CN115389084A - Device and method for measuring bolt torque coefficient based on elastic force balance - Google Patents
Device and method for measuring bolt torque coefficient based on elastic force balance Download PDFInfo
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- CN115389084A CN115389084A CN202210937355.8A CN202210937355A CN115389084A CN 115389084 A CN115389084 A CN 115389084A CN 202210937355 A CN202210937355 A CN 202210937355A CN 115389084 A CN115389084 A CN 115389084A
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- 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
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Abstract
The application discloses a device and a method for measuring a bolt torque coefficient based on elastic force balance, and relates to the technical field of engineering machinery. The method has the advantages of less interference factors on measurement precision, simple operation and lower cost. The device comprises a connected piece, a supporting piece, a torque wrench and at least one elastic piece; the connected piece is positioned above the supporting piece, and the elastic piece is arranged between the connected piece and the supporting piece and provides downward elastic force for the supporting piece; the screw end of the bolt to be tested sequentially penetrates through the through holes on the connected piece and the supporting piece and then is fastened with the nut; the torque wrench is used for fastening the bolt to be measured and the nut and measuring a torque value when the bolt to be measured is fastened. The application also provides a method for measuring the torque coefficient of the bolt based on elastic force balance.
Description
Technical Field
The application relates to the technical field of engineering machinery, in particular to a device and a method for measuring a bolt torque coefficient based on elastic force balance.
Background
The bolt is used as a common fastener, is widely applied to the industrial fields of aerospace, railway transportation, ship turbines, civil manufacturing and the like due to the advantages of good connection performance, simplicity in disassembly and low cost, and is used for ensuring good connection performance or sealing effect. The bolt can be loosened in the working process due to the fact that the pre-tightening force is too small, so that machine failure is caused, the fatigue strength of the bolt is reduced due to the fact that the pre-tightening force is too large, and even the bolt can be broken in the working process. Therefore, how to accurately control the pretightening force of the bolt is always a technical problem in engineering.
In the bolt tightening process, the operation of a torque method is simplest, the practical application is very wide, and the bolt is tightened according to a formula T = KFD in engineering, wherein T represents an applied torque value, K represents a torque coefficient, F represents pretightening force, and D represents a nominal diameter of the bolt. But the core torque coefficient K is influenced by more factors such as the material of the connected piece, the thickness of the connected piece, the grade of a bolt, the grade of a gasket, the lubrication state, the surface roughness, the tightening speed, the ambient temperature and humidity, the tightening times and the like. In general, the K value varies from 0.100 to 0.450 depending on the screw connection method, the surface friction condition, and the quality of screw production. Therefore, the torque coefficient values of the bolts under different conditions are measured through experiments, the dispersion of the applied pretightening force of the torque method is reduced, and the method is significant for guiding how to accurately control the pretightening force of the bolts.
In the prior art, the pretightening force of the bolt is firstly measured by an ultrasonic method, an axial force sensor method or a strain gauge method, and then the torque coefficient value of the bolt is calculated. The ultrasonic method is characterized in that an ultrasonic probe special for pretightening force is arranged on a bolt head, and when ultrasonic waves emitted by the ultrasonic probe enter from one end of the bolt and are transmitted to the other end of the bolt, the ultrasonic waves are reflected on the end surface of the bolt and then transmitted back to the probe. Therefore, the ultrasonic method can calculate the elongation of the bolt by measuring the sound time difference of ultrasonic waves before and after the bolt is stressed, and then calculate the axial force applied to the bolt according to the relation between the axial force and the elongation. Because the method indirectly measures the elongation of the bolt before and after being stressed by the flight time of the ultrasonic waves in the bolt, the method is influenced by more interference factors such as a vacuum environment, a high-temperature environment and appearance of the surfaces of two ends of the bolt, the measurement precision is greatly influenced by the operation of an operator, and in addition, the measurement cost is higher due to higher price of an ultrasonic measuring instrument with high precision.
The axial force sensor method is characterized in that a stress area of the sensor is clamped between the bolt and the connected piece, when the bolt is tightened and stressed to stretch, pretightening force is applied to the stress area, and the sensor can measure the axial force of the bolt. The disadvantages of this method are: because the bolts to be measured need to pass through the middle holes of the axial force sensors to be installed and measured, bolts of different specifications need to be matched with axial force sensors of different models, and the measurement cost is high.
The strain gauge method is that resistance strain gauges are respectively adhered to the polished rod of the bolt to be measured, then the polished rod is arranged in a connected piece, the axial strain value of the bolt to be measured is measured, and the axial tension of the bolt is calculated according to the relation between the axial tension and the axial strain value. The disadvantages of this method are: a plurality of strain gauges need to be pasted on the surface of each bolt to be tested, the operation is troublesome, the preparation period is long, the test workload is large, the error of test measurement data is large, the precision is low, and the method is only suitable for single-piece small-batch inspection and measurement.
Disclosure of Invention
The embodiment of the application provides a device and a method for measuring a bolt torque coefficient based on elastic force balance, based on the relationship between spring force and pretightening force balance, the spring force, namely the pretightening force of a bolt, is obtained through calculation by measuring the compression amount of a compression spring arranged between a connected piece and a supporting piece, a preset torque value is applied through a torque wrench to tighten the bolt, and the bolt torque coefficient is calculated according to the fitted torque value and the pretightening force of the bolt.
In order to achieve the above objects, in one aspect, embodiments of the present application provide an apparatus for measuring a torque coefficient of a bolt based on elastic force balance, including a connected member, a supporting member, a torque wrench, and at least one elastic member; the connected piece is positioned above the supporting piece, and the elastic piece is arranged between the connected piece and the supporting piece and provides downward elastic force for the supporting piece; the screw rod end of the bolt to be tested sequentially penetrates through the through holes on the connected piece and the supporting piece and then is fastened with the nut; the torque wrench is used for fastening the bolt to be tested and the nut and measuring a torque value of the bolt to be tested during fastening.
Further, the connected piece comprises a first connected piece and a second connected piece which are stacked up and down.
Further, the elastic piece is a compression spring; and two ends of the compression spring are respectively abutted against the lower end face of the connected piece and the upper end face of the supporting piece.
Furthermore, compression spring is a plurality of, and is a plurality of compression spring is followed the circumference equipartition of bolt that awaits measuring is in the outside of bolt that awaits measuring.
Furthermore, a spring positioning hole is formed in the upper end face of the supporting piece, and the lower end of the compression spring is located in the spring positioning hole.
On the other hand, the embodiment of the application provides a testing method based on the device for measuring the torque coefficient of the bolt based on the elastic force balance, which comprises the following steps: s1, sequentially placing an elastic piece and a connected piece on a supporting piece from bottom to top, and sequentially penetrating a bolt to be detected through holes in the connected piece and the supporting piece; s2, measuring the distance l between the connected piece and the supporting piece before the bolt to be measured is fastened 1 (ii) a S3, fastening the bolt to be tested to a first preset torque value by using a torque wrench, and measuring the distance l between the fastened bolt to be tested and the supporting piece 2 (ii) a S4, calculating the bolt pretightening force F after the first preset torque value is applied through a formula 1; f = nK (l) 2 -l 1 ) Formula 1, wherein n is the number of compression springs; k is the stiffness of the compression spring and has the unit of N/mm; l 1 For the distance between the attached member and the supporting member before fastening,/ 2 The distance between the fastened connected piece and the supporting piece is in mm; s5, repeating the steps from S3 to S4 and gradually increasing the preset torque value to obtain bolt pretightening force corresponding to the preset torque values one by one; s6, fitting a relational expression T of the ideal torque value and the ideal bolt pretightening force according to the plurality of preset torque values and the corresponding bolt pretightening force n ＝CF n And calculating a constant C according to a formula 2;
formula 2, wherein T n Is any desired torque value in units of N "m; f n The ideal bolt pretightening force corresponding to Tn is expressed in the unit of N; s7, calculating a torque coefficient value k of the bolt to be tested through a formula 3;
and 3, wherein d is the nominal diameter of the bolt to be measured and has the unit of mm.
Further, the connected piece and the supporting piece in the step S1 are processed according to the specification of the bolt to be tested.
Compared with the prior art, the application has the following beneficial effects:
according to the embodiment of the application, the pre-tightening force of the bolt can be effectively measured only through the balance relation between the spring force and the pre-tightening force, and a relational expression between an ideal torque value and the ideal bolt pre-tightening force is fitted according to a plurality of preset torque values and the corresponding bolt pre-tightening force, so that the torque coefficient value of the bolt is calculated; compared with the prior art which highly depends on the measuring modes of various sensors, the test equipment of the embodiment of the application is simple, low in cost, simple to operate and directly effective.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic perspective view of an angle of a device for measuring a torque coefficient of a bolt based on elastic force balance according to an embodiment of the present disclosure;
FIG. 2 is a schematic perspective view of another angle of the device for measuring the torque coefficient of the bolt based on elastic force balance according to the embodiment of the present application;
FIG. 3 is a schematic perspective view of a support member in an apparatus for measuring a torque coefficient of a bolt based on elastic force balance according to an embodiment of the present disclosure
FIG. 4 is a front view of a support member of the apparatus for measuring a torque coefficient of a bolt based on elastic balance according to an embodiment of the present disclosure;
fig. 5 isbase:Sub>A sectional viewbase:Sub>A-base:Sub>A of fig. 4.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In the description of the present application, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be construed as limiting the present application.
In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; the specific meaning of the above terms in this application will be understood to be a specific case for those of ordinary skill in the art.
The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless otherwise specified.
Referring to fig. 1 and 2, the present embodiment provides an apparatus for measuring a torque coefficient of a bolt based on elastic force balance, which includes a first connected component 1, a second connected component 2, a supporting component 3, a torque wrench (not shown) and an elastic component. The middle parts of the first connected piece 1, the second connected piece 2 and the support piece 3 are all provided with through holes for the bolts 6 to be tested to pass through. The first connected piece 1, the second connected piece 2 and the support piece 3 are all processed according to the specification of the bolt 6 to be measured.
The first connected piece 1 and the second connected piece 2 are superposed up and down, so that the friction force between the first connected piece 1 and the second connected piece 2 after the two pieces are connected can be simulated, and the friction force is closer to the real working condition. The first attached member 1 and the second attached member 2 are both located above the support member 3.
The elastic member is provided between the second attached member 2 and the support member 3 and provides a downward elastic force to the support member 3. The screw end of the bolt 6 to be measured sequentially passes through the through holes in the first connected piece 1, the second connected piece 2 and the support piece 3 and then is fastened with the nut 4. The torque wrench is used for fastening the bolt 6 to be measured and the nut 4, and measuring a torque value when the bolt 6 to be measured is fastened.
In this embodiment, the elastic member adopts four compression springs 5, and the both ends of compression spring 5 butt respectively by the lower terminal surface of connecting piece 2 and the up end of support piece 3 of second, and four compression springs 5 along the circumference equipartition of the bolt 6 that awaits measuring in the outside of the bolt 6 that awaits measuring. In other embodiments, the elastic member may also be a compression spring, the inner diameter of the compression spring is larger than the outer diameter of the bolt 6 to be tested, the compression spring is sleeved on the bolt 6 to be tested, and two ends of the compression spring respectively abut against the lower end surface of the second connected member 2 and the upper end surface of the supporting member 3.
Referring to fig. 3 to 5, in order to facilitate installation and prevent the compression springs 5 from being displaced when compressed, in the present embodiment, four spring positioning holes 31 are provided on the upper end surface of the support 3, and the lower ends of the four compression springs 5 are respectively located in the corresponding spring positioning holes 31.
On the other hand, the embodiment of the application further provides a test method based on the device for measuring the torque coefficient of the bolt based on elastic balance, which comprises the following steps:
s1, sequentially placing a compression spring 5, a first connected piece 1 and a second connected piece 2 on a supporting piece 3 from bottom to top, and sequentially enabling a bolt 6 to be tested to pass through holes in the first connected piece 1, the second connected piece 2 and the supporting piece 3; the first connected piece 1, the second connected piece 2 and the support piece 3 are machined according to the specification of the bolt to be tested.
S2, measuring the distance l between the connected piece and the supporting piece 3 before the bolt 6 to be measured is fastened 1 ；
S3, fastening the bolt 6 to be tested to a first preset torque value by using a torque wrench, and measuring the distance l between the fastened bolt 6 to be tested and the supporting piece 3 2 ；
S4, calculating the bolt pretightening force F after the first preset torque value is applied through a formula 1;
F＝nK(l 2 -l 1 ) Equation 1
Wherein n is the number of the compression springs 5; k is the stiffness of the compression spring 5 in N/mm; l 1 For the distance between the second attached member 2 and the supporting member 3 before fastening, l 2 The distance between the second connected piece 2 and the support piece 3 after fastening is in mm;
s5, repeating the steps from S3 to S4 and gradually increasing the preset torque value to obtain bolt pretightening force corresponding to the preset torque values one by one;
s6, fitting a relational expression T of the ideal torque value and the ideal bolt pretightening force according to the plurality of preset torque values and the corresponding bolt pretightening force n ＝CF n And solving a constant C according to a formula 2;
wherein, T n Is any desired torque value in units of N "m; f n The ideal bolt pretightening force corresponding to Tn is expressed in the unit of N;
s7, calculating a torque coefficient value k of the bolt 6 to be tested through a formula 3;
where d is the nominal diameter of the bolt 6 to be measured in mm, where the nominal diameter of the bolt 6 to be measured is obtained by measurement.
The above is only an embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions within the technical scope of the present disclosure should be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (7)
1. The device for measuring the torque coefficient of the bolt based on the elastic force balance is characterized by comprising a connected piece, a supporting piece, a torque wrench and at least one elastic piece; the connected piece is positioned above the supporting piece, and the elastic piece is arranged between the connected piece and the supporting piece and provides downward elastic force for the supporting piece; the screw rod end of the bolt to be tested sequentially penetrates through the through holes on the connected piece and the supporting piece and then is fastened with the nut; the torque wrench is used for fastening the bolt to be tested and the nut and measuring a torque value of the bolt to be tested during fastening.
2. The device for measuring the torque coefficient of the bolt based on the elastic force balance is characterized in that the connected piece comprises a first connected piece and a second connected piece which are arranged on top of each other.
3. The device for measuring the torque coefficient of the bolt based on the elastic force balance as claimed in claim 1, wherein the elastic member is a compression spring; and two ends of the compression spring are respectively abutted against the lower end face of the connected piece and the upper end face of the supporting piece.
4. The device for measuring the torque coefficient of the bolt based on the elastic force balance is characterized in that the number of the compression springs is multiple, and the compression springs are uniformly distributed on the outer side of the bolt to be measured along the circumferential direction of the bolt to be measured.
5. The device for measuring the torque coefficient of the bolt based on the elastic force balance is characterized in that a spring positioning hole is formed in the upper end face of the supporting piece, and the lower end of the compression spring is located in the spring positioning hole.
6. A method for testing the device for measuring the torque coefficient of the bolt based on the elastic force balance according to any one of claims 1 to 5, which is characterized by comprising the following steps:
s1, sequentially placing an elastic piece and a connected piece on a supporting piece from bottom to top, and sequentially penetrating a bolt to be detected through holes in the connected piece and the supporting piece;
s2, measuring the distance l between the connected piece and the supporting piece before the bolt to be measured is fastened 1 ；
S3, fastening the bolt to be tested to a first preset torque value by using a torque wrench, and measuring the distance l between the fastened bolt to be tested and the supporting piece 2 ；
S4, calculating the bolt pretightening force F after the first preset torque value is applied through a formula 1;
F＝nK(l 2 -l 1 ) Equation 1
Wherein n is the number of compression springs; k is the stiffness of the compression spring and has the unit of N/mm; l 1 For the distance between the attached member and the supporting member before fastening,/ 2 The distance between the fastened connected piece and the supporting piece is in mm;
s5, repeating the steps from S3 to S4 and gradually increasing the preset torque value to obtain bolt pretightening force corresponding to the preset torque values one by one;
s6, fitting a relational expression T of the ideal torque value and the ideal bolt pretightening force according to the plurality of preset torque values and the corresponding bolt pretightening force n ＝CF n And solving a constant C according to a formula 2;
wherein, T n Is any desired torque value in units of N "m; f n Is T n The unit of the corresponding ideal bolt pretightening force is N;
s7, calculating a torque coefficient value k of the bolt to be tested through a formula 3;
wherein d is the nominal diameter of the bolt to be measured, and the unit is mm.
7. The method according to claim 6, wherein the connected piece and the supporting piece in the step S1 are processed according to the specification of the bolt to be tested.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210937355.8A CN115389084A (en) | 2022-08-05 | 2022-08-05 | Device and method for measuring bolt torque coefficient based on elastic force balance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210937355.8A CN115389084A (en) | 2022-08-05 | 2022-08-05 | Device and method for measuring bolt torque coefficient based on elastic force balance |
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| Publication Number | Publication Date |
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| CN115389084A true CN115389084A (en) | 2022-11-25 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210937355.8A Pending CN115389084A (en) | 2022-08-05 | 2022-08-05 | Device and method for measuring bolt torque coefficient based on elastic force balance |
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|---|---|
| CN (1) | CN115389084A (en) |
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2022
- 2022-08-05 CN CN202210937355.8A patent/CN115389084A/en active Pending
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