JPH0852778A - Mold-compression molding method and process - Google Patents

Abstract

PURPOSE:To control an injection filling process with a high accuracy while efficiently controlling the changeover timing to a mold compression process by controlling the driving part of an injection mechanism and the start of mold compression on the basis of the output signal of the power sensor provided to the rod receiving part of a platen interfacial distance adjusting mechanism. CONSTITUTION:Four fixed adjusting units 13 are provided to the platen interfacial distance adjusting mechanism 11 mounted on a mold clamping device 1 corresponding to respective movable adjusting units 12. A plurality of rod receiving parts 29 coming into contact with respective adjusting rods 14 and load sensors 30 detecting the contact pressures of the adjusting rods 14 coming into contact with the rod receiving parts 29 are provided to the fixed adjusting units 13. An injection control unit 55 and a timing control unit 56 are controlled on the basis of the detection signals from the respective load sensors 30 to control a mold clamping force control unit 32 and a speed servo control unit 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold compression molding method and apparatus, and is capable of controlling the filling state, the mold internal pressure and the timing of the start of mold compression in the injection filling process with high accuracy. A method and apparatus.

[0002]

2. Description of the Related Art As a method of controlling an injection filling process when performing injection compression molding, for example, a pressure sensor is incorporated in a molding die and a change in the mold pressure due to injection filling is detected via the pressure sensor. However, it is known to perform switching control to the injection amount and the mold compression process using the detected signal as a control parameter. As another method, for example, a change in the drive system of the injection mechanism, for example, a hydraulic change in the case of hydraulic drive is used as a control parameter, but the detection response speed is slow when compared with the former pressure sensor method. Therefore, the control accuracy is said to be inferior.

[0003]

In the mold compression process in injection compression molding, the mold compression speed and displacement are also extremely small, so it is extremely important to control the injection filling process, which is the preceding process, with high accuracy. is there. On the other hand, in the above conventional method, since the detection signal of the pressure sensor is used as the control parameter, the following problems occur.

(1) Since it is a detection means in a local area, the pressure inside the mold greatly differs depending on the location, and the pressure difference due to the detection position is large, and the injection filling behavior inside the molding mold is detected. Is difficult to do. Therefore, it is difficult to control the injection filling process with high accuracy.

(2) Since the arrival time of the injection filling material varies depending on the detection position, an error occurs in the detection response speed. Therefore, correction of the time factor is required, and continuous control over the entire injection filling process is difficult.

(3) In addition to the complicated work such as mounting and removing the pressure sensor and calibrating the detection signal for each different molding die, the pressure sensor is mounted on the molding die. Processing is also required. Therefore, the cost becomes high and the productivity is deteriorated.

The present invention has been made in view of the above problems, and a mold compression molding method capable of controlling the injection filling process with high accuracy and efficiently controlling the timing of switching to the mold compression process. And a device.

[0008]

[Means for Solving the Problems] A movable platen is provided with a mold clamping mechanism for generating a forward / backward movement and a mold clamping force, and
Mechanical platen face-to-face distance adjustment with a movable platen and a fixed platen, an adjusting rod, a rod adjusting unit having a prime mover for moving the adjusting rod forward and backward, and a rod feed mechanism, and a rod receiving unit having a force sensor. Using a mold clamping device for mold compression molding equipped with multiple mechanisms, the injection filling process control is based on the output signal of the force sensor or based on the current value of the drive system of the prime mover. The method and apparatus control the start of the compression process.

[0009]

[Operation] In the injection filling process, the molding die is separated by the mold opening force (F1) corresponding to the detection signal (F2) from the force sensor and the mold internal pressure (P1) showing the behavior of the filling material due to the injection filling and the injection filling. The relationship between the mold clamping force generated by the mold clamping mechanism in order to prevent this, that is, the mold clamping force (F0) for maintaining the mold compression amount is F0 = F1 (= P1) + ΣF2
Becomes That is, the mold internal pressure (P
1) Measure the amount of change in the detection signal from the force sensor (F2)
By performing the function of detecting by, the drive unit control of the injection mechanism and the start control of the mold compression are performed based on the detection signal (F2) from the force sensor, thereby detecting the filling behavior and the timing control of the mold compression. Can be performed with high precision.

Further, in the mold compression process, the detection signal (F2) from the force sensor, the mold clamping force (F0) generated by the mold clamping mechanism, and the mold internal pressure (P1) which changes according to the mold compression process.
The relationship of the mold compression force (F'1) corresponding to is F0 = F'1
(= P1) +. SIGMA.F2, and by controlling the moving speed of the adjusting rod and controlling the mold clamping force (F0) of the mold clamping mechanism based on the detection signal (F2) from the force sensor, the mold compression in the mold compression molding is performed. Speed and mold compression force (F'1 =
P1) Control can be performed with high accuracy.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a vertical injection compression molding apparatus or a mold compression molding apparatus. The mold clamping device 1 is provided with a movable platen 3 that holds a movable mold 2 that is also an upper mold of a mold for compression molding, and a fixed platen 5 that holds a fixed mold 4 that is also a lower mold, and is movable. The mold clamping cylinder 6 that moves the platen 3 vertically with respect to the fixed platen 5 and presses the movable platen 3 toward the fixed platen 5 to clamp between the movable mold 2 and the fixed mold 4 is a cylinder support member 8. It is attached to and installed in.

Columns 7 project from the four corners of the upper surface of the fixed platen 5, as shown in FIG. Further, the cylinder support member 8 is provided on the upper ends of the four columns 7.
Has been fixed. The mold clamping cylinder 6 is fixed downward at the center of the cylinder support member 8. The mold clamping cylinder 6 may be divided into a plurality of mold clamping cylinders 6 having an ability according to the number of divisions.

The mold clamping device 1 is provided with a platen surface distance adjusting mechanism (hereinafter referred to as a platen adjusting mechanism) 11 for adjusting the attitude of the movable platen 3 to a state in which the movable platen 3 has an arbitrary position and angle with respect to the fixed platen 5 side. It is installed. This platen adjusting mechanism 11 is mounted on the movable platen 3 side 4
One movable adjustment unit 12 and four fixed adjustment units 13 mounted on the fixed platen 5 side and provided corresponding to each movable adjustment unit 12 are provided. The movable adjustment units 12 are arranged inside the four columns 7 as shown in FIG.

Further, in each movable side adjusting unit 12, as shown in FIG. 3, the adjusting rod 14 mounted on the movable platen 3 so as to be movable in the vertical movement direction of the movable platen 3.
And a ball screw type feed mechanism 15 for driving the adjusting rod 14 along the movement direction of the movable platen 3.

Here, the adjusting rod 14 is provided with a male screw-shaped screw shaft portion 16 forming a ball screw on the upper side and a spline shaft portion 17 on the lower side. Further, the ball screw type feed mechanism section 15 is provided with a ball screw section 18 and a spline bearing section 19 fixed to the movable platen 3, and a drive motor 20 for rotationally driving the adjusting rod 14. There is. The adjusting rod 14 may have a rack and pinion configuration instead of the ball screw configuration, and the same effect can be obtained.

A unit mounting plate 22 is fixed to the upper side of the movable platen 3. This unit mounting plate 22
Guide shafts 23 are respectively provided at the four corners of the above.
A guide plate 24 for holding the speed reducer 21 is vertically movably attached to the four guide shafts 23. The drive motor 20 is attached to the guide plate 24 via a motor attachment member 25.

When the drive motor 20 is driven, the drive motor 2
The rotational force from 0 is transmitted to the screw shaft portion 16 of the adjusting rod 14 in a state of being decelerated by the speed reducer 21, and as the screw shaft portion 16 rotates, a screw operation along the ball operation of the female screw portion in the ball screw portion 18 is performed. The screw shaft portion 16 itself is vertically moved by the advancing operation. At this time, adjusting rod 1
4, the guide plate 24 has four guide shafts 23
Driven in the vertical direction along with, the drive motor 20 and the speed reducer 21 are moved up and down together with the adjusting rod 14.

Further, the screw shaft portion 1 of the adjusting rod 14
As shown in FIG. 5, the lower end portion of 6 is a compound type thrust ball bearing 2
An end portion of the spline shaft portion 17 is connected via a bearing box 28 in which 7 is incorporated. The double thrust ball bearing 27 in the bearing box 28 absorbs the rotational movement of the screw shaft portion 16 of the adjusting rod 14, and only the moving movement thereof is transmitted to the spline shaft portion 17 side so that the spline shaft portion 17 is splined. The bearing portion 19 is guided to move up and down.

As shown in FIG. 4, the fixed-side adjusting unit 13 is provided with a plurality of rod receiving portions 29, which are arranged facing each other with respect to each adjusting rod 14 and are in contact with each adjusting rod 14, respectively. A load sensor (pressure detection means) 30 that detects the contact pressure of each adjustment rod 14 that contacts the portion 29 is provided. In addition,
A spacer having an appropriate thickness may be mounted between the movable side adjustment unit 12 and the fixed side adjustment unit 13 according to the thickness of the injection molding die. In FIG. 1, the lower side of the adjusting rod 14 is extended downward and a spacer is not used, but as shown in FIGS. 3 and 5, the lower end of the adjusting rod 14 or the spline shaft portion 17 is short. Then, a relatively long rod-shaped spacer (not shown) is used.

A mold clamping force control device (control means) 32 is connected to each load sensor 30. A hydraulic control valve 33 that controls the operation of the mold clamping cylinder 6 and a speed servo control device 34 that controls the operation of each drive motor 20 are connected to the mold clamping force control device 32. 33a
Is a simplified hydraulic pressure supply source.

Next, the injection device 42 will be described. FIG.
As shown in FIG. 5, the injection device 42 for explaining the embodiment of the present invention shows a case where the screw shaft 43 is driven by a hydraulic motor.

Reference numeral 44 is a heating cylinder, and 43 is a screw shaft which is fitted in the heating cylinder 44 so as to be able to move forward and backward and rotate in the forward and reverse directions. Reference numeral 45 denotes a screw head having a conical tip portion, the other end of which is screwed into the screw shaft 43 and is integrally connected to the screw shaft 43.

Reference numeral 46 denotes a raw material storage portion provided in front of the screw head 45, and the molten raw material stored therein is injected from an injection nozzle 47.

Reference numeral 48 is a forward / reverse rotation motor for rotating the screw shaft 43, and 49 is an injection piston which is fitted into the injection cylinder 50 and connected to the screw shaft 43. Reference numeral 51 indicates an oil tank, and 52 indicates a hopper.

Each load sensor 30 of the mold clamping device 1 is connected to a mold clamping force control device 32 and an injection control device 55.
And timing controller 56, respectively. The timing control device 56 is also connected to the mold clamping force control device 32.

The injection control device 55 includes an injection cylinder 5
A hydraulic control valve 57 for controlling the 0 operation is connected.
Reference numeral 33b is a simplified hydraulic pressure supply source. In this embodiment, the hydraulically driven injection device has been described, but in the case of electric drive, for example, the injection control device 5
5 will be connected to an electric drive source.

The control of the injection filling process in the mold compression molding is as follows.
The injection control device 55 and the timing control device 56 are controlled based on the detection signals from the load sensors 30, and the mold compression process is controlled based on the detection signals from the load sensors 30 and the mold clamping force control device 32 and the speed servo. The controller 34 is controlled to perform the following mold compression molding control.

When performing the injection filling process, the mold clamping device 1 is used to adjust the mold compression amount. First, the movable platen 3 is operated by the mold clamping cylinder 6 and moved to the mold clamping position where the movable mold 2 comes into contact with the fixed mold 4 (movable platen moving process for adjusting the reference point).

Next, the four drive motors 20 are driven while the movable platen 3 is held at the mold clamping position, and the respective adjustment rods 14 are moved downward and brought into contact with the rod receiving portion 29. In this case, the drive motor 20 stops when the load sensor 30 detects the state where each adjustment rod 14 is in contact with the rod receiving portion 29 (reference point adjustment step).

Next, after the reference point adjustment work is completed, the mold compression amount is set. The drive motor 20 is driven, each adjustment rod 14 is operated by a preset stroke amount, and the drive motor 20 is stopped (mold compression amount adjustment step).

After adjusting the mold compression amount, an injection filling process is performed. Now, the pressure of the mold clamping cylinder 6 is P, the mold clamping cylinder 6
Is F0, the mold internal pressure generated in the mold cavity formed by the movable mold 2 and the fixed mold 4 by injection filling is P1,
When the mold opening force generated in the movable mold 2 is F1 and the force generated in the adjusting rod 14 is F2, the forces F0, F1 and F2 of the respective parts are as follows.

The output F0 of the mold clamping cylinder 6 is a force required for preload within the allowable load of the adjusting rod 14, and the pressure P corresponding to the force is set by the hydraulic control valve 33. At this time, the relationship between the three forces is F0 = F1 (= P1) +. SIGMA.F2. Since the mold pressure P1 = 0 before injection filling, F1 = 0
Then, F0 = ΣF2.

In this state, when injection filling is performed from the injection device 42 into the mold cavity, a mold internal pressure P1 is generated, and a mold opening force F1 is generated based on this, so that F2 is reduced by that amount.

Here, the above relational expression F0 = F1 (= P1)
By detecting the force F2 detected by the load sensor 30 based on + ΣF2, it is possible to know the amount of change (P1) in the mold pressure due to injection filling. That is, by using the detection signal from the load sensor 30 as a control parameter and controlling the injection speed of the injection cylinder 50, which is the drive unit of the injection device 42, via the injection control device 55, the preset injection filling behavior (mold internal pressure). Can be accurately executed, and highly accurate control of the injection filling process can be achieved.

Incidentally, with the injection filling, the mold area on which the mold internal pressure P1 acts increases, and F1 increases as pressure × area, so that the movable mold 2 is prevented from separating, that is, set. It is also necessary to increase F0 for holding the mold compression amount. Again, the relation F0 = F1 (= P1)
Since + ΣF2 is established, the mold pressure P1 is accurately detected.

Next, at the time of starting the mold compression process, a state in which the mold cavity is completely filled in an ideal state, for example, a mold internal pressure at the time of complete filling is input as a set value to the timing control device 56 in advance. Oke, relational expression F0
= F1 (P1) + ΣF2 The force F2 from the load sensor 30 and the set value are compared and calculated, and a mold compression process start signal is sent to the mold clamping force control device 32 to start the mold compression process. It That is, by using the detection signal from the load sensor 30 as a control parameter, it is possible to appropriately control the start of the mold compression process.

Next, when the compression start point comes, the drive motor 2
When 0 is rotated, the speed of the adjusting rod 14 is controlled by the speed servo controller 34 according to a preset program, and the compression process is executed. When the compression process is executed, P1 naturally changes, but the compression force is F0 = F'1 (= P1)
Due to + ΣF2, F0 corresponding to F'1 is always set automatically. As a result, the compression speed accurately executes the set program, and highly accurate mold compression process control can be achieved.

The mold compressing process is performed after the injection filling process, but the mold compressing process may be started in parallel from an arbitrary position in the injection filling process.

In the above operation, the injection filling process is carried out while the preset mold compression amount is held. However, after the reference point adjustment, the injection filling process is started and the detection signal F2 from the load sensor 30 is started. Based on the above, the movable mold 2 is fixed to the fixed mold 4 by the injection speed control of the injection device 42 and the mold clamping device 1 so that the mold internal pressure P1 becomes constant at a preset value.
It is also possible to simultaneously perform control to move the movable platen 3 backward in the direction of separating it, and to switch from the injection filling process to the mold compression process after reaching the preset mold compression amount.

Further, instead of the output signal of the load sensor 30, the current detector 36 detects the change amount of the current value or the torque value of the drive system of the drive motor 20 and uses it as the control signal of each control device. It is also possible. In addition,
The output signal of the load sensor 30 and the output signal of a change in the current value of the drive system of the drive motor 20 may be used at the same time,
It is also possible to use them as needed.

FIG. 6 shows a schematic structure of the injection control circuit.
An input / output interface 39 for inputting and outputting a detection signal from each detector such as the load sensor 30 and the current detector 36 and a control signal to be output to each drive unit of the injection cylinder 50 and the drive motor 20 and setting conditions are stored. Storage unit 41
Unit and a set value and an arithmetic processing unit 40 that performs a comparative arithmetic process on the detection signal and outputs a control signal.
5 and a timing control device 56 are configured and connected to the mold clamping force control device 32 on the mold clamping device side. In the storage unit 41, the target value of the mold internal pressure and the input value of the time distribution are stored as set values. In the figure, 37 is a keyboard for inputting setting conditions, and 38 is a display unit.

The most important feature of the present invention is that the injection filling behavior (change of the mold internal pressure) in the mold cavity in the injection filling process is detected by the detection signal from the load sensor 30 of the platen adjusting mechanism 11 of the mold clamping device 1. The injection filling process control is performed by using this detection signal as a control parameter.

In the case where a pressure sensor or the like is incorporated in a conventional mold as a means for detecting a change in mold pressure,
Since it is a detection signal in a local area, there is a high possibility that it may be an inaccurate detection signal depending on the detection position, and it cannot be detected until the filling material reaches the detection position.
Obtaining accurate detection signals throughout the injection and filling process is extremely difficult.

Further, even in an attempt to compensate for the above-mentioned drawback by increasing the number of pressure sensors and the like, a group of independent detection signals accompanied by a time shift is required, and correction for converting into a continuous control signal is required. In addition to the above, the cost of mounting the pressure sensor and the cost of the modification of the mold for the mounting are increased.

Further, it requires complicated work such as mounting / removing the pressure sensor and calibrating the detection signal for each different mold, and it may be impossible to mount depending on the mold shape.

Although the vertical mold compression molding is described as the first embodiment, the present invention is not limited to the vertical mold compression molding and can be used in the horizontal mold compression molding. In that case, like the movable platen 3 and the movable mold 2,
The platen surface distance adjusting mechanism 11 is also mounted in a horizontal state so as to operate in the horizontal direction.

[0047]

According to the present invention, a mechanical platen surface distance adjusting mechanism composed of an adjusting rod, a prime mover for driving the adjusting rod, a rod adjusting section having a rod feed mechanism, and a rod receiving section having a force sensor. It is superior to the method of incorporating the pressure sensor in the mold by performing the injection filling process control and the mold compression start control by using a plurality of detection signals from the force sensor as control parameters. (1) Since the mold internal pressure P1 generated by injection filling can be accurately and continuously detected, highly accurate injection control can be performed, and a high-quality molded product with good product weight accuracy can be obtained. (2) Since the detection signal response speed is extremely high and the detection signal accuracy does not fluctuate, highly accurate mold compression start control can be performed, and high quality molded products can be stably obtained. (3) Since the mold internal pressure P1 generated by injection filling is not measured by the mold cavity internal pressure sensor method, hardware and software for performing mounting work and calculation are unnecessary, and the economical effect is excellent. (4) High-precision mold opening control eliminates measurement (injection) instability and enables accurate injection filling volume control, resulting in high-quality molded products with no sink marks or burrs. You can (5) Further, since the detection means for control has a double structure, the detection accuracy is improved and an unexpected trouble can be dealt with swiftly, thereby preventing a reduction in productivity due to the stop of the molding machine. it can. (6) Furthermore, since the force F1 generated in the movable mold can be accurately and quickly detected even in the mold compression process following the injection filling process, highly accurate mold compression control can be performed, which is extremely synergistic with the effect of the injection control described above. It is possible to stably supply high quality molded products.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an apparatus for carrying out the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a front view showing a movable side adjustment unit.

FIG. 4 is a front view showing a fixed adjustment unit.

FIG. 5 is a vertical sectional view showing a connecting portion of a spline shaft.

FIG. 6 is a circuit configuration diagram showing an embodiment of injection control.

[Explanation of symbols]

 1 mold clamping device 2 movable mold 3 movable platen 4 fixed mold 5 fixed platen 6, 6a mold clamping cylinder 11 platen surface distance adjusting mechanism (platen adjusting mechanism) 12 movable side adjusting unit 13 fixed side adjusting unit 14 adjusting rod 15 feed mechanism Part 16 Screw shaft part 17 Spline shaft part 18 Ball screw part 20 Drive motor 23 Guide shaft 29 Rod receiving part 30 Load sensor (pressure detection means) 31 Hydraulic cylinder 32 Mold clamping force control device (control means) 33 Hydraulic control valve 34 Speed Servo control device 35 Position detector 36 Current detector 37 Input keyboard 38 Display unit 39 Input / output interface 40 Arithmetic processing unit 41 Storage unit 42 Injection device 43 Screw shaft 44 Heating cylinder 45 Screw head 46 Resin reservoir 47 Injection nozzle 48 Forward / reverse rotation Motor 49 Injection piston 50 Injection cylinder 55 Injection control device 56 Timing control device 57 Hydraulic control valve

Claims (8)

[Claims] 1. A movable platen is provided with a mold clamping mechanism for generating a forward / backward movement and a mold clamping force, and a movable platen and a fixed platen are provided with an adjusting rod, and a prime mover and a rod feed mechanism for moving the adjusting rod forward and backward. When performing mold compression molding using a mold clamping device equipped with a plurality of platen surface distance adjusting mechanisms equipped with a rod adjusting part equipped with a rod receiving part equipped with a force sensor, in the injection filling step,
A mold compression molding method, characterized in that control of a drive unit of an injection mechanism and start control of a mold compression process are performed based on an output signal of a force sensor. 2. A mold clamping mechanism based on a moving speed control of an adjusting rod and an output signal of the force sensor in a state where a predetermined load is applied to the force sensor in the injection filling process or a mold compression process subsequent to the injection filling process. The mold compression molding method according to claim 1, wherein the compression force control is performed at the same time. 3. A target value for mold internal pressure and an input value for time distribution are stored as set values in a storage unit, and the result of comparison calculation of the detection signal from the force sensor and the set value by a calculation processing unit is output as a control value. The mold compression molding method according to claim 1, wherein the signal is used to control the injection speed of the injection mechanism and to start the mold compression step. 4. The mold compression molding method according to claim 1, wherein a current value of a drive system of the platen surface distance adjusting mechanism is used as a detection signal instead of the force sensor. 5. A molding machine provided with an injection mechanism, wherein a movable mold for molding is held by a movable platen and a fixed side is held by a fixed platen, respectively, and the movable platen is moved forward and backward with respect to the fixed platen. The platen is provided with a mold clamping mechanism that generates a mold clamping force, and a mechanical feed mechanism and an adjusting rod that are movably attached to either the movable platen or the fixed platen along the forward / backward movement direction of the movable platen. From the rod adjusting unit that has a prime mover that drives the adjusting rod and the adjusting rod receiving unit that has the rod receiving unit that is arranged facing the adjusting rod and the detecting unit that detects the force applied to the rod receiving unit on the other side. It is equipped with a plurality of platen surface distance adjustment mechanisms configured and controls the injection speed of the injection mechanism based on the output signal from the force sensor. A mold compression molding apparatus comprising a controlled injection control device and a timing control device for starting a mold compression process. 6. A speed servo control device for controlling a moving amount of a movable platen in a drive system of a platen surface distance adjusting mechanism,
The mold compression molding apparatus according to claim 5, further comprising a mold clamping force control device that controls a mold clamping force of the mold clamping mechanism based on an output signal output from the force sensor. 7. A control unit for a drive system of an injection mechanism by comparing and processing a detection signal from a force sensor and a set value with a storage unit section for storing a target value of mold internal pressure and an input value of time distribution as a set value. An arithmetic processing unit section for outputting as a control signal, an input / output interface section for inputting / outputting a detection signal and a control signal, an injection controller and a timing controller having an input keyboard and a display section, and a force sensor section. The mold compression molding apparatus according to claim 5, wherein a drive unit of the injection mechanism is connected. 8. The mold according to claim 5, wherein instead of the force sensor, a current detector for inputting the current value of the drive unit of the platen inter-plane distance adjusting mechanism as a detection signal to the input / output interface is used. Compression molding equipment.