JP2009113132A - Pulse hammering tightening tool and method of detecting defective tightening of the tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulse hammering tightening tool capable of increasing the quality of screw tightening to improve a tightening accuracy by detecting a defective tightening if the defective tightening occurs when a screw is tightened. <P>SOLUTION: The pulse hammering tightening tool includes a torque sensor or a tightening torque detection means, an angle sensor or a rotating angle detection means for detecting the rotating angle of a spindle, and a determination part or a determination means for determining whether the screw tightening is defective. The determination part determines, based on a torque value acceptable range D1 and an angle value acceptable range D2, that the screw tightening is defective when a detected torque value is smaller than a lower limit value ToPmin of the torque value acceptable range D1 when a detected angle value reaches the upper limit value APmax of the angle value acceptable range D2 and when the detected angle value is smaller than the lower limit value APmin in the angle value acceptable range D2 when the detected angle value reaches the upper limit value ToPmin in the torque value acceptable range D1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pulse-type impact tightening tool including a main shaft to which a pulsed torque is applied, and tightening a screw such as a bolt or a nut by rotation of the main shaft, and a tightening failure detection method therefor.

Conventionally, a torque wrench (so-called hand-held pulse) has been provided as a hand-held tool that tightens screws by rotating the main shaft, which is provided with a main shaft to which pulse-like torque is applied when tightening screws such as bolts and nuts. Tool) is used (see, for example, Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4).
Specifically, the hand-held pulse tool as described above has a rotational driving source such as an air motor or an electric motor, and a continuous rotational torque from the rotational driving source as a pulsed impact torque with respect to the main shaft. The impact torque generator for converting is provided, and pulsed torque from the impact torque generator is applied to the main shaft. Then, as described above, the main shaft is rotated while being applied with the pulse-like torque in a state where the tip end side is engaged with the screw through an attachment or the like, whereby the screw is tightened.

On the other hand, when tightening screws such as bolts and nuts, quality control of screw tightening, specifically, whether there is a defect in the work fastened by the screw, whether the tightening state is good, angle control, axial force control, etc. It is very important to measure the tightening angle of the screw.
Therefore, Patent Document 1 discloses a technique for accurately measuring the tightening angle of a screw in a hand-held pulse tool by eliminating the influence of noise such as camera shake and rebound. Specifically, the following techniques are disclosed. That is, in the hand-held pulse tool disclosed in Patent Document 1, the tightening torque and the rotation angle of the main shaft are detected. Then, the rotation angle of the main shaft while the detected value of the tightening torque is equal to or greater than a preset value (snugging torque) is integrated in the pulsed tightening torque applied to the main shaft, and the integrated value Is calculated as the screw tightening angle.

However, in the conventional hand-held pulse tool, even if the accuracy of the tightening torque can be increased, if a tightening failure occurs, it is not possible to detect the failure factor on the workpiece side that is tightened with screws. .
That is, in the conventional hand-held pulse tool, when the value of the detected tightening torque is used or an operation stop mechanism as shown in Patent Document 3 is provided, etc., when tightening the screw, Some have a configuration for automatically stopping the operation of the tool (operation of a rotary drive source such as an air motor) when the tightening torque reaches a predetermined value. Thus, in the configuration in which the operation of the tool is stopped based on only the value of the tightening torque when tightening the screw, even if a tightening failure occurs, a predetermined tightening torque is set. The tool stops when the value is reached, and the tool does not stop unless the tightening torque reaches a predetermined value. Such a phenomenon will be described with reference to the graph shown in FIG.

FIG. 7 is an example of a graph showing the relationship between the rotation angle value (deg) of the main shaft and the tightening torque value (N · m) during screw tightening. The value of the rotation angle of the main spindle is based on the value at the time when the fact that the screw is in contact with the seat surface of the workpiece (the screw is seated on the workpiece) is detected from the value of the tightening torque. 0 deg).
In this example, as described above, a predetermined value (hereinafter referred to as “target torque”) of a tightening torque that is set in advance to automatically stop the operation of the tool when the screw is tightened is set to 30 N · m. Yes.

When tightening the screws normally, the tightening torque value increases as the spindle rotation angle (hereinafter simply referred to as “rotation angle”) increases. In a state where is within a predetermined range, the value of the tightening torque reaches the target torque. That is, when normal screw tightening is performed, the range of the rotation angle value when the tightening torque value reaches the target torque is determined to some extent in the relationship between the rotation angle value and the tightening torque value. When the value of the tightening torque reaches the target torque in that range, it is ensured that the quality of the screw tightening is a non-defective product without causing a tightening failure.
In the graph of FIG. 7, the angle range indicated by the symbol D101 for the rotation angle value is the angle range of the rotation angle value that ensures that the screw tightening quality is non-defective as described above (hereinafter, “non-defective angle range D101”). It is said.) In this example, the non-defective product angle range D101 is in a range of about 80 to 130 deg.

  Therefore, in the graph of FIG. 7, a graph A101 indicated by a solid line is a graph in a case where the screws are normally tightened. That is, in tightening the screw shown in the graph A101, the tightening torque value reaches the target torque (see the straight line T101) in a state where the rotation angle value is within the non-defective angle range D101. In other words, the value of the rotation angle when the value of the tightening torque reaches the target torque is a value within the non-defective product angle range D101.

On the other hand, in the graph of FIG. 7, a graph A102 indicated by a broken line and a graph A103 indicated by an alternate long and short dash line are graphs when a tightening failure occurs during tightening of a screw. That is, in the screw tightening shown in the graph A102, the rotation angle value exceeds the non-defective product angle range D101 before the tightening torque value reaches the target torque. Further, in the screw tightening shown in the graph A103, the value of the tightening torque reaches the target torque before the value of the rotation angle reaches the non-defective product angle range D101. As described above, when a tightening failure occurs during tightening of the screw, the value of the rotation angle when the value of the tightening torque reaches the target torque becomes a value outside the non-defective product angle range D101.
Note that, as shown in the graph A102, before the tightening torque value reaches the target torque, the cause of the poor tightening when the rotation angle value exceeds the non-defective product angle range D101 is, for example, screw crushing. Conceivable. Further, as shown in the graph A103, the cause of the poor tightening when the value of the tightening torque reaches the target torque before the value of the rotation angle reaches the non-defective product angle range D101 is as follows. A missing item such as a washer interposed between them may be considered.

As described above, the conventional hand-held pulse tool employs a configuration that stops the operation of the tool based on only the tightening torque value when tightening the screw. Even so, it could not be detected from the value of the tightening torque, and the quality of the screw tightening could not be determined as good or defective.
Japanese Patent Laid-Open No. 2007-30056 Japanese Utility Model Publication No. 1-29012 Japanese Unexamined Patent Publication No. 6-321381 Japanese Patent Laid-Open No. 10-15843

  The present invention has been made in view of the above-described problems of the prior art, and the problem to be solved is that it is possible to detect a tightening failure when tightening a screw. Accordingly, it is an object of the present invention to provide a pulse-type impact tightening tool capable of improving the tightening accuracy and improving the quality of screw tightening, and a tightening failure detection method therefor.

  The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

  That is, according to the first aspect of the present invention, a rotation drive source and a main shaft to which a pulsed impact torque obtained by converting the rotation torque from the rotation drive source is provided, and the screw is tightened by the rotation of the main shaft. A pulse-type impact tightening tool, wherein a tightening torque detecting means for detecting the tightening torque of the screw, a rotation angle detecting means for detecting a rotation angle of the main shaft, and a tightening failure with respect to the tightening of the screw are determined. Determining means, wherein the determining means is configured in advance for each of the value of the tightening torque detected by the tightening torque detecting means and the value of the rotation angle detected by the rotation angle detecting means. When the value of the rotation angle detected by the rotation angle detection means reaches the upper limit value of the pass range based on a predetermined pass range that is set, the tightening torque detection means When the detected value of the tightening torque is smaller than the lower limit value of the acceptable range, and the value of the tightening torque detected by the tightening torque detecting means has reached the upper limit value of the acceptable range. Sometimes, the case where the value of the rotation angle detected by the rotation angle detection means is smaller than the lower limit value of the acceptable range is detected as the tightening failure.

  The pulse-type impact tightening tool according to claim 1, further comprising an elapsed time measuring unit that measures an elapsed time from a predetermined reference time in screw tightening, wherein the determination unit includes the elapsed time. About the value of the elapsed time measured by the measuring means, when the value of the elapsed time measured by the elapsed time measuring means reaches the upper limit value of the acceptable range based on a predetermined acceptable range set in advance. A value of the tightening torque detected by the tightening torque detection means or a value of the rotation angle detected by the rotation angle detection means is smaller than a lower limit value of each acceptable range; and the tightening The value of the tightening torque detected by the torque detection means or the value of the rotation angle detected by the rotation angle detection means exceeds the respective acceptable ranges. When it reaches a value, where the value of has been the elapsed time measured by the elapsed time measuring means is less than the lower limit value of the said acceptance range, and detects as a defective said clamping.

  According to a third aspect of the present invention, in the pulse-type impact tightening tool according to the second aspect, the determination means includes an initial reference value for screw tightening preset for the tightening torque value, and a value of the rotation angle. And the rotation angle detecting means when the value of the tightening torque detected by the tightening torque detecting means reaches the initial reference value based on a minimum reference value preset for each of the elapsed time values. The case where the value of the rotation angle detected by the above or the value of the elapsed time measured by the elapsed time measuring means is smaller than the minimum reference value is detected as the tightening failure.

  According to a fourth aspect of the present invention, there is provided a pulse type that includes a rotation drive source and a main shaft to which a pulse-like impact torque obtained by converting the rotation torque from the rotation drive source is applied, and the screw is tightened by the rotation of the main shaft. A tightening failure detection method for an impact tightening tool, wherein the tightening torque of the screw and the rotation angle of the main shaft are detected, and the value of the tightening torque to be detected and the value of the rotation angle are detected in advance. When the detected value of the tightening torque is smaller than the lower limit value of the acceptable range when the value of the detected rotation angle reaches the upper limit value of the acceptable range based on the set predetermined acceptable range, And when the detected value of the tightening torque reaches the upper limit value of the acceptable range, the detected value of the rotation angle is smaller than the lower limit value of the acceptable range is detected as a tightening failure. Is shall.

  In claim 5, in the tightening failure detection method in the pulse-type impact tightening tool according to claim 4, the elapsed time from a predetermined reference time in screw tightening is measured, and the value of the elapsed time to be measured is measured. Based on a predetermined pass range set in advance, when the measured elapsed time value reaches the upper limit value of the pass range, the detected tightening torque value or the detected rotation angle value is When the value is smaller than the lower limit value of the acceptable range, and when the detected tightening torque value or the detected rotation angle value reaches the upper limit value of the respective acceptable range, the measured elapsed time value is The case where it is smaller than the lower limit value of the acceptable range is detected as a tightening failure.

  According to a sixth aspect of the present invention, in the tightening failure detection method for the pulse-type impact tightening tool according to the fifth aspect of the present invention, an initial reference value for screw tightening that is set in advance for the tightening torque value, and the value of the rotation angle. In addition, based on the minimum reference value set in advance for each of the elapsed time values, the detected rotation angle value or the measured elapsed time value when the detected tightening torque value reaches the initial reference value. A case where the value is smaller than each of the minimum reference values is detected as a tightening failure.

As effects of the present invention, the following effects can be obtained.
That is, according to the present invention, when a tightening failure occurs when tightening a screw, it is possible to detect the tightening accuracy, and it is possible to improve the tightening accuracy and improve the quality of the tightening of the screw. Can be achieved.

Next, embodiments of the invention will be described.
First, the configuration of a torque wrench that is an embodiment of a pulse-type impact tightening tool according to the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 shows a torque wrench main body (hereinafter referred to as “tool main body 1”) according to the present embodiment. The tool body 1 is a so-called hand-held pulse tool configured as a hand-held tool used for tightening screws such as bolts and nuts. Therefore, the tool main body 1 is packaged by the housing 2 having the grip portion 2a.

  As shown in FIG. 1, the torque wrench of the present embodiment includes an air motor 3 as a rotational drive source, and a main shaft 4 to which a pulsed impact torque obtained by converting the rotational torque from the air motor 3 is applied. Screws are tightened by the rotation of the main shaft 4. That is, the torque wrench of this embodiment is configured as an air motor driven torque wrench.

The air motor 3 is provided in the housing 2. The air motor 3 has a rotor 5 that generates rotational torque by high-pressure air. Supply and stop of the high-pressure air to the rotor 5 are performed through operation of an operation lever 6 provided in the grip portion 2 a of the housing 2. The operation lever 6 is interlocked with a main valve 7 provided in the grip portion 2a. The main valve 7 supplies and stops high-pressure air to the rotor 5. That is, by operating the operation lever 6, the main valve 7 is operated, and high-pressure air is supplied to and stopped from the rotor 5. Here, the high-pressure air for the rotor 5 is supplied from an air source such as an air pump via an air hose (not shown) connected to the end of the grip portion 2 a of the housing 2.
In addition, the rotational drive source with which a torque wrench is provided is not limited to this embodiment. That is, the torque wrench of the present embodiment includes the air motor 3 as its rotational drive source, but instead of this, for example, an electric motor may be used. That is, in this case, the torque wrench is configured as an electric motor drive type torque wrench.

  The main shaft 4 is an output shaft in the tool main body 1, and is rotatably supported with one end portion (tip portion) protruding from the housing 2. The tip protruding portion of the main shaft 4 from the housing 2 is engaged with the screw through an attachment or the like. That is, the main shaft 4 engaged with the screw is rotated to tighten the screw.

A hydraulic striking torque generator 8 is provided between the air motor 3 and the main shaft 4 in the housing 2.
The striking torque generator 8 converts continuous rotational torque from the air motor 3 into pulsed striking torque. That is, the striking torque generator 8 is connected to the rotor 5 of the air motor 3 and converts the rotational torque generated by the rotor 5 into a pulsed striking torque. The pulsed impact torque after being converted by the impact torque generating device 8 is transmitted to the main shaft 4. Thereby, a pulsed impact torque is applied to the main shaft 4.
The striking torque generator 8 converts a continuous rotational torque from the air motor 3 into a pulsed striking torque by a known configuration in which hydraulic pressure is used. The hydraulic striking torque generator 8 generally has the following configuration.

That is, the impact torque generating device 8 is connected to the rotor 5 and rotated in the same radial direction while being urged radially outward of the main shaft 4 with respect to the main shaft 4. And a vane (blade) provided to be movable. The substantially cylindrical liner is provided coaxially with the main shaft 4. The main shaft 4 is inserted into the internal space of the substantially cylindrical liner. The working oil is filled and sealed in the inner space of the liner, that is, in the space outside the main shaft 4 in the inner space of the liner (the space between the main shaft 4 and the liner). Further, the vane provided for the main shaft 4 is provided at a portion of the main shaft 4 where the liner is located. Therefore, since the vane is urged to the outer side in the radial direction of the main shaft 4 as described above, the vane comes into contact with the inner peripheral surface (surface forming the internal space) of the liner. A seal surface is formed at a predetermined position on each of the inner peripheral surface of the liner and the outer peripheral surface of the main shaft 4. The sealing surface of the inner peripheral surface of the liner, the sealing surface of the outer peripheral surface of the main shaft 4 and the vane are matched by relative rotation between the liner and the main shaft 4, and the inner space of the liner and the high-pressure chamber are matched with each other. Divide into low pressure chambers.
With such a configuration, when the liner rotates with the rotation of the rotor 5 of the air motor 3, the liner and the seal surface of the outer peripheral surface of the spindle 4 and the vane each match the liner. Is transmitted to the main shaft 4 via the hydraulic oil.

As described above, the continuous rotational torque from the air motor 3 is converted into a pulsed impact torque on the main shaft 4. For example, Patent Document 2, Patent Document 3, and Patent Document 4 can be referred to as known configurations for the impact torque generating device 8.
The impact torque generating device 8 of the present embodiment is a hydraulic type, but instead of this, a mechanical impact torque generating device that mechanically generates an impact force by the rotational force of the rotor 5 may be used. Good.

In addition, the torque wrench of the present embodiment includes an operation stop mechanism (not shown) in the tool body 1. The operation stop mechanism operates the tool body 1 (operation of the air motor 3) when the tightening torque reaches a predetermined value (hereinafter referred to as “target torque”) when tightening the screw with a torque wrench. Is a configuration for automatically stopping.
In the present embodiment, the operation stop mechanism is schematically configured as follows.

  That is, the operation stop mechanism has a shutoff valve that communicates with the inner space of the liner in the impact torque generating device 8 as described above. The shutoff valve closes to shut off the supply of high-pressure air to the air motor 3. In the operation stop mechanism, a predetermined pressure is set in advance for the high pressure chamber formed in the internal space filled with the hydraulic oil as the liner rotates in the impact torque generating device 8.

In the torque wrench, the main valve 7 is opened by operating the operation lever 6 when tightening the screws. When the main valve 7 is opened, high-pressure air is supplied to the air motor 3 and the rotor 5 is rotationally driven. As a result, the liner of the impact torque generating device 8 rotates and a pulsed impact torque is applied to the main shaft 4. At this time, the pressure of the high-pressure chamber formed in the striking torque generator 8 is applied with a pulse-shaped striking torque (operation of the air motor 3 (rotation of the rotor 5)) until the predetermined pressure is reached. Screws are tightened.
That is, as the tightening of the screw proceeds, the tightening torque increases, and the pressure in the high-pressure chamber in the impact torque generating device 8 increases accordingly. When the pressure in the high-pressure chamber reaches the predetermined pressure, the high-pressure side hydraulic oil in the inner space of the liner closes the shut-off valve, and the operation of the air motor 3 (rotation of the rotor 5) stops. . As a result, the application of the pulsed impact torque to the main shaft 4 is stopped.

As described above, when the screw is tightened with the torque wrench and the tightening torque reaches the target torque, the operation of the tool body 1 (operation of the air motor 3) is automatically stopped.
Note that the configuration of the operation stop mechanism is not limited to this embodiment. Other known configurations can be employed as the operation stopping mechanism. As a known configuration of the operation stop mechanism, for example, Patent Document 3 can be referred to.

  Further, the torque wrench of the present embodiment includes a torque sensor 10 as a tightening torque detection unit that detects a tightening torque of the screw, and an angle sensor 20 as a rotation angle detection unit that detects the rotation angle of the main shaft 4. .

As shown in FIG. 1, the torque sensor 10 of the present embodiment is provided in the housing 2 and has a magnetostrictive type having an excitation coil 11 and a detection coil 12 arranged so as to go around a predetermined portion of the main shaft 4. Configured as a sensor. In the main shaft 4, a groove processing portion 4 a in which the outer peripheral surface of the main shaft 4 is grooved is provided at a predetermined portion where the exciting coil 11 and the detection coil 12 are disposed.
In the torque sensor 10 having such a configuration, a magnetic field is formed by the excitation coil 11, and the change in permeability through the groove processing portion 4a of the main shaft 4 is related to (proportional to) the magnitude of the torque. Is detected as a change. That is, in the torque sensor 10 configured as a magnetostrictive sensor, the torque (tightening torque) transmitted by the main shaft 4 is converted by converting the change in the output voltage from the detection coil 12 accompanying the change in the magnetic permeability of the main shaft 4. Is detected. A detection signal (voltage signal) from the torque sensor 10 is transmitted to the controller 50 (see FIG. 2) via the cable 14 arranged in the housing 2 and led out from the end of the grip portion 2a.
The configuration of the torque sensor 10 is not limited to this embodiment. As torque sensor 10, various torque sensors, such as a strain gauge type sensor, are employable, for example.

Similarly, as shown in FIG. 1, the angle sensor 20 of the present embodiment is provided in the housing 2, a rotor core 21 provided in a predetermined portion of the main shaft 4, and a stator provided so as to go around the rotor core 21. The magnetic sensor includes an iron core 22 and a stator coil 23 wound around the stator iron core 22.
In the angle sensor 20 having such a configuration, when the stator coil 23 is excited as the main shaft 4 rotates, an output voltage is induced in the stator coil 23. Since the output voltage of the stator coil 23 varies depending on the rotation angle of the main shaft 4, the output voltage of the stator coil 23 is detected. That is, in the angle sensor 20 configured as a magnetic sensor, the rotation angle of the main shaft 4 is detected by converting the output voltage from the stator coil 23 as the main shaft 4 rotates. A detection signal (voltage signal) from the angle sensor 20 is transmitted to the controller 50 (see FIG. 2) via the cable 24 arranged along the housing 2 and led out from the end of the grip portion 2a.
The configuration of the angle sensor 20 is not limited to this embodiment. As angle sensor 20, various angle sensors, such as an optical sensor, can be adopted, for example.

  Moreover, as shown in FIG. 2, the torque wrench of this embodiment is provided with the controller 50 as a control apparatus. The controller 50 includes a control unit 51 and a display unit 52.

The control unit 51 controls the operation of the tool body 1. The control unit 51 is essentially a storage unit that stores various programs, a development unit that develops these programs, a computation unit that performs predetermined computations according to these programs, a computation result by the computation unit, and the like. A storage unit for storing, a storage unit for storing values set in advance for the tightening torque, the rotation angle of the spindle 4, and the like are provided. The program stored in the storage unit includes a tightening failure detection program to be described later. Specifically, as the control unit 51, a configuration in which a CPU, a ROM, a RAM, an HDD, or the like is connected by a bus, or a configuration that includes a one-chip LSI or the like is used.
Note that the control unit 51 of the present embodiment is a dedicated product, but it may be replaced with a computer in which the above-described program is stored in a commercially available personal computer or workstation. Moreover, in the torque wrench of this embodiment, although the control part 51 is the structure incorporated in the controller 50 separate from the tool main body 1, it is not limited to this. That is, the structure provided in the tool main body 1 side, such as the control part 51 in this embodiment being equipped with the housing 2 of the tool main body 1, may be sufficient.

  A torque sensor 10 and an angle sensor 20 provided in the tool body 1 are connected to the control unit 51. That is, the torque sensor 10 is connected to the controller 51 of the controller 50 via the cable 14 derived from the housing 2 as described above, and the angle sensor 20 is also connected to the controller 50 via the cable 24 derived from the housing 2. Connected to the control unit 51. And the detection signal by the torque sensor 10 and the angle sensor 20 is each transmitted to the control part 51 via each cable 14 * 24. Thereby, the control unit 51 acquires the detection signal from the torque sensor 10 and the detection signal from the angle sensor 20, and measures the value of the tightening torque and the value of the rotation angle of the main shaft 4 based on the detection signal. . That is, the torque sensor 10 detects the tightening torque value, and the angle sensor 20 detects the rotation angle value of the spindle 4.

The display unit 52 displays the relationship between the value of the tightening torque detected by the torque sensor 10 shown by a graph or the like and the value of the rotation angle of the main shaft 4 detected by the angle sensor 20, and tightening when tightening the screws. Display failure detection results.
The display unit 52 of the present embodiment is a dedicated product, but can be replaced with a commercially available monitor or liquid crystal display.

  Control of the torque wrench of the present embodiment having the above configuration will be described. The torque wrench control described below is for detecting a tightening failure when a screw is tightened by the torque wrench.

  The torque wrench according to the present embodiment includes a determination unit 53 in the control unit 51 of the controller 50 for the control. The determination unit 53 is an embodiment of the determination unit according to the present invention, and determines a tightening failure with respect to screw tightening. Substantially, the control unit 51 functions as the determination unit 53 by performing a predetermined calculation or the like in accordance with the tightening failure detection program stored in the storage unit.

When detecting a tightening failure in the torque wrench of the present embodiment, the value of the screw tightening torque (hereinafter simply referred to as “tightening torque”) detected by the torque sensor 10 and the spindle detected by the angle sensor 20. A rotation angle of 4 (hereinafter simply referred to as “rotation angle”) is used. Then, whether or not the graph showing the relationship between the value of the rotation angle and the value of the tightening torque falls within a predetermined pass area on the coordinate plane on which the graph is shown determines whether or not the screw has been tightened. Is called. That is, a case where the graph indicating the relationship between the value of the rotation angle and the value of the tightening torque does not enter the predetermined pass area is detected as a tightening failure.
This will be specifically described below.

  In the control of the torque wrench according to the present embodiment, the determination unit 53 determines a predetermined torque that is set in advance for each of the tightening torque value detected by the torque sensor 10 and the rotation angle value detected by the angle sensor 20. Based on the acceptable range, it detects a tightening failure when tightening a screw. That is, determination logic based on the passing ranges of the tightening torque value detected by the torque sensor 10 and the rotation angle value detected by the angle sensor 20 is incorporated in the controller 50 (control unit 51) in advance. According to the determination logic, the determination unit 53 detects a tightening failure during tightening of the screw.

Predetermined acceptable ranges set in advance for each of the tightening torque value and the rotation angle value are determined based on the respective values when normal screw tightening is performed without causing a tightening failure. .
That is, when tightening the screw, when the normal screw is tightened, the value of the tightening torque increases as the value of the rotation angle increases, and the value of the rotation angle is within a predetermined range. The value of the tightening torque reaches the target torque. That is, when normal screw tightening is performed, the range of the rotation angle value when the tightening torque value reaches the target torque is determined to some extent in the relationship between the rotation angle value and the tightening torque value. When the value of the tightening torque reaches the target torque in that range, it is ensured that the quality of the screw tightening is a non-defective product without causing a tightening failure.

Therefore, the acceptable range for each of the tightening torque value and the rotation angle value is set in advance based on the relationship between the rotation angle value and the tightening torque value when normal screw tightening is performed. Is done. The pass range is set in advance in the control unit 51 for each of the tightening torque value and the rotation angle value.
The setting of the acceptable range for each of the tightening torque value and the rotation angle value will be described with reference to the graph shown in FIG. In the following description, a predetermined pass range preset for the tightening torque value detected by the torque sensor 10 is referred to as a “torque value pass range”, and the rotation angle value detected by the angle sensor 20 is set in advance. The predetermined pass range to be set is defined as “angle value pass range”.

FIG. 3 is a graph showing the relationship between the value of the rotation angle (deg) and the value of the tightening torque (N · m) when tightening the screw.
In the graph of FIG. 3, a graph A <b> 11 indicated by a solid line is an example of a graph corresponding to a case where the screws are normally tightened. That is, the graph A11 shows an example of the relationship between the rotation angle value and the tightening torque value when normal screw tightening is performed. An example in which the torque value passing range and the angle value passing range are set based on the graph A11 corresponding to the case where the normal screw tightening is performed will be described.

  Here, with respect to the value of the rotation angle, a torque corresponding to the value of the torque generated when the screw contacts the seat surface of the workpiece (the screw is seated on the workpiece) (hereinafter referred to as “start torque”). The value at the time when the error occurs becomes the reference (0 deg). In other words, the value of the tightening torque when the start torque (see symbol STo) is reached is the reference (0 N · m). Therefore, in the graph shown in FIG. 3, the portion (thin line portion) where the rotation angle value is 0 deg or less is the time from when the operating lever 6 is turned on until the tightening torque reaches the start torque in the torque wrench of this embodiment. Indicates the state (hereinafter referred to as “free-run state”).

In the graph shown in FIG. 3, the value ToS for the tightening torque value indicates the target torque. The torque value pass range is set based on the target torque value ToS. That is, in this case, the torque value passing range is set as a predetermined range D1 of the tightening torque value with the target torque value ToS as a reference (center value).
Further, the angle value pass range is a rotation angle based on the rotation angle value AS when the graph A11 corresponding to normal screw tightening reaches the target torque value as a reference (center value). Is set as a predetermined range D2.
Here, the predetermined range based on the target torque value ToS for the torque value pass range D1 and the predetermined range based on the rotation angle value AS for the angle value pass range D2 are, for example, normal screw Is determined in consideration of an error range and the like for a large number of graphs (data) corresponding to the case where the tightening is performed.

  As described above, the predetermined range is set for each of the tightening torque value and the rotation angle value, so that the region satisfying both the predetermined ranges on the coordinate plane indicating the relationship between the rotation angle and the tightening torque. Is defined. That is, as shown by the hatched portion in FIG. 3, a region B1 that satisfies both the torque value passing range D1 and the angle value passing range D2 is defined on the coordinate plane indicating the relationship between the rotation angle and the tightening torque. The The area B1 that satisfies both of the acceptable ranges is the above-described acceptable area. In other words, in the torque wrench control of the present embodiment, when the screw is tightened, a case where the graph showing the relationship between the rotation angle value and the tightening torque value does not fall within the pass region B1 is detected as a tightening failure. The

Therefore, when the torque wrench is controlled in tightening the screw, the determination unit 53 uses the following two relations between the rotation angle value and the tightening torque value based on the torque value pass range D1 and the angle value pass range D2. The case is detected as tightening failure.
That is, when the rotation angle value detected by the angle sensor 20 (hereinafter referred to as “detection angle value”) reaches the upper limit value of the angle value pass range D2, the tightening torque value detected by the torque sensor 10 ( (Hereinafter referred to as “detected torque value”) is smaller than the lower limit value of the torque value pass range D1, and when the detected torque value reaches the upper limit value of the torque value pass range D1, the detected angle value is the angle value pass range D2. Is smaller than the lower limit of.

In the graph of FIG. 3, a graph A <b> 12 indicated by a broken line is the former of the two cases (hereinafter referred to as “two cases in the angle-torque relationship”) in the relationship between the rotation angle value and the tightening torque value. This is an example of a graph corresponding to the case (hereinafter also referred to as “the former case in the angle-torque relationship”). That is, in the screw tightening shown in the graph A12, when the detected angle value reaches the upper limit value AP _max of the angle value passing range D2, the detected torque value becomes smaller than the lower limit value ToP _min of the torque value passing range D1. ing. In such a case, the graph A12 does not enter the pass area B1. That is, in this case, the determination unit 53 detects the tightening failure.

In the graph of FIG. 3, a graph A13 indicated by an alternate long and short dash line corresponds to the latter case (hereinafter also referred to as “the latter case in the angle-torque relationship”) among the two cases in the angle-torque relationship. It is an example. That is, in the screw tightening shown in the graph A13, when the detected torque value reaches the upper limit value ToP _max of the torque value pass range D1, the detected angle value becomes smaller than the lower limit value AP _min of the angle value pass range D2. ing. In such a case, the graph A13 does not enter the pass area B1. That is, also in this case, the determination unit 53 detects the tightening failure.

  As described above, when the screw is tightened, the two cases in the angle-torque relationship indicate that the graph indicating the relationship between the rotation angle value and the tightening torque value does not enter the pass region B1, and is detected as a tightening failure. Is done.

As described above, in the torque wrench of the present embodiment, as a tightening failure detection method, when tightening a screw, the tightening torque and the rotation angle are detected, and based on the torque value passing range D1 and the angle value passing range D2, When the detected angle value reaches the upper limit value AP _max of the angle value pass range D2, the detected torque value is smaller than the lower limit value ToP _min of the torque value pass range D1, and the detected torque value is the upper limit value of the torque value pass range. When the ToP _max is reached, a case where the detected angle value is smaller than the lower limit value AP _min of the angle value pass range D2 is detected as a tightening failure.

  By controlling the torque wrench in this way, it is possible to detect any tightening failure when tightening the screw, and to improve the tightening accuracy. Can improve quality.

That is, when a screw is tightened, if the torque wrench is controlled based only on the tightening torque value, it can be detected from the tightening torque value even if a tightening failure occurs. Although not possible, as described above, the torque wrench is controlled based on the value of the tightening torque and the value of the rotation angle, so that it is possible to detect a tightening failure. In other words, the relationship between the value of the rotation angle and the value of the tightening torque at the time of screw tightening differs depending on whether the screw is tightened normally or when a tightening failure occurs. Based on this, it is possible to detect a tightening failure.
As a result, even in a hand-held pulse tool such as the torque wrench of the present embodiment, it is possible to discriminate between a non-defective product and a defective product with respect to the screw tightening quality, and it is possible to fasten a highly accurate and traceable screw. It is possible to prevent the outflow of a defective product including a tightening defect in the fastening portion by the screw.

By the way, there are a plurality of types of tightening failures in the tightening of the screws detected as described above. It can be said that the tightening failure corresponds to one of two cases in the angle-torque relationship depending on the type.
Therefore, when the screw is tightened, each case occurs in the relationship between the rotation angle value and the tightening torque value, that is, the former case in the angle-torque relationship and the latter case in the angle-torque relationship. A specific example of the type of tightening failure will be described with reference to a graph for each type using FIG.

  Each graph shown in FIG. 4 is a graph showing the relationship between the rotation angle value and the tightening torque value. As for the value of the rotation angle, the value at the time when the start torque is generated becomes the reference (0 deg). In this example, the torque value pass range is set to about ± 5 N · m, that is, about 25 to 35 N · m, based on the target torque (see straight line T1) which is 30 N · m. It is set as about 80 to 130 deg, and the pass area B1 is defined by each of these ranges.

  First, among the two cases in the angle-torque relationship, examples of the types of tightening failure that may occur in the former case include screw crushing, bearing crushing, and slanting.

FIG. 4 (a) shows a case where screw crushing occurs as a tightening failure. In other words, this is a case where the thread of the threaded portion of the bolt, nut, or the like is crushed when the screw is tightened.
In this case, a point in time when the detection of the rotation angle is started when a slight amount of torque generated by the screw sitting on the workpiece (or a torque generated by screwing of the screw having a corresponding size) is generated. (When the value of the rotation angle is 0 deg). Then, the value of the tightening torque rapidly increases due to the screwing of the screw, and then the magnitude of the tightening torque becomes substantially flat as the value of the rotation angle increases (the rotation of the main shaft 4 advances). As described above, when the screw thread is crushed as a tightening failure, the tightening torque value hardly increases and the rotation angle value increases even if the screw is tightened (rotation of the main shaft 4). As a result, the rotation angle is exceeded. That is, when the detected angle value reaches the upper limit value of the angle value pass range, the detected torque value is smaller than the lower limit value of the torque value pass range, and the graph shows the pass region B1 as the former in the angle-torque relationship. Will not enter.

FIG. 4B shows a case where crushing of the seat surface occurs as a tightening failure. In other words, when the screw is tightened, the seat surface that is the surface where the screw comes into contact with the workpiece is crushed (depressed) by the screw tightening.
In this case, the point in time at which a slight amount of torque generated when the screw is seated on the workpiece is the point in time when the detection of the rotation angle is started (the value of the rotation angle is 0 deg). Then, the value of the tightening torque rapidly increases due to the screwing of the screw, and then the magnitude of the tightening torque gradually increases as the value of the rotation angle increases (the rotation of the main shaft 4 advances). . As described above, when the bearing surface is crushed as a tightening failure, the tightening torque value increases only slightly even if the screws are tightened (rotation of the main shaft 4), and the rotation angle value is It increases and the rotation angle is over. That is, also in this case, when the detected angle value reaches the upper limit value of the angle value passing range, the detected torque value becomes smaller than the lower limit value of the torque value passing range, and the graph is as shown in the former case in the angle-torque relationship. It will not enter the acceptance area B1.

FIG. 4 (c) shows a case where oblique insertion occurs as a tightening failure. That is, when tightening a screw, for example, a male screw portion such as a bolt is screwed in an oblique direction with respect to a female screw portion such as a nut or a screw hole.
In this case, a graph that is substantially the same as that in the case of the collapsed bearing surface described above is shown. In other words, when there is an oblique insertion as a tightening failure, the tightening torque value only slightly increases and the rotation angle value increases even if the screw is tightened (rotation of the main shaft 4). The rotation angle is over. That is, also in this case, when the detected angle value reaches the upper limit value of the angle value passing range, the detected torque value becomes smaller than the lower limit value of the torque value passing range, and the graph is as shown in the former case in the angle-torque relationship. It will not enter the acceptance area B1.

  Next, of the two cases in the angle-torque relationship, an example of the type of tightening failure that may occur in the latter case is a washer missing.

FIG. 4D shows a case where a washer missing occurs as a tightening failure. In other words, for the reasons such as stabilizing the seat surface when tightening the screws, an interposition member such as a washer may be used, for example, between the bolt and the workpiece in the fastening portion with the screw. This is a case where the interposed member is missing.
In this case, since the intervening member is missing, the value of the rotation angle is slightly increased from the time when the detection of the rotation angle is started (the value of the rotation angle is 0 deg) without increasing the tightening torque value. (The rotation of the main shaft 4 proceeds). Thereafter, the value of the tightening torque increases rapidly due to screwing. This is because the amount of bending of the portion fastened by the screw is reduced by the amount of the interposed member missing, and therefore the rotation angle (rotation amount) until the tightening torque value increases is reduced. As described above, when a washer is missing as a tightening failure, the tightening torque value is rapidly increased and the rotation angle value is excessively small due to screw tightening (rotation of the main shaft 4). It becomes. That is, when the detected torque value reaches the upper limit value of the torque value pass range, the detected angle value is smaller than the lower limit value of the angle value pass range, and the graph shows the pass region B1 as the latter case in the angle-torque relationship. Will not enter.

As described above, there are two cases in the angle-torque relationship in which the tightening failure is considered to occur in the screw tightening, that is, the former case and the latter case in the relationship between the rotation angle value and the tightening torque value described above. Therefore, it is possible to identify the type of tightening failure to some extent.Therefore, when a tightening failure is detected from the relationship between the rotation angle value and the tightening torque value as described above. By notifying which one of the two cases in the angle-torque relationship is true, the type of tightening failure that has occurred can be recognized by the operator. That is, as described above, in the relationship between the value of the rotation angle and the value of the tightening torque, when the graph indicating the relationship does not fall within the acceptance region B1 (two cases in the angle-torque relationship), the tightening failure is not. By using the technique of assuming occurrence, each case can be applied to the identification of the type of tightening failure. Also from such a point, as described above, a method of detecting a tightening failure from the relationship between the value of the rotation angle and the value of the tightening torque is useful when tightening the screw.

In addition, in the torque wrench of this embodiment, the value of the elapsed time is used in addition to the value of the tightening torque and the value of the rotation angle when detecting a tightening failure in tightening the screw.
Therefore, the torque wrench of the present embodiment includes a timer 54 as an elapsed time measuring unit that measures an elapsed time from a predetermined reference time in screw tightening (see FIG. 2).

The timer 54 is provided in the controller 50. The timer 54 is connected to the control unit 51. A measurement signal from the timer 54 is transmitted to the control unit 51. Thereby, the control part 51 acquires the measurement signal from the timer 54, and measures the elapsed time from the predetermined | prescribed reference time in tightening of a screw based on this measurement signal. In other words, the timer 54 measures the elapsed time from the predetermined reference time.
Here, the configuration and method for measuring the elapsed time from the predetermined reference time are not particularly limited, and a known configuration can be adopted. In the torque wrench of the present embodiment, the timer 54 is built in the controller 50 separate from the tool body 1, but is not limited to this. In other words, the timer 54 may be provided on the tool body 1 side, such as being housed in the housing 2 of the tool body 1.

When detecting a tightening failure in the torque wrench of the present embodiment described below, the relationship between the value of the tightening torque detected by the torque sensor 10 and the value of the rotation angle detected by the angle sensor 20 , The value of the elapsed time measured by the timer 54 is used. That is, the relationship between the elapsed time value measured by the timer 54 and the tightening torque value detected by the torque sensor 10, or the elapsed time value measured by the timer 54 and the rotation angle measured by the angle sensor 20. The relationship with the value of is used respectively. And a graph showing the relationship between the value of the elapsed time and the value of the tightening torque, or a graph showing the relationship between the value of the elapsed time and the value of the rotation angle is in a predetermined pass area on the coordinate plane where the graph is shown. Depending on whether or not it is inserted, it is determined whether or not the screw is tightened. In other words, if the graph indicating the relationship between the elapsed time value and the tightening torque value and the graph indicating the relationship between the elapsed time value and the rotation angle value do not fall within the predetermined pass range, Detected.
This will be specifically described below.

First, the control (hereinafter referred to as “time-torque control”) when the relationship between the value of the elapsed time and the value of the tightening torque is used in the torque wrench of the present embodiment will be described.
In the time-torque control in the torque wrench of the present embodiment, the determination unit 53 is preset with respect to the torque value passing range D1 and the value of the elapsed time from the predetermined reference time for screw tightening, which is measured by the timer 54. Based on the acceptable range, it detects the tightening failure when tightening the screw. That is, determination logic based on the passing ranges of the tightening torque value detected by the torque sensor 10 and the elapsed time value measured by the timer 54 is incorporated in the controller 50 (control unit 51), and the determination is made. According to the logic, the determination unit 53 detects a tightening failure at the time of tightening the screw.

A predetermined pass range set in advance for the value of the elapsed time is determined based on a value when normal screw tightening is performed without causing a tightening failure.
That is, when tightening a screw, when the normal screw is tightened, the value of the tightening torque increases as the elapsed time value increases, and the elapsed time value is within a predetermined range. The value of the tightening torque will be within the torque value pass range D1. In other words, when normal screw tightening is performed, the range of the elapsed time value when the tightening torque value reaches the target torque is determined to some extent in the relationship between the elapsed time value and the tightening torque value. When the value of the tightening torque reaches the target torque in that range, it is ensured that the quality of the screw tightening is a non-defective product without causing a tightening failure.

Therefore, the pass range for the elapsed time value is set in advance based on the relationship between the elapsed time value and the tightening torque value when normal screw tightening is performed. Setting of the pass range for the elapsed time value is performed in advance in the control unit 51.
The setting of the pass range for such an elapsed time value will be described using the graph shown in FIG. In the following description, a predetermined pass range preset for the value of the elapsed time detected by the timer 54 is referred to as a “time value pass range”.

FIG. 5 is a graph showing the relationship between the elapsed time value (msec) and the tightening torque value (N · m) during screw tightening.
In the graph of FIG. 5, a graph A <b> 21 indicated by a solid line is an example of a graph corresponding to a case where the screws are normally tightened. That is, the graph A21 shows an example of the relationship between the elapsed time value and the tightening torque value when normal screw tightening is performed. An example in which the time value passing range is set based on the graph A21 corresponding to the case where the normal screw tightening is performed will be described.

  Here, with respect to the value of the elapsed time, the value at the time when the start torque (see the symbol STo) is generated becomes the reference (0 msec). Therefore, in the present embodiment, the predetermined reference time for screw tightening with respect to the elapsed time measured by the timer 54 is the time when the start torque is generated. In the graph shown in FIG. 5, a portion (thin line portion) whose elapsed time value is 0 msec or earlier indicates a free run state in the torque wrench of the present embodiment.

In the graph shown in FIG. 5, the time value passing range is based on the elapsed time value TiS when the graph A21 corresponding to normal screw tightening reaches the target torque value (center value). ) And a predetermined range D3 of the elapsed time value.
Here, the predetermined range based on the elapsed time value TiS for the time value pass range D3 is, for example, an error range for a large number of graphs (data) corresponding to normal screw tightening, etc. Is taken into consideration.

  In this way, by setting a predetermined range for the value of the elapsed time, a region that satisfies both the predetermined ranges is defined on the coordinate plane indicating the relationship between the elapsed time and the tightening torque. That is, as indicated by the hatched portion in FIG. 5, a region B2 that satisfies both the torque value passing range D1 and the time value passing range D3 is defined on the coordinate plane indicating the relationship between the elapsed time and the tightening torque. The The region B2 that satisfies both the acceptable ranges is the above-described acceptable region. That is, in the time-torque control in the torque wrench of the present embodiment, when a screw is tightened, a graph indicating the relationship between the elapsed time value and the tightening torque value does not fall within the pass area B2, and the tightening failure Detected as

Therefore, when the torque wrench is controlled in tightening the screw, the determination unit 53 uses the following two relations between the elapsed time value and the tightening torque value based on the torque value passing range D1 and the time value passing range D3. The case is detected as tightening failure.
That is, when the value of the elapsed time measured by the timer 54 (hereinafter referred to as “measurement time value”) reaches the upper limit value of the time value pass range D3, the detected torque value is greater than the lower limit value of the torque value pass range D1. This is a case where the measured time value is smaller than the lower limit value of the time value pass range D3 when the detected torque value reaches the upper limit value of the torque value pass range D1.

In the graph of FIG. 5, a graph A22 indicated by a broken line is the former of the two cases (hereinafter referred to as “two cases in the time-torque relationship”) in the relationship between the elapsed time value and the tightening torque value. It is an example of the graph corresponding to the case of. That is, in the screw tightening shown in the graph A22, when the measured time value reaches the upper limit value TiP _max of the time value pass range D3, the detected torque value becomes smaller than the lower limit value ToP _min of the torque value pass range D1. ing. In such a case, the graph A22 does not enter the pass area B2. That is, in this case, the determination unit 53 detects the tightening failure.

In the graph of FIG. 5, a graph A <b> 23 indicated by an alternate long and short dash line is an example of a graph corresponding to the latter case among the two cases in the time-torque relationship. That is, in the screw tightening shown in the graph A23, when the detected torque value reaches the upper limit value ToP _max of the torque value passing range D1, the measured time value becomes smaller than the lower limit value TiP _min of the time value passing range D3. ing. In such a case, the graph A23 will not enter the pass area B2. That is, also in this case, the determination unit 53 detects the tightening failure.

  Thus, when tightening a screw, the two cases in the time-torque relationship indicate that the graph indicating the relationship between the elapsed time value and the tightening torque value does not fall within the pass region B2, and is detected as a tightening failure. Is done.

As described above, in the torque wrench of this embodiment, as a tightening failure detection method, when tightening a screw, the screw tightening from a predetermined reference time (when the tightening torque value reaches the start torque) is determined. The elapsed time is measured, and when the measured time value reaches the upper limit value TiP _max of the time value pass range D3 based on the time value pass range D3, the detected torque value is smaller than the lower limit value ToP _min of the torque value pass range D1. If the measured time value is smaller than the lower limit value TiP _min of the time value pass range D3 when the detected torque value reaches the upper limit value ToP _max of the torque value pass range D1, the tightening failure is detected.

  Thus, it is possible to detect a tightening failure by controlling the torque wrench based on the value of the elapsed time and the value of the tightening torque. In other words, the relationship between the elapsed time value and the tightening torque value during screw tightening differs depending on whether the screw is tightened normally or when a tightening failure occurs. Based on this, it is possible to detect a tightening failure.

Next, the control (hereinafter referred to as “time-angle control”) when the relationship between the value of the elapsed time and the value of the rotation angle is used in the torque wrench of the present embodiment will be described.
In the time-angle control in the torque wrench of the present embodiment, the determination unit 53 detects a tightening failure during tightening of the screw based on the angle value pass range D2 and the time value pass range D3. That is, the determination logic based on the passing ranges of the rotation angle value detected by the angle sensor 20 and the elapsed time value measured by the timer 54 is incorporated in the controller 50 (control unit 51), and the determination logic Accordingly, the determination unit 53 detects a tightening failure at the time of tightening the screw.

FIG. 6 is a graph showing a relationship between an elapsed time value (msec) and a rotation angle value (deg) when tightening a screw.
In the graph of FIG. 6, a graph A <b> 31 indicated by a solid line is an example of a graph corresponding to a case where the screws are normally tightened. That is, the graph A31 shows an example of the relationship between the value of the elapsed time and the value of the rotation angle when normal screw tightening is performed.

  Here, as for the value of the elapsed time, the value at the time when the start torque is generated is the reference (0 msec), as in the case of the time-torque control described above. Therefore, the value at the time when the start torque is generated is the reference (0 deg) for the value of the rotation angle, and in the graph shown in FIG. 6, the portion where the elapsed time value is 0 msec or earlier (thin line portion) is the present embodiment. The free-run state of the torque wrench is shown.

  In the time-angle control, as indicated by the hatched portion in FIG. 6, in the coordinate plane indicating the relationship between the elapsed time and the rotation angle, the region satisfying both the angle value passing range D2 and the time value passing range D3. B3 is defined. The region B3 that satisfies both the acceptable ranges is the above-described acceptable region. In other words, in the time-angle control in the torque wrench of the present embodiment, when the screw is tightened, a graph indicating the relationship between the value of the elapsed time and the value of the rotation angle does not enter the pass area B3. Detected.

Therefore, when the torque wrench is controlled in tightening the screw, the determination unit 53 is based on the angle value passing range D2 and the time value passing range D3 in the following two cases in the relationship between the elapsed time value and the rotation angle value: Is detected as a tightening defect.
That is, when the measured time value reaches the upper limit value of the time value pass range D3, the detected angle value is smaller than the lower limit value of the angle value pass range D2, and the detected angle value becomes the upper limit value of the angle value pass range D2. In this case, the measured time value is smaller than the lower limit value of the time value pass range D3.

In the graph of FIG. 6, a graph A32 indicated by a broken line is the former of the two cases (hereinafter referred to as “two cases in the time-angle relationship”) in the relationship between the elapsed time value and the rotation angle value. It is an example of the graph corresponding to a case. That is, in tightening the screw shown in the graph A32, when the measurement time value reaches the upper limit value TiP _max of the time value pass range D3, the detected angle value becomes smaller than the lower limit value AP _min of the angle value pass range D2. ing. In such a case, the graph A32 does not enter the pass area B3. That is, in this case, the determination unit 53 detects the tightening failure.

In the graph of FIG. 6, a graph A33 indicated by a one-dot chain line is an example of a graph corresponding to the latter case among the two cases in the time-angle relationship. That is, in the screw tightening shown in the graph A33, when the detected angle value reaches the upper limit value AP _max of the angle value pass range D2, the measurement time value becomes smaller than the lower limit value TiP _min of the time value pass range D3. ing. In such a case, the graph A33 does not enter the pass area B3. That is, also in this case, the determination unit 53 detects the tightening failure.

  As described above, when tightening the screw, the two cases in the time-angle relationship indicate that the graph showing the relationship between the value of the elapsed time and the value of the rotation angle does not enter the pass region B3, and is detected as a tightening failure. The

As described above, in the torque wrench of this embodiment, as a tightening failure detection method, when tightening a screw, the screw tightening from a predetermined reference time (when the tightening torque value reaches the start torque) is determined. The elapsed time is measured, and when the measured time value reaches the upper limit value TiP _max of the time value pass range D3 based on the time value pass range D3, the detected angle value is smaller than the lower limit value AP _min of the angle value pass range D2. If the measured time value is smaller than the lower limit value TiP _min of the time value pass range D3 when the detected angle value reaches the upper limit value AP _max of the angle value pass range D2, the fastening failure is detected.

  In this manner, the tightening failure can be detected by controlling the torque wrench based on the elapsed time value and the rotation angle value. In other words, the relationship between the value of the elapsed time and the value of the rotation angle at the time of tightening the screw is different depending on whether the tightening of the screw is normally performed or when the tightening failure occurs. This makes it possible to detect tightening defects.

Further, in the torque wrench of the present embodiment, the tightening torque is based on the detected angle value or measured time value in the free run state from when the operating lever 6 is turned on until the tightening torque reaches the start torque. Defective attachment, especially initial abnormality before the screw is seated, is detected.
In other words, when normal screw tightening is performed, the amount of increase in the rotation angle value and elapsed time value in the free run state (the value of the rotation angle when the free run state ends) And the value of the elapsed time) are larger than a certain level. In other words, when tightening a screw, if a so-called double tightening occurs, such as when the screw is tightened again against the tightened portion of the screw once tightened, the rotation angle value and progress in the free-run state The increase in time value is extremely small. Therefore, when a case where the increase amount of the rotation angle value or the increase amount of the elapsed time value in the free-run state is less than the predetermined value is detected, the screw tightening such as the second tightening as described above is performed. It is possible to detect an initial abnormality in.

Therefore, the determination unit 53 determines the minimum torque that is set in advance for each of the start torque, the rotation angle value, and the elapsed time value that are set as initial reference values in the tightening of the screws. Based on the value, when the detected torque value reaches the start torque, the case where the detected angle value or the measured time value is smaller than the minimum reference value is detected as a fastening failure.
The minimum reference value for each of the start torque for the tightening torque value, the rotation angle value, and the elapsed time value is set in advance in the control unit 51. In the following description, the minimum reference value for the rotation angle value is referred to as “minimum angle reference value”, and the minimum reference value for the elapsed time value is referred to as “minimum time reference value”. In the torque wrench of the present embodiment, the control for detecting the tightening failure based on the free-run state is referred to as “initial abnormality detection control”.

First, the case where the rotation angle value is used in the initial abnormality detection control in the torque wrench of the present embodiment will be described with reference to FIG.
In this case, the determination unit 53 determines the detected angle value when the detected torque value reaches the start torque STo based on the start torque (see symbol STo, hereinafter referred to as “start torque STo”) and the minimum angle reference value A0. A case where the angle is smaller than the minimum reference value A0 is detected as a tightening failure.

That is, in the graph shown in FIG. 3, the point indicated by reference numeral O1 is the time when the operation lever 6 is turned on. That is, detection of the value of the tightening torque and the value of the rotation angle is started from the time when the operation lever 6 is turned on. In the following description, the time point indicated by reference numeral O1 when the operation lever 6 is turned on is referred to as “starting point O1”. When the screw is tightened, the torque wrench is in a free run state from the start point O1 until the detected torque value reaches the start torque STo.
In the free run state of the torque wrench, when the amount of increase in the value of the rotation angle in the free run state (see symbol FrA) is smaller than the minimum angle reference value A0, that is, when the free run state ends ( the value a _ST of the rotation angle of the detection torque value reaches the start torque STo point) is smaller than the angle minimum reference value A0 is detected as defective tightening.

Therefore, the graph shown in FIG. 3 shows that in the initial abnormality detection control in the torque wrench of the present embodiment, the rotation angle value _AST at the time when the free-run state is finished is not smaller than the minimum angle reference value A0. Is an example of a case where the tightening failure is not detected.

Next, the case where the value of elapsed time is used in the initial abnormality detection control in the torque wrench of this embodiment will be described with reference to FIG.
In this case, the determination unit 53 determines that if the measured time value is smaller than the minimum time reference value Ti0 when the detected torque value reaches the start torque STo based on the start torque STo and the minimum time reference value Ti0, the tightening failure is determined. Detect as.

That is, in the graph shown in FIG. 5, the detection of the tightening torque value and the measurement of the elapsed time value are started from the start point O1.
In the free run state of the torque wrench, when the amount of increase in the value of the elapsed time in the free run state (see the sign FrTi) is smaller than the time minimum reference value Ti0, that is, when the free run state ends ( A case where the elapsed time value Ti _ST at the time when the detected torque value reaches the start torque STo is smaller than the minimum time reference value Ti0 is detected as a tightening failure.

Accordingly, the graph shown in FIG. 5 shows that in the initial abnormality detection control in the torque wrench of the present embodiment, the elapsed time value Ti _ST at the time when the free-run state ends is not smaller than the time minimum reference value Ti0. Is an example of a case where the tightening failure is not detected.

  As described above, in the initial abnormality detection control of the torque wrench according to the present embodiment, when the screw is tightened, the detected torque value is determined based on the start torque STo, the minimum angle reference value A0, and the minimum time reference value Ti0. When the detected angle value or the measured time value is smaller than the minimum reference value (minimum angle reference value A0 / minimum time reference value Ti0), the tightening failure is detected.

  In this way, in the free running state of the torque wrench, the initial abnormality before the seating of the screw is detected as a tightening failure by performing the initial abnormality detection control based on the rotation angle value or the elapsed time value. Is possible. That is, when tightening a screw, it is possible to detect an initial abnormality before the seating of the screw, such as double tightening, as a tightening failure. As a result, the tightening accuracy can be improved, and the quality of the screw tightening can be improved.

The partial cross section figure which shows the structure of the tool main body which concerns on one Embodiment of this invention. The control block diagram of the torque wrench which concerns on one Embodiment of this invention. The figure showing the graph which shows the relationship between a rotation angle and fastening torque. The figure showing the graph which shows the relationship between the rotation angle for every kind of fastening failure, and fastening torque. The figure showing the graph which shows the relationship between elapsed time and fastening torque. The figure showing the graph which shows the relationship between elapsed time and a rotation angle. The figure showing the graph which shows the relationship between a rotation angle and fastening torque.

Explanation of symbols

1 Tool body 3 Air motor (rotation drive source)
4 Spindle 10 Torque sensor (Tightening torque detection means)
20 Angle sensor (rotation angle detection means)
50 controller 51 control unit 53 determination unit (determination means)
54 timer (elapsed time measuring means)

Claims (6)

A pulse-type impact tightening tool comprising a rotational drive source and a main shaft to which a pulsed impact torque obtained by converting the rotational torque from the rotational drive source is applied, and tightening a screw by the rotation of the main shaft. And
A tightening torque detecting means for detecting a tightening torque of the screw;
Rotation angle detection means for detecting the rotation angle of the spindle;
Determining means for determining a tightening failure with respect to the tightening of the screw,
The determination means includes
For each of the value of the tightening torque detected by the tightening torque detection means and the value of the rotation angle detected by the rotation angle detection means, based on a predetermined pass range set in advance,
When the value of the rotation angle detected by the rotation angle detection means reaches the upper limit value of the acceptable range, the value of the tightening torque detected by the tightening torque detection means is the lower limit of the acceptable range. A value of the rotation angle detected by the rotation angle detection means when the value is smaller than a value, and when the value of the tightening torque detected by the tightening torque detection means reaches the upper limit value of the acceptable range Is detected as the tightening failure when the value is smaller than the lower limit value of the acceptable range. Equipped with an elapsed time measuring means for measuring an elapsed time from a predetermined reference time in screw tightening,
The determination means includes
About the value of the elapsed time measured by the elapsed time measuring means, based on a predetermined pass range set in advance,
When the value of the elapsed time measured by the elapsed time measuring means reaches the upper limit value of the acceptable range, the value of the tightening torque detected by the tightening torque detecting means or the rotation angle detecting means When the detected value of the rotation angle is smaller than the lower limit value of each acceptable range, and the value of the tightening torque detected by the tightening torque detection means or the rotation angle detection means When the value of the rotation angle reaches the upper limit value of each acceptable range, the elapsed time value measured by the elapsed time measuring means is smaller than the lower limit value of the acceptable range. The pulse-type impact tightening tool according to claim 1, wherein: The determination means includes
Based on an initial reference value for tightening a screw that is preset for the value of the tightening torque, and a minimum reference value that is preset for each of the value of the rotation angle and the value of the elapsed time,
When the value of the tightening torque detected by the tightening torque detecting means reaches the initial reference value, the value of the rotation angle detected by the rotation angle detecting means or the elapsed time measuring means is measured. The pulse-type impact tightening tool according to claim 2, wherein a case where the value of the elapsed time is smaller than each of the minimum reference values is detected as the tightening failure. A rotation driving source, and a main shaft to which a pulsed impact torque converted from the rotational torque from the rotation driving source is applied, and tightening in a pulse-type impact tightening tool for tightening a screw by rotation of the main shaft. A defective detection method,
Detecting the tightening torque of the screw and the rotation angle of the spindle;
Based on a predetermined pass range set in advance for each of the detected tightening torque value and the rotation angle value,
When the detected value of the rotation angle reaches the upper limit value of the acceptable range, the detected value of the tightening torque is smaller than the lower limit value of the acceptable range, and the detected value of the tightening torque When the upper limit value of the acceptable range is reached, the detected rotation angle value is smaller than the lower limit value of the acceptable range, and is detected as a tightening failure. Tightening failure detection method for tools. Measure the elapsed time from the predetermined reference time in screw tightening,
About the value of the elapsed time to be measured, based on a predetermined pass range set in advance,
When the measured elapsed time value reaches the upper limit value of the acceptable range, the detected tightening torque value or the detected rotation angle value is smaller than the lower limit value of the respective acceptable range, And when the detected value of the tightening torque or the detected value of the rotation angle reaches the upper limit value of the respective acceptable range, the measured elapsed time value is smaller than the lower limit value of the acceptable range. Is detected as a tightening failure. 5. The method of detecting a tightening failure in a pulse-type impact tightening tool according to claim 4. Based on the initial reference value in the tightening of the screw set in advance for the value of the tightening torque, and the minimum reference value set in advance for each of the value of the rotation angle and the value of the elapsed time,
When the detected value of the tightening torque reaches the initial reference value, the detected rotation angle value or the measured elapsed time value is smaller than the minimum reference value. 6. The method for detecting a fastening failure in a pulse-type impact fastening tool according to claim 5, wherein the detection is performed.

Images