JPS6317565Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a gas vent for compressing molding sand in a mold making device, and it is possible to form these parts neatly even in molds that protrude sharply at right angles or have external angular ridges or external angular vertices with a small radius of curvature. With the goal.

Conventionally, in a mold making device, a mold 62 is fixed on a surface plate, and the outer periphery of the mold 62 is surrounded by a mold, and while molding sand is filled in the flask, a vent hole 66 is made in the surface plate or the mold 62, and the molding sand is poured into the mold. A vent vent 55 is buried to suck out the gas (see Fig. 9). However, when forming a mold with a sharp protrusion at right angles or an external edge or apex with a small radius of curvature, the mold model 62 is buried.
The vent 55 is buried in a vent hole 66 opened vertically downward along the side wall 71 forming the inner corner ridge 70, and the molding sand is filled so as to surely contact and press the inner corner ridge, but the upper wall of the vent is Since the width H of the hole 51 is small, when it is pressed from above and press-fitted, it may shift to the left or right or be damaged. The ventilation groove 5 of the vent is directly connected to the ridge 70.
3 is not located, the molding sand is pressed against the model while leaving a void around the inner corner ridge 70, so it is difficult to completely restore the outer corner ridge of the formed mold from the model.

For this reason, the method shown in Japanese Utility Model Application Publication No. 55-154649 was proposed.

That is, apart from a vent, we proposed a gas venting device consisting of an assembly of multiple thin plate members, each of which has protrusions placed at appropriate intervals on its front surface, and a curved surface on the upper end. The projection member is fixed to the back surface of the thin plate member by gluing or the like to form an aggregate, and in the state where the aggregate is formed,
A large number of ventilation holes with a square cross section are formed between the thin plate member and the protruding member, penetrating in the vertical direction,
A series of curved surfaces are formed at the upper end.

As a result, a desired curved surface can be formed at the upper end of the gas venting device, so that the gas venting device can be installed even in a curved location.

However, this product had the following drawbacks.

Since the curved surfaces formed on a plurality of thin plate members are connected to form a series, the shape of the curved surface formed is fixed to one. For this reason, only one type of curved surface can be obtained from one degassing device, resulting in poor versatility.

In addition, since it is an aggregate made of multiple thin plate members glued together, it is difficult to process the upper end by cutting or other means to form various curved surfaces, and there is a risk of damage during processing. , there is a high risk of breakage.

Furthermore, since curved surfaces formed on a plurality of thin plate members are connected to each other to form a series of curved surfaces, it is not possible to form a continuous curved surface with high precision. For this reason, stepped portions are formed at the joints of the curved surfaces, where molding sand tends to accumulate and cause clogging at an early stage.

Moreover, since it is made up of multiple thin plate members glued together to form an assembly, if one part of the ventilation hole is damaged or broken, the surrounding thin plate members will be affected and damaged. , the cross-sectional shape of other ventilation holes may be deformed. For this reason, the durability of the gas venting device as a whole is poor, and there is also the problem that molding sand passes through the deformed and enlarged vent hole.

Moreover, since the degassing device is an assembly consisting of a plurality of thin plate members, its structure is complicated and expensive.

Also, the width H of the upper wall 51 of the integrally molded vent 55
From a technical point of view, it was impossible to create a large number of ventilation grooves 53 lined up in the upper wall 51 having a large width H.

Therefore, in order to eliminate the above-mentioned drawbacks in accordance with recent technological advances, the present invention has been developed by extending a connecting wall downward from the lower part of the upper wall, and creating a narrow ventilation groove that does not allow the molding sand to pass through, but allows gas to pass through. A large number of ventilation grooves are formed in a row in the upper wall vertically through the upper wall, and ventilation grooves are integrally formed in the upper wall.The width of the outline of the group of ventilation grooves is set as L, and the thickness of the upper wall is set as H. In this case, the thickness H of the upper wall and the width L of the outline of the group of ventilation grooves are set so as to satisfy at least the formula H>L/2, and the vent with the above thickness is set as a mold model. By embedding the vent in an inclined manner on the inner corner ridge or top of the vent, and by scraping the top wall of the vent diagonally, it is possible to completely press the molding sand into the inner corner ridge, etc. of this model so that it is flush with the model surface. Even if the mold has a sharply protruding portion or a portion with a small radius of curvature, such as an external corner edge, this portion can be formed accurately.

The present invention will be explained below based on the drawings.

Figure 1 is a partial vertical perspective view of the mold making device, Figure 2
The figure is a perspective view showing the state before the vent is buried in the model, Figure 3 is a longitudinal cross-sectional view of the main part of the model showing the state where the vent is buried, and Figure 4 is the main part of the model showing the state with the vent hollowed out. The mold making device 10 is a vertical cross-sectional view, in which the outer periphery of a mold model 12 fixed on a surface plate 11 is surrounded by a flask 13, the upper opening of the flask 13 is closed with a compression plate 14, and the mold making device 10 is fixed. A molding space 15 formed by the plate 11, the flask 13, and the compression plate 14 is filled with molding sand by pneumatic transport from a molding sand supply device (not shown).

Vent holes are provided in the inner corners of the surface plate 11 and the model 12 to suck the molding sand filled in the molding space 15 so as to bring it into sealing contact with the model, and to discharge the molding sand transfer gas to the outside of the molding space. 16 are installed in multiple locations at appropriate locations.

A gas release vent 5 for compressing molding sand is press-fitted into this vent hole 16 to prevent molding sand from flowing out of the molding space 15.

The vent hole 16 of the surface plate 11 is stepped from above and penetrates in the vertical direction, and the vent 5 is press-fitted into this stepped part. Provided to be inclined at approximately 45 degrees from below with respect to the inner corner edge 20b of the recessed portion,
A hook portion 12a is left on the inner wall so that the vent 5 is press-fitted from below and is not removed outwardly from the model 12.

The vent 5 is made up of a cylindrical upper wall 1 and a connecting wall 2, and has narrow ventilation grooves 3 extending vertically through the upper wall 1 that do not allow the casting sand to pass through but allows gas to pass therethrough, as well as a large number of holes in the horizontal direction. They are arranged in a downwardly expanding shape, and a cylindrical connecting wall 2 is extended below the connecting wall 2, and a rib 17 is formed inside the connecting wall and below the center in the direction orthogonal to the ventilation groove 3.

Also, as shown in Fig. 3, this vent is press-fitted at an angle of about 45 degrees from the perpendicular direction to the inner corner edge 20 of the model 12, so the thickness of the upper wall 1 is H, and the ventilation grooves 3 are parallel to each other. If the width of the contour of the groove group is L, then the distance S between the upper surface 18 of the upper wall 1 and the internal angle ridge 20 must be set smaller than the thickness H of the upper wall, and
Since the distance S is equal to half the contour width L of the groove group, it must satisfy the formula H>L/2. After closing the lid and fitting the vent 5 into the inner corner ridge 20, in order to adjust the model, the flesh wall 21 protruding from the model 12 is cut out by cutting or the like, so that it is flush with the side wall of the model, as shown in FIG. Due to the need to form a vent surface, the limit of this hollowed out portion is determined by the contour width of the groove group, so the thickness H of the upper wall 1 must be larger than the depth L/2 of this hollowed out portion 21. This is because there is a risk that the central portions of the plurality of ventilation grooves 3 will be gouged out and the foundry sand will be discharged from the vent holes.

The above vent is a cylindrical body with an outer diameter of 20 mm, the thickness of the upper wall is 10 mm, the thickness of the connecting part is 5 mm, the outline width of the ventilation groove group is 18 mm, and the gap between the ventilation grooves is 0.3 to 0.4 mm. It is best to make it from SS material, brass or epoxy resin.

Further, a shell mold may be used for the molding sand, and carbon dioxide may be used as the gas for transporting the molding sand.

FIG. 5 is a vertical cross-sectional view of the main part of another embodiment of the present invention in which the vent is buried, and FIG. A step-shaped vent hole 16 is penetrated from diagonally above a predetermined internal angle edge of the model 12, and the vent 5 is press-fitted into this step, and the depth S of the hollowed out vent is equal to the vent outer diameter M. Therefore, the thickness H of the vent upper wall 1 must be larger than half M/2 of the vent outer diameter (H>M/2>L/2).

Furthermore, FIG. 7 also shows another embodiment of the present invention, in which the inner corner edge 20 of the model 12 forms an angle other than 90 degrees, and the thickness H of the vent upper wall 1 is By making the contour L larger than the group outline L, the upper wall thickness H can be ensured to be thicker than the gouge depth S of the vent, and on the other hand, the vent operation can be applied even when the inner corner edge of the model forms the R surface 21.

Next, as shown in FIG. 8, even if the model 12 has a deep groove 30, by using the vent of the present invention and press-fitting it into the innermost part of the groove, the molding sand can be reliably poured into the innermost part of the groove. This eliminates the need for a core that can be compressed and difficult to pull out depending on the depth and thinness of the groove.

The effects of the present invention will be described below.

Since the thickness of the vent upper wall is set to be larger than half the width of the outline of the group of ventilation grooves, the radius of curvature is Even if the model has small corners or grooves, by scooping out the thick upper wall of the vent to match the corners of the model, the vent can be buried in the above-mentioned area in an inclined direction. Therefore, it is possible to prepare a mold by filling the molding sand sufficiently deeply, and it is possible to form a mold whose external edges, corners, etc. are accurately reproduced from the model.

In addition, since the upper wall part of the vent protruding from the model is cut out by cutting according to the internal angle edge and radius of curvature, whether the internal angle edge or the internal angle apex of the model is sharply cut at right angles or obtuse angles, Regardless of the size of the radius of curvature, various types of castings can be easily formed by simply preparing a common type of corner vent, which is excellent in versatility, and there is no need to always have a type of vent other than the corner vent.

Furthermore, since the desired shape is cut out by cutting etc. on the vent upper wall where the ventilation groove is integrally formed,
A series of shapes can be formed with high precision, eliminating problems such as stepped portions and early clogging.

Moreover, since the ventilation grooves are integrally formed on the upper wall of the vent, even if one of the ventilation grooves is damaged or broken, there is almost no effect on the ventilation grooves outside, ensuring durability. Excellent in

Moreover, it is only necessary to integrally form the ventilation grooves on the upper vent wall and to form the thickness of the upper vent wall to be larger than half the width of the outline of the group of ventilation grooves, so the structure can be improved. It is not complicated, can be summarized into something simple, and can be implemented at low cost.

[Brief explanation of the drawing]

Figure 1 is a partial vertical perspective view of the mold making device, Figure 2
The figure is a perspective view showing the state before the vent is buried in the model, Figure 3 is a longitudinal cross-sectional view of the main part of the model showing the state where the vent is buried, and Figure 4 is the main part of the model showing the state with the vent hollowed out. 5 is a view equivalent to FIG. 3 showing another embodiment of the present invention, FIG. 6 is a view equivalent to FIG. 4, and FIG. 7 is a fourth view showing still another embodiment of the present invention. Fig. 8 is a vertical sectional view of the main part of the model showing how the vent is used in a model with grooves, Fig. 9
The figure is a vertical cross-sectional view of a main part of a model showing a conventional example of a vent buried in the state. 1... Upper wall, 2... Connecting wall, 3... Ventilation groove, H
... Thickness of the upper wall, L ... Width of the outline of the group of ventilation grooves.

Claims (1)

[Scope of utility model registration request] Connecting walls 2 are integrally extended downward from the lower part of the upper wall 1, and a large number of narrow ventilation grooves 3, which do not allow the passage of molding sand to pass through but allow gas to pass through the upper wall 1 in the vertical direction, are lined up and opened. The ventilation grooves 3 are integrally formed on the upper wall 1, and the width of the outline of the group of ventilation grooves 3 is set as L, and the upper wall 1
If the thickness of
A gas vent vent for compressing molding sand in a mold making device, characterized in that the thickness H of the upper wall 1 and the width L of the outline of the group of ventilation grooves 3 are set so as to satisfy the formula >L/2.