JP5340997B2 - Coating film removing bolt and manufacturing method thereof - Google Patents

Description

  The present invention relates to a coating film removing bolt and a method for manufacturing the same. More specifically, the coating film on the female screw portion is removed when screwed into a nut or other member having a female screw portion (hereinafter referred to as “nuts”) in which a coating film is formed on the female screw portion. In particular, the present invention relates to a coating film removing bolt that can be smoothly screwed into a nut or the like and can be fastened to the nut or the like with a sufficient tightening force, and a method for manufacturing the same.

  In general, in the process of manufacturing an assembly in which a plurality of members are assembled together by fastening them with bolts, and at least some of the members are painted, this member is coated after being painted. In some cases, other members may be bolted. For example, in the assembly process of an automobile body, first, a nut is welded to a plate-like member that forms the main part of the vehicle body, and then the plate-like member is coated, and then a bolt is screwed into the nut. May be fixed to the plate-like member.

  In this case, when the plate-like member is coated, the paint adheres to the female thread portion of the nut. In particular, a considerable amount of paint adheres to the valleys between the threads of the female threaded portion of the nut or the flank surface of the thread. As described above, when a bolt is screwed into a nut having a coating film formed on the female screw portion and a coating film is formed, the paint adhering to the female screw portion causes a gap between the female screw portion of the nut and the male screw portion of the bolt. The clearance may be too little or none, and the frictional force between the female screw portion and the male screw portion may increase, resulting in a tightening abnormality. When such a tightening abnormality occurs, a sufficient tightening axial force cannot be obtained between the bolt and the nut, and the bolt and the nut cannot be securely or securely fastened.

  Further, for example, when the bolt is an automobile earth bolt, it is necessary to ensure electrical conductivity between the bolt and the vehicle body or a nut welded to the vehicle body, but paint adheres to the female thread portion of the nut. When the coating material is insulative, sufficient electrical conductivity between the bolt and the vehicle body or nut cannot be ensured.

  Therefore, as shown in FIGS. 1 to 3, a groove 5 extending in the bolt central axis direction from the bolt tip portion 3 toward the bolt head portion 4 side is formed on the outer peripheral surface of the bolt shaft portion 2 on which the male screw portion 1 is formed. On the other hand, a paint removal bolt has been proposed in which the height of the thread of the male screw portion 1 is higher than the other portions in the vicinity of the peripheral edge of the groove 5 (see Patent Document 1). In this conventional paint removing bolt, the paint removing bolt is screwed by a portion 6 (hereinafter referred to as “thread raised portion 6”) having a high thread height formed in the vicinity of the peripheral edge of the groove 5. The paint adhering to a female screw portion (not shown) such as a nut is removed. In the paint removal bolt disclosed in Patent Document 1, the thread ridge 6 on the peripheral edge of one side of the groove 5 is formed as a blade 6a, and the thread ridge 6 on the other side is formed as a relief 6b. Is formed.

  The thread ridge 6 of this conventional paint removal bolt is formed by the following procedure. That is, the groove 5 is formed in the bolt shaft portion 2 by cold working before the male screw portion 1 is formed. At that time, as shown in FIG. 4, the protruding portion 7 is formed at the peripheral edge of the groove 5. Thereafter, the male screw portion 1 is formed on the bolt shaft portion 2 by rolling. As a result, the portion corresponding to the protrusion 7 has a high thread height and becomes a thread ridge 6 (blade 6a and relief 6b), and the portion other than the protrusion 7 has a normal height thread ( (Hereinafter referred to as “regular thread part”).

JP 05-318017 A

  As shown in FIGS. 5 and 6, in the conventional paint removal bolt disclosed in Patent Document 1, the height of the thread ridge 6 (blade 6a and relief 6b) is equal to the height H of the regular thread. Therefore, when the paint removal bolt is screwed into the nut or the like, the paint adhering to the female thread portion can be removed by the thread ridge 6.

  However, when the paint removal bolt is screwed into a nut or the like, when the thread ridge 6 (blade 6a and escape portion 6b) interferes with or engages with a female thread such as a nut, the thread ridge 6 A portion higher than the normal thread portion, that is, a portion where the volume is increased compared to the normal thread portion (hereinafter referred to as “volume increasing portion”) is deformed by plastic flow as indicated by an arrow P in FIG. However, the paint removal bolt must be screwed into the nut. In addition, the paint removal bolt is provided with a relief groove 6b. However, if the degree of interference between the increased volume portion of the thread ridge 6 and the thread of the female thread is too large, the material of the paint removal bolt is removed at this portion. There is a problem that the frictional force for plastic flow increases, an appropriate tightening force cannot be obtained, and normal tightening cannot be performed.

  The present invention has been made to solve the above-described conventional problems, and when a bolt is screwed into a nut or the like in which a coating film is formed by attaching a coating film to an internal thread portion, the coating film or the coating film is applied. It is an object to be solved to provide means that enables a bolt to be fastened to a nut or the like with an appropriate tightening force while removing the bolt.

  In the coating film removing bolt according to the present invention made to solve the above problems, a groove portion extending from the bolt tip toward the bolt end side is formed on the outer peripheral portion of the portion where the male screw portion of the bolt shaft portion is formed. ing. A thread deformation portion formed by deforming the vicinity of the top portion of the thread of the male screw portion in the vicinity of at least one side edge portion (groove shoulder portion) of the groove portion so as to protrude in the bolt axis direction is provided. Is formed. In addition, it is preferable that the thread deformation part is formed in the vicinity of both side edges of the groove part. Moreover, it is preferable that a plurality of grooves are formed. This coating film removing bolt can be manufactured by the following manufacturing method, for example.

  That is, first, a groove extending from the tip of the bolt toward the end of the bolt is formed on the outer peripheral surface of the bolt shaft portion of the bolt material by cold forging. Next, a male thread portion is formed on the outer peripheral surface of the bolt shaft portion by thread rolling. Thereafter, in the vicinity of at least one side edge portion of the groove portion, the thread deformation portion is formed by plastically deforming the external thread portion so that the vicinity of the top portion of the thread portion of the external thread portion protrudes in the bolt axis direction. Thereby, a coating film removal bolt is completed.

  In the coating film removing bolt according to the present invention, it is preferable that the thread deformation portion is plastically deformed so that the vicinity of the top portion of the male screw portion tilts (falls) toward the bolt end side. This coating film removing bolt can be manufactured by the following manufacturing method, for example.

  That is, first, a groove extending from the tip of the bolt toward the end of the bolt is formed on the outer peripheral surface of the bolt shaft portion of the bolt material by cold forging. Next, a male thread portion is formed on the outer peripheral surface of the bolt shaft portion by thread rolling. In addition, the portion other than the portion corresponding to the vicinity of at least one side edge of the groove has a shape that fits (fits) the outer peripheral shape of the cross section of the bolt shaft portion, while the vicinity of at least one side edge of the groove In a portion corresponding to, a mold having a hollow portion having a shape smaller than the outer peripheral shape of the cross section of the bolt shaft portion is prepared. Thereafter, while maintaining the positional relationship in which the shape of the hollow portion and the outer peripheral shape of the cross section of the bolt shaft portion coincide with each other, the bolt material is press-fitted into the hollow portion from the bolt front end side, and the peripheral wall of the hollow portion A thread deformation part is formed by plastically deforming the vicinity of the top part of the male screw part in the vicinity of the side edge part so as to tilt toward the bolt end side. Thereby, a coating film removal bolt is completed.

  In the coating film removing bolt according to the present invention, the thread deformation portion is plastically deformed so that the vicinity of the top portion of the male screw portion is crushed in the bolt radial direction and protrudes to the bolt front end side and bolt end side. Also good. This coating film removal bolt can be manufactured by the following manufacturing method, for example.

  That is, first, a groove extending from the tip of the bolt toward the end of the bolt is formed on the outer peripheral surface of the bolt shaft portion of the bolt material by cold forging. Next, a male thread portion is formed on the outer peripheral surface of the bolt shaft portion by thread rolling. After this, at the portion corresponding to the vicinity of at least one side edge of the groove portion, the vicinity of the top portion of the male screw portion is crushed in the bolt radial direction by press molding using a pressing member so as to protrude to the bolt front end side and bolt end side. To form a thread deformation portion. Thereby, a coating film removal bolt is completed.

  According to the coating film removing bolt according to the present invention, when the coating film removing bolt is screwed into a nut or the like in which the coating material is attached to the female screw portion and the coating film is formed, the coating film is peeled off by the thread deformation portion. The peeled paint or coating film can be removed to the outside via the groove. Thus, the paint or the coating film can be removed from the internal thread portion such as a nut, so that the bolt can be smoothly screwed into the nut or the like with an appropriate tightening force to be firmly tightened. In addition, when it is necessary to provide electrical conductivity between the bolt and nut, for example, when the coating film removal bolt is an automobile ground bolt, ensure electrical conductivity between the bolt and nut. Can do.

  The thread deformation part is a plastic deformation such that the normal thread part, that is, the normal thread part, is plastically deformed so as to tilt toward the bolt end side, or the vicinity of the top part of the male screw part is crushed in the bolt radial direction. Therefore, the volume of the thread portion does not increase due to the formation of the thread deformation portion. That is, the volume of the thread portion with the thread deformation portion is substantially the same as the volume of the normal thread portion. For this reason, even when the degree of interference between the thread thread deformed part and the female thread part such as a nut is large, the frictional force for plastic flow of the material of the coating film removing bolt does not increase so much at this part, and proper tightening is not possible. The coating film removing bolt can be firmly tightened to a nut or the like with an applied force.

  According to the method for manufacturing a coating film removing bolt according to the present invention, various coating film removing bolts having the effects as described above can be manufactured easily and inexpensively.

It is a conventional paint removal bolt side view. It is a bottom view of the paint removal bolt shown in FIG. It is a typical side surface sectional view of the part in which the thread of the axial part of the paint removal bolt shown in FIG. 1 was formed. It is a side view of the paint removal bolt material in the state in which the groove was formed in the process of manufacturing the paint removal bolt shown in FIG. FIG. 2 is a schematic side cross-sectional view of the thread of the paint removal bolt shown in FIG. 1, showing the difference between the height of the thread ridge and the height of the normal thread. FIG. 2 is an enlarged bottom view of the paint removal bolt shown in FIG. 1, showing a state of plastic flow of a thread ridge when the paint removal bolt is screwed into a female screw. It is a figure which shows one method of deform | transforming the screw thread of a bolt in order to give a coating-film removal function. It is a figure which shows another method of deform | transforming the screw thread of a bolt in order to give a coating-film removal function. It is a side view of the volt | bolt in which the groove | channel was formed in the axial part. It is a side view of the volt | bolt which concerns on Embodiment 1 of this invention. It is AA sectional view taken on the line of the volt | bolt shown in FIG. 12, and has shown the shape of the thread in a groove shoulder part. It is a side view which expands and shows the axial part around the groove | channel of the volt | bolt shown in FIG. It is a side view of the volt | bolt which concerns on Embodiment 2 of this invention. FIG. 16 is a cross-sectional view of the bolt shown in FIG. 15 taken along the line B-B, showing the shape of the thread in the groove shoulder. It is a side view which expands and shows the axial part around the groove | channel of the volt | bolt shown in FIG. (A), (b) and (c) are respectively a top view, a side view and a bottom view of the bolt material in the course of the manufacturing process of the bolt according to Embodiment 1 of the present invention, in which a groove is formed. The state before a thread is formed later is shown. It is CC sectional view taken on the line of the bolt material shown in FIG.16 (b). (A), (b), and (c) are respectively a top view, a side view, and a bottom view of a bolt material in the course of manufacturing a bolt according to Embodiment 1 of the present invention, in which a thread is formed. It shows the state after. It is the DD sectional view taken on the line of the bolt material shown in FIG.18 (b). It is the DD sectional view taken on the line of the bolt material shown in FIG.18 (b). It is an upper surface sectional view (transverse sectional view) of a shaft part of a mold and a bolt material arranged in the mold. (A) is a side view of the bolt material in a state before the thread is deformed, (b) is a side view of a mold for deforming the bolt material shown in (a), and (c) is ( It is the bottom view which looked at the metal mold | die shown to b) from the direction shown by the arrow F. FIG. It is a side view of the bolt material in a state after deforming the thread.

(Technical thought which is the premise of the present invention)
Hereinafter, embodiments of the present invention will be specifically described. First, the technical idea which is the premise of the present invention will be described with reference to FIGS. As disclosed in Patent Document 1, when a thread ridge is provided by raising a part of a thread of a bolt, when the bolt is screwed into a nut or the like, the thread ridge is Interferes with female thread such as nuts. And the coating material adhering to the internal thread part can be peeled and removed by this interference. However, as described above, when the thread ridge is provided, the frictional force for causing the bolt material to plastically flow when the thread bulge interferes with the female thread such as a nut increases due to the increase in the volume of the thread. There arises a problem that an appropriate tightening force cannot be obtained.

  Therefore, as shown in FIG. 7, after forming the regular thread portion 10 in the bolt material, the regular thread portion 10 is pressed or crushed downward in the bolt radial direction to extend the bolt center axis (in FIG. 7). A method is conceivable in which the thread deformation part 11 (hereinafter referred to as “press thread deformation part 11”) is formed by plastic deformation so as to protrude from both sides in the right and left direction in the positional relationship. Such a press thread deformed portion 11 is formed, for example, by first forming a regular thread portion 10 in a bolt material, and a pressing member having a flat contact surface on the top of a predetermined portion of the regular thread portion 10. 12 can be formed by applying a predetermined molding load L to the pressing member 12.

  In this case, since the volume of the thread portion with the press thread deformation portion 11 is substantially the same as the volume of the normal thread portion 10, the space between the press thread deformation portion 11 and the internal thread portion such as a nut is between. Even when the degree of interference is large, the frictional force for plastic flow of the bolt material does not increase so much.

  However, the peeled paint accumulates in the gap between the male threaded portion of the bolt and the female threaded portion such as a nut, thereby increasing the frictional force. Further, when it is necessary to provide electrical conductivity between the bolt and the nut, for example, when the bolt is an automobile ground bolt, the electrical conductivity between the bolt and the nut cannot be sufficiently ensured. When the degree of interference between the press thread deformed portion 11 and the female thread portion such as a nut is large, the press thread deformed portion 11 is difficult to restore to the original shape of the normal threaded portion 10 and is therefore screwed into a nut or the like. Sometimes, the tightening frictional force between the bolt and the nut or the like, or the bolt and the nut or the like may be firmly fixed (with galling).

  Further, as shown in FIG. 8, after the regular thread portion 10 is formed in the bolt material, the regular thread portion 10 is tilted toward the bolt end side (leftward in the positional relationship in FIG. 8). Thus, it is conceivable to form the thread deformation part 13 (hereinafter referred to as “inclined thread deformation part 13”) by plastic deformation.

  In this case, the volume of the thread portion with the tilting thread deformation portion 13 is substantially the same as the volume of the normal thread portion 10, and therefore, between the tilting thread deformation portion 13 and the female thread portion such as a nut. Even when the degree of interference is large, the frictional force for plastic flow of the bolt material does not increase so much.

  However, in this case as well, the peeled paint accumulates in the gap between the male screw portion of the bolt and the female screw portion such as a nut, thereby increasing the frictional force. Further, when it is necessary to provide conductivity between the bolt and the nut, the conductivity between the bolt and the nut cannot be sufficiently ensured. In this case as well, when the degree of interference between the tilted thread deformed portion 13 and the female thread portion such as a nut is large, the tilted thread deformed portion 13 is difficult to restore to the original shape of the regular threaded portion 10, so When screwed into the bolt, there is a risk that an increase in the frictional force of tightening between the bolt and the nut or the like, and the fixing of the bolt and nut or the like (with galling) may occur.

(Coating removal bolt according to Embodiment 1)
Hereinafter, the configuration and function of the coating film removing bolt according to Embodiment 1 of the present invention will be specifically described with reference to FIGS. 9 to 12. FIG. 9 is a side view of a bolt 15 which is a comparative example for comparison with the coating film removing bolt according to the present invention, in which a groove portion is formed but a thread deformation portion is not formed. These are the side views of the coating film removal bolt 16A in which the groove part and tilting thread deformation part which concern on Embodiment 1 of this invention were formed.

  As shown in FIG. 9, the bolt 15 according to the comparative example has a bolt head portion 17 and a bolt shaft portion 18, and a male screw portion 19 is formed on the outer peripheral surface of the bolt shaft portion 18. In the vicinity of the tip end portion of the bolt shaft portion 18, a tip tapered portion 20 without a male screw is provided, while in the vicinity of the end portion, a bolt neck portion 21 without a male screw is provided. The outer periphery of the bolt shaft portion 18 is provided with two groove portions 22 extending linearly in a direction parallel to the bolt center axis from the tip tapered portion 20 toward the bolt neck portion 21 or the bolt head portion 17. . Both groove portions 22 are arranged at positions shifted from each other by 180 ° at the central angle with respect to the circumferential direction of the bolt 15. Each groove portion 22 terminates at a portion where the male screw portion 19 is formed at a portion slightly on the bolt tip side from the bolt neck portion 21.

  As shown in FIG. 10, the coating film removing bolt 16 </ b> A according to Embodiment 1 of the present invention is basically similar to the bolt 15 according to the comparative example, the bolt head portion 17, the bolt shaft portion 18, and the male screw portion. 19, a tip tapered portion 20, a bolt neck portion 21, and two groove portions 22. Further, in the coating film removing bolt 16A, the vicinity of both side edges 24 (groove shoulders) of each groove portion 22 is connected to the male screw portion 19, and the vicinity of the top of the thread of the male screw portion 19 is on the bolt neck portion 21 side or the bolt head. An inclined thread deformation portion 25 is formed on the portion 17 side, that is, plastically deformed so as to incline toward the pressure side flank surface. However, the inclined thread deformation portion 25 is not formed on one small-diameter male screw on the bolt front end side and some male screws on the bolt end side.

  As described above, the tilting thread deforming portion 25 of the coating film removing bolt 16A tilts the normal male thread portion 19, that is, the normal thread portion as shown in FIG. 9 toward the bolt neck portion 21 side, that is, the pressure side flank surface direction. It is formed by plastic deformation. Accordingly, the volume of the male screw portion 19 does not increase due to the formation of the tilted thread deformation portion 25. In other words, the volume of the male screw portion in which the tilted thread deformation portion 25 is formed is substantially the same as the volume of the normal male screw portion in which the tilt screw thread deformation portion 25 is not formed.

  In addition, although the coating film removal bolt 16A which concerns on Embodiment 1 is provided with the two groove parts 22, the number of the groove parts 22 is not necessarily limited to two, One may be sufficient and three or more It may be. The depth of each groove portion 22 is not particularly limited, but when there is a lot of paint or coating film adhering to the nut or the like to which the coating film removing bolt 16A is screwed, the depth of the groove portion 22 according to the amount thereof. It is preferable to deepen. Further, in the coating film removing bolt 16A according to the first embodiment, the screw thread 19 is inclined to the male screw portion 19 in the vicinity of both side edge portions 24 (groove shoulder portions) on the leading side and the trailing side of the groove portion 22 in the bolt tightening rotation direction. Although the deformed portion 25 is formed (see FIG. 12), the inclined thread deformed portion 25 may be formed only in the vicinity of either the side edge portion 24 on the leading side or the trailing side of the groove portion 22.

  In the coating film removing bolt 16A, the groove portion 22 has a function of smoothly discharging the paint or coating film peeled off and removed from a female screw portion such as a nut into which the coating film removing bolt 16A is screwed. Further, as will be described in detail later, the groove portion 22 includes an inclined screw thread deforming portion 25 formed in the male screw portion 19 in the vicinity of both side edges 24 (both groove shoulder portions) of the groove portion 22 and a female screw such as a nut. It has a function of reducing resistance when it deforms by interfering with the part.

  Hereinafter, with reference to FIG. 11 and FIG. 12, functions, functions, and effects of the groove portion 22 and the inclined thread deformation portion 25 in the coating film removing bolt 16 </ b> A according to the first embodiment will be described. When the coating film removing bolt 16A is rotated around the bolt center axis as shown by an arrow R in FIG. No. 25 peels off the paint or coating film adhering to the internal thread portion such as a nut as the coating film removing bolt 16A rotates. The paint thus peeled is pushed out through the groove 22 and discharged along with the rotation of the coating film removing bolt 16A around the bolt central axis.

  As described above, since the paint or the coating film is removed from the female screw portion such as the nut by the inclined thread deformation portion 25 and the groove portion 22, the coating film removing bolt 16A can be smoothly applied to the nut or the like with an appropriate tightening force. It can be screwed and fastened firmly. Further, when it is necessary to provide conductivity between the coating film removal bolt 16A and the nut, for example, when the coating film removal bolt 16A is an automobile earth bolt, the coating film removal bolt 16A and the nut etc. It is possible to reliably ensure the conductivity.

  As described above, since the volume of the male screw portion 19 does not increase due to the formation of the tilting thread deformation portion 25, the volume of the male screw portion where the tilting screw thread deformation portion 25 is formed is that the tilting screw thread deformation portion 25 is formed. It is substantially the same as the volume of the normal male screw portion. For this reason, even when the degree of interference between the inclined thread deformation part 25 and the female thread part such as a nut is large, the frictional force for plastically flowing the material of the coating film removing bolt 16A does not increase so much at this part. The coating film removing bolt 16A can be firmly tightened to a nut or the like with an appropriate tightening force.

  Further, when the coating film removing bolt 16A is screwed into a nut or the like, the inclined thread deformation portion 25 protruding in the bolt neck portion 21 side, that is, the pressure side flank surface direction, is connected to the flank surface of the female screw portion such as a nut. have a finger in the pie. On the other hand, since the inclined thread deformation portion 25 is formed on the side edge portion 24 (groove shoulder portion) of the groove portion 22, it is only supported in the form of a cantilever (cantilever) by the base portion of the male screw portion 19. Yes, not so firmly supported.

  For this reason, when the degree of interference between the tilted thread deformed portion 25 and the female thread portion such as a nut is large, the tilted thread deformed portion 25 is easily formed by the flank surface of the female threaded portion as indicated by an arrow Q in FIG. It is deformed, and generally returns to its original shape, that is, the shape of the normal male screw portion 19. For this reason, an increase in the tightening frictional force between the coating film removing bolt 16A and the nut or the like, or the adhesion (with scuffing) between the coating film removing bolt 16A and the nut does not occur. Therefore, even when the degree of interference between the inclined thread deformation portion 25 and the female screw portion such as a nut is large, the frictional force for plastic flow of the material of the coating film removing bolt 16A does not increase so much at this portion. The coating film removal bolt 16A can be firmly tightened to a nut or the like with a sufficient tightening force.

  In addition, as shown in FIG. 8, in the bolt in which the inclined thread deformation portion 13 is simply provided without providing the groove portion, as described above, when the degree of interference between the inclined screw thread deformation portion 13 and the female screw portion such as a nut is large, Since the inclined thread deformation portion 13 is difficult to restore to the original shape of the normal thread portion 10, an increase in the tightening frictional force between the bolt and the nut, etc. Sticking occurs.

(Coating film removal bolt according to Embodiment 2)
Hereinafter, the configuration and function of the coating film removing bolt 16B according to the second embodiment of the present invention will be specifically described with reference to FIGS. However, since the coating film removal bolt 16B according to the second embodiment has many common points with the coating film removal bolt 16A according to the first embodiment, in order to avoid duplication of explanation, the coating mainly according to the first embodiment will be described below. Differences from the film removal bolt 16A will be described. In addition, in the coating film removal bolt 16B shown in FIGS. 13-15, the same reference number is attached | subjected to the component which is common in the coating film removal bolt 16A which concerns on Embodiment 1 shown in FIGS. 10-12. .

  As shown in FIGS. 13 to 15, in the coating film removing bolt 16 </ b> B according to the second embodiment, the screw of the male screw portion 19 is connected to the male screw portion 19 in the vicinity of both side edge portions 24 (groove shoulder portions) of each groove portion 22. A press-type thread deformation portion 27 is formed by pressing (crushing) the vicinity of the top of the mountain downward and plastically deforming so as to protrude from both sides in the direction in which the bolt central axis extends with respect to the normal flank surface. Yes. However, the press thread deformation portion 27 is not formed on some male screws on the bolt front end side and some male screws on the bolt end side. In addition, the top part of the press thread deformation part 27 is substantially flat.

  As described above, the press screw thread deformed portion 27 of the coating film removing bolt 16B has a normal male screw portion 19 as shown in FIG. 9, that is, a normal screw thread portion in a direction in which the bolt central axis extends with respect to the normal flank surface. It is formed by plastic deformation so as to protrude. Accordingly, the formation of the press thread deformation portion 27 does not increase the volume of the male screw portion 19. In other words, the volume of the male screw portion in which the press screw thread deformed portion 27 is formed is substantially the same as the volume of a regular male screw portion in which the press screw thread deformed portion 27 is not formed.

  In the coating film removing bolt 16B, the groove portion 22 has a function of smoothly discharging the paint or coating film peeled off and removed from the female thread portion such as a nut, as in the coating film removing bolt 16A according to the first embodiment. Have Further, the groove portion 22 has a resistance when a press thread deformation portion 27 formed on the male screw portion 19 in the vicinity of both side edge portions 24 (groove shoulder portions) of the groove portion 22 is deformed by interference with a female screw portion such as a nut. It has the function to reduce.

  Hereinafter, functions, functions, and effects of the groove portion 22 and the press thread deformation portion 27 in the coating film removing bolt 16B according to the second embodiment will be described. When the coating film removal bolt 16B is rotated around the bolt center axis and screwed into a nut or the like having paint or coating film attached to the female thread portion, the press thread deformation portion 27 rotates the coating film removal bolt 16B. Along with this, the paint or coating film adhering to the female screw part such as a nut is peeled off. The coating material thus peeled is pushed out through the groove portion 22 and discharged along with the rotation of the coating film removing bolt 16B around the central axis of the bolt.

  As described above, since the coating thread or the coating film is removed from the female screw portion such as the nut by the press thread deformation portion 27 and the groove portion 22, the coating film removing bolt 16B can be smoothly applied to the nut or the like with an appropriate tightening force. It can be screwed and fastened firmly. Further, when it is necessary to provide electrical conductivity between the coating film removal bolt 16B and the nut, for example, when the coating film removal bolt 16B is an automobile earth bolt, the coating film removal bolt 16B is separated from the nut or the like. It is possible to reliably ensure the conductivity.

  As described above, since the volume of the male screw portion 19 does not increase due to the formation of the press screw thread deformation portion 27, the volume of the male screw portion where the press screw thread deformation portion 27 is formed is the same as that of the press screw thread deformation portion 27. It is substantially the same as the volume of the normal male screw portion. For this reason, even when the degree of interference between the press thread deformation part 27 and the female thread part such as a nut is large, the frictional force for plastically flowing the material of the coating film removing bolt 16B does not increase so much at this part. The coating film removing bolt 16B can be firmly tightened to a nut or the like with an appropriate tightening force.

  When the coating film removing bolt 16B is screwed into a nut or the like, the press thread deformation portion 27 protruding to both sides with respect to the bolt central axis direction interferes with a flank surface of a female screw portion such as a nut. On the other hand, since the press thread deformation part 27 is formed in the side edge part 24 (groove shoulder part) of the groove part 22, it is not supported so firmly.

  For this reason, when the degree of interference between the press screw thread deformed portion 27 and the female screw portion such as a nut is large, the press screw thread deformed portion 27 is easily deformed by the flank surface of the female screw portion, and generally has an original shape, that is, a regular one. It returns to the shape of the male screw part 19. For this reason, the increase in the tightening frictional force between the coating film removal bolt 16B and the nut or the like, or the adhesion (with scuffing) between the coating film removal bolt 16B and the nut does not occur. Therefore, even when the degree of interference between the press thread deformation portion 27 and the female screw portion such as a nut is large, the frictional force for plastically flowing the material of the coating film removing bolt 16B does not increase so much at this portion. The coating film removal bolt 16B can be firmly tightened to a nut or the like with a sufficient tightening force.

  In addition, as shown in FIG. 7, in the bolt in which the groove portion is not provided and the press thread deformation portion 11 is simply provided, as described above, when the degree of interference between the press thread deformation portion 11 and the female thread portion such as a nut is large, Since the press thread deformation portion 11 is difficult to restore to the original shape of the regular thread portion 10, when the screw thread deformation portion 11 is screwed into the nut or the like, the tightening frictional force between the bolt and the nut or the like is increased. May occur.

(Method for Manufacturing Coating Film Removal Bolt According to Embodiment 1)
Hereinafter, a method for manufacturing the coating film removing bolt 16A according to the first embodiment will be described with reference to FIGS. In the method of manufacturing the coating film removing bolt 16A, first, as shown in FIGS. 16 (a) to 16 (c) and FIG. 17, a bolt material made of a predetermined metal material and provided with a bolt head portion 17 and a bolt shaft portion 18. 30 is subjected to cold forging, and two bolts extending linearly in the direction of the bolt material central axis from the front end of the bolt material or the vicinity of the front end of the bolt material toward the end of the bolt material on the outer peripheral surface of the bolt shaft 18. A groove 22 is formed. Both groove portions 22 are arranged at positions shifted from each other by 180 ° at the central angle with respect to the circumferential direction of the bolt material 30. Both side edge portions 24 (groove shoulder portions) extending in the bolt material central axis direction of the groove portion 22 have an R shape (see FIG. 21) in order to prevent damage to the mold 32 (see FIG. 21) for forming the inclined thread deformation portion 25. Rounded shape). In addition, when the side edge part 24 of the groove part 22 is edge shape, damage to the metal mold | die 32 tends to arise.

  Next, as shown in FIGS. 18A to 18C, 19, and 20, the bolt material 30 is subjected to thread rolling and the male screw portion 19 is formed on the outer peripheral surface of the bolt shaft portion 18. . The groove portion 22 terminates at a portion where the male screw portion 19 is formed in a portion slightly on the bolt front end side from the bolt neck portion 21. Here, a tip tapered portion 20 where no male screw is formed exists in the vicinity of the tip portion of the bolt shaft portion 18, while a bolt neck portion 21 where no male screw is formed exists in the vicinity of the end portion. In FIG. 19, T (two-dot chain line) indicates the outer peripheral surface or outer diameter of the bolt material 30 before being subjected to thread rolling. Moreover, in FIG. 20, G1 and G2 have shown the outer diameter and trough diameter of the external thread part 19, respectively. Since the side edge portion 24 (groove shoulder portion) of the groove portion 22 is formed in an R shape as described above, the male screw portion 19 has an R shape in the portion 34 corresponding to the side edge portion 24 of the groove portion 22.

  Thereafter, as shown in FIGS. 21 to 23, in the vicinity of the side edge portions 24 of the groove portion 22, the vicinity of the top portion of the male screw portion 19 is plastically deformed so as to incline toward the bolt material terminal side, and the inclined screw thread deformed portion. 25 is formed. Specifically, first, a mold 32 having a hollow portion 33 is prepared. As shown in FIG. 21, the hollow portion 33 of the mold 32 has a cross section of the bolt shaft portion 18 as shown by J1 and J2 in portions other than the portion corresponding to the vicinity of the side edge portion 24 of the groove portion 22. It has a shape that matches (fits) the outer peripheral shape. On the other hand, a portion corresponding to the vicinity of the side edge portion 24 of the groove portion 22 has a shape that is smaller than the outer peripheral shape J4 of the cross section of the bolt shaft portion 18, as indicated by J3. FIG. 21 is a view in which the cross section of the mold 32 and the cross section of the male thread portion 19 of the bolt shaft portion 18 of the bolt material 30 after the thread forging are overlaid, and the solid line represents the gold The shape of the mold 32 is shown, and a two-dot chain line shows a cross section of the male screw portion 19.

  Then, as shown in FIGS. 22A to 22C and FIG. 23, the bolts are coaxially maintained while maintaining the positional relationship in which the shape of the hollow portion 33 and the outer peripheral shape of the cross section of the bolt shaft portion 18 coincide. The material 30 is press-fitted into the hollow portion 33 of the mold 32 from the bolt front end side. Thus, the peripheral wall of the hollow portion 33 plastically deforms the vicinity of the top portion of the male screw portion 19 in the vicinity of the side edge 31 of the groove portion 22 so as to tilt toward the bolt end side, and the tilted thread deformation portion 25 is formed. . Thus, the coating film removing bolt 16A according to the first embodiment is completed. 22A to 22C show a state before the tilted thread deformation portion 25 is formed, and FIG. 23 shows a state after the tilted thread deformation portion 25 is formed.

  As described above, the hollow portion 33 of the mold 32 has a shape that is smaller than the outer peripheral shape of the cross section of the bolt shaft portion 18 at a portion corresponding to the vicinity of the side edge portion 24 of the groove portion 22, and thus the bolt material 30. Is pressed into the hollow portion 33, the portion outside the hollow portion 33 of the male screw portion 19, that is, the portion corresponding to the region indicated by S in FIG. It becomes. Here, by increasing or decreasing the area indicated by S in FIG. 21, the amount of plastic deformation of the male screw portion 19 or the size of the inclined thread deformation portion 25 can be increased or decreased. The groove portion 22 formed in the bolt shaft portion 18 has a function of positioning the bolt material 30 and the mold 32 when the bolt material 30 is press-fitted into the hollow portion 33. According to this manufacturing method, the coating film removing bolt 16A according to Embodiment 1 can be easily and inexpensively manufactured.

(Manufacturing method of the coating film removal bolt which concerns on Embodiment 2)
Hereinafter, the manufacturing method of the coating film removal bolt 16B which concerns on Embodiment 2 is demonstrated. In the method of manufacturing the coating film removing bolt 16B, as in the method of manufacturing the coating film removing bolt 16A, the bolt material 30 made of a predetermined metal material and including the bolt head portion 17 and the bolt shaft portion 18 is used. Cold forging is performed, and two groove portions 22 are formed on the outer peripheral surface of the bolt shaft portion 18 so as to extend linearly in the bolt material central axis direction from the bolt material tip or the vicinity of the bolt material tip. (See FIGS. 16A to 16C and FIG. 17). Next, as in the case of the method of manufacturing the coating film removing bolt 16A, the bolt material 30 is subjected to thread rolling, and the male thread portion 19 is formed on the outer peripheral surface of the bolt shaft portion 18 (FIG. 18A). -(C) and FIG.19 and FIG.20).

  Thereafter, in the portion corresponding to the vicinity of both side edge portions 24 of the groove portion 22, the vicinity of the top portion of the male screw portion 19 is subjected to press molding in the bolt radial direction using a pressing member (see FIG. 7) to be crushed. A press thread deformation portion 27 is formed by plastically deforming the vicinity of the top portion of 19 so as to protrude to both sides of the bolt front end side and the bolt end side. Thus, the coating film removing bolt 16B according to the second embodiment is completed. According to this manufacturing method, the coating film removing bolt 16B according to Embodiment 2 can be manufactured easily and inexpensively.

  1 Thread, 2 Bolt Shaft, 3 Bolt Tip, 4 Bolt Head, 5 Groove, 6 Thread Raised, 6a Blade, 6b Escape, 7 Projection, 10 Regular Thread, 11 Press Thread Deformation Part, 12 pressing member, 13 tilting thread deformation part, 15 bolt, 16A coating film removal bolt, 16B coating film removal bolt, 17 bolt head part, 18 bolt shaft part, 19 male thread part, 20 tip taper part, 21 bolt neck part , 22 groove part, 24 side edge part, 25 tilting thread deformation part, 27 press thread deformation part, 30 bolt material, 32 mold, 33 hollow part.

Claims (6)

On the outer peripheral portion of the portion where the male thread portion of the bolt shaft portion is formed, a groove portion extending from the bolt tip or the vicinity of the bolt tip toward the bolt end side is formed,
In the vicinity of at least one side edge of the groove portion, a thread deformation portion is formed on the male screw portion, which is plastically deformed so that the vicinity of the top of the screw thread of the male screw portion protrudes in the bolt axis direction. A film removing bolt characterized by that.   2. The coating film removing bolt according to claim 1, wherein the thread deformation portion is plastically deformed so that a portion near the top of the male screw portion tilts toward a bolt end side.   The screw thread deformed portion is formed by plastic deformation so that the vicinity of the top portion of the male screw portion is crushed in the bolt radial direction and protrudes to the bolt front end side and bolt end side. The coating film removing bolt as described. It is a manufacturing method of the paint film removal bolt according to claim 1,
By cold forging, on the outer peripheral surface of the bolt shaft portion of the bolt material, a groove portion extending from the bolt material tip or the bolt material tip vicinity to the bolt material terminal side is formed,
By thread rolling, a male screw part is formed on the outer peripheral surface of the bolt shaft part,
Forming a thread deformation portion by plastically deforming the male screw portion so that a portion near the top of the screw thread of the male screw portion protrudes in the bolt axial direction in the vicinity of at least one side edge of the groove portion; The manufacturing method of the coating film removal bolt characterized by the above-mentioned. It is a manufacturing method of the paint film removal bolt according to claim 2,
By cold forging, on the outer peripheral surface of the bolt shaft portion of the bolt material, a groove portion extending from the bolt material tip or the bolt material tip vicinity to the bolt material terminal side is formed,
By thread rolling, a male screw part is formed on the outer peripheral surface of the bolt shaft part,
The portion other than the portion corresponding to the vicinity of at least one side edge of the groove has a shape that matches the outer peripheral shape of the cross section of the bolt shaft portion, and corresponds to the vicinity of at least one side edge of the groove. In the part, prepare a mold having a hollow part having a shape reduced than the outer peripheral shape of the cross section of the bolt shaft part,
While maintaining the positional relationship in which the shape of the hollow portion and the outer peripheral shape of the cross section of the bolt shaft portion coincide with each other, the bolt material is press-fitted into the hollow portion from the bolt tip side, and the peripheral wall of the hollow portion A method for producing a coating film removing bolt, wherein a screw thread deformed portion is formed by plastically deforming a vicinity of a top portion of the male screw portion in a vicinity of a side edge portion of the groove portion so as to tilt toward a bolt material terminal side. It is a manufacturing method of the paint film removal bolt according to claim 3,
By cold forging, on the outer peripheral surface of the bolt shaft portion of the bolt material, a groove portion extending from the bolt material tip or the bolt material tip vicinity to the bolt material terminal side is formed,
By thread rolling, a male screw part is formed on the outer peripheral surface of the bolt shaft part,
In a portion corresponding to the vicinity of at least one side edge portion of the groove portion, the vicinity of the top portion of the male screw portion is crushed in the bolt radial direction by press molding using a pressing member so as to protrude to the bolt front end side and bolt end side. A method for producing a coating film removing bolt, wherein a thread deformation portion is formed by plastic deformation.

Images