Method and system for determining screw tightened state of electric rotating tool

Abstract

A method and a system for determining a screw tightening state of an electric rotating tool are provided, in which when screws having different screw shaft dimensions are applied to a plurality of screw tightening positions common to a plurality of workpieces in the electric rotating tool configured to perform a continuous screw tightening operation on the workpieces, the screw tightening operation can be appropriately, quickly, and smoothly performed, and various inappropriate screw tightening states can be easily and reliably determined even by a human error of an operator.SOLUTION: A driver bit (20) is coupled to a driving output shaft of an electric motor (12) via a clutch mechanism (18), and a rotation amount detection means (24) and / or a load current value detection means (26) for detecting a screw tightening rotation amount based on the rotation of the driver bit are provided to automatically set a target rotation amount and / or a load current value of screw tightening by screw tightening operation by a first plurality of times, and to easily determine the propriety of a proper screw tightening state in screw tightening work thereafter.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method and system for determining the screw tightening state of an electric rotary tool that can be configured to easily and reliably confirm and determine the proper screw tightening state and various improper screw tightening states during screw tightening operations in an electric rotary tool that is configured to perform screw tightening operations by connecting a driver bit to the drive output shaft of an electric motor via a clutch mechanism. [Background technology]

[0002] Various electric screwdrivers that employ a clutch mechanism have been proposed in the past. One proposed electric screwdriver has a control unit that includes a rotation amount detection means for detecting the amount of rotation of the electric motor in the control circuit of the electric motor that rotates the driver bit, and is set to detect and record the amount of rotation of the electric motor during screw tightening work, and detects the completion state of screw tightening by the clutch operation of the clutch mechanism, and successively detects and records the amount of rotation of the electric motor from the start of screw tightening at the time of clutch operation.

[0003] For example, the inventors have successfully developed an automatic screw tightening control method and device that can easily and reliably determine whether a screw is tightened properly or not by using an electric screwdriver having the above-described configuration to perform a first screw tightening operation, thereby starting detection of the rotation amount of the electric motor using the rotation amount detection means, detecting the completion of the screw tightening operation by the clutch operation of the clutch mechanism, detecting and recording the rotation amount of the electric motor from the start of the screw tightening operation at the time of clutch operation, and setting this detected and recorded rotation amount as a target rotation amount. Then, in subsequent screw tightening operations (second and subsequent operations), sequentially detect the rotation amount of the electric motor from the start of the screw tightening operation until the completion of the screw tightening operation and the clutch operation of the clutch mechanism, compare the rotation amount detected at the time of clutch operation with the target rotation amount, and determine whether the screw is tightened properly if the rotation amount matches the target rotation amount (including an allowable range), or whether the screw is tightened improperly or abnormally if the rotation amount does not match the target rotation amount (including an allowable range). This method and device have been patented under Japanese Patent No. 6304661 (Patent Document 1).

[0004] It has also been proposed that an electric screwdriver having the above configuration can be configured to provide a load current detection means to detect and record a load current value proportional to the screw tightening torque value, and that together with a rotation amount detection means to detect and record the rotation amount of the electric motor, the rotation amount and load current value of the electric motor can be detected during clutch operation of the clutch mechanism, and compared with a predetermined target rotation amount (including an allowable range) and also with a predetermined target load current value (including an allowable range) to determine whether the screw tightening condition is good or bad, and that the load current value during clutch operation can be detected and the determination result can be displayed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6304661 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, in the screw tightening device described in Patent Document 1, a screw tightening reference time point (t1) is set, and the amount of rotation of the rotary tool detected by the rotation amount detection means from the start time of screw tightening (t2) to the completion time of screw tightening (t3) is compared with a preset reference value to determine whether it is within an allowable range, thereby making it possible to properly and reliably detect screw tightening defects such as galling of the screw in the screw hole or looseness of the screw, at low cost, with a relatively simple configuration that is easy, convenient, and convenient.

[0007] However, in the screw tightening device, a screw tightening reference time point (t1) is set for each screw tightening operation, and the amount of rotation of the rotary tool is detected by the rotation amount detection means from the screw tightening start time point (t2) to the screw tightening completion time point (t3). Therefore, it is necessary to always pay attention to the operation of setting the screw tightening reference time point (t1). While this is not a particular problem for experienced workers, it is conceivable that when an inexperienced worker performs screw tightening operations, the appropriate work effect and work efficiency exhibited by the invention may not be obtained.

[0008] In an electric screwdriver employing one of the various conventionally proposed clutch mechanisms described above, a rotation amount detection means for detecting the amount of rotation of the electric motor and / or a load current value detection means for detecting the load current value generated in the electric motor is provided in the control circuit of the electric motor that rotates the driver bit, and is set to detect and record the rotation amount and / or load current value of the electric motor during screw tightening work, and the state where screw tightening is completed is detected by the clutch operation of the clutch mechanism, and an electric screwdriver is configured with a control unit that sequentially detects and records the rotation amount and / or load current value of the electric motor from the time when screw tightening began at the time of clutch operation.

[0009] Therefore, when using an electric screwdriver having the above configuration to perform screw tightening operations on multiple workpieces each having multiple common screw tightening points, and when screws with different screw shaft dimensions are applied to the multiple common screw tightening points, and when screw tightening operations are performed in the same order on the multiple common screw tightening points on the multiple workpieces, when tightening operations on the multiple common screw tightening points are performed, the completion state of screw tightening at the multiple common screw tightening points is detected by the clutch operation of the clutch mechanism, and the rotation amount and / or load current value from the start of screw tightening of the electric motor at the time of clutch operation will be detected values ​​that are different for each, so it is difficult to properly perform screw tightening operations on multiple screw tightening points using a single electric screwdriver.

[0010] Therefore, in the present invention, when starting a predetermined screw tightening operation using an electric screwdriver having the above-mentioned configuration, when tightening screws on a plurality of workpieces each having a plurality of common screw tightening points, when screws with different screw axial dimensions are applied to the common screw tightening points, the screw tightening operation is set to be performed in the same order on the common screw tightening points on the plurality of workpieces, and When starting a screw tightening operation, the system is set so that the screw tightening operation is performed in the same order at a plurality of common screw tightening locations for a plurality of pre-set workpieces, The amount of rotation and / or load current value of the electric motor accompanying the rotation of the driver bit from the start of screw tightening to the point at which the clutch mechanism operates upon completion of screw tightening are detected, stored and calculated sequentially for each of the multiple workpieces using the rotation amount detection means and / or load current value detection means, and a target amount of rotation (including the allowable range) and / or target load current value (including the allowable range) are set in the rotation amount memory means and / or load current value memory means, provided that all of the multiple screw tightening states are appropriate, and the detected amount of rotation and / or load current value can be compared with the set target amount of rotation (including the allowable range) and / or target load current value (including the allowable range), thereby determining whether the screw tightening state is appropriate.

[0011] In the present invention, when the initial multiple preliminary screw tightening operations are performed, a standard torque adjustment is performed in advance in the clutch mechanism, and then based on the set target rotation amount (including the allowable range), the screw tightening state is determined for each screw tightening rotation amount detected in a specified screw tightening operation, making it possible to easily and reliably determine whether the screw tightening state is appropriate by conforming to the target rotation amount (including the allowable range).

[0012] Furthermore, when comparing the rotation amount of the electric motor detected sequentially up to the time when the clutch operates or the rotation stops based on the stall torque of the electric motor during a specified screw tightening operation with the target rotation amount set in advance as described above, the rotation amount of the electric motor detected up to the time when the clutch operates or the rotation stops based on the stall torque of the electric motor during a specified screw tightening operation can be calculated by sequentially adding or subtracting from the set value of the target rotation amount, and the final detected value of the rotation amount can be set to be compared with the set value of the target rotation amount (including the tolerance range).

[0013] Furthermore, in the present invention, in an electric rotary tool having the above configuration, a load current value detection means is provided and set to detect and record a load current value proportional to a screw tightening torque value at the same timing as the screw tightening rotation amount, and together with, or instead of, the rotation amount detection means that detects and records the rotation amount of the electric motor, the rotation amount and / or load current value of the electric motor is detected and compared with a predetermined target rotation amount (including an allowable range) and / or a predetermined target load current value (including an allowable range), thereby determining whether the screw tightening state is good or bad, and further the load current value when the clutch is operating can be detected and the determination result can be displayed.

[0014] In the present invention, the electric rotary tool is provided with an operating switch or encoder that operates when the driver bit comes into contact with the object to be screwed, or a push-operated switch that operates due to axial displacement at the time of contact, and by detecting the operating signal, the start point of screw tightening when performing screw tightening work can be set.

[0015] In this way, setting the screw tightening start point when performing a screw tightening operation means that when the amount of rotation of the electric motor detected by the rotation amount detection means is detected and recorded during a screw tightening operation using an electric screwdriver, the drive switch for driving the electric motor is operated with the switch operating member, and at the same time the amount of rotation of the electric motor is detected by the rotation amount detection means.As a result, for example, if the driver bit is allowed to rotate freely until it abuts against the object to be screwed, the amount of rotation detected at the timing of this rotation will make the amount of rotation of the electric motor during the actual screw tightening operation inaccurate.Therefore, by setting the screw tightening start point as described above, it is possible to accurately detect the amount of rotation of the electric motor during the actual screw tightening operation.

[0016] In particular, by detecting the operation signal of the push switch as described above, the start point of the screw tightening operation is set when the driver bit comes into contact with the object to be screwed, and then by operating the drive switch for driving the electric motor, the amount of rotation of the electric motor during the actual screw tightening operation until the screw is seated can be accurately detected.

[0017] Therefore, according to the present invention, as seen in micrometers, with precision screws, improvements in the machining accuracy of the screw pitch dimensions, coupled with the improvement in the accuracy of detecting the amount of screw rotation described above, make it possible to set positioning that corresponds with high precision to the relationship between the amount of screw rotation and the distance traveled by the screw shaft when tightening the screw.This makes it possible to accurately set and confirm the relationship between the position and amount of rotation where the screw will be properly seated on the object to be tightened, and sufficiently improves the reliability of pass / fail judgments in screw tightening operations.

[0018] Therefore, the object of the present invention is to provide a method and system for determining the screw tightening state of an electric rotary tool that can be configured to easily and reliably confirm and determine the screw tightening state in an electric rotary tool that is configured to perform screw tightening operations by connecting a driver bit to the drive output shaft of an electric motor via a clutch mechanism. [Means for solving the problem]

[0019] In order to achieve the above object, a method for determining the tightening state of a screw for an electric rotary tool according to claim 1 of the present invention uses an electric rotary tool that includes an electric motor, a drive switch for driving the electric motor, and a driver bit connected to the drive output shaft of the electric motor via a speed reducer and a clutch mechanism, and that is provided with a switch operating member for operating the drive switch, a clutch operation detection sensor for detecting the clutch operation of the clutch mechanism, an electric motor control circuit that controls the driving and stopping of the electric motor, and a rotation amount detection means for detecting the rotation amount of the electric motor and / or a load current value detection means for detecting a load current value obtained in the electric motor based on a load torque (reaction force) applied to the driver bit, When performing screw tightening work on a plurality of workpieces each having a plurality of common screw tightening points, and when screws having different screw axial dimensions are applied to the common screw tightening points, the screw tightening work is set to be performed in the same order on the common screw tightening points of the plurality of workpieces, and when starting the screw tightening work, the screw tightening work is set to be performed in the same order on the common screw tightening points of the plurality of workpieces, The rotation amount and / or load current value of the electric motor accompanying the rotation of the driver bit from the start of screw tightening to the clutch operation by the clutch mechanism upon completion of screw tightening are detected, stored and calculated sequentially for each of the plurality of workpieces by the rotation amount detection means and / or load current value detection means, and, on the condition that the screw tightening states of the plurality of times are all appropriate, a target rotation amount (including an allowable range) and / or a target load current value (including an allowable range) are set in the rotation amount storage means and / or load current value storage means, During the subsequent screw tightening operation on the workpiece, the rotation amount and / or load current value of the electric motor accompanying the rotation of the driver bit from the start of screw tightening to the clutch operation by the clutch mechanism upon completion of screw tightening are sequentially detected by the rotation amount detection means and / or the load current value detection means, and recorded in the rotation amount storage means and / or the load current value storage means, and the detected rotation amount and / or the load current value are compared with the set target rotation amount (including the allowable range) and / or target load current value (including the allowable range) to determine whether the screw tightening condition is good or bad.

[0020] The method for determining the screw tightening state of an electric rotary tool described in claim 2 of the present invention is characterized in that if it is determined that the rotation amount of the electric motor detected at the time of clutch operation or the time of rotation stop based on the stall torque, which is recorded in the rotation amount memory means, matches the set target rotation amount (including the allowable range), and / or if it is determined that the load current detection value proportional to the screw tightening torque value of the electric motor detected at the time of clutch operation, which is recorded in the load current value memory means, matches the set target load current value (including the allowable range), the screw tightening state is determined to be appropriate and recorded or displayed.

[0021] The method for determining the screw tightening state of an electric rotary tool described in claim 3 of the present invention is characterized in that if the control means determines that the rotation amount of the electric motor when the clutch is operating or not operating, which is recorded in the rotation amount memory means, does not match the set target rotation amount (including the allowable range) during subsequent screw tightening work, and / or if the load current detection value proportional to the screw tightening torque value of the electric motor at the time the clutch is operating, which is recorded in the load current value memory means, does not match the set target load current value (including the allowable range), the screw tightening state is determined to be poor and recorded or displayed.

[0022] The method for determining the screw tightening state of an electric rotary tool described in claim 4 of the present invention is characterized in that, when the screw tightening state is determined to be appropriate, the control means detects and records the number and / or length dimensions of the screws whose screw tightening state is determined to be appropriate.

[0023] A screw tightening state determination system for an electric rotary tool according to claim 5 of the present invention comprises an electric motor, a drive switch for driving the electric motor, and a driver bit connected to a drive output shaft of the electric motor via a speed reducer and a clutch mechanism, the system comprising an electric rotary tool provided with a switch operating member for operating the drive switch, a clutch operation detection sensor for detecting clutch operation of the clutch mechanism, an electric motor control circuit for controlling driving and stopping of the electric motor, and rotation amount detection means for detecting the rotation amount of the electric motor and / or load current value detection means for detecting a load current value obtained in the electric motor based on a load torque (reaction force) applied to the driver bit, When performing screw tightening work on a plurality of workpieces each having a plurality of common screw tightening points, and when screws having different screw axial dimensions are applied to the common screw tightening points, the screw tightening work is set to be performed in the same order on the common screw tightening points of the plurality of workpieces, and when starting the screw tightening work, the screw tightening work is set to be performed in the same order on the common screw tightening points of the plurality of workpieces, The rotation amount and / or load current value of the electric motor accompanying the rotation of the driver bit from the start of screw tightening to the clutch operation by the clutch mechanism upon completion of screw tightening are detected, stored and calculated sequentially for each of the plurality of workpieces by the rotation amount detection means and / or load current value detection means, and a rotation amount storage means and / or load current value storage means are provided which set a target rotation amount (including an allowable range) and / or target load current value (including an allowable range) on the condition that all of the screw tightening states of the plurality of times are appropriate, During the subsequent screw tightening operation on the workpiece, the rotation amount and / or load current value of the electric motor accompanying the rotation of the driver bit from the start of screw tightening to the clutch operation by the clutch mechanism upon completion of screw tightening are sequentially detected by the rotation amount detection means and / or the load current value detection means, and recorded in the rotation amount storage means and / or the load current value storage means, and a control means is provided for controlling the screw tightening state to be judged as good or bad by comparing the detected rotation amount and / or the load current value with the set target rotation amount (including the allowable range) and / or target load current value (including the allowable range).

[0024] The screw tightening state determination system for an electric rotary tool described in claim 6 of the present invention is characterized in that it is provided with a control means which determines the screw tightening state to be appropriate and records or displays it when it is determined that the rotation amount of the electric motor detected at the time of clutch operation or the time of rotation stop based on the stall torque, which is recorded in the rotation amount memory means, matches the set target rotation amount (including the allowable range), and / or when it is determined that the load current detection value proportional to the screw tightening torque value of the electric motor detected at the time of clutch operation, which is recorded in the load current value memory means, matches the set target load current value (including the allowable range).

[0025] The screw tightening state determination system for an electric rotary tool described in claim 7 of the present invention is characterized in that, in the control means, if it is determined that the rotation amount of the electric motor when the clutch is operating or not operating, which is recorded in the rotation amount memory means, does not match the set target rotation amount (including the allowable range) during subsequent screw tightening work, and / or if it is determined that the load current detection value proportional to the screw tightening torque value of the electric motor at the time the clutch is operating, which is recorded in the load current value memory means, does not match the set target load current value (including the allowable range), the screw tightening state is determined to be poor and this is recorded or displayed.

[0026] The screw tightening state determination system for an electric rotary tool described in claim 8 of the present invention is characterized in that, when the screw tightening state is determined to be appropriate in the control means, the number of screws and / or their length dimensions for which the screw tightening state is determined to be appropriate are detected and recorded. [Effects of the Invention]

[0027] According to the screw tightening state determination method and system for an electric rotary tool as set forth in claims 1 and 5 of the present invention, a screw tightening state determination method and system for an electric rotary tool is provided in which a driver bit is coupled to the drive output shaft of an electric motor via a clutch mechanism and used to perform screw tightening work, and when performing a screw tightening work on a plurality of workpieces each having a plurality of common screw tightening points as a first screw tightening operation, when screws with different screw shaft dimensions are applied to the common screw tightening points, the screw tightening work is set to be performed in the same order on the common screw tightening points of the plurality of workpieces, and when the screw tightening work starts, the screw tightening work is set to be performed in the same order on the common screw tightening points of the plurality of workpieces, and The rotation amount and / or load current value of the electric motor accompanying the rotation of the driver bit until the clutch mechanism is engaged upon completion of tightening are detected, stored, and calculated for each of the multiple workpieces by the rotation amount detection means and / or load current value detection means. Furthermore, a rotation amount storage means and / or load current value storage means are provided that set a target rotation amount (including a tolerance range) and / or target load current value (including a tolerance range) on the condition that all of the multiple screw tightening operations are appropriate. By comparing the detected rotation amount and / or load current value with the set target rotation amount (including a tolerance range) and / or target load current value (including a tolerance range) during subsequent screw tightening operations, the quality of the screw tightening can be easily and simply confirmed. Therefore, by using the electric rotary tool of this invention, even an inexperienced screw tightener can easily and accurately tighten screws.

[0028] According to the method and system for determining the screw tightening state of an electric rotary tool as set forth in claims 2, 5, or 6 of the present invention, it is possible to accurately detect the rotational speed of the electric motor during actual screw tightening operations, which in turn facilitates the detection of various screw tightening abnormalities and enables reliable confirmation and determination of the appropriate screw tightening state during screw tightening operations. In this way, according to the present invention, it is possible to smoothly and easily collect and process images of control-related data detected in the clutch-type electric rotary tool being used, thereby improving the control data processing function of the electric rotary tool.

[0029] According to the method and system for determining the screw tightening state of an electric rotary tool as set forth in claim 3 or 7 of the present invention, in addition to determining whether the screw tightening state is good or bad as described above, if the rotational speed of the electric motor is less than the target rotational speed (including the allowable range), it is possible to easily determine whether the screw tightening is defective, for example, by determining whether the screw has galling, loosened threads, or is incompatible with the selected screw shaft dimensions, or by determining whether the rotational speed of the electric motor is more than the target rotational speed (including the allowable range) by determining whether the screw has stripped, worn out pilot hole, cam-out of the screw, broken bit, or is incompatible with the selected screw shaft dimensions. Therefore, according to the present invention, in addition to reducing the defect rate in the screw tightening operation as described above, it is also possible to easily detect and confirm human and material work errors.

[0030] According to the method and system for determining the screw tightening state of an electric rotary tool as set forth in claim 4 or 8 of the present invention, as described above, it is possible to extremely easily and accurately determine whether the screw tightening state is good or bad, and in particular, the number of screws determined to be properly tightened can be reliably recorded in the control unit, distinguished from the number of screws determined to be abnormal or defective, and by confirming or displaying these recorded numbers of screws, it is possible to improve the efficiency and reliability of the screw tightening work. Also, as described above, when the screw tightening state is determined to be good, the axial dimension of the tightened screw can be accurately recorded by the control means based on the amount of rotation detected during clutch operation, and the recorded content can be displayed. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is an explanatory diagram showing a schematic configuration of an embodiment of an electric rotary tool equipped with a system for implementing a method for determining the screw tightening state of an electric rotary tool according to the present invention, and its control system. [Figure 2] 2 is a control system diagram of a system for carrying out the method for determining the screw tightening state of the electric rotary tool according to the present invention shown in FIG. 1. FIG. [Figure 3] 2 is a flowchart showing a screw tightening control program as a basic control operation method for determining whether a screw is tightened properly by the system that implements the method for determining the screw tightening state of the electric rotary tool shown in FIG. 1. FIG. [Figure 4] FIG. 4 is an explanatory diagram showing multiple common screw tightening positions for multiple workpieces when performing the first screw tightening operation shown in FIG. 3 using a system that implements the method for determining the screw tightening state of an electric rotary tool according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] Next, embodiments of a method and system for determining the tightening state of a screw in an electric rotary tool according to the present invention will be described in detail below with reference to the accompanying drawings.

[0033] [ Example of system configuration for implementing the method for determining the tightening state of a screw ] Fig. 1 is a schematic diagram illustrating an embodiment of an electric rotary tool that constitutes a method and system for determining the tightening state of a screw according to the present invention. In Fig. 1, reference numeral 10 denotes an electric rotary tool, and the grip of this electric rotary tool 10 incorporates an electric motor 12, a drive switch 13 for driving this electric motor 12, a reduction mechanism 16 connected to the drive output shaft (not shown) of the electric motor 12, and a clutch mechanism 18, and a driver bit 20 is connected to the electric motor 12 via the clutch mechanism 18.

[0034] The electric rotary tool 10 is provided with a switch operating member 14 for operating the drive switch 13 of the electric motor 12, an electric motor control circuit 22 for controlling the drive and stop of the electric motor 12, and a clutch operation detection sensor 28 for detecting the clutch operation of the clutch mechanism 18. The electric motor control circuit 22 is provided with rotation amount detection means 24 for detecting the rotation amount of the leading electric motor 12. Furthermore, load current detection means 26 is provided as appropriate for detecting the load current obtained in the electric motor 12 based on the load torque (reaction force) applied to the driver bit 20.

[0035] In the electric rotary tool 10 of this embodiment, a brushless motor can be suitably used as the electric motor 12. Furthermore, the switch operating member 14 that operates the drive switch 13 to drive the electric motor 12 can be configured as, for example, a known lever member provided on the outer periphery of the grip of the electric rotary tool 10.

[0036] In this embodiment, the rotation amount detecting means 24 for detecting the rotation amount of the electric motor 12 can be provided as a means for counting pulses generated when a Hall element that detects the magnetic pole of the rotor of the brushless motor detects the magnetic pole. In this case, the number of counted pulses detected by the rotation amount detecting means 24 can be detected and recorded as an amount of rotation that correlates with the amount of rotation for screw tightening during a screw tightening operation accompanied by the rotation of the driver bit 20.

[0037] Furthermore, the load current value detection means 26 for detecting the load current value of the electric motor 12 can be provided as a means for detecting the load current value in the power supply circuit of the electric motor 12. In this case, the detected load current value of the electric motor 12 can be detected and recorded as a load current value that correlates with the screw tightening torque value during screw tightening work accompanied by rotation of the driver bit 20.

[0038] The clutch mechanism 18 is configured, for example, by attaching a clutch plate to the output shaft of the speed reduction mechanism 16, with a clutch ball elastically engaging with the clutch plate in the axial direction, so that when a load torque (reaction force) greater than a certain level is applied to the output shaft via the driver bit 20 during screw tightening work, the clutch plate overcomes the clutch ball, cutting off the transmission of rotational driving force to the bit holder that engages and holds the driver bit 20, allowing the screw to be tightened with a preset torque. In this case, the screw tightening torque can be set by appropriately adjusting the elasticity of the clutch ball when it elastically engages with the clutch plate.

[0039] The clutch operation detection sensor 28 that detects the clutch operation of the clutch mechanism 18 can be configured using known means, such as a limit switch that is activated by the displacement of the clutch plate at the time of clutch operation, or a magnetic sensor that detects the rotation of the internal gear that constitutes the reduction mechanism 16 that rotates freely at the time of clutch operation.

[0040] Therefore, in this embodiment, a control unit 30 is provided as a control means for determining the screw tightening state, and the CPU 32 inputs a drive switch operation signal S13 obtained by the operation of the drive switch 13 operated by the switch operation member 14 to the electric motor control circuit 22 provided on the electric motor 12 in the electric rotary tool 10 when starting a screw tightening operation, and based on this drive switch operation signal S13, outputs a motor drive control signal S22a and inputs it to the electric motor control circuit 22 to control the drive of the electric motor 12.

[0041] When the required screw tightening operation is performed by driving the electric motor 12, the CPU 32 is set to detect and record the rotation amount Rt of the electric motor 12 based on the rotation amount detection signal S24 detected by the rotation amount detection means 24 at the time t0 when the electric motor 12 starts to be driven in conjunction with the start of the screw tightening operation.

[0042] Also, similarly to the above, at the time t0 when the electric motor 12 starts to drive in response to the start of the screw tightening operation, the load current value It proportional to the screw tightening torque value is detected and recorded based on the load current value detection signal S26 detected by the load current value detection means 26.

[0043] The CPU 32 is configured to detect the rotation amount of the electric motor 12 at the clutch operation time t1 obtained based on the clutch operation detection signal S28 detected by the clutch operation detection sensor 28 at the clutch operation time of the clutch mechanism 18, and to detect and record the setting of a target rotation amount Rm±α (±α is an allowable range) described below and the rotation amount Rt1 to be compared with this target rotation amount Rm±α.

[0044] Also, as described above, at the clutch operation time t1 obtained based on the clutch operation detection signal S28 detected by the clutch operation detection sensor 28 at the time of clutch operation of the clutch mechanism 18, a load current value proportional to the screw tightening torque value is detected, and the target load current value Im±β (±β is an allowable range) described below and the load current value It1 for comparison with this target load current value Im±β are detected and recorded.

[0045] As mentioned above, when clutch operation is detected by the clutch operation detection sensor 28, a motor stop control signal S22b is output via the CPU 32 and input to the electric motor control circuit 22, so that stop control of the electric motor 12 is performed.

[0046] Furthermore, in this embodiment, as described above, when the CPU 32 of the control unit 30 determines whether the screw tightening state is good or bad by comparing the rotation amount Rt1 detected at the clutch operation time t1 with the preset target rotation amount Rm±α, and / or when the CPU 32 determines whether the screw tightening state is good or bad by comparing the load current value It1 detected at the clutch operation time t1 with the preset target load current value Im±β, the CPU 32 outputs one of the screw tightening determination signals S40, and the respective determination results are displayed on the display 40 as appropriate.

[0047] Next, an embodiment of the method and system for determining the screw tightening state in an electric rotary tool having the above-described configuration will be described based on a control system diagram of the control unit 30 and a flowchart showing the control operation, in terms of the steps up to determining whether the screw tightening state is good or bad during a screw tightening operation.

[0048] [ The inventive method of the electric rotary tool according to the present invention ] FIG. 2 shows the control system of the control unit 30 of an electric rotary tool equipped with a system for implementing the screw tightening state determination method of the present invention shown in FIG. 1, and FIG. 3 is a flowchart showing the control operation of the control unit 30 of the electric rotary tool shown in FIG. 1.

[0049] 2, in the control system of the control unit 30 of the electric rotary tool embodying the present invention, a CPU 32 denotes a processor that controls the entire system, and is connected via a data bus to the above-mentioned operation switch (encoder) 13, rotation amount detection means 24, load current detection means 26, and electric motor control circuit 24. Also connected to the data bus of the CPU 32 is a ROM 50 that stores a control program, and a RAM 60 that serves as storage means for storing detection data associated with the operation of the electric rotary tool 10 detected by the operation switch (encoder) 13, rotation amount detection means 24, and load current value detection means 26.

[0050] That is, the RAM 60 is provided with a screw tightening start time memory unit 61 that records and sets the screw tightening start time, a rotation amount memory unit 62 that records the rotation amount detected by the rotation amount detection means 24 and sets a target rotation amount, and a load current value memory unit 63 that records the load current value detected by the load current value detection means 26 and sets a target load current value.

[0051] Furthermore, an LCD 40a serving as a display device for externally displaying data based on various data stored in the RAM 60 is connected to the data bus of the CPU 32 via an LCDIC 40b serving as its control circuit, and an input / output circuit 52 for inputting and outputting data etc. via an external controller as appropriate is also connected.

[0052] Next, as a specific example of the screw tightening state determination method and system according to the present invention, the control operation shown in FIG. 3 will be described based on the configuration of the electric rotary tool 10 shown in FIG. 1 and the control system of the control unit 30 of the system shown in FIG. 2.

[0053] First, when driving the electric rotary tool 10 that implements the screw tightening state determination method and system of the present invention, the drive switch 13 is activated by operating the switch operating member 14, and the motor drive control signal S22a is input to the electric motor control circuit 22, which controls the drive of the electric motor 12 and starts driving the electric screwdriver 10 (see FIGS. 1 and 2). In this case, when using the electric rotary tool 10 for the first time, it is necessary to previously perform a standard torque adjustment on the clutch mechanism 18 in accordance with the standard of the screw used in the applicable screw tightening operation.

[0054] 3 and 4, when the electric rotary tool 10 is used for the first time, a first to fifth screw tightening operation is performed on a plurality of (e.g., 1 to 5) workpieces W1 to W5 each having the same configuration and each having a common plurality of screw tightening points (No. 1, No. 2, No. 3, ... No. 5) as the required screw tightening targets (STEP-1). In this case, the screw tightening start time t0, which is the time when the electric motor 12 starts to be driven, is detected by actuation of the drive switch 13 provided on the electric rotary tool 10, and is recorded in the screw tightening start time memory unit 61 of the RAM 60 (see FIG. 2).

[0055] Next, the rotation amount and / or load current value of the electric motor associated with the rotation of the driver bit from the start of screw tightening to the clutch operation by the clutch mechanism upon completion of screw tightening at the common multiple screw tightening locations (No. 1, No. 2, No. 3, ... No. 5) are detected, stored and calculated sequentially for the multiple workpieces W (W1 to W5) by the rotation amount detection means 24 and / or load current value detection means 26, and, provided that the screw tightening conditions are all appropriate, the target rotation amount (including the allowable range) and / or target load current value (including the allowable range) for each of the multiple screw tightening locations (No. 1, No. 2, No. 3, ... No. 5) are recorded in the rotation amount memory unit 62 and / or the load current value memory unit 63 (see Figures 2, 3 and 4).

[0056] In this case, the rotation amount detection means 24 provided in the electric rotary tool 10 starts counting the rotation amount of the electric motor 12, which is proportional to the rotation amount of the driver bit 20 that performs the screw tightening. Then, the screw tightening is performed by the driver bit 20, and the screw tightening rotation amounts counted up to time t1 when the clutch operation is performed by the clutch mechanism 18 are recorded in the rotation amount memory unit 62 of the RAM 60 (STEP-2).

[0057] Similarly to the rotation amount detection means 24 provided in the electric rotary tool 10, the load current detection means 26 provided in the electric rotary tool 10 starts to detect the load current It proportional to the screw tightening torque of the electric motor 12 based on the load current detection signal S26 (STEP-1'). Then, the screw is tightened by the driver bit 20, and the load current values ​​of the electric motor 12 detected successively up to time t1 when the clutch mechanism 18 performs the clutch operation are recorded in the load current value memory section 63 of the RAM 60 (STEP-2').

[0058] In this way, provided that all screw tightening conditions are performed properly during the multiple screw tightening operations, the target rotation amount Rm±α (±α is an allowable range) and / or target load current value Im±β (±β is an allowable range) are automatically set in the rotation amount memory unit 62 and / or the load current value memory unit 63 based on the screw tightening rotation amount recorded in the rotation amount memory unit 62 and / or the screw tightening load current value recorded in the load current value memory unit 63 (STEP-3, STEP-3').

[0059] In this way, the target rotation amount Rm±α (±α is an allowable range) is set in the electric rotary tool 10, thereby enabling the subsequent required screw tightening operation (STEP-4). Therefore, when the subsequent required screw tightening operation is performed by the electric rotary tool 10 (STEP-4), the screw tightening rotation amount counted from the screw tightening start time t0 to the time t1 when the clutch operation is performed by the clutch mechanism 18 is detected and recorded in the rotation amount storage unit 62 (STEP-5), as in the case described above.

[0060] Furthermore, by setting the target load current value Im±β (including the allowable range) in the electric rotary tool 10, the desired screw tightening operation can be performed thereafter (STEP-4'). Therefore, when the desired screw tightening operation is performed by the electric rotary tool 10 thereafter (STEP-4'), the load current value It1 of the electric motor 12 is successively detected from the screw tightening start time t0 to the time t1 when the clutch operation of the clutch mechanism 18 is performed, as in the case described above, and recorded in the load current value storage unit 63 (STEP-5').

[0061] As described above, the detected screw tightening rotation amount Rt1 is compared with the target rotation amount Rm±α (±α is an allowable range) set in the rotation amount storage unit 62 (STEP-6), and the quality of the screw tightening state is determined based on the result. That is, when comparing the detected screw tightening rotation amount Rt1 with the target rotation amount Rm±α (±α is an allowable range), if the condition Rm+α≧Rt1≧Rm-α is satisfied, the screw tightening state is determined to be appropriate (STEP-7), and if the condition is not satisfied, the screw tightening state is determined to be poor or abnormal (STEP-8).

[0062] Furthermore, as described above, the detected load current value It1 is compared with the target load current value IRm±β (±β is an allowable range) set in the load current value storage unit 63 (STEP-6'), and the quality of the screw tightening state is determined based on the result of the comparison. That is, when the detected load current value It1 is compared with the target load current value Im±β (±β is an allowable range), if the condition Im+β≧It1≧Im-β is satisfied, the screw tightening state is determined to be appropriate (STEP-7'), and if this condition is not satisfied, the screw tightening state is determined to be poor or abnormal (STEP-8').

[0063] In addition, when the screw tightening operation using the electric rotary tool 10 and the start of the subsequent screw tightening work (STEP-1 and STEP-4) are performed, if the rotation amount Rt of the electric motor 12 is recorded in the rotation amount memory unit 61 based on the rotation amount detection signal S24 detected by the rotation amount detection means 24, the accurate rotation amount can be detected by detecting the rotation amount Rt of the electric motor 12 from the time the driver bit 20 comes into contact with the object to be screwed until the screw tightening work is actually performed.

[0064] Therefore, in the present invention, as proposed by the applicant in Patent No. 4721535, for example, a push-operated switch (not shown) is provided in the electric screwdriver 10 that is activated by axial displacement when the driver bit 20 abuts against the object to which the screw is to be attached, and the operating signal of this push-operated switch can be used to set the start time t0 of screw tightening when performing screw tightening work.

[0065] In this way, when the screw tightening state is judged to be good or bad, a judgment display can be made that clearly distinguishes between a good judgment and a bad judgment. Therefore, the electric rotary tool 10 according to the present invention can be configured to appropriately display the respective judgment contents on the LCD 40a as a display device in accordance with any of the screw tightening judgment signals S40 output from the control unit 30 (see FIGS. 1 and 2).

[0066] A preferred embodiment of the present invention has been described above, but a known rotary encoder can be used as the rotation amount detection means of the electric rotary tool 10 of this embodiment. In this case, the rotation amount of the driver bit 20 can be set as the rotation amount detection means by inputting a detection signal from the encoder to the CPU 32 of the control unit 30.

[0067] Furthermore, in the present invention, when the rotational drive of the electric motor reaches the stall torque upon completion of screw tightening, the rotation stops. By providing an encoder or the like for the electric motor 12, it is possible to detect when the rotation of the electric motor 12 stops due to the stall torque. This makes it possible to properly detect the amount of rotation of the electric motor 12 from the start of screw tightening to the completion of screw tightening, or the load current value of the electric motor 12.

[0068] Furthermore, in the present invention, when performing screw tightening work using an electric rotary tool, equipment can be provided that irradiates the workpieces, each positioned at a predetermined position, with the required beam of light to sequentially specify the screw tightening positions from above, in accordance with a predetermined order of screw tightening positions corresponding to a common workpiece.

[0069] As is clear from the above examples, the method and system for determining the screw tightening state of an electric rotary tool according to the present invention has the excellent effect of easily and reliably detecting human work errors, such as making a mistake in the order of screw installation positions corresponding to a predetermined common workpiece, or making a mistake in the selection of a screw specified for a predetermined screw installation position.

[0070] Furthermore, according to the method and system for determining the screw tightening state of an electric rotary tool of the present invention, when a predetermined number of screws are tightened sequentially during a required screw tightening operation, the judgment of whether the screw tightening state is good or bad for each screw as described above can be detected and recorded, and at the same time, the number of tightened screws can be detected and recorded all at once, making it possible to easily realize the construction of a production management system for production lines that perform various screw tightening operations and their networks.

[0071] In particular, the method and system for determining the screw tightening state with an electric rotary tool according to the present invention utilizes a clutch mechanism to properly detect the rotational speed of the electric motor driven by the electric screwdriver during a required screw tightening operation, thereby easily and reliably determining the correct screw tightening completion (screw seating) state and recording or displaying the tightening state of each screw in relation to the number of screws to be tightened continuously. Furthermore, by detecting and recording the load current value of the electric motor at the time of clutch operation during each screw tightening operation, the load current value at the time of clutch operation can be confirmed with an extremely accurate correlation with the tightening torque value of each screw that has been tightened (seated). Therefore, by setting the system to detect, record, or display the load current value of the electric motor in combination with the detection of the rotational speed of the electric motor, it becomes possible to easily realize the construction of a production management system for a production line that performs various screw tightening operations and a network of such production lines.

[0072] The above describes a preferred embodiment of the present invention in which screw tightening control is performed using a normal screw on an object with a normal screw hole, but the present invention is not limited to this embodiment and can be similarly applied to screw tightening control using a tapping screw or drill screw, or to an electric rotary tool that performs thread processing using a tap.

[0073] The above describes a preferred embodiment of the present invention in which screw tightening control is performed using a normal screw on an object with a normal screw hole, but the present invention is not limited to this embodiment and can be similarly applied to, for example, screw tightening control using a tapping screw or drill screw, or a method and system for determining the screw tightening state of an electric rotary tool that performs thread processing using a tap. [Explanation of symbols]

[0074] 10 Electric rotary tool 12 Electric motor 13 drive switch 14 switch operating member 16 Reduction mechanism 18 Clutch mechanism 20 driver bit 22 electric motor control circuit 24 Rotation amount detection means 25 First encoder (rotation amount detection means) 26 Load current value detection means 28 Clutch operation detection sensor 29 Second encoder (rotation amount detection means) 30 control unit 32 CPU 40 Display 40a LCD 40b LCDIC 50 ROM 52 Input / output circuit 60 RAM 61 Screw tightening start time memory section 62 Rotation amount storage unit 63 Load current value storage unit S13 Drive switch operation signal S22a Motor drive control signal S22b Motor stop control signal S24 Rotation amount detection signal S25 Encoder detection signal S26 Load current value detection signal S28 Clutch operation detection signal S29 Encoder detection signal S40 Screw tightening status judgment signal Rm±α Target rotation amount (including tolerance range) Im±β Target load current value (including tolerance range) t0 Electric motor drive start time / screw tightening start time t1 Clutch operation time Rt1 Amount of rotation at clutch operation It1 Load current detection value at clutch operation No.1~No.5 screw tightening positions W1~W5 Work

Claims

1. an electric rotary tool including an electric motor, a drive switch for driving the electric motor, and a driver bit connected to a drive output shaft of the electric motor via a reduction mechanism and a clutch mechanism, the electric rotary tool also including a switch operating member for operating the drive switch, a clutch operation detection sensor for detecting clutch operation of the clutch mechanism, an electric motor control circuit for controlling driving and stopping of the electric motor, and a rotation amount detection means for detecting the rotation amount of the electric motor and / or a load current value detection means for detecting a load current value obtained in the electric motor based on a load torque (reaction force) applied to the driver bit; When performing screw tightening work on a plurality of workpieces each having a plurality of common screw tightening points, and when screws having different screw axial dimensions are applied to the common screw tightening points, the screw tightening work is set to be performed in the same order on the common screw tightening points of the plurality of workpieces, and when starting the screw tightening work, the screw tightening work is set to be performed in the same order on the common screw tightening points of the plurality of workpieces, The rotation amount and / or load current value of the electric motor accompanying the rotation of the driver bit from the start of screw tightening to the clutch operation by the clutch mechanism upon completion of screw tightening are detected, stored and calculated sequentially for each of the plurality of workpieces by the rotation amount detection means and / or load current value detection means, and, on the condition that the screw tightening states of the plurality of times are all appropriate, a target rotation amount (including an allowable range) and / or a target load current value (including an allowable range) are set in the rotation amount storage means and / or load current value storage means, A method for determining the screw tightening state of an electric rotary tool, characterized in that during the subsequent screw tightening work on the workpiece, the rotation amount and / or load current value of the electric motor accompanying the rotation of the driver bit from the start of screw tightening to the clutch operation by the clutch mechanism upon completion of screw tightening are sequentially detected by the rotation amount detection means and / or the load current value detection means, and recorded in the rotation amount storage means and / or the load current value storage means, and the detected rotation amount and / or the load current value are compared with the set target rotation amount (including the allowable range) and / or target load current value (including the allowable range) to determine whether the screw tightening state is good or bad.

2. The method for determining the screw tightening state of an electric rotary tool according to claim 1, characterized in that if it is determined that the rotation amount of the electric motor detected at the time of clutch operation or the time of rotation stop based on the stall torque, which is recorded in the rotation amount storage means, matches a set target rotation amount (including an allowable range), and / or if it is determined that the load current detection value proportional to the screw tightening torque value of the electric motor detected at the time of clutch operation, which is recorded in the load current value storage means, matches a set target load current value (including an allowable range), the screw tightening state is determined to be appropriate and recorded or displayed.

3. The method for determining the screw tightening state of an electric rotary tool according to claim 2, characterized in that if, during subsequent screw tightening work, it is determined that the rotation amount of the electric motor when the clutch is operating or when it is not operating, which is recorded in the rotation amount memory means, does not match the set target rotation amount (including the tolerance range), and / or if it is determined that the load current detection value proportional to the screw tightening torque value of the electric motor at the time the clutch is operating, which is recorded in the load current value memory means, does not match the set target load current value (including the tolerance range), the screw tightening state is determined to be poor and this is recorded or displayed.

4. The method for determining the screw tightening state of an electric rotary tool according to claim 2, characterized in that, when the screw tightening state is determined to be appropriate, the number of screws whose screw tightening state is determined to be appropriate and / or their length dimensions are detected and recorded.

5. an electric rotary tool including an electric motor, a drive switch for driving the electric motor, and a driver bit connected to a drive output shaft of the electric motor via a reduction mechanism and a clutch mechanism, the electric rotary tool further including a switch operating member for operating the drive switch, a clutch operation detection sensor for detecting clutch operation of the clutch mechanism, an electric motor control circuit for controlling driving and stopping of the electric motor, and a rotation amount detection means for detecting the rotation amount of the electric motor and / or a load current value detection means for detecting a load current value obtained in the electric motor based on a load torque (reaction force) applied to the driver bit, When performing screw tightening work on a plurality of workpieces each having a plurality of common screw tightening points, and when screws having different screw axial dimensions are applied to the common screw tightening points, the screw tightening work is set to be performed in the same order on the common screw tightening points of the plurality of workpieces, and when starting the screw tightening work, the screw tightening work is set to be performed in the same order on the common screw tightening points of the plurality of workpieces, The rotation amount and / or load current value of the electric motor accompanying the rotation of the driver bit from the start of screw tightening to the clutch operation by the clutch mechanism upon completion of screw tightening are detected, stored and calculated sequentially for each of the plurality of workpieces by the rotation amount detection means and / or load current value detection means, and a rotation amount storage means and / or load current value storage means are provided which set a target rotation amount (including an allowable range) and / or target load current value (including an allowable range) on the condition that all of the screw tightening states of the plurality of times are appropriate, A screw tightening state determination system for an electric rotary tool, characterized in that during the subsequent screw tightening work on the workpiece, the rotation amount and / or load current value of the electric motor accompanying the rotation of the driver bit from the start of screw tightening to the clutch operation by the clutch mechanism upon completion of screw tightening are sequentially detected by the rotation amount detection means and / or the load current value detection means, and recorded in the rotation amount storage means and / or the load current value storage means, and the system is provided with control means for controlling to determine whether the screw tightening state is good or bad by comparing the detected rotation amount and / or the load current value with the set target rotation amount (including an allowable range) and / or target load current value (including an allowable range).

6. The screw tightening state determination system for an electric rotary tool according to claim 5, further comprising a control means for determining that the screw tightening state is appropriate and recording or displaying the determination if the rotation amount of the electric motor detected at the time of clutch operation or at the time of rotation stop based on the stall torque, which is recorded in the rotation amount storage means, is determined to match a set target rotation amount (including an allowable range), and / or if the load current detection value proportional to the screw tightening torque value of the electric motor detected at the time of clutch operation, which is recorded in the load current value storage means, is determined to match a set target load current value (including an allowable range).

7. The screw tightening condition determination system for an electric rotary tool according to claim 5, wherein the control means is configured to determine that the screw tightening condition is poor and record or display this if, during a subsequent screw tightening operation, it determines that the amount of rotation of the electric motor when the clutch is operating or not, which is recorded in the rotation amount storage means, does not match the set target rotation amount (including the allowable range), and / or if it determines that the load current detection value proportional to the screw tightening torque value of the electric motor at the time the clutch is operating, which is recorded in the load current value storage means, does not match the set target load current value (including the allowable range).

8. The screw tightening state determination system for an electric rotary tool according to claim 5, characterized in that, when the control means determines that the screw tightening state is appropriate, the number of screws whose screw tightening state is determined to be appropriate and / or their length dimensions are detected and recorded.

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