JP6817859B2 - Automatic screw tightening device - Google Patents

Description

The present invention relates to an automatic screw tightening device capable of exchanging a bit or a rotary drive unit that rotationally applies to the bit according to the type or size of the screw.

As shown in Patent Document 1, a conventional automatic screw tightening device includes a rotary drive unit that applies a rotational force to a bit that engages with a screw, and a bit holding unit that rotatably and slidably supports the bit. A screw tightening tool having a screw tightening tool, a robot that can hold the screw tightening tool in an openable and closable hand and move to a predetermined position, and a control that is connected to the screw tightening tool and the robot by wiring and gives a drive command to each of them. It consists of a device. Further, the screw tightening tool includes a attachment / detachment mechanism that enables attachment / detachment of the bit holding portion and the rotation drive portion.

The attachment / detachment mechanism includes an air cylinder arranged on a base to which the rotation drive unit is fixed, an outer cylinder that can move in the axial direction via a floating joint connected to the air cylinder, and an inner peripheral surface of the outer cylinder. Alternatively, it is composed of an inner cylinder that is loosely fitted with a steel ball that engages with the tapered surface. When the steel ball comes into contact with the inner peripheral surface of the outer cylinder, it is positioned inward so as to protrude from the inner peripheral surface of the inner cylinder, while when it comes into contact with the tapered surface of the outer cylinder, the outer circumference of the inner cylinder is opposite to the previous one. It is located outward so that it protrudes from the surface.

The bit holding portion has a compression spring that constantly 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 the bit is fixed and fitted into the torque transmission shaft. It consists of a socket that slides in the axial direction while being fitted, and a connecting portion that is arranged above the socket and has an engaging groove that is inserted into the inner cylinder and engages with the steel ball.

The rotary drive unit is formed by integrally rotatably attaching an output shaft inserted into the inner cylinder, and has a tip shape in which the output shaft fits into the socket.

The conventional automatic screw tightening device configured in this way has a feature that since different types of screw tightening tools can be gripped by the hand of the robot, it can be easily handled even when the screw is changed.

Further, the conventional automatic screw tightening device is configured to fit the steel ball into the engaging groove of the connecting portion by operating the cylinder and abut on the inner peripheral surface of the outer cylinder, so that the bit is held. The unit and the rotation drive unit can be attached and detached. As a result, there is also a feature that the degree of freedom in combination of the bit holding portion and the rotation driving portion constituting the screw tightening tool is high.

International Patent Publication No. WO2015 / 140939

However, in the conventional automatic screw tightening device, the robot is moved to a predetermined position to rotate the screw engaged with the bit while pressing it against the work. At this time, the compression spring in a flexed state returns 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. Sliding 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 slides smoothly. There was a problem that it was difficult to obtain.

Further, in the conventional automatic screw tightening device, since the bit holding portion and the rotation driving portion are connected by a steel ball provided with a spherical surface, the bit holding portion tends to tilt following the spherical surface of the steel ball, and accordingly. There is also a problem that the bit engaged with the screw is easily tilted.

A screw tightening tool equipped with a rotatable bit that engages with the screw to be fastened to the work, and a robot equipped with a detachable mechanism for attaching and detaching this screw tightening tool and capable of moving to a predetermined position in response to a command from the control device. In the automatic screw tightening device composed of the above, the screw tightening tool includes a bit holding portion formed by rotatably supporting the bit and a polygonal fitting portion connecting the bit holding portion, and the bit is connected to the bit. A rotation drive unit that imparts rotation is provided, and the rotation drive 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, and the tool holding unit is provided. The plate is a slide shaft erected on the slide shaft, a bit cushion spring inserted through the slide shaft and always in contact with the tool holding plate, a bush inserted through the slide shaft, and the bush are integrally attached to hold the tool. A first sliding plate arranged parallel to the plate is provided, and the bit holding portion includes a bit holding plate that rotatably supports the bit and is arranged parallel to the tool holding plate. The attachment / detachment mechanism includes a first attachment / detachment mechanism for connecting or disconnecting the first sliding plate and the robot, and a second attachment / detachment mechanism for connecting or disconnecting the bit holding plate and the tool holding plate. The first attachment / detachment mechanism is composed of a first fitting shaft member that operates in a direction of increasing the diameter by inputting compressed air, and a first fitting hole member that fits into the first fitting shaft member. is configured, the robot and the first slide plate, said formed includes any of the first fitting shaft member or the first fitting hole member is, the second detachable mechanism, expanding the input of compressed air The bit holding plate and the tool holding plate are composed of a second fitting shaft member that operates in the radial direction and a second fitting hole member that fits into the second fitting shaft member. automatic screw clamping device characterized by forming isosamples comprise any fitting shaft member or the second fitting hole member.

As described above, the automatic screw tightening device of the present invention has a configuration in which a bit is directly connected to the rotation drive unit and is provided with a first sliding plate that is cut off 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.

Further, the automatic screw tightening device of the present invention has a first attachment / detachment mechanism that enables attachment / detachment of the robot and the tool holding plate, or in addition to the first attachment / detachment mechanism, attachment / detachment of the bit holding plate and the tool holding plate. It is provided with a second attachment / detachment mechanism that enables it. This also has the advantage that the automatic screw tightening device of the present invention can be a different type of screw tightening tool for the robot, or the combination of the bit holding portion or the rotation driving portion constituting the screw tightening tool can be changed. Moreover, since the automatic screw tightening device of the present invention has a structure in which a steel ball is not used at the connecting portion between the bit holding portion and the rotation driving portion, there is an advantage that the problem that the bit is easily tilted as in the conventional case can be solved.

It is a schematic explanatory drawing which shows one Embodiment which concerns on this invention. (A) is a cross-sectional view showing a main part, and (b) is a partially cutaway cross-sectional view of (a) viewed 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 a main part, and (b) is a partial notched sectional view of (a) viewed from the front. It is a schematic explanatory drawing which shows the other embodiment which concerns on this invention. (A) is a partially cutaway sectional view showing a main part, and (b) is a partial notched sectional view of (a) viewed from the front. It is operation | movement explanatory drawing of screw tightening work by the screw tightening tool of FIG. (A) is a cross-sectional view of a main part showing an early stage of a screw tightening operation of sucking a screw and tightening a screw to a work, and (b) is a partially cutaway cross-sectional view of (a) viewed from the front. It is an operation explanatory view which shows the middle part of the screw tightening work which proceeded from FIG. (A) is a cross-sectional view of a main part showing a time point when the sucked screw abuts on the work and the bit cushion spring is bent, and (b) is a partially cutaway cross-sectional view of (a) viewed from the front. .. It is an operation explanatory view which shows the latter half of the screw tightening work which proceeded from FIG. (A) is a cross-sectional view of a main part showing a time point when a screw is screwed into a work and the bit cushion spring is being restored, and (b) is a partially cutaway cross-sectional view of (a) viewed from the front. It is explanatory drawing for demonstrating the connection of a rotation drive part and a bit holding part. (A) is a partially cutaway cross-sectional explanatory view showing a main part, and (b) is a schematic explanatory view of (a) viewed from the front.

Hereinafter, an embodiment of the automatic screw tightening device according to the present invention will be described with reference to FIGS. 1 to 7. The automatic screw tightening device 1 is provided on the work W and is configured to fasten the screw S screwed to the screw Wa with a predetermined torque, and is a bit Ba (Bb) that can be fitted into the drive hole of the screw S. A screw tightening tool 10 having a bit holding portion 30 rotatably provided with a) and a rotation driving portion 20 for imparting rotation to the bit Ba (Bb), a robot 50 to which the screw tightening tool 10 can be attached and detached, and the robot 50. It is composed of a robot 50 and a control device (not shown) that controls the screw tightening tool 10. Further, as an example of the automatic screw tightening device 1 according to the present invention, there are various forms such as those shown in FIGS. 1, 4 to 6, those shown in FIG. 2, and those shown in FIGS. 3 and 7. The automatic screw tightening devices having different forms shown below will be described in order below.

First, the automatic screw tightening device 1 shown in FIGS. 1, 4 to 6 makes it possible to replace the screw tightening tool of a different form with the robot 50 by changing the screw S to be fastened to the work W. The robot 50 of the automatic screw tightening device 1 can be replaced with a screw tightening tool in which the combination of the bit holding portion 30 and the rotary drive portion 20 is fixed and cannot be changed, and a plurality of different forms supported by the support plate 100 are different. It is configured so that a screw tightening tool can be attached. Further, the robot 50 has a configuration having multiple joints, a plurality of slide tables (not shown) that move to XYZ coordinates, and the like, and is a first fitting shaft member that forms a part of the attachment / detachment mechanism. It consists of 51 attached.

The first fitting shaft member 51 includes a shaft portion that operates in a direction of increasing the diameter by inputting compressed air to the first fitting shaft member 51, and the first fitting hole member 41 that forms another part of the attachment / detachment mechanism. It is configured so that it can be fitted into the hole. That is, the attachment / detachment mechanism is configured by pairing the first fitting shaft member 51 and the first fitting hole member 41.

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

The rotation drive unit 20 includes a speed reducer connected to the AC servo motor and a torque sensor built in the speed reducer to convert torque of the rotational load of the AC servo motor, and the bit of the bit holding unit 30. It is directly connected without moving Ba relative to the axial direction.

The bit holding portion 30 includes a connecting shaft 32 that connects the bit Ba and the rotation driving unit 20 and is rotatably supported, a cylindrical guide 33 that rotatably supports the connecting shaft 32 and the bit Ba, and the like. It includes 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 urges the screw guide 34 downward. Further, the cylindrical guide 33 is arranged on the outer shape thereof and is connected to an air suction means 36 that sucks air from the tip of the screw guide 34.

The tool holding plate 40 extends in a direction orthogonal to the axis of the bit Ba, and two slide shafts 43a and 43b are erected so as to sandwich the rotary drive unit 20 attached to the tool holding plate 40. Further, the slide shafts 42a and 42b are arranged with bit cushion springs 43a and 43b inserted therein, and the bit cushion springs 43a and 43b are arranged so that one ends thereof 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 that is inserted through the slide shafts 42a and 42b and slides in a direction that compresses and bends the bit cushion springs 43a and 43b.

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 to the upper surface thereof. As a result, the first sliding plate 45 can be integrated with or detached from the first fitting shaft member 51 attached to the robot 50. Although the first fitting hole member 41 is fixed to the upper surface of the first sliding plate 45, it may be replaced with the first fitting shaft member 51. In this case, the first fitting The joint hole member 41 may be fixed to the robot 50.

The screw tightening operation of the automatic screw tightening device 1 shown in FIGS. 1, 4 to 6 thus configured 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 engages with the bit Ba in the screw guide 34. When the screw S is supplied to the screw tightening tool 10 in this way, the robot 50 moves so as to bring the tip of the screw guide 34 closer to the female screw Wa of the work W taught in advance as shown in FIG. .. Further, at this time, since the AC servomotor is rotationally driven in response to a command from the control device, the bit Ba and the screw S engaged with the bit Ba rotate in the screw guide 34.

Subsequently, as shown in FIG. 5, the robot 50 that moves to the female screw Wa uses the bit cushion springs 43a and 43b and the screw guide cushion spring 35 at the time when the tip of the screw S comes into contact with the work W. When it moves to a position where it bends in the direction of compression, it stops on the spot and keeps the screw S stopped until it reaches a predetermined torque. Further, at this time, the bit Ba rotates the screw S in the direction of screwing into the female screw Wa while exerting a thrust corresponding to the amount of bending 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 the stopped state, and the cylindrical guide is increased as the screw S is screwed into the female screw Wa. Bit Ba is lowered together with 33. Eventually, the head bearing surface of the screw S is brought into close contact with the surface of the work W, and the screw S is 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 having these two different forms enables the rotation drive unit 20 and the bit holding unit 30 to be attached to and detached from each other, unlike those shown in FIGS. 1, 4 to 6 described above. .. Further, in the automatic screw tightening device 1 shown in FIGS. 2 and 7 and FIG. 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 drive unit 20 and the bit holding unit 30 are connected to each other, while the second fitting shaft member 48 described later and the second fitting hole member 38 described later are provided, respectively. The point that the fitting confirmation sensor 60 is provided and the structure that the screw guide 34 is relatively moved with respect to the bit Bb are different. In explaining the automatic screw tightening device 1 shown in FIGS. 2 and 7 and FIG. 3, the same parts as those of the automatic screw tightening device shown in FIGS. 1, 4 to 6 already described will be described. I will omit the explanation.

First, the common structure of the automatic screw tightening device 1 shown in FIGS. 2 and 7 and FIG. 3 will be described. The rotary drive unit 20 of the automatic screw tightening device 1 includes a connecting portion 21 capable of connecting a bit holding portion 30 instead of the connecting shaft 32, and the connecting portion 21 is constantly urged by a spring and the bit Bb. It has a hexagonal hole that fits into one end of the. Further, the connecting portion 21 includes a dog that is in contact with one end of the spring and has an outer diameter overhanging, and a fitting confirmation sensor 60 that detects this dog is integrally attached to the tool holding plate 40 via a bracket. There is. That is, the bit holding portion 30 of the automatic screw tightening device 1 shown in FIGS. 2 and 7 and FIG. 3 does not include the connecting shaft 32, and one end of the bit Bb is a connecting portion of the rotation driving unit 20. It is configured so that it can be fitted to 21.

Further, the automatic screw tightening device 1 has a second fitting shaft member 48 to which the rotation driving unit 20 and the bit holding portion 30 can be attached and detached, and a second fitting that fits the second fitting shaft member 48. A hole member 38 is provided, and 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. Consists of. The mounting positions of the second fitting shaft member 48 and the second fitting hole member 38 may be interchanged.

Next, a structure that is not common to the automatic screw tightening device 1 shown in FIGS. 2 and 7 and FIG. 3 will be described. The bit holding portion 30 of the automatic screw tightening device 1 shown in FIGS. 2 and 7 has substantially the same configuration as the bit holding portion of the automatic screw tightening device shown in FIGS. 1, 4 to 6 described above, and has a screw guide 34. A screw guide cushion spring 35 is arranged inside. On the other hand, the bit holding portion 30 of the automatic screw tightening 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. A rotating bracket 71 attached to the lower surface of the 31 and rotatably supporting the bit Bb, a screw guide 34 including the bit Bb, columns 72a and 72b erected on the screw guide 34, and the columns. The screw guide cushion springs 35a and 35b, which are inserted into the bit holding plate 31 and the tool holding plate 40 at all times, and the guides which are inserted into the columns 72a and 72b and attached to the bit holding plate 31, respectively. The bushes 73a and 73b are provided. Further, the screw guide 34 is arranged on the outer shape thereof and is connected to an air suction means 36 that 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 constantly 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 drive unit 20 and the bit holding unit 30 of the automatic screw tightening device 1 shown in FIG. 2 described above will be described with reference to FIG. As shown in FIG. 7, the robot 50 is in a state where the rotation driving unit 20 is integrally fixed, and moves the bit holding units 30 to a hanging 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 phases of one end of the bit Bb and the hexagonal hole of the connecting portion 21 do not match 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. The dog is not detected. Therefore, the control device rotates the AC servomotor until it receives a signal from the fitting confirmation sensor 60 that the dog has been detected. As a result, the bit Bb and the connecting portion 21 are completed, and the robot 50 returns to be in a state where the screw tightening work can be performed.

1 ... Automatic screw tightening device 10 ... Screw tightening tool 20 ... Rotation drive unit 30 ... Bit holding unit 31 ... Bit holding plate 38 ... Second fitting hole member 40 ... Tool holding plate 41 ... First fitting hole members 43a, 43b ... Bit cushion spring 45 ... 1st sliding plate 48 ... 2nd fitting shaft member 50 ... Robot 51 ... 1st fitting shaft member Ba, Bb ... Bit S ... Screw W ... Work

Claims (1)

A robot that has a screw tightening tool equipped with a rotatable bit that engages with the screw to be fastened to the work, and a attachment / detachment mechanism that allows the screw tightening tool to be attached / detached, and can be moved to a predetermined position in response to a command from the control device. In the automatic screw tightening device composed of
The screw tightening tool includes a bit holding portion that rotatably supports the bit, a polygonal fitting portion that connects the bit holding portion, and a rotation driving portion that imparts rotation to the bit. Made up of
The rotation drive 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 is integrally attached with a slide shaft erected on the slide shaft, a bit cushion spring inserted through the slide shaft and constantly in contact with the tool holding plate, a bush inserted through the slide shaft, and the bush. A first sliding plate arranged parallel to the tool holding plate is provided.
The bit holding portion includes a bit holding plate that rotatably supports the bit and is arranged in parallel with the tool holding plate.
The attachment / detachment mechanism includes a first attachment / detachment mechanism that connects or disconnects the first sliding plate and the robot, and a second attachment / detachment mechanism that connects or disconnects the bit holding plate and the tool holding plate. Being done
The first attachment / detachment mechanism is composed of a first fitting shaft member that operates in a direction of increasing the diameter by inputting compressed air, and a first fitting hole member that fits into the first fitting shaft member.
The robot and the first sliding plate, Ri formed comprises one of the first fitting shaft member or the first fitting hole member,
The second attachment / detachment mechanism is composed of a second fitting shaft member that operates in a direction of increasing the diameter by inputting compressed air, and a second fitting hole member that fits into the second fitting shaft member.
The bit holding plate and said tool holding plate, automatic screwing device according to claim formed isosamples comprise any of the second engaging shaft member or the second fitting hole member.

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