JPH04201224A - Precision molds and molded products - Google Patents

Abstract

PURPOSE:To realize the mechanism reducing the deformation of a mold and the mold structure, in which deformation is difficult to be generated, by preventing the deformation of a cavity by resin pressure injected or the lowering of the parallelism of a stationary mold and a movable mold forming the cavity even when the cavity is deformed. CONSTITUTION:The quantity of deformation is detected by a deformation detecting sensor 13 installed to a movable mold 6, and the signal is transmitted over a control section 11. The control section 11 compares the quantity of deformation with a previously input deformation-quantity target value and decides it, and controls the injection speed and/or injection pressure of a molding-machine injection section 12 so that the quantity of deformation reaches the target value or less. When the control section 11 controls a hydraulic cylinder 15 in the rear section of a support 14 in response to the quantity of deformation detected by the deformation detecting sensor 13, the hydraulic cylinder 15 varies hydraulic power in response to a controlled variable. The hydraulic cylinder 15 applies pressure to the support 14 from a rear section, and the support 14 is finely forwarded or finely retreated against resin filling pressure. The deformation of the movable mold 6 is corrected through a back plate 19 and a thermally insulating board 18.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mold for plastic injection molding, and in particular to deformation of the mold for molding high-precision precision molded products such as optical components with excellent parallelism. The present invention relates to a prevention mechanism, a molded product using the mold, and an injection molding machine that performs molding using the mold.

[Conventional technology]

Conventionally, in the case of high-precision precision molding molds for optical parts, etc., operations such as heating, separating the gate, and applying pressure are performed to improve precision, as described in Japanese Patent Publication No. 1-14010. was. Specifically, in addition to the temperature control mechanism of the heater for heating, the cutter and cutter drive mechanism for gate separation, the cylinder mechanism and its control mechanism for pressurization, and the control of each mechanism in a timely manner. It was equipped with control software to ensure the necessary accuracy.

[Invention or problem to be solved]

Although the above-mentioned conventional technology applies heat and pressure to the resin in the cavity through the mold, such as heating and pressurizing, and separating the gate, no consideration is given to the deformation of the mold due to these loads. First, deformation of the mold due to resin filling pressure in addition to these loads was unavoidable. As a result, the cavity is deformed and the parallelism between the fixed and movable parts is reduced, resulting in a problem in that the molded product cannot have good parallelism or dimensional accuracy. There is also the problem that the mold becomes complicated and maintenance cannot be simplified.

An object of the present invention is to provide a mechanism for detecting and reducing such deformation of a mold, and a mold structure that does not easily cause deformation.

Another object of the present invention is to provide an injection molding die that has a simple structure and can produce highly accurate molded products without causing the above-mentioned deformation without heating, pressurizing, or separating the gate. be.

[Means to solve the problem]

In order to achieve the above object, a sensor for detecting the amount of deformation is provided in a portion of the mold that forms the cavity to detect the amount of deformation and the amount of deformation in the vicinity of the cavity. Further, a control section for determining the detected amount of deformation is provided, and this control section is coupled to the control mechanism of the injection section of the injection molding machine to control the injection pressure and injection speed.

In addition, at the same time or separately from the injection control of the molding machine, there is an extrusion plate that fixedly supports an extrusion pin that performs extrusion for releasing the molded product.
Pressure applying means was provided at the rear of the support, which serves as a sliding guide for extrusion and also to reduce deformation from the extrusion plate sliding gap of the mold due to resin filling pressure. This pressure applying means is also combined with a control section that detects and determines the amount of deformation of a displacement detection sensor provided near the cavity, so as to control the pressure in accordance with the amount of deformation caused by the resin filling pressure.

In addition, the cavity part and runner part that receive the resin filling pressure are separated from the movable mold and made into separate parts as a movable insert piece and a runner insert piece, and a movable insert piece support part and a runner insert piece support part are provided at the rear of each insert piece. The parts were joined together. Furthermore, pressure applying means was arranged at the rear of each support part to receive resin filling pressure.

This pressure applying means is also coupled to a control section that detects and determines the amount of displacement of the displacement detection sensor, so that the applied pressure is controlled in accordance with the amount of deformation caused by the resin filling pressure. A hydraulic cylinder and/or a wedge mechanism were used as these pressure applying means.

Separately, the movable insert piece and runner insert piece that receive resin filling pressure are coupled to the movable mounting plate via a support portion or directly to reduce mold deformation into the extrusion plate sliding gap. did. Furthermore, high-rigidity materials including ceramics are used for the movable insert pieces, runner insert pieces, and supporting parts.
Reduced resin pressure deformation.

[Effect]

A sensor installed near the cavity that detects the amount of displacement detects the deformation of the mold under the resin filling pressure, and when a displacement signal is sent to the control section, the control section that receives this signal controls the injection molding machine. A control signal is sent to the injection section to control the resin injection speed and/or injection pressure of the injection section of the injection molding machine. That is, when the detected amount of deformation is larger than the target value, the injection speed and/or injection pressure is controlled in a direction to reduce it, and in the opposite case, it is controlled in the opposite direction. This control allows the amount of deformation of the mold to be kept below the target value, so a precision molded product that maintains parallelism can be obtained. Similarly, the control section controls the pressure applying means provided at the rear of the support, so that when the mold is deformed due to the resin filling pressure, the pressure applying means generates a counterbalancing pressure to the deformation of the mold. Reduced the amount of mold deformation. As a result, the amount of deformation can be suppressed below the target value, making it possible to obtain a precision molded product that maintains parallelism.

Separately from this, a cavity part and a runner part, which are separated from the movable mold and receive resin filling pressure, are separate parts of a movable insert piece and a runner insert piece, and the rear part thereof is connected to a pressure applying means through a support part or directly. did. By controlling this pressure applying means by a control unit that detects the amount of deformation, a pressure that counteracts the resin filling pressure is generated to reduce the amount of deformation of the mold. As a result, it is possible to obtain a precision molded product whose deformation amount is less than the target value and which maintains parallelism. Note that the pressure applying means can be a hydraulic cylinder and/or a wedge mechanism to obtain the same effect.

Furthermore, apart from these, the cavity part and the runner part, which are separated from the movable mold and receive the resin filling pressure, are made into separate parts of the movable insert piece and the runner insert piece, and the rear part is connected to the above-mentioned part through the support part or in connection with the cavity part and the runner part. By combining with the movable mounting plate and using high-rigidity materials including ceramics for the movable insert piece, runner insert piece, and support part, the amount of mold deformation can be kept below the target value, so parallelism can be maintained. Precision molded products can be obtained.

Furthermore, in a mold equipped with the pressure applying means, even if deformation of the mold due to resin filling pressure includes deformation of the molding machine die plate, the amount of deformation of the movable mold itself is reduced by applying pressure. Therefore, a molded product that maintains parallelism can be obtained regardless of the deformation of the die plate of the molding machine.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below using FIG. FIG. 1 is a longitudinal sectional view of an injection molding machine injection section and an injection mold. In the figure, 1 is the runner part, which is the resin passage of the mold, and 2
is the injection molding machine injection section (hereinafter simply referred to as the molding machine injection section) 1
2 is a sprue part that guides the resin into the runner part 1; 3 is a cavity groove that shapes the resin (not shown) that has passed through the runner part 1 and the gate part 16; 4 is a fixed mold that forms one side of the cavity 3; , 6 are movable molds forming the other side of the cavity 3. 8 is an extrusion pin that is fixed to the extrusion plate 9 and moves forward together with the extrusion plate 9 to extrude the molded product when the mold is opened as the molding machine extrusion rod (not shown) moves forward; 10 is an extrusion pin for sliding the extrusion plate 9; a spacer block forming a void 2o;
A deformation detection sensor 13 is located near the cavity 3 and detects deformation of the movable mold 6. A deformation detection sensor 11 receives a signal from the deformation detection sensor 13 and controls the injection section 12 of the molding machine and/or the hydraulic cylinder 15 at the rear of the support 14. 14 is a guide for the forward and backward sliding movement of the extrusion plate 9, and a sabot h that reduces pressure deformation of resin filling into the extrusion plate gap 20; 15 is a support 1;
This is a hydraulic cylinder for counteracting the pressure applied to the movable mold 6 and reducing deformation of the movable mold 6. When resin is injected from the injection section 12 of the molding machine into the mold configured as described above, the resin that has passed through the sprue section 2, runner section 1, and gate section 16 fills the cavity 3. The mold that received the resin filling pressure was
As shown in the figure, the runner part 1 faces the extrusion plate sliding gap 20,
The movable mold 6 is deformed so that the cavity 3 expands left and right. As a result, as shown in FIG. 4, the molded product 3' shaped in the cavity 3 cannot maintain parallelism on both sides as indicated by a and a', making it impossible to obtain the target value.

Therefore, the amount of deformation is detected by the deformation detection sensor 13 provided on the movable mold 6, and this signal is sent to the control section 11. Upon receiving this signal, the control section 11 compares and determines the amount of deformation with a deformation amount target value inputted in advance, and controls the injection speed and/or injection pressure of the injection section 12 of the molding machine so that the amount of deformation is equal to or less than the target value. . When the injection speed and/or injection pressure is reduced by this control, the amount of deformation of the movable mold 6 is reduced,
Convergence within the target value is possible. For example, the injection pressure is 15
The amount of deformation of the movable mold 6, which was 60 μm in the case of 00 kg/an(m), was reduced to 40 μm when the injection pressure was lowered to 1200 kg/an(m), and the target could be achieved.

Further, in accordance with the amount of deformation detected by the deformation detection sensor 13, the control unit 11 controls the hydraulic cylinder 15 at the rear of the support 14.
When this is controlled, the hydraulic cylinder 15 increases or decreases the hydraulic pressure according to the controlled amount. By increasing and decreasing this hydraulic pressure, the hydraulic cylinder 15 applies pressure to the support 14 from the rear, and causes the support 14 to move forward and backward slightly while counteracting the resin filling pressure.

Due to this displacement of the support 14, the back plate 19,
The deformation of the movable mold 6 is corrected through the heat insulating plate 18, and the movable mold 6 reduces deformation into the extrusion plate sliding gap 20 despite the application of resin filling pressure. For example, resin filling pressure 1200k
g/-, look for the pressure of the hydraulic cylinder 15.
By controlling it to g/7, the amount of deformation of the movable mold 6 is reduced to 20μ.
It was possible to reduce this to m. As a result, the parallelism of the molded product formed in the cavity 3 could be improved to 0.01°. It should be noted that whether the support 14 is used also as a sliding guide for the extrusion plate 9 or simply as a support for reducing the deformation of the movable die 6, both are effective in reducing deformation. Needless to say. Also support 14
Although the hydraulic cylinder 15 that applies hydraulic pressure from the rear is embedded in the movable mounting plate 7 in FIG. It goes without saying that the same effect as in Fig. 1 can be obtained even if it is installed in a section. Furthermore, it goes without saying that it is effective to apply different hydraulic pressures to the hydraulic cylinders 15 that apply pressure from the rear to the multiple supports 14 by controlling them differently depending on their positions. Nor.

Next, another embodiment shown in FIG. 2 will be described.

In the figure, parts given the same numbers as in FIG. 1 have the same functions and effects as in FIG. 1. In the figure, reference numerals 21 and 24 are a movable insert piece and a runner insert piece that are separated from the movable die 6 and made into separate parts. Reference numeral 17 denotes a resin pressure support portion that supports the movable insert piece 21 and the runner insert piece 24 and receives the hydraulic pressure of the hydraulic cylinder 15. An extrusion bottle 25 is fixed to the extrusion plate 9 and extrudes the molded product from the movable mold 6 when the mold is opened by the forward motion of the extrusion plate 9. In the precision molding die constructed in this way, when the resin passes through the sprue part 2 and the runner part l and fills the cavity 3, as in FIG. 21. Resin filling pressure is applied to the runner insert piece 24 and the movable mold 6 is deformed. A deformation detection sensor (not shown) detects this, and a control section (not shown) controls the hydraulic cylinder 15 according to the amount of deformation, thereby increasing or decreasing the hydraulic pressure of the hydraulic cylinder 15. Increases and decreases in the hydraulic pressure of the hydraulic cylinder 15 are transmitted to the movable input piece 21 and the runner input piece 24 via the resin pressure support section 17.

The movable insert piece 21 and the runner insert piece 24 cancel deformation of the movable mold 6 by mutually canceling the hydraulic pressure and the resin filling pressure. For example, when the resin filling pressure is 1200 kg/-, the hydraulic cylinder 15 is controlled by the control section to generate a hydraulic pressure of 950 kg/-, transmits the pressure to the runner input piece 24 via the resin pressure support section 17, and counteracts the resin filling pressure. Movable type 6 by making
It was possible to reduce the deformation to 20 μm. In this embodiment, similarly to the embodiment shown in FIG.
Needless to say, it can be used as a guide for the sliding movement of item 9. Also, the hydraulic cylinder 15 is embedded in the movable mounting plate 7, but as in the embodiment shown in FIG. Needless to say, the same effect can be obtained even if it is installed between the support part 17 and the resin pressure support part 17.

Next, another embodiment shown in FIG. 5 will be described.

In FIG. 5, parts given the same numbers as in FIGS. 1 and 2 have the same functions and effects. 5. 21' is a movable insert piece, 24' is a runner insert piece, and the rear part of each piece is a sloped surface. 22 is a wedge having the same slope as the rear part of the movable insert piece 21' and the runner insert piece 24'. 23 is a wedge drive unit that controls the forward and backward movements of the wedge 22. In the precision molding mold configured in this way, as in the first and second embodiments, when the cavity 3 is filled with resin, the movable mold 6 is deformed, and a deformation detection sensor ( (not shown) and a control section (not shown) to control the wedge driving section 23. The wedge drive unit 23 moves the wedge 22, which contacts the runner entry piece 24' and the movable human piece 21' through the slope part, slightly forward and backward in response to the control signal from the control unit, and this operation is performed through the slope part. The runner entry piece 24° and the movable human piece 21° are individually moved slightly forward and backward by counteracting the displacement caused by the resin filling pressure. As a result, the parallelism of the resin inside the cavity 3 was improved to within 0.01°.

As described above, according to the embodiments described in the first to third embodiments, not only the deformation of the movable mold 6 but also the deformation that occurs in the molding machine die plate (not shown) in which the center part opens by about 100 μm can be prevented. Absorb the influence and reduce the parallelism of cavity 3 to 0.01
° (the amount of deformation of the movable mold is 20 μm).

Next, another embodiment will be described using FIG. 6.

In FIG. 6, the parts labeled with the same numbers as those in FIGS. 1 to 5 have the same functions and effects.

21a in FIG. 6 is a movable insert piece, and 24a is a runner insert piece, which are separate parts independent of the movable mold 6. They are made of a highly rigid material such as ceramics, and are integrally fixed to the movable mounting plate 7. ing. The sprue part 2. When the cavity 3 is filled with resin (not shown) from an injection molding machine (not shown) that has passed through the runner part 1, the runner part 1. The cavity 3 tends to deform toward the extrusion plate sliding gap 20.

At this time, since the runner insert piece 24a and the movable insert piece 21a are made of a highly rigid material such as ceramics, and are directly supported by the movable mounting plate 7, large deformations do not occur due to dust. .

For example, when the resin pressure is 1200 kg/-, the amount of mold deformation is 3
5μm, and the parallelism is 0.02° against the target parallelism of 0.02°.
A precision molded product with an angle of 0.02° could be obtained.

As described above, since the parallelism that satisfies the target can be obtained in each of the embodiments, precision molded products for lenses, disks, and other optical cells can be obtained. Furthermore, by controlling the injection section in response to the deformation signal from the mold, an injection molding machine capable of adjusting the resin injection speed and injection pressure was realized. It goes without saying that with regard to this injection molding machine, in addition to the injection speed and injection pressure, the amount of mold deformation may be reduced by adjusting the resin temperature, amount of plasticized resin, back pressure, etc. .

〔Effect of the invention〕

As explained above, according to the present invention, the amount of deformation of the mold subjected to the resin filling pressure is detected by the sensor provided near the cavity, and the injection speed and/or Alternatively, by controlling the injection pressure, it became possible to reduce the amount of mold deformation to below the target value.

For example, when the resin filling pressure is 1500 kg/ci, the amount of deformation near the mold cavity is 60 μm, but if you control the injection section of the injection molding machine to lower the resin filling pressure to 120 kg/ci, the amount of deformation will be reduced to the target value. It was possible to reduce the thickness to 40 μm.

In addition, depending on the amount of deformation, the hydraulic cylinder which is the pressure applying means at the rear of the extrusion plate sliding support and/or (the two that control the rust mechanism) The amount of mold deformation could be reduced to 20 μm.

Separately from this, in the case where a pressure applying means is provided at the rear of the movable insert piece and the rear of the runner insert piece, which are separate parts from the movable mold, via a support part or directly, the pressure is applied according to the amount of deformation. Since the pressure of the means is controlled, when the resin filling pressure is 1200 kg/ml, the amount of mold deformation is reduced to 2 with the hydraulic cylinder pressure 950 kg/alt, which is the pressure adding means.
It was possible to set it to 0 μm.

As described above, by providing a pressure applying means to counteract the resin filling pressure applied to the cavity, not only the deformation of the mold but also the deformation of the die plate of the molding machine can be absorbed and mold deformation i.
It is possible to obtain a precision molded product with a parallelism of less than 20 μm and a parallelism of less than 0.01°.

Furthermore, apart from these, the rear part of the movable insert piece and the rear part of the runner insert piece, which are separate parts from the movable type, are connected to the movable mounting plate via the support part or directly, and the movable insert piece, the runner insert piece and the support part By using a highly rigid material containing ceramics as the material, the amount of mold deformation at a resin filling pressure of 1200 kg/batch can be reduced to 35 μn1, and a precision molded product with a parallelism of 0.02° or less can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a side view of the injection part of an injection molding machine and a longitudinal sectional view of the mold showing one embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the mold showing another embodiment of the invention, and FIG. 3 is a longitudinal sectional view of the mold. FIG. 4 is a vertical cross-sectional view showing deformation due to resin pressure in the vicinity of a conventional mold cavity, FIG. 4 is a vertical cross-sectional view showing a decrease in parallelism of a molded product, and FIGS. FIG. 1 Runner part, 2 ・Sprue part, 3... Cavity, 4
... Fixed type, 6... Movable type, 9... Extrusion plate, 12
- Injection molding machine injection section, 13... Displacement detection sensor, 1
4...Support, 15...Hydraulic cylinder, 20...
Extruded plate sliding gap. Renrenjin-h Katsuo Ogawa Katsutoshi I Z Taku 3 Koku 4 Koku 3' S Entrance

Claims (1)

[Claims] 1. In the cavity of an injection mold formed by a fixed mold and a movable mold, the cavity is not deformed by the pressure of the injection resin, or even if the cavity is deformed, the fixed mold and movable mold that form the cavity are parallel to each other. A precision mold that is characterized by its ability to prevent a drop in temperature. 2. The precision molding mold according to claim 1, characterized in that one or more sensors for detecting deformation or displacement of the fixed mold and/or the movable mold are provided near the cavity. 3. The precision molding mold according to claim 2, wherein the injection speed and/or injection pressure of the injection section of the injection molding machine are controlled in accordance with the signal detected by the sensor. 4. Pressure applying means for preventing deformation of the movable mold plate is provided at one or more places in the sliding gap in the rear part of the movable mold, in which the extrusion plate for extruding the molded product from the mold slides. The precision molding die according to claim 1. 5. The precision molding die according to claim 4, wherein the pressure of the pressure applying means is controlled in accordance with a signal detected by the sensor. 6. A claim characterized in that the pressure applying means is installed at an end or in the middle of a support inserted between a movable mold for sliding the extrusion plate and a movable mounting plate for attaching the movable mold to a molding machine. Precision molding mold according to item 4 or 5. 7. The precision molding mold according to claim 2, wherein the runner part and the cavity part formed in the movable mold are separate parts that are not integrated with the movable mold, and a pressure applying means is provided at the rear thereof. 8. The precision molding die according to claim 7, wherein the pressure of the pressure applying means is controlled in accordance with a signal detected by the sensor. 9. The precision molding die according to claim 4 or 7, wherein the pressure applying means is a hydraulic cylinder. 10. The precision molding die according to claim 4 or 7, wherein the pressure applying means has a structure in which pressure is obtained by moving a wedge back and forth. 11. The runner part and the cavity part formed in the movable mold are each separate parts that are not integrated with the movable mold, and the rear part thereof is directly connected to a movable mounting plate for attaching the movable mold to a molding machine. Precision molding mold described in item 1. 12. The precision molding die according to claim 11, wherein the runner portion and the cavity portion, which are provided as separate parts from the movable mold and are directly connected to the movable mounting plate, are made of a highly rigid material. 13. The precision molding die according to claim 12, wherein the high-rigidity material used for the runner part and the cavity part, which are separate parts, is ceramic. 14. Molded using a precision mold in which the cavity is not deformed by the injection resin pressure as described in claim 1, or the parallelism of the fixed mold and the movable mold that form the cavity does not decrease even if the cavity is deformed. Precision molded products for lenses, disks, optical cells, etc., which are characterized by: 15. An injection molding machine, characterized in that injection speed and/or injection pressure are controlled in accordance with a deformation or displacement signal from a sensor provided in the precision mold according to claim 1.