JPH11170314A - Injection molding device, injection molding method, and ejecting method of injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a releasing resistance and keep a releasing balance uniformly by a method wherein the releasing resistance of a molding applied to an ejector pin is detected so as to control a vibrating device for exciting the ejector pin to its ejecting direction in proportion to the releasing resistance. SOLUTION: A load sensor 21 measures a releasing resistance developing in both a molding 23 and a movable retainer plate 31 when an ejector pin 32 ejects the molding 23. In addition, a vibration generating device 20 for generating minute vibration to the ejecting direction of the ejector pin is provided. Further, the detection signal of the releasing resistance at the ejecting detected with the load sensor 21 is stored through a signal conversion device 10 and an interface 9 in a CPU 1. Next, a minute vibration actuating command determined at the CPU 1 is outputted through an interface 7 to a driving device 8, which converts the signal command from the CPU 1 to the driving force of the vibration generating device 20 so as to generate the minute vibration. Thus, the seizure of the molding 23 to the retainer plate 31 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding apparatus using an ejector pin for ejecting an injection molded product from a mold, an injection molding method, and a method for ejecting an injection molded product.

[0002]

2. Description of the Related Art In general, when a so-called biting occurs in which an injection molded product and a molding die come into close contact with each other at the time of release, a release agent is applied to the surface of the molding die or the surface of the molding is polished. ,
The device is designed to reduce the release resistance between the mold and the molded product.

[0003] 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 extremely large. This release resistance tends to increase as the adhesion becomes stronger, and if the release resistance varies at each protruding position of the molded product, the timing at the time of release deviates and the release balance becomes poor. It becomes a factor that causes deformation of the molded product at the time of mold release. The deformation that occurs in this way also causes scratches and the like on the surface of the molded product that is in contact with the molding die. Therefore, under the present circumstances, the number of ejector pins provided for a part of a molded product that is difficult to release is increased, and the arrangement position of the ejector pins is devised to improve the balance of release.

[0004]

However, there are cases in which the desired number and positions of the ejector pins cannot be realized due to various restrictions such as the design of the mold. In such a case, the mold release balance is uniform. I can't keep it.

An object of the present invention is to provide an injection molding apparatus, an injection molding method, and an injection molding method for ejecting an injection-molded article capable of reducing the mold release resistance of the molded article and maintaining a uniform mold release balance. is there.

[0006]

According to an injection molding apparatus of the present invention, after a product is injection-molded using a molding die, the molded product is molded from the molding die using an ejector pin protruding from the molding die. In an injection molding apparatus for releasing a mold, detecting means for detecting a release resistance of the molded product applied to the ejector pin when releasing the molded product, and a vibration device capable of vibrating the ejector pin in a protruding direction. And control means for controlling the vibration device in accordance with the release resistance detected by the detection means.

The injection molding method according to the present invention is an injection molding method in which after a product is injection molded using a molding die, the molded product is released from the molding die using an ejector pin protruding from the molding die. Wherein, when the molded product is released from the mold, a release resistance of the molded product applied to the ejector pin is detected, and the ejector pin is vibrated in a protruding direction according to the release resistance. .

[0008] The method of ejecting an injection-molded article of the present invention comprises:
Using an ejector pin protruding from a molding die for injection molding, in an ejection method of an injection molded product for ejecting a molded product from the molding die, when the molded product is ejected, the molded product that is applied to the ejector pin is ejected. It is characterized in that the release resistance is detected and the ejector pin is vibrated in the protruding direction in accordance with the release resistance.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic structural view of an ejector device provided in an injection molding apparatus according to the present invention. In FIG.
Numeral 30 is a mold plate on the mold fixed side, and 31 is a mold plate on the mold movable side. Ejector plates 33 and 34 have a role of projecting the ejector pins 32. The cycle of injection molding starts with filling of the resin into the cavity formed by the mold plates 30 and 31, and after the filling of the resin is completed,
After the pressure-suppressing / cooling step, the fixed-side mold plate 30 and the movable-side mold plate 31 are separated by the mold opening operation. Thereafter, by the ejector ejecting operation, the ejector plates 33 and 34 eject the ejector pins 32, and the ejector pins 32 eject the injection molded article 23 located on the movable mold plate 31.

In such a molding cycle, the mold opening detection sensor 22 senses the start of mold opening of the fixed mold plate 30 and the movable mold plate 31, and the load sensor 2 causes the ejector pin 32 to protrude the molded product 23. At this time, the mold release resistance generated between the molded product 23 and the movable mold plate 31 is measured. 20 is
This is a vibration generating device that generates a minute vibration in the direction in which the ejector pins protrude.

The detection signal of the mold opening sensor 22 is transmitted to the CP through the signal converter 12 and the interface 11.
It is taken into U1. Similarly, the detection signal of the release resistance at the time of protrusion detected by the load sensor 21 is transmitted to the CPU through the signal converter 10 and the interface 9.
It is taken into 1. Further, a small vibration operation command determined based on the command processed by the CPU 1 is output from the interface 7 to the driving device 8. The driving device 8 transmits a signal instructed from the CPU 1 to the vibration generating device 2.
The driving force is converted to zero, and the vibration generator 20 generates a minute vibration. Reference numeral 24 denotes a sensor for detecting the movement position of the ejector plates 33 and 34, that is, the protruding position of the ejector pin 32. The detection signal is sent to the CPU 1 through the signal converter 14 and the interface 13.
It is taken into 1.

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

In FIG. 1, after the injection-molded article 23 undergoes a cooling process, when the fixed mold plate 30 and the movable mold plate 31 are fully opened, the injection molded product 23 is projected upward by ejector pins 32 in the figure. At this time, it was confirmed by experiment that the temporal change of the release resistance applied to the load sensor 21 was as shown in FIG. In FIG. 3, the release resistance measured by the load sensor 21 increases with the passage of time, and the load when the molded product 23 protrudes becomes larger than the force of the molded product 23 being in close contact with the movable mold plate 31. When the product 23
Starts to separate from the movable mold plate 31. In this way,
By measuring the load applied to the ejector pins 32 when the molded product 23 projects, the maximum projecting load Rp in FIG. 3 can be obtained.

When the contact area between the molded product 23 and the mold plate 31 is large, as in the case of a molded product having deep ribs, the mold release resistance increases. When such a molded product 23 is protruded, the deformation of the resin as the molded product 23 or the buckling of the ejector pin occurs due to an experiment, and the release resistance force that repeatedly increases and decreases as shown in the area a of FIG. Curve was observed. Therefore, before entering the region of the mold release resistance in FIG. 4A, a small vibration is applied to the ejector pin 32 as described below in order to reduce the adhesion force between the molded product 23 and the mold plate 31.

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

First, the timing at which the mold is opened is detected by the mold opening sensor 22 shown in FIG. 1 (step S).
1). Next, in the process of ejecting the ejector pin 32 at a predetermined ejection speed, the release resistance force immediately after the start of the ejection is measured by the load sensor 21 (step S2). When ejecting the ejector pin 32 with a constant force, the release resistance can be determined from the pushing speed. The load data measured by the load sensor 21 is stored in the storage unit 6 via the signal converter 10 and the interface 9 and is also used as data for predicting the release resistance by the CPU 1. For example, based on a temporal change in the release resistance detected by the load sensor 21, the release resistance is determined to be a predetermined value in FIG. It can be determined whether or not the region a is equal to or more than the release resistance R1.

Further, the state of the temporal change of the release resistance and the method of oscillating the ejector pin 32 corresponding to the state are stored in the storage means 6 in advance, and the release resistance obtained in step S2 is stored. Based on the values, data (for example, vibration width and frequency) for driving the vibration generator 20 when the ejector pins 32 protrude is created and selected (step S3).

Next, the drive data of the vibration generator 20 created and selected in step S3 is output to the drive unit 8 via the interface 7. The drive device 8 causes the vibration generator 20 to slightly vibrate in the protruding direction based on the command (step S4). At this time, the width of the vibration of the vibration generator 20 is set to “0”, that is, not driven, until the release resistance enters the region a where the release resistance is larger than R1 in FIG. At this time, the vibration generating device 20 may be driven in accordance with the release resistance. Of course, the vibration generator 20 may be driven from the start of the mold opening.

Thereafter, it is determined whether or not the vibration end time has been reached (step S5). If the time has not been reached, the process returns to step S2, and if the time has been reached, the drive of the vibration generator 20 is stopped. (Step S6). In the case of this example, the protrusion position (projection amount) of the ejector pin 32 is detected by the sensor 24 and the ejector pin 3 is detected.
2 is set as the end time of the vibration when it is protruded to a position beyond the time of the maximum load Rp in FIG. For example, the protruding position of the ejector pin 32, which is used as a criterion for determining the end time, may be stored in advance in the storage means 6 for each molded product 23. By inputting from such as the above, the CPU 1 can also take in and set the corresponding criterion.
Further, the vibration generation device 20 may be driven until the release operation is completed, with the vibration end time being the release end time.

As described above, the mold release resistance is measured, and the ejector pin 32 is vibrated in the protruding direction in accordance with the measured value.
3 bite can be reduced.

In this embodiment, a single ejector pin has been described. However, in an ejecting method using a plurality of ejector pins, it is also possible to suppress deformation of a molded product due to a variation in release resistance at the time of release. . For example, FIG.
When using the ejector pins 32a and 31b such as
That is, when the protruding position by the ejector pins 32a has stronger adhesion between the molded product 23 and the mold plate 31 and the protruding position by the ejector pins 32b is weaker, when the ejector pins 32a and 32b protrude, they are slightly smaller. Also, there is a possibility that the molded article 23 is deformed as shown in FIG. The present invention can be applied as a means for preventing such deformation, and it is sufficient to vibrate the ejector pins 32a and 32b individually or in association with each other in accordance with the release resistance force. FIG. 7 shows an example of a case where the vibration device 20 is assembled so as to have such a configuration. In this case, the ejector pin may be caused to vibrate when the release resistance exceeds a certain value.

[0023]

As described above, according to the present invention,
When ejecting an injection-molded product from a molding die with an ejector pin, by vibrating the ejector pin in the protruding direction in accordance with the mold release resistance, it is possible to reduce the adhesion generated between the molded product and the mold, As a result, the mold release balance at the time of projecting the molded product can be kept uniform, and the deformation of the molded product at the time of projecting can be minimized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a control system of an injection molding apparatus according to the present invention.

FIG. 2 is a flowchart for explaining a mold release operation in the injection molding apparatus of FIG.

FIG. 3 is an explanatory diagram of a change over time in a mold release resistance when adhesion between a mold and a molded product is relatively low.

FIG. 4 is an explanatory diagram of a change with time in release resistance when the adhesion between a mold and a molded product is relatively high.

FIG. 5 is a schematic configuration diagram of a main part of an injection molding apparatus including a plurality of ejectors.

6 is an explanatory diagram of a release operation state in the injection molding apparatus of FIG.

FIG. 7 is an explanatory diagram when the present invention is applied to the injection molding apparatus of FIG.

[Description of Signs] 1 CPU 2 Keyboard 3 CRT 4 ROM 5 RAM 6 Storage Means 7, 9, 11, 13 Interface 10, 12, 14 Signal Converter 20 Vibration Generator 21 Load Sensor 22 Mold Opening Sensor 23 Injection Molded Product REFERENCE SIGNS LIST 30 Fixed-side mold plate 31 Movable-side mold plate 32 Ejector pin 33, 34 Ejector plate

Claims (13)

[Claims] After injection molding a product using a mold,
Using ejector pins protruding from the mold,
In an injection molding apparatus for releasing the molded product from the molding die, when the molded product is released from the mold, detection means for detecting a release force of the molded product applied to the ejector pin, and ejecting the ejector pin An injection molding apparatus comprising: a vibrating device capable of vibrating in a direction; and control means for controlling the vibrating device in accordance with a release resistance detected by the detecting means. 2. The apparatus according to claim 1, wherein the control unit controls a vibration width and / or a vibration frequency of the vibration device according to a release resistance detected by the detection unit. Injection molding equipment. 3. The injection molding apparatus according to claim 1, wherein the control unit controls a driving time of the vibrating device according to a release resistance detected by the detection unit. . 4. The apparatus according to claim 1, wherein the control means drives the vibration device when the release resistance detected by the detection means is equal to or more than a predetermined value. Injection molding equipment. 5. An ejection amount detecting means for detecting an ejection amount of the ejector pin, wherein the control means detects when an ejection amount of the ejector pin detected by the ejection amount detecting means becomes a predetermined amount or more. The injection molding apparatus according to any one of claims 1 to 4, wherein the vibration device is stopped. 6. The control unit stops the vibrating device when an amount of protrusion of the ejector pin detected by the amount of protrusion detection unit is equal to or greater than a specified amount according to a type of the molded product. 6. The method according to claim 5, wherein
3. The injection molding apparatus according to claim 1. 7. A plurality of ejector pins, wherein said detecting means detects a release resistance applied to each of said plurality of ejector pins, and said vibrating device individually applies each of said plurality of ejector pins. Wherein the control means causes each of the plurality of ejector pins to be individually vibrated by the vibrating device in accordance with a release resistance force of each of the plurality of ejector pins detected by the detection means. The injection molding apparatus according to any one of claims 1 to 6, wherein: 8. After injection-molding a product using a molding die,
Using ejector pins protruding from the mold,
In the injection molding method for releasing the molded product from the molding die, when the molded product is released, a release resistance of the molded product applied to the ejector pin is detected, and according to the release resistance. An injection molding method, wherein the ejector pin is vibrated in a protruding direction. 9. The injection molding method according to claim 8, wherein a vibration width and / or a vibration frequency of the ejector pin is changed according to the release resistance. 10. A plurality of ejector pins, wherein a release resistance force applied to each of the plurality of ejector pins is detected, and a plurality of ejector pins are provided in accordance with the release resistance force of each of the plurality of ejector pins. The injection molding method according to claim 8, wherein each is individually vibrated. 11. An injection molding method for ejecting a molded product from an injection mold using an ejector pin protruding from a mold for injection molding, wherein the ejector pin is ejected when the molded product is ejected. An ejection method for an injection-molded article, comprising detecting a mold release resistance of the molded article to be applied, and vibrating the ejector pin in a protruding direction according to the mold release resistance. 12. The method according to claim 11, wherein a vibration width and / or a vibration frequency of the ejector pin is changed according to the release resistance. 13. A plurality of ejector pins, wherein a release resistance applied to each of the plurality of ejector pins is detected, and a plurality of ejector pins are provided in accordance with the release resistance of each of the plurality of ejector pins. The method for ejecting an injection-molded product according to claim 11, wherein each of the components is vibrated individually.