JPH04145210A - Manufacturing method for bolts with built-in washers - Google Patents

Abstract

PURPOSE:To attain large strength and highly accurate outer diameter measure without the slip-off of a washer by press-fitting a split spring washer to a bolt column part between a bolt head and a serration formed at the bolt column part in such a way as to protrude slightly from the outer diameter of the bolt column part. CONSTITUTION:A short serration 4 protruding slightly from the outer diameter of a bolt column part 2 continuous from a bolt head part 1 is formed at the bolt column part 2, and a split spring washer 6 is press-fitted between the bolt head part 1 and the serration 4. The press-fitted spring washer 6 is therefore prevented from slipping off. Bolts of large strength and excellent outer diameter measure accuracy can be therefore obtained and also mass-produced easily at low cost.

Description

[Detailed description of the invention]

[0001]

[Industrial application field]

The present invention relates to a method for manufacturing washer-installed bolts that can be used to mass-produce washer-installed bolts with spring washers installed in advance at low cost. [0002]

[Conventional technology]

Conventional washer-installed bolts used when assembling automobile parts usually have a washer temporarily attached to the bottom of the bolt head with adhesive, but the washer tends to fall off during transportation. It had the disadvantage of poor workability. In addition, a washer is fitted into the cylindrical part of the bolt between the bolt head and the male thread, and a ring-shaped raised part is formed on the cylindrical part of the bolt, and the washer is supported by this raised part. This can be seen in Japanese Publication No. 57-53111, etc., but such a method has problems such as stress concentration in the recess formed to provide the ring-shaped protuberance, which tends to reduce the strength of the bolt. It was left behind. Furthermore, in recent years, in a bolt manufacturing method in which the bolt head and the following bolt cylindrical part are forged from bolt material and a male threaded part is rolled on the front part of the bolt cylindrical part, the bolt cylindrical part above the male threaded part is A method was developed in which a washer was fitted and serrations extending in the axial direction of the bolt were carved over a predetermined length, and the washer between the serration and the bolt head was held by the serrations.
Although it is disclosed in the above publication, the work of carving serrations over a predetermined length so as to extend in the axial direction of the bolt after fitting the washer to the cylindrical part of the bolt requires considerable labor and is inexpensive because the washer moves. It could not be mass-produced. [0003]

[Problem to be solved by the invention]

The present invention solves the above-mentioned conventional problems, and aims to provide a method for manufacturing a washer-embedded bolt that is easy to mass-produce, has no fear of the washer falling off, has excellent strength, and has excellent accuracy in outer diameter dimensions. It is complete. [0004]

[Means for Solving the Problems] A method for manufacturing a washer-integrated bolt according to the present invention which attempts to solve the above-mentioned problems is to forge a bolt head and a bolt cylindrical portion following the bolt from a bolt material to form the bolt cylindrical part. In a bolt manufacturing method in which a male thread is rolled at the front end of the bolt, when the bolt head and the subsequent bolt cylindrical part are forged or when the male thread is rolled, a part of the bolt cylindrical part near the bolt head is rolled. Short serrations extending in the axial direction are simultaneously molded so that their tops slightly protrude beyond the outer diameter of the bolt cylindrical portion, and then a spring with a notch is inserted from the bolt tip into the bolt cylindrical portion between the serrations and the bolt head. The feature is that the washer is press-fitted. [0005] In the present invention, the process of forging the bolt head and the subsequent bolt cylindrical part from the bolt material, and the process of rolling a male threaded part on the front part of the bolt cylindrical part are no different from conventional bolt manufacturing methods. Never. In addition, the short serrations extending in the axial direction are formed in the part of the cylindrical part of the bolt near the bolt head so that the top of the serrations slightly protrudes beyond the outer diameter of the cylindrical bolt part. By forming the serrations in advance, the serrations may be forged at the same time as the bolt cylindrical part is forged, or the serrations may be rolled when the male thread part is rolled after the bolt head and the following bolt cylindrical part are forged. It is also possible to form a serration processing part on the die so that the serrations are rolled at the same time as the male thread part is rolled, but in any case, the serrations only need to have a bolt holding function, so they can be short.
For this reason, there is almost no burden on heading or rolling processing. [0006] At the same time as the forging of the cylindrical part of the bolt or the rolling of the externally threaded part, short serrations extending in the axial direction are added to a portion of the cylindrical bolt part near the bolt head, the top of which is slightly larger than the outer diameter of the cylindrical bolt part. Once the bolt has been formed to protrude, a spring washer with a notch may be press-fitted from the tip of the bolt into the cylindrical part of the bolt between the serrations and the bolt head beyond the male threaded part and the serrations. [0007]

【Example】

Next, an embodiment of the present invention will be described in detail with reference to the washer assembly bolt shown in the drawings. 1 is a bolt head, and 2 is a bolt cylindrical portion following the bolt head 1. The bolt head 1 and the bolt cylindrical portion 2 following this are made of a bolt material such as a coil wire material by a well-known cold heading method. Shape more. Reference numeral 3 denotes a male threaded portion formed on the peripheral surface of the tip end of the bolt cylindrical portion 2 by a well-known rolling method, and the outer diameter of the bolt cylindrical portion 2 is slightly larger than the outer diameter of the male threaded portion 3. . The bolt head 1 and the bolt cylindrical part following it are forged by a well-known cold heading method, and then passed through a well-known rolling die to form the male threaded part 2. Short serrations 4 carved in the axial direction of the bolt are formed in a part of the bolt cylindrical part 2 near the bolt head 1. The length of the serration 4 is that the total length of the bolt is 95 mm, and the outer diameter of the bolt cylinder part (2) is 1
In the case of 0 mm, it may be as short as about 6 mm. The reason for this is that the shorter the serrations 4, the easier the heading or rolling, and the serrations 4 only need to have the function of holding a spring washer 4, which will be described later. The top 5 of the serrations 4 is slightly protruded by about 0.1 mm on one side from the outer diameter of the bolt cylinder 2, and the serrations are rolled on the bolt cylinder 2 between the serrations 4 and the bolt head 1. In order to press-fit the spring washer 6 with a cut after this, the inner diameter of the spring washer 6 is set to be smaller than the outer diameter of the bolt cylindrical part 2, but smaller than the diameter of the top part 5 of the serrations 4. The spring washer 6 is fitted from the tip of the bolt, the slit of the spring washer 6 is opened, and the slit of the spring washer 6 is pressed into the bolt cylindrical portion 2 between the serration 4 and the bolt head 1, passing over the male threaded portion 3 and the serrations 4, and then the slit is closed and the serration is removed. The spring washer 6 is prevented from falling off by the top 5 of the spring 4. [0008]

[Effect]

The bolt with built-in washer manufactured in this way can be assembled by inserting the bolt cylindrical part 2 into the mounting part, screwing the male thread part 3 into the bolt hole of the mounted part, and tightening it. The spring washer 6 press-fitted into the part close to the bolt head 1 is pressed between the lower surface of the bolt head 1 and the mounting part and deforms into a flat shape, producing a bolt loosening effect similar to that of conventional washer-integrated bolts. However, in the product obtained according to the present invention, the spring washer 6 is prevented from falling off by the top part 5 of the serration 4, so unlike the conventional product in which the washer was temporarily attached with adhesive, the spring washer 6 does not fall off during transportation etc. 6 will never fall off. Furthermore, unlike the ring-shaped protuberances of conventional washer-integrated bolts, the serrations 4 extend in the axial direction of the bolt, so even if the unevenness is made shallow, the spring washer 6 can be reliably prevented from falling off. In addition, since the cross-sectional area of the shaft section is open to the parts other than the serrations 4, the strength of the bolt cylindrical part 2 does not decrease due to stress concentration. Since the grooves are carved in the portion of the bolt cylindrical portion near the bolt head at the same time as the rolling of the bolt cylindrical portion 2, deterioration in accuracy of the outer diameter dimension of the bolt cylindrical portion 2 can be kept to a minimum. [0009]Furthermore, the characteristic configuration of the product obtained by the present invention is that a spring washer 6 having a cutout is used as a washer, and the serrations 4 are shortened. For the first time, it will be possible to solve the most demanding problem in the current bolt industry, which is mass production at low cost. In other words, the short serrations 4 extending in the axial direction can be easily formed at the same time as forging the bolt or rolling the male threaded portion 3, so there is no need to add a special process.Moreover, the spring washer 6 has a diameter larger than the inside diameter of the washer. If the bolt with the serrations 4 is forcibly press-fitted from the bolt tip side, the top of the short serrations 4 will easily deform when the serrations 4 are at full size, and the spring washer 6 with the notch will be easily and accurately placed in the required location with a small press-fitting load. Not only can it be press-fitted, but it can also contribute to improving the accuracy of the outer diameter dimension. [0010]

【Effect of the invention】

As is clear from the above description, the present invention provides a spring washer that is forcibly press-fitted beyond the short serrations formed on the bolt cylindrical portion when forging the cylindrical portion of the bolt or rolling the male threaded portion. Bolts with built-in washers that prevent falling off, are strong, and have excellent accuracy in outer diameter dimensions can be easily mass-produced by simply making a slight modification to the heading or rolling dies used in the conventional bolt manufacturing process. The washer is temporarily attached to the underside of the bolt head with adhesive so that the washer does not fall off during transportation or assembly, and the bolt between the bolt head and the male thread is secure. In addition to fitting a washer into the cylindrical part of the bolt, a ring-shaped protuberance or serration is carved into the cylindrical part of the bolt so that the washer is retained by the protuberance or serrations, but the biggest drawback is the manufacturing problem. This solves the problem of the need for special jigs and labor to form the protrusions and serrations after fitting the washer into the cylindrical portion of the bolt while preventing the washer from moving, and has the advantage of being mass-produced at an extremely low cost. Therefore, the present invention greatly contributes to the development of the industry by eliminating the problems of the conventional method of manufacturing bolts with built-in washers. [0011]

[Brief explanation of the drawing]

FIG. 1 is a front view showing an example of a washer-integrated bolt manufactured according to the present invention.

[Explanation of symbols]

1 Bolt head Bolt cylinder part 2 Male thread part short serrations Spring washer with cutout

【Document name】

drawing [Zugetsu

Claims (1)

[Claims] Claim 1: A method for manufacturing a bolt, in which a bolt head and a bolt cylindrical part following the bolt head are forged from a bolt material, and a male threaded part is rolled in a forward part of the bolt cylindrical part, wherein During heading of the cylindrical part of the bolt or rolling of the male threaded part, a short serration extending in the axial direction is formed at the same time in the part of the cylindrical bolt part near the bolt head so that the top of the serration protrudes slightly beyond the outer diameter of the cylindrical bolt part. A method for manufacturing a washer-integrated bolt, characterized in that, next, a spring washer with a notch is press-fitted from the tip of the bolt into a cylindrical portion of the bolt between the serrations and the bolt head.