JP2007292193A - Rubbing-cutting type self-punching screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubbing-cutting type self-punching screw for enhancing quickness of screwing-in work and fastening strength. <P>SOLUTION: The screw is composed of a shaft 1 and a head part 2, and a tip part of the shaft 1 is formed as a tapering-off part 3. Among the shaft 1, a part except for the tapering-off part 3 is mainly composed of a large diameter part 6 positioned on the head side, and a small diameter part 7 positioned on the tip side. A first thread 4 and a second thread 5 extend to the large diameter part 6 from the small diameter part 7. Both threads 4 and 5 are different in the height in both parts of the large diameter part 6 and the small diameter part 7. Since both threads 4 and 5 are different in the height over the whole, screwing-in resistance to a base material 11 is restrained from becoming excessively high. Since the large diameter part 6 also bites in a frame material (the base material) 11, hitching resistance of the base material 11 to the threads 4 and 5 is increased, and as a result, high fastening strength is secured. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a self-drilling screw (screw) of a type with a sharpened tip.

  There are two types of self-drilling screws: a chopping type with a sharp tip and a drill type with a drill part with a cutting edge at the tip. The former type of chopped screw makes the shaft enter the member by expanding the structure of the member (work) at the tapered portion with the sharpened tip, and the base material made of soft material such as wood For example, it is frequently used to fasten various workpieces to a thin steel plate substrate having a plate thickness of about 0.5 to 1.2 mm.

  Various improvements have been made to chopped self-drilling screws. For example, two threads are formed on the shaft, and various development examples have been proposed based on the two-thread system. For example, a portion of the shaft excluding the tapered portion is formed in a straight shape having a constant valley diameter over the entire length, and the heights of the two threads are made different from each other.

  On the other hand, in Patent Document 1, in which the entire thread portion is composed of two threads, the height (or outer diameter) of both threads is the same in a certain range on the head side of the thread portion. It is described that it is formed with the same high portion, and a portion of the screw thread on the tip side of the high height portion is formed with a different height portion where the heights of both screw threads are different.

Further, in Patent Document 2, when the entire thread portion is formed of two threads, the thread portion is divided into a small-diameter parallel thread portion located on the distal end side and a large-diameter parallel thread portion located on the head side. And a tapered intermediate threaded portion that smoothly connects the small-diameter parallel threaded portion and the large-diameter parallel threaded portion.
JP 2001-200222 A Japanese Patent No. 3334563

  Self-drilling screws are used in various applications, and one of the applications is to fasten a gypsum board constituting a wall or ceiling of a building to a frame material. Conventionally, wood has been widely used as a frame material (base material) constituting walls and ceilings. However, in recent years, in order to improve fire resistance and durability, for example, a thickness of about 0.5 to 1.2 mm and a cross section of about C A thin steel plate frame material (underlying material) formed in a letter shape is often used.

  In any case, the work is fastened by the screw thread biting into the base material. If the outer diameter of the tip side portion is formed in a tapered shape as in Patent Document 2, the work enters the base material. Can be said to be easy.

  By the way, when two threads are formed, the lead angle of each thread can be increased, so that the length of the screw that advances per rotation can be increased, and there is an advantage that the working efficiency can be improved. However, in the case where two threads are set to the same height in each part as in Patent Document 2, if the height of the thread becomes high, the screwing resistance becomes too large, and if the height of the thread is made low, the base material There is a problem that the hooking resistance becomes small and the fastening strength becomes weak.

  The present invention has been made in view of such a current situation, and an object of the present invention is to provide a trimmed self-drilling screw having an improved form.

  The self-drilling screw according to the present invention includes a shaft having a circular cross section and a head portion provided at the base end thereof, and a tip portion of the shaft opposite to the head portion is sharpened at the leading edge. A threaded portion formed with a plurality of threads starting from a tapered portion on the shaft, and an engaging portion on which the driver bit is fitted on the head. It is a basic configuration.

  In the invention of claim 1, as a feature, the portion of the screw portion of the shaft excluding the tapered portion is divided into a plurality of portions adjacent in the axial direction, and the adjacent portions are The trough diameter of the part located on the part side is set to be larger than the trough diameter of the part located on the tip side, and at least a part of the thread located on the head side of each part The heights are different from each other.

  The invention of claim 2 further embodies the invention of claim 1, and the self-drilling screw according to this invention is such that a portion of the screw portion excluding the tapered portion is located on the head side. The large diameter portion, the small diameter portion located on the distal end side, and a tapered portion for smoothly connecting the large diameter portion and the small diameter portion, and two strips of the first thread and the second thread Are formed in a state where the heights are different from each other in each part, and in addition, in the large diameter part and the small diameter part, the valley diameter and the outer diameter of both screw threads are respectively substantially straight. It has become.

  The invention of claim 3 is devised as a form suitable for fastening a work made of a brittle (or very soft) material such as a plaster board to a base material. The head is formed in a trumpet shape having a curved profile that is curved in a longitudinal sectional view with the outer diameter gradually expanding toward the top surface, and the outer peripheral edge is a flange having the same thickness. The outer periphery of the flange portion is set to a size larger than twice the maximum outer diameter of the threaded portion.

  As described above, in the self-drilling screw, when the thread portion is composed of a plurality of threads such as a double thread, the lead angle of the thread can be increased, so that the screwing operation can be performed quickly.

  And in this invention, while the front end side is small diameter among screw parts, while the initial approach to a workpiece | work and a base material is made easy, and the head side is large diameter, it is a screw thread to a base material. It is possible to obtain a high fastening strength by firmly biting in, and moreover, since the multiple threads are different in height at least at the head side portion, It is possible to suppress an excessive increase in screwing resistance while firmly biting into the material.

  In summary, the self-drilling screw of the present invention can improve the fastening strength and reduce the labor required for the fastening operation while maintaining the advantage of the multi-thread screw that can perform the fastening operation efficiently.

  Now, gypsum board is often used as an interior material for buildings mainly in houses, but in recent years, gypsum board tends to be reduced in strength because it often contains waste materials. In this respect, when the head is structured as in claim 3, the head has a flange portion, and the outer diameter of the flange portion is larger than twice the maximum outer diameter of the screw portion (of the conventional screw head). The outer diameter is almost twice the outer diameter of the threaded portion), and the pressing force against the work is improved, so that it is particularly suitable for fastening a gypsum board that is more brittle than conventional ones, for example. In addition to the gypsum board, it is also suitable for fastening a work made of a soft material that is elastically deformed (compressed and deformed) such as a heat insulating material.

  Next, an embodiment of the present invention will be described with reference to the drawings. 1 to 2 show the first embodiment. First, the first embodiment will be described.

(1). Structure of the First Embodiment In FIG. 1, (A) is a front view of a self-drilling screw, (B) is a front view in a state where a screw thread is omitted, (C) is a plan view, and (D). FIG. 4 is a partial cross-sectional view. In (D), the parallel diagonal lines (hatching) of the cross-sectional display are only partially displayed.

  The self-drilling screw includes a shaft 1 having a circular cross section and a head 2 integrally connected to the base end thereof, and the tip of the shaft 1 opposite to the head 2 has a pointed tip. It is a narrowed portion 3. The taper angle of the tapered portion 3 is set to about 25 degrees. In addition, although the tapered portion 3 of the present embodiment is formed in a conical shape, it can be formed in a bullet shape having a curved shape in a longitudinal sectional view.

  Two threads of the first thread 4 and the second thread 5 are formed on the shaft 1, and a flat valley is exposed between the adjacent threads 4 and 5 in a sectional view. is doing. Both screw threads 4 and 5 start (rise) from the constricted portion 3, and both screw threads 4 and 5 extend to the vicinity of the neck (the end of the screw threads 4 and 5 and the head 2 There may be an unthreaded portion between them.) In addition, the height of the first thread 4 is higher than the height of the second thread 5 in each part except for the start end and the end.

  In the present embodiment, the starting end (tip) of the first screw thread 4 extends to the tip of the tapered portion 3, and the starting end of the first screw thread is the chopped portion 4 a. By the biting action of the chopping portion 4a, an opportunity for the shaft 1 to enter the member (work, base material) is created. The terminal portions of both the first screw thread 4 and the second screw thread 5 are gradually lowered in height, and the terminal ends of the second screw threads 5 are located at the back surface in FIG.

  Of the threaded portion in which the two threads 4 and 5 are formed, the portion excluding the tapered portion 3 is a large-diameter portion 6 located on the head 2 side and a small-diameter portion 7 located on the tip side. And the taper portion 8 that smoothly connects both the large diameter portion 6 and the small diameter portion 7. It has a straight shape with a constant outer diameter.

  That is, the valley diameter D1 of the large diameter portion 6 is substantially constant over the entire length of the large diameter portion 6, and the outer diameter D2 of the first thread 4 and the outer diameter D3 of the second thread 5 in the large diameter section 6 are Except for the terminal end, each is substantially constant over the entire length of the large-diameter portion 6. Similarly, the valley diameter D 4 of the small-diameter portion 7 is substantially constant over the entire length of the small-diameter portion 7. The outer diameter D5 of the mountain 4 and the outer diameter D6 of the second screw thread 5 are substantially constant over the entire length of the small diameter portion 7, respectively.

  The outer diameter difference (D2-D5) of the first thread 4 and the outer diameter difference (D3-D6) of the second thread 5 are substantially the same as the difference in valley diameter (D1-D4). In the present embodiment, the height of the first thread 4 is set to about twice the height of the second thread 5 in both the large-diameter portion 6 and the small-diameter portion 7, but the ratio of the height is arbitrary. Can be set. It is also possible to set the outer diameter D5 of the first screw thread 4 in the small diameter portion 7 to the same extent as the outer diameter D3 of the second screw thread 5 in the large diameter portion 6.

  Although the angle θ1 of the first thread 4 and the angle θ2 of the second thread 5 are different, the angles θ1 and θ2 may be equal to each other. In the present embodiment, θ1 is set to about 30 degrees and θ2 is set to about 60 degrees, but of course, the angle can be arbitrarily set as necessary.

  The head 2 has a trumpet shape having a profile that curves outwardly concavely, and a cross hole 9 is formed on the top surface as an example of an engaging portion into which a driver bit is fitted. A flange portion 2a is provided at the upper end. The outer diameter of the flange portion 2a is set to about three times the outer diameter D2 of the first thread 4 in the large diameter portion 6.

(2) Usage state Fig. 2 shows an example of the use of screws. In this example, the gypsum board 10 is used for fastening to a frame material (base material) 11 made of a thin steel plate and having a substantially C-shaped cross section, (A) is a cross-sectional view in a screwed state, (B ) Is a sectional view in the middle of screwing. A cover 12 is attached to the surface of the gypsum board 10 and a backing paper 13 is attached to the back.

  In screwing in the screw, the small diameter portion 7 first enters the frame material 11 from the gypsum board 10, and then the large diameter portion 6 enters the gypsum board 10 and the frame material 11. In the screwed state, the threads 4 and 5 of the large-diameter portion 6 are hooked on the inner peripheral edge of the frame member 12, and the flange portion 2b of the head portion 2 is in a state of being recessed into the gypsum board 10 (on the cover sheet 12). To put wallpaper.)

  The frame member 11 is formed with a burring-like bulging portion 11a protruding in the screwing direction by the screw entry, and the bulging portion 11a is caught by the flank (following flank) of the screw threads 4 and 5 to be screwed. Omission is prevented.

  In the present invention, since the small diameter portion 7 first enters the frame member 11, the screwing resistance from the initial stage to the middle stage of the screwing is small and the screwing can be smoothly performed. (Ie, the frame material 11 is pushed and spread), there is no backlash between the large diameter portion 6 and the frame material 11, and the threads 4 and 5 are formed in the bulging portion 11 a of the frame material 11. It can be hooked firmly, and thereby a high fastening strength can be ensured.

  As in this embodiment, when the flange portion 2a of the head 2 is set to about 3 times the maximum diameter (nominal diameter) D2 of the screw thread (the conventional product is about 2 times), the pressing force against the gypsum boat 2 is increased. Although it can be remarkably improved, since it is necessary to squeeze the flange portion 2a into the gypsum board 10, if the outer diameter of the flange portion 2a is larger than before, a high pulling resistance is required at the end of screwing. For this, the hooking resistance of the frame member 11 to the threads 4 and 5 must be large.

  In this regard, in the present invention, as described above, since the hooking resistance of the frame member 11 with respect to the threads 4 and 5 of the large-diameter portion 6 increases, the bulging portion 11a of the frame member 11 is crushed and the screw is idle. While avoiding the phenomenon that the screw becomes stupid, the entire head 2 can be embedded in the gypsum board 10.

  In addition, if the entire screw portion is straight, the gypsum board may collapse and play may occur between the screw portion. However, in the present invention, the large diameter portion 6 bites into the gypsum boat 10 as well. The thread portion can be brought into close contact with the tissue of the gypsum board 10.

  Needless to say, the screw of this embodiment can also be used to fasten the gypsum board 10 to a wooden frame member. In this case, the whole or most of the threaded portion remains in the frame material in many cases. However, since the screwing resistance as a whole is reduced by the presence of the small diameter portion 7, the burden on the operator during the fastening work is reduced. can do.

(3). Other Embodiments FIG. 3 shows another embodiment. Of these, in the second embodiment shown in (A), the portion of the screw portion excluding the tapered portion 3 is divided into two parts, a large diameter part 6 and a small diameter part 7, and the small diameter part 7. Is entirely tapered with a tapered shape. Therefore, in the small diameter portion 7, the root diameter and the outer diameters of both screw threads 4 and 5 are gradually reduced from the rear end toward the front end.

  In 3rd Embodiment shown to (B), the whole screw part which the taper part 3 contains is divided into the large diameter part 6 and the small diameter part 7, and an outer diameter becomes small gradually the small diameter part 7 over the full length. It is formed in a taper shape. In this case, the tapered portion is a part of the small diameter portion 7. The same effects as those of the first embodiment can also be obtained in the embodiment of FIG.

(4). Others The present invention can be embodied in various ways other than the above embodiment. For example, although not shown, as a modification of the first embodiment, the height (or outer diameter) of both screw threads 4 and 5 is set to be the same in the small diameter portion 7, and the tapered portion 8 and the large diameter portion 6. It is also possible to make the heights of both screw threads 4 and 5 different.

  It is also possible for the threaded portion to have three straight-shaped portions of a large-diameter portion, an intermediate-diameter portion, and a small-diameter portion, and the adjacent straight-shaped portions can be smoothly continuous with a taper. In addition, for example, the difference in height between the first thread and the second thread can be changed between the large diameter part and the small diameter part. Alternatively, the shaft is divided into three portions, a tapered portion, a first tapered portion continuous with the tapered portion, and a second tapered portion continuous with the first tapered portion, and the height of two threads It is also possible to make the difference between the first taper portion and the second taper portion.

  Furthermore, the form of the head can be selected according to the application. Specifically, a dish head, pan head, hexagon head, etc. can be employed. The form of the engaging portion is not limited to the cross hole, and when the engaging hole method is adopted, various shapes of engaging holes such as a square hole, a hexagonal hole, or a star-shaped hole can be adopted.

It is a figure which shows the structure of 1st Embodiment, (A) is a front view, (B) is a front view in the state which abbreviate | omitted the screw thread, (C) is a top view, (D) is a fragmentary sectional view. is there. It is sectional drawing which shows a use condition. It is a figure which shows 2nd-3rd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Axis 2 Head 3 Tapered part 4 1st thread 5 5 2nd thread 6 Large diameter part 7 Small diameter part 8 Tapered part 9 Cross hole as an example of engaging part 10 Gypsum board as an example of workpiece 11 Thin steel plate frame material (base material) as an example of the material

Claims (3)

A shaft having a circular cross section and a head provided at the base end thereof, and the tip of the shaft on the side opposite to the head is a tapered portion sharpened at the tip, A threaded self-drilling, in which a threaded portion having a plurality of threads starting from a tapered portion is formed, and an engaging portion into which a driver bit is fitted is formed in the head. A screw,
Of the threaded portion of the shaft, the portion excluding the tapered portion is divided into a plurality of portions that are adjacent in the axial direction, and the adjacent portion has a valley diameter of the portion located on the head side on the tip side. Is set to be larger than the root diameter of the portion located in the portion, and the height of the plurality of threads is different from each other in the portion located at least on the head side of each portion,
A chopped self-drilling screw. Of the threaded portion, the portion excluding the tapered portion is for smoothly connecting the large-diameter portion located on the head side, the small-diameter portion located on the tip side, and the large-diameter portion and the small-diameter portion. A taper portion, and two threads of the first screw thread and the second screw thread are formed at different heights in each part,
Furthermore, in the large diameter portion and the small diameter portion, the valley diameter and the outer diameter of both screw threads are substantially constant straight, respectively.
The chopped self-drilling screw according to claim 1. The head is formed in a trumpet shape having a curved profile that is curved in a longitudinal sectional view with the outer diameter gradually expanding toward the top surface, and a flange portion having an equal thickness on the outer peripheral edge. Formed, the outer periphery of the flange portion is set to a size larger than twice the maximum outer diameter of the screw portion,
A chopped self-drilling screw according to claim 1 or 2.

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