JPH0242337B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an automatic mold clamping force setting device for an injection molding machine having a toggle type mold clamping device.

Conventional technology When replacing a mold, a toggle type mold clamping device requires a mold thickness adjustment operation to adjust the mold clamping force according to the thickness of the mold, and also In some cases, it is necessary to change and adjust the mold clamping force. Conventionally, this mold clamping force setting operation was performed by workers based on their experience, but if the mold clamping force is too strong, too much force is applied to the tie bars and there is a risk of damage, and if the mold clamping force is too weak, the injection molding cannot be done properly. It was hot.

For hydraulic injection molding machines, for example,
As shown in Japanese Patent No. 25321, a device that automatically sets the mold clamping force has become publicly known.

However, there is no electric injection molding machine that is driven by a motor that automatically sets the mold clamping force.

Problems to be Solved by the Invention Therefore, the present invention provides an electric injection molding machine that automatically sets the mold clamping force by simply setting the mold clamping force when replacing the mold or changing the mold clamping force. The purpose of this invention is to provide an automatic mold clamping force setting device that can obtain sufficient force.

Means for Solving the Problems Figure 1 is a block diagram of the means adopted by the present invention to solve the above problems. a rear platen servo motor Ma for moving the rear platen along the rear platen, a rear platen position detection means 51a for detecting the position of the rear platen by a position detector attached to the rear platen servo motor Ma, and a toggle servo motor for driving the toggle mechanism 7. Mb, a toggle position detection means 51b for detecting the bending/extension state of the toggle link of the toggle mechanism by a position detector attached to the toggle servo motor Mb, and servo circuits 40a and 40b for the rear platen and toggle servo motors.
The mold contact detection means 50a and 50b detect the value of the error register or the drive current of each servo motor to detect mold contact, and the toggle servo motor Mb is driven to detect mold contact. Means 5
When mold contact is detected at 0b, the rear platen servo motor Ma is driven to move the rear platen 6 in the direction opposite to the mold to fully extend the toggle mechanism 7, and then the rear platen servo motor Ma is driven.
The rear platen 6 is moved toward the mold, and the rear platen 6 is further advanced from the position where the mold contact was detected by the mold contact detection means 50a to a position where the set mold clamping force is obtained. The above problem was solved by providing a control means 30 for positioning the rear platen 6.

Operation When a mold clamping force adjustment command with a mold clamping force set is input, the control device 30 controls the toggle servo motor.
Drive Mb and extend the toggle mechanism. Then, the toggle position detection means 51b detects whether the toggle mechanism has reached the fully extended position, and the mold abutment detection means 50b detects whether or not the mold has abutted. If contact with the mold is detected before the mechanism is fully extended, the rear platen servo motor
Drive Ma to move the rear platen 6 in the direction opposite to the mold (backward). Then, when the toggle mechanism is fully extended, the rear platen servo motor Ma is driven to move the rear platen 6 toward the mold (forward), and the mold contact detection means 50a detects the mold contact detection means 50a. Advance until contact is detected. When mold contact is detected, the rear platen is advanced from the position detected by the rear platen position detection means to a position corresponding to the mold clamping force, and the mold clamping adjustment is completed.

Embodiment FIG. 2 is a diagram showing a mold clamping mechanism in an embodiment of the present invention, FIG. 3 is a diagram showing the configuration of a control section in the same embodiment, and FIG. 4 is a diagram showing the operation processing flow of the same embodiment. This shows that.

In FIG. 2, one mold 1 is mounted on the front platen 2, and the other mold 3 is mounted on the moving platen 4.
are installed in each. Four tie bars 5 are attached to the front platen 2, and a rear platen 6 is connected to the other end of each tie bar 5.
A toggle mechanism 7 consisting of two sets of toggle links 8 and 8' is provided between the rear platen 6 and the moving platen 4, and the moving platen 4 is driven by the toggle mechanism 7 so that it can slide on each tie bar 5. It is set in.

A through hole 9 is made in the center of the rear platen 6,
A ball nut 10 is provided in the through hole 9, and a ball screw 12 to which a cross head 11 for bending and extending two sets of toggle links 8, 8' is connected is screwed into the ball nut 10. ball nut 10
is fixed to the first gear 13, and the first gear 13
It is provided so that it can be rotated together.

Nuts 15 are provided on the back surface of the rear platen 6 to be engaged with screws cut into each tie bar 5. A sprocket 16 is provided on the nut 15, and the rear platen 6 is connected to the rear platen 6 via a support member 17.
Servo motor for moving the rear platen fixed to the
The nut 15 is rotated by the drive of the servo motor Ma via a sprocket 19, a chain 20, and a sprocket 16 provided on the shaft of the servo motor Ma. One side surface of each nut 15 is formed into a flange shape, and this flange-like protrusion 14 is connected to a groove provided in the rear platen 6.
4', which causes the servo motor to
When Ma is driven, each nut 15 rotates and moves on each tie bar 5 to the left and right in FIG.
As each nut moves due to the engagement of 4',
The rear platen 6 is also movable. The amount of movement of the rear platen 6 is detected by an incremental encoder Pa provided on the servo motor Ma as rear platen position detection means. Further, on the back side of the rear platen 6, a second gear meshing with the first gear 13 is provided.
A servo motor Mb for toggle driving is provided to drive the gear 22 via the shaft 23. The servo motor Mb for driving the toggle is provided with an incremental encoder Pb as a toggle position detecting means for detecting the bending/extending state of the toggle mechanism 7.

FIG. 3 shows the configuration of a control unit that controls the mold clamping device of this embodiment, and 30 is a numerical control device (hereinafter referred to as CNC) having a computer as a control means for controlling the mold clamping device; 40a is the servo circuit of the servo motor Ma for driving the rear platen,
40b is a servo circuit for a servo motor Mb for toggle driving. In the CNC 30, 31 is a central processing unit (hereinafter referred to as CPU), and 32 stores control programs such as mold clamping processing and mold clamping force adjustment.
33 is an input/output circuit; 33 is an input/output circuit; 33 is an input/output circuit;
A position command is output to the error registers 41a, 41b of the servo circuits 40a, 40b, and the values of the error registers 41a, 41b are read through the servo circuits 40a, 40b. Reversible counters 34 and 35 count pulses from encoders Pa and Pb provided on servo motors Ma and Mb, respectively, and detect the positions of the rear platen 6 and the crosshead 11 of the toggle mechanism, respectively. 36 is a manual input device for inputting various commands and various setting values. Note that 37 is a bus.

40a and 40b are known servo circuits,
These servo circuits 40a and 40b have the same configuration, and when a movement command consisting of a pulse train is input as a movement amount per unit time through the input/output circuit 33 of the CNC 30, this movement command and the encoder Pa, The error registers 41a and 41b store the difference between the amount of movement of the servo motors Ma and Mb detected by Pb.
This is calculated by digital-to-analog converters (hereinafter referred to as D/A converters) 42a and 42b and converted into an analog quantity voltage as a speed command value. Furthermore, this servo circuit performs speed feedback in order to improve responsiveness.
The voltage corresponding to the actual speed of the servo motor is subtracted from the speed command value, and the difference, that is, the error between the command speed and the actual speed, is amplified by compensators 44a and 44b to calculate the torque. Output as a command. This torque command is applied to the servo motor Ma,
It is output as a voltage corresponding to the current value flowing through the armature Mb.In order to further improve responsiveness to this torque command, the servo motor Ma,
A current detector 47a that detects the armature current of Mb,
The voltage corresponding to the armature current from 47b is fed back, and the difference between the torque command and the armature current feedback signal is applied to compensators 45a and 45b.
The signal is amplified by the power amplifiers 46a and 46b to drive and control the servo motors Ma and Mb.

Although the servo circuits 46a and 46b operate as described above, each servo circuit 40a and 40b
The values of the error registers 41a and 41b are input to the input/output circuit 33, so that the CNC 30 can detect the amount of error.

In the above configuration, when the mold of the injection molding machine is replaced or the clamping force is changed, the clamping force is set and a clamping force setting command is input. Then,
CPU31 is the servo motor Mb for driving the toggle mechanism.
rotate gears 22, 13 and ball nut 1.
0. Drive the ball screw 12, move the crosshead 11 forward (to the right in Figure 2), extend the toggle links 7 and 8, move the moving platen 4 forward (step S1), and when the servo motor Mb rotates, the encoder The pulse from Pb is input to the reversible counter 35, thereby detecting the position of the crosshead 11. The CPU 31 reads the value of this reversible counter 35 and determines whether or not the toggle links 7 and 8 have reached the fully extended position L1 (step S2). (step S3), and repeats steps S2 and S3 sequentially, and if the mold 3 of the moving platen 4 is connected to the mold of the front platen 2 before reaching the value L1 of the reversible counter 35. When it comes into contact, the servo motor
Since the rotation of Mb is stopped, the error register 41b of the servo circuit 40b receives no pulse from the encoder Pb even though a movement command is input, and the value of the error register 41b is amplified as an error amount. When this error amount reaches a certain value (step S3), it is assumed that the mold has come into contact, and the drive of the servo motor Mb is stopped (step S4), and the position L2 of the crosshead 11, that is, the value of the reversible counter 35 is read. (Step S5), the current crosshead position L2 is subtracted from the crosshead position L1 at which the toggle link is fully extended to calculate the remaining amount L3 until the toggle ring is fully extended (step S6). Then, the servo motor Ma for driving the rear platen is reversed to drive the sprocket 19, chain 20, sprocket 16, and nut 15 to move the rear platen 6 backward by the remaining amount L3.
Stop driving servo motor Ma (step
S7). Next, the servo motor Mb for driving the toggle mechanism is rotated normally again to extend the toggle link, and the moving platen 4 is advanced (step S8), and the processing from step S2 onwards is performed again. Since the rear platen 6 has been retreated by the required amount, the reversible counter 35 detects in step S2 that the specified amount L1 has been reached, and the process moves to step S9. In addition, the specified amount L1
If this is not reached, the process from step SS3 onwards is repeated again.

Furthermore, when the servo motor Mb is rotated in the normal direction starting at step S1, the error amount in the error register 41b of the servo circuit 40b increases by the specified amount L1.
When this is detected, that is, when the toggle link is fully extended before the molds 1 and 3 come into contact, the process moves to step S9. In step S9, the drive of the servo motor Mb is stopped, the operation of the toggle mechanism 7 is stopped, and the servo motor Ma is rotated in the forward direction to move the rear platen 6, toggle mechanism 7, and moving platen 4 forward (step S10). When the moving platen 4 moves forward and the molds 1 and 3 come into contact with each other, the servo circuit 4 is activated as described above.
When the error amount in the error register 41a of 0a increases and exceeds a predetermined value, driving of the servo motor Ma is stopped (steps S11 and S12). That is, the servo motors Ma and Mb will stop at the position where the mold 3 comes into contact with the fully extended toggle link.
Next, the amount of extension L0 of the tie bar 5 corresponding to the set torque T is calculated (step S13). This is because mold clamping force is applied to the molds 1 and 3 depending on the amount of extension of each tie bar 5, and the amount of extension of the tie bar 5 and the mold clamping force are in a proportional relationship. If the amount of extension of the tie bar is 1 when the mold clamping force is T, the amount of extension LO corresponding to the set torque T can be calculated using the formula L0=T/T0×l. next,
The servo motor Mb is reversed to move the moving platen 4 backward by the mold opening amount (step S14).
Next, the servo motor Ma is rotated in the forward direction to move the rear platen 6 forward by the extension amount LO of the tie bar corresponding to the set torque T calculated in step S13 (step S15). As a result, when the servo motor Mb is driven, the molds 1 and 3 come into contact before the toggle link is fully extended, and when the servo motor Mb is driven by the specified amount L1, the tie bar 5 is extended by L0, and this elongation causes the mold to 1 and 3 will be tightened with the set torque T.

In the above embodiment, the contact between the molds 1 and 3 is controlled by the error registers 41a and 4 of the servo circuits 40a and 40b.
Although the detection is based on an increase in the amount of error 1b, this contact between the molds may also be detected based on an increase in the armature current to the servo motors Ma and Mb. In this case, the current detector 47 of the servo circuits 40a and 40b
a, 47b output via A/D converter
All you have to do is input it to the CNC and detect the armature current values of the servo motors Ma and Mb.When the molds 1 and 3 come into contact, the torque of the servo motors Ma and Mb, that is, the armature current, is used to move the moving platen 4 forward. Since this increases, contact of the mold can be detected. In this example, DC motors are shown as the servo motors Ma and Mb, but AC motors are also used, and pulse encoders are used as the encoders Pa and Pb, but resolvers of other detectors, A speed generator or the like may also be used.

Effects of the Invention As described above, in the present invention, by simply setting the mold clamping force and inputting a mold clamping force setting command, the rear platen is positioned so that the set mold clamping force is automatically obtained. Therefore, it is very convenient when replacing the mold or changing the mold clamping force, and since the mold clamping force is not manually adjusted as in the past, there is less error in setting the mold clamping force. Optimal mold clamping force can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a diagram showing a mold clamping mechanism of an embodiment of the present invention, and FIG. 3 is a diagram showing the configuration of a control section in the same embodiment.
FIG. 4 is a diagram showing the operational processing flow of the same embodiment. 1, 3...Mold, 2...Front platen, 4
...Moving platen, 5...Tie bar, 6...
... Rear platen, 7... Toggle mechanism, Ma... Servo motor for rear platen, Pa... Position detector for rear platen, Mb... Servo motor for toggle, Pb... Position detector for toggle, 30... Control means, 40a , 40b... Servo circuit.

Claims (1)

[Claims] 1 In an injection molding machine having a toggle-type mold clamping device, a rear platen servo motor that moves the rear platen along a tie bar, and a rear platen position that detects the position of the rear platen using a position detector attached to the rear platen servo motor. a detection means, a toggle servo motor that drives the toggle mechanism, and a toggle position detection means that detects the bending and stretching state of the toggle link of the toggle mechanism using a position detector attached to the toggle servo motor;
Each mold contact detection means detects the contact of the mold by detecting the error register value of the servo circuit of the rear platen and toggle servo motors or the drive current of each servo motor, and drives the toggle servo motor. When mold contact is detected by the mold contact detection means for toggle, the rear platen servo motor is driven to move the rear platen in the direction opposite to the mold to fully extend the toggle mechanism, and then the rear platen servo motor is activated. The motor is driven to move the rear platen toward the mold, and the rear platen is further advanced from the position at which mold contact was detected by the mold contact detection means for the rear platen, thereby obtaining the set mold clamping force. 1. An automatic mold clamping force setting device comprising a control means for positioning a rear platen at a position where the rear platen is positioned.