阅读说明：本技术 一种非平行安装端面的螺栓防松结构 (Bolt anti-loosening structure with non-parallel mounting end faces ) 是由 孙清超 袁志伟 郭钢毅 赵斌斌 孙克鹏 于 2020-07-30 设计创作，主要内容包括：本发明属于螺栓连接结构防松设计领域,提供了一种非平行安装端面的螺栓防松结构,包括上被连接件、下被连接件、螺栓和螺母；螺栓穿过上被连接件和下被连接件,其两端与螺母配合,螺栓与螺母夹持上被连接件和下被连接件,上被连接件表面加工有非平行安装端面；当螺栓节点受到横向振动载荷时,所受到的额外接触摩擦力会提高螺栓防松结构的防松性能。该防松结构无需引入其他零件,区别于传统的摩擦防松、机械防松和永久防松方法,只需要改变螺栓安装端面的倾斜角度就能实现螺栓连接结构防松,不改变螺栓和螺母的结构,拆卸方便,便于重复使用且拧紧力矩适中,应用范围广。本防松结构可以与现有的其他螺栓连接防松方法配合使用,增强防松效果。(The invention belongs to the field of anti-loose design of bolt connection structures, and provides a bolt anti-loose structure with non-parallel installation end surfaces, which comprises an upper connected piece, a lower connected piece, a bolt and a nut; the bolt penetrates through the upper connected piece and the lower connected piece, two ends of the bolt are matched with the nut, the bolt and the nut clamp the upper connected piece and the lower connected piece, and the surface of the upper connected piece is provided with a non-parallel mounting end surface; when the bolt node receives lateral vibration load, the additional contact friction that receives can improve bolt anti loosening structure's locking performance. The anti-loosening structure does not need to introduce other parts, is different from the traditional friction anti-loosening method, the mechanical anti-loosening method and the permanent anti-loosening method, can realize the anti-loosening of the bolt connecting structure only by changing the inclination angle of the installation end surface of the bolt, does not change the structures of the bolt and the nut, is convenient to disassemble, convenient to reuse, moderate in tightening torque and wide in application range. The anti-loosening structure can be matched with other existing anti-loosening methods for bolt connection, and the anti-loosening effect is enhanced.)

1. A bolt anti-loosening structure with non-parallel mounting end faces is characterized by comprising an upper connected piece (1), a lower connected piece (2), a bolt (3) and a nut (4); the bolt (3) penetrates through the upper connected piece (1) and the lower connected piece (2), two ends of the bolt are matched with the nut (4), the bolt (3) and the nut (4) clamp the upper connected piece (1) and the lower connected piece (2), and non-parallel mounting end faces are machined on the surface of the upper connected piece (1); when bolt (3) node received lateral vibration load, the extra contact friction that receives can improve bolt anti loosening structure's locking performance, realizes the locking effect of structure.

2. The bolt looseness prevention structure of claim 1, wherein a limit value of a geometric inclination angle θ of said non-parallel mounting end surface is:

wherein, the deformation of the connected piece

p_GThe allowable maximum stress of the material, K is a safety coefficient, F is an initial value of the pretightening force of the bolt connecting structure, A (z) is the area of a pressed layer of a connected piece area, E is the elastic modulus of the connected piece, and l is the actual clamping length.

3. The bolt looseness prevention structure according to claim 1 or 2, wherein the non-parallel mounting end face is a non-parallel end face, a countersunk non-parallel end face or a boss non-parallel end face.

4. Bolt looseness prevention structure according to claim 1 or 2, wherein said non-parallel mounting end face is machined on a contact surface of the nut (4) and the attached member.

5. The bolt looseness prevention structure according to claim 3, wherein said non-parallel mounting end face is machined at a contact surface of the nut (4) and the connected member.

6. The bolt looseness prevention structure of claim 1, 2 or 5, wherein said non-parallel mounting end face is inclined from a center to an edge of the connected member.

7. The bolt looseness prevention structure of claim 3, wherein said non-parallel mounting end surface is inclined from a center to an edge of the connected member.

8. The bolt looseness prevention structure of claim 4, wherein said non-parallel mounting end surface is inclined from a center to an edge of the connected member.

9. The bolt looseness prevention structure according to claim 1, 2, 5, 7 or 8, wherein an actual clamping length of said upper and lower connected members (1, 2) ranges between 40cm and 55 cm.

10. The bolt looseness prevention structure according to claim 6, wherein an actual clamping length of the upper and lower connected members (1, 2) ranges between 40cm and 55 cm.

Technical Field

The invention belongs to the field of anti-loosening design of bolt connection structures, and particularly relates to a bolt anti-loosening structure with non-parallel mounting end faces.

Background

The bolt connection has the advantages of simple installation, convenient disassembly, low cost, high interchangeability and the like, and is one of the most widely applied connection modes in the fields of machinery, construction, traffic, aviation, aerospace, ships, furniture and the like. However, during the service of the bolt connection, the bolt connection is often subjected to external loads such as vibration, impact, periodic temperature change and the like, so that the thread pretightening force gradually declines along with the increase of the service time. The insufficient pretightening force not only causes the threaded connection to lose the original functions of fastening, sealing and the like, but also can reduce the fatigue life of the connecting piece, cause the fracture of the connecting piece and even cause serious safety accidents.

The anti-loosening measures of bolt connection used in the current engineering are divided into three categories of friction anti-loosening, mechanical anti-loosening and permanent anti-loosening according to different anti-loosening working principles.

1. Friction anti-loose

Friction locking is the most widely used locking method, which generates a positive pressure between the thread pairs that is not changed by an external force, so as to generate a friction force that can prevent the thread pairs from rotating relatively. This positive pressure can be achieved by axial or simultaneous two-way compression of the thread pairs.

However, this method is not very reliable and is therefore usually only used in places where the requirements for locking are not strict. Common forms of friction are the use of spring washers and the use of double nuts.

2. Mechanical anti-loosening device

The mechanical anti-loosening is realized by connecting a nut and a bolt into a whole by using a mechanical device and directly limiting the relative rotation of a thread pair.

But this method causes inconvenience in later disassembly. Such as the use of cotter pins, tandem wires, and stop washers.

3. Permanent anti-loose

The permanent anti-loosening is realized by fixing a nut on a bolt or a connected piece by using methods such as tack welding, spot riveting and the like, and a screw can be fixed on the connected piece.

This method is reliable, but the coupling cannot be reused after disassembly.

At present, the anti-loosening measures cannot completely meet the requirements of compact structure, simple assembly and repeated detachability. In view of the above situation, the present invention provides a method for realizing looseness prevention of a bolt connection structure by using non-parallel mounting end faces.

Disclosure of Invention

The bolt anti-loosening structure of the non-parallel mounting end face is different from the traditional friction anti-loosening, mechanical anti-loosening and permanent anti-loosening methods, the anti-loosening of the bolt connecting structure can be completed only by changing the inclination angle of the mounting end face, no additional part is needed in the method, and the requirements of compact structure, simple assembly and repeated detachability are met.

The technical scheme of the invention is as follows:

a bolt anti-loosening structure with non-parallel mounting end faces comprises an upper connected piece 1, a lower connected piece 2, a bolt 3 and a nut 4; the bolt 3 penetrates through the upper connected piece 1 and the lower connected piece 2, two ends of the bolt are matched with the nut 4, the bolt 3 and the nut 4 clamp the upper connected piece 1 and the lower connected piece 2, and the surface of the upper connected piece 1 is provided with a non-parallel mounting end surface; when the node 3 of the bolt is subjected to transverse vibration load, the additional contact friction force can improve the anti-loosening performance of the bolt anti-loosening structure, and the anti-loosening effect of the structure is realized;

the limit value of the geometric inclination angle theta of the non-parallel mounting end surface is as follows:

wherein, the deformation of the upper connected piece 1

p_GThe allowable maximum stress of the material, K is a safety coefficient, F is an initial value of the pretightening force of the bolt connecting structure, A (z) is the area of a pressed layer of a connected piece area, E is the elastic modulus of the connected piece, and l is the actual clamping length.

The non-parallel mounting end faces are machined on the contact surfaces of the nut 4 and the connected piece.

The non-parallel mounting end faces are inclined from the center to the edge of the connected piece.

The non-parallel mounting end face is a non-parallel end face, a countersunk non-parallel end face or a boss non-parallel end face.

The actual clamping length of the upper and lower connected members 1 and 2 is in the range of 40cm to 55 cm.

The invention has the beneficial effects that: according to the bolt anti-loosening structure with the non-parallel mounting end surfaces, additional contact pressure and contact friction torque are introduced at the thread contact positions through the contact of the non-parallel end surfaces and the lower surface of the nut, and when a bolt node is subjected to transverse vibration load, the additional contact friction force can improve the anti-loosening performance of the bolt connecting structure. The anti-loosening structure does not need to introduce other parts, is different from the traditional friction anti-loosening method, the mechanical anti-loosening method and the permanent anti-loosening method, can realize the anti-loosening of the bolt connecting structure only by changing the inclination angle of the installation end surface of the bolt, does not change the structures of the bolt and the nut, is convenient to disassemble, convenient to reuse, moderate in tightening torque and wide in application range. The anti-loosening structure can be matched with other existing anti-loosening methods for bolt connection, and the anti-loosening effect is enhanced.

Drawings

Fig. 1 is a schematic diagram of a bolt anti-loosening structure.

Fig. 2 is a schematic view of a conventional bolt connection structure.

Fig. 3 is a schematic diagram of a bolt anti-loosening structure with common non-parallel end faces.

Fig. 4 is a schematic diagram of a bolt anti-loosening structure with countersunk non-parallel end faces.

Fig. 5 is a schematic diagram of a bolt anti-loosening structure of a boss non-parallel end face.

Fig. 6 is an exploded view of friction on the thread face of the bolt looseness prevention structure with non-parallel end faces.

Fig. 7 is a schematic diagram of the actual contact area of the nut and the connected piece in the bolt anti-loose structure with non-parallel end faces.

Fig. 8 is a schematic diagram of the actual clamping length of the bolt anti-loosening structure with non-parallel end faces.

Fig. 9 is a schematic view of an upper connector machined with generally non-parallel end faces.

Fig. 10 is a schematic view of an upper connector machined with countersunk non-parallel end faces.

Fig. 11 is a schematic view of an upper connector machined with non-parallel end faces of bosses.

Fig. 12 is a cross-sectional view of an upper connector machined with generally non-parallel end faces.

Fig. 13 is a cross-sectional view of an upper connector machined with countersunk non-parallel end faces.

FIG. 14 is a cross-sectional view of an upper connector machined with non-parallel end faces of bosses.

Fig. 15 is a curve of a pretightening force drop curve of a bolt anti-loose structure with end faces of different inclination angles when a transverse displacement load is applied, wherein the ordinate represents the pretightening force of the bolt, the structure is more stable as the drop degree of the pretightening force is smaller, and the abscissa represents the vibration time.

In the figure: 1, connecting piece; 2 lower connected piece; 3, bolts; 4, nuts.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings of the present invention.

As shown in fig. 1, the bolt anti-loosening structure with non-parallel mounting end surfaces comprises an upper connected piece 1, a lower connected piece 2, a bolt 3 and a nut 4, wherein the bolt 3 penetrates through the upper connected piece 1 and the lower connected piece 2 to be matched with the nut 4, and the bolt 3 and the nut 4 clamp the upper connected piece 1 and the lower connected piece 2. The surface of the upper connected piece 1 is processed with non-parallel mounting end surfaces.

The machining of the non-parallel mounting end surface of the upper connected piece 1 surface can adopt but is not limited to milling:

1. the upper connected piece 1 is obliquely milled to form a non-parallel mounting end face: on a vertical or horizontal milling machine, under the condition that a milling cutter cannot realize a rotation angle, the upper connected part 1 is installed at an inclined angle required for milling a non-parallel installation end face.

2. The milling cutter obliquely mills and processes a non-parallel mounting end face: the end milling cutter and the end milling cutter can be deflected by a certain angle according to requirements on a vertical milling machine with a deflectable end milling head, a horizontal milling machine with the deflectable end milling head and a universal tool milling machine to mill non-parallel mounting end surfaces.

3. The milling processing of the angle milling cutter has non-parallel mounting end faces: a milling cutter in which the cutting edges are inclined at an angle to the axis is called an angle milling cutter, and the inclination angle of the non-parallel mounting end face is secured by the angle milling cutter.

As shown in FIG. 7, the non-parallel end surface of the upper connected piece 1 should not be changed to affect the overall geometric dimension or performance, and the actual clamping length of the bolt connecting structure in the invention is the perpendicular distance from the intersection point of the non-parallel mounting end surface and the bolt axis to the contact surface of the bolt head and the lower connected piece.

As shown in fig. 9 to 14, the non-parallel end surface of the upper connected member 1 may be processed into a common non-parallel end surface, a countersunk non-parallel end surface, or a boss non-parallel end surface according to the installation requirement without changing the overall geometric dimension or performance.

The depth of the non-parallel end face of the countersunk head can be designed as a compensation size according to the installation requirement.

The height of the non-parallel end face of the boss can be designed as a compensation dimension according to the installation requirement.

As shown in fig. 6, the input torque applied to the outer nut may be decomposed into a thread friction torque, a pitch torque, and a face friction torque. Due to the presence of the non-parallel mounting end surfaces, there is an additional contact force on the contact surfaces on the external thread, which creates an additional contact friction and thus an additional friction torque. When the bolt node receives lateral vibration load, extra contact friction can improve the locking performance of bolt.

The upper connected piece and the bottom of the bolt are fixed, at the moment, the thread, the bolt and the connected piece can be approximately regarded as cantilever beam structures, and the rigidity of the cantilever beam structures is K₁、K₂And K₃The bending angle is theta₁、θ₂And theta₃. Because of the end face contact with geometric unevenness, bending moment M is generated at the bolt joint, the bending moment M generates an additional contact force, and the fact that the internal thread and the external thread are transversely pressed in the tightening process is proved to generate additional contact friction force F_fNamely:

the additional contact friction torque M' is:

wherein r is_cIs the end face friction radius, mu_tIs the thread friction factor, r_tIs the thread friction radius, and beta is the thread form half angle.

According toIt can be seen that when r is_cIs the end face friction radius, mu_tIs the thread friction factor, r_tWhen the thread friction radius is equal and beta is a tooth-shaped half angle, the larger the geometric inclination angle theta of the non-parallel end surface is, the larger the extra contact friction torque M' is, and the anti-loosening effect of the non-parallel end surface is enhanced.

As shown in fig. 7, in the load-bearing area between the nut and the upper coupled member, the actual contact area a is reduced due to the non-parallel mounting end surfaces,

in the assembling process, the pre-tightening force is not reduced due to the fact that the upper connecting piece generates plastic deformation because of overlarge assembling load. Thus, the surface contact stress does not exceed the maximum allowable stress for the material. Selecting a proper safety coefficient K and a limit value of the geometric inclination angle theta of the non-parallel end face as follows:

wherein, the deformation of the upper connected piece

p_GThe allowable maximum stress of the material, K is a safety coefficient, F is an initial value of the pretightening force of the bolt connecting structure, A (z) is the area of a pressed layer of a connected piece area, E is the elastic modulus of the connected piece, and l is the actual clamping length.

As shown in fig. 14, in order to further verify the anti-loosening effect, the invention is tested by experiments, wherein the experiments adopt 12.9-grade M10 × 1.5 bolt and nut, the material is 40Cr, the material of the connected piece also adopts 40Cr, the transverse load vibration amplitude set by the experiments is 0.4mm, and the frequency is 4 HZ. The total 4 interchangeable by the connecting piece cushion blocks of different inclinations of used experimental test piece in the experiment are 0 degree, 0.6 degree, 0.8 degree and 1 degree respectively. At the inclination angle of 0 degree, the pretightening force basically shows a straight line descending trend. Along with the increase of the inclination angle, the descending slope of the pretightening force of the bolt is reduced, and the anti-loosening effect of the non-parallel end face is enhanced. When the inclination angle reaches 1 degree, the descending slope of the pretightening force of the bolt approaches to 0, and the anti-loosening effect of the non-parallel end face reaches the limit.

The above is an embodiment of the invention, and the bolt anti-loose structure with the non-parallel mounting end face can be used in combination with other traditional methods, so that the anti-loose effect is enhanced.