JP3654394B2 - Injection compression molding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an injection compression molding method, and more particularly to an injection compression molding method using a toggle type injection molding machine.
[0002]
[Prior art]
Conventionally, in a toggle type injection molding machine, by controlling the position of the hydraulic cylinder for mold clamping, the mold clamping force before injection (initial mold clamping force) is arbitrarily set, and injection is performed by re-clamping after injection. Compression molding is performed. Normally, the position of the mold clamping hydraulic cylinder is controlled using an ON / OFF type switching valve or a servo valve.
[0003]
FIG. 5 shows a hydraulic circuit of a toggle type injection molding machine using a conventional servo valve. This hydraulic circuit is an injection compression dedicated hydraulic circuit 21 provided separately from a standard hydraulic circuit that is normally used, and is provided with an injection compression dedicated power 22, a mold clamping cylinder servo valve 23, and a servo control device (not shown). ing. A crosshead 7 is attached to the tip of the piston rod of the mold clamping cylinder 6, and the position of the crosshead 7 is detected by a movable plate position detection sensor 10.
[0004]
[Problems to be solved by the invention]
However, in the method of using an ON / OFF switching valve for controlling the position of the hydraulic cylinder for mold clamping, it is very difficult to perform positioning accurately, and the overrun amount becomes larger than the target position, and the stop position The repeatability of was also poor.
[0005]
In addition, the method using the servo valve has good positioning accuracy and repeatability of the stop position. However, in order to configure the hydraulic servo circuit, the hydraulic pressure dedicated to injection compression is different from the hydraulic circuit that controls the mold opening and closing of the injection molding machine. A circuit, dedicated power for injection compression, and a servo control device are required, and it is necessary to select hydraulic equipment (hydraulic block, piping, servo valve) according to the size of the injection molding machine, and to configure the servo circuit It was a cause of cost increase.
[0006]
The present invention has been made in view of the above-described problems, and is an injection compression molding method in which the initial mold clamping position positioning accuracy and the stop position repetition accuracy by a hydraulic cylinder for mold clamping can be obtained at low cost. It is an issue to provide.
[0007]
[Means for Solving the Problems]
According to the present invention, the above-described problems have been solved as follows. That is, the operation of the clamping cylinder in the toggle type injection molding machine is performed by the standard mold closing operation up to the mold touch position, and after the mold touch position, the speed is low (for example, 20% of the maximum mold closing speed) When the head position is a predetermined stroke before the initial clamping force completion position (3 to 5 mm), the speed becomes very slow (for example, 0.1%). Clamping is stopped at the initial clamping force completion position, and re-clamping is performed after injection. Do. Alternatively, when the position of the crosshead is a predetermined stroke before the initial clamping force completion position (for example, 0.5 mm), the mold clamping cylinder switching valve is closed and the clamping is stopped at the initial clamping force completion position. Re-clamp.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the injection compression molding method according to the present invention, the operation of the clamping cylinder in the toggle type injection molding machine is performed by the standard mold closing operation up to the mold touch position, and the speed is set at a low speed before a predetermined stroke from the position where the initial clamping force is completed. The mold clamping is stopped at the position where the initial mold clamping force is completed, and the mold is clamped again after injection.
[0009]
Specifically, the mold clamping cylinder in the toggle type injection molding machine is operated by the standard mold closing operation up to the mold touch position, the speed after the mold touch position is set at a low speed, and a predetermined stroke from the initial mold clamping force completion position. It is characterized in that it is set at a very low speed in front, the mold clamping is stopped at the position where the initial mold clamping force is completed, and the mold clamping is performed after injection.
[0010]
More specifically, when the position of the crosshead connected to the mold clamping cylinder is 3 to 5 mm before the position where the initial mold clamping force is completed, the mold clamping cylinder is set to a very low speed.
[0011]
In another injection compression molding method according to the present invention, the operation of the clamping cylinder in the toggle type injection molding machine is performed by the standard mold closing operation up to the mold touch position, and a predetermined stroke before the initial clamping force completion position. Close the mold clamping cylinder switching valve before a stroke shorter than the predetermined stroke from the initial mold clamping force completion position, stop the mold clamping at the initial mold clamping force completion position, and perform mold clamping again after injection. Features.
[0012]
Specifically, the mold clamping cylinder in the toggle type injection molding machine is operated by the standard mold closing operation up to the mold touch position, the speed after the mold touch position is set at a low speed, and a predetermined stroke from the initial mold clamping force completion position. Close the mold clamping cylinder switching valve before the stroke shorter than the predetermined stroke from the initial mold clamping force completion position, stop the mold clamping at the initial mold clamping force completion position, and perform mold clamping after injection. It is characterized by that.
[0013]
【Example】
Embodiments of the present invention will be described with reference to the drawings. FIG. 4 shows a hydraulic circuit of a toggle type injection molding machine for carrying out the injection compression molding method of the present invention. This hydraulic circuit is a standard hydraulic circuit 1 that is normally used. A standard molding power 2 is provided with a switching valve 3 for an injection cylinder, a switching valve 4 for a hydraulic motor, a switching valve 5 for a mold clamping cylinder, and the like via a pipeline. It is connected. A cross head 7 is attached to the tip of the piston rod of the mold clamping cylinder 6, and the cross head 7 is connected to the movable plate 9 via a toggle mechanism 8. The position of the crosshead 7 is detected by a movable plate position detection sensor 10. The movable plate position detection sensor 10 is connected to an injection compression controller 11 that compares the position with a position setter (not shown). By operating the mold clamping cylinder 6 to move the crosshead 7 back and forth, the mold 13 attached to the movable platen 9 and the fixed platen 12 can be brought into and out of contact with each other.
[0014]
Next, an injection compression molding method using the hydraulic circuit of the toggle type injection molding machine described above will be described.
[0015]
(Example 1)
FIG. 1 is an operation diagram of the mold clamping cylinder of the first embodiment, and shows the relationship between the position of the cross head attached to the tip of the mold clamping cylinder and the speed of the mold clamping cylinder. 1A is an overall operation diagram, and FIG. 1B is an enlarged view of a main part thereof.
[0016]
As shown in FIG. 1 (b), the standard mold closing operation is performed up to the mold touch position, and after the mold touch position, a low-speed flow rate for generating an initial mold closing force (for example, 20% of the maximum mold closing speed). ) When the target is approached, the flow rate is further reduced, and the mold clamping operation is performed at a fine flow rate (for example, 0.1%). When the target position (initial clamping force completion position) is reached, the hydraulic pressure is cut off and the mold clamping is stopped.
[0017]
The switching point between the standard flow rate and the low-speed flow rate, or the low-speed flow rate and the fine-speed flow rate is arbitrarily set depending on the model. Note that the switching point between the low-speed flow rate and the slow-speed flow rate is set to a predetermined stroke (3 to 5 mm) before the initial mold clamping force completion position where the initial mold clamping force is generated.
[0018]
FIG. 2 is a flowchart showing a control procedure of the mold clamping cylinder described above.
[0019]
When the mold clamping cylinder 6 starts operating and the crosshead 7 comes to the mold touch position (step 1), the speed of the mold clamping cylinder 6 is reduced to, for example, 20% of the maximum mold closing speed (step 2). Next, when it reaches several mm before the initial clamping force completion position (step 3), the speed of the clamping cylinder 6 is reduced to, for example, 0.1% (step 4). Next, when the initial clamping force completion position is reached (step 5), the clamping cylinder switching valve 5 is closed (step 6) to stop clamping. Thereafter, injection compression molding is performed by injection and re-clamping.
[0020]
In the above embodiment, the standard flow rate is switched to the very low speed flow rate via the low speed flow rate, but the standard flow rate can be directly switched to the very low speed flow rate.
[0021]
According to the embodiment described above, the overrun with respect to the initial clamping position is greatly suppressed, and the repeatability is further improved.
[0022]
(Example 2)
FIG. 3 is an operation diagram of the mold clamping cylinder of the second embodiment, and shows the relationship between the position of the cross head attached to the tip of the mold clamping cylinder and the speed of the mold clamping cylinder. As shown in the figure, the standard mold closing operation is performed up to the mold touch position, and after the mold touch position, a low flow rate (for example, 20% of the maximum mold closing speed) for generating the initial mold closing force, initial Switch to the clamping cylinder at the control stop position set to a fine speed before a predetermined stroke (for example, 3 to 5 mm) from the initial clamping force completion position where the clamping force is generated and set to a stroke (for example, 0.5 mm) shorter than the predetermined stroke. The valve 5 is closed. The mold clamping cylinder switching valve 5 is completely closed with some delay due to physical inertia. The cross head 7 moves by an idle running distance depending on the magnitude of the initial mold clamping force, and stops around the initial mold clamping completion position which is the final target value. The initial mold clamping force completion position is calculated as a crosshead position when the initial mold clamping force is set.
[0023]
In the above embodiment, the clamping cylinder switching valve 5 is closed at a low flow rate, but the clamping cylinder switching valve 5 may be closed at a standard flow rate.
[0024]
According to the embodiment described above, the positioning accuracy and repeatability are improved by appropriately setting the control stop position.
[0025]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0026]
That is, compared with the conventional method using an ON / OFF type switching valve, the overrun with respect to the initial clamping position is greatly suppressed, and the repeatability is improved. Further, compared with the method using the servo valve, the cost is reduced because the servo valve, the servo hydraulic circuit and the servo amplifier are unnecessary. In addition, adjustment and setting of servo constants are unnecessary, and adjustment is easy. Furthermore, since the servo valve and hydraulic block are not required and a standard hydraulic circuit can be used, the machine delivery time can be greatly reduced.
[Brief description of the drawings]
FIGS. 1A and 1B are operation diagrams of a mold clamping cylinder according to a first embodiment, wherein FIG. 1A is an overall operation diagram, and FIG.
FIG. 2 is a flowchart showing a control procedure of a mold clamping cylinder.
FIG. 3 is an operation diagram of the mold clamping cylinder of the second embodiment.
FIG. 4 is a diagram showing a hydraulic circuit of a toggle type injection molding machine that performs an injection compression molding method according to the present invention.
FIG. 5 is a diagram showing a hydraulic circuit of a toggle type injection molding machine using a conventional servo valve.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Standard hydraulic circuit 2 Standard shaping power 3 Injection cylinder switching valve 4 Hydraulic motor switching valve 5 Mold clamping cylinder switching valve 6 Mold clamping cylinder 7 Crosshead 8 Toggle mechanism 9 Movable platen
10 Movable platen position sensor
11 Injection compression controller
12 Fixed platen
13 Mold

Claims (3)

  The operation of the clamping cylinder (6) in the toggle type injection molding machine is performed by the standard mold closing operation until the mold touch position, the speed after the mold touch position is low, and a predetermined stroke before the initial mold clamping force completion position. The injection compression molding method is characterized in that the mold clamping is stopped at a position where the initial mold clamping force is completed, and the mold is clamped again after injection.   The operation of the clamping cylinder (6) in the toggle type injection molding machine is performed by the standard mold closing operation up to the mold touch position, and the initial mold clamping force is completed by setting the speed slightly before a predetermined stroke from the initial mold clamping force completion position. An injection compression characterized in that the mold clamping cylinder switching valve (5) is closed before the stroke shorter than the predetermined stroke from the position, the mold clamping is stopped at the initial mold clamping force completion position, and re-clamping is performed after injection. Molding method.   The operation of the clamping cylinder (6) in the toggle type injection molding machine is performed by the standard mold closing operation until the mold touch position, the speed after the mold touch position is low, and a predetermined stroke before the initial mold clamping force completion position. Close the mold clamping cylinder switching valve (5) before a stroke shorter than the predetermined stroke from the initial mold clamping force completion position, stop the mold clamping at the initial mold clamping force completion position, and re-clamp after injection. Performing an injection compression molding method.

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