JP3668868B2 - Cap nut casting method and cast member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of casting a cap nut so as to be flush with a cast product cast by a full mold method, and a cast-in member used for casting the cap nut.
[0002]
[Prior art]
For example, when casting a heavy object such as an upper mold, a lower mold, or a pad by a full mold method, it is common to cast a cap nut for screwing a suspension such as a suspension bolt or an eye bolt.
By the way, the cap nut described above usually needs to be cast so as not to protrude from the side surfaces of the upper mold, the lower mold, the pad, etc., which are cast products, that is, to be flush with the cast product. For this reason, conventionally, as shown in FIG. 3, the cap nut 3 is fitted and fixed to the hole 2 formed in the vanishing model 1 made of polystyrene foam so as to be flush, and the bolt 4 is screwed into the cap nut 3. Then, the lock nut 5 screwed to the bolt 4 is brought into close contact with the cap nut 3, and then the bolt 4 is embedded together with the lock nut 5 in a sand mold 6 formed by wrapping the disappearance model 1. By assembling the cap nut 3 in the mold in this way, at the time of casting, the lock nut 5 prevents the molten metal from entering the threaded portions of the cap nut 3 and the bolt 4, and the mold 4 is released after casting to lock the bolt 4 When the nut 5 is removed, as shown in FIG. 4, the cap nut 3 is cast so as to be flush with the cast product 7 replacing the vanishing model 1, and is used for screwing the lifting tool as it is. Will be able to.
[0003]
[Problems to be solved by the invention]
However, according to the assembly structure of the cap nut 3 in the mold, since the end surface of the cap nut 3 is abutted against the sand mold 6, a gap is generated in the mating portion due to poor adhesion or poor sanding. In many cases, the molten metal is inserted into the gap during casting and the lock nut 5 is welded to the cap nut 3. Further, when a small-diameter screw such as M12 or M20 is used as the cap nut 3, the lock nut 5 is overheated and partially melted by the heat of the molten metal at the time of casting, and its peripheral portion A is welded to the cap nut 3. It also occurred. If such welding occurs, it will be difficult to remove the lock nut 5 and the bolt 4, and if it is removed forcibly, the female screw of the cap nut 3 will be damaged and complicated post-processing will be required. This has been a major cause of lowering the performance and increasing the manufacturing cost.
[0004]
The present invention has been made in view of the above-mentioned problems, and the problem is to prevent troubles caused by welding in advance, thereby greatly contributing to improvement of productivity and reduction of manufacturing cost. It is an object of the present invention to provide a cap nut casting method and to provide a casting member used in the casting method.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a cap nut casting method according to the present invention is a casting method in which a cap nut is cast so as to be flush with a cast product cast by a full mold method. It is formed in a longer length, and the extension portion is hermetically plugged and embedded in a sand mold surrounding the disappearance model, and after the casting and mold release, the extension portion of the cap nut is removed.
In the casting method of the cap nut performed in this way, the end surface of the cap nut cast into the cast product is flush with the cast product by removing the extended portion of the cap nut after casting and releasing the mold. And since the extension part of the cap nut is embedded in the sand mold, the molten metal does not enter the screw portion of the cap nut, and the lock nut is unnecessary, so there is a concern about welding due to overheating. There is no need to do.
[0006]
In this casting method, the method of removing the extension portion of the cap nut is optional, but a notch is formed in advance on the outer peripheral surface of the cap nut, and after casting and mold separation, an external force is applied to the extension portion of the cap nut. It is desirable that the extended portion be sheared away from the notch as a starting point.
Further, in the cast-in method, a bolt may be used as a plug member sealed with the cap nut, and the cap nut may be supported by a sand mold through the bolt.
[0007]
On the other hand, the cast-in member according to the present invention is a cap nut-shaped cast-in member that is cast into a cast product cast by the full mold method, and is embedded in a sand nut that surrounds the cap nut part embedded in the disappearance model and the disappearance model. It is characterized by comprising an extended cylinder part to be inserted, and provided with a V-shaped annular notch at the boundary between the cap nut part and the extension cylinder part on the outer peripheral surface.
In such a cast-in member, when the casting is finished, the cap nut portion is cast into a cast product that replaces the disappearance model, while the extension tube portion projects from the cast product. After releasing, when an external force is applied to the extension cylinder, the extension cylinder easily shears starting from the V-shaped annular notch, and the end face of the cap nut cast in the casting is cast. It becomes the same as the product.
In this case, the internal screw hole is stepped with a large diameter on the opening end side, and the stepped portion of the screw hole is set at a position slightly deviated toward the main body side from the installation site of the notch. It can be a structure.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0009]
1 and 2 show one embodiment of a cap nut casting method according to the present invention. In addition, since the casting form by the full mold method is the same as the conventional one, the same reference numerals are given to the same parts as those shown in FIGS. In the present embodiment, a cap nut-like cast-in member 10 to be cast in a casting 7 cast by the full mold method is prepared separately. The cast-in member 10 includes a cap nut portion 11 fitted and fixed in the hole 2 of the disappearance model 1 and an extension cylinder portion 12 embedded in the sand mold 6 surrounding the disappearance model 1. An annular notch 13 having a V shape is formed at a boundary portion between the cap nut portion 11 and the extension tube portion 12. Further, a stepped screw hole 14 formed by connecting a small diameter female screw 14 a and a large diameter female screw 14 b is formed inside the cast-in member 10. The step portion 15 of the stepped screw hole 14 is set at a position slightly deviated toward the cap nut portion 11 side with respect to the installation portion of the notch 13, whereby a large portion of the cast-in member 10 in the cap nut portion 11 is set. Is provided with a small-diameter (regular) female screw 14a, and a large-diameter female screw 14b is disposed in the extension cylinder portion 12, respectively.
[0010]
In casting, first, the cast-in member 10 is fitted and fixed in the hole 2 formed in the disappearance model 1. In this fitting and fixing, an adhesive is applied in advance to the outer peripheral surface of the cap nut portion 11 of the cast-in member 10, and the cap nut portion 11 is inserted into the hole 2 until it is bottomed (FIG. 1). As a result, the cast-in member 10 is firmly fixed to the disappearance model 1 via the adhesive, and in this state, the annular notch 13 is positioned at a position where it matches the side surface of the disappearance model 1. Next, a bolt 16 is screwed to the extension cylinder portion 12 of the cast-in member 10. As the bolt 16, a bolt having a long neck length is selected, and the tip of the bolt 16 is screwed into the female screw 14 b to a site slightly deviated from the installation site of the annular notch 13 toward the opening end side of the cast-in member 10. . Thereby, the bolt 16 is positioned in a state in which the head side largely protrudes from the cast-in member 10.
[0011]
Next, the vanishing model 1 on which the cast-in member 10 and the bolt 16 are mounted is surrounded by a mold (not shown), and the sand mold 6 is formed by filling the mold with casting sand. By this molding, the extended cylindrical portion 12 of the cast-in member 10 and the bolt 16 screwed thereto are embedded in the sand mold 6, and the cast-in member 10 is firmly supported by the sand mold 6 via the bolt 16. This completes the mold. At this time, sand also enters the annular notch 13 of the cast-in member 10, and the notch 13 is also embedded in the sand mold 6 (FIG. 1).
[0012]
Next, molten metal is poured into the mold (sand mold 6). Then, the foamed polystyrene constituting the disappearance model 1 is combusted and vaporized, and a cast product 7 is formed in place of the disappearance model 1, whereby the cap nut portion 11 of the cast-in member 10 is cast into the cast product 7. (FIG. 2). At this time, since the cylindrical member 12 of the cast-in member 10 is embedded in the sand mold 6, the molten metal does not enter the screw hole 14 of the cast-in member 10. Further, since there is no lock nut 5 (FIGS. 3 and 4) that has been indispensable in the past, there is no need to worry about welding due to overheating.
[0013]
Thereafter, when the sand mold 6 is separated, the extended cylindrical portion 12 and the bolt 16 of the cast-in member 10 are exposed, and further, the annular notch 13 on the outer peripheral surface of the cast-in member 10 is exposed by performing shot blasting or the like. When the head of the bolt 16 is struck with a hammer or the like as shown in FIG. 2 after the completion of the mold separation, the extension cylinder portion 12 of the cast-in member 10 shears (breaks) starting from the bottom of the notch 13. Thus, the cap nut portion 11 of the cast-in member 10 remains in the cast product 7. Thus, since the notch 13 serving as the shearing portion is positioned at a position aligned with the side surface of the disappearance model 1 as described above, the end surface of the cap nut portion 11 serving as the shearing surface is flush with the casting 7. Therefore, the cap nut portion 11 is in a state of being cast with the casting 7 in the same form as the conventional cap nut 3 (FIGS. 3 and 4). In this case, there is no fear of welding due to overheating as described above, so that it is possible to use small-diameter screws such as M12 and M20, and the application range as a cap nut is expanded.
[0014]
Particularly in the present embodiment, after casting, the extra length portion (extension tube portion 12) of the cast-in member 10 and the bolt 16 can be removed by simply hitting the head of the bolt 16 with a hammer or the like. Thus, the troublesome work of removing the lock nut 5 and the bolt 4 using a tool (hexagonal wrench) after casting becomes unnecessary, and the efficiency of the work and the productivity are improved.
In addition, since the cast-in member 10 is supported by the sand mold 6 via the bolts 16, the support of the cast-in member 10 is ensured even if the extension cylinder portion 12 of the cast-in member 10 is set to be short, and the cast member 10 is cast. Since the entire length of the wrapping member 10 can be shortened, its manufacture becomes easy. Further, since the screw hole 14 provided in the cast-in member 10 is stepped and the stepped portion 15 is set at a position slightly deviated toward the bag nut portion 11 side from the installation portion of the notch 13, the bottom wall of the notch 13 is set. The thickness is reduced, and shearing of the extension cylinder portion 12 of the cast-in member 10 after casting becomes easier. Moreover, even if burr is generated during this shearing, the burr is present in the large-diameter female screw 14b, so that a hanger such as a hanger bolt or an eyebolt with respect to the screw hole 14 on the side of the cap nut portion 11 is used. There is no obstacle to installation.
[0015]
In the above embodiment, the cast-in member 10 is supported by the sand mold 6 via the bolts 16. However, when the extended cylinder portion 12 of the cast-in member 10 is formed long, the extended cylinder Only by embedding the portion in the sand mold 6, the support of the cast-in member 10 is sufficient, and the bolt 16 can be omitted. However, since the bolt 16 also functions as a plug member that prevents sand from entering the cast-in member 10, if this is omitted, the bolt 16 replaces the bolt 16 at the opening end of the cast-in member 10. It is necessary to seal the plug member.
[0016]
【The invention's effect】
As described above, according to the method for casting a cap nut according to the present invention, the cap nut can be efficiently cast so as to be flush with the cast product without causing troubles due to welding and production. This greatly contributes to improvement in performance and reduction in manufacturing costs.
In addition, according to the cast-in member according to the present invention, since it has a simple shape by merely providing a notch in a part of the outer peripheral surface of the cap-nut-shaped member, it is suitable for the implementation of the cast-in method. Become.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a mold structure for carrying out a cap nut casting method according to the present invention.
FIG. 2 is a cross-sectional view showing a processing state after casting in the cast-in method.
FIG. 3 is a cross-sectional view showing a mold structure for carrying out a conventional cap nut casting method.
FIG. 4 is a cross-sectional view showing a processing state after casting in a conventional casting method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vanishing model, 6 Sand mold 10 Cast-in member 11 Cap nut part 12 Extension cylinder part 13 Notch 14 Stepped screw hole, 15 Step part 16 Bolt

Claims (5)

  In a casting method in which a cap nut is cast so as to be flush with a cast product cast by a full mold method, the cap nut is formed longer than a specified length, and an extended portion thereof is placed in a sand mold surrounding the disappearance model. A method for casting a cap nut, wherein the cap nut is removed after the cap nut is embedded and sealed, cast and released.   2. A notch is formed in advance on the outer peripheral surface of the cap nut, and after casting and releasing the mold, an external force is applied to the extension portion of the cap nut, and the extension portion is sheared and removed from the notch as a starting point. The cast-in method described in 1.   3. The casting method according to claim 1 or 2, wherein a bolt is used as a plug member sealed with the cap nut, and the cap nut is supported on the sand mold through the bolt.   A cap nut-like cast-in member that is cast into a cast product cast by the full mold method, and is composed of a cap nut portion embedded in the disappearance model and an extension cylinder portion embedded in a sand mold surrounding the disappearance model. A cast-in member having an annular notch formed in a V shape at a boundary portion between the cap nut portion and the extension tube portion.   The internal screw hole is stepped with a large diameter on the opening end side, and the stepped portion of the screw hole is set at a position slightly deviated toward the main body side from the installation part of the notch. The cast-in member according to claim 4.

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