JP4210745B2 - Investment precision casting mold dewaxing method and use thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention removes a wax model (the whole tree including the runner and the gate part) from the investment casting mold (hereinafter referred to as the investment mold). More specifically, the wax model in the investment mold is burned with a gas, liquid or solid powder as a fuel, or a flame such as a torch lamp with petroleum components. direct heating to rapidly flow out and collected, new investment which allows to prevent mold cracking frequently during dewaxing in hot water carried out subsequent to this, to produce a sound casting with high efficiency it relates to the dewaxing how the mold.
[0002]
Conventional method
In general, the investment mold manufacturing method involves first immersing a tree-shaped wax model having a runner and a spout attached to a product part in a slurry mainly composed of a binder and a refractory fine powder. Is immediately sprinkled with sand-like refractory particles (this operation is called sanding) to form a thin shell-like mold layer, which is dried and cured to produce one mold layer. The model wrapped with the mold layer is dipped in the slurry again, pulled up, and after sanding, the second mold layer is dried and cured. The process from the slurry immersion to the curing of the mold layer is usually repeated about 7 times to produce an investment mold.
[0003]
Conventional methods for dewaxing investment molds include: (a) a shock heat method in which a mold is inserted into a furnace heated to about 1000 ° C. and the wax model is burnt rapidly; (b) the mold is placed in an autoclave. Autoclave method for eluting wax model in an atmosphere of superheated steam at about 150 ° C. and 6-7 atm, (c) Hot water method for immersing mold in hot water heated to about 100 ° C. to elute the wax model Are known (see Patent Documents 1 to 4 and Non-Patent Documents 1 and 2).
[0004]
However, in the method (a), gas and black smoke are often generated due to the burning of wax, and the method has not been used from the viewpoint of environmental pollution. Although the method (b) is currently used for mass production, there is a drawback that the initial and running costs are increased due to the equipment cost of the autoclave and the large amount of energy consumption required for generating superheated steam. The method (c) has an advantage that the recovery rate of the wax is high, but there are problems that the time required for dewaxing is long and that the mold often breaks during the dewaxing. If the mold is largely cracked, it is discarded immediately, but even in the case of a small crack, defects such as casting (fins) are produced in the cast product, and the precision cast product is rejected or discarded. As described above, the above-described methods (a) to (c) are conventionally known as dewaxing methods for investment precision molds. However, these methods have the above-described problems, and the technical field In Japan, development of a new dewaxing method that can replace the above method has been requested.
[0005]
[Patent Document 1]
Japanese Patent Publication No.54-26204 [Patent Document 2]
Japanese Patent Laid-Open No. 7-47443 [Patent Document 3]
Japanese Patent Laid-Open No. 10-43835 [Patent Document 4]
JP-A-10-180408 [Non-Patent Document 1]
Japan Foundry Association: Casting Handbook, 4th revised edition, P1046 (Maruzen published 1986)
[Non-Patent Document 2]
Nishikori Tokuro, Gaiden: Precision casting, P35-36 (published by Nikkan Kogyo Shimbun, 1973)
[0006]
[Means for Solving the Problems]
In such a situation, the present inventor, in view of the above-mentioned prior art, can prevent pollution to the environment by recovering the wax model as a dewaxing method for the investment precision mold. As a result of intensive research with the goal of developing an economical dewaxing method that does not cause mold cracking, the time required for the process can be greatly reduced, using controlled heat from a burner or torch lamp, etc. Without melting the wax model, the wax component is directly discharged from the mold, and then the wax model remaining in the mold is melted and recovered by immersing the dewaxed mold in hot water. The inventors have found that the object can be achieved, and have completed the present invention.
In the present invention, by partially heating the wax model without rapidly burning, the liquefied wax can be discharged and recovered, and the dewaxing time can be significantly shortened compared to the hot water method. , A new dewaxing method that can prevent mold cracking that frequently occurs when a mold including the entire wax model is heated and discharged in hot water, and a molten metal is cast into the mold obtained by the method. An object of the present invention is to provide a method for producing a sound casting with high efficiency.
[0007]
[Means for Solving the Problems]
The present invention for solving the above-described problems comprises the following technical means.
(1) In the method of dewaxing an investment precision casting mold, a wax model (tree) of an investment precision casting mold is directly heated by a flame to liquefy the brazing component without burning it, and is discharged from the mold and dewaxed. The mold dewaxed by the method is immersed in hot water at about 100 ° C., so that the wax model remaining in the mold is melted and recovered, and the occurrence of mold cracks is prevented. A method for dewaxing investment precision casting molds.
( 2 ) In the manufacturing process of investment precision casting molds, the mold is tilted so that the exposed part of the wax model in the mold is exposed to the outside air from the horizontal direction to the downward direction, and gas, liquid or solid powder is used as fuel. The mold and / or one or both of the burner and the torch lamp are placed so that the flame and the temperature-controlled flame of the torch lamp with liquid fuel are applied directly from the sprue part of the wax model to the runner part and the product part sequentially. The investment according to (1 ) , wherein the wax component is liquefied without being burned while moving, and is discharged from the mold, collected in a container provided below the mold, and recycled as a model material again. Dewaxing method for precision casting molds.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in more detail.
In the present invention, due to the shape of the wax model (tree), burner, etc., the pouring gate side exposed to the outside air of the mold is turned sideways (clockwise hand at 3 o'clock) from downward (at 6 o'clock). Inclined to an appropriate angle, burner with a gas such as hydrocarbons, liquids such as petroleum components, or solid powders such as coal, or a flame such as a torch lamp that uses liquids such as petroleum components as fuel. By gradually heating from the portion to the runner portion and the product portion, the liquefied wax is discharged from the mold and collected in a container provided below the mold.
In the present invention, LPG gas (natural gas) and coal dry distillation gas can be preferably used as the fuel for the burner, but not limited thereto, combustible gas, liquid, and solid can be used. Their types and combinations are not limited. Further, as the fuel for the torch lamp, gasoline or kerosene can be preferably used. However, the present invention is not limited thereto, and a combustible liquid can be used, and the types and combinations thereof are not limited. Moreover, if it has a function similar to the said burner or a torch lamp, it can be used similarly.
[0009]
In the present invention, as many wax models as possible are allowed to flow out by putting a flame such as a burner or a torch lamp as deep as possible inside the mold. When the amount remaining in the mold is small (less than 5%), it can be sent to the next firing step as it is, and a small amount of wax components remaining in the mold can be burned and removed in the firing furnace. it can. However, when the amount of residual wax in the mold is relatively large (5% or more), the mold is previously placed in hot water at about 100 ° C. in order to reduce the generation of combustion gas and black smoke in the firing furnace. By immersing, the remaining wax component is melted and floated on the molten metal surface to be removed from the mold and collected.
In order to remove moisture, the mold dewaxed in hot water is preferably dried at about 200 to 300 ° C., and then sent to the next firing step, where the remaining wax component remains slightly (less than 1%). Is completely burned and removed in a firing furnace.
[0010]
Next, the present invention will be specifically described with reference to the drawings.
The most characteristic feature of the present invention is that, as shown in FIG. 1, an investment mold 4 including a wax model (tree) comprising a product portion 1, a runner portion 2 and a spout portion 3 is formed into a shape of a burner or torch lamp 5. By applying a flame such as a burner directly to the wax model while tilting the side of the gate from the side to the side where the wax is easy to flow out, liquefy and drain from the gate part to the runner part and product part sequentially. The wax component that has flowed out is efficiently recovered in the container 6 placed below the mold, and is recycled and used again as a wax model material . Subsequently, the dewaxed mold is immersed in hot water in the mold. Melt and collect the wax model remaining on the
[0011]
As the model material and mold material used in the present invention, commercially available products generally used are sufficient. The model material is not particularly limited as long as it is a material liquefied by a burner or the like in addition to the wax component. For example, a resin such as styrene resin or urea resin used as a disappearance model material can be used (see JP-A-11-19749, JP-A-2000-271701, JP-A-10-36552).
[0012]
[Action]
In the present invention, the wax component can be liquefied and discharged in a short time by directly applying a flame such as a burner to the wax model. This is because the heat conductivity of organic materials such as wax is as low as about 1/100 of that of metals and about 1/10 of that of ceramics. This is because the speed is high. In this way, the wax part, which occupies a large volume by a burner, etc., and the part of the runner, and then the wax model as much as possible to the product part are discharged in order to remove the wax in the hot water in the next process. Time can be greatly reduced.
[0013]
In addition, in the conventional hot water method in which the investment mold including the entire wax model is immersed in hot water, the thermal expansion coefficient of the wax model is about five times larger than that of the investment mold made of the surrounding ceramic. The amount of thermal expansion of the part and runner part in hot water increases, and as a result of strongly pushing the investment mold, it often causes mold cracking, but the method of the present invention removes most of the wax model beforehand with a burner or the like Then, even if the investment mold is immersed in hot water, mold cracking does not occur.
[0014]
【Example】
EXAMPLES Next, although this invention is demonstrated concretely based on an Example, this invention is not limited at all by the following Examples.
Example 1 (Reference Example)
The exposed part (pouring gate part) of the investment mold including a wax model (tree) with two water pump impeller models with a diameter of 100 mmΦ, a height of 70 mm, and a wax weight of 95 g is initially placed sideways (horizontal direction). The flame of the torch lamp that uses kerosene as fuel is applied to the runner part and the product part sequentially from the sprue part of the tree. During this time, the spout side of the mold is lowered from the horizontal direction (clockwise hand at 3 o'clock). The direction (same as 6 o'clock) was changed, and most (about 95%) of the wax component was recovered from the exposed portion in a container placed under the mold in about 10 minutes. In this case, 18Cr-8Ni cast stainless steel was cast into a mold in which the brazing component was completely burned and removed in the next firing furnace without dewaxing in hot water, and a sound product free from gas defects was obtained. It was. Conventionally, the dewaxing of the investment mold has been performed in hot water that requires a long time of 2 hours or more or in an expensive autoclave facility. However, the present invention significantly reduces the time and cost required for dewaxing ( 50% or less).
[0015]
Example 2
The exposed part of the investment mold including a wax model (tree) to which eight rocker arm models for automobile engines of 70 mm × 30 mm × thickness 20 mm and a wax weight of 11 g are attached, from the beginning diagonally downward (the short hand of the watch is at 4:30) The Bunsen-Burner flame, which uses LPG gas as fuel, is applied to the gate and runner of the tree, and about 80% of the wax model components are eluted in about 10 minutes. did. Since the wax of the thin product portion remained, the remaining wax component was melted by heating in hot water at 100 ° C. for about 10 minutes, and the solid content floating on the surface of the hot water was recovered. In this case, no mold cracking occurred (acceptance rate 100%). Conventionally, when an investment mold containing all of the wax model is dewaxed in hot water, about 50% of the mold is cracked and becomes unusable and discarded.
The investment mold dewaxed in about 99% in hot water was heated in a firing furnace at about 1000 ° C. to completely burn and remove the brazing component, and then cast spheroidal graphite cast iron to obtain a sound product.
[0016]
Example 3
The exposed part of the investment mold including the wax model (tree) to which six gas turbine blade models for aircraft engines of 80 mm x 30 mm x thickness 10 mm and wax weight 10 g are attached, initially in the lateral direction (clock hand 3 o'clock Place the flame of a portable burner fueled with isobutane gas on the gate, and tilt the mold slightly downward (5 o'clock) when applying flame to the runner. About 75% of the wax component was eluted in about 10 minutes and collected in a container. Since the wax remained in the complex and thin product portion, the remaining wax component was melted by heating in hot water at 100 ° C. for about 10 minutes, and the solid content floating on the hot water surface was recovered. Also in this case, no mold cracking occurred (pass rate 100%). Conventionally, when an investment mold containing all of the wax model is dewaxed in hot water, about 40% of the mold is cracked and discarded.
The investment mold, which has been dewaxed about 99% in hot water, was heated in a firing furnace at about 1000 ° C. to completely burn and remove the brazing component, and then 12Cr-2.5Ni-1.5Mo heat resistant steel was cast. Got a healthy product.
[0017]
Example 4
From the beginning, the exposed part of the investment mold including the wax model (tree) to which four bearing models for pneumatic equipment of 50mm x 50mm x height 40mm and wax weight 23g are attached is facing downward (clockwise hand is at 5 o'clock) The Bunsen-Burner flame, fueled with LPG gas, is sequentially applied from the gate to the runner, and about 85% of the wax components are eluted in about 10 minutes. It was collected. Since the wax remained in the thin product part, the remaining wax component was melted by heating in hot water at 100 ° C. for about 10 minutes, and the solid content floating on the hot water surface was recovered. Also in this case, no mold cracking occurred (pass rate 100%). Conventionally, when an investment mold containing all of the wax model is dewaxed in hot water, about 50% of the mold is cracked and discarded.
The investment mold, which had been dewaxed about 99% in hot water, was heated in a firing furnace at about 1000 ° C. to completely burn and remove the brazing component, and then cast high-strength brass to obtain a sound product.
[0018]
Example 5
The exposed part of the investment mold including the wax model (tree) with 12 optical microscope parts (mirror box) models of 20mm x 20mm x height 13mm and wax weight 3g is facing downwards from the beginning. The Bunsen-Burner flame, which uses LPG gas as fuel, is sequentially applied to the sprue part and the runner part, and about 80% of the wax component is eluted in about 10 minutes. Collected in a container. Since the wax remained in the complex and thin product portion, the remaining wax component was melted by heating in hot water at 100 ° C. for about 10 minutes, and the solid content floating on the hot water surface was recovered. Also in this case, no mold cracking occurred (pass rate 100%). Conventionally, when an investment mold containing all of the wax model is dewaxed in hot water, about 40% of the mold is cracked and discarded.
The investment mold dewaxed in about 99% in hot water was heated in a firing furnace at about 1050 ° C. to completely burn and remove the brazing component, and then cast an aluminum alloy to obtain a sound product.
[0019]
【The invention's effect】
As described above in detail, the present invention according to the dewaxing how investment precision casting mold, the present invention, by heating directly by such a burner the wax model (1) Investment in a mold, expensive (2) About half of the molds when dewaxing in hot water is performed in the normal case where the shape of the product is often complicated. (3) Use of the present invention promotes resource saving (recycling of wax) and energy saving (shortening of heating time), and as a result, In this case, a special effect is achieved in that the manufacturing cost of the medium-to-small volume product can be greatly reduced (about 30 to 50%).
[Brief description of the drawings]
FIG. 1 is a schematic diagram of the present invention in which an investment mold is directly heated with a burner or torch lamp to elute wax components and collect them in a container.
[Explanation of symbols]
1 Product part 2 Runway part 3 Spout part 4 Investment mold 5 Burner or torch lamp 6 Wax collection container

Claims (2)

An investment precision casting mold dewaxing method in which a wax model (tree) of an investment precision casting mold is directly heated with a flame to liquefy the wax components without burning, and then dewaxed and dewaxed. Investment precision casting characterized by melting the wax model remaining in the mold and preventing mold cracking by immersing the brazed mold in hot water of about 100 ° C Mold dewaxing method. In the manufacturing process of investment precision casting mold, burner or liquid using gas, liquid or solid powder as fuel by tilting the mold so that the gate part exposed to the outside air of the wax model in the mold is from sideways to downward While moving the mold and / or one or both of the burner and the torch lamp so that the flame controlled in size and temperature of the fuel torch is directly applied from the sprue part of the wax model to the runner part and the product part sequentially. The investment precision casting mold according to claim 1, wherein the wax component is liquefied without being burned to flow out of the mold, and is recovered in a container provided below the mold and recycled as a model material. How to remove wax.

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