JP2012066358A - Electric screwdriver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric screwdriver, capable of preventing deterioration in workability, and capable of efficiently preventing the occurrence of fastening failure, while suppressing increase in costs and size thereof.SOLUTION: A plurality of types of reverse modes as the rotation modes for once rotating an output shaft 6 to the opposite side upon the start of the rotation are stored in the electric screwdriver, and one of the plurality of types of reverse modes is set in accordance with the operation condition. When an operator instructs the start of the rotation by a trigger switch 9, a control circuit 13 first rotates the output shaft 6 by a prescribed angle in a reverse side in the set reverse mode, and thereafter rotates the output shaft 6 in a screw fastening direction.

Description

  The present invention relates to an electric screw tightening tool capable of performing a screw tightening operation.

  When tightening a screw member such as a bolt using an electric screw tightening tool such as an electric screwdriver, if the screw member is rotated in a posture that does not properly engage with the screw hole to be tightened, the screw member is caught. There is a problem that a poor fastening occurs.

  On the other hand, in the electric screw tightening tool described in Patent Document 1, by rotating the output shaft once to the opposite side (hereinafter referred to as “inversion”) at the start of rotation, the screw member is brought into an appropriate posture, After that, the output shaft is rotated forward so that the screw tightening operation is performed. In this electric screw tightening tool, the output shaft is reversed when the pull-in amount of the trigger switch is within a small range, and the output shaft is rotated forward when the pull-in amount exceeds a certain range. .

  In other words, the configuration is such that the operator attempts to adjust the reversal of the output shaft by adjusting the pull-in amount of the trigger switch.

JP 02-224934 A

  In the electric screw tightening tool described in Patent Document 1, when the output shaft is once reversed, the operator himself / herself needs to finely adjust the pull-in method of the trigger switch according to the type of the screw member and the target to be tightened. There is. Therefore, particularly when many screw tightening operations are executed continuously, there is a problem that the work efficiency is lowered.

  On the other hand, for example, a sensor that detects that the screw member is in an appropriate posture may be provided, and the output shaft may be automatically reversed until the sensor detects the proper posture. However, in that case, since it is necessary to install a dedicated sensor on the tool itself, the cost and size of the tool are increased.

  The present invention has been invented in view of the above-mentioned problems, and is effective in preventing the occurrence of poor fastening while suppressing deterioration in workability and suppressing the increase in cost and size of the tool. It is an object of the present invention to provide an electric screw tightening tool that can be restrained automatically.

  In order to solve the above-mentioned problems, the electric screw tightening tool of the present invention has the following configuration.

  The electric screw tightening tool of the present invention includes a motor, an output shaft that is rotated by the motor and performs a screw tightening operation, a control circuit that controls rotation driving of the output shaft by the motor, and rotation start of the output shaft. An electric screw tightening tool that includes a trigger switch for commanding and that once rotates the output shaft to the opposite side when the rotation is started. The electric screw tightening tool according to the present invention includes a memory unit that stores a plurality of types of reversal modes as a rotation mode that once rotates the output shaft to the opposite side when the rotation is started, and one of a plurality of types of the reversal modes. And a mode setting unit for setting. Then, when the rotation start is instructed by the trigger switch, the control circuit rotates the output shaft to the opposite side by a predetermined rotation angle in the set reverse mode, and then the output shaft is screwed. It is provided to rotate in the direction.

  In the electric screw tightening tool of the present invention, it is preferable that the reversal modes stored in the memory unit include a plurality of types with different rotation angles and a plurality of types with different rotation speeds.

  Moreover, it is also preferable that the mode setting unit sets the reverse mode by wireless communication.

  It is also preferable that a changeover switch for switching between a screw tightening operation and a screw loosening operation is provided, and that the control circuit is provided so as not to perform reversal at the time of rotation start when switching to the screw loosening operation.

  The present invention has an effect that it is possible to effectively suppress the occurrence of a fastening failure while suppressing a decrease in workability and suppressing an increase in cost and size of a tool.

An electric screw fastening tool of an example in an embodiment of the present invention is shown roughly, (a) is a side view for explanation of the whole tool, and (b) is a principal part front view. It is a block diagram which shows the electrical structure of the electric screw fastening tool same as the above. It is a circuit block diagram of the drive circuit and motor of an electric screw fastening tool same as the above. It is a control flow figure of an electric screw fastening tool same as the above. It is a block diagram which shows the electric constitution of the electric screw fastening tool of the other example in embodiment of this invention.

  The present invention will be described based on embodiments shown in the accompanying drawings. 1 to 4 show an example of an electric screw tightening tool according to an embodiment of the present invention.

  The electric screw tightening tool of this example is a portable electric driver as shown in FIG. 1A, and a power source unit 2 which is a rechargeable battery pack is detachably attached to a tool body 1. . The tool body 1 includes a cylinder portion 3 provided with a motor 5 and an output shaft 6 that is driven to rotate by this, and a handle portion 4 that extends from the outer peripheral surface of the cylinder portion 3. Part 2 is attached.

  In the cylinder portion 3, a motor 5 capable of forward / reverse rotation, a drive portion 7 including a speed reduction mechanism that transmits the rotation of the motor 5, and an output shaft that is rotationally driven by the motor 5 via the drive portion 7. 6 and a rotation detector 8 that detects the rotation of the motor 5 are arranged on a straight line. The output shaft 6 has a tip portion protruding from an opening of the cylindrical portion 3, and a tip tool 50 for screw tightening is attached to the tip portion.

  The handle portion 4 is a portion that an operator holds with one hand, and a trigger switch 9 and a changeover switch 10 are provided at the base portion. The trigger switch 9 is a switch that controls the on / off of the motor 5 and the rotation speed (that is, the rotation speed of the output shaft 6 and the like) according to the pull-in amount, and the changeover switch 10 is a screw tightening operation and a screw loosening operation (that is, output). It is a switch for switching the rotation direction of the shaft 6.

  A mode setting unit 11 for setting a reverse mode at the time of activation and a display unit 12 for displaying the setting contents are provided on the front portion of the handle unit 4 so as to be visible from the outside. The handle portion 4 accommodates a control circuit 13 composed of a microcomputer. The control circuit 13 is electrically connected to a rotation detection unit 8, a trigger switch 9, a changeover switch 10, a mode setting unit 11, a display unit 12, and the like.

  As shown in FIG. 1B, the mode setting unit 11 and the display unit 12 are arranged adjacent to each other, and the mode setting unit 11 is provided with a mode selection button 15. The display unit 12 is provided so as to display the set mode as a number. If the operator presses the mode selection button 15 marked “△”, the numbers on the display unit 12 increase as 1, 2, 3,..., And if the mode selection button 15 marked “▽” is pressed, The numbers on the display unit 12 decrease in order.

  FIG. 2 shows an electrical configuration of the electric screw tightening tool of this example. As shown in the figure, the control circuit 13 is connected to a memory unit 16 composed of a storage element. The memory unit 16 stores a plurality of types of reversal modes as rotation modes for reversing the output shaft 6 once at the start of rotation. The stored inversion modes have different rotation angles and rotation speeds. The control circuit 13 is connected to a drive circuit 17 that rotates the motor 5.

  FIG. 3 shows a circuit configuration of the drive circuit 17 and the motor 5. The motor 5 is a three-phase brushless motor having motor coils 20, 21, and 22, and after the DC voltage supplied from the power supply unit 2 is converted into three-phase drive power via the drive circuit 17, It is supplied to each motor coil 20, 21, 22.

  The drive circuit 17 has six switching elements 23, 24, 25, 26, 27, and 28 made of FETs. The group of switching elements 23 and 24, the group of switching elements 25 and 26, and the group of switching elements 27 and 28 are elements in which the elements are connected in series, and these groups are further connected in parallel. I am letting. The intermediate point of the switching elements 23 and 24 and the motor coil 20 are connected via the connection terminal 30. Further, the intermediate point of the switching elements 25 and 26 and the motor coil 21 are connected via the connection terminal 31, and the intermediate point of the switching elements 27 and 28 and the motor coil 22 are connected via the connection terminal 32.

  The gate terminals of the switching elements 23, 24, 25, 26, 27, 28 are turned on / off by a signal from the control circuit 13. By turning these gate terminals on and off, the DC voltage from the drive unit 7 is appropriately converted into three-phase drive power and then supplied to the motor coils 20, 21, 22 to drive the motor 5 in a desired rotational direction. . That is, the control circuit 13 can control the on / off of the motor 5 and its rotation direction and rotation speed.

  In the following, a screw tightening operation performed using the electric screw tightening tool of this example will be described.

  In the electric screw tightening tool of this example, the operator can select an appropriate inversion mode by operating the button on the mode setting unit 11. As the reversal mode, a plurality of types having different rotation angles and rotation speeds are stored in the memory unit 16 in advance, so that it is optimal for bringing the screw member to an appropriate posture with respect to the screw hole. May be selected as appropriate according to the work situation. The working conditions here include, for example, the type, dimension, shape, hardness, dirt, and thread burr of the screw member, the type, dimension, shape, hardness, dirt, thread burr, and coating film of the screw member to be tightened. Thickness, how the operator presses, the posture of the worker, and the like.

  After completing the setting of the reverse mode, the operator grasps the handle portion 4 of the electric screw tightening tool and presses the screw member against the tip portion of the tip tool 50 attached to the output shaft 6. When the trigger switch 9 is pulled in here, the control circuit 13 controls the rotation drive of the motor 5 so that the output shaft 6 rotates in the set reverse mode. The rotation direction of the output shaft 6 at this time is a rotation direction B opposite to the rotation direction A for screw tightening (see FIG. 1).

  When the control circuit 13 rotates the output shaft 6 in the rotation direction B at a predetermined rotation speed by a predetermined rotation angle (for example, 90 °, 180 °, etc.) set in the reversal mode, the output shaft 6 is then rotated in the rotation direction. Rotate to A. The rotational drive of the output shaft 6 in the rotational direction A is performed at a rotational speed corresponding to the pulling amount of the trigger switch 9.

  The set reversal mode is saved until the next work, but if the work situation or the like changes, the mode setting unit 11 is operated to change the reversal mode, and the rotation angle and rotation speed at the time of reversal are changed. Change to something appropriate for your situation. For example, if the screw member or the object to be tightened has a lot of burrs and dirt, set the rotation angle and rotation speed to a larger value, and reliably remove burrs and dirt by the cleaning effect during reversal. It should be set so that it can. Further, when the tightening target is, for example, a painted nut or the like, it is preferable to set the rotation angle and the rotation speed according to the thickness of the coating film so that an unnecessary coating film is eliminated during reversal.

  By the way, in the state where unnecessary burrs, dirt, a coating film, and the like exist, these can rattle the screw member, so that the posture in which the screw member does not engage properly is likely. Therefore, by setting the rotation angle and rotation speed according to the amount of burrs, dirt, coating film, etc., and setting so that the cleaning effect at the time of reversal is exhibited as much as possible, the fastening failure can be further suppressed.

  Further, for example, when the screw member is a double screw, the screw member can be brought into an appropriate posture by reversing the rotation angle that is smaller than that of the single screw. Therefore, when the screw member is changed from a single thread to a double thread, the working time can be shortened by setting a smaller rotation angle.

  In addition, the reversal mode can be used properly according to various factors such as various work situations, the preference of the worker, certainty and efficiency required for the work, and the like. And since the rotation control of the output shaft 6 in each reversal mode is automatically performed according to the setting, the work efficiency is reduced even when many screw tightening operations are executed continuously. Absent.

  FIG. 4 shows a control flow of the electric screw tightening tool of this example. As shown in the figure, in the case of screw tightening work (in the case of forward / reverse signal = forward rotation), as described above, after the output shaft 6 is once reversed by the set rotation angle, the output shaft 6 is rotated forward. .

  On the other hand, when the screw loosening operation is selected by operating the changeover switch 10 (forward / reverse signal ≠ forward rotation), the control circuit 13 performs the reversing operation at the time of starting rotation as in the case of the screw tightening operation. It is provided not to execute. In other words, in the case of the screw loosening operation, the output shaft 6 is set to rotate only in the rotational direction for screw tightening (rotational direction B in FIG. 1) from the beginning to the end when the trigger switch 9 is pulled. Yes.

  As described above, the electric screw tightening tool of this example includes the motor 5, the output shaft 6 that is rotated by the motor 5 to perform screw tightening, and the control circuit 13 that controls the rotational drive of the output shaft 6 by the motor 5. And a trigger switch 9 for instructing rotation start of the output shaft 6, and temporarily rotates the output shaft 6 to the opposite side at the time of rotation start. Furthermore, the electric screw tightening tool of the present example includes a memory unit 16 that stores a plurality of types of reversal modes as a rotation mode that once rotates the output shaft 6 to the opposite side at the time of starting rotation, and one of a plurality of types of reversal modes. And a mode setting unit 11 for setting one. Then, when the rotation start is instructed by the trigger switch 9, the control circuit 13 rotates the output shaft 6 to the opposite side by a predetermined rotation angle in the set reverse mode, and then the output shaft 6 in the screw tightening direction. It is provided to rotate.

  Therefore, according to the electric screw tightening tool of this example, even if the operator himself / herself does not adjust the pull-in amount of the trigger switch 9 every time work is performed, the output shaft 6 is automatically reversed once and the fastening failure is caused. Can be suppressed. Therefore, even when many screw tightening operations are executed continuously, a decrease in work efficiency can be suppressed. In addition, since it is not necessary to provide a dedicated sensor or the like for this purpose, the cost and size of the tool can be suppressed. As the reverse mode, an appropriate mode can be set according to the work situation and the like, and the occurrence of fastening failure is more effectively suppressed by mode selection.

  Moreover, in the electric screw tightening tool of this example, the reversal modes stored in the memory unit 16 include a plurality of types with different rotation angles. As a result, the rotation angle that is considered to be most suitable as the rotation angle at the time of reversal can be set according to the work situation, and the occurrence of poor fastening is more effectively suppressed.

  Further, in the electric screw tightening tool of this example, the reversal modes stored in the memory unit 16 include a plurality of types having different rotational speeds. As a result, the rotation speed at the time of reversal that is considered to be most appropriate can be set according to the work situation, and the occurrence of poor fastening is more effectively suppressed.

  In addition, the electric screw tightening tool of this example includes a changeover switch 10 for switching between screw tightening work and screw loosening work, and the control circuit 13 does not perform reversal at the time of rotation start when switching to screw loosening work. Provided. Accordingly, it is possible to perform a screw loosening operation, and at this time, since the reversal at the time of activation is not executed, the screw member or the like can be prevented from being damaged, and the working efficiency can be improved.

  Next, another example of the electric screw tightening tool according to the embodiment of the present invention will be described with reference to FIG. Since the basic configuration of this example is the same as that of the example, only the characteristic configuration different from the example will be described below.

  In the electric screw tightening tool of this example, the mode setting unit 11 includes a remote control operation unit 40 that transmits a radio signal and a reception unit 41 that receives a radio signal from the remote control operation unit 40. The remote control operation unit 40 can perform button operations similar to the mode selection button 15 in the example, and transmits the operation contents as a radio signal. The receiving unit 41 is connected to the control circuit 13 and inputs the received radio signal to the control circuit 13.

  Thus, the mode setting unit 11 of this example sets the reverse mode by wireless communication. Therefore, in a work environment such as a factory line where a large number of workers each use an electric screw tightening tool, the reversal modes of the large number of electric screw tightening tools can be collectively managed wirelessly.

  Although the present invention has been described based on the embodiments shown in the accompanying drawings, the present invention is not limited to the above-described embodiments, and appropriate design changes may be made within the intended scope of the present invention. Is possible.

5 Motor 6 Output shaft 9 Trigger switch 10 Changeover switch 11 Mode setting unit 13 Control circuit 16 Memory unit

Claims (5)

  A motor, an output shaft that is rotated by the motor and performs a screw tightening operation, a control circuit that controls rotational driving of the output shaft by the motor, and a trigger switch that commands rotation start of the output shaft, An electric screw tightening tool that once rotates the output shaft to the opposite side when the rotation is started, and a memory that stores a plurality of reversal modes as a rotation mode that temporarily rotates the output shaft to the opposite side when the rotation is started And a mode setting unit for setting one of the plurality of types of inversion modes, and when the rotation start is instructed by the trigger switch, the control circuit outputs the output in the set inversion mode. Electric screw tightening characterized in that the shaft is rotated to the opposite side by a predetermined rotation angle, and then the output shaft is rotated in the screw tightening direction. Ingredients.   The electric screw tightening tool according to claim 1, wherein the reversal mode stored in the memory unit includes a plurality of types having different rotation angles.   3. The electric screw tightening tool according to claim 1, wherein the reversal modes stored in the memory unit include a plurality of types having different rotational speeds.   The said mode setting part sets the said inversion mode by radio | wireless communication, The electric screw fastening tool as described in any one of Claims 1-3 characterized by the above-mentioned.   2. The switch according to claim 1, further comprising a changeover switch for switching between a screw tightening operation and a screw loosening operation, wherein the control circuit is provided so as not to perform reversal at the time of starting the rotation when switching to the screw loosening operation. Electric screw tightening tool as described in any one of -4.

Images