Tap with low resistance to extrusion

Abstract

The present application provides a tap with low extrusion resistance, which comprises a shank and a thread section. The thread section is provided with a plurality of flutes around a mandrel. The periphery of each of the flutes has two first cutting edges and two second cutting edges. The first distance between the two first cutting edges is greater than the second distance between the two second cutting edges, so that the periphery of the flutes of the tap is provided with unequal lengths. This can provide smaller extrusion resistance and prevent the tap from being broken during machining.

Description

Technical Field

[0001] This invention relates to a forming tap, and more particularly to a tap with low forming resistance. Background Technology

[0002] like Figure 1 The image shown is a top view of a known extrusion tap 1, which is mainly a tool for forming internal threads in a hole A by plastic forming.

[0003] The tap 1 has a toothed section 2, the cross-section of which is a square with equal divisions. Four serrated edges 3 are arranged around the periphery of the toothed section 2, and each pair of adjacent serrated edges 3 has a pressing point 4. During forming, the four pressing points 4 of the tap 1 come into contact with the hole A, thus generating resistance. In other words, the tap 1 applies force to the inner wall of the hole A at four points. This results in significant pressing resistance, making the tap 1 prone to breakage during processing. Summary of the Invention

[0004] To address the aforementioned issues, this invention discloses a tap with low extrusion resistance, wherein the periphery of its teeth is set with unequal lengths, which provides lower extrusion resistance and makes the tap less prone to breakage during processing.

[0005] To achieve the above objectives, this invention provides a tap with low extrusion resistance, comprising a shank and a threaded section. The threaded section extends along a mandrel of the shank and is formed at one end of the shank. The threaded section has a plurality of teeth around the mandrel. Each tooth has four extrusion points and two spaced-apart first cutting edges and two second cutting edges connected between the two first cutting edges. There is an extrusion point between adjacent first and second cutting edges. The threaded section has a first transverse axis and a second transverse axis passing through the mandrel and not perpendicular to each other. The first transverse axis passes through two mutually distant extrusion points, and the second transverse axis passes through the other two mutually distant extrusion points. There is a first spacing angle and a second spacing angle between the first and second transverse axes. The first spacing angle faces the first cutting edge, and the second spacing angle faces the second cutting edge. The first spacing angle is greater than the second spacing angle.

[0006] In another embodiment of the present invention, the first spacing angle is greater than 90 degrees and the second spacing angle is less than 90 degrees.

[0007] In another embodiment of the present invention, the first spacing angle is 93 degrees and the second spacing angle is 87 degrees.

[0008] In another embodiment of the present invention, each first cutting edge includes a first yielding surface and first arc edges located on both sides of the first yielding surface, each second cutting edge includes a second yielding surface and second arc edges located on both sides of the second yielding surface, and the distance between the two first yielding surfaces is greater than the distance between the two second yielding surfaces.

[0009] In another embodiment of the present invention, the distance between the two first relief surfaces is 1.04 mm, and the distance between the two second relief surfaces is 1 mm.

[0010] In another embodiment of the present invention, the maximum outer diameter of the threaded section is 1.245 mm, and the root diameter of the threaded section is 0.95 mm.

[0011] In another embodiment of the present invention, a tap with low extrusion resistance is provided, comprising a shank and a threaded section. The threaded section extends along a mandrel of the shank and is formed at one end of the shank. The threaded section has a plurality of teeth around the periphery of the mandrel. Each tooth has four extrusion points, two spaced-apart first cutting edges, and two second cutting edges connected between the two first cutting edges. There is an extrusion point between adjacent first and second cutting edges. The threaded section has a first transverse axis and a second transverse axis passing through the mandrel. There is a first spacing angle and a second spacing angle between the first and second transverse axes. The first spacing angle faces the first cutting edge, and the second spacing angle faces the second cutting edge. The first spacing angle is greater than the second spacing angle. There is a first distance between the two first cutting edges and a second distance between the two second cutting edges. The first distance is greater than the second distance.

[0012] Therefore, by designing the first and second spacing angles to be unequally distributed, the present invention ensures that the force is applied only at the two diagonal pressing points of the teeth during tapping, thereby providing less pressing resistance and making the tap less prone to breakage during processing. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a known extrusion tap inside a hole. Figure 2 This is a schematic diagram of the tap with low extrusion resistance according to the present invention. Figure 3 This is a schematic diagram showing the appearance of the low extrusion resistance tap of the present invention inside a hole. Figure 4 This is a comparison table of the maximum torque of the taps of the present invention and comparative examples. Figure 5 This is a comparison table of the thread fill rate of the taps in this invention and comparative examples. Detailed Implementation

[0014] Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings. The present invention is not intended to limit the technical principles of the invention to the specific disclosed embodiments, but its scope is limited only by the scope of the claims, which includes alternatives, modifications and equivalents.

[0015] Please see Figures 2 to 3 As shown, a low-resistance tap 100 of the present invention is a forming tap comprising a shank 10 and a threaded section 20. The threaded section 20 extends along a mandrel X of the shank 10 and is formed at one end of the shank 10. The shank 10 is clamped and fixed by a tapping tool so as to drive the threaded section 20 to tap an internal thread into a hole A.

[0016] The threaded segment 20 has a plurality of teeth 21 around the mandrel X. Each tooth 21 has four pressing points 22 and two spaced-apart first cutting edges 23 and two second cutting edges 24 connected between the two first cutting edges 23. In this embodiment of the invention, there is a pressing point 22 between adjacent first cutting edges 23 and second cutting edges 24. The maximum outer diameter B of the threaded segment 20 is 1.245 mm, and the root diameter C of the threaded segment 20 is 0.95 mm.

[0017] There is a first distance D1 between the two first cutting edges 23 and a second distance D2 between the two second cutting edges 24. The first distance D1 is greater than the second distance D2, so that the four sides of the tooth 21 have unequal widths.

[0018] In this embodiment of the invention, each first cutting edge 23 includes a first yielding surface 231 and first arcuate edges 232 located on both sides of the first yielding surface 231, with one end of each first arcuate edge 232 connected to the first yielding surface 231 and the other end connected to a pressing point 22. Each second cutting edge 24 includes a second yielding surface 241 and second arcuate edges 242 located on both sides of the second yielding surface 241, with one end of each second arcuate edge 242 connected to the second yielding surface 241 and the other end connected to a pressing point 22. It should be noted that a pressing point 22 is located between adjacent first cutting edges 23 and second cutting edges 24, and between the first arcuate edge 232 and the second arcuate edge 242. The distance between two first yielding surfaces 231 is defined as the first distance D1, and the distance between two second yielding surfaces 241 is defined as the second distance D2. The distance between the two first relief surfaces 231 (first distance D1) is 1.04 mm, and the distance between the two second relief surfaces 241 (second distance D2) is 1 mm.

[0019] It should be noted that by setting each of the first relief surfaces 231 and each of the second relief surfaces 241, the gap between the teeth 21 and the inner wall of the hole A is increased, so as to inject more cutting fluid and provide better lubrication during the operation of the tap 100.

[0020] In this embodiment of the invention, the threaded segment 20 has a first transverse axis Y1 and a second transverse axis Y2 passing through the mandrel X and not perpendicular to each other. The first transverse axis Y1 passes through two mutually distant pressing points 22, and the second transverse axis Y2 passes through two other mutually distant pressing points 22. Furthermore, as... Figure 3 As shown, the four extrusion points 22 of this invention are, based on the upper right corner and in a clockwise direction, the first extrusion point 221, the second extrusion point 222, the third extrusion point 223, and the fourth extrusion point 224. The first horizontal axis Y1 passes through the first extrusion point 221 and the third extrusion point 223, and the second horizontal axis Y2 passes through the second extrusion point 222 and the fourth extrusion point 224.

[0021] A first spacing angle θ1 and a second spacing angle θ2 exist between the first horizontal axis Y1 and the second horizontal axis Y2. The first spacing angle θ1 faces the first cutting edge 23, and the second spacing angle θ2 faces the second cutting edge 24. The first spacing angle θ1 is greater than the second spacing angle θ2. In this embodiment of the invention, the sum of the first spacing angle θ1 and the second spacing angle θ2 is 180 degrees. Preferably, the first spacing angle θ1 is greater than 90 degrees, and the second spacing angle θ2 is less than 90 degrees. More preferably, the first spacing angle θ1 is 93 degrees, and the second spacing angle θ2 is 87 degrees.

[0022] To further clarify, the first spacing angle θ1 is the angle formed by connecting the first extrusion point 221 to the mandrel X and the second extrusion point 222 to the mandrel X, or the angle formed by connecting the third extrusion point 223 to the mandrel X and the fourth extrusion point 224 to the mandrel X. The second spacing angle θ2 is the angle formed by connecting the first extrusion point 221 to the mandrel X and the fourth extrusion point 224 to the mandrel X, or the angle formed by connecting the second extrusion point 222 to the mandrel X and the third extrusion point 223 to the mandrel X.

[0023] like Figure 3 As shown, the present invention utilizes the unequal distribution of the first spacing angle θ1 and the second spacing angle θ2 between the first horizontal axis Y1 and the second horizontal axis Y2. Therefore, the four pressing points 22 are slightly shifted inward relative to the inner wall of the hole A, forming an unequal division of the diagonal of the teeth 21. During tapping operations, the force is applied only at the two diagonal pressing points 22 of the teeth 21 (such as the first pressing point 221 and the third pressing point 223, or the second pressing point 222 and the fourth pressing point 224), thereby providing less pressing resistance and making the tap 100 less prone to breakage during processing.

[0024] Please see Figure 4As shown in the comparison table, the torque test of the tap of the present invention and the comparative example tap was conducted using a Kistler-9273 power meter (torque sensor). The table shows that the maximum torque that the tap of the present invention can withstand is 20 N-mm, while the maximum torque that the comparative example tap can withstand is 31.42 N-mm. It can be seen that the resistance of the tap of the present invention is less than that of the comparative example tap, which makes the tap of the present invention less prone to breakage during processing.

[0025] Please refer to Figure 5, which is a comparison table of the internal thread fullness (%) of the tap of the present invention and the comparative example tap. It shows that the tap of the present invention can achieve an internal thread fullness of 87.13%, which is higher than the internal thread fullness of 86.44% of the comparative example tap, and can achieve the expected tapping effect.

[0026] The above description, while illustrating a preferred embodiment, allows those skilled in the art to make various modifications without departing from the spirit and scope of the invention. The foregoing embodiments are merely illustrative and not intended to limit the scope of the invention. All modifications or alterations made without departing from the spirit of the invention are within the scope of the patent applications. [Symbol Explanation]

[0027] 1: Tap. 2: Tooth. 3: Teeth. 4: Extrusion point. A: Hole. 100: Tap. 10: Rod section. 20: Threaded section. 21: Teeth. 22: Extrusion point. 221: First extrusion point. 222: Second extrusion point. 223: Third extrusion point. 224: Fourth extrusion point. 23: First cutting edge. 231: First yielding surface. 232: First arc edge. 24: Second cutting edge. 241 Second yielding surface. 242: Second arc edge. X: Mandrel. B: Maximum outer diameter. C: Root diameter. D1: First distance. D2: Second distance. Y1: First horizontal axis. Y2: Second horizontal axis. θ1: First spacing angle. θ2: Second spacing angle.

Claims

1. A tap with low extrusion resistance, characterized in that, The tap includes: One part; and A threaded segment extends along a spindle of the rod and is formed at one end of the rod. The threaded segment has a plurality of teeth around the spindle. Each tooth has four pressing points, two spaced-apart first cutting edges, and two second cutting edges connected between the two first cutting edges. There is a pressing point between adjacent first and second cutting edges. The threaded segment has a first transverse axis and a second transverse axis passing through the spindle and not perpendicular to each other. The first transverse axis passes through two of the pressing points that are far apart from each other, and the second transverse axis passes through the other two pressing points that are far apart from each other. There is a first spacing angle and a second spacing angle between the first transverse axis and the second transverse axis. The first spacing angle faces the first cutting edge, and the second spacing angle faces the second cutting edge. The first spacing angle is greater than the second spacing angle. Wherein, the first spacing angle is greater than 90 degrees, and the second spacing angle is less than 90 degrees; Each of the first cutting edges includes a first relief surface and a first arc edge located on both sides of the first relief surface, and each of the second cutting edges includes a second relief surface and a second arc edge located on both sides of the second relief surface, and the distance between the two first relief surfaces is greater than the distance between the two second relief surfaces.

2. The tap with low extrusion resistance as described in claim 1, characterized in that, The first spacing angle is 93 degrees, and the second spacing angle is 87 degrees.

3. The tap with low extrusion resistance as described in claim 1, characterized in that, The distance between the two first relief surfaces is 1.04 mm, and the distance between the two second relief surfaces is 1 mm.

4. The tap with low extrusion resistance as described in claim 3, characterized in that, The maximum outer diameter of the threaded section is 1.245 mm, and the root diameter of the threaded section is 0.95 mm.

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