阅读说明：本技术 一种螺栓拧紧方法 (Bolt tightening method ) 是由 狄志慧 张博譞 伊丽花 于 2020-04-26 设计创作，主要内容包括：本发明提供一种螺栓拧紧方法,包括(1)建立横纵坐标；(2)设定起始扭矩值；(3)拧紧NOS角度值并计算该NOS角度值区间内的扭矩的平均值Ta；拧紧INC角度值；拧紧第二个NOS角度值并计算平均值Tb；(4)得到理论线性拉伸区角度起始值X-(1)和终点对应的角度值为X-(2),从第二个NOS角度值终点继续旋转拧紧A-(X-(2)-X-(1)),同时记录最终扭矩值；(5)基于预定试验次数的拧紧数据,对最终扭矩值进行统计学分布分析,设定最终扭矩阈值范围,当实际最终扭矩值落入阈值范围判定拧紧合格,如果超出阈值范围即判定拧紧不合格。本发明可精确控制螺栓拧紧后的最终预紧力,最大限度的消除传统拧紧方法中螺栓及夹紧件的摩擦系数对最终预紧力的影响,更好的实现预紧力的控制。(The invention provides a bolt tightening method, which comprises the steps of (1) establishing a horizontal coordinate and a vertical coordinate; (2) setting a starting torque value; (3) tightening an NOS angle value and calculating the average value Ta of the torque in the NOS angle value interval; tightening the INC angle value; tightening the second NOS angle value and calculating an average value Tb; (4) obtaining the initial value X of the angle of the theoretical linear stretching area 1 The angle value corresponding to the end point is X 2 Continuing to screw A- (X) from the second NOS angle value end point 2 ‑X 1 ) Simultaneously recording the final torque value; (5) and performing statistical distribution analysis on the final torque value based on the tightening data of the preset test times, setting a final torque threshold range, judging that the tightening is qualified when the actual final torque value falls into the threshold range, and judging that the tightening is unqualified if the actual final torque value exceeds the threshold range. The invention can accurately control the final pretightening force of the screwed bolt, eliminate the influence of the friction coefficient of the bolt and the clamping piece on the final pretightening force in the traditional screwing method to the maximum extent and better realize the control of the pretightening force.)

1. A bolt tightening method, characterized by comprising the steps of:

(1) establishing a horizontal coordinate and a vertical coordinate, wherein the horizontal coordinate is an angle, the vertical coordinate is a torque, drawing a bolt tightening curve in the horizontal coordinate and the vertical coordinate, and determining a fitting point on the bolt tightening curve;

(2) setting a starting torque value, wherein the starting torque value is larger than a corresponding torque value at a joint point;

(3) when the actual torque value is larger than the initial torque value, the screwing equipment is used for screwing one NOS angle value in a rotating mode, and the average value Ta of the torque in the NOS angle value interval is calculated; then the screwing device rotates to screw the INC angle value; then screwing the equipment and then screwing a second NOS angle value in a rotating manner, and calculating the average value Tb of the torque in the NOS angle value interval;

(4) connecting Ta and Tb with a straight line, intersecting a reverse extension line with a horizontal coordinate to obtain an angle initial value X of a theoretical linear stretching area₁(ii) a The angle value corresponding to the bolt extending to the second NOS angle value end point is X₂The tightening device continues to rotate and tighten A- (X) from the second NOS angle value end point₂-X₁) Simultaneously recording the final torque value, wherein A is the theoretical value of the tightening angle；

(5) And performing statistical distribution analysis on the final torque value based on the tightening data of the preset test times, setting a final torque threshold range, judging that the tightening is qualified when the actual final torque value falls into the threshold range, and judging that the tightening is unqualified if the actual final torque value exceeds the threshold range.

2. A bolt tightening method, characterized by comprising the steps of:

(1) establishing a horizontal coordinate and a vertical coordinate, wherein the horizontal coordinate is an angle, the vertical coordinate is a torque, drawing a bolt tightening curve in the horizontal coordinate and the vertical coordinate, and determining a fitting point on the bolt tightening curve;

(2) setting a starting torque value, wherein the starting torque value is larger than a corresponding torque value at a joint point;

(3) when the actual torque value is larger than the initial torque value, the screwing device rotates to screw the NOS angle values for N times, the INC angle values are screwed for one time between every two adjacent NOS angle values, and the average value T of the torque in each NOS angle value interval is calculated_N；N≥3；

(4) Will T₁、T₂Up to T_NPerforming linear fitting on the multiple points, and intersecting the reverse extension line with the abscissa to obtain an angle initial value X of a theoretical linear stretching area₁(ii) a The angle value corresponding to the terminal point of the angle value of the Nth NOS drawn by the bolt is X_NThe screwing device continues to rotate and screw A- (X) from the Nth NOS angle value end point_N-X₁) Simultaneously recording a final torque value, wherein A is a theoretical value of a tightening angle;

(5) and performing statistical distribution analysis on the final torque value based on the tightening data of the preset test times, setting a final torque threshold range, judging that the tightening is qualified when the actual final torque value falls into the threshold range, and judging that the tightening is unqualified if the actual final torque value exceeds the threshold range.

3. The bolt tightening method according to claim 1 or 2, wherein the NOS angle value is determined based on the length of the linear segment of the tightening curve and statistical distribution analysis of tightening data.

4. The bolt tightening method according to claim 1 or 2, wherein the INS angle value is determined from the length of the linear segment of the tightening curve and a statistical distribution analysis of tightening data.

5. The bolt tightening method according to claim 1 or 2, characterized in that the NOS angle value is not equal to the INS angle value.

6. The bolt tightening method according to claim 1 or 2, characterized in that the calculation formula of the tightening angle theoretical value a is:

wherein A is a theoretical value of a screwing angle, F is a pre-tightening force required by the bolt, E is an elastic modulus of a bolt material, S is a cross-sectional area of the bolt, and P is a thread pitch of the bolt.

7. The bolt tightening method according to claim 1 or 2, wherein in step (5), when it is determined that the tightening is not satisfactory, the tightening apparatus issues an alarm signal announcing the failure of the tightening.

8. The bolt tightening method according to claim 1, wherein A- (X)₂-X₁) Positive values.

9. The bolt tightening method according to claim 2, wherein A- (X)_N-X₁) Positive values.

Technical Field

The invention relates to a threaded connection technology, in particular to a bolt tightening method.

Background

The axial force of the bolt is to screw the nut so that the bolt is screwed into the threaded hole according to the thread of the bolt, and the elastic force generated by the bolt in the elastic interval is the pretightening force of the bolt. Because the pretightening force can not be intuitively controlled and monitored, the pretightening force after the bolt is screwed is indirectly controlled in a mode of controlling torque or angle in production.

The method generally adopted at present comprises a pure torque control method and a torque angle control method, the bolt pretightening force of the torque angle control method is more accurate than that of the pure torque control method, but the torque control is adopted in part of the tightening processes of the two methods, the torque control pretightening force is influenced by a friction coefficient to a great extent, and due to the limitation of the production process, the friction coefficient cannot be well controlled, so that the pretightening force of the tightened bolt in the actual production has larger deviation.

In view of the above, the inventor of the present invention breaks through the limitation that the conventional bolt tightening method is affected by the friction coefficient, and provides a more accurate and stable tightening method for the manufacturing industry in the control of the key bolt pre-tightening force.

Disclosure of Invention

The invention aims to eliminate the influence of the friction coefficient of a bolt and a clamping piece on the final pretightening force in the traditional screwing method to the maximum extent, and provides a more accurate and stable bolt screwing method for the control of the key bolt pretightening force in the manufacturing industry.

To achieve the above object, the present invention provides a bolt tightening method, which includes the steps of:

(1) establishing a horizontal coordinate and a vertical coordinate, wherein the horizontal coordinate is an angle, the vertical coordinate is a torque, drawing a bolt tightening curve in the horizontal coordinate and the vertical coordinate, and determining a fitting point on the bolt tightening curve;

(2) setting a starting torque value, wherein the starting torque value is larger than a corresponding torque value at a joint point;

(3) when the actual torque value is larger than the initial torque value, the screwing equipment is used for screwing one NOS angle value in a rotating mode, and the average value Ta of the torque in the NOS angle value interval is calculated; then the screwing device rotates to screw the INC angle value; then screwing the equipment and then screwing a second NOS angle value in a rotating manner, and calculating the average value Tb of the torque in the NOS angle value interval;

(4) connecting Ta and Tb with a straight line, intersecting a reverse extension line with a horizontal coordinate to obtain an angle initial value X of a theoretical linear stretching area₁(ii) a The angle value corresponding to the bolt extending to the second NOS angle value end point is X₂The tightening device continues to rotate and tighten A- (X) from the second NOS angle value end point₂-X₁) Simultaneously recording a final torque value, wherein A is a theoretical value of a tightening angle;

(5) and performing statistical distribution analysis on the final torque value based on the tightening data of the preset test times, setting a final torque threshold range, judging that the tightening is qualified when the actual final torque value falls into the threshold range, and judging that the tightening is unqualified if the actual final torque value exceeds the threshold range.

The invention also provides a bolt tightening method, which comprises the following steps:

(1) establishing a horizontal coordinate and a vertical coordinate, wherein the horizontal coordinate is an angle, the vertical coordinate is a torque, drawing a bolt tightening curve in the horizontal coordinate and the vertical coordinate, and determining a fitting point on the bolt tightening curve;

(2) setting a starting torque value, wherein the starting torque value is larger than a corresponding torque value at a joint point;

(3) when the actual torque value is larger than the initial torque value, the screwing device rotates to screw the NOS angle values for N times, the INC angle values are screwed for one time between every two adjacent NOS angle values, and the average value T of the torque in each NOS angle value interval is calculated_N；N≥3；

(4) Will T₁、T₂Up to T_NPerforming linear fitting on the multiple points, and intersecting the reverse extension line with the abscissa to obtain an angle initial value X of a theoretical linear stretching area₁(ii) a The angle value corresponding to the terminal point of the angle value of the Nth NOS drawn by the bolt is X_NThe screwing device continues to rotate and screw A- (X) from the Nth NOS angle value end point_N-X₁) Simultaneously recording a final torque value, wherein A is a theoretical value of a tightening angle;

(5) and performing statistical distribution analysis on the final torque value based on the tightening data of the preset test times, setting a final torque threshold range, judging that the tightening is qualified when the actual final torque value falls into the threshold range, and judging that the tightening is unqualified if the actual final torque value exceeds the threshold range.

According to the bolt tightening method, the NOS angle value is determined according to the length of a tightening curve linear segment and the statistical distribution analysis of tightening data.

According to the bolt tightening method, the INS angle value is determined according to the length of a tightening curve linear segment and the tightening data statistical distribution analysis.

In the bolt tightening method, the NOS angle value is not equal to the INS angle value.

The bolt tightening method comprises the following steps of:

wherein A is a theoretical value of a screwing angle, F is a pre-tightening force required by the bolt, E is an elastic modulus of a bolt material, S is a cross-sectional area of the bolt, and P is a thread pitch of the bolt.

In the bolt tightening method, in the step (5), when it is determined that the tightening is not satisfactory, the tightening device issues an alarm signal to declare a tightening failure.

The bolt tightening method described above, wherein A- (X)₂-X₁) Positive values.

The bolt tightening method described above, wherein A- (X)_N-X₁) Positive values.

The invention has the beneficial effects that: according to the invention, the full-angle control of bolt tightening is realized by calculating the rotating angle component of the pretightening force generated by the bolt at the initial stage of bolt tightening, the pretightening force of the bolt can be more accurately controlled, and a brand-new tightening method is provided for bolt tightening in the manufacturing industry. The method can be widely applied to the manufacturing industry, the final pretightening force of the screwed bolt can be accurately controlled by the method, the influence of the friction coefficient of the bolt and the clamping piece on the final pretightening force in the traditional screwing method is eliminated to the maximum extent, and the pretightening force is better controlled.

Drawings

FIG. 1 is a schematic illustration of a bolt tightening curve in the torque + angle method;

fig. 2 is a schematic view of a bolt tightening curve according to the projected angle method of the present invention.

Detailed Description

Before setting forth the technical solutions of the present invention, several basic concepts in the art are described.

The torque tightening method and the torque + angle method are most widely used in the manufacturing process of the automobile engine, and compared with the torque tightening method, the torque + angle method reduces the influence of friction on pretightening force and can obtain more stable axial force. However, in either the Torque tightening method or the Torque + angle method, all or part of the tightening process is controlled by Torque, i.e., Threshold Torque (T) T exists_T。

Specifically, refer to fig. 1, which is a schematic diagram of a torque + angle bolt tightening curve. Threshold torque T_TNeeds to fall within the Elastic Clamping interval and be larger than the fitting point P_STorque at (Snag Point). At threshold torque T_TThe previous, commonly referred to as the "torque method stage", generates axial forces that are related to material stiffness, coefficient of friction, and size; at threshold torque T_TTo total Torque (Resultant Torque) T_RThe "angle method stage" is usually called between, and the generated axial force is related to the material rigidity and the size, in other words, the effect of the friction coefficient is not obvious in the "angle method stage".

Therefore, the pretightening force is controlled through the Torque, the pretightening force is influenced by the friction coefficient to a great extent, the friction coefficient cannot be well controlled due to the limitation of the production process, so that the pretightening force after the bolt is screwed in the actual production has larger deviation, and meanwhile, the larger the Threshold Torque (Threshold Torque), the larger the influence caused by friction is.

About the point of contact P_S: the screw, which is not initially tightened, does not provide a preload force and needs to be screwed in with a low torque, overcoming the friction. In the process of screwing in, the opponentThe gap between the mating surfaces of the members is gradually eliminated until the mating surfaces are fully engaged at a point, referred to as the engagement point P_S. As shown in FIG. 1, in the abscissa and ordinate, the abscissa is the angle A, the ordinate is the torque T, and the contact point P is_SOn the bolt tightening curve and the fitting point P_SCalculated according to statistical distribution analysis. During the tightening process of the bolt, once the tightening torque is more than or equal to the fitting point P_SThe stretching moment T and the rotation angle A form a theoretical linear relation, and the slope is K.

Theoretical value a for the tightening angle: assuming that the bolt is stretched from the beginning and the mating surfaces between the counter-elements are already fitted, the bolt directly enters the elastic linear stretching region from the beginning until the Yield Point P is reached_YBefore, the tightening angle and the pretightening force form a theoretical linear relation. A calculation formula of a theoretical value A of a tightening angle:

wherein A is a theoretical value of a screwing angle, F is a pre-tightening force required by the bolt, E is an elastic modulus of a bolt material, S is a cross-sectional area of the bolt, and P is a thread pitch of the bolt.

In practical application, considering batch and individual difference of bolts, theoretical values are referred, statistical distribution is utilized to calculate and analyze and correct calculated values based on data statistical results of a large amount of actual final pretightening force, and a reasonable bolt tightening angle value A in a linear area is finally given so as to obtain ideal final pretightening force F.

The invention will be further explained with reference to the drawings. Based on the description of the above concept, in order to eliminate the discrete influence of the difference in friction coefficient and the like at the initial stage of the torque tightening method in tightening, in other words, in order to eliminate the threshold torque T_TThe invention discloses a novel bolt tightening Method, namely a projection Angle Method (PA Method for short), by utilizing the calculation and analysis functions of automatic tightening equipment.

Please refer to fig. 2, which is based onA schematic diagram of a bolt tightening curve of the projected angle method of the present invention. Based on statistical distribution analysis of a certain amount of tightening data, a horizontal ordinate and a vertical ordinate are established, wherein the horizontal coordinate is an angle A, and the vertical coordinate is a torque T. And drawing a bolt tightening curve according to the angle and the torque change in the actual tightening process in the horizontal and vertical coordinates. Due to the sticking point P_SRepresents the position where the matching surface of the bolt is completely jointed in the screwing process, so that the jointing point P_SIs positioned on the bolt tightening curve. Calculating the attaching point P according to statistical distribution analysis_SDetermining a fitting point P on a bolt tightening curve_SSetting a value greater than the fitting point P_SAnd (3) processing a torque value TC corresponding to the torque value, and after the actual torque value T is greater than the TC, the tightening equipment rotates and tightens an NOS angle value (preset angle value), wherein the NOS angle value is determined according to the length of a linear section of a tightening curve and the statistical distribution analysis of tightening data, and the average value Ta of the torque in the NOS interval is calculated by using a computer. Subsequently, the tightening device is rotated to tighten an INC angle value (incremental angle value), it should be noted that the INC angle value is determined in the same manner as the NOS angle value, but preferably, the INC angle value is not equal to the NOS angle value, so that the calculation result is more accurate. Then, the tightening device rotates to tighten a second NOS angle value, similarly, the computer is used for calculating the average value Tb of the torque in the NOS interval, the computer connects the Ta and the Tb value to form a straight line, the reverse extension line is intersected with the abscissa, and the starting value X of the theoretical linear stretching zone angle is obtained₁(the torque is zero at this time). Starting value X of angle of theoretical linear stretching zone obtained by regression because the torque is zero₁It is actually the starting point of the theoretical value a of the tightening angle, i.e. the starting point of the entry of the bolt into the elastic linear stretch zone.

The angle value corresponding to the bolt extending to the second NOS angle value end point is X₂I.e. the theoretical linear stretch zone angle end point value X₂，X₂-X₁For the angle at which the bolt has finished stretching on the theoretical linear stretch curve, the tightening device then continues to rotate the tightening a- (X) at the second NOS end₂-X₁) While recording the final torque value T_FThe whole bolt tightening process is completed, which is equivalent to completely tightening the boltThe linear region is tightened for the full angle a.

Likewise, the final torque value T is calculated based on a certain amount of tightening data_FAnd carrying out statistical distribution analysis, setting a reasonable final tightening torque threshold range, judging that the tightening is qualified when the actual final torque value falls into the threshold range, otherwise, judging that the tightening is unqualified when the actual final torque value exceeds the threshold range, and sending an alarm signal by tightening equipment to declare the tightening failure.

In addition, the present invention also provides an embodiment comprising the steps of:

(1) establishing a horizontal coordinate and a vertical coordinate, wherein the horizontal coordinate is an angle, the vertical coordinate is a torque, and determining a fitting point in the horizontal coordinate and the vertical coordinate;

(2) setting a starting torque value, wherein the starting torque value is larger than a corresponding torque value at a joint point;

(3) when the actual torque value is larger than the initial torque value, the screwing device rotates to screw the NOS angle values for N times, the INC angle values are screwed for one time between every two adjacent NOS angle values, and the average value T of the torque in each NOS angle value interval is calculated_N；N≥3；

(4) Will T₁、T₂Up to T_NPerforming linear fitting on the multiple points, and intersecting the reverse extension line with the abscissa to obtain an angle initial value X of a theoretical linear stretching area₁(ii) a The angle value corresponding to the terminal point of the angle value of the Nth NOS drawn by the bolt is X_NThe screwing device continues to rotate and screw A- (X) from the Nth NOS angle value end point_N-X₁) Simultaneously recording a final torque value, wherein A is a theoretical value of a tightening angle;

(5) and performing statistical distribution analysis on the final torque value based on the tightening data of the preset test times, setting a final torque threshold range, judging that the tightening is qualified when the actual final torque value falls into the threshold range, and judging that the tightening is unqualified if the actual final torque value exceeds the threshold range.

In conclusion, the invention has the following beneficial effects: according to the invention, the full-angle control of bolt tightening is realized by calculating the rotating angle component of the pretightening force generated by the bolt at the initial stage of bolt tightening, the pretightening force of the bolt can be more accurately controlled, and a brand-new tightening method is provided for bolt tightening in the manufacturing industry. The method can be widely applied to the manufacturing industry, the final pretightening force of the screwed bolt can be accurately controlled by the method, the influence of the friction coefficient of the bolt and the clamping piece on the final pretightening force in the traditional screwing method is eliminated to the maximum extent, and the pretightening force is better controlled.

While the invention has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the technical features mentioned in the embodiments can be combined in any way as long as there is no structural conflict. It is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.