JPH0694096B2 - Automatic screw tightener - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic screw tightening machine equipped with a novel reciprocating drive source that gives a reciprocating motion to 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 for tightening a screw to a work, a driver bit that rotates by receiving rotation of a motor starts descending due to an operation of a cylinder, and tightening work When the above is completed, it is configured to return to the ascending state by the returning movement of the cylinder. 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,
Moreover, since the impact load when the rod reaches the bottom end becomes large, the moving speed of the driver bit cannot be increased above a predetermined speed, and the cycle time required for screw tightening cannot be shortened above a certain level. Has the drawbacks of.

The present invention aims to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide an automatic screw tightening machine having an improved reciprocating drive source for reciprocating a driver bit for tightening a screw on a work.

[Means for Solving the Problems] In order to achieve the above object, a slide shaft extending in parallel through a fixture is reciprocally arranged in the bracket. A driver base extending in a direction intersecting with this slide shaft is movably guided,
Moreover, a driver bit that rotates in response to the rotation of the drive motor is attached to the driver base in parallel with the slide shaft. Further, a chuck base extending in a direction intersecting with the slide shaft is fixed to a lower end of the slide shaft, and a chuck main body through which the driver bit is inserted and a chuck body rotatably attached to the chuck main body for moving the driver bit. A chuck unit including a pair of chuck claws biased by a spring so as to block the path is fixed.

On the other hand, a roller shaft that is rotated by the rotation of the lifting motor is arranged on the bracket, and the rotating shaft is arranged on the roller shaft so as to rotate integrally with the driver table and the chuck table, respectively. Has been done. A circumferential cam groove having a descending curve portion having a predetermined descending stroke and an ascending curve portion having a predetermined ascending stroke is formed in the outer periphery of each of the rotation rollers on the driver table side and the chuck table side. The cam followers attached to the driver stand side and the chuck stand side are respectively fitted in these circumferential cam grooves, and the cam followers reciprocate by the rotation of the rotating roller to reciprocate between the driver stand and the chuck stand. It is configured to move. Further, the descending stroke of the descending curve portion of the circumferential cam groove on the driver base side is configured to be longer than that of the circumferential cam groove on the chuck base side, so that the driver bit held on the driver base can penetrate the chuck unit. It is configured.

It is also possible to form the start point of the rising curve portion of the circumferential cam groove on the chuck base side earlier than that on the circumferential cam groove on the driver base side.

[Operation] In the above automatic screw tightener, after the drive motor is driven,
When the lifting motor is driven, its rotation is transmitted to the rotating roller via the roller shaft, and the rotating roller rotates. At 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 circumference of the rotating roller, the cam followers follow the descending curve portion of the circumferential cam groove of the rotating roller. It is pushed downward as it rolls. As a result, the driver base descends along the slide shaft and the chuck base descends together with the slide shaft. At this time, since the descending stroke of the descending curve portion of the circumferential cam groove on the driver base side is longer than that of the circumferential cam groove on the chuck base side, the driver base descends even after the chuck base has descended a predetermined stroke and stopped. Then, the driver bit held by this penetrates the chuck unit, and the screw held by the chuck claw can be tightened on a predetermined work.

If the start point of the rising curve of the circumferential cam groove of the rotating roller on the chuck base side is set earlier than the circumferential cam groove on the driver base side, the chuck base will rise with respect to the driver bit and the driver bit The tip of the tool surely protrudes from the chuck unit and reliably removes the screw remaining in the chuck unit due to improper tightening, and even if the screw is fed into the chuck unit for the next work, the screw will overlap in the chuck unit. Can be prevented.

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 bracket 2 fixed upright on a base (not shown). Two slide shafts 3 extending parallel to each other along the upright surface are reciprocally attached to the bracket 2 via fixtures 2a provided at two upper and lower positions. A driver base 4 extending in a direction intersecting with the slide shaft 3 is slidably guided at an intermediate position of the slide shaft 3, and a chuck base 5 extending parallel to the driver base 4 is integrally formed at a lower end of the slide shaft 3. Fixed to move. A drive motor 7 is fixed to the driver base 4 via a motor mounting base 6 with its drive shaft 7a facing downward, and the drive shaft 7a is parallel to the slide shaft 3 via a transmission mechanism 8. The extending driver bit 9 is connected so as to rotate integrally.

A chuck unit 11 is fixed to the lower surface of the chuck base 5 via a mounting plate 10. The chuck unit 11 is rotatably supported by a chuck body 11a through which the driver bit 9 can be inserted, and urged by a spring (not shown) to close the tip of the chuck body 11a to close the moving path of the driver bit 9. And a pair of chuck claws 11b formed therein, and one screw is air-fed from a supply hose (not shown) into a screw holding hole formed by the pair of chuck claws 11b. . Cam followers 13 and 13a are rotatably attached to the driver base 4 and the chuck base 5 via a support tool 12 so as to project in the extending direction, and these cam followers 13 and 13a are respectively cut on the bracket 2. It is configured so as to reach the inside of the bracket 2 through the notched window 2b and fit into the circumferential cam grooves 14a, 15a of the rotating rollers 14, 15 described later to roll.

On the other hand, an elevator motor 16 forming a part of an elevator drive source is fixed to the upper portion of the bracket 2 with the drive shaft 16a facing downward, and the elevator motor 16 stops when the drive shaft 16a makes only one rotation. Then, it is configured to wait for the next work start signal. The drive shaft 16a has a coupling 1
A roller shaft 18 which is upright and rotatable is connected via 7 and is configured to rotate integrally with the rotation of the lifting motor 16. Rotation rollers 14 and 15 are fixed to the roller shaft 18 at positions corresponding to the driver table 4 and the chuck table 5, respectively, at predetermined intervals, and the rotation rollers 14 and 15 are rotated by the rotation of the lifting motor 16. , 15 are configured to rotate once at a predetermined speed. Further, as shown in FIG. 2A, the rotating roller 14 on the driver base 4 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. The provided continuous circumferential cam groove 14a is cut, and the descending curve portion is configured to be sufficiently larger and longer than the circumferential cam groove on the chuck table 5 side described later and to draw a gentle curve. . Further, the straight portion is configured to stand by at the position until the driver base reaches the lowermost position and the rear driver bit 9 completes the tightening. Moreover, the cam follower 13 fixed to the driver base 4 side is fitted into the circumferential cam groove 14a, and the cam follower 13 rotates as the rotating roller 14 rotates.
When 13 rolls along the descending curve portion, it is pushed down, and when rolling along the ascending curve portion, it is pushed up.

Further, as shown in FIG. 2B, the rotary roller 15 on the chuck table 5 side has a descending curve portion having a predetermined descending stroke, an ascending curve portion having a predetermined ascending stroke, and a linear portion having a constant length on the outer periphery thereof. A continuous circumferential cam groove 15a having a groove is formed, and the descending stroke of the descending curve portion is formed to have a length necessary to bring the tip of the chuck unit 11 closer to the work. Further, the linear portion is configured to wait at that position until the driver bit 9 completes the tightening after the chuck base reaches the lowermost position. Further, the rising curve portion is formed so that the starting point of the rising stroke is earlier than the circumferential cam groove 14a on the driver base 4 side, and when the rising stroke on the driver base 4 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 15a on the chuck table 5 side has a straight line portion,
The chuck table 5 is temporarily stopped in the middle of ascending, waits for the driver table 4 to rise, and then re-elevates to lift the driver table 4 and the chuck table 5.
And are configured to return to their original position.

In the above automatic screw tightener, when the work start signal is received, the lifting / lowering motor 16 is driven and the drive shaft 16a starts to rotate at a predetermined speed so that the drive shaft 16a makes only one rotation. Rotate together. With the rotation of these rotating rollers 14 and 15, cam followers 13 and 13a attached to the driver table 4 side and the chuck table 5 side are formed on the outer circumference of the rotating rollers 14 and 15 to form circumferential cam grooves 14a and 15a. The cam followers 13, 13a roll on the descending curve portion and receive a force in the downward pressing direction, and the driver base 4 and the chuck base 5 descend. Moreover, the rotation roller on the driver base 4 side
The predetermined descending stroke of the descending curve portion of the circumferential cam groove 14a of 14 is longer than that of the circumferential cam groove 15a of the rotating roller 15 on the chuck base 5 side, and the inclination thereof is gentle, so that the chuck base 5 stops. After that, the driver base 4 descends to reach the lowest position and waits at that position for a while to secure the screw tightening time. Therefore, the driver bit 9 held by the driver base 4 moves forward with respect to the chuck unit 11 fixed on the chuck base 5, and abuts on a screw (not shown) held by the chuck claw 11b. The screws can be tightened in place by extruding from 11b.

When the screw tightening is completed, the drive motor 7 stops,
Since the lifting motor 16 rotates during this time, the chuck table 5
And after the driver stand 4 has stopped at that position for a while,
The cam follower 13a on the chuck base 5 side rolls along the rising curve portion of the circumferential cam groove 15a. Therefore, since the chuck table 5 rises with respect to the driver table 4, the chuck unit
11 rises with respect to driver bit 9. This allows
Even if a screw remains in the chuck unit 11 due to improper tightening of the screw, the screw can be ejected from the chuck unit 11, and even if the screw is fed for the next work, the screw remains in the chuck unit 11. Can be prevented from overlapping. After that, when the chuck table 5 returns by half of the ascending stroke, it stops at that position. afterwards,
The cam follower 13 on the driver base 4 side rolls along the rising curve portion of the circumferential cam groove 14a, and the driver base 4 starts rising. When the driver base 4 moves up to reach a position where the remaining lift stroke is equal to the remaining stroke of the chuck base 5, the chuck base 5 also moves up, and the driver base 4 and the chuck base 5 can be lifted and returned almost at the same time. .

[Advantages of the Invention] As described above, according to the present invention, a driver follower holding a driver bit and a chuck stand to which a chuck unit holding a screw is fixed are attached to a cam follower and a circumferential cam to which the cam follower is fitted. Since it is configured to reciprocate by a reciprocating drive source consisting of a grooved roller, the moving speed of the driver base and chuck base can be changed arbitrarily by changing the rotation speed of the lifting motor, and screw tightening There is an advantage that the cycle time required for work can be shortened arbitrarily. Further, according to the present invention, the starting point of the rising curve portion of the circumferential cam groove cut on the rotating roller on the chuck base side is set earlier than the circumferential cam groove on the driver base side. When ascending and returning, the chuck base is raised first, and the driver bit can be reliably projected from the chuck unit.
There is also an advantage that screws remaining in the chuck unit can be reliably discharged from the chuck unit.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view for explaining the whole of the present invention, and FIGS. 2a and 2b.
FIG. 4 is a development view of a circumferential cam groove of the disc cam according to the present invention. 1 ... Automatic screw tightener, 2 ... Bracket, 2a ... Fixing tool, 2b ... Notch window, 3 ... Slide shaft, 4 ... Driver stand, 5 ... Chuck stand, 6 ... Motor mount stand, 7 ... Drive motor, 7a ... Drive shaft, 8 ... Transmission mechanism, 9 ... Driver bit, 10 ... Mounting plate, 11 ... Chuck unit, 11a ... Chuck body, 11b ... Chuck claw, 12 ... … Supporting device, 13,13a …… Cam follower, 14 …… Rotating roller, 14a …… Circumferential groove, 15 …… Rotating roller, 15a …… Circular cam groove, 16 …… Motor for lifting, 16a …… Drive Shaft, 17 …… Coupling, 18 …… Roller shaft,

Claims (2)

[Claims] 1. A slide shaft extending in parallel to a bracket via a fixture is arranged so as to be capable of reciprocating, and a driver base extending in a direction intersecting with the slide shaft is movably guided to the drive shaft. A driver bit that rotates in response to the rotation of a motor is attached in parallel with a slide shaft, and a chuck base extending in a direction intersecting with the slide shaft is fixed to the lower end of the slide shaft, and the chuck body into which the driver bit is inserted. A chuck unit consisting of a pair of chuck claws rotatably mounted on the bracket and biased so as to close the moving path of the driver bit by closing the tip with a spring, while rotating the lifting motor on the bracket. A roller shaft that receives and rotates is arranged, and the rotating roller is attached to this driver shaft. The table and the chuck table are arranged so as to rotate integrally, and a descending curve portion having a predetermined descending stroke and an ascending curve portion having a predetermined ascending stroke are provided on the outer circumferences of the rotation rollers on the driver table side and the chuck table side, respectively. The circumferential cam groove consisting of is cut, and the cam followers that fit into these circumferential cam grooves are attached to the driver base side and the chuck base side, and the downward stroke of the circumferential cam groove on the driver base side is set to the chuck base side. An automatic screw tightener that is longer than the circumferential cam groove. 2. The automatic screw according to claim 1, wherein the starting point of the rising curve portion of the circumferential cam groove on the chuck base side is formed earlier than that of the circumferential cam groove on the driver base side. Fastener.