JP2018153894A - Automatic screw driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic screw driving device of which a motor can be replaced with another motor, even when the motors have different ratings.SOLUTION: The automatic screw driving device has a robot 50 including an interface mechanism that can mount and dismount a screw driving tool 10 having a bit Ba to be engaged with a screw S. The screw driving tool 10 comprises: a bit holder 30 for supporting the bit Ba; and a rotary drive 20 for rotating the bit Ba. The bit holder 30 and the rotary drive 20 are directly connected to each other through a tool holding plate 40 perpendicular to an axis of the bit Ba. The tool holding plate 40 has a first sliding plate 45 that slides parallel to the tool holding plate. The interface mechanism includes a first interface mechanism for connecting/disconnecting the first sliding plate 40 and the robot 50 to/from each other. The first interface mechanism includes: a first fitting shank member 51 that is moved in a radially expanding direction by input of compressed air; and a first fitting hole member 41 to be fitted to the first fitting shank member. The robot 50 has one of the first fitting shank member 51 and the first fitting hole member 41, while the first sliding plate 40 has the other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an automatic screw tightening device capable of exchanging a bit or a rotation driving unit for applying rotation to the bit in accordance with the type or size of the screw.

  As shown in Patent Document 1, a conventional automatic screw fastening device includes a rotation driving unit that applies a rotational force to a bit that engages with a screw, and a bit holding unit that supports the bit so as to be rotatable and slidable. A screw tightening tool, a robot that can hold the screw tightening tool in a hand that can be opened and closed, and can move to a predetermined position, and a control that is wired to the screw tightening tool and the robot and gives a drive command to each Device. The screw tightening tool includes an attachment / detachment mechanism that enables attachment / detachment of the bit holding unit and the rotation driving unit.

  The attachment / detachment mechanism includes an air cylinder disposed on a base to which the rotation driving unit is fixed, an outer cylinder that is movable in an axial direction via a floating joint connected to the air cylinder, and an inner peripheral surface of the outer cylinder. Or it is comprised from the inner cylinder which provided the steel ball engaged with a taper surface freely. The steel ball is positioned inward so as to protrude from the inner peripheral surface of the inner cylinder when contacting the inner peripheral surface of the outer cylinder, while the outer periphery of the inner cylinder is opposite to the previous one when contacting the tapered surface of the outer cylinder. Located outward so as to protrude from the surface.

  The bit holding portion is a compression spring that always presses the bit downward, a torque transmission shaft that engages with one end of the compression spring, and is inserted into the compression spring, and that fixes the bit and fits the torque transmission shaft. The socket includes a socket that slides in the axial direction while being joined, and a connecting portion that is provided above the socket and that has an engaging groove that is inserted into the inner cylinder and engages the steel ball.

  The rotation driving unit is configured by integrally rotating an output shaft inserted through the inner cylinder, and the output shaft has a tip shape that fits into the socket.

  The conventional automatic screw tightening device configured as described above is characterized in that since it can hold different types of screw tightening tools on the hand of the robot, it can be easily handled even when the screws are changed.

  In addition, the conventional automatic screw tightening device is configured so that the steel ball is fitted into the engaging groove of the connecting portion and is brought into contact with the inner peripheral surface of the outer cylinder by operating the cylinder. And the rotary drive unit can be attached and detached. Thereby, there also exists the characteristic that the freedom degree of the combination of the said bit holding | maintenance part and rotation drive part which comprises a screw fastening tool is high.

International Patent Publication Number WO2015 / 140939

  However, the conventional automatic screw tightening device rotates the robot while moving the robot to a predetermined position while pressing the screw engaged with the bit against the workpiece. At this time, the compression spring in the bent state is returned to the original state as the screw is screwed in, and the socket moves relative to the torque transmission shaft and rotates as the compression spring returns. Slide while. Therefore, in the conventional automatic screw tightening device, torque is applied to the sliding portion between the socket and the torque transmission shaft when the screw is screwed in. Therefore, when the torque generated when the screw is screwed in is high, the socket smoothly slides. There was a problem that it was difficult to obtain.

  Further, in the conventional automatic screw tightening device, the bit holding part and the rotation driving part are connected by a steel ball having a spherical surface, so that the bit holding part easily tilts following the spherical surface of the steel ball. There was also a problem that the bit engaged with the screw was easily tilted.

  An object of the present invention is to solve the above-described problems, and includes a screw tightening tool including a bit that is engaged with a screw that is fastened to a work and is rotatable, and an attaching / detaching mechanism that can attach and detach the screw tightening tool. In the automatic screw tightening device configured with a robot capable of moving to a predetermined position in response to a command from the control device, the screw tightening tool includes a bit holding portion configured to rotatably support the bit, and the bit holding And a rotation drive unit that applies rotation to the bit. The rotation drive unit and the bit holding unit are directly connected via a tool holding plate that extends in a direction perpendicular to the axis of the bit. The tool holding plate is made up of a slide shaft erected on the tool holding plate, and is always in contact with the tool holding plate inserted through the slide shaft. A bit cushion spring, a bush inserted through the slide shaft, and a first sliding plate that is integrally attached to the bush and is arranged in parallel to the tool holding plate. A first attachment / detachment mechanism that connects or disconnects the sliding plate and the robot is provided. The first attachment / detachment mechanism includes a first fitting shaft member that operates in a direction of expanding the diameter by the input of compressed air, and the first fitting. The robot and the first sliding plate are each provided with either the first fitting shaft member or the first fitting hole member. It is characterized by that. The rotation driving unit includes a polygonal fitting unit that connects the bit holding unit, and the bit holding unit rotatably supports the bit and is parallel to the tool holding plate. A bit holding plate disposed, wherein the attaching / detaching mechanism includes a first attaching / detaching mechanism and a second attaching / detaching mechanism that connects or disconnects the bit holding plate and the tool holding plate. Is composed of a second fitting shaft member that operates in the direction of expanding the diameter by the input of compressed air, and a second fitting hole member that fits into the second fitting shaft member, and the bit holding plate and the The tool holding plate includes either the second fitting shaft member or the second fitting hole member.

  As described above, the automatic screw tightening apparatus according to the present invention has a first sliding plate that is formed by directly connecting a bit to the rotation driving unit and is edge-cut from the rotating bit and slides in the axial direction. There is an advantage that the bit can slide smoothly in the axial direction as compared with the conventional case.

  The automatic screw tightening apparatus according to the present invention is a first attachment / detachment mechanism that enables attachment / detachment of the robot and the tool holding plate, or attachment / detachment of the bit holding plate and the tool holding plate in addition to the first attachment / detachment mechanism. A second attaching / detaching mechanism is provided. As a result, the automatic screw tightening apparatus of the present invention has an advantage that the robot can be a different type of screw tightening tool, or the combination of the bit holding portion or the rotation driving portion constituting the screw tightening tool can be changed. In addition, since the automatic screw tightening device of the present invention has a structure in which steel balls are not used at the connecting portion of the bit holding portion and the rotation driving portion, there is an advantage that the problem that the bit is easily inclined as in the conventional case can be solved.

It is a schematic explanatory drawing showing one embodiment concerning the present invention. (A) is sectional drawing which shows the principal part, (b) is a partially notched sectional view which looked at (a) from the front. It is a schematic explanatory drawing which shows another embodiment which concerns on this invention. (A) is a partially cutaway sectional view showing the main part, (b) is a partially cutaway sectional view of (a) seen from the front. It is a schematic explanatory drawing which shows other embodiment which concerns on this invention. (A) is a partially cutaway sectional view showing the main part, (b) is a partially cutaway sectional view of (a) seen from the front. It is operation | movement explanatory drawing which is carrying out the screw fastening operation | work with the screw fastening tool of FIG. (A) is principal part sectional drawing which shows the early stage of the screw fastening operation | work which adsorb | sucks a screw and screw | tightens to a workpiece | work, (b) is a partially notched sectional view which looked at (a) from the front. It is operation | movement explanatory drawing which shows the intermediate | middle board of the screw fastening operation which progressed from FIG. (A) is principal part sectional drawing which shows the time of the attracted screw contact | abutting to a workpiece | work and the bit cushion spring bent, (b) is a partially notched sectional view which looked at (a) from the front. . It is operation | movement explanatory drawing which shows the second half of the screwing operation which progressed from FIG. (A) is a principal part sectional view in which a screw is screwed into a work and a bit cushion spring is returning. (B) is a partially cutaway sectional view of (a) as viewed from the front. It is explanatory drawing for demonstrating connection with a rotation drive part and a bit holding | maintenance part. (A) is a partially cutaway cross-sectional explanatory view showing the main part, (b) is a schematic explanatory view of (a) seen from the front.

  Hereinafter, an embodiment of an automatic screw tightening device according to the present invention will be described with reference to FIGS. The automatic screw tightening device 1 is configured to fasten a screw S that is provided on the workpiece W and is screwed to the screw Wa with a predetermined torque, and a bit Ba (Bb) that can be fitted into a drive hole of the screw S. ), A screw holding tool 30 provided with a bit holding part 30 provided rotatably and a rotation driving part 20 for imparting rotation to the bit Ba (Bb), a robot 50 capable of removing the screw tightening tool 10, and a robot The robot 50 and a control device (not shown) for controlling the screw tightening tool 10 are configured. Further, as an example of the automatic screw tightening device 1 according to the present invention, various forms such as those shown in FIG. 1, FIG. 4 to FIG. 6, those shown in FIG. 2, and those shown in FIG. 3 and FIG. In the following, these automatic screw fastening apparatuses having different forms will be described in order.

  First, the automatic screw tightening device 1 shown in FIGS. 1, 4 to 6 can change a screw tightening tool of a different form to the robot 50 by changing the screw S fastened to the workpiece W or the like. The robot 50 of the automatic screw tightening apparatus 1 can change the screw tightening tool that cannot be changed because the combination of the bit holding unit 30 and the rotation driving unit 20 is fixed, and is different in the form supported by a plurality of support plates 100. A screw tightening tool can be attached. Further, the robot 50 has a multi-joint structure or a plurality of slide tables (not shown) that move to XYZ coordinates, and the like, and a first fitting shaft member that forms part of an attachment / detachment mechanism. 51 is attached.

  The first fitting shaft member 51 includes a shaft portion that operates in a direction of expanding the diameter by inputting compressed air to the first fitting shaft member 51. It is comprised so that fitting to a hole part is possible. That is, the attachment / detachment mechanism includes the first fitting shaft member 51 and the first fitting hole member 41 as a pair.

  The screw tightening tool 10 includes the bit holding unit 30, a rotation driving unit 20 including an AC servo motor, and a tool holding plate 40 that directly connects the rotation driving unit 20 and the bit holding unit 30.

  The rotational drive unit 20 includes a speed reducer connected to the AC servomotor and a torque sensor built in the speed reducer for torque conversion of the rotational load of the AC servomotor. Ba is directly connected without relative movement in the axial direction.

  The bit holding unit 30 includes a connecting shaft 32 that rotatably supports the bit Ba and the rotation driving unit 20, a cylindrical guide 33 that rotatably supports the connecting shaft 32 and the bit Ba, A screw guide 34 that slides in the axial direction with respect to the cylindrical guide 33 and includes the tip of the bit Ba, and a screw guide cushion spring 35 that constantly biases the screw guide 34 downward are provided. The cylindrical guide 33 is connected to an air suction means 36 which is arranged on the outer shape and sucks air from the tip of the screw guide 34.

  The tool holding plate 40 extends in a direction orthogonal to the axis line of the bit Ba, and has two slide shafts 43a and 43b standing so as to sandwich the rotation driving unit 20 attached thereto. The slide shafts 42a and 42b are provided with bit cushion springs 43a and 43b inserted therethrough, and the bit cushion springs 43a and 43b are arranged so that their one ends are always in contact with the tool holding plate 40, respectively. ing. The other ends of the bit cushion springs 43a and 43b are in contact with a first sliding plate 45 which is inserted through the slide shafts 42a and 42b and slides in a direction in which the bit cushion springs 43a and 43b are compressed and bent.

  The first sliding plate 45 is formed by fixing bushes 44a and 44b inserted through the slide shafts 42a and 42b and the first fitting hole member 41 on the upper surface thereof. Accordingly, the first sliding plate 45 can be integrated with or detached from the first fitting shaft member 51 attached to the robot 50. The first fitting hole member 41 is fixed to the upper surface of the first sliding plate 45, but may be replaced with the first fitting shaft member 51. In this case, the first fitting hole member 41 is replaced with the first fitting hole member 41. The hole member 41 may be fixed to the robot 50.

  The screw tightening operation of the automatic screw tightening apparatus 1 shown in FIGS. 1, 4 to 6 will be described below with reference to FIGS. 4 to 6. In response to a command from the control device, the robot 50 approaches a screw feeder (not shown) in which the screw S is suspended. At this time, the control device sends an operation command to the air suction means 36 to suck air from the tip of the screw guide 34. As a result, the screw S is sucked into the screw guide 34 and engaged with the bit Ba in the screw guide 34. As described above, when the screw S is supplied to the screw tightening tool 10, the robot 50 moves so that the tip of the screw guide 34 approaches the female screw Wa of the work W that has been previously taught as shown in FIG. . At this time, the AC servomotor is driven to rotate in response to a command from the control device, so that the bit Ba and the screw S engaged therewith rotate within the screw guide 34.

  Subsequently, as shown in FIG. 5, the robot 50 moving to the female screw Wa moves the bit cushion springs 43 a and 43 b and the screw guide cushion spring 35 at the time when the tip of the screw S comes into contact with the workpiece W. If it moves to the position which bends in the direction to compress, it will stop on that spot and will stop until the screw S reaches a predetermined torque. At this time, the bit Ba is rotated in a direction in which the screw S is screwed into the female screw Wa while exerting a thrust according to the deflection amount of the bit cushion springs 43a and 43b.

  As a result, the tool holding plate 40 starts to move relative to the first sliding plate 45 connected to the robot 50 in a stopped state, and the cylindrical guide is moved in accordance with the amount of screw S inserted into the female thread Wa. 33, the bit Ba is lowered. Eventually, the screw S is brought into close contact with the surface of the workpiece W and fastened with a predetermined torque.

  Next, the configuration of the automatic screw tightening device 1 shown in FIGS. 2 and 7 and FIG. 3 will be described. The automatic screw tightening device 1 in two different forms enables the rotation drive unit 20 and the bit holding unit 30 to be attached to and detached from those shown in FIGS. 1, 4 to 6. . Further, in the automatic screw tightening device 1 shown in FIGS. 2, 7, and 3, the common points are the same as those of the first fitting shaft member 51 and the first fitting hole member 41. It is possible to confirm that the rotation driving unit 20 and the bit holding unit 30 are connected to each other, although the configuration includes a second fitting shaft member 48 and a second fitting hole member 38 which will be described later. There is a difference in that a fitting confirmation sensor 60 described later is provided and a structure for moving the screw guide 34 relative to the bit Bb. In the following description of the automatic screw tightening device 1 shown in FIGS. 2, 7 and 3, the same parts as those of the automatic screw tightening device shown in FIGS. I will omit the explanation.

  First, the common structure of the automatic screw fastening device 1 shown in FIGS. 2 and 7 and FIG. 3 will be described. The rotation driving unit 20 of the automatic screw fastening device 1 includes a connecting part 21 that can connect a bit holding part 30 instead of the connecting shaft 32, and the connecting part 21 is always urged by a spring and the bit Bb. A hexagonal hole is provided to fit at one end. The connecting portion 21 includes a dog that abuts one end of the spring and projects an outer diameter, and a fitting confirmation sensor 60 that detects the dog is integrally attached to the tool holding plate 40 via a bracket. Yes. That is, the bit holding part 30 of the automatic screw tightening device 1 shown in FIGS. 2, 7, and 3 does not include the connecting shaft 32, and one end of the bit Bb is a connecting part of the rotation driving unit 20. 21 can be fitted.

  In addition, the automatic screw tightening device 1 includes a second fitting shaft member 48 to which the rotation driving unit 20 and the bit holding unit 30 can be attached and detached, and a second fitting to be fitted to the second fitting shaft member 48. In the present embodiment, the second fitting shaft member 48 is attached to the lower surface of the tool holding plate 40, and the second fitting hole member 38 is attached to the upper surface of the bit holding plate 31. It consists of The mounting positions of the second fitting shaft member 48 and the second fitting hole member 38 may be switched.

  Next, the structure which is not common in the automatic screw fastening apparatus 1 shown in FIG. 2, FIG. 7, and FIG. 3 is demonstrated. The bit holder 30 of the automatic screw tightening device 1 shown in FIGS. 2 and 7 has substantially the same configuration as the bit holder of the automatic screw tightening device shown in FIGS. A screw guide cushion spring 35 is arranged inside. On the other hand, the bit holding portion 30 of the automatic screw fastening device 1 shown in FIG. 3 includes the bit holding plate 31, the second fitting hole member 38 attached to the upper surface of the bit holding plate 31, and the bit holding plate. Rotating bracket 71 attached to the lower surface of 31 and rotatably supporting the bit Bb; a screw guide 34 including the bit Bb; struts 72a and 72b erected on the screw guide 34; Screw guide cushion springs 35a and 35b that are inserted into the bit holding plate 31 and the tool holding plate 40, respectively, and guides that are inserted into the columns 72a and 72b and attached to the bit holding plate 31, respectively. Bush 73a, 73b is provided. The screw guide 34 is connected to an air suction means 36 that is arranged on the outer shape of the screw guide 34 and sucks air from the tip of the screw guide 34. Therefore, in the automatic screw tightening device 1 shown in FIG. 3, since the screw guide 34 is always urged downward by the screw guide cushion springs 35a and 35b, the screw guide 34 is relatively moved upward with respect to the bit Bb. It is configured to be possible.

  The connection operation between the rotation driving unit 20 and the bit holding unit 30 of the automatic screw fastening device 1 shown in FIG. 2 will be described with reference to FIG. As shown in FIG. 7, the robot 50 is in a state in which the rotation driving unit 20 is integrally fixed, and moves to a suspension plate 101 in which a plurality of the bit holding units 30 are suspended. As a result, the second fitting shaft member 48 is fitted into the second fitting hole member 38 of the bit holding portion 30 and is integrated with the second fitting hole member 38. At this time, if the phase of one end of the bit Bb and the hexagonal hole of the connecting portion 21 do not coincide with each other and the connecting portion 21 rides on one end of the bit Bb, the fitting confirmation sensor 60 is connected to the connecting portion 21. This dog is not detected. Therefore, the control device rotates the AC servo motor until a signal indicating that the dog has been detected is received from the fitting confirmation sensor 60. As a result, the bit Bb and the connecting portion 21 are completed, and the robot 50 returns to a state where the screw tightening operation can be performed.

DESCRIPTION OF SYMBOLS 1 ... Automatic screw fastening apparatus 10 ... Screw fastening tool 20 ... Rotation drive part 30 ... Bit holding part 31 ... Bit holding plate 38 ... 2nd fitting hole member 40 ... Tool holding plate 41 ... 1st fitting hole member 43a, 43b ... Bit cushion spring 45 ... First sliding plate 48 ... Second fitting shaft member 50 ... Robot 51 ... First fitting shaft member Ba, Bb ... Bit S ... Screw W ... Workpiece

Claims (2)

A screw tightening tool having a rotatable bit that engages with a screw that is fastened to a workpiece, and a robot that has an attaching / detaching mechanism that can attach and remove the screw tightening tool and that can be controlled to move to a predetermined position in response to a command from a control device In the automatic screw tightening device composed of
The screw tightening tool includes a bit holding unit configured to rotatably support the bit, and a rotation driving unit that is attached to the bit holding unit and applies rotation to the bit.
The rotation driving unit and the bit holding unit are directly connected via a tool holding plate extending in a direction orthogonal to the axis of the bit,
The tool holding plate has a slide shaft erected thereon, a bit cushion spring that is inserted through the slide shaft and constantly contacts the tool holding plate, a bush that is inserted through the slide shaft, and the bush. A first sliding plate arranged parallel to the tool holding plate,
The attachment / detachment mechanism is a first attachment / detachment mechanism that connects or disconnects the first sliding plate and the robot,
The first attaching / detaching mechanism includes a first fitting shaft member that operates in a direction in which the diameter is increased by input of compressed air, and a first fitting hole member that is fitted to the first fitting shaft member.
The automatic screw tightening device, wherein the robot and the first sliding plate are provided with either the first fitting shaft member or the first fitting hole member. The rotation driving unit includes a polygonal fitting unit that connects the bit holding unit,
The bit holding unit includes a bit holding plate that rotatably supports the bit and is arranged in parallel to the tool holding plate,
The attachment / detachment mechanism includes the first attachment / detachment mechanism and a second attachment / detachment mechanism that connects or disconnects the bit holding plate and the tool holding plate.
The second attaching / detaching mechanism includes a second fitting shaft member that operates in a direction in which the diameter is increased by input of compressed air, and a second fitting hole member that is fitted to the second fitting shaft member,
The automatic screw tightening device according to claim 1, wherein the bit holding plate and the tool holding plate include either the second fitting shaft member or the second fitting hole member.

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