End thread fastener

Abstract

The utility model discloses an ending thread fastener which comprises a polished rod part and thread parts located at the two ends of the polished rod part, the diameter of the polished rod part is smaller than that of the thread parts, a reducing part is connected between the polished rod part and the thread parts, and a thread ending area is arranged at the end, close to the thread parts, of the reducing part. The thread structure of the thread ending area and the thread structure of the thread part are connected end to end to form an integrated structure, the ending transition end face of the thread ending area in the thread trend is a straight ending end face, and an arc-shaped face is arranged between the polished rod part and the thread ending area and the straight ending end face and between the polished rod part and the thread ending area and the straight ending end face. The edge of the thread part and the edge of the thread ending area are each of a large-arc chamfer structure, compared with a common ending mode, stress concentration can be reduced, the stress distribution of threads is uniform, through tests, the improved thread ending can bear cyclic loading of 5 million times or above in a fatigue test, and the fatigue resistance of the thread structure can be improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to thread fastener technical field especially is related to a kind of end thread fastener. BACKGROUND

[0002] Thread fastener is a kind of metal fastening device with thread, mainly including bolt, nut and screw, etc., they are achieved by the interlocking of thread and the fastening and connection of component, these fasteners are widely used in automobile manufacturing, construction engineering, furniture manufacturing, electronic appliances and machinery manufacturing etc. many fields, with its high strength, reliability and reusable characteristics, ensure the stability and safety of connection, wherein, GB / T192《General Thread Basic Profile》And GB / T197《General Thread Tolerance》Regulation thread basic profile meets the requirements, wherein, the minimum circular arc radius of external thread should not be less than 0.125P (P is pitch), and the maximum is 0.14434P (P is pitch);

[0003] Chinese patent announcement No. CN217633344U discloses an end thread fastener, belonging to the technical field of fastening components, which comprises a threaded portion and a smooth rod portion. The straight line where the threaded portion is located is provided with an end transition section between the smooth rod portion. The end transition section has an end circular arc radius R of 0.165P < R < 0.2P, and the length L of the end transition section along the axial direction of the thread fastener is L < 1.5P. In the above-mentioned technology, the profile end is unnatural, the processing difficulty is large, which leads to local stress concentration and easy breakage of the thread structure. Therefore, the utility model discloses an end thread fastener to solve the above-mentioned problems. UTILITY MODEL CONTENTS

[0004] The utility model aims to provide an end thread fastener to solve the problem of unnatural thread fastener profile end in the background art, large processing difficulty, local stress concentration and easy breakage of thread structure.

[0005] To achieve the above-mentioned purpose, the utility model solves the technical problems in the following scheme: an end thread fastener, comprising a smooth rod portion and threaded portions located at both ends of the smooth rod portion. The diameter of the smooth rod portion is smaller than that of the threaded portions. A variable diameter portion is connected between the smooth rod portion and the threaded portions. One end of the variable diameter portion near the threaded portion is provided with a thread end area. The thread structure of the thread end area is connected with the thread structure of the threaded portion as an integral structure. The end transition surface of the thread end area along the thread direction is a flat end surface. An arc surface is provided between the smooth rod portion, the thread end area and the flat end surface. The arc surface gradually tends to be flush with the flat end surface along the thread extension path. The flat end surface gradually tends to be flush with the smooth rod portion along the thread extension path.

[0006] As a further scheme of the utility model, the pitch of the threaded part is P, the radius of the threaded part is R, and 0.15P < R < 0.18P.

[0007] As a further scheme of the utility model, the angle between the straight line where the variable-diameter part is located and the central axis of the polished rod part is S, and 0° < S < 3°.

[0008] As a further scheme of the utility model, the threaded part is provided with a chamfered surface at the edge of one end away from the polished rod part.

[0009] As a further scheme of the utility model, the threaded part and the edge of the threaded end area are provided with chamfered structures.

[0010] As a further scheme of the utility model, the length of the threaded part is at least 5 times the length of the threaded end area.

[0011] Compared with the prior art, the utility model has the beneficial effects that:

[0012] 1. The utility model relates to a threaded end fastener, wherein the edges of the threaded part and the threaded end area are provided with large-arc chamfered structures, compared with the ordinary end mode, stress concentration can be reduced, the stress distribution of the thread is uniform, through test, the improved threaded end can bear more than 5 million times of cyclic loading in fatigue test, and the fatigue resistance of the threaded structure can be improved.

[0013] 2. The utility model relates to a threaded end fastener, wherein the end transition end face of the threaded end area along the thread direction is provided with a flat surface, and the arc-shaped surfaces on the two sides of the flat end face are connected with the polished rod part and the threaded end area, while the structural strength is ensured, the technical difficulty of the tooth-shaped end is reduced, and the threaded end is easy to process and manufacture.

[0014] 3. The utility model relates to a threaded end fastener, wherein the straight line where the threaded part is located and the polished rod part are connected through the variable-diameter part of the conical structure, and the threaded part, the polished rod part and the variable-diameter part are integrally formed, the stress distribution of the bolt can be improved, and the overall fatigue resistance of the bolt is improved. DRAWINGS

[0015] The utility model will be further described in connection with the drawings and embodiments:

[0016] Figure 1 It is a sectional view of the threaded end fastener.

[0017] Figure 2 It is an enlarged view of the structure at A in the threaded end fastener. Figure 1

[0018] ​In the drawings, the components represented by each reference numeral are listed as follows: 1, polished rod part; 2, threaded part; 21, chamfered surface; 3, variable diameter part; 4, threaded end zone; 41, flat end surface; 42, arc surface. DETAILED DESCRIPTION

[0019] The utility model will be further described below in combination with examples.

[0020] Please refer to Figures 1-2 The utility model provides a threaded end fastener, including polished rod part 1 and threaded part 2 at both ends of polished rod part 1, the diameter of polished rod part 1 is less than the diameter of threaded part 2, the variable diameter part 3 is connected between polished rod part 1 and threaded part 2, the included angle between the variable diameter part 3 and the central axis of polished rod part 1 is S, and 0 ° < S < 3 °.

[0021] Further, the variable diameter part 3 forms a trapezoidal cross section, and the included angle between the straight line where the inclined side of the trapezoidal cross section is located and the central axis of the polished rod part 1 is 0° to 3°. This structure design makes the transition from the polished rod part 1 to the threaded part 2 smoother. In terms of stress transmission, the smaller included angle S makes the taper change of the variable diameter part 3 gentle, which can effectively disperse stress and reduce stress concentration phenomenon, thereby improving the durability and reliability of the fastener. At the same time, the gentle taper structure reduces the precision requirement of tool angle adjustment in the machining process, reduces the machining difficulty, improves the production efficiency, reduces the manufacturing cost, and under the action of load, this structure can better maintain stability, ensuring the improvement of the overall performance of the fastener.

[0022] Specifically, the included angle S between the straight line where the variable diameter part 3 is located and the polished rod part 1 is controlled between 0° and 3°, which can ensure that the transition from the polished rod part 1 to the threaded part 2 is smooth. This smooth transition helps to reduce stress concentration, improve the durability and reliability of the fastener, and the smaller included angle S means that the taper change of the variable diameter part 3 is relatively gentle, which can reduce the machining difficulty, make the production process more efficient, reduce the manufacturing cost, and improve its stability under load. Compared with the traditional variable diameter part with a larger included angle (such as 5°-10°), the utility model controls the included angle S between 0° and 3°. Through experimental testing, the stress concentration coefficient is reduced by 10%, the fatigue life is improved by 30%, the machining time of the variable diameter part designed with this included angle range is shortened by 10% under the same production conditions, the production cost is reduced by 5 yuan / piece, and the deformation amount is reduced by 0.5 mm when bearing 1000N load.

[0023] Further, the threaded end zone 4 is provided at one end of the variable diameter part 3 close to the threaded part 2, the threaded structure of the threaded end zone 4 and the threaded structure of the threaded part 2 are connected as an integral structure, the pitch of the threaded part 2 is P, the radius of the threaded part 2 is R, and 0.15P < R < 0.18P.

[0024] Specifically, the proper radius of the arc helps to reduce the stress concentration of the threaded portion 2, thereby improving the fatigue strength of the threaded fastener and prolonging its service life.

[0025] Further, the length of the threaded portion 2 is at least 5 times the length of the threaded end portion 4.

[0026] Specifically, the longer threaded portion 2 means that the threaded end portion 4 accounts for a smaller proportion of the entire threaded fastener, which can reduce fatigue failure caused by stress concentration at the threaded end and prolong the service life of the fastener, so that the stress is more evenly distributed on the threaded fastener.

[0027] Further, the edges of the threaded portion 2 and the threaded end portion 4 are provided with chamfer structures.

[0028] Specifically, by chamfering the edges of the threaded portion 2 and the threaded end portion 4, the stress distribution can be more uniform, and the durability of the threaded fastener can be improved.

[0029] Further, the threaded portion 2 is provided with a chamfer surface 21 at the edge of the end away from the light rod portion 1.

[0030] Specifically, the chamfer surface 21 can make the threaded fastener more smooth during assembly, reduce friction and resistance during assembly, and especially in the case of close fit, the chamfer can avoid damage during installation.

[0031] Further, the end transition surface of the threaded end portion 4 along the thread direction is a flat end surface 41, the light rod portion 1 and the threaded end portion 4 are provided with an arc surface 42 between the flat end surface 41, the arc surface 42 gradually tends to be flush with the flat end surface 41 along the thread extension path, and the flat end surface 41 gradually tends to be flush with the light rod portion 1 along the thread extension path.

[0032] Specifically, the maximum radius of the arc surface 42 is the same as the finish arc radius of the thread finish area 4, and the combination of the straight finish end face 41 and the arc surface 42 simplifies the machining process because they provide a clear geometric reference, making the manufacturing process more accurate and efficient, the arc surface 42 can reduce friction and wear during assembly, making it easier to screw in and out of the threaded fastener, improving assembly convenience, and the arc surface 42 achieves a smooth transition, reducing stress concentration, when machining and manufacturing, the combination of the straight finish end face 41 and the arc surface 42 forms a unique geometry, which can be directly used by programmers to determine the tool movement trajectory without complex calculations and adjustments, greatly improving machining accuracy and efficiency, compared to traditional complex-shaped thread design, the machining time can be shortened by about 6%, and finally the thread finish area 4 is formed by rolling the thread finish area 4 using a rolling die.

[0033] Working principle:

[0034] In use, the edges of the threaded portion 2 and the thread finish area 4 are chamfered with large circular arcs, which can reduce stress concentration and make the stress distribution of the thread uniform compared to ordinary finish methods, and the improved thread finish fatigue test can pass more than 5 million times, which can improve the fatigue strength of the thread structure; the finish transition end face of the thread finish area 4 along the thread direction is a straight face, and the arc surfaces 42 on both sides of the straight finish end face 41 connect the straight rod portion 1 and the thread finish area 4, which reduces the technical difficulty of the tooth profile finish while ensuring the structural strength and is easy to process and manufacture; the straight line where the threaded portion 2 is located is connected to the straight rod portion 1 through the tapered variable diameter portion 3, and the threaded portion 2, the straight rod portion 1 and the variable diameter portion 3 are integrally formed, which can improve the stress distribution of the bolt and improve the overall fatigue strength.

Claims

1. A finished threaded fastener, characterized by, The application relates to a light rod part (1) and a threaded part (2) located at both ends of the light rod part (1), the diameter of the light rod part (1) is smaller than the diameter of the threaded part (2), a variable-diameter part (3) is connected between the light rod part (1) and the threaded part (2), a thread tailing area (4) is arranged at one end of the variable-diameter part (3) close to the threaded part (2), the thread structure of the thread tailing area (4) is connected with the thread structure of the threaded part (2) in a head-tail integrated structure, wherein a flat tailing end surface (41) is arranged at the tailing transition end surface of the thread tailing area (4) along the thread direction, an arc surface (42) is arranged between the light rod part (1), the thread tailing area (4) and the flat tailing end surface (41), the arc surface (42) gradually tends to be flush with the flat tailing end surface (41) along the thread extension path, and the flat tailing end surface (41) gradually tends to be flush with the light rod part (1) along the thread extension path.

2. A finishing thread fastener according to claim 1, wherein: The pitch of the threaded part (2) is P, the radius of the threaded part (2) is R, and 0.15P < R < 0.18P.

3. A finishing thread fastener according to claim 1, wherein: The included angle between the straight line where the variable-diameter part (3) is located and the central axis of the light rod part (1) is S, and 0 < S < 3.

4. A finishing thread fastener according to claim 1, wherein: A chamfer surface (21) is arranged at the edge of one end of the threaded part (2) away from the light rod part (1).

5. A finishing thread fastener according to claim 1, wherein: The edge of the threaded part (2) and the thread tailing area (4) is provided with a chamfer structure.

6. A finishing thread fastener according to claim 1, wherein: The length of the threaded part (2) is at least 5 times the length of the thread tailing area (4).

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