Non-uniform pitch lock screw connection pair

Abstract

This invention provides a non-unequal pitch lock screw connection pair and belongs to the field of non-standard fastening members. The non-unequal pitch lock screw connection pair includes a female thread and a male thread, where the pitch of the female thread is greater than the pitch of the male thread. The difference in length between the female thread and the male thread is n turns. By using TIFF2026520195000199.tif1641, the threaded region of the female and male threads includes a primary load region near the starting position and a secondary load region near the ending position. The load between the female and male threads in the secondary load region is much smaller than in the primary load region, and in some cases, there is no load at all, which helps to increase the effective working length of the bolt. By separating the load concentration region from the primary sliding region of the female and male threads, the load concentration region is located near the starting position, and the sliding region extends from the ending position to the starting position. When the bolt rod bends, the secondary load region gradually begins to come into contact, increasing the force between the female and male threads, which helps to share the force due to the bending of the bolt rod.

Description

[Technical Field]

[0001] The present invention relates to non-equal pitch locking screw connection pairs and belongs to the field of non-standard fastening members. [Background technology]

[0002] Screw connections are characterized by their strong connection performance, ease of removal, and ease of manufacture, and are widely used in fields such as wind power generation, shipbuilding, automobile manufacturing, aerospace, and mechanical products. When screw connections are subjected to external perturbations, bolts often loosen and fail, leading to serious safety accidents. Conventional loosening prevention theories have revealed that the main cause of screw loosening is the occurrence of relative slippage due to insufficient friction between the female and male threads.

[0003] The specific process is as follows: When a screw is subjected to a lateral load while in a partially tightened state, the frictional force generated between the nut and the support surface (the end face to which the connected member is pressed against the nut) causes the nut to move in the direction of the lateral load, resulting in a certain degree of bending in the bolt rod. When the lateral load is relatively small, the static frictional force between the female and male threads is sufficient to overcome the force acting due to the bending of the bolt rod, and no relative slippage occurs between the female and male threads. However, as the lateral load increases, the static frictional force between the female and male threads becomes insufficient to overcome the force acting due to the bending of the bolt rod, and relative slippage occurs between the female and male threads, i.e., loosening occurs.

[0004] Upon investigating the cause, it was found that in conventional equal-pitch screws, both the load concentration region and the main sliding region of the female and male threads are located near the support surface (taking a nut as an example, the support surface is the end face of the nut that crimps the connected member, that is, the support surface is the end face at the end position of the threaded region of the female and male threads, and the other end face is the end face at the starting position). When a screw close to the support surface slips completely, the frictional force between the female and male threads far from the support surface is small, and it is not possible to prevent the expansion of the sliding region, so loosening of the screw connection pair is likely to occur. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide a non-unequal pitch threaded connection pair that solves the problem in conventional threaded connection pairs where, because both the load concentration region and the main sliding region of the female and male threads are located near the support surface, when the thread near the support surface slips completely, the frictional force between the female and male threads, which are farther from the support surface, is small, making it impossible to prevent the expansion of the sliding region and making the threaded connection pair prone to loosening. [Means for solving the problem]

[0006] To achieve the above objectives, the non-equal pitch locking screw connection pair in the present invention employs the following technical aspects.

[0007] An uneven-pitch locking screw connection pair, comprising a female thread and a male thread, where the pitch of the female thread is greater than the pitch of the male thread. The difference in length between the female thread and the male thread is n turns.

number

number

number

[0008] The beneficial effects of the above technical embodiment are as follows: The present invention proposes an improved non-unequal pitch locking screw connection pair, the main improvement being the difference in length between the n-turn female and male threads.

number

[0009] Furthermore, k, k c , taking into account all possible values ​​of K

number

number

[0010] The beneficial effects of the above technical embodiment are as follows: By giving l a specific lower limit, the anti-loosening effect is guaranteed.

[0011] Furthermore, if the threaded region of the female and male threads starts from the starting position, and the axial load on the male thread at any number of turns n' is F(n'),

number

number

number

number

number

number

number

number

number

number

number

number

number

number

[0012] The beneficial effects of the above technical embodiment are as follows: With a load F(n′), etc.

number

[0013] Furthermore, the difference in length between the female and male threads of an n-turn thread.

number

[0014] The beneficial effects of the above technical embodiment are as follows: By further reducing the lower limit of the difference l between the length of the n-turn female thread and the male thread, a better anti-loosening effect is guaranteed.

[0015] Furthermore, k, k c , taking into account all possible values ​​of K

number

number

[0016] The beneficial effects of the above technical aspects are as follows. By providing a new specific value for the lower limit, it facilitates the design, manufacture, and processing of the screw connection pair.

[0017] Furthermore, if the screwing region of the female screw and the male screw starts from the starting position and the axial load of the male screw thread at any number of turns n′ is F(n′),

Number

Number

Number

Number

Number

Number

Number

Number

number

number

number

[0018] The beneficial effects of the above technical solution are as follows: When F(n') gradually decreases with the number of turns of the screw within the range of 0 to n turns.

number

[0019] Furthermore, the difference in length between the female and male threads of the first turn screw.

number

[0020] The beneficial effects of the above technical embodiment are as follows: It provides an upper limit on the difference l1 in length between the female and male threads of the first turn screw, preventing the axial load of the male thread from being borne by the first turn screw and thus protecting the first turn screw.

[0021] Furthermore, the difference in length between the female and male threads of the first turn screw.

number

[0022] The beneficial effects of the above technical embodiment are as follows: By further reducing the upper limit of the difference l1 in length between the female and male threads of the first turn screw, it is ensured that the load-bearing capacity of the first turn screw is less than 70% of the total load.

[0023] Furthermore, the difference in length between the female and male threads of the first turn screw.

number

[0024] The beneficial effects of the above technical embodiment are as follows: By further reducing the upper limit of the difference l1 in length between the female and male threads of the first turn screw, it is ensured that the load-bearing capacity of the first turn screw is less than 50% of the total load.

[0025] Furthermore, the pitch difference ΔP(n1) between the female and male threads near the starting position is less than or equal to the pitch difference ΔP(n2) between the female and male threads farther from the starting position, i.e., n1 <n2、

number

[0026] The beneficial effects of the above technical embodiment are as follows: By unifying the cases where ΔP is constant and non-constant, the manufacturing of screws becomes easier when ΔP is constant, and when ΔP gradually increases with the number of screw turns, the load-bearing capacity of the first-turn screw is reduced, thereby reducing the stress concentration phenomenon in the first-turn screw. Comparative verification revealed that the load ratio of the first-turn screw is relatively large when ΔP is constant.

[0027] Furthermore, the total axial engagement gap δ = PS when the female and male threads are engaged. w -S n (S w : Tooth width in the middle diameter of a male screw; S n : In the case of the tooth width of the female thread in the middle diameter of the male thread,

number

[0028] The beneficial effect of the above technical embodiment is to prevent teeth grinding caused by insufficient axial clearance.

[0029] Furthermore, the total axial engagement gap δ = PS when the female and male threads are engaged. w -S n >0, i.e., P>S w +S n (S w : Tooth width in the middle diameter of a male screw; S n (The width of the female thread in the middle diameter of the male thread).

[0030] The beneficial effect of the above technical embodiment is to prevent the occurrence of tooth jamming due to the female screw tooth width being too large and the male screw clearance being insufficient. [Brief explanation of the drawing]

[0031] [Figure 1] This is a diagram of the threaded base male screw according to the present invention. [Figure 2] This is a diagram of the thread profile of the basic female screw according to the present invention. [Figure 3] This is a diagram of the female thread of the non-equal pitch locking screw connection pair of the present invention. [Figure 4] This is a schematic diagram illustrating the principle by which the tooth-meshing phenomenon does not occur in the female and male threads according to the present invention. [Figure 5] This diagram shows the relationship between the lengths of the female and male threads of the female and male threads according to the present invention when there is no load. [Figure 6] This is a schematic diagram of the start and end positions under load for the non-equal pitch locking screw connection pair of the present invention. [Figure 7] This is a schematic diagram of the forces acting on the male thread in the threaded region of the female and male threads of the present invention. [Figure 8] This is a general trend diagram of the F(n') curve in the present invention. [Figure 9] This is a schematic diagram of the effective length from the equivalent point of action to the support point for a conventional equal-pitch screw. [Figure 10] This is a schematic diagram of the effective length from the equivalent point of action to the support point for a non-equal pitch screw. [Figure 11] This is a schematic diagram showing a simplified representation of the male screw according to the present invention as an equivalent compression cylinder. [Figure 12] Figure 11 is a schematic diagram illustrating the average elongation and elongation on the cylindrical surface of a small cylinder. [Figure 13] This is a schematic diagram showing a simplified representation of the female screw according to the present invention as an equivalent compressed hollow cylindrical body. [Figure 14] Figure 13 is a schematic diagram illustrating the average compression and compression at the inner cylindrical surface of a small hollow cylinder. [Figure 15] This diagram shows the number of the male screw threads and the position of the load value. [Figure 16] This figure shows the load ratio at each thread of screws 1 to 6 under the same boundary conditions. [Figure 17] This is a curve diagram showing the change in the percentage of pre-tightening force as it vibrates under the same axial and lateral displacement loads applied to screws 1 through 6. [Figure 18] This is a curve diagram showing the change in the loosening rotation angle as it is affected by the vibration period under the same axial load and lateral displacement load applied to screws 1 to 6. [Figure 19] This figure shows the load ratio at each thread of screws 7 through 12 under the same boundary conditions. [Figure 20] This is a curve diagram showing the change in the percentage of pre-tightening force as it vibrates under the same axial load and lateral displacement load applied to screws 7 to 12. [Figure 21] This is a curve diagram showing the change in the loosening rotation angle as it is affected by the vibration period under the same axial load and lateral displacement load on screws 7 to 12. [Modes for carrying out the invention]

[0032] The features and performance of the present invention will be described in more detail below in relation to the examples.

[0033] The present invention sets a lower limit for the difference in length l between the n-turn female and male threads, so that the threaded area of ​​the female and male threads includes a primary load area near the starting position and a secondary load area near the ending position, thereby increasing the effective working length of the bolt, helping to share the forces acting due to the bending of the bolt rod, reducing the possibility of relative slippage between the female and male threads, and thereby achieving a better anti-loosening effect. At the same time, the present invention sets an upper limit for the difference in length l1 between the female and male threads of the first turn thread in order to prevent the axial load of the male thread from being borne by the first turn thread.

[0034] Example 1 of the non-equal pitch locking screw connection pair in the present invention:

[0035] An uneven-pitch locking screw connection pair includes a female thread and a male thread, where the pitch of the female thread is greater than the pitch of the male thread. Moreover, the pitches of both the female and male threads may be constant, or one may be a constant-pitch screw and the other a gradually-variable-pitch screw. In the case of a gradually-variable-pitch screw, the pitch is obtained by adjusting the pitch based on a base thread profile, and during adjustment, the tooth width of the screw is cut or increased, or a transition structure is added to the tooth root, based on the base thread profile. Here, the base thread profile is a standard screw such as a metric screw, MJ screw, trapezoidal screw, or arc screw, and a non-standard screw may also be used. The base male thread profile is a crest profile with a width of one standard pitch along the axial direction.

[0036] In one specific embodiment, the male thread is a fixed-pitch thread, and the male thread type is a basic male thread type. As shown in Figure 1, the pitch P1 of the male thread is equal to the basic male thread pitch P, the large diameter is d, the small diameter is d1, and the tooth width at the middle diameter d2 of the male thread is S w The yield strength of the male screw material is σ, and the elastic modulus of the male screw material is E w That is the case.

[0037] As shown in Figure 2, the basic female thread type has a pitch of P, a large diameter of D, a small diameter of D1, a number of female thread turns of n, and the elastic modulus of the female thread material is E. nThat is the case.

[0038] In one specific embodiment, the female thread is a gradually changing pitch thread, and the pitch of the female thread is increased by maintaining the base female thread profile and increasing the transition structure. As shown in Figure 3, the crest line of the female thread in a plane passing through the axis is formed by sequentially joining multiple base female thread profiles and transition structures G, and the longitudinal section of the transition structure G is a straight segment. The pitch of the female thread gradually increases along the axial direction. Since the pitch P2 of the female thread is the distance between any corresponding point MM′ of two adjacent base female thread profiles on the female thread profile line and the male thread threading region, the pitch P2 of the female thread is a non-constant value, and the pitch of the female thread is greater than the base thread pitch of the male thread, i.e., P2 > P. The pitch adjustment amount ΔP of the female thread (i.e., gradually changing pitch thread) is P2 - P. Since the pitch of the male thread P1 = P, the pitch adjustment amount ΔP of the gradually changing pitch thread is the pitch difference between the female thread and the male thread.

[0039] As shown in Figures 3 and 5, the tooth width of the female thread at the middle diameter d2 of the male thread is S n Therefore, the total axial engagement gap δ = P1 - S in the male thread's mid-diameter d2 between the female and male threads. w -S n Since >0, that is, P > S w +S n This prevents the problem of teeth jamming occurring due to insufficient clearance in the male thread when the tooth width of the female thread is too large.

[0040] Furthermore, as shown in Figure 4, when the pitches of the female and male threads are equal (refer to the diagram line where P2=P1, upper diagram in Figure 4), the lengths of both the female and male threads are L1. When the pitch of the female thread is greater than the pitch of the male thread (refer to the diagram line where P2>P1, lower diagram in Figure 4), the length of the female thread is L2, and the straight segments of the female thread gradually come into contact with the straight segments of the male thread. As can be easily seen from Figure 4, in the upper diagram, the pitches of the female and male threads are equal, they are joined on one side and not in contact on the other side, and the axial gap between the female and male threads is δ. In the lower diagram, the female and male threads are joined at the leftmost point, and because the pitch of the female thread is greater than the pitch of the male thread, the female and male threads start to separate from the joined position, and at the rightmost point, the other side of the female and male threads gradually approaches, and at this point the difference in length between the female and male threads is l. When l = δ, the rightmost points of the female and male threads make contact. When l > δ, an interference fit occurs between the female and male threads, which is disadvantageous for assembly. Therefore,

number

[0041] Furthermore, as shown in Figure 5, the length of the male thread with an arbitrary number of turns n′ starts from the starting position cross section Q.

number

number

number

number

[0042] For the sake of explanation, in this invention, a starting position and an ending position are provided, and a bolt 1 and a nut 2 are used as examples, as shown in Figures 5 and 6. Within the threaded area of ​​the female thread and the male thread, in this invention, one end face perpendicular to the axis of the female thread is defined as the starting position cross-section Q, and the other end face of the female thread is defined as the ending position cross-section Z (the conventionally considered support surface, i.e., the end face for crimping the connected member of the nut 2), and the direction from the starting position to the ending position is the same as the direction in which the male thread receives the rated axial load N.

[0043] When a female thread has n turns and is used in engagement with a male thread, a female thread with n turns will always be used in engagement with a male thread with n turns. If no load deformation occurs, starting from the starting position, any number of turns n'(

number

number

[0044] As shown in Figure 7, the axial load acting on the male thread by the female thread over an arbitrary number of turns n′, starting from the starting position of the threaded region of the female and male threads, is F(n′). Whether it is a conventional equal-pitch screw or a non-equal-pitch screw, if the axial load on the male thread is N, then when an n-turn screw is engaged and used, the resultant force on the n-turn thread is equal to the axial load N on the male thread.

number

[0045] In conventional equal-pitch screws, when a load is applied, the female and male threads of each turn come into contact simultaneously. Due to the cumulative effect of the load, the axial load on the male threads of a conventional equal-pitch screw is F(n′), which corresponds to curve 1 in Figure 8 (i.e., in the case of curve 1, a normal screw where the female and male threads are of equal pitch). The axial load F(n′) is large on the male threads near the end position and small on the male threads at the starting position. As shown in Figure 9, the equivalent point of application A where the female thread acts on the male thread is close to the cross-section Z at the end position and the support surface.

[0046] If the pitch of the female thread is greater than the pitch of the male thread, as the female thread is subjected to a load, the female thread and the male thread begin to come into contact at the starting position, and as the load increases, subsequent threads come into contact one by one. As a result, the axial load F(n') on the male thread increases at the starting position and decreases at the ending position, and as shown in Figure 10, the equivalent point of application B where the female thread acts on the male thread approaches the cross-section Q at the starting position.

[0047] The effective length from the equivalent point of action A to the support point O of a conventional equal-pitch screw is l A The effective length from the equivalent point of action B to the support point O of a non-equal pitch screw is l B Therefore, l A is, l B Smaller. In this case, the bolt can be considered a cantilever, where the bolt head position is one support position, and the cantilever of the equal-pitch thread is l A Therefore, a cantilever beam with unequal pitch screws is l B and l A ga l B For smaller displacement loads and the same displacement load (resulting in the same deflection in both cantilever beams), the deflection of the shorter rod of the cantilever beam is greater, meaning the force acting due to the rod deflection is also greater. Therefore, for the same axial load and coefficient of friction, equal-pitch screws exhibit greater bending action and are more prone to relative slippage between the female and male threads. In other words, the engagement method shown in Figure 9 is prone to relative slippage.

[0048] Therefore, in this embodiment, the difference in length between the n-turn female thread and the male thread

number

[0049] The specific calculation process is provided below. To simplify the calculation, the present invention assumes that all n turns mesh and simplifies the n-turn male screw into an equivalent compression cylinder. As shown in Figure 11, the two circular cross-sections of the equivalent compression cylinder are the starting position cross-section Q and the ending position cross-section Z, respectively, and the cross-sectional area of ​​the equivalent compression cylinder

number

[0050] Cut out a small cylinder at the position of any number of turns n' of the equivalent compression cylinder. The thickness of the small cylinder is dh = Pdn', and the axial load received by the lower cross-section of the small cylinder is [Number] According to Hooke's law, the average elongation of the small cylinder with thickness dh is [Number] can be obtained. Starting from the cross-section at the starting position, the total average elongation of the equivalent compression cylinder at any number of turns n' is [Number] .

[0051] As is clear from Fig. 12, since the surface load direction of the outer cylindrical surface of the small cylinder is opposite to the acting direction of the lower cross-section load N1 of the small cylinder, the elongation amount on the outer cylindrical surface of the small cylinder is smaller than the average elongation amount dl w1 Since the outer cylindrical surface of the equivalent compression cylinder is the male thread simplification region, the elongation amount of the outer cylindrical surface is the elongation amount dl w of the male thread, that is [Number] (0 < k1 < 1). For ease of analysis, assume that k1 is a constant value. Starting from the starting position, the total elongation amount [Number] .

[0052] As shown in Figure 13, to facilitate the analysis, the female thread in the threaded region of the male thread is simplified to an equivalent compressed hollow cylinder. The two circular cross-sections of the equivalent compressed hollow cylinder are the starting position cross-section Q and the ending position cross-section Z, respectively, and the cross-sectional area of ​​the equivalent compressed hollow cylinder is:

number

number

number

[0053] A small hollow cylinder is cut from an equivalent compressed hollow cylinder at an arbitrary height h=n′P, the thickness of the small hollow cylinder is dh=Pdn′, and the axial load on the lower cross section of the small hollow cylinder is:

number

number

[0054] As can be seen from Fig. 14, since the surface load direction of the inner cylindrical surface of the micro hollow cylinder is opposite to the acting direction of the lower cross-section load (axial load F N ) of the micro hollow cylinder, the compression amount on the inner cylindrical surface of the micro hollow cylinder is larger than the average compression amount dl n1 . Since the inner cylindrical surface of the equivalent hollow cylinder is the female thread simplification region, the compression amount of the inner cylindrical surface is the compression amount dl n of the female thread, and [Number] (1 < k2). To facilitate the analysis, assuming k2 is a constant value, starting from the starting position, the total compression amount [Number] of the female thread at any number of turns n' is as follows.

[0055] Furthermore, starting from the starting position, the change amount l'1 of the lengths of the female thread and the male thread at any number of turns n' is equal to the sum of the total elongation amount l w of the male thread and the total compression amount l n of the female thread. [Number]

[0056] After selecting the female thread and male thread materials, that is, the nut outer dimensions, since both E n and A2 are constant values, the ratio k3 of E w A1 to E n A2 is a constant. To facilitate the calculation, unify the elastic modulus and area in the formula to E w and A1, then [Number] To facilitate subsequent calculations, a comprehensive reference coefficient is used.

number

number

[0057] Generally, the sectional stress in an equivalent compression cylinder subjected to an axial load on a male screw is less than the yield strength σ of the material. That is,

number

number

[0058] Furthermore, if n'=n,

number

number

number

number

number

[0059] The above calculation and analysis process adopts equal load design, that is, based on the fact that the load received by each thread turn is equal. When the difference in length l between the female and male threads of n turns is smaller than the change in length l′1(n) of the female and male threads of n′ turns, that is, when l < l′1(n), the difference in length l between the female and male threads is not sufficient to provide the length l′1(n) required for the deformation of the female and male threads. The threads at the end position need to bear more load, meaning that the load at the end position is greater than the load at the start position and the main load area is closer to the end position. In this case, the change trend of F(n′) is similar to curve 2 in Figure 8. When l = l′1(n), the difference in length l between the female and male threads exactly provides the length l′1(n) required for the deformation of the female and male threads, and the change trend of F(n′) is similar to curve 3 in Figure 8. When l > l′1(n), the difference in length l between the female and male threads is sufficient to provide the length l′1(n) required for the deformation of the female and male threads, and the load between the female and male threads at the end position is smaller than the load at the start position. In this case, the change trend of F(n′) is similar to curve 4 in Figure 8.

[0060] When l > l′1(n), the main load area is close to the start position, and the secondary load area is close to the end position. Furthermore, considering the load coefficient k, the ratio k of the yield strength to the elastic modulus of the material c and the comprehensive reference coefficient K comprehensively, the range of the difference in length l between the female and male threads of n turns is

Number

Number

Number

[0061] Furthermore, the difference in length between the female and male threads of n turns

Number

Number

Number

Number

Number

Number

Number

Number

Number

number

[0062] Furthermore, when l = l'2(n), the difference l in length between the female and male threads provides exactly the length l'2(n) required for the deformation of the female and male threads, and the load is 0 for n turns of the female and male threads. The trend of change of F(n') resembles curve 5 in Figure 8. When l > l'2(n), the difference l in length between the female and male threads is sufficient to provide the length l'(n) required for the deformation of the female and male threads, and the load is 0 for less than n turns of the female and male threads. In this case, the trend of change of F(n') resembles curve 6 in Figure 8.

[0063] Furthermore,

number

number

number

number

[0064] In addition, when n=1, the change in length of the female and male threads in the first turn is:

number

number

number

number

[0065] Furthermore, in order to ensure that the load-bearing capacity of the first turn screw is less than 70% of the total load, the range of the difference l1 between the length of the female and male threads of the first turn screw is:

number

[0066] Furthermore, in order to ensure that the load-bearing capacity of the first turn screw is less than 50% of the total load, the range of the difference l1 between the length of the female and male threads of the first turn screw is:

number

[0067] The performance of the unequal-pitch anti-loosening screw connection pair of the present invention will be analyzed and verified below, referring to specific screw parameters and comparative tests.

[0068] Specific Embodiment 1:

[0069] The male thread is an arc male thread. The pitch of the arc male thread is constant and the pitch P1 = 6.35 mm, the major diameter d = 41.5 mm, the minor diameter d1 = 36.5 mm, and the tooth width S at the pitch diameter of the male thread w = 3.175 mm. The modulus of elasticity E of the male thread material is 206 GPa, the yield strength σ is 930 Mpa, and the axial load

Number

[0070] The female thread is a set of arc female threads. The pitch of the arc female thread is constant. The major diameter D of the female thread is 42.36 mm, the minor diameter D1 is 37.56 mm, and the tooth width S of the female thread at the pitch diameter of the male thread n = 2.3 mm. The number of turns of the female thread is n = 10 turns. Since the pitches of both the female thread and the male thread are constant, the pitch difference ΔP(n1) between the female thread and the male thread close to the starting position in this embodiment is equal to the pitch difference ΔP(n2) between the female thread and the male thread far from the starting position. That is, n1 < n2, ΔP(n1) = ΔP(n2).

[0071] Furthermore, the length L1 of the male thread for 10 turns is 63.5 mm.

[0072] Furthermore,

Number

[0073] Furthermore,

Number

[0074] Furthermore,

Number

[0075] Furthermore,

Number

[0076] Furthermore,

number

[0077] Furthermore, P1=6.35>S w +S n = 5.475 mm, δ = P1-S w -S n = 0.875 mm.

[0078] Table 1 shows the specific parameters for screws 1 to 6, along with the boundary determination conditions. Furthermore, the difference in length l between the female and male threads of 10-turn screws 1 to 6 is less than δ in all cases. A finite element model is constructed based on the screw parameters, and the load ratio at each thread is calculated under the same boundary conditions for screws 1 to 6, based on the positions of the thicker short horizontal lines shown in Figure 15, and is shown in Figure 16.

[0079] Table 1: Specific screw parameters of the screw in this application and the comparative screw. [Table 1]

[0080] Three-dimensional models of screws 1 to 6 are constructed, and as shown in Figures 17 and 18, the curves of change in pre-tightening force and loosening rotation angle with the vibration period due to the same axial load and lateral displacement load for each screw are calculated. In Figure 18, the "-" for the loosening rotation angle indicates the direction of rotation, and a negative value is obtained for counterclockwise rotation.

[0081] As can be seen from Table 1 and Figures 16-18, screw 1 and screw 2 are different.

number

[0082] Specific Embodiment 2:

[0083] The male screw is an arc male screw. The pitch of the arc male screw is constant and the pitch P1 = 6.35 mm, the major diameter d = 48.3 mm, the minor diameter d1 = 41.7 mm, and the tooth width S at the pitch diameter of the male screw w = 3.175 mm, the elastic modulus E of the male screw material = 206 Gpa, the yield strength σ = 930 Mpa, and the axial load [Number] is as follows.

[0084] The female thread is a set of arc-shaped female threads, and the pitch of the arc-shaped female thread is a gradually changing pitch, with the pitch difference ΔP increasing as the number of turns n' of the thread increases. The large diameter of the female thread D = 49.6 mm, the small diameter D1 = 44 mm, and the thread height H = 2.8. The tooth width S of the female thread at the medium diameter of the male thread. n The diameter is 2.2 mm, and the number of turns of the female thread is n = 10 turns.

[0085] Furthermore, the length L1 of the 10-turn male screw is 63.5 mm.

[0086] Furthermore,

number

[0087] Furthermore,

number

[0088] Furthermore,

number

[0089] Furthermore,

number

[0090] Furthermore,

number

[0091] Furthermore, P1=6.35>S w +S n = 5.475 mm, δ = P1-S w -S n = 0.875 mm.

[0092] In this embodiment, all screws start from the starting position. Among them, screws 7 to 12 have a female thread with an arbitrary number of turns n′ and a male thread with a length difference l′, which is given by the equation.

number

[0093] Table 2: Specific screw parameters for screws 7 to 12 [Table 2]

[0094] Referring to the positions of the thick, short horizontal lines shown in Figure 15, the load ratio at each thread of screws 7 to 12 is calculated under the same boundary conditions, as shown in Figure 19. A three-dimensional model of screws 7 to 12 is constructed, and the curves of change in pre-tightening force and loosening rotation angle with the vibration period due to the same axial load and lateral displacement load for each screw are calculated, as shown in Figures 20 and 21. Note that the "-" in the loosening rotation angle in Figure 21 indicates the direction of rotation, and a negative value is obtained in the case of counterclockwise rotation.

[0095] Furthermore, the differences between Specific Embodiment 2 and Specific Embodiment 1 are as follows. In Specific Embodiment 2, starting from the starting position, the pitch difference ΔP between the female and male threads increases with increasing number of turns n′ of the screw, and the total load on the axial cross-section of the male thread from the starting position increases with increasing number of turns n′ of the screw. Taking a screw with two turns from the front as an example, if the pitch difference between the female and male threads is constant, the total deformation of the first turn screw is equal to the pitch difference between the female and male threads. Because the minute deformation that occurs in the female and male threads of the first turn accumulates in the second turn screw, the effective gap of the second turn screw is smaller than the pitch difference between the female and male threads. Consequently, the total deformation of the second turn screw is smaller than one pitch difference. In other words, the total load of the first turn screw is greater than the load of the second turn. If the pitch of the female and male threads increases with the number of turns of the screw, the total load of the second turn screw can be increased. That is, it prevents the load ratio between the first and second turn screws from being too large. This is also evident from a comparison between Figure 16 and Figure 19. Therefore, when obtaining a large difference in length between the female and male threads, or when obtaining the same difference in length between the female and male threads, the variable-pitch screw in specific embodiment 2 can reduce the total load of the first turn screw and improve the load-bearing safety of the screw.

[0096] In another embodiment, the total average elongation amount l of the equivalent compressed cylinder at any number of turns n′ w1 Using this as is, the total elongation amount l of a male screw with any number of turns n' w It can also represent the total average compression amount l of an equivalent compressed hollow cylinder over any number of turns n′. n1 Using this as is, the total compression amount l of the female thread with any number of turns n′ n It can also represent this.

[0097] In other embodiments, if the simplification method is different, the simplified results of the equations for the changes in the lengths of the female and male threads, l'1 and l'2, may differ as needed.

[0098] In other embodiments, k, k cThe specific values ​​of b1 and b2 obtained will differ depending on the specific value of K.

[0099] In another embodiment, the gap in the middle diameter of the male thread is the tooth width S of the female thread. n Equivalent to, namely PS w =S n .

[0100] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. The scope of patent protection of the present invention shall be in accordance with the claims, and all equivalent structural modifications made using the description and drawings of the present invention shall be included within the scope of protection of the present invention.

[0101] (Note) (Note 1) A non-unequal pitch lock screw connection pair, comprising a female thread and a male thread, wherein the pitch of the female thread is greater than the pitch of the male thread, The difference in length between the n-turn female thread and the male thread.

number

number

number

[0102] (Appendix 2) The non-uniform pitch anti-loosening screw connection pair described in Appendix 1, where k, k c Considering comprehensively the possible values of K

Number

Number

[0103] (Appendix 3) The non-uniform pitch anti-loosening screw connection pair described in Appendix 1 or 2, where If the screwing area of the female screw and the male screw starts from the starting position and the axial load of the male screw thread at an arbitrary number of turns n' is F(n'),

Number

Number

Number

Number

Number

Number

number

number

number

number

number

number

number

number

[0104] (Note 4) Non-equal pitch locking screw connection pair as described in Appendix 1 or 2, wherein the difference in length between the n-turn female thread and the male thread.

number

[0105] (Note 5) The non-equal pitch locking screw connection pair described in Appendix 4, k, k c , taking into account all possible values ​​of K

number

number

[0106] (Note 6) A non-equal pitch locking screw connection pair as described in Appendix 4, If the threaded region of the female and male threads starts from the starting position, and the axial load on the male thread at an arbitrary number of turns n' is F(n'),

number

number

number

number

Number

Number

Number

Number

Number

Number

Number

[0107] (Appendix 7) The non-uniform pitch anti-loosening screw connection pair according to Appendix 1 or 2, wherein the difference in length between the female and male threads of the first turn screw

Number

[0108] (Appendix 8) The non-equal pitch locking screw connection pair described in Appendix 7, wherein the difference in length between the female thread and the male thread of the first turn screw.

number

[0109] (Note 9) The non-equal pitch locking screw connection pair described in Appendix 8, wherein the difference in length between the female thread and the male thread of the first turn screw.

number

[0110] (Note 10) In the non-equal pitch lock screw connection pair described in Appendix 1 or 2, the pitch difference ΔP(n1) between the female and male threads near the starting position is less than or equal to the pitch difference ΔP(n2) between the female and male threads farther from the starting position, i.e., n1 <n2、

number

[0111] (Note 11) A non-equal pitch locking screw connection pair as described in Appendix 1 or 2, wherein the total axial engagement gap δ = PS when the female and male threads are engaged. w -S n (S w : Tooth width in the middle diameter of a male screw; S n : In the case of the tooth width of the female thread in the middle diameter of the male thread,

number

[0112] (Note 12) A non-equal pitch locking screw connection pair as described in Appendix 1 or 2, wherein the total axial engagement gap δ = PS when the female and male threads are engaged. w -S n >0, i.e., P>S w +S n (S w : Tooth width in the middle diameter of a male screw; S n A non-unequal pitch locking screw connector pair characterized by having the tooth width of the female thread in the middle diameter of the male thread.

Claims

1. A non-unequal pitch lock screw connection pair, comprising a female thread and a male thread, wherein the pitch of the female thread is greater than the pitch of the male thread, The difference in length between the female and male threads of an n-turn screw. [Math 1] A non-equal pitch locking screw connection pair characterized in that the threaded region of the female and male threads includes a primary load region near the starting position and a secondary load region near the ending position. Here, b １ : General reference boundary 1; P: Pitch of the male screw; n: Total number of turns in the threaded area of ​​the female and male threads; k: Load coefficient where 0 < k < 1; [Math 2] ； σ: Yield strength of the male screw material; E ｗ : Elastic modulus of the male screw material; K: This is the overall reference coefficient. [Math 3] 。

2. A non-equal pitch locking screw connection pair according to claim 1, wherein k, k ｃ , taking into account all possible values ​​of K [Math 4] If we limit it to that, [Math 5] A non-equal pitch locking screw connection pair characterized by the following:

3. A non-equal pitch locking screw connection pair according to claim 1 or 2, If the threaded region of the female and male threads starts from the starting position, and the axial load on the male thread at an arbitrary number of turns n' is F(n'), [Math 6] （ [Number 7] (N: Axial load on the male screw) The load on the threads in each turn is equal, that is, [Number 8] In this case, the change in length l' between the female and male threads for any number of turns n'. １ The total elongation of the male screw is l ｗ and the total compression amount of the female thread l ｎ It is equal to the sum of, [Number 9] (k １ , k ２ : a constant value; [Number 10] : Tensile stress area of male screw; E ｎ : Young's modulus of female screw material, [Math 11] (Stress cross-sectional area of ​​the female thread) E ｗ A １ and E ｎ A ２ The ratio of k ３ and [Math 12] toshi, l' １ The formula [Number 13] Simplified to, after that [Number 14] Based on, [Number 15] Obtained, If n' = n, [Number 16] 、 [Number 17] Using [Number 18] Obtained, The difference in length between the female and male threads of an n-turn thread is l > l'. １ In case (n), l is the length l' required for deformation of the female and male threads. １ (n) is provided in sufficient quantities, [Number 19] A non-equal pitch locking screw connection pair characterized by the ability to obtain [the desired result].

4. A non-equal pitch locking screw connection pair according to claim 1 or 2, wherein the difference in length between the n-turn female thread and the male thread [Number 20] (b ２ A non-equal pitch locking screw connection pair characterized by being a comprehensive reference boundary 2).

5. A non-equal pitch locking screw connection pair according to claim 4, wherein k, k ｃ , taking into account all possible values ​​of K [Math 21] If we limit it to that, [Number 22] A non-equal pitch locking screw connection pair characterized by the following:

6. A non-equal pitch locking screw connection pair according to claim 4, If the threaded region of the female and male threads starts from the starting position, and the axial load on the male thread at an arbitrary number of turns n' is F(n'), [Number 23] （ [Number 24] (N: Axial load on the male screw) [Number 25] That is, F(n') decreases with the number of turns of the screw within the range of 0 to n turns, the main load area gets closer to the starting position, and at the point where n' = n, F(n') = 0, and at that point, there is no compression between the female and male threads. At this time, the change in length l' between the female and male threads for any number of turns n'. ２ The total elongation of the male screw is l ｗ and the total compression amount of the female thread l ｎ It is equal to the sum of, [Number 26] (Here, k １ , k ２ : a constant value; [Number 27] : Stress cross-sectional area of ​​the male screw; E ｎ : Elastic modulus of female thread material; [Number 28] (Stress cross-sectional area of ​​the female thread) E ｗ A １ and E ｎ A ２ The ratio of k ３ and [Number 29] And then [Number 30] Based on this, simultaneously n' = n, [Number 31] In the case of l' ２ The formula [Number 32] It can be simplified to this, The difference in length between the female and male threads of an n-turn thread is l > l'. ２ In case (n), l is the length l' required for deformation of the female and male threads. ２ (n) is provided in sufficient quantities, [Number 33] A non-equal pitch locking screw connection pair characterized by the ability to obtain [the desired result].

7. A non-equal pitch locking screw connection pair according to claim 1 or 2, wherein the difference in length between the female thread and the male thread of the first turn screw [Number 34] (b ３ A non-equal pitch locking screw connection pair characterized by being a comprehensive reference boundary 3).

8. A non-equal pitch locking screw connection pair according to claim 7, wherein the difference in length between the female thread and the male thread of the first turn screw [Number 35] (b ４ A non-equal pitch locking screw connection pair characterized by being a comprehensive reference boundary 4).

9. A non-equal pitch locking screw connection pair according to claim 8, wherein the difference in length between the female thread and the male thread of the first turn screw [Number 36] (b ５ A non-equal pitch locking screw connection pair characterized by being a comprehensive reference boundary 5).

10. A non-equal pitch locking screw connection pair according to claim 1 or 2, wherein the pitch difference ΔP(n) between the female thread and the male thread near the starting position. １ ) is the pitch difference ΔP(n) between the female and male threads furthest from the starting position. ２ ) is less than or equal to n １ <n ２ , [Number 37] A non-equal pitch locking screw connection pair characterized by the following:

11. A non-equal pitch locking screw connection pair according to claim 1 or 2, wherein the total axial engagement gap δ = P - S when the female and male threads are engaged. ｗ -S ｎ (S ｗ : Tooth width in the middle diameter of the male screw; S ｎ : In the case of the tooth width of the female thread in the middle diameter of the male thread, [Number 38] A non-equal pitch locking screw connection pair characterized by the following:

12. A non-equal pitch locking screw connection pair according to claim 1 or 2, wherein the total axial engagement gap δ = P - S when the female and male threads are engaged. ｗ -S ｎ > 0, i.e., P > S ｗ +S ｎ (S ｗ : Tooth width in the middle diameter of the male screw; S ｎ A non-equal pitch locking screw connector pair characterized by having the tooth width of the female thread at the medium diameter of the male thread.

Images