JPS5927264B2 - Pressure molding method and equipment - Google Patents

Description

[Detailed Description of the Invention] In recent years, the efficiency and mechanization of molding processes in foundries have been significantly improved, and in particular, various high-pressure molding devices have been developed for mass-produced cast iron castings. High-speed molding is carried out at 60 seconds/mold.

On the other hand, when it comes to 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. However, 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 that is often used for molding mass-produced castings is a method that applies pressure from the top surface of the mold (opposite the model surface), and for this reason, the model surface is sufficiently filled with ℃ molding sand. In order to
cn! t), the combined use of vibrators, and studies on segment shapes are being conducted.

When such a pressurizing type molding apparatus is applied to molding a mold for a large mold, problems such as a loss during transmission of pressurizing 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 inventors conducted various tests on pressure transmission and molding sand filling, and found that
As shown in Figure 1, the pressure transmission rate gradually decreases as the thickness of the molding sand layer increases, that is, the height of the mold, but the dust filling the molding sand increases from a depth of 100 to 200 mm from the pressurizing surface. There is a tendency for the pressure to decrease rapidly, and at a depth of 250 mm, approximately 65% of the pressurizing force is transmitted, but it was found that the filling with molding sand was carried out and the temperature was 0°C.

Therefore, if a conventional vibrator is used in conjunction with a vibrator to solve such filling defects, as the mold becomes larger, a high-performance dog/pie break will be required, which will also increase noise and degrade the working environment. make worse.

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 it.

In general, molds are required to have strength to withstand mold handling and molten metal 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. However, the strength of the mold increases as it is more densely filled with molding sand, while the air permeability decreases, making it difficult to effectively adjust both properties. That's a problem.

However, in conventional molds that are made only by applying pressure from the top, the filling of molding sand becomes sparse from the pressurizing surface to the casting surface, and although the casting surface has good air permeability, it has poor strength. This results in defects such as sand build-up, washing, and burning.

Furthermore, if the pressing force is increased to make the casting surface more densely filled with molding sand, the strength of the casting surface increases, but the permeability deep from the casting surface deteriorates, making gas defects more likely to occur.

Furthermore, judging from the degree of filling of the molding sand shown in FIG. 1, it is expected that even if the pressing force is increased in degrees Celsius or more, 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 to a depth of 100 to 150 mm, and the middle part of the mold is not filled as much. Therefore, a sand inch-shaped mold is formed that has strong casting surface and upper surface and good air permeability in the middle part.

Also, there is no need to fill the molding sand deep into the mold.
Therefore, it is possible to reduce the pressing force (surface pressure), and there is no limit to the height of the mold to be molded, making it possible to pressurize molds for large objects.

Next, the present invention will be explained with reference to an embodiment shown in FIGS. 2 to 11.

The structure of the device of this embodiment will be explained with reference to FIGS. 2 to 6.
1 is a squeeze head, which is connected to a rod 2 via a spherical seat 4, and the rod 2 is connected to a rotary drive shaft 7 for lifting and lowering the squeeze head through engagement between a female screw 5 and a male screw 3.
・Ru.

The rotation shaft 7 for lifting and lowering the squeeze head is rotated by a hydraulic motor 8 by a rotation angle preset by a rotation angle detector 9, thereby raising and lowering the rod 2.

The rod 2 has a structure in which a slide guide 22 prevents lateral vibration and a rotation stop key 23 prevents rotation during elevation.

Further, the axial force that the squeeze head 1 receives when pressurizing the mold is supported by the slide bearing 6.

The squeeze head 1 having the above structure is used for the model 1 to be handled.
Considering the 40 types and sizes, they are suspended from the upper frame 19 of the molding machine at appropriate intervals.

A flask stopper 10 has a lifting mechanism similar to that of the squeeze head 1, and its height can be adjusted according to the amount of compression of the casting sand.

Reference numerals 17 and 18 indicate a plurality of rams and cylinders of a flask lifting mechanism, which push up the flask 11 and fix the flask 11 together with the flask stopper 10.

In FIG. 2, the flask elevating mechanism is illustrated using a ram and a cylinder, but other elevating mechanisms using screws or the like may also be applied.

Reference numeral 15 denotes a molding sand pressurizing ram, which is installed in the lower frame 20 of the molding machine by a cylinder 16 for the molding sand pressurizing ram. Apply pressure.

21 is a support of the molding machine, 26 is a flange of the surface plate, and 27 is a rib of the surface plate.

The height H of the rib 27 attached to the surface plate 12 is determined by the molding sand 13.
If the molding sand 13 is placed higher and in a continuous shape than the compression scale, it is possible to prevent the molding sand 13 from leaking from the lower side of the flask 11 when the flask 11 is pushed up and fixed by the flask lifting ram 17. .

Furthermore, if the surface 26' of the flange 26 on the surface plate 12 facing the flask 11 is located at a higher temperature than the surface 26 surrounded by the ribs 27, the mold pressurizing ram 1
5 to push up the surface plate 12 and compress the molding sand 13, the surface 26' of the flange 26 of the surface plate 12 will touch the flask 11.
Compression of the molding sand 13 ends at the position where it comes into contact with the end surface 11' of the molding sand 13.

That is, the flange 26 is effective for positioning to prevent the molding sand 13 from being excessively compressed. When placed in the high position, the cutting surface 13' of the mold after molding will protrude from the end surface 11' of the flask 11, that is, the mating surface.

Therefore, when the upper mold equipped with a pouring spout, riser, etc. is stacked on top of the mold, the parting surfaces 13' of the molds are in close contact with each other, so that an accurate mold can be formed, and no casting occurs during casting.・.

Next, the molding method will be explained with reference to FIGS. 7 to 11.

First, the surface plate 12 is placed on the conveyor 24, and the surface plate 12 is placed on the conveyor 24.
The rear leg surface plate 12, on which the model 14 and casting flask 11 are placed and molding sand 13 is charged from the molding sand supply tank 25, is fixed in the molding machine.

The sand inlet of the molding sand supply tank 25 may be provided inside the molding machine so that the molding sand can be introduced inside the molding machine.

Next, at 0.degree. C., the hydraulic motor 8 is rotated to the scale of the rotation angle detector 9 set according to the shape of the model 14, and the plurality of squeeze heads 1 are lowered.

Although FIG. 9 only shows positioning, the amount of molding sand input is large and sometimes pressure is applied temporarily.

On the other hand, the flask stopper 1 is placed at a position corresponding to the amount of compression of the molding sand.
0 is fixed for raising and lowering.

After that, only the flask 11 is pushed up by the flask lifting ram 17 until it touches the flask stopper 10, and then the mold pressurizing ram 15 is raised until the flange 26 of the surface plate 12 touches the flask 11. Casting sand 1 is passed through the plate 12 and the model 14.
3 is compressed under pressure.

Next, the flask lifting ram 17 and the mold pressurizing ram 15 are lowered, while the squeeze head 1 is also raised, and the mold 14 is carried out of the molding machine together with the surface plate 12 and sent to subsequent processes such as die cutting.

In the case of large molds, self-hardening sand is often used, and the mold cannot be removed immediately after pressure molding, so the mold is placed on a surface plate.
However, in the case of molding sand made of clay or the like as a caking agent, the mold can be removed immediately after pressure molding, and there is no need to have a mechanism for transporting it together with the surface plate.

As described in detail above, in the present invention, since the mold is molded by applying 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 drawing]

Figure 1: Relationship diagram between the depth from the pressure surface, the pressure transmissibility of the sand, and the sand filling dust; Figure 2: A front view of the device according to the present invention (
(Partial sectional view), Figure 3: A-A sectional view in Figure 2 of the apparatus according to the present invention, Figure 4: Detailed view of the squeeze head and flask stopper according to the present invention, Figure 5: Book Detailed view of the surface plate according to the invention, FIG. 6: An explanatory view of the cutting surface of the mold according to the invention, FIGS. 7 to 11: An explanatory view of the operation process of the apparatus according to the invention. 1... Squeeze head, 7... Rotating shaft for lifting and lowering the squeeze head, 11... Casting flask, 12...
... Surface plate, 14 ... Model, 15 ...
...Mold pressure ram, 17...Flame lifting ram, 1
9... Upper frame of the molding machine 20... Lower frame of the molding machine.

Claims (1)

[Claims] 1. After pouring molding sand into a flask placed on a surface plate on which a model is placed, a plurality of upper squeeze heads are lowered and positioned into the flask according to the shape of the model. Next, the flask is raised to a predetermined position determined based on the amount of compression of the molding sand put into the flask, and then the surface plate is pushed up until it comes into contact with the flask again. A pressure molding method characterized by filling molding sand under pressure. 2 Suspended from the upper frame of the molding machine at appropriate intervals,
There are a number of squeeze heads each equipped with a lifting mechanism using screws on the top, a plurality of flask stoppers equipped with lifting mechanisms using screws installed at positions facing the top surface of the flask, and a plurality of flask stoppers equipped with a lifting mechanism using screws installed at positions facing the top surface of the flask, and facing the bottom surface of the flask. A pressure molding device characterized by having a plurality of flask push-up mechanisms using screws or cylinders installed at positions to push up the flask, a surface plate equipped with sand-stopping ribs, and a mechanism for pushing up the surface plate. .