JPH02307632A - Manufacture of simplified die - Google Patents

Abstract

PURPOSE:To uniformly stick the die to a matrix and to surely secure the die clearance by applying a substance having a low friction coefficient to at least one of the surface of the matrix and the surface of a rubber sheet which adhere closely to each other. CONSTITUTION:On a surface layer part of a matrix 8, an impregnated layer 11 of a silicone resin is formed. Subsequently, molybdenum disulfide is applied by a spray to the product shape surface of the matrix 8 and a film 12 of molybdenum disulfide is formed on the product shape surface of the matrix 8. Next, the matrix is set to a punch casting frame 2, a heat resisting rubber sheet (silicone rubber) 7 is set thereon, a die casting frame 1 is formed integrally, and thereafter, by supplying negative pres sure to the punch casting frame, the matrix and the rubber sheet are allowed to adhere closely to each other. Thereafter, by bringing the matrix into contact with a molten metal M for a low melting point alloy in the casting frame 2, and cooling it, one of die is cast. It is brought into contact with the low melting point alloy molten metal in the other casting frame as a new matrix, and cooled, by which the other die is cast. In such a way, since a substance 12 of a low friction coefficient is applied, the rubber sheet expands and contracts smoothly and the mold clearance can be secured surely.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for easily manufacturing a mold using a low melting point alloy.

(Prior art) Conventionally, as a simple manufacturing method, there is a dual form method in which a punched sheet metal model is immersed in a molten low melting point alloy in a melting tank and then solidified to obtain a punch and die at the same time. ([Machines and Tools J June 1975 P2i-25, Japanese Patent Publication No. 4B-7576, etc.] Or, as a modification of the dual form method, a sheet metal model without perforations is used, and the inner and outer surfaces of the sheet metal model are A method of simultaneously obtaining a punch and die of different alloys by contacting with a molten metal of a low melting point alloy and solidifying it as it is (Japanese Patent Publication No. 53-159H, Japanese Unexamined Patent Publication No. 51/1982)
-55733, JP-A-51-95930, etc.) have already been established. According to these methods, it is possible to obtain the punch and die at the same time using a sheet metal model, compared to conventional general-purpose methods in which plaster and sand molds are sequentially transferred from the mother mold, manufactured, and cast into the sand mold. , productivity will improve significantly.

However, according to these methods, in order to guarantee mold shape accuracy, a high-precision sheet metal model must be prepared, which is extremely troublesome to manufacture, and cannot easily accommodate complex design changes. The problem was that it lacked versatility.

Recently, efforts have been made to develop a method for easily manufacturing molds using a matrix made of a wooden mold, a resin model, etc., and a heat-resistant rubber mold made of silicone rubber, fluorine rubber, etc. Publication No. 1984-185
This is disclosed in Publication No. 35. Take a look at JP-A-1984
This method will be explained with reference to FIGS. 3 and 4 taken from Publication No. 18535. First, a guide casting frame 1 and a punch casting frame 2 each consisting of a substrate 3 and a frame body 4 are prepared, and a punch casting frame 2 is prepared. The mother mold 8 is placed in the casting frame 2, and both casting frames 1.2 are assembled together with a heat-resistant rubber sheet 7 in between, and then the pouring port 6 on the punch casting frame 2 side is closed with a vacuum pump (not shown). ), negative pressure is introduced into the punch casting frame 2, air is removed using the air vent hole 8 provided in the matrix 8, and the rubber sheet 7 is forcibly brought into close contact with the matrix 8 ( Figure 3). Then, while maintaining the close contact of the rubber sheet 7 to the mother mold 8, the molten metal M of the low melting point alloy is poured into the mold casting frame 1 through the pouring port 5, and then cooled and solidified to form the die D. Cast (
1st step).

Next, remove the substrate 3 on the punch casting frame 2 side and
Take out the board 3 and attach the board 3 again (FIG. 4). During this work, negative pressure is applied from the pouring port 5 on the Gui casting frame 1 side using a vacuum pump (not shown), and the rubber sheet 7 and die D
The rubber sheet 7 is brought into close contact with the die D by removing air from between the rubber sheet 7 and the die D. After that, the low melting point alloy molten metal M is poured from the pouring port 6.
The molten metal is poured into the punch casting frame 2, cooled and solidified, and the punch P is cast (second step).

According to this method, mold clearance can be easily secured by adjusting the thickness of the rubber sheet 7,
It becomes possible to solve the problems in the above-mentioned dual form method using sheet metal nedel and its modification method.

(Problem to be Solved by the Invention) However, according to the simple manufacturing method using the rubber sheet 7, depending on the shape of the matrix 8, the rubber sheet 7
There was a problem that variations in the thickness of the mold were likely to occur, making it difficult to guarantee mold clearance. This is shown in Figure 5(a)
To explain using the model shown in , (b), if we consider the minute cross section S corresponding to the corner of the matrix 8, the difference in thickness [tl''t2] of the rubber sheet 7 will be It is proportional to the difference Δε of the left and right strain ε.On the other hand, this strain difference Δε is proportional to the coefficient of friction between the rubber sheet 7 and the matrix 5, the Young's modulus of the rubber sheet 7 to E, and the air vent hole 8. The negative pressure suction force of the tail is Pv, the thickness of the rubber sheet 7 is t,
The total strain acting perpendicularly to the bottom surface of the micro cross section S is expressed as (Σεi (
a)+Σεj(b)) It is given by the following formula.

Doyo (Σεi (a) + Σεj (b)), that is,
The strain difference Δε depends on the coefficient of friction between the rubber sheet 7 and the matrix 8, and therefore, in order to make the thickness of the rubber sheet 7 uniform, it is necessary to reduce this coefficient of friction. However, conventionally, no measures have been taken to proactively reduce this coefficient of friction, especially when it comes to the matrix 8.
If the mold has a complicated shape, or if the mother mold 8 is made of a wooden mold, it may be difficult to guarantee mold clearance, and there is a risk that the mold may become unusable.

KIHATSU I was created with the aim of solving the above problem, and it eliminates the variation in the thickness of the 7 rubber sheets that adhere to the mother mold, thereby stably producing molds with excellent precision. The object of the present invention is to provide a simple manufacturing method that can obtain the desired results.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention has the steps of: closely adhering a heat-resistant rubber sheet to a mother mold; One of the paired molds is then cast by cooling, and then one of the molds is used as a new mother mold, and it is brought into contact with the molten low melting point alloy in the other casting frame, and then cooled. In the manufacturing method of a simple crystal mold, in which the other of a pair of molds is cast using a metal mold, a substance having a low coefficient of friction is applied in advance to at least one of the surface of the mother mold and the surface of the rubber sheet that are in close contact with each other. It is characterized by being configured as follows.

In the present invention, the substance having a low coefficient of friction is not particularly limited in type as long as it does not change in quality at the melting temperature of the low melting point alloy (50 to 300°C),
For example, molybdenum disulfide (MoS2), boron nitride (BN), Graphi 1-(C), etc. can be selected. Further, the method of applying the substance having a low coefficient of friction is also arbitrary, and various methods such as coating, spraying, dipping, etc. can be employed.

Further, in the invention, the substance having a low coefficient of friction described in 1.
It can be applied directly to the surface of the matrix, but if a wooden mold is used as the matrix, the surface of the wooden mold must be coated or impregnated with a heat-resistant paint, such as silicone resin or fluororesin, in advance. It is desirable to keep the surface roughness of the matrix small.

(Function) In the simple manufacturing method configured as described above, a substance with a low coefficient of friction is applied to the surface of the mother mold or the rubber sheet, so that when the rubber sheet is brought into close contact with the mother mold, the rubber sheet expands and contracts. The material will be smooth and will be able to be stretched onto the matrix with a constant thickness.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings. Note that the basic steps of this example are the same as the simple manufacturing method explained based on FIGS. 3 and 4 above, so only the main parts are shown here, and the manufacturing method shown in FIG. , parts that are the same as those shown in FIG. 4 are given the same reference numerals, and redundant explanations will be omitted.

FIGS. 1 and 2 show the first step of IJIJ to obtain the die (D). In this first step, a wooden mold is used as the mother mold 8, silicone resin is applied to the product shape surface by spraying in advance, and the silicone resin is sufficiently permeated to coat the surface layer of the mother mold 8 with silicone resin. An impregnated layer 11 is formed. Next, molybdenum disulfide (MoS2) is sprayed onto the product-shaped surface of the matrix 8 to form a molybdenum disulfide film 12 on the product-shaped surface. At this time, after applying molybdenum disulfide,
It is desirable to slightly rub the film 12 to make it slippery.

Next, the mother mold 8 prepared as described above is set in the punch casting frame 2, a heat-resistant rubber sheet (silicon rubber) 7 is further set on top of it, the die casting frame 1 is integrated, and then the punch casting frame 2 is set. Negative pressure is supplied to frame 2. By this negative pressure supply, the air between the product-shaped surface of the mother mold 8 and the rubber sheet 7 is discharged to the outside through the air vent hole 8, and the rubber sheet 7 is moved to the mother mold 8.
closely adhere to. At this time, the molybdenum disulfide film 12
Since the frictional resistance between the rubber sheet 7 and the matrix 8 is reduced due to the presence of It will stick to a constant thickness of i corresponding to the plate thickness of the pressed product. Incidentally, the friction coefficient between the rubber seal I.7 and the matrix 8 is 0.2 when the molybdenum disulfide film 12 is formed as in this embodiment, whereas it is 0.2 as in the conventional case. When no film is formed, the value is 0.8, and this large difference in friction coefficient contributes to eliminating the strain difference (Δε). In addition, in this embodiment, since the silicone resin impregnated layer 11 is particularly formed under the molybdenum disulfide skin 112, the surface roughness of the matrix 8 is reduced as much as possible, and the expansion and contraction of the rubber sheet 7 is further reduced. It becomes smoother and its thickness becomes more uniform.

Therefore, after that, if the low melting point alloy molten metal M is poured into the die casting frame and brought into contact with the mother mold 8, and is visibly cooled and solidified, a die D with good precision can be obtained, and then the die casting frame The rubber sheet 7 is stretched over the die D by supplying negative pressure into the die D, the mother die 8 is removed from the mold, and then the low melting point alloy molten metal M is punched into the casting frame in the manner described in FIG. 4 above. By pouring the metal into 2 and casting the punch, a mold with excellent mold clearance can be obtained. Therefore, when demolding the mother mold 8, the mother mold 8 is easily separated from the rubber sheet 7 due to the presence of the molybdenum disulfide film 12, and damage to the rubber sheet 7 is prevented, making it possible to use it repeatedly. become.

It should be noted that the present invention is of course not limited to the embodiments described above, and for example, as shown in Japanese Patent Application Laid-Open No. 83-273544, a simple mold is manufactured by placing a mother mold in a pair of upper and lower casting frames. It can also be applied to methods that

(Effects of the Invention) As described above in detail, according to the mold manufacturing method according to the present invention, the presence of the substance having a low coefficient of friction allows the rubber sheet to smoothly expand and contract, and the mold It has the effect of sticking evenly and ensuring mold clearance. Further, by reducing the friction between the mother mold and the rubber sheet, the mother mold can be easily removed from the mold after casting, and there is an effect of preventing damage to the rubber sheet during demolding.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an example of manufacturing a simple type according to the present invention, Fig. 2 is an enlarged sectional view of section A in Fig. 1, and Figs. 3 and 4 are a conventional simple type. A cross-sectional view showing an example of manufacturing,
FIGS. 5(a) and 5(b) are explanatory diagrams illustrating the causes of variations in the thickness of the rubber sheet using a model. 1... Gui mold flask 2... Punch casting frame 7... Rubber sheet 8... Mother die 11... Impregnated layer 12... Low friction material coating M... Low melting point alloy molten metal No. 3 Notebook 4 Figure 5 (a) (b)

Claims (1)

[Claims] (1) A heat-resistant rubber sheet is closely attached to the mother mold, the mother mold is brought into contact with the molten low melting point alloy in the casting frame, and one of the paired molds is cast by cooling it as it is, and then In a simple mold manufacturing method, one of the molds is used as a new mother mold, and this is brought into contact with the molten low melting point alloy in the other casting frame, and the other mold of the pair is cast by cooling. A simple manufacturing method characterized in that a substance having a low coefficient of friction is applied in advance to at least one of the surface of the mother mold and the surface of the rubber sheet that are to be brought into close contact with each other.