JP4605517B2 - Cap nut manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a cap nut.
[0002]
[Prior art]
Conventionally, as a method of manufacturing a cap nut, for example, a nut member including a nut body and a hollow cylindrical portion integrally formed on the head side of the nut body is molded, and a screw stand is applied to a screw lower hole of the nut body. After that, the nut member is rotated at a high speed, and a plurality of rollers rotating at a high speed in the opposite direction to the hollow cylindrical portion are pressed against the hollow cylindrical portion from the outside, and the top portion of the hollow cylindrical portion is deformed into a bag shape while deforming the top portion. It is known that a bag head is formed by welding, and then a burr generated at the welding top of the bag head is scraped off (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
JP-A-57-160586 (first page, FIG. 3)
[0004]
[Problems to be solved by the invention]
However, in the conventional method for manufacturing a cap nut described above, a portion (burr) that overlaps the front end portion of the hollow cylindrical portion, that is, the top portion of the bag portion, is generated when the bag head is formed by a plurality of rollers. For this reason, a step of scraping the overlapped portion is specially required as a post-process, and in addition, the scraped portion remains as a cut and has a problem that the appearance is deteriorated. In addition, the molding of the bag head by only the pressure contact from the outside of the plurality of rollers has a limit in the molding, and it is difficult to accurately mold the bag head of various shapes.
[0005]
Therefore, the present invention has an object to provide a method of manufacturing a bag nut that can easily and accurately form bag heads of various shapes and can manufacture beautiful bag nuts that do not have cutting or cutting scratches on the bag head. To do.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, first , the present invention provides a nut main body having a screw hole, and an inner hole integrally connected to the head side of the nut main body and having a diameter larger than the valley diameter of the screw hole. A nut blank body having a hollow cylindrical portion with a punch is driven by a punch into a mold having a curved concave portion at the back so that the tip of the hollow cylindrical portion follows the curved concave portion at the back in the die. To form a bag head with a hole remaining at the top, and then support the inner surface of the top of the bag head with a receiving punch having a curved convex portion at the tip, and a hole in the bag head Under the condition that the portion was heated to near the melting temperature in advance, the hole portion was hermetically welded by pressurizing the hole portion of the bag head from the outside with a pressure punch provided with a curved recess. It is characterized by.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, as shown in FIG. 1, a nut main body 2 having a screw lower hole 2a and a hollow that is larger in diameter than the screw main hole 2a integrally formed on the head side of the nut main body 2 and thinner than the nut main body 2. The nut body 1 composed of the cylindrical portion 3 is formed by appropriate means such as forging or cutting. Thereafter, as shown in FIG. 2, the screw hole 2 b is tapped in the screw lower hole 2 a of the nut body 2 in the nut body 1. In addition, when forming the nut body 1, if a hollow material having a through hole (hollow cutting blank of a predetermined length) is forged by a forging machine (not shown), a large amount of nuts can be easily and quickly formed. Since the raw material 1 can be formed, it is preferable.
[0011]
Next, as shown in FIG. 3, the nut body 1 is driven by a punch 6 into a mold 5 having a curved recess 5 a in the back, and the tip of the hollow cylindrical section 3 is curved in the mold 5. The bag head 4 is formed by bending along the recess 4a and leaving the hole 4a at the top. In FIG. 3, reference numeral 7 denotes a knockout pin that pushes the molded nut body 1 out of the mold 4.
[0012]
Thereafter, the hole 4a portion of the bag head 4 is heated in advance to near the melting temperature by a heating means (not shown) such as a heater, and then the bottom surface of the nut body 1 is extruded as shown in FIG. While being supported by the member / support member 8, the top side inner surface of the bag head 4 is supported by a receiving punch 9 having a curved convex portion 9a at the tip. Then, the hole 4a portion of the bag head 4 in the nut body 1 is pressurized from the outside with the pressure punch 10 having the curved recess 10a. The hole 4a is hermetically welded by this pressurization to form a cap nut N as a final product as shown in FIG. 4 and 5, reference numeral 11 denotes a base member.
[0013]
According to the above-described method for manufacturing a cap nut, the hole 4a of the bag head 4 is reliably hermetically welded by pressurizing the hole 4a of the bag head 4 in a state of being heated to near the melting temperature in advance. It is possible to manufacture a beautiful nut N with no cutting scratches or cutting scratches left at the top of the bag head 4 as well as at the top. Moreover, since the top portion of the bag head is hermetically welded while being formed in a predetermined shape by being sandwiched between the curved convex portion 9a of the receiving punch 9 and the curved concave portion 10a of the pressure punch 10, the top portion of the bag head 4 Can be formed accurately and easily according to the desired shape, that is, according to the shape of the curved concave portion 10 a of the pressure punch 10. In addition, since the bag head 4 portion of the nut body 1 is heated in advance by appropriate heating means such as a heater and hermetically welded under heat or warm, hermetic welding of the hole 4a is performed. It can be done quickly and easily.
[0014]
In addition, if an indentation concave / convex portion such as a trademark, size, or number is provided on the inner surface of the pressure punch 10, the trademark, size, number, Etc., and is effective for discrimination during use, advertising and the like.
[0021]
【The invention's effect】
As described above, according to the method for manufacturing a cap nut of the present invention, first, the tip of the hollow cylindrical portion in the nut blank is bent along the curved concave portion at the back of the mold, and the hole is formed at the top. the remaining molding a bag head, then Fukuroatama a hole portion of the bag head remains as unshaped pre under a state of being heated to the melting temperature near at pressing punch having a curved recess Since the hole is hermetically welded by pressurizing the hole part of the part from the outside, a beautiful cap nut with no cutting or cutting flaws remaining on the top part as well as the side part of the bag head is manufactured. be able to. Moreover, since the receiving punch having the curved concave portion that receives the inner surface of the bag head when the hole portion of the bag head is hermetically welded by the pressure punch, the curved convex portion of the receiving punch and the pressure punch are provided. The top part of the bag head can be sealed and welded while being shaped into a predetermined shape by sandwiching the top part of the bag head with the curved concave part, whereby the top part of the bag head is shaped according to the predetermined shape, that is, the curved shape of the pressure punch It can be formed accurately and easily according to the shape of the recess. In addition, if an indentation, such as a trademark, size, number, etc., is provided on the inner surface of the pressure punch, the trademark, size, number, etc. It is effective for discrimination during use, advertising, etc.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a nut body used in the present invention.
FIG. 2 is a vertical cross-sectional view of a nut element body that has been tapped.
FIG. 3 is a longitudinal sectional view of a nut body having a bag head with a hole.
FIG. 4 is a longitudinal sectional view before the start of hermetic welding of a hole by a pressure punch.
FIG. 5 is a longitudinal sectional view at the end of hermetic welding of a hole with a pressure punch.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Nut base body 2 Nut main body 2b Screw hole 3 Hollow cylindrical body 4 Bag head part 4a Hole 9 Receiving punch 9a Curved convex part 10 Pressure punch 11a Curved concave part N Cap nut

Claims (1)

First, a nut material body including a nut body having a screw hole and a hollow cylindrical portion integrally provided on the head side of the nut body and having an inner hole larger in diameter than the valley diameter of the screw hole. A bag head that is punched into a mold having a curved recess at the back, and the tip of the hollow cylindrical part is bent along the curved recess at the back of the mold, leaving a hole at the top. And then supporting the inner surface of the top portion of the bag head with a receiving punch having a curved convex portion at the tip and heating the hole portion of the bag head to near the melting temperature in advance. A method for producing a cap nut, wherein the hole portion is hermetically welded by pressurizing the hole portion of the bag head from the outside with a pressure punch provided with a curved concave portion.

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