JPS60145243A - Production of die - Google Patents

Abstract

PURPOSE:To manufacture easily a die which can be formed by decreased machining by coating the cavity of a casting mold formed of a ceramic slurry with an air permeable casting mold provided with a sprue and subjecting the die obtd. by pouring a molten metal into the mold to electric discharge machining. CONSTITUTION:Three layers consisting of zircon flower, mold coating material and xylol resin are successively formed on the surface of a die pattern 3 consisting of rigid foamed urethane formed by allowing for a margin for elongation, margin for working, etc. The pattern 3 is set in a flask 5 and a ceramic slurry 6 is cast therein from above and is soldified. The slurry is allowed to dry naturally and is calcined to form a ceramic casting mold 9. The mold 9 is set between a cope 10 and a draft 11 and a molten metal M is poured into the cavity 9a of the mold 9 through the sprue 13 of the cope 10 to form a casting 16. The casting 16 is subjected to machining, hardening and tempering then to electric discharge machining by a discharge electrode followed by prescribedfinish working, by which an intended die 18 is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a mold used for die casting, press molding, etc.

Conventionally, when manufacturing molds, a metal block is machined to approximate a predetermined mold shape, and the mold is finally obtained by hand finishing. Such conventional methods require a considerable amount of time for machining, and furthermore, require a cumbersome manual finishing step after machining. For this reason, in order to directly manufacture precision parts from the shape of a mold, a precise model must first be prepared, which is time-consuming and costly, and if the mold itself is large and has a complex shape. This results in poor dimensional accuracy and requires a lot of effort in the subsequent correction process.Furthermore, in the case of precision casting, the outermost surface of the casting becomes the surface of the mold.
There are problems such as the need to pay close attention to the occurrence of casting defects.

On the other hand, the full mold method is known as a mold manufacturing method that allows easy model manufacturing and is excellent in mass production. In this full mold method, a mold model is made from styrofoam, this model is set in a frame and filled with molding sand, etc., a mold is made, and the molten metal is poured into the mold. If the Styrofoam is vaporized and disappears, and if there is molten metal in the area where the Styrofoam has disappeared, gas will be generated as the Styrofoam vaporizes at the same time as the molten metal is poured, and this gas component will dissolve into the molten metal. For this reason, the materials that can be cast are limited to cast iron,
It is difficult to apply to cast steel, etc.

The present invention was created in view of the problems in conventional mold manufacturing described above, and its purpose is to facilitate the production of a mold model and to reduce the number of machining steps required to produce the mold. Moreover, it is an object of the present invention to provide a method for manufacturing a mold that can also be applied to a mold made of cast steel or the like.

In order to achieve the above object, the present invention manufactures a model by subjecting hard urethane foam to NC processing, sets the model in a frame, and pours ceramic slurry to create a molded body. The model is removed from the body and the molded body is fired to obtain a ceramic mold.The cavity of the ceramic mold is then covered with a mold having air permeability and a sprue, and molten metal is injected into the cavity from the sprue. ,
The gist is that the casting is then ejected from the ceramic mold, and the casting is subjected to electrical discharge machining to form a mold.

An example of the method of the present invention will be explained below in order of steps according to the drawings.

First, as shown in FIG. 1, a material 1 is cut using a general-purpose NC die carving machine 2, taking into account the allowance for stretching, electrical discharge machining, etc., to obtain a die model 3. Here, it is desirable that the material for the model 3 has properties such as being vaporized by heating, being easy to cut, having a good finished surface roughness, having excellent strength, allowing the use of adhesives, and being easy to modify. However, taking these into consideration, a hard foamed urethane resin or a hard foamed polystyrene resin is suitable.

Further, a surface layer 4 is formed on the surface of the mold model 30.

The surface layer 4 consists of three layers, and the inner first layer is a layer of about 25μ thick made of zircon flour, and the resol 3 is made of zircon flour as the main material on the surface of this first layer.
A coating agent consisting of 50% methanol and 50% methanol is applied and dried to form a second layer, and the surface of this second layer is sprayed with Kijirol resin to form a third layer. In this way, by forming the smooth surface layer 4 on the surface of the mold model 3, it is possible to improve the casting surface of the casting that will become the mold, and also to prevent abnormal electrical discharges during electrical discharge machining caused by refractories remaining on the casting surface. can be prevented.

Next, the mold model 3 obtained as described above is set in a frame 5 as shown in FIG. 2, and a ceramic slurry 6 is poured onto it. The constituent materials of the ceramic slurry 6 include, for example, a refractory aggregate consisting of 40% zircon sand, 30% chamotte sand, and 30% zircon flour, and an ethylene silicate hydrolyzed solution as a binder in an amount of 10 to 12% based on the aggregate. In addition, ammonium carbonate was added as a hardened oil at a ratio of about 0.2% to the binder, and the mixture was mixed and stirred.

Then, after pouring the ceramic slurry 6 into the frame 5 and leaving it for about 5 to 7 minutes to solidify, after 15 to 30 minutes, the ceramic molded body 7 is removed from the frame 5 as shown in FIG. Take out the mold model 3 from the ceramic molded body 7
remove. In this case, if the mold model 3 has an undercut or the like, the mold model 3 may not be completely removed, but a small amount may be left.

After that, it was allowed to air dry for 8 to 12 hours, and then put into a furnace as shown in Figure 4, fired in a mill 8 at 900°C for 3 to 6 hours, cooled to 150 to 200°C, and taken out. A ceramic mold 9 is obtained.

Next, as shown in FIG. 5, the ceramic mold 9 is set between the upper and lower molds 10° and 11. That is, both the upper mold 10 and the lower mold 11 are made of phenolic organic self-hardening sand and have good air permeability.

Further, a recess 12 that opens upward is formed in the lower mold 11,
The ceramic mold 9 is placed in the cavity 9 in this recess 12.
It is set so that a is the top surface.

On the other hand, the upper mold 10 is provided with a sprue 13, a runner 14, and a riser 15.

From the above state, as shown in FIG. 6, molten metal M equivalent to JIS 5KD61, for example, is injected from the sprue 13.

The concrete casting temperature is 1570°C and the casting weight is about 300 Ky. Here, before injecting the molten metal M, the surface of the ceramic mold 9 is heated by a burner for 40 min.
You may heat it to 0-500 degreeC. In this way, casting defects such as poor molten metal flow and scale formation can be prevented.

Furthermore, when the molten metal M is injected, the molten metal M entrains gas, or the mold model 3 remaining in the undercut of the ceramic mold 90 evaporates, generating gas, and the molten metal M entrains this gas, and the ceramic The mold 9 does not have air permeability, but as described above, the cavity 9d of the ceramic mold 9 is covered with the upper mold 10 which has air permeability, so the gas in the cavity 9a is exhausted to the outside through the upper mold 10. , no casting defects occur.

After that, the upper and lower molds 10 and 11 are released, and a casting 16 as shown in FIG. Holes, extrusion pin holes, etc. are machined, and then quenching and tempering are performed to obtain a predetermined hardness, for example, HRC 40 to 45 for die casting molds.

Next, using the discharge electrode 17 obtained by separate N'C machining, the casting 16 was subjected to electric discharge machining as shown in FIG.
Thereafter, sandblasting, tuftride treatment (treatment temperature = 570 DEG C., treatment time 15 to 2 hours), etc. are performed to obtain the desired mold 18 as shown in FIG.

The above is an example of the implementation of the present invention, and the present invention is not limited to the conditions described above, such as the material of the model, the constituent materials of the ceramic slurry, the casting temperature, etc. In cases where the mold is made of cast iron, the heat treatment steps such as annealing, hardening, and tempering described above may be omitted.

As explained above, according to the present invention, the material is made of hard urethane foam, etc., and the mold is obtained by cutting it in consideration of stretching or electric discharge machining costs, so that conventional precision casting is not possible. Compared to this method, the mold is easier to manufacture and the surface of the mold can be made smoother, and the quality of the mold is improved by zero. In addition, since the cavity of the ceramic mold is covered with a permeable mold during mold casting, gas can be removed reliably, and a wide range of mold materials can be selected from die steel to cast iron. Demonstrates the effect of

[Brief explanation of the drawing]

Figure 1 is a side sectional view showing the process of making a mold model.
Figure 2 is a side sectional view of the ceramic slurry poured into the frame, Figure 3 is a side sectional view of a molded body made of ceramic slurry, and Figure 4 is a side view of the molded body being fired. 5 is a side sectional view showing the state in which the ceramic mold is set between the upper and lower molds, FIG. 6 is a side sectional view showing the state in which the ceramic mold is being used for casting, and FIG. Fig. 8 is a side view of the obtained casting, and Fig. 9 is a partially sectional side view showing the state where the casting is subjected to electric discharge machining.
The figure is a side sectional view of the mold. In addition, in the drawing, 1 is the material of the mold model, 3 is the mold model, 5 is the frame, and 6
is a ceramic slurry, 17 is a molded body, 9 is a ceramic mold, 9a is a cavity, 10.11 is a mold, 13 is a sprue, 1si product, 17 is an electric discharge machine, 18 is a mold, and M is a molten metal. . Patent applicant Honda Motor Co., Ltd. agent Patent attorney 2 1) Production department Patent attorney Kuni Ohashi Production volume Patent attorney Yu Koyama Figure 7 1G Figure 8

Claims (3)

[Claims] (1) Form a model with allowances for stretching or processing, etc.
Ceramic slurry is poured into the frame in which this model is set to make a molded body, and the model is removed from this molded body (
At the same time, the molded body is fired to form a ceramic mold, and then the cavity of the ceramic mold is covered with a mold that is equipped with a sprue and has air permeability, and the molten metal is injected into the cavity of the ceramic mold from the sprue, and then the product is poured from the ceramic mold. A method for manufacturing a mold, characterized in that a barrel mold is taken out and electrical discharge machining is performed. (2) A layer made of zircon flower is formed on the surface of the model, and an alcohol coating mainly composed of zircon flower is applied to the surface of this layer of zircon flower,
A method for manufacturing a mold according to claim 1, characterized in that a resin film is further formed on the surface of the mold after drying.
Law. (3) The method for manufacturing a mold according to claim 1 or 2, wherein the mold is made of hard urethane foam.