JPH04109215U - Tatsu pin screw for thin plate - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a tapping screw for thin plates that has a high maximum screw tightening torque and can reliably prevent loosening of the screw when fixing parts to a relatively thin plate-shaped workpiece. [Structure] At least the base side of the screw threads 20 is formed at a gentle angle on the play side flank surface 22 of the plurality of asymmetric threads 20 of the leg portion 3 close to the seat surface, and the interval between the valley portions 23 at the base is This is a tapping screw for a thin plate in which the distance between the troughs 24 on the tip side of the leg portion 3 is narrower. [Effect] At the initial stage of screwing, it is relatively easy to screw the screw into the workpiece, and when the workpiece approaches the head seat, the part with the idle side flank surface is screwed in, which reduces friction between this screw thread and the workpiece. The force increases, the maximum screw tightening torque improves, and the screw loosening function can be reliably obtained after tightening is completed.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention is a screwdriver that is screwed into a pre-formed hole while forming a thread. For pin screws, in particular, screws for thin plates are used to fix parts to relatively thin plate-shaped workpieces. Regarding pin screws.

0002

[Conventional technology]

Conventionally, when fixing parts to such a relatively thin plate-like work, this work In addition to preventing the work piece from escaping in the axial direction or causing cracks, the In order to make the maximum screw tightening torque TM just before breaking the screw as high as possible, When the thread angle is made smaller than that of the thread, the angle of the flank surface that forms the thread becomes smaller. Asymmetrical screws are used. In addition, the contact area between the screw thread and the workpiece should be Tapping screws with finer thread pitches are used to increase the number of threads. Furthermore, in order to increase the contact area between the workpiece and the screw thread, the screw head bearing surface Some have two threads formed near the part.

0003

[Problem that the idea aims to solve]

However, all the threads on the legs are asymmetrical and the spacing between the valleys is the same. In order to continuously form female threads on the workpiece during screwing, the workpiece cracks are less likely to occur, but on the other hand, there is less frictional resistance in the axial and radial directions of the thread. Improved maximum screw tightening torque (the torque just before breaking the female thread) and sufficient loosening. No stopping effect can be obtained. The same applies to screw threads with finer pitches. Furthermore, in the case of a leg with two threads formed close to the seat surface, screwing operation is not possible. In order to form the second thread on the work piece from the middle of the work, the first thread formed on the work piece is This causes various problems such as the internal threads of the parts being easily broken and the parts being insufficiently fixed to the workpiece. It's working.

0004 The present invention solves these problems and makes it possible to obtain proper screwing action. A self-tapping screw for thin plates that improves the maximum screw tightening torque and has a reliable locking effect. It was devised for the purpose of providing the same.

[0005]

[Means to solve the problem]

The present invention achieves such an object, and has legs 3 on the seat surface of the head 2. The angle between the pressure side flank surface 21 and the plane that crosses the axis of the leg 3 is The asymmetric thread 20 is made up of an idle side flank surface 22 with an angle less than In the formed tapping screw 1, a plurality of asymmetric screws on the leg portion 3 close to the seat surface At least the base side of the thread 20 is inclined at the play side flank surface 22 of the thread 20. The interval between the troughs 23 at the base is set at a gentle angle, and the troughs 24 at the tip end of the leg 3 are These are self-tapping screws for thin plates with narrower spacing than .

[0006]

[Effect]

In this way, the plurality of threads 20 in the portion of the self-tapping screw 1 close to the head bearing surface are It is symmetrical and tilts at least the base side of the thread 20 on the play side flank surface 22. Since the grooves 23 are formed at a gentle angle and the intervals between the valleys 23 are narrow, the female thread of the workpiece 30 is The same is drawn into the trough 23 by the pressure side flank surface 21, and the play Sandwiched between the side flank surfaces 22, the maximum screw tightening torque is improved and the screw loosens. is prevented.

[0007]

【Example】

Hereinafter, embodiments of the present invention will be described based on the drawings. In Fig. 1, 3 is the tack for thin plate. This is a leg formed on the seat surface of the head 2 of the pin screw 1, and this leg 3 is a straight part. 10, and a conical portion 11 that is continuous with the conical portion 10 and has a tapered tip. this strike A thread 20 is formed on the rate part 10 and the conical part 11, and this thread 20 is The height decreases as you reach the edge. Also, is this thread 20 at the tip? The pressure side flank surface 21 is a steep slope with an inclination angle α relative to the plane that crosses the leg portion 3. , an asymmetric thread 2 in which the play side flank surface 22 is a slope with a gentler inclination angle β. It is 0. Furthermore, as shown in FIG. The plurality of screw threads 20 at positions 2 and 3 are on the so-called pressure side flank surface 21 on the head seat side. It is formed on a slope with a steep angle of inclination α to the plane that crosses the axis; The play side flank surface 22 on the opposite side of the surface has a screw thread tip side with an inclination angle β, and a base side side with an inclination angle β. A compound angle slope is formed by a gentle slope with an inclination angle γ. These angles are The relationship is α<β<γ, and the interval between the valleys 23 between these threads 20 is is relatively narrower than the interval between the troughs 24 on the tip end side of the leg due to the slope with the inclination angle γ. There is.

[0008] Moreover, FIG. 3 is a sectional view of the leg part showing another embodiment, and the leg part close to the head seat surface. The plurality of threads 20 of No. 3 have a pressure side flank surface 21 with respect to a plane that crosses the axis. As in the previous embodiment, the flank surface 21 is formed at an angle of inclination α. On the free side flank surface 22 on the opposite side of the degree, and the longer base side than the above embodiment is sloped with a compound angle consisting of a gentler slope angle γ. A surface is formed.

[0009] For this reason, the tip of the leg 3 of the tapping screw 1 that fixes the component 31 is set in advance. When the workpiece 30 is pressed into the specified hole and the screwing operation starts, the workpiece The screw is screwed in while forming an internal thread in the hole No. 30. At this time, the female thread of the hole is The screw thread 20 on the tip end of the leg allows it to be formed into a normal shape with the screwing torque TS. , a compound square screw thread 20 formed at a position close to the head seat is screwed in. , the workpiece 30 is deformed along this direction, and as shown in FIG. 20 is pulled toward the head side by the pressure side flank surface 21, and the free side It comes to be sandwiched between it and the flank surface 22. On the other hand, in this way, the screw thread 20 and The workpiece 30 sandwiched between the screw thread 20 enters the narrow valley 23, and as shown in FIG. In addition, the maximum screw tightening torque TM is significantly improved. In this way, screw tightening work is done. When completed, complete screw locking action will be obtained.

0010 In these examples, all of the play side flank surfaces are formed with compound angles, but However, it is not limited to this, and it is possible to use a gentle straight slope from the tip of the thread to the base. It may be a surface.

[0011]

[Effect of the idea]

As is clear from the embodiments described above, the present invention is applicable to the head bearing surface of the self-tapping screw 1. It has a pressure side flank surface 21 with a steep slope at a position close to the pressure side. At least the base side of the thread 20 is formed at a gentle angle on the opposite side of the flank surface 21. The gap between the troughs 23 at the base is adjusted to the width of the leg. 3. Since the spacing is narrower than the gap between the grooves 24 on the tip side, the initial screw-in period is relatively narrow. It is easy to screw the screw into the workpiece, and there is no play when the workpiece approaches the head seat. Since the part with the side flank surface is screwed in, there is no friction between this thread and the workpiece. The friction force increases, the maximum screw tightening torque improves, and the screw loosens after tightening is completed. A blocking effect can be obtained reliably. Also, it is used to form threads on the workpiece from the middle. Since there are no can get.

0012

[Brief explanation of drawings]

FIG. 1 is a front view showing the tightened state of the present invention.

FIG. 2 is an enlarged sectional front view of essential parts showing an embodiment of the present invention.

FIG. 3 is a sectional front view of main parts showing another embodiment of the present invention.

FIG. 4 shows the screw tightening characteristics according to the present invention.

FIG. 5 shows the screw tightening characteristics of a conventional screw.

[Explanation of symbols]

1 Tapping screw 2 Head 3 Legs 10 Straight part 11 Conical part 20 Screw thread 21 Pressure side flank surface 22 Free side flank surface 23, 24 Tanibe 30 work 31 Parts

Claims (1)

[Scope of utility model registration request] [Claim 1] The seat of the head (2) has legs (3),
This leg (3) is an asymmetrical thread consisting of a pressure side flank surface (21) and an idle side flank surface (22) whose angle is less than the angle formed by this surface and a plane that crosses the leg (3). In the self-tapping screw (1) formed with threads (20), at least the threads (20) are formed on the play side flank surface (22) of the asymmetrical plurality of threads (20) of the leg (3) close to the seat surface. ) is formed with a gentle angle of inclination, and the interval between the troughs (23) at the base is set to the base side of the leg (3).
A tapping screw for a thin plate, characterized in that the interval is narrower than the interval between the troughs (24) on the tip side of the screw.