JPS5927265B2 - Pressure molding method and equipment - Google Patents

Description

Detailed Description of the Invention In recent years, the molding process in foundries has become significantly more efficient and mechanized. In particular, various high-pressure molding devices have been developed for mass-produced iron castings, allowing high-speed molding of 10 to 60 seconds per mold. is being carried out.

On the other hand, in the case of large castings, water, glass,
Self-hardening sand using cement and various organic binders has been developed, and molding efficiency has improved, but the molding process still relies on human labor, and young workers are discouraged due to heavy labor during molding work. Casting costs continue to rise due to increased labor costs for molding work.

The present invention relates to a molding method for large molds using self-hardening sand and an apparatus therefor.

Currently, the molding equipment commonly used for mass-produced castings applies pressure from the top surface of the mold (opposite the model surface), so in order to sufficiently fill the molding sand along the model surface, Higher pressure (surface pressure 10-20kg/crt
f), the combined use of vibrators, and studies on segment shapes are being conducted.

When such a pressure-type molding device is applied to mold a mold for large objects, problems such as loss during transmission of pressure force due to an increase in the height of the mold and insufficient filling of molding sand occur.

In order to solve the above-mentioned problems, the present inventors conducted various tests on pressure transmission and molding sand filling, and as a result, as shown in Fig. 1, the pressure transmission coefficient is determined by the layer thickness of molding sand, that is, the mold Although it gradually decreases as the height increases, the degree of filling of molding sand tends to decrease suddenly from a depth of 100 to 200++ m from the pressurized surface, and at a depth of 250 mm, approximately 65% of the pressurizing force is transmitted. However, it became clear that the molding sand was not filled.

Therefore, if a conventional vibrator is used in combination to solve such filling defects, as the mold becomes larger, a vibrator with higher performance is required, which increases noise and deteriorates the working environment.

Based on the above findings, the present inventors have developed a method and apparatus for pressurizing a mold from both the model surface and the upper surface as a molding method that can be applied to molding large molds without deteriorating the working environment. Invented.

In general, casting molds are required to have strength to withstand handling, molten metal, and pressure, and ventilation to exhaust gas generated during casting.In particular, strength is required for the casting surface and surface, and ventilation is required for the center of the mold. is required.

However, since the strength of the mold increases as it is more densely filled with molding sand, and the air permeability decreases, it is difficult to effectively adjust both properties.

However, in conventional molds that are made only by applying pressure from the top, the filling of molding sand is sparse from the pressurizing surface to the casting surface, and although the casting surface has good air permeability, its strength is low. Defects such as sanding, washing, and burning occur.

If the pressing force is increased to make the casting surface more densely filled with molding sand, the strength of the casting surface will increase, but the permeability deep from the casting surface will deteriorate, making gas defects more likely to occur.

Furthermore, considering the degree of filling of the molding sand shown in FIG. 1, it is expected that no matter how high the pressing force is, there is a limit to the height of the mold that can be molded.

On the other hand, according to the pressurizing method of the present invention, since pressure is applied from both the model surface and the upper surface of the mold, the casting surface and upper surface are filled with molding sand by 100 to 150 mm, and the middle part of the mold is not filled to that extent. Therefore, the cast surface and top surface are strong,
A sandwich-shaped mold with good air permeability is molded in the middle part.

In addition, since it is not necessary to apply molding sand to the deep part of the mold, it is possible to reduce the pressing force (surface pressure), and there is no limit to the height of the mold to be molded, so it is possible to reduce the pressure of molds for large objects. Molding becomes possible.

Next, the present invention will be explained with reference to FIGS. 2 to 8.

The structure of the device according to the present invention will be explained with reference to FIGS. 2 to 4. 1 is a squeeze head connected to a rod 2 via a spherical seat 4, and the rod 2 is connected to a pressure tank connected to an external hydraulic pump or The squeezing head is raised and lowered at the same time by pressurizing oil into the cylinder 3 for raising and lowering the squeeze head, which is connected to the same pressure source such as an accumulator.

17 and 18 are sealing gaskets (in Fig. 2, the hydraulic piping system to the cylinder 3 for raising and lowering the squeeze head is not shown) 5 is a flask stopper, which has a lifting mechanism with screws and is The height can be adjusted depending on the amount of compression.

12 and 13 push up the flask 6 with the ram and cylinder of the flask lifting mechanism to fix the flask 6 together with the flask stopper 5.

In FIG. 2, the flask elevating mechanism is shown using a ram and a cylinder, but an elevating mechanism using screws or the like may also be used.

10 is a mold pressure ram, mold pressure ram cylinder ii
l/l: Therefore, it is installed in the lower frame 15 of the molding machine, and the mold pressurizing ram 10 pressurizes the molding sand 8 via the surface plate 7 and the model 9.

14 is an upper frame, 16 is a support of the molding machine, 21 is a flange of the surface plate, and 22 is a rib of the surface plate.

Next, the molding method will be explained with reference to FIGS. 5 to 8.

First, the surface plate 7 is installed on the conveyor 19, the model 9 and the casting flask 6 are placed on the surface plate 7, and the molding sand 8 is introduced from the molding sand supply tank 20, and then the surface plate 1 is placed inside the molding machine. to be placed in place.

The sand inlet of the foundry sand supply tank 20 can also be provided inside the molding machine so that the foundry sand can be introduced inside the molding machine.

Next, the flask stopper 5 is set at a height corresponding to the amount of molding sand compression.
Raise and lower and fix.

After that, only the flask 6 is pushed up by the flask lifting ram 12 until it touches the flask stopper 5, and then oil is pressurized into the squeeze head lifting cylinder 3 and the molding sand pressurizing cylinder 11, and the flange 21 of the surface plate γ is pushed up. Pressure ram 10 pushes up molding sand 8 until it contacts casting flask 6,
From above, molding sand 8 is pressurized from above and below by a squeeze head 1 to form a mold.

Next, at the same time as the squeeze head 1 is raised, the molding sand pressurizing ram 10 and the flask elevating ram 12 are lowered, and the mold is carried out of the molding machine together with the surface plate 7 and sent to subsequent processes such as die cutting.

In the case of large molds, self-hardening sand is often used, and since the mold cannot be removed immediately after pressure molding, the mold is transported together with the surface plate. It is possible to remove the mold immediately after pressure molding, and it is also possible to remove the mold in the molding machine and carry it out.

According to the present invention, pressure can be applied from above and below at the same time with a single hydraulic operation, and since cylinder 2 to which squeeze head 1 is connected is connected to the same pressure source as other cylinders, molding sand can be Even if the height of the model 8 is different, the squeeze head 1 is lowered according to the shape of the model, and the same pressure can be applied.

Therefore, it is unnecessary to position the squeeze head 1 according to the shape of the model, and the strength and filling properties of the mold at the same depth are uniform.

Furthermore, since the mold is molded under pressure from above and below, only the pressurized surface of the mold is filled, and a mold with good air permeability inside the mold can be obtained.

[Brief explanation of the drawings] Figure 1: Relationship diagram between the depth from the pressurizing surface, the pressure transmission coefficient of sand, and the dust filling of the sand. Figure 2: Front view (partial sectional view) of the device according to the present invention, Figure 3: A-A sectional view in Figure 2 of the device according to the present invention, Figure 4: Squeeze head according to the present invention. Detailed views of FIGS. 5 to 8: Explanatory views of the operating steps of the device according to the present invention. 1... Squeeze head, total... Cylinder for lifting and lowering the squeeze head, 6... Casting flask, 7...
...Surface plate, 9...Model, 10...
Mold pressure ram, 12... Ram for raising and lowering the flask, 14
...... Upper frame of the molding machine, 15... Lower frame of the molding machine.

Claims (1)

[Claims] 1. A casting flask is placed on a surface plate on which a model is placed, molding sand is poured into the flask, and a plurality of upper squeeze heads are pressed until they come into contact with the molding sand in the flask. Then, the flask is raised and fixed to a predetermined position according to the amount of compression of the molding sand, and then the surface plate is pushed up by a mold pressurizing ram until it comes into contact with the flask, and the squeeze head is lowered. let me,
A pressure molding method characterized in that molding sand is filled under pressure by changing the position of the squeeze head so that the pressure applied to the squeeze head is approximately uniform. 2. A plurality of squeeze heads each having an elevating mechanism using a cylinder connected to the same pressure source on the upper part, a plurality of flask stoppers each having an elevating mechanism using a screw installed at a position facing the upper surface of the flask, and a flask. A pressure molding device characterized by having a plurality of flask push-up mechanisms each having an elevating mechanism using screws or cylinders installed at positions facing the lower surface of the molding device, and a mechanism for pressurizing molding sand from the lower part.