CN115419646A - Multifunctional fastening characteristic test bolt - Google Patents

Multifunctional fastening characteristic test bolt Download PDF

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Publication number
CN115419646A
CN115419646A CN202211003721.9A CN202211003721A CN115419646A CN 115419646 A CN115419646 A CN 115419646A CN 202211003721 A CN202211003721 A CN 202211003721A CN 115419646 A CN115419646 A CN 115419646A
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CN
China
Prior art keywords
bolt
inner hole
end cap
sensitive unit
force
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202211003721.9A
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Chinese (zh)
Inventor
严鲁涛
王浩
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Beijing University of Posts and Telecommunications
Original Assignee
Beijing University of Posts and Telecommunications
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Beijing University of Posts and Telecommunications filed Critical Beijing University of Posts and Telecommunications
Priority to CN202211003721.9A priority Critical patent/CN115419646A/en
Publication of CN115419646A publication Critical patent/CN115419646A/en
Pending legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B35/00—Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
    • G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/24—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for determining value of torque or twisting moment for tightening a nut or other member which is similarly stressed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B2200/00—Constructional details of connections not covered for in other groups of this subclass
    • F16B2200/95—Constructional details of connections not covered for in other groups of this subclass with markings, colours, indicators or the like

Abstract

The invention discloses a multifunctional fastening characteristic test bolt, which comprises: a bolt, an end cap and a sensitive unit; the inner part of the bolt is provided with a bolt inner hole, the depth of the bolt inner hole is greater than the length of a bolt nut, and the bolt inner hole is divided into a top inner hole, a middle section inner hole and a bottom inner hole; the sensitive unit comprises an end part, a column section and a guide section, the upper plane of the end part is in contact fit with the end cap, a plurality of groups of strain gauges are uniformly distributed on the lower plane of the end part along the axial direction, the plurality of groups of strain gauges are further connected with corresponding signal lines respectively, and the axial force and the moment can be monitored simultaneously. The column section and the guide section are used for penetrating into an inner hole of the bolt; the end cap threads of the end cap are connected with the bolt threads, the end cap is tightly pressed with the sensitive unit under the action of screwing force, and the sensitive unit is tightly pressed with the inner hole at the bottom of the bolt through the column section and the guide section. The invention does not change the structure of the original bolt, does not influence the installation and use of the original bolt, and can feed back the force and the moment born by the bolt in real time.

Description

Multifunctional fastening characteristic test bolt
Technical Field
The invention discloses a multifunctional fastening characteristic testing bolt, belongs to the technical field of connection of mechanical structures, and particularly relates to a method for testing and monitoring the pretightening force and the axial force of a bolt.
Background
The bolt connection has the advantages of good stress and anti-seismic performance, high connection strength, fatigue resistance, simple structure and the like, and is widely applied to various engineering practices, such as railways, aviation, ships and other industries, due to convenient disassembly and low cost. As such, the bolts have an important impact on the reliability and safety of the engineering components, and the failure of the bolts can cause significant economic loss and even casualties.
When the bolt is installed, the requirement of pretightening force is usually required, and the common bolt connection for transferring the transverse load is that corresponding positive pressure is generated between contact surfaces of a connected piece through the pretightening force, so that frictional resistance is generated between the contact surfaces to achieve the purpose of transferring the transverse load. The size of bolt pretightening force is the important factor that influences structural safety and reliability. The selection of larger pretightening force is beneficial to the reliability of threaded connection and the fatigue strength of a connecting piece, but the excessive pretightening force can cause the bolt to be broken when in assembly or accidental overload, so that the bolt connection structure is failed.
However, the connection state of the bolt is determined by an operator, a tightening tool, a tightening method, a material of the connecting member, and the like. In addition, the bolt connection state may be changed by the influence of vibration, impact, temperature change, and the like, and the connection structure may be failed. Therefore, in the important occasions of using the bolt connection, the bolt connection state is paid particular attention to, and the pretightening force is monitored in real time in the installation process; after the installation is finished, the axial force (pretightening force) of the bolt is randomly and periodically detected to ensure the stability and reliability of bolt connection.
In engineering, indirect methods such as a torque method and a corner method are usually adopted to control the axial force of the bolt so as to achieve the purpose of fastening the connecting piece, but the torque coefficient is not constant, so that the axial force in the mechanical connecting structure is large in dispersity, and the overall reliability of the structure is further influenced. In addition, the bolt connection in the structure is usually a bolt group comprising a plurality of bolts, the tightening process increases the tightening sequence, the number of times of re-tightening and other factors, and the control of the axial force of the bolt group by using a torque method and a rotation angle method is more difficult. The tightening state of the bolt can be quickly and effectively sensed and evaluated by directly measuring the axial force of the bolt.
At present, the axial force of the bolt is measured by a force measuring gasket, an ultrasonic method and a strain measurement method. The force measuring gasket needs to specially manufacture a sensor according to the space and the size of a bolt, so that the process is complicated, and the cost is high; the ultrasonic method calculates the elongation of the bolt according to the ultrasonic time and speed, calculates the axial force of the bolt according to the axial rigidity of the bolt, and has low accuracy because the measurement accuracy is related to factors such as the planeness and the parallelism of the end face of the bolt; strain measurement is the most intuitive way to use strain to test the direct strain of the bolt pieces and thus obtain the axial force. The strain measurement method is divided into a direct mounting method and an indirect measurement method, wherein the direct mounting method is to mount a strain gauge outside a bolt, but the strain gauge cannot be used in actual installation; in the indirect measurement method, an elastic element is arranged in a bolt and is in relation with the strain of the bolt, so that the axial force of the bolt is obtained through a sensitive element, but the realization structure of the strain measurement method is complex.
The invention patent with publication number CN106872092A is a force measuring bolt and a method for measuring axial force, wherein a core body connected with a strain gauge is arranged in an inner hole of the bolt, the core body is tightly fixed with a main bolt, and a strain value can be directly obtained through the strain gauge on the core body to measure the axial force value of the bolt. The method can measure the axial force, but the volume of the core body influences the diameter of the inner hole of the bolt, namely the axial force load of the bolt. In addition, the invention has higher installation requirement.
Disclosure of Invention
The invention aims to overcome part of defects in the prior art, provides a multifunctional fastening characteristic test bolt required by bolt axial force (or pretightening force) test, and solves the problems that the conventional bolt cannot test fastening force, and the prior art is complex in structure, single in test function and unstable.
The multifunctional fastening characteristic testing bolt provided by the invention utilizes the existing bolt structure, the sensitive unit is arranged in the bolt structure, the pretightening force is applied by the end cap, the stress of the bolt is connected with the sensitive unit, and when the bolt is screwed, the sensitive unit can monitor the axial force and the moment of the bolt so as to judge the fastening state and the stress condition of the bolt. The invention does not change the structure of the original bolt, does not influence the installation and use of the original bolt, and can feed back the force and the moment born by the bolt in real time.
A multifunctional fastening characteristic testing bolt comprising: bolts, end caps, sensitive units;
the bolt is a universal fastener, and different specifications can be selected according to actual use conditions. The bolt is internally provided with a bolt inner hole, and the depth of the bolt inner hole is greater than the length of a bolt nut. The bolt inner hole is divided into a top inner hole, a middle section inner hole and a bottom inner hole, wherein the top inner hole is used for providing a certain guiding function when the sensitive unit is installed.
The sensitive unit is a core component of the invention and is used for sensing the external acting force applied to the bolt. The sensitive unit comprises an end part, a column section and a guide section, the upper plane of the end part is in contact fit with the end cap, a plurality of groups of strain gauges are uniformly distributed on the lower plane of the end part along the axial direction, the plurality of groups of strain gauges are further connected with corresponding signal lines respectively, and the axial force and the moment can be monitored simultaneously. The column section and the guide section are used for penetrating into the inner hole of the bolt, and the guide section is in direct contact with the inner hole at the bottom of the inner hole of the bolt, is used for preventing the sensitive unit from inclining and plays a certain role in fixing;
furthermore, a lubricating layer is arranged between the upper plane of the end part of the sensitive unit and the end cap, so that the friction force between the end part of the sensitive unit and the end cap is reduced, and the sensitive unit is convenient to fasten and install. The lubricating layer can be made of ceramic, teflon, copper and the like with strong lubricating property.
The end cap is of a hollow structure, is provided with internal threads, and is in threaded fit with the bolt to form an accommodating space for accommodating and protecting the sensitive unit;
furthermore, the side wall of the end cap is provided with an end cap groove which is of a through groove structure. The signal line is led out from the signal acquisition system and is connected with an external transmitter and a signal acquisition system.
Furthermore, the top end of the end cap is provided with a groove to form a fastening end, which is mainly used for providing a force application space for a screwing tool.
The end cap threads of the end cap are connected with the bolt threads, the end cap is tightly pressed with the sensitive unit under the action of screwing force, and the sensitive unit is tightly pressed with the inner hole at the bottom of the bolt through the column section and the guide section. The tightening force is applied to the tightening end of the end cap by an external tool, and the groove provides a force application space. When the end cap is tightly pressed with the sensitive unit, the lubricating layer plays a role in reducing friction, and further the operation difficulty is reduced.
As mentioned above, after the end cap is screwed with the bolt, the sensitive unit is connected with the bottom of the bolt through the column section and the guide section, and the stress of the sensitive unit is the pre-tightening force between the end cap and the bolt. When an external force acts on the bolt, the column section of the bolt is stretched, the column section of the sensing unit releases a certain force, and the stress of the sensing unit is monitored in real time by the strain gauge on the sensing unit, so that the stress of the bolt can be tested.
The multifunctional fastening characteristic testing bolt provided by the invention is a key tool for testing the fastening force of the bolt and the stress of a connecting part, and has practical significance for monitoring the reliability of a bolt connecting piece. The invention can realize the fastening force test in the bolt fastening process, the axial force monitoring after bolt fastening, the torque monitoring and the like. The invention has the obvious advantages that:
(1) The original thread structure of the bolt is not changed, the bolt is consistent with the original use state, and no special requirement is imposed on the installation and use of the bolt;
(2) The multifunctional bolt fastening device has various functions, can test parameters such as fastening force, axial force, external moment and the like of the bolt, and can realize reliability monitoring in the fastening process and the using process;
(3) The invention has high integration level and convenient use, is provided with the lubricating layer and has low requirement on installation;
(4) The invention has no special requirements on the diameters of the column section and the guide section of the sensitive element, namely the inner hole of the bolt can be a smaller value, and the influence on the axial load capacity of the bolt is smaller;
(5) The invention is suitable for bolts with different specifications and can realize state monitoring of different structures.
Drawings
FIG. 1 is a front view of an overall structure of a multifunctional test bolt
FIG. 2 front view of the bolt
FIG. 3 front view of the sensing unit
FIG. 4 bottom view of the sensing unit
FIG. 5 end cap elevation view
FIG. 6 end Cap left side elevation view
FIG. 7 end cap top view
1, a bolt; 2a signal line; 3, end cap grooves; 4 an end cap; 5 a lubricating layer; 6, a sensitive unit; 7, grooves; 8 strain gauge; 9 end cap threads; 10 bolt threads; 11, inner holes of bolts; 11a top inner hole; 11b bottom inner hole; a middle section inner hole 11c;6a column section; 6b a guide section; 7a fastening end
Detailed Description
Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar components or components having the same or similar functions throughout. The terms "first," "second," "third," and the like in the description and in the claims of the present application, and in the drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the objects so described are interchangeable under appropriate circumstances. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise. Furthermore, the terms "comprising" and "having," as well as any variations thereof, are intended to cover a non-exclusive inclusion. The directional phrases referred to in this application, for example: up, down, left, right, front, rear, inner, outer, lateral, etc., are simply directions with reference to the drawings.
It should be noted that unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly and may include, for example, fixed connections, removable connections, or integral connections; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
The embodiment of the invention provides a multifunctional fastening characteristic testing bolt, which specifically comprises the following components as shown in fig. 1: a bolt 1; a signal line 2; an end cap groove 3; an end cap 4; a lubricating layer 5; a sensitive unit 6; a groove 7; a strain gauge 8; end cap threads 9; a bolt thread 10; the bolt bore 11.
As shown in fig. 1, the bolt inner hole 11 in the bolt 1 includes a top inner hole 11a, a middle inner hole 11c and a bottom inner hole 11b; the sensitive unit 6 is provided with a column section 6a and a guide section 6b; the top end of the end cap 4 is provided with a fastening end 7a.
The bolt 1 is a main body of the invention, and a bolt inner hole 11 is arranged at the inner central position of the bolt 1 and comprises a top inner hole 11a, a middle section inner hole 11c and a bottom inner hole 11b; into which the column section 6a and the guide section 6b mainly for the sensitive unit 6 protrude. The top inner hole is used for providing a certain guiding function when the sensitive unit is installed; the bottom end of the bottom inner hole 11b is directly contacted with the bottom of the guide section 6b of the sensitive unit 6, so that the sensitive unit is prevented from inclining and plays a certain fixing role; the middle section inner hole 11c is used for accommodating the sensitive unit column section 6a.
The top of the nut of the bolt 1 is provided with bolt threads 10 for connection with the end cap 4 by means of end cap threads 9.
The length of the bolt inner hole 11 is larger than the thickness of the nut of the bolt 1.
As shown in fig. 3 and 4, the sensing unit 6 is a core component of the present invention, and is mainly used for sensing the acting force applied to the bolt. The end of the sensitive unit 6 is located inside the end cap 4; the column section 6a and the guide section 6b of the sensitive unit 6 are both located in the threaded bore 11. The lower plane of the end of the sensing unit 6 is provided with a strain gauge 8 for sensing an external force and converting strain caused by the force into an electrical signal. The strain gauges 8 are circumferentially and uniformly arranged, and each set of strain gauges 8 corresponds to one set of signal lines 2. In this embodiment, the strain gauges are 4 sets and are correspondingly connected with 4 sets of signal lines, that is, four-way signal output.
Furthermore, a lubricating layer 5 is arranged between the upper plane of the end part of the sensitive unit 6 and the end cap 4, so that the friction force between the end part of the sensitive unit and the end cap is reduced, and the sensitive unit is convenient to fasten and install. The lubricating layer 5 can be made of ceramic, teflon, copper and the like with strong lubricating property.
In the screwing process, the inner plane of the end cap 4 is directly contacted with the lubricating layer 5 on the upper plane of the sensitive unit 6, the end cap 4 and the lubricating layer 5 are gradually compressed along with the screwing process, and the sensitive unit 6 is compressed; the end cap 4 also serves to protect the sensitive unit 6 after the mounting of the integrated structure.
As shown in fig. 5 and 6, the end cap groove 3 is arranged on the side wall of the end cap 4 and is of a through groove structure. The function of the device is that a signal wire 2 is led out from the device and is connected with an external transmitter and a signal acquisition system.
As shown in fig. 5 and 7, the top end of the end cap 4 is provided with a groove 7 to form a fastening end 7a, which is mainly used for providing a force application space of a tightening tool. For example, when the wrench is used, the fastening end 7a can be driven to rotate by placing the fastening end in the groove 7.
In the present embodiment, the diameter of the column section 6a of the sensing unit 6 of the present invention is 2mm; the material of the bolt is the same as that of the bolt, so that the elasticity modulus of the bolt and the elasticity modulus of the bolt are the same.
When the device is applied and implemented specifically:
(1) Selecting a bolt 1 with an actual specification according to actual requirements, and selecting a corresponding sensitive unit 6 according to the pretightening force;
(2) Placing the sensitive unit 6 in a bolt inner hole 11 of the bolt 1, and enabling the guide section 6b to be in contact with a bottom inner hole 11b of the bolt inner hole 11;
(3) Placing an end cap 4 at the bolt thread 10 of the bolt 1, and leading out the signal wire 2 of the sensitive unit 6 through an end cap groove 3;
(4) Screwing the end cap 4 through the groove 7 and the fastening end 7a by using a tool until the lubricating layer 5 is attached to the inner side of the end cap 4;
(5) At the moment, the column section 6a of the sensitive unit 6 is compressed, an output signal of the strain gauge 8 at the moment is obtained through an external data acquisition system, and the end cap 4 is gradually screwed until the output signal reaches a preset value;
(6) The end cap 4 is secured in place to the bolt 1 using welding or gluing. And setting the pre-tightening force at the moment to be a zero position.
(7) When the bolt 1 is pre-tightened, the bolt column section is stretched, the guide section 6b is in contact with the bottom of the bolt inner hole 11, the pre-tightening force of the guide section 6b is reduced, and meanwhile, the pre-tightening force is tested by the strain gauge 8 in the sensitive unit 6, so that the external load of the bolt 1 is sensed by the sensitive unit 6.
The pretightening force and the external load of the bolt are in a functional relation, for example, an M10 bolt is taken as an example, and the ratio of the axial force of the bolt to the reading is 2500/1; the derivation is by the ratio of the circumferential area of the pin to the bolt.

Claims (6)

1. The utility model provides a multi-functional fastening characteristic test bolt which characterized in that: this test bolt includes: a bolt, an end cap and a sensitive unit;
the inner part of the bolt is provided with a bolt inner hole, and the depth of the bolt inner hole is greater than the length of a bolt nut;
the inner hole of the bolt is divided into a top inner hole, a middle section inner hole and a bottom inner hole, wherein the top inner hole is used for providing a certain guiding function when the sensitive unit is installed;
the sensing unit is used for sensing external acting force applied to the bolt and comprises an end part, a column section and a guide section, the upper plane of the end part is in contact fit with the end cap, a plurality of groups of strain gauges are uniformly distributed on the lower plane of the end part along the axial direction, the plurality of groups of strain gauges are further connected with corresponding signal lines respectively, and axial force and moment can be monitored simultaneously; the column section and the guide section are extended into the inner hole of the bolt, wherein the guide section is directly contacted with the inner hole at the bottom of the inner hole of the bolt;
the end cap is of a hollow structure, is provided with internal threads and is matched with the bolt threads to form an accommodating space;
the side wall of the end cap is provided with an end cap groove which is of a through groove structure, a signal wire is led out of the end cap groove, and the end cap groove is connected with an external transmitter and a signal acquisition system.
2. The multifunctional fastening property test bolt according to claim 1, characterized in that: and a lubricating layer is arranged between the upper plane of the end part of the sensitive unit and the end cap so as to reduce the friction force between the end cap and the sensitive unit.
3. The multifunctional fastening property test bolt according to claim 2, characterized in that: the lubricating layer is preferably made of ceramic, teflon and copper materials with strong lubricating property.
4. The multifunctional fastening property test bolt according to claim 1, characterized in that: the strain gauges are preferably 4 groups.
5. The multifunctional fastening property test bolt according to claim 1, characterized in that: the top end of the end cap is provided with a groove to form a fastening end, and a force application space of a screwing tool is provided.
6. The multifunctional fastening property testing bolt according to any one of claims 1 to 5, wherein: after the end cap is screwed with the bolt, the sensitive unit is connected with the bottom of the bolt through the column section and the guide section, and the stress of the sensitive unit is the pre-tightening force between the end cap and the bolt; when an external force acts on the bolt, the column section of the bolt is stretched, the column section of the sensitive unit releases a certain force, the stress of the sensitive unit is monitored in real time by the strain gauge on the sensitive unit, and the stress of the bolt can be tested.
CN202211003721.9A 2022-08-21 2022-08-21 Multifunctional fastening characteristic test bolt Pending CN115419646A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202211003721.9A CN115419646A (en) 2022-08-21 2022-08-21 Multifunctional fastening characteristic test bolt

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202211003721.9A CN115419646A (en) 2022-08-21 2022-08-21 Multifunctional fastening characteristic test bolt

Publications (1)

Publication Number Publication Date
CN115419646A true CN115419646A (en) 2022-12-02

Family

ID=84198213

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202211003721.9A Pending CN115419646A (en) 2022-08-21 2022-08-21 Multifunctional fastening characteristic test bolt

Country Status (1)

Country Link
CN (1) CN115419646A (en)

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