JPH0794092B2 - Automatic screw tightener - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of an automatic screw tightening machine provided with a novel lifting drive source for lifting a driver bit for tightening a screw.

[Prior Art] and [Problems to be Solved by the Invention] Generally, in the case of an automatic screw tightener that tightens a screw on a work, a driver bit that rotates by receiving the rotation of a drive motor starts descending due to the operation of a cylinder, and tightens. When the work is completed, the cylinder is returned to move up and down. In this type of screw tightener, the descending speed of the driver bit is determined by the moving speed of the rod of the cylinder, and because a large impact load is applied when the rod reaches the lowermost end, the moving speed of the driver bit is increased above a predetermined speed. However, there is a drawback that the cycle time required for screw tightening cannot be shortened beyond a certain level.

As a device for eliminating this drawback, an automatic screw fastening machine described in Japanese Patent Application No. 1-167681 has been invented. This automatic screw tightening machine 1 has a column 2 fixed to a base (not shown) as shown in FIG. 4, and a driver base 6 and a chuck base 7 are movable along the column 2. You are being guided.
A driver bit 11 that is rotated by the rotation of the drive motor 9 is attached to the driver base 6. A chuck body 13a, through which the driver bit 11 is inserted, is rotatably attached to the chuck base 7, and a tip end is closed by a spring (not shown) so as to close the moving path of the driver bit 11. A chuck unit 13 including a pair of biased chuck claws 13b is fixed. further,
A roller shaft 18 extending in parallel with the driver bit 11 is rotatably arranged in the column 2 and is configured to be rotatable by receiving rotation of a lifting rotary drive source 24 fixed to an upper end of the column 2. There is. The roller shaft 18 has a rotating roller.
The roller shafts 16 and 17 are fixed to the driver base 6 and the chuck base 7 at predetermined intervals.
The rotating rollers 16 and 17 are configured to rotate integrally with the rotation of 18. The driver base 6 side,
Circumferential cam grooves 16a, 17 composed of a descending curve portion having a predetermined descending stroke and an ascending curve portion having a predetermined ascending stroke are provided on the outer periphery of each of the rotating rollers 16, 17 on the chuck base 7 side.
a is removed, and the lower stroke of the circumferential cam groove 16a on the driver base 6 side is longer than the lower stroke of the circumferential cam groove 17a on the chuck base 7 side. Moreover, the cam followers 15, 15a mounted on the driver base 6 side and the chuck base 7 side are respectively attached to the circumferential cam grooves 16a, 17a.
Are arranged so as to be fitted to each other, and the driver base 6 and the chuck base 7 are configured to move integrally at a predetermined interval and after the chuck base 7 is stopped, the driver base 6 alone moves. In this automatic screw tightener 1, the type of work is changed, the height position of the work surface is changed, and when adjusting the distance between the work and the lower end of the chuck unit 13,
It is necessary to change the stop positions of the driver base 6 and the chuck base 7. In this case, the rotary shaft 1
Because 6,17 are fixed at fixed intervals, only the driver base 6 and the chuck base 7 cannot be moved,
It is necessary to screw the height adjusting bolts at four places on the bottom of the column 2 and rotate the bolts to move the entire column 2 up and down. Therefore, not only a large number of workers are required for this work, Each time, it is necessary to confirm whether or not the column 2 is upright with respect to the base, and this kind of work becomes troublesome, and there is a demand for a device that can easily perform this kind of work.

The present invention has been made in view of the above demands, and is an automatic screw that improves a lifting drive source that raises and lowers a driver bit that tightens a screw on a work and enables a worker to easily change the position of a work surface by himself. It is intended to provide a tightening machine.

[Means for Solving the Problems] In order to achieve the above object, a driver table and a chuck table are movably guided along a column. A driver bit that rotates in response to the rotation of the drive motor is mounted on the driver base, and a chuck body through which the driver bit is inserted and a chuck base are rotatably mounted on the chuck base and the tip of the driver bit is closed by a spring. A chuck unit including a pair of chuck claws biased so as to block the moving path is attached.

A roller shaft extending in parallel with the driver bit is rotatably arranged on the column in response to the rotation of the lifting rotary drive source, and the roller shaft has positions corresponding to the driver base and the chuck base. The rotating roller provided with a circumferential cam groove having a predetermined lifting stroke is arranged so as to rotate integrally. Further, the rotary roller is arranged so as to be movable in the axial direction with respect to the roller shaft with a spacer interposed therebetween, and these two rotary rollers are pressed by a lock nut screwed at the vertical position of the roller shaft. Fixed to the roller shaft. Further, cam followers attached to the driver base side and the chuck base side are respectively fitted and positioned in the respective circumferential cam grooves, and the cam followers move up and down as the rotary roller rotates. .

[Operation] In the above automatic screw tightener, when the type of the desired work is changed and the height position of the work surface is changed, the worker loosens one of the nuts screwed to the roller shaft, The rotation roller on the driver table side or the rotation roller on the chuck table side is moved to a predetermined position along the roller shaft. As a result, the cam followers fixed to the driver base and the chuck base respectively and fitted in the circumferential cam grooves of the rotating roller move. Therefore, the driver table and the chuck table move along the slide guide, reach the position immediately before the chuck table comes into contact with the workpiece, and stop, so that it is possible to correspond to a new height position of the work surface. Then, the other lock nut is tightened, and the lock nuts at the upper and lower positions of the roller shaft can be fixed to the roller shaft by pinching the two rotating rollers.

In this state, when the screw tightening start command signal is output, the drive motor rotates and the driver bit rotates, and the rotating roller rotates by one rotation in response to the rotation of the lifting rotary drive source. During this time, since the cam followers attached to the driver base side and the chuck base side are fitted in the circumferential cam grooves on the outer periphery of the rotating roller, the cam followers move along the circumferential cam grooves of the rotating roller, and The table and chuck table are lowered. At this time, it can be stopped immediately before the chuck table descends a predetermined stroke and contacts the work. Even after that, the driver base descends, so that the driver bit integrated with the driver base can be inserted through the chuck unit and the screw held by the chuck claw can be tightened on the work. Even after the screw tightening is completed, each cam follower moves along the circumferential cam groove, and the driver base and the chuck base are lifted and returned to prepare for the next work.

Embodiments Embodiments will be described below with reference to the drawings. In FIG. 1, reference numeral 1 is an automatic screw tightening machine, which has a column 2 fixed upright on a base 1a. Two slide guides 3 extending in parallel along the upright surface are fixed to the column 2. First sliders 4a, 4a are respectively mounted on the slide guides 3 so as to be able to move up and down, and the slide guides 3 are mounted on the first sliders 4a, 4a via a first mounting member 5a fixed over them. A driver base 6 extending in a direction intersecting with is attached. Further, second sliders 4b, 4b are mounted on the slide guide 3 so as to be able to move up and down, and the second sliders 4b, 4b are parallel to the driver base 6 via a second mounting tool 5b fixed over them. The chuck base 7 extending to the position is fixed therebelow. A drive motor 9 is fixed to the driver base 6 via a motor mounting base 8 with its drive shaft 9a downward, and the drive shaft 9a is connected to the slide guide 3 via a transmission gear mechanism 10. Driver bits 11 extending in parallel are connected so as to rotate together.

A chuck unit 13 is fixed to the lower surface of the chuck base 7 via a mounting plate 12. The chuck unit 13 is provided with a chuck body 13a through which the driver bit 11 can be inserted and a rotatably rotatably supported by the chuck body 13a, and a spring (not shown) closes the tip to close the moving path of the driver bit 11. It is composed of a pair of biased chuck claws 13b, and one screw is air-fed from a supply hose (not shown) to a screw holding hole (not shown) formed by the pair of chuck claws 13b. Is configured. Cam followers 15 and 15a are rotatably attached to the driver base 6 and the chuck base 7 via a support tool 14 so as to project in the extending direction, and these cam followers 15 and 15a are respectively cut on the column 2. Column 2 from the cutout window 2a
Circumferential cam grooves 16a, 1 of rotating rollers 16,17 that reach inside
It is configured to fit into 7a and roll.

On the other hand, a roller shaft 18 is erected and rotatably attached to the column 2 so as to be rotated by the rotation of a rotary shaft 19 described later. Rotating rollers 16 and 17 are attached to the roller shaft 18 at positions corresponding to the driver table 6 and the chuck table 7, respectively, and the rotating rollers 16 and 17 and the roller shaft 18 are fitted over these. Key (not shown) and locking bushing (not shown)
It is attached so as to rotate integrally with. The locking bushing is configured so that the rotating rollers 16 and 17 can be moved along the roller shaft 18 by loosening bolts (not shown) and fixed at any position.
The reason why the key and the locking bushing are used together when fixing the rotating rollers 16 and 17 to the roller shaft 18 is to eliminate any loss in torque transmission of the roller shaft 18. Further, the two rotary rollers 16 and 17 are configured to be fixed at arbitrary height positions by lock nuts 21a and 21b which are screwed onto the roller shaft 18 at upper and lower positions thereof.

As shown in FIG. 3a, the rotary roller 16 on the driver base 6 side is provided with a descending curve portion having a predetermined descending stroke, an ascending curve portion having a predetermined ascending stroke, and a straight portion having a predetermined length on the outer periphery thereof. A continuous circumferential cam groove 16a is formed, and the descending stroke of this descending curve portion is sufficiently longer and more gentle than the descending stroke of the circumferential cam groove 17a on the chuck base 7 side described later. Is configured. Further, the straight portion is configured to wait at that position until the driver base 6 reaches the lowermost position and the rear driver bit 11 completes the tightening. Moreover, the cam follower 15 fixed to the driver base 6 side is fitted in the circumferential cam groove 16a, and when the cam follower 15 rolls along the descending curve portion as the rotation roller 16 rotates, the cam follower 15 is lowered. It is configured so that it is pushed downwards and is pushed upwards when rolling along the rising curve portion.

The rotation roller 17 on the chuck base 7 side is shown in FIG.
Similarly, a continuous circumferential cam groove 17a having a descending curve portion having a predetermined descending stroke, an ascending curve portion having a predetermined ascending stroke, and a straight portion having a certain length is cut out on the outer periphery thereof as shown in FIG. The descending stroke of the descending curve portion is formed to have a length required to descend the tip of the chuck unit 13 by a predetermined distance. Further, the linear portion is configured to wait at that position until the driver bit 11 completes the tightening after the chuck base 7 reaches the lowermost position. Further, the rising curve portion is formed so that the starting time of the rising stroke is earlier than the circumferential cam groove 16a on the driver base 6 side, and when the rising stroke on the driver base 6 side is started, it is almost half. It is formed so as to reach a position where it ascends and returns. Further, the ascending curve portion of the circumferential cam groove 17a on the chuck base 7 side has a straight line portion, and the chuck base 7 is temporarily stopped during the ascending and waits for the driver base 6 to ascend, and then re-ascends to the driver base. 6 and the chuck base 7 are configured to return to their original positions.

On the other hand, below the roller shaft 18, as shown in FIG. 2, a rotary shaft 19 extending in a direction intersecting with the roller shaft 18 is rotatable as a part of a lifting drive source 24 for transmitting rotation to the roller shaft 18. The electromagnetic clutch 19b is installed at one end of the
A driven sprocket 19a that transmits rotation from an external drive source (not shown) is fixed via the drive shaft, and the rotation shaft 19 is rotated by the rotation of the external drive source. The rotating shaft 19 and the roller shaft 18 are connected via a bevel gear mechanism 22 which is an example of a rotation transmitting mechanism, and the rotation of the rotating shaft 19 is transmitted to the roller shaft 18. Moreover, a pulse encoder 23 is connected to the other end of the rotary shaft 19 to detect the rotation angle of the rotary shaft 19,
One rotation of the roller shaft 18 is detected from the rotation angle of the rotation shaft 19, and when the roller shaft 18 makes one rotation, the electromagnetic clutch 19b is disengaged and the rotation of the rotation shaft 19 is stopped. The rotary drive source for raising and lowering may be directly connected to the roller shaft 18.

In the above automatic screw tightening machine, when the type of work is changed, the worker can lock the lock nuts 21a, 21
Loosen one of b and move the rotating rollers 16 and 17 in a desired direction. By the movement of the rotary rollers 16 and 17, the driver table 6 and the chuck table 7 are fixed on their respective sides and their circumferential cam grooves 16a,
Since the cam followers 15, 15a fitted to the 17a move, the driver table 6 and the chuck table 7 move along the slide guide 3. When the tip of the chuck unit 13 fixed to the chuck table 7 reaches the position immediately before contacting the desired work, the other lock nut 21 screwed onto the roller shaft 18 is engaged.
By tightening a or 21b, the two rotating rollers 16 and 17 can be clamped and fixed by the upper and lower lock nuts 21a and 21b of the roller shaft 18, and a new work can be dealt with.

In this state, when the work start command signal is received, the rotation from the external drive source is transmitted to the rotary shaft 19, and the roller shaft 18 moves to 1
It only rotates. While the roller shaft 18 makes one rotation, the rotating rollers 16 and 17 rotate integrally with the rotation of the roller shaft 18 without loss during torque transmission.
With the rotation of 6,17, the driver table 6 side, chuck table 7
Cam followers 15, 15a attached to the respective sides roll on the descending curve portions of the circumferential cams 16a, 17a on the outer circumferences of the rotating rollers 16, 17. Therefore, the cam followers 15 and 15a receive a force in the downward pressing direction, and the driver base 6 and the chuck base 7 are
Goes down. At this time, the predetermined descending stroke of the descending curve portion of the circumferential cam groove 16a of the rotating roller 16 on the driver table 6 side is longer than the descending stroke of the circumferential cam groove 17a of the rotating roller 17 on the chuck table 7 side. The chuck table 7 is stopped while the driver table 6 is being lowered, but the chuck table 7 can be stopped immediately before contacting the work. Further, since the circumferential cam groove 16a of the rotary roller 16 on the driver base 6 side has a straight line portion following the descending curve portion, the driver base 6 is lowered even after the chuck base 7 is stopped, and is lowered to the lowest position. Reach the position,
Wait at that position for a while so that the screw tightening time can be secured. Therefore, the chuck unit in which the driver bit 11 held on the driver base 6 is fixed to the chuck base 7
It can move forward with respect to 13 and come into contact with a screw (not shown) held by the chuck claw 13b, and this can be pushed out from the chuck claw 13b and tightened at a predetermined position.

When the screw tightening is completed, the drive motor 9 stops, while the driver base 6 and the chuck base 7 stop at that position for a while, and then the cam follower 15a on the chuck base 7 side moves to the rising curve portion of the circumferential cam groove 17a. After the chuck base 7 rolls up and the chuck base 7 rises with respect to the driver base 6,
And the driver base 6 is raised and returned to prepare for the next work.

EFFECTS OF THE INVENTION As described above, according to the present invention, the driver base that holds the driver bit, the cam follower that integrally moves the chuck base to which the chuck unit that holds the screw is fixed, and the circle to which these are fitted. It is moved up and down by an up-and-down drive source consisting of rotating rollers having a circumferential cam groove, and the rotating rollers are mounted so as to rotate integrally with the roller shaft and movable along the roller shaft, and these rotating rollers are pinched by a lock nut. Since it is configured to be fixed at any position, the moving speed of the driver base and chuck base can be changed arbitrarily by changing the rotation speed of the rotating roller, and the cycle time required for screw tightening work can be shortened arbitrarily. Not only can the work be performed, but even if the work is changed and the height position of the work surface is changed, the worker does not lock the nut. There is an advantage that the fixing position of the rotary roller can be easily changed only by loosening the blade to adjust the distance between the work and the lower end of the chuck unit. Further, according to the present invention, since it is not necessary to move the entire column up and down with respect to the base, it is not necessary to check whether or not the column is upright with respect to the base each time. There is an advantage that an easy device can be provided.

[Brief description of drawings]

1 is a longitudinal sectional view of an essential part for explaining the whole of the present invention, FIG. 2 is a sectional view of an essential part of FIG. 1, and FIGS. 3a and 3b are circumferential cam grooves of a disc cam according to the present invention. FIG. 4 is a partially cutaway view of the conventional example. 1 ... Automatic screw tightener, 1a ... base, 2 ... column, 2a ... notch window, 3 ... slide guide, 4a ... first slider, 4b ... second slider, 5a ... first Fixture, 5b ... Second fixture, 6 ... Driver base, 7 ... Chuck base, 8 ... Motor mount, 9 ... Drive motor, 9a ... Drive shaft, 10 ... Transmission gear mechanism, 11 ...... Driver bit, 12 …… Mounting plate, 13 …… Chuck unit, 13a …… Chuck body, 13b …… Chuck claw, 14 …… Supporting tool, 15, 15a …… Cam follower, 16 …… Rotary roller, 16a… … Circumferential cam groove, 17 …… Rotating roller, 17a …… Circumferential cam groove, 18 …… Roller shaft, 19 …… Rotating shaft, 19a …… Driven sprocket, 19b …… Electromagnetic clutch, 20 …… Spacer, 21a , 21b …… Lock nut, 22 …… Bevel gear mechanism, 23 …… Pulse encoder, 24 …… Rotation drive source for lifting,

Claims (1)

[Claims] 1. A driver base and a chuck base are movably guided along a column, and a driver bit which is rotated by a rotation of a drive motor is attached to the driver base, and the driver bit is inserted into the chuck base. Fixing a chuck unit composed of a chuck main body and a pair of chuck claws rotatably attached to the chuck main body and urged so as to close the moving path of the driver bit by closing the tip by a spring, while the driver is attached to the column. A roller shaft extending parallel to the bit is rotatably arranged in response to the rotation of the lifting rotary drive source, and is provided with a circumferential cam groove having a predetermined lifting stroke at a position corresponding to each of the driver base and the chuck base. The roller is arranged so as to rotate together with the roller shaft and movably in the direction in which the roller shaft extends with a spacer in between. A cam follower that fits in each of the circumferential cam grooves is attached to the base side and the chuck base side, and the two rotating rollers are pinched by a lock nut that is screwed onto the roller shaft at the upper and lower positions of the roller shaft. An automatic screw tightener characterized by being fixed to a shaft.