JP2003094440A - Method for manufacturing injection mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an optimum cooling circulating passage corresponding to the outer shape of a molded article in a mold. SOLUTION: The mold is molded on the basis of the three-dimensional data of a mold, which has the cooling medium circulating passage including a curved passage part along the wall surface for forming the cavity of the mold for molding the molded article, by an optical shaping method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an injection molding die capable of molding a die based on three-dimensional data.

[0002]

2. Description of the Related Art In an injection molding die, a cooling medium circulating passage for circulating a cooling medium for cooling the die to cool and solidify the molded article is formed inside as a cooling circuit. Water, oil or the like is used as the cooling medium.

Such a cooling medium circulation passage is, for example,
As shown in FIG. 7 and FIG. 8, it is provided around the cavity formed inside the fixed mold 2 and the movable mold 4, which are so-called insert pieces. Note that FIG. 8 shows the outer appearance of the moving die 4.

During mold clamping, the fixed mold 2 and the movable mold 4
Parting line where the opposite end faces of
The PL is formed between the fixed mold 2 and the movable mold 4.

The fixed mold 2 is formed with a concave portion into which a convex portion of a male movable mold 4 to be described later is inserted. A cavity is formed between the convex portion and the concave portion of the fixed mold 2. Cooling passages 6A, 6B, 6C, 6D, 6E and 6F are formed in the fixed side mold 2 around the inner wall surface forming a part of the outline of the cavity. Cooling passages 6A-6
Each F penetrates the inside in a straight line parallel to each other and in the same direction.

On the other hand, the movable die 4 is formed with a male convex portion 4CA corresponding to the outer shape of the obtained molded product. Cooling passages 8A, 8B, 8C, 8D, and 8E are formed in the inner portion of the outer surface of the convex portion 4CA forming the remaining portion of the contour of the cavity described above.

Cooling passages 8A, 8B, 8C, 8D, and 8E
Respectively intersect the cooling passages 6A to 6F in parallel with each other at a predetermined interval and at a predetermined angle.

Each of the cooling passages 8A to 8E is formed to include two linear passages that intersect at a predetermined angle. One end of the cooling passage 8A communicates with a linearly extending cooling passage 10A1 that intersects with the cooling passage 8A. The other end of the cooling passage 8A communicates with a cooling passage 10A2 orthogonal to it. One end of the cooling passage 8B communicates with the cooling passage 10A1. The other end of the cooling passage 8B communicates with a cooling passage 10B2 orthogonal to it. One end of the cooling passage 8C communicates with the cooling passage 10C1. The other end of the cooling passage 8C communicates with a linearly extending cooling passage 10C2 that intersects with the cooling passage 8C. One end of the cooling passage 8D communicates with the cooling passage 10C1. The other end of the cooling passage 8D communicates with the cooling passage 10D2. One end of the cooling passage 8E communicates with the cooling passage 10D1 and the other end of the cooling passage 8E communicates with the cooling passage 10D2.

In such a structure, in the mold clamping state as described above, for example, the cooling medium is supplied to each passage along the direction shown by the arrow in FIG. 4 will be cooled.

Further, in manufacturing such fixed side mold 2 and movable side mold 4, for example, as shown in FIG. 9, a plurality of steps are required. In FIG. 9, first, the machine work including rough finishing is performed on the material of the mold, and then the finish processing is performed on the six surfaces of the rough-finished rectangular parallelepiped material. Next, the cooling passages described above are formed by machining including drilling. Subsequently, the concave portion and the convex portion that form the above-mentioned cavity in the mold are formed by predetermined machining and electric discharge machining. Then, after the concave portion and the convex portion of the mold are respectively ground or polished and finished, the mold is assembled and adjusted in the injection molding apparatus.

Therefore, in the production of the mold, the cutting work by the machine tool is the center, so that the more complicated the product shape and the cooling circulation passage, the more difficult the work is. As a result, the manufacturing cost increases.

Therefore, in the manufacture of the mold, for example, as shown in Japanese Patent Publication No. 8-4854 and Japanese Patent Laid-Open No. 7-276507, the material of the mold is hardened or sintered based on the three-dimensional shape data. It has been proposed to manufacture a mold using an optical molding method in which a mold is formed while being laminated.

[0013]

However, in the mold fabrication using the above-mentioned proposed stereolithography, the cooling circulation passage is optimally formed along the surface shape of the portion forming the cavity in the mold. There is a risk that local heat accumulation may occur in the mold because it is formed linearly inside rather than in the mold. Therefore, in the obtained molded product,
Sinks or warpages may occur due to uneven temperature distribution during the cooling process.

In consideration of the above problems, the present invention is a method of manufacturing an injection molding die capable of molding a die based on three-dimensional data, and is an optimum cooling circulation corresponding to the outer shape of a molded product. It is an object of the present invention to provide a method for manufacturing an injection molding die capable of forming a passage.

[0015]

In order to achieve the above object, a method of manufacturing an injection molding die according to the present invention includes a curved passage portion along a wall surface forming a cavity of a die for molding a molded article. A step of forming three-dimensional data of a mold having a cooling medium circulation passage including the step of forming slice data representing each cross-sectional shape of the mold divided at predetermined intervals based on the three-dimensional data; and slice data And forming a mold by sequentially irradiating the material of the mold with the light beam on the basis of the scanning locus data.

[0016]

FIG. 2 shows a mold group of an injection molding apparatus equipped with a mold to which an example of a method for manufacturing an injection molding mold according to the present invention is applied.

In FIG. 2, the mold group is the fixed side support plate 2.
0 and the moving side support plate 28. The fixed side support plate 20 is fixed to a fixed side platen of an injection molding device (not shown). Further, the moving side support plate 28 is
It is fixed to the moving platen.

A fixed side mold 22 is fixed to the fixed side support plate 20. A mold 24, which is called an insert piece, is inserted and held in the concave portion at the center of the fixed-side mold 22. The female mold 24 has a portion inside which forms one side of the outer surface of the obtained molded product. Further, the inner wall of the mold 24 cooperates with a male mold 36 described later to form a cavity.

Further, a plurality of cooling medium passages 26A, 26B, 26C, and
26D, 26E, and 26F are provided in an arc shape facing the inner wall thereof at a predetermined angular interval. The cooling medium passages 26A to 26F linearly penetrate from the one end of the fixed mold 22 to the other end thereof. At both ends of the cooling medium passages 26A to 26F, joint portions 26J connected to a supply passage for supplying the cooling medium from the cooling medium supply source are provided.

A movable side die 32 is fixed to the movable side support plate 28 via support bases 28A and 28B. A male die 36 called an insert piece is inserted and held in the concave portion at the center of the moving side die 32.

Between the supports 28A and 28B, eject plates 30 and 31 are connected to the above-mentioned drive ram so as to be able to approach or separate from each other. The eject plate 30 is provided with ejection pins and the like (not shown). As a result, when the mold is opened, the movable side support plate 28 is separated from the fixed side support plate 20 along the direction indicated by the arrow in FIG.
When the eject plate 31 is separated from the eject plate 31, the ejected pin causes the molded product to be ejected.

As shown in FIG. 1, the mold 36 has portions 36A and 36D which form the other side of the outer surface of the resulting molded product.
And 36E on the base 36B. The trapezoidal portion 36D and the arc-shaped portion 36E are independently formed on the portion 36A.

An arc-shaped portion 36E inside the mold 36
The cooling medium passages 38A, 38B, 38C, 38E, and 38F are respectively provided at predetermined positions from the outer surface of the trapezoidal portion 36D so as to intersect the cooling medium passages 26A to 26F. Are formed inside at a distance of. The cooling medium passage 38A is formed inside along the outer surface of the portion 36A and the outer surface of the arc-shaped portion 36E. Further, the cooling medium passage 38A has a curved portion 38a corresponding to the outer surface of the arc-shaped portion 36E.

One end of the cooling medium passage 38A communicates with a cooling medium passage 34B formed in the base 36B. The other end of the cooling medium passage 38A has a base 36B.
Cooling medium passage 3 via communication passage 38H formed inside
It communicates with one end of 8B.

The cooling medium passages 38B and 38C are formed inside along the outer surface of the portion 36A and the outer surface of the arc-shaped portion 36E, respectively. Cooling medium passage 38B
And 38C respectively have curved portions 38b and 38w corresponding to the outer surface of the arcuate portion 36E. The other end of the cooling medium passage 38B communicates with the other end of the cooling medium passage 38C via a communication passage 38D. One end of the cooling medium passage 38C communicates with a cooling medium passage 34A formed substantially parallel to the cooling medium passage 34B.

The cooling medium passages 38E and 38F are formed inside along the outer surface of the portion 36A and the outer surface of the trapezoidal portion 36D, respectively.

The other ends of the cooling medium passages 38E and 38F communicate with each other through a communication passage 38G. Also,
One ends of the cooling medium passages 38E and 38F are respectively
The cooling medium passages 34D and 34C formed in the base 36B are communicated in parallel with each other.

At both ends of the cooling medium passages 34A, 34B, 34C, and 34D, joint portions 34J connected to the supply passages for supplying the cooling medium from the cooling medium supply source are provided.

Therefore, since the cooling medium passages 38A to 38F are optimally formed along the outer surfaces thereof, the intervals from the cooling medium passages 38A to 38F to the outer surfaces thereof are uniform, and as a result, the temperature distribution is uniform. Therefore, the mold 36 is uniformly cooled so that

In manufacturing such a mold 36, for example, a bronze-nickel alloy powder is used by a stereolithography method as described later.

First, as shown in FIG. 6, three-dimensional CAD data representing a contour of a model of a molded product to be molded is created by a CAD system using a predetermined CAD program (step S1). Next, the obtained 3D CAD
The data is converted into the STL format by the CAD system by the method of approximating the three-dimensional free-form surface with a set of triangular batches (step S2).

Subsequently, as shown in FIG. 4, the data SD converted into the STL format is supplied to the slice data forming unit 50 in the modeling apparatus. The slice data forming unit 50 cuts the data SD at equal predetermined intervals to form a slice data group SLD representing the contour of each cross section (step S3). The cutting is performed at predetermined equal intervals, for example, 50 to 100 μm, after the stacking direction is set according to how to place the model of the molded product.

Subsequently, the slice data group SLD is supplied to the scanning locus data forming unit 52 in the modeling apparatus. The scanning locus data forming unit 52 calculates the locus of the laser beam spot based on the slice data group SLD, the laser scanning speed, and the like. A data group SPD representing the calculated trajectory of the laser beam spot is supplied to the laser irradiation controller 54. The laser irradiation control unit 54 forms the control signal CD based on the data group SPD and supplies it to the optical system 58 in the modeling apparatus as shown in FIG.

FIG. 3 schematically shows a main part of the modeling apparatus.
In FIG. 3, the molding portion in which the mold is formed contains the metal powder M that is the material of the mold and a predetermined amount of the metal powder M.
And the optical system 58 for irradiating the metal powder M with the light beam from the carbon dioxide gas laser beam generator 60. There is.

The ascending / descending cylinder section CL is composed of a cylinder control section 56.
It is controlled based on the control signal CS from. The cylinder control unit 56 forms a control signal based on the signal representing a predetermined stroke based on the slice data group SLD from the laser irradiation control unit 54.

In modeling (step S4: see FIG. 6),
Based on the control signal CD, the optical system 58 irradiates the light beam LB so that the scanning loci become parallel to each other at a predetermined interval within a predetermined range, as shown in FIG. As a result, the metal powder is sintered by the scanning of the light beam LB based on each slice data, and the sintered layer TL1 is formed. At that time, the tank T is moved up and down by a predetermined amount CL
Thus, the metal powder is lowered and a predetermined amount of metal powder is replenished on the sintered layer.

Next, based on the control signal CD, the optical system 58 causes the scanning loci of the light beam LB to be parallel to each other at a predetermined interval within a predetermined range, as shown in FIG. 5 (a). Irradiate. As a result, as shown in FIG.
The sintered layer TL2 corresponding to the base 36B is formed and laminated on the sintered layer TL1. At this time, the cooling medium passage 34
Part 34A ', 34B', 34C ', and 34D' of the part corresponding to A, 34B, 34C, and 34D will be formed, respectively. Also, the communication passages 38G, 38D, 38
Part of the part corresponding to H, 38G ', 38D', 3
8H 'will be formed.

Subsequently, as shown in FIG. 5C, a sintered layer TL3 is formed on the sintered layer TL2 by the same method as described above.
Thereby, the cooling medium passages 34A, 34B, 34C, and 34D are formed, and the communication passages 38G, 38D, and 3D are formed.
8H will be formed.

Subsequently, as shown in FIG. 5D, the sintered layer TL4 is formed on the sintered layer TL3 by the same method as described above. Thereby, the part 36 of the part corresponding to the part 36A is
A'is formed. Further, the cooling medium passages 38A, 38
Part of portions corresponding to B, 38C, 38E and 38F, 38A ', 38B', 38C ', 38E' and 38
F'will be formed.

Subsequently, as shown in FIG. 5E, a sintered layer TL5 is further formed on the sintered layer TL4 by the same method as described above. As a result, the cooling medium passages 38A, 38B, 3
Curved portions are formed at portions 38A ', 38B', 38C ', 38E', and 38F 'of portions corresponding to 8C, 38E, and 38F, respectively. At that time, a part of the portions 36D 'and 36E' corresponding to the portions 36D and 36E will be formed.

Then, as shown in FIG. 5 (f), the sintered layer TL6 is formed on the sintered layer TL5 by the same method as described above. As a result, the portions 36D and 36E are formed and the cooling medium passages 38A, 38B, 38 are formed.
C, 38E and 38F will be formed inside.
Therefore, the modeling is completed. Although the description of the gate and the runner is omitted in the above description of the modeling, they will be formed at the same time.

As shown in FIG. 6, the molded die is subjected to a predetermined finishing process (step S5) and then a surface treatment in which a thermosetting epoxy resin or the like is infiltrated (step S6).
Is applied.

The surface-treated mold is assembled and adjusted on the stationary mold 32 (step S7).

Therefore, in manufacturing the mold, by using the stereolithography method, the cooling medium passage is automatically formed inside together with the mold manufacturing, and the cooling medium passage is curved along the curved shape of the mold. It will be easily formed to have parts.

Further, conventionally, the cooling passage, which is often machined by a drilling machine, a milling machine or the like, can often be machined only linearly due to the nature of the machine,
In addition, complicated work is required to provide an appropriate cooling circuit for a mold of a molded product having a complicated shape. As a result, there is a problem that the cost of the mold is increased and a large delivery time is spent.

However, by directly and automatically forming the cooling passage and the mold with the metal powder as in the above-mentioned example, the working of the cooling passage of the mold is significantly improved.

That is, without impairing the cooling performance of the mold,
There is an effect that a die can be manufactured easily and accurately at low cost.

In a resin molded product having a complicated shape and a three-dimensional free-form surface, an optimal cooling circuit having the cooling efficiency of each part in the mold increased equally is arranged in the mold, so that the local cooling occurs in the mold. Heat is prevented, and deterioration of processing accuracy due to sink marks and warpage is avoided. as a result,
A resin molded product with relatively high processing accuracy can be obtained.

Further, since sufficient cooling is performed in a relatively short period, the cooling time in a series of cycles can be set to be relatively short. As a result, it is possible to prevent problems such as an increase in cost of the resin molded product and a delay in delivery due to the extension of the molding cycle.

In the above example, it is needless to say that a mold may be manufactured by using an ultraviolet laser beam as a light beam for irradiation and using a heat-curable photocurable resin material as a material of the mold. Is.

[0051]

As is apparent from the above description, according to the method for manufacturing an injection molding die of the present invention, cooling including a curved passage portion along a wall surface forming a cavity of a die for molding a molded product. Since the molding of the mold is performed based on the three-dimensional data of the mold having the medium circulation passage, it is possible to form the optimum cooling circulation passage corresponding to the outer shape of the molded product in the die.

[Brief description of drawings]

FIG. 1 is a perspective view showing an appearance of a mold manufactured by an example of a method for manufacturing an injection molding mold according to the present invention.

FIG. 2 is a perspective view showing a main part of an injection molding die in which a mold molded by an example of a method for manufacturing an injection molding mold according to the present invention is mounted.

FIG. 3 is a diagram schematically showing a configuration of a main part of a modeling apparatus used in an example of a method for manufacturing an injection molding die according to the present invention.

FIG. 4 is a block diagram showing a control block provided in the modeling apparatus shown in FIG.

5 (a), (b), (c), (d), (e) and (f) respectively show a molding step in an example of a method for manufacturing an injection molding die according to the present invention. It is a perspective view.

FIG. 6 is a diagram showing each step in an example of a method for manufacturing an injection molding die according to the present invention.

FIG. 7 is a perspective view showing a cooling medium passage provided in a conventional mold.

8 is a perspective view showing one side of the mold shown in FIG. 7. FIG.

FIG. 9 is a diagram showing each step in a conventional manufacturing method.

[Explanation of symbols]

36 type 34A, 34B, 34C, 34D cooling medium passage 38A, 38B, 38C, 38E, 38F cooling medium passage

Claims (3)

[Claims] 1. A step of forming three-dimensional data of a mold having a circulation passage for a cooling medium including a curved passage portion along a wall surface forming a cavity of a mold for molding a molded article, and based on the three-dimensional data. A step of forming slice data representing each cross-sectional shape of the mold divided at predetermined intervals, a step of creating scanning trajectory data of a light beam based on the slice data, and the step of generating scanning trajectory data based on the scanning trajectory data. And a step of sequentially irradiating a material of the mold with a light beam to mold the mold, and a method of manufacturing an injection molding mold, comprising: 2. The method for manufacturing an injection molding die according to claim 1, wherein the material of the die is a metal powder for sintering or a photocurable resin material. 3. The method of manufacturing an injection molding die according to claim 1, wherein the molded product is molded from a resin material.