JP2001212854A - Apparatus and method for ejecting molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for ejecting a molded article, capable of releasing the molded article without inclining an ejector plate even when the release resistance immediately after ejection is large. SOLUTION: The apparatus for ejecting the molded article 23 is equipped with ejector pins 32a, 32b for releasing a molded article from a mold 31, ejector plates 33, 34 for supporting the ejector pins, an ejector rod 50 for driving the ejector plates in the direction releasing the molded article from the mold and the drive device 20 arranged in the ejector plate 34 and driving the ejector pins a little in the direction releasing the molded article from the mold before operating the ejector rod.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for ejecting an injection-molded product from a mold with an ejector pin when the molded product partially bites into the mold without breaking the mold release balance. is there.

[0002]

2. Description of the Related Art Conventionally, generally, when biting occurs when a molded product is released from a mold, a mold release agent is applied to the surface of the molding die in advance, or the surface of the mold is polished in advance. To reduce the mold release resistance. However, when the adhesion between the molded article and the mold is strong, the mold release resistance until the molded article leaves the mold becomes large. This release resistance shows a tendency to increase as the adhesion becomes stronger, and if this release resistance varies at each projecting location, the timing at the time of release deviates, the release balance becomes worse, and as a result, at the time of release, This is a factor that causes deformation of the molded product.

[0003] In addition, this can cause abrasion or the like on the surface in contact with the molding die when the molded product is released from the mold. Therefore, the present situation is to improve the balance of mold release by increasing the number of ejector pins in places where mold release is likely to be bad or devising places where ejector pins are arranged.

[0004]

However, there is a case where the number and arrangement of the ejector pins cannot be realized due to some restrictions due to the number and arrangement of the ejector pins.

[0005] In addition, unexpected release resistance may occur depending on the processing state, and the projection balance initially assumed may be lost. When the mold release balance is lost, the ejector plate that pushes out the ejector pin may be slightly inclined. The inclination of the ejector plate may cause the ejector pins to be rubbed, adversely affecting the ejecting force, and possibly causing deformation of the molded product when ejected.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-described problems, and has as its object to reduce the initial release resistance without tilting the ejector plate even when the release resistance immediately after the protrusion is large. It is an object of the present invention to provide an apparatus and a method for ejecting a molded article.

[0007]

Means for Solving the Problems To solve the above-mentioned problems,
In order to achieve the object, an ejector for a molded article according to the present invention includes an ejector pin for releasing a molded article from a mold, an ejector plate for supporting the ejector pin, and an ejector plate for connecting the ejector plate to the molded article. A first driving unit that is driven in a direction to be released from the mold, and the ejector pin is disposed in the ejector plate, and the ejector pin is moved from the mold before the first driving unit is operated. And a second driving means for driving a small amount in the direction of releasing the mold.

[0008] The ejecting apparatus according to the present invention is characterized in that the ejecting apparatus further comprises a detecting means for detecting a mold release resistance of the molded product.

Further, in the eject device according to the present invention, the second driving means is driven in accordance with a change in the release resistance detected by the detecting means.

Further, in the eject device according to the present invention, the operation of the second driving means is stopped when the release resistance detected by the detecting means does not increase.

In addition, a method of ejecting a molded article according to the present invention includes a plurality of eject pins, the second driving means and the detecting means arranged on each of the plurality of eject pins, When the release resistance detected by each of the detection units does not increase, the operation of the second drive unit corresponding to the detection unit that has detected that the release resistance has not stopped increasing is stopped. It is characterized by:

In the ejecting method according to the present invention, an ejector pin for releasing a molded article from a mold, an ejector plate for supporting the ejector pin, and an ejector plate for separating the molded article from the mold are provided. Eject comprising first drive means for driving in the direction of molding, and second drive means disposed in the ejector plate for driving the ejector pins in a direction for releasing the molded product from the mold by a small amount. A method for ejecting a molded article using an apparatus, wherein the second driving means is driven before the first driving means is operated.

Further, in the ejecting method according to the present invention, the ejecting device is further provided with detecting means for detecting a mold release resistance of the molded article.

The ejecting method according to the present invention is characterized in that the second driving means is driven in accordance with a change in the releasing force detected by the detecting means.

In the ejecting method according to the present invention, the operation of the second driving means is stopped when the release resistance detected by the detecting means does not increase.

In the ejecting method according to the present invention, the ejecting device has a plurality of the ejecting pins, and has the second driving means and the detecting means arranged on each of the plurality of ejecting pins. And
When the release resistance detected by each of the detection units does not increase, the operation of the second drive unit corresponding to the detection unit that has detected that the release resistance has not stopped increasing is stopped. It is characterized by:

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing a schematic configuration of an ejector device having an ejection mechanism according to an embodiment of the present invention.

In FIG. 1, reference numeral 30 denotes a fixed mold plate in a mold, and 31 denotes a movable mold plate.

Reference numerals 33 and 34 serve to protrude the ejector pins 32 with ejector plates. The injection molding cycle begins with resin filling, after resin filling is completed and after a pressure-holding / cooling process, the fixed-side mold plate 30 and the movable-side mold plate 31 are separated by the mold opening operation, and then the ejector is ejected. The ejector pins 32 protruded by the ejector plates 33 and 34 by the operation are a series of motions of protruding the injection molded product 23 on the movable mold plate 31.

Further, in the molding cycle, the sensor 22 for detecting a mold opening start signal of the fixed-side mold plate 30 and the movable-side mold plate 31 and the ejector pin 32 eject the molded product 23 when the molded product 23 is moved. A load sensor 21 for measuring a release resistance generated between the side mold plates 31,
A drive device 20 is provided which enables the ejector pins to protrude in the protruding direction.

The signal from the mold opening sensor 22 is taken into the CPU 1 through the signal converter 12 and the interface 11. Similarly, the release resistance force at the time of protrusion is taken into the CPU 1 from the load sensor 21 through the signal converter 10 and the interface 9. The command value of the protrusion amount determined based on the command processed by the CPU 1 is transmitted to the protrusion drive device 20 through the interface 7 and the drive device 8 that converts the command value into the driving power of the protrusion device, and The device 20 operates. Note that the protrusion drive device can be configured using, for example, a piezoelectric element or the like.

Next, a description will be given of a change in the release resistance with time.

In FIG. 1, after the injection molded article 23 has undergone a cooling process, it is ejected by an ejector pin 32 when the fixed mold plate 30 and the movable mold plate 31 are completely opened. The inventor of the present application has confirmed by experiment that the change in the release resistance applied to the load sensor 21 due to the ejector pin protrusion distance at this time is as shown in FIG.

In FIG. 3, the release resistance measured by the load sensor 21 sharply increases immediately after the protrusion, and increases in proportion to the protrusion distance of the ejector pin. Then, when the load at the time of projecting becomes larger than the force of the molded product 23 being in close contact with the movable mold 31, the molded product 23 starts to separate from the movable mold 31. Molded product 23
The load immediately before starting to separate from the mold is the maximum release resistance Rp
Becomes The distance that the ejector pins protrude until the maximum release resistance is reached is about 0.1 mm to 0.2 mm. In the case of a molded product such as a deep rib having a large contact area between the mold and the mold, the position of the ejector pin is determined in consideration of the mold release resistance. However, when the release resistance is increased due to improper placement of the ejector pins or due to an unsatisfactory release such as a processing defect, the ejection balance is lost, and as shown in FIG. It has been confirmed by experiments of the present inventor that the ejector plate is slightly tilted. This inclination increases the possibility of causing an adverse effect on the mold release, for example, an increase in the mold release resistance due to the rubbing of the ejector pin.

Normally, the ejector rod is projected at a constant speed by the ejector rod, and if the ejected speed is too slow, the ejecting plate takes a long time to be ejected, and the molding cycle becomes longer. However, as shown in FIG. 5, the inventor of the present application has confirmed by experiment that the release resistance is reduced as the ejection speed is lower.

Therefore, as shown in FIG. 6, before ejecting the ejector plates 33, 34 with the ejector rods 50, the ejector plates 33, 34 are assembled to the ejector plate 34 in a state of being in close contact with the movable mold plate 52. Projecting device 20
By slowly extruding the molded product, the mold release can be performed smoothly without tilting of the ejector plates 33 and 34 due to the release resistance.

Next, the processing procedure will be described with reference to the flowchart of FIG.

The molding machine is set so as to project at a predetermined ejection speed, and the timing at which the mold is opened is detected by the mold opening sensor 22 shown in FIG. 1 (step S1).

Next, in the ejecting process of the ejector pins 32a, 32b, before ejecting the ejector plates 33, 34 with the ejector rod 50, the command value of the ejecting amount determined based on the command processed by the CPU 1 is used. To the ejection drive device 20 through the drive device 8 which converts the ejection command value into the drive power of the ejection device, and the ejector pins 32a and 32b are pushed out (step S2).

Immediately after the driving device 20 starts to protrude, the release resistance is measured by the load sensor 21. The load data measured by the load sensor 21 is fetched at regular intervals through the signal converter 10 and the interface 9 and is stored in the storage means 6 to monitor whether the mold release resistance is increasing (step S1). S3).

While the release resistance continues to increase, the drive device 20 increases the amount of protrusion of the ejector pin by a certain distance (step S4).

When the ejector pins are ejected by the drive unit 20, it is determined whether or not the command value exceeds the maximum ejection amount of the ejector pins 32a and 32b stored in the storage means 6 (step S5). As long as the maximum protrusion amount is not exceeded, the process returns to step S3, and the ejector pins 32a and 32b are repeatedly protruded while the mold release resistance is increasing. If the maximum amount of protrusion is exceeded, an alarm signal of mold release failure is generated to notify the operator of the abnormality (step S6).

In step S3, when the measured value indicates that the release resistance has stopped increasing, that is, the molded article has begun to separate from the mold, the ejector ejection is completed.
When the load measured by the sensors 21 corresponding to all the ejector pins on which the ejection device 20 is arranged does not increase, that is, when the state of close contact between the mold and the molded product is eliminated, the first ejection device 20 uses the first ejection device 20. The ejection is completed, and a drive signal of the ejector rod 50 for performing the second ejection is sent to the molding machine. Upon receiving this signal, the molding machine receives the ejector rod 5 as in the normal cycle.
0, and the ejection operation of the molded product is completed.

As described above, the ejector rod 50
Before the normal ejecting process of ejecting the ejector plates 33 and 34, the ejector pins are slightly ejected by the ejector pin driving devices 20 arranged on the ejector pins, whereby the close contact between the mold and the molded article can be eliminated. Further, when the ejector pin is ejected by the drive device 20, the ejector plate is ejected in a state in which the ejector plate is in close contact with the movable mold plate of the mold, that is, in a state where the ejector pin is supported. Therefore, it is possible to reduce the possibility that the balance of the release resistance is lost and the ejector plate is tilted, and further, the balance of the ejector pin protrusion such as rubbing of the ejector pin is deteriorated. In addition, since the ejector pin drive device 20 protrudes a minute distance at a slow speed, the problem that the ejector pin intrudes into a molded product caused by abrupt ejection is reduced, and the molded product in the mold at the time of release is reduced. Biting can be reduced.

[0036]

As described above, according to the present invention,
Adhesion between the molded product and the mold that occurs when the injection molded product is ejected from the mold can be reduced, keeping the mold release balance at the time of ejection uniform and minimizing the deformation of the molded product at the time of ejection. it can.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an ejector method for injection molding according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a procedure of an injection molding ejector method according to an embodiment.

FIG. 3 is a diagram illustrating a relationship between a mold release resistance of a mold and a molded product and a protrusion distance.

FIG. 4 is a diagram showing a case where the ejector system of the present invention is not adopted.

FIG. 5 is a diagram showing the relationship between the mold release resistance of a mold and a molded product and the ejection time.

FIG. 6 is a diagram showing a case where an ejector system according to an embodiment is adopted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CPU 2 Keyboard 3 CRT 4 ROM 5 RAM 6 Storage means 7, 9, 11 Interface 8 Driving device 10, 12 Signal conversion device 20 Projection driving device 21 Load sensor 22 Mold opening detection sensor 23 Injection molded product 30 Fixed mold plate 31 movable-side template 32 ejector pin 33, 34 ejector plate

Claims (10)

[Claims] 1. An ejector pin for releasing a molded product from a mold, an ejector plate for supporting the ejector pin, and a first driving device for driving the ejector plate in a direction for releasing the molded product from the mold. And a second driving means disposed in the ejector plate and driving the ejector pin by a small amount in a direction for releasing the molded product from the mold before operating the first driving means.
An ejecting apparatus for a molded article, comprising: 2. The apparatus for ejecting a molded article according to claim 1, further comprising a detecting means for detecting a release resistance of the molded article. 3. The apparatus according to claim 2, wherein the second drive unit is driven in accordance with a change in the release resistance detected by the detection unit. 4. The ejection of a molded product according to claim 3, wherein the operation of the second drive unit is stopped when the release resistance detected by the detection unit does not increase. apparatus. 5. A mold having a plurality of said eject pins, said second driving means and said detecting means arranged on each of said plurality of eject pins, and a release detected by said respective detecting means. 5. The operation according to claim 4, wherein when the resistance does not increase, the operation of the second driving means corresponding to the detecting means detecting that the release resistance has stopped increasing is stopped. Eject device for molded products. 6. An ejector pin for releasing a molded article from a mold, an ejector plate for supporting the ejector pin, and a first driving means for driving the ejector plate in a direction for releasing the molded article from the mold. A driving means of
A method of ejecting a molded product using an ejecting device having a second drive unit disposed in the ejector plate and having a small amount of drive of the ejector pin in a direction in which the molded product is released from the mold, A method for ejecting a molded article, comprising: driving the second driving means before operating the first driving means. 7. The molded article ejecting method according to claim 6, wherein the ejecting device further includes a detecting unit for detecting a mold release resistance of the molded article. 8. The method according to claim 7, wherein the second driving unit is driven in accordance with a change in the release resistance detected by the detection unit. 9. The ejection of a molded article according to claim 8, wherein the operation of the second drive unit is stopped when the release resistance detected by the detection unit does not increase. Method. 10. The eject device has a plurality of the eject pins, the second driving means and the detecting means arranged on each of the plurality of eject pins, and When the detected release resistance does not increase, a second signal corresponding to the detecting means that has detected that the release resistance has not increased.
10. The method according to claim 9, wherein the operation of the driving means is stopped.