JPH10193036A - Manufacture of mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely manufacture a mold having complicate shape without using a pattern by forming raw material grain coating resin on the surface of a core as laminated state, irradiating this formed material with a beam having a prescribed pattern, melt-sticking the coated layer of the raw material grain, forming mold thin piece and laminating these mold thin pieces. SOLUTION: The coating layer composed of a thermal plastic resin is arranged on the peripheral by using the molding sand as a core. This raw material grain is filled to a prescribed thickness in a chamber 5 of an optical molding device 4 to form the raw material grain layer 6. A controller calculates a shape sliced to the thickness corresponding to the thickness of the raw material grain layer 6 and control signal is transmitted to a laser between irradiation device 7 so as to execute the laser beam scanning along a pattern observing this shape as the plane state. The raw material grain layer 6 is irradiated with the laser beam from a laser beam source 7a in a laser irradiation device 7 through a mirror 7b. The coated layer of the raw material grain layer 6 is melted to form the melt-sticking part and the mold thin piece 7 is formed. On this layer, the raw material grain layer 6 is laminated and irradiated with the laser beam. This process is repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a mold most suitable for casting a casting having a relatively complicated shape such as a pump blade.

[0002]

2. Description of the Related Art When casting an article having a complicated shape such as an impeller of a rotary machine, it is necessary to combine a core and a main mold in a complicated manner. As a method of manufacturing such a mold, in addition to the conventional method of (1) creating a main mold and a core from a wooden mold formed into a shape to be formed, (2)
A foamable polyurethane or the like is molded according to the product shape, embedded in molding sand, and poured directly onto the polyurethane (lost foam method). A method has been developed in which a shell is attached, and then the model is erased and used as a mold.

[0003]

However, in the conventional example described above, (1) it takes time and effort to create a wooden mold; (2) it is necessary to consider a mold crack when the model disappears, so that a casting method is created. (3) Sanding work at the time of shell making and drying after sanding are time-consuming and require considerable time.

[0004] The present invention has been made in view of the above circumstances, and is a method of manufacturing a mold capable of obtaining a cast product having high dimensional accuracy without using a conventional mold having a cavity along a shape to be formed. The aim is to provide a method.

[0005]

Means for Solving the Problems The present invention has been made to solve the above problems, and the invention according to claim 1 is a method for preparing raw material particles having a resin coating layer on the surface of a core. A step of forming the mold particles by laminating the material particles, irradiating the material particles with light in a predetermined pattern, and fusing the coating layers of at least some of the material particles to form a mold flake; And a step of forming a mold.

[0006] Thus, first, a two-dimensional mold flake (mold element) is prepared and laminated, whereby a three-dimensional mold is prepared directly from a powdery raw material. Light irradiation can be performed in an arbitrary pattern by light scanning (scanning), for example, by control by a computer, so that a mold having a complicated pattern can be manufactured without trouble. The data input at that time is also C
AD (computer aided design) or CAM (computer aided design)
ed manufacturing) data can be used as it is.

In the present invention, a resin is contained as a binder in the constituent material of the mold, which is decomposed by heat during casting. However, if the mold surface is maintained until a shell layer on the surface of the cast metal is formed. Often, this can be done by selecting the raw material and adjusting the density. Conversely, the good removability of the mold due to such a reaction can also be used effectively. As the light, laser light having strong directivity is preferable.

According to a second aspect of the present invention, a raw material particle layer is supplied onto the lower mold flake, and the layer is irradiated with light to form an upper mold flake. The method for producing a mold according to claim 1, wherein the mold is formed. This can be performed by, for example, a conventionally used stereolithography apparatus. The mold flake production step and the lamination step may be performed separately, but this makes the process simpler and can save a lot of time and effort.

According to a third aspect of the present invention, there is provided the method of manufacturing a mold according to the first aspect, further comprising a step of reinforcing the laminated mold. Thereby, casting of a large-sized article is attained and safety is improved. Conversely, since it is not necessary to bear the strength on the laminated mold itself, the thickness of this portion can be reduced to simplify the light irradiation step. Examples of the reinforcing method include a method of providing a reinforcing layer and a reinforcing frame outside the multilayer mold, a method of impregnating the multilayer mold with a reinforcing agent, and the like.

According to a fourth aspect of the present invention, there is provided the method of manufacturing a mold according to the first aspect, wherein the core and the main mold are formed in the same step. The core can also be formed by directly patterning the mold flakes in the irradiation step. The support for supporting the core may also be formed by patterning by light irradiation.

According to a fifth aspect of the present invention, raw material particles having a resin coating layer on the surface of a core are used as a raw material, and the coating layers of adjacent raw material particles are fused together to maintain the shape. It is a mold characterized by being performed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. First, as shown in FIG. 2 (a), casting sand 1 is used as a core,
Raw material particles 3 coated with a coating layer 2 made of a thermoplastic resin fused to each other at 00 to 150 ° C. are prepared. As a material of the casting sand 1, silica, zircon sand, chromite, or the like is used. The average particle diameter is about 30 to 40 μm. As a material of the coating layer 2, polycarbonate, nylon, polyurethane, or the like is used. About 1 to 10 μm is preferable.

As shown in FIG. 1A, the raw material thus prepared is uniformly filled into a chamber 5 of a stereolithography apparatus 4 with a predetermined thickness, for example, a thickness of 0.1 mm. The particle layer 6 is formed. The optical molding device 4 includes a laser irradiation device 7 disposed above the chamber 5 and a control device (not shown). The storage unit of the control device stores the shape of the mold to be manufactured in advance, for example, by numerical data. It is stored as

The controller calculates the shape of the material particle layer 6 in a circle corresponding to the thickness of the material particle layer 6, and instructs the laser irradiation device 7 to scan the shape with a laser beam along a pattern viewed in plan. Send a control signal to it. The laser irradiation device 7 irradiates a laser beam from a laser light source 7a such as a carbon dioxide laser generator to the raw material particle layer 6 via a mirror 7b. The temperature of the coating layer 2 of the raw material particle layer 6 at the location where the laser irradiation has been performed is raised, and the plastic resin is partially melted to form a fused portion 8, thereby forming a mold flake 9.

Next, a raw material is supplied onto the mold flake 9 to form a raw material particle layer 6 having the same thickness, and a laser irradiation is performed on the raw material particle layer 6 so as to have a shape following the mold flake 9.
The focal point of the laser beam is adjusted by adjusting the distance between the laser irradiation device 7 and the raw material particle layer 6 as necessary. By repeating this step sequentially, the laminated mold 1 as shown in FIG.
0 is created.

Casting can be performed using the thus-produced laminated mold 10 as it is. That is,
As shown in FIG. 3, a molten metal is poured from the gate 11 to solidify, the mold 10 is peeled off, and a casting 12 as shown in FIG.

As described above, since the laminated mold 10 is formed by bonding the raw material particles 3 through the fusion portion 8 of the thermosetting resin located at the portion irradiated with the laser beam,
As shown in FIG. 2B, the raw material particles 3 adjacent to each other
A gap S is present between 3, that is, porous, and the molding sand 1 is separated from each other via a coating layer 2. However, by forming the coating layer 2 sufficiently thin, it is possible to maintain the shape at the moment of casting and to obtain a density having sufficient strength to form a solidified layer (shell) on the surface of the metal. it can.

Conversely, after casting, the density is adjusted to such an extent that the coating layer 2 bonded to the mold is burned or decomposed and disappears, and the shape cannot be maintained, thereby facilitating separation of the casting from the mold. Or the core can be easily removed. Further, in order to adjust the mechanical properties and releasability of such a mold, an appropriate substance may be impregnated. In addition, a frame or an appropriate material “haga” may be fitted around the multilayer mold 10 for reinforcement.

FIG. 4 shows another embodiment of the method of the present invention, in which the laminated mold 10 manufactured by the stereolithography apparatus 4 has only a surface layer surrounding a cavity, and a backup layer 13 is formed around the surface layer. It is intended to reinforce. In this embodiment, the backup layer 13
Is formed by filling the space between the inner surface of the container 14 and the laminated mold 10 with sand, a fire-resistant castable, or the like, but the material and the forming method are arbitrary.

In this method, in addition to the improvement of the safety due to the improvement of the strength of the mold, it is possible to obtain the effects of reducing the time and labor for laser irradiation when forming the laminated mold 10 and improving the homogeneity of the mold. Can be. The thickness of the multilayer mold 10 can be made thin enough to maintain the shell shape.

FIG. 5 shows still another embodiment of the present invention, in which a core 15 is provided in a manner shown in FIG. 16
Are arranged. Further, a runner 17 for sub-casting is formed in the laminated mold 10.
As described above, according to the method of the present invention, not only a mold having a complicated shape can be easily formed, but also a portion such as a core or a runner can be formed in the same step as the formation of the mold.

[0022]

As described above, according to the present invention,
Without using a model of the shape to be molded, it is possible to accurately and easily manufacture molds of complicated shapes,
As a result, the number of processing steps can be reduced and the degree of freedom in shape design can be increased, and excellent effects such as improved quality and reduced manufacturing cost can be achieved in the casting of precision articles or in the case of small-lot production of many kinds.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a step of one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a structure of raw material particles and a bonding step thereof.

FIG. 3 is a view showing a structure of a laminated mold and a cast product.

FIG. 4 is a cross-sectional view illustrating a mold according to another embodiment.

FIG. 5 is a sectional view showing a mold according to still another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Foundry sand (core) 2 Coating layer 3 Raw material particle 4 Stereolithography device 6 Raw material particle layer 7 Laser irradiation device 8 Fusion part 9 Mold flake 10 Laminated mold 13 Backup layer 15 Core 16 Support part

Claims (5)

[Claims] 1. A step of preparing raw material particles having a resin coating layer on the surface of a core, forming the raw material particles into a layer, and irradiating the layer with light in a predetermined pattern to form a coating layer of at least a part of the raw material particles. A method for producing a mold, comprising: a step of forming a mold flake by fusing them together; and a step of forming a laminated mold in which the mold flakes are laminated. 2. A method of supplying a raw material particle layer onto the lower mold flake, irradiating light to form an upper mold flake, and sequentially repeating this process to form the laminated mold. A method for producing a mold according to claim 1. 3. The method according to claim 1, further comprising performing a reinforcing step of reinforcing the laminated mold. 4. The method according to claim 1, wherein the core and the main mold are formed in the same step. 5. A method in which raw material particles having a resin coating layer on the surface of a core are used as a raw material, and the coating layers of adjacent raw material particles are fused together to maintain a shape. Mold.