JP3173042U - bolt - Google Patents

Abstract

The present invention provides a bolt capable of reducing a fastening torque at an initial stage of fastening and reducing a worker's work load.
A screw portion 30 that can be screwed into a screw portion of a nut, and a cylindrical guide portion 4 that is formed on the tip side of the screw portion 30 so as to be smaller in diameter than the inner diameter of the screw portion. 30 includes a spiral first complete thread 31 and a spiral second complete thread 32 formed so as to be continuous with the distal end side of the first complete thread 31. The valley diameter D2b is set to be larger than the outer diameter Dg of the guide portion 4 and smaller than the valley diameter D1b of the first complete thread 31, and the cross section of the second complete thread 32 is the cross section of the first complete thread 31. And the same shape. Thereby, the advance side flank of the second complete thread 32 and the thread of the nut can be partially brought into contact in the initial stage of fastening.
[Selection] Figure 2

Description

  In the present invention, the threaded portion that can be screwed into the female thread of the member to be fastened is constituted by a first complete thread and a second complete thread having a root diameter smaller than the root diameter of the first complete thread. Related to the bolts.

  2. Description of the Related Art Conventionally, in an automobile production line, cationic electrodeposition coating in which a vehicle body is immersed in a water-based paint and a direct current is passed through the vehicle body as a cathode is performed in the undercoating step of the vehicle body. In this cationic electrodeposition coating, an acidic paint and an object to be coated (car body) are charged with static electricity having different polarities, and the object to be coated is subjected to a neutralization reaction utilizing the alkalinity generated when water is electrolyzed. A rust-preventing coating is formed on the surface.

  Body equipment such as an engine, transmission, and suspension of an automobile is assembled using bolts after a nut as a fastened member is welded in advance to a body side member such as a body and the body is subjected to cationic electrodeposition coating. Therefore, a cationic electrodeposition coating film is deposited on the threaded portion of the nut, and when the bolt is fastened, an increase in the screwing torque of the bolt or a poor biting of the bolt is caused. Therefore, in the previous stage of cationic electrodeposition coating, a film made of a highly insulating organic resin as a raw material is formed in advance on the entire inner surface of the threaded portion of the nut welded to the vehicle body side. This prevents deposition of the cationic electrodeposition coating film generated on the threaded portion of the nut.

Usually, in the assembly process after the undercoat process, various body equipments are mounted on the vehicle body by fastening the bolt to the nut using an automatic fastening device such as a nut runner.
The organic resin coating coated on the nut threaded portion welded to the vehicle body is removed from the inner surface of the nut threaded portion as the bolt rotates when the threaded portion of the bolt meshes with the threaded portion of the nut ( Stripped). Thereby, the surface shape of the screw part of the nut is restored to the original screw part shape from the state covered with the organic resin coating, and the screw part of the bolt and the screw part of the nut are brought into direct contact and fastened.

  On the other hand, when assembling the bodywork, if the bolt is tightened when the bolt axis is not aligned with the nut's female thread (thread) centerline, the bolt is tilted with respect to the nut's female thread centerline If the screw is forcibly screwed in, there is a risk that the bolt may be galled or seized. Then, the bolt with the seizure prevention function for preventing such a bolt tightening diagonally is proposed.

  The bolt of Patent Document 1 forms a threaded portion entrance cut out at an angle of 15 to 80 degrees on the front end side of the shaft center with respect to the shaft center at the start end portion of the complete thread of the threaded portion provided in the shaft portion. In addition, the guide boss formed at the tip of the shaft center is formed with a guide groove that is continuous with the valley of the thread and has the same pitch as the valley. As a result, the guide groove guides the top of the screw thread of the nut and preliminarily corrects the inclination angle of the bolt, and the notch shape of the screw part inlet corrects the inclination angle of the bolt. It can guide properly and prevents the bolts from being diagonally tightened.

JP 2002-213425 A

Due to factors such as the layout of the equipment, the automatic fastening device that rotates the bolt interferes with the vehicle body equipment, and it may not be possible to secure an arrangement space for inserting the automatic fastening device. In this case, the operator inserts the tip of the bolt into the female screw of the nut, and then manually tightens the bolt until the initial fastening stage where the complete screw thread of the bolt and the screw thread of the nut are screwed together. It has been practiced to mount vehicle body equipment using a fastening tool such as.
That is, when performing a hand tightening operation in which a bolt is screwed into a nut whose screw portion is covered with an organic resin coating, the bolt complete screw thread is removed while removing the organic resin coating covering the inner surface of the screw portion of the nut. Since the screw thread of the nut is screwed together, the fastening torque at the initial stage of fastening by the worker is high, and there is a possibility that the hand tightening workability of the worker is reduced.

The bolt of patent document 1 can correct the inclination angle of the bolt with respect to the female thread center line of the nut, and can screw the start end portion (thread portion inlet) of the complete screw thread of the bolt and the screw thread of the nut.
However, as described above, when a bolt is hand-tightened to a nut covered with an organic resin coating, the operator performs an operation of screwing the start end portion of the complete screw thread of the bolt with the screw thread of the nut. Therefore, it is necessary to perform the hand tightening work at the initial stage of fastening by screwing the complete screw thread of the bolt and the screw thread of the nut while removing the organic resin film. The challenge remains high.

  The objective of this invention is providing the volt | bolt which can reduce a worker's work load by reducing the fastening torque of a fastening initial stage.

  The bolt according to claim 1 is a screw portion having a complete thread having a fixed height that can be screwed into the female screw of the member to be fastened, and a circle formed on the tip side of the screw portion to be smaller in diameter than the inner diameter of the female screw. In the bolt having the columnar guide portion, the screw portion includes a spiral first complete screw thread and a spiral second complete screw thread formed so as to be connected to the tip side of the first complete screw thread. The second complete thread has a valley diameter that is larger than an outer diameter of the guide portion and smaller than a valley diameter of the first complete thread, and a cross section of the second complete thread is the first It is characterized by being formed in the same shape as the cross section of one complete thread.

The device of claim 2 is characterized in that, in the device of claim 1, the outer diameter of the second complete thread is set larger than the valley diameter of the first complete thread.
The invention of claim 3 is characterized in that, in the invention of claim 1 or 2, it is screwed into the member to be fastened, wherein the entire inner surface of the female screw is coated.

  According to the first aspect of the present invention, the valley diameter of the second complete thread connected to the tip side of the first complete thread is set larger than the outer diameter of the guide portion and smaller than the valley diameter of the first complete thread. In addition, since the cross section of the second complete thread connected to the tip side of the first complete thread is formed in the same shape as the cross section of the first complete thread, the second complete thread of the bolt and the thread of the nut The tightening torque for screwing the bolts can be lower than the tightening torque for screwing the first complete thread of the bolt and the thread of the nut. Can be reduced. Thereby, when an operator hands-tightens a bolt with respect to a nut, a worker's workload can be reduced.

According to the second aspect of the present invention, it is possible to reduce the fastening torque while reducing the inclination angle of the bolt with respect to the female screw center line of the nut in the initial stage of fastening.
According to the third aspect of the present invention, even in a hand tightening operation in which a bolt is screwed into a nut whose thread portion is covered with a coating, the tightening torque of the bolt can be reduced, and the operator's hand tightening workability can be reduced. Can be high.

It is a side view of the volt | bolt which concerns on the Example of this invention, and a longitudinal cross-sectional view of the nut which this volt | bolt can screw together. It is a side view of the front-end | tip part of a volt | bolt. It is state explanatory drawing of the fastening operation in which the bolt is screwed onto the nut whose screw part is covered with the coating, (a) is a diagram showing the guide part insertion state, (b) is the hand-tightened state of the second complete thread (C) is a figure which shows the fastening state of a 1st complete thread.

  The bolt of the present invention includes a threaded portion having a complete screw thread of a certain height that can be screwed into the female thread of a member to be fastened, and a cylindrical shape formed on the tip side of the threaded part with a diameter smaller than the inner diameter of the female thread. And a screw portion including a spiral first complete thread and a spiral second complete thread formed to be continuous with a tip end side of the first complete thread. The full thread valley diameter is set to be larger than the outer diameter of the guide portion and smaller than the first complete thread valley diameter, and the cross section of the second complete thread has the same shape as the cross section of the first complete thread. Is formed.

A first embodiment of the present invention will be described below with reference to FIGS.
As shown in FIG. 1, the bolt 1 includes a head 2, a shaft portion 3 that is continuous with the head portion 2, and a columnar guide portion 4 that is continuous with the bolt tip side of the shaft portion 3.
The shaft portion 3 is formed with a cylindrical portion 5 that forms a lower neck portion and a screw portion 30 that is connected to the bolt front end side of the cylindrical portion 5.

As shown in FIGS. 1 and 2, the screw portion 30 is formed so as to be able to be screwed to a screw portion 60 (female screw) formed on the nut 6 (fastened member), and has a helical first complete thread 31. A spiral second complete thread 32 connected to the front end of the bolt of the first complete thread 31, and a spiral second incomplete whose thread height gradually decreases from the end of the second complete thread 32. And a thread 33.
The threaded portion 60 of the nut 6 includes a thread 61, and the inner diameter (prepared hole diameter) is set to Dn. The bolt 1 of this embodiment is an example of a bolt for fastening a vehicle body equipment such as a seat to a vehicle body of an automobile.

  The first complete thread 31 of the screw part 30 is formed in the middle part of the shaft part 3 so as to have a substantially isosceles cross section and a constant height. The first complete thread 31 has a top portion 31a and a valley portion 31b spaced apart from the axis of the bolt 1 by a certain distance, and the top portion 31a and the valley portion 31b are configured to have a constant pitch interval. Yes.

As shown in the following equation (1), the outer diameter (top diameter) D1a of the first complete thread 31 is larger than the inner diameter Dn of the thread part 60 of the nut 6, and the valley diameter D1b of the first complete thread 31 is The inner diameter Dn of the threaded portion 60 of the nut 6 is set smaller.
Dn <D1a D1b <Dn (1)

As shown in FIGS. 1 and 2, the second complete thread 32 of the threaded portion 30 has the same shape and a constant height as the cross section of the first complete thread 31 (substantially isosceles triangle). Is formed. The second complete thread 32 has a top portion 32a and a valley portion 32b that are spaced apart from the axis of the bolt 1 by a certain distance, and the top portion 32a and the valley portion 32b are respectively spaced apart from the pitch interval of the first complete thread 31. It is comprised so that it may become the same pitch space | interval.
In the present embodiment, the axial length of the second complete thread 32 is formed to a length corresponding to 4 pitches (corresponding to 4 threads).

As shown in the following equation (2), the outer diameter (top diameter) D2a of the second complete thread 32 is larger than the inner diameter Dn of the threaded portion 60 of the nut 6 and is larger than the outer diameter D1a of the first complete thread 31. Is set too small.
Dn <D2a <D1a (2)
As shown in the following expression (3), the valley diameter D2b of the second complete thread 32 is set to be larger than the outer diameter Dg of the guide portion 4 and smaller than the valley diameter D1b of the first complete thread 31. .
Dg <D2b <D1b (3)

  The second incomplete thread 33 of the screw portion 30 has a cross-section similar to that of the second complete thread 32 (substantially isosceles triangle) and the pitch interval between the first and second complete threads 31 and 32. It is comprised so that it may become the same pitch space | interval. The second incomplete thread 33 is formed so that the height of the apex 33a gradually increases from the start end and continues to the tip apex 32a of the second complete thread 32 at the end. The valley diameter of the valley portion 33b of the second incomplete thread 33 is set to be the same as the valley diameter D2b of the second complete thread 32.

  The guide portion 4 is provided so as to extend in the bolt tip direction from the tip of the screw portion 30 through the taper portion, and the bolt axial direction length corresponds to a plurality of pitches of the first and second complete thread threads 31 and 32, for example, It is formed corresponding to 4 pitches. As described above, the outer diameter Dg of the guide part 4 is set smaller than the valley diameter D2b of the second complete thread 32 (the valley diameter of the second incomplete thread 33), and the thread part 60 of the nut 6 is visually recognized. Even when it is impossible, the operator can search for the screw portion 60 with the tip of the bolt 1 and can insert the tip of the bolt 1 into the screw portion 60.

The bolt 1 is formed by, for example, forming the head portion 2 by cold forging a steel bar and then forming the screw portion 30 by plastic forming the shaft portion 3 using a rolling die or the like. ing.
When the head 2 is molded, a rod-shaped intermediate molded body corresponding to the shaft portion 3 is simultaneously formed. In this intermediate formed body, the outer diameter of the cylindrical portion where the second complete thread 32 is processed is lower than the outer diameter of the cylindrical portion where the first complete thread 31 is processed. Preliminarily formed so as to correspond to the difference between the diameter D1b (the outer diameter D1a of the first complete thread 31) and the valley diameter D2b of the second complete thread 32 (the outer diameter D2a of the second complete thread 32). Yes. After the threaded portion 30 is processed, heat treatment or surface treatment is performed to adjust the surface hardness of the bolt 1. In this embodiment, after heat treatment, an Al—Zn composite coating for rust prevention is formed on the surface of the bolt 1, and a frictional resistance coefficient adjusting material is applied to the surface of this rust prevention coating.

A fastening operation using the bolt 1 will be described with reference to FIGS. 3 (a) to 3 (c).
In this fastening operation, the operator performs the hand tightening operation until the initial fastening stage where the second complete thread 32 of the bolt 1 and the thread 61 of the nut 6 are screwed together, and then uses a manual fastening tool to tighten the bolt. Fasten 1 completely. The nut 6 is welded and joined to the vehicle body in advance, and the cationic electrodeposition coating is performed on the vehicle body to which the nut 6 is welded in the pre-process of the fastening operation. On the entire surface, a highly insulating organic resin film 62 for preventing the deposition of a cationic electrodeposition coating film is formed.

  As shown in FIG. 3A, the operator moves the bolt 1 to a position near the nut 6 and inserts the guide portion 4 of the bolt 1 into the screw portion 60 of the nut 6. At this time, since the outer diameter Dg of the guide portion 4 is formed smaller than the inner diameter Dn of the screw portion 60, the guide portion 4 can screw the screw portion 60 even in a blind operation where the operator cannot visually recognize the screw portion 60 of the nut 6. The part 60 can be searched.

  Since the guide portion 4 is guided to the top of the screw thread 61, the bolt 1 is guided to the front end side in the axial direction, and the second complete thread 32 or the second incomplete thread 33 of the first thread from the bolt front end side. When the screw part 60 comes into contact with the screw thread 61 (organic resin film 62) at the bolt side end, the operation of inserting the guide part 4 into the screw part 60 is completed. Since the axial length of the guide portion 4 is a length corresponding to 4 pitches of each complete thread 31, 32, the axial center of the bolt 1 becomes the axial center of the nut 6 in synchronization with the insertion operation of the guide portion 4. The posture is adjusted to align.

Next, the operator performs a hand-tightening operation by rotating the head 2 of the bolt 1 so that the second complete thread 32 of the bolt 1 and the thread 61 of the nut 6 are screwed into a plurality of pitches.
As shown in FIG. 3B, the second complete thread 32 has the same cross-sectional shape (substantially isosceles triangle) as the first complete thread 31, but the outer diameter D2a of the second complete thread 32 and the screw. A clearance with the mountain 61 can be secured. Therefore, since the advance side flank of the second complete thread 32 and the organic resin film 62 are in partial contact, it is not necessary to completely remove the organic resin film 62 from the inner surface of the thread 61, and the organic resin film 62. However, the second complete thread 32 and the thread 61 can be screwed together while remaining on the inner surface of the thread 61, and the tightening torque of the hand tightening operation by the operator can be kept low.

  Further, since the outer diameter D2a of the second complete thread 32 is set larger than the valley diameter D1b of the first complete thread 31, the second complete thread 32 of the bolt 1 and the thread 61 of the nut 6 In the initial fastening stage in which a plurality of pitches are screwed together, the inclination angle of the bolt 1 with respect to the center line of the threaded portion 60 of the nut 6 can be reduced.

After the manual tightening operation, the first complete thread 31 of the bolt 1 and the thread 61 of the nut 6 are screwed together using a manual fastening tool such as a corner wrench.
As shown in FIG. 3 (c), in synchronism with the fastening operation of the bolt 1, an organic resin film 62 in which substantially the entire front side flank of the first complete thread 31 covers the inner surface of the threaded portion 60 of the nut 6. It advances in the fastening direction (bolt tip direction) while removing. The fastening operation is terminated when the fastening torque of the bolt 1 exceeds a predetermined torque value.

Next, the operation and effect of the bolt 1 according to the embodiment will be described.
In this bolt 1, the valley diameter D2b of the second complete thread 32 connected to the distal end side of the first complete thread 31 is larger than the outer diameter Dg of the guide portion 4 and is larger than the valley diameter D1b of the first complete thread 31. Since the cross section of the second complete thread 32 connected to the tip end side of the first complete thread 31 is formed in the same shape as the cross section of the first complete thread 31, the second complete thread 31 of the bolt 1 is set to be small. The fastening torque for screwing the screw thread 32 and the screw thread 31 of the nut 6 can be reduced below the fastening torque for screwing the first complete screw thread 31 of the bolt 1 and the screw thread 61 of the nut 6. The fastening torque at the initial stage of fastening corresponding to the hand tightening operation can be reduced. Thereby, when an operator hands-tightens the volt | bolt 1 with respect to the nut 6, a worker's workload can be reduced.

Since the outer diameter D2a of the second complete thread 32 is set larger than the valley diameter D1b of the first complete thread 31, the inclination angle of the bolt 1 with respect to the center line of the threaded portion 60 of the nut 6 is set at the initial stage of fastening. The fastening torque can be reduced while reducing the size.
Even in the hand tightening operation in which the bolt 1 is screwed into the nut 6 covered with the organic resin coating 62 on the screw portion 60, the tightening torque of the bolt 1 can be reduced, and the operator's hand tightening workability is improved. be able to.

Next, a modification in which the above embodiment is partially changed will be described.
1] In the above embodiment, the example of the bolt applied to the hand tightening work and the fastening work using the manual fastening tool has been described, but at least the hand tightening work by the operator may be present. Even when the automatic fastening device is used, the fastening torque in the initial stage of fastening can be reduced, and the work load on the operator can be reduced.

2] In the above embodiment, the example in which the axial length of the second complete thread portion is formed to a length equivalent to 4 pitches has been described, but depending on the design conditions such as the diameter and axial length of the bolt, It may be formed shorter than a length corresponding to 4 pitches, or may be formed longer than a length corresponding to 4 pitches. Further, the axial length of the guide portion can be arbitrarily set.
3) In addition, those skilled in the art can implement the present invention by adding various modifications without departing from the spirit of the present invention, and the present invention includes such modifications. is there.

  In the present invention, the threaded portion that can be screwed into the female thread of the member to be fastened is constituted by a first complete thread and a second complete thread having a root diameter smaller than the root diameter of the first complete thread. In the formed bolt, by forming the cross section of the second complete thread in the same shape as the cross section of the first complete thread, it is possible to reduce the fastening torque in the initial stage of fastening and reduce the work load of the operator. .

DESCRIPTION OF SYMBOLS 1 Bolt 3 Shaft part 4 Guide part 6 Nut 30 (Bolt) thread part 31 1st complete thread 31b (1st complete thread) Valley part 32 2nd complete thread 32b (2nd complete thread) Valley part 60 ( Nut) Screw part 61 (Nut) Screw thread 62 Organic resin coating D1b (First complete thread) Valley diameter D2a (Second complete thread) Outer diameter D2b (Second complete thread) Valley diameter Dg Guide part outer diameter Dn (Nut) Thread inner diameter

Claims (3)

A screw portion having a complete screw thread of a certain height that can be screwed into the female screw of the member to be fastened, and a cylindrical guide portion formed on the tip side of the screw portion with a diameter smaller than the inner diameter of the female screw; In bolts
The threaded portion includes a spiral first complete thread and a spiral second complete thread formed so as to be continuous with a tip side of the first complete thread;
The valley diameter of the second complete thread is set larger than the outer diameter of the guide portion and smaller than the valley diameter of the first complete thread, and the cross section of the second complete thread is the first complete thread. A bolt characterized by being formed in the same shape as the cross section of the thread.   The bolt according to claim 1, wherein an outer diameter of the second complete thread is set larger than a valley diameter of the first complete thread. 3. The bolt according to claim 1, wherein the bolt is screwed into the fastened member in which a coating is applied to the entire inner surface of the female screw.