Bolt capable of automatically recognizing pre-tightening force and fastening assembly

Abstract

The bolt and fastening assembly comprises a bolt head and a bolt rod which are coaxially and fixedly arranged, the bolt head is provided with a containing hole with an opening in one end, a warning column and a spring used for pushing the warning column to stretch out of the containing hole are arranged in the containing hole in a sliding mode, and a sliding groove hole is formed in one side of the containing hole. A pushing block which is clamped into the warning column to limit the warning column in the containing hole is arranged in the sliding groove hole in a sliding mode, the pushing block is pushed by a control unit through a telescopic piece to be clamped into or separated from the warning column, a signal input interface of the control unit is connected with a pressure sensor, and the pressure sensor is arranged on the end face, making contact with the connecting piece, of the bolt head. The pre-tightening force between the bolt head and the connecting piece is obtained by detecting the pre-tightening force between the bolt head and the connecting piece, the detected pre-tightening force is transmitted to the control unit, the control unit controls stretching and retracting of the telescopic piece according to the pre-tightening force, the pre-tightening force can be accurately controlled, and installation of the bolt is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical fasteners, in particular to a bolt and a fastening assembly which can self-identify pre-tightening force. Background Art

[0002] Bolts, as important fasteners and connectors, play a vital role in mechanical connections. Their tightening effect is directly related to the stability and safety of the entire mechanical system. During the installation process, the bolt preload should reach the predetermined design value to ensure that the equipment will not cause stress relaxation due to vibration, sliding, fatigue, pressure and temperature changes during operation.

[0003] The traditional bolt tightening method mainly relies on the operator's experience, feel or consulting the mechanical manual, and achieves the required tightening degree, that is, the predetermined pre-tightening force, by rotating the bolt. However, this operation method results in imprecise control of the pre-tightening force. If the pre-tightening force is less than the design value, it is easy to cause problems such as loose connection and leakage, thereby affecting the overall performance of the mechanical system; if the pre-tightening force is greater than the design value, it will cause damage to the bolts or connectors. Summary of the invention

[0004] In order to solve the problem of inaccurate preload control in the prior art, the present invention provides a bolt and a fastening assembly with self-identifying preload, which can accurately control the preload so that the preload of the bolt reaches the designed value.

[0005] In order to achieve the above-mentioned purpose, the specific scheme adopted by the present invention is: a bolt with self-identifying pre-tightening force, comprising a bolt head and a bolt rod coaxially fixed, the bolt head being provided with a receiving hole with an opening at one end, a warning column and a spring for pushing the warning column out of the receiving hole being slidably arranged in the receiving hole, a slide slot hole being provided on one side of the receiving hole, a pushing block being slidably arranged in the slide slot hole and being inserted into the warning column to restrict the warning column in the receiving hole, the pushing block being pushed into or out of the warning column by a control unit through a telescopic member, and the signal input interface of the control unit being connected to a pressure sensor, the pressure sensor being provided on the contact end surface of the bolt head and the connecting member to obtain the pre-tightening force between the bolt head and the connecting member, and transmitting the detected pre-tightening force to the control unit, and the control unit controlling the extension and retraction of the telescopic member according to the pre-tightening force.

[0006] As an optimization solution for the above-mentioned self-identifying pre-tightening force bolt and fastening assembly: the material of the telescopic member is an electroactive polymer.

[0007] As another optimization scheme for the above-mentioned self-identifying pre-tightening bolt and fastening assembly: the pushing block has an inclined surface, and a slot is provided on the outer side wall of the warning column, and one side wall of the slot is inclined and can fit with the inclined surface.

[0008] As another optimization solution for the above-mentioned self-identifying pre-tightening bolt and fastening assembly: the side of the slot close to the push block has a cut-in fitting area, and the cut-in fitting area is located on the sliding track of the push block.

[0009] As another optimization scheme of the above-mentioned self-identifying preload bolt and fastening assembly: an annular member coaxial with the bolt rod is fixedly provided on the end face of the bolt head close to the bolt rod, and the pressure sensor is embedded in the annular member.

[0010] As another optimization scheme for the above-mentioned self-identifying preload bolt and fastening assembly: the pressure sensor is connected to the control unit through a connecting wire, a threading hole is provided on the bolt head, one end of the connecting wire is connected to the pressure sensor, and the other end of the connecting wire passes through the threading hole and is connected to the control unit.

[0011] As another optimization scheme for the above-mentioned self-identifying pre-tightening bolt and fastening assembly: a limit ring extending toward the center of the accommodating hole is arranged around the inner wall of the accommodating hole, and a limit block is arranged around the outer wall of the warning column, and the limit block cooperates with the limit ring to limit the length of the warning column extending out of the bolt head.

[0012] As another optimization scheme for the above-mentioned self-identifying preload bolt and fastening assembly: a first annular plate is coaxially arranged on the end face where the bolt head contacts the connecting piece, and a first annular tip is arranged on the inner side wall of the first annular plate, and the first annular tip can be squeezed into the gap between the bolt rod and the inner side wall of the through hole of the connecting piece.

[0013] A fastening assembly comprises a bolt and a nut. The bolt rod of the bolt passes through a through hole of a connecting piece and then matches with the nut. The bolt is the above-mentioned bolt.

[0014] As an optimization solution for the above-mentioned fastening assembly: the end surface of the nut is provided with a second annular tip, and the second annular tip can be squeezed into the gap between the bolt rod and the inner side wall of the through hole of the connecting piece.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The present invention provides a bolt with self-identifying pre-tightening force. Before the bolt is installed, the telescopic part is in an extended state, the pushing block is stuck in the warning column to restrict the warning column in the bolt head, and the spring is in a compressed state; during the bolt installation process, the pressure sensor collects the pre-tightening force and transmits the collected data to the control unit. When the collected pre-tightening force reaches the design value, the control unit controls the telescopic part to shorten, thereby driving the pushing block to move away from the warning column. The spring pushes the warning column to move until the top of the warning column extends out of the bolt head, indicating that the pre-tightening force of the bolt reaches the design value and the bolt is tightened. That is, the present invention can accurately control the pre-tightening force and facilitate the installation of the bolt.

[0017] 2. In the present invention, when the bolt becomes loose during use, the preload force collected by the pressure sensor is less than the design value, and the control unit controls the telescopic part to extend, driving the push block to extend into the slot to press the warning column into the bolt head, thereby shortening the length of the warning column extending from the bolt head, making it easier for staff to detect and tighten the bolt in time, thereby further improving the stability and safety of the entire mechanical system.

[0018] 3. In the present invention, the limit ring and the limit block cooperate to limit the length of the warning column extending from the bolt head, so that the cutting-in fitting area is located on the sliding track of the push block, thereby ensuring that when the bolt is loosened, the free end of the push block can smoothly enter the slot.

[0019] 4. The present invention provides a fastening assembly. During the installation of the bolt and the nut, the first annular tip and the second annular tip enter the gap between the bolt rod and the through hole of the connecting piece to ensure that the bolt rod and the through hole are coaxial, so that the force on the bolt is more balanced and the service life of the bolt is increased; the maximum force on the bolt is increased by the extrusion of the first annular tip and the second annular tip. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the bolt structure when the push block is stuck into the warning column;

[0021] Figure 2 It is a schematic diagram of the structure of the bolt when the push block slides out of the slot;

[0022] Figure 3 is a schematic structural diagram of a bolt head in Embodiment 2;

[0023] Figure 4 is a schematic structural diagram of a bolt head in Embodiment 3;

[0024] Figure 5 It is a schematic diagram of the structure of the warning column and the push block;

[0025] Figure numerals: 1. bolt head, 101. threading hole, 102. receiving hole, 103. slide slot hole, 2. bolt rod, 3. pressure sensor, 4. control unit, 5. telescopic member, 6. push block, 601. inclined surface, 7. warning column, 701. slot, 702. spring, 703. cut-in fitting area, 8. sealing plate, 9. nut, 901. second annular tip, 10. first annular sheet, 1001. first annular tip. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further elaborated in detail below in conjunction with specific embodiments. The parts that are not described and disclosed in detail in the following embodiments of the present invention should be understood as the existing technologies known or should be known to those skilled in the art, such as how the pressure sensor 3 obtains the preload force, how the pressure sensor 3 transmits the obtained preload force to the control unit 4, how the control unit 4 controls the extension and retraction of the telescopic member 5, etc.

[0027] Example 1

[0028] A bolt that self-identifies preload force comprises a bolt head 1 and a bolt rod 2 that are coaxially fixed. The cross section of the bolt head 1 is a hexagon, and the bolt rod 2 is a cylindrical structure. The center line of the bolt head 1 coincides with the center line of the bolt rod 2. The bolt head 1 is provided with a receiving hole 102 with an open end, that is, the receiving hole 102 is a blind hole provided on the bolt head 1. The receiving hole 102 may be a circular hole, a square hole, or a polygonal hole. In the present embodiment, the receiving hole 102 is a circular hole structure. The axis of the receiving hole 102 may be parallel, perpendicular, or intersecting with the center line of the bolt head 1 to form an angle. In the present embodiment, the axis of the receiving hole 102 is parallel to the center line of the bolt head 1, such as Figure 1 As shown, the opening of the receiving hole 102 is formed on the end face of the bolt head 1 facing away from the bolt shaft 2 .

[0029] A warning column 7 and a spring 702 for pushing the warning column 7 out of the accommodating hole 102 are slidably arranged in the accommodating hole 102. The shape of the cross section of the warning column 7 is the same as the shape of the cross section of the accommodating hole 102. In the present embodiment, the warning column 7 is a cylindrical structure, and the diameter of the warning column 7 is slightly smaller than the diameter of the accommodating hole 102, that is, there is a movable margin between the outer wall of the warning column 7 and the inner wall of the accommodating hole 102 for the warning column 7 to slide, and an elastic zone is formed between the bottom end of the warning column 7 and the bottom wall of the accommodating hole 102. The spring 702 is located in the elastic zone, one end of the spring 702 is fixedly connected to the bottom end of the warning column 7, and the other end of the spring 702 is fixedly connected to the bottom wall of the accommodating hole 102. In the present embodiment, the spring 702 is a compression spring 702.

[0030] A slide slot hole 103 is provided on one side of the receiving hole 102. In this embodiment, the slide slot hole 103 is a long strip groove with an opening located at the end face of the bolt head 1 away from the bolt rod 2. One end of the slide slot hole 103 is connected to the receiving hole 102. The extension direction of the slide slot hole 103 can be perpendicular to the axis of the receiving hole 102 or intersect to form an acute angle. In this embodiment, the extension direction of the slide slot hole 103 is perpendicular to the axis of the receiving hole 102. The slide slot hole 103 is a long strip groove with an opening located at the end face of the bolt head 1 away from the bolt rod 2. A push block 6 is slidably provided in the slide slot hole 103 to be inserted into the warning column 7 to limit the warning column 7 in the receiving hole 102. The sliding direction of the push block 6 is the same as the extension direction of the slide slot hole 103.

[0031] The structure for driving the push block 6 to slide is that the push block 6 is pushed by a control unit 4 through a telescopic member 5 to be inserted into or disengaged from the warning column 7, wherein the control unit 4 is a miniature circuit board with a built-in receiver and capacitor. When the bolt reaches the pre-tightening force, the pressure sensor 3 transmits current to the control unit 4, and the current passes through the receiver and controls the capacitor to release electrons, thereby stimulating the electroactive polymer; the telescopic member 5 is a long strip structure and its material is an electroactive polymer. The telescopic member 5 is located in the slide slot hole 103 and its telescopic direction is the same as the extension direction of the slide slot hole 103. One end of the telescopic member 5 is connected to the pushing block 6, and the other end of the telescopic member 5 is connected to the signal output interface of the control unit 4, and the signal input interface of the control unit 4 is connected to the pressure sensor 3; the pressure sensor 3 is arranged on the contact end surface of the bolt head 1 and the connecting member. Specifically, an annular member coaxial with the bolt rod 2 is fixedly arranged on the contact end surface of the bolt head 1 and the connecting member. The inner diameter of the annular member is equal to the diameter of the bolt rod 2, and the outer diameter of the annular member is the same as the diameter of the inscribed circle of the bolt head 1. The pressure sensor 3 is embedded in the annular member to obtain the preload force between the bolt head 1 and the connecting member, and transmit the detected preload force to the control unit 4. The control unit 4 controls the extension and retraction of the telescopic member 5 according to the preload force.

[0032] The pressure sensor 3 is connected to the control unit 4 via a connecting wire. The bolt head 1 is provided with a threading hole 101 . One end of the connecting wire is connected to the pressure sensor 3 , and the other end of the connecting wire passes through the threading hole 101 and is connected to the control unit 4 .

[0033] When the bolt is not installed, the telescopic rod is in an extended state. At this time, the telescopic rod is inserted into the warning rod to restrict the warning rod in the receiving hole 102, that is, the top of the receiving hole 102 is located in the receiving hole 102. At this time, the spring 702 is in a compressed state; during the installation of the bolt, the preload force between the bolt head 1 and the connecting member gradually increases, and the pressure sensor 3 obtains the preload force and transmits it to the control unit 4. When the preload force reaches the design value, the control unit 4 controls the telescopic member 5 to shorten and drive the push block 6 to slide in the slide slot hole 103, and the sliding direction deviates from the warning column 7 until the push block 6 is separated from the warning column 7. At this time, the spring 702 pushes the warning rod to make the warning rod extend out of the bolt head 1. The extended warning rod is used to display that the bolt has reached the design value and the bolt is tightened, that is, the preload force can be accurately controlled to facilitate the installation of the bolt.

[0034] The above is a basic implementation of the present invention, which can be further improved, optimized and limited on the basis of the above, so as to obtain the following embodiments:

[0035] Example 2

[0036] This embodiment is an improved solution based on the embodiment 1. Its main structure is the same as that of the embodiment 1. The improvement is as follows: Figure 2As shown, the push block 6 has an inclined surface 601, and the push block 6 is a rectangular parallelepiped structure. The inclined surface 601 is close to the warning column 7, and the top of the inclined surface 601 is close to the warning column 7, and the bottom of the inclined surface 601 is away from the warning column 7. The outer wall of the warning column 7 is provided with a card slot 701, as shown in FIG. Figure 5 As shown, the top side wall of the slot 701 is a horizontal plane. One side wall of the slot 701 is inclined and can fit with the inclined surface 601 .

[0037] like Figure 4 As shown, the side of the slot 701 close to the pushing block 6 has a cut-in fitting area 703, and the cut-in fitting area 703 is located at the bottom of the slot 701. When the pushing block 6 enters the slot 701, it first enters from the cut-in fitting area 703, and when the pushing block 6 exits the slot 701, it finally slides out from the cut-in fitting area 703; when the pre-tightening force reaches the design value, the pushing block 6 is separated from the warning column 7, and the spring 702 pushes the top of the warning column 7 to extend out of the bolt head 1. When the spring 702 is in a free state, the cut-in fitting area 703 is located on the sliding track of the pushing block 6. When the bolt is not installed, the telescopic member 5 is in an extended state, and the inclined surface 601 of the push block 6 fits with the inclined side wall of the slot 701 to limit the top of the warning column 7 in the receiving hole 102; when the preload reaches the design value, the control unit 4 controls the telescopic member 5 to shorten, and at this time, the inclined surface 601 of the push block 6 slides along the inclined side wall of the slot 701. During the sliding process, the spring 702 pushes the warning column 7 out of the bolt head 1 to complete the bolt tightening. When the bolt is loose, the control unit 4 controls the telescopic member 5 to extend, and the push block 6 enters the slot 701 by cutting into the fitting area 703. The inclined surface 601 slides along the inclined side wall of the slot 701, pushing the warning column 7 to retract into the bolt head 1, indicating that the bolt is loose, which is convenient for the staff to detect and perform maintenance in time, further improving the stability and safety of the entire mechanical system.

[0038] Example 3

[0039] This embodiment is an improved solution based on the embodiment 2. Its main structure is the same as that of the embodiment 2. The improvement is as follows: Figure 4 As shown, a limit ring extending toward the center is arranged around the inner wall of the accommodating hole 102, and a limit block is arranged around the outer wall of the warning column 7. The limit block cooperates with the limit ring to limit the length of the warning column 7 extending out of the bolt head 1, thereby ensuring that the cutting-in fitting area 703 is located on the sliding track of the pushing block 6, thereby ensuring that when the bolt is loosened, the free end of the pushing block 6 can smoothly enter the slot 701.

[0040] Example 4

[0041] This embodiment is an improved solution based on the embodiment 1, and its main structure is the same as that of the embodiment 1, and the improvement is that: in this embodiment, a groove is provided on the end face of the bolt head 1 away from the bolt rod 2, and the slide slot hole 103 is provided at the bottom of the groove, and a sealing plate 8 capable of closing the opening is provided at the opening of the groove, which plays a protective role for the telescopic member 5 and the push block 6. In this embodiment, a hole coaxial with the receiving hole 102 is provided on the sealing plate 8, so that the warning column 7 can pass through the sealing plate 8 and extend out of the bolt head 1.

[0042] Example 5

[0043] This embodiment is an improvement on the embodiment 1, and its main structure is the same as that of the embodiment 1, and the improvement lies in that: during the bolt installation process, since the diameter of the through hole of the connecting piece is larger than the diameter of the bolt rod 2, there is a gap between the outer wall of the bolt rod 2 and the inner wall of the through hole, which makes it easy for the bolt to deviate from the predetermined position during installation, that is, the axis of the bolt rod 2 and the axis of the through hole cannot coincide, which leads to uneven force on the contact surface between the connecting piece and the bolt head 1, and produces stress concentration, affecting the stability and life of the mechanical system. Therefore, a first annular plate 10 is coaxially arranged on the end face where the bolt head 1 contacts the connecting piece, the inner diameter of the first annular plate is equal to the diameter of the bolt rod 2, the outer diameter of the first annular plate is equal to the diameter of the inscribed circle of the bolt head 1, and the inner wall of the first annular plate 10 is provided with a first annular tip 1001, as shown in FIG. Figure 4 As shown, the first annular tip 1001 extends toward the side away from the bolt head 1, and its outer side wall is an arc-shaped structure. The first annular tip 1001 can be squeezed into the gap between the bolt rod 2 and the inner side wall of the connecting member through hole, ensuring that the bolt rod 2 is coaxial with the through hole, making the force on the bolt more balanced and improving the service life of the bolt.

[0044] Example 6

[0045] A fastening assembly includes a bolt and a nut 9. A bolt rod 2 of the bolt passes through a through hole of a connecting piece and then matches with the nut 9. The bolt is any one of the bolts described in embodiments 1-5.

[0046] Example 7

[0047] A fastening assembly includes a bolt and a nut 9. The bolt rod 2 of the bolt passes through the through hole of the connecting piece and then matches with the nut 9. The bolt in this embodiment is the bolt described in Embodiment 4. The end face of the nut 9 is provided with a second annular tip 901. The second annular tip 901 and the nut 9 are integrally formed. The second annular tip 901 can be squeezed into the gap between the bolt rod 2 and the inner side wall of the through hole of the connecting piece. During the bolt installation process, the first annular tip 1001 and the second annular tip 901 squeeze into the gap between the inner side wall of the connecting hole and the bolt rod 2, ensuring that the bolt rod 2 is coaxial with the through hole, making the force on the bolt more balanced, and improving the service life of the bolt; through the extrusion of the first annular tip 1001 and the second annular tip 901, the maximum force on the bolt is increased.

[0048] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A bolt with self-identifying preload force, comprising a bolt head (1) and a bolt shank (2) coaxially fixedly arranged, characterized in that: The bolt head (1) is provided with a receiving hole (102) with an opening at one end, a warning column (7) and a spring (702) for pushing the warning column (7) out of the receiving hole (102) are slidably arranged in the receiving hole (102), a slide slot hole (103) is arranged on one side of the receiving hole (102), a pushing block (6) is slidably arranged in the slide slot hole (103) and is inserted into the warning column (7) to restrict the warning column (7) in the receiving hole (102), the pushing block (6) is pushed by a control unit (4) through a telescopic member (5) to be inserted into or separated from the warning column (7), and a signal input interface of the control unit (4) is connected to a pressure sensor (3), the pressure sensor (3) is arranged on the contact end surface of the bolt head (1) and the connecting member to obtain the preload force between the bolt head (1) and the connecting member, and transmits the detected preload force to the control unit (4), and the control unit (4) controls the extension and retraction of the telescopic member (5) according to the preload force.

2. A bolt with self-identifying preload force as claimed in claim 1, characterized in that: The material of the telescopic member (5) is an electroactive polymer.

3. A bolt with self-identifying preload force as claimed in claim 1, characterized in that: The pushing block (6) has an inclined surface (601), and the outer side wall of the warning column (7) is provided with a slot (701), and one side wall of the slot (701) is inclined and can fit with the inclined surface (601).

4. A bolt with self-identifying preload force as claimed in claim 3, characterized in that: The side of the clamping slot (701) close to the pushing block (6) has a cut-in fitting area (703), and the cut-in fitting area (703) is located on the sliding track of the pushing block (6).

5. A bolt with self-identifying preload force as claimed in claim 1, characterized in that: An annular member coaxial with the bolt rod (2) is fixedly arranged on the end surface of the bolt head (1) close to the bolt rod (2), and the pressure sensor (3) is embedded in the annular member.

6. A bolt with self-identifying preload force as claimed in claim 1, characterized in that: The pressure sensor (3) and the control unit (4) are connected via a connecting wire; the bolt head (1) is provided with a threading hole (101); one end of the connecting wire is connected to the pressure sensor (3); and the other end of the connecting wire passes through the threading hole (101) and is connected to the control unit (4).

7. A bolt with self-identifying preload force as claimed in claim 1, characterized in that: A limiting ring extending toward the center is arranged around the inner wall of the accommodating hole (102), and a limiting block is arranged around the outer wall of the warning column (7). The limiting block cooperates with the limiting ring to limit the length of the warning column (7) extending beyond the bolt head (1).

8. A bolt with self-identifying preload force as claimed in claim 1, characterized in that: The end surface of the bolt head (1) in contact with the connecting piece is coaxially provided with a first annular plate (10), and the inner side wall of the first annular plate (10) is provided with a first annular tip (1001), and the first annular tip (1001) can be squeezed into the gap between the bolt rod (2) and the inner side wall of the through hole of the connecting piece.

9. A fastening assembly, comprising a bolt and a nut (9), wherein the bolt shank (2) of the bolt passes through a through hole of a connecting member and then matches with the nut (9), characterized in that: The bolt is the bolt described in any one of claims 1 to 8.

10. A fastening assembly according to claim 9, characterized in that: The end surface of the nut (9) is provided with a second annular tip (902), and the second annular tip (902) can be squeezed into the gap between the bolt rod (2) and the inner side wall of the connecting member through hole.

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