JP2542275Y2 - Bolt with pilot - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bolt used for tightening an impact wrench, a robot or the like in, for example, a process of assembling an automobile part, and more particularly to a bolt with a pilot for preventing oblique screwing.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional bolt 100 of this type. The bolt 100 has a head portion 101 and a shaft portion 102, and the shaft portion 102 has a female screw 1 of a mating member 103.
A normal thread 105 to be screwed to the thread 04 is formed. A pilot 106 having an axis (not shown) aligned with the axis of the shaft 102 is provided on the distal end side of the axis 102.

The pilot 106 has a guide thread 10
7 is formed. Outer diameter d1 of this guide screw thread 107
Is set equal to or slightly smaller than the inner diameter d2 of the female screw 104. Also, the root diameter d3 of the guide screw thread 107
Is usually set smaller than the root diameter of the thread 105. Furthermore, the thread angle θ1 of the guide thread 107
Is set substantially equal to (about 60 °).

[0004] The bolt 100 having the above-described structure is attached to the mounting member 10.
8 and 109 are inserted into the insertion holes 110 and 111, and the guide thread 107 is locked to the female screw 104 of the mating member 103 as shown in FIG.

After that, when the bolt 100 is rotated using an impact wrench (not shown), the guide screw thread 107 moves along the female screw 104, so that the straightness of the bolt 100 with respect to the mating member 103 is maintained, and further, the shaft portion 1
02 is screwed into the female screw 104 to complete the tightening.

[0006]

However, the conventional bolt 100 has the following problems. Since the root diameter d3 of the guide screw thread 107 is set to be smaller than the root diameter of the normal screw thread 105, the material 200 before thread processing is used.
The difference between the diameter d4 of the shaft portion 106 and the diameter d5 of the pilot 102 is extremely large. For this reason, in the cold plastic working step of obtaining the material 200 of (C) from the rod-shaped material having the same diameter,
It was difficult to draw the boundary portion 201 between the shaft portion 102 and the pilot 106, and the processing time was increased, resulting in poor production efficiency.
Since the root diameter d3 of the guide screw thread 107 is usually set smaller than the root diameter of the screw thread 105, there is a very wide space for the female screw 104 of the mating member 103.

[0007] Therefore, when the pilot portion 106 is inserted into the mating member 103, it is greatly inclined, and there is a possibility that the straightness of the bolt 100 with respect to the mating member 103 is lost and oblique screwing occurs.

The present invention has been made to solve the above-mentioned problem, and the drawing process at the boundary between the shaft and the pilot is easy.
Moreover, it is an object of the present invention to provide a pilot bolt with which straightness with respect to a mating member can be easily maintained.

[0009]

In order to achieve the above object, according to the present invention, a normal thread which is screwed into a female thread of a mating member is formed on a shaft, and the shaft is formed on a tip end side of the shaft. A pilot having a portion and an axis aligned with each other is provided, and the pilot is formed with a guide thread continuous with the normal thread, and the root diameter of the guide thread is within an allowable dimension of the root diameter of the normal thread. And the outer diameter of the guide thread was set to be larger than the inner diameter of the female thread.

[0010]

According to the present invention based on the above configuration, the guide thread of the pilot is screwed into the female screw of the mating member, thereby maintaining the straightness of the mating member. Since the root diameter of the guide screw thread is usually set within the allowable range of the root diameter of the screw thread, the difference between the diameter of the shaft part and the diameter of the pilot in the cold plastic working process of the material is relatively small. Easy to do.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows a first embodiment. In FIG. 1, reference numeral 1 denotes a bolt with a pilot according to the present invention. The bolt 1 has a head 2 and a shaft 3. The head 2 has a hexagonal shape in the figure, but may have a hexagonal hole, or may have a slidable shape. The shaft 3 has a mating member (engine body, nut, etc.)
Normal thread 6 set to the size that can be screwed into the 4 internal thread 5
Is formed.

A pilot 7 whose axis (not shown) coincides with the axis of the shaft 3 is provided at the tip end of the shaft 3.
The length of the pilot 7 is usually 50 times the nominal diameter of the thread 6.
About 80% is preferable. And to pilot 7,
A guide thread 8 continuous with the normal thread 6 is formed. The root diameter D1 of the guide thread 8 is usually the root diameter D of the thread 6.
2, while the outer diameter D3 of the guide screw thread 8 is set larger than the inner diameter D4 of the female screw 5. Further, the thread angle θ2 of the guide screw thread 8 is set to approximately 90 °.

In this embodiment, the reference dimensions of each part of the bolt 1 and the mating member 4 are set to the values shown in Table 1.

[0014]

[Table 1] The bolt 1 is manufactured as follows. That is, first, a columnar material (not shown) is subjected to cold plastic working, specifically, is inserted into a hole of a die and extruded,
As shown in FIG. 2 (B), the shaft portion 3 and the pilot 7 are drawn to a predetermined diameter and used as the drawing material 10. A chamfer 13 is formed at the tip of the pilot section 7. At this time, in the bolt 1 of the present invention, the root diameter D1 of the guide screw thread 8 is set within the allowable dimension of the root diameter D2 of the normal screw thread 6, and the thread angle θ2 is about 90 °. The diameter D7 of the shaft portion 3 and the diameter D of the pilot 7
The difference from 8 is relatively small. Accordingly, drawing from the material to the material 10 can be easily performed in a short time, and the production efficiency is improved.

In the raw material 10 thus obtained, normal threads 6 and guide threads 8 are rolled by a combination of a normal thread dice and a guide thread dice (not shown).

The bolt 1 is inserted into the insertion hole 12 of the mounting member 11.
When the front end of the pilot 7 is brought into contact with the mating member 4 and rotated using an impact wrench or the like, the guide screw thread 8 advances along the female screw 5. Since the root diameter D1 of the guide screw thread 8 is normally set within the allowable range of the root diameter D2 of the screw thread 6, the bolt 1 is unlikely to be inclined, so that the axial center of the female screw 5 and the axial center of the bolt 1 are different. Roundness is maintained.
In the first embodiment, since the peak angle θ2 is set to about 90 °, the function of suppressing the inclination of the bolt 1 is excellent, and the insertability is good.

In this case, the bolt 1 may actually be slightly inclined as shown in FIG.
And the guide thread 8 have good fitting properties. When the bolt 1 is further rotated, the pitch of the female thread 5 matches the pitch of the normal thread 6, so that the normal thread 6 smoothly engages with the female thread 5, as shown in FIG. The head 2 is the mounting member 1
1 and the tightening is completed. Therefore, quick tightening work can be performed.

FIG. 2C shows a second embodiment. In this embodiment, the guide thread 15 is an incomplete thread. In this embodiment as well, each dimension D1, D3 of the guide thread 15
Are configured similarly to the first embodiment. Other configurations are the same as in the first embodiment.

The guide screw thread may not be triangular as in the first embodiment, but may be trapezoidal or square.

[0020]

[Effects of the Invention] Since the present invention is constructed as described above, the material can be easily drawn in the cold plastic working process, and the cost can be reduced and the production efficiency can be improved.

Further, the straightness with respect to the mating member can be maintained, and the tightening workability is improved.

[Brief description of the drawings]

1A is a partial cross-sectional front view before screwing a bolt of the present invention into a mating member, and FIG. 1B is a partial cross-sectional front view while screwing the bolt into a female screw of the mating member.

2A is a partial cross-sectional front view of the bolt of the present invention completely tightened, FIG. 2B is a front view of a material used for the bolt of the present invention, and FIG. 2C is a front view of the second embodiment.

3 (A) is a partial cross-sectional front view of a conventional bolt pilot inserted into a mating member, FIG. 3 (B) is an enlarged cross-sectional view showing a relationship between a guide thread and a female thread of the conventional bolt, and FIG. The front view which shows the raw material for the conventional bolts.

[Explanation of symbols]

 1 Bolt 3 Shaft 4 Mating member 5 Female thread 6 Normal thread 7 Pilot 8 Guide thread

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-2326 (JP, A) JP-A-1-202333 (JP, A) Japanese Utility Model Showa 52-77371 (JP, U) Japanese Utility Model Showa 59- 37413 (JP, U) Japanese Utility Model 3-17412 (JP, U) Japanese Utility Model 58-146114 (JP, U) Japanese Utility Model Utility Model 2-38509 (JP, U) Japanese Utility Model Utility Model 62-2012 (JP, U) 60-8510 (JP, U)

Claims (1)

(57) [Scope of request for utility model registration] An ordinary screw thread is formed on a shaft portion to be screwed with an internal thread of a mating member, and a pilot having an axis coincident with the shaft portion is provided at a distal end side of the shaft portion. Forming a guide thread continuous with the normal thread, setting the root diameter of the guide thread within an allowable dimension of the root diameter of the normal thread, and setting the outer diameter of the guide thread to Bolt with pilot set larger than the inner diameter of female thread.