JP3249336U - Electric motor drive control system for electric rotary tools - Google Patents

Abstract

[Problem] To provide an electric motor drive control system for an electric rotating tool, which, when an improper screw tightening state is determined, immediately switches the electric motor to reverse drive to quickly and easily remove the screw. [Solution] An electric rotating tool 10 is provided with a switch operating member 14 for operating a drive switch 13 of an electric motor 12, an electric motor drive 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 a clutch mechanism 18. The electric motor drive control circuit 22 is provided with a rotation amount detection means 24 for detecting the rotation amount of the leading electric motor 12. Furthermore, a load current detection means 26 is appropriately provided for detecting a load current obtained in the electric motor 12 based on a load torque (reaction force) applied to a driver bit 20. [Selected Figure] Figure 1

Description

This invention relates to an electric motor drive control system for 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, and that can simply and reliably confirm and determine whether a screw is properly tightened and whether there are various inappropriate screw tightening states during screw tightening operations, and that can immediately switch the electric motor to reverse drive if an inappropriate screw tightening state is determined, thereby quickly and easily removing the screw.

Various electric screwdrivers using a clutch mechanism have been proposed in the past. An electric screwdriver has been proposed in which a rotation amount detection means for detecting the amount of rotation of an electric motor is provided in a control circuit of an electric motor that rotates a driver bit, and the amount of rotation of the electric motor is set to be detected and recorded during screw tightening work, and a control unit is provided that 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 this clutch operation.

Therefore, the inventor first uses the electric screwdriver having the above configuration to perform a proper screw tightening operation (first time) at the start of a predetermined screw tightening operation, thereby starting detection of the rotation amount of the electric motor by the rotation amount detection means, then detects the completion state of the screw tightening by the clutch operation of the clutch mechanism, detects and records the rotation amount from the start of the screw tightening operation of the electric motor at the time of the clutch operation, and sets the detected and recorded rotation amount as a target rotation amount. Then, in the subsequent predetermined screw tightening operation (second time onwards), sequentially detects the rotation amount of the electric motor from the start of the screw tightening operation to the time of the clutch operation of the clutch mechanism after the screw tightening is completed, compares the rotation amount detected at the time of the clutch operation with the target rotation amount, and judges that the screw tightening state is proper if the rotation amount matches the target rotation amount (including the allowable range), and easily and reliably judges that the screw tightening state is defective or abnormal if the rotation amount does not match the target rotation amount (including the allowable range). The inventor has succeeded in developing an automatic screw tightening control method and device, which has been patented as Japanese Patent No. 6304661 (Patent Document 1).

It has also been proposed that in an electric screwdriver configured as described above, a load current detection means can be provided and set to detect and record a load current value proportional to a screw tightening torque value, and together with a rotation amount detection means which detects and records 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 preset target rotation amount (including an acceptable range) as well as a preset target load current value (including an acceptable range) to determine whether the screw tightening condition is good or bad, and further the load current value during clutch operation can be detected and the determination result can be displayed.

Patent No. 6304661

As described 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 rotating 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, and screw tightening defects such as galling of the screw in the screw hole or loosening of the screw can be detected easily, simply, and reliably at low cost with a relatively simple configuration.

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

In an electric screwdriver that employs the various clutch mechanisms proposed in the prior art 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 an electric screwdriver is configured in which the completion state of screw tightening is detected by the clutch operation of the clutch mechanism, and the rotation amount and/or load current value of the electric motor from the start of screw tightening at the time of clutch operation is detected and recorded sequentially.

Therefore, when using an electric screwdriver having the above configuration to perform screw tightening operations on a number of workpieces each having a number of common screw tightening points, for example, when screws with different screw shaft dimensions are applied to the common screw tightening points, and when screw tightening operations are performed in the same order on the common screw tightening points of the multiple workpieces, in the screw tightening operations at the common screw tightening points, the completion state of screw tightening 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 different detection values for each, so it is difficult to properly perform screw tightening operations on each of the multiple screw tightening points using a single electric screwdriver.

From this perspective, the inventor has discovered that, when starting a screw tightening operation, it is possible to set the screw tightening operation to be performed in the same order on a plurality of pre-set workpieces at a plurality of common screw tightening points, and to detect, store and calculate 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 sequentially for the plurality of workpieces by the rotation amount detection means and/or load current value detection means, and to set target rotation amount (including tolerance range) and/or target load current value (including tolerance range) in the rotation amount storage means and/or load current value storage means, on the condition that all of the plurality of screw tightening states are appropriate, and to determine whether or not each screw tightening state is appropriate by comparing the detected rotation amount and/or load current value with the set target rotation amount (including tolerance range) and/or target load current value (including tolerance range).

Therefore, the present inventor has confirmed that when using an electric screwdriver having the above-mentioned configuration to start a specified screw tightening operation, when tightening screws on multiple workpieces each having multiple common screw tightening points, for example when screws of different types such as screw shaft dimensions are applied to the multiple common screw tightening points, and when setting up to tighten screws in the same order to the multiple common screw tightening points in the multiple workpieces to which the screws are applied, if the screw tightening worker tightens the screw with the wrong type of screw that was previously set for the specified screw tightening point, when determining whether the screw tightening condition is good or bad, it is confirmed that the screw is in a poor or abnormal state, and in such a case it is necessary to immediately remove the screw, select the appropriate type of screw again, and quickly perform the screw tightening operation again.

Therefore, the inventor discovered that if a screw tightening worker mistakenly selects the wrong pre-set type of screw at a specified screw tightening location and the screw tightening condition is determined to be poor, by providing an automatic reverse drive control mechanism that can immediately and automatically switch the drive output shaft of the electric motor to reverse drive, it is possible to quickly and easily remove the screw, select the appropriate type of screw again, and perform the screw tightening operation again easily and reliably.

Therefore, the object of the present invention is to provide an electric motor drive control system for 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, and that is equipped with an electric rotary tool having a control means having a screw tightening condition judgment function that can properly judge whether the screw tightening condition is good or bad, so that when it is confirmed that the screw tightening condition is poor during the required screw tightening operation, the screw removal operation can be performed quickly and easily.

In order to achieve the above object, the electric motor drive control system of the present invention described in claim 1 comprises an electric rotary tool that is set to perform a required screw tightening operation on a specified screw-attaching object, and is equipped with a control means having a function of judging the quality of the screw tightening state after the screw tightening is completed, and is characterized in that, during the process of performing the required screw tightening operation on a specified screw-attaching object using the electric rotary tool, when the control means for judging the quality of the screw tightening state judges that the screw tightening state is poor, the electric motor drive control circuit is provided with an automatic reverse drive control mechanism configured to automatically switch the drive of the electric motor of the electric rotary tool from forward drive to reverse drive immediately to continuously perform screw removal operation.

In the electric motor drive control system for an electric rotating tool equipped with a control means having a screw fastening state determination function according to claim 2 of the present invention, the electric rotating tool equipped with a control means having a screw fastening state determination function 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 reduction gear mechanism and a clutch mechanism, and further includes a switch operation 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 for controlling the drive 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,
In the rotation amount storage means and/or the load current value storage means, the target rotation amount (including a tolerance range) and/or the target load current value (including a tolerance range) are set for the rotation amount and/or the 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 accompanying the completion of screw tightening,
The electric rotary tool is characterized in that when 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 are sequentially detected by the rotation amount detection means and/or the load current value detection means, they are recorded in the rotation amount memory means and/or the load current value memory means, and the detected rotation amount and/or load current value are compared with the set target rotation amount (including an allowable range) and/or target load current value (including an allowable range) to determine whether the screw tightening condition is good or bad.

The electric motor drive control system for an electric rotating tool equipped with a control means having a function of determining whether a screw tightening state is good or bad as described in claim 3 of the present invention is characterized in that, in the control means having the function of determining whether a screw tightening state is good or bad, 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 a set target rotation amount (including an 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 a set target load current value (including an allowable range).

The electric motor drive control system of an electric rotating tool equipped with a control means having a function of determining whether a screw tightening state is good or bad as described in claim 4 of the present invention is characterized in that, in the control means having the function of determining whether a screw tightening state is good or bad, when 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, during a required screw tightening operation, does not match a set target rotation amount (including an 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 at the time of clutch operation, which is recorded in the load current value memory means, does not match a set target load current value (including an allowable range), the screw tightening state is determined to be poor and recorded or displayed.

The electric motor drive control system of the electric rotating tool having a control means having a function of determining whether the screw fastening state is good or bad according to the fifth aspect of the present invention is characterized in that it is provided with an indicator set to generate an effective visual or audible alarm when the screw fastening state is determined to be bad.

According to the electric motor drive control system for an electric rotating tool described in claim 1 of the present invention, when a screw is tightened by selecting the wrong type of pre-set screw and the screw tightening condition is determined to be poor, the drive output shaft of the electric motor can be immediately and automatically switched to reverse drive, thereby quickly and easily removing the screw, and then the appropriate type of screw can be selected again and the screw tightening operation can be performed easily and reliably.

According to the electric motor drive control system for an electric rotating tool as set forth in claim 2 of the present invention, an electric rotating tool having a control means having a function of determining whether a screw tightening state is good or bad, in which a driver bit is coupled to the drive output shaft of an electric motor via a clutch mechanism and configured to perform screw tightening work, is used, and when a screw tightening work is set to be performed on a plurality of predetermined common workpieces using the same or different types of screws at a plurality of required screw tightening locations, 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 point by the clutch mechanism accompanying the completion of screw tightening are detected, stored and calculated by a rotation amount detection means and/or a load current value detection means, respectively, to determine a target rotation amount (including a tolerance range) and/or a load current value under the condition that all of the screw tightening states are proper. Alternatively, by using an electric rotary tool equipped with a screw tightening state determination function that provides a rotation amount memory means and/or load current value memory means for setting a target load current value (including a tolerance range), and by comparing the rotation amount and/or load current value detected in a subsequent screw tightening operation with the set target rotation amount (including a tolerance range) and/or target load current value (including a tolerance range), the quality of the screw tightening state can be properly determined easily and simply. As described above, when a screw tightening operation is performed by mistakenly selecting the preset type of screw, and the quality of the screw tightening state is determined to be poor, the drive output shaft of the electric motor can be immediately and automatically switched to reverse drive, so that the screw removal operation can be quickly and simply performed, and the appropriate type of screw can be selected again and the screw tightening operation can be performed easily and reliably.

According to the electric motor drive control system for an electric rotating tool equipped with a control means having a function of determining whether a screw tightening state is good or bad as described in claim 2 of the present invention, it is possible to accurately detect the amount of rotation of the electric motor while a screw is actually being tightened, and based on this, it is possible to easily detect various screw tightening abnormalities and reliably confirm and determine the proper screw tightening state during the screw tightening operation. In this way, according to the present invention, it is possible to smoothly and easily achieve the collection or image processing of control-related data detected in the clutch-type electric rotating tool used, and to improve the control data processing function of the electric rotating tool.

Furthermore, according to the electric motor drive control system for an electric rotating tool equipped with a control means having a function of determining whether a screw is fastened or not as described in claims 3 and 4 of the present invention, in addition to the above-mentioned determination of whether a screw is fastened or not, it is possible to easily determine whether a screw is fastened or not by determining, for example, if the rotation amount of the electric motor is less than the target rotation amount (including the allowable range), whether the screw is galled, loose, or the selected screw shaft dimension is not suitable, and if the rotation amount of the electric motor is more than the target rotation amount (including the allowable range), whether the screw is stripped, wear of the pilot hole, cam-out of the screw, bit damage, or the selected screw shaft dimension is not suitable, etc. Therefore, according to the present invention, in addition to reducing the defect rate in the screw fastening work described above, it is also possible to easily detect and confirm human and physical work errors.

In particular, according to the electric motor drive control system for an electric rotating tool equipped with a control means having a function of determining whether the screw tightening state is good or bad as described in claim 5 of the present invention, when the control means determines that the screw tightening state is poor, an indicator is provided which generates a visually or audibly effective alarm as a means for displaying the determination result. By generating the alarm, the screw tightening worker can easily confirm that the screw tightening state during the work is abnormal and can reliably confirm that it is time to move on to the screw removal work, thereby achieving safe and quick screw tightening work.

According to the electric motor drive control system for an electric rotating tool equipped with a control means having a function of determining whether the screw tightening state is good or bad as described in claims 3 and 4 of the present invention, since the determination of the quality of the screw tightening state can be performed extremely easily and accurately as described above, the number of screws determined to be in a proper screw tightening state can be reliably recorded in the control unit, separately from the number of screws determined to be abnormal or defective, and by confirming or displaying the recorded number of screws, the efficiency and reliability of the screw tightening work can be improved. Also, as described above, when the screw tightening state is determined to be proper, the axial dimension of the screw tightened can be accurately recorded by the control means based on the amount of rotation detected during clutch operation, and the recorded contents can be easily displayed.

1 is an explanatory diagram showing a schematic configuration of one embodiment of an electric rotating tool having a function for determining whether a screw tightening state is good or bad, which constitutes an electric motor drive control system for an electric rotating tool according to the present invention, and showing its control system; FIG. 2 is a control system diagram of an electric rotating tool having a control means having a function of determining whether a screw fastening state is good or bad according to the present invention shown in FIG. 1 . FIG. 2 is a flowchart showing a screw tightening control program for explaining the relationship between the determination of the screw tightening state by the electric motor drive control system according to the present invention and the drive control of the electric motor in an electric rotating tool equipped with a control means having a function of determining whether the screw tightening state is good or bad as shown in FIG.

Next, an embodiment of an electric motor drive control system for an electric rotating tool according to the present invention will be described in detail below with reference to the accompanying drawings.

[ Example of the configuration of an electric rotating tool to which the present invention is applied ]
FIG. 1 is a schematic diagram illustrating a typical embodiment of an electric rotating tool equipped with a control means having a function of determining whether a screw tightening state is good or bad for implementing an electric motor drive control system according to the present invention.

In FIG. 1, reference numeral 10 denotes an electric rotary tool. The electric rotary tool 10 has a grip portion which incorporates therein an electric motor 12, a drive switch 13 for driving the electric motor 12, a reduction gear mechanism 16 which is connected to a drive output shaft (not shown) of the electric motor 12, and a clutch mechanism 18, and is configured to connect a driver bit 20 via the clutch mechanism 18.

The electric rotating tool 10 is provided with a switch operating member 14 for operating the drive switch 13 of the electric motor 12, an electric motor drive 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 drive control circuit 22 is provided with a rotation amount detection means 24 for detecting the rotation amount of the leading electric motor 12. Furthermore, a load current detection means 26 for detecting a load current obtained in the electric motor 12 based on the load torque (reaction force) applied to the driver bit 20 is appropriately provided.

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

In this embodiment, the rotation amount detection 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 poles of the rotor of the brushless motor is detected. In this case, the number of counted pulses detected by the rotation amount detection means 24 can be detected and recorded as an amount of rotation that correlates with the amount of screw tightening rotation during a screw tightening operation accompanied by the rotation of the driver bit 20.

Furthermore, a 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 a load current value in a 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 a screw tightening torque value during a screw tightening operation accompanied by the rotation of the driver bit 20.

The clutch mechanism 18 is configured, for example, by attaching a clutch plate to the output shaft of the reduction gear mechanism 16 and elastically engaging a clutch ball with this clutch plate in the axial direction, so that when a load torque (reaction force) of a certain level or more is applied to the output shaft via the driver bit 20 during screw tightening work, the clutch plate overcomes the clutch ball and the transmission of rotational driving force to the bit holder that engages and holds the driver bit 20 is interrupted, 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 when the clutch ball elastically engages with the clutch plate.

The clutch operation detection sensor 28 that detects the clutch operation of the clutch mechanism 18 can be constructed 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.

Therefore, in this embodiment, a control unit 30 is provided as a control means for judging whether the screw tightening state is good or bad, and in the CPU 32, a drive switch operation signal S13 obtained by operation of the drive switch 13 operated by the switch operation member 14 when starting a screw tightening operation is input to the electric motor drive control circuit 22 provided in the electric motor 12 in the electric rotating tool 10, and based on this drive switch operation signal S13, a motor drive control signal S22a is output that enables forward/reverse switching control of the electric motor to perform screw tightening and screw removal operations by driving the electric motor, and at the same time, this is input to the electric motor drive control circuit 22, thereby controlling the drive of the electric motor 12.

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.

As described 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.

The CPU 32 is set to detect the amount of rotation 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 acceptable range) described later, and the rotation amount Rt1 to be compared with this target rotation amount Rm±α.

Similarly to the 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 clutch operation time of the clutch mechanism 18, a load current value proportional to the screw tightening torque value is detected, and a target load current value Im±β (±β is an acceptable range) described below and a load current value It1 for comparison with this target load current value Im±β are detected and recorded.

As described 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 drive control circuit 22, so that stop control of the electric motor 12 is performed.

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 against the preset target rotation amount Rm±α, and/or when the load current value It1 detected at the clutch operation time t1 against the preset target load current value Im±β, the respective judgment contents are displayed on the display 40 as appropriate by any of the screw tightening judgment signals S40 output from the CPU 32.

Next, the basic control operations of the electric rotating tool having the control means with the function of determining whether the screw tightening state is good or bad, and the drive control system of the electric motor associated with the determination of the screw tightening state in the screw tightening work according to the present invention will be described based on a control system diagram of the control unit 30 and a flow chart showing the control operation program.

[ Control operation of an electric rotating tool equipped with a control means having a function of determining whether a screw fastening state is good or bad ]
FIG. 2 shows a control system of an electric rotating tool equipped with a control means having a function of determining whether a screw tightening state is good or bad, which is applicable to the electric motor control system of the present invention shown in FIG. 1, and FIG. 3 is a flowchart showing a control operation program of the control unit 30 of an electric rotating tool equipped with a control means having a function of determining whether a screw tightening state is good or bad, which is applicable to the present invention shown in FIG. 1.

2, in the control system of the control unit 30, 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 in which a control program is stored, and a RAM 60 as a storage means for storing detection data associated with the operation of the electric rotating tool 10 detected by the operation switch (encoder) 13, rotation amount detection means 24, and load current value detection means 26.

That is, the RAM 60 is provided with a screw tightening start point memory unit 61 which records and sets the screw tightening start point, a rotation amount memory unit 62 which 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 which records the load current value detected by the load current value detection means 26 and sets a target load current value.

Furthermore, an LCD 40a serving as a display device for providing external display 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 operating device as appropriate is also connected.

Next, as a specific example of the control operation of the electric rotating tool 10 according to the present invention, the content of the control operation shown in FIG. 3 will be described based on the configuration of FIG. 1 and the control system of the control unit 30 shown in FIG.

First, when driving the electric rotary tool 10 according to the present invention, the drive switch 13 is operated by operating the switch operating member 14, and the motor drive control signal S22a is input to the electric motor drive control circuit 22 to control the drive of the electric motor 12, and the drive of the electric screwdriver 10 is started (see Figs. 1 and 2). In this case, when the electric rotary tool 10 is used for the first time, it is necessary to previously carry out a standard torque adjustment for the clutch mechanism 18 in accordance with the standard of the screw used in the screw tightening work to be applied.

Therefore, when the electric rotating tool 10 of the present invention is used for the first time, as shown in Fig. 3, the first screw tightening operation is performed multiple times on a required screw tightening object, for example, multiple workpieces having the same structure with one or multiple screw tightening points (STEP-1). In this case, the screw tightening start time t0, which is the start time of driving the electric motor 12, is detected by the operation of the drive switch 13 provided on the electric rotating tool 10, and is recorded in the screw tightening start time storage unit 61 of the RAM 60 (see Fig. 2).

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 are detected, stored and calculated for the required work by the rotation amount detection means 24 and/or load current value detection means 26, respectively, for the common screw tightening point, and, provided that the multiple screw tightening states are all appropriate, these are recorded in the rotation amount memory unit 62 and/or the load current value memory unit 63 as the target rotation amount (including the tolerance range) and/or the target load current value (including the tolerance range) for the required screw tightening point (see Figures 2 and 3).

In this case, the rotation amount detection means 24 provided in the electric rotating 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 rotation amounts counted up to time t1 when the driver bit 20 tightens the screw and the clutch mechanism 18 performs the clutch operation are recorded in the rotation amount storage unit 62 of the RAM 60 (STEP-2).

Similarly to the rotation amount detection means 24 provided in the electric rotating tool 10, the load current detection means 26 provided in the electric rotating tool 10 starts to detect the load current It proportional to the screw tightening torque value of the electric motor 12 based on the load current detection signal S26 (STEP-1'). Then, the driver bit 20 tightens the screw, 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 storage section 63 of the RAM 60 (STEP-2').

In this way, provided that all of the screw tightening operations performed multiple times were performed properly, the target rotation amount Rm±α (±α is within the acceptable range) and/or the target load current value Im±β (±β is within the acceptable 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').

In this manner, in the electric rotating tool 10 applied to the practice of the present invention, the target rotation amount Rm±α (±α is an allowable range) is set, so that the required screw tightening work can be performed thereafter (STEP-4). Therefore, when the required screw tightening work is performed by the electric rotating tool 10 thereafter (STEP-4), the screw tightening rotation amount Rt1 counted from the screw tightening start time t0 to the time t1 at which 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.

In the electric rotating tool 10 applied to the practice of the present invention, the target load current value Im±β (including the allowable range) is set, so that the required screw tightening work can be performed thereafter (STEP-4'). Therefore, when the required screw tightening work is performed by the electric rotating 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 at which the clutch operation is performed by the clutch mechanism 18, as in the case described above, and recorded in the load current value storage unit 63 (STEP-5').

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 screw tightening state is determined to be good or bad based on the result of the comparison. 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 proper (STEP-7), and if the condition is not satisfied, the screw tightening state is determined to be bad or abnormal (STEP-8).

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 good or bad of the screw fastening 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 fastening state is determined to be proper (STEP-7'), and if the condition is not satisfied, the screw fastening state is determined to be defective or abnormal (STEP-8').

In addition, when the screw tightening operation using the electric rotating 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, an accurate rotation amount can be detected by detecting the rotation amount Rt of the electric motor 12 from when the driver bit 20 comes into contact with the object to which the screw is to be attached until the screw tightening work is actually performed.

Therefore, in the electric rotary tool 10 applied to the present invention, for example, as proposed by the applicant in Patent No. 4,721,535, the electric screwdriver 10 can be provided with a push-operated switch (not shown) 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 operation signal of this push-operated switch can be used to set the start time t0 of screw tightening when performing a screw tightening operation.

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, in the electric rotating tool 10 according to the present invention, the screw tightening judgment signal S40 outputted from the control unit 30 can be configured to appropriately display each judgment content on the LCD 40a as a display (see FIGS. 1 and 2).

[ Electric motor drive control system for electric rotating tool according to the present invention ]
Next, an embodiment will be described in which an electric motor drive control system for an electric rotating tool according to the present invention is constructed using an electric rotating tool 10 equipped with a control means having a function of determining whether a screw tightening state is good or bad, as configured as described above.

That is, as shown in Figures 3 and 2, by starting the required screw tightening operation (STEP-4 and/or STEP-4'), the screw tightening rotation amount Rt1 and/or the load current value It1 at the time of clutch operation are detected (STEP-5 and/or STEP-5') and are recorded in the rotation amount memory unit 62 and/or the load current value memory unit 53, respectively (STEP-6 and/or STEP-6').

Next, the rotation amount Rt1 and/or the load current value It1 stored in the rotation amount memory unit 62 and/or the load current value memory unit 53 are compared with the corresponding target rotation amount Rm±α (±α is an acceptable range) and/or target load current value Im±β (±β is an acceptable range) that have been recorded and set in advance (STEP-6 and/or STEP-6').

Then, in the rotation amount memory unit 62 and/or the load current value memory unit 53, if the detected rotation amount Rt1 and/or the load current value It1 match the corresponding target rotation amount Rm±α (±α is an allowable range) and/or the target load current value Im±β (±β is an allowable range), it is determined that the screw tightening state is proper, and an output signal for proper judgment (STEP-7 and/or STEP-7') is obtained.

However, if the detected rotation amount Rt1 and/or load current value It1 do not conform to the corresponding target rotation amount Rm±α (±α is an allowable range) and/or target load current value Im±β (±β is an allowable range) in the rotation amount memory unit 62 and/or load current value memory unit 53, it is determined that the screw tightening state is improper, and an output signal for screw tightening defect judgment (STEP-8 and/or STEP-8') is obtained.

Therefore, in the present invention, when an output signal of the above-mentioned screw tightening failure judgment (STEP-8 and/or STEP-8') is obtained, the forward/reverse rotation switching control mechanism of the electric motor drive control circuit 22 of the electric rotating tool 10 is controlled to switch from forward drive to reverse drive (STEP-9 and/or STEP-9'), thereby quickly and reliably removing the screw that has been judged to be screw tightening failure.

Therefore, according to the electric motor drive control system for the electric rotating tool of the present invention, if an operator makes a mistake in selecting the preset type of screw when performing a screw tightening operation, and the screw tightening condition is determined to be poor, the drive output shaft of the electric motor can be automatically and immediately switched from forward drive to reverse drive, thereby quickly and easily performing the screw removal operation, and then the appropriate type of screw can be selected again and the screw tightening operation can be performed again easily and reliably.

Furthermore, according to the electric motor drive control system for the electric rotating tool of the present invention, as described above, when it is confirmed that the judgment of the screw tightening condition is poor, the display 40 can be set to generate an effective alarm, for example visually or audibly, based on the judgment signal S40 of the judgment of the screw tightening condition in the electric rotating tool (see Figures 1 and 2).

Therefore, in this manner, when the judgment of the screw tightening condition results in a poor condition, an effective visual or audible alarm is generated to alert the screw tightening worker and enable him or her to easily confirm that the screw tightening condition is abnormal during the screw tightening operation, and also to reliably confirm that the screw removal operation should be moved on to, thereby achieving safe and quick screw tightening operation.

A preferred embodiment of the electric motor drive control system for an electric rotary tool equipped with a control means having a function of determining whether a screw is fastened properly, which is used in the present invention, has been described above, but a known rotary encoder can be used as the rotation amount detection means for 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.

Furthermore, in the present invention, by providing an encoder or the like to the electric motor 12, it is possible to detect when the rotation of the electric motor 12 has stopped due to the stall torque, which occurs when the rotation drive of the electric motor reaches the stall torque upon completion of screw tightening. 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 to detect the load current value of the electric motor 12.

Furthermore, in the present invention, when performing screw tightening work using the above-mentioned electric rotary tool, a facility can be provided which irradiates the workpieces positioned at predetermined positions from above, in accordance with a predetermined order of screw mounting positions corresponding to a common workpiece, with the required beam of light which sequentially specifies the screw mounting positions for screw tightening.

As is clear from the above explanation, the electric rotating tool applied to the present invention has the excellent effect of easily and reliably detecting human work errors such as making a mistake in the screw installation position corresponding to a predetermined common workpiece, or making a mistake in the selection of the type of screw specified for a specific screw installation position.

Furthermore, with the electric rotary tool having the above-described configuration applied to the present invention, when a predetermined number of screws are tightened sequentially during a required screw tightening operation, the quality of the tightening state of each screw as described above can be detected and recorded, and the number of tightened screws can also be detected and recorded all at once, making it possible to easily realize the construction of a production line that performs various screw tightening operations and a production management system for the network of these production lines.

In particular, according to the electric rotary tool applied to the present invention, in a required screw tightening operation, the rotation amount of the electric motor by the electric screwdriver is properly detected by utilizing the clutch mechanism, so that the proper screw tightening completion (screw seating) state can be easily and reliably determined, and each screw tightening state can be recorded or displayed in relation to the number of screws to be tightened continuously. Also, by detecting and recording the load current value of the electric motor at the time of clutch operation in each screw tightening operation, the load current value at the time of clutch operation can be confirmed in a very accurate correlation with the screw tightening torque value of each screw that has been tightened (seated). Therefore, by setting the detection of the rotation amount of the electric motor and the load current value of the electric motor to be detected, recorded or displayed in combination, it becomes possible to easily realize the construction of a production line performing various screw tightening operations and a production management system in the network thereof.

The above describes a preferred embodiment of the present invention in which a normal screw is used to control screw tightening on an object having a normal screw hole. However, the present invention is not limited to this embodiment and can be similarly applied to, for example, screw tightening control using tapping screws or drill screws, or to electric rotary tools that perform screw processing using taps.

REFERENCE SIGNS LIST 10 Electric rotating tool 12 Electric motor 13 Drive switch 14 Switch operation member 16 Speed reduction mechanism 18 Clutch mechanism 20 Driver bit 22 Electric motor drive 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 point storage section 62 Rotation amount storage section 63 Load current value storage section 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 state determination signal Rm±α Target rotation amount (including allowable 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: Rotation amount at clutch operation It1: Load current detection value at clutch operation

Claims (5)

The electric rotating tool is configured to perform a required screw tightening operation on a predetermined screw-attaching object, and is equipped with a control means having a function of determining whether the screw is in a good or bad state after the screw tightening operation is completed,
an electric motor drive control system for an electric rotating tool, characterized in that an automatic reverse drive control mechanism is provided in an electric motor drive circuit, which is configured to automatically switch the drive of the electric motor of the electric rotating tool from forward drive to reverse drive immediately to continuously perform screw removal work when the control means having a function of determining whether the screw fastening state is good or bad during the process of performing a required screw fastening operation on a specified screw-fastening object using the electric rotating tool determines that the screw fastening state is bad. 2. The electric motor drive control system for an electric rotating tool according to claim 1, further comprising:
the screw tightening state determining device includes 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 having a screw tightening state determining function via a reduction mechanism and a clutch mechanism, and further includes 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 drive control circuit for controlling 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,
In the rotation amount storage means and/or the load current value storage means, the target rotation amount (including a tolerance range) and/or the target load current value (including a tolerance range) are set for the rotation amount and/or the 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 accompanying the completion of screw tightening,
The electric motor drive control system for an electric rotating tool is characterized in that the electric rotating tool is equipped with a screw tightening state determination function, in which when 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 are sequentially detected by the rotation amount detection means and/or the load current value detection means, they are recorded in the rotation amount memory means and/or the load current value memory means, and the detected rotation amount and/or load current value are compared with the set target rotation amount (including an allowable range) and/or target load current value (including an allowable range) to determine whether the screw tightening state is good or bad. 3. An electric motor drive control system for an electric rotating tool, comprising: an electric rotating tool control means having a function of determining whether the screw tightening state is good or bad, comprising: a control means for determining and recording or displaying the screw tightening state as being proper when 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, is determined to match a set target rotation amount (including an acceptable range); and/or when 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, is determined to match a set target load current value (including an acceptable range). An electric motor drive control system for an electric rotating tool, comprising a control means having a function of determining whether the screw tightening state is good or bad as described in claim 2, wherein the control means is configured to determine and record or display the screw tightening state as poor when 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 a set target rotation amount (including an acceptable range), and/or when 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 a set target load current value (including an acceptable range). 5. The electric motor drive control system for an electric rotating tool according to claim 1, 2 or 4, further comprising an indicator configured to generate an effective visual or audible alarm when the control means having a function of determining whether the screw tightening state is poor is provided.

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