JPS59166347A - Molding method in pack casting method - Google Patents

Abstract

PURPOSE:To obtain a casting mold having good packability of a heat resistant granular material and having excellent strength in a pack casting method using a consumable casting pattern by embedding a pattern in the heat resistant granular material in a fluid state and evacuating the inside of the mold after oscillating the same. CONSTITUTION:A molding flask 1 disposed with a porous pipe 2 for pressurization and a porous pipe 3 for evacuation in a bottom part is prepd. and a prescribed amt. of molding sand 4 which is a heat resistant granular material is packed therein. The porous pipe of which the perforated part is covered with a finely meshed metallic screen is used. After the sand 4 is fluidized by opening a pressurizing source 4, a pattern 8 manufactured with a product part 6 of a circular shape having two flange parts 5 in proximity to each other together with a runner 7, etc. by using foamed polystyrene as shown in the figure is inserted and embedded in the flask 1. An oscillating table 9 is oscillated to oscillate the flask 1 after stopping the pressurization. The opening part of the flask 1 is then covered with a vinyl material which is a combustible material, then the inside of the flask 1 is evacuated through the pipe 3 and a melt of Al, etc. is charged through a sprue 11. Casting is thus accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding method in a filling casting method using a fugitive model.

A filling casting method is known in which a fugitive model such as expanded polystyrene is buried in #-shaped sand, which is a heat-resistant granular material, and molten metal is directly poured into the mold without removing the model from the molding sand. This filling casting method (1) eliminates the need to divide the mold into H-type and 'F-type and remove the models, (2) eliminates the need to use a core, and (3) manufactures products because no flash is generated. It has a characteristic of 9 etc. that can significantly reduce the number of man-hours, and by taking advantage of this characteristic, it is widely used in the production of individual castings and mass-produced castings.

In such a filling casting method, once the model is made.

In principle, castings of any shape can be manufactured, but unless the model is sufficiently held in place by the mold, it is difficult to manufacture accurate castings. For this reason,
The question is whether the molding method is good or bad.

The following methods are available as molding methods in the filling casting method.

(6) A method in which a fugitive model is placed in a casting flask in advance and then filled with molding sand containing a binder. in this way.

Molding sand has poor fluidity because it contains a binder.

Therefore, there was a problem with the filling property, and the molding work was accompanied by great difficulty. This method also allows for the recovery of molds.

Recycled paper also required extra man-hours and costs, resulting in poor yields.

In order to solve this problem, there is a method of vacuum molding using CB) molding sand that does not contain a binder (hereinafter referred to as non-caking sand). Although this method improves the filling properties compared to the case (c) above, it is not sufficient and has the disadvantage that the strength of the mold is weak.

Historically, as an improvement on +B), as shown in Figure 5, (Q
There is a molding method in which pressure and vacuum tanks are provided at the end of the casting flask, non-caking sand is made to flow under pressure, and after the model is inserted, it is fixed under reduced pressure. According to this method, the filling properties of molding sand.

Although the mold strength is better than (B), when manufacturing complex-shaped castings that require a core using a casting method other than the filling casting method, it is recommended to fill the part corresponding to the core with molding sand. It is not easy to do so, and the strength of the complexly shaped part is not sufficient to withstand the gas generated by the combustion of expanded polystyrene.

The present invention was made to solve such problems,
The object of the present invention is to provide a molding method in a filling casting method that has good filling properties and excellent mold strength.

According to the molding method in the filling casting method according to the present invention, the lower part of the flask is equipped with a pressurizing means and an M pressure hand grip,
This is achieved by inserting and burying the model into the flask with the heat-resistant granules fluidized by pressurizing means, then applying vibration, covering the opening of the flask, and solidifying the mold by reducing the pressure. let

The feature of the present invention over the prior art is that a vibration process is added to the molding process.

In the present invention, the pressurizing means and the depressurizing means may be provided as pressurizing and depressurizing tanks as shown in FIG. 5, or may be provided directly within the mold. In the case of the latter, pressurized air or vacuum pressure is blown onto the #4 thermal particles.

This is more direct and more effective than when pressurization and depressurization tanks are provided separately. In particular, when reducing the pressure, assimilation of the reduced pressure in the mold occurs instantaneously, so it is desirable to apply a large reduced pressure at the same time as the start of reducing the pressure.In this respect, it is preferable to install the pressure reducing means directly inside the mold. .

In the case of direct installation, the pressurizing means consists of two pressurizing sources, such as a pressurizing pump, and a porous pipe connected to the pressurizing source and blowing out compressed air.

The pressure reducing means is composed of a pressure reducing device such as a vacuum pump, and a perforated pipe connected to an interpressure source and having a number of holes for intake.

Both the pressure means and the pressure reduction means have a pressure of 1l1.
4. Disposed over the entire bottom of the mold so as to act evenly on the thermal granules. Also, the pores of a porous pipe.

The diameter must be large enough to prevent heat-resistant particles from entering. In addition, when the pore diameter of the porous pipe is large.

Eye 4. By covering with III mesh, clogging and mixing of heat-resistant particles can be prevented.

In the present invention, the filling properties of the heat-resistant granules can be significantly improved by applying vibration. In particular, it is excellent for filling thin-walled parts and complex-shaped parts with heat-resistant granules, which not only improves filling performance compared to conventional methods, but also increases the packing density of the entire mold and increases the strength of the mold.

It is desirable that this vibration be applied in the direction in which the thin-walled portions and complex-shaped portions are sufficiently filled with heat-resistant granules while the model is buried. However, it is usually sufficient to add it from either the left or right direction. The magnitude of the vibration applied, the cycle,
The application time should be determined as appropriate, taking into account the size, shape, etc. of the model.

In the present invention, foamed polystyrene and foamed polyethylene are commonly used as model materials.

Foamed polyurethane etc. can also be used. As the heat-resistant granules, molding sand, shot, etc. can be used.

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

Example Figure 1 is a sectional view showing the pressure reduction process in the present invention, Figure 2 is a cross-sectional view showing the pressure reduction process in the present invention.
The figure is the I+-1 diagram of FIG. 1 (lfi L, heat-resistant granules are excluded), and FIG. 3 is a front view showing the perforated tube used in the present invention.

First, a flask 1 is prepared in which a porous tube for pressurization 2 and a porous tube for depressurization 3 are arranged at the bottom of the flask as shown in FIG.

Inside this casting flask 1, a predetermined amount of molding sand 4, which is a heat-resistant granular material, is used.
was loaded. The perforated tube is as shown in Figure 3.

The porous portion 5 is covered with a fine wire mesh.

Next, a pressure source 9 (not shown) was opened, and the molding sand 4 was made to flow. Thereafter, as shown in FIG.
Model 8 made of Totomo Banko foamed polystyrene is placed in casting flask 1.
It was inserted and buried inside.

After the pressurization was stopped, the vibration table 9 was vibrated to apply vibration to the flask 1. The vibration conditions at this time were: amplitude 5 mm, cycle 3500 rpm + vibration application time 15 minutes.

The vibration acceleration was 0.45G.

Then - the opening of the frame 1 is made of combustible material.

covered with vinyl. In this state, a vacuum pump (not shown) was operated to reduce the pressure inside the flask 1 via the pressure reducing porous pipe 3.

During this period, aluminum melt was poured from the sprue 11 while maintaining the pressure to cast a product with a lift channel and the like. After breaking out the molds, weir folding was performed to obtain a product with a predetermined shape.

When observing the product, it was confirmed that not only the cylindrical body but also the flange part was made with good precision, molding sand was sufficiently filled between the flange parts, and the strength was sufficient.

As described below, according to the present invention, by adding a vibration process to the conventional process, the heat-resistant granules can be filled into parts that were not sufficiently filled with the heat-resistant granules in the past, and the whole As the filling density increased, it became possible to obtain sound castings with complex shapes using the filling casting method.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing the pressure reduction process in the present invention, Figure 2
The figures are the ]-υ diagram of FIG. 1, FIG. 3 is a front view showing the perforated tube used in the present invention, and FIGS. 4 and 5 are sectional views showing the conventional method. l...Casting flask 2...Porous pipe for pressurization 3...Porous pipe for pressure reduction 4...Molding sand (#4 thermal granules) 5...Flange part 6...Product Part 7...Door part 8...Model 9...Vibration table 10...Vinyl 11...Gate part 12...Pressure/depressurization Tank 13... Mold application person Toyota Motor Corporation

Claims (1)

[Claims] (1) +# A molding method in the filling casting method in which a fugitive model is inserted into a flask equipped with a pressure means and a decompression means at the bottom of the flask, and the fugitive model is embedded in the flask with heat-resistant granules. , a step of fluidizing the heat-resistant granules by a pressurizing means, a step of inserting a fugitive model into the flask in a fluidized state, a step of vibrating the flask after stopping the flow, and a step of vibrating the flask after applying the vibration. A molding method in a filling casting method, comprising the steps of: covering the opening of the mold and solidifying the inside of the flask under reduced pressure using a depressurizing means.