KR960016030B1 - Method and apparatus for injection compression molding - Google Patents

Abstract

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Description

[Name of invention]

Injection compression molding method and apparatus

[Brief Description of Drawings]

1 is a flowchart of a control program for melt resin compression control information writing process and torque limit value setting process in an injection compression molding method according to an embodiment of the present invention.

2 is a flowchart of a control program for executing pulse distribution processing for two axes in parallel in the injection compression molding method according to the embodiment.

3 is a schematic diagram showing in block form a part of the main portion of the electric injection compression molding machine to which the injection compression molding method according to the embodiment is applied.

Detailed description of the invention

[Technical Field]

The present invention provides an injection compression molding method capable of precisely controlling the compression force on the molten resin injected into the mold of the electric injection compression molding machine to uniformly fill the molten resin into the mold, and to produce a high quality molded article with good reproducibility. To the device.

[Background]

It is well known that injection compression molding is performed to compress the molten resin injected into the mold to evenly spread the molten resin to the details of the mold cavity to improve the dimensional accuracy of the molded article and to make the density of the molded article uniform. Injection compression molding typically drives a compression pin provided in a clamp mechanism of a hydraulic injection molding machine by a compression mechanism at the end of the injection to the mold from the movable platen and presses the melted resin filled in the mold with the compression pin. Is done. However, according to the conventional apparatus for driving the compression pin by the compression mechanism, mainly due to the change in the characteristic of the hydraulic oil of the hydraulic mechanism due to the change of the injection molding machine temperature, the driving force and the moving position of the compression pin on the compression pin melt. Since it is difficult to control the compressive force exerted on resin precisely and reproducibly, the quality of a molded article arises.

[Initiation of invention]

An object of the present invention is to provide an injection compression molding method and apparatus for producing a high quality molded article with high reproducibility.

According to one aspect of the present invention, there is provided an injection compression molding method applied to an injection molding machine for controlling a servo motor of each axis by a numerical control processing device and controlling various operation parts by a programmable, machine, and controller. do. The injection compression molding method includes a step (a) of determining whether a melt resin compression operation start condition is established and a melt resin compression operation command from the programmable controller, the numerical controller to the numerical control processor when the start condition is established. And (b) outputting information for specifying an axis for melt resin compression and information for melt resin compression control, and a pulse control for the specified axis according to the command and based on the control information. And (d) controlling the output torque of the servo motor relating to the specified axis so that the compression force actually applied to the molten resin becomes a set value during the step (c) to be executed by the step (c) and during the step (c). Equipped.

According to another aspect of the present invention, an electric injection compression molding machine includes a numerical control processor for driving control of a servo motor on each axis, a programmable machine, a controller, and a controller for sequence control of various operating parts of the molding machine. Storage means accessible from both the control processing device and the programmable machine, controller, pressure detection means for detecting the compressive force actually applied to the molten resin, axis for melt resin compression, information for melt resin compression control, melt resin Means for setting a compression force to be applied to the start timing of the melt compression operation and a torque limit means for limiting an output torque corresponding to the axis for melt resin compression in the servo motor; , The machine and the controller, upon reaching the compression operation start timing, And means for outputting, to said storage means, information for specifying the axis for compression of the melted resin and information for compression control for the melted resin, wherein the numerical control processing apparatus is configured to perform pulse distribution on the axis for compression of the melted resin. Output of the servo motor related to the axis for compression of the molten resin so that the compression force actually applied to the molten resin becomes the set compression force while being executed according to the compression operation command and in accordance with the information for the compression control for the molten resin. To control the torque.

As described above, according to the present invention, when the melt resin compression operation start condition is satisfied, information on the axis for melt resin compression output from the programmable controller, the machine and the controller, information for melt resin compression control, and melt resin compression operation command The output torque of the servo motor related to the axis for melt resin compression is set so that the pulse control is performed for the axis for melt resin compression by the numerical control processing device, and the compression force actually applied to the melt resin becomes a set value. Since it is controlled, the molten resin compression operation can be performed precisely to produce a molded article of high quality and little variation.

Best Mode for Carrying Out the Invention

The electric injection molding machine to which the injection compression molding method according to an embodiment of the present invention is applied is a servo motor for performing various operations such as injection, metering, kneading, mold heating, mold closing, molding machine, and ejecting a molded article. A movable and stationary platen 3 and 4 and a servo motor for clamping shafts having various operating parts driven, for example, mounted with the mold half parts 1 and 2, respectively, as shown in FIG. Mold) is inserted into the heating cylinder 6 and is axially driven by the injection servo motor 7 through a rotational / linear motion converter mechanism (not shown), An injection mechanism including a screw 5 which is rotationally driven by a dedicated servo motor, and an ejector (not shown) are provided.

In addition, in order to apply a compressive force to the molten resin injected into the mold cavity (not shown) which is formed by the mold halves 1 and 2 during or after the injection process by the injection servo motor 7. For example, a molten resin compression pin (not shown) disposed as a protruding material in the mold cavity is supported by the movable platen 3 as a reciprocating material, and the pin is a rotary motion / linear motion converter mechanism 9 It is connected to the servo motor 8 for melt compression. Both elements 8, 9 are formed on the movable platen 3. Then, a pressure detector, for example, a load cell 9a for detecting the melt resin compressive force, is mounted, for example, by a linear motion member (not shown) of the converter tool 9. Moreover, it is not necessary to necessarily provide the dedicated compression servo motor 8, For example, the ejector servo motor may simultaneously have a function as a servo motor for molten resin compression.

Reference numeral 20 denotes a numerical control device (hereinafter referred to as an NC device) for controlling the operation of the injection molding machine, and the NC device 20 is a central processing unit (hereinafter referred to as a CPU) for numerical control ( 21) and a CPU 22 for a programmable, machine, and controller (hereinafter referred to as PMC). The NC CPU 21 is connected via a bus ROM (24) storing a control program for controlling the injection molding machine as a whole, a RAM 25 used for temporary storage of data, and a servo interface 26. In the servo interface 26, only the servo circuits for driving control of the servo motors of the respective axes (the servo circuits of the injection and compression servo motors 7 and 8 are indicated by reference numerals 27a and 27b). Each servo circuit is connected to a position detector formed in the corresponding servo motor, for example, a pulse coder (not shown), and the injection to the PMC CPU 22 is performed. ROM 28 which stores a sequence program for controlling the sequence operation of the molding machine and the like and a RAM 29 which is used for temporary storage of data during arithmetic processing by the CPU 22 are connected via a bus. .

A shared RAM 30, an input circuit 31, and an output circuit 32 are connected to a bus avita controller (hereinafter referred to as BAC) 23 connected to both CPUs 21 and 22 via a bus. In addition, a manual data input device (hereinafter referred to as CRT / MDI) 34 having a CRT display device is connected through the operator panel controller 33. The shared RAM 30 is composed of a nonvolatile memory capable of reading and writing a bubble memory, a CMOS memory, and the like, and for example, various setting values and parameters for determining an NC program and injection molding conditions for controlling the operation of the injection molding machine. And macro variables. The input circuit 31 is connected to various sensors (not shown) formed on the load cell 9a and the injection molding machine via the A / D converter 10. The output circuit 32 is connected to various actuators (not shown) of the injection molding machine, and is connected to the servo circuit 27b corresponding to the servo motor 8 for compression in order to perform the torque control described later. 35).

Hereinafter, the operation of the injection molding machine configured as described above will be described. First, information specifying the axis (step transfer shaft) for melt compression and control information (transfer direction, target transfer position (target transfer amount)), transmission speed and compression force (surge in melt compression) for performing the melt compression process Various injection molding conditions (including torque limit values) for limiting the beam motor output torque) are set by the operator via the CRT / MDI 34, and these setting conditions are stored in the shared RAM 30.

After the injection molding condition is set, when the injection molding machine is operated, the NC apparatus 20 controls the injection molding machine according to the sequence program stored in the ROM 28 and the NC program stored in the shared RAM 30 to close the mold, The injection molding operation consisting of a series of processes such as molding, injection, compression, packing, cooling, weighing kneading, mold heating, and ejecting a molded article is repeatedly performed to manufacture a molded article. The NC CPU 21 performs the processing shown in FIG. 2 at predetermined intervals in each injection molding operation.

That is, when the NC CPU 21 receives an instruction from the PMC CPU 22, the NC CPU 21 reads one block of the part corresponding to the instruction of the NC program from the shared RAM 30, and the control described in the block. The pulse distribution amount for one pulse distribution period calculated in accordance with the contents is output to the servo circuit associated with the axis designated by the program via the servo interface 26 (step S 200). Next, it is determined whether or not the melt resin compression mode (step mode) is performed (step S 201). If it is not the step mode, it is determined whether the pulse distribution for the axis designated by the program is completed (step S 208). Then, the loops of steps S 200, S 201 and S 208 are repeatedly executed until the pulse distribution is completed, and when the pulse distribution is completed, the process proceeds to step S 209 to perform the same processing as described above for the next block of the NC program. Run

On the other hand, the PMC CPU 22 executes the control operation in accordance with the sequence program stored in the ROM 28. That is, as shown in FIG. 1, the PMC CPU 22 writes the injection start instruction into the shared RAM 30 through the BAC 23, and at the same time determines the start timing of the melt resin compression operation. The timer T starts (steps S 100 and S 101). At this time, the NC CPU 21 performs pulse distribution to the servo circuit 27a related to the injection servo motor 7 according to the injection start instruction as described above. The timer time is set at a time corresponding to the injection time, for example, almost equal to or shorter than the injection time.

When the timer T times up at the end of the injection process or during execution of the injection process (step S102), the PMC CPU 22 together with the melt resin compression operation command (step mode command) in a predetermined address area of the shared RAM 30. Information specifying the above step transmission shaft and control information for the melt resin compression step are written (step S 103).

When the step mode instruction is written to the shared RAM 30, the NC CPU 21 determines that the step mode is selected in step S 201 of FIG. 2, and determines whether or not the manual transfer flag indicating the step mode is present. It judges (step S202). If the manual transmission flag is not standing, the flag is set (S203). That is, the manual transfer flag is set in the program execution cycle immediately after the step mode command is written in the shared RAM 30. The CPU 22 for PMC then reads the control information for the melt resin compression process written in the predetermined address area of the shared RAM 30 by the CPU, and calculates the amount of distribution of the step transmission shaft for one program execution cycle. The calculated value is stored in the shared RAM 30. The NC CPU 21 distributes pulses to the servo circuit, for example, the servo circuit 27b, for driving control of the servo motor associated with the step transmission shaft based on the calculated memory value (step S205). As a result, for example, the compression servo motor 8 is rotated in the rotational direction and rotational speed corresponding to the transmission direction and the transmission speed, and accordingly compression is connected to the linear motion member (not shown) of the exchanger 9. A pin (not shown) gradually protrudes from the mold cavity to start compression of the molten resin injected into the cavity.

The NC CPU 21 determines whether or not pulse distribution to the target transmission position has been completed for the step transmission axis (step S206). If this pulse distribution is not completed, the axis designated in the NC program, for example, It is determined whether pulse distribution to the injection shaft for holding pressure or injection is completed (step S208). If the pulse distribution is not finished, the loop of steps S 201, S 202, S 205, S 206, and S 208 is repeatedly executed. In other words, the pulse distribution for both the axis specified in the NC program and the axis (step transmission shaft) specified for the melt resin compression is executed in parallel. As a result, for example, while the injection or holding pressure operation | movement by the injection servo motor 7 or the metering operation | movement by a screw rotation servo motor (not shown) is performed, for example, a compression servo motor The melt resin compression operation according to (8) is performed.

During this melt resin compression operation, the PMC CPU 22 displays the torque limit value TLS (upper limit value of the output torque of the servo motor related to the step transmission shaft) in the compression process set in the shared RAM 30. ), And through the output circuit 32 and the D / A converter 35, to the servo circuit associated with the servo motor corresponding to the step transmission shaft, for example, to the servo motor 8 for compression. The set torque limit value is output to the servo circuit 27b (step S 104 in FIG. 1). Then, through the input circuit 31 and the A / D converter 10, a feedback signal indicating the pressure PF supplied from the pressure detector, for example, the load cell 9a and actually applied to the molten resin, (Step S105), this is compared with the set torque limit value TLS (step S106). If the feedback pressure PF is smaller than the set torque limit value TLS, for example, the torque limit value TLS outputted to the servo circuit 27b is increased by a predetermined value? If large, it decreases by (DELTA) (alpha) (step S107, S108). If the feedback pressure PF is equal to the value TLS, the flow advances to step S109 without changing the set torque limit value and determines whether or not it reaches the target step transfer position. In this way, by controlling the compression force applied to the molten resin while changing the set torque limit value as necessary, the actual compression force is compensated while compensating for the control error caused by the change of time in the melt compression system of the injection molding machine. Control by the set value. In addition, the matching accuracy between the set value TLS and the feedback value (actual value) PF varies depending on the resolution capability of the A / D converter 10 and the D / A converter 35.

When the pulse distribution to the target transmission position to the step transmission axis is completed (step S206 in FIG. 2), the NC CPU 21 lowers the manual transmission flag, resets the step mode, and then reaches the step transmission position. Is written into the shared RAM 30 (step S207). When the step transfer position arrival signal is written into the shared RAM 30 (step S109 of FIG. 1), the PMC CPU 22 ends the compression operation.

As described above, the melt resin compression operation is precisely performed during the injection, holding operation or metering operation, and a molded article of high quality and little variation is produced.

Claims (8)

(A) determining whether or not melt compression start operation conditions have been established; and when the start conditions are established, programmable, machines, controllers for controlling sequence of various operation parts of the injection molding machine, (B) outputting a melt resin compression operation instruction, information for specifying an axis for melt resin compression, and information for melt resin compression control to a numerical control processing apparatus for driving control of a beam motor, and The step (c) of performing pulse distribution in accordance with the command and based on the control information by the numerical control processing device, and during the execution of the step (c), the specification such that the compressive force actually applied to the molten resin becomes a set value. An injection compression molding method comprising the step (d) of controlling the output torque of the servo motor related to the rotated shaft. The injection compression molding method according to claim 1, wherein in step (c), the pulse distribution for the specified axis is performed in parallel with the pulse distribution for an axis different from the specified axis. The injection compression according to claim 1, wherein in the step (a), the molten resin compression operation start condition is satisfied when a predetermined time determined according to the injection time has elapsed from the start of the injection operation of the injection molding machine. Molding method. The injection molding apparatus according to claim 1, wherein the information for controlling the melt resin compression includes a torque limit value indicating an upper limit of a transmission amount, a transmission speed and a transmission direction of the specified axis, and an output torque of the servo motor associated with the specified axis. Compression molding method. Numerical control processing device for driving control of servo motor of each axis, programmable, machine, controller for sequential control of various operation parts of the molding machine, and access from both of the numerical control processing device and the programmable, machine, controller Possible storage means, pressure detection means for detecting the compressive force actually applied to the molten resin, the axis for melt compression, information for the melt compression control, the compression force to be applied to the melt and the timing of the start of the melt compression operation Means for setting the torque control unit and torque limiting means for limiting the output torque of the shaft corresponding to the axis for melt resin compression in the servo motor. To the melt compression operation command and the set axis for Means for outputting information to the storage means, and information for melt resin compression control, wherein the numerical control processor performs pulse distribution for the specified axis in accordance with the compression operation command and based on the control information. And an electric injection compression molding machine which controls the output torque of the servo motor related to the axis for the molten resin compression so that the compression force actually applied to the molten resin becomes the set compression force. 6. The electric injection compression molding machine as set forth in claim 5, wherein said numerical control processor performs pulse distribution for said specified axis in parallel with pulse distribution for an axis different from that specified axis. The injection compression molding machine according to claim 5, wherein the compression operation start timing setting means is a timer. The said melt resin compression control information includes a torque limit value for indicating a transmission amount, a transmission speed and a transmission direction of said specified axis, and an upper limit of an output torque of a servo motor associated with said specified axis. Injection compression molding machine.

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