JP2001341165A - Mold for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for injection molding capable of being manufactured in a small size at a low cost by incorporating a sufficient strength even without providing a shallow hole even when a stock having a low strength or large thermal expansion coefficient than that of a steel such as a non-ferrous metal, photo (thermo)setting resin or the like as a stock for an insert, a wide selecting range of the insert material, doing away with a decrease in a dimensional accuracy due to a thermal expansion of the insert and small manhour or short period of working a mold plate. SOLUTION: The mold for injection molding comprises a retainer plate 11, a movable retainer plate 21 and an insert 3 to be mounted on a surface of at least one mold plate of the plates 11 and 21 in such a manner that a sectional profile of the insert 3 cut in a direction perpendicular to a movable direction of the mold is formed in a concentrically circular or doughnut state, an end of the insert 3 to an opposite side to the cavity surface C is contacted with the surfaces of the plates 11 and 21, cutouts 33 and 34 are provided on outer peripheral surfaces of the cavity surface C side of the insert 3, and supported to cover the cutouts 33 and 34 with the insert support ring 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection-molding die having a nest mounted thereon.

[0002]

2. Description of the Related Art Conventionally, as a mold for injection molding to which an insert is mounted, a fixed mold plate, a movable mold plate, a fixed mold plate and a movable mold plate (hereinafter, collectively referred to as both). A pocket that is provided so as to be deeply engraved on the mold surface of the movable mold plate. Insert the nest into the hole,
It was common to attach the movable mold plate to the movable mold plate with bolts from the back side opposite to the molding surface of the movable mold plate, or to use a slide core.

[0003] However, in such a mold, when the insert is damaged, it is not easy to repair or replace the insert.

In view of the above, there has been proposed a mold in which an overhanging portion which comes into contact with a parting surface is provided around the base of the nest, and the overhanging portion is attached to the movable side mold plate from the molding surface side of the movable side mold plate. (Japanese Utility Model Laid-Open No. 4-137816).

However, in such a conventional injection mold, it takes much time and labor to engrave deep and elaborate pocket holes in the mold surface of the mold plate. There is a problem that the adjustment man-hour for fitting the child is large, and the pocket hole needs to be thickened on the mold surface because the pocket hole is deeply carved into the mold surface. .

[0006] The material used for the injection mold is usually a steel material. However, in the case of using an insert, a non-ferrous metal, a light (heat) curable resin, etc., which are more excellent in workability than the steel material. It is preferable to use a raw material in terms of processing cost. However, these non-ferrous metals and light (heat) curable resins are generally lower in strength or have a higher coefficient of thermal expansion than steel, and when used as inserts, they are damaged or molded products due to expansion of inserts. In some cases, the dimensional accuracy was reduced, and mold clamping failure occurred.

Therefore, the present inventors have solved the above problem.
The cylindrical insert is fitted into a shallow hole provided in the template, and the side peripheral surface protruding from the shallow hole is supported by a cylindrical insert support ring, thereby providing a stronger strength than steel. Injection molds that can be used even for materials having a low thermal expansion coefficient or a high thermal expansion coefficient have been proposed (Japanese Patent Application No. 11-365).
No. 125).

FIGS. 3A and 3B show an example of the injection molding mold proposed above, wherein FIG. 3A is a cross-sectional view thereof, and FIG. 3B is a state in which the fixed mold is provided with an insert. It is the top view seen from the cavity side. As shown in FIG. 3, the injection molding die includes a fixed mold plate 91, a movable mold plate 92, and an insert 9 mounted on the mold surfaces of the fixed mold plate 91 and the movable mold plate 92.
3 and 93, and is an injection molding die in which a cavity 9C having an inner surface shape corresponding to the outer surface shape of a molded product to be molded at the time of mold clamping is formed. The inserts 93, 93 are formed in a columnar shape, and the ends of the inserts 93, 93 on the side opposite to the cavity 9C surface are provided on the mold surfaces of the mold plates 91, 92. The holes 94, 94 are fitted. The side peripheral surfaces 931, 931 of the inserts 93, 93 projecting from the shallow holes 94, 94 are formed on the side peripheral surfaces 93, 93.
1, a support ring 95 having an inner peripheral surface in close contact with 931;
95. The support rings 95, 9
5 is made of steel material and is fixed to the mold surfaces of the mold plates 91 and 92, has the effect of reinforcing the inserts 93 and 93 to compensate for the lack of strength and to suppress thermal expansion. Is what it is. And the nests 93, 93
4 and 94 are screwed together with an insert fixing screw 932.
In FIG. 3B, reference numeral 951 denotes a fixing screw for fixing the support rings 95, 95 to the fixed-side template 91.

[0009] With the above-described injection molding die, the material forming the insert is made of a material having a lower strength or a larger thermal expansion coefficient than steel. This is also designed to sufficiently withstand use as a mold.

[0010]

However, even with the mold having the above structure, the number of steps for machining a shallow hole is large, and
In order to compensate for the decrease in strength due to the provision of the shallow hole, the entire mold plate is thickened, and the size of the mold is increased to increase the cost.

[0011] The present invention solves the above-mentioned problems, and as a material for nesting, a material having a lower strength or a larger coefficient of thermal expansion as compared with steel, such as a non-ferrous metal or a light (heat) curable resin. Even when using, it has sufficient strength without providing shallow holes, the selection range of nesting material is wide, the decrease in dimensional accuracy due to thermal expansion of nesting can be eliminated, and the man-hours for processing template etc. It is an object of the present invention to provide an injection molding die which can be manufactured in a small size and at a low cost.

[0012]

SUMMARY OF THE INVENTION An injection molding die according to the present invention comprises a fixed mold plate, a movable mold plate, and a mold surface of at least one of the fixed mold plate and the movable mold plate. With a nest to be mounted, the fixed side template and the movable side template are each made of a steel material, and the nest is made of a material having a lower strength or a larger coefficient of thermal expansion than this steel material, An injection molding die in which a cavity having an inner surface shape corresponding to the outer surface shape of a molded product to be molded at the time of mold clamping is formed, and the mold plate on which the nest is mounted is formed in a flat plate shape. The cross-sectional shape when the scribe is cut in a direction orthogonal to the movable direction of the mold has a concentric or donut shape, and the end of the nest that is opposite to the cavity surface is formed on the mold surface of the mold plate. Abutting, the side peripheral surface of the nest has an inner peripheral surface that is in close contact with the side peripheral surface; One end thereof is supported by the insert support ring consisting of a fixed cylindrical steel material surface, notches are provided on the outer peripheral surface of the cavity surface of 該入Ko,
The notch is supported so as to be covered by the insert support ring.

According to a second aspect of the present invention, when the mold is clamped, the nests are brought into contact with each other or the nest and the mold plate. Is preferably slightly higher than the surface of the nesting support ring on the parting line side.

If the step between the abutting surface of the insert and the surface of the insert support ring on the parting line side is too low, the insert support rings bear the mold clamping force, so that burrs occur during molding. When the height is too high, the insert tends to buckle, so the thickness is preferably 0.2 to 0.4 mm, more preferably 0.2 to 0.3 mm.

In the present invention, the insert is made of a material having a lower strength or a higher thermal expansion coefficient than the steel material forming the fixed mold plate, the movable mold plate and the insert support ring.

As the steel material forming the fixed-side mold plate, the movable-side mold plate, and the insert support ring, steel materials used as ordinary mold materials can be used, and carbon steel such as S50C, SUS304,
Examples include stainless steel such as SUS316 and high corrosion resistant steel such as Hastelloy.

The fact that the strength of the nested material is lower than that of steel is
It means that at least one of compressive strength, tensile strength, bending strength, or elastic modulus is low. It is needless to say that the strength of the nested material needs to be equal to or more than a predetermined value enough to withstand destruction during injection molding.

The compressive strength of the nested material is 100 to 50 when the compressive strength of the steel material of the fixed mold plate, the movable mold plate and the nest support ring is 500 MPa.
0 MPa is preferred. The compressive strength of the nested material is 100M
If it is smaller than Pa, molding with high resin pressure becomes difficult,
It is necessary to mold at low pressure. Here, the above-mentioned compressive strength refers to a value measured according to JIS K 6911 “Test method for thermosetting plastics”.

The tensile strength of the nested material is 60 to 500 when the tensile strength of the steel material of the fixed mold plate, the movable mold plate and the nest support ring is 500 MPa.
MPa is preferred. Tensile strength of nested material is 60MPa
If it is smaller, molding with high resin pressure becomes difficult, and molding with low pressure is required. Here, the above tensile strength refers to a value measured according to JIS Z 2241 “Metallic material tensile test method”.

It goes without saying that the thermal expansion coefficient of the nested material must be less than a predetermined value for maintaining the accuracy of the molded product. The thermal expansion coefficient of the nested material is
When the thermal expansion coefficient of the steel material as the material of the fixed mold plate, the movable mold plate and the nest support ring is 11 × 10 ⁻⁶ / ° C., 1
It is preferably from 1 to 90 × 10 ⁻⁶ / ° C. Thermal expansion coefficient is 90 ×
If it is higher than 10 ^-6 / ° C, the precision of the molded product cannot be maintained. Here, the above-mentioned coefficient of thermal expansion is based on JIS
R 3102 "Test method for average thermal expansion coefficient of glass"
Refers to the value measured according to

Examples of such a material for nesting include non-ferrous metals such as aluminum-based alloys, copper-based alloys, and zinc-based alloys, and thermo (photo) curable resins such as epoxy.

In the present invention, the insert has a concentric or donut-shaped cross section when cut in a direction perpendicular to the movable direction of the mold. This is because the internal pressure such as the resin pressure applied to the insert can be equally shared and supported by the insert support ring.

The end of the insert opposite to the cavity surface is in contact with the mold surface of the mold plate, and the side peripheral surface of the insert has an inner peripheral surface closely contacting the side peripheral surface. A notch portion is provided on an outer peripheral surface of the mold plate on the cavity surface side, the end portion being supported by a tubular steel support member made of a cylindrical steel material having one end fixed to the mold surface; The part is supported so as to be covered by the telescopic support ring.

(Function) In the injection molding die of the present invention, the stationary mold plate and the movable mold plate are each made of steel, and the insert has lower strength or a thermal expansion coefficient than this steel. Is made of a large material, the selection range of the nested material is expanded, and it is possible to use a low-cost and easy-to-process material.
It can be manufactured at low cost.

The cross section of the insert when cut in a direction perpendicular to the movable direction of the mold is formed in a concentric or donut shape, and the end of the insert opposite to the cavity surface is formed in the mold. Since it is in contact with the mold surface of the plate, there is no need for a hole to fit the end of the insert, so the process of carving a hole in the mold surface of the template or fitting with the end of the insert The number of adjustment steps can be greatly reduced, and the thickness of the template can be reduced, so that the size of the mold can be reduced.

[0026] Further, it has an inner peripheral surface that is in close contact with the side peripheral surface of the nest, and is supported by a cylindrical nest support ring having one end fixed to the mold surface of the mold plate. A notch is provided on the outer peripheral surface of the nest on the cavity surface side,
Since the notch portion is supported so as to be covered by the insert support ring, it is possible to suppress the compression failure due to the resin pressure of the insert during injection molding, the fall of the end face surrounding the cavity, and the thermal expansion. Thus, it is possible to form a molded product having excellent outer diameter dimensional accuracy and appearance.

In the injection molding die of the present invention, when the mold is clamped, the inserts or the insert and the mold plate are brought into contact with each other, and the contact surface of the insert is inserted. If it protrudes slightly from the parting line side of the support ring,
Since the nested members bear the mold clamping force, or between the nested and template,
Burrs are less likely to occur during molding.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of an injection molding die according to the present invention, and FIG.
FIG. 2B is a plan view of the fixed mold with the nest inserted, as viewed from the cavity side. In FIG. 1, reference numeral 1 denotes a fixed mold, 11 denotes a fixed mold, 2 denotes a movable mold, 21 denotes a movable mold plate, 3 denotes an insert, 4 denotes an insert support ring, and C denotes a cavity.

The injection mold of the present invention comprises a fixed mold 1, a movable mold 2, an insert 3, and an insert support ring 4. The fixed mold 1 is a fixed mold plate 11. , A fixed-side mounting plate 12 and a sprue bush 13, in which a nozzle touch portion 14, which is a passage for injected resin, and a sprue 15 are provided. On the other hand, the movable mold 2 includes a movable mold plate 21, a protruding plate 22,
It comprises a spacer block 23 and a movable-side mounting plate 24.

Further, the insert 3 comprises a fixed insert 31 mounted on the mold surface of the fixed mold plate 11 and a movable insert 32 mounted on the mold surface of the movable mold plate 21. The nest support ring 4 includes a fixed nest support ring 41 that supports the fixed nest 31 and a movable nest support ring 42 that supports the movable nest 32.

The fixed mold plate 12, the movable mold plate 21, and the insert support ring 4 are made of steel (S50C, compressive strength: 600 MPa, tensile strength: 600 MPa, tensile elastic modulus 210 GPa, thermal expansion coefficient: 11 ×). ^10-6 / ° C.), and the insert 3 is made of an epoxy-based photocurable resin containing glass beads (manufactured by D-MEC, product number “SCR802”), compressive strength: 140 MPa, tensile strength: 80 MPa, tensile modulus of elasticity 7 GPa, heat Expansion coefficient: 86 × 10 ⁻⁶ / ° C.).

The fixed-side mold plate 11 and the movable-side mold plate 21 are each formed in a flat plate shape. And nesting 3, and
The nest support ring 4 forms a cavity C having an inner surface shape corresponding to the outer surface shape of a molded product to be molded at the time of mold clamping.

The fixed side mold plate 11 is attached to the fixed side mounting plate 12
A surface opposite to the mold surface is fixed, and a through hole is provided at a substantially central portion thereof, and a through hole provided at a substantially central portion of the fixed side mounting plate 12 is inserted into the through hole. Is inserted through the sprue bush 15.

The nest 3 has a concentric cross section centered on the sprue 15 when cut in a direction orthogonal to the movable direction of the mold. The opposite end is brought into contact with the mold surface of the template 11, 21, and the template 1 is fixed by the positioning pins 51, 52.
It is fixed at a predetermined position with respect to 1, 21.

The positioning pins 51 and 52 are mounted on the template 1.
1, 21 and one of the pin holes provided in the insert 3 is embedded and fixed.
When embedded and fixed in the pin holes provided in the mold plates 1 and 21 so as to protrude from the mold plates 11 and 21, the portions protruding from the mold plates 11 and 21 are fixed to the pins provided in the insert 3 during mold clamping. Inserted and fixed in the hole.

The pin holes provided in the insert 3 can be formed at the same time when the insert 3 is manufactured.
It is manufactured with an accuracy of about 0.01 mm. On the other hand, the template plates 11 and 21 are manufactured by NC processing with an accuracy of about ± 0.01 mm. Therefore, the positioning is performed with high accuracy without providing shallow holes in the template plates 11 and 21.

A side peripheral surface of the insert 3 is supported by an insert support ring 4. Notches 33 and 34 are provided on the outer peripheral surface of the insert 3 on the side of the cavity C, and the notches 33 and 34 are supported so as to be covered by the insert support ring 4.

The nest support ring 4 is made of a tubular steel material, has an inner peripheral surface that is in close contact with the side peripheral surface of the nest 3, and supports the nest 3. Then, on the mold surfaces of the mold plates 11 and 21,
One end thereof is fixed by nesting support ring fixing screws 61 and 62. The insert support ring 4 is provided with a flange so as to cover the cutouts 33 and 34 of the insert 3, and the insert 3 is fixed to the templates 11 and 21 while being pressed against the flange. . With such a configuration, a bolt hole for fixing the insert 3 to the template plates 11 and 21 becomes unnecessary, and the insert can be made compact.

In FIG. 1, reference numeral 16 denotes a guide pin, and reference numeral 25 denotes a protruding pin.

FIG. 2 is a sectional view showing an example of the injection molding die according to the second aspect of the present invention in an opened state.

As shown in FIG. 2, in the injection molding die of this embodiment, the end face surrounding the cavity surface of the fixed insert 31 is slightly smaller than the end face of the fixed insert support ring 41 on the parting line side. (0.2 to 0.25 mm) higher than that described with reference to FIG.

[0042]

As described above, the injection mold of the present invention has the above-mentioned structure, and therefore, as a material for nesting, compared to steel materials such as non-ferrous metals and light (heat) curable resins. Even if a material with a low or large thermal expansion coefficient is used, it has sufficient strength without providing shallow holes, the selection range of the nesting material is wide, and the dimensional accuracy due to the thermal expansion of the nest also decreases. It is possible to reduce the number of man-hours and time required for processing a template, and it is possible to manufacture a small product at low cost.

[Brief description of the drawings]

FIG. 1 shows an example of an injection mold according to the present invention, in which (a)
FIG. 2 is a cross-sectional view of the fixed mold, and FIG. 2B is a plan view of the fixed mold with a nest attached to the fixed mold as viewed from the cavity side.

FIG. 2 is a cross-sectional view of an example of the injection molding die according to the second embodiment of the present invention, showing a state in which the die is opened.

3A and 3B show an example of an injection mold proposed in Japanese Patent Application No. 11-365125; FIG. 3A is a cross-sectional view thereof, and FIG. FIG. 4 is a plan view of the child mounted state as viewed from the cavity side.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fixed mold 11 fixed mold 2 movable mold 21 movable mold plate 3 insert 31 fixed insert 32 movable insert 33, 34 cutout 41 fixed insert support ring 42 movable insert Child support ring C cavity

Claims (2)

[Claims] A fixed side template, a movable side template, and a nest mounted on a mold surface of at least one of the fixed side template and the movable side template; And the movable mold plate are each made of a steel material, and the insert is made of a material having a lower strength or a larger thermal expansion coefficient than this steel material, and corresponds to the outer surface shape of a molded product to be molded at the time of mold clamping. An injection molding mold in which a cavity having an inner surface shape is formed, and the mold plate on which the insert is mounted is formed in a flat plate shape,
The nest is formed in a concentric or donut shape in cross section when cut in a direction orthogonal to the movable direction of the mold,
The end of the nest opposite to the cavity surface is in contact with the mold surface of the mold plate, and the side peripheral surface of the nest has an inner peripheral surface closely contacting the side peripheral surface; One end of the plate is supported by a nesting support ring made of a tubular steel material having one end fixed thereto, and a notch is provided on the outer peripheral surface of the nest on the cavity surface side, and the notch is An injection molding die supported by the insert support ring so as to be covered. 2. When the mold is clamped, the nests are connected to each other or
2. The injection according to claim 1, wherein the insert and the template are brought into contact with each other, and the contact surface of the insert is slightly higher than the parting line side surface of the insert support ring. Mold for molding.