JP2794988B2 - Inspection method in the mold for precision casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision casting method (wax method) such as a lost wax method, and more particularly, to inspecting the inside of a precision casting mold used for casting, for example, a product having a hollow portion. Inspection method.

[0002]

2. Description of the Related Art A wax casting method has advantages such as easy mass production of a complicated three-dimensional shape, high dimensional accuracy and few internal defects. Is widely used in the manufacture of mechanical parts that are difficult to manufacture by machining.

[0003] In mechanical parts such as turbine blades cast by the above-mentioned brazing method, hollow parts may be provided inside the parts due to demands for increased cooling capacity and weight reduction. In the case where the hollow portion is manufactured by the above-mentioned wax casting method, a method of performing casting by embedding a ceramic core in a molded product formed by a wax or the like is conventionally known. Steps will be briefly described.

In order to cast a thin-walled hollow part by a wax casting method, first, a core is formed corresponding to the shape of the hollow part of the part to be cast using ceramics such as fused silica as a raw material.

[0005] Next, the core is incorporated into a mold having a void formed therein having the same shape as the outer surface contour of the part to be cast. Thereafter, a molten product such as a brazing filler metal is injected into the space through a flow path formed in the mold to form a molded product in which the core is embedded (molding step).

A plurality of molded articles formed as described above are assembled in a tree shape, and a ceramic layer is coated around the assembly by an investment method or a ceramic shell molding method to form a model (coating step). Then, the molded product embedded in the model is eluted leaving the above-mentioned core (dewaxing step).
The organic component remaining in the inside is removed by firing at a temperature of 00 to 1200 ° C., and thereafter, the molten metal is poured into the void formed in the model (mold) by the elution of the molded product (casting step).

After pouring the molten metal, the mold is dropped after cooling of the molten metal, and a cast tree connected in a dendritic shape is taken out. The cast tree is cut off, so that the outer contour is the same as a predetermined part shape. Obtain a cast product in which a core is cast. Then, the casting is immersed in an alkaline solution to dissolve the core, thereby forming a hollow portion having a predetermined shape in the casting.

[0008]

However, when a casting having a hollow portion is cast as described above, the ceramic core is brittle and has low strength.
The core was sometimes broken by the impact received during the manufacturing process. And, in this case, the angle-cast product was rejected, and the yield was reduced. In particular, once the coating is applied to the molded product obtained by insert molding the core, the core is not visible from the outside, so that the core is broken until the cast product is inspected by X-ray inspection or the like after the casting. It is difficult to determine whether the cause is in the casting process or in the previous process, such as the dewaxing process. Therefore, it is easy to take appropriate measures to prevent breakage of the core. Was not.

The present invention has been made in view of the above circumstances, and an object of the present invention is to enable easy and reliable inspection of the inside of a mold before a casting step. When is inserted, it is possible to smoothly check whether the core is broken or not, and to provide an inspection method in the precision casting mold that makes it easy to identify the cause of the core breakage. is there.

[0010]

In order to achieve the above-mentioned object, the present invention is to form a molded article having the same shape as a product, apply a coating to the molded article, and elute the molded article. An inspection method for inspecting the inside of a precision casting mold that has been made, wherein an inspection window member is connected to an inspection target portion of the molded product, and at the time of the coating, the tip of the inspection window member is exposed. After being in the state, the inspection window member is eluted together with the molded product to form an inspection window, and the state inside the mold is inspected using the inspection window.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In this embodiment, a turbine blade will be described, but it goes without saying that the present invention is not limited to this.

FIG. 1 shows a molded article 2 obtained by inserting a ceramic core 1 into a cavity (cavity) in an injection mold, injecting molten wax (wax), and molding (insert molding). . Then, a cylindrical inspection window member 3 made of the same material as the molded product 2 or a material equivalent thereto is adhered to a portion of the molded product 2 to be inspected (a portion where the core 1 is easily broken). . Further, a disk-shaped metal plate 4 is bonded to the tip surface of the inspection window member 3. A rod 5 is fixed to the center of the metal plate 4 (see FIGS. 2 and 3). The metal plate 4 to which the rod 5 is fixed is
May be bonded to the molded product 2 in a state where the rod-shaped body 5 is inserted into the round bar-shaped inspection window member 3 in advance. In this case, the metal plate 4 and the round bar-shaped inspection window member 3 are used.
Are firmly connected to each other, so that they are easy to handle in handling or in a bonding step with a molded product and a coating step.

In this manner, as shown in FIG. 1, in a state where the inspection window member 3 and the metal plate 4 are bonded to the molded product 2 including the core 1, the coating process is started. That is,
The model 6 is formed by repeating the operation of attaching the binder slurry to the outer surface of the molded article 2 and dusting the refractory particles. At this time, as shown in FIG. 2, the surface of the metal plate 4 is exposed by wiping off the attached slurry and refractory particles every time coating is performed.

Next, after the model 6 is dried, the process proceeds to a dewaxing step, and the molded article 2 embedded in the model 6 is
Elution is carried out leaving the core 1. At this time, the inspection window member 3
Is also eluted, and the metal plate 4 is also removed, so that the inspection window 6a is formed in the model 6 (see FIG. 3).

Then, by inspecting the inside of the model 6 using the inspection window 6a formed in the model 6, it is inspected whether the core 1 is broken (or the surface is peeled). In this case, if breakage (peeling) of the core 1 is confirmed,
It can be seen that the cause of breakage (peeling) of the core 1 is due to the conditions prior to the casting process, particularly the dewaxing process.
What is necessary is to clarify the cause of the problem and take countermeasures.
If the breakage (peeling) of the core 1 is not confirmed, it is understood that the breakage (peeling) of the core 1 is in the condition of the casting process. Can be.

In addition to visually inspecting the inside of the model 6 from the inspection window 6a, a fiber scope or the like may be inserted into the inside to inspect the inner surface of the model 6.

[0017]

As described above, the present invention provides a precision casting mold produced by molding a molded article having the same shape as a product, coating the molded article, and eluted the molded article. An inspection method for inspecting the inside of a molded product, wherein an inspection window member is connected to an inspection target portion of the molded product, and the coating window is exposed after exposing the tip of the inspection window member. The inspection window is formed by dissolving the inspection window member together with the molded product, and the state of the interior of the mold is inspected by using the inspection window, so that the interior of the mold is removed before the casting process. In particular, when the core is inserted into the mold, it is possible to smoothly check whether the core is broken, and to check for damage to the core. It is easy to identify the cause and take measures.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a molded article assembling step showing one embodiment of the present invention.

FIG. 2 is an explanatory view of a coating step.

FIG. 3 is an explanatory view after a dewaxing step.

[Explanation of symbols]

 2 Molded product 3 Inspection window member 6 Model (mold) 6a Inspection window

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Fumie Nishiwaki 1230 Kamideya, Okegawa-shi, Saitama Mitsubishi Materials Corporation Okegawa Second Works (58) Field surveyed (Int. Cl. ⁶ , DB name) B22C 9/04 B22C 9/00

Claims (1)

(57) [Claims] 1. An inspection method for molding a molded article having the same shape as a product, applying a coating to the molded article, and then inspecting the inside of a precision casting mold manufactured by dissolving the molded article. Connecting an inspection window member to an inspection target portion of the molded article, and leaving the tip of the inspection window member exposed at the time of the coating, and then, together with the molded article, the inspection window member. A method for inspecting the inside of a mold for precision casting, wherein an inspection window is formed by dissolving the resin.