JPS6186048A - Device for removing casting mold in investment casting method - Google Patents

Abstract

PURPOSE:To provide a titled removing device which removes successively and satisfactorily expendable patterns from the lower part by carrying and transferring casting molds contg. the expendable patterns into a shielding box while rotating said molds, irradiating microwaves thereto and raising successively the bottom end of a shielding part. CONSTITUTION:The casting molds 3 contg. the expendable patterns by an investment casting method are carried and transferred into the shielding box 1 while the molds are rotated by revolving shafts 7. The microwaves are irradiated through irradiation ports 4 of the box 1 into said box and the bottom end of the microwave shielding member 2 is successively raised. The expendable patterns are successively and successively heated from the lower part to melt and flow out. The casting molds contg. the patterns are thus satisfactorily removed and ejected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mold removal device for an investment casting method (precision casting method), and particularly to a mold removal device for an investment casting method using microwaves.

[Conventional technology]

To make a mold using the investment casting method, wax, paraffin, urea resin (urea resin),
Prepare one or more product models made from fugitive substances such as polystyrene that can be eluted by heat or water.
This is joined to a casting plan part made of the same material and serving as the runner part of the mold.

In this way, a large number of product models attached to a runner is called a tree. A mold is made by forming a coating layer on the surface of this tree using refractory slurry and refractory sand using a well-known method. Next, after sufficiently drying the ri-covered layer (mold) formed on the tree surface, the fugitive model is removed using heat or water, and the mold is removed. There are many types of demolding methods, including the autoclave demolding method that uses heated steam, and the heat 1# bombardment method that uses a high-temperature heating furnace. There is one.

The principle of microwave demolding is that microwaves act on fugitive substances, including dielectric materials, inside a mold made using a conventional method, generating heat, and the heat dissolves the fugitive substances. be. This method uses a relatively WIR device and can recover fugitive substances without degrading them, generates little gas when the model melts, and the gas generated is at room temperature and pressure, so it is easy to use. In addition to having the advantage of being yazui, the equipment is simple and compact, and the recovered fugitive substances do not deteriorate much, so they can be recycled.
There are also great cost advantages.

However, compared to the autoclave demolding method and the thermal shock method, this microwave demolding method has JBi! It has the disadvantage that the mold easily breaks during molding, making it particularly unsuitable for demolding a tree-like shape. One of the reasons for this is that the thermal output is often small, and at room temperature and pressure, the fugitive substance expands and cracks the outer mold as it gradually heats up. Another reason is that steam and gas generated by fugitive substances cannot be quickly extracted from the inside of the mold, and the mold cracks due to the pressure of these steam and gas.

To prevent mold cracks caused by the causes mentioned above,
When designing the casting method, it was necessary to consider the shape and wall thickness so that the feeder in the investment casting method would be melted first, then the runner, the head, and then the product model. .

However, in many cases, the way of elution differs depending on the shape of the runner and product model, and it takes many tests and trial and error to remove everything from the mold in a healthy state. For this reason, demolding using microwaves requires a highly skilled technique and requires a great deal of time and effort, so its use has been limited.

Therefore, the present applicant solved the problem of mold cracking that occurs in the demolding method using microwaves by changing the microwave irradiation point of the fugitive substance in the mold over time, without relying on the design of the casting method. In order to solve the problem by causing the elution of the tree to occur quickly, a mold containing a fugitive substance to be demolded is placed on a table, the mold is covered with a microwave shield, and the mold is placed between the shield and the table. He proposed a method of moving one or both of them and irradiating them with microwaves (Special Publication No. 59-5382, Special Publication No. 59-53
No. 83).

[Problem that the invention seeks to solve]

The above-mentioned Special Publication No. 59-5382 and Special Publication No. 59-538
According to No. 3, it has various advantages over the conventional autoclave demolding method or thermal shock method as described in the specification.

However, although this method has no problems when used in hatch processing, it has the problem that it cannot be used for mass production.

The present invention has been made to solve the problems of the prior art described above, and the technical problem of the present invention is to enable continuous demolding.

[Means for solving problems]

This technical problem is achieved by a mold removal device in the following investment casting method.

That is, the mold forming apparatus in the investment casting method of the present invention carries in and out a mold containing a fugitive model to be demolded, and also performs demolding using microwaves between the loading and unloading of the mold. A shield box equipped with a microwave irradiation port for heating, and a shield box installed inside this shield box,
A microwave shielding member whose lower end of the shield rises along the mold transport direction and whose shielding area gradually decreases, a turntable on which the mold is rotatably mounted, and the turntable is moved in the mold transport direction. The invention is characterized in that it has a driving means for driving.

[Effect]

According to the mold demolding device for the investment casting method of the present invention, the mold placed on the rotating turntable is irradiated with microwaves and molded while the mold is being transported within the shield box.

At this time, since the microwave shielding member is formed so that the lower end of the shielding gradually or stepwise rises in the conveying direction of the mold, the portion of the mold that is exposed from the microwave shielding member as it is conveyed. The fugitive model in the mold increases and is exposed in the order in which it is melted and removed from the feeder mouth, runner, head, and product in order at almost maximum efficiency.

〔Effect of the invention〕

As described above, according to the mold removing device in the investment casting method of the present invention, the following effects are achieved.

(a) As the mold is transported through the shield box, the microwave irradiation area of the mold increases, and the fugitive models in the mold are sequentially eluted from below.

Therefore, simply by transporting the mold inside the shield box while irradiating it with microwaves, the fugitive model is automatically and efficiently eluted, allowing continuous production and mass production.

(b) Since local non-uniformity of the electric field density acting on the mold does not occur, the fugitive model melts smoothly out of the mold at approximately the same speed in the feeder mouth, runner, head, and product parts. comes out.

Therefore, no excessive force is applied to the mold, and no cracks or the like occur. Furthermore, the deterioration of the disappearing model is minimal, making it easy to reuse.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Here, FIG. 1 is a schematic configuration diagram showing a mold removing device in an investment casting method according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line II-n in FIG. 1.

In the figure, 1 is a shield box with a rectangular cross section, and is in the shape of an elongated tunnel. A microwave shielding member 2 having a U-shaped cross section is attached to the upper wall surface of the shielding box l with its opening facing downward.

This microwave shielding member 2 is provided to extend in the longitudinal direction inside the shield box 1, and covers the mold 3 along the transport direction of the mold 3 (direction of arrow A in FIG. 1).
The lower end of the mold 3 becomes higher in stages, and the area covering the mold 3 gradually decreases. Also, shield box l
Microwave irradiation ports 4 are installed at equal intervals in the longitudinal direction on the side of the shield box 1, and elongated holes 5 are formed in the bottom of the shield box 1 in the longitudinal direction.

6 is a turntable made of a microwave shielding material, and the mold 3 is placed on this turntable 6. This turntable 6 is supported by a rotating shaft 7, and the rotating shaft 7 is rotated by a drive means (not shown) and moved in the conveying direction of the mold 3 while being guided by a hole 5 provided at the bottom of the shield box l. do.

The mold 3 containing the fugitive model placed on the turntable 6 has the configuration shown in FIG. 2.

In FIG. 2, 8 is a tree (disappearing model) formed of a dielectric material that absorbs microwaves and generates heat, and a large number of product models 9 are passed through the head 10 to the runner section II A feeder opening 12 is attached to one end of the runner 11. A mold 3 made of a microwave-transparent refractory material is formed around this disappearing model 8.

The mold 3 containing the fugitive model 8 is placed on the turntable 6 provided in the shield box 1 with the feeder mouth 12 facing down.

Next, the operation will be explained.

First, the mold 3 containing the fugitive model 8 is placed on the turntable 6 with the riser mouth 11 facing down, and then the mold 3 is placed one after another at regular intervals into the shield box 1 while rotating the rotary shaft 7.
be brought inside. At the same time, microwaves are irradiated toward the mold 3 from the microwave irradiation port 4 inside the shield box l.

The mold 3 carried into the shield box 1 is partially shielded by the microwave shielding member 2, and transported in the direction of arrow A in FIG. 1 while being irradiated with microwaves. At this time, immediately after being carried into the shield box (X in Figure 1).

2), except for the feeder port 12 of the fugitive model 8, the other parts are shielded by the microwave shielding member 2, so only the feeder port gr<r2 absorbs microwaves and generates heat. Elute. Subsequently, as the mold 3 is conveyed, the area receiving concentrated microwaves expands, and melt is sequentially emitted from the feeder opening 12 to the runner 11, the head 10, and the product model 9.

Then, when approaching the final end of the shield box 1 (area Xi in FIG. 1), the entire mold 3 is no longer covered with the microwave shielding member 2, and the top end of the fugitive model 8 inside the mold 3 disappears. The microwave is absorbed and the elution is completed.

In this example, a microwave with an output of 2450 MHz and 5 KW was used, and 1.2 kg of urea resin was used as the disappearing model, which completely disappeared in about 12 minutes.

Although not shown, the melted fugitive substance may be removed by, for example, providing holes or grooves in the part of the turntable 6 that contacts the feeder port 12, or making the rotating shaft 7 hollow. 7 may be taken out to the outside.

As is clear from the above, the demolding device 1 of the actual HFI-example
The area of the microwave shielding part that covers the mold is formed so that it gradually decreases as the mold progresses, so just by passing the mold containing the evanescent model through the shield box, it will disappear. Since the model material can be eluted sequentially from the bottom, the model material that has been eluted can smoothly flow downward. For this reason, gas does not fill the mold and the mold is not cracked by the pressure, and the microwave energy is gradually absorbed by the fugitive model, so the mold can be molded before the thermal expansion of the fugitive model material increases. It can be melted from. Therefore, cracks in the mold do not occur.

Furthermore, according to the demolding device of this embodiment, it is only necessary to transport the mold containing the fugitive model inside the shield box while irradiating microwaves, so unlike the conventional method, the mold can be continuously molded. Compatible with mass production.

Therefore, productivity is greatly improved.

Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and includes various embodiments within the scope of the claims. .

For example, in the examples, the conveyance speed of the mold is assumed to be approximately constant, but when eluating thick parts such as the sprue or the model body of a fugitive model, the movement speed may be slowed down, etc.
The movement may be performed discontinuously, or the reduction rate of the shielding surface 8!1 of the microwave shielding member may be changed.

Further, in the embodiment, the rate of decrease in the shielding area of the microwave shielding member was changed in stages, but the rate of decrease in the shielding area of the microwave shielding member may be changed gradually as shown in FIG.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing a mold demolding device in an investment casting method according to an embodiment of the present invention, Fig. 2 is a sectional view taken along line nn of Fig. 1, and Fig. 3 is used in the present invention. FIG. 3 is a schematic configuration diagram showing another example of a microwave shielding member. 1...-Shield box 2--Microwave shielding member 3--Mold 4--Microwave irradiation port 5--111 hole 6--・Turntable 7---Rotation shaft 8---Disappearance model (tree) 9---Product model 10-11~---Head 1 i---/A road part 12...・・− riser mouth part

Claims (1)

[Claims] (1) A shield box equipped with a microwave irradiation port for loading and unloading a mold containing a fugitive model to be demolded, and for demolding using microwaves during loading and unloading of the mold. a microwave shielding member that is installed in the shield box and whose lower end of the shield rises along the conveying direction of the mold and whose shielding area gradually decreases; and a turntable on which the mold is rotatably mounted. 1. A mold demolding device for an investment casting method, comprising: a drive means for moving the turntable in a mold transport direction.