JP3410798B2 - Mold and casting method using this mold - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold used for producing metal castings (mainly cast iron products) and a casting method using this mold.

[0002]

2. Description of the Related Art In the case of tapping a metal cast product, after performing the necessary surface processing, the cast product is conveyed to a hole drilling machine such as a milling machine, where it is drilled with a drilling tool or an end mill. After forming the pilot hole in the cast product, the drilling tool is replaced with a thread cutting tool such as a tap, and a screw is engraved in the pilot hole by the thread cutting tool. It is also practiced to form a pilot hole at the casting stage and omit the pilot hole. As a method of forming a pilot hole during casting, for example, in the case of performing casting using a split mold, a method of forming a projection for forming a pilot hole at a predetermined location on the inner surface of one or both molds, There is a method of holding the core for forming the pilot hole in a predetermined portion of the casting space formed later.

[0003]

However, even a small cast product is quite heavy, and there is a limit to carrying it manually. Therefore, a hoist, a crane, a carrier, or the like is used when the cast product is conveyed from the surface processing machine to the hole processing machine or directly to the hole processing machine. Therefore, the work itself of setting a cast product on a machine tool due to thread cutting is difficult and dangerous. In particular, when it is necessary to provide screw holes with different hole diameters at multiple locations, it is necessary to change the set position of the cast product on the machine tool and replace the thread cutting tool many times, which is very troublesome. Therefore, the work efficiency was poor.

Further, depending on the shape of the cast product and the position where the screw hole is formed, the cast product cannot be set in the machine tool,
In some cases, it was not possible to insert the thread cutting tool to the lower hole position . The present invention has been made in view of the above circumstances, and it is possible to form screw holes and the like extremely easily, quickly, and safely, and further, without being affected by the shape of the casting, the forming position of the screw holes, and the like. It is an object of the present invention to provide a mold capable of forming a screw hole reliably and with high accuracy, and a casting method using this mold.

[0005]

In order to achieve the above object, the present invention takes the following technical means. That is, in the mold according to the present invention, the casting space (3) formed in the mold
Of the screw core (2
0) (26) is held in the mold, wherein the screw
Both ends of the core (20) (26) are held in the mold.
It is characterized in that there. In addition, in the mold according to the present invention, the entire casting space (3) formed in the mold or at least a part including the screw hole forming position is loaded with the screw receiving member (25) which can disappear at the casting temperature or lower. A screw core (26) having a male screw shape is held at a predetermined position of this screw receiving member (25) , and the screw core (26) is
It is characterized in that both ends are held in a mold or the like.

By forming the screw core from a carbonaceous material, a unique effect can be obtained . In the casting method according to the present invention, the casting space (3) formed in the mold
Of a carbon-based material that
Gas passage (2
6a) has a threaded core (20) (26) formed therethrough.
It is characterized in that the molded product is held, the product is cast, the cast product (1) is taken out, and the screw cores (20) and (26) are collapsed and removed from the cast product (1). .

[0007]

In the mold according to the present invention, the screw core itself to be held in the casting space in the mold is formed with the male screw shape. Therefore, after the casting, the screw hole is formed by simply removing the screw core from the cast product. It is obtained and does not require machining for thread cutting. If the screw core is held in advance in the screw receiving member and then set together with this screw receiving member in the casting space, the screw core can be positioned easily and accurately with respect to the casting space, and its holding is ensured. Becomes

When the screw core is made of a carbon material, the casting surface on the inner surface of the screw hole can be formed finely and the screw shape itself can be formed with high precision.
It is also possible to form a keyed hole by replacing the screw core with a keyed core. When the screw core is formed of a carbon-based material, it can be collapsed and removed from the cast product by striking the core after casting and the like, and thus the post-treatment is simple. In particular, when the screw core is made of a carbon-based material, even if the core debris (carbon-based material) remains in the screw hole portion of the casting formed by the core, Lubrication is performed between the screw hole and the screw screwed into the screw hole, and no problem occurs.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a side sectional view (shown by a portion corresponding to the line AA of FIG. 4) showing the mold 2 of the present invention used for casting the cast product 1 illustrated in FIG. Is a casting 1
The casting space 3 corresponding to is formed. In this embodiment, since the casting 1 has a shape having a semi-cylindrical main body 4 and a flange joint 5 protruding upward from the central portion, the casting mold 2 is referred to as an upper die 6. It is a split mold composed of a lower mold 7, and the upper mold 6 is a first upper mold 8 and a second upper mold 9.
It is assumed that the lower mold 7 can be divided into a first lower mold 10 and a second lower mold 11. Further, the second upper mold 9 is configured to be horizontally splittable (not shown) with the center position of the flange joint portion 5 as a boundary. 12 is a cast product 1
It is a core for making the main body part 4 in the hollow shape.

By the way, in the cast product 1 shown in FIG. 4, a tongue piece portion 15 protruding outward is provided on a side portion of the main body portion 4, and the tongue piece portion 15 is vertically penetrated. A threaded hole 16 is required. Also, the flange joint part 5
The boss portion 17 is bulged on the side surface of the boss 17, and a screw hole 18 penetrating the boss portion 17 in the horizontal direction is required. Therefore, the mold 2 is as follows.
That is, at the corresponding portion of the lower die 7 in which the screw hole 16 is provided (the portion shown in FIG. 3B), a state of passing through the casting space 3 between the first lower die 10 and the second lower die 11 as shown in FIG. The screw core 20 is held by.

The screw core 20 is composed of a male screw portion 21 having a thread formed on the outer peripheral surface thereof, and a skirting board 22 provided at both ends of the male screw portion 21. At the center of the screw core 20, a gas through hole 2 penetrating the inside of the male screw portion 21 and the skirting board 22.
0a is formed. The baseboard 22 is a screw core 20.
It is for the purpose of preventing the positional deviation when holding the mold and the positional deviation at the time of casting, and is fitted in the fitting recesses 23 and 24 formed in advance in the first lower mold 10 and the second lower mold 11. To It has nothing to do with the outer shape of the casting 1. In addition, such a skirting board 22 is not indispensable, and when the skirting board 22 is not provided, the first lower die 10 and the second lower die 11 face the screw core 20 from both ends thereof. The clamping force is applied (in this case, the fitting recesses 23 and 24 for the first lower mold 10 and the second lower mold 11 are of course unnecessary).

On the other hand, at a corresponding portion (FIG. 3C) of the upper die 6 in which the screw hole 18 (see FIG. 4) is provided, as shown in FIG. 2, a screw receiver for filling the casting space 3 facing the second upper die 9. The member 25 is loaded and the screw core 26 is held in a state where the inside of the screw receiving member 25 is penetrated. The screw receiving member 25 is made of a material that can disappear at a temperature lower than the casting temperature, for example, Styrofoam, and in the flange joint portion 5 (see FIG. 4) of the cast product 1, at least the boss portion 17 and its surroundings. Has a shape corresponding to some of the peripheral wall portions (see FIG. 5). A holding hole 25a penetrating in the horizontal direction is formed in a portion corresponding to the boss portion 17. The holding hole 25a is formed to have an inner diameter that allows the screw core 26 to be fitted in a penetrating manner and to be held without rattling. In addition, in the holding hole 25a,
An internal thread that can be screwed into the threaded core 26 may be formed, but such a measure is not always necessary.
Further, the screw core 26 may be integrally formed when the screw receiving member 25 is formed.

The screw core 26 has a male screw shape as a whole. Regarding the length of the screw core 26, if the size is determined such that both ends of the screw core 26 project even slightly from the screw receiving member 25, the screw core 26 can be compared with the second upper mold 9 or the core 12. I will cut in,
Even after the screw receiving member 25 has disappeared during casting, the screw core 26 is not pushed by the molten metal to cause a positional shift, which is a preferable measure. A gas passage hole 26a is also formed through the entire length of the central portion of the screw core 26. At the time of assembling the mold, the screw receiving member 25 holding the screw core 26 is pinned to the core 12 for hollowing out or the second upper mold 9 of the cast body,
Just glue it.

For the above-mentioned screw cores 20 and 26, a core is removed by adding a binder to graphite powder as appropriate (mold for core production).
Etc. are used to harden it into a predetermined shape, to further sinter it, or to machine it from a graphite rod by machining to obtain a predetermined shape. The material of the screw core has mechanical strength that does not cause damage to the threads, etc. due to the mild impact expected during handling, and has fire resistance and heat resistance at the casting temperature. Any material that does not cause fusion with the hot water or a local cooling effect (chilling) on the hot water is preferable, and a material that collapses by being hit with a hammer or the like after casting is preferable. As a material satisfying such characteristics, a ceramic (Al ₂ O ₃ , ZrO ₂ , SiO _2, etc.) fired body, gypsum, or the like can be used in addition to the above-mentioned carbon-based material. Diameter is several tens of μ
It is also possible to use fine mold sand of m or less.

In the mold 2 thus constructed, as shown in FIG.
When the molten metal is poured into the casting space 3 after molding in the state shown in Fig. 4, the corresponding portion of the screw hole 16 (see Fig. 4) except the screw core 20 is filled with the hot water, and the screw hole 18 The screw receiving member 25 is provided at the corresponding position (see FIG. 4).
Disappears, the surroundings except the screw core 26 are filled with hot water. At this time, the screw core 20
(See FIG. 1) and 26 (see FIG. 2) allow gas to freely flow between the molds through the gas passage holes 20a and 26a, so that gas defects such as pinholes occur in the casting 1. Can be prevented.

After the casting is completed, the casting 1 is taken out after waiting for a certain amount of cooling to demold or collapse the mold 2. Since the threaded cores 20 and 26 are still held in the cast product 1 taken out, the threaded cores 20 and 26 are struck with a hammer or the like to be collapsed and removed. Screw core 20,2
By forming the gas through hole 20a in 6, the core can be collapsed and removed very easily. FIG. 6 shows another example of a casting 28.
It is a partial view showing the screw hole 2 in this cast product 28.
Obstacles 30 and 31 are provided on an extension line of the shaft 9 in the axial direction. Therefore, conventionally, a tool insertion hole having a large diameter is formed in advance on either one of the obstacle portions 30 or 31, and a thread cutting tool (not shown) such as a tap is inserted from the tool insertion hole. According to the casting method of the invention, the screw hole 29 can be easily formed without forming the tool insertion hole.

By the way, when it is necessary to form keyed holes (including serration holes, spline holes, etc.) in the cast products 1, 28, etc., the above-mentioned screw core 20
Instead of or 26, a keyed core (not shown) having at least one recess or protrusion formed in the radial direction so as to project or be recessed in the radial direction of the core is used. To do. Others are the same as the case of the screw cores 20 and 26, and thus the description thereof is omitted here. In the present invention,
The structure and forming material of the mold 2 and the shape of the casting 1 are not limited in any way. For example, not only ordinary molds such as raw mold and dry mold but also special molds such as baking mold, dry hardening mold and room temperature self-hardening mold It can be applied to any mold such as a mold.

As a method of removing the screw cores 20 and 26 from the cast product 1, tool engaging portions (hexagonal heads, hexagonal recesses, etc.) are previously formed on the screw cores 20 and 26, and after casting, A wrench or the like may be engaged with the tool engaging portion to loosen the core and then withdraw the core. In this case, the disintegrating property is not always necessary as the material of the core.

[0019]

According to the present invention, which has the above-described structure, the screw core itself to be held in the casting space in the mold is formed with the male screw shape. A screw hole can be obtained simply by removing the screw core.
No machining required for thread cutting. Therefore, there is no need to carry or set the cast product to the high-hole drilling machine, and work efficiency can be dramatically improved. In addition, since it is possible to form the screw holes without being affected by the shape of the cast product, the screw hole formation position, etc., it is possible to remove the design restrictions on the cast product and to bother the casting purpose. It is possible to omit the trouble of forming a tool insertion hole in the product.

If the screw core is held by the screw receiving member in advance and then set in the casting space together with the screw receiving member, the positioning of the screw core with respect to the casting space can be performed easily and accurately. The holding becomes reliable. If the screw core is made of carbon-based material,
The casting surface on the inner surface of the screw hole can be formed finely and the screw shape itself can be formed with high precision. Therefore, in the cast product, strong and reliable screw connection with other members can be achieved. If the threaded core is replaced with a keyed core, the same effects as above can be obtained when forming the keyed hole.

When the screw core is made of carbonaceous material, it can be collapsed and removed from the cast product by striking the screw core after the casting, so that the post-treatment is simple. . Further, even if the debris (carbonaceous material) of the screw core remains in the screw hole, the debris causes a lubricating action between the screw hole and the screw screwed into the screw hole. Excellent productivity with no need to remove residual debris from the thread groove.

[Brief description of drawings]

FIG. 1 is an enlarged view of part B of FIG. 3, showing a first embodiment of a screw core.

FIG. 2 is an enlarged view of a C portion of FIG. 3, showing a second embodiment of the screw core.

FIG. 3 is a side sectional view showing a mold according to the present invention at a portion corresponding to the line AA in FIG.

FIG. 4 is a perspective view showing an example of a cast product.

FIG. 5 is a perspective view showing a screw receiving member and a screw core according to a second embodiment of the screw core.

FIG. 6 is a side sectional view of a main part showing another example of a cast product.

[Explanation of symbols]

1 casting 2 molds 3 casting space 6 Upper mold 7 Lower mold 16 screw holes 18 screw holes 20 Screw core (first embodiment) 25 Screw receiving member 26 Screw Core (Second Embodiment)

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Claims (4)

(57) [Claims] 1. A screw core (20) having a male screw shape with respect to a predetermined portion of a casting space (3) formed in a mold.
(26) is a mold holding the screw core
(20) A mold characterized in that both ends of (26) are held by the mold. 2. A screw receiving member (25) capable of disappearing at a temperature lower than the casting temperature is loaded in all or at least a portion including a screw hole forming position of the casting space (3) formed in the mold, and the screw receiving member (25). member (25) screw core having a male screw shape to a predetermined position of (26) is held, and in the screw
A mold characterized in that both ends of the child (26) are held by a mold or the like . 3. The mold according to claim 1, wherein the screw cores (20) (26) are made of a carbon-based material. 4. A carbon-based material having a male screw shape at a predetermined position of a casting space (3) formed in the mold.
And a gas passage (26
a) is molded with the threaded cores (20) (26) through which it is formed , held, and then cast, and then the cast product (1) is taken out, and the screw is removed from this cast product (1). A casting method characterized in that the cores (20) (26) are collapsed and removed.