JP4669663B2 - Torque management system using an electric screwdriver having a torque detection function and an electric screwdriver having a torque detection function - Google Patents

Description

  The present invention relates to an electric screwdriver having a torque detection function, and a torque detection function capable of performing a screw tightening operation safely and reliably and smoothly with an appropriate screw tightening torque on an object to be mounted such as a screw at all times. The present invention relates to a torque management system in the case of using an electric screwdriver equipped with an electric screwdriver and an electric screwdriver equipped with a torque detection function.

  Conventionally, the present applicant, as an electric screwdriver having a torque detection function, for example, in screw tightening work, continuously measures fluctuations in torque value from the start of screw tightening to the completion of tightening. An electric screwdriver equipped with a torque detector set so as to be able to be used has been proposed (see Patent Document 1). That is, the electric driver described in Patent Document 1 includes (1) a pinion gear connected to a rotational drive source, a planetary gear meshing with the pinion gear, and an internal gear meshing internally with the planetary gear. A planetary speed reduction mechanism, and (2) a cylindrical casing that houses the planetary speed reduction mechanism, and (3) the internal gear is rotatably fitted in the cylindrical casing, and the outer periphery of the internal gear is A torsion bar extending radially outward is fixed through a slit formed in the cylindrical casing, and (4) a support extending radially in parallel to the torsion bar is attached to the cylindrical casing. (5) A stopper that restricts rotation of the internal gear in the vicinity of the free end of the torsion bar is attached to the support, and the torsion bar Those having the structure obtained by arranging the strain gauge to the appropriate position. Therefore, in the electric screwdriver configured as described above, the fluctuation of the torque value from the start of the tightening of the screw to the completion of the tightening can be measured by detecting the stress strain transmitted to the torsion bar. It is configured to be able to.

  Also, in the past, when tightening a screw or the like, when a strong counter load is applied to the driver bit, the clutch mechanism that operates with a preset tightening torque value detects the state that has reached a predetermined torque value. The clutch mechanism is operated to temporarily disconnect the coupling between the output shaft of the electric motor and the driven shaft on the driver bit side, and when the clutch mechanism is operated, this is detected by a limit switch or the like. Thus, an electric screwdriver configured to stop driving the electric motor has been proposed and put into practical use.

  From this point of view, the applicant first detects when a predetermined load torque is received between the output shaft and the driven shaft of the electric motor and transmits the rotational driving force of the output shaft. An electric rotary tool having a torque detection and automatic stop mechanism has been proposed (see Patent Document 2), which has a clutch mechanism for interrupting the motor and a mechanism for simultaneously detecting the torque value at that time and automatically stopping the electric motor. ). That is, the electric rotary tool described in Patent Document 2 is provided with (1) a gripping portion with a built-in electric motor, and a driven shaft is coupled to the output shaft of the electric motor via a planetary speed reducing mechanism. An internal gear that meshes with the planetary gear of the planetary reduction mechanism is rotatably disposed in a cylindrical casing that surrounds the clutch, and a clutch mechanism that uses a steel ball is provided between the internal gear and the grip casing. In the electric rotary tool provided with a torque detection mechanism provided with means for detecting the operation of the clutch mechanism, (2) the internal gear of the clutch mechanism provided between the internal gear of the planetary reduction mechanism and the grip casing. A notch that opens a part of the swing detection piece is provided, and one end of the swing detection piece is disposed in this notch with the steel ball of the clutch mechanism, and the other end of the swing detection piece is gripped. It is configured to be fixed to a part of the casing and receive a stress displacement during the clutch operation, and (3) a strain gauge is stretched on the displacement portion of the swing detection piece, and (3a) the strain gauge is further detected. A torque detection circuit that detects a torque value based on the signal and (3b) an automatic stop circuit that stops driving the electric motor based on the detected torque value are provided. Therefore, the electric rotary tool configured as described above can accurately detect the opposite load torque from the driven shaft side due to the clutch operation of the clutch mechanism by the strain gauge, and the torque detected by the strain gauge. Based on the value, if the torque value is appropriate, the drive of the electric motor can be temporarily automatically stopped, and if the torque value detected by the strain gauge is inappropriate, an alarm is generated. It can be set to.

  On the other hand, conventionally, an electric driver that performs automatic torque control by electrically stopping the driving of the electric driver has been proposed and implemented. As an electric driver of this type, the applicant of the present invention has an electric motor with a built-in electric motor and a driver shaft driven by the rotation of the electric motor. An overload current detection circuit that detects this state change when the load current flowing through the line changes to an overload current of a predetermined value or more due to an external load applied to the driver shaft, and (2) operation of the detection circuit. In response to the above, a configuration is proposed in which an automatic stop device combined with a switching circuit that cuts off the energization of the electric motor drive power supply line and returns the energization after a lapse of a certain time has been proposed (Patent Document) 3).

  Furthermore, the present applicant has proposed a screw tightening device including an automatic stop device that is a combination of a power supply device capable of performing torque control by electrically automatically stopping the driving of the electric screw driver and an electric screw driver. (See Patent Document 4). That is, the screw tightening device described in Patent Document 4 includes: (1) a transformer and a rectifying device are provided to supply a DC voltage, and a constant voltage circuit that can be variably adjusted is connected to the output side of the rectifying device; (2) Connect a load resistor to the DC voltage output line, compare the potential difference caused by the motor load current flowing through this load resistor with the predetermined constant voltage set by the constant voltage circuit, and flow through the load resistor When the load current changes to an overload current greater than or equal to a predetermined value and flows continuously for a certain period of time, the capacitor is charged with this overload current, and the relay is activated when the capacitor charging voltage reaches the predetermined value. (3) and a switching circuit that keeps the operation of the relay within the discharge time of the capacitor is provided. Those configured to connect to a power source of an electric screwdriver with a driver shaft for driving more rotation. Therefore, in the screw tightening device configured as described above, the potential difference caused by the load current of the motor flowing through the load resistance is proportional to the screw tightening torque value of the electric driver, and variable adjustment for comparison with this potential difference By adjusting the set voltage of a possible constant voltage circuit, torque control that can achieve screw tightening at a required torque value can be realized.

JP-A-56-94233 JP-A-6-254775 Japanese Utility Model Publication No. 53-47677 Japanese Examined Patent Publication No. 53-15240

  In the above-described conventional electric screwdriver having a torque detection function, it is possible to detect a screw tightening torque value when screw tightening is completed in a required screw tightening operation. Therefore, for example, in an electric driver equipped with a clutch mechanism, if the clutch mechanism is set to operate in advance corresponding to a predetermined torque value by a torque setting device, the electric driver is always set to a set torque value. The screw tightening work can be achieved. In addition, in an electric driver configured to perform torque control by detecting a load current of the electric motor, a setting voltage for comparison with a potential difference caused by the load current is set to a voltage value proportional to a predetermined torque value. Thus, in the same manner as described above, the screw tightening operation by the electric screwdriver can be achieved so that the torque value is always set.

  However, when the required screw tightening operation is performed using the electric screwdriver in which the screw tightening torque value is set as described above, the predetermined screw tightening cannot always be reliably completed. Appropriate screw tightening may not be completed due to unforeseen circumstances such as changes in the state of the screw, cam-out from the screw fitting groove of the driver bit, deformation or breakage due to the material of the screw mounting target. In such a case, the torque value at the time of operation of the clutch mechanism and the torque value corresponding to the load current of the electric motor each show an abnormal value. By setting this to detect this state and generate an alarm, etc. An electric screwdriver configured to notify an operator of an abnormal state during screw tightening has also been put into practical use.

  However, in the electric driver configured as described above, it is necessary to determine an allowable value for the set torque value of the electric driver in order to determine an abnormal state during screw tightening. Therefore, for example, as the allowable value, it is common to simply set the upper limit value and the lower limit value for the set torque value as ± 10 to 30%. However, in the case of an electric screwdriver, depending on the material of the screw mounting object, the shape, size, type, etc. of the screw, the abnormal torque value when an abnormal condition occurs depends on the set characteristics of the electric screwdriver. It was confirmed that there was a tendency to be above or below the value. Therefore, in the electric driver with the alarm function as described above, when the upper limit value and the lower limit value are simply set as ± 10 to 30% as the allowable value as the allowable range for the set torque value of the electric driver, If the allowable value range is small, an alarm is activated unnecessarily, and if the allowable value range is large, an alarm is not activated when an alarm is required. There was a problem that it was difficult to set.

  Therefore, as a result of intensive research and trial production to solve the above problems, the present inventor has provided a gripping portion incorporating an electric motor, and the output shaft of the electric motor is driven by a reduction mechanism comprising a planetary gear. In an electric screwdriver in which a shaft is coupled and a clutch mechanism is provided between a support member that supports a part of the driven shaft, one end of a torsion bar is coupled to a part of the speed reduction mechanism, and the other end is It leads out to the outside from the opening, extends parallel to the gripping part, and is fixedly placed on the gripping part. A strain gauge is stretched on the stress displacement part of the torsion bar, and the torque value is based on the detection signal of the strain gauge. And a torque detection function capable of detecting and measuring an appropriate screw tightening torque value at the time of clutch operation of the clutch mechanism. I have found that it is possible to obtain a dynamic driver. Therefore, by using the electric screwdriver having such a configuration, it is possible to appropriately detect and measure the screw tightening torque value in consideration of the characteristics specific to the electric screwdriver, and to set the screw tightening torque value and its upper limit value. It was found that the allowable value consisting of the lower limit value can be set easily and appropriately.

  That is, when setting the screw tightening torque value in the electric screwdriver and setting the allowable value consisting of the upper limit value and the lower limit value, the torque is set so that the clutch mechanism is operated in advance with a predetermined screw tightening torque value. Raw data on the screw tightening torque value of an electric screwdriver is repeatedly performed a plurality of times (for example, about 10 times) by using an electric screwdriver for which a value has been set, and repeatedly performing screw attachment trials on a required screw mounting object. Can be obtained. Therefore, when the screw tightening of each screw is completed, the torque value detected by the strain gauge provided in the electric screwdriver is stored and held, and the detected torque value as the stored raw data is set as the set torque value. Each is compared and the maximum torque value and the minimum torque value are extracted. Then, values corresponding to about 5 to 10% with respect to the deviation between the extracted maximum torque value and minimum torque value and the set torque value are calculated, and these calculated values are used as the maximum torque value and the minimum torque value. In addition to the above, an upper limit value and a lower limit value are calculated, and these upper limit value and lower limit value are set as allowable values that are within an allowable range of the set torque value of the electric driver. By setting in this way, the minimum necessary for the set torque of the electric screwdriver in screw tightening work that is expected to cause abnormal conditions depending on the material of the screw mounting object, the shape, dimensions, type, etc. of the screw It has been found that the allowable range of the appropriate allowable value can be set easily and easily, and that an erroneous determination of an abnormal state can be prevented during the screw tightening operation, so that proper torque management can always be achieved. Such torque management can also be applied to an air driver provided with a clutch mechanism.

  Further, the load current of the electric motor is detected, the potential difference caused by the load current is compared with a predetermined set voltage, the load current changes to an overload current greater than a predetermined value, and the potential difference exceeds the set voltage. In the electric driver configured to cut off the drive power line of the electric motor when the overload current continuously flows for a certain time, the set voltage is set to a voltage value corresponding to the screw tightening torque value of the electric driver. Setting and detecting the potential difference caused by the load current of the electric motor as the screw tightening torque value, and appropriately detecting and measuring the screw tightening torque value with the characteristics specific to the electric screwdriver taken into account as described above It has been found that an electric screwdriver with a torque detection function can be obtained.

  In the electric driver having the torque detection function configured as described above, the maximum torque value and the minimum torque value are extracted from the detected torque value as raw data for the set torque value in the same manner as described above. A value corresponding to about 5 to 10% with respect to a deviation between the maximum torque value and the minimum torque value and the set torque value is calculated, and these calculated values are added to the maximum torque value and the minimum torque value, respectively. It is also possible to calculate the upper limit value and the lower limit value and set these upper limit value and lower limit value as allowable values that are within the allowable range of the set torque value of the electric driver. Even in this case, it is possible to easily and easily set an allowable range of the minimum appropriate allowable value for the set torque of the electric screwdriver in the same manner as described above, and prevent erroneous determination of an abnormal state during screw tightening work. It has been found that proper torque management suitable for an electric screwdriver that is always used can be achieved.

  Accordingly, an object of the present invention is to appropriately detect and measure the screw tightening torque value in an electric screwdriver having a torque detection function, and to determine the material of the screw mounting object, the shape, size, type, etc. of the screw. Therefore, it is possible to easily and easily set the allowable range of the appropriate minimum value for the set torque of the electric screwdriver when tightening the screw that is expected to cause an abnormal condition. Provide a torque management system that uses an electric screwdriver with a torque detection function and an electric screwdriver with a torque detection function, which can prevent erroneous determination of an abnormal state and achieve proper torque management suitable for the electric screwdriver that is always used There is.

In order to achieve the above object, an electric screwdriver having a torque detection function according to claim 1 of the present invention is provided with a gripping part incorporating an electric motor, and a reduction mechanism comprising a planetary gear is provided on the output shaft of the electric motor. An internal gear that meshes with the planetary gear of the speed reduction mechanism is rotatably disposed in a cylindrical casing that surrounds the speed reduction mechanism by coupling a driven shaft that rotationally drives the driver bit. In the electric driver provided with a clutch mechanism using a steel ball between the clutch surface formed on the bottom surface portion and the circular bottom surface portion of the gripping portion side cylindrical casing facing the clutch surface ,
One end of the torsion bar is coupled to a part of the outer periphery of the internal gear of the speed reduction mechanism, and the other end is led out to the outside of the gripping part through an opening provided in the gripping part side cylindrical casing, and outside the gripping part. And extending in parallel to the axial direction and fixedly arranged on the gripping portion, and a strain gauge is stretched on the stress displacement portion of the torsion bar, and a torque value is detected based on a detection signal of the strain gauge. The screw tightening torque value detecting means is provided.

According to a second aspect of the present invention, there is provided a torque management system using an electric screwdriver having a torque detection function, wherein a grip portion having a built-in electric motor is provided, and an output shaft of the electric motor is provided with a speed reduction mechanism including a planetary gear. A driven shaft that rotationally drives the driver bit is coupled, and an internal gear that meshes with the planetary gear of the speed reduction mechanism is rotatably disposed in a cylindrical casing that surrounds the speed reduction mechanism, and a closed bottom surface portion of the internal gear A clutch mechanism using a steel ball is provided between the clutch surface formed on the cylindrical surface and the circular bottom surface of the gripping portion side cylindrical casing, and a torsion bar is provided on a part of the outer periphery of the internal gear of the reduction mechanism. Connect one end and lead the other end to the outside of the gripping part through an opening provided in the cylindrical casing on the gripping part. Screw tightening configured to extend parallel to the gripping part and to be fixed to the gripping part, to stretch a strain gauge on the stress displacement part of the torsion bar, and to detect the torque value based on the detection signal of the strain gauge Use an electric screwdriver with a torque detection function provided with torque value detection means,
A screw tightening torque value storage means for storing and holding the screw tightening torque value of the electric screwdriver at the time of completion of screw tightening of each screw by repeatedly performing screw mounting on the required screw mounting target object by the electric screw driver a plurality of times. When,
The maximum torque value and the minimum torque value are extracted from a plurality of screw tightening torque values stored and held in the screw tightening torque value storage means, and the deviation between the maximum torque value and the minimum torque value and the set torque value is obtained. a value corresponding to 5-10% for, provided the permissible value calculating means for calculating the respective upper and lower limit values in addition to the maximum torque value and the minimum torque value,
The upper limit value and the lower limit value calculated by the allowable value calculating means are set as the allowable values for the set torque value of the electric driver for the screw tightening torque value detecting means of the electric driver.

According to a third aspect of the present invention, there is provided a torque management system that uses an electric screwdriver having a torque detection function. The electric motor includes a built-in electric motor, and a driven shaft that rotationally drives a driver bit is coupled to the output shaft of the electric motor. A load resistor that detects the load current of the electric motor and a constant voltage circuit that can be variably adjusted are connected to the drive power line of the motor, and a potential difference generated by the load current flowing through the load resistor is set by the constant voltage circuit. When the load current changes to an overload current equal to or greater than a predetermined value and the potential difference exceeds a set constant voltage and the overload current continuously flows for a certain period of time, the drive power line of the electric motor The constant voltage set by the constant voltage circuit is set to a voltage value corresponding to the screw tightening torque value of the electric screwdriver, The potential difference caused by the load current flowing in the load resistor for detecting a load current of the dynamic motor using an electric screwdriver with a torque detecting function provided with a screw tightening torque value detection means configured to detect a screw tightening torque value,
A screw tightening torque value storage means for storing and holding the screw tightening torque value of the electric screwdriver at the time of completion of screw tightening of each screw by repeatedly performing screw mounting on the required screw mounting target object by the electric screw driver a plurality of times. When,
The maximum torque value and the minimum torque value are extracted from a plurality of screw tightening torque values stored and held in the screw tightening torque value storage means, and the deviation between the maximum torque value and the minimum torque value and the set torque value is obtained. And an allowable value calculation means for calculating an upper limit value and a lower limit value, respectively, by adding a value corresponding to 5 to 10% to the maximum torque value and the minimum torque value,
The upper limit value and the lower limit value calculated by the allowable value calculating means are set as the allowable values for the set torque value of the electric driver for the screw tightening torque value detecting means of the electric driver.

According to an electric screwdriver having a torque detection function according to the first aspect of the present invention, a grip portion having a built-in electric motor is provided, and a driver bit is rotated through a speed reduction mechanism comprising a planetary gear on the output shaft of the electric motor. A clutch formed on a closed bottom surface portion of the internal gear , in which a driven shaft to be driven is coupled, an internal gear meshing with the planetary gear of the speed reduction mechanism is rotatably disposed in a cylindrical casing surrounding the speed reduction mechanism the electric screwdriver having a clutch mechanism using a steel ball between the surface and the circular bottom portion of the grip portion side cylindrical casing opposite thereto, the screw tightening torque at the same time the screw tightening completion and clutching of the clutch mechanism The value can be detected and measured with the characteristics unique to the electric screwdriver in mind, and the screw tightening screw conforming to the characteristics specific to the electric screwdriver It can be carried out setting the click value and the setting of the tolerance consisting of the upper limit value and the lower limit value easily and properly.

According to the torque management system using the electric screwdriver or the like having the torque detection function according to the second aspect of the present invention, the clutch mechanism that performs the clutch operation with a preset screw tightening torque value, and the electric driver when the screw tightening is completed When using an electric screwdriver with a torque detection function provided with a screw tightening torque value detecting means for detecting the screw tightening torque value of the screw, depending on the material of the screw mounting object, the shape, size, type, etc. of the screw At the time of screw tightening work that is expected to cause an abnormal condition, set the allowable range of the appropriate minimum allowable value for the set torque of the electric screwdriver, and try to install the screw on the required screw mounting object. Repeated multiple times to store and store the raw data of the screw tightening torque value at that time. By calculating based on the data, it is possible to easily and easily set the allowable value suitable for the characteristics specific to the electric screwdriver, and to prevent erroneous determination of an abnormal state during the screw tightening operation. Appropriate torque management suitable for the driver can be achieved.

According to the electric driver having the torque detection function used in the torque management system according to the third aspect of the present invention, the load current of the electric motor is detected, and the potential difference caused by the load current is detected as the screw tightening torque value. At the same time, in the electric screwdriver configured to perform torque control so that the screw tightening torque value set in advance when the screw tightening of the electric screwdriver is completed, the screw tightening torque value is detected and measured in consideration of the characteristics specific to the electric screwdriver. It is possible to set the screw tightening torque value and the allowable value including the upper limit value and the lower limit value easily and appropriately.

According to the torque management system using the electric screwdriver having the torque detection function according to claim 3 of the present invention, the load current of the electric motor is detected, and the potential difference caused by the load current is used as the screw tightening torque value. In the case of using an electric screwdriver configured to detect and control the torque so that the screw tightening torque value set in advance when screw tightening of the electric screwdriver is completed, the material of the screw mounting object and the shape of the screw As with the above torque management system, setting the allowable range of the appropriate minimum allowable value for the set torque of the electric screwdriver when tightening the screw that is expected to cause an abnormal condition depending on the size, type, etc. In addition, it can be easily and easily adapted to the characteristics unique to the electric screwdriver and screw tightening Preventing erroneous determination of the abnormal state during work, it is possible to always achieve proper torque management conforming to the electric driver used.

  Next, embodiments of an electric screwdriver having a torque detection function and a torque management system using the electric screwdriver according to the present invention will be described in detail with reference to the accompanying drawings.

( Configuration of electric screwdriver with torque detection function )
FIG. 1 shows an embodiment of an electric screwdriver having a torque detection function according to the present invention. That is, in FIG. 1, reference numeral 10 indicates a grip portion of an electric screwdriver having a built-in electric motor (not shown), and a driver bit (not shown) can be appropriately connected to the tip portion of the grip portion 10. A clutch mechanism 12 is provided.

However, the tip of the output shaft 14 of the electric motor is connected and fixed to a pinion gear 16, and a reduction mechanism 20 including a planetary gear 18 is meshed and connected via the pinion gear 16. An internal gear 22 that meshes with the planetary gear 18 is disposed on the outer periphery of the speed reduction mechanism 20. The internal gear 22 is housed and disposed rotatably in the gripper side cylindrical casing 24. One or a plurality of long grooves 23 are formed radially from the axial center of the closed bottom surface portion 22a of the internal gear 22, and a roller 28 is fitted into the long groove 23 so as to be able to roll. At this time, the roller 28 is set so that its rolling surface half projects outward from the long groove 23, and the closed bottom surface portion 22a is configured as a clutch surface. A driven shaft 30 that is coaxially connected to the output shaft 14 and coupled to the driver bit passes through the central portion of the clutch surface , which is the closed bottom surface portion 22a of the internal gear 22, and has an internal gear at one end thereof. A disk-like support portion 31 is provided which supports the planetary gear 18 meshing with the rotor 22 and performs reduced-speed rotation driving.

Wherein the circular bottom portion 24a of the grip portion side cylindrical casing 24 the clutch surfaces are closed bottom portion 22a of the internal gear 22 is opposed, the flesh thereof in part provided a hole 26 to the hole 26 A steel ball 32 having a diameter larger than the thickness is disposed. Further, in order to prevent the steel ball 32 from falling off the circular bottom surface portion 24a and to force the steel ball 32 against the clutch surface of the closed bottom surface portion 22a , the grip portion side cylindrical casing boss 25 A flanged sleeve 34 is arranged on the outer periphery, and the steel ball 32 is held by the flange portion 35. Further, one end of a coil spring 36 is locked to the flanged sleeve 34 , and the other end of the coil spring 36 is screwed into a front end portion of a sleeve cover 38 surrounding the flanged sleeve 34. and held by the torque adjustment cap 40, the elastic force of the coil spring 36, said flanged sleeve 34 is pressed against the action with respect to the steel ball 32 may set the setting namely the clutch operating point of the screw tightening torque to be described later Configured as follows.

However, in the electric driver of the present embodiment, an opening 42 is provided in a part of the gripping portion side cylindrical casing 24 corresponding to the speed reduction mechanism 20, and one end of the torsion bar 44 is inserted into the opening 42 in the gap. Then, this is coupled and fixed to a part of the internal gear 22, and the other end is extended in parallel to the axial direction on the outside of the grip portion 10 and fixedly disposed on the grip portion 10. Then, against the stress displacement portion of the torsion bar 44, which stretched the strain gauge 46 as the screw tightening torque detection unit. Therefore, based on the detection signal of the strain gauge 46, in the screw tightening operation by the electric screwdriver, it is possible to properly detect the torque value when the screw tightening is completed when the clutch mechanism 12 is operated.

  In FIG. 1, reference numeral 48 indicates a limit switch disposed in proximity to the flanged sleeve 34. The limit switch 48 is set so as to perform a switch operation in accordance with the clutch operation of the clutch mechanism 12, and to cut off the drive power supply line of the electric motor to perform drive stop control of the electric motor. As an alternative, the clutch operation of the clutch mechanism 12 is detected by detecting a state in which the cam engagement of the clutch mechanism is completely released by a combination of a magnet and a magnetic sensor, and performs drive stop control of the electric motor. The set torque control method according to the proposal of the applicant of the present application can also be adopted (see Japanese Patent Application Laid-Open No. 2002-321166).

( Torque management system with electric screwdriver with torque detection function )
Next, a torque management system in the case of using an electric screwdriver having a torque detection function having the above configuration will be described.
FIG. 2 is an explanatory diagram showing a schematic system configuration of the torque management system according to the present invention. 2, reference numeral 50 is an electric driver having a torque detection function, 52 is a torque setting device for setting a screw tightening torque of the electric driver 50, that is, a clutch operating point, and 54 is a clutch of the electric driver 50. A torque detector that detects a screw tightening torque value during operation, 56 is a power supply device for an electric screwdriver, and 58 is an object to be screwed.

  Therefore, regarding the torque management process in the torque management system configured as described above, a system configuration for performing arithmetic processing using the CPU 60 shown in FIG. 3, and a flowchart of an operation program for executing the torque management process shown in FIG. The description will be made with reference to the allowable value setting process explanatory diagram shown in FIG.

  First, the required screw tightening torque, that is, the operating point of the clutch mechanism 12 (see FIG. 1) is set for the electric driver 50 having a torque detection function using the torque setting device 52 (STEP-1). Using the electric screwdriver 50 in which the operating point of the clutch mechanism 12 is set in this manner, the screw attachment to the screw attachment object 58 is repeatedly performed a plurality of times (for example, about 10 times) (STEP-2). In this way, when a plurality of screw attachment attempts are made, the screw tightening torque value detected by the screw tightening torque value detecting means 51 is stored and held (STEP-3). Accordingly, as shown in FIG. 3, the torque detector 54 is provided with screw tightening torque value storage means 55A for storing and holding the screw tightening torque value detected by the screw tightening torque value detecting means 51. The data stored and held in the screw tightening torque value storage means 55A in this way is represented as a broken line graph as shown in FIG. 5, for example.

  Thereafter, the maximum torque value Tmax and the minimum torque value Tmin are extracted from the plurality of screw tightening torque values stored and held in the screw tightening torque value storage means 55A (STEP-4). Next, deviations [Tmax−TB = + α and Tmin−TB = − from the set torque value TB set in the electric driver 50 with respect to the maximum torque value Tmax and the minimum torque value Tmin (indicated by a one-dot chain line in FIG. 5). β] respectively, and values [+ α × (5 to 10%) and −β × (5 to 10%)] corresponding to about ± 5 to 10% with respect to the deviation [+ α and −β]. Calculate (STEP-5). Then, this calculated value is added to the maximum torque value Tmax [= TB + α] and the minimum torque value Tmin [= TB−β], respectively, and an upper limit value Tmax ′ [= TB + α + α × (5 to 10%)] and The lower limit value Tmin ′ [= TB−β−β × (5 to 10%)] is calculated (STEP-6). Accordingly, as shown in FIG. 3, the torque detector 54 performs operations from the extraction of the maximum torque value Tmax and the minimum torque value Tmin to the calculation of the upper limit value Tmax ′ and the lower limit value Tmin ′. The permissible value calculating means 55B is provided. The upper limit value Tmax 'and the lower limit value Tmin' for the set torque value TB of the electric driver 50 calculated by the allowable value calculation means 55B in this way are expressed as an allowable line by a solid line as shown in FIG. 5, for example. The

  In this manner, the upper limit value Tmax is set as an allowable range for the screw tightening torque value detected by the screw tightening torque value detecting means 51 with respect to the screw tightening torque setting value TB set for the electric screwdriver 50 having the torque detecting function. By setting 'and the lower limit value Tmin', the torque value can be displayed on the torque value display means 55C provided in the torque detector 54, and the malfunction of the alarm generation means 55D due to an erroneous determination of an abnormal state during the screw tightening operation. Can always be achieved and proper torque management can be achieved (see FIG. 3).

  The torque management system described above is not limited to an electric screwdriver having a torque detection function having the configuration shown in the first embodiment, and includes a clutch mechanism that performs a clutch operation with a preset screw tightening torque value, and a screw tightening The present invention can also be applied in a wide range to an electric driver having a torque detection function including a screw tightening torque value detecting means for detecting the screw tightening torque value of the electric driver at the time of completion.

( Configuration example of electric screwdriver with torque detection function )
As another embodiment of the electric driver having the torque detection function of the present invention, an electric motor is built in, a driven shaft for rotating a driver bit is coupled to the output shaft of the electric motor, and an electric power is supplied to the drive power line of the electric motor. A load resistor that detects a load current of the motor and a constant voltage circuit that can be variably adjusted are connected, a potential difference caused by a load current flowing through the load resistor is compared with a predetermined constant voltage set by the constant voltage circuit, and the load The present invention can be applied to an electric driver configured to operate a relay to cut off a drive power supply line of an electric motor when the current changes to an overload current of a predetermined value or more and continuously flows for a predetermined time.
In this case, the constant voltage set by the constant voltage circuit is set to a voltage value corresponding to the screw tightening torque value of the electric screwdriver, and the potential difference caused by the load current flowing through the load resistor for detecting the load current of the electric motor is screwed. The screw tightening torque value detecting means configured to detect the tightening torque value is provided. Even in the electric screwdriver having the torque detection function of the present embodiment configured as described above, in the screw tightening operation, it is possible to appropriately detect the torque value when the screw tightening is completed when the relay is operated.

( Torque management system with electric screwdriver with torque detection function )
Therefore, the torque management system in the case where the electric screwdriver having the torque detection function configured as described above is used can be realized in the same manner as in the first embodiment.
In this embodiment, when the required screw tightening torque is set using the torque setting device 52, the constant voltage set by the constant voltage circuit is set to a value corresponding to the set value of the screw tightening torque. The torque value detected as the screw tightening torque of the electric driver is different only in that it is a value corresponding to a potential difference caused by a load current flowing through the load resistance of the electric motor. Other system configurations relating to the torque management system can be applied in the same manner as in the first embodiment, and the same operations and effects can be obtained.

  The torque management system described above is not limited to the electric driver having the torque detection function having the configuration shown in the second embodiment, but detects the load current of the electric motor and tightens the potential difference caused by the load current by screwing. Torque detection configured to stop the driving of the electric motor when the load current becomes equal to or higher than a preset voltage value corresponding to a preset screw tightening torque value provided with a screw tightening torque value detecting means for detecting as a torque value It can also be applied to a wide range of electric drivers with functions.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments. For example, the upper limit value Tmax ′ and the lower limit value Tmin ′ as an allowable range of the set torque value TB are set. About ± 5 to 10% is used as a suitable calculation value for the deviations + α and −β between the maximum torque value Tmax and the minimum torque value Tmin and the set torque value TB when calculating, but is limited to this calculation value. For example, an electric driver having a torque detection function can be suitably applied to an air driver provided with a clutch mechanism. However, many other design changes can be made without departing from the spirit of the present invention.

It is a principal part sectional side view showing one example of an electric screwdriver provided with a torque detection mechanism concerning the present invention. It is explanatory drawing which shows the schematic system configuration | structure of the torque management system which uses an electric screwdriver provided with the torque detection mechanism which concerns on this invention. It is a system block diagram which performs the arithmetic processing by CPU of the torque management system which uses an electric screwdriver provided with the torque detection mechanism which concerns on this invention. It is a flowchart figure of the operation | movement program for performing the torque management process in the torque management system which uses an electric screwdriver provided with the torque detection mechanism which concerns on this invention. It is explanatory drawing which shows the setting process of the screw tightening torque value of an electric screwdriver in the torque management system which uses an electric screwdriver provided with the torque detection mechanism which concerns on this invention, and its allowable value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Holding part 12 Clutch mechanism 14 Output shaft 16 Pinion gear 18 Planetary gear 20 Deceleration mechanism 22 Internal gear 22a Closed bottom face part 23 Long groove 24 Holding part side cylindrical casing 24a Circular bottom face part 25 Boss part 26 Hole part 28 Roller 30 Driven shaft 31 Disc-shaped support part 32 Steel ball 34 Sleeve 34 with flange
35 Flange portion 36 Coil spring 38 Sleeve cover 40 Torque adjustment cap 42 Opening portion 44 Torsion bar 46 Strain gauge 48 Limit switch 50 Electric screwdriver 51 having torque detection function Screw tightening torque value detecting means 52 Torque setting device 54 Torque detector 55A Screw Tightening torque value storage means 55B Allowable value calculation means 55C Screw tightening torque value display means 55D Alarm generation means 56 Power supply device 58 for electric screwdriver Screw attachment object 60 CPU

Claims (3)

A gripping portion incorporating an electric motor is provided, and a driven shaft for rotationally driving a driver bit is coupled to the output shaft of the electric motor via a speed reduction mechanism including a planetary gear, and the cylindrical casing surrounding the speed reduction mechanism is An internal gear that meshes with the planetary gear of the speed reduction mechanism is rotatably arranged, and between the clutch surface formed on the closed bottom surface portion of the internal gear and the circular bottom surface portion of the gripping portion side cylindrical casing facing the clutch surface. In an electric driver with a clutch mechanism using steel balls ,
One end of the torsion bar is coupled to a part of the outer periphery of the internal gear of the speed reduction mechanism, and the other end is led out to the outside of the gripping part through an opening provided in the gripping part side cylindrical casing, and outside the gripping part. And extending in parallel to the axial direction and fixedly arranged on the gripping portion, and a strain gauge is stretched on the stress displacement portion of the torsion bar, and a torque value is detected based on a detection signal of the strain gauge. An electric screwdriver having a torque detecting function, characterized in that the screw tightening torque value detecting means is provided. A gripping portion incorporating an electric motor is provided, and a driven shaft for rotationally driving a driver bit is coupled to the output shaft of the electric motor via a speed reduction mechanism including a planetary gear, and the cylindrical casing surrounding the speed reduction mechanism is An internal gear that meshes with the planetary gear of the speed reduction mechanism is rotatably disposed, and between the clutch surface formed on the closed bottom surface portion of the internal gear and the circular bottom surface portion of the gripping portion side cylindrical casing facing the clutch surface. A clutch mechanism using a steel ball is provided, one end of the torsion bar is coupled to a part of the outer periphery of the internal gear of the speed reduction mechanism, and the other end is connected to the grip part via an opening provided in the cylindrical casing of the grip part. In addition to extending to the outside, it extends parallel to the axial direction outside the gripping part and is fixedly placed on the gripping part, and a strain gauge is stretched on the stress displacement part of the torsion bar. Use a power screwdriver with a torque detecting function provided with a screw tightening torque value detecting means arranged to detect the torque value based on the detection signal of the strain gage,
A screw tightening torque value storage means for storing and holding the screw tightening torque value of the electric screwdriver at the time of completion of screw tightening of each screw by repeatedly performing screw mounting on the required screw mounting target object by the electric screw driver a plurality of times. When,
The maximum torque value and the minimum torque value are extracted from a plurality of screw tightening torque values stored and held in the screw tightening torque value storage means, and the deviation between the maximum torque value and the minimum torque value and the set torque value is obtained. And an allowable value calculation means for calculating an upper limit value and a lower limit value, respectively, by adding a value corresponding to 5 to 10% to the maximum torque value and the minimum torque value,
An upper limit value and a lower limit value calculated by the allowable value calculation means are set for the screw tightening torque value detection means of the electric driver as allowable values for the set torque value of the electric driver. Torque management system using an electric screwdriver. A constant voltage circuit with a built-in electric motor, a driven shaft that rotationally drives a driver bit to the output shaft of this electric motor, and a load resistance that detects the load current of the electric motor in the drive power line of the electric motor. Are connected to each other, the potential difference caused by the load current flowing through the load resistor is compared with a predetermined constant voltage set by the constant voltage circuit, and the load current is changed to an overload current greater than a predetermined value to set the potential difference. When a constant voltage is exceeded and the overload current continues to flow for a certain period of time, the drive power line of the electric motor is cut off, and the constant voltage set by the constant voltage circuit is set to the screw tightening torque of the electric driver. The voltage difference corresponding to the value is set, and the potential difference caused by the load current flowing through the load resistance that detects the load current of the electric motor is set to the screw tightening torque value. Use a power screwdriver with a torque detecting function provided with a screw tightening torque value detection means configured to detect and,
A screw tightening torque value storage means for storing and holding the screw tightening torque value of the electric screwdriver at the time of completion of screw tightening of each screw by repeatedly performing screw mounting on the required screw mounting target object by the electric screw driver a plurality of times. When,
The maximum torque value and the minimum torque value are extracted from a plurality of screw tightening torque values stored and held in the screw tightening torque value storage means, and the deviation between the maximum torque value and the minimum torque value and the set torque value is obtained. And an allowable value calculation means for calculating an upper limit value and a lower limit value, respectively, by adding a value corresponding to 5 to 10% to the maximum torque value and the minimum torque value,
An upper limit value and a lower limit value calculated by the allowable value calculation means are set for the screw tightening torque value detection means of the electric driver as allowable values for the set torque value of the electric driver. Torque management system using an electric screwdriver.

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