JPH081732A - Detecting method of starting timing of post-processing in injection molding machine - Google Patents

Abstract

PURPOSE:To obtain swiftly and reliably starting timing of post-processing suitable for the desirous post-processing, by a method wherein the starting timing of the post- processing at the time when lowering of set resin reaction force is detected first is obtained and the same is set up to an injection molding machine as the optimum post-processing timing. CONSTITUTION:An injection molding machine is constituted so that after molds 3, 4 are filled with a resin, post-processing is applied to the resin within the molds 3, 4 by driving a moving member 8 within the molds 3, 4. Molding operation and the post processing are performed by quickening starting timing TO of the post-processing every molding cycle by fixed notch widths DELTAt1, DELTAt2. Then mean resin reaction force corresponding to the timing is obtained by detecting the resin reaction force acting upon the moving member 8 performing the post-processing every timing. Hereby, operation obtaining a solidified condition of the resin is performed in order by changing the foregoing timing. Then the solidified condition of the resin at the each timing is obtained, through which the starting timing of the post-processing corresponding to the solidified condition of the resin suitable for the desirous post-processing treatment is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a post-processing start timing detecting method in an injection molding machine.

[0002]

2. Description of the Related Art A moving member for gate cutting is provided in a mold, and after completion of injection, the resin in the mold is driven in an appropriately solidified state to drive the gate to cut the molded product before starting the mold opening. Also, by providing a moving member for pressure application inside the mold and driving this at an appropriate timing after completion of injection, pressure is applied to the resin in the mold to prevent sinking of the molded product. The post-processing technology of an injection molding machine which is designed to do so is known.

When post-processing the gate cut, if the timing of driving the moving member is too early, the resin will not be sufficiently solidified, resulting in incomplete cutting of the gate. If the timing is late, the gate will be cut. Although the process itself can be performed accurately, there is a problem that the waiting time until the start of post-processing becomes long, the molding cycle is increased, and the productivity is deteriorated. On the other hand, when the moving member is driven and pressure is applied to prevent sink marks, if the timing of driving the moving member is late, the resin will solidify more than necessary, so the pressure inside the mold will not be properly applied. Cannot be applied, and if the timing is too early and the moving member is moved to the stroke end by performing this operation before the gate sealing is completed, the moving member is driven after the gate sealing is completed. There is a problem that pressure cannot be applied to the resin.

In order to solve these problems, it is necessary to accurately know the solidified state of the resin and set the start timing of the post-processing, but so far, the solidified state of the resin in the mold has to be appropriate. There is no means to detect it accurately, and the timing is set by trial and error depending on the intuition of the operator. Therefore, it takes a considerable amount of time to find an appropriate start timing for the post-processing, and the mold may be released from the mold due to the failure of the gate cutting while the post-processing continues to be defective, or the mold may be pinched. There is also a risk that the molding material and work time will be wasted due to damage to the product or continuous sink marks.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an injection molding machine which solves the above-mentioned drawbacks of the prior art and can promptly and surely obtain a post-processing start timing suitable for desired post-processing. It is to provide a method for detecting a post-processing start timing.

[0006]

According to the present invention, by shifting the timing for each molding cycle and driving a moving member for post-processing to detect a resin reaction force acting on the moving member, the timing at each timing is detected. Detects the solidification state of the resin,
The above object is achieved by a configuration characterized in that a post-processing start timing corresponding to a solidified state of a resin suitable for a desired post-processing treatment is obtained.

Further, in the post-processing start timing detecting method according to one embodiment, the timing at which the resin is completely solidified is set in the injection molding machine as an initial value of the post-processing start timing, and the post-processing start timing is advanced. The time step width is set in advance in the injection molding machine, the post-processing start timing is advanced by the time step width for each molding cycle, and the continuous molding operation and post-processing operations are performed to reduce the set resin reaction force. The same object was achieved by detecting the post-processing start timing in the molding cycle in which is first detected.

Further, every time a molding cycle in which the set resin reaction force decrease is first detected is obtained, the post-processing start timing in the molding cycle one cycle before the molding cycle is reset as a new initial value, The post-processing corresponding to the solidified state of the resin suitable for the desired post-processing is performed by resetting the time step width for accelerating the post-processing start time to a shorter time and repeating the same processing for the set number of times. Made the start timing more accurate.

Further, instead of changing the post-processing start timing for each molding cycle, the post-processing is performed at the same timing over a plurality of molding cycles to obtain the average value of the resin reaction force acting on the moving member, and then the timing is changed. By offsetting the fluctuations of the disturbance that affect the detection of the resin reaction force, the post-processing start timing corresponding to the solidified state of the resin suitable for the desired post-processing can be obtained more precisely. I did it.

[0010]

Function: The timing at which the resin is completely solidified is set in the injection molding machine as the initial value of the post-processing start timing, and the time step width for advancing the post-processing start timing is set in the injection molding machine. The injection molding machine performs the continuous operation of molding work and post-processing by advancing the post-processing start timing by the step size of each time in each molding cycle, and in the molding cycle in which the decrease of the set resin reaction force is first detected. The post-processing start timing is detected. Hereinafter, the injection molding machine renews the post-processing start timing in the molding cycle one cycle before the molding cycle, whenever a decrease in the resin reaction force set based on the initially detected resin reaction force is detected. The initial setting value is set again, the time step size for accelerating the post-processing start timing is reset to a shorter time, and the same processing is repeatedly executed for the set number of times to solidify the resin suitable for the desired post-processing. The post-machining start timing corresponding to the state is precisely obtained.

Since the solidified state of the resin is detected by detecting the reaction force of the resin acting on the moving member, the solidified state of the resin at various start timings of the post-processing can be accurately known, and the desired post-processing can be performed. The post-processing start timing corresponding to the solidified state of the resin suitable for processing can be easily selected. In addition, the timing at which the resin is completely solidified is set as the initial value of the post-processing start timing, and the timing is gradually changed only in the direction of advancing the post-processing start timing, and the molding operation and the post-processing continuous operation are performed appropriately. Since the post-machining start timing is detected, the post-machining start timing can be compared with the case where the optimum machining start timing is detected by performing trial and error timing setting without specifying the directionality that shifts the timing. The time required for detection can be shortened. Furthermore, every time a decrease in the resin reaction force set with the initially detected resin reaction force as the reference is detected, the post-processing start timing in the molding cycle one cycle before the molding cycle is returned to,
Since the optimum time for starting post-machining is detected by shortening the time with a shorter time width, it is possible to detect the optimum time for starting post-machining by changing the timing at a slight time interval from the beginning. The time required for timing detection is shortened, and moreover, the optimum post-machining start timing is sufficiently precise as in the case where the timing is changed from the beginning at a slight time interval to detect the optimum post-machining start timing. Can be detected. Further, since the post-processing is performed at the same timing over a plurality of molding cycles to obtain the average value of the resin reaction force acting on the moving member, the influence of fluctuating disturbance is removed and the solidified state of the resin is more suitable. The post-processing start timing corresponding to the solidified state of the resin suitable for the desired post-processing can be detected more accurately and can be obtained more accurately.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of main mechanical parts of an injection molding machine according to an embodiment and a main part of a control system of the injection molding machine. In FIG. 1, only the periphery of the ejector mechanism is shown, but the other shafts, such as the injection shaft, the screw rotation shaft, the mold clamping shaft, and the mold thickness adjusting shaft, are the same as those of the conventional electric injection molding machine. It is the same. First, a brief explanation will be given. In FIG. 1, reference numeral 1 is an injection cylinder of an injection molding machine, reference numeral 4 is a fixed side mold attached to a fixed platen of the injection molding machine, and reference numeral 3 is a movable platen of the injection molding machine. It is a movable die attached (collectively referred to as a die), and a product shape is formed by a cavity 5 formed in a gap between the fixed die 4 and the movable die 3. As in the conventional case, the molten resin injected from the injection cylinder 1 flows into the runner 6 engraved between the fixed side mold 4 and the movable side mold 3 via the sprue bush 9 of the fixed side mold 4. Then, it enters the cavity 5 through the gate portion 7 that connects the cavity 5 and the runner 6.

A movable member 8 for gate cutting made of a rod material or the like is slidably provided on the movable mold 3 in correspondence with the position of the gate portion 7, and a base portion of the movable member 8 is slid. The tip of the moving member 8 is adapted to be projected and retracted in the gate portion 7 in the mold in association with the contact and separation operation of the board 2 with respect to the movable mold 3. The protrusion limit of the moving member 8 is finally the fixed side mold 4
Of the moving member 8 comes into contact with the parting surface of the fixed-side mold 4 and is in a push-cut state, the resin of the gate portion 7 is completely sheared and the post-processing is performed. Gate cutting work is completed.

In the case of this embodiment, since the sliding board 2 is driven by the ejector rods provided as standard equipment on the movable platen, further ejector pins are arranged and stripper plates are continuously arranged. If the ejector plate is to be driven by the ejector rod to perform the final product release work, some measures must be taken. The gate cutting work performed by driving the moving member 8 needs to be performed with the molds 3 and 4 closed, whereas the product release work performed by driving the ejector pins and the like opens the molds 3 and 4. This is because it is necessary to perform the operation after the ejector rod, and if the sliding board 2 and the ejector plate simultaneously follow the operation of the ejector rod, it becomes impossible to perform both the gate cutting work and the product releasing work without any trouble. . However, as a person skilled in the art can easily assume, such a problem can be easily solved by the following method.

The simplest way is to construct the slide board 2 and the ejector plate separately and to drive them substantially independently by a single ejector rod. For example, the ejector plate is arranged relatively close to the back surface of the movable die 3 and a return spring for urging the ejector plate is interposed between the back surface of the movable die 3 and the ejector plate to eject the ejector pin. Urges the ejector plate in a direction in which the movable mold 3 is retracted from the parting of the movable mold 3, and further restricts the separation limit of the ejector plate from the movable mold 3 with a mechanical stopper. Further, the sliding plate 2 is arranged so that the sliding plate 2 is superposed on the ejector plate at a certain distance in the direction away from the ejector plate, and the sliding plate is attached to the tip of the ejector rod in the retracted state. Install 2.

According to this structure, the ejector rod is expanded and contracted in a predetermined range from the retracted state, that is, until the sliding plate 2 contacts the ejector plate,
With the molds 3 and 4 closed, only the moving member 8 can be driven to perform the gate cutting work.
If the ejector rod is projected beyond the range in the state where 4 is opened, it is possible to drive the ejector plate which overlaps with the sliding board 2 to perform the product releasing work by the ejector pin or the like. With this configuration, the moving member 8 considerably projects at the stage of product release work, but at this stage, the movable side mold 3 is already at the mold opening completion position or the position during the mold opening operation. Since there is nothing that prevents the moving member 8 from protruding, no particular problem occurs. Naturally, it is necessary to separately set the ejector rod protrusion stroke for gate cutting work and the ejector rod protrusion stroke for product demolding work, but such setting and control is performed by a numerical controller or a servo. This is easy in an injection molding machine equipped with a motor. M in FIG. 1 is a servomotor for an ejector shaft, which is provided as a standard on a movable platen of an injection molding machine, for controlling the amount of protrusion of an ejector rod, and includes a pulse coder P as position detecting means. Instead of directly attaching the sliding board 2 to the ejector rod on the movable platen side, it is possible to use the same return spring specifications as in the case of the ejector plate, and only the ejecting operation of the moving member 8 can be performed by the ejector rod. When the resin reaction force acting on the moving member 8 during the gate cutting work is detected by the drive current flowing through the servo motor M or the observer output, in order to reduce the proportion of unintentional load fluctuation in the whole, Elements such as springs that cause disturbance should be eliminated.
Of course, with the above arrangement, the return spring of the ejector plate is not compressed during the gate cutting operation.

The simplest structural example in which the moving member 8 for the gate cutting work and the ejector pin for the product releasing work are driven by the single servo motor M has been described above. It is also possible to appropriately operate the mechanical elements and the mechanics of the above, and to adopt another configuration. Furthermore, by providing another motor or a servo motor that drives only the moving member 8, The ejector pins and the like may be driven completely independently.

Numerical control device 1 for driving and controlling an injection molding machine 1
Reference numeral 0 denotes a CNC CPU 25 which is a numerical control microprocessor, a PMC CPU 18 which is a programmable machine controller microprocessor, a servo CPU 20 which is a servo control microprocessor, and a pressure monitoring CPU 17, and a bus. Information can be transmitted between the microprocessors by selecting mutual input / output via 22. In addition,
The pressure monitoring CPU 17 is a monitoring CPU for performing a sampling process of the injection holding pressure and the screw back pressure via the A / D converter 16 and the pressure detector on the injection screw side (not shown). As far as the example is concerned, it is irrelevant to the configuration for detecting the resin reaction force acting on the moving member 8.

The PMC CPU 18 is connected to the ROM 13 which stores a sequence program for controlling the sequence operation of the injection molding machine and the RAM 14 which is used for temporary storage of operation data. The CNC CPU 25 is connected to the entire injection molding machine. R storing a program for controlling the program
R used for temporary storage of OM27 and operation data
AM28 is connected.

Further, each of the servo CPU 20 and the pressure monitoring CPU 17 has a ROM 21 storing a control program dedicated to servo control, a RAM 19 used for temporary storage of data, and a control program relating to the above-mentioned pressure data sampling processing and the like. ROM that stores
11 and a RAM 12 used for temporary storage of data are connected. Further, the servo CPU 20 has the CPU 2
Based on a command from 0, a servo amplifier 15 for driving a servo motor (not shown) for each axis for mold clamping, injection, screw rotation, etc. and a servo motor M for an ejector axis is connected, and Each of the outputs from the pulse coder provided to the axis servo motor is fed back to the servo CPU 20, and the current position and movement speed of each axis calculated by the servo CPU 20 based on the feedback pulse from the pulse coder are stored in the current position storage register of the RAM 19 and At present, each of the speed storage registers is sequentially updated and stored. Further, in the present embodiment, an observer 60 for estimating the load torque acting on the servomotor M for the ejector shaft is incorporated, and the present value Td2 of the load torque estimated by the observer 60 is successively read by the load torque of the RAM 19. It is adapted to be updated and stored in the storage register.

FIG. 8 is a schematic view of the structure of an observer 60 for detecting a load torque acting on the servomotor M for the ejector shaft, that is, a value which is a resin reaction force acting on the moving member 8 during the gate cutting work. It is a functional block diagram showing. In FIG. 8, u is a torque command obtained by the speed loop processing of the servo CPU 20, elements 52, 5
3 is an element of the transfer function of the servomotor M, which is K of the element 52.
t is the torque constant of the servomotor M, J is the inertia, and S is the Laplace operator. Also, the elements 61, 65
"B" is the estimated ratio of the torque constant Kt of the servomotor M and the inertia J, that is, the estimated value of (Kt / J). Further, K1 and K2 of the elements 62 and 63 are parameters of this observer 60, S is a Laplace operator, and element 6
Reference numeral 4 represents an integral element. When the block diagram of the observer 60 of FIG. 8 is analyzed with b = Kt / J, finally, Td2 = Td1. (1 / b) = (Td / J). (J / Kt)
= (Td / Kt) and the estimated value Td of the load torque Td (proportional to it)
2, that is, the value obtained by calculating the load torque Td in units of the torque command (current command) is obtained (if Td is divided by the torque constant, the same dimension as the torque command u is obtained).

In this way, the load torque Td applied to the motor M is obtained by the processing of the observer 60 for each predetermined cycle (processing cycle of the position / speed loop processing) performed by the servo CPU of the servomotor M for the ejector axis. Member 8
The resin reaction force acting on is measured and sequentially written in the RAM 19. The substantial processing operation by the servo CPU 20 is described in detail in the patent application of the method for measuring the mold internal pressure submitted by the present applicant on May 2, 1994, so the detailed description will be omitted. As another embodiment, the drive current of the ejector shaft servomotor M is directly detected, and the resin reaction force acting on the moving member 8 by directly attaching a pressure detector to the moving member 8 or the sliding board 2 is used. It is also possible to detect.

The interface 23 is an input / output interface for receiving signals from limit switches and operation panels provided in various parts of the injection molding machine and for transmitting various commands to peripheral equipment of the injection molding machine. is there. A manual data input device 29 with a display is connected to the bus 22 via a CRT display circuit 26 so that a monitor display screen, a function menu can be selected and various data input operations can be performed. Also, various function keys and the like are provided.

The non-volatile memory 24 is a memory for storing molding data for storing molding conditions (injection pressure holding condition, metering and kneading condition, etc.) and various set values, parameters, macro variables and the like related to injection molding work.

With the above configuration, the PMC CPU 18 controls the sequence of the entire injection molding machine, while the CNC CPU 25 distributes the pulses to the servo motors of the respective axes based on the control program of the ROM 27, and the servo CP.
U20 is a position loop control, speed loop control, current loop similar to the conventional one based on the movement command distributed to each axis, the position feedback signal detected by a detector such as a pulse coder, and the speed feedback signal. Control and servo control such as observer processing are performed, and so-called digital servo processing is executed.

The method for detecting the post-machining start timing in this embodiment will be described below based on the above-mentioned configuration. In this embodiment, the initial value of the post-processing start timing is delayed in advance by at least the elapsed time from the start of pressure holding (injection completion), that is, the elapsed time based on the completion point of resin filling (at least when the resin is completely The required time until solidification is set) and the post-machining start timing is gradually increased to automatically obtain the optimum post-machining start timing for the gate cutting work. The time step size for speeding up the process is automatically switched in two steps from long to short in order to detect a more suitable post-processing start timing. Initial value of machining start timing or time step width Δt1 (long), Δt for advancing the timing
Each of 2 (short) is stored in the non-volatile memory 24 in advance.

Further, as a method for detecting the resin reaction force (load torque Td2) acting on the moving member 8 during the gate cutting work and specifying the solidified state of the resin, the moving member 8 moves and the stroke section Method for sampling the load torque Td2 when reaching the predetermined position to represent the resin reaction force Ra acting on the moving member 8 during the gate cutting work, and a predetermined time has elapsed since the moving member 8 started moving. The load torque Td2 at this time is sampled to represent the resin reaction force Ra acting on the moving member 8 during the gate cutting work (in this case, of course, the predetermined time is set shorter than the total stroke moving time of the moving member 8). According to the average value of the load torque Td2 detected while the moving member 8 moves from the first predetermined position set on the stroke section to the second predetermined position. Method for representing the resin reaction force Ra acting on the moving member 8 during the gate cutting work, and detecting while the moving member 8 moves from the first predetermined position set on the stroke section to the second predetermined position. Method for representing the resin reaction force Ra acting on the moving member 8 during the gate cutting operation by the maximum value of the applied load torque Td2, the second from the time when the moving member 8 starts moving and the first predetermined time elapses. Method in which the resin reaction force Ra acting on the moving member 8 during the gate cutting work is represented by the average value of the load torque Td2 detected until the predetermined time elapses (in this case, of course, the first and second predetermined values). Time is moving member 8
Of the maximum load torque Td2 detected from the time when the first predetermined time elapses after the moving member 8 starts moving until the second predetermined time elapses. A method of representing the resin reaction force Ra acting on the moving member 8 during the gate cutting work by the value (in this case, the moving member 8 is naturally used for the first and second predetermined times.
Set shorter than the total stroke movement required time).

[0028] Of these, what is selected to represent the solidified state of the resin is arbitrary, and depending on the mold structure, the characteristics of the resin, etc., the selection may be changed as necessary. Therefore, in the present embodiment, in order to satisfy such a need, the elapsed time i.
t0 (t0 = sampling cycle of load torque Td2, i =
0, 1, 2, 3, ...), and a file means (FIG. 6) for storing the position Pn of the moving member 8 and the resin reaction force Rn (Rn = load torque Td2) at that time in correspondence with 0, 1, 2, 3 ,.
(See (a)) is provided in the RAM 14. Further, although a sub-program (corresponding to step S14 of the process described later) for selectively carrying out each of the above-mentioned methods (1) to obtain the resin reaction force Ra indicating the solidified state is stored in the ROM 13, Regarding the processing for searching other data by referring to the value of the specific data type of, and obtaining the average value or the maximum value, it is already known in the peripheral technology related to the computer, so the content itself Will not be explained.

2 to 5 are flowcharts showing the outline of the post-processing start timing detection processing in this embodiment. This processing is performed by the injection molding operation for obtaining the post-processing start timing for the gate cutting work. While being seen
It is repeatedly executed by the PMC CPU 18 each time the start of the holding pressure is confirmed, and includes the protrusion control of the moving member 8 for the gate cutting work. When the processing start timing detection process is completed after this, the PMC CPU
18 returns to the normal sequence control similar to the conventional one,
The sequence control after mold opening is continuously performed in the same manner as the conventional one.

Therefore, the PMC CPU 18 which has confirmed the start of the holding pressure and started the post-processing start timing detection processing,
First, the time required from the start of pressure holding until the resin is completely solidified is set as the initial value of the waiting time T0 by the timer T.
(Step S1), measurement of the elapsed time by the timer T is started (step S2), and the process waits until the set time T0 elapses, that is, until the resin in the mold is completely solidified ( In step S3), a rod movement start command is output to the CPU 25 for CNC, driving of the ejector shaft servomotor M is started, and gate cutting work by the projecting operation of the moving member 8 is started (step S4).

Next, the PMC CPU 18 sets an initial value 0 to the index i used for designating the address of the above-mentioned file means (step S5), resets the sampling cycle t0 to the timer T, and sets the elapsed time. Measurement is started (step S6, step S7), and the resin reaction force Rn
The current value of (Rn = load torque Td2) and the current position Pn of the moving member 8 are transferred to the RAM 19 via the servo control CPU 20.
Read from the file means (see FIG. 6A) and stored in the storage areas R (i) and P (i) of the address i (steps S8 and S9), and the current position Pn of the moving member 8 is the final target. It is determined whether or not the position has been reached (step S10). Needless to say, the final target position referred to here is a value corresponding to the ejection stroke of the ejector rod for the gate cutting work. Moving member 8
If the current position Pn of P has not reached the final target position, P
The MC CPU 18 increments the value of the index i by 1 (step S11), waits until the set time of the timer T elapses, that is, until one sampling period elapses (step S12), and returns to the process of step S6. Then, the same processing as described above is repeatedly executed.

As a result, a predetermined sampling period t from the start of the gate cutting work by the protruding operation of the moving member 8
For each 0, the resin reaction force Rn acting on the moving member 8 at that time and the position Pn of the moving member 8 are sampled,
The data is sequentially written in the file means.

While the above processing is repeatedly executed, the position Pn of the moving member 8 reaches the final target position, the tip of the moving member 8 abuts the parting surface of the stationary mold 4, and the gate portion 7 moves. When it is confirmed that the resin has been completely sheared (step S10), the PMC CPU 18 sets the CNC C
A rod return command is output to the PU 25 to cause the ejector shaft servomotor M to rotate in the reverse direction to return the moving member 8 to the original position in the retracted state to end the gate cutting work (step S13). ~
The subprogram is executed according to any one of the above methods to obtain the representative value Ra of the resin reaction force acting on the moving member 8 during the gate cutting work (step S14).

Next, the PMC CPU 18 determines whether or not the current value of the determination reference value storage register R is 0 (step S15), but at the present stage immediately after the start of the injection molding work for obtaining the post-processing start timing. In the above, since the value of the discrimination reference value storage register R is held at the initial value 0, the discrimination result of step S15 is inevitably true. Therefore, the PMC CPU 18 uses the resin reaction force R calculated this time.
a, that is, a discrimination reference value is obtained with the value of the resin reaction force Ra detected in the first gate cutting work after the injection molding work for obtaining the post-processing start timing as a reference, and the value is the discrimination reference value storage register. The data is updated and stored in R (step S16). Discrimination reference value R updated by this process
Is the resin reaction force Ra detected in the first gate cutting work.
Can be obtained as a value obtained by subtracting the set value α of the resin reaction force corresponding to the maximum allowable range of resin hardness reduction that allows appropriate gate cutting. As already described in the section of the prior art, when post-processing the gate cut, there is a problem that the cutting of the gate is incomplete if the resin is not sufficiently solidified. Therefore, in the case of this embodiment, the driving force of the moving member 8 required to shear the resin completely solidified by the above-mentioned treatment, that is, the resin actually acting on the moving member 8 when the completely solidified resin is sheared The reaction force Ra is first obtained, and by subtracting the set value α from the value, the resin reaction force R corresponding to the lower limit of the hardness of the resin capable of appropriately performing the gate cut, that is, the determination reference value. Find R. In this case, needless to say, the set value α corresponds to a decrease in the set resin reaction force.

PMC CPU 18 for determining the discrimination reference value R
Next, while setting the larger step size setting value Δt1 in the step size storage register ΔT that stores the step size of the time for advancing the post-processing start timing (step S17), the value of the waiting time T0 is set. By updating the setting to T0-ΔT, the waiting time for the gate cutting work in the next molding cycle is shortened (step S19), the post-machining start timing detection process of this cycle is finished, and the normal sequence control is resumed. The sequence control after the opening is continuously performed as in the conventional case, and when the sequence control for one molding cycle is completed, the sequence control for the next molding cycle is started.

When it is confirmed that the holding pressure is started again,
The PMC CPU 18 starts the post-machining start timing detection process in the same manner as described above. Step S in the previous cycle
Since the update setting work related to the waiting time T0 is performed in the process of 19, the gate cutting work started by the output of the rod movement start command is naturally at a timing ΔT (= Δt1) earlier than the previous molding cycle. Will be started. Hereinafter, the PMC CPU 18 repeatedly executes the same processing as described above to obtain the value of the resin reaction force Ra that has acted on the moving member 8 during the current gate cutting work (above, step S1 to step S14). .

The PMC CPU 18 which has obtained the value of the resin reaction force Ra acting on the moving member 8 during the current gate cutting work.
Then, it is determined whether or not the current value of the discrimination reference value storage register R is 0 (step S15), but the discrimination reference value of R> 0 has already been set in the discrimination reference value storage register R. Therefore, the determination result of step S15 becomes false, and the PMC CPU 18 determines that the resin reaction force R obtained this time is R.
Whether or not the value of a is below the discrimination reference value R, that is,
It is determined whether the hardness of the resin is lower than the range in which the gate cut can be appropriately performed (step S18). If the value of the resin reaction force Ra is equal to or greater than the determination reference value R, it is possible to perform the normal gate cutting work even if the waiting time for starting the gate cutting work is set to be shorter to lower the hardness of the resin. Because it means that
The PMC CPU 18 waits for the waiting time T0 in the same manner as described above.
Is shortened to T0-ΔT (ΔT = Δt1) (step S19), and the post-machining start timing detection process of this cycle is ended.

Then, while the injection molding work and the gate cutting work accompanying it are repeatedly executed in this way, the value of the waiting time T0 is finally shortened more than necessary, and the post-processing start timing detection processing is performed. When the result of the determination in step S18 in step 3 is true (when the set decrease in the resin reaction force is first detected).

For example, as shown in FIG. 7 (b), a waiting time T0 having a required time required from the start of holding pressure to the complete solidification of the resin as an initial value is divided by a step width ΔT (= Δ
If it is gradually shortened at t1), then at some point (Fig. 7 (b))
In the above example, the value of the resin reaction force Ra becomes smaller than the determination reference value R at T0 ₅ ) and the hardness of the resin becomes lower than the range in which the gate cut can be appropriately performed. Since the gate cutting work can be appropriately performed only when the value of the resin reaction force Ra is larger than the determination reference value R, Δ
When the step size of T (= Δt1) is large, naturally, Ra
Wait time T0 when <R (Fig. 7 (b)
In the above example, it is not appropriate to select T0 ₅ ) as the waiting time of the post-processing start timing, and the value of T0 when the value of the resin reaction force Ra agrees with the determination reference value R (gate cut properly If the step width ΔT (= Δt1) is set too short in order to exactly detect the minimum value of the waiting time T0 within the feasible range, a considerable number of times will be required until the optimum waiting time T0 is detected. The molding cycle must be repeated and time is wasted. In order to solve such a problem, the step width (Δt
After the waiting time is shortened in 1) and T0 that Ra <R is obtained, the step width ΔT is reset to a shorter value (Δt2), and the phenomenon in which Ra <R occurs is detected. It is rational to strictly detect the change in Ra only in the vicinity and obtain the value of T0 when the value of the resin reaction force Ra substantially coincides with the discrimination reference value R. When the waiting time is shortened by the rough step width ΔT (= Δt1), it is difficult to predict in advance when the phenomenon that Ra <R will occur.
After the time when Ra <R is actually detected by the rough step size (Δt1), the standby time of the previous cycle satisfying the condition of Ra> R is returned, and the standby time is set as the initial value and the small step size ΔT is set. The value of T0 when the value of the resin reaction force Ra substantially agrees with the determination reference value R is obtained by shortening the waiting time little by little by (= Δt2) and repeating the same processing.

Therefore, when it is detected from the determination result of step S18 that the value of the resin reaction force Ra is below the determination reference value R, the PMC CPU 18 first determines whether or not the switching completion flag F is set. That is, it is determined whether or not the work of switching the step width ΔT is completed (step S20). Since the flag F is in the unset state at the initial stage, naturally the determination result when the process of step S20 is first performed is true. So CP for PMC
U18 resets the smaller step size setting value Δt2 in the step size storage register ΔT (step S21), and adds the value of Δt1−ΔT (ΔT = Δt2) to the current value of the waiting time T0, The waiting time in the previous molding cycle (the waiting time that allows adequate gate cutting, which corresponds to T0 ₄ in the example of FIG. 7B) is shortened by ΔT (ΔT = Δt2). After the waiting time is calculated and updated and set as the waiting time T0 in the next molding cycle (step S22), the switching completion flag F is set.
Is set (step S23), and the post-machining start timing detection process of this cycle ends. The waiting time T0 set at this time is a new initial value when the waiting time is shortened by the step size Δt2. Then PMC CPU1
8 returns to the normal sequence control, continues the sequence control after the mold opening as in the conventional method, and when the sequence control for one molding cycle is completed, starts the sequence control for the next molding cycle. To do.

Then, when the start of the holding pressure is confirmed again,
The PMC CPU 18 starts the post-machining start timing detection process in the same manner as described above, but of course the update setting work regarding the standby time T0 is performed in the processes of steps S21 and S22 in the previous cycle, so naturally the rod movement start The gate cutting work that starts with the output of the command is ΔT compared to the waiting time of the previous molding cycle, that is, the waiting time when it is possible to properly perform the gate cutting.
It will be started at a slightly earlier timing by (= Δt2). Hereinafter, the PMC CPU 18 repeatedly executes the same processing as described above to obtain the value of the resin reaction force Ra applied to the moving member 8 during the current gate cutting work (above, step S1 to step S14), step S15. After performing the determination process of No., it is determined whether the value of the resin reaction force Ra obtained this time is less than the determination reference value R (step S18). If the value of the resin reaction force Ra is greater than or equal to the determination reference value R, it is possible to set the waiting time for starting the gate cutting work even shorter, so the PMC CPU 18 sets the value of the waiting time T0 in the same manner as described above. To T0-ΔT (ΔT = Δ
The time is shortened to t2) (step S19), the post-processing start timing detection process of this cycle is ended, and thereafter, the injection molding work and the gate cutting work associated therewith are repeatedly executed in the same manner as described above.

Then, while the injection molding work and the gate cutting work accompanying it are repeatedly executed in this way, the determination result of step S18 becomes true again,
A time point T0 at which the value of the resin reaction force Ra falls below the determination reference value R is detected (corresponding to time data at point A in the example of FIG. 7B). Then, the PMC CPU 18 determines again whether or not the switching completion flag F is set (step S20). In this case, however, since the switching completion flag F has already been set, the determination result of step S20 is false. Become. This is the waiting time T that is sufficiently close to the minimum waiting time in the range in which the gate cut can be appropriately performed.
0 means that a minute step width by Δt2 is detected as a unit, and there is no obstacle to using the waiting time T0 at this time as the optimum post-machining start timing for the gate cutting work. Absent. Therefore,
The PMC CPU 18 waits for the waiting time T0 at this point.
The present value of is displayed on the manual data input device with display 29 as the optimum post-machining start timing for the gate cutting work to inform the operator, and the value is saved as the post-machining start timing (step S24), and the subsequent processing is performed. It is applied as the waiting time for gate cut work. Once the waiting time T0 is fixed, it is not necessary to obtain it again. Therefore, in the subsequent processing cycles, the waiting processing of steps S1 to S3 and the output of the gate cutting work start command of step S4, and the step S4 are performed.
It suffices to perform only the waiting process for waiting for the completion of the gate cutting work corresponding to 10 and the returning process of the moving member 8 in step S13.

Strictly speaking, although Ra <R has already been satisfied when the final T0 is obtained (corresponding to the reaction force data at point A in FIG. 7B), Δt2
In view of the fact that the step size of Δ is sufficiently small and that the hardness of the resin does not fluctuate significantly due to a slight difference in the cooling time, it is possible that the optimum waiting time may occur with Δt2 as the upper limit. The error of can be ignored. If this point is inevitable, the value obtained by adding Δt2 to the value of T0 finally obtained is added to the optimum waiting time T by the same method as in step S19 described above.
It is set to 0 and saved in the process of step S24,
It suffices to satisfy the wording condition regarding T0 of "the minimum value of the waiting time within the range in which the gate cut can be appropriately performed".

Contrary to the above-mentioned embodiment, it is theoretically possible to obtain the optimum post-machining start timing T0 by setting the initial value of the waiting time T0 to be short and gradually extending it. In that case, there is a high possibility that a defective gate cut will occur in the product molded by the time when the optimum post-processing start timing T0 is detected, and the mold or the injection caused by the defective mold release or the like. In order to prevent damage to the molding machine, it becomes necessary for the operator to monitor the injection molding machine on a continuous basis. Therefore, when obtaining the post-processing start timing for gate cutting work,
Set the waiting time with the required time required for the resin to completely solidify or a longer time (especially when the required time for complete resin solidification is unknown) as the initial value However, it is the most rational method to shorten the time required for the molding cycle by shortening this as much as possible (of course, post-processing other than gate cutting, for example,
Other methods may be more rational when determining the timing for starting post-processing for post-processing such as sink prevention).

Further, in the above-mentioned embodiment, the resin reaction force when shearing the completely solidified resin is used as a reference, and from this reference value, the maximum allowable range of the decrease in the hardness of the resin that can be appropriately gate-cut is obtained. Although the determination reference value R is obtained by subtracting the set value α of the corresponding resin reaction force, the determination reference value R
If the value of is known, the value may be set in the control device 10 as the determination reference value R from the beginning.

The set value α of the resin reaction force corresponding to the maximum permissible range of the resin hardness reduction that can appropriately perform the gate cut differs depending on the type of the resin, the gate diameter, etc. It is not always easy to accurately obtain it beforehand. However, generally speaking, regarding the relationship between the cooling time and the solidified state of the resin, as shown in the example of FIG. 7B, if the cooling time is gradually increased, the resin will follow the cooling time. Although the hardness gradually increases, there is a limit point that the hardness of the resin does not increase even if the cooling time is extended beyond a certain point, so by setting the value of α as a relatively small value Good results can be obtained. A straightforward example is when the initial waiting time is set to be considerably longer than the time required for complete curing of the resin. In this case, the waiting time after the resin is completely cured is completely wasted, and it has an adverse effect of extending the molding cycle, but the setting value α is set to a severe value to perform the processing of the above-described embodiment. For example, the waiting time required for the complete curing of the resin can be accurately detected, and all the unnecessary waiting time after the complete curing can be omitted. Of course,
It is permissible to set the value of α to a relatively large value for those that do not interfere with the gate cutting work before the resin is completely cured.

Further, in the above-mentioned embodiment, the resin reaction force Ra is obtained each time one molding cycle and post-processing are completed, and the value is compared with the determination reference value R to determine the solidified state of the resin. Although the waiting time T0 was shortened according to the result, the resin reaction force Ra was measured each time several molding cycles and post-processing were performed in a state where the waiting time T0 was not changed, and the molding was performed several times. The average value of the resin reaction force Ra obtained by the cycle and the post-processing may be obtained and compared with the determination reference value R, and the waiting time T0 may be shortened according to the determination result. In this way, the resin reaction force Ra is sampled a plurality of times during the standby time under the same condition and the average value is obtained, whereby the influence of fluctuating disturbance can be removed and the solidified state of the resin can be determined more accurately.

Such processing can be easily implemented by adding some steps to the processing of the above-described embodiment as shown in FIGS. As an example, an example in which N molding cycles and post-processing are performed with the same waiting time to obtain the average of the resin reaction forces Ra1 to RaN will be described.

In this case, first, step S of the above embodiment.
Before 1, the counter j having an initial value of 0 is incremented by 1 (step s01), the process of determining whether the value of the counter j matches N (step s02), the value of the counter j is set to N. If they match, a process of resetting the counter j to 0 (step s03) is inserted. If it is determined in the process of step s02 that the value of the counter j does not match N, and the process of step s03 is completed. In this case, the processing after step S1 of the embodiment is started, and in the processing of step S14, after the value of the resin reaction force Ra is obtained in the same manner as in the embodiment, the value is further stored in the register Ra (j). To be stored (however, j = 0 to
N-1).

Therefore, the resin reaction force Ra obtained in the first post-processing with the same waiting time is stored in the register Ra (1),
Similarly, the resin reaction force Ra obtained in the second post-processing with the same waiting time is in the register Ra (2), and the resin reaction force Ra obtained in the third post-processing with the same waiting time is in the register Ra.
Is stored in (3), and the resin reaction force Ra obtained by the last post-processing with the same waiting time, that is, the N-th post-processing with the same waiting time is stored in the register Ra (0). It will be.

Therefore, further, step S1 of the above embodiment.
4 and the process of step S15, the counter j
Is inserted (step s04), and if the value of the counter j matches 0, [Ra (1) + Ra (2) + Ra (3) +.・ ・ ＋
Ra (N-1) + Ra (0)] / N is executed to obtain the average value Ra of the resin reaction force and stored in the register Ra (step s05), and then step S1 of the above embodiment.
While executing the processing of 5 and subsequent steps, step s
When it is determined in the determination processing of 04 that the value of the counter j does not match 0, step s05 and step S
The processing after 15 is canceled and the post-processing start timing detection processing of the cycle is ended.

As a result, N molding cycles and post-processing are performed with the same waiting time, and at the time of the completion of the last post-processing, the average value R of the resin reaction force in the N post-processings up to that time
a is obtained, and it is judged whether the waiting time is shortened or the detection of the optimum timing is completed according to the relationship between the average value Ra and the discrimination reference value R.

As described above, the controller 1 automatically obtains the optimum waiting time which is the timing for starting the processing after the gate cutting work.
Although one embodiment in which the automatic standby time is set to 0 has been described, data for determining the optimal standby time may be displayed on the manual data input device 29 with a display, and the optimal standby time may be determined by the operator's judgment. . For example, step S1 to step S in the above embodiment
14 and step S19 are repeatedly performed, and the relationship between the post-processing start timing (waiting time from the start of holding pressure to the start of gate cutting) T0 and the resin reaction force Ra in each molding cycle is shown in FIG. 7 (a). If the file is stored in a different file means and is displayed as a graph on the display-equipped manual data input device 29 as in the example of FIG. 7B, the operator refers to this graph display to determine the optimum post-processing start timing. It is possible to obtain T0. In this case, it is possible to directly visually check the relationship between the post-processing start timing and the resin solidification state (resin reaction force). Therefore, the maximum allowable range of resin hardness reduction that allows proper gate cutting. Even if you do not understand (α above), due to the change in the slope of the graph,
It is possible to relatively easily detect the minimum value of the waiting time that can appropriately perform the gate cut. Further, at this time, instead of the automatic shortening process of the waiting time as seen in step S19, the operator himself / herself uses T0.
The value of may be changed manually.

Further, the data detected during the gate cutting work in each molding cycle, that is, the elapsed time after the movement of the moving member 8 is started, the position of the moving member 8, and the moving member 8 are detected.
A graph showing the relationship between the elapsed time after the start of the movement of the resin and the resin reaction force is shown for each molding cycle, for example, as shown in FIG.
It is also possible to determine the optimum waiting time T0 by superimposing it on the display and observing the variation of the slope of the graph between molding cycles having different waiting times. That is, the time at which the waiting time is gradually shortened and the inclination of the graph begins to change is the time at which the resin reaction force changes significantly, that is, the time at which the ease of shearing the resin changes.

The controller 1 automatically obtains the optimum waiting time.
It is possible to easily perform the graph display as shown in FIG. 6B and FIG. 7B at the same time while performing the processing as shown in FIGS. 2 to 7 for automatically setting to 0. Is.

[0056]

According to the present invention, the solidified state of the resin is detected by detecting the resin reaction force acting on the moving member. Therefore, the solidified state of the resin at various start timings of post-processing can be accurately measured. The post-processing start timing corresponding to the solidified state of the resin suitable for the desired post-processing can be easily selected and can be easily selected. In addition, the timing at which the resin is completely solidified is set as the initial value of the post-processing start timing, and the timing is gradually changed only in the direction of advancing the post-processing start timing, and the molding operation and the post-processing continuous operation are performed appropriately. Since the post-machining start timing is detected, the post-machining start timing can be compared with the case where the optimum machining start timing is detected by performing trial and error timing setting without specifying the directionality that shifts the timing. The time required for detection can be shortened. Further, every time a decrease in the resin reaction force set based on the resin reaction force detected based on the completely solidified state of the resin is detected, the post-processing start timing in the molding cycle one cycle before the molding cycle is detected. Since the timing is shortened with a shorter time width to detect the optimum post-machining start timing, the timing is changed at a slight time interval from the beginning to detect the optimum post-machining start timing. Compared to the case, the time required to detect the post-machining start timing is shortened, and moreover, the optimum post-machining is detected in the same way as when the optimum post-machining start timing is detected by changing the timing at a slight time interval from the beginning. The start timing can be detected with sufficient precision. Further, since the post-processing is performed at the same timing over a plurality of molding cycles to obtain the average value of the resin reaction force acting on the moving member, it is possible to remove the fluctuation of the disturbance that affects the detection of the resin reaction force. Therefore, the post-processing start timing corresponding to the solidified state of the resin suitable for the desired post-processing can be obtained more accurately.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main mechanical portion and a main portion of a control system of an injection molding machine according to an embodiment to which the method of the present invention is applied.

FIG. 2 is a flowchart showing an outline of post-processing start timing detection processing in the same embodiment.

FIG. 3 is a continuation of the flowchart showing the outline of the post-processing start timing detection processing.

FIG. 4 is a continuation of the flowchart showing the outline of the post-processing start timing detection processing.

FIG. 5 is a continuation of the flowchart showing the outline of the post-processing start timing detection processing.

FIG. 6 is a diagram showing an example of file means and data display.

FIG. 7 is a diagram showing an example of file means and data display.

FIG. 8 is a functional block diagram showing a configuration of an observer for detecting a resin reaction force acting on a moving member.

[Explanation of symbols]

 1 Injection Cylinder 2 Sliding Plate 3 Movable Side Mold 4 Fixed Side Mold 5 Cavity 6 Runner 7 Gate 8 Moving Member 10 Numerical Control Device 18 PMC CPU 20 Servo CPU

Claims (6)

[Claims] 1. An injection molding machine configured to perform post-processing on resin inside a mold by driving a moving member provided inside the mold after completion of filling the resin into the mold, at each molding cycle. The resin solidification state at each timing is detected by driving the moving member at different timings to detect the resin reaction force acting on the moving member, and the resin solidification state suitable for the desired post-processing is obtained. A post-processing start timing detection method in an injection molding machine, characterized by obtaining a corresponding post-processing start timing. 2. A plurality of molding cycles in an injection molding machine in which after the resin is filled in the mold, the moving member provided inside the mold is driven to post-process the resin inside the mold. By driving the moving member at the same timing over time to perform post-processing, the resin reaction force acting on the moving member is detected each time, and the average of the resin reaction force corresponding to the timing is obtained to determine the resin The solidification state of the resin at each timing is obtained by sequentially performing the work for obtaining the solidification state by changing the timing, and the post-processing start timing corresponding to the solidification state of the resin suitable for the desired post-processing treatment is obtained. A post-processing start timing detection method for a characteristic injection molding machine. 3. The timing at which the resin is completely solidified is set in the injection molding machine as an initial value of the post-processing start timing, and the time step width for accelerating the post-processing start timing is set in advance in the injection molding machine. For each cycle, advance the post-processing start timing by the above-mentioned step size to perform the molding operation and the post-processing continuous operation, and set the post-processing start timing in the molding cycle where the set resin reaction force decrease is first detected. The post-processing start timing detection method for an injection molding machine according to claim 1, wherein the post-processing start timing is obtained by detecting the post-processing start timing. 4. The timing at which the resin is completely solidified is set in the injection molding machine as an initial value of the post-processing start timing, and the time step width for advancing the post-processing start timing is set in advance in the injection molding machine. For each predetermined number of molding cycles, the post-processing start timing is advanced by the step size of the time, and the predetermined number of molding operations and the post-processing continuous operation are performed to average the resin reaction force at the same timing. The post-processing start timing detecting method for an injection molding machine according to claim 2, wherein the post-processing start timing is calculated by obtaining a value and detecting the post-processing start timing when the average value decreases by a set amount. 5. A post-processing start timing detection method in an injection molding machine comprising the following steps. Step 1. The step of setting the timing at which the resin is completely solidified as the initial value of the post-processing start timing in the injection molding machine and setting the step size of the time for advancing the post-processing start timing in the injection molding machine. Step 2. The post-processing start timing is advanced by the time width set for each molding cycle to allow continuous operation of the molding work and the post-processing, and the moving member for the post-processing is driven to cause the resin reaction that acts on the moving member. The process of detecting the force and determining the molding cycle in which the set decrease of the resin reaction force is first detected. Step 3. The post-machining start timing in the molding cycle one cycle before the molding cycle obtained in step 2 is reset as a new initial value, and the time step size for advancing the post-machining start timing is reset to a shorter time. Process. Step 4. A step of repeatedly performing step 2 and step 3 a set number of times. Step 5. A step of obtaining the post-processing start timing based on the post-processing start timing of the molding cycle detected in step 4. 6. A post-processing start timing detection method in an injection molding machine comprising the following steps. Step 1. The step of setting the timing at which the resin is completely solidified as the initial value of the post-processing start timing in the injection molding machine and setting the step size of the time for advancing the post-processing start timing in the injection molding machine. Step 2. Each time the molding cycle is executed a predetermined number of times, the post-machining start timing is advanced by the set step width to perform the continuous molding operation and the post-machining operation, and the moving member for the post-machining is driven for each molding cycle. A step of detecting and temporarily storing a resin reaction force acting on the resin, obtaining an average value of the resin reaction force in the molding cycle of the predetermined number of times, and obtaining a post-processing start timing when the average value decreases by a set amount. Step 3. The post-machining start timing that was applied immediately before the post-machining start timing obtained in step 2 is reset as a new initial value, and the time step width for advancing the post-machining start timing is reset to a shorter time. The process of doing. Step 4. A step of repeatedly performing step 2 and step 3 a set number of times. Step 5. A step of obtaining a post-addition start timing based on the post-processing start timing detected in step 4.