JPH0752213A - Control method of molding of injection molding machine - Google Patents

Abstract

PURPOSE:To apply directly pressure to resin within a mold without causing mold clamping force of the mold to be changed. CONSTITUTION:In a process wherein resin up to complection of dwelling from starting of injection is solidified, a core 4 is moved forward by driving servo motor 10 and the resin within a mold 1 clamped with set up mold clamping force is compressed. This compression force is detected by a load cell 5, which is controlled by a numerical control device 20 so that the compressed force reaches a fixed value. Since compression force is applied to the resin within the mold clamped by the set up mold clamping force in a solidifying process, transferabilities of a molded product become favorable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding method using an injection molding machine.

[0002]

2. Description of the Related Art A compression molding method and a control method thereof are described in, for example, JP-A-63-35327 and JP-A-6-36327.
It is known from, for example, Japanese Patent Publication No. 3-39314. In these conventional injection compression molding methods, the movable mold is moved to compress the resin in the mold. For example, the above-mentioned JP-A-63-35
The one described in Japanese Unexamined Patent Publication No. 327 performs speed control of the mold moving speed at the initial stage of mold clamping for compression, and when the mold reaches a set position, the pressure control is performed in a single-stage or multi-stage pressure. The control is switched to control the compression process.

Further, the one disclosed in Japanese Patent Laid-Open No. 63-39314 is also movable by switching from the filling process to the compression process when the amount of resin filled in the cavity by injection reaches a target value. The side mold is moved to compress the resin in the mold to control the pressure.

[0004]

The object of the present invention is not to move the movable side mold to compress the resin in the mold as in the conventional compression control, but to adjust the mold clamping force of the mold. It is an object of the present invention to provide a new molding method in which a pressure is directly applied to a resin in a mold in a mold clamped by a set mold clamping force without changing.

[0005]

According to the present invention, an injection molding machine is provided with a pressing member that moves in a clamped mold and presses resin in the mold, and a driving means that drives the pressing member. During the period from the start of injection to the end of pressure holding, the driving means is driven to press the resin in the mold with a set single-stage or multi-stage pressure to perform molding.

[0006]

In the process in which the molten resin injected into the mold is solidified from the start of injection to the end of holding pressure, the driving means is driven to press the resin in the mold by the pressing member. This improves the transferability of the molded product.

[0007]

FIG. 2 is a block diagram of the essential parts of an injection molding machine that employs the molding control system of the present invention. In the figure, 1 is a mold, 2
Is a heating cylinder, and 3 is a screw. Reference numeral 4 denotes a core, and in the present embodiment, the core 4 is rotated by a ball nut 7 and a ball screw 6 for converting the rotation of the servomotor 10 into a linear movement via a timing gear 9 and a timing belt 8. To the resin 13 in the cavity.
I try to compress. Reference numeral 5 is a load cell for detecting the pressure applied to the resin 13 in the cavity, and the pressure detected by the load cell 5 is converted into a digital signal by the A / D converter 12. Reference numeral 11 is a pulse coder as a position detector for detecting the rotation of the servo motor, that is, the position of the core 4.

Reference numeral 20 denotes a numerical control device as a control device for controlling the injection molding machine. The numerical control device 20 is a central processing unit (hereinafter, C) for numerical control (hereinafter, NC).
It has a CPU 22 for a PU and a programmable machine controller (hereinafter referred to as PMC) 21, and the NC CPU 21 has a ROM 24 and a data storing a control program for controlling the injection molding machine as a whole. A RAM 25 used for temporary storage and the like is connected to the bus. A servo interface 26 is connected to the NC CPU 21 by a bus, and a servo circuit for driving and controlling a servo motor for each axis for injection, clamping, screw rotation, compression, etc. is connected to the servo interface 26. 2 and the servo circuit 27 for compression is shown in FIG.
Only illustrated. The servo circuit 27 is connected to the servomotor 10 and receives a feedback pulse from the pulse coder 11 to control the rotational position, torque, etc. of the servomotor 10.

The PMC CPU 22 is bus-connected to a ROM 28 which stores a sequence program or the like for controlling the sequence operation of the injection molding machine, and a RAM 29 which is used for temporary storage of data during the arithmetic processing of the PMC CPU 22. .

The CPU 21 for NC and the CPU 2 for PMC
2 is a bus arbiter controller (hereinafter referred to as BAC)
A bus is connected to the BAC 23 by a bus 23, and a shared RA
The M30, the input circuit 31, and the output circuit 32 are bus-coupled. The shared RAM 30 is composed of a writable non-volatile memory such as a bubble memory or a CMOS memory, and stores an NC program for controlling the operation of the injection molding machine, various set values such as molding conditions, parameters, macro variables and the like. It is like this. Various sensors provided in the injection molding machine are connected to the input circuit 31, and particularly in connection with the present invention, the output signal of the load cell 5 is converted into the A / D converter 1.
The pressure signal converted into a digital signal in 2 is input.

Although various actuators of the injection molding machine are connected to the output circuit 32, the torque limit for limiting the output torque of the compression servomotor 10 from the output circuit 32 is related to the present invention. The value is output to the servo circuit 27.

Further, a manual data input device with a CRT display device (hereinafter referred to as CRT / MDI) 34 is connected to the BAC 23 via an operator panel controller 33.

In the above construction, various molding conditions are input and set from the CRT / MDI 34 before operating the injection molding machine and stored in the shared RAM 30. In particular, in this embodiment, the position of the core 4 that has completed compression during the compression process, that is, the rotational position of the servo motor 10 that has completed compression, the torque limit value that is the compression force, the compression time, and the quality of the molded product are determined. Set the value of NG timer TN. Next, when the injection molding machine is operated, the numerical controller 20 causes the ROM 28
Sequence program and shared RAM 30 stored in
The injection molding machine is controlled according to the NC program stored in, and the molding process is repeated by repeating the steps of mold closing, mold clamping, injection, compression, holding pressure, cooling, metering, mold opening, and molding product ejection. When the process comes, the PMC CPU 22 starts the process of the compression process shown in FIG.

First, the PMC CPU 22 uses the shared RAM 3
The compression time set to 0 is read out via the BAC 23, the compression time is set in the compression timer Tp provided in the RAM 29, and the compression timer Tp is started (step S
1). The torque limit value as the compression force set in the shared RAM 30 is output to the servo circuit 27 via the BAC 23 and the output circuit 32 to limit the output torque of the servo motor 10 (step S2) and set in the shared RAM 30. The compression completion position is set to the address position of the shared RAM 30 read by the NC CPU 21 (step S
3) Further, the setting value of the NG timer TN set in the shared RAM 30 is read out, set in the NG timer TN provided in the RAM 29, and started (step S
4) Write the compression start command in the shared RAM 30 (step S5).

When the compression start command is read from the shared RAM 30, the NC CPU 21 starts pulse distribution to the set compression completion position and outputs it to the servo circuit 27 via the servo interface 26. The servo circuit 27 outputs a torque command according to the difference between the commanded pulse amount and the pulse amount detected by the pulse coder 11, and limits the output torque by the torque limit value output from the output circuit 32 to perform servo control. The motor 10 is driven to move the core 4 to the right in FIG. 1 via the timing gear 9, the timing belt 8, the ball nut 7, and the ball screw 6 to compress the resin in the cavity. At this time, the compression pressure detected by the load cell 5 is converted into a digital signal by the A / D converter 12 and input to the input circuit 31.
U22 compares the fed back compression pressure with the current torque limit value, increases or decreases the torque limit value so that the pressure detected by the load cell 5 becomes the set compression pressure (torque limit value), and outputs it via the output circuit 32. Output to the servo circuit 27.

Although this pressure feedback control is not shown in the flow chart of FIG. 1, this point is the same as the conventional pressure feedback control. Further, the compression pressure control may be performed by simply applying the torque limit to the output of the servo motor 10 by the open control without performing the pressure feedback control. On the other hand, PMC CPU
Reference numeral 22 denotes an in-position indicating that the pulse distribution end signal up to the compression completion position is written from the NC CPU 21 to the shared RAM 30 or the in-position width of the compression completion position is entered while the compression is being performed. It is determined whether or not the signals are written (step S6). If these signals are not written and the core 4 has not reached the compression completion position, it is determined whether or not the NG timer TN has timed up ( If the time is not up in step S7), the process returns to step S6, and the processes of steps S6 and S7 are repeated. Then, when the core 4 reaches the command position, that is, the compression completion position before the NG timer TN times out, there is no error between the command position and the current position, so the servo motor 1
0 stops at the position, applies the torque of the set torque limit value to the core 4, holds the core 4 at the position, and waits until the compression timer Tp expires (step S8). Then, when the compression timer Tp times out, the processing of this compression step is ended.

While pressure control is performed in this manner, position control (compression position control) is also performed. On the other hand, before the core 4 reaches the command compression completion position, the NG timer TN
(Step S7), this occurs when the amount of resin filled in the cavity is large.
At this time, a signal indicating that the molded product is defective is sent and defective product processing such as writing in the shared RAM 30 is performed (step S9), and the processing of the compression process is ended. When the defective product signal is sent, the molded product is taken out from the mold separately from the non-defective product.

The above is the operation in the compression process. The position of the core 4 when the compression process is started is the compression completion position A.
Position B where the volume is larger than the cavity volume (see Fig. 1) of
In particular, the position of the core 4 before the start of injection may be any position, but if it is at a position where the cavity volume is smaller than the compression completion position A (the position on the right side of the compression completion position A in FIG. 1). , It becomes the form of vacuum forming, and it becomes easy to remove air. In this case, at the time of injection, the torque limit value of the servo motor 10 is reduced or the servo is turned off to perform injection, and the core 4 is moved by the injected resin pressure.
It may be moved to the center left and moved to the position B where the cavity volume is larger than the compression completion position A.

In the above embodiment, an example in which the compression pressure is not changed during the compression process has been described, but the compression pressure may be switched in multiple stages. In this case, for example, the compression pressure may be changed according to the position of the core 4. If it is changed, the compression pressure switching position of each stage and the torque limit value of the compression pressure of each stage are set in the shared RAM 30 in advance, and step S6 of FIG. 1 is performed.
The position of the core 4 (the position of the servo motor 10) is also detected while repeating the process of S7, and the torque limit value is switched to the set torque limit value of the next stage every time the core 4 reaches the switching position of each stage. Good.

[0020]

According to the present invention, since the molten resin is solidified in the mold, the pressure member moving in the mold presses the resin in the mold clamped with the set mold clamping force. The transferability of the molded product is improved, and the dimensional accuracy of the molded product can be improved.

[Brief description of drawings]

FIG. 1 is a processing flowchart of a compression process according to an embodiment of the present invention.

FIG. 2 is a block diagram of an essential part of an injection molding machine that implements the same embodiment.

[Explanation of symbols]

 1 Mold 4 Core 10 Servo Motor 20 Numerical Control Device

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Keno Ueguchi 3-5 Asahigaoka, Hino-shi, Tokyo 1 FANUC CORPORATION Product Development Laboratory (72) Inventor Tetsuaki Neko 3-5 Asahigaoka, Hino-shi, Tokyo 1 Inside FANUC CORPORATION Product Development Laboratory

Claims (1)

[Claims] 1. A molding control method for an injection molding machine, comprising: a pressurizing member that moves in a mold closed by the injection molding machine and pressurizes resin in the mold, and a driving unit that drives the pressurizing member. The injection molding machine is characterized in that the resin in the mold is pressed by a single-stage pressure or a multi-stage pressure set by driving the driving means between the start of injection and the end of pressure holding. Molding control method.