JP2002113749A - Mold for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold which can be used for an impeller whose blades are overlapped in the mold for injection molding for molding a wax model of the impeller manufactured by means of a lost wax precise casting process. SOLUTION: The mold for injection molding characterized by providing a fixed side mold and a movable mold which can be opened and closed in the axial direction of a product and slide molds which are respectively arranged between adjoining blades and form blade cavities of the impeller by a shape being mutually annularly arranged when the mold is clamped and the slide molds being freely movable in the radial direction and being rotatable to the axial line of the radial direction and having a rotating and retreating means when the mold is opened and molding the wax model by the slide molds, the fixed side mold and the movable side mold, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold structure for injection molding for forming a wax model of an impeller manufactured by a lost wax precision casting method, and more particularly to a mold model for releasing a wax model of an impeller from a mold. For an easy structure. The impeller referred to here is a general term for an impeller having a large number of radially curved blade surfaces used in a supercharger or the like.

[0002]

2. Description of the Related Art An exhaust turbine of a supercharger (turbocharger) of an automobile internal combustion engine has a shape in which adjacent blades project radially and spirally with respect to a product axis. However, for the mold part that forms between the blades,
Conventionally, wax models are taken out by various structures. For example, Japanese Patent Application Laid-Open No. 59-232810 proposes a method for manufacturing a wax model integrated by separating and assembling blade cavities along a radial guide. This proposal is excellent as a wax model manufacturing mold structure having high accuracy and mass productivity.

On the other hand, impellers used in other fields,
For example, a turbocharger for a marine internal combustion engine or an impeller for a small gas turbine has a large number of blades protruding from a boss portion in order to obtain a larger air flow, and has a large blade surface area to increase the blade area. -The angle of installation of the blade surface has become more gradual, from the hub side of the blade (the base of the blade) to the shroud side of the blade (the outer periphery of the blade). There is a lot of overlap in the direction of the rotation axis, that is, there is a lot of overlap when projected in the direction of the rotation axis.

[0004] Such an impeller cannot be formed with the above-mentioned mold structure to form an overwrap portion of the blade. One method is to separately injection-mold the boss portion and the blade portion, and then assemble and integrate them together.
Specifically, this method uses a wax assembling jig to mold the wax model molded body of the boss portion and the wax model molded body of the blade portion, and bond and integrate the blades one by one. It becomes. Another method is to assemble the metal cores that form the gap between the blades one by one into the movable mold, close the fixed mold and perform injection molding, then open the fixed mold and open the movable mold. This is a method in which the metal cores are removed one by one from a mold and a wax model is taken out.

Further, the intake side impeller of the supercharger of the internal combustion engine for an automobile has many overwraps, long wings and short wings, and has a large number of blades, similarly to the above-mentioned impeller. , More complex shapes. Since such an impeller cannot be injection-molded as a single molded wax model, a master model of the impeller alone is manufactured, and the master model is used as a silicon model.
A method has been adopted in which a rubber mold is made by flowing and solidifying rubber, and a silicone rubber is injected into the rubber mold to form a rubber molded body as a model.

[0006]

As described above, in a mold for injection-molding a wax model of an impeller in which each blade overlaps, a method of bonding and bonding the previously molded wax models to each other requires a lot of man-hours and production. In addition to the poor efficiency, there is a problem that it is not easy to secure the joining accuracy between the boss portion and the blade portion. Also, when using a metal core, it takes a lot of time to open and close the mold and remove the wax model, resulting in poor production efficiency. Therefore, it is not easy to secure the combination accuracy because one metal core is used, and there is also a problem that a step, that is, a parting line occurs in the wax model because the blade surface is not integrated. Regarding the method of using a rubber mold, it takes a lot of man-hours to make one rubber molded body from a rubber mold, and a large number of rubber molds must be manufactured in accordance with the production volume. In addition, there is a problem that it is not easy to secure dimensional accuracy because the rubber molded body is easily deformed. In any case, when an impeller whose blade surfaces overlap with each other is manufactured by the lost wax precision casting method, there is a serious problem in mass-production using a uniform wax model. An object of the present invention is to solve the operating method of a movable slide mold, and to mold a single wax model for an impeller manufactured by a lost wax precision casting method at a uniform and high production efficiency. Is to provide a structure.

[0007]

SUMMARY OF THE INVENTION The present inventor has studied the problem of the method of operating a movable slide mold, and has studied CAD / CA.
By searching for the undercut direction of the blade surface of the impeller that overlaps in the direction of the rotation axis with the three-dimensional model using M, the undercut processing is performed in addition to the radial movement with respect to the product axis of the slide mold. The present inventors have found that it is possible to remove the slide mold by applying a rotating operation along a curved surface corresponding to the blade shape, and arrived at the present invention.

That is, the present invention relates to an injection molding mold for molding a wax model of an impeller manufactured by a lost wax precision casting method having a plurality of blades radially arranged with respect to a product axis. It has a slide mold that is disposed between the fixed mold and the movable mold that can be opened and closed, and the adjacent blades, and forms a blade cavity of the impeller by a shape that is arranged in a ring shape when the mold is compressed. The slide mold is movable in a radial direction, is rotatable about the radial axis, and has a retreat means for rotating when the mold is opened. The slide mold, the fixed mold, and the movable mold A mold for injection molding, characterized in that a wax model is formed by a mold. Preferably, the slide dies are integrated in an interlocking structure, and each of the slide dies preferably rotates and recedes. The rotating and retreating means includes a slide mold having a curved slide surface, and a guide that fits and slides on the slide surface, and the slide mold moves from the mold clamping position to the guide with respect to the product shaft. A metal mold for injection molding characterized by rotating along a curved surface of a slide surface while retreating radially along the same. Further, the rotating means slides along a groove provided obliquely with respect to a radial axis on a guide on which the protrusions provided on the curved slide surface of the slide mold are fitted and slid. This is a mold for injection molding characterized by being set according to the structure to be formed.

[0009]

As described above, an important feature of the present invention is that a three-dimensional CAD / CAM model is used to search for an undercut direction of a blade surface of an impeller overlapping in the direction of a rotation axis, and an undercut is performed. An operation method of a slide mold that enables processing, that is, an operation method in which the slide mold simultaneously performs a radial slide and a rotation operation with respect to the slide axis, that is, the slide mold rotates and retracts when the mold is opened. It has been found that undercut processing is possible. In the present invention, the above operation is realized by using a slide plate having a curved surface portion disposed on a fixed mold.
It is not limited to this.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments and drawings. Note that the present invention is not limited to the following examples, and various forms can be applied depending on products, particularly blade shapes. FIG. 1 is a front view showing the entire wax model of the impeller formed by the mold apparatus. The impeller 1 includes a boss 2 having a conical shape at the center, and a plurality of blades 3 protruding radially on the outer peripheral surface of the boss 2.
In the drawing, the number of blades is omitted for clarity, but the present embodiment has 14 blades. Further, as shown in FIG. 1, the shape of the rear edge side of the back side of the blade 3 and the shape of the front edge side of the abdominal side of the adjacent blade 3 overlap.

FIG. 2 is an arrow view of the entire injection molding die for molding the wax model 1 of the impeller. This mold includes a movable mold 4, a fixed mold 5, and a slide mold 6. FIG. 3 is an arrow view of the main part 7 of the fixed die 5 and the slide die (only one is shown for clarity). FIG. 4 is an enlarged view showing a state of the slide plate 8 having a curved surface portion attached to the fixed mold. FIG. 5 is an enlarged view of a main part 7 of the slide die. The main portion also has a curved surface portion 10 that matches the slide plate 8.

Next, the operation of the injection mold will be described with reference to FIGS. Overlapping impeller 1
Is assembled with a movable mold 4 and a fixed mold 5 that can be opened and closed in the product axial direction, and a slide mold 6 that is respectively arranged between the adjacent blades 3, and the molds are brought into close contact to form an impeller cavity. I do. Next, the wax model in a molten or semi-molten state is molded using an injection molding machine (not shown) to produce a wax model. After the wax material has solidified and a predetermined time has elapsed, the injection molding die is disassembled and the wax model is released.

First, the movable mold 4 is opened. Next, the main part 7 of the slide mold is radially pulled out along the groove provided in the fixed mold. At this time, the projection 11 attached to the main part 7 of the slide die obliquely moves on the curved surface along the groove 9 engraved on the slide plate having the curved surface part attached to the fixed-side die. The slide die is pulled out by rotating in accordance with the movement. The curved surface portion of the slide plate is set in accordance with the curved surface of the blade surface. However, depending on the shape of the overlapping surface of the blade portion, it may be a simple columnar or cylindrical part. Although the slide die moving means is not shown, a method of manually pulling out individual slide die main parts, preferably, the slide die is integrated by an interlocking structure, and each slide die retreats. The structure can be pulled out.

[0015]

According to the present invention, the production efficiency can be remarkably improved in producing a uniform and stable wax model of an impeller having overlapping blades, and the impeller by the lost wax precision casting method can be produced. This is an indispensable technology for manufacturing.

[Brief description of the drawings]

FIG. 1 is a front view showing the entire wax model of an impeller.

FIG. 2 is an arrow view of the entire injection molding die.

FIG. 3 is an arrow view of a fixed mold 5 and a main part 7 (only one is shown for clarity) of a slide mold.

FIG. 4 is an enlarged view showing a state of a slide plate having a curved surface portion attached to a fixed mold.

FIG. 5 is an enlarged view of a main part of the slide mold.

[Explanation of symbols]

 Impeller Boss Blade Movable mold Fixed mold Mold slide mold Slide mold main part Slide plate Slide plate groove Curved surface

Claims (3)

[Claims] 1. An injection mold for molding a wax model of an impeller manufactured by a lost wax precision casting method having a plurality of blades radially arranged with respect to a product axis, the mold being capable of being opened and closed in the product axis direction. A slide mold that is disposed between the fixed mold and the movable mold and the adjacent blade, and that forms a blade cavity of the impeller by a shape that is arranged in an annular shape when the mold is pressed; The mold is movable in the radial direction,
It is rotatable with respect to the radial direction axis and has retreat means for rotating when the mold is opened, and a wax model is formed by a slide mold, the fixed mold and the movable mold. Mold for injection molding. 2. The rotary retreat means comprises a slide mold having a curved slide surface, and a guide which is fitted and slid on the slide surface, and the slide mold is moved from a mold clamping position to a product shaft. 2. The injection molding die according to claim 1, wherein the die revolves radially along the guide and rotates along the curved surface of the slide surface. 3. The rotating means includes a groove formed on a curved slide surface of the slide die, the protrusion being disposed obliquely with respect to a radial axis on the guide for fitting and sliding. The injection mold according to claim 1, wherein the mold is set by a structure that slides along the mold.