JP4550874B2 - Injection compression molding method or injection press molding method - Google Patents

Description

  The present invention relates to an injection compression molding method or an injection press molding method that performs pressure control by switching from positioning control to pressure control.

  In a compression molding machine that forms a workpiece by performing positioning control and pressure control of the movable member with respect to the fixed member, the fixed member is controlled by positioning control before starting the pressure control or during a part of the time during the pressure control. It is required to control the position and parallelism of the movable member with respect to, and to control the pressure during the pressurization control of the movable member with respect to the other fixed members. As an example of such a compression molding machine, the one described in Patent Document 1 is known. In Patent Document 1, by controlling the position of the ram of the clamping cylinder and the pressure in the clamping cylinder, the thermosetting resin supplied in the mold is heated to give fluidity, and compression stretching and degassing are performed. The present invention relates to a compression molding machine that cures while molding and performs molding. In the compression molding machine, at the time of position control, the pump discharge amount is controlled by load sensing control using a combination of a variable displacement pump and a directional flow control valve. At the time of pressure control, the first half performs fixed control of the pump discharge amount to 10 to 15%, and the second half performs self-holding by the clamping cylinder by confining high-pressure hydraulic oil in the clamping cylinder. .

  Further, as a compression molding machine that forms a molding by performing position / speed control and pressure control of a movable member with respect to a fixed member, a machine described in Patent Document 2 is known. Patent Document 2 relates to an apparatus for plastic processing a plastic material or the like using its plastic deformation characteristics. In Patent Document 2, as shown in FIG. 3, speed control is performed in the latter half of the lowering of the ram, and then pressure control is performed. At the time of pressure control, a fixed displacement pump using an inverter-controlled electric motor is used, and the pressure of the compression cylinder is controlled by feedback control of the rotational speed of the motor and feedback control of the leakage amount from the hydraulic fluid leakage amount adjustment unit. Is adjusted.

  Moreover, in the pressure control device of the press device, the installation space can be reduced by using a small capacity AC servo motor and servo motor driver by controlling the displacement per pump rotation and the rotation speed of the AC servo motor that drives the pump. A device described in Patent Document 3 is known as a low-cost supply.

Registered Utility Model No. 3014863 (Claim 1, Claim 2, FIG. 1, FIG. 2) JP 2003-156005 A (0027, 0041, 0042, FIG. 1, FIG. 2) JP 2001-132651 A (Claim 2, 0015, FIG. 1)

  However, Patent Document 1 has a problem in that the energy efficiency is low because the rotational speed of the motor is constant during positioning control. Further, during the pressure control, when the operating oil pressure rises to the set pressure, there is a problem that the pressure difference is lost and the discharge amount of the pump cannot be controlled. Therefore, in Patent Document 1, in the first half of the pressure control, the discharge amount of the variable displacement pump is fixed, the pressure of the mold clamping cylinder is controlled by a pressure sensor and an electromagnetic relief valve, and the hydraulic pressure of the mold clamping cylinder is set to an arbitrary pressure. Was holding. As a result, a majority of the fixed amount of hydraulic oil discharged from the pump is returned to the tank from the electromagnetic relief valve, which is problematic in terms of energy efficiency. Also, during the second half of the self-holding by the mold clamping cylinder during pressure control, the mold clamping cylinder cannot be controlled to an arbitrary pressure, and the pressure of the mold clamping cylinder gradually decreases due to leakage of hydraulic oil. there were. Moreover, since the thing of patent document 2 uses the fixed pump and adjusts pressure by the amount of leakage of hydraulic fluid at the time of pressure control, there was a problem in the point of energy efficiency.

  Therefore, in the present invention, the compression molding machine that performs the positioning control and pressurization control of the movable member with respect to the fixed member to mold the molding object can be saved energy by using the injection compression molding method or the injection press molding method. It is an object of the present invention to provide an injection compression molding method or an injection press molding method. It is another object of the present invention to provide an injection compression molding method or an injection press molding method capable of improving the accuracy of pressure control during the pressure control.

An injection compression molding method or an injection press molding method according to claim 1 of the present invention is an injection compression molding method or an injection press molding method in which pressure control is performed by switching from a positioning control step to a pressure control step. is to use the cylinder is supplied hydraulic fluid from a pump displacement per revolution by the angle of the swash plate is changed is driving rpm is controlled by a servo motor variable, movable platen stop position The pump is fixed at a large inclination angle when moving up to the position, and in the positioning control process started after the movable plate reaches the stop position, the pump is variably controlled to make it a large inclination angle or a small inclination angle, and the pressurization control process with the time of switching to maintain the pump in a small inclination angle or in a small angle of inclination to the support by using a detection value of the pressure sensor for detecting the pressure of pressure control process sometimes hydraulic oil Wherein the rotational speed or torque of Bomota is closed-loop controlled.

The injection compression molding method or the injection press molding method according to claim 2 of the present invention is the method according to claim 1, wherein the swash plate angle adjusting cylinder is driven by an electromagnetic proportional valve when switching from the positioning control step to the pressurization control step. Then, the swash plate angle of the pump is changed from the large inclination angle to the small inclination angle, and the displacement volume per one rotation of the pump is controlled to be smaller than that in the positioning control process, so that the displacement volume of the pump becomes small. It is controlled.

The injection compression molding method or the injection press molding method according to claim 3 of the present invention is the pressure feedback signal according to claim 1 or 2, wherein the pressure of the hydraulic oil is detected by a pressure sensor during the pressurization control step. The servo motor target rotation speed is calculated from the servo motor control signal generated from the servo motor and the feedback signal in which the rotation speed of the servo motor is detected by the rotary encoder, and the pump rotation speed is closed-loop controlled. Features.

According to a fourth aspect of the present invention, there is provided an injection compression molding method or injection press molding method according to any one of the first to third aspects, wherein the movable mold is positioned and controlled with respect to the fixed mold by the compression cylinder. It is moved by the process , and after forming the cavity, the molten resin is filled from the injection device, and then the pressure control is performed by switching from the positioning control process to the pressure control process.

Injection compression molding method or injection press molding method of the present invention is an injection compression molding method or injection press molding method for performing pressurization control is switched from the positioning control process pressure control step, the swash plate into the compression cylinder By changing the angle, the displacement volume per rotation is variable, and the hydraulic oil is supplied from the pump driven by the rotation speed controlled by the servo motor. When moving to the stop position of the movable plate, the pump is turned on. In the positioning control process, which is fixed at a large inclination angle and started after the movable platen reaches the stop position, the pump is variably controlled to be a large inclination angle or a small inclination angle, and the pump is switched at the time of switching to the pressurization control process . while maintaining a small inclination angle or a small angle of inclination, the rotation of the servo motor by using the detected value of the pressure sensor for detecting the pressure of pressure control process sometimes hydraulic oil Or the torque is to be closed-loop control, in particular become possible to save energy in the time pressurization control. In addition, the accuracy of pressure control during the pressurization control can be improved.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a compression molding machine of the present invention and its control. FIG. 2 is a graph showing the relationship between the servo valve control voltage and the servo motor command voltage of the pump during the positioning control of the present invention.

  A vertical compression molding machine 11 (hereinafter simply referred to as a compression molding machine 11) for thermosetting resin of the present invention will be described with reference to FIG. The compression molding machine 11 is a vertical press molding machine that performs positioning control of a movable member with respect to a fixed member and pressurization control to mold a workpiece. In the compression molding machine 11, a heatable upper die 13 is attached to a fixedly provided upper plate 12, and a movable platen 14 is provided so as to be movable up and down with respect to the upper platen 12, and the movable platen 14 can be heated. A lower mold 15 is attached. A position sensor 16 for detecting the position of the movable board 14 is attached between the upper board 12 and the movable board 14 to indirectly detect the position of the lower mold 15. A ram 18 of a hydraulic cylinder 17 which is a driving means for moving the movable plate 14 up and down is fixed to the movable plate 14.

  The hydraulic cylinder 17 is a backward movement in which both mold closing and mold opening oil chambers are formed so that the lower mold 15 that is a movable member can be moved close to and separated from the upper mold 13 that is a fixed member in the vertical direction. It consists of a type cylinder. The hydraulic cylinder 17 is provided with a mold closing oil chamber (compression oil chamber) 19 to which hydraulic oil is supplied when the ram 18 is raised below the piston portion integrated with the ram 18. A mold opening oil chamber 20 to which hydraulic oil is supplied when the ram 18 is lowered is provided above the part.

  Although details of the hydraulic circuit are omitted, a servo valve 21 capable of supplying hydraulic oil to both the mold closing oil chamber 19 and the mold opening oil chamber 20 of the hydraulic cylinder 17 is provided. The A port of the servo valve 21 is connected to the mold closing oil chamber 19, the B port is connected to the mold opening oil chamber 20, the P port is connected to a pump 22 described later, and the T port is connected to a tank 23. The servo valve 21 includes various directional flow rate proportional valves in which the valve drive unit 21a is controlled by a closed loop to control the valve position.

  A pump 22 is disposed in the tank 23. In this embodiment, the pump 22 is a one-way discharge pump driven by a servo motor 24. The pump 22 is an axial type piston pump (variable displacement pump), and the displacement per pump rotation can be changed by changing the angle of the swash plate. A swash plate angle adjusting cylinder 25 as swash plate angle adjusting means is attached to the pump 22, and the swash plate angle adjusting cylinder 25 is operated by a pilot pressure (not shown) by excitation of an electromagnetic proportional valve 26. ing. Further, a rotary encoder 27 that detects the number of rotations of the pump 22 is connected to the servo motor 24 that is a driving means of the pump 22. The discharge port of the pump 22 is connected to a pressure sensor 28 that detects the pressure of hydraulic oil at least during pressurization control.

  In the pump 22 of the present invention, the swash plate may be provided with detection means for detecting the angle, and the angle of the swash plate may be controlled by a closed loop. The pump 22 may be another type of variable displacement pump or fixed displacement pump as long as it is driven by a servo motor 24. The pressure detection during pressurization control may be such that the pressure of the hydraulic fluid in the mold closing oil chamber 19 is directly detected. Furthermore, the pressure detection may be such that the pressure applied by the lower die 15 that is a movable member with respect to the upper die 13 that is a fixed member is detected by pressure detection means such as a load cell.

  Next, the control of the compression molding machine 11 will be described with reference to FIGS. 1 and 2, focusing on the positioning control process (during positioning control) and the pressurization control process (during pressurization control). When the thermosetting resin which is a molding object is supplied to the lower mold | type 15 by the raw material supply apparatus which is not shown in figure, a movable plate raising process is started next. In the movable plate raising step, the discharge amount from the pump 22 is maximized to move the movable plate 14 at a high speed, and the movable plate 14 is moved at a low speed immediately before the positioning stop position.

  When the position sensor 16 detects that the movable platen 14 has reached the stop position, a signal is sent from the sequence control unit 30 of the control device 29 to the servo valve setting unit 31 and the pump setting unit 32 to start the positioning control process. Is done. The purpose of this positioning control process is to stop the movable plate 14 and the lower mold 15, which are heavy objects, for a certain period of time at a stop position where the mold is slightly opened with respect to the upper mold 13, and the thermosetting resin supplied to the lower mold 15. Is heated to a fluid state. In the positioning control step, a position / speed command signal targeting the stop position is sent from the servo valve setting section 31 to the position / speed control section 33. The position / speed command signal is matched with the position feedback signal detected by the position sensor 16 in the adder 34 to obtain a position deviation, and is sent to the position / speed control unit 33 as a corrected position / speed command signal. Then, a servo valve control voltage (servo valve control signal) 35 obtained by the feedback signal from the position sensor 16 is generated in the position / velocity control unit 33 and sent to the current generation unit 36. Then, power is amplified in the current generator 36, and the operating current is sent toward the valve drive unit 21a that operates the sprue of the servo valve 21.

  During the positioning control process, the pump 22 is controlled based on the servo valve control voltage 35. Specifically, the servo valve control voltage 35 is sent from the position / speed control unit 33 to the pump setting unit 32 as a pump control signal 37 during positioning control. The pump setting unit 32 generates a servo motor command voltage (servo motor command signal) 38 for driving the pump 22 from the pump control signal 37 and sends it to the servo amplifier 41. In the servo amplifier 41, the servo motor drive current is amplified in power and the servo motor 24 is driven. The rotational speed of the servo motor 24 is detected by the rotary encoder 27 and sent from the rotary encoder 27 to the servo amplifier 41 as a position / speed feedback signal. Then, the servo amplifier 41 is controlled so that the rotation speed of the servo motor 24 becomes a target rotation speed based on the servo motor command voltage 38. Therefore, in the positioning control process, the servo motor command voltage 38 calculated based on the servo valve control voltage 35 performs open loop control of the rotation speed of the servo motor 24 to control the discharge amount of the pump 22, and the pressure of the pressure sensor 28. The closed loop for performing the control for detecting the amount of discharge and controlling the discharge amount of the pump 22 is not performed.

A specific calculation formula for calculating the servo motor command voltage 38 for driving the pump 22 based on the servo valve control voltage 35 at this time is as follows:
Servo motor command voltage = A × | servo valve control voltage | + Expression of offset voltage. Therefore, the servo motor command voltage 38 is a voltage calculated by multiplying the absolute value of the control voltage (within ± 10V) to the servo valve 21 by the coefficient value A and adding the offset voltage thereto. In the present embodiment, when the servo valve control voltage 35 to the servo valve 21 is ± 10 V (b and c in FIG. 2), a proportional expression is used in which the servo motor command voltage 38 is 5 V (d in FIG. 3). It is done. Further, the offset voltage is set to 1V, and when the servo valve control voltage 35 is 0V (a in FIG. 3), the discharge amount of the hydraulic oil from the pump 22 is controlled so as not to become zero. As for the servo valve control signal used when the servo motor command signal is calculated, the control voltage (V) is used in this embodiment, but the calculation is performed using the current value (A) for operating the valve drive unit 21a. May be.

  As a result of performing the positioning control, the position of the lower mold 15 is positioned at the stop position while being slightly corrected in the vertical direction. In this embodiment, the swash plate of the pump 22 in the positioning control is fixed at a large inclination angle continuously from the movable plate raising process. However, depending on circumstances, the swash plate of the pump 22 may have a small inclination angle or may be variably controlled.

  When the timer of the sequence control unit 30 detects that a certain time has elapsed since the start of the positioning control process, the positioning control process is ended, and the ram 18 of the hydraulic cylinder 17 is moved slowly according to the determined speed. 14 is raised, and the lower mold 15 and the upper mold 13 are closed.

  When the position sensor 16 detects that the lower mold 15 and the upper mold 13 are closed, a signal is sent from the sequence control unit 30 of the control device 29 to the servo valve setting unit 31 and the pump setting unit 32 to add A pressure control process is started, and the thermosetting resin in a fluid state is compressed and shaped. In the pressurization control step, the valve position of the servo valve 21 is controlled from the servo valve setting unit 31 to the position / speed control unit 33 so that hydraulic oil from the pump 22 is continuously supplied to the mold closing side oil chamber. A command signal is sent. A control current is sent to the valve drive unit 21a of the servo valve 21 via the position / speed control unit 33 and the current generation unit 36, and the A port and the P port of the servo valve 21 are connected by the operation of the valve drive unit 21a. Is done. At this time, position feedback control based on the position sensor 16 is not performed.

  At the same time, the electromagnetic proportional valve 26 is excited by the signal from the pump setting unit 32 of the control device 29 and the swash plate angle adjusting cylinder 25 is driven, and the swash plate angle of the pump 22 is changed from the large inclination angle to the small inclination angle. Thus, the displacement per pump rotation (per servo motor rotation) is reduced. In this embodiment, the displacement per pump rotation in the pressurization control process is controlled to be 37.5% of the displacement in the positioning control process. In addition, a servo motor command voltage 38 is transmitted from the pump setting unit 32, the number of revolutions of the servo motor 24 is controlled, and the discharge amount of the pump 22 is controlled. At this time, the pressure of the hydraulic oil discharged from the pump 22 is detected by the pressure sensor 28 and sent to the adder 39 as a pressure feedback signal to obtain a deviation from the servo motor command voltage 38, and pressure control as the correction command voltage. Sent to the unit 40. In the pressure control unit 40, a servo motor control voltage (servo motor control signal) is generated and sent to the servo amplifier 41. The rotational speed of the servo motor 24 is detected by the rotary encoder 27 and sent from the rotary encoder 27 to the servo amplifier 41 as a position / speed feedback signal. Then, the servo amplifier 41 amplifies the power so that the rotation speed of the servo motor 24 becomes a target rotation speed based on the control voltage generated by the pressure control unit 40, and a drive current is sent to the servo motor 24. In this embodiment, closed loop control is performed so that the torque of the servo motor 24 is always constant at this time.

  Then, the rotational speed of the pump 22 is controlled by the pressure sensor 28, the servo motor 24, etc., and the displacement per pump rotation is controlled to be smaller than that in the positioning control process. In addition, highly accurate pressure control is realized in the pressurization control process. In this embodiment, in the pressurization control step, the rotation speed (discharge amount) of the servo motor 24 is controlled, but the torque (discharge pressure) of the servo motor 24 or both the rotation speed and torque of the servo motor 24 are controlled. It may be controlled.

  In this embodiment, the degassing control step for slightly opening the lower mold 15 to remove the volatile gas generated from the thermosetting resin that is the molding object is performed once or a plurality of times. The pressure control process is stopped and the positioning control process is performed again. When the degassing control process is completed, the pressurization control process is performed again. Next, when the thermosetting resin as the molding is completed, a mold opening process is performed. In the mold opening process, low speed mold opening is initially performed, and then high speed mold opening is performed, and then the mold is opened by being decelerated before the mold opening is stopped.

  In the present embodiment, an example of the vertical compression molding machine 11 for thermosetting resin has been described as a compression molding machine that performs positioning control and pressurization control of the movable member with respect to the fixed member to mold the molding target. The object to be molded is not limited to a thermosetting resin. In the compression molding machine of the present invention, a plurality of movable hot plates that are movable members are moved upward relative to a fixed hot plate that is a fixed member fixed to the upper board, and the movable hot plate between the fixed hot plate and the movable hot plate is movable. It may be a hot press apparatus that performs positioning control of the movable hot plate and pressurization control to the laminated molded product between the hot plates. Furthermore, the compression molding machine of the present invention moves the movable mold, which is a movable member disposed on the movable plate, relative to the fixed mold, which is a fixed member disposed on the fixed plate, and performs positioning control to move the cavity. It is also possible to use injection compression molding or an injection press in which a molten resin is filled from an injection device and pressurization is controlled thereafter. In that case, it is not limited to the vertical type, and the movable member may be moved in the horizontal direction. Further, the compression cylinder is not limited to one, and a compression cylinder may be provided on each tie bar. In the above description, the target position of the movable member at the time of positioning control is changed with the passage of time, and the movable member is moved at a lower speed than at the time of the mold closing high speed movement.

  The present invention is not enumerated one by one, but is not limited to the above-described embodiment, and it goes without saying that the present invention can be applied to those modified by a person skilled in the art based on the gist of the present invention.

It is a block diagram which shows the compression molding machine of this invention, and its control. It is a graph which shows the relationship between the servo valve control voltage at the time of positioning control of this invention, and the servomotor command voltage of a pump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Vertical compression molding machine for thermosetting resins 12 Upper board 13 Upper mold 14 Movable board 15 Lower mold 16 Position sensor 17 Hydraulic cylinder 18 Ram 19 Mold closing oil chamber 20 Mold opening oil chamber 21 Servo valve 21a Valve drive Section 22 Pump 23 Tank 24 Servo motor 25 Swash plate angle adjustment cylinder 26 Proportional solenoid valve 27 Rotary encoder 28 Pressure sensor 29 Controller 30 Sequence control section 31 Servo valve setting section 32 Pump setting section 33 Position / speed control section 34, 39 Addition 35 Servo valve control voltage 36 Current generator 37 Pump control signal during positioning control 38 Servo motor command voltage 40 Pressure controller 41 Servo amplifier

Claims (4)

An injection compression molding method or an injection press molding method for performing pressure control by switching from a positioning control step to a pressure control step ,
Hydraulic oil is supplied to the compression cylinder from a pump driven by changing the angle of the swash plate so that the displacement per rotation is variable and the rotation speed is controlled by a servo motor.
When the movable platen is moved to the stop position, the pump is fixed at a large inclination angle, and in the positioning control process that starts after the movable platen reaches the stop position, the pump is variably controlled to have a large inclination angle or a small inclination angle, At the time of switching to the pressurization control process , while maintaining the pump at a small inclination angle or a small inclination angle,
An injection compression molding method or an injection press molding method, wherein the rotation speed or torque of the servo motor is closed-loop controlled using a detection value of a pressure sensor that detects the pressure of hydraulic oil during the pressurization control step . When switching from the positioning control step to the pressure control step ,
The swash plate angle adjustment cylinder is driven by the electromagnetic proportional valve, and the swash plate angle of the pump is changed from a large tilt angle to a small tilt angle.
2. The injection compression molding method according to claim 1, wherein the displacement of the pump is controlled so as to be smaller than that during the positioning control step so that the displacement of the pump is reduced. Injection press molding method. During the pressure control step ,
The target rotational speed of the servo motor is calculated from the servo motor control signal generated from the pressure feedback signal in which the hydraulic oil pressure is detected by the pressure sensor and the feedback signal in which the rotational speed of the servo motor is detected by the rotary encoder. 3. The injection compression molding method or the injection press molding method according to claim 1, wherein the number of rotations of the pump is closed-loop controlled. The movable mold is moved with respect to the fixed mold by the compression cylinder in the positioning control process , and after forming the cavity, the molten resin is filled from the injection device, and then the pressure is switched from the positioning control process to the pressure control process. The injection compression molding method or the injection press molding method according to any one of claims 1 to 3, wherein control is performed .

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