JP2012236264A - Torque wrench - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure an actual fastening force applied to a screw even if fastening work is carried out for the screw while a torque wrench is tilted.SOLUTION: The torque wrench 20 includes a fastening head 21 at the tip of a shaft 22. The fastening head 21 includes an engaging part 24 engaged with a nut 12. In the engaging part 24, three distance sensors 25 are arranged in a circular arc part 24b in the direction of an axis A of the nut 12 in order to detect the tilting of the torque wrench 20 with respect to the axis A. The tilting of the torque wrench 20 is detected from a difference between the detected distances using a tilting angle detection part 27, thereby detecting actual torque to the nut 12. A preset prescribed torque value is corrected by a torque correction circuit 30, and a corrected prescribed torque value is calculated.

Description

  The present invention relates to a torque wrench having a function as a screw tightening tool and a function of measuring a tightening torque.

  A wrench is generally used as a tool for tightening screws, but the tightening torque must be set in order to ensure proper tightening so that the screws do not loosen and the threads are not damaged or damaged. A torque wrench having a function of measuring is used. A predetermined torque value is set in advance, and when the measured torque reaches the set specified torque, the operator is made to recognize it. As a result, a torque with no excess or deficiency can be applied to perform a highly accurate screw tightening operation. Here, although a hand type, a hydraulic type, and an electric type are used as the torque wrench, the same can be said for any type of torque wrench.

  In addition, there are various configurations such as a ratchet type, spanner type, monkey type, etc., for the head part that tightens the screw, and a torque measurement method using a strain sensor, a load cell, etc. There is.

  A torque wrench disclosed in Patent Document 1 is conventionally known. This known torque wrench includes a strain sensor connected to a tightening portion, and includes a strain sensor that detects a tightening force applied by the tightening portion as a strain amount of the strain generating body, and is based on a signal from the strain sensor. Torque is calculated, and the torque value measured by the torque calculator is compared with the preset torque value.When the measured torque value becomes the set torque value, it is displayed, and this is indicated by a buzzer or lamp. Is configured to notify the operator.

JP 2006-289535 A

  By the way, the torque value measured by the torque wrench is a torque that acts on the tightening portion during rotation and is not an actual tightening force that acts on the screw when the screw is tightened. The torque wrench generates an axial propulsive force on the screw by rotating the screw part. To accurately measure the tightening force, when the screw part is rotated by the torque wrench, Force that the screw advances in the axial direction must be applied, and force should not be applied in the other direction. For this purpose, it is necessary to arrange the torque wrench in a direction orthogonal to the axis of the screw portion. However, especially in the case of a hand-type torque wrench, a long shaft portion is used from the viewpoint of reducing the operating force, and there is an interference with the rotation of the torque wrench around the screw portion. In some cases, the torque wrench cannot be tightened in a state in which the torque wrench extends in a direction orthogonal to the axis of the screw portion. Under such circumstances, even if the specified torque value of the torque wrench is obtained, the threaded portion cannot be tightened to an appropriate state.

  The present invention has been made in view of the above points. The purpose of the present invention is to accurately calculate the actual tightening force acting on the screw portion even if the torque wrench is tilted. It is to be able to measure.

  In order to achieve the above-mentioned object, the present invention comprises a fastening head engaged so as to screw a threaded portion and a shaft portion that applies a rotational force to the fastening head, and acts on the fastening head. A torque wrench for measuring a torque and setting a specified torque value to be actually applied to the screw portion, the torque wrench being mounted on the tightening head and facing an outer surface of the screw portion, the axis of the screw portion And at least two distance sensors that measure the distance to the outer surface, and the tightening head with respect to the axis of the screw portion based on a detection signal from each distance sensor. An inclination angle calculating means for calculating an inclination angle, and a torque value correcting means for correcting the specified torque value based on a calculation result by the inclination angle calculating means. It is an its characterized in that a formed.

  The external shape of the threaded portion with which the tightening head in the torque wrench is engaged may be a curved surface shape such as a circle, but the external shape is generally rectangular, particularly hexagonal. When tightening the hexagonal threaded portion, the tightening head engages with two surfaces facing the parallel direction of the threaded portion. For this reason, two inclined surfaces adjacent to these surfaces face the inner surface of the clamping head. Therefore, if the distance sensor is provided so as to face these two surfaces, the inclination of the tightening head can be measured more accurately. A plurality of distance sensors are arranged at positions spaced apart by a predetermined interval in the axial direction of the threaded portion, that is, in the thickness direction of the fastening head. The number of distance sensors to be arranged is at least two, but three or more may be provided.

  Here, the inclination of the torque wrench means a state in which the torque wrench is tilted forward or backward with respect to the axis of the screw portion, which is the screw advance direction in the screw portion, when engaged with the screw portion. The inclination angle is relative to the direction orthogonal to this axis.

  When the tightening force that is applied to the threaded portion by the torque wrench is applied with a tightening torque that is corrected to the specified torque value by the inclination of the torque wrench, it is necessary to prevent the load of the torque wrench from further acting on the threaded portion in that state. Yes, so the operator must be informed. The notification method is not particularly limited, but it is desirable to use an alarm sound such as a buzzer.

  Even if the tightening operation is performed in a state where the torque wrench is tilted, the actual tightening force acting on the screw portion can be accurately measured, and excessive or insufficient tightening force of the screw portion can be prevented or suppressed.

It is a front view which shows the connection part of a hose and a pipe as an example of the piping connection part by which a screw is fastened. It is a front view of the state which isolate | separated the hose and pipe of FIG. It is a front view of the torque wrench which shows one embodiment of the present invention. FIG. 4 is a right side view of FIG. 3. It is principal part expansion structure explanatory drawing which shows the engaging part of the fastening head of a torque wrench, and the nut for piping connection. It is an action explanatory view showing the state where the torque wrench is inclined and the screw is tightened. It is explanatory drawing which shows the force which acts on a thread part when operating a torque wrench in the state of FIG. It is explanatory drawing which shows the state which is detecting the inclination of a torque wrench. It is a diagram which shows the relationship between the inclination angle of a torque wrench, and the correction value of a regulation torque. It is a block diagram which shows the structure of the correction | amendment mechanism of a regular torque value.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, FIG.1 and FIG.2 shows one structural example of the piping connection part connected using a torque wrench. The pipe connection portion is detachably connected to a hard pipe 2 provided with a flexible hose 1 in a bending direction fixedly at a predetermined position. For this pipe connection, a base 3 is connected to the tip of the hose 1, and the end of the pipe 2 is a connection port 4. 1 shows a state where the hose 1 and the pipe 2 are separated, and FIG. 2 shows a connected state.

  A base 3 provided at the tip of the hose 1 is composed of a base body 10 and a nut 11, and a fixing nut portion 12 for holding the base body 10 so as not to rotate when the nut 11 is tightened to the base body 10. Is formed. The nut 11 is a cap nut that is rotatable with respect to the base body 10 and is held in a connected state with the base body 10. Further, the connection port 4 in the pipe 2 is a portion where a thread groove 13 is formed on the outer peripheral surface, and a lock nut 14 is screwed into the connection port 4.

  The nut 11 is tightened using a torque wrench 20. For example, as shown in FIGS. 3 and 4, the torque wrench 20 is configured by connecting a shaft portion 22 to a fastening head 21, and the tip of the shaft portion 22 is a grip portion 23. The torque wrench is not limited to this. The torque wrench 20 functions as a screw tightening tool and also has a function of measuring a tightening torque. Then, the measured current tightening torque value and the target specified torque value at the time of tightening are displayed. For this purpose, a torque display portion 23 is formed on the shaft portion 22.

  Here, the tightening head 21 of the torque wrench 20 has an engaging portion 24 formed of a substantially U-shaped recess, and this engaging portion 24 engages with the nut 11 constituting the screw portion. . Here, the outer shape of the nut 11 is substantially a regular hexagon. As shown in FIG. 5, the opposing vertical wall portions 24a and 24a constituting the engaging portion 24 are parallel to each other. Will abut against one surface. Further, the two heads have two oblique sides directed to one apex from the two parallel surfaces and two oblique sides directed to the other apex, and the fastening head 21 is engaged with the nut 11. In some cases, the hypotenuse of one set is located inside the engaging portion 24.

  When the gripping portion 22a of the torque wrench 20 is gripped by hand with the engaging portion 24 of the tightening head 21 engaged with the nut 11 and rotated around the screw groove 13, the nut 11 As a result of moving along the thread groove 13 of the connection port 4 of the pipe 2 that is screwed, the end surface of the base body 10 is moved toward the direction in which the end surface of the base body 10 is pressed against the end surface of the connection port 4. The direction of relative movement between the nut 11 and the connection port 4 is the axis A, and the tightening operation is performed by rotating the torque wrench 20.

  As described above, the nut 11 is tightened by the torque wrench 20. The nut 11 is tightened by pressing the end surface of the base body 10 and the end surface of the connection port 4 in the base 3 on the hose 1 side. A seal member (not shown) interposed between the two is bent. As a result, airtightness is ensured between the hose 1 and the pipe 2, and the connection portion between the hose 1 and the pipe 2 is not separated due to the action of an external force or the like.

  Here, when the hose 1 is connected to the pipe 2 by providing the nut 11 rotatably provided on the base body 10, as shown in FIG. 6, the fixing body provided on the base body 10 of the base 3. The fixing wrench 18 is engaged with the nut portion 12, and the torque wrench 20 is engaged with the nut 11 in this state, and the shaft portion 22 of the torque wrench 20 is rotated. Thereby, at the time of operation which connects the hose 1 and the pipe 2, they do not rotate together.

  Torque generated when the nut 11 is rotated by the torque wrench 20 is detected by a strain sensor or the like built in the torque wrench 20. When the torque acting on the nut 11 reaches a predetermined set value, the screw tightening operation is completed. Here, when the torque wrench 20 is arranged in the direction orthogonal to the axis A and tightened, the maximum torque can be applied to the nut 11. However, due to the obstacle S in the vicinity of the pipe connection portion, the torque wrench 20 cannot be extended in the direction orthogonal to the axis A of the connection port 4 as shown by the phantom line in FIG. , It may be inclined by an angle θ toward the longitudinal direction of the axis A.

  The nut 11 can be tightened even when the torque wrench 20 is tilted. However, the movement of the nut 11 in the straight direction is obstructed, and the necessary tightening torque cannot be obtained unless an excessive tightening force is applied. That is, as shown in FIG. 7, the tightening force of the nut 11 is maximized when it is working in the direction F <b> 1 orthogonal to the axis A. However, the tightening force acting on the torque wrench is that when the torque wrench 20 is inclined by an angle θ, the force acting on the nut 11 becomes the diagonal direction F2, and the transmission of the force in the direction of rotating the nut 11 is obstructed. Is done. As a result, as the measured torque value of the torque wrench 20, there is a situation where the actual tightening force is insufficient by ΔF to the target torque value despite the fact that the preset specified torque is acting.

  Therefore, as shown in FIG. 8, a predetermined torque value Tset is set in advance in the torque wrench 20. This specified torque value Tset is the final target tightening force when the torque wrench 20 is not tilted, that is, when tightening is performed in a state extending in a direction orthogonal to the axis A of the nut 11. This is a torque value for acting. Therefore, if the torque wrench 20 is inclined with respect to the axis A, the torque value Treal acting on the nut 11 is smaller than the specified torque value Tset according to the magnitude of the angle θ, and the target tightening force is applied. Instead, the specified torque value Tset is generated in a state where the tightening force is insufficient. Therefore, when tightening with the torque wrench 20 tilted, the corrected specified torque value Tcom is set to be the target in order to exert the target tightening force with the specified torque value Tset. As a result, the tightening operation of the screw by the torque wrench 20 can be performed with high accuracy, and a situation such as insufficient tightening force does not occur.

  Therefore, the inclination angle of the torque wrench 20 is detected. That is, as apparent from FIG. 9, in the engaging portion 24 of the torque wrench 20, the portion between the vertical wall portions 24a, 24a is an arc-shaped portion 24b (see FIG. 5), and this arc-shaped portion 24b. Is equipped with a distance sensor 25. The distance sensor 25 includes a plurality of distance sensors 25 provided in the thickness direction of the tightening head 20, that is, in the direction of the axis A when the torque wrench 20 is engaged with the nut 11. As shown, two sets of these distance sensors 25 are provided. Each of the three distance sensors 25 faces the arcuate portion 24b when the left and right vertical wall portions 24a of the engaging portion 24 of the tightening head 21 are engaged with two mutually parallel surfaces of the nut 11. It is provided so as to face two oblique sides.

  Here, the two sets of the three distance sensors 25 are provided for more accurate distance measurement. The distance measurement can be performed using, for example, an optical measurement means. In this case, the distance sensor 25 must be separated from the surface of the nut 11, but one apex portion of the nut 11 has an arc shape. Even if it abuts on the portion 24b, the disposition position of the distance sensor 25 is maintained in a non-contact state with the outer surface of the nut 11.

  In this way, by detecting the inclination of the torque wrench 20 with respect to the axis A of the nut 11 by providing three (or two) distance sensors 25 at different positions in the direction of the axis A of the nut 11. Can do. That is, as shown in FIG. 8, when the distance sensors provided at three locations on the tightening head 21 of the torque wrench 20 are sequentially denoted by reference numerals 25L, 25M, and 25R, the torque wrench 20 including the tightening head 21 has an axis line. When tilted by an angle θ with respect to A, the distance sensor 25L is closest to the surface of the nut 11, and then the distance sensor 25M is the farthest position. Therefore, the inclination angle θ can be calculated by calculating these distance differences.

  As described above, the inclination of the torque wrench 20 is detected. According to the inclination of the torque wrench 20, a corrected specified torque value Tcom obtained by correcting the specified torque value Tset is calculated, and the corrected specified torque value Tcom is calculated. It is set as the final tightening torque. The corrected specified torque value Tcom is obtained by calculation from the specified torque value Tset and the inclination angle θ of the torque wrench 20, and for this purpose, a means for correcting the specified torque value shown in FIG. 10 is provided. That is, a signal from the distance sensor 25 that is a set of three in the engaging portion 24 of the torque wrench 20 is input to the distance calculation unit 26, and the distance to the surface of the nut 11 in each distance sensor 25. Based on the difference, the tilt angle θ of the torque wrench 20 is calculated by the tilt angle detection unit 27, and the data of the tilt angle θ is taken into the memory unit 28, along with this, a strain sensor incorporated in the torque wrench 20, etc. A detection signal of the torque value measured by the torque detection means 29 is also taken into the memory unit 28. Furthermore, data relating to the specified torque value Tset is also recorded in the memory unit 28. Each of these data is taken into the torque value correction circuit 30, and a corrected specified torque value Tcom is calculated.

  Now, assuming that the specified torque value Tset is applied to the nut 11, the length of the torque wrench 20 is L, and the force F is applied when the torque wrench 20 is in a direction perpendicular to the axis A of the nut 11. Then, if the specified torque value Tset is obtained, Tset = F × L. However, when the torque wrench 20 is inclined by the angle θ, the torque T1 acting on the nut 11 is F × Lcos θ. Therefore, when 1 / cos θ is multiplied as a correction coefficient, T1 = F × (Tset × 1 / cos θ) × L cos θ = F × L. That is, when the torque wrench 20 is tilted, the torque acting on the nut 11 decreases and decreases by cos θ. Therefore, by increasing the torque by (1 / cos θ), that is, in FIG. By setting the torque Treal that directly acts as the tightening direction for the nut 11 by the tilt of the torque wrench 20 to Tcom obtained by multiplying the correction coefficient 1 / cosθ, the nut 11 can be subjected to a torque corresponding to Tset.

DESCRIPTION OF SYMBOLS 1 Hose 2 Pipe 3 Base 4 Connection port part 10 Base body 11 Nut 20 Torque wrench 21 Tightening head 22 Shaft part 22a Torque display part 24 Engagement part 24a Vertical wall part 24b Arc-shaped part 25 Distance sensor 26 Distance calculation part 27 Inclination angle Detection unit 28 Memory unit 29 Torque detection means 30 Torque correction circuit

Claims (2)

It consists of a tightening head engaged so as to screw the screw portion and a shaft portion that applies a rotational force to the tightening head, and measures the torque acting on the tightening head and actually acts on the screw portion. A torque wrench in which a specified torque value to be set is set,
At least two distance sensors that are mounted on the tightening head and are opposed to the outer surface of the threaded portion and spaced apart from each other by a predetermined distance in the axial direction of the threaded portion, and measure the distance to the outer surface; ,
An inclination angle calculating means for calculating an inclination angle of the tightening head with respect to the axis of the screw portion based on detection signals from the distance sensors;
A torque wrench comprising torque value correcting means for correcting the specified torque value based on a calculation result by the tilt angle calculating means.   The threaded portion with which the tightening head engages has a hexagonal portion, and the distance sensor has a configuration in which two or three pairs are arranged so as to face two or more different surfaces of the hexagonal portion. The torque wrench according to claim 1.

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