TW202130922A - A self-tapping screw - Google Patents

Abstract

A self-tapping screw is provided to overcome the problem of the conventional self-tapping screw deviating from the center and generating high temperature when drilling. The self-tapping screw includes a rod, a cap and a tapping part. The rod has a predetermined length and at least one screw teeth part helically formed on and extended along the rod from the first end to the second end of the rod. The cap is located at the second end of the rod. The tapping part is located at the first end of the rod and includes a tip and two cutting edges. Each of the two cutting edges has a spiral groove and a back. The cutting edge has a start end. A first spacing forms between the start end and the tip. A second spacing forms between the end of the back and the start end.

Description

Self-tapping screws

The invention relates to a self-tapping screw, in particular to a tapping part design of a self-tapping screw.

Please refer to Figure 1, which is a conventional self-tapping screw 9. The conventional self-tapping screw 9 has a nut 91, a screw 92, and a drill bit 93. A threaded portion 94 spirally surrounds the screw 92. The outer surface extends to the tip of the drill bit 93.

Before drilling and locking, the above-mentioned conventional self-tapping screw 9 will first contact the object to be locked with the drill bit 93, and generate an initial drilling hole on the outer surface of the object to be locked, and position the screw on the object to be locked for subsequent follow-up Tap drill. However, the conventional self-tapping screw 9 only relies on the tip of the drill bit 93 to dig on the surface of the locked object. Because the tip of the drill bit 93 lacks the shoveling ability to damage the surface of the locked object, the digging is not easy to drill. The enlargement will not only prevent the conventional self-tapping screw 9 from being positioned or cause offset, but also greatly increase the time required for tapping. The constant drilling position also makes the conventional self-tapping screw 9 in The process of drilling and locking is easy to generate high temperature. Therefore, the worker will first drill a hole or screw hole on the object to be locked with a drill bit, and then drill and lock the conventional self-tapping screw 9 into the preset hole or screw hole. Such steps make the work of the drill lock cumbersome and more time-consuming.

In view of this, the conventional self-tapping screws do still need to be improved.

In order to solve the above-mentioned problems, the purpose of the present invention is to provide a self-tapping screw, which can expand the borehole to avoid the center shift.

The second objective of the present invention is to provide a self-tapping screw, which can continuously change the contact point with the object to be locked, so as to avoid high temperature during drilling and locking.

Another object of the present invention is to provide a self-tapping screw, which can be tapped and positioned in the locked object by the structure of the screw itself, so as to simplify the worker's operating procedures.

The directionality described in the full text of the present invention or its similar terms, such as "front", "rear", "left", "right", "up (top)", "down (bottom)", "inner", "outer" , "Side", etc., mainly refer to the directions of the attached drawings, and the terms of directionality or similar terms are only used to assist in the description and understanding of the embodiments of the present invention, and are not intended to limit the present invention.

The elements and components described in the full text of the present invention use the quantifiers "one" or "one" for convenience and to provide the general meaning of the scope of the present invention; in the present invention, it should be construed as including one or at least one, and single The concept of also includes the plural, unless it clearly implies other meanings.

Approximate terms such as "combination", "combination" or "assembly" mentioned in the full text of the present invention mainly include the types that can be separated without destroying the components after being connected, or the components cannot be separated after being connected, which are common knowledge in the field Those can be selected based on the materials of the components to be connected or assembly requirements.

The self-tapping screw of the present invention includes: a rod body with a predetermined length, the rod body is provided with at least one thread part, the thread part starts from the first end of the rod body to the second end Spirally surrounding; a hat head located at the second end of the rod body; and a tapping portion located at the first end of the rod body, the tapping portion has a tip and two cutting edges, the tip has a taper angle, Each of the cutting edges has a spiral groove and a back. The cutting edge has a starting end. There is a first distance between the starting end and the tip. There is a gap between an end of the back and the starting end of the cutting edge. The second distance.

Accordingly, during the tapping process of the self-tapping screw of the present invention, the tapping part can continuously change the contact point between the cutting edge and the object to be locked by the rotation of the screw, so as to avoid continuous tapping with the object to be locked. The high temperature is generated by contact and friction. The spiral groove is used to guide the debris generated during the tapping process. The back part is kept at a certain distance from the object to be locked during the tapping process to reduce the friction with the object to be locked. It can improve the efficiency of screw tapping, reduce the temperature and friction of the drill lock, expand the drill hole to reduce the worker's working time, simplify the operation procedure before the drill lock, avoid the deviation of the screw and maintain the locking strength of the screw, etc. effect.

Among them, the cone angle is between 30 and 60 degrees. In this way, it has the effect of facilitating the worker to tap and drill the locked object.

Wherein, the first distance is between 1.0 and 2.0 mm. In this way, it is avoided that the initial screw hole is too large due to the premature start of cutting, which reduces the locking strength of the screw, and has the effect of maintaining the locking strength of the screw.

Wherein, the second distance is between 0.5 and 1.5 mm. In this way, the debris generated during the tapping and drilling process is gathered into the spiral groove, which has the effect of reducing the friction with the object to be locked and improving the tapping and drilling efficiency.

Wherein, there are a plurality of chip flutes between the threads of the thread part, the cutting edge has a tail end, and the tail end is communicated with the chip flute of the rod body. In this way, the debris generated during the tapping process can be introduced into the chip flute, so that the debris can be discharged along the chip flute toward the direction of the cap, which has the advantage of avoiding debris accumulation and lifting the tapping drill. Effectiveness of efficiency.

Wherein, the rod body has an axial centerline, and there is an inclination angle between the cutting edge and the axial centerline. In this way, during the tapping process of the self-tapping screw, the cutting edge can gradually come into contact with the object to be locked, so as to prevent the cutting edge from contacting the object to be locked in a large area at the same time. The body structure and the effect of reducing screw damage.

Among them, the inclination angle is between 0.3 and 5 degrees. In this way, it has the effect of improving the structural strength of the screw and dispersing the stress of the drill lock.

Wherein, there is an inflection point between the spiral groove and the back, and the spiral groove is bent from the inflection point to form a concave arc and extends toward the cutting edge. In this way, the spiral groove system can collect the debris generated by tapping and guide it toward the rod body, which has the effect of avoiding accumulation of debris.

Wherein, there is an inflection point between the spiral groove and the back part, the back part has a decreasing curvature from the inflection point toward the cutting edge, and the back part has a clearance angle from the cutting edge. In this way, the contact area between the penetration portion and the object to be locked is reduced, so that the back can pass through quickly during drilling and locking, which has the effect of reducing friction with the object to be locked and avoiding rapid temperature rise during the drilling and locking process.

Among them, the clearance angle is between 2 and 10 degrees. In this way, the system has the effect of increasing the tapping speed of the screw.

In order to make the above and other objectives, features and advantages of the present invention more comprehensible, the following describes the preferred embodiments of the present invention in conjunction with the accompanying drawings in detail as follows:

Please refer to Figure 2, which is a preferred embodiment of the self-tapping screw of the present invention, which includes a shaft 1, a cap head 2 and a tapping portion 3, the tapping portion 3 is located on the shaft 1 The cap head 2 is located at the second end of the rod body 1.

The rod body 1 has a predetermined length and has an axial centerline X. The rod body 1 has at least one thread portion, and the thread portion starts from the first end of the rod body 1 toward the second In this embodiment, the rod body 1 has a first thread portion 11 and a second thread portion 12, and the first thread portion 11 is formed by the first end of the rod body 1. Starting to spiral around the second end, the second thread portion 12 is connected to the tail end of the first thread portion 11, and continues to spirally loop toward the second end, so that the first thread portion 11 and the The second thread portion 12 is continuously wound around and protrudes on the outer surface of the rod body 1. Preferably, there may be a plurality of chip flutes 13 between each of the first screw thread portions 11, and the chip flutes 13 are surrounded in a continuous spiral and recessed on the outer surface of the rod body 1. , In order to discharge the debris generated in the process of tapping and drilling toward the direction of the cap head 2.

The cap head 2 is located at the second end of the rod body 1, and the cap head 2 is used for the user to rotate the self-tapping screw. The cap head 2 can have various conventional structures and shapes, and the present invention is not limited. In this embodiment, the cap head 2 is illustrated by taking a circular shape as an example. The cap head 2 has a surface 2a and a connecting surface 2b. The surface 2a may have a conventional inline groove or a cross groove. The connecting surface 2 b is connected to the rod body 1, and the connecting surface 2 b is generally arc-shaped and has a decreasing diameter toward the rod body 1. Preferably, the hat head 2 may also have a plurality of ribs 21 located on the connecting surface 2b, and each of the ribs 21 extends from the surface 2a toward the connecting surface 2b, which has the effect of enhancing the strength of the overall structure. .

Please refer to Figure 3, the tapping part 3 is used to expand the hole, so that the self-tapping screw can be positioned on the outer surface of the object to be locked, so as to improve the tapping efficiency of the tapping part 3 and avoid screw skew . The tapping portion 3 has a tip P. The tip P is the part of the self-tapping screw that first contacts the object to be locked. The tip P can generate an initial drilling hole on the surface of the object to be locked to position the screw on the object to be locked. On the lock object to facilitate subsequent tapping, the tip P has a taper angle θ1, and the taper angle θ1 is between 30 and 60 degrees to facilitate the worker's tapping and drilling operations on the locked object. The tapping portion 3 has two cutting edges 31. The cutting edges 31 are used to destroy the internal structure of the object to be locked and can be of any shape, which is not limited by the present invention. In this embodiment, the cutting edge 31 is illustrated by taking a convex arc shape as an example. The cutting edge 31 has a starting end 31a and a trailing end 31b. The starting end 31a is closer to the tip P than the trailing end 31b. There is a first distance L1 between the starting end 31a and the tip P, so as to prevent the starting screw hole from being too large due to the premature start of cutting, thereby reducing the locking strength of the screw. The grooves 13 communicate with each other, so that the debris in the spiral groove 32 is guided into the chip discharge groove 13 so that the chips can be discharged along the chip discharge groove 13 toward the direction of the cap head 2. Preferably, the first distance L1 is between 1.0 and 2.0 mm.

Each of the cutting edges 31 has a spiral groove 32 and a back 33, so that the cutting edge 31 cuts and breaks the object to be locked, and the spiral groove 32 moves the chips generated by tapping towards the direction of the rod body 1. Guide to avoid the accumulation of debris and affect the tapping efficiency of the tapping portion 3. There is a second distance L2 between an end point E of the back 33 and the starting end 31a of the cutting edge 31, so that the tapping process The generated debris is collected in the spiral groove 32 to improve the efficiency of screw tapping and reduce the friction of the drill lock. Preferably, the second distance L2 is between 0.5 and 1.5 mm.

Please refer to Fig. 4, there is an inclination angle θ2 between the cutting edge 31 and the axial centerline X to prevent the cutting edge 31 and the axial centerline X from being flat, causing the self-tapping screw to suffer The stress is concentrated, causing the screw to be damaged or broken during the tapping and drilling process. Preferably, the inclination angle θ2 is between 0.3 and 5 degrees to disperse the stress applied to the screw during tapping.

Please refer to FIG. 5, the penetration portion 3 is formed by the two cutting edges 31 and two continuous curves C, each of which is connected to the cutting edge 31, the spiral groove 32 and the back 33, the intersection of the spiral groove 32 and the back 33 has an inflection point R. The spiral groove 32 is bent at the inflection point R to form a concave arc and extends toward the cutting edge 31 to form A space is used to accommodate chips generated by tapping. The back 33 has a decreasing curvature from the inflection point R toward the cutting edge 31. The back 33 has a clearance angle θ3 from the cutting edge 31. The clearance angle θ3 can reduce the contact area between the tapping part 3 and the object to be locked, allowing the back 33 to pass quickly when drilling and locking, which can increase the tapping speed of the screw, reduce the friction with the object to be locked, and avoid drilling. The temperature rises rapidly during the locking process. Preferably, the clearance angle θ3 is between 2 and 10 degrees to increase the tapping speed of the screw.

According to the aforementioned structure, when the self-tapping screw of the present invention is actually used, the tip P can be used to form an initial hole on the outer surface of the object to be locked, and the self-tapping screw can be screwed into the object along a rotation direction T. In the lock, in the process of tapping and drilling, the cutting edge 31 can shovel the locked object and destroy the internal structure of the locked object, so as to expand the hole so that the self-tapping screw can be locked in more easily. The spiral groove 32 and the back 33 guide the debris generated during the tapping process to the chip flute 13 of the rod body 1, and lead out along the chip flute 13 toward the cap head 2 to avoid accumulation of debris and Increase the tapping efficiency of self-tapping screws.

In summary, during the tapping process of the self-tapping screw of the present invention, the tapping part can continuously change the contact point between the cutting edge and the object to be locked by the rotation of the screw, so as to avoid being locked during tapping and drilling. The spiral groove is used to lead out the debris generated during the tapping and drilling process. The back part is kept at a certain distance from the locked object during the tapping and drilling process to reduce the distance between the locked object and the locked object. Friction, which improves the efficiency of screw tapping, reduces the temperature and friction of the drill lock, expands the drill hole to reduce the worker's working time, simplifies the operation procedure before the drill lock, avoids the deviation of the screw and maintains the screw lock Strength and other effects.

Although the present invention has been disclosed using the above-mentioned preferred embodiments, it is not intended to limit the present invention. Anyone who is familiar with the art without departing from the spirit and scope of the present invention may make various changes and modifications relative to the above-mentioned embodiments. The technical scope of the invention is protected. Therefore, the scope of protection of the invention shall be subject to the scope of the attached patent application.

﹝this invention﹞ 1: Rod body 11: The first thread part 12: The second thread part 13: Chip flute 2: hat head 2a: surface 2b: Connection surface 21: Ribs 3: Invasion 31: cutting edge 31a: starting end 31b: end 32: spiral groove 33: back E: Endpoint C: continuous curve L1: The first spacing- L2: second spacing P: Tip R: Recurve point T: rotation direction X: axial centerline θ1: Cone angle θ2: Tilt angle θ3: Clearance angle ﹝Used ﹞ 9: Known self-tapping screws 91: Nut 92: screw 93: Drill 94: Threaded part

[Picture 1] A conventional self-tapping screw diagram. [Figure 2] A perspective view of a preferred embodiment of the present invention. [Figure 3] A front view of a preferred embodiment of the present invention. [Figure 4] A top view of a preferred embodiment of the present invention. [Picture 5] A cross-sectional view along the line A-A in Fig. 3.

1: Rod body

11: The first thread part

12: The second thread part

13: Chip flute

2: hat head

2a: surface

2b: Connection surface

21: Ribs

3: Invasion

31: cutting edge

32: spiral groove

33: back

P: Tip

Claims (10)

A self-tapping screw, including: A rod body having a predetermined length, the rod body is provided with at least one threaded portion, and the threaded portion starts from the first end of the rod body and spirally surrounds the second end; A hat head located at the second end of the rod; and A tapping portion is located at the first end of the rod body. The tapping portion has a tip and two cutting edges. The tip has a taper angle. Each of the cutting edges has a spiral groove and a back. The cutting edge has A starting end, a first distance between the starting end and the tip, and a second distance between an end of the back and the starting end of the cutting edge. Such as the self-tapping screw of claim 1, wherein the taper angle is between 30 and 60 degrees. For example, the self-tapping screw of claim 1, wherein the first pitch is between 1.0 and 2.0 mm. Such as the self-tapping screw of claim 1, wherein the second pitch is between 0.5 and 1.5 mm. For example, the self-tapping screw of claim 1, wherein a plurality of chip flutes are formed between the threads of the thread part, the cutting edge has a tail end, and the tail end communicates with the chip flute of the rod body. Such as the self-tapping screw of claim 1, wherein the rod body has an axial centerline, and there is an inclination angle between the cutting edge and the axial centerline. Such as the self-tapping screw of claim 6, wherein the inclination angle is between 0.3 and 5 degrees. For example, the self-tapping screw of claim 1, wherein there is an inflection point between the spiral groove and the back, and the spiral groove is bent from the inflection point to form a concave arc and extends toward the cutting edge. For example, the self-tapping screw of claim 1, wherein there is an inflection point between the spiral groove and the back, and the back has a decreasing curvature from the inflection point toward the cutting edge, and the back has a surplus from the cutting edge Gap angle. Such as the self-tapping screw of claim 9, wherein the clearance angle is between 2 and 10 degrees.

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