JPH0428452A - Mold - Google Patents

Abstract

PURPOSE:To reduce the development of flash and to improve dimensional accuracy by gradually reducing outside size of a core print and inside size of a core print hole toward end part of the core print from boundary part between cavity and the core print and forming the inside size of core print hole larger than the outside size of core print in the end part of core print. CONSTITUTION:For example, body part 3a of a core 3 is formed as columnar shape and the core print 4 is formed as truncated conical shape. The core print hole 5 is formed as truncated conical shape coaxially to the core print 4, too but inclining angle of the conical surface thereof to the axis of conical face is formed at larger than that of the core print 4 so as to have angle alphato the conical surface of core print 4. Further, the outside size of core print 4 and the inside size of core print hole 5 at the boundary part with the cavity 6 are formed as the same so as to bring the core print 4 into close contact with the core print hole 5 in this part. Further, the core print 4 and the core print hole 5 at upper end part of the core 3 are formed as the same as the above, too.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mold used in manufacturing castings, and in particular, the occurrence of casting tension in the core baseboard portion is extremely small, and The present invention relates to a mold that can produce castings that are extremely easy to finish.

[Conventional technology]

FIG. 4 is a vertical cross-sectional view of a main part showing an example of a mold containing a core. In FIG. 4, 1 and 2 are an upper mold and a lower mold, respectively, and each constitute a main mold forming the outer surface of the casting. 3 is a core, which forms the inner surface of the casting, such as a hollow hole. Skirting boards 4 are integrally formed at the upper and lower ends of the core 3, and the core 3 is inserted through baseboard holes 5 provided in the upper mold 1 and lower mold 2, respectively.
is configured to be fixed in place. 6 is the cavity.

Reference numeral 7 denotes a sprue, which is bored into the upper mold 1 and the lower mold 2 so as to communicate the cavity 6 and the hot water lower so that molten metal can be introduced thereinto.

FIG. 5 is a vertical sectional view of the main part showing the vicinity of the baseboard 4 of the core 3 shown in FIG. 4, and the same parts are indicated by the same reference numerals as in FIG. 4. When formed, the baseboard 4 is formed in the shape of a truncated cone.

Using the mold formed as described above, a hollow casting corresponding to the cavity 6 can be manufactured by pouring molten metal into the cavity 6 via the hot water lower.

[Problem to be solved by the invention]

In the mold having the above configuration, there is a gap δ between the baseboard 4 and the baseboard hole 5 in order to adjust the position and/or inclination of the core 3 and to prevent wear of the model and core holder due to continued use. It is normal to form a . That is, the tapered angles of the conical surfaces of the baseboard 4 and the baseboard hole 5 are formed to be the same. Therefore, when the core 3 is assembled in the mold and molten metal is poured into the cavity 6, the molten metal may enter the gap δ between the baseboard 4 and the baseboard hole 5, causing so-called exaggeration. become. When such casting occurs, there is a problem in that extra casting work is required to remove the casting after manufacturing the casting. In addition, if the model and the core are partially worn, the occurrence of the above-mentioned casting will be further promoted.

On the other hand, if the gap δ between the baseboard 4 and the baseboard hole 5 is made extremely small in order to prevent the above-mentioned casting, the core 3
There is also the problem that the straightness of the core 3 decreases, which reduces the dimensional accuracy of the manufactured casting, and also induces mold ringing in the vicinity of the baseboard hole 5.

The present invention solves the problems existing in the above-mentioned prior art, and reduces the occurrence of casting in the core baseboard portion to an extremely small extent.
It is an object of the present invention to provide a mold capable of producing a casting with high dimensional accuracy and extremely easy finishing work.

[Means to solve the problem]

In order to achieve the above object, the first invention first includes a main mold provided with a cavity forming the outer surface of the casting;
In a mold formed by combining a core forming part of the inner surface and/or outer surface of the casting through one baseboard and a baseboard hole, the outside dimension of the baseboard at the boundary between the cavity and the baseboard. and the inside dimension of the baseboard hole are formed to be the same, and the outside dimension of the baseboard and the inside dimension of the baseboard hole are formed so that they gradually decrease from the boundary between the cavity and the baseboard toward the end of the baseboard, and the width is 1 width. The inside dimension of the baseboard hole is formed to be slightly larger than the outside dimension of the baseboard at the wood end. A technical method was adopted.

In the above invention, the angle between the outer contour line of the baseboard and the inner contour line of the baseboard hole in a cross section including the axis of the two cores or a cross section parallel to this cross section, or the angle between the tangent line in contact with each of the contour lines is 1 to 3. It can be formed into @.

Next, in the second invention, in a mold formed by fitting an upper mold and a lower mold through a convex part and a concave part forming a non-planar parting surface, the boundary part between the cavity and the baseboard is The outer dimension of the convex part and the inner dimension of the concave part are formed to be the same, and the outer dimension of the convex part and the inner dimension of the concave part are formed so that they each gradually decrease from the boundary between the cavity and the baseboard toward the end of the concave part and the concave part. The inner dimension of the concave portion is formed to be slightly larger than the outer dimension of the convex portion at the end of the portion. A technical method was adopted.

In the above invention, the angle formed by the outer contour line of the convex part and the inner contour line of the recessed part in a plane perpendicular to the mold matching direction or in a plane parallel to this plane, or the angle formed by the tangent line in contact with each of the contour lines is set to 1 to 3 degrees. can be formed.

In the first aspect of the invention, if the angle between the outside contour of the baseboard 9 and the inside contour of the baseboard hole, or the angle between the tangents touching the contour, is less than 1°, the boundary between the cavity and the baseboard Not only does mold ringing occur at the inner edge of the baseboard hole, but the function to adjust the straightness or inclination of the core is insufficient.
This is inconvenient because it reduces the dimensional accuracy of the casting.

However, if the angle exceeds 3°, the degree of adhesion between the baseboard and the baseboard hole at the boundary between the cavity and the baseboard will be insufficient;
When pouring molten metal, the molten metal can resist the pressure of the hot water, and the molten metal not only invades and causes casting tension, but also causes the core to shift due to the hot water pressure, which can cause problems in the finishing work of castings. This is not preferable because it complicates the process and reduces the dimensional accuracy of the casting.

Next, in the second invention, if the angle between the outer ring line of the 5 convex portions and the inner contour line of the recessed portion, or the angle between the tangent lines touching the contour line, is less than 1, the boundary between the 1 cavity and the baseboard This is inconvenient because mold ringing occurs at the edges of the uneven portion, reducing the dimensional accuracy of the casting. On the other hand, if the angle exceeds 3°, the degree of adhesion between the uneven parts at the boundary between the cavity and the baseboard will be insufficient, and the molten metal will be able to withstand the pressure of 11 molten metal, and the molten metal will invade. This is undesirable because it causes casting tension, which complicates the finishing work of the casting, and reduces the dimensional accuracy of the casting.

[For production]

With the above configuration, it is possible to prevent the occurrence of casting by ensuring the degree of closeness between the baseboard and the baseboard hole at the cavity boundary portion, or the degree of closeness between the uneven portions.

〔Example〕

FIG. 1 is a vertical cross-sectional view of the main part showing the vicinity of the baseboard of the core in the embodiment of the present invention, and the same parts are designated by the same reference numerals as in FIG. 5. Main body part 3a
For example, it is formed into a cylindrical shape.

The baseboard 4 is formed into a truncated cone shape. Note that the inclination angle θ of the conical surface with respect to the axis is preferably selected to be around 20°.

Next, the baseboard hole 5 is also formed in the shape of a truncated cone coaxial with the baseboard 4, but at a large inclination angle with respect to the axis of the conical surface.

It is formed to form an angle α with the conical surface of the baseboard 4. Further, the outer dimension of the baseboard 4 and the inner dimension of the baseboard hole 5 at the boundary with the cavity 6 are formed to be the same, so that the baseboard 4 and the baseboard hole 5 are in close contact with each other in this portion. Note that the baseboard 4 and baseboard holes 5 at the upper end of the core 3 are also formed in the same manner.

The table shows the number of occurrences of casting and mold ringing at the boundary with the cavity 6 when the angle α between the baseboard 4 and the baseboard hole 5 shown in FIG. 1 is varied.

In this case, the number of molded pieces is 10.

As is clear from the table, at first, angle α is θ
Because of this, the abutting positions of the baseboard 4 and the baseboard hole 5 in FIG. A gap is generated at the boundary between the baseboard 6 and the skirting board 4, resulting in a casting. On the other hand, in dimensions 5 and 6, the angle α exceeds 3°, and the contact between the first baseboard 4 and the baseboard hole 5 is too strong near the boundary between the cavity 6 and the baseboard 4. Therefore, although it is effective in preventing casting, the occurrence of mold ringing that damages the baseboard hole 5 in this area is observed. On the contrary.

In locks 2 to 4, the contact position when the first baseboard 4 and baseboard hole 5 fit is near the boundary between the cavity 6 and the baseboard 4, and the strength of the contact is appropriate. In addition to suppressing the occurrence of overcasting, there is almost no mold ringing.

FIG. 2 is a vertical sectional view of a main part of a mold showing another embodiment of the present invention, and FIG. 3 is a perspective view showing an example of a casting manufactured by the mold of FIG. When manufacturing a semi-cylindrical casting 8 as shown in FIG. 3, which is indicated by the same reference numeral as in the figure, a part of the parting surface of the upper mold 1 and the lower mold 2 becomes a conical surface.

The concave portion and the convex portion face each other. In FIG. 2, a portion of the lower mold 2 swells upward to form a semi-truncated conical convex portion 2a at both ends of the upper mold 1, which faces the semi-truncated conical recess 1a at both ends of the upper mold 1. . The outer dimension of the convex portion 2a and the inner dimension of the recessed portion 1a at the boundary with the cavity 6 are formed to be the same, and
The conical surface of the convex portion 2a and the conical surface of the concave portion 1a are formed to form an angle α.

By forming as described above, when the upper mold 1 and the lower mold 2 are molded together, the recessed part 1a and the convex part 2a are in close contact with each other at the boundary with the cavity 6 without mold ringing, Even when pouring molten metal, it is possible to prevent casting from occurring.

Note that the value of the angle α is 1° to 3＠ as in the above embodiment.
It is preferable to set it as the range of.

In this embodiment, an example was described in which a cylindrical core was used and each of the baseboard and the baseboard hole was formed in a truncated conical shape, but shapes other than those described above may also be used. The effect is the same even if the baseboard holes are each formed into a truncated polygonal pyramid, or even formed into a spherical crown or other curved surface. Further, the above-mentioned modification can also be applied to the convex portions and concave portions forming part or all of the parting surface of the mold. Furthermore, in this embodiment, an example of a single mold with one core inserted was described, but even if multiple cores are used, or in the case of a multi-core mold, The effect is the same. Of course, the present invention can also be applied to a core that forms part of the outer surface of a casting.

〔Effect of the invention〕

Since the present invention has the configuration and operation described above, the following effects can be expected.

(1) At the boundary with the cavity, the skirting board and the baseboard hole, as well as the convex part and the concave part that constitute the mold parting surface, can be completely brought into close contact, preventing the occurrence of casting can be made extremely small.

(2) As a result of the above, the dimensional accuracy of the casting can be improved, and the casting work can be extremely facilitated.

(3) When inserting the core and matching the molds, the baseboard and the baseboard hole fit together very well, which prevents mold ringing and greatly improves the dimensional accuracy of the casting.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a main part showing the vicinity of the baseboard of a core in an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of a main part of a mold showing another embodiment of the present invention, and FIG. FIG. 2 is a perspective view showing an example of a casting manufactured by the mold shown in FIG. 2; Figure 4 is a vertical sectional view of the main part showing an example of a mold containing a core;
FIG. 5 is a longitudinal cross-sectional view of the main part of the core shown in FIG. 4, showing the vicinity of the baseboard. 1: Upper mold, 2: Lower mold, 3: Core, 4: Skirting board. 5: Baseboard hole, 6: Cavity.

Claims (4)

[Claims] (1) A main mold provided with a cavity that forms the outer surface of the casting, and a core that forms part of the inner surface and/or the outer surface of the casting are combined through the baseboard and the baseboard hole. In a mold made of A mold characterized in that the dimensions and the inner dimension of the baseboard hole are each gradually decreased, and the inner dimension of the baseboard hole is formed to be slightly larger than the outer dimension of the baseboard at the end of the baseboard. (2) The angle between the outside contour of the skirting board and the inside contour of the skirting hole in a cross section including the axis of the core or a cross section parallel to this cross section, or the angle between the tangents touching each of the contours, is 1 to 3 degrees. The mold according to claim (1), which is formed as follows. (3) In a mold formed by fitting an upper mold and a lower mold through a convex part and a concave part that constitute a non-planar parting surface, the external dimensions of the convex part and the concave part at the boundary between the cavity and the baseboard. The inner dimension is the same, and the outer dimension of the convex part and the inner dimension of the concave part are each gradually decreased from the boundary between the cavity and the baseboard toward the end of the uneven part. A mold characterized in that the inner dimension of the concave portion is slightly larger than the outer dimension of the convex portion. (4) The angle formed by the outer contour line of the convex part and the inner contour line of the recessed part, or the angle formed by the tangent line that touches each of the above contour lines, in a plane perpendicular to the mold matching direction or in a plane parallel to this plane is 1 to 3 degrees. The mold according to claim (3).