JPH06277778A - Die for producing painting removing bolt - Google Patents

Abstract

PURPOSE:To provide a painting removing bolt producing die which can produce a painting removing bolt having a precise screw thread without hardly generating a lack of a die thread. CONSTITUTION:A die thread 2 and a die root 3 for forming a screw thread of a bolt are formed in a fixed die 1, and a rectangular groove forming part 4 is fit in a groove forming part fitting space 5. The groove forming part fitting space 5 is inclined by an angle theta corresponding to a lead angle of the screw to a form rolling direction. Therefore, an upper boundary 5b of the groove forming part fitting space 5 is made parallel to the die thread 2, which is not made tapered form by being cut with the groove forming part fitting space 5. Further, a length L of the die thread and die root positioned on the rear part of the groove forming part 4 is formed longer than a conventional die so that the bolt 8 can be rolled by 1.5 turns, a built-up part of burr generated in forming the groove is corrected and the precision of the screw thread is guaranteed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die for producing a paint removing bolt, and more particularly to a die for rolling a bolt suitable for screwing on a painted nut.

[0002]

2. Description of the Related Art Conventionally, for example, in assembling an automobile,
A fastening method using a combination of a bolt and a welding nut is performed. This method is a method in which a through hole is formed in the tightening portion of the tightening material, a nut is welded to the back surface side, the materials to be tightened having the through hole are overlapped, and the bolt is tightened. By welding the nut 2 in advance, it is not necessary to prevent the nut from rotating during the fastening work, which is a method that can improve workability. In this method, as a normal process, a nut is attached to a body or the like by welding, painting is performed, and then each portion is fastened with a bolt. Therefore,
At the time of painting, the coating film accumulates inside the nut, and when tightening with bolts, the coating film becomes resistance, which causes an abnormal increase in screwing torque and when the bolt is caught in the nut. The bolts tend to fall down when meshing, and if they are forcibly screwed in as they are, abnormal meshing occurs, causing the threads of the bolts or nuts to be crushed.

In order to cope with the above-mentioned problems, a paint removal bolt having a structure for the purpose of fastening and tightening while peeling off the coating film accumulated inside the nut at the tip of the bolt is used. 5A and 5B show an example of a bolt having such a structure, FIG. 5A is a side view, and FIG. 5B is an enlarged side view of the vicinity of the tip portion. In the figure, 11 is a bolt, 12 is a thread portion, 13 is a guide portion, and 14 is a groove portion. The bolt 11 has a guide portion 13 formed at the tip of the thread portion 12. In this example, the guide portion 13 is formed in a tapered shape. The groove portion 14 is provided with a groove having a square cross section from the thread portion 12 to the tip of the guide portion 13.

Such a bolt is manufactured by rolling using a fixed die and a moving die. 2 and 3 are explanatory views of a die for manufacturing the bolt of FIG. 5, FIG. 2 is a fixed die, and FIG. 3 is a moving die. In the figure, 1 is a fixed die, 2 is a die die, 3 is a die valley, 4
Is a groove forming portion, 5 is a groove forming portion fitting space, 6 is a moving die,
7 is a bolt blank, and 8 is a rolled bolt. The die crests 2 form the bolt troughs and the die troughs 3 form the bolt crests. The die valley 3 is shown by a broken line in order to distinguish it from the die mountain 2. Further, the groove forming portion 4 called a rack is provided to form the groove described in FIG. 5, and the shape of the peaks and valleys is selected according to the shape of the groove formed in the bolt. It Groove forming part 4
Although it is configured as a separate body and is shown separately from the fixed die 1, it is used by being fitted into the groove forming portion fitting space 5 and integrated with the fixed die 1. The moving die 6 is the same as that used for manufacturing a normal bolt having no groove, and has a die peak 2 and a die valley 3.

In order to roll a bolt using the fixed die 1 and the moving die 6, a bolt blank 7 is inserted from the introduction side, and by moving the moving die 6, first, a screw is formed on the bolt blank 7 by rolling. Then, the groove is rolled in the groove forming portion 4. The bolt 8 rolled through the groove forming portion 4 is discharged through the die at the rear of the groove forming portion 4.

In such a rolling die, the die ridges 2 and the die valleys 3 for forming the threads are inclined by the lead angle with respect to the rolling direction (moving direction of the moving die). , In the die provided with the groove forming portion,
The die peak 2 and the die valley 3 are separated by the groove forming portion fitting space 5. At the boundary 5a in the groove forming portion fitting space 5 parallel to the rolling direction, as shown in FIG. 4, there is a problem that the die ridge 2 is tapered and easily chipped. Further, since the groove is formed by plastic deformation, the material pushed in by the groove forming portion 4 in the groove portion seems to be raised in the vicinity to cause burrs, and is formed before entering the groove forming portion 4. There is also a problem in that the formed thread is deformed and the outer diameter becomes large.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and is capable of producing a paint removal bolt having a highly accurate screw thread, in which chipping of a die is unlikely to occur. It is intended to provide a die for producing a bolt.

[0008]

According to the present invention, in a die for producing a paint removal bolt having a groove forming portion in a part of a die for forming a screw thread, a boundary parallel to the rolling direction in the groove forming portion is the above-mentioned. It is characterized in that it is parallel to the groove of the thread die, and in the above die,
It is also characterized in that the die for forming the thread at the rear portion of the groove forming portion is formed over the length of one rotation of the bolt or more.

[0009]

According to the present invention, since the boundary parallel to the rolling direction in the groove forming portion is parallel to the groove of the thread die, the die thread at the boundary portion is not divided and a chip is generated. Can be prevented. Further, since the die for forming the screw thread in the rear portion of the groove forming portion is formed over the length of one rotation of the bolt or more,
The threaded portion in which the groove is formed is rolled again over the entire circumference, so that the deformation of the screw when forming the groove can be corrected.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view for explaining an embodiment of a die for producing a paint removal bolt of the present invention.
Is a plan view of the fixed die, FIG. 1 (B) is a sectional view taken along line BB, and FIG. 1 (C) is a sectional view taken along line CC of the groove forming portion 4. In the figure, the same parts as those in FIG.
The moving die is similar to that described in FIG. In this embodiment, the groove forming portion 4 is formed in a rectangular shape, and therefore the angles of the corners are all 90 °. The groove forming portion fitting space 5 is configured to be inclined by an angle θ with respect to the rolling direction. That is, 5b and 5c, which are substantially orthogonal to the rolling direction, are inclined by an angle θ with respect to a plane orthogonal to the rolling direction, and 5a which is parallel to the rolling direction is also inclined by an angle θ with respect to the rolling direction. This angle θ is chosen to be equal to the lead angle of the screw. For example, if the nominal diameter is 10 mm and the pitch is 1.25 mm, the lead angle is 2 ° 31 ′, so the angle θ is selected to be 2 ° 31 ′. By doing so, the boundary at which the groove forming portion 4 is parallel to the rolling direction, that is, the boundary 5a at the upper portion of the groove forming portion fitting space 5 is parallel to the die peak 2 and the die valley 3. Therefore, the die crest 2 is not tapered by the groove forming portion fitting space 5. In addition, as shown in FIG.
Preferably starts from the thread root of the bolt 11. Therefore, the boundary parallel to the rolling direction of the groove forming portion fitting space 5 in the fixed die 1 is preferably the top of the die mountain.

The length of the groove forming portion in the rolling direction is the length of one rotation of the bolt. In this embodiment, the crests for forming the grooves are formed so as to have a flat portion in the middle between the angles of inclination of 15 ° and 51 °, and five inclines are formed. Therefore, the groove of the rolled bolt 8 is inclined with respect to the axial direction, and five grooves are formed on the entire circumference.

In the die 1, the length L of the portion where the die ridges and the valleys are formed at the rear portion of the groove forming portion 4 is larger than that of the conventional die so that the bolt 8 rolls 1.5 turns. It is formed long. As a result, the bolt 8 having the groove formed is rolled for 1.5 rotations,
Burrs, such as burrs, created by the formation of grooves are corrected and the thread accuracy is guaranteed. It will be apparent from this description that the length L requires a minimum length of one rotation of the bolt. In the experiment, the vicinity of the value for 1.5 rotations was suitable.

In the above-described embodiment, the groove forming portion 4 has a rectangular shape, and the groove forming portion fitting space 5 is substantially orthogonal to the rolling direction 5.
b and 5c were tilted. Therefore, when the groove forming portion 4 is attached to the groove forming portion fitting space 5, the lower surface of the groove forming portion 4 (lower side of the figure) and the lower surface of the fixed die 1 (lower side of the figure) are θ.
Will have an angle of, which will cause a step. When the groove forming portion 4 is attached to the groove forming portion fitting space 5 in order to prevent a step portion from being formed, the lower surface of the groove forming portion 4 and the lower surface of the fixed die 1 may be flush with each other.

Further, the side surfaces 5b, 5 of the groove forming portion fitting space 5 are
c may be orthogonal to the lower surface of the fixed die 1, and the angle θ in FIG. 1 may be zero. Alternatively, another suitable angle other than 0 may be used. However, 5a parallel to the rolling direction
Must be inclined by an angle θ with respect to the rolling direction. Of course, this angle θ is chosen to be equal to the lead angle of the screw.

Although the embodiment of FIG. 1 has been described as a fixed die, it may be a movable die. In that case, the movable die as described in FIG. 3 may be used on the fixed die side.

[0016]

As is clear from the above description, according to the paint removing bolt manufacturing die of the present invention, it is possible to provide a die which is less likely to be chipped in the die mountain at the boundary with the groove forming portion, and to have high accuracy. There is an effect that it is possible to provide a die for manufacturing a paint removing bolt that can manufacture a paint removing bolt having a screw thread.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of a die for producing a paint removal bolt of the present invention.

FIG. 2 is an explanatory view of a conventional fixed die for manufacturing a paint removal bolt.

FIG. 3 is an explanatory view of a conventional moving die for manufacturing a paint removing bolt.

FIG. 4 is an enlarged view of a part of a fixed die for manufacturing the mounting bolt of FIG.

FIG. 5 is a side view of an example of a paint removal bolt.

[Explanation of symbols]

 1 Fixed Die 2 Die Mountain 3 Die Valley 4 Groove Forming Part 5 Groove Forming Part Fitting Space 6 Moving Die 7 Bolt Blank 8 Rolled Bolt

Claims (2)

[Claims] 1. A die for producing a paint removal bolt having a groove forming portion in a part of a die for forming a screw thread, wherein a boundary of the groove forming portion parallel to the rolling direction is parallel to the groove of the screw thread die. Die for manufacturing paint removal bolts characterized by being present. 2. The die for producing a paint removal bolt according to claim 1, wherein the die for forming the thread at the rear portion of the groove forming portion is formed over the length of one rotation of the bolt or more. .