JPS6083739A - Assembling method of pattern for investment casting mold - Google Patents

Abstract

PURPOSE:To reduce the time for assembling and to improve assembling strength and surface shape by winding tubes which shrink when heated at a low temp. to the joint parts such as product part, runner, riser, etc. of a pattern for a casting mold and heating the pattern until the tubes shrink. CONSTITUTION:A PVC tube 4 which shrinks when heated is wound on the outside of the gate 3a of a product part 3 to attach the part 3 to a runner 2. The gate 3a is inserted into the attaching hole 2a of the runner 2 and the space between the hole 2a and the gate 3a is closed by the tube 4. A riser 5 is assembled to the runner 2 and a tube 6 is wound on the outside circumference of the end of a sprue 2 and the end of the riser 5 including both grooves 2b and 5a. When a pattern 1 for a casting mold made into a tree-like shape is heated, the tubes 4 and 6 shrink to fix the product part 3 to the runner 2 and to fix the riser 5 to the runner 2. The pattern 1 is then dipped in a slurry to form a coating layer on the outside and the casting mold is thus formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for assembling a model for investment casting.

Conventional technology In the investment casting method (lost wax casting method), which is a precision casting method, a refractory coating layer is formed around a wax model having the same shape as the product to be cast, and then the wax is cast! It is created by heating a mold to melt it and form a cavity within the coating layer. When manufacturing the wax model, the product part model, which will become the product after casting, the runner model, which will become the runner, and the riser part model, which will become the riser, etc. will be waxed separately. ! They are now able to create and assemble these and other things.

Conventionally, when assembling the product part model, runner part model, riser part model, etc. as described above, there have been two methods: (1) welding each model using a soldering iron, etc., and (2) adhesive. (3) A method of forming fitting portions between the parts to be assembled and fitting the fitting portions, etc. have been conventionally used.

However, among the conventional model assembly methods mentioned above, method (1) has the problem that the welded parts of the model are uneven, and these unevenness can be a factor in the occurrence of defects on the opposite object, and there are many problems with welding. Method (2), which had the problem of being time-consuming, had the problem that the adhesive used in the adhesive traps for each part of the model melted when the wax model was immersed in the binder that made up the fireproof souffle. There was a problem in that bonding required a lot of time.

In method (3), gaps occur at the fitting parts of each part model,
Slurry enters this gap and is washed away by the molten metal, causing defects, so there is a problem in that it is necessary to seal the outside of the gap.

Purpose of the Invention In view of the above, the present invention enables rapid and accurate assembly of a wax model for investment Ra, does not require padding of the assembly part, and further improves the strength after assembly. The object of the present invention is to provide a method for assembling a model that has sufficient functions.

Means for achieving the above object In order to achieve the above object, the present invention is accomplished as follows.

That is, in a model for an investment mold, which is formed by joining together the product part, runner part, riser part, etc., which were manufactured separately (using a brazing filler metal that melts by heating),
A tube that shrinks when heated at a low temperature is wrapped around the joints of the product section, runner section, riser section, etc., and the model is heated to a temperature at which the tube contracts. A model for an investment mold is formed by assembling the feeder and other parts.

Embodiments Next, the present invention will be explained based on embodiments shown in the drawings.

In Figure 1, tIX for investment mold, mold 1
(hereinafter referred to as the mold model) has a round bar-shaped runner 2, and four mounting holes 2a are drilled on the left, right, top, and bottom sides of the runner 2. There is. A weir 6a of a predetermined length is formed in the product part 6 to be assembled to the runner 2, and this [3&] corresponds to a size that allows insertion of the attachment hole 2aK of the runner 2. Here, both the runner section 2 and the product section 6 are manufactured using a thermosetting urea resin.

In order to attach the product part 6 to the runner part 2, a tube 4 made of vinyl chloride/l', which has the property of shrinking when heated, is wound around the outside of the weir 6a of the product part 3. Then, the weir 6a is inserted into the attachment hole 2a of the runner 2, and the gap between the attachment hole 2a and the weir 3a is covered with the tube 4. All the product parts 6 are attached to the runner part 2 as described above.

Next, in order to assemble the feeder part 5 made of urea resin to the runner part 2, an annular groove 2b is formed on the outer periphery of the end of the runner part 2 where the feeder part 5 is assembled. Groove 5 similar to 142b
a is formed on the outer periphery of the end of the feeder section 5 where the runner section 2 is assembled. Then, the end of the runner section 2 and the end of the riser section 5 are butted together,
including both grooves 2b and 5a, the end of the sprue section 2 and the feeder section 5;
Wrap the vinyl chloride IV'lJ tube 6 around the outer circumference of the end.

When the molding model 1 assembled into a tree shape as described above is heated to about 50° C. (lower than the melting temperature of the product part 3, etc.), the tubes 4 and 6 each contract. Then, as the tube 4 contracts, the product part 6 is fixed to the runner part 2, and as the tube 6 contracts, p*2b
and 5a, and fix the feeder section 5 to the runner section 2.

Next, this mold model 1 was immersed in ethyl silicate-based tree as a binder to form a coating layer on the outside to create a mold. There were no problems with this.

In this embodiment, when assembling the molding model 1, it is only necessary to wrap the heat shrink tube around the connection point between the sprue part and the product part and the connection part between the sprue part and the feeder part, so it is possible to assemble the mold model 1. Compared to the welding method, it is possible to shorten the assembly time and improve the surface shape of the assembled portion, and compared to the fitting method, it is possible to improve the assembly strength and the surface shape of the assembled portion. Furthermore, compared to the conventional method of assembling using a contact bonding agent, there are advantages in that it is not dissolved in the binder, has strong assembly strength, and can shorten the assembly time.

FIG. 2 shows a second embodiment of the invention. This figure shows the joining of the runners (made of urea resin) of the mold model, with a protrusion 7& formed at one end of the rod-shaped runner 7, and a recess 7b formed at the other end. has been done. In order to assemble a plurality of runners 7 to each other, the protrusion 7 of one runner 7 is
A is fitted into the recess 7b of the other runner 7, and a silicone heat shrinkable tube 8 is wrapped around the outer periphery of this fitted part.

When the required number of assembled runners 7 to 7 are heated in this way, each tube 8 contracts and the runners 7 to 7 are assembled to each other. In this embodiment, the convex portion 7a of one runner 7 is connected to the other runner 7.
The main function of the tube 8 is to fill the gap 9 between the two runners 7 and 7, and it also has the effect of slightly increasing the joint strength of the two runners 7 and 7. ing.

Effects of the Invention As is clear from the above explanation, according to the present invention, a model for investment casting can be reliably assembled in a shorter time than conventional methods without requiring any eyeliner, etc. Since no unevenness is caused in the assembly part, it is possible to prevent defects in the casting due to unevenness, and furthermore, the assembly strength can be improved compared to the conventional method.

[Brief explanation of drawings]

The figures show an embodiment of the present invention, FIG. 1 is a longitudinal sectional view of the investment casting model of the first embodiment, and FIG. 2 shows the second embodiment. The front view of the section, FIG. 2←) is a sectional view taken along the line 1-I in FIG. 2 (6). 1... Model for investment mold 2... Hot water path part 2a... Mounting hole 2 b...
・Groove 3...Product part 3 a...Weir 4...
・Heat shrink tube 7゛5...Riser section 6...Heat shrink tube 7-...Rice section 8-...Heat shrink tube Applicant: Toyota Motor Corporation Agent Patent attorney: Hideo Oka 1) Hikodai 1 Figure 2

Claims (1)

[Claims] A model for investment molding is formed by joining together product parts, runner parts, feeder parts, etc. that are separately manufactured using melted brazing material (by heating), and heating it to a temperature that causes the tube to shrink. A method for assembling a model for an investment mold, characterized by: