JPS62101349A - Investment casting method and device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in investment casting methods and apparatus.

[Conventional technology and problems]

Investments of the old style (investment sinking process) use the first molds that allow the reproduction of multiple disposable conventional brazing filler metal patterns. Conventionally, multiple wax models representing the product to be cast are attached to wax runners by gates to form model clusters. The model clusters are then coated one or more times with a refractory material. or molded around the wax model (encased in a plaster mold). Following curing of the material making up the seven els around the model and runners, the disposable material is removed leaving a completely empty deck cavity and the runners are also removed. Next, the empty shell is filled with molten metal and a predetermined product is cast.

Various proposals have been made in the art to minimize the use of wax in runners. As is well known, the wax runner used in this method requires a considerable amount of material, and the removal of the wax material forming the runner or sprue requires heat for its removal. It takes an amount of energy fc.

The use of solid waxes not only requires ancillary consumption of energy but also requires a time period on the order of 6 to 40 minutes or more.
It takes. Of course, it is desirable to minimize the time and energy required.

Additionally, wax runners or sprues present a 'weak ling' in investment casting technology.

It is therefore known that mold cracks occur when the mold expands while being heated for removal of the solder sprue. It is of course desirable that this too be avoided.

The most recent problem with wax sprues is their weakness. Manufacturing automation is limited by the inherent weakness of wax sprues. The speed at which the model cluster is rotated in the refractory material is therefore limited by the inherent strength of the wax runner.

It is known in the art from US Pat. No. 3,177,537 to use metal runners instead of wax runners. The metal runner is coated with a thin layer of wax to allow the attachment of the model to it.

The use of metal runners reduces the amount of brazing material used and furthermore, the metal runners are reused with minimal time and energy.

The thin wax-coated metal runners are first removed from the model cluster by filling the runners with a heat transfer material, such as oil, according to the teachings of the aforementioned US patents. This melts the thin wax coating which is then easily removed from the metal runner beam 2 star and reused to form a new cluster, while the remainder of the model cluster p1&: is removed in the usual manner and wax r-) and remove the model.

However, the use of hot oil or other heat transfer materials is dangerous, l) and time consuming. Furthermore, the oil is selectively heated, sent to and then removed from the runner.

It is an object of the present invention to provide a new method of heating metal runners that is simpler and more efficient than known methods.

It is also an object of the invention to provide a method for carrying out the aforementioned method.

[Means for solving problems]

The above problem can be solved by the present invention, in which a hollow metal runner coated with wax is coated with solder darts to be cast, a shell is formed inside and outside the hollow metal runner, and the metal runner is heated to a temperature that sufficiently melts the wax. The problem is solved by an investment casting process that includes induction heating and removing the metal runner to leave a runner device for introducing molten metal into the runner to minimize the amount of metal used in the runner.

Furthermore, the above-mentioned problem arises in the investment casting method in which a cluster of wax models of the product to be cast is attached to a runner. Coating the interior and exterior of the runner with a mold-forming material and induction heating to a temperature sufficient to melt the wax coating and allow removal of the metal runner and leave the runner for introduction of molten metal material, The solution is an investment casting process that involves a process that minimizes the use of metal materials.

According to the invention, the metal runner is preferably tubular and heated with an induction coil. The induction coil is placed in close proximity to the metal runner and the coil is actuated to rapidly heat the metal runner, melting the wax coating and allowing the runner to be quickly, easily and cleanly removed from the model cluster for reuse. .

Furthermore, the above problem is solved according to the invention by providing a cylindrical metal runner having a first open end and a second opposite end having at least one drain/port, and a wax coating on the inner and outer surfaces of the metal runner. and at least one wax pattern of a cast article attached to the exterior of the braze-coated metal runner with a braze gate, and a coating of mold-forming material around the interior and exterior of the metal runner.
The problem is solved by a built-in device. The apparatus includes induction heating means proximate to the metal runner and means for fully operating the induction heating means to melt the wax on the metal runner from the clusters. In a preferred embodiment of the invention, the metal runner is aluminum or an aluminum alloy material. Accordingly, aluminum and/or its alloys have many desirable properties necessary for the practice of this invention.

The induction heating device may be any conventional induction coil and preferably uses high frequencies. Generally 60 to io, ooo
Hertz frequencies are a preferred range. It is preferable to arrange the induction coil as close to the tubular metal runner as possible to increase the coupling efficiency.

Furthermore, the tubular runner is preferably of relatively thin material to provide rapid heating. It has been found that metal runners can be removed in less than 10 seconds while carrying out the method described above.

In a preferred embodiment of the present invention, the thickness of the metal runner is 0.04
0rb-ire 0.150 I>+<tJori, -Rei,
g; Rime Jn> O As mentioned above, it is preferable to be as thin as possible, and the limiting factor is typically deformation as a result of mechanical stress or external heating. [Example] The present invention will be described in detail below based on the drawings.

In the Investmen HQ manufacturing method of the present invention, a plurality of wax models l
is attached to a thin wax coating 3 applied to a tubular metal runner 5. Attach model l with solder gate 7.

Model l is the product to be cast.

The tubular metal runner is preferably a thin-walled cylindrical tube having an open end 15 and a closed end, referred to as the sprue end 13. The sprue end has two 19K through holes. The runner 5 is made of copper, copper and aluminum alloy or any other suitable metal material known to those skilled in the art.

The assembled model 11, runner 5, and dart 7 constitute a model cluster as shown in FIG.

The model cluster is then immersed in a slurry to form a shell of molding material as shown in FIG. Molding material shell 17
can be coated by dipping into ceramic slurry glue 2 Star, and then a vibrating screen can be applied by stuffing refractory granules onto the model cluster coating surface of the slurry coat by dipping in a fluidized bed.

The dipping and moving process is repeated until the shell reaches a predetermined thickness.

The coated model cluster 15 with the drying shell 17 is then supported by suitable means within the induction coil 21 as shown in FIG. Cluster 15 is steel handle Rondo 23! It is operated as follows. Generally, the cluster 15 is supported such that the longitudinal axis of its tubular runner and the central longitudinal axis of the induction coil 21 coincide. A current is then applied from the power source via the induction coil 21 to conductively heat the tubular metal runner with suitable control means. When the runner 5 is heated, a thin wax coating 3 on the runner surface
melts and leaves the runner from the lower tunnel 17 through the sprue end 13. The runner 5 has a shell 17 as shown in FIG.
You can easily remove the bedding and reuse the runner. Next, the remaining wax in the model is separately dewaxed, and the wax model and dirt are removed from the shell 17, and then 7 ells are filled with molten metal and the product is cast.

The use of tubular metal runners and induction heating to heat the runner and melt the wax coating is an efficient and easy way to remove the runner from a beam 2 star and reuse it.

It will be understood that the above examples are for illustration only and changes and modifications may be made without departing from the spirit and scope of the invention.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of one model cluster of the present invention, FIG. 2 is a cross-sectional view of the model cluster after coating with synthetic material, and FIG. 3 is a cross-sectional view of the model cluster placed within an induction heating coil. The coated pattern is shown in a cross-sectional view of the cluster.
FIG. 4 is a cross-sectional view showing the removal of metal runners from the model cluster. l... Wax model (pattern), 3... Wax coating, 5... Metal runner, 7... Wax gate, 1
3... sprue end, 15... cluster, 17... shell, 19... through hole. Margin below

Claims (1)

[Scope of Claims] 1. Prepare a model cluster for forming a plurality of wax models of a cast product in which a wax gate is attached to a wax coated hollow metal runner, coat the model cluster with a mold forming material, and apply a wax pattern to the hollow metal runner. A shell is formed on the inside and outside, the metal runner is induction heated to a temperature that sufficiently melts the solder, and the metal runner is removed to leave a runner device for introducing molten metal into the mold inside the runner. An investment casting method that involves a process that minimizes the amount of metal used in 2. The method according to claim 1, wherein the step of inductively heating the metal runner includes disposing an induction heating coil inside the coated metal runner. 3. The method of claim 1, wherein the metal runner is cylindrical in shape with one open end and the opposite end has at least one drain port. 4. The current frequency to the induction heating coil is 60 hertz and 10
,000 hertz. 5. In the investment casting method in which a cluster of wax models of the product to be cast is attached to a runner, a hollow thin-walled metal runner having a wax coating on its inner and outer surfaces is prepared, the wax model is attached to the metal runner, and the inside of the metal runner is and externally coated with a mold-forming material, and induction heated to a temperature sufficient to melt the solder coating and permit removal of the metal runner and leave an introduction runner for the molten metal material; An investment manufacturing method that includes processes that minimize use. 6. The method of claim 5, wherein the metal runner has a cylindrical shape with one end open and the opposite end has at least one drain port. 7. a cylindrical metal runner having a first open end and a second opposite end having at least one drain port; a wax coating on the inner and outer surfaces of the metal runner; and a wax coating on the exterior of the wax coated metal runner. An investment casting apparatus having at least one wax model of a cast article attached with a gate and a coating of mold-forming material around the interior and exterior of the metal runner.