JPH0714535B2 - Simplified manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for easily manufacturing a mold using a low melting point alloy, and particularly to a mold having a cavity as seen in a resin molding mold. The present invention relates to a method for easily manufacturing.

(Prior Art) Conventionally, as a simple mold manufacturing method, generally used is a general-purpose casting method in which a low melting point alloy such as a zinc alloy (ZAS) is cast into a mold obtained by transferring a wooden mold to a gypsum or sand mold (“ Metal Press "1976
However, in this method, the plaster and sand molds are transferred from the wooden molds, so the number of man-hours cannot be increased, and there is great dissatisfaction in terms of productivity and cost. Was becoming.

Therefore, for example, JP-A-63-273544 and JP-A-64-1853
As shown in Japanese Patent No. 5, etc., one of the pair of molds is cast by pouring a low melting point alloy into a mother mold such as a wooden mold or a resin model through a heat resistant rubber sheet made of silicon rubber, fluororubber, etc. Then, after that, one of the molds is used as a new mother mold, and a low melting point alloy is poured into the mother mold through the rubber sheet to cast the other of the paired molds. According to such a method, since the wood mold and the like are protected by the heat-resistant rubber sheet, the mold can be directly cast from the mother mold, which eliminates the above-mentioned transfer step and improves productivity. Can be achieved and cost can be reduced.

(Problems to be Solved by the Invention) However, according to the simple mold manufacturing methods disclosed in the above two publications, the heat-resistant rubber sheet also plays a role of guaranteeing the mold clearance. However, since the rubber sheet has a uniform thickness, it is not possible to form the cavity, and in that mode, it cannot be applied to the production of a resin molding die or the like that requires the cavity. There was a problem. Of course, if a model having a product shape is prepared in place of the rubber sheet, and this model is placed on the surface of a new mother die and cast, the use of the model becomes possible. However, in this case, the surface part of the matrix around the model comes into direct contact with the low melting point alloy, and seizure (welding) occurs in this part,
This seizure becomes remarkable especially when similar alloys are combined,
In reality, there was no choice but to give up its use.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to maintain a basic aspect of casting a die directly from a mother die, and to provide a die having a cavity. It is an object of the present invention to provide a simple casting method capable of manufacturing a steel with high efficiency and high accuracy.

(Means for Solving the Problems) In order to solve the above problems, the first invention is to cast one of a pair of molds by pouring a low melting point alloy into a mother mold such as a wooden mold or a resin model. After that, a model having a product shape is placed on the upper surface of the mold, and a thin film made of a heat-resistant material is placed around the model in the mold. The gist is that the melting point alloy is poured and the other of the pair of molds is cast.

A second invention is that a low melting point alloy is poured into a mother die such as a wooden die or a resin model to cast one of the paired die, and thereafter,
A model having a product shape is arranged on the upper surface of the mold, a mold made of a heat-resistant material is arranged on the upper surface of the new mold as a new mother mold, and a low melting point alloy is poured into the mold. It is characterized in that the plate is cast and the other of the pair of molds is cast.

In the above-mentioned two inventions, when casting one of the pair of molds, it is preferable to protect the surface of the mother mold such as a wooden mold or a resin model by some method, for example, the above-mentioned JP-A-63-273544. As disclosed in JP-A-64-18535 and JP-A-64-18535, a method of interposing a heat-resistant rubber sheet made of silicon rubber, fluororubber or the like on the surface of a mother die, or a silicone resin is previously formed on the surface of the mother die. A method of applying a heat resistant paint such as paint or fluororesin paint is effective.

Further, in the above-mentioned two inventions, the model to be placed on the upper surface of the new mother die is molded on the surface of the mother die and placed as it is It may be arranged at. In order to mold the model on the upper surface of the master mold, for example, a method of pouring a modeling material such as putty or plaster onto the master mold and hand-finishing can be adopted. In this case, it is desirable to select a silicone resin as the putty material because it has high heat resistance and good moldability.

Further, in the above-mentioned two inventions, the heat-resistant thin film or plate to be arranged on the upper surface of the new master mold does not specify the material as long as the low melting point alloy can be prevented from being seized to the new master mold. It is desirable to select a resin film such as a silicone resin as the thin film and a metal plate such as a steel plate as the plate. When a resin film is used as the thin film, the resin coating can be thinly applied to the surface of the mother die, and then dried and solidified. When one plate is used, it is premised that the plate is integrated with the other of the pair of molds to be used as a part of the mold. It is possible to use a method in which the studs are planted and the studs are surrounded by casting.

(Operation) In the simple mold manufacturing method configured as described above, by disposing the thin film or plate around the model, one mold cast from a master mold such as a wooden mold or a resin model can be used as a mother mold. Even when the other mold is cast as a mold, the low melting point alloy does not come into direct contact with the surface of the mother mold, and seizure between the pair of molds can be prevented in advance.

(Example) Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

1 and 2 show a first embodiment of the present invention. In the first embodiment, a wooden mold 1 is used as a mother mold and a female mold 2 is used.
Of the first mold (FIG. 1) and a second process (FIG. 2) of casting the male mold 3 using the female mold 2 as a new mother mold. In the first step, first, the wooden mold 1 processed from raw wood is left in vacuum for a predetermined time to sufficiently drain water from the inside, and then the wooden mold 1 is dipped in a silicone resin coating, A silicone resin is sufficiently permeated into the surface layer portion on the product shape portion 1a side. Next, for example, a far infrared ray lamp is used to irradiate the surface of the wooden mold 1, and the silicone resin coating is sufficiently baked and dried to form a hard silicone resin impregnated layer 4 on the surface layer portion of the wooden mold 1 on the product shape portion 1a side. To form. After that, the wooden mold 1 is set in a pair of upper and lower casting frames 5 and 6 as shown in FIG. 1, the low melting point alloy 7 is poured into the space above the wooden mold 1, and the solidification is performed by cooling. Then, the female mold 2 is cast. At the time of this casting, the heat resistance of the wooden mold 1 is increased by the presence of the silicone resin impregnated layer 4 so that the wooden mold 1 will not be damaged by the heat of the molten metal, and water will be discharged from the wooden mold 1 by leaving it in a vacuum in advance. Therefore, a large amount of gas is not generated during casting, and the female die 2 having excellent shape and quality can be obtained.

Next, the female mold 2 obtained as described above is inverted together with the casting frame 5, and as shown in FIG.
A putty (not shown) made of silicone resin is poured into the inside, and this putty is manually molded to obtain a product (molded product).
A model 12 having a shape is formed. Next, a silicone resin paint is uniformly applied to the upper surface of the female mold 2 including the model 12, and this is dried and solidified to form a silicone resin film 13 having a thickness of several tens to several hundreds of μm. Then, another casting frame 14 is placed on the casting frame 5 in a superposed manner, the low melting point alloy 7 is poured into the casting frame 14, and the mixture is cooled and solidified to cast the male mold (3).
After casting, if the molds 2 and 3 are released and the model 12 is released, a common cavity is formed between the molds 2 and 3.

During casting of the male die 3, the low melting point alloy 7 does not directly contact the female die 2 due to the presence of the model 12 and the silicone resin film 13, and therefore seizure occurs between the die 2 and the die 3. Without doing so, a mold having excellent shape accuracy can be obtained. Moreover, in this embodiment, since the model 12 is molded using the silicone resin putty, it is possible to mold the model extremely easily and accurately due to its good moldability, and efficient mold manufacturing is possible. become.

Needless to say, the silicone resin film 13 may be formed only around the model 12.

FIG. 3 shows a second embodiment of the present invention.
The second embodiment is also the same as the first embodiment in that it is composed of the first and second steps.
Only the second step will be shown here. In the second embodiment, the product shape portion 2a of the female die 2 obtained in the second step
Then, the model 12 is formed using the silicone resin putty as in the first embodiment, and the steel plate 15 having a plate thickness of about 2 mm is placed on the surface of the female die 2 around the model 12.
A plurality of studs 16 are preliminarily set up on the steel plate 15 by welding so that the studs 16 face the casting frame 14. Under this condition, the low melting point alloy 7 is placed in the casting frame 14.
Is poured and cooled and solidified. Then, the stud 16 is cast around the obtained male die (3), and the steel plate 15 is integrated with the male die 3. The male mold 3 is put to practical use together with the steel plate 15. At the time of casting, the steel plate 15 plays a role of preventing seizure of the molds 2 and 3, and a mold having excellent shape accuracy can be obtained as in the first embodiment.

(Effects of the Invention) As described above in detail, according to the simple mold manufacturing method of the present invention, one mold cast from a master mold such as a wooden mold or a resin model is used as a master mold for the other mold. Even if the mold is cast, the thin film or plate arranged on the surface of the master mold prevents the two molds from seizing, so that the mold having the cavity can be manufactured with high efficiency and high accuracy.

[Brief description of drawings]

1 and 2 are sectional views showing a first embodiment of the present invention, and FIG. 3 is a sectional view showing a second embodiment of the present invention. 1 …… Wooden mold 2 …… Female mold 3 …… Male mold 5,6,14 …… Casting frame 7 …… Low melting alloy melt 12 …… Model 13 …… Thin film (silicone resin) 15 …… Plate (steel plate) 16 …… Stud

Claims (2)

[Claims] 1. A low-melting-point alloy is poured into a mother die such as a wooden mold or a resin model to cast one of the paired molds, and then a model having a product shape is arranged on the upper surface of the mold. Placing a thin film made of a heat-resistant material around the model of the mold, using this mold as a new master mold, and pouring a low melting point alloy into the mold to cast the other of the paired molds. A simple manufacturing method characterized by the above. 2. A low-melting-point alloy is poured into a mother die such as a wooden mold or a resin model to cast one of the paired molds, and then a model having a product shape is arranged on the upper surface of the mold. Using the mold as a new master mold, place a plate made of a heat resistant material on the upper surface of the new master mold, pour low-melting point alloy into the plate, cast the plate, and cast the other of the pair of molds. A simple manufacturing method characterized by: