JP2005299859A - Tapping screw, and component mounting method to thin plate by using tapping screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tapping screw and a component mounting method to a thin plate by using the tapping screw, capable of clearly determining the completion of tapping. <P>SOLUTION: This tapping screw 1 is used for mounting a component 31 to the thin plate 30, and has a female screw processing part 2 for forming a female screw 35 on the thin plate 30, a male screw part 3 engaged with the female screw 35 of the thin plate 30, and a head part 5, successively mounted from a tip side. A threaded groove 9a of the female screw processing part 2 has a tapping part 20 for forming the female screw 35, a radius of the tapping part of a rear end part of the female screw processing part 2 is larger than a radius of a male screw part 3, further a distance between a bearing surface 5c of the head part 5 and a rear end of the female screw processing part 2 is longer than the sum of a thickness of a hole part formation part 32 of the thin plate 30 and a hole part formation part 36 of the component 31, and further a distance between the bearing surface 5c of the head part 5 and the rear end of the male screw part 3 is shorter than the sum of the thickness of the hole formation part 32 of the thin plate 30 and the hole part formation part 36 of the component 31. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a self-tapping screw that forms a female screw directly on a thin plate and fastens the component when attaching the component to the thin plate.

Conventionally, when attaching parts to a thin plate, it has been done by welding a nut to a thin plate with a prepared hole and tightening a bolt, but in recent years it has been directly reduced to a thin plate using a tapping screw that can form a female screw on the thin plate to reduce costs. This is done by forming and tightening a female screw.
As such a tapping screw, Japanese Patent Laid-Open No. 8-338412 discloses a special non-circular taper screw portion, a special non-circular screw portion, a circular screw portion, a screwless portion, and a head in order from the tip side. A tapping screw is described (Patent Document 1).
In addition, as a tapping screw, Japanese Patent Application Laid-Open No. 2000-35016 has, in order from the tip side, a processing screw portion for processing a female screw and a standard screw portion having a standard thread, and the thread of the processing screw portion includes a standard thread A tapping screw having a plurality of machining threads having an outer diameter and an effective diameter larger than the thread is formed (Patent Document 2).

As a method for tightening the tapping screw represented by the above example, for example, an operator often directly tightens the body of an automobile using an impact wrench or the like. However, in tightening with an impact wrench or the like, it is difficult to perform accurate torque control during the tightening operation. For this reason, if the conventional tapping screw as described above is tightened using an impact wrench, the completion time of tapping cannot be clearly determined, so that the tightening is tighter than the standard, the internal thread produced by tapping is sheared, or tapping is performed. Since the completion time cannot be clearly identified, there is a possibility that tightening may be stopped before tapping, in other words, during tapping.
Japanese Patent Laid-Open No. 8-338412 JP 2000-351616 A

  Therefore, the present invention solves the above-described problems, and provides a tapping screw and a method of attaching a component to a thin plate using the tapping screw, which can clearly determine when tapping is completed.

What achieves the above object is as follows.
(1) An internal thread processing portion for attaching a component to a thin plate and located on the distal end side, and forming a female screw in a hole formed in the thin plate or a hole formed in the component The tapping screw is located on the rear end side of the female thread processed portion, and has a male screw portion that engages with the female screw formed by the female screw processed portion, and a head provided on the rear end side of the male screw portion. The female threaded portion and the male threaded portion are each provided with a thread, and the thread of the female threaded portion has a tapping portion for machining the female screw, and a tapping portion at the rear end of the female threaded portion. The radius is made larger than the radius of the male screw portion, and the distance between the seating surface of the head and the rear end of the female screw processed portion is the thickness of the hole forming portion of the thin plate and the hole portion of the component. From the sum of the thickness of the forming part Further, the distance between the seating surface of the head and the rear end of the male screw portion is shorter than the sum of the thickness of the hole forming portion of the thin plate and the thickness of the hole forming portion of the component. A tapping screw characterized by
(2) The tapping screw according to (1), wherein the tapping portion is a protruding portion forming portion provided on a thread of the female thread machining portion.
(3) The distance between the seating surface of the head and the rear end of the female thread processed portion is 1.0 P or longer than the sum of the thickness of the hole forming portion of the thin plate and the thickness of the hole forming portion of the component. The tapping screw according to the above (1) or (2).
(4) The projecting portion constituting the tapping portion is any one of the above (1) to (3) provided at a position that is substantially equiangular with respect to a central axis of the tapping screw of the thread. Tapping screw.
(5) The tapping according to any one of the above (1) to (4), wherein a radius of a tapping portion at a rear end portion of the female screw processed portion is 0.03P to 0.15P larger than a radius of the male screw portion. screw.

(6) The tapping screw according to any one of (1) to (5), wherein the tapping screw has a shaft portion that does not include a screw thread between the head portion and the male screw portion.
(7) The tapping screw according to (6), wherein the shaft portion has a breaking strength smaller than a shear strength of the female screw.
(8) The tapping screw according to any one of (1) to (7), wherein a tip portion of the tapping screw is tapered toward the tip.
(9) The tapping screw according to any one of (1) to (8), wherein a rotational torque value when tapping of the tapping screw is completed is 50% or less of a peak value of the rotational torque at the time of tapping.
(10) The tapping screw according to any one of (1) to (9), wherein a rotational torque value at the completion of tapping of the tapping screw is substantially zero.
(11) A component mounting method for mounting a component having a hole to a thin plate having a hole in which a female screw is not formed by using a tapping screw. The component mounting method includes the above (1) to (10). The tapping screw according to any one of the above, wherein the distance between the seating surface of the head and the rear end of the female thread processed portion is the sum of the thickness of the hole forming portion of the thin plate and the thickness of the hole forming portion of the component Using a tapping screw that is slightly longer and the distance between the seating surface of the head and the rear end of the male screw portion is shorter than the sum of the thickness of the hole forming portion of the thin plate and the thickness of the hole forming portion of the component Then, after the component to be fixed is arranged on the surface of the thin plate so that the holes of both are aligned, the tapping screw is inserted from the hole of the component to be fixed and rotated to rotate the thin plate by the tapping portion. In the hole A tapping screw is used, wherein a female screw part is formed, and the tapping part is threaded through the thin plate and screwed with the male screw part, and after confirming a decrease in rotational torque, final fastening is performed. How to attach components to a thin plate.

The present invention is for attaching a component to a thin plate, and is located on the distal end side, and is a hole formed in the thin plate or a female screw processing portion for forming a female screw in the hole formed in the component A tapping screw that is located on the rear end side of the female screw processed portion and has a male screw portion that is screwed with the female screw formed by the female screw processed portion, and a head provided on the rear end side of the male screw portion. The female threaded portion and the male threaded portion include a thread, and the thread of the female threaded portion has a tapping portion for processing the female screw, and the tapping at the rear end portion of the internally threaded portion. The radius of the part is made larger than the radius of the male screw part, and the distance between the seating surface of the head and the rear end of the female screw processed part is the thickness of the hole forming part of the thin plate and the part of the part. Thickness of hole forming part Further, the distance between the seating surface of the head and the rear end of the male screw portion is greater than the sum of the thickness of the hole forming portion of the thin plate and the thickness of the hole forming portion of the component. It is short.
For this reason, according to the tapping screw of the present invention, it is possible to clearly determine when tapping is completed.

Further, the present invention is a component mounting method for mounting a part having a hole to a thin plate having a hole in which a female screw is not formed using a tapping screw, and the part mounting method is the above-described tapping screw. The distance between the seating surface of the head and the rear end of the female thread processed portion is slightly longer than the sum of the thickness of the hole forming portion of the thin plate and the thickness of the hole forming portion of the component, and the seat of the head A tapping screw whose distance between the surface and the rear end of the male screw portion is shorter than the sum of the thickness of the hole forming portion of the thin plate and the thickness of the hole forming portion of the component, and a component to be fixed to the surface of the thin plate Are arranged so that the two hole portions coincide with each other, and then the tapping screw is inserted through the hole portion of the part to be fixed and rotated to form a female screw portion in the hole portion of the thin plate by the tapping portion. Let A parts mounting method of the thin plate using a tapping screw which is characterized in that the final engagement after confirming a reduction in rotational torque with screwed with the male screw portion of the tapping portion is passed through the sheet.
According to this method, when tapping is completed can be clearly determined, tapping is not completed before tapping is completed, and shearing of the female screw due to overtightening can be prevented.

The tapping screw of the present invention will be described.
FIG. 1 is a front view of a tapping screw according to an embodiment of the present invention (a drawing in which a thread is omitted). FIG. 2 is a partially enlarged view of the tapping screw shown in FIG. FIG. 3 is a bottom view of the tapping screw shown in FIG.

  The tapping screw 1 of the present invention is for attaching the component 31 to the thin plate 30 and is located on the distal end side, and a female screw 35 is provided in a hole formed in the thin plate 30 or a hole formed in the component 31. An internal thread processing portion 2 for forming, an external thread portion 3 positioned on the rear end side of the internal thread processing portion 2 and screwed with an internal thread 35 formed by the internal thread processing portion 2, and provided on the rear end side of the external thread portion 3 And a head 5 formed. The female threaded portion 2 and the male threaded portion 3 are provided with screw threads 9 a and 9 b, and the threaded thread 9 of the female thread processed portion 2 has a tapping portion 10 for processing the female screw 35 and the rear end portion of the female thread processed portion 2. The radius of the tapping portion 8 is made larger than the radius of the male screw portion 3, and the distance between the seating surface 5 c of the head 5 and the rear end of the female screw processed portion 2 is the thickness of the hole forming portion 32 of the thin plate 30. And the sum of the thickness of the hole forming part 36 of the component 31, and the distance between the seating surface 5 c of the head 5 and the rear end of the male screw part 3 is equal to the thickness of the hole forming part 32 of the thin plate 30. This is shorter than the sum of the thicknesses of the hole forming portions 36 of the component 31.

In the embodiment shown in FIG. 1, the tapping screw 1 is composed of a female screw machining portion 2, a male screw portion 3, a shaft portion 4, and a head portion 5 provided in order from the tip side. In addition, on the outer surfaces of the female thread processing portion 2 and the male screw portion 3, thread strips 9a and 9b are provided, respectively. The threads 9a and 9b are provided continuously. Moreover, the tapping part 10 is provided in the thread 9a of the internal thread processing part 2 so that it may mention later. Further, it is preferable that the tip portion of the tapping screw is tapered toward the tip in order to gradually form the female screw into the prepared hole.
The internal thread processing portion 2 is a portion for processing an internal thread on the thin plate 30. In the embodiment shown in FIGS. 1 and 2, a thread 9a is provided on the outer surface, and the taper is tapered toward the tip. Thread portion 6, transition screw portion 7 having a larger diameter than screw portion 6 provided on the rear end side of tapered thread portion 6, and substantially the same diameter provided on the rear end side of transition screw portion 7. It consists of the same diameter thread part 8 currently formed in this. Further, a tapping portion 10 is provided on the thread 9a of the female thread processing portion 2 (the outer surface of the thread portion 8 having the same diameter as the tapered thread portion 6 and the transition screw portion 7). Moreover, in the Example of this invention, the front-end | tip of the tapping screw 1 is produced flat. Moreover, it is preferable that the internal thread processing part 2 has the same diameter thread part formed in the substantially same diameter provided in the rear-end part like the Example of this invention.

Moreover, the internal thread processed part may be produced by a tapered thread part that is reduced in a taper shape and an identical diameter thread part that has the same diameter.
In the embodiment shown in FIGS. 1 and 3, four tapping units 10 are provided. As shown in FIGS. 1 and 3, the tapping portion 10 is a protruding portion forming portion provided on the thread 9 a of the internally threaded portion 2 (cross hatch portion in the figure). It is preferable that the tapping part 10 is constituted by a protruding part 10a provided on the thread 9a of the female thread processed part 2. In the embodiment, the tapping portion 10 is constituted by a protruding portion 10a continuous in the axial direction. In other words, the tapping portion 10 is configured by a protruding portion 10a that is provided for each successive winding of the thread 9a and that is continuous in the axial direction. Moreover, the tapping part may be comprised by the protrusion part provided in the screw thread intermittently. In other words, the tapping portion may be constituted by protruding portions formed every other turn or every plurality of turns.

As shown in FIGS. 1 and 3, the protruding portion 10a constituting the tapping portion 10 is preferably provided partially on the circumference of the thread 9a. In the embodiment of the present invention, it is preferable that the protruding portions 10a constituting the tapping portion 10 are provided at about 3 to 5 places on the circumference of the thread 9a of the female thread processing portion 2. Further, it is preferable that the protruding portion 10 a constituting the tapping portion 10 is provided at a position that is substantially equiangular with respect to the central axis of the tapping screw 1. In the embodiment, the protruding portions 10a constituting the tapping portion 10 are provided approximately every 90 ° with respect to the central axis of the tapping screw 1 (provided at four locations). Thus, by providing the tapping part 10 partially on the thread 9a, the contact area between the female thread processed part 2 and the mating member (thin hole forming part or part hole forming part) is reduced during tapping. Therefore, tapping torque can be reduced.
In the embodiment of the present invention, the protruding portion 10a constituting the tapping portion 10 is formed at a substantially equiangular position with respect to the central axis. However, the present invention is not limited to this. It may be provided at an arbitrary position that is not equiangular. Further, the projecting portions constituting the respective tapping portions are not provided in the axial direction as in the embodiment, but may be provided obliquely with respect to the axial direction.

  The protruding portion 10a is formed with a sharp tip so that a female screw can be machined into the hole of the thin plate 30 or the hole of the component 31. As shown in FIG. 3, the protruding portion 10 a preferably has a shape that gradually increases in diameter toward the maximum diameter portion (tip) of the protruding portion 10 a. As shown in FIG. 3, the thread 9 a provided with the tapping portion 10 is manufactured so that the peak portion (projection portion 10 a) and the valley portion (projection portion non-formed portion) 11 are smoothly continuous. Is preferred. As described above, the protruding portion 10a constituting the tapping portion 10 is preferably produced by partially expanding the diameter of the thread 9a. By providing the protruding portion 10a partially and smoothly connecting the protruding portion 10a and the protruding portion non-forming portion 11, the contact area with the mating member can be reduced particularly when forming the internal thread, and the torque during tapping can be reduced. be able to. Further, in the present invention, a plastic working type in which the outer diameters are smoothly connected, but a cutting type with a notch may be used. The tapping portion 10 of the embodiment is configured by the protruding portions 10a formed in this way continuing in the axial direction.

In the embodiment of the present invention, the projecting portion 10a is formed such that the cross-sectional shape of the internal thread machining portion 2 of the tapping screw 1 shown in FIGS. 1 and 3 is a quadrangular shape curved so that each side swells outward. Have been made. Specifically, the tapping portion 10 is near the corner of the quadrangle, and the trough 11 is near the midpoint of each side of the quadrilateral. Since the cross-sectional shape of the internal thread machining portion 2 is formed in this way, the internal thread 35 can be formed without scraping off the hole forming portion 32 of the thin plate 30 at the time of tapping. Therefore, it can also be suitably used for assembling precision parts that cause problems.
In the case of the embodiment of the present invention, the tapping portion 10 is produced by partially expanding the diameter of the screw 9a by plastic deformation. Moreover, the tapping part 10 may be produced by notching the thread 9a of the internal thread processed part 2.

The radius of the tapping portion of the rear end portion (in the embodiment of the present invention, the same diameter screw portion 8) of the female screw processed portion 2 is made larger than the radius of the male screw portion 3. The difference between the radius of the tapping portion at the rear end and the radius of the male screw portion is determined so that the difference in rotational torque between the tapping time and the tapping time can be clearly discriminated.
The radius of the tapping portion of the rear end portion 8 of the female thread processed portion 2 depends on the size of the screw, but is 0.03P (pitch, the same applies hereinafter) to 0.15P, particularly 0.05-0. It is preferable that it is 10P larger. Depending on the screw size, for example, when the male screw portion 3 is M6 coarse, 1P is 1.0 mm, and when M5 is coarse, 1P is 0.8 mm (hereinafter the same). Specifically, the radius of the tapping portion at the rear end of the female threaded portion 2 is 2.940 to 3.135 mm, particularly 2.960 to 3.085 mm in the case of M6, depending on the screw size. Is preferable (corresponding to JIS class 2). In the case of M5, it is preferably 2.433 to 2.608 mm, and particularly preferably 2.453 to 2.568 mm (corresponding to JIS class 2).

Moreover, it is preferable that the radius of the tapping part non-formation part 11 of the rear-end part 8 of the internal thread processed part 2 is made smaller than the radius of the external thread part 3, as shown in FIG. The radius of the tapping portion non-forming portion 11 at the rear end portion of the female thread processed portion 2 is 0.10 P to 0.30 P, particularly 0.15 P to 0.25 P smaller than the radius of the male screw portion 3, depending on the size of the screw. It is preferable that Specifically, the radius of the tapping portion non-forming portion 11 at the rear end portion of the female screw processed portion 2 is 2.610 to 2.885 mm when the male screw portion 3 is M6, although it depends on the screw size. It is preferably 660 to 2.835 mm (corresponding to JIS class 2). Moreover, when the external thread part 3 is M5, it is preferable that it is 2.173-2.408 mm, especially 2.213-2.368 mm (corresponding to JIS class 2).
Further, the tip of the tapping screw may be pointed unlike the embodiment of the present invention. Thereby, an internal thread can be gradually formed in the prepared hole formed in the thin plate 30.

Moreover, the tapping screw may have a thread non-formation part in which the thread is not formed in the front end side of the internal thread processed part. Specifically, you may have the rod-shaped part in which the thread is not provided in the front end side of the internal thread processed part. Thereby, the stability at the start of the tapping operation is improved by inserting the non-thread-formed portion into the prepared hole before the tapping operation.
As shown in FIGS. 1 and 8, the male screw portion 3 is screwed with a female screw 35 provided on the rear end side of the female screw processing portion 2 and formed in the hole portion of the thin plate 30 or the hole portion of the component 31 by the female screw processing portion 2. It is a part to match. In the embodiment of the present invention, the male screw portion 3 is screwed with the female screw 35 formed in the hole forming portion 32 of the thin plate 30 by the female screw processing portion 2. The male screw portion 3 is a substantially circular screw portion. The thread 9b formed on the outer surface of the male thread portion 3 is provided continuously with the thread 9a. The male screw part 3 is not provided with the tapping part 10 (projecting part 10a) unlike the female screw processed part 3.

The radius of the male screw portion 3 is preferably smaller than the radius of the tapping portion at the rear end portion of the female screw processed portion 2 (in the embodiment, the protruding portion 10a of the same diameter screw portion 8). Specifically, the radius of the male screw portion 3 depends on the screw size, but in the case of M6, it is preferably 2.910 to 2.985 mm (corresponding to JIS class 2). Further, in the case of M5, the radius of the male screw portion is preferably 2.413 to 2.488 mm (corresponding to JIS class 2).
The length of the male screw portion 3 is preferably 1.0 P or more longer than the thickness of the hole forming portion 32, and particularly preferably 1.0 P to 2.0 P or longer.
As shown in FIG. 1, the tapping screw 1 has a shaft portion 4 that is not provided with a screw thread between a head portion 5 and a male screw portion 3. The shaft portion 4 is a rod-like portion provided on the rear end side of the male screw portion 3. The shaft diameter of the shaft portion 4 is smaller than the root diameter of the male screw portion 3 in the embodiment of the present invention.

  The shaft portion 4 preferably has a breaking strength smaller than the shear strength of the female screw 35. As such a shaft portion, for example, a shaft portion 16 having a small diameter portion 17 whose diameter is smaller than the root diameter of the male screw portion 3 provided in the tapping screw 14 shown in FIG. Further, like the tapping screw 15 shown in FIG. 5, the entire shaft portion may be a shaft portion that is a small diameter portion 18 having a diameter smaller than the root diameter of the male screw portion 3. Further, the shaft portion may be provided with a groove or a recess so that the breaking strength of the shaft portion is smaller than the shear strength of the female screw. Further, the shaft portion having a breaking strength smaller than the shear strength of the female screw 35 may be one in which the female screw 35 prevents shearing by extending when tightened too much. With such a configuration, even if the tapping screw is tightened excessively, the shaft portion 4 of the tapping screw 1 is broken or elongated before the female screw 35 is sheared, so that the female screw 35 is not sheared, and the shaft portion 4 is broken or elongated due to excessive tightening. In that case, you only need to replace the tapping screw.

A head portion 5 is provided at the rear end portion of the shaft portion 4. In the embodiment of the present invention, the head 5 is composed of a hexagon head 5a and a disk portion 5b provided on the tip side of the hexagon head. The seat surface 5c of the disk portion 5b is made flat. Examples of the shape of the head 5 include a hexagonal head, a square head, a flat round head, a round shape, a pan shape, a truss shape, a bind shape, a dish shape, and a round dish shape.
As shown in FIGS. 1 and 8, the distance between the seating surface 5 c of the head 5 and the rear end of the female threaded portion 2 is determined by the thickness of the hole forming portion 32 of the thin plate 30 and the hole forming portion of the component 31. It is longer than the sum of the thicknesses of 36. As a result, as shown in FIG. 7, when the tapping is completed, the thin plate 30 and the component 31 are completely positioned between the rear end of the female screw processed portion 2 and the seat surface 5c. Further, by combining the above-described configuration with the configuration in which the radius of the tapping portion at the rear end portion of the internal thread machining portion described above is made larger than the radius of the external thread portion, it is possible to clearly determine when the tapping is completed. Become. Further, since it is possible to clearly determine when tapping is completed, the impact wrench or the like can be tightened with the recognition that it has not been seated, so that shearing of the female screw due to excessive tightening can be prevented.

Further, the distance between the seating surface 5 c of the head 5 and the rear end of the male screw portion 3 is shorter than the sum of the thickness of the hole forming portion 32 of the thin plate 30 and the thickness of the hole forming portion 36 of the component 31. . As a result, the female screw 35 and the male screw portion 3 formed on the thin plate 31 can be screwed together in a state where the seat surface 5c and the upper surface of the component 31 are in contact with each other (in a seated state). Can be securely connected. On the other hand, when the distance between the seating surface 5c of the head 5 and the rear end of the male screw portion 3 is longer than the sum of the thickness of the hole forming portion 32 of the thin plate 30 and the thickness of the hole forming portion 36 of the component 31, for example, screw When the length of the shaft portion on which the strip is not formed is longer than the sum of the thicknesses of the hole forming portion of the thin plate and the hole forming portion of the component, the thin plate 30 is connected to the male screw portion 3 in a state where the component 31 is seated. Since it does not screw, the component 31 cannot be fastened to the thin plate 30.
Further, the distance between the seating surface 5c of the head 5 and the rear end of the female thread processed portion 2 is 1.0 P from the sum of the thickness of the hole forming portion 32 of the thin plate 30 and the thickness of the hole forming portion 36 of the component 31. It is preferable that the length is longer. In particular, it is preferably 1.0P to 2.0P, and more preferably 1.5P to 2.0P.
The distance between the seating surface 5c of the head 5 and the rear end of the male screw portion 3 (in the embodiment of the present invention, the length of the shaft portion 4) is equal to or less than the thickness of the hole forming portion 36 of the component 31. Is preferred.

Further, as shown in FIG. 13, in the tapping screw 1, the difference between the peak value of the rotational torque at the time of tapping and the rotational torque value at the time of completion of the tapping is large enough to clearly determine that the tapping is completed. It is preferable. Further, the rotational torque value at the completion of tapping of the tapping screw is preferably 50% or less, particularly 10% or less of the peak value of the rotational torque at the time of tapping. Specifically, the rotational torque at the completion of tapping is preferably 0.25 kgfm or less, particularly about 0 kgfm at M6.
Examples of the material of the thin plate to which the tapping screw of the present invention is attached include cold-rolled steel plates such as SPCC, SPCD, and SPCE, hot-rolled steel plates such as SPHC, SPHD, and SPHE, and high-tensile steel plates. In addition, as a material of the tapping screw, for example, steel, stainless steel, brass, copper, aluminum, titanium, or the like is used. The material of the tapping screw is preferably a material that can be carburized. Moreover, the tapping screw of the present invention is used, for example, for attaching a part to a thin plate constituting an automobile or the like.

Next, a component mounting method and operation using the tapping screw of the present invention will be described.
FIG. 6 is an explanatory diagram for explaining a component mounting method using a tapping screw according to an embodiment of the present invention (during tapping). FIG. 7 is an explanatory diagram for explaining a component mounting method using a tapping screw according to an embodiment of the present invention (when tapping is completed). FIG. 8 is an explanatory diagram for explaining a component mounting method using a tapping screw according to an embodiment of the present invention (at the time of fastening). FIG. 13 is a graph showing a torque change with respect to the rotation angle of the tapping screw according to the embodiment of the present invention and the conventional tapping screw. The solid line in the graph represents a change in rotational torque with respect to the rotation angle of the tapping screw according to the embodiment of the present invention, and the broken line represents a change in torque with respect to the rotation angle of the conventional tapping screw. The tapping screw used for measuring the change in rotational torque with respect to the rotational angle of the tapping screw shown in FIG. 13 and the measurement conditions are performed according to the conditions shown in the following (Example) and (Experiment).

  The component attachment method to the thin plate 30 using the tapping screw 1 of the present invention is a component attachment method in which a component 31 having a hole is attached to the thin plate 30 having a hole where the female screw 35 is not formed using the tapping screw. The component mounting method is the tapping screw 1 described above, and the distance between the seating surface 5c of the head 5 and the rear end of the female screw processed portion 2 is the thickness of the hole forming portion 32 of the thin plate 30 and the hole of the component 31. The thickness of the hole forming portion 32 of the thin plate 30 and the thickness of the hole forming portion 36 of the component 31 are slightly longer than the sum of the thickness of the forming portion 36 and the distance between the seating surface 5c of the head 5 and the rear end of the male screw portion 3 is. And using the tapping screw 1 shorter than the sum of the two, the fixing target component 31 is arranged on the surface of the thin plate 30 so that the holes of both of them match, and then the tapping screw 1 is inserted through the hole of the fixing target component 31 and rotated. By The female screw 35 is formed in the hole portion of the thin plate 30 by the ping portion 10, and the tapping portion 10 is threaded through the thin plate 30 and screwed with the male screw portion 3. Is what you do.

As the tapping screw 1 used in the component mounting method of the present invention, the distance between the seating surface 5c of the head 5 and the rear end of the female thread processed portion 2 is the thickness of the hole forming portion 32 of the thin plate 30 among those described above. The thickness of the hole forming portion 32 of the thin plate 30 and the hole of the component 31 are slightly longer than the sum of the thicknesses of the hole forming portions 36 of the component 31 and the distance between the seating surface 5 c of the head 5 and the rear end of the male screw portion 3. A material shorter than the sum of the thicknesses of the forming portions 36 is used.
Before the attachment operation, a hole (a pilot hole) is formed in the thin plate 30 to be tapped. Examples of the shape of the hole include a cross shape and a round shape. In the embodiment, the hole has a cross shape. Alternatively, the thin plate 30 may be subjected to burring in advance to form a hole.
In addition, a hole 31 through which the tapping screw 1 passes is formed in the component 31 attached to the thin plate 30. In the embodiment, the inner diameter of the hole formed in the component is slightly larger than the maximum diameter of the tapping screw 1, and the female thread is not formed by the female thread processing section 2 in the hole. In addition, as a component attachment method of this invention, you may form a female screw with a tapping screw in both the hole of a thin plate, and the hole of a component. The tapping screw is preferably attached using an impact wrench or the like.

  After the fixing target component 31 is arranged on the surface of the thin plate 30 so that the holes 30 and 31 overlap each other, the tapping screw 1 is inserted through the hole of the fixing target component 31 and the screw is rotated. 35 is formed. Specifically, by rotating the tapping screw 1, the peripheral portion of the hole formed in the cross shape of the thin plate 30 protrudes downward as shown in FIG. 6, and is caused by the tapping portion 10 of the female thread machining portion 2. Female holes 35 are formed in the hole forming portion 32 of the thin plate 30. From the start of tapping (point A), the rotational torque is such that the tapered screw portion 6 and the transition screw portion 7 of the tapping screw 1 pass through the hole forming portion 32 of the thin plate 30, and the vicinity of the tip of the same diameter screw portion 8 is the hole portion. It is considered that it gradually increases until reaching the formation part 32. And when the same diameter thread part 8 reaches | attains the hole formation part 32, it is thought that the rotational torque at the time of tapping becomes a peak (B point). And while the screw part 8 of the same diameter of the tapping screw 1 is traveling through the hole forming part 32, the rotational torque is considered to be substantially constant (point B).

  When the tapping screw 1 is further rotated, the tapping portion 10 (same diameter screw portion 8) gradually passes through the hole forming portion 32, and the male screw portion 3 is formed by the female screw 35 formed in the hole forming portion 32. And gradually screwed together. The rotational torque gradually decreases as the male screw portion 3 is screwed with the female screw portion 35. As shown in FIG. 7, when the tapping portion 10 has completely penetrated the thin plate 30, the rotational torque decreases so that the completion of tapping can be clearly determined as shown in FIG. 13. The rotational torque value at the completion of tapping is preferably 50% or less, particularly 10% or less of the peak value of the rotational torque at the time of tapping. Specifically, the rotational torque at the completion of tapping is preferably 0.25 kgfm or less, particularly about 0 kgfm at M6. If the rotational torque decreases to this extent, it is possible to clearly determine when tapping is completed. In the embodiment, the rotational torque at the completion of tapping is almost 0 (point C). If there is such a decrease in rotational torque, it is possible to reliably determine when tapping is completed by confirming the decrease in rotational torque.

  When the screw further rotates, as shown in FIG. 8, the upper surface of the component 31 is seated on the seat surface 5c. Then, the seat 31 is further rotated after the seating, and when the tightening torque reaches an appropriate level (point D), the fastening is finished, whereby the attachment of the component 31 to the thin plate 30 is completed. This final tightening can be performed after confirming that the tapping has been completed as described above. Therefore, the final tightening can be performed with the recognition that the component 31 is just before seating. Can be prevented from shearing.

  On the other hand, when the torque change with respect to the rotation angle was measured in the same manner using a conventional tapping screw, it was as shown in FIG. As shown in FIGS. 9, 10, 11, and 12, the conventional tapping screw 40 is provided on the rear end side of the rod-like portion 41 and the rod-like portion 41 in which the thread groove is not formed in order from the front end side. An internal thread machining portion 42, a tapping portion 43 (cross hatch portion shown in FIGS. 9 and 10) provided in the internal thread machining portion 42, a standard thread portion 44 provided on the rear end side of the internal thread machining portion 42, It has a screw head 45 provided on the rear end side of the standard screw portion 44. The tapping portion 43 has a triangular shape in which each side of the cross-sectional shape is curved outward. The female thread machining portion 42 includes a tapered thread portion 46 and a thread portion 47 having the same diameter.

Further, the maximum diameter portion of the tapping portion 43 is the same as the screw diameter of the standard screw portion 44. Moreover, the tapping part 43 is provided in the female thread processing part 42 every 120 degrees. Further, a notch 48 as shown in FIG. 11 is formed between the tapping portions 43 of the female thread machining portion 42. Further, the tapping screw 40 has no shaft portion, and the length of the standard screw portion 44 is shorter than the sum of the thicknesses of the hole forming portion 32 of the thin plate 30 and the hole forming portion 36 of the component 31. It has become. The tapping screw and measurement conditions used for measuring the rotational torque change with respect to the rotation angle of the tapping screw shown in FIG. 13 are performed according to the conditions shown in (Comparative Example) and (Experiment) described later.
Using such a tapping screw, the component 31 is attached to the thin plate 30 by the tapping screw 40 as described above.

  After the fixing target part 31 is arranged on the surface of the thin plate 30 so that the holes of both the parts 30 and 31 overlap, the tapping screw 40 is inserted from the hole part of the fixing target part 31 and the screw is rotated to thereby form the thin plate 30. An internal thread 35 is formed. Specifically, when the tapping screw 40 is rotated, the peripheral portion of the hole formed in the cross shape of the thin plate 30 protrudes downward as shown in FIG. 9, and the hole portion of the thin plate 30 is formed by the tapping portion 43. A female screw 35 is formed in the portion 32. The rotational torque continues to increase gradually from the start of tapping (point A ′) to the point B ′ (peak of rotational torque), and after reaching point B ′, the upper surface of the component 31 contacts the seating surface 45c of the tapping screw 40. It decreases slightly until it becomes (C 'point). Then, as shown in FIG. 10, the rotational torque rapidly increases after contacting the seating surface 45c. Then, the tightening is finished at a time point (D ′) when an appropriate tightening torque is reached, and the attachment of the component 31 to the thin plate 30 is completed.

In the mounting operation of the parts using the conventional tapping screw 40, the difference between the rotational torque peak at the time of tapping (point B ′) and the rotational torque at the time of completion of tapping (point C ′) is small. This cannot be clearly determined. In such a case, there is a risk that tapping will be terminated before tapping is completed. Further, since it cannot be clearly determined that the tapping has been completed and the final tightening operation cannot be performed with the recognition that the component 31 is not seated, the female screw 35 may be sheared due to excessive tightening.
On the other hand, the tapping screw according to the embodiment of the present invention does not have such a problem and can clearly determine when the tapping is completed.
Although the tapping screw and the component mounting method using the tapping screw of the present invention have been described above, the tapping screw and the mounting method are not limited to the above-described embodiments.

Next, specific examples of the tapping screw of the present invention will be described.
(Example)
As shown in FIG. 1, the tapping screw includes a female thread processed portion, a male screw portion, a shaft portion, and a screw head, which are provided in order from the tip side.
The tapping screw has a pitch of 1.0 mm, a tapping portion screw diameter φ6.1 mm of the same diameter portion of the female screw processed portion, a female screw processed portion length of 8.0 mm (tapered screw portion length 5.0 mm, same diameter screw portion length 3.0 mm) ), A male screw part screw diameter φ 6.0 mm, a male screw part length 5.0 mm, a shaft part diameter φ 5.3 mm, and a shaft part length 2.0 mm. Further, as shown in FIG. 3, the cross-sectional shape of the tapping portion is a quadrangular shape that curves so that each side swells outward, and the tapping portion is formed every 90 °. And the surface of the tapping screw produced in this way was carburized.

(Comparative example)
As shown in FIGS. 9, 11, and 12, the tapping screw includes a rod-shaped portion, a female screw processed portion, a male screw portion, and a screw head, which are provided in order from the tip side.
The tapping screw has a pitch of 1.0 mm, a screw diameter of the tapping portion of the same diameter portion of the female screw processed portion, about φ6.0 mm, a screw diameter of the non-tapping portion of the same diameter portion of about φ5.0 mm, and a length of the female screw processed portion of about 7. 0mm (tapered thread length approx. 4mm, same-diameter threaded part 3mm), the inclination of the taper-shaped threaded part about 12 °, male threaded part screw diameter φ6.0mm, male threaded part length 4.0mm, shafted part diameter It is manufactured in a size such as φ5.3 mm and a shaft length of 2.0 mm. Further, as shown in FIG. 12, the cross-sectional shape of the tapping portion is a triangular shape that curves so that each side swells outward, and the tapping portion is formed every 120 °. Further, a cutout portion as shown in FIG. 12 is provided in the same diameter portion of the female thread processed portion at a position at 30 ° from the tapping portion. And the surface of the tapping screw produced in this way was carburized.

(Experiment)
Using the tapping screw produced in the example and the comparative example, the rotational torque with respect to the rotational angle when the component was attached to the thin plate was measured. The rotation torque was measured using a nut runner.
First, a component to be fixed having a thickness of 4 mm is placed on a thin plate made of SPCC having a plate thickness of 0.6 mm and SPCC so that the holes overlap, and both are fixed to the support bed. And when it tightened until a tapping screw fractured | ruptured with the rotational speed of 395 rpm, it became a result as shown in FIG.

FIG. 1 is a front view of a tapping screw according to an embodiment of the present invention (a drawing in which a thread is omitted). FIG. 2 is a partially enlarged view of the tapping screw shown in FIG. FIG. 3 is a bottom view of the tapping screw shown in FIG. FIG. 4 is a front view of a tapping screw according to another embodiment of the present invention. FIG. 5 is a front view of a tapping screw according to another embodiment of the present invention. FIG. 6 is an explanatory diagram for explaining a component mounting method using a tapping screw according to an embodiment of the present invention. FIG. 7 is an explanatory diagram for explaining a component mounting method using a tapping screw according to an embodiment of the present invention.

FIG. 8 is an explanatory diagram for explaining a component mounting method using a tapping screw according to an embodiment of the present invention. FIG. 9 is an explanatory diagram for explaining a component mounting method using a conventional tapping screw. FIG. 10 is an explanatory diagram for explaining a component mounting method using a conventional tapping screw. FIG. 11 is an enlarged view of a tip portion of a conventional tapping screw. FIG. 12 is a bottom view of a conventional tapping screw. FIG. 13 is a graph showing the torque change with respect to the rotation angle of the tapping screw according to the embodiment of the present invention and the conventional tapping screw.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tapping screw 2 Female thread processing part 3 Male thread part 5 Head 5c Seat surface 9a, 9b Thread 10 Tapping part 30 Thin plate 31 Parts 32 Hole formation part 35 Female thread 36 Hole formation part

Claims (11)

An internal thread processing portion for attaching a component to a thin plate and located on the distal end side, and forming a female screw in a hole formed in the thin plate or a hole formed in the component, and the female screw A tapping screw that is located on the rear end side from the processing portion and has a male screw portion that is screwed with a female screw formed by the female screw processing portion, and a head provided on the rear end side of the male screw portion, The internal thread machining portion and the external thread portion include a thread, and the internal thread processing portion has a tapping portion for machining the internal thread, and the radius of the tapping portion at the rear end of the internal thread processing portion is: The distance between the seating surface of the head and the rear end of the female screw processed portion is set so that the thickness of the hole forming portion of the thin plate and the hole forming portion of the component are larger than the radius of the male screw portion. Longer than the sum of thickness Furthermore, the distance between the seating surface of the head and the rear end of the male screw portion is shorter than the sum of the thickness of the hole forming portion of the thin plate and the thickness of the hole forming portion of the component. A tapping screw characterized by The tapping screw according to claim 1, wherein the tapping portion is a protruding portion forming portion provided on a thread of the female thread machining portion. The distance between the seating surface of the head and the rear end of the female thread processed portion is 1.0 P or more longer than the sum of the thickness of the hole forming portion of the thin plate and the thickness of the hole forming portion of the component. The tapping screw according to claim 1 or 2. The tapping screw according to any one of claims 1 to 3, wherein the projecting portion constituting the tapping portion is provided at a position that is substantially equiangular with respect to a central axis of the tapping screw of the thread. The tapping screw according to any one of claims 1 to 4, wherein a radius of a tapping portion at a rear end portion of the female screw processed portion is 0.03P to 0.15P larger than a radius of the male screw portion. The tapping screw according to any one of claims 1 to 5, wherein the tapping screw has a shaft portion that does not include a screw thread between the head portion and the male screw portion. The tapping screw according to claim 6, wherein the shaft portion has a breaking strength smaller than a shear strength of the female screw. The tapping screw according to any one of claims 1 to 7, wherein a tip end portion of the tapping screw is tapered toward the tip end. The tapping screw according to any one of claims 1 to 8, wherein a rotational torque value of the tapping screw upon completion of tapping is 50% or less of a peak value of the rotational torque at the time of tapping. The tapping screw according to any one of claims 1 to 9, wherein a rotational torque value at the completion of tapping of the tapping screw is substantially zero. 11. A component mounting method for mounting a component having a hole to a thin plate having a hole in which a female screw is not formed by using a tapping screw, the component mounting method comprising the tapping according to claim 1. A distance between the seating surface of the head and the rear end of the female thread machining portion is slightly longer than the sum of the thickness of the hole forming portion of the thin plate and the thickness of the hole forming portion of the component, and the head A tapping screw in which the distance between the seating surface of the part and the rear end of the male screw part is shorter than the sum of the thickness of the hole forming part of the thin plate and the thickness of the hole forming part of the component, and the surface of the thin plate is used. After the fixing target part is arranged so that both the holes match each other, the tapping screw is inserted from the hole part of the fixing target part and rotated, so that the female screw is inserted into the hole part of the thin plate by the tapping part. Forming part Further, the tapping portion is threaded through the thin plate and screwed with the male screw portion, and after confirming a decrease in rotational torque, final fastening is performed, and the component to the thin plate using the tapping screw is characterized in that Mounting method.

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