JPS63160813A - Injection mold - Google Patents

Abstract

PURPOSE:To enable injection molding of high-precision molded product by a simple and low-cost mold, by a method wherein molten resin filled in the inside of a cavity through injection is compressed by a preset compression quantity through a shape memory effect of a member for compression operation. CONSTITUTION:When molten resin is injected into a cavity 2 through a sprue, runner 8 gate 9, then inserts 3, 5 each are moved in the direction enlarging capacity of the cavity 2 in the injection pressure of the molten resin, in injection molding of a high-precession optical parts such as plastic lens. As springs 14, 15 for compression operation has been kept deformed beforehand in a contracting direction, they don't block a movement of each of inserts 3, 5. Also temperatures of springs 14, 15 each for compression operation composed of a shape memory alloy are raised by that of the molten resin filled in the inside of the cavity 2. At the time of arrival fo the springs at the transformation point, the springs 14, 15 each for compression operation are restored in an extending direction by their shape memory effect. The resin of the inside of the cavity 2 is compressed through extension of the springs 14, 15 and molded into a molded product of a desired form.

Description

[Detailed Description of the Invention] [Industrial Application Field]
This invention relates to an injection mold for injection molding a quadrilateral.

[Prior Art] When injection molding high-precision optical components such as plastic lenses, it is required to mold the molded product so that no optical distortion occurs. As a means of satisfying this request,
In the first injection stage in which molten resin is filled into the gear cavity, the volume inside the cavity is expanded by setting the required mold opening amount between the fixed mold part and the tTr movable mold part.
After the filling of the molten resin is completed, the movable mold section is moved to uniformly compress the molten resin in the cavity, and the molding is carried out while taking into account the shrinkage of the molded product in the cavity as it cools.

L: Various molding methods of this type have been proposed in the past, such as JP-A-58-167134 Gin and JP-A-58
There are techniques disclosed in Japanese Patent Application Laid-open No. 197032, Japanese Patent Application Laid-Open No. 61-83016, and Japanese Patent Publication No. 35926/1983.

[Problems to be solved by the invention] L In each of the conventional technologies, molding molds and molding machines are equipped with complex hydraulic mechanisms (hydraulic control waves) (Japanese Patent Application Laid-open No. 58-167134, (Techniques disclosed in Japanese Patent Application Laid-open No. 61-83016), equipped with a complicated toggle mechanism (toggle link mechanism), (Techniques disclosed in Japanese Patent Application Laid-open No. 58-197032 and Patent Publication No. 61-35926) )
As the molding equipment was configured to expand the volume inside the cavity and perform compression operations, the molding equipment became complicated.
There was a problem that the cost was extremely high.

The present invention has been made in view of the above-mentioned problems of the prior art, and provides an injection molding die that enables injection molding of high-precision molded products using an extremely simple and low-cost die. The purpose is to

[Means for Solving the Problems] The present invention provides a movable insert having a molding surface on the fixed mold base portion and/or the movable mold base portion in a direction that expands or reduces the internal volume of the cavity. The movable insert is freely provided, and the movable insert is configured to be able to be pressed and moved by a preset movable amount in a direction to reduce the internal volume of the cavity after resin filling through a compression operation member made of a shape memory alloy. This is what I did.

[Effect] In the above configuration, injection is made into the cavity.

The filled molten resin is compressed and molded by a preset compression amount due to the shape memory effect of the compression operation member.

[Example] Hereinafter, an example of the present invention will be described in detail using the drawings.

(First Example) FIGS. 1a and 1b show a first example of an injection mold l according to the present invention.
This shows an example, and FIG. 1a shows the process of filling (injecting) molten resin into the cavity 2.
FIG. 1 shows the process of compressing the molten resin filled in the cavity 2.

As shown in the figure, the injection mold l is composed of a fixed mold base part 4 which is internally equipped with a fixed side insert 3, a movable mold base part 6 which is internally equipped with a movable side insert 5, etc. The two mold base parts 4 and 6 have a mechanism that allows them to move toward and away from each other at a parting line (mold matching surface) 7.

A cavity 2 is formed between each molding surface 3a and 5a in both inserts 3.5.
There are sprues and runners (not shown) inside. The molten resin is filled through the gate 9. Each insert 3.5 has a fitting hole 10, 11 in each mold base part 4, 6.
The movable amount of each insert 3.5 is determined by the flange portion 3b formed at the end of each insert 3,5.
5b and the stopper surface parts 4a, 6 of each mold base part 4, 6
A is set to a predetermined stroke.

Concave portions 12, 13 of appropriate depth are formed on the side opposite to the molding surfaces 3a, 5a of each insert 3, 5, and compression operation springs 14, 15 are formed in each of the four portions 12, 13. are interpolated. Each of the compression springs 14 and 15 is made of a Xi-Ti or Gu-Al-Ni shape memory alloy having a transformation point at a temperature of about 100°C, for example. Each of the compression operation springs 14, 15 is in the direction of contraction in advance, that is.

It is deformed in a direction to expand the volume inside the cavity 2, and the direction is expanded depending on the resin temperature of the resin filled in the cavity 2 or the temperature control temperature during a heat cycle;
That is, a shape memory effect is imparted so that it deforms in the compression direction (the direction in which the volume inside the cavity 2 is reduced).

Reference numeral 16.17 indicates a template mounting plate, and reference numeral 18.19 indicates a spacer for the spring receiver of spring 14.15.

Next, the operation based on the above configuration will be explained.

The molten resin flows through sprues and runners (not shown) 8.
When the resin is injected into the cavity 2 through the gate 9, the injection pressure (filling pressure) of this molten resin causes the inserts 3 and 5 to move in a direction to expand the volume of the cavity 2.

Since the compression operation springs 14.15 are deformed in advance in the direction of contraction, they do not interfere with the movement of each insert 3.5.

Depending on the resin temperature of the molten resin filled in the cavity 2,
The temperature of each insert 3 and 5 increases. As the temperature of each insert 3.5 increases, the temperature of each compression operation spring 14, 15 made of a shape memory alloy also increases, and each compression operation spring 14,
When the temperature of 15 reaches a transformation point (for example, 100° C.), each compression operation spring 14, 15 deforms (restores) in the direction of expansion due to its shape memory effect. Due to the expansion, the resin in the cavity 2 is compressed and molded into a molded product having a desired shape.

Once the molded product has cooled, the mold can be opened and the molded product taken out.

As described above, according to this embodiment, a resin molded product can be injection compression molded with an extremely simple configuration, and costs can be significantly reduced. Furthermore, since the volume inside the cavity 2 is expanded when filling with the molten resin and then compressed and molded, a molded product with excellent transferability can be molded.

(Second Embodiment) Fig. 2 shows a second embodiment of the present invention.The features of this embodiment are that each mold mounting plate 16.1 on the fixed side and the movable side
7 near each input f3 and 5.

This is because a temperature control tube (or heater) 20 is provided. For other configurations, see Figure 1a.

Since it is the same as that shown in b, its explanation will be omitted.

According to the configuration L, the temperature of the mold l is heat cycled via the temperature control tube (or heater) 20, and the time for transformation of each compression operation spring 14, 15 made of a shape memory alloy can be controlled. can. As a result, it is possible to control the timing of the compression operation after resin injection, and in addition to the functions and effects of the first embodiment, it is possible to perform compression molding with higher precision.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention.The feature of this embodiment is that a recess 30 is formed on the outer periphery of the insert 5, and a recess 30 is formed inside the recess 30. This is because a bias spring 31 having a restoring force smaller than that of the spring 15 is elastically loaded.

The bias spring 31 is connected to the flange portion 5b of the insert 5 and the recessed portion 3.
The bullet is loaded between the end face 30a of 0 and the end face 30a of 0. The rest of the configuration is the same as in the second embodiment, so the same members are given the same reference numerals and their explanations will be omitted.

Next, the operation based on the above configuration will be explained with reference to FIG. 4.

When the compression operation spring 15 is below the transformation temperature, the spring 1
5 is in a contracted state, and the insert 5 is moved in a direction to expand the volume inside the cavity 2 by the action of the bias spring 31. In this state, the molten resin is injected into the cavity 2, and immediately after filling is completed, the temperature of the mold 1 is controlled via the A tube (or heater) 20 so that the temperature of the spring 15 becomes higher than the transformation temperature. control. At this time, the spring 15 is expanded and deformed by a pressing force exceeding that of the bias spring 31 due to the shape memory effect, and the insert 5 is suppressed and moved in a direction in which the volume inside the cavity 2 is reduced.

Thereby, the resin in the cavity 2 is compression molded.

When the molded product is cooled and solidified, the mold is opened and the molded product is taken out. At this time, when the temperature of the mold 1 decreases and the spring 15 becomes below the transformation temperature, the spring 15 contracts, so the insert 5 Due to the action of the bias spring 31, the cavity 2 is moved in a direction in which the volume within the cavity 2 is expanded. By repeating such operations, molded products can be molded one after another.

Also in the above configuration, the first. Similar effect to the second embodiment,
It can be effective.

(Fourth Embodiment) FIG. 5 shows a fourth embodiment of the present invention. The feature of this embodiment is that the springs 14 and 15 for compression operation in the first to third embodiments are replaced with It is constructed using compression operation members 40 and 41 formed in a U-shape. The compression operation members 40° and 41 are made of shape memory alloy,
A shape memory effect is imparted so that the U-shaped opening becomes narrow below the transformation temperature, and deforms in a direction in which the opening becomes enlarged below the transformation temperature.

The rest of the structure is the same as that shown in FIGS. 1a and 1b, so the same members are given the same reference numerals and their explanations will be omitted.

In the case of L constituent acid, the compression operation member 40 having the shape of
．． 41 is the compression operation spring 14, 1 in FIGS. 1a and 1b.
Same effect as 5! Since it has a Pt function, it can produce the same functions and effects as the first embodiment.

(Fifth Embodiment) FIG. 6 shows a fifth embodiment of the present invention. The feature of this embodiment is that the compression operation members 50 and 51 formed in an I shape (column shape) are used instead of the compression operation springs 14 and 15 in the first to third embodiments. The compression operation members 50 and 51 are made of a shape memory alloy, and are limited in the axial direction (in the vertical direction in the figure) below the transformation temperature, and become elongated in the axial direction when the temperature exceeds the transformation temperature. It has a shape memory effect. Since the other configurations are the same as those shown in FIGS. 1a and 1b, the same members are designated by the same reference numerals and their explanations will be omitted.

In L structure acid, a ■-shaped compression operation member 50.5
1 has the same function and function as the compression operation springs 14 and 15 in FIGS.

In each of the above embodiments, the springs 14 and 15 and the members 40 and 41° 50.51 made of shape memory alloy are installed inside each insert 3.5 of the fixed mold base part 4 and the movable mold base part 6. Although the example shown in FIG.
41, 50° 51 is the fixed mold base part 4. It goes without saying that the movable mold base portion 6 may be internally installed on either side of the mold base portion 6.

[Effects of the Invention] As described above, according to the present invention, a molded article with good transferability can be molded using an extremely simple and low-cost mold.

[Brief explanation of the drawing]

1a and b are cross-sectional explanatory views showing a first embodiment of a mold according to the present invention; FIG. 2 is a cross-sectional explanatory view showing a second example of a mold according to the present invention; FIG. FIG. 1 is an explanatory cross-sectional view showing a third embodiment of the mold according to the present invention. FIG. 4 is an explanatory diagram showing the relationship between mold temperature and cavity volume in FIG. 3, and FIGS.
It is a cross-sectional explanatory view showing a fifth example. 2... Cavity 3.5... Inserts 3a, 5a... Molding surface 14.15... Spring for compression operation 20... Temperature control tube (or heater) 31... Bias spring 40 .41,50.51...Patent applicant for compression operation member Olympus Optical Industry Co., Ltd. Agent on patent attorney
Kai Ryo Takeshi bb 1975
tja Figure 3 Memo 5a □77 Procedural amendment (voluntary) June 9, 1988 t, = 3 indications 1988 Patent application No. 309745 2, title of invention Injection mold 3, Relationship with the weight of the person making the amendment Patent applicant address 2-43 Hatagaya, Shibuya-ku, Tokyo Second name (037) Olympus Optical Industry Co., Ltd. Representative Shimoyamashikibe 4, Agent Name (8942) Patent attorney Takeshi Shinara 5, Date of amendment order 6, Subject of amendment'-I 1. ! No. 7. Contents of the amendment (1) "Fill (inject)" written in page 4, line 15 to line 16 of page 4 of the specification is amended to read "filled (injected)." (“Compress” written on page 4, line 17 of the specification)
is corrected as "compressed". (3) Written on page 6, line 5 of the specification:
” or compressed using the injection pressure of the molten resin (the injection pressure is sufficiently high compared to the holding pressure, etc.)
00 kg/cm2 or more). (4) "Deformed" written on page 6, line 19 of the specifications should be replaced with "deformed or compressed using the injection pressure of the molten resin (injection pressure is lower than holding pressure etc. Please set it so that it is sufficiently high (more than 500 kg/cm2).''

Claims (2)

[Claims] (1) Fixed side mold base part or/and movable side mold base
A movable insert having a molding surface is provided on I so as to be movable in the direction of expanding or contracting the internal volume of the cavity, and the movable insert is moved by a preset amount of movement via a compression operation member made of a shape memory alloy. 1. A mold for injection molding, characterized in that the mold is configured such that only the mold can be pressed and moved in a direction to reduce the internal volume of the cavity after being filled with resin. (2) The injection mold according to claim 1, wherein a temperature control tube or a heater is provided near the compression operation member.