Electric driver device

Abstract

To enable smooth operation of tightening or loosening a screw.SOLUTION: An electric driver device 1 comprises: a driver motor 311 that tightens or loosens a screw by causing an output shaft 312 to rotate; a pressing-force shaft 413 that is disposed on a line of extension of a rotational centerline of the output shaft 312; and a pressing-force motor 411 that imparts, to the pressing-force shaft 413, the force for pressing the driver motor 311 in a direction along the rotational centerline.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an electric driver device.

Background Art

[0002] As a device for tightening or loosening a screw on a workpiece, a device as shown in Patent Document 1 is known. Patent Document 1 describes a screw loosening device configured to linearly drive an electric driver unit provided with a rotary drive motor in the vertical direction by a lifting motor. Further, it is described that a driver bit connected to the output shaft of the rotary drive motor is pressed downward by a spring.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the screw loosening device described in Patent Document 1, it is possible to loosen the screw while pressing the screw using a spring and a lifting motor. However, in the pressing by the spring, it is difficult to adjust the pressing force according to the type of the screw or the like. Further, in the pressing by the lifting motor, since the pressing force is applied from a position on the side of the electric driver unit, an oblique pressing force with respect to the axial direction of the screw or the output shaft of the rotary drive motor is inevitably applied. As a result, an unexpected load is applied to the screw or the thread, and there is a risk of screw collapse or other abnormalities. In particular, when the size of the screw is minute or when it is made of a material that is easily deformed, such problems are likely to become apparent.

[0005] An object of the present invention is to provide an electric driver device capable of smoothly tightening or loosening a screw.

Means for Solving the Problems

[0006] The present invention provides, as a first aspect, an electric driver device including a motor for a driver that performs screwing or unscrewing by rotating an output shaft, a pressing shaft disposed on an extension line of the rotation center line of the output shaft, and a pressing motor that applies a force for pressing the driver motor in a direction along the rotation center line with respect to the pressing shaft.

[0007] According to the electric driver device of the first aspect, since the pressing shaft is disposed on the extension line of the rotation center line of the output shaft of the motor for the driver, a pressing force can be applied to a screw to be screwed or unscrewed by the output shaft of the motor for the driver also in the direction of the center line, and screwing or unscrewing can be performed smoothly.

[0008] In the electric driver device of the first aspect, a configuration may be adopted as a second aspect in which the pressing shaft is connected to the output shaft of the pressing motor, and the pressing shaft can move straight in a direction along the rotation center axis by rotation of the output shaft by driving of the pressing motor. According to the electric driver device of the second aspect, the rotational driving force by the pressing motor can be made to act as a pressing force on the motor for the driver.

[0009] In the electric driver device of the first or second aspect, a configuration may be adopted as a third aspect in which a driver bit is connected to the output shaft of the motor for the driver, and the pressing motor is disposed on the extension line of the rotation center line at a position on the side opposite to the side where the driver bit is connected with respect to the motor for the driver. According to the electric driver device of the third aspect, the motor for the driver and the pressing motor can be disposed in a straight line, and the installation space in the width direction can be reduced.

[0010] In the electric driver device according to any one of the first to third aspects, a first circuit board provided with a circuit for driving the driver motor, a second circuit board provided with a circuit for driving the pressing motor, and a cable connecting the first circuit board and the second circuit board are provided. The first circuit board moves relative to the second circuit board along the rotation center line direction by driving the pressing motor. A first connector for connecting one end side of the cable to the first circuit board is provided at a position near the side of the first circuit board opposite to the side facing the second circuit board. A second connector for connecting the other end side of the cable to the second circuit board is provided at a position near the side of the second circuit board opposite to the side facing the first circuit board. Such a configuration may be adopted as a fourth aspect.

[0011] According to the electric driver device of the fourth aspect, the bending of the cable due to the movement of the first circuit board can be reduced, and the deterioration and damage of the cable, the first connector, and the second connector can be reduced.

[0012] In the electric driver device according to any one of the first to fourth aspects, a case member for housing the driver motor is provided. The case member can remove the driver motor and house another driver motor. When the other driver motor is attached, the position of the output shaft does not change compared to the case when the driver motor is attached. Such a configuration may be adopted as a fifth aspect.

[0013] According to the electric driver device of the fifth aspect, even when the driver motor is replaced with another driver motor of a different size, the position of the output shaft does not change, so the position of the driver bit also does not change. Therefore, when the electric driver device is attached to a robot arm, it is not necessary to perform readjustment associated with the replacement of the driver motor.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an electric driver device 1 according to an embodiment of the present invention will be described. Figure 1 is a diagram showing the appearance of the electric driver device 1. The electric driver device 1 is composed of a controller 11 and an electric driver unit 12. The communication line 110 connects the controller 11 and the electric driver unit 12 and is used for data communication between the two. The electric driver unit 12 is composed of a base portion 21, a driver portion 31 attached on the base portion 21, and a pressing portion 41. The driver bit 51 is connected to the driver portion 31, and a screw is engaged with the tip portion, and it is used for the operations of tightening and loosening the screw.

[0016] Figure 2 is a diagram showing the appearance of the electric driver unit 12. Figure 2(A) is a perspective view, and Figure 2(B) is a side view. The base portion 21 is composed of a rectangular plate-like member and has support portions 212, 213, 214, 215 provided to protrude from the plate-like member. Along the longitudinal direction of the base portion 21, the driver portion 31 and the pressing portion 41 are provided.

[0017] The driver portion 31 is provided between the support portion 212 and the support portion 213, and a driver motor (described later) is provided inside the case member constituting the driver portion 31. The driver bit 51 is connected to the tip side of the output shaft 312 of the driver motor. The pressing portion 41 is provided at a position on the opposite side of the driver portion 31 from the side where the driver bit 51 is connected, and is provided between the support portion 214 and the support portion 215. The pressing portion 41 has a pressing motor (described later) inside the case member constituting the pressing portion 41. The output shaft 412 of the pressing motor in the pressing portion 41 is engaged with the pressing shaft 413.

[0018] A circuit board 315 is attached to the upper surface (the surface opposite to the base portion 21 side) of the driver portion 31. A circuit board 415 is attached so as to span the upper surfaces of the support portion 213 and the support portion 214. The circuit boards 315 and 415 will be described later.

[0019] Figure 3 is a diagram schematically showing the configuration of the electric driver unit 12. In this embodiment, the driver motor 311 provided inside the driver unit 31 is a stepping motor. Also, the pressing motor 411 provided inside the pressing unit 41 is a stepping motor in this embodiment.

[0020] The output shaft 312 of the driver motor 311 penetrates through the case member of the driver unit 31 and the openings provided in the support portion 212, and a driver bit 51 is connected to the tip of the output shaft 312. The driver bit 51 is replaceable with another driver bit according to the type of screw to be tightened or loosened. When the driver motor 311 is driven, the output shaft 312 rotates, and the driver bit 51 connected to the output shaft 312 also rotates. By the rotation of the driver bit 51, the screw engaged with the tip of the driver bit 51 rotates, enabling screw tightening and loosening of the workpiece.

[0021] The output shaft 412 of the pressing motor 411 in the pressing unit 41 penetrates through the case member of the pressing unit 41 and the openings provided in the support portion 214, and the tip side of the output shaft 412 is engaged with the pressing shaft 413. The pressing shaft 413 penetrates through the opening of the support portion 213, and the tip portion is connected to the driver unit 31.

[0022] The engagement portion between the output shaft 412 and the pressing shaft 413 constitutes a ball screw. When the output shaft 412 rotates due to the drive of the pressing motor 411, the rotational motion is converted into a linear motion by the ball screw, and the pressing shaft 413 moves linearly in the direction of arrow M in FIG. 3. Due to the linear movement of the pressing shaft 413, the connected driver unit 31 moves linearly in the direction of arrow M. The case member constituting the driver unit 31 is configured to be movable, for example, along a guide rail formed in the direction of arrow M on the base portion 21 so that linear movement is possible. When the driver unit 31 moves linearly, the driver motor 311, the output shaft 312, and the driver bit 51 move linearly integrally with the driver unit 31.

[0023] In this embodiment, as will be described later, when driving the driver motor 311 to tighten or loosen a screw on a workpiece, a pressing force is applied by driving the pressing motor 411 to press the driver unit 31 in the direction of arrow P, which is the pressing direction, against the pressing shaft 413, and the operation is basically performed with the driver unit 31 being pressed.

[0024] In FIG. 3, the center line C is drawn by extending the rotation center axis of the output shaft 312 of the driver motor 311. In this embodiment, the center line of the driver bit 51, the center line of the pressing shaft 413, and the rotation center line of the output shaft 412 of the pressing motor 411 coincide with the center line C.

[0025] Since the rotation center line of the output shaft 312 of the driver motor 311 (or the center line of the driver bit 51) coincides with the center line of the pressing shaft 413, the pressing force is applied only in the direction of the center line of the output shaft 312 without applying an oblique pressing force to the output shaft 312. Thereby, a force can be applied to press or pull out the screw parallel to the depth direction of the screw hole. Therefore, unnecessary loads applied to the screw and the screw hole can be reduced. As a result, the risk of causing abnormalities such as screw and thread collapse is reduced. In particular, when the size of the screw is extremely small or the material of the screw and the screw hole is easily deformed, it is important how much force can be applied to the screw to push it in (or pull it out) parallel to the depth direction of the screw hole. According to this embodiment, even in such a case, screw tightening and loosening can be performed smoothly.

[0026] Also, the screw hole is not necessarily formed in the vertical direction. According to this embodiment, since a pressing force can be accurately applied to the screw parallel to the depth direction of the screw hole, smooth screw tightening and loosening can be achieved even when the tightening or pulling-out direction is different from the gravitational direction.

[0027] Note that the center of the pressing shaft 413 does not necessarily have to exactly coincide with the center line C (the central axis of the output shaft 312). However, from the perspective of applying a force that is as parallel as possible to the output shaft 312 in the axial direction, it is preferable to provide the pressing shaft 413 at a position such that the center line C passes through the inside of the pressing shaft 413.

[0028] FIG. 4 is a block diagram showing the configuration of the electric driver device 1. The electric driver unit 12 includes a driver motor 311, a pressing motor 411, an encoder 421, and an input / output control circuit 121. The encoder 421 is provided in the pressing unit 41 and detects the rotational position of the rotor of the pressing motor 411 (that is, the rotational position of the output shaft 412).

[0029] The input / output control circuit 121 communicates with the controller 11 via the communication line 110. Further, the input / output control circuit 121 outputs a drive signal and a stop signal to the driver motor 311 and the pressing motor 411 in response to a signal from the controller 11. Also, the input / output control circuit 121 inputs a detection signal from the encoder 421 and transmits the rotational position information of the pressing motor 411 to the controller 11. Based on this rotational position information, the position of the driver bit 51 is detected in the controller 11. Also, the input / output control circuit 121 monitors the output current of the driver motor 311 and transmits the current value information to the controller 11. Based on this current value information, the torque of the driver motor is detected in the controller 11.

[0030] Specifically, the input / output control circuit 121 is provided in the electric driver unit 12 as the circuit board 315 and the circuit board 415 in FIG. 2. Among the configurations of the input / output control circuit 121, the configuration related to the input / output of signals to the driver motor 311 is provided on the circuit board 315, and the configuration related to the input / output of signals to the pressing motor 411 and the encoder 421 is provided on the circuit board 415.

[0031] The controller 11 is composed of a processor, a memory, a keyboard, a display, etc. The controller 11 shown in FIG. 4 shows a functional configuration realized by those hardware configurations of the computer. The functional configuration of the controller 11 will be described below.

[0032] The motor control unit 111 for the driver of the controller 11 outputs a drive signal and a stop signal to control the drive and stop of the driver motor 311 with respect to the electric driver unit 12. The motor control unit 112 for pressing outputs a drive signal and a stop signal to control the drive and stop of the pressing motor 411 with respect to the electric driver unit 12.

[0033] The driver bit position detection unit 113 acquires the rotation position information of the pressing motor 411 from the electric driver unit 12 (based on the detection result of the encoder 421) and detects the current position in the direction along the center line C of the driver bit 51. The position of the driver bit 51 changes together with the position of the driver unit 31 (the position in the direction along the center line C in FIG. 3). Taking a position where the driver unit 31 has moved to the pressing unit 41 side as the initial position, the position (the position of the tip) of the driver bit 51 is calculated based on the moving amount in the straight-ahead direction (M direction, that is, the direction along the center line C) from the initial position. That is, if the moving amount of the pressing shaft 413 in the straight-ahead direction per rotation of the output shaft 412 by the pressing motor 411 is known, the position of the driver bit 51 can be calculated based on the rotation position information of the pressing motor 411 by the encoder 421 (including information on the number of rotations from the initial position). The driver bit position detection unit 113 outputs the calculated position information of the driver bit 51 to the arithmetic unit 115.

[0034] The torque detection unit 114 acquires the output current value information of the driver motor 311 from the electric driver unit 12 and estimates the torque value of the driver motor 311. Since the output current value increases as the output torque of the driver motor 311 increases, the estimation of the output torque is possible. The torque detection unit 114 outputs the estimated torque value information to the arithmetic unit 115.

[0035] The calculation unit 115 acquires the position information of the driver bit 51 from the driver bit position detection unit 113 and the torque value information from the torque detection unit 114, determines whether to start, stop, or change the driving state of each of the driver motor 311 and the pressing motor 411, and outputs an instruction signal to the driver motor control unit 111 and the pressing motor control unit 112.

[0036] The storage unit 116 stores information for calculating, estimating values, and determining the necessity of operations by the driver bit position detection unit 113, the torque detection unit 114, and the calculation unit 115. For example, the storage unit 116 stores information such as the rotational position of the pressing motor 411 at the initial position, which is necessary information for the driver bit position detection unit 113 to calculate the position of the driver bit 51, and the amount of movement of the pressing shaft 413 in the straight-ahead direction per rotation of the output shaft 412 by the pressing motor 411. Further, the storage unit 116 stores coefficients and the like for estimating the torque value from the output current value in the torque detection unit 114. Also, the storage unit 116 stores various information for the calculation unit 115 to determine the drive control of the driver motor 311 and the pressing motor 411. For example, it stores threshold information for determining the completion of screw tightening based on the torque value, and information on predetermined positions for determining the start and completion of screw tightening and loosening based on the position of the driver bit 51.

[0037] The input unit 117 is a device operable by a user for input operations, such as a keyboard and a mouse, and the user can input information to be stored in the storage unit 116. The display unit 118 is a display device, and displays the operation status by the input unit 117, the state of the electric driver unit 12, etc. so that the user can visually recognize them.

[0038] FIG. 5 is a diagram for explaining the screw tightening operation using the electric driver device 1, and FIG. 6 is a diagram showing the control flow during the screw tightening operation using the electric driver device 1. The operations described below are realized by a program for realizing the operations shown in the flowchart of FIG. 6 being stored in the memory of the computer that constitutes the controller 11, and the processor of the computer reads and executes the program. Before starting the screw tightening operation, the pressing motor control unit 112 of the controller 11 outputs a drive start signal to start driving the pressing motor 411 in the electric driver unit 12, and moves the driver unit 31 straight to move it to the initial position.

[0039] The initial position may be the side where the driver unit 31 is closest to the pressing unit 41 within the movable range. For example, when the driver unit 31 reaches the end on the side close to the pressing unit 41 in the moving range, it can no longer move, so the rotational position information detected by the encoder 421 does not change, and it can be detected by the driver bit position detection unit 113 that the end has been reached. The position information detected by the driver bit position detection unit 113 in the state of being in such an initial position is stored in the storage unit 116.

[0040] FIG. 5(A) shows a state in which the pressing motor 411 is driven to move the driver bit 51 from the initial position in the direction of arrow P to approach the workpiece W and move it to a predetermined position, and the screw 53 is adsorbed to the tip of the driver bit 51. In FIG. 5(A), the predetermined position indicates that the tip of the driver bit 51 is at a distance L1 from the surface of the workpiece W.

[0041] For example, if the distance between the tip of the driver bit 51 at the initial position and the surface of the workpiece W is stored in the storage unit 116 in advance, in the arithmetic unit 115, by calculating the difference between the distance and the distance L1, the pressing motor control unit 112 and the driver bit position detection unit 113 can move the driver bit 51 to the position in FIG. 5(A). The controller 11 enters a standby state until the screw 53 is adsorbed as shown in FIG. 5(A), and when it recognizes that the screw 53 has been adsorbed, it starts screw tightening control (step S601).

[0042] The fact that the screw 53 has been adsorbed is recognized, for example, by an input signal from the outside (such as a screw supply device) to the controller 11. As a means for adsorbing the screw 53 to the driver bit 51, a method of magnetizing the driver bit 51 and adsorbing the screw 53 by magnetic force can be adopted.

[0043] Subsequently, the pressing motor control unit 112 of the controller 11 outputs a drive signal to the electric driver unit 12 so as to move the driver bit 51 in the direction of arrow P in FIG. 5, and drives the pressing motor 411 (step S602). Subsequently, the driver motor control unit 111 outputs a drive signal that rotates the driver bit 51 in the direction of tightening the screw 53, outputs it to the electric driver unit 12, and drives the driver motor 311 (step S603). By performing control to drive the pressing motor 411 and the driver motor 311 in this way, the screw 53 approaches the workpiece W while rotating, reaches the surface of the workpiece W, and then is tightened into the workpiece W.

[0044] FIG. 5(B) shows a state where the screw 53 has reached the surface of the workpiece W, and FIG. 5(C) shows a state where the screw 53 is being tightened into the workpiece W. Even in the states of FIGS. 5(B) and 5(C), since the pressing motor 411 continues to be driven, a force for pressing the screw 53 in the direction of the workpiece W (arrow P direction) continues to be applied to the driver bit 51. Therefore, even when the screw 53 is tightened into the workpiece W by the rotation of the driver bit 51, the tip of the driver bit 51 can continue to engage without leaving the screw 53 and continue to apply a rotational force.

[0045] In the states of FIGS. 5(B) and 5(C), the torque detection unit 114 of the controller 11 continues to detect the torque value by acquiring the output current value of the driver motor 311. The arithmetic unit 115 compares the torque value detected by the torque detection unit 114 with the threshold value previously stored in the storage unit 116. Then, by determining whether the torque value exceeds the threshold value, it is determined whether the screw 53 has reached the screw tightening completion position (step S605).

[0046] FIG. 5(D) shows a state where the screw 53 is tightened to the screw tightening completion position. In this state, since the screw 53 and the driver bit 51 cannot continue to rotate, the torque of the driver motor 311 increases and the output current increases. As a result, the torque value detected by the torque detection unit 114 exceeds the threshold value. When the torque value exceeds the threshold value (step S605: YES), the position of the driver bit 51 is detected by the driver bit position detection unit 113 (step S606). When the detected torque value is below the threshold value (step S605: NO), torque detection is continued with the driver motor 311 and the pressing motor 411 driven.

[0047] The arithmetic unit 115 compares the position information of the driver bit 51 detected by the driver bit position detection unit 113 with the information on the allowable range of the position of the driver bit 51 at the completion of screw tightening previously stored in the storage unit 116 (step S607). If the position of the driver bit 51 is within the allowable range, it is determined that the screw tightening has been completed normally (step S607: YES), the screw tightening operation is terminated, and the pressing motor control unit 112 controls to switch the pressing motor 411 to reverse drive to return the driver bit 51 to the initial position. FIG. 5(E) shows a state where the screw tightening is completed and the driver bit 51 is being moved to the initial position.

[0048] When the position of the driver bit 51 is not within the allowable range (step S607: NO), it is determined that the screwing has not been completed normally, and the user is requested to perform an inspection process (step S608). As a cause, for example, when the screw 53 becomes non-rotatable before reaching the state of FIG. 5(D) (when tightening cannot be performed halfway).

[0049] In the above-described screwing operation, the pressing force in the direction of arrow P by the pressing motor 411 is applied by the pressing shaft 413. The center line of the pressing shaft 413 coincides with the center line C of the driver bit 51 (center line C in FIG. 5) and also coincides with the center line of the screw 53. Therefore, no force is applied to the screw 53 in a direction other than the center line direction, and the screwing is performed smoothly.

[0050] FIG. 7 is a diagram for explaining the screw loosening operation using the electric driver device 1, and FIG. 8 is a diagram showing the control flow during the screw loosening operation using the electric driver device 1. The operations described below are realized by a program for realizing the operations shown in the flowchart of FIG. 8 being stored in the memory of the computer that constitutes the controller 11 and the processor of the computer reading and executing the program. Similar to the screwing operation, before starting the screwing operation, the pressing motor control unit 112 of the controller 11 outputs a drive start signal to start driving the pressing motor 411 to the electric driver unit 12, and moves the driver unit 31 in a straight line to the initial position.

[0051] FIG. 7(A) shows a state where the driver bit 51 is waiting at the initial position. In FIG. 7(A), the initial position indicates that the tip of the driver bit 51 is at a distance L2 from the surface of the workpiece W. In this state, the pressing motor control unit 112 of the controller 11 outputs a drive signal to the electric driver unit 12 to move the driver bit 51 in the direction of arrow P, and drives the pressing motor 411 (step S801). When the pressing motor 411 is driven, the driver bit 51 approaches the screw 53 tightened to the workpiece.

[0052] While the driver bit is moving, the driver bit position detector 113 detects the position of the driver bit (step S802). Then, the arithmetic unit 115 determines whether the tip of the driver bit 51 has reached a predetermined position near the screw 53 based on the position information detected by the driver bit position detector 113 (step S803).

[0053] FIG. 7(B) shows a state where the driver bit 51 has reached a predetermined position near the screw 53. FIG. 7(B) shows that the predetermined position near the screw 53 is a position moved in the direction of arrow P by a distance L3 from the initial position. Information indicating the distance L3 is stored in the storage unit 116 in advance. The arithmetic unit 115 can determine whether the tip of the driver bit 51 has reached a predetermined position near the screw 53 based on the position information detected by the driver bit position detector 113 and the information on the distance L3 stored in the storage unit 116.

[0054] When it is determined that the driver bit 51 has not reached the predetermined position (step S803: NO), the operations of step S802 and step S803 are repeated. When it is determined that the driver bit 51 has reached the predetermined position (step S803: YES), the driver motor control unit 111 outputs a drive signal to rotate the driver bit 51 in the direction of loosening the screw 53 (the direction opposite to the case of screw tightening described with reference to FIGS. 5 and 6), and drives the driver motor 311 (step S804). At this time, similar to the case of screw tightening control, an operation for adsorbing the screw 53 to the driver bit 51 is started.

[0055] The pressing motor control unit 112 continues to control the driving of the pressing motor 411 (step S805). The driver bit 51 approaches the screw 53 while rotating, and the tip of the driver bit 51 contacts the head of the screw 53 and engages with the cross hole (or split) formed in the head of the screw 53. FIG. 7(C) shows a state where the tip of the driver bit 51 is engaged with the cross hole in the head of the screw 53.

[0056] When shifting from the state of FIG. 7(B) to the state of FIG. 7(C), the rotational torque applied to the driver bit 51 by the control of the driver motor control unit 111 is preferably made smaller than the rotational torque when loosening the screw in FIGS. 7(D) and 7(E) described later, so that the tip of the driver bit 51 smoothly engages with the screw 53.

[0057] Similarly, when shifting from the state of FIG. 7(B) to the state of FIG. 7(C), the pressing force applied to the driver bit 51 by the control of the pressing motor control unit 112 (that is, the rotational torque output by the pressing motor 411) is preferably made smaller than when shifting from the state of FIG. 7(A) to the state of FIG. 7(B). By doing so, the moving speed of the driver bit 51 in the direction of arrow P when shifting from the state of FIG. 7(B) to the state of FIG. 7(C) is reduced compared to when shifting from the state of FIG. 7(A) to the state of FIG. 7(B), and the tip of the driver bit 51 can be smoothly engaged with the screw 53.

[0058] In step S804 and step S805, by starting control to drive the driver motor 311 and the pressing motor 411 with appropriate torque for loosening the screw, the screw 53 fastened to the workpiece W is loosened. FIG. 7(D) shows a state where the screw 53 is being loosened and rising with respect to the workpiece W surface. In the state of loosening the screw 53, the pressing force in the direction of arrow P with which the driver bit 51 presses the screw 53 by driving the pressing motor 411 is such that it does not prevent the screw 53 from rising with respect to the workpiece W surface. The pressing motor control unit 112 controls the torque of the pressing motor 411.

[0059] In the state of loosening the screw as shown in FIG. 7(D), the driver bit position detection unit 113 detects the position of the driver bit (step S806). Then, the arithmetic unit 115 determines whether the tip of the driver bit 51 has reached a predetermined position before the lower end of the screw 53 comes out of the workpiece W based on the position information detected by the driver bit position detection unit 113 (step S807).

[0060] FIG. 7(E) shows a state where the lower end of the screw 53 has reached a predetermined position before coming out of the workpiece W. The predetermined position may be set regardless of the characteristics of the screw and the tightening conditions, or may be determined depending on the structural characteristics of the screw such as the length of the screw, the pitch of the thread, the strength of the screw, the diameter of the screw, or control parameters such as the rotation speed and the pressing force. As an example, it is preferable to set, as the predetermined position, the position when the screw 53 reaches a position where about the last two threads of the screw 53 have not come out of the workpiece W. In short, as will be described later, the predetermined position may be determined so that the loosening of the screw is achieved reliably and smoothly.

[0061] FIG. 7(E) shows that in this case, the predetermined position is a position where the tip of the driver bit 51 is separated from the initial position by a distance L4 in the direction of arrow P. Information indicating the distance L4 is stored in the storage unit 116 in advance. The arithmetic unit 115 can determine whether the tip of the driver bit 51 has reached the predetermined position shown in FIG. 7(E) based on the position information detected by the driver bit position detector 113 and the information on the distance L4 stored in the storage unit 116.

[0062] When it is determined that the driver bit 51 has not reached the predetermined position (step S807: NO), the operations of steps S806 and S807 are repeated. When it is determined that the driver bit 51 has reached the predetermined position (step S807: YES), the pressing motor control unit 112 outputs a drive signal for reversing the rotation direction of the pressing motor 411 (step S808).

[0063] That is, in the state of FIG. 7(E), the rotation direction of the pressing motor 411 is reversed. Since the rotation of the driver bit 51 continues in the same direction, the loosening of the screw 53 continues. FIG. 7(F) shows a state where the entire screw 53 has come out of the workpiece W and the screw loosening is completed. When the state of FIG. 7(E) is reached, since the rotation direction of the pressing motor 411 is reversed, the pressing force in the direction of arrow P by the driver bit 51 does not occur, and a force for the driver bit 51 to move in the direction opposite to the P direction in FIG. 7 acts. As a result, in the state where the screw loosening is completed as shown in FIG. 7(F), the screw 53 can be smoothly removed from the workpiece W without rattling caused by the screw 53 being pressed against the workpiece W surface direction.

[0064] The calculation unit 115 determines whether the driver bit 51 has reached the position shown in FIG. 7(F) based on the position information detected by the driver bit position detection unit 113 (step S809). If it has not reached (step S809: NO), the process of step S809 is repeated with the driver motor 311 and the pressing motor 411 being driven. If it has reached (step S809: YES), the pressing motor control unit 112 performs control to return the driver bit 51 to the initial position and ends the process. In this case, the driver motor control unit 111 may perform control to stop the driving of the driver motor.

[0065] In the screw loosening operation as described above, similar to the screw tightening operation, the pressing force in the direction of arrow P by the pressing motor 411 is applied by the pressing shaft 413. However, the center line of the pressing shaft 413 coincides with the center line C of the driver bit 51 (center line C in FIG. 7) and also coincides with the center line of the screw 53. Therefore, no force is applied to the screw 53 in a direction other than the center line direction, and the screw loosening is performed smoothly. Also, in FIGS. 7(C) to (E), since the screw 53 is loosened while being pressed, the tip of the driver bit 51 continues to engage with the screw 53, and the screw loosening is performed smoothly without the driver bit 51 and the screw 53 separating from each other.

[0066] FIG. 9 is a diagram showing the configuration of a cable connecting between two circuit boards in the electric driver unit 12 of the electric driver device 1. FIG. 9(A) is a configuration diagram according to the present embodiment, and FIG. 9(B) is a configuration diagram according to a comparative example. In FIG. 9, members denoted by the same reference numerals as those in FIGS. 1 to 3 are the same members as those shown in FIGS. 1 to 3, and thus the description thereof is omitted.

[0067] As described above, the circuit board 315 is attached to the driver unit 31, and is provided with a circuit for inputting and outputting signals to and from the driver motor 311. As described above, the circuit board 415 is attached across the upper surfaces of the support portion 213 and the support portion 214, and is provided with a circuit for inputting and outputting signals to and from the pressing motor 411 and the encoder 421. Since the circuit board 315 is attached to the driver unit 31, it moves in the direction of arrow M integrally with the driver unit 31 due to the movement of the driver unit 31 in the direction of arrow M caused by the driving of the pressing motor 411. Since the circuit board 415 is fixed to the base portion 21, its position with respect to the base portion 21 does not change.

[0068] As can be seen from FIG. 2(A), the circuit boards 315 and 415 are rectangular (rectangular in this embodiment) plate-like members. As shown in FIGS. 2 and 9, the circuit boards 315 and 415 are installed such that one side of each rectangle faces the other. As shown in FIG. 9(A), connectors 315a and 415a are provided near the sides of the circuit boards 315 and 415 opposite to the sides facing the other circuit board.

[0069] Also, the connectors 315a and 415a are provided near the corners of each circuit board. In FIG. 9(A), only one connector 315a of the circuit board 315 is shown, which is the connector 315a provided at the front corner, and a connector 315a is also provided at the rear corner. Similarly, the connectors 415a of the circuit board 415 are provided at the front corner and the rear corner.

[0070] The cable 317 is connected at both ends to the connectors 315a and 415a. The cable 317 is composed of a plurality of wirings such as signal lines and power lines bundled together. The circuit board 315 side of the cable 317 is installed along the side surface of the base portion 21 through the space between the driver portion 31 and the support portion 212 from the connector 315a. The portion of the cable 317 installed along the side surface of the base portion 21 is housed in the groove portion 217 provided on the side surface of the base portion 21. The groove portion 217 is closed by a lid member with a part of the cable 317 housed therein.

[0071] The circuit board 415 side extends from the groove portion 217 through the space between the support portion 214 and the support portion 215 to the connector 415a. The cable 317 is provided on the back side in the same manner as that provided on the front side in FIG. 9(A) and is connected to the connectors 315a and 415a provided on the back side. The groove portion 217 is also provided on the side surface of the base portion 21 on the opposite side.

[0072] FIG. 9(B) is a diagram showing a configuration according to a comparative example. Connectors 315b and 415b are provided near the sides of each of the circuit boards 315 and 415 facing the other circuit board. The cable 317A is connected at both ends to the connectors 315b and 415b. Compared with the cable 317 in FIG. 9(A), the cable 317A in FIG. 9(B) is shorter, and the space required for installing the cable 317A is also smaller than in the case of FIG. 9(A).

[0073] During the screwing or unscrewing operation, since the driver unit 31 moves straight in the direction of arrow M, the distance between the circuit boards 315 and 415 also changes. In the case of the configuration as shown in Fig. 9(B), the length of the cable 317A is set such that no tension is applied to the cable 317A even when the distance between the circuit boards 315 and 415 increases. When the distance between the circuit boards 315 and 415 decreases, the cable 317A bends significantly. As the straight movement of the driver unit 31 is repeated, the cable 317A will repeatedly deform between the extended state and the bent state, resulting in problems with durability. Also, at the connection parts of both ends of the cable 317A with the connectors 315b and 415b, it is also easily affected by the deformation of the cable 317A, and damage and the like are likely to occur.

[0074] In Fig. 9(A), connectors 315a and 415a are provided near the opposite sides of the circuit boards 315 and 415 with respect to Fig. 9(B) to connect the cable 317. The cable 317 is longer than the cable 317A in Fig. 9(B), and near the connectors 315a and 415a, the cable 317 can be installed in a sufficiently wide space. Therefore, the bending of the cable 317 due to the straight movement of the driver unit 31 is smaller than that of the cable 317A in Fig. 9(B), the durability of the cable 317 is improved, and damage to the cable 317 or the connectors 315a and 415a at the connection part with the connectors 315a and 415a is also less likely to occur.

[0075] Fig. 10 is a diagram showing the state in which two types of driver motors are attached in the electric driver unit 12 of the electric driver device 1. As shown in Fig. 10(A), the case member constituting the driver unit 31 is provided with a driver motor 311 inside.

[0076] When performing screwing or unscrewing on a workpiece, depending on the size of the screw used, it is necessary to prepare an electric driver unit equipped with a driver motor capable of generating a torque suitable for that screw size. In such a case, in the present embodiment, it is possible to replace the driver motor 311 of the electric driver unit 12.

[0077] Figure 10(B) shows a state in which the motor 311 for the driver provided in the driver unit 12 of the electric driver unit is removed and a new motor 311A for the driver is attached. The motor 311A for the driver is a motor capable of generating higher torque than the motor 311 for the driver, and therefore, it is larger in size than the motor 311 for the driver. As shown in FIGS. 10(A) and 10(B), with respect to the radial length D1 of the motor 311 for the driver, the motor 311A for the driver has a radial length D2 that is longer than D1.

[0078] In the present embodiment, in the case member of the driver unit 31, as shown in FIG. 10(A), the motor 311 for the driver is attached so that a predetermined space is secured around (vertically in the figure) the motor 311 for the driver. Therefore, as shown in FIG. 10(B), it is also possible to attach the large-sized motor 311A for the driver within the case member of the driver unit 31.

[0079] In the present embodiment, when the motor 311 for the driver is attached and when the motor 311A for the driver is attached within the case member of the driver unit 31, the position of the output shaft 312 does not change. That is, the distance E from the bottom surface of the base portion 21 to the center of the output shaft 312 is the same regardless of which of the motors 311 and 311A for the driver is attached. Although not shown in FIG. 10, the position of the support portion 212 of the output shaft 312 in the depth direction also does not change between FIGS. 10(A) and 10(B).

[0080] Here, depending on the size, composition, tightening conditions, etc. of the screw, the ideal output torque characteristics of the motor to be used may also vary. According to the above configuration, in the state where the electric driver unit 12 is attached to the robot arm, regardless of whether the driver motors 311 and 311A with different torque characteristics are used, the positional relationship of the driver bit 51 with respect to the robot arm does not change. Therefore, even when the torque of the driver motor is changed, it is not necessary to adjust the positional relationship between the robot arm and the driver bit 51. Thus, by simply appropriately replacing the driver motor using the electric driver device 1, it is possible to cope with different tightening conditions and the like.

[0081] For example, when using different electric driver units to change the torque of the driver motor, the position of the driver bit with respect to the robot arm may change. However, by using the electric driver unit 12 of the present embodiment, readjustment due to torque change of the driver motor becomes unnecessary.

[0082] [Modification Example] The above-described embodiments can be variously modified. Examples of these modifications are shown below. Note that the above-described embodiments and the modification examples shown below may be appropriately combined.

[0083] (1) In the above-described embodiment, the encoder 421 is provided in the pressing unit 41, but an encoder may be provided in the driver unit 31. Further, although the torque detection unit 114 of the controller 11 is configured to detect the torque of the driver motor 311, it may be configured to detect the torque of the pressing motor 411. FIG. 11 is a block diagram showing the configuration of an electric driver device 1A according to a modification example. In FIG. 11, components denoted by the same reference numerals as those in FIG. 4 are the same as those in FIG. 4, and thus the description thereof is omitted.

[0084] The controller 11A of the electric driver device 1A shown in Fig. 11 is different from the controller 11 shown in Fig. 4 in that it includes a driver motor torque detection unit 114A and a pressing motor torque detection unit 114B. Further, the electric driver unit 12A is different from the electric driver unit 12 shown in Fig. 4 in that it includes an encoder 321. The encoder 321 of the electric driver unit 12A is provided in the driver unit 31 and detects the rotational position of the rotor of the driver motor 311 (i.e., the rotational position of the output shaft 312).

[0085] Similar to the torque detection unit 114 in Fig. 4, the driver motor torque detection unit 114A of the controller 11A acquires the output current value information of the driver motor 311 from the electric driver unit 12A and estimates the torque value of the driver motor. The pressing motor torque detection unit 114B acquires the output current value information of the pressing motor 411 from the electric driver unit 12A and estimates the torque value of the pressing motor 411. In the modification example of Fig. 11, the input / output control circuit 121 transmits the rotational position information of the driver motor 311 based on the detection signal from the encoder 321 and the current value information obtained by monitoring the output current of the pressing motor 411 to the controller 11A.

[0086] In addition to the rotational position information of the pressing motor 411 from the electric driver unit 12A, the driver bit position detection unit 113 of the controller 11A acquires the rotational position information of the driver motor 311 (based on the detection result of the encoder 321). Therefore, it is possible to calculate the position information of the driver bit 51 based on the rotational position information of the pressing motor 411 and also calculate the position information of the driver bit 51 based on the rotational position information of the driver motor 311. The calculation of the position information of the driver bit 51 based on the rotational position information of the driver motor 311 can be calculated based on the rotational position information and the pitch information of the thread of the screw 53 stored in advance in the storage unit 116.

[0087] According to the electric driver device 1A according to the above-described modification example, the control operation of screwing or unscrewing in the electric driver device 1 according to the above-described embodiment can be changed. In the control of screwing in the above-described embodiment, the determination as to whether or not the screw 53 has reached the screw tightening completion position in steps S604 and S605 of FIG. 6 was made based on whether or not the torque value of the driver motor 311 exceeded the threshold value. However, it may be made based on whether or not the torque value of the pressing motor 411 exceeds the threshold value.

[0088] As shown in FIG. 5(D), in a state where the screw 53 is tightened to the screw tightening completion position, the pressing shaft 413 cannot continue to move straight, so the output current of the pressing motor 411 increases. As a result, since the torque value detected by the pressing motor torque detection unit 114B exceeds the threshold value, it can be determined that the screw 53 has reached the screw tightening completion position.

[0089] Further, in the above-described embodiment, the determination as to whether or not the position of the driver bit 51 when it is determined that screwing is completed in steps S606 and S607 of FIG. 6 is within the allowable range is made based on the position information of the driver bit 51 based on the rotation position information of the pressing motor 411 detected by the driver bit position detection unit 113. This determination may be made based on the position information of the driver bit 51 based on the rotation position information of the driver motor 311 (based on the detection result of the encoder 321).

[0090] In this case, the driver bit position detection unit 113 acquires the rotation position information of the driver motor 311 based on the detection result of the encoder 321. Then, the position of the driver bit 51 is estimated from the number of rotations of the driver motor 311 from the state of FIG. 5(B) and the information on the number of threads of the screw 53 stored in advance in the storage unit 116, and compared with the information on the allowable range of the position of the driver bit 51 at the time of completion of screwing stored in advance in the storage unit 116.

[0091] The determination that the state shown in Fig. 5(B) (the state where the lower end of the screw 53 has reached the surface of the workpiece W) has been reached can be made based on the position information of the driver bit 51 based on the rotational position information of the pressing motor 411. Further, the determination that the state shown in Fig. 5(B) has been reached may be made based on the variation in the torque value calculated by the driver motor torque detection unit 114A or the pressing motor torque detection unit 114B.

[0092] Also, in the screw loosening control of the above-described embodiment, in step S807 of Fig. 8, the determination that the driver bit 51 has reached the position shown in Fig. 7(E) is made based on the position information of the driver bit 51 based on the rotational position information of the pressing motor 411 detected by the driver bit position detection unit 113. This determination may be made based on the position information of the driver bit 51 based on the rotational position information (based on the detection result of the encoder 321) of the driver motor 311.

[0093] In this case, the driver bit position detection unit 113 acquires the rotational position information of the driver motor 311 based on the detection result of the encoder 321. Then, the position of the driver bit 51 is estimated from the number of rotations of the driver motor 311 from the state shown in Fig. 7(C) and the information on the number of threads of the screw 53 stored in advance in the storage unit 116, and it may be determined that the driver bit 51 has reached the position shown in Fig. 7(E).

[0094] The determination that the state shown in Fig. 7(C) (the state where the driver bit 51 is engaged with the screw 53) has been reached can be made based on the position information of the driver bit 51 based on the rotational position information of the pressing motor 411. Further, the determination that the state shown in Fig. 7(C) has been reached may be made based on the variation in the torque value calculated by the driver motor torque detection unit 114A or the pressing motor torque detection unit 114B.

[0095] In the above-described embodiment, in step S809 of FIG. 8, the determination that the driver bit 51 has reached the position shown in FIG. 7(F) is made based on the position information of the driver bit 51 based on the rotation position information of the pressing motor 411 detected by the driver bit position detection unit 113. This determination may also be made based on the position information of the driver bit 51 based on the rotation position information of the driver motor 311 (based on the detection result of the encoder 321).

[0096] In this case, the driver bit position detection unit 113 acquires the rotation position information of the driver motor 311 based on the detection result of the encoder 321. Then, the position of the driver bit 51 is estimated from the number of rotations of the driver motor 311 from the state of FIG. 7(C) (or the state of FIG. 7(E)) and the information on the number of threads of the screw 53 stored in advance in the storage unit 116, and it may be determined that the driver bit 51 has reached the position of FIG. 7(F).

[0097] (2) In the above-described embodiment, the controller 11 has functional configurations such as the driver motor control unit 111, the pressing motor control unit 112, the driver bit position detection unit 113, the torque detection unit 114, the calculation unit 115, and the storage unit 116. However, these functional configurations may be those of the electric driver unit 12. For example, a CPU, a memory, etc. may be provided on the circuit board 315 or the circuit board 415 of the electric driver unit 12, and a configuration may be adopted that performs functions equivalent to those of the driver motor control unit 111, the pressing motor control unit 112, the driver bit position detection unit 113, the torque detection unit 114, the calculation unit 115, the storage unit 116, etc.

[0098] (3) In the above-described embodiment, a part of the cable 317 is housed in the groove 217 provided on the side surface of the base portion 21. However, if a situation where the cable 317 contacts or gets caught by other members does not occur during the screwing or unscrewing operation, there is no need to provide a groove for housing. For example, a plurality of portions of the cable 317 may be fixed to the base portion 21 with pin-shaped members or the like.

[0099] (4) In the above-described embodiment, as shown in FIG. 10, the driver motor 311 was replaced with a driver motor 311A that is larger in size (higher torque) than the driver motor 311. However, the driver motor 311 may be replaced with a driver motor that is smaller in size (lower torque) than the driver motor 311.

[0100] (5) In the above-described embodiment, a stepping motor was used as the driver motor and the pressing motor. However, other types of motors (for example, a DC motor, etc.) may be used as long as detection of the rotational position and detection of the torque are possible.

Explanation of Reference Numerals

[0101] 1, 1A: Electric driver device, 11, 11A: Controller, 12, 12A: Electric driver unit, 21: Base portion, 31: Driver portion, 41: Pressing portion, 51: Driver bit, 53: Screw, 110: Communication line, 111: Driver motor control portion, 112: Pressing motor control portion, 113: Driver bit position detection portion, 114: Torque detection portion, 114A: Driver motor torque detection portion, 114B: Pressing motor torque detection portion, 115: Arithmetic portion, 116: Storage portion, 117: Input portion, 118: Display portion, 121: Input / output control circuit, 212, 213, 214, 215: Support portion, 217: Groove portion, 311: Driver motor, 312: Output shaft, 315: Circuit board, 315a: Connector, 321: Encoder, 317: Cable, 411: Pressing motor, 412: Output shaft, 413: Pressing shaft, 415: Circuit board, 415a: Connector, 421: Encoder, W: Workpiece.

Claims

1. A motor for a driver that performs screwing or unscrewing by rotating an output shaft, A pressing shaft disposed on an extension line of the rotation center line of the output shaft, A pressing motor that applies a force to press the driver motor in a direction along the rotation center line with respect to the pressing shaft An electric driver device comprising.

2. The pressing shaft is connected to the output shaft of the pressing motor, and when the output shaft rotates by driving the pressing motor, the pressing shaft can move straight in a direction along the rotation center line The electric driver device according to claim 1.

3. A driver bit is connected to the output shaft of the driver motor, and the pressing motor is disposed on an extension line of the rotation center line at a position on the side opposite to the side where the driver bit is connected to the driver motor The electric driver device according to claim 1 or 2.

4. A first circuit board provided with a circuit for driving the driver motor, A second circuit board provided with a circuit for driving the pressing motor, A cable connecting the first circuit board and the second circuit board, The first circuit board moves relatively along the rotation center line direction with respect to the second circuit board by driving the pressing motor, A first connector for connecting one end side of the cable to the first circuit board is provided in the vicinity of the side opposite to the side of the first circuit board facing the second circuit board, A second connector for connecting the other end side of the cable to the second circuit board is provided in the vicinity of the side opposite to the side of the second circuit board facing the first circuit board The electric driver device according to any one of claims 1 to 3.

5. A case member for housing the driver motor, The case member can remove the driver motor and house another driver motor, When the other driver motor is attached, the position of the output shaft does not change compared to when the driver motor is attached The electric driver device according to any one of claims 1 to 4.

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