JP3112359U - Tapping screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a head even when a large torsional load is generated between the body of a screw head and a body when an engaging portion of a driver bit is engaged with a driving hole of the head and rotated. Provided is a tapping screw that can prevent torsional breakage at the base portion of the screw.
A tapping screw 10 having a head portion 11 and a neck portion 12 continuous with the head portion 11 and having a screw portion 13b formed in a spiral shape on a body portion 13 continuous with the neck portion 12, the screw The crests 14 of the part 13b are formed to have the same outer diameter, and the troughs 14a are formed to reduce in diameter as they approach the tip.
[Selection] Figure 1

Description

  The present invention relates to a tapping screw, and more particularly to a tapping screw that can prevent torsional breakage at the base of the head during tightening.

  2. Description of the Related Art Conventionally, when a lightweight member such as a thin plate is assembled, a tapping screw that can omit a tapping fastening process for forming a female screw in advance on the member has been frequently used. The tapping screw does not have to be formed in advance with a mating member to be fastened, and is fastened at the same time while forming the female screw with the tapping screw itself in the prepared hole corresponding to the male screw.

  However, the tapping screw is forcibly screwed while forming the female screw in the pilot hole not formed with the female screw provided in the mating member to be fastened by engaging the engaging part of the driver bit with the driving hole of the head and rotating it. Therefore, a large torsional load is generated between the trunk part screwed into the hole at the base part of the head, and the torsional stress with the trunk part increases at the base part of the head. There was a problem that a torsional breakage occurred at the base portion, and the head portion could be removed from the trunk portion.

  This invention solves the above-mentioned problem, and when the engaging part of the driver bit is engaged with the driving hole of the head and rotated, the root part of the head of the screw is between the trunk part. The present invention provides a tapping screw that can prevent torsional breakage at the base of the head even when a large torsional load occurs.

  In order to solve the above-mentioned problem, a device according to claim 1 is a tapping screw having a head portion and a neck portion continuous to the head portion, and a screw portion spirally formed on a body portion continuing to the neck portion. The tapping screw is characterized in that the crests of the screw part are formed to have the same outer diameter, and the trough part is formed to reduce in diameter as it approaches the tip.

  According to the second aspect of the present invention, the lower surface of the head is formed into a tapered shape chamfered at a first angle, and the peripheral surface of the neck continuous with the head is steeper than the first angle. The tapping screw according to claim 1, wherein the tapping screw is formed in a tapered shape at an angle of 2.

  According to the tapping screw of the present invention, the engagement portion of the driver bit is engaged with the head drive hole and rotated, and a large torsional load is generated between the base portion of the screw head and the trunk portion. However, it is possible to prevent torsional breakage at the base of the head.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 is a front view of an embodiment of a tapping screw according to the present invention, FIG. 2 is an enlarged cross-sectional view of a portion A in FIG. 1, FIG. 3A is a plan view of FIG. 1, and FIG. It is a bottom view.

  1 to 3, a drive hole (cross groove in FIG. 3 (a)) 11b is formed on the upper surface 11a of the head 11 of the tapping screw 10 of the present invention. Has been. The lower peripheral surface 11c of the head 11 is formed in a tapered shape that is chamfered at a first angle. Further, the neck portion 12 is formed integrally with the head portion 11, and the peripheral surface 12 a is chamfered at a second angle that is steeper than the tapered first angle of the lower peripheral surface 11 c of the head portion 11. It is formed in a tapered shape. In addition, the body portion 13 is integrally formed continuously with the lower portion of the neck portion 12.

  The body portion 13 is formed of a cylindrical portion 13a whose upper peripheral surface is chamfered flat, a threaded portion 13b is formed in the center portion, and a cutting portion in which a groove 15 whose lower portion is inclined in the axial direction is formed. 13c. In the cutting part 13c, the edge of the groove 15 is a cutting edge 15a.

  In the trunk portion 13, the diameter of the peripheral surface of the upper cylindrical portion 13a and the diameter of the crest portion 14 forming the spiral screw portion 13b in the center portion are formed to the same outer diameter, and the trough portion 14a of the screw portion 13b The upper side is substantially the same as the diameter of the circumferential surface of the cylindrical portion 13a, and is formed so as to reduce in diameter as it approaches the tip.

  Therefore, the diameter of the shaft core 13d that protrudes and supports the peak portion 14 on the outer periphery is formed so as to be thicker toward the upper side of the trunk portion 13 in the portion having the valley portion 14a as the outer periphery, so that it is difficult to cause torsional fracture. Yes. In addition, the lower peripheral surface 11c of the head 11 is formed in a tapered shape chamfered at a first angle, and the peripheral surface 12a of the neck 12 formed continuously and integrally with the head 11 is 11 is formed in a tapered shape with a chamfered second angle that is steeper than the tapered first angle of the lower peripheral surface 11c of the lower peripheral surface 11c. In addition, the diameter of the head 11 on the upper side of the neck 12 is also made thicker than that of the neck 12.

  Next, the operation will be described. A prepared hole is provided in advance in a mating member (not shown) for fastening the tapping screw 10. Then, when an engaging portion of a driver bit (not shown) is engaged with the drive hole 11b of the head portion 11 of the tapping screw 10 and the tapping screw 10 is rotated, the tapping screw 10 is attached to the edge of the groove 15 of the tip portion 13c. The prepared hole in which the female screw is not formed is cut and enlarged by the cutting blade 15a, and the threaded portion 14b of the screw portion 13b is forcibly screwed while forming the female screw in the enlarged prepared hole.

  At this time, since the tapping screw 10 is rotated by engaging the engaging portion of the driver bit with the driving hole 11b of the head portion 11, the body portion screwed into the lower hole at the base portion of the head portion 11 A large torsional load is generated between the two.

  However, the diameter of the valley portion 14a in the screw portion 13b is substantially the same as the diameter of the circumferential surface of the cylindrical portion 13a, and the diameter decreases as the tip approaches the tip, and the shaft core 13d has the valley portion 14a of the screw portion 13b as the outer periphery. The diameter is thicker toward the upper side of the body portion 13 and has a structure in which torsional breakage hardly occurs.

  In addition, the diameter of the neck portion 12 on the upper side of the body portion 13 is also formed so as to be tapered toward the upper side, and the diameter of the head portion 11 on the upper side of the neck portion 12 is also formed to be thicker than the neck portion 12 in a tapered shape toward the upper side. Even if a large torsional load occurs between the root portion of the screw head 13 and the body portion 13, torsional breakage at the root portion of the head 11 can be prevented.

  The present invention is not limited to the above-described embodiment, and various design changes can be made without departing from the present invention described in the claims of the utility model registration, and the present invention is not limited to the above-described embodiment. Needless to say.

It is a front view of the Example of the tapping screw which concerns on this invention. It is an expanded sectional view of the A section of FIG. (A) is a top view of FIG. 1, (b) is a bottom view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tapping screw 11 Head 11a Upper surface 11b Drive hole 12 Neck part 13 Body part 13a Cylindrical part 13b Screw part 13c Tip part 13d Shaft core 14 Mountain part 14a Valley part 15 Groove 15a Cutting blade

Claims (2)

  A tapping screw having a head and a neck continuous with the head, and a threaded portion formed in a spiral on a body continuous with the neck, wherein the crests of the screw are formed to have the same outer diameter. The tapping screw is characterized in that the trough is formed so as to reduce in diameter as it approaches the tip.   The lower surface of the head is formed into a tapered shape chamfered at a first angle, and the peripheral surface of the neck continuous with the head is formed into a tapered shape at a second angle that is steeper than the first angle. The tapping screw according to claim 1.

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