JP2004249328A - Die for metal injection-molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the development of burr, the increase of thickness, etc., by enhancing the rigidity of a die. <P>SOLUTION: A support block (16a) at the fixed side is disposed between an insert (9a) at the fixed side and a fitting plate (15a) at the fixed side, and the above supporting block (16a) at the fixed side is freely expanded/shrunk to a die clamping direction of the die (2). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mold for a metal injection molding machine, and in particular, to obtain a high-quality molded product by enhancing the rigidity of a mold used in metal injection molding of a magnesium alloy or a zinc alloy or a die casting method or the like. And a mold for a metal injection molding machine.
[0002]
[Prior art]
FIG. 3 shows a conventional metal injection molding machine and a metal mold. In FIG. 3, reference numeral 1 denotes a heater installed outside, 2 denotes a cylinder for melting and storing a raw material (not shown), and 3 denotes a screw for conveying and injecting the raw material. Reference numeral 5 denotes a mold, which includes a fixed mold 24 and a movable mold 25, and is heated by a heating device (not shown). 15a and 15b are mounting plates for mounting the fixed mold 24 and the movable mold 25 to the injection molding machine, 14 is a cavity serving as a product part, 9a and 9b are nests on the fixed and movable sides, and 8a and 8b are movable. This is a main type that incorporates and holds the side insert 9a and the fixed insert 9b. The fixed mold 24 incorporates a sprue 12 serving as a sprue of molten metal, a sprue bush 6 forming the sprue 12, and a runner 13 connecting the sprue 12 and the cavity 14. Reference numeral 11 denotes an ejector pin for ejecting and ejecting an injection-molded product, and reference numeral 10 denotes an ejector plate which is fixedly connected to the ejector pin 11 and protrudes in the direction of a fixed-side mold. A support block 16b is disposed between the main mold 8b of the movable mold 25 and the ejector plate 10, and suppresses deformation of the main mold 8b. The movable mold 25 incorporates a plug catcher bush 7 having a recess 20 for receiving solidified metal called a plug formed at the tip of the nozzle 4.
[0003]
Next, the operations of the metal injection molding machine and the mold will be described.
As shown in FIG. 3, the cylinder 2 is heated by the heater 1, and the raw material is charged into the cylinder 2 from the right side in the figure. As the screw 3 rotates and moves backward, the input raw material is conveyed to the front of the cylinder 2. The raw material is heated from the cylinder 2 to be in a molten state and stored in front of the screw 3. The movable mold 25 is moved, the cylinder 2 moves forward in a state where the mold is closed together with the fixed mold 24, and the mold is brought into contact with the nozzle 4 provided in front of the cylinder 2 and melted from this contact portion. After pressing at a high pressure so that the raw material does not leak, the screw 3 moves at a high speed, so that the raw material in a molten state passes through the sprue 12, which is a sprue, through the runner 13 through the nozzle 4 into the cavity 14. Will be filled. After the molten raw material filled in the cavity 14 is cooled and solidified in the mold, the movable mold 25 is moved to open the mold, and the ejector plate 10 is pushed to be connected to the ejector plate 10. The ejector pin 11 is released by projecting the sprue 12, the runner 13 and the product.
[0004]
[Patent Document 1]
JP-A-7-16719 [0005]
[Problems to be solved by the invention]
However, in the above-described conventional metal injection molding machine and mold, the molten raw material filled in the cavity at high temperature and high pressure has high energy, so that the die for receiving the molten raw material needs to have high strength. In recent years, since there is a great demand for thin and light products, the injection speed of a molding machine has been increased, and the mold temperature has been increased. For this reason, the mold has insufficient rigidity, and it is difficult to maintain the product shape, and there are problems such as an increase in the thickness of the molded product and generation of burrs.
[0006]
The present invention is to solve such a problem. To increase the rigidity of the mold, there is no need to make a large mold or to repeatedly adjust the fixed mold and movable mold, and the mold structure is compatible with products of any shape. By doing so, the purpose is to reduce burrs, increase in wall thickness, and the like.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention is arranged such that a fixed mold attached to the injection molding machine by a fixed-side mounting plate, and a fixed mold attached to the injection molding machine by a movable-side mounting plate, and are opposed to the fixed mold. A metal mold for a metal injection molding machine, comprising a fixed mold and a movable mold, wherein the fixed mold and the movable mold are clamped to form a cavity between the fixed nest and the movable nest.
A support block is arranged between the fixed side nest and the fixed side mounting plate,
It is characterized in that the support block is extendable and contractible in a mold clamping direction of the mold.
[0008]
A second aspect of the present invention is characterized in that the support block is provided with a heating means.
[0009]
The invention according to claim 3 of the present invention is characterized in that the heating means is an external heating device such as a band heater or an IH induction heating coil.
[0010]
The invention according to claim 4 of the present invention is characterized in that the support block is made of a material having a larger linear expansion coefficient than materials of other mold members such as a mounting plate, a main mold, and a nest. .
[0011]
The invention according to claim 5 of the present invention is characterized in that the support block uses aluminum, duralumin, stainless steel, or a copper alloy.
[0012]
The invention according to claim 6 of the present invention is characterized in that the support block can be set within a range of about 100 to 700 ° C. by the heating means.
[0013]
The invention according to claim 7 of the present invention is characterized in that a heating means is provided on the support block of the movable mold.
[0014]
In addition, the code | symbol in a parenthesis shows the corresponding member of embodiment mentioned later.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
A metal injection molding machine and a mold according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a metal injection molding machine and a mold according to the present invention, FIG. 2A is a sectional view showing an embodiment applied to a movable mold, and FIG. It is sectional drawing which shows a form. The configuration and operation other than the support block embodying the present invention and its heating means are the same as those of the prior art, and therefore detailed description is omitted.
[0016]
In the mold for a metal injection molding machine of the present embodiment, a fixed mold 24 attached to the fixed-side attachment plate 15a and a movable mold attached to the movable-side attachment plate 15b and arranged to face the fixed mold 24. The fixed mold 24 and the movable mold 25 are clamped to form the cavity 14 between the fixed nest 9a and the movable nest 9b. A fixed-side support block 16a is arranged between the fixed-side insert 9a and the fixed-side mounting plate 15a, so that the fixed-side support block 16a can expand and contract with respect to the direction of clamping the movable mold 25. Things.
[0017]
Specifically, a heating unit is provided in the fixed-side support block 16a. The heating means is a fixed external heating device 17a such as a band heater or an IH induction heating coil as shown in FIG. 2B. As shown in FIG. 2, a band heater 17 a as an external heating device and a thermocouple 18 a for controlling the band heater 17 a are arranged on each of the fixed-side support pins 16 a separately from the oil medium for heating the entire mold. The temperature is controlled by a temperature control device (not shown). The fixed-side support block 16a can be set in the range of about 100 to 700 ° C. by the external heating device 17a.
[0018]
Further, it is preferable that the fixed-side support block 16a be made of a material having a larger linear expansion coefficient than the material of the mounting plate 15a, the main mold 8a, and the insert 9a, which are other mold members. Specifically, the fixed-side support block 16a is made of SUS304 having a higher coefficient of thermal expansion than the fixed-side main die 8a, the nest 9a, and the SKD51 and S55C of the mounting plate 15a. In addition, it is preferable to use aluminum, duralumin, stainless steel, a copper alloy, or the like. The fixed-side support block 16a can determine the overall length of the fixed-side support block 16a by calculating the coefficient of thermal expansion from the following equation and inputting an arbitrary value to the temperature control device. Can be dealt with.
ΔL = α (t2−t1) × L
ΔL: Thermal expansion (mm)
L: Length before expansion (mm)
α: linear expansion coefficient t1: temperature before change (° C.) t2: temperature after change (° C.)
[0019]
As described above, the fixed mold has been described. However, the support block of the movable mold is usually arranged between the main mold and the mounting plate, and the support block acts on the nest through the main mold. is there. On the other hand, since the support block of the fixed mold is disposed between the nest and the mounting plate, and the support block directly acts on the nest, the effect is remarkably exhibited. Therefore, the same effect can be obtained if the support block of the movable mold is also disposed between the nest and the mounting plate as described below.
As shown in FIG. 2A, a heating means may be provided in the support block 16b of the movable mold 25.
As a heating means, as shown in FIG. 2A, a fixed-side external heating device 17b such as a band heater or an IH induction heating coil is used. As shown in FIG. 2A, each of the fixed-side support pins 16b is individually provided with a band heater 17b as an external heating device and a thermocouple 18b for controlling the same, separately from the oil medium for heating the entire mold. Are arranged, and the temperature is controlled by a temperature control device (not shown). The movable support block 16b can be set in the range of about 100 to 700 ° C. by the external heating device 17b.
[0020]
The movable support block 16b is preferably made of a material having a larger linear expansion coefficient than the material of the mounting plate 15b, the main mold 8b, and the nest 9b, which are other mold members. Specifically, the movable-side support block 16b is made of SUS304 having a higher coefficient of thermal expansion than the fixed main die 8b, the nest 9b, and the SKD51 and S55C of the mounting plate 15b.
[0021]
【Example】
The experiment was performed under the following conditions.
Model used: JLM220-MG machine Temperature conditions: cylinder temperature 600 ° C, mold temperature 180 ° C
Product thickness, etc .: average thickness 0.8mm
Support block size: φ50 × length 70mm
Heating condition: 350 ° C
As a result of the experiment, when the product protruding from the cavity 14 has a burr of 0.1 mm, when the length of the fixed-side support block 16a is 70 mm, the fixed-side support block 16a is set to 350 ° C. By heating, generation of burrs could be prevented.
[0022]
【The invention's effect】
As described above, according to the first and second aspects of the present invention, a product nest and a mounting plate for a fixed-side mold, which constitute a cavity serving as a fixed-side product part, in a fixed mold for injection molding. And the fixed-side support block is disposed between the fixed-side support block and the length of the fixed-side support block itself, so that the bending of the mold can be suppressed. As a result, it is not necessary to perform abutting adjustment of the mold as in the related art, and it is possible to prevent the occurrence of burrs and an increase in product thickness without increasing the size of the mold due to an increase in the rigidity of the mold. it can. Further, even if the product shape such as the product thickness or the projected area changes, the same support block can cope with the change, so that the design of the mold becomes easy.
In addition, since the rigidity of the mold can be increased in a pinpoint manner for each support block, a stable product state can be achieved in a short period of time, so that a transition to a mass production system can be quickly performed. . Further, since the mold maintenance interval during mass production can be lengthened, the downtime of the apparatus can be reduced, and the production efficiency is improved.
[0023]
According to the third aspect of the present invention, since the heating means is an external heating device such as a band heater or an IH induction heating coil, the temperature can be controlled efficiently.
[0024]
In the invention according to claims 4 and 5 of the present invention, the support block is made of a material having a larger linear expansion coefficient than materials of other mold members such as a mounting plate, a main mold, and a product nest. Since geralumin, stainless steel, copper alloy, or the like is used, adjustment by changing the length of the support block can be optimally performed.
[0025]
In the invention according to claim 6 of the present invention, the support block can be set within a range of about 100 to 700 ° C. by the heating means, so that adjustment by changing the length of the support block is optimized. Can do it.
[0026]
In the invention according to claim 7 of the present invention, since the heating means is provided in the support block of the movable mold, the support block can be controlled by both molds, so that the product shape is complicated. In such a case, control can be performed more suitably.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram showing a metal injection molding machine and a mold embodying the present invention.
2A is a cross-sectional configuration diagram showing an embodiment applied to a movable die, and FIG. 2B is a cross-sectional configuration diagram showing an embodiment applied to a fixed die.
FIG. 3 is a sectional view showing the structure of a conventional metal injection molding machine and a metal mold.
[Explanation of symbols]
5 Mold 8a Fixed-side main mold 8b Movable-side main mold 9a Fixed-side nest 9b Movable-side nest 14 Cavity 15a Fixed-side mounting plate 15b Movable-side mounting plate 16a Fixed-side support block 16b Movable-side support block 17 External heating device 24 Fixed metal Mold 25 Movable mold

Claims (7)

A fixed mold (24) attached to the injection molding machine by the fixed-side mounting plate (15a), and attached to the injection molding machine by the movable-side mounting plate (15b), and arranged to face the fixed mold (24). A fixed mold (24) and a movable mold (25) are clamped to form a cavity (14) between a fixed insert (9a) and a movable insert (9b). ) To form a metal injection molding machine mold,
A fixed-side support block (16a) is arranged between the fixed-side insert (9a) and the fixed-side mounting plate (15a),
A mold for a metal injection molding machine, characterized in that the fixed-side support block (16a) is extendable and contractable in the direction of clamping the mold (5). The mold for a metal injection molding machine according to claim 1, wherein a heating means is provided on the fixed-side support block (16a). The mold for a metal injection molding machine according to claim 2, wherein the heating means is an external heating device (17a) such as a band heater or an IH induction heating coil. The fixed-side support block (16a) has a larger coefficient of linear expansion than materials such as the mounting plate (15a), the main mold (8a), and the nest (9a), which are members constituting another fixed mold (24). The mold for a metal injection molding machine according to any one of claims 1 to 3, wherein the mold is made of a material. The mold for a metal injection molding machine according to any one of claims 1 to 4, wherein the fixed-side support block (16a) uses aluminum, duralumin, stainless steel, or a copper alloy. 6. The metal injection molding machine according to claim 1, wherein the fixed side support block (16a) can be set in a range of about 100 to 700 [deg.] C. by the heating means. Mold. A movable-side support block (16b) is arranged between the movable-side insert (9b) and the movable-side mounting plate (15b),
The mold for a metal injection molding machine according to any one of claims 1 to 6, wherein a heating means is provided on the movable support block (16b).

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