Rotary drive device for fastening components

Abstract

To provide a rotary drive device for fastening components and a control method related to the yield point method that can appropriately and rationally perform bolt tightening while employing the yield point method. [Solution] The rotation angle of the fastening component (nut or bolt) and the torque applied to the nut detected by the sensor unit 140 are acquired periodically. Based on the acquired detection results, the torque application unit 130 controls the bolt tightening operation based on the change in the torque change gradient value (Vn=ΔTn / Δθn), which is the ratio of the estimated increase (=ΔTn(=Tn+p-Tn)) of the applied torque (Tn+p) at the (n+p) time from the applied torque (Tn) at the nth time, with respect to the estimated change (=Δθn(=θn+p-θn)) of the nut rotation angle between the nth time (n=1,2,...) time and the (n+p(p is a predetermined natural number of 2 or more)).

Description

Technical Field

[0001] The present invention relates to a rotational drive device for fastening components and a control method related to the proof stress method.

Background Art

[0002] Conventionally, when constructing bridges and the like, high-strength bolts are tightened. As such tightening methods, the so-called torque method and proof stress method (torque gradient method) and the like are adopted. Here, in the implementation of the torque method, a standard torque coefficient for the high-strength bolts used is obtained through experiments and the like, and using this torque coefficient, the rotation drive of the nut is performed until the torque value estimated to be near the yield point (the change point from the elastic region to the plastic region of the deformation in the axial direction of the bolt) is reached. Such a torque coefficient during tightening changes depending on the storage condition of the high-strength bolts. Therefore, in tightening by the torque method, relatively large variations are predicted for the introduced axial force in the actual tightening result, and manual additional tightening has been performed at about 10%.

[0003] On the other hand, in the proof stress method, since the rate of change of the applied torque to the nut with respect to the change in the rotation angle of the nut is utilized, which gradually decreases as the plastic change progresses after changing from the elastic region to the plastic region of the deformation in the axial direction of the high-strength bolt, it is possible to perform tightening up to near the yield point without using the torque coefficient, although it will exceed the yield point. Therefore, a larger axial force can be introduced than in the torque method, and the variation in the introduced axial force can be reduced. For this reason, additional tightening is basically unnecessary.

[0004] As a technique for this type of load-bearing point method, a technique has been proposed in which, after the tightening state has passed the snug point, the load-bearing point is defined as the point at which the rate of change of the tightening torque applied to the nut in response to the change in tightening rotation angle reaches a predetermined value and then decreases after reaching a predetermined value, and the tightening operation is terminated (see Patent Document 1; hereinafter referred to as "conventional example"). In this conventional example, the tightening torque value is detected each time the rotation angle changes by a predetermined amount. Subsequently, the rate of change of the tightening torque value in response to the change in the predetermined rotation angle is calculated. Then, when this rate of change reaches a predetermined percentage after reaching a maximum value during bolt tightening in progress, the tightening operation for the high-strength bolt being tightened is terminated. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 61-033871 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In the conventional technology described above, the tightening torque value is acquired each time the rotation angle changes by a predetermined amount, and the rate of change of the tightening torque value with respect to that predetermined rotation angle change is calculated. However, the change by the predetermined rotation angle and the detected tightening torque value contain detection errors. Furthermore, it is possible that there may be fluctuations (pulsations), although not with a large amplitude, in the change in the rate of change. As a result, it is possible that misjudgments may occur, such as judging that the predetermined percentage has been reached before it has been reached, or that the tightening of the high-strength bolt in the plastic region may progress to an unintended extent.

[0007] This invention has been made in view of the above circumstances, and aims to provide a rotary drive device for fastening components and a control method related to the yield point method that can appropriately and rationally perform bolt tightening while employing the yield point method. [Means for solving the problem]

[0008] The first method is, A rotary drive device for rotating one of the fastening components, either a high-strength bolt or a nut, when tightening a high-strength bolt, A torque application unit that applies torque to one of the fastening components; A sensor unit for detecting the rotation angle of one of the fastening components and the torque applied to the one fastening component; The system includes a control unit that periodically acquires detection results from the sensor unit and controls the torque application unit based on the acquired detection results; The control unit estimates the change in the rotation angle (=Δθn (=θn+p-θn)) between the nth (n=1,2,...)th time and the (n+p (p is a predetermined natural number of 2 or more)) The applied torque (Tn+p) in the (n+p)th instance is the same as the nth instance. The torque application unit controls the bolt tightening operation based on the change in the torque change gradient value (Vn = ΔTn / Δθn), which is the ratio of the estimated increase (= ΔTn (= Tn + p - Tn)) from the applied torque (Tn). It is configured in such a way, The torque application unit applies torque to the one fastening component while maintaining the rotational speed of the one fastening component. The control unit is At predetermined time intervals, the rotation angle of one of the fastening components and the torque applied to the one fastening component are acquired. When the ratio (Vn / VMAX) of the torque change gradient value (Vn) to the maximum value (VMAX) after the start of the bolt tightening operation falls below a predetermined value, the torque application unit is instructed to terminate the bolt tightening operation. It is characterized by the following:

[0009] The second method is, in the first method, The predetermined value is a value selected in advance from within the range of 0.6 to 0.9. It is characterized by the following: [Effects of the Invention]

[0014] According to the first method, the control unit calculates a torque change gradient value (Vn=ΔTn / Δθn), which is the ratio of the estimated increase (=ΔTn(=Tn+p-Tn)) of the applied torque (Tn+p) at the (n+p)th time detected by the sensor unit from the applied torque (Tn) at the nth time, to the estimated change (=Δθn(=θn+p-θn)) of the nut rotation angle (θn,θn+p) detected by the sensor unit between the nth (n=1,2,...)th time and the n+p (p is a predetermined natural number of 2 or more). Then, based on the change in the change gradient value (Vn), the control unit controls the bolt tightening operation by the torque application unit.

[0015] Therefore, the detection error of the nut rotation angle (θn, θn+1P) and applied torque (Tn, Tn+p) used to calculate the torque change gradient value (Vn) has an effect on the calculation result of the torque change gradient value (Vn) that is reduced by about (1 / p) compared to the conventional example, while still allowing calculation each time the rotation angle of the high-strength bolt or nut changes by an amount Δθ (=θn+1-θn), similar to the conventional example. In addition, the effect of the so-called wavering mentioned above can also be reduced compared to the conventional example due to the averaging effect.

[0016] Therefore, the torque change gradient value (Vn) can be calculated accurately and rationally, and consequently, high-strength bolt tightening can be performed appropriately and rationally while employing the yield strength point method.

[0019] Also, the first means According to the system, when the torque application unit applies torque to a high-strength bolt or nut while maintaining the rotational speed of the bolt or nut, the control unit acquires the rotation angle of the high-strength bolt or nut and the torque applied to the bolt or nut at predetermined time intervals. The control unit then instructs the torque application unit to terminate the bolt tightening operation when the ratio of the torque change gradient value (=Vn) to the maximum value (=VMAX) after the start of the bolt tightening operation (=Vn / VMAX) falls below a predetermined value. In this way, the bolt tightening operation can be terminated appropriately and rationally while employing the load-bearing point method.

[0020] Second method According to this, the predetermined value is a value preselected from within the range of 0.6 to 0.9. As described above, when the predetermined value is large, the occurrence of a situation where the bolt tightening operation ends before the axial force of the high-strength bolt reaches the allowable range increases. On the other hand, when the predetermined value is small, the occurrence of a situation where the deformation in the plastic region of the high-strength bolt progresses to an extent not assumed increases. According to the knowledge obtained by the inventor's research and development, by selecting and adopting the predetermined value from within the range, for example, in the tightening of high-strength bolts frequently used in bridge construction, for multiple types of high-strength bolts, the endurance point method can be adopted relatively generally and appropriately perform high-strength bolt tightening.

Brief Explanation of Drawings

[0023] [Figure 1] It is a diagram for explaining the outline of the endurance point tightening method. [Figure 2] It is a diagram showing the functional configuration of a nut rotation drive device according to an embodiment of the present invention. [Figure 3] It is a flowchart for explaining the nut rotation drive process executed by the processing control unit in FIG. 2. [Figure 4] It is a flowchart for explaining the nut rotation process in FIG. 3. [Figure 5] It is a diagram showing an example of the mode of acquisition of the detection result and calculation of the torque change gradient value during the nut rotation drive process executed by the processing control unit in FIG. 2.

Mode for Carrying Out the Invention

[0024] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 5. In the following description and drawings, the same elements are denoted by the same reference numerals, and duplicate explanations are omitted.

[0025] [Regarding the Endurance Point Tightening Method] Prior to the specific description of an embodiment, the outline of the "endurance point tightening method (torque gradient method)" will be described with reference to FIG. 1.

[0026] As the nut that screws onto the high-strength bolt is rotated to tighten the bolt, the torque T required for tightening (=F(θ) (hereinafter also simply referred to as "torque T")) applied to the nut increases in proportion to the increase in the rotation angle θ of the nut, as shown comprehensively in Figures 1(A) and 1(B). The torque T then reaches the so-called snug point (the point at which the tightening torque necessary to bring the seating surfaces into close contact is applied: the rotation angle θ of the nut = θS) without changing significantly. After that, as the rotation continues, the torque T required for tightening changes more significantly in proportion to the increase in the rotation angle θ. Then, as shown in Figure 1(B), the rate of change V of torque T with respect to the change in rotation angle θ quickly approaches its maximum value VMAX.

[0027] Subsequently, in the region where the axial deformation of the high-strength bolt becomes elastic (hereinafter simply referred to as the "elastic region"), the rate of change V remains near its maximum value VMAX. After the yield point (nut rotation angle θ = θG), where the elastic axial deformation of the high-strength bolt reaches its limit, the rate of change V gradually decreases in proportion to the increase in the rotation angle θ.

[0028] The "load-bearing point tightening method" is a bolt tightening method that manages bolt tightening by utilizing the pattern of change in this rate of change (i.e., the "torque change gradient value") V. In this "load-bearing point tightening method," the torque T is detected when the rotation angle θ of the nut has increased by a predetermined value since the last acquisition, and a new rate of change V is calculated. Then, the point at which the new rate of change V becomes a predetermined ratio R (<1) relative to the maximum value VMAX of the rate of change up to that point is determined to be the end of load-bearing point tightening (see Figure 1(B)), and the rotation drive of the nut is stopped. The predetermined ratio R is determined in advance through experiments, simulations, experience, etc., from the viewpoint of ensuring effective bolt tightening.

[0029] [composition] Next, the configuration of a nut rotation drive device 100 according to one embodiment will be described.

[0030] Figure 2 shows the functional configuration of the nut rotation drive device 100 in a block diagram. In the following explanation, the nut rotation drive device 100 will be described assuming that the bolt tightening work is performed on the connecting section of a bridge girder (plate girder) that makes up a large bridge with a total length of several hundred meters, and that bolt tightening is performed on the said bolt tightening work target OBJ.

[0031] In this embodiment, the OBJ to which the bolt tightening work is performed is a structure in which high-strength hexagonal bolts BLT (hereinafter also simply referred to as "bolts") are tightened via the first connecting plate CP1 and the second connecting plate CP2 at the joint where the first bridge girder BG1 and the second bridge girder BG2 are joined. The tightening is performed by sequentially passing the high-strength hexagonal bolt BLT through the washer WS1, the first connecting plate CP1, the bridge girder BG1 or bridge girder BG2, the second connecting plate CP2 and the washer WS2 in the Z-axis direction, and then screwing a nut NT onto the protruding portion on the Z-axis side of the high-strength hexagonal bolt BLT and tightening it.

[0032] As shown in Figure 2, the nut rotation drive device 100 includes a processing control unit 110 including a timing mechanism, a storage unit 120, a torque application unit 130, and a sensor unit 140. The nut rotation drive device 100 also includes an operation input unit 150, a display unit 160, and a sound output unit 170.

[0033] The processing control unit 110 is comprised of a central processing unit (CPU) and peripheral circuits. The processing control unit 110 executes programs to perform various processes and control connected units, thereby realizing the functional operation of the nut rotation drive device 100.

[0034] The memory unit 120 is equipped with a memory section capable of writing and reading data, and stores various information data used by the processing control unit 110. The information data stored in the memory unit 120 includes programs executed by the processing control unit 110, tightening operation parameters, and the like.

[0035] The torque application unit 130 is an electric tool that applies torque to a nut that is screwed onto a bolt during bolt tightening. This torque application unit 130 is connected to the processing control unit 110, and the torque application is started and stopped under the control of the processing control unit 110. Furthermore, the torque application unit 130 can switch its rotation direction between right rotation (clockwise) and left rotation (counterclockwise) according to the specification of the processing control unit 110. Here, the right rotation direction is the tightening rotation direction and is the direction in which the rotation angle θ of the nut increases.

[0036] The sensor unit 140 includes a rotation angle detection unit 141 and a torque sensor 142. It starts detection operation in response to a detection start command issued by the processing control unit 110 simultaneously with a torque application start command for load-bearing point tightening issued by the processing control unit 110 to the torque application unit 130. It continues detection operation without interruption until it ends in response to a detection end command issued by the processing control unit 110 simultaneously with a torque application end command issued by the processing control unit 110 to the torque application unit 130.

[0037] Furthermore, the processing control unit 110 is configured to issue a command to start applying torque for tightening at the load-bearing point and a command to start detecting the load-bearing point after the snug point has been exceeded.

[0038] The rotation angle detection unit 141 detects the rotation angle θ of the nut. The rotation angle θ thus detected is sent to the processing control unit 110.

[0039] The torque detection unit 142 detects the torque T applied to the nut. The torque T thus detected is sent to the processing control unit 110.

[0040] The operation input unit 150 is equipped with various function keys and accepts key press inputs from the user of the nut rotation drive device 100, and the operation information is sent to the processing control unit 110. In this embodiment, many of the function keys of the operation input unit 150 are made up of touch panels or the like, with transparent electrodes arranged in a grid pattern to cover the LCD (Liquid Crystal Display) display surface of the display unit 160, which will be described later. The touch panel detects the position where a finger or stylus is pressed and sends the position information as operation information to the processing control unit 110.

[0041] The display unit 160 is equipped with an LCD. Images are displayed on the LCD screen according to display control signals from the processing control unit 110.

[0042] Furthermore, the display unit 160 is equipped with a green lamp and a red lamp located on the head of the nut rotation drive device 100. These lamps light up or turn off in response to a light-up / off command from the processing control unit 110.

[0043] For example, if the processing control unit 110 performs a tightening operation on a bolt that satisfies the desired tightening conditions, it will illuminate only the green lamp in addition to the display on the LCD screen. If the processing control unit 110 fails to perform a tightening operation on a bolt that satisfies the desired tightening conditions, it will illuminate only the red lamp in addition to the display on the LCD screen.

[0044] The sound output unit 170 receives output sound data from the processing control unit 110. The sound output unit 170 then outputs sound corresponding to the output sound data. In this embodiment, the sound output unit 116 is configured as an earphone type and is worn in the user's ear.

[0045] For example, the processing control unit 110 outputs a predetermined chime sound from the sound output unit 170 when a tightening operation is performed on the bolt that satisfies the desired tightening conditions. Conversely, the processing control unit 110 outputs a predetermined beep sound from the sound output unit 170 when a tightening operation is not performed on the bolt that satisfies the desired tightening conditions.

[0046] [Operation] Next, the operation of the nut rotation drive device 100 will be explained, focusing mainly on the processing performed by the processing control unit 110.

[0047] The predetermined ratio R mentioned above is determined in advance through experiments, simulations, experience, etc., depending on the combination of bolts, washers, and nuts used, from the viewpoint of ensuring effective bolt tightening, and is registered in the memory unit 120. Furthermore, the rotation angle change (Δθ0) for periodic acquisition of detection results by the sensor unit 140 by the processing control unit 110, which is suitable for detecting the yield point with the desired accuracy using the yield point tightening method adopted in this embodiment, is also determined in advance through experiments, simulations, experience, etc., depending on the combination of bolts, washers, and nuts used, and is registered in the memory unit 120. In addition, it is assumed that bolt tightening up to the point where the nut rotates slightly beyond the snug point (so-called pre-tightening) is completed. Such pre-tightening may be performed using the nut rotation drive device 100, or using an electric shot other than the nut rotation drive device 100.

[0048] Under the above premise, the nut rotation drive device 100 performs load-bearing point tightening. When performing load-bearing point tightening, the processing control unit 110 sends a command to start applying torque for load-bearing point tightening to the torque application unit 130, and also sends a command to start detection to the rotation angle detection unit 141 and the torque detection unit 142. Then, as shown in Figure 3, in step S11, the processing control unit 110 first reads the detection results from the rotation angle detection unit 141 and the torque detection unit 142 received from the sensor unit 140 and acquires them as the first rotation angle θ1 and torque T1.

[0049] In the following explanation, the rotation angle obtained in the nth (n=1,2,...)th measurement will be denoted as "θn," and the torque obtained in the nth (n=1,2,...) measurement will be denoted as "Tn."

[0050] Next, in step S12, the processing control unit 110 determines whether or not to acquire a new rotation angle and torque. In making this determination, the processing control unit 110 determines, based on the rotation angle detection result received from the rotation angle detection unit 141, whether or not it can be estimated that the rotation angle of the nut has increased by a rotation angle change (Δθ0) from the previously acquired rotation angle, within a predetermined accuracy set in the memory unit 120. If the result of the determination in step S12 is negative (step S12:N), the process in step S12 is repeated.

[0051] If the result of the determination in step S12 is positive (step S12: Y), the process proceeds to step S13. In step S13, the rotation angle and torque are newly acquired.

[0052] Next, in step S14, the processing control unit 110 determines whether the acquisition of rotation angle and torque in the preceding step S13 was the third acquisition. If the result of the determination in step S14 is negative (step S14:N), the process returns to step S12. Then, the process from steps S12 to S14 is repeated until the result of the determination in step S14 becomes positive.

[0053] If the result of the judgment in step S14 is positive (step S14: Y), the process proceeds to step S15. In step S15, the processing control unit 110 calculates the average torque change gradient value V1 from the first acquisition to the third acquisition, based on the detection result acquired in the first acquisition (rotation angle θ1 and torque T1) and the detection result acquired in the third acquisition (rotation angle θ3 and torque T3), using the following equation (1). V1 = (T3 - T1) / (θ3 - θ1) …(1) Next, in step S16, the processing control unit 110 updates the maximum torque change gradient value VMAX by registering the calculated torque change gradient value V1 as the maximum torque change gradient value VMAX in the storage unit 120.

[0054] Next, in step S17, the processing control unit 110 performs the nut rotation process. When step S17 is completed, the load-bearing point tightening operation is finished.

[0055] <Nut rotation process> Next, the nut rotation process in step S17 will be described.

[0056] In the nut rotation process, as shown in Figure 4, first, in step S21, the processing control unit 110 determines whether or not to acquire a new rotation angle and torque. In making this determination, the processing control unit 110, as in step S12, determines from the rotation angle detection result received from the rotation angle detection unit 141 whether or not it can be estimated that the rotation angle of the nut has increased by a rotation angle change (Δθ0) from the previously acquired rotation angle within a predetermined accuracy. If the result of the determination in step 21 is negative (step S21:N), the process in step S21 is repeated.

[0057] If the result of the determination in step S21 is positive (step S21: Y), the process proceeds to step S22. In step S22, the rotation angle and torque are newly acquired.

[0058] Next, in step S23, the processing control unit 110 calculates the average torque change gradient value Vn from the nth acquisition to the (n+2)th acquisition based on the detection result (rotation angle θn and torque Tn) acquired as the nth acquisition and the detection result (rotation angle θn+2 and torque Tn+2) acquired as the (n+2)th acquisition, using the following equation (2). Vn=(Tn+2-Tn) / (θn+2-θn) …(2)

[0059] Next, in step S24, the processing control unit 110 performs an update process for the maximum torque change gradient value VMAX. During this update process, the processing control unit 110 determines whether the torque change gradient value Vn calculated in the preceding step S23 is greater than the current value of the maximum torque change gradient value VMAX registered in the storage unit 120. If the result of this determination is negative, the maximum torque change gradient value VMAX is maintained at its current value. On the other hand, if the result of this determination is positive, the torque change gradient value Vn calculated in the preceding step S23 is registered in the storage unit 120 as the new maximum torque change gradient value VMAX.

[0060] Next, in step S25, the processing control unit 110 determines whether or not to terminate the current load-bearing point tightening operation. In making this determination, the processing control unit 110 uses the registered maximum torque change gradient value VMAX and a predetermined ratio R to make a first determination as to whether or not the most recently calculated torque change gradient value Vn satisfies the following equation (3). R·VMAX>Vn (3) If the result of the first judgment is positive, the processing control unit 110 determines that the load-bearing point tightening was successful and decides to terminate the load-bearing point tightening operation.

[0061] Furthermore, if the processing control unit 110 determines that the load-bearing point tightening has failed if the condition of equation (3) is not met even after a predetermined time has elapsed since the start of step S11, or if the condition of equation (3) is not met even after the total rotation angle from the start of step S11 exceeds a predetermined angle, it determines that the load-bearing point tightening operation has been terminated.

[0062] The predetermined time or angle is determined in advance through experiments, simulations, experience, etc., and registered in the memory unit 120.

[0063] If the result of the judgment in step S25 is negative (step S25:N), the process returns to step S21. Then, the process from steps S21 to S25 is repeated until the result of the judgment in step S25 becomes positive.

[0064] Figure 5 shows how the torque change gradient value Vn is calculated during the nut rotation drive process performed by the processing control unit 110.

[0065] If the result of the determination in step S25 is positive (step S25: Y), the process proceeds to step S26. In step S26, the processing control unit 110 sends a command to terminate the load-bearing point tightening operation to the torque application unit 130 and the sensor unit 140. Specifically, the processing control unit 110 sends a torque application termination command to the torque application unit 130 and a detection termination command to the rotation angle detection unit 141 and the torque detection unit 142.

[0066] Next, in step S27, the processing control unit 110 determines whether the load-bearing point tightening was successful. If the result of the determination in step S27 is positive (step S27: Y), the process proceeds to step S28. In step S28, the processing control unit 110 provides a notification to the user that the load-bearing point tightening was successful. Specifically, the processing control unit 110 displays a success message on the LCD screen of the display unit 160, lights up only the green lamp on the display unit 160, and outputs a predetermined chime sound to the sound output unit 170.

[0067] Once the process in step S27 is completed, the processing control unit 110 terminates the process in step S17. As a result, the load-bearing point tightening operation is completed.

[0068] On the other hand, if the result of the determination in step S27 is negative (step S27:N), the process proceeds to step S29. In step S29, the processing control unit 110 provides a notification to the user that the load-bearing point tightening has failed. Specifically, the processing control unit 110 displays a failure on the display surface of the display unit 160 LCD, lights up only the red lamp on the display unit 160, and outputs a predetermined beep sound to the sound output unit 170.

[0069] Once the process in step S28 is completed, the processing control unit 110 terminates the process in step S17. As a result, the load-bearing point tightening operation is completed.

[0070] As described above, the processing control unit 110 periodically acquires the rotation angle of the nut and the torque applied to the nut detected by the sensor unit 140. Based on the acquired detection results, the processing control unit 110 controls the bolt tightening operation by the torque application unit based on the change in the torque change gradient value (Vn=ΔTn / Δθn), which is the ratio of the estimated increase (=ΔTn(=Tn+2-Tn)) of the applied torque (Tn+2) at the (n+2) time from the applied torque (Tn) at the nth time, with respect to the estimated change in the rotation angle of the nut between the nth (n=1,2,...) time and the (n+2) time (=Δθn(=θn+2-θn)).

[0071] Therefore, the detection error of the nut rotation angle (θn, θn+2) and applied torque (Tn, Tn+2), which are used to calculate the torque change gradient value (Vn), has an effect on the calculation result of the torque change gradient value (Vn) that is reduced by about half compared to the conventional example, while still allowing calculation every time the nut rotation angle changes by an amount Δθ (=θn+1-θn), just like in the conventional example. In addition, the effect of so-called wavering can also be reduced compared to the conventional example due to the averaging effect.

[0072] Therefore, the torque change gradient value (Vn) can be calculated accurately and rationally, and consequently, bolt tightening can be performed appropriately and rationally while employing the yield strength point method.

[0073] Furthermore, in this embodiment, the processing control unit 110 instructs the torque application unit 130 to terminate the bolt tightening operation when the ratio (=Vn / VMAX) of the torque change gradient value (=Vn) to the maximum value (=VMAX) after the start of the tightening operation falls below a predetermined ratio R. Therefore, the bolt tightening operation can be terminated appropriately and rationally while employing the load-bearing point method.

[0074] Furthermore, by combining torque control and load-bearing point control tightening programs, highly accurate load-bearing point tightening is possible. For example, a standard wrench used for steel bridges can only be tightened using one control method, but a torque management system has the advantage of being able to perform several types of control by switching settings. Furthermore, by combining several control methods, continuous tightening can be performed with a single wrench without the need to switch settings. For example, by combining torque control and load-bearing point control, tightening can be performed until the torque value set by torque control is reached, and once torque control is complete, load-bearing point control can be started without the wrench stopping.

[0075] [Variations of the Embodiment] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the spirit of the invention.

[0076] For example, in the above embodiment, the present invention was applied to confirming the tightening position and tightening state when using high-strength hexagonal bolts. However, the present invention may also be applied when using types other than high-strength hexagonal bolts.

[0077] Furthermore, in the above embodiment, it was assumed that a wired method was used for communication between the processing control unit and the display unit and sound output unit. However, a wireless method may be used for such communication.

[0078] Furthermore, in the above embodiment, the torque change gradient value Vn is calculated based on the detection result (θn, Tn) obtained on the nth (n=1,2,...)th time and the detection result (θn+2, Tn+2) obtained on the (n+2)th time. Alternatively, the torque change gradient value Vn may be calculated based on the detection result (θn, Tn) obtained on the nth time and the detection result (θn+q, Tn+q) obtained on the (n+q)th time (q is a natural number of 3 or more and is predetermined). In this case, the larger the value "q", the longer the end of the endurance point tightening operation will be delayed, but it is expected that the influence of the detection error of the rotation angle of the nut and the applied torque used in calculating the torque change gradient value Vn on the calculation result of the torque change gradient value, as well as the effect of the so-called wavering described above, can be reduced compared to the above embodiment.

[0079] Furthermore, when the torque application unit applies torque to the nut while maintaining the rotational speed of the nut, a processing control unit having a timing mechanism may acquire the rotation angle of the nut and the torque applied to the nut detected by the sensor unit at predetermined time intervals.

[0080] Furthermore, although the above embodiment described the case of tightening a bolt by rotating the nut side relative to the high-strength bolt, it goes without saying that it can also be applied to the case of tightening a bolt by rotating the head of the high-strength bolt. [Industrial applicability]

[0081] As described above, the present invention is useful in the field of bolt fastening. [Explanation of symbols]

[0082] 100 ... Nut rotation drive device 110 ... Processing control unit (control unit) 120 ... Memory Unit 130 ... Torque-applying unit 140 ... Sensor unit 141 ... Rotation angle detection unit 142 ... Torque detection unit 150 ... Operation input unit 160 ... Display Unit 170 ... Sound output unit

Claims

1. A rotary drive device for rotating one of the fastening components, either a high-strength bolt or a nut, when tightening a high-strength bolt, A torque application unit that applies torque to one of the fastening components; A sensor unit for detecting the rotation angle of one of the fastening components and the torque applied to the one fastening component; A control unit that periodically acquires detection results from the sensor unit and controls the torque application unit based on the acquired detection results; The control unit estimates the change in the rotation angle (=Δθn (=θn+p-θn)) between the nth (n=1, 2, ...)th time and the (n+p (p is a predetermined natural number of 2 or more)) The applied torque (Tn+p) in the (n+p)th time for the nth time The torque application unit is configured to control the bolt tightening operation based on the change in the torque change gradient value (Vn = ΔTn / Δθn), which is the ratio of the estimated increase from the applied torque (Tn) to (= ΔTn (= Tn + p - Tn)). The torque application unit applies torque to the one fastening component while maintaining the rotational speed of the one fastening component. The control unit is At predetermined time intervals, the rotation angle of one of the fastening components and the torque applied to the one fastening component are acquired. When the ratio (Vn / VMAX) of the torque change gradient value (Vn) to the maximum value (VMAX) after the start of the bolt tightening operation falls below a predetermined value, the torque application unit is instructed to terminate the bolt tightening operation. A rotary drive device for fastening components, characterized by the above.

2. The rotational drive device for fastening components according to Claim 1, characterized in that the predetermined value is a value selected in advance from within the range of 0.6 to 0.9.

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