JPH0557415U - Bolt with pilot - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a bolt with a pilot, which is easy to draw at the boundary between the shaft portion and the pilot portion, and which is easy to maintain straightness with respect to the mating member. [Structure] A normal screw thread 6 to be screwed into a female screw 5 of a mating member 4 is formed on a shaft portion 6, and a pilot 7 having a shaft center aligned with that of the shaft portion 3 is provided on a tip end side of the shaft portion 3. A guide screw thread 8 continuous with the normal screw thread 6 is formed in the pilot 7, and the root diameter D1 of the guide screw thread 8 is set within an allowable dimension of the root diameter D2 of the normal screw thread 6. Then, the outer diameter D3 of the guide screw thread 8 is set within the allowable dimension of the inner diameter D4 of the female screw 5, and the angle of the guide screw thread 8 is set to approximately 90 ° or more.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a bolt used for tightening with an impact wrench, a robot, etc., in an assembly process of automobile parts, for example, a bolt with a pilot for preventing oblique screwing.

[0002]

[Prior Art]

 FIG. 3 shows a conventional bolt 100 of this type. The bolt 100 includes a head portion 101 and a shaft portion 102, and the shaft portion 102 is formed with a normal thread 105 that is screwed into a female screw 104 of a mating member 103. Further, a pilot 106 whose shaft center (not shown) coincides with that of the shaft portion 102 is provided on the tip end side of the shaft portion 102.

Guide threads 107 are formed on the pilot 106. The outer diameter d1 of the guide screw thread 107 is set to be equal to or slightly smaller than the inner diameter d2 of the female screw 104. The root diameter d3 of the guide screw thread 107 is set smaller than the root diameter of the normal screw thread 105. Further, the ridge angle θ1 of the guide screw thread 107 is set to be substantially equal to the ridge angle of the normal screw thread 105 (about 60 °).

The bolt 100 having the above structure is inserted into the insertion holes 110 and 111 of the mounting members 108 and 109, and the guide screw thread 107 is inserted into the female screw 104 of the mating member 103 as shown in FIG. Lock on.

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 the shaft portion is further maintained. The normal thread 105 of 102 is screwed into the female thread 104 to complete the tightening.

[0006]

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

Therefore, when the pilot portion 106 is inserted into the mating member 103, the pilot portion 106 may be largely tilted, the straightness of the bolt 100 with respect to the mating member 103 may be lost, and diagonal screwing may occur.

The present invention is to solve the above problems, and provides a bolt with a pilot, which can easily draw a boundary portion between a shaft portion and a pilot and can maintain the straightness with respect to a counterpart member. It is an object.

[0009]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a pilot in which a shaft is formed with a normal thread to be screwed into a female screw of a mating member, and the shaft is aligned with the shaft center on the tip side of the shaft. A guide screw thread continuous with the normal screw thread is formed on the pilot, and the root diameter of the guide screw thread is set within the allowable dimension of the root diameter of the normal screw thread. The outer diameter of the crest was set larger than the inner diameter of the female thread.

[0010]

[Action]

 In the present invention based on the above configuration, the pilot thread of the pilot is screwed into the female thread of the mating member, so that the straightness of the mating member is maintained. Since the guide thread root diameter is usually set within the allowable dimension of the thread root diameter, the difference between the shaft diameter and the pilot diameter is relatively small in the cold plastic working process of the material. , Easy to draw.

[0011]

【Example】

 Next, the present invention will be described based on illustrated embodiments. FIG. 1 shows a first embodiment, and in FIG. 1, reference numeral 1 denotes a pilot bolt of the present invention. The bolt 1 has a head portion 2 and a shaft portion 3. Although the head 2 has a hexagonal shape in the figure, it may have a hexagonal hole or a slotted shape with a slot. The shaft portion 3 is formed with a normal thread 6 which is set to have a size to be screwed into the female screw 5 of a mating member (engine body, nut, etc.) 4.

A pilot 7 having a shaft center (not shown) aligned with the shaft portion 3 is provided on the tip end side of the shaft portion 3. Usually, the length of the pilot 7 is preferably about 50 to 80% of the nominal diameter of the screw thread 6. The pilot 7 is formed with a guide screw thread 8 continuous with the normal screw thread 6. 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, while the outer diameter D3 of the guide screw thread 8 is set larger than the inner diameter D4 of the female screw 5. There is. Further, the crest angle θ2 of the guide screw thread 8 is set to about 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 cylindrical material (not shown) is cold plastically worked, specifically, inserted into a hole of a die and extruded, and the shaft portion 3 and the pilot 7 are made to have a predetermined diameter as shown in FIG. 2 (B). The diaphragm material 10 is used. A chamfer 13 is formed at the tip of the pilot portion 7. At this time, in the bolt 1 of the present invention, since 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 crest angle θ2 is about 90 °, the material is The difference between the diameter D7 of the shaft portion 3 of 10 and the diameter D8 of the pilot 7 is relatively small. Therefore, the drawing process for processing the material 10 from the material can be easily performed in a short time, and the production efficiency is improved.

In the material 10 thus obtained, the normal screw thread 6 and the guide screw thread 8 are respectively rolled by a combination of a die for a normal screw thread and a die for a guide screw thread (not shown).

When the bolt 1 is inserted into the insertion hole 12 of the mounting member 11 and the tip 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 becomes the female screw 5. Follow along. Since the valley diameter D1 of the guide screw thread 8 is usually set within the allowable dimension of the valley diameter D2 of the screw thread 6, the bolt 1 is less likely to tilt, and the axial center of the female screw 5 and the axial center of the bolt 1 are Roundness is maintained. In the first embodiment, since the crest angle θ2 is set to about 90 °, the function of suppressing the inclination of the bolt 1 is excellent and the insertability is good.

Although the bolt 1 may actually be slightly tilted as shown in FIG. 1B, the fitting property between the female screw 5 and the guide screw thread 8 is better. When the bolt 1 is further rotated, the pitch of the internal thread 5 and the pitch of the normal thread 6 match, so the normal thread 6 smoothly engages with the internal thread 5, as shown in FIG. 2 (A). The head 2 comes into contact with the mounting member 11 to complete the tightening. Therefore, quick tightening work can be performed.

FIG. 2C shows a second embodiment. In this embodiment, the guide threads 15 are incomplete full threads. Also in this embodiment, the dimensions D1 and D3 of the guide screw thread 15 are the same as those in the first embodiment. Other configurations are the same as those in the first embodiment.

Note that the guide threads may be trapezoidal or quadrangular instead of triangular as in the first embodiment.

[0020]

[Effect of the device]

 Since the present invention is configured as described above, it is possible to easily perform drawing of the material in the cold plastic working process, reduce costs and improve production efficiency.

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

[Brief description of drawings]

FIG. 1 (A) is a partially sectional front view before screwing the bolt of the present invention into a mating member, and FIG. 1 (B) is a partially sectional front view in the middle of screwing the bolt into a female screw of the mating member.

2A is a partially 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 a second embodiment.

3A is a partially sectional front view of a conventional bolt pilot inserted into a mating member, FIG. 3B is an enlarged sectional view showing a relationship between a guide thread and an internal thread of a conventional bolt, and FIG. The front view which shows the material for the conventional bolts.

[Explanation of symbols]

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

Claims (1)

[Scope of utility model registration request] 1. A normal thread to be screwed into a female screw of a mating member is formed on a shaft portion, and a pilot whose axial center coincides with that of the shaft portion is provided on the tip end side of the shaft portion. While forming a guide screw thread continuous to the normal screw thread, the root diameter of the guide screw thread is set within an allowable dimension of the root diameter of the normal screw thread, and the outer diameter of the guide screw thread is A bolt with a pilot set larger than the inner diameter of the female thread.