JP2845356B2 - Ejector control method for injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a resin heated and melted in a heating cylinder is filled at a high pressure into a cavity of a mold, cooled in the cavity, and then the mold is opened to take out a molded product. In the injection molding machine
When the cooling step is completed, the mold is opened with the molded article left on the movable side, and the molded article is pushed down from the mold by the ejector device.

[0003] Therefore, an ejector pin is provided so as to face the cavity, a rear end is fixed to an ejector plate, and an ejector cylinder is connected to the rear end of the ejector plate via an ejector rod. ing. Therefore, by operating the ejector cylinder and advancing the ejector plate via the ejector rod, the molded product can be pushed down by the ejector pin fixed to the ejector plate.

By the way, in order to reliably push down a molded product, an ejector cylinder is operated to move an ejector pin forward and backward a plurality of times. However, in this case, since the backward movement time is set to at least 0.1 second or more, a time loss occurs due to the operation of the ejector cylinder, and the cycle time until the molded article is pushed down is lengthened.

[0005] In view of the above, there have been provided ones that eliminate the idle running of the ejector rod until the ejector rod is brought into contact with the ejector plate or change the ejecting speed of the ejector pin during the ejecting stroke.

[0006]

However, in the above-mentioned conventional ejector control method for an injection molding machine, since the ejector pins are rapidly moved forward and backward, the molded product is scattered in various directions, and the molded product has cracks or the like. Damage may occur. In addition, the ejector pin bites into the molded product, and the molded product is damaged, or the molded product cannot be reliably pushed down. Further, when the ejector pins are retracted, the ejector plate collides with the movable mold mounting plate, and at that time, an impact sound exceeding 90 [dB] is generated.

The present invention solves the above-mentioned problems of the conventional ejector control method of an injection molding machine, and has a short cycle time until the molded product is pushed down, the molded product scatters in each direction, and the molded product has cracks. No breakage of the ejector member occurs, the molded product is not damaged by the intrusion of the ejector member into the molded product, the molded product cannot be reliably pushed down, and the ejector plate is retracted. It is an object of the present invention to provide an ejector control method for an injection molding machine that can reduce an impact sound generated when the ejector is operated.

[0008]

For this purpose, in the ejector control method for an injection molding machine according to the present invention, the ejector member is advanced to start the ejection, and the ejection member is set at a position short of a projecting position sufficient to push down the molded product. At the set position, the ejector member is released by generating a minute vibration consisting of a minute protrusion and a minute return to the ejector member, and after the mold release is completed, the ejector member is retracted to terminate the protrusion. Then, the position where each minute protrusion of the ejector member ends is set to a position closer to the protrusion position enough to push down the molded product.

In the ejector control method for an injection molding machine according to another aspect of the present invention, each of the minute protrusion and the minute return is performed for a set minute time of less than 0.1 second. In still another ejector control method for an injection molding machine of the present invention, the minute return and retreat of the ejector member are performed by a restoring force of a return spring, and a resistance force is generated against the restoring force. . In still another ejector control method for an injection molding machine according to the present invention, the resistance force is generated by a member that controls an amount of oil in a hydraulic circuit of a cylinder that drives the ejector member. In yet another ejector control method for an injection molding machine according to the present invention, the resistance force is generated by controlling a current of a motor driving the ejector member. In still another ejector control method for an injection molding machine according to the present invention, the ejector member is advanced to start projecting, and at a position set before the projecting position sufficient to push down a molded product, the ejector member is moved to the ejector member. A minute vibration consisting of a minute protrusion and a minute return is generated. After terminating the generation of the minute vibration, it is possible to select whether to retract the ejector member or to further advance the ejector member to the projecting position in accordance with a molded product.

[0010]

According to the present invention, as described above, in the ejector control method for an injection molding machine, the ejector member is advanced to start projecting, and the ejecting member is set before the projecting position sufficient to drop the molded product. At the position, the release is performed by generating a minute vibration including a minute protrusion and a minute return to the ejector member, and after the mold release is completed, the ejector member is retracted to finish the protrusion. Then, the position where each minute protrusion of the ejector member ends is set to a position closer to the protrusion position enough to push down the molded product.

In this case, the ejector member is advanced to start projecting, and at a position set before the projecting position sufficient to push down the molded product, a minute vibration consisting of a minute projection and a minute return to the ejector member is generated. generate. Then, the position where each minute protrusion of the ejector member ends is set to a position closer to the protrusion position enough to push down the molded product. The molded product tries to advance further due to the inertial force generated due to the minute protrusion, whereas the ejector member that has digged into the molded product retreats with the minute return.

In another aspect of the present invention, the ejector member is minutely returned and retracted by a restoring force of a return spring, and a resistance force is generated against the restoring force. Let me do. In this case, the speed at which the ejector plate supporting the ejector member is retracted is reduced.

In still another ejector control method for an injection molding machine according to the present invention, the ejector member is advanced to start projecting, and the ejector member is moved to a position set before a projecting position sufficient to push down a molded product. A minute vibration consisting of a minute protrusion and a minute return is generated in the ejector member. After terminating the generation of the minute vibration, it is possible to select whether to retract the ejector member or to further advance the ejector member to the projecting position in accordance with a molded product. In this case, if the molded article cannot be pushed down at the time when the generation of the minute vibration ends, the ejector member can be further advanced.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of an ejector device to which the ejector control method of the present invention is applied, and FIG. 2 is a diagram showing a relationship between a protruding position and time. In FIG. 1, reference numeral 1 denotes a fixed die, 2 denotes a movable die which is disposed so as to be able to freely contact and separate from the fixed die 1, 3 denotes a receiving plate for reinforcing the movable die 2, and 4 denotes a movable platen. It is. 6 is an upper ejector plate, 7
Is a lower ejector plate, 8 is a fixed mold attaching plate for attaching the fixed mold 1 to a fixed platen (not shown), and 9 is a movable mold attaching plate for attaching the movable mold 2 to the movable platen 4. is there.

Further, reference numeral 10 denotes a sprue, and reference numeral 11 facilitates attachment of the fixed mold 1 to the fixed platen.
Locating ring for smooth nozzle touch,
12 is a sprue bush for guiding resin injected from an injection nozzle (not shown), 13 is a guide pin attached to the movable mold 2 and guides the fixed mold 1, 14 is a guide pin bush, and 16 is a sprue lock pin. , 17
Is an ejector pin as an ejector member, 18 is a return pin, 19 is a return spring that surrounds the return pin 18 and urges the upper ejector plate 6 rearward, and 21 is for smoothly projecting the ejector pin 17 by the ejector pin 17. Ejector guide pins, 22 an ejector guide pin bush, 23 a cavity formed between the fixed mold 1 and the movable mold 2, 23a a runner,
3b is a gate. In addition, P. L. Is the fixed mold 1
And a parting line between the movable mold 2 and the movable mold 2.

In the injection molding machine having the above construction, when the resin is injected while the injection nozzle is in contact with the sprue bush 12, the resin is filled into the cavity 23 through the sprue 10, the runner 23a and the gate 23b. You. Then, when the injection step is completed, pressure is maintained to replenish the resin in the cavity 23 with the contraction of the resin. Thereafter, when the resin cools and becomes a molded product, the movable mold 2 retreats, moves to the left in the drawing, separates from the fixed mold 1 and the mold is opened.

At this time, the ejector pin 17 advances, and the molded product is pushed down from the movable mold 2. Therefore, an ejector rod 25 is provided at the rear end of the lower ejector plate 7 so as to be able to freely contact and separate, and the ejector rod 25 is moved forward and backward by an ejector cylinder 30. Here, Ar is the retreat limit position of the ejector rod 25.

A piston 31 is slidably disposed in the ejector cylinder 30, and a first oil chamber 32 and a second oil chamber 33 are formed by the piston 31. The first oil chamber 32 and the second oil chamber 33 are connected to a hydraulic valve 38 via oil paths 35 and 36, respectively. Reference numeral 39 denotes an oil pump that supplies oil to the first oil chamber 32 and the second oil chamber 33, and 40 denotes an oil tank.

The hydraulic valve 38 is operated by the solenoids a and b. When the solenoid a is turned on, the hydraulic valve 38 assumes the position A, and the oil discharged from the oil pump 39 is supplied to the first oil passage 35 through the oil passage 35.
The oil is supplied to the oil chamber 32, and the oil in the second oil chamber 33 is drained to the oil tank 40 via the oil passage 36. At this time,
The ejector rod 25 moves forward. The hydraulic valve 38 takes the position B when the solenoid b is turned on, supplies the oil discharged from the oil pump 39 to the second oil chamber 33 via the oil passage 36, and controls the oil in the first oil chamber 32. Is drained to an oil tank 40 via an oil passage 35. At this time, the ejector rod 25 retreats.

Further, the hydraulic valve 38 takes the N position when the solenoids a and b are turned off, and transfers the oil in the first oil chamber 32 and the second oil chamber 33 to the oil tank 4 through oil passages 35 and 36.
Drain to zero. The hydraulic valve 38 has throttles 41 and 42.
Flow through 1,42. Next, the operation of the injection molding machine having the above configuration will be described with reference to FIG.

Normally, an injection molding machine has an automatic mode, a semi-automatic mode, and a manual mode. When the automatic mode or the semi-automatic mode is selected, the ejector rod 25 is moved to the retreat limit position before the first ejection. Move forward from Ar at a preset speed for a preset time. Thereafter, the solenoids a and b of the hydraulic valve 38 are turned off. At this time, the ejector rod 25 is retracted by the restoring force of the return spring 19, and the oil in the first oil chamber 32 and the second oil chamber 33 of the ejector cylinder 30 passes through the throttles 41 and 42 via the oil passages 35 and 36. Drain to the oil tank 40.

In this case, since the oil flows through the throttles 41 and 42, a resistance force against the restoring force of the return spring 19 is generated. Therefore, the speed at which the lower ejector plate 7 retreats is reduced, and the impact when colliding with the movable mold mounting plate 9 is reduced.
[DB]. At this time, as the lower ejector plate 7 collides with the movable mold mounting plate 9 and the retreat is completed, the ejector rod 25 projects and stops at the start position B. It is performed from the start position B. Therefore, when ejecting is performed again, the ejector rod 25 does not run idle from the retreat limit position Ar to the ejecting start position B.

Next, the movable platen 4 is advanced, the mold is clamped, the resin is injected and filled into the cavity 23, and after the resin is cooled, the mold is opened. Then, the ejector rod 25 is moved for a preset time or until the ejector rod 25 reaches a preset position (when the motor is used instead of the ejector cylinder 30, the motor is driven by a preset number of pulses). Move forward with low speed control. In this case, if the material of the molded article is a hard resin, only the speed control is performed, and if the material is a soft resin such as an elastomer, the ejector rod 25 is advanced by low pressure control. Therefore, the ejector pins 17 do not excessively bite into the molded product.

Next, swing back is started. That is, the ejector rod 25 is advanced at a medium speed or a high speed for a minute time of less than 0.1 second, and is retracted for a minute time of less than 0.1 second. In this embodiment, 0.0
Forward for 3 seconds, retract for 0.03 seconds, up to 9
I repeat it up to times. The forward movement is performed by the hydraulic pressure in the ejector cylinder 30, and the backward movement is performed by the restoring force of the return spring 19. Therefore, there is no time loss associated with the operation of the ejector cylinder 30,
It is possible to shorten the cycle time until the molded article is pushed down. At this time, while the ejector pin 17 that has penetrated the molded product retreats, the molded product attempts to move forward due to the inertial force, and the molded product is pushed down.

In the swingback, it is necessary to repeat the advance and retreat within a very short time. However, the time and speed of each advance and retreat are determined only by peeling off the adhesion of the ejector pin 17 to the molded product due to biting. Is sufficient. In addition,
The magnitude of the swing-back amplitude can be changed depending on the shape, material, and the like of the molded product.

When the molded product is a shallow product, the molded product can be reliably pushed down at this stage, and the ejector rod 25 can be retracted as it is, thereby shortening the cycle time until the molded product is pushed down. Become. Also,
Since the ejector rod 25 is advanced at a low speed until the swingback is started, the impact on the molded product is reduced, and the molded product is scattered in each direction, and the molded product is damaged such as cracks. There is no.

Next, when the solenoids a and b are turned off,
Ejector rod 25 by return spring 19
Is retracted and the first oil chamber 3 of the ejector cylinder 30 is
The oil in the second and second oil chambers 33 passes through oil passages 35 and 36, passes through throttles 41 and 42, and drains to an oil tank 40. In this case, since the oil flows through the throttles 41 and 42, the speed at which the lower ejector plate 7 retreats is low, and the impact when colliding with the movable mold mounting plate 9 is small, and the impact noise is also 15 [dB]. ] About smaller. Then, the process moves to the next cycle.

When the molded product is a deep product, it cannot be reliably pushed down only by swinging back. Then, the ejector rod 25 is advanced to the projecting position C which is sufficient to push down the molded product. In this case, the tip of the ejector pin 17 is located at a position sufficiently distant from the movable mold 2, so that the molded product is securely pushed down. At this time, when air is injected and supplied from above the molded product, the movable mold 2
The molded product or runner 23a that has come off from the mold is completely peeled off (stripped) and is pushed down. Further, it is possible to prevent the molded article from scattering in each direction.

Thereafter, when the solenoids a and b are turned off, the ejector rod 25 is retracted by the return spring 19, and the oil in the first oil chamber 32 and the second oil chamber 33 of the ejector cylinder 30 is removed from the oil passage 35, Drain to the oil tank 40 through the throttles 41 and 42 via 36. Then, the process moves to the next cycle. The apertures 41 and 42
Generates a resistance force opposing the retraction force of the return spring 19.

If it is difficult for the molded product to be pushed down by the ejector pins 17, a variable throttle 50 and a check valve 51 are arranged in parallel with the oil passage 35, and the variable throttle 50 is adjusted. Thereby, the resistance force when the ejector rod 25 retreats can be made variable. Then, when the mode switch (not shown) is turned off or the manual mode is selected when the protrusion in the automatic mode or the semi-automatic mode is completed, the ejector rod 25 can be retracted to the retreat limit position Ar at an arbitrary time and at an arbitrary speed. . Thus, when the movable mold 2 is attached to and detached from the movable platen 4, the ejector rod 2
Since the tip of 5 is located deeper than the end surface of the movable platen 4, the movable mold 2 and the like are not damaged.

The throttles 41, 42, the variable throttle 50, and the check valve 51 may be provided with both, or may be provided with either one. Further, another resistance generating means may be provided. In this embodiment, the ejector cylinder 30 is used as a driving means for moving the ejector rod 25 forward and backward.
When an electric motor is used, the number of rotations is controlled instead of the speed, the current or torque is controlled instead of the pressure, and the number of pulses is controlled instead of the position. In this case, the resistance force opposing the retraction force of the return spring 19 can be controlled by the current supplied to the electric motor, and the speed of the ejector rod 25 can be controlled by the number of pulses.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified based on the gist of the present invention, and these are not excluded from the scope of the present invention.

[0033]

As described above in detail, according to the present invention, in the ejector control method for an injection molding machine, the ejector member is advanced to start ejecting, and the projecting position is sufficient to push down the molded product. At a position set closer to the front, release is performed by generating a minute vibration consisting of a minute protrusion and a minute return to the ejector member, and after the release is completed, the ejector member is retracted to finish the protrusion. . Then, the position where each minute protrusion of the ejector member ends is set to a position closer to the protrusion position enough to push down the molded product.

In this case, the ejector member is advanced to start projecting, and at a position set before the projecting position sufficient to drop the molded product, a minute vibration consisting of a minute projection and a minute return to the ejector member is generated. When the position at which the ejector member is generated and each minute protrusion of the ejector member ends is located closer to a protrusion position sufficient to push down the molded product, the molded product is further advanced by the inertial force generated due to the minute protrusion. On the other hand, the ejector member that has digged into the molded article retreats with the minute return. Therefore, when the molded product is a shallow object, the ejector member can be moved only by a very small amount to move the ejector member in a position set before the projecting position sufficient to push down the molded product. Can be peeled off by sticking to the molded article, and the molded article can be pushed down in a short time. As a result, time loss can be eliminated and work efficiency can be improved.

In the ejector control method for an injection molding machine according to another aspect of the present invention, the minute protrusion and the minute return are both performed for a set minute time of less than 0.1 second. In this case, it is not necessary to change the set value of the very small time, so that the setting operation is not required.

In the ejector control method for an injection molding machine according to still another aspect of the present invention, the ejector member is minutely returned and retracted by a restoring force of a return spring, and a resistance force is resisted against the restoring force. Generated.
In this case, the speed at which the ejector plate supporting the ejector member is retracted is reduced, so that the impact noise when the movable plate attaches to the movable mold mounting plate is reduced.

In still another ejector control method for an injection molding machine according to the present invention, the ejector member is advanced to start projecting, and the ejector member is moved to a position set before the projecting position sufficient to push down a molded product. A minute vibration consisting of a minute protrusion and a minute return is generated in the ejector member. After terminating the generation of the minute vibration, it is possible to select whether to retract the ejector member or to further advance the ejector member to the projecting position in accordance with a molded product. In this case, if the molded article cannot be pushed down at the time when the generation of the minute vibration ends, the ejector member can be further advanced.

Therefore, even if the molded product is a deep product, it can be reliably pushed down. Also, when the ejector member is retracted after the generation of the minute vibration is terminated,
It is possible to shorten the cycle time until the molded article is pushed down.

[Brief description of the drawings]

FIG. 1 is a sectional view of an ejector device to which an ejector control method according to the present invention is applied.

FIG. 2 is a relationship diagram between a protruding position and time.

[Explanation of symbols]

 6 Upper ejector plate 7 Lower ejector plate 17 Ejector pin 19 Return spring 25 Ejector rod 30 Ejector cylinder B Projection start position C Projection position

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yukihiro Ishii 731 Naganumaharamachi, Inage-ku, Chiba-shi, Chiba Chiba Works, Sumitomo Heavy Industries, Ltd. (72) Inventor Atsushi Fujishiro Inage-ku, Chiba-shi, Chiba No. 731 Naganumahara-cho 1 Chiba Works, Sumitomo Heavy Industries, Ltd. (56) References JP-A-1-308613 (JP, A) JP-A-4-305423 (JP, A) JP-A-4-146113 ( JP, A) JP-A-6-114897 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 45/40 B29C 33/44 B29C 45/76

Claims (6)

(57) [Claims] (A) advancing an ejector member to start projecting; and (b) a minute projecting and returning to the ejector member at a position set short of a projecting position sufficient to push down a molded product. (C) after the mold release is completed, the ejector member is retracted to finish the protrusion , and (d) each minute protrusion of the ejector member is finished. Rank
Position the product from a protruding position that is sufficient to push the part down.
An ejector control method for an injection molding machine , which is performed before . 2. The ejector control method for an injection molding machine according to claim 1, wherein both the minute protrusion and the minute return are performed for a set minute time of less than 0.1 second. 3. The injection according to claim 1, wherein (a) the ejector member is slightly returned and retracted by a restoring force of a return spring, and (b) a resistance force is generated against the restoring force. Ejector control method for molding machine. 4. The apparatus according to claim 1, wherein the resistance force drives the ejector member.
A part that controls the amount of oil in the hydraulic circuit of the moving cylinder
The injection molding machine according to claim 3, which is generated by a material.
Ejector control method. 5. The ejector according to claim 1, wherein the resistance force drives the ejector member.
Generated by controlling the current of a moving motor.
An ejector control method for an injection molding machine according to claim 3, wherein
Law. 6. An ejector member is advanced to start projecting, and (b) a minute projecting and returning to the ejector member at a position set before the projecting position sufficient to push down a molded product. to generate small vibrations consisting of, quits the occurrence of (c) fine small vibration, or retracting the ejector member, the ejector member to said protruding position
A method for controlling the ejector of an injection molding machine, wherein it is possible to select whether to further advance the apparatus in accordance with the molded article.