Arc-shaped locking screw

Abstract

This is a locking screw with an arc structure, belonging to the field of screw technology. The locking screw with an arc structure includes a female thread (1) and a male thread (2). At least one of the roots (1-3, 2-3) of the female thread (1) and the male thread (2) has an arc thread structure with a root arc. The male thread (2) has a contact crest (2-1) that abuts against the root arc of the female thread (1) when the female thread and the male thread are threaded together, or the female thread (1) has a contact crest (1-1) that abuts against the root arc of the male thread when the female thread and the male thread are threaded together. The contact point between the female and male threads is not a linear step, but rather the tooth root arc and the contact tooth crest (1-1, 2-1). Since the contact point is closer to the lowest point of the tooth root arc than in a linear step, under the same external load, the angle between the direction in which the support force of the female and male threads acts and the radial direction of the threads, i.e., the angle α1, becomes smaller, and sin α1 also becomes smaller. Therefore, the support force N1 between the female and male threads increases. As a result, the friction force between the female and male threads increases, improving anti-loosening performance.

Description

[Technical Field]

[0001] The present invention relates to a locking screw having an arc structure, and belongs to the technical field of screws. [Background technology]

[0002] Threaded connections are a common industrial connection method, widely used in fields such as wind power generation, shipbuilding, automobile manufacturing, aerospace, and machinery production. Threaded connections have become the most common connection method due to their strong connection strength, convenient removal, and ease of manufacturing. When subjected to external force, threaded connections often loosen and lose their connection strength, potentially resulting in serious safety accidents. Traditional anti-loosening theories cite insufficient friction between the female and male threads, resulting in relative slippage, as the main cause of loosening. However, traditional metric and MJ threads, for example, have a bearing force between the female and male threads of only 1.15 times the axial force, making them prone to loosening under vibration loads.

[0003] The prior art also includes threads with a circular arc structure, such as the high-strength circular arc screw pair disclosed in the Chinese Utility Model Patent Application Publication No. CN209818480U. This screw pair includes a bolt and a nut. The male thread on the bolt is formed by sequentially connecting an upper crest arc, a straight section, a lower root arc, and a straight section. The radii of the upper crest arc and the lower root arc are equal, and the straight section is tangent to the upper crest arc and the lower root arc, respectively. The female thread on the nut is formed by sequentially connecting an upper semicircular arc, a straight section, and a crest. The crest is flat, and the straight section is tangent to the upper semicircular arc.

[0004] The tooth roots of both the female and male threads feature a large arc thread structure, which effectively improves the fatigue and support performance of the mating product. However, the female and male threads on the bolt and nut are in surface contact with each other. That is, as shown in Figure 1, the linear section of female thread 1 contacts the linear section of male thread 2. A support force N1 = F0 / sinα1 acts from female thread 1 to male thread 2. Here, F0 is the external load acting on male thread 2. α1 is the angle between the direction in which N1 acts and the radial direction of the thread, which is numerically equal to the thread angle, i.e., 60°. The direction in which N1 acts is perpendicular to the linear section. Due to the limited support force N1 due to the restriction of angle α1, the anti-loosening performance of this arc-threaded mating product is not significantly improved compared to conventional metric threads. Similarly, the support force between the female and male threads is approximately 1.15 times the axial force, resulting in insufficient friction and poor anti-loosening performance. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to provide an arc-structure locking screw that solves the problem of limited bearing capacity and poor locking performance due to contact between the female and male threads of conventional arc-structure screws caused by linear sections. [Means for solving the problem]

[0006] In order to achieve the above object, the arc-structure locking screw of the present invention employs the following technical solution. The locking screw has an arc-shaped structure and includes a female thread and a male thread. The tooth root of at least one of the female thread and the male thread has an arc-shaped thread structure with a tooth root arc. The male thread has a contact tooth crest that abuts against the tooth root arc of the female thread when the female thread and the male thread are threaded together. Alternatively, the female thread has a contact tooth crest that abuts against the tooth root arc of the male thread when the female thread and the male thread are threaded together.

[0007] The beneficial effects of the above technical solution are as follows. The present invention proposes an improved anti-loosening screw with an arc structure. The main improvement of the present invention is that the male thread has a contact tooth crest that abuts the root arc of the female thread when the female thread and the male thread are threaded together, or that the female thread has a contact tooth crest that abuts the root arc of the male thread when the female thread and the male thread are threaded together. That is, the main improvement of the present invention is that the female thread and the male thread contact each other at the root arc and the contact tooth crest, rather than at the linear step. Because the contact point is closer to the lowest point of the root arc than at the linear step, under the same external load, the angle between the direction in which the support force of the female thread and the male thread acts and the thread radial direction is smaller. That is, the angle α1 is smaller. And because sin α1 is smaller, the support force N1 of the female thread and the male thread is larger. As a result, the friction force between the female thread and the male thread is increased, improving anti-loosening performance.

[0008] Furthermore, when the radial distance from the contact point between the contact crest and the root arc to the center of the root arc is l and the radius of the root arc is r, and k=l / r, the value of k is set to a range of 0.5 to 1. As a further improvement, the value of k is set to a range of 0.55 to 0.866. As a further improvement, the value of k is set to a range of 0.67 to 0.866. As a further improvement, the value of k is set to a range of 0.714 to 0.866.

[0009] The beneficial effect of the above technical solution is that by setting the value of k within the above range, good anti-loosening performance can be obtained.

[0010] Furthermore, the female thread includes a crest, a first transition step, a root, and a second transition step, connected in that order, and the male thread includes a crest, a third transition step, a root, and a fourth transition step, connected in that order. The root of the female thread has a root arc, and the crest of the male thread constitutes a contact crest.

[0011] The beneficial effect of the above technical solution is that the crest of the male thread contacts the root arc of the female thread, which makes manufacturing and assembly easier.

[0012] Furthermore, the contact tooth crest has a tooth crest arc.

[0013] The beneficial effect of the above technical solution is that stress concentration and damage to the anticorrosion coating are reduced.

[0014] Furthermore, both the first transition stage and the second transition stage are linear stages.

[0015] The beneficial effect of the above technical solution is to facilitate the transition to the tooth crest and root.

[0016] Furthermore, each of the first transition step and the second transition step contacts the tooth root of the female thread.

[0017] Furthermore, both the third transition step and the fourth transition step are straight line segments.

[0018] The beneficial effect of the above technical solution is to facilitate the transition to the tooth crest and root.

[0019] Furthermore, the female thread may include a crest, a first transition step, a root, and a second transition step connected in that order, and the male thread may include a crest, a third transition step, a root, and a fourth transition step connected in that order, where the root of the male thread has the root arc, and the crest of the female thread constitutes the contact crest.

[0020] The beneficial effect of the above technical solution is that the crest of the female thread contacts the root arc of the male thread, which makes manufacturing and assembly easier.

[0021] Furthermore, the contact crest is a spur crest.

[0022] The beneficial effect of the above technical solution is that it is easy to process and manufacture.

[0023] Furthermore, both the first transition stage and the second transition stage are linear stages.

[0024] The beneficial effect of the above technical solution is that the transition between the tooth top and the tooth bottom is easy.

[0025] Furthermore, both the third transition stage and the fourth transition stage are linear stages.

[0026] Furthermore, the third transition step and the fourth transition step contact the tooth crest and the tooth root of the male thread, respectively.

[0027] The beneficial effect of the above technical solution is that the transition between the tooth top and the tooth bottom is easy. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a diagram showing the fitting configuration of a female thread and a male thread in a case where both the female thread and the male thread are arc-shaped threads in the prior art. [Figure 2] FIG. 1 is a diagram showing the configuration of a first embodiment of a locking screw with an arc structure according to the present invention. [Figure 3] FIG. 3 is an enlarged view of the engagement between the crest of the male thread and the root of the female thread in FIG. 2. [Figure 4] FIG. 10 is an enlarged view of the engagement between the tooth root of the male thread and the tooth crest of the female thread in Example 2 of the arc-structure locking screw of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The features and performance of the present invention will be described in more detail below based on examples.

[0030] Example 1 of the arc-shaped locking screw of the present invention: According to this embodiment, by bringing the crest of the male thread and the root of the female thread into contact, the contact position approaches the lowest point of the root arc. As a result, under the same external load, the angle between the direction in which the support force of the female and male threads acts and the radial direction of the threads, i.e., the angle α1, becomes smaller. As sin α1 becomes smaller, the support force N1 of the female and male threads increases, and the friction force between the female and male threads also increases. As a result, the anti-loosening performance is improved.

[0031] Specifically, as shown in Figures 2 and 3, the arc-structure locking screw includes a female thread 1 and a male thread 2. Both the female thread 1 and the male thread 2 are arc-shaped threads. The female thread 1 includes, connected in order, a tooth crest (i.e., the female thread crest 1-1), a first transition stage 1-2, a tooth root (i.e., the female thread root 1-3), and a second transition stage 1-4. Here, the female thread crest 1-1 is a spur crest, and the female thread root 1-3 has an arc-shaped thread structure with a root arc. The first transition stage 1-2 and the second transition stage 1-4 are both linear stages. The first transition stage 1-2 and the second transition stage 1-4 are each in contact with the female thread root 1-3.

[0032] The male thread 2 includes, connected in order, a tooth crest (i.e., a male thread crest 2-1), a third transition stage 2-2, a tooth root (i.e., a male thread root 2-3), and a fourth transition stage 2-4. Here, the male thread crest 2-1 has a circular arc thread structure with a tooth crest arc, and the male thread root 2-3 has a circular arc thread structure with a tooth root arc. The third transition stage 2-2 and the fourth transition stage 2-4 are both linear stages. The third transition stage 2-2 and the fourth transition stage 2-4 contact the male thread crest 2-1 and the male thread root 2-3, respectively.

[0033] In this embodiment, as shown in Figure 2, when the female thread 1 and the male thread 2 are screwed together, a load is applied to the female thread 1 and the male thread 2. When the female thread 1 and the male thread 2 move relative to each other and come into contact, the crest 2-1 of the male thread abuts against the root 1-3 of the female thread. In other words, the contact point between the root arc of the female thread 1 and the crest of the male thread 2 is located on the root arc of the female thread 1, and the crest 2-1 of the male thread forms a contact crest that abuts against the root arc of the root 1-3 of the female thread.

[0034] A bearing force N2 = F0 / sinα2 acts from the female thread 1 to the male thread 2. Here, F0 is the external load acting on the male thread 2. Since α1 > α2, N2 > N1. In other words, since the external load F0 remains the same and the contact point position changes, the angle between the direction in which the bearing force of the female and male threads acts and the radial direction of the threads becomes smaller. As a result, the angle that was α1 (shown in Figure 1) in the prior art becomes smaller. And because sinα1 becomes smaller, the bearing force N1 of the female and male threads increases (becomes N2). As a result, the friction force between the female and male threads increases, improving anti-loosening performance.

[0035] In this embodiment, the radial distance from the contact point between the contact crest of the male thread 2 and the root arc of the female thread 1 to the center of the root arc of the female thread 1 (i.e., the projected length of the line segment from the contact point to the center of the root arc in a radial plane perpendicular to the axis of the thread pair) is l, the radius of the root arc of the female thread 1 is r, and k = l / r. The value of k is set to a range of 0.5 to 1 (the maximum range, where the thread angle is 60°). Theoretically, the larger k, the greater the bearing force generated between the female thread 1 and the male thread 2. Preferably, the value of k can be 0.55, 0.67, 0.714, or 0.866. These are all parameters of conventional, general circular-arc threads. Table 1 shows the bearing forces corresponding to different k values.

[0036] [Table 1]

[0037] The accuracy of the above conclusion is verified below using the specific dimensions of a circular arc thread. As shown in Figure 3, assume that the root arc radius of the female thread root 1-3 is R = 2.8 mm (i.e., O1A = 2.8 mm), the major diameter of the female thread 1 is D = 48.44 mm, the crest arc radius of the male thread crest 2-1 is r1 = 2 mm (i.e., O2A = 2 mm), the root arc radius of the male thread root 2-3 is r2 = 2 mm, and the major diameter of the male thread 2 is d = 48.3 mm.

[0038] When a load is applied to the female and male threads and they mesh, the contact point A between the female and male threads, the center O1 of the root arc of the female thread root 1-3, and the center O2 of the crest arc of the male thread crest 2-1 are all on the same line. The distance from the center O1 of the female thread root 1-3 to the thread pair axis is l1 = D / 2 - O1C1 = 24.22 - R = 24.22 - 2.8 = 21.42 mm, and the distance from the center O2 of the male thread crest 2-1 to the thread pair axis is l2 = d / 2 - O2C2 = 24.15 - r1 = 24.15 - 2 = 22.15 mm. The radial distance between the center O1 of the root 1-3 of the female thread and the center O2 of the crest 2-1 of the male thread, i.e., the length of the line segment O2B2, is l' = l2 - l1 = 22.15 - 21.42 = 0.73 mm. From the geometric similarity relationship (O1O2 / O1A = l' / l, O1A-O2A = O1O2 = 0.8 mm), the length of the line segment AB1 (i.e., the radial distance within the radial plane of the thread pair AO1) can be calculated as l = 2.555 mm. From the mathematical relationship, cosα2 = l / R = 0.913 (i.e., the value of k is 0.913). Therefore, sinα2 = (1-l 2 / R 2 ) 0.5 = 0.408, and N2 = F0 / sinα2 = F0 / 0.408, the bearing force N2 = 2.45F0 applied from female thread 1 to male thread 2 can be calculated. The bearing force N2 is greater than the bearing force of a regular thread and a Spirallock thread. Table 2 is a comparison table of the bearing force at the contact point between the thread of this application and threads of conventional technology. Note that the process of finding the bearing force of a regular thread and a Spirallock thread is conventional technology, and will not be described further in this invention.

[0039] [Table 2]

[0040] Example 2 of the arc-shaped locking screw of the present invention: This embodiment achieves the same effect as Example 1 by abutting the tooth root of the male thread and the tooth crest of the female thread. Specifically, as shown in FIG. 4, the specific thread structures of the female thread 1 and the male thread 2 in this embodiment are the same as those in Example 1. Here, the specific thread structures of the female thread 1 and the male thread 2 will not be further described. However, this embodiment differs from Example 1 in that the tooth root 2-3 of the male thread abuts the tooth crest 1-1 of the female thread. Therefore, the tooth crest 1-1 of the female thread forms a contact tooth crest that abuts the tooth root arc of the tooth root 2-3 of the male thread. Needless to say, the contact tooth crest is a spur tooth crest.

[0041] Assuming that the radius of the root arc of the male thread root 2-3 is r2 = 2 mm (i.e., OC = 2 mm), the minor diameter of the male thread 2 is d3 = 41.7 mm, and the minor diameter of the female thread 1 is D3 = 41.96 mm, the distance from the center O of the root arc of the male thread root 2-3 to the axis of the thread pair is l1 = d3 / 2 + OC = 41.7 / 2 + 2 = 20.85 + 2 = 22.85 mm. The length of the line segment AB is l = l1 - D3 / 2 = 22.85 - 41.96 / 2 = 22.85 - 20.98 = 1.87 mm. From the mathematical relationship, we can find that cosα2 = l / r2 = 0.935 (i.e., the value of k is 0.935), and therefore sinα2 = (1 - l 2 / r2 2 ) 0.5 = 0.355. Then, we can calculate the bearing force N3 applied from female thread 1 to male thread 2: N3 = F0 / sinα2 = F0 / 0.355 = 2.82F0. The bearing force N3 is much greater than the bearing force of a normal screw and a Spiral Lock screw.

[0042] In another embodiment of the locking screw with an arc structure, the first transition step, the second transition step, the third transition step and the fourth transition step may be arc surface transitions.

[0043] In another embodiment of the locking screw having an arc structure, the crest of the female thread may be an arc crest.

[0044] In another embodiment of the locking screw with an arc structure, the crest of the external thread may be a spur crest.

[0045] In another embodiment of the locking screw with an arc structure, the tooth root of either the female thread or the male thread may have an arc thread structure having a tooth root arc.

[0046] In other embodiments of the arc-shaped locking screw, the value of k may be less than 0.5 depending on the thread angle.

[0047] The above is a preferred embodiment of the present invention, and is not intended to limit the present invention. The patent protection scope of the present invention is governed by the claims, and any equivalent structural changes made using the specification and drawings of the present invention should be included in the protection scope of the present invention.

[0048] (Addendum) (Appendix 1) The thread structure includes a female thread and a male thread, and the tooth root of at least one of the female thread and the male thread has a circular arc thread structure having a tooth root arc, the male thread has a contact crest that abuts against a tooth root arc of the female thread when the female thread and the male thread are screwed together, Alternatively, the female thread has a contact tooth crest that abuts against a tooth root arc of the male thread when the female thread and the male thread are screwed together. Arc-shaped locking screw.

[0049] (Appendix 2) The value of k is in the range of 0.5 to 1, where l is the radial distance from the contact point between the contact crest and the root arc to the center of the root arc, r is the radius of the root arc, and k=l / r. The arc-shaped locking screw described in Appendix 1.

[0050] (Appendix 3) The value of k is in the range of 0.55 to 0.866. The arc-shaped locking screw described in Appendix 2.

[0051] (Appendix 4) The value of k is in the range of 0.67 to 0.866. The arc-shaped locking screw described in Appendix 2.

[0052] (Appendix 5) The value of k is in the range of 0.714 to 0.866. The arc-shaped locking screw described in Appendix 2.

[0053] (Appendix 6) the internal thread includes a tooth crest, a first transition step, a tooth root, and a second transition step connected in sequence; the external thread includes a tooth crest, a third transition step, a tooth root, and a fourth transition step connected in sequence; a tooth root of the female thread has the tooth root arc, a tooth apex of the male thread constitutes the contact tooth apex, A locking screw having an arc structure according to any one of appendices 1 to 5.

[0054] (Appendix 7) The contact tooth crest has a tooth crest arc. A locking screw with an arc structure as described in Appendix 6.

[0055] (Appendix 8) The first transition stage and the second transition stage are both linear stages. A locking screw with an arc structure as described in Appendix 6.

[0056] (Appendix 9) The first transition step and the second transition step each contact the tooth root of the female thread. A locking screw with an arc structure as described in Appendix 8.

[0057] (Appendix 10) The third transition stage and the fourth transition stage are both linear stages. A locking screw with an arc structure as described in Appendix 6.

[0058] (Appendix 11) the internal thread includes a tooth crest, a first transition step, a tooth root, and a second transition step connected in sequence; the external thread includes a tooth crest, a third transition step, a tooth root, and a fourth transition step connected in sequence; a tooth root of the male thread has the tooth root arc, a tooth apex of the female thread constitutes the contact tooth apex, A locking screw having an arc structure according to any one of appendices 1 to 5.

[0059] (Appendix 12) The contact tooth crest is a spur tooth crest. A locking screw with an arc structure as described in Appendix 11.

[0060] (Appendix 13) The first transition stage and the second transition stage are both linear stages. A locking screw with an arc structure as described in Appendix 11.

[0061] (Appendix 14) The third transition stage and the fourth transition stage are both linear stages. A locking screw with an arc structure as described in Appendix 11.

[0062] (Appendix 15) The third transition step and the fourth transition step contact the top and bottom of the male thread, respectively. A locking screw with an arc structure as described in Appendix 14. [Explanation of symbols]

[0063] 1: female thread, 1-1: female thread crest, 1-2: first transition stage, 1-3: female thread root, 1-4: second transition stage, 2: male thread, 2-1: male thread crest, 2-2: third transition stage, 2-3: male thread root, 2-4: fourth transition stage.

Claims

1. The thread structure includes a female thread and a male thread, and a tooth root of at least one of the female thread and the male thread has a circular arc thread structure having a tooth root arc, the male thread has a contact crest that abuts against a tooth root arc of the female thread when the female thread and the male thread are screwed together, Alternatively, the female thread has a contact tooth crest that abuts against a tooth root arc of the male thread when the female thread and the male thread are screwed together. Arc-shaped locking screw.

2. wherein the value of k is in the range of 0.5 to 1, where l is the radial distance from the contact point between the contact crest and the root arc to the center of the root arc, r is the radius of the root arc, and k = l / r. The locking screw having an arc structure according to claim 1.

3. The value of k is in the range of 0.55 to 0.

866. The locking screw having an arc structure according to claim 2.

4. The value of k is in the range of 0.67 to 0.

866. The locking screw having an arc structure according to claim 2.

5. The value of k is in the range of 0.714 to 0.

866. The locking screw having an arc structure according to claim 2.

6. the internal thread includes a tooth crest, a first transition step, a tooth root, and a second transition step connected in sequence; the external thread includes a tooth crest, a third transition step, a tooth root, and a fourth transition step connected in sequence; a tooth root of the female thread has the tooth root arc, a tooth apex of the male thread constitutes the contact tooth apex, The locking screw having an arc structure according to any one of claims 1 to 5.

7. The contact tooth crest has a tooth crest arc. The locking screw having an arc structure according to claim 6.

8. Both the first transition stage and the second transition stage are linear stages. The locking screw having an arc structure according to claim 6.

9. The first transition step and the second transition step each contact a tooth root of the female thread. The locking screw having an arc structure according to claim 8.

10. Both the third transition stage and the fourth transition stage are linear stages. The locking screw having an arc structure according to claim 6.

11. the internal thread includes a tooth crest, a first transition step, a tooth root, and a second transition step connected in sequence; the external thread includes a tooth crest, a third transition step, a tooth root, and a fourth transition step connected in sequence; a tooth root of the male thread has the tooth root arc, a tooth apex of the female thread constitutes the contact tooth apex, The locking screw having an arc structure according to any one of claims 1 to 5.

12. The contact tooth crest is a spur tooth crest. The locking screw having an arc structure according to claim 11.

13. Both the first transition stage and the second transition stage are linear stages. The locking screw having an arc structure according to claim 11.

14. Both the third transition stage and the fourth transition stage are linear stages. The locking screw having an arc structure according to claim 11.

15. The third transition step and the fourth transition step contact the tooth crest and the tooth root of the male thread, respectively. The locking screw having an arc structure according to claim 14.

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