JPH0788594A - Sprue rod used to lost wax casting - Google Patents

Abstract

PURPOSE:To shorten the flow-out time of a wax at the time of dewaxing by nicking recessed grooves on the outer surface of a melt-sticking part, forming the recessed grooves toward and axial direction of the melt-sticking part and opening them in a sprue part. CONSTITUTION:The wax in a mold is melted with an autoclave, etc., by vertically standing the sprue rod with a holding part 6 downward. At this time, under a high temp. and pressurized state, the mold is rapidly heated from the outside and, at the same time, heated from the inside of the sprue rod because the central part of the sprue rod is hollow, and the wax in the flow-out passage is earlier and more quickly melted than that of the wax pattern. The molten wax flows out all at once because of its dead wt. of the wax at the time of dewaxing because the recessed grooves 2 are formed vertically. Therefore, the molten wax of the wax pattern can smoothly flow out without being narrowed with its outlet and dammed up.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sprue bar used for mounting a plurality of wax models in a tree shape in lost wax casting.

[0002]

2. Description of the Related Art A conventional sprue bar is disclosed in JP-A-59-9773.
As described in Japanese Patent Laid-Open No. 8, a metal cylindrical body having a large number of small holes and one end closed is used.

[0003]

In the conventional sprue bar, when the wax is melted (dewaxing), the wax flows out from the gaps corresponding to the thickness of the wax covered by the sprue bar and from the small holes formed in the cylinder. Was there. Since the small holes are made at right angles to the direction in which the wax flows down, in order for the wax to flow from the outside to the inside of the cylinder through the small holes, it must flow transversely to the direction in which the wax flows out. It was a structure. For this reason, the wax that has flowed at a right angle through the small hole from the middle of the cylinder will change the flow of the wax that flows down from above, or the wax that flows down from above will try to flow through the small hole. It acts as a weir for the wax, and blocks the flow of wax from the small holes. Furthermore, because of the resistance of wax passing through small holes, so-called pipe friction is large,
There is a problem that the wax elutes slowly during dewaxing, so that the wax thermally expands and the mold cracks or breaks.

The present invention solves the problems of the conventional sprue bar, and provides a sprue bar having a structure with small outflow resistance, which replaces the small hole for inflowing the melted wax, which is particularly indispensable. The purpose is to

[0005]

The present invention has been devised to reduce the resistance of the wax outflow passage at the time of dewaxing, and is characterized in that the shaft core of the sprue part and the welded part are characterized. And a concave groove is formed on the outer surface of the welded portion, and the concave groove is formed in the axial direction of the welded portion and opens at the sprue portion. It is in.

[0006]

When the wax in the mold is melted and dewaxed, the gripping portion is directed downward, and the wax is melted and discharged at a high temperature at a high temperature. At this time, the direction of the groove provided on the outer surface of the welded portion is formed perpendicularly to the sprue portion through which the wax flows out, and coincides with the direction in which gravity acts. It can be discharged at a stretch along the concave groove. Moreover, since the outflow passage through which the wax passes is a concave groove instead of the conventional small hole, the friction resistance is smaller than the pipe friction resistance.

[0007]

Embodiments will be described in detail with reference to FIGS.

FIG. 1 is a front view showing a sprue bar A made of metal. A plurality of wax models are welded to each other on a welded portion 1 in which a plurality of concave grooves 2 are engraved in the axial direction, which is the longitudinal direction. Is
The concave groove 2 is connected to an elongated hole 9 provided in a conical sprue part 4 that is continuously provided. The long hole 9 is provided on an extension of the concave groove 2 and opens inside the hollow sprue 4. Further, the sprue part 4 is provided with a hollow grip part 6 projecting in a direction opposite to the welding part 1, and a tip end thereof is formed with a convex part 7 for easy holding by hand during operation and easy hanging. Has been done.

FIG. 2 is a plan view of the sprue rod A, and FIG.
FIG. 3 is a sectional view taken along the line XX of FIG. The welded portion 1 is hollow so that the upper end is closed for weight saving, and the gripping portion 6 extends to the lower end of the welded portion and is fixed by the hollow portion, and penetrates the hollow portion of the sprue portion 4 for further stability. And is supported by a flange 5 provided at the lower end. The flange 5 is
As shown in FIG. 4, a gap is formed between the sprue portion 4 and the flow passage 10 for ensuring the flow of the wax.

FIG. 5 is a sectional view taken along the line YY of FIG. The concave groove 2 has a shape in which the width thereof is gradually increased outward. The material of the sprue bar is not limited to metal, and synthetic resin such as plastic that withstands the temperature during dewaxing may be used.

The sprue bar A constructed as described above is dipped in molten wax by holding the grip portion 6 and then pulled up to form the welded portion 1.
A wax coating is formed on the sprue part 4. At this time, it is important that both the concave groove 2 and the long hole 9 are dimensioned so as to be blocked with wax. The sprue bar A adheres the wax model after the wax coating is completed and the wax is solidified. After that, the slurry obtained by mixing the refractory powder and the solvent is welded to the welding part 1 and the sprue part 4.
The mold is formed by repeating the process of adhering even up to the side surface and further adhering the refractory material thereto several times.

Next, the holding part 6 is placed vertically with an autoclave or the like to stand vertically to melt the wax in the mold. At this time, the mold is rapidly heated from the outside under the condition of high temperature and pressure, and at the same time, it is also heated from the inside of the sprue bar because the center part of the sprue bar A is hollow. As a result, the wax in the outflow passage through which it melts melts faster and faster than the wax model.

Further, the melted wax flows out at once because the concave groove 2 is formed in the vertical direction during dewaxing, as is clear from FIG. Therefore, the melted wax of the wax model does not narrow the exit,
It can flow out very smoothly without being blocked.

FIG. 6 is a sectional view showing another embodiment,
A groove 29 continuous with the concave groove 22 is provided on the outer surface of the sprue portion 24, and opens at the lower portion of the sprue portion 24. This sprue bar B prevents the wasteful use of the wax because the wax does not enter the inside of the welded portion 21 and the sprue portion 24 at all when it is dipped in the molten wax when forming the wax coating on the outer surface. Is.

FIG. 7 is a partial cross-sectional view of the upper portion of the welded portion showing another embodiment. Above the welded portion 31, each concave groove 3 is formed.
Vent hole 33 penetrating inward of welded portion 31 at the tip of
The present invention prevents the negative pressure from being generated at the tip of the concave groove 32 in the initial stage of melting the wax, thereby further facilitating the outflow of the wax.

8 to 10 are sectional views showing other concave groove shapes. 8 and 9, the inner width of the concave groove is made wider than the outer width to increase the cross-sectional area of the outflow passage through which the wax flows, and FIG. 10 shows the protruding portion 4 when the entire welded portion is bent.
1 serves as a reinforcing member to improve the section modulus.

[0017]

Since the present invention is constructed as described above, the wax outflow time during dewaxing can be greatly shortened, and before the entire wax model is heated and expanded. The molten wax does not flow out rapidly and the mold is not cracked. Furthermore, the welded part is extremely lightweight,
Moreover, the sprue bar having a stable strength can be obtained even when it is bent by the weight of the wax or its own weight.

[Brief description of drawings]

1 is a front view of a sprue rod A. FIG.

2 is a plan view of the sprue bar A. FIG.

FIG. 3 is a sectional view taken along line XX of FIG.

4 is a bottom view of the sprue rod A. FIG.

FIG. 5 is a sectional view taken along the line YY.

FIG. 6 is a sectional view showing a sprue bar B according to another embodiment.

FIG. 7 is a partial cross-sectional view showing the upper side of a welded portion of another embodiment.

[Figure 8]

FIG. 9

FIG. 10 is a sectional view showing the shape of another concave groove.

[Explanation of symbols]

 1 ... ・ Welded portion 2 ・ ・ ・ Recessed groove 4 ・ ・ ・ ・ Gate portion 6 ・ ・ ・ ・ Gripping portion

Claims (1)

[Claims] 1. A sprue bar used for lost wax casting, comprising a columnar welded part for welding a plurality of wax models, a sprue part connected to one end of the welded part, and a grip part provided at the sprue part. The axis of the sprue part and the axis of the welding part are arranged coaxially, and a concave groove is formed on the outer surface of the welding part.
A sprue bar used for lost wax casting, in which the concave groove is formed in the axial direction of the welded portion and is open to the sprue portion.