TW202111225A - Self-tapping screw for achieving the effects of preventing cracks and maintaining the anti-pulling ability - Google Patents

Abstract

A self-tapping screw includes a screw head, a screw rod extending from the screw head along an axis, a tapping unit extending spirally around the screw rod, and a fixing assistance unit. The tapping unit includes a plurality of cutting edges radially tapered and extended outward from the screw rod and continuously connected to each other. The fixing assistance unit includes a plurality of crest members which are spaced apart from each other, axially arranged on adjacent cutting edges, and radially tapered and extended outward; and a plurality of concave surfaces which are respectively adjacent to the crest members and recessed in the screw rod so as to define a plurality of mortise grooves radially recessed inward. By means of the crest members, the uncut part is correspondingly pushed away during the tapping process without causing severe shear changes and damages. After the crest members passes, the uncut part rebounds correspondingly and is mortised into the mortise groove, so as to achieve the effects of preventing cracks and maintaining the anti-pulling ability.

Description

Self-tapping screws

The present invention relates to a kind of workpiece, in particular to a self-tapping screw.

Referring to Fig. 1, a common self-tapping screw on the market includes a screw head 5, a screw 6 extending from the screw head 5 along an axis Y and a sharp end, and an axially spiraling screw around the screw 6 Extension tapping unit 7. The screw head 5 includes a screwdriver slot 51 suitable for detachably clamping a driving tool; the screw 6 includes a shaft member 61 extending axially, and a shaft member 61 away from the screw head 5 One end of the drill piece 62 is tapered and extended; the tapping unit 7 includes a plurality of cutting edges 71 that are continuously connected to each other and extend radially outward from the screw rod 6 to form a triangular cross-section.

2 and 3, in the current tapping operation, when the screw head 5 is clamped and driven by the driving tool to rotate around the axis Y, the screw 6 will be driven to rotate together, and a wood board W to be tapped It will be first drilled by the drill piece 62, and then entered by the cutting edges 71 one by one and spirally cut to form a threaded groove A corresponding to the tapping unit 7.

Although the self-tapping screw can indeed be cut by the tapping unit 7 and clamped to the corresponding screw groove A, and screwed to the wood board W to be tapped. However, in actual operation, it is found that the top edge of the cutting edge 71 and the shaft member 61 have a large radial height difference. The wood board W to be tapped is often subjected to severe shear changes during cutting, as shown in FIG. 2 The indication rupture results in the reduction of the structural strength of the screw groove A and the decrease of the screw connection strength. What's more, it may also cause the chipping and damage of the wood board W to be tapped, and the screw connection operation cannot be performed.

In view of the above-mentioned problems, if in order to prevent the wood board W to be tapped from cracking, a self-tapping screw with a smaller radial height difference between the top edges of the cutting edges 71 is selected, and the depth of the threaded groove A will be reduced. The same will cause the strength of the screw connection to decrease. In addition, because the strength of the engagement between the tapping unit 7 and the threaded groove A is insufficient, when the screw head 5 is subjected to an axial pulling force, the tapping unit 7 will be directly separated from the threaded groove A in the axial direction. , Which is the shortcoming of the so-called insufficient pull-out resistance in the related industry.

Therefore, the purpose of the present invention is to provide a self-tapping screw that maintains good pull-out resistance and does not cause damage to the object to be tapped.

Therefore, the self-tapping screw of the present invention includes a screw head, a screw rod extending from the screw head along an axis, a tapping unit extending spirally around the screw shaft in the axial direction, and a cooperating screw provided on the screw head.固unit.

The screw head includes a body defining a screwdriver slot suitable for detachably clamping a driving tool.

The screw includes a shaft member extending from the screw head along the axis, and a drill bit member extending from one end of the shaft member away from the screw head.

The tapping unit includes a plurality of cutting edges extending radially outward from the screw rod and continuously connected to each other.

The cohesive unit includes a plurality of tooth tips which are arranged at adjacent cutting edges in an axial direction at intervals and extend radially outward, and a plurality of tooth tips are respectively adjacent to the tooth tips and recessed in the The screw defines a plurality of concave surfaces of the tenon grooves recessed radially inward.

The effect of the present invention is that by the cutting edges spaced apart between the cutting edges, and the concave surfaces adjacent to the cutting edges, each cutting edge enters and spirally cuts the cutting edge. When attacking an object, the adjacent but uncut part will be further pushed away by the adjacent and similar radial height of the front part, and will not be caused by the radial height difference between the front part and the shaft part. Damaged by severe shear changes. After the tooth tip passes through, the adjacent but uncut part will also rebound homeopathically and be inserted into the mortise groove to be mortise joint, so as to prevent unpredictable cracks and maintain good pull-out resistance.

Referring to Figures 4 to 6, an embodiment of the self-tapping screw of the present invention includes a screw head 1, a screw rod extending from the screw head 1 along an axis C 2, an axially surrounding the screw rod 2 in a spirally extending shape The tapping unit 3, and a co-fixing unit 4 arranged on the screw 2.

The screw head 1 includes a body 12 defining a screwdriver slot 11 suitable for detachably clamping a driving tool. Although the screwdriver slot 11 depicted in FIG. 1 is suitable for a hexagonal screwdriver, in fact the screwdriver slot 11 can be changed according to common driving tools on the market, such as a character, a cross, or a rice character, etc., as long as it can provide The screwdriver is clamped and driven to rotate around the axis C, which can improve the applicability and achieve its function.

The screw 2 includes a shaft member 21 extending from the screw head 1 along the axis C, and a drill member 22 extending from one end of the shaft member 21 away from the screw head 1.

The tapping unit 3 includes a plurality of cutting edges 31 that extend radially outward from the screw 2 and are continuously connected to each other. In practice, the tapping unit 3 is a well-known thread. For the convenience of description, the cutting edges 31 are distinguished by a reference line R located on one side of the screw 2 and parallel to the axis C, that is, Each cutting edge 31 described below means that it passes through the reference line R and surrounds the screw 2 once. In addition, in order to provide the configuration of the co-fixing unit 4 which will be described next, the spacing distance between each cutting edge 31 is preferably a wide spacing.

Referring to Figures 5-7, the co-fixing unit 4 includes a plurality of tooth tips 41 which are spaced apart from each other and axially arranged on the adjacent cutting edges 31 and extend radially outwardly, and a plurality of tooth tips 41 respectively adjacent to the The tooth blade 41 is recessed in the screw 2 to define a plurality of concave surfaces 43 of the tenon groove 42 recessed radially inward. Wherein, each tooth element 41 is a tetrahedron that tapers and extends from a side adjacent to the drill bit 22 to a side adjacent to the screw head 1, and has a top edge extending radially to the axis C and in line with The sinking area 411 connected to the concave surface 43, a pushing-up area 412 located on the other side of the sinking area 411 and suitable for pushing against an object I to be attacked, and two are respectively integrally connected to the shaft member 21 and the adjacent cutting The connecting area 413 of the blade 31. To be precise, the radial distance D1 between the top edge of each tooth 41 and the shaft 21 is 50 of the radial distance D2 between the top edge of each cutting edge 31 and the shaft 21. % To 70%, preferably 50%. The radial distance D3 between the bottom edge of each mortise groove 42 and the shaft member 21 is 30% to 30% of the radial distance D1 between the top edge of each tooth front member 41 and the shaft member 21 50%.

Referring to Figures 6 and 7, in conjunction with Figures 2 and 3, the actual situation of using this embodiment to tap the object to be tapped I will be described below. The user clamps the screwdriver in the screwdriver slot 11 and surrounds it. When the axis C rotates in a clockwise direction, the tapping unit 3 and the co-fixing unit 4 and the drill bit 22 on the shaft member 21 will rotate together. The object I to be tapped will first be drilled with a small hole by the drill piece 22, and tapped by the cutting edge 31 at the front end to form a screw socket S. The object I to be tapped is adjacent to the screw socket S but not The tapped part (defined as the tenon part T hereinafter) will be further pushed away by the push-up area 412 of the tooth front 41 that is adjacent and has a similar radial height as shown in FIG. The radial height difference between the tooth front member 41 and the shaft member 21 is damaged due to the severe change in the shear force generated between the screw socket S and the tenon part T. After the settlement area 411 passes, the tenon joint T will also rebound and fit into the tenon groove 42.

As the cutting edges 31, the tooth elements 41 and the concave surfaces 43 enter one by one and continue to spirally cut, the thread groove S will spirally extend and form a screw hole, and the tenon part T will be cut due to the cutting The radial distance between the edge 31 and the tines 41 is smaller than the radial distance between the cutting edge 31 and the shaft member 21, and will not produce drastic changes in the shearing force during the cutting process, thereby avoiding such Figure 2 shows the cracks caused by changes in shear. It is also because the teeth 41 are spaced apart from each other instead of completely covering the shaft 21, and the thickness of each of the teeth 41 does not increase the diameter of the shaft 21, resulting in the result shown in FIG. 2 It shows that the radial distance of each cutting edge 71 is small, which reduces the pull-out resistance.

Referring to Figure 8, regarding the pull-out resistance, according to the state of the embodiment being pulled by an external force, it can be classified as being screwed out in a counterclockwise direction around the axis C, or directly out of the screw socket S along the axis C. . When the embodiment is pulled out by a slower force, the embodiment will tend to be screwed out counterclockwise along the thread socket S around the axis C, and the tongue-and-groove portions T will respectively settle relative to the The area 411 generates a reverse pushing force F, thereby preventing the embodiment from rotating out the object I to be attacked in a counterclockwise direction as shown in FIG. 8, thereby improving the pull-out resistance of the embodiment.

On the other hand, the mortise groove 42 formed by the concave surfaces 43, when the embodiment is pulled out of the thread groove S in the axial direction, it springs back and engages in the mortise groove 42 of the mortise groove 42 T will produce a tenoning effect with respect to the concave surface 43, further strengthen the pushing force with respect to the concave surface 43, and also improve the pull-out resistance of this embodiment.

Finally, the above description of the application status of clockwise screwing in and counterclockwise screwing out is for the convenience of readers to understand, so the main screw design is explained. However, it should be emphasized that this embodiment can also be used for counterclockwise screwing in and clockwise screwing out of counter-thread screws for different purposes on the market to perform the transposition of the tapping unit 3 in the spiral direction, and the threading element 41 The opposite arrangement of the settling zone 411 and the pushing up zone 412, and changing the corresponding positions of the concave surfaces 43 can achieve the same effect.

To sum up, the self-tapping screw of the present invention reduces the radial distance between the cutting edges 31 and the shaft member 21 by using the tooth blades 41 during the tapping process, thereby reducing severe shearing. The cracks caused by the force change; and cooperate with the tenon joints T to generate the thrust force F to prevent the embodiment from being unscrewed with respect to the settlement areas 411 respectively; and then the tenon grooves formed by the concave surfaces 43 42. Cooperating with the mortise parts T to form a mortise function that resists axial separation from the screw alveolar S, which improves the pull-out resistance of this embodiment, so it can indeed achieve the purpose of the invention.

However, the above are only examples of the present invention. When the scope of implementation of the present invention cannot be limited by this, all simple equivalent changes and modifications made in accordance with the scope of the patent application of the present invention and the content of the patent specification still belong to This invention patent covers the scope.

C: axis R: reference line I: Object to be attacked S: Thread socket T: Tenon joint F: Pushing force D1: distance D2: distance D3: distance 1: Screw head 11: Screwdriver slot 12: body 2: screw 21: Shaft 22: Drill bits 3: Tapping unit 31: cutting edge 4: Associated solid unit 41: Teeth 411: Settlement Zone 412: Push Up Zone 413: connection area 42: Tenon groove 43: concave 71: cutting edge

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, in which: Figure 1 is a perspective view illustrating one of the existing self-tapping screws; Figure 2 is a schematic diagram illustrating the cracks generated during the tapping process of the self-tapping screw; Figure 3 is a schematic diagram illustrating that the self-tapping screw has insufficient pull-out resistance; Figure 4 is a perspective view illustrating an embodiment of the self-tapping screw of the present invention; Figure 5 is a schematic diagram illustrating the actual application of this embodiment; Figure 6 is a schematic diagram illustrating the actual application of this embodiment; Figure 7 is a schematic diagram illustrating the actual application of the embodiment from another perspective; and Fig. 8 is a schematic diagram illustrating the anti-pull mechanism of this embodiment.

1: Screw head

11: Screwdriver slot

12: body

2: screw

21: Shaft

22: Drill bits

3: Tapping unit

31: cutting edge

4: Associated solid unit

41: Teeth

Claims (6)

A self-tapping screw, including: A screw head, including a body defining a screwdriver slot suitable for detachably clamping a driving tool; A screw, including a shaft member extending from the screw head along an axis, and a drill bit member extending from an end of the shaft member away from the screw head; A tapping unit, which axially surrounds the screw and extends in a spiral shape, and includes a plurality of cutting edges that extend radially outward from the screw and are continuously connected to each other; and A cohesive unit includes a plurality of tooth blades which are axially arranged between adjacent cutting edges at intervals and extend radially outwardly, and a plurality of tooth blades respectively adjacent to the tooth blades and recessed in the The screw defines a plurality of concave surfaces of the tenon grooves recessed radially inward. The self-tapping screw according to claim 1, wherein the radial distance between the top edge of each tooth edge and the shaft member is the radial distance between the top edge of each cutting edge and the shaft member 50% to 70% of the size. The self-tapping screw according to claim 1, wherein the radial distance between the bottom edge of each mortise groove and the shaft member is the radial distance between the top edge of each tooth and the shaft member 30% to 50% of the distance. The self-tapping screw according to claim 1, wherein each of the threaded elements has a settlement area connected to the concave surface and a pushing area located on the other side of the settlement area and suitable for pushing against an object to be tapped. The self-tapping screw according to claim 4, wherein the settlement area extends radially toward the axis. The self-tapping screw according to claim 1, wherein each of the tooth elements of the co-fixing unit is a tetrahedron that tapers and extends from a side adjacent to the drill bit to a side adjacent to the screw head.

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