Structure of low-resistance crack prevention screw

Abstract

To provide a structure of a low-resistance crack prevention screw having higher structural strength and better cutting efficiency.SOLUTION: A structure of a low-resistance crack prevention screw includes a low-resistance screw. The low-resistance screw is divided from top to bottom into an upper screw body, a middle screw body, a lower screw body, and a tapered tip. In the lower screw body, at least one milling groove is formed into a concave shape. The milling groove gradually deepens from top to bottom, and the milling groove is inclined relative to a central axis of the low-resistance screw at a milling pitch angle, where the milling pitch angle is between 10 and 20 degrees. The milling groove is inclined relative to a radial direction at an inclination gradient angle, where the inclination gradient angle is between 79 and 89 degrees. The maximum depth of a second groove part is less than 55% of a radius of the lower screw body. The lower side of the milling groove gradually narrows to form a resistance reduction angle, where the resistance reduction angle is between 15 and 20 degrees. On the surfaces of the lower screw body and a screw tip, a spiral lower thread is formed.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a structure of a low resistance crack prevention screw, and in particular to a structure of a low resistance crack prevention screw that has higher strength and better cutting efficiency. [Background technology]

[0002] Until now, thread-cutting screws are screws used for tapping, and the tip of the screw is subjected to a thread-cutting process to remove material during tapping. This is widely used on pre-drilled workpieces. However, the thread-cutting process actually harms the screw itself, resulting in a decrease in the strength of the screw and a poor thread yield rate. Furthermore, because traditional thread-cutting screws have a groove at the tip, they often damage the taper point or the taper tail cannot be used directly, further reducing their tapping effectiveness.

[0003] When conventional thread-cutting screws cut grooves at the tip, they often scrape off the threads directly, which is practically damaging to the thread structure, significantly reducing the strength of the structure, making it difficult to manufacture and use, and may even cause the thread to break. Furthermore, when the chips enter the groove, there may be problems with uneven scraping speed and force, and the resistance may also affect the function of the thread lock.

[0004] Therefore, there is a strong need to maintain the strength of the screw structure while improving the chip removal efficiency and eliminating the influence of resistance, with the premise of being advantageous in manufacturing and use.

[0005] Therefore, the present inventors have taken this into consideration and conceived the concept of the invention, designed it based on their many years of experience, and completed the present invention after much discussion, prototype testing of samples, and several modifications and improvements. Summary of the Invention [Problem to be solved by the invention]

[0006] The technical problem to be solved by the present invention is to provide a low resistance crack prevention screw structure in response to the above-mentioned drawbacks existing in the prior art. [Means for solving the problem]

[0007] Technical points to solve the problem The present invention provides a structure of a low resistance crack prevention screw, which includes a low resistance screw, the low resistance screw being divided from top to bottom into an upper thread body, a middle thread body, a lower thread body, and a tapered tip, wherein the lower thread body is recessed with at least one cutting groove, the cutting groove gradually deepening from top to bottom, and the cutting groove is inclined with respect to the central axis of the low resistance screw at a cutting pitch angle, the cutting pitch angle being between 10 degrees and 20 degrees, the cutting groove being divided into a flat first groove portion and an oblique second groove portion, the second groove portion being inclined with respect to the radial direction at an oblique gradient angle, the oblique gradient angle being between 79 degrees and 89 degrees, and the maximum depth of the second groove portion is The groove is smaller than 55% of the radius of the lower thread body, and as the lower side of the milling groove approaches the space between the two sides of the thread tip, it gradually shrinks to form a resistance reduction angle, which is between 15 and 20 degrees. This prevents the chips from entering the milling groove and then leaving it, preventing unnecessary packing and shrinkage that would increase resistance, thereby improving the complete penetration effect when screwing in. A spiral lower thread is provided on the surface of the lower thread body and the thread tip, and the lower thread and the milling groove are inclined in the same direction relative to the central axis of the low resistance screw, and the lower thread is continuously formed, and the milling groove is separated by the lower thread.

[0008] Additionally, the angle of the lower thread is between 37 and 43 degrees.

[0009] Furthermore, a helical upper thread is provided on the surface of the upper screw body, and the helical direction of the upper thread is opposite to the helical direction of the lower thread.

[0010] Here, the cutting pitch angle is preferably 15 degrees.

[0011] Here, the inclination angle is preferably 84 degrees.

[0012] Here, the drag reduction angle is preferably 18 degrees.

[0013] In accordance with the first main objective of the present invention, the tip of the low resistance screw is first used to butt against the workpiece to be screwed, and then the low resistance screw is turned to screw in. The lower thread is then planed to drill a hole and achieve a tapping effect, so that the low resistance screw can be screwed into the workpiece. The lower thread body is recessed with at least one cutting groove, and extra space is maintained, so that chips generated after the lower thread is planed can enter and exit through the cutting groove, improving the speed and efficiency of chip discharge out of the drill hole, and preventing chip accumulation that reduces tapping efficiency, and preventing chip accumulation that collides with the low resistance screw, causing distortion and reducing the quality of screwing. Furthermore, the lower thread is continuously shaped, and the cutting grooves are separated by the lower thread, so that chips do not follow the spiral direction and are discharged, preventing clogging.

[0014] In the second main object of the present invention, the grooves to be machined are not located at the tip of the screw, but are recessed into the lower screw body, and therefore do not harm the structure of the tip of the screw, resulting in a stronger structure and preventing the tip from breaking during manufacturing, and preventing the tip from breaking into the drilled hole when the low resistance screw is subsequently unscrewed and removed from the drilled hole. The grooves to be machined are gradually deeper from top to bottom, so that the grooves become deeper the closer to the bottom of the low resistance screw, allowing the low resistance screw to withstand greater resistance encountered at its tip when tapping, and providing better resistance. Since the maximum depth of the second groove portion is less than 55% of the radius of the lower thread body, the cutting efficiency is maintained while ensuring the structural strength of the lower thread body, preventing it from breaking during processing, manufacturing, or use. Furthermore, the cutting groove is inclined at the cutting pitch angle relative to the central axis of the low resistance thread, and the lower thread and the cutting groove are inclined in the same direction relative to the central axis of the low resistance thread, allowing the chips to enter the cutting groove smoothly, further improving the cutting efficiency.

[0015] In accordance with the third main object of the present invention, as the bottom of the cutting groove approaches the space between the two sides of the screw tip, it gradually shrinks to form the resistance reduction angle. Therefore, when the low resistance screw is first tapped into the workpiece, the bottom of the cutting groove is narrower, which prevents the initial chips of the low resistance screw from getting stuck in the cutting groove and shrinking, thereby preventing the low resistance screw from shaking due to excessive resistance when first turned in, thereby reducing the resistance and improving the complete penetration effect of the low resistance screw.

[0016] Other objects, advantages, and novel features of the present invention will become more apparent from the following detailed description and the associated drawings. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a three-dimensional view of the present invention. [Figure 2] FIG. 1 is a front view of the present invention, with the screw tip portion shown in cross section for better understanding. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA of FIG. 2 of the present invention. [Figure 4] FIG. 3 is a cross-sectional view taken along line BB of FIG. 2 of the present invention. [Figure 5] FIG. 3 is a cross-sectional view taken along CC in FIG. 2 of the present invention. [Figure 6] FIG. 2 is a front view of the lower screw body and screw tip portion of the present invention. [Figure 7] FIG. 7 is a cross-sectional view taken along line D-D of FIG. 6 of the present invention. [Figure 8] FIG. 2 is a partially enlarged view of the lower screw body and screw tip of the present invention. [Figure 9] 1 is a schematic diagram of the milled groove depth of the present invention, with the thread portion omitted for better understanding; FIG. [Figure 10] FIG. 1 is a schematic diagram of the screwing of the present invention. [Figure 11] FIG. 2 is a schematic diagram of the drag reduction angle of the present invention. [Figure 12] 1 is a schematic diagram of a state in which the present invention is used; [Figure 13] 10 is a schematic diagram showing chip removal from the lower screw body when the present invention is actually used. [Figure 14] 1 is a schematic view of a first embodiment of an internal screw body of the present invention. FIG. [Figure 15] FIG. 2 is a schematic view of a second embodiment of the internal screw body of the present invention. [Figure 16] FIG. 10 is a schematic view of a third embodiment of the internal screw body of the present invention. [Figure 17] FIG. 10 is a schematic view of a fourth embodiment of the internal screw body of the present invention. [Figure 18] FIG. 10 is a schematic view of a fifth embodiment of the internal screw body of the present invention. [Figure 19] FIG. 10 is a schematic view of a sixth embodiment of the internal screw body of the present invention. [Figure 20]FIG. 1 is a schematic view of a first embodiment of an upper screw body of the present invention. [Figure 21] FIG. 1 is a schematic view of a second embodiment of the upper screw body of the present invention. [Figure 22] FIG. 10 is a schematic view of a third embodiment of the upper screw body of the present invention. [Figure 23] FIG. 10 is a schematic view of a fourth embodiment of the upper screw body of the present invention. [Figure 24] FIG. 10 is a schematic view of a fifth embodiment of the upper screw body of the present invention. [Figure 25] FIG. 10 is a schematic view of a sixth embodiment of the upper screw body of the present invention. [Figure 26] 1 is a schematic view of a first embodiment of a screw head according to the present invention; [Figure 27] FIG. 2 is a schematic view of a second embodiment of the screw head of the present invention. [Figure 28] FIG. 10 is a schematic view of a third embodiment of the screw head of the present invention. [Figure 29] FIG. 10 is a schematic view of a fourth embodiment of the screw head of the present invention. [Figure 30] FIG. 10 is a schematic view of a fifth embodiment of the screw head of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] In order to better understand and appreciate the objects, features, and advantages of the present invention, the following detailed description will be made with reference to the drawings in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0019] First, as shown in Figures 1 and 2, the present invention provides a structure of a low resistance crack prevention screw, which includes a low resistance screw (10), which is divided from top to bottom into an upper thread body (11), a middle thread body (12), a lower thread body (13), and a tapered thread tip (14), of which at least one cutting groove (131) is recessed in the lower thread body (13), and as shown in Figures 3 to 7, the cutting groove (131) gradually becomes deeper from top to bottom, and as shown in Figure 8, and the cutting groove (131) is inclined at a cutting pitch angle (X) with respect to the central axis of the low resistance screw (10), and the cutting pitch angle (X) is between 10 degrees and 20 degrees. As shown in FIG. 9, the cutting groove (131) is divided into a flat first groove portion (1311) and an inclined second groove portion (1312), and the second groove portion (1312) is inclined at an inclination gradient angle (Y) with respect to the radial direction, and the inclination gradient angle (Y) is between 79 degrees and 89 degrees. The maximum depth of the second groove portion (1312) is less than 55% of the radius of the lower thread body (13). As shown in Figures 10 and 11, when the lower side of the cutting groove (131) approaches the space between both sides of the thread tip (14), it gradually shrinks to form a resistance reduction angle (Z). The resistance reduction angle (Z) is between 15 degrees and 20 degrees. When the chips start to enter the cutting groove (131) and leave it, unnecessary packing and shrinkage occur, increasing resistance. This prevents the thread from breaking, thereby improving the effect of complete penetration when screwed in. A spiral lower thread (101) is provided on the surface of the lower screw body (13) and the screw tip (14), and the lower thread (101) and the cutting groove (131) are inclined in the same direction relative to the central axis of the low resistance screw (10), and the lower thread (101) is continuously formed, and the cutting groove (131) is separated by the lower thread (101).

[0020] As shown in Figures 12 and 13, in actual use, the thread tip 14 of the low resistance screw 10 is used to butt against the workpiece to be screwed, and the low resistance screw 10 is turned to screw in. The lower thread 101 is planed to drill the drill hole 20 to achieve a tapping effect, and the low resistance screw 10 can be screwed into the workpiece. At least one cutting groove 131 is recessed in the lower thread body 13, and extra space is maintained, so that chips generated after the lower thread 101 is planed can be easily removed. can enter and exit through the cutting groove (131), which improves the speed and efficiency of the discharge of chips out of the drill hole (20), and prevents the accumulation of chips from reducing tapping efficiency, and prevents the accumulation of chips from colliding with the low resistance screw (10), causing distortion and reducing the quality of screw fastening. Furthermore, since the lower thread (101) is continuously shaped and the cutting groove (131) is separated by the lower thread (101), it is possible to prevent the chips from being discharged in a non-spiral direction and becoming clogged.

[0021] According to the above structure, the grooves (131) are not located on the tip (14) but are recessed into the lower screw body (13), and therefore do not harm the structure of the tip (14). This increases the strength of the structure, and prevents the tip (14) from breaking during manufacturing, and the tip (14) from breaking into the drilled hole (20) when the low resistance screw (10) is subsequently unscrewed and removed from the drilled hole (20). The grooves (131) become gradually deeper from top to bottom, and the grooves (131) become deeper the closer they are to the bottom of the low resistance screw (10). This allows the low resistance screw (10) to withstand greater resistance encountered at its tip when tapping. Since the second groove portion (1312) can accommodate more chips than the first groove portion (1312), the cutting efficiency is improved. Furthermore, since the maximum depth of the second groove portion (1312) is less than 55% of the radius of the lower thread body (13), the cutting efficiency is maintained while ensuring the structural strength of the lower thread body (13) to prevent fracture and breakage during processing, manufacturing, or use. Furthermore, since the cutting groove (131) is inclined at the cutting pitch angle (X) with respect to the central axis of the low resistance screw (10), and the lower thread (101) and the cutting groove (131) are inclined in the same direction with respect to the central axis of the low resistance screw (10), the chips can be smoothly introduced into the cutting groove (131), further improving the cutting efficiency.

[0022] Furthermore, as the lower side of the cutting groove (131) approaches the space between the two sides of the screw tip (14), it gradually shrinks to form the resistance reduction angle (Z). Therefore, when the low resistance screw (10) is first tapped into the workpiece, the bottom of the cutting groove (131) is narrower, which prevents the initial chips of the low resistance screw (10) from getting stuck in the cutting groove (131) and shrinking, which would increase resistance. At the same time, it also prevents the low resistance screw (10) from shaking due to excessive resistance when it is first turned, which reduces the resistance and improves the ability of the low resistance screw (10) to penetrate completely.

[0023] Therefore, the low resistance screw 10 of the present invention maintains the strength of the structure while improving the cutting efficiency, and has many advantages in use.

[0024] As shown in FIG. 8, the present invention provides a structure of low resistance crack prevention screw, wherein the angle of said lower thread (101) is between 37 degrees and 43 degrees.

[0025] As shown in FIG. 9, the present invention provides a structure of a low resistance crack prevention screw, wherein the depth of the first groove portion (1311) is between 15% and 20% of the radius of the lower screw body (13).

[0026] As shown in Figure 2, the present invention provides a low resistance crack prevention screw structure, in which a spiral upper thread (102) is provided on the surface of the upper thread body (11), and the spiral direction of the upper thread (102) is exactly opposite to the spiral direction of the lower thread (101), so that the low resistance screw (10) has a forward tooth and reverse tooth structure.

[0027] As shown in FIG. 8, the present invention provides a structure of a low resistance crack prevention screw, where the cutting pitch angle (X) is 15 degrees.

[0028] As shown in FIG. 9, the present invention provides a structure of a low resistance crack prevention screw, wherein the bevel gradient angle (Y) is 84 degrees.

[0029] As shown in Figures 10 and 11, the present invention provides a structure of a low resistance crack prevention screw, where the resistance reduction angle (Z) is 18 degrees.

[0030] The present invention provides a low resistance crack prevention screw structure, in which both sides of the cutting groove (131) are inclined, the included angle of both sides of the cutting groove (131) is 65 degrees, the inclination angle of one side of the cutting groove (131) is 45 degrees, and the inclination angle of the other side is 20 degrees, where the inclination angle is larger, chips can slide into the cutting groove (131), and where the inclination angle is smaller, chips will pile up.

[0031] The present invention provides a low resistance crack prevention screw structure, wherein the maximum depth of the second groove portion (1312) is between 40% and 55% of the radius of the lower screw body (13).

[0032] As shown in Figures 14 to 19, there are schematic diagrams showing various shapes of the internal thread body 12, and the surface shape of the internal thread body 12 has different effects and appearances.

[0033] As shown in Figures 20 to 25, there are schematic diagrams showing various shapes of the upper screw body (11), and different shapes of the upper thread (102) have different effects or turning directions.

[0034] The low resistance screw (10) is provided at its top end with a screw head (15) that takes advantage of the screw fastening. As shown in Figures 26 to 30, these are schematic diagrams showing various shapes of the screw head (15), and different shapes of the screw head (15) have different effects.

[0035] The above is merely one embodiment of the present invention and is not intended to limit the scope of the present invention, and all changes and modifications made within the scope of the claims of the present invention are also within the scope of the present invention. [Explanation of symbols]

[0036] 10 Low resistance screws 101 Bottom Thread 102 Upper thread 11 Upper screw body 12 Middle screw body 13 Lower screw body 131 Carved groove 1311 First groove 1312 Second groove 14 Screw tip 15 screw head 20 drill holes X Cutting pitch angle Y Tilt Angle Z Drag reduction angle

Claims

1. A structure of a low resistance crack prevention screw, including a low resistance screw, the low resistance screw being divided from top to bottom into an upper screw body, a middle screw body, a lower screw body, and a tapered screw tip; At least one machining groove is recessed into the lower thread body, the machining groove gradually becomes deeper from top to bottom, and the machining groove is inclined with respect to the central axis of the low resistance screw at a machining pitch angle, the machining pitch angle being between 10 degrees and 20 degrees, the machining groove is divided into a flat first groove portion and an oblique second groove portion, the second groove portion is inclined with respect to the radial direction at an inclination gradient angle, the inclination gradient angle being between 79 degrees and 89 degrees, the maximum depth of the second groove portion is less than 55% of the radius of the lower thread body, and as the lower side of the machining groove approaches between both side surfaces of the thread tip, The resistance reduction angle is gradually reduced to form a resistance reduction angle, the resistance reduction angle being between 15 and 20 degrees, and it is possible to prevent unnecessary packing and shrinkage from occurring when the shavings start to enter the cutting groove and when they leave it, thereby increasing the effect of complete penetration when screwing in, and a spiral lower thread is provided on the surface of the lower screw body and the screw tip, the lower thread and the cutting groove are inclined in the same direction relative to the central axis of the low resistance screw, the lower thread is in a continuous shape, and the cutting groove is separated by the lower thread.

2. 2. The low resistance crack prevention screw structure of claim 1, wherein the angle of the lower thread is between 37 and 43 degrees.

3. 2. The structure of claim 1, wherein the depth of said first groove is between 15% and 20% of the radius of said lower thread body.

4. The structure of a low resistance crack-preventing screw according to claim 1, characterized in that a spiral upper thread is provided on the surface of the upper thread body, and the spiral direction of the upper thread is directly opposite to the spiral direction of the lower thread.

5. 2. The structure of a low resistance crack prevention screw according to claim 1, wherein the cutting pitch angle is 15 degrees.

6. 2. The structure of a low resistance crack prevention screw according to claim 1, wherein said bevel gradient angle is 84 degrees.

7. 2. The structure of a low resistance crack prevention screw according to claim 1, wherein the resistance reduction angle is 18 degrees.

8. The structure of the low resistance crack prevention screw according to claim 1, characterized in that both sides of the cutting groove are inclined, and the included angle between the two side surfaces of the cutting groove is 65 degrees.

9. 9. The structure of a low resistance crack-preventing screw according to claim 8, wherein the angle of inclination of one side of said groove is 45 degrees and the angle of inclination of the other side is 20 degrees.

10. 2. The structure of a low resistance crack-preventing screw according to claim 1, wherein the maximum depth of said second groove portion is between 40% and 55% of the radius of said lower thread body.

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