JPH0225048B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention involves performing burring on a thin metal plate and forming an internal thread on the inner peripheral surface of an annular lip (hole flange) formed by the burring. Regarding the tuft pin screw that is screwed in.

Prior Art As a conventionally known example of this kind of tatsu pin screw for a metal plate with a pilot hole, there is
There are Jitsugoku No. 56-47379, etc. The tatsupin screws in these known examples have a square pyramid section with a square cross section provided at the lower end of the screw shaft, and the tip of the square pyramid section is filled into the target thin metal plate, and the head of the tatsupin screw is struck. and pierce the square pyramid into a thin metal plate,
A circular lip is formed on the back side of the thin metal plate by penetrating it and burring, and then the tap pin screw is rotated in the direction of screwing while pressing it, and a female screw is tapped on the inner circumferential surface of the circular lip and screwed in. It is something that

Problems to be Solved by the Invention When the burring process is performed by hitting and piercing the square pyramid part, such as the tutpin screw in the above-mentioned known example, it is difficult to accurately center the annular lip, and the burring process is difficult. The disadvantage is that the annular lip is prone to cracking. In addition, in the case of tut pin screws that are burred into a metal plate with a prepared hole, the protrusion of the annular lip that pushes out to the edge of the prepared hole increases, and it is not possible to screw each tut pin screw all the way in at once. Tatsupin screws must be temporarily tightened and then screwed in, which makes the work of tightening the tatsupin screws troublesome, leading to deterioration of work efficiency. Furthermore, if the annular lip does not protrude sufficiently, there will inevitably be insufficient room for forming a female thread, resulting in a reduction in tightening strength.

The present invention was made in view of the above circumstances, and it is possible to accurately center a tuppin screw in the pilot hole, and furthermore, to center an annular lip, without requiring any skill. The tatsupin screw can be accurately perpendicular to the plate, and the tatsupin screw can be screwed into the metal plate all at once without temporarily tightening the tatsupin screw, improving work efficiency. By increasing the amount of protrusion of the annular lip as much as possible, it is possible to ensure a sufficient margin for forming a female thread, and also to effectively solve the problem of cracking. A portion of the screw is polished to remove burrs and smooth the metallographic structure, resulting in a precisely finished state, and the hole diameter is also accurate, allowing the tapped screw to hold the metal with great holding force. It is an object of the present invention to provide a tatu pin screw for a metal plate with a pilot hole that can be held on a plate.

Means for Solving the Problems The tatsupin screw for a metal plate with a prepared hole according to the present invention includes a screw shaft portion having a male thread formed on the circumferential surface, a head provided at the base end of the screw shaft portion, The threaded shaft part integrally has an unthreaded shaft part provided concentrically with the threaded shaft part at the tip of the threaded shaft part, and the unthreaded shaft part is further attached to a mating metal plate. A cylindrical guide shaft portion having a slightly smaller diameter or the same diameter as the pilot hole to be provided and constituting the most distal end of the unthreaded shaft portion, and a space between the base end of this guide shaft portion and the tip of the threaded shaft portion. are formed at equal intervals in the circumferential direction,
It has a plurality of ridges extending in the axial direction of the unthreaded shaft, and each ridge starts from the base end of the guide shaft and widens outward toward the threaded shaft. , an inclined top surface that terminates at the intermediate portion of each ridge, and an axial center of the unthreaded shaft portion at approximately the same height as the root of the male thread between the end of the inclined top surface and the tip of the threaded shaft portion. It has a parallel top surface extending parallel to the top surface.

Function: First, the guide shaft portion of the non-threaded shaft portion is fitted into the pilot hole provided in the thin metal plate. As a result, the tuft pin screw is accurately centered with respect to the prepared hole, and the tatu pin screw is accurately orthogonal to the thin metal plate.

Next, when the Tatsupin screw is screwed into the prepared hole from this state, the inner peripheral edge of the prepared hole is first expanded by the slanted top surface of the ridge, and is perpendicular to the back side of the thin metal plate. An annular lip of a certain amount is formed (ie, burred).

Next, the parallel top surface of the ridge is rubbed against the inner peripheral surface of the annular lip, and the annular lip is deburred and the metal structure of the roughened inner peripheral surface of the annular lip is smoothed and refined. The hole diameter is also accurate. Further, when screwing is continued, the inner peripheral surface of the annular lip is tapped by the screw shaft, and the screw shaft is screwed into the inner peripheral surface of the annular lip.

Embodiments Hereinafter, specific embodiments of the present invention will be described in detail based on the drawings.

The tuft pin screw A shown in the embodiment of the drawings includes a screw shaft portion 3 having a male thread 2 provided on its circumferential surface, a head portion 1 provided at the tip of the screw shaft portion 3, and a tip end 3a of the screw shaft portion 3. It integrally includes a non-threaded shaft portion 5 which is not provided with a thread and is concentric with the screw shaft portion 3 provided on the shaft.

The distal end side of the unthreaded shaft portion 5 is shaped like a cylinder, and the diameter of this cylindrical portion is determined by a prepared hole 7 such as a crimp-punch hole drilled in a thin metal plate 6 into which the tatu pin screw A is to be screwed. Set to a slightly smaller or equal diameter. Further, the most extreme edge of this cylindrical portion is chamfered.

A non-threaded conical shaft portion 4 is formed in a portion of the non-threaded shaft portion 5 between the cylindrical portion and the threaded shaft portion 3 and has a tapered truncated conical shape whose diameter gradually decreases toward the distal end. has been done. The tip 4b of the unthreaded conical shaft portion 4 has the same diameter as the cylindrical portion.

As another example, although not shown, the unthreaded conical shaft portion 4 may also have a cylindrical shape, and the cylindrical portion may have a smaller diameter. In this case, it is preferable that the large-diameter and small-diameter cylindrical portions are connected to each other via an inclined surface.

A plurality of ridges 9 are formed on the circumferential surface of the non-threaded shaft portion 5 at equal intervals in the circumferential direction. In the embodiment shown in the drawings, four ridges 9 are provided. Each ridge 9 starts from the middle part of the unthreaded shaft part 5 and ends at the base end of the conical shaft part 4 (in other words,
(to the tip 3a of the threaded shaft portion 3), and extends in the axial direction of the unthreaded shaft portion 5 (this axial direction coincides with the axial direction of the entire tuft pin screw A). A ridge 9 on the tip side of the cylindrical portion of the non-threaded shaft portion 5
The portion where is not provided constitutes a guide shaft portion 5a.

Further, each ridge 9 starts from the tip of each ridge 9 (that is, the base end of the guide shaft portion 5a), spreads outward toward the screw shaft portion 3, and ends at the middle portion of each ridge 9. A terminating inclined top surface 9f, and a parallel line extending parallel to the axis of the unthreaded shaft section 5 at approximately the same height as the root of the male thread 2 between the terminal end of the inclined top surface 9f and the tip of the threaded shaft section 3. It has a top surface 9e. Moreover, when viewed from above, each ridge 9 has its tip 9b
It has a long delta shape that widens toward the vicinity of the base end 9a, and the intersections of both side surfaces of the widened end with the inclined top surface 9f and the parallel top surface 9e form arcuate edges 9d, 9d. are doing. Further, each ridge 9 has a shape that suddenly widens near its base end 9a.

Next, screwing the tuft pin screw A into the thin metal plate 6 will be explained using FIG. 3.

First, the guide shaft portion 5a of the unthreaded shaft portion 5 located at the tip of the tuft pin screw A is attached to a thin metal plate 6.
It fits into the pilot hole 7 of the. As a result, the tuft pin screw A is accurately centered with respect to the pilot hole 7, and the tatu pin screw A is accurately orthogonal to the thin metal plate 6.

Next, when the Tatsupin screw A is screwed into the prepared hole 7 from this state, the inner circumferential edge of the prepared hole 7 first undergoes retrograde deformation due to the sloped top surface 9f of the ridge 9 and the arcuate edges 9d on both sides thereof. The annular lip 8 is pushed out downwardly, and a sufficient amount of annular lip 8 is formed perpendicularly to the back side of the thin metal plate 6.
is formed (that is, burring is performed; see FIGS. 3A and 3B).

When the tuft pin screw A is continued to be screwed in, the thin metal plate 6 passes through the inclined top surface 9f, and the parallel top surface 9e of the ridge 9 rubs against the inner peripheral surface of the annular lip 8. At the same time, the metal structure of the inner circumferential surface roughened by the inclined top surface 9f is smoothed, and the metal structure is precisely finished.
The hole diameter is also made accurate. In this way, an annular lip 8 having a sufficient protrusion is provided on the back side of the thin metal plate 6 as a space for forming an internal thread (see FIG. 3C).

Further, when the tuft pin screw A is continued to be screwed in, the annular lip 8 is opened by the male thread 2 of the screw shaft portion 3.
The inner circumferential surface of the annular lip 8 is tapped, and the screw shaft portion 3 is screwed into the inner circumferential surface of the annular lip 8 (see FIG. 3D).

As mentioned above, the tuft pin screw A according to the present invention is
The guide shaft portion 5a ensures alignment and upright posture of the thin metal plate 6 with respect to the prepared hole 7, and then the material is pushed away evenly in the radial direction by the plurality of ridges 9 that gradually become higher around the shaft to perform burring processing. As shown in FIG.
When attaching the attached member 10 to the attached member 10 using a large number of tut pin screws A, it is not necessary to screw the first tut pin screw A1 into the pilot hole 7 of the thin metal plate 6 and the mounting hole 11 of the attached member 10 all the way in one go. , without causing any center deviation between the other prepared hole 7 and the mounting hole 11, and from now on, the second tut pin screw A2, the third tut pin screw A3, etc. can be properly tightened without temporarily tightening them. Burring and tapping can be performed with posture.

Next, another embodiment of the tuft pin screw A according to the present invention will be described.

The tuft pin screw A according to the present invention can be implemented when the thickness of the metal plate 6 is relatively thick or when the material thereof is relatively hard. For example, as shown in FIG. 9 is further formed with a second parallel top surface 9e' and a second inclined top surface 9f', so that the parallel top surface and the inclined top surface are alternately arranged in multiple stages, as shown in FIGS. 1 to 4. Including cases where it is used in the same way as Tatsupin screw A.

As yet another example, although not shown,
The ridge 9 may be formed in an inverted delta shape, that is, in a shape that widens from the base end 9a to the tip 9b of the ridge 9.

Effects of the Invention As described above, the tuft pin screw according to the present invention has the following features: (a) By fitting the guide shaft portion into the pilot hole previously formed in the metal plate, it is possible to accurately fit the pilot hole into the pilot hole without requiring any skill. It is possible to center the tuft pin screw and, by extension, to center the annular lip, and also to make the tuft pin screw accurately perpendicular to the metal plate.

(b) Since the inclined top surface of the ridge is rotated and expands the pilot hole to form an annular lip, the tut pin screw can be screwed into the metal plate at once without temporarily tightening the tut pin screw, improving work efficiency. Furthermore, by increasing the amount of protrusion of the annular lip pushed out to the edge of the pilot hole as much as possible, it is possible to ensure a sufficient margin for forming the internal thread, and to effectively solve the problem of cracking.

(c) Before the inner circumferential surface of the annular lip is tapped, it is rubbed against the parallel top surface of the ridge to remove burrs and to smooth out the metal structure roughened by the sloped top surface to make it precise. It is in a finished state, and the hole diameter is accurate, so that the screw that is screwed in is held in the metal plate with a large holding force.

(d) Paragraph (a) above allows the use of electric screwdrivers, etc.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIG. 1 is a front view of the first embodiment of the tuft pin screw according to the present invention, FIG. Figure 2B is an enlarged sectional view taken along the line A-A in Figure 2A, Figures 3A to D are enlarged front views of the metal plate showing each step of screwing in the tutpin screw, and Figures FIG. 4 is a front view illustrating the case where a large number of the tuft pin screws are screwed in, and FIG. 5 is an enlarged front view of the essential parts of the second embodiment of the tatu pin screw. A... Tatsupin screw, 1... Head, 2... Male thread, 3... Threaded shaft, 4... Unthreaded conical shaft, 5
...Unthreaded shaft portion, 5a... Guide shaft portion, 6... Thin metal plate, 7... Pilot hole, 9... Ridge, 9e... Parallel top surface, 9f... Inclined top surface.

Claims (1)

[Claims] 1. A screw shaft having a male thread formed on its circumferential surface, a head provided at the base end of the screw shaft, and a head provided concentrically with the screw shaft at the tip of the screw shaft. and an unthreaded shaft portion which is not provided with a screw, the unthreaded shaft portion further having a slightly smaller or equal diameter than the pilot hole provided in the mating metal plate, A cylindrical guide shaft portion constituting the most distal end of the screw shaft portion, and formed at equal intervals in the circumferential direction between the base end of the guide shaft portion and the tip of the screw shaft portion,
It has a plurality of ridges extending in the axial direction of the unthreaded shaft, and each ridge starts from the base end of the guide shaft and widens outward toward the threaded shaft. , an inclined top surface that terminates at the intermediate portion of each ridge, and an axial center of the unthreaded shaft portion at approximately the same height as the root of the male thread between the terminal end of the inclined top surface and the tip of the threaded shaft portion. A tatsu pin screw for metal plates with a pilot hole, which has a parallel top surface extending parallel or substantially parallel to the surface of the metal plate.