JPH0441890B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a control method for supplying molding material to an injection cylinder of an injection molding machine, and particularly relates to a control method for supplying molding material to an injection cylinder of an injection molding machine, and particularly to a control method for supplying molding material to an injection cylinder of an injection molding machine. The present invention relates to a material supply control method during a process.

(Prior art) An in-line screw type injection molding machine transports the molded resin material supplied into the injection cylinder forward while plasticizing and kneading it by the rotation of the injection screw, and moves the injection screw forward. Therefore, the mold cavity is filled with plasticized resin. In such an injection molding machine, a hopper is generally attached to the rear upper surface of the injection cylinder, and material is supplied from the hopper through a material supply port provided in the injection cylinder. In this case, if the material is directly fed into the injection cylinder from the hopper, the material feeding speed may vary depending on the amount, particle size, density, etc. of the material in the hopper. Therefore, as shown in Japanese Utility Model Publication No. 52-35968, a system was developed in which a material feeder was provided between the hopper and the injection cylinder to control the amount of material fed to the injection cylinder. There is.

This material feeder rotates a feed screw fitted into the feed cylinder to transport the material supplied from the hopper forward and feed it into the injection cylinder in predetermined amounts. . The feed screw is rotated in conjunction with the rotation of the injection screw during the material plasticization process of the injection molding machine.

When such a material feeder is provided, the material is
Since the feed amount is controlled by the material feeder, it is possible to adjust the actual compression ratio, reduce the plasticizing torque of the injection molding machine when using high viscosity materials, and further reduce surging. It is also possible to obtain the effect that it is possible to prevent silver, discoloration, etc. that appear on molded products.

By the way, conventionally, even in an injection molding machine having such a material feeder, during the injection process,
Either the material supply was stopped completely or the material was supplied at a constant rate.

(Problems to be Solved by the Invention) However, when the supply of material is stopped during the injection process, a space corresponding to the length corresponding to the injection stroke of the injection screw is created in the injection cylinder. Furthermore, even if a fixed amount of material is supplied during the injection process, the movement speed of the injection screw is controlled in a multi-stage sequence during the injection process, so that the material can be fed within a length range corresponding to the injection stroke. This will result in uneven supply.

If such space or material supply unevenness occurs in the injection cylinder, it will cause uneven kneading and variations in plasticization time in the next plasticizing process, resulting in unstable molded product quality. There is a problem that.

The present invention was made in view of these problems, and its purpose is to supply an optimal amount of material into the injection cylinder during the injection process in an injection molding machine equipped with a material feeder. It is to do so.

(Means for Solving the Problem) In order to achieve this object, the present invention performs appropriate arithmetic processing on the moving speed value of the injection screw during the injection process, and based on the result of the calculation, the material feeder The rotation speed of the feed screw is controlled.

The movement speed value of the injection screw may be the injection speed setting value set in the molding condition setting device of the injection molding machine, the time differential value of the detected value of the actual injection screw movement amount, the detected value of the actual injection screw speed, etc. is used. The calculation process is to calculate the optimum material supply rate based on the moving speed of the injection screw and the depth of the screw groove at that time.

(Function) With this configuration, even when the injection speed is changed in multiple stages in the injection process, the rotational speed of the feed screw is controlled according to the injection speed of each stage. In the stage, the rotation speed of the feed screw is low,
The rotational speed of the feed screw is increased in stages where the injection speed is high. Accordingly, an optimum amount of material is supplied depending on the speed of movement of the injection screw, and an optimum distribution of the material within the material supply area corresponding to the injection stroke of the injection cylinder is achieved.

(Example) Hereinafter, an example of the present invention will be described using the drawings.

The figure is a block diagram showing an example of a control device for carrying out the method of controlling material supply for an injection molding machine according to the present invention.

As is clear from this figure, the injection cylinder 1 of the injection molding machine is rotatably driven by a rotating machine 3 equipped with a hydraulic motor 2, and an injection hydraulic cylinder 4 is provided inside the injection cylinder 1.
An injection screw 5, which is driven forward by a screw, is fitted therein. The depth of the screw groove 5a of this screw 5 is designed to gradually change over the entire length of the screw 5. An injection nozzle 6 is provided at the front end of the cylinder 1, and as the screw 5 advances, the molten resin stored in the cylinder 1 is injected through the nozzle 6 into the cavity of a mold (not shown). It is becoming more and more filled.

A material supply port 7 communicating with the inside of the cylinder 1 is provided on the rear upper wall of the injection cylinder 1.
The molding resin material supplied from the hopper 8 is guided into the cylinder 1 from the material supply port 7 after its supply amount is controlled by the material feeder 9. The material feeder 9 has a feed cylinder 10 and a feed screw 11, and the feed screw 11 is rotationally driven by a feed motor 12.

The hydraulic motor 2 and injection hydraulic cylinder 4 of the rotating machine 3 are each driven by hydraulic oil supplied from a hydraulic pump 13. The hydraulic pressure is controlled in magnitude by a pressure regulating valve 14, and a solenoid valve 15 for process switching.
The direction can be changed by. The solenoid valve 15 establishes continuity between the hydraulic pump 13 and the right chamber 4a of the injection hydraulic cylinder 4 when the left solenoid 15a is energized, and locks the hydraulic motor 2, and the right solenoid 15b is energized. sometimes hydraulic pump 1
3 and the hydraulic motor 2, and the right chamber 4a of the injection hydraulic cylinder 4 is communicated with the oil tank 16. The hydraulic oil supplied to the injection hydraulic cylinder 4 is further supplied to the flow rate regulating valve 17.
The flow rate is controlled by

The position of the injection screw 5 is detected as the displacement of the screw by a position detector 18 via a bracket or the like. This position detector 1
The detected value of 8 is sent to the controller 2 through the condition setter 19.
I'm starting to be guided by 0. Condition setter 19
is for setting various molding condition values of the injection molding machine, and inside it there are n injection speed switching position setters 21 1 , 21 2 , ..., 21 o, and n-1 injection speed switching position setters 21 ₁ , 21 ₂ , ..., 21 _o Speed setter 22 ₁ , 22 ₂ ,..., 22 _oi , m
holding pressure setting devices 23 ₁ , 23 ₂ , ... 23 _n and m holding pressure time setting devices 24 ₁ , 24 ₂ , ..., 24 _n
etc. are provided. Injection speed switching position setter 2
1 ₁ to 21 _o are used to set the position of the injection screw 5 at which the injection speed should be changed during the injection filling process, and the final stage setter 21 _o is used to set the position of the injection screw 5 at the end of the filling process, i.e. It is said that the amount of cushioning is set.
The injection speed setting devices 22 ₁ to 22 _oi are the screws 5 set in the injection speed switching position setting devices 21 ₁ to 21 _o.
The moving speed of the screw 5 between each position is set respectively. In addition, the holding pressure setting device 2
3 ₁ to 23 _n are used to set the magnitude of each holding force when changing the holding force in multiple stages in the holding pressure process, and the holding pressure time setter 24 ₁
to 24 _n are for setting the load time of each holding force set in the holding force setting devices 23 ₁ to 23 _n , respectively. The controller 20 compares the actual position of the screw 5 detected by the position detector 18 with the positions set in the injection speed switching position setters 21 ₁ to 21 _o , and adjusts the screw 5 to each set position. is reached, and after a set amount of time has elapsed.
The pressure regulating valve 14, the solenoid valve 15, the flow regulating valve 17, etc. are controlled to control the amount of hydraulic oil and the oil pressure applied to the hydraulic motor 2 or the injection hydraulic cylinder 4.

Each setting value of the injection speed setter 22 ₁ to 22 _oi is as follows:
Furthermore, the calculation processing is performed in the calculation unit 25. This calculator 25 is an injection speed setting device 2
2 ₁ - 22 Calculates the optimum material supply speed at that point in time according to the set values set in _oi and the depth of the screw groove 5a of the injection screw 5 located at the material supply port 7 at that time. It is. Then, the value of the calculation result by the calculator 25 is led to the controller 20, and the controller 20 controls the rotational speed of the feed motor 12 of the material feeder 9. This feed motor 12
is rotated in conjunction with the rotation of the injection screw 5 in the material plasticizing process of the injection molding machine.

In the injection molding machine configured as described above, the solenoid 15b on the right side of the process switching solenoid valve 15 is energized during the plasticizing process. As a result, the high-pressure hydraulic oil discharged from the hydraulic pump 13 and regulated by the pressure regulating valve 14 is supplied to the hydraulic motor 2 of the rotating machine 3, so that the injection screw 5 rotates at a predetermined rotational speed. Driven. At this time, the feed motor 12 of the material feeder 9 is also driven to rotate at a predetermined rotational speed. Therefore, the molded resin material supplied from the hopper 8 to the material feeder 9 is sent forward by the feed screw 11 at a speed corresponding to its rotation speed, and is fed into the injection cylinder 1 in predetermined amounts from the material supply port 7. Ru.

The material supplied into the injection cylinder 1 is kneaded and plasticized between the cylinder 1 and the screw 5 by the rotation of the injection screw 5.
sent to the front. At this time, the right chamber 4a of the injection hydraulic cylinder 4 is connected to the oil tank 16, and the cylinder 4 is in a free state, so the injection screw 5 moves as the molten resin accumulates at the front of the injection cylinder 1. and retreat.

When a predetermined amount of molten resin is stored in the front part of the injection cylinder 1, the injection screw 5
The position set in the stage injection speed switching position setter ₂₁₁ is reached. Then, the position is detected by the position detector 18, and the controller 20 is activated.
The left solenoid 15a of the solenoid valve 15 is energized, and the right solenoid 15b is de-energized. Thereby, the injection molding machine is switched from the plasticizing process to the injection process.

When the injection process begins, high-pressure hydraulic oil is sent from the hydraulic pump 13 to the right chamber 4a of the injection hydraulic cylinder 4. The oil pressure and oil amount are controlled by the pressure regulating valve 14 and the flow rate regulating valve 17 to a level corresponding to the set value set in the first stage injection speed setting device 22 ₁ . Therefore, the injection screw 5 is driven forward at a speed corresponding to the set value. Thereby, the molten resin stored in the front part of the injection cylinder 1 is injected from the injection nozzle 6 at a predetermined speed.

At this time, the feed screw 11 of the material feeder 9 is rotationally driven by the feed motor 12 based on the value obtained by processing the set value of the injection speed setting device 22 ₁ by the calculator 25 . Therefore, the rotation speed of the feed screw 11 corresponds to the forward movement speed of the injection screw 5. As a result, material is supplied into the injection cylinder 1 at a speed corresponding to the moving speed of the injection screw 5, and the optimum amount of material is fed onto the screw 5 over the range of the stroke at that time. will be distributed.

When the injection screw 5 moves forward and reaches the position set in the second stage injection speed switching position setter ₂₁₂ , the injection hydraulic cylinder 4 moves the injection screw 5 to the second stage injection speed setting. Hydraulic pressure and oil amount sufficient to move the container ₂₂₂ forward at the set speed are applied. Thereby, the moving speed of the injection screw 5, that is, the injection speed is switched. At this time, the rotational speed of the feed screw 11 of the material feeder 9 is also switched to a speed corresponding to the moving speed of the injection screw 5. Therefore, material is fed into the injection cylinder 1 at an optimal speed depending on the injection speed.

In this way, as the injection screw 5 moves forward and its moving speed is switched,
The rotation speed of the feed screw 11 of the material feeder 9 is switched, and material is fed into the injection cylinder 1 at high speed when the injection screw 5 moves forward at high speed, and at low speed when the injection screw 5 moves forward at low speed. . There is therefore an approximately uniform distribution of material in the injection cylinder 1 over an area corresponding to the injection stroke of the injection screw 5.

When the injection screw 5 reaches the position set by the final stage injection speed switching position setter 21n, the filling process is completed and the process is switched to the pressure holding process. After that, the hydraulic pressure applied to the injection hydraulic cylinder 4 is controlled by the pressure holding time setting devices 24 ₁ , 24 ₂ , . . . , 2
4 At every time set to _n , the holding force setting device 23
₁ , 23 ₂ , . . . , 23 _n are switched in order.

When moving to the pressure holding step, the injection screw 5 usually comes to a nearly stopped state. Therefore, at that time, the feed motor 12 of the material feeder 9 is stopped. However, there are molding situations in which the injection screw 5 continues to move forward even after entering the pressure holding step. In such a case, the value of the movement amount of the screw 5 detected by the position detector 18 is time-pulverized by the calculator 25, and the rotational speed of the feed screw 11 is controlled according to the obtained screw movement speed value. Do it like this. Alternatively, a screw speed detector capable of detecting the moving speed of the injection screw 5 may be separately provided, and the rotation speed of the feed screw 11 may be controlled in accordance with the detected value.

When the pressure holding process is completed, the solenoid 15b on the right side of the solenoid valve 15 is energized, and the process is switched to the plasticizing process. Thereby, the next plasticizing step is started.

Note that, as in the above embodiment, the calculation processing by the calculator 25 is performed in advance by using the injection speed set value set in the condition setting device 19 as the moving speed value of the injection screw 5 during the injection process. be able to. Therefore, the arithmetic unit 25 may have a slow processing speed, and can respond quickly when changing the speed of the injection screw 5.

However, the actual moving speed of the injection screw 5 may vary from the set speed set in the injection speed setters 22 ₁ to 22 _oi . When it is required to prevent such uneven supply of material due to speed fluctuations of the injection screw 5, the detected value of the actual screw movement amount detected by the screw position detector 18 is subjected to time differentiation processing. , the feed screw 11 is determined based on the obtained screw movement speed value.
It is also possible to control the rotation speed of.
Alternatively, the actual moving speed of the injection screw 5 may be detected by a separately provided screw speed detector, and the detected value may be used. Even in such a case, the screw groove 5a is adjusted to the screw ground velocity value.
The rotational speed of the feed screw 11 is determined by calculating the rotation speed of the feed screw 11 by performing arithmetic processing that takes into consideration the depth of the can be accommodated.

(Effects of the Invention) As is clear from the above invention, according to the present invention, during the injection process, the rotational speed of the feed screw of the material feeder is controlled according to the moving speed of the injection screw, so the injection speed Even when the injection molding material is switched in multiple stages or when the molding conditions are changed, the molding material can be distributed almost uniformly within the injection cylinder. Therefore, during the plasticizing process, the material is always kneaded uniformly and well, molding defects are minimized, and it is possible to stably mold a good product.

[Brief explanation of drawings]

The figure is a block diagram showing an example of a control device for carrying out the method of controlling material supply for an injection molding machine according to the present invention. 1... Injection cylinder, 3... Rotating machine, 4... Hydraulic cylinder for injection, 5... Injection screw, 9...
Material feeder, 11...Feed screw, 12
...Feed motor, 14...Pressure regulating valve, 15
...Process switching solenoid valve, 17...Flow rate adjustment valve, 18...Position detector, 19...Condition setting device,
20... Controller, 21 ₁ to 21 _o ... Injection speed switching position setter, 22 ₁ to 22 _oi ... Injection speed setting device,
25...Arithmetic unit.

Claims (1)

[Scope of Claims] 1. In an injection molding machine in which molding material is supplied into an injection cylinder by a material feeder having a feed screw that is rotationally driven in conjunction with the rotation of an injection screw during the plasticizing process; , by performing arithmetic processing on the moving speed value of the injection screw, the optimum material supply speed associated with the movement of the screw is determined, and based on the calculation result, the rotational speed of the feed screw of the material feeder during the injection process is controlled. A material supply control method in an injection molding machine, characterized by: 2. The injection according to claim 1, characterized in that, as the moving speed value of the injection screw during the injection process, injection speed setting values set in multiple stages in a condition setting device for setting molding conditions are used. Material supply control method in a molding machine. 3. As set forth in claim 1, the actual movement amount of the injection screw is detected and a value obtained by time-differentiating the detected value is used as the movement speed value of the injection screw during the injection process. Material supply control method in injection molding machine.