JPS6156054B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic screw tightening device equipped with a screw duplication prevention mechanism.

Conventionally, screw tightening machines that force-feed screws from a supply section to a catch section for tightening screws have a screwdriver that pushes out the bit from the catch section and tightens the screw so that the screw does not remain in the catch section after tightening the screw. Equipped with a screw duplication prevention mechanism that always eliminates screws. There were two types of this mechanism: one using two cylinders and the other using one cylinder. The former requires two things: a driver and a lifting cylinder to lift and lower the bit rotationally driven by the driver, and a screw-out cylinder to lift and lower only the catch part, and further requires a valve and a sequence controller to operate each cylinder. It had become expensive. In the latter case, instead of the screw-removal cylinder of the former type, a pawl was provided, and a catch part was used to engage the catch part, or a friction plate was provided. All of these had drawbacks, such as that the action of bringing the catch to the screw tightening position and the reset action did not work well, and that they could not be used when tightening multiple screws like a multi-spindle screw driver.

The present invention solves the above-mentioned problems, and makes it possible to easily set the catch part to the screw tightening position using one drive cylinder, and also to ensure smooth reset operation when the catch part retreats. The object of the present invention is to provide an automatic screw tightening device that can be used easily and has a simple structure.

In order to achieve the above object, the present invention provides an automatic screw tightening device that pressure-feeds screws from a supply section to a catch section and tightens the screws with a bit. At the same time, a driver for rotationally driving the bit is provided so as to be interlocked with the advancement of the catch base to the screw tightening position, a cam pin that moves together with the drive cylinder, and a cam pin that is firmly supported by the catch base so that the cam pin can be inserted. and
and a cam body having a tapered surface that becomes narrower toward the rear end on the inner surface on the rear end side, which is the upper side in the cam pin insertion direction;
A plurality of steel balls built into the cam body so as to be able to come into contact with the tapered surface, a lock spring that presses the steel balls toward the tapered surface, and a cam pin inserted through the cam body are interlocked with the drive cylinder. a tapered stepped portion provided on the cam pin so as to engage and hold the steel ball with the tapered surface of the cam body to prevent the cam pin from being pulled out when the cam body moves backward; and the lock spring of the steel ball. a reset collar that is slidably provided on the cam body at a position opposite to the locking spring and that, when slid against the locking spring, pushes the steel ball to release it from its engaged and held position; The reset plate is provided on the frame and comes into contact with the reset collar at the retraction limit of the drive cylinder to slide the reset collar against the lock spring.

An embodiment of the present invention will be described below based on the drawings. In FIGS. 1 to 4, reference numeral 1 denotes a catch portion to which a screw supply pipe 1a is attached, and is fixedly supported on a catch stand 3 via a connector 2. As shown in FIG. Reference numeral 4 designates a bit for performing a screw tightening operation, which is connected to a driver 7 via a holder 5 and a universal joint 6. A driver holder 8 holds the driver 7 firmly. A rod A 9 is parallel to the bit 4, and is fixed to the driver holder 8 so that the bearing 11 of the block A10 is slidably held therein. A spring seat 12 is screwed onto the threaded end of the rod A9, and receives the spring 13 between it and the block A10. 14 is a stopper A, which is screwed to the threaded portion of the rod A9 between the spring seat 12 and the block A10.

15 is a block B to which block A10 is connected, and a cylinder rod of a drive cylinder 16 parallel to the bit 4 and a rod B17 are firmly supported, and a stopper B18 is locked to the rod B17. Further, the catch table 3 of the block B15
A cam pin 19 is firmly supported on the side opposite to. Reference numeral 20 denotes a return limit switch, which is attached to the rear end of the cylinder 16 and has a dog 20a fixed to the driver holder 8 (in the figure, it is connected to block C2, which will be described later).
2 and comes into contact with the driver holder 8). Reference numeral 21 denotes a screw floating detection switch, which is fixed to the block C22 and can come into contact with a switch rod 23 fixed to the driver holder 8. 24a and 24b are slide shafts parallel to the bit 4, the rear end of which is secured by the block C22, the front end of which is secured by the catch base 3, and the shaft is connected to the block C22.
22 moves together with the catch platform 3. Further, the driver holder 8 has slide shafts 24a and 24b.
It is held so as to be slidable along the same direction, and can be pushed by the block C22 and moved forward together with the catch base 3 to the screw tightening position. A fixed frame 25 slidably holds the slide shafts 24a and 24b.

A guide rod 26 is firmly supported by the catcher 3 and slides inside the block A10 to guide a spring 27 interposed between the catcher 3 and the block A10. This spring 27 transmits the driving force from the drive cylinder 16 to the catch base 3. 28 is a stopper C, which is engaged with the rod A9, and the block A10 is pressed against the stopper C28 by a spring 13. A reset plate 29 is fixedly supported by the fixed frame 25 and presses the reset collar 32 against the reset spring 30 and the lock spring 31 at the return limit of the catch base 3. 33 is a reset collar stopper for preventing the reset collar 32 from coming off. A plurality of steel balls 34 can be engaged with the tapered stepped portion 35 of the cam pin 19. 36 is a spring seat of the lock spring 31. Reference numeral 37 denotes a retaining ring with a hole, which is fitted into a circumferential groove in the cam body 38; the lock spring 31 is interposed between the retaining ring 37 with a hole and the spring seat 36; Built into the cam body 38, the spring seat 36 and the cam body 38
It is located between the tapered surfaces 38a of.

Next, its operation will be explained. In response to the screw tightening start signal, the driver 7 starts rotating, the cylinder 16 operates, and the block B connected to it starts rotating.
15 and the block A10 connected to this block B15 begin to move. Accordingly, the catch base 3 (together with the block C22 and the screw floating detection switch 21) and the driver holder 8 start to move forward together with the switch rod 23 due to the elasticity of the springs 27 and 13, and accordingly the catch part 1 and the bit 4 also move forward. Start.

First, the stopper D39 locked on the slide shaft 24a comes into contact with the end surface 25a of the fixed frame 25, and the forward movement of the catch base 3 is stopped. Next, when the cylinder 16 is further operated, the spring 27 is compressed and the blocks B15 and A are
10 moves forward, and the driver holder 8 and the bit 4 move forward until the stopper E40, which is locked on the slide shaft 24b, comes into contact with the end surface 8a of the driver holder 8, and the bit 4 is in the state shown in FIG. Tighten the screws.

Further, the drive cylinder 16 has a stopper E40.
Stopper A of rod A9, which stopped moving forward due to
The block A10 moves forward until it comes into contact with the block A14.
At the same time, the stopper B18 of the rod B17 comes into contact with the fixed frame 25. During this time, the cam pin 19 passes through the reset collar 32 and pushes away the group of steel balls 34 within the cam body 38, so that the tapered stepped portion 35 of the cam pin 19 and the steel balls 34 are engaged.

At this time, the switch rod 23 comes into contact with the screw lifting detection switch 21, and it is detected that the driver 7 and the bit 4 have moved forward to the tightening position.
If the screw cannot be fully tightened due to misalignment or the like, the driver 7 and the bit 4 will be prevented from moving forward during tightening, and the switch rod 23 will not operate the screw detection switch 21. This determines whether the screw is floating.

When the screw tightening is completed, the cylinder 16 starts to return, but the cam pin 19 that has returned uses the tapered part 35a of the tapered step part 35 to press the steel ball 34 against the tapered part 38a of the cam body 38, and perpendicular to the tapered surface. directional force is generated to prevent the cam pin 19 from coming off from the cam body 38. However, bit 4 does not return until block A10 comes into contact with stopper C28 of rod A9.
The catch part 1 has a cam pin 1 as shown in FIG.
9 and the catch base 3 before the bit 4, and after the block A10 comes into contact with the stopper C28, the bit 4 returns together with the catch part 1. Then, the reset collar 32 is attached to the fixed frame 2.
When the reset collar 32 comes into contact with the reset plate 29 of No. 5, the reset collar 32 resists the reset spring 30 and the lock spring 31, pushes up the steel ball 34 along the tapered part 35a of the step part 35, and causes the cam pin 19 to separate from the cam body 38. For this reason, the catch base 3 has a spring 27
(If it is vertical, it will fall due to its own weight), and the catch part 1 moves forward as if wiping the tip of the bit 4, removing the defective screw that unexpectedly attached to the bit 4, and the screw tightening machine moves as shown in Fig. 1. Return to original state. In addition, when the screw tightening head is retracted, the bit always comes out from the tip of the catcher, so there is no need to reset screws that have been tightened incorrectly due to missing pilot holes or misalignment, etc., remaining in the catcher. , can be removed from the catcher section each time.

Next, another embodiment will be described based on FIG.
The difference between this second embodiment and the first embodiment described above is that the first embodiment was a single-shaft screw tightening machine;
The second embodiment shows a multi-spindle screw tightening machine that tightens a plurality of screws at the same time. For this reason, the catch base becomes heavy and falls when a screw is ejected, but a shock damper is provided to absorb the impact. In addition, in the first embodiment, a spring was interposed between the drive cylinder and the driver to determine the operating stroke of the screw ejecting cam, but in the second embodiment, the spring is inserted between each spring for multiple axes. It is provided between the driver holder and the bit to enable the above-mentioned operation for each axis.

Hereinafter, the same parts as those in the first embodiment will be given the same numbers, and the explanation will be omitted, and only the different parts will be explained. Reference numeral 41 denotes a column that supports the cylinder stand 42 and the lower frame 43. A slide shaft 44 is installed between the cylinder base 42 and the lower frame 43. 45 is a driver holder,
It is connected to the rod of the drive cylinder 16 and is slidable on the slide shaft 44. 46 is a lowering limit stopper of the driver holder 45. Reference numeral 47 denotes a catch base, which is supported by the rod end of the drive cylinder 16 and biased downward by a spring 48. 49 is a stopper of the catch table 47. A spring 50 is located between the driver 7 and the bit 4 and constitutes a flexible shaft system.
Reference numeral 51 denotes a cushion cylinder fixed to the catch base 47, and its cylinder rod 52 is supported by the driver holder 45 at its tip step. 53
is a connection port of the cushion cylinder 51, which is connected to an air source.

Next, its operation will be explained. Due to the lowering movement of the cylinder 16, the catch portion 1 is lowered until the catch base 47 comes into contact with the stopper 49. The driver holder 45 continues to descend further, and the bit 4 engages with the screw to tighten the screw. At this point, the bit 4 stops descending, but the driver holder 45 continues to descend by compressing the spring 50, and when the cam pin 19 is fully inserted into the cam body 38, it comes into contact with the lowering limit stopper 46 and stops descending. After the screw tightening is completed, the cylinder 16 begins to return and returns with the cam pin 19 still engaged with the cam body 38, as in the first embodiment, and the reset collar 32 comes into contact with the reset plate 29, causing the cam pin 19 and the cam body 38 to be separated. The engagement is released. At this time, the catch table 47 falls, but returns to its original position without impact due to the action of the cushion cylinder 51.

In this way, the multi-shaft screw tightening machine of the second embodiment can also provide the same effects as the first embodiment.

As described above, according to the present invention, a screw tightening operation can be performed using a single drive cylinder without the need for a sequence controller, and a smooth reset can be performed reliably when the screw tightening head is retracted with a simple configuration. I can do it.

[Brief explanation of the drawing]

Fig. 1 is a screw tightening device according to an embodiment of the present invention, Fig. 2 is a plan view thereof, Fig. 3 is a detailed view of the catch section and main parts advanced to the tightening surface, and Fig. 4 is a screw ejecting operation. FIG. 5 is a detailed view of the catch portion and main parts, and a partially sectional side view showing another embodiment. 1...Catcher part, 3,47...Catcher stand,
4... Bit, 7... Driver, 8, 45... Driver holder, 13, 50... Spring, 16... Drive cylinder, 19... Cam pin, 25... Fixed frame, 2
9... Reset plate, 30... Reset spring, 31... Lock spring, 32... Reset collar, 34... Steel ball,
35...Tapered step part, 38...Cam body, 50...Cushion cylinder.

Claims (1)

[Claims] 1. In an automatic screw tightening device that pressure-feeds screws from a supply section to a catch section and tightens the screws with a bit,
A spring is interposed between the catch base to which the catch part is attached and the drive cylinder, and a driver for rotationally driving the bit is provided so as to be interlocked with the advance of the catch base to the screw tightening position, and the driver moves together with the drive cylinder. a cam pin, a cam main body that is firmly supported by the catcher stand so that the cam pin can be inserted therein, and that has a tapered surface that narrows toward the rear end on the inner surface of the rear end, which is the upper side in the cam pin insertion direction, and that contacts the tapered surface. When a plurality of steel balls built into the cam body so as to be able to touch each other, a lock spring that presses the steel balls toward the tapered surface, and a cam pin inserted through the cam body move backward in conjunction with the drive cylinder. a tapered stepped portion provided on the cam pin so as to engage and hold the steel ball with the tapered surface of the cam body to prevent the cam pin from being pulled out, and a position of the steel ball on the opposite side of the lock spring. a reset collar that is slidably provided on the cam body and that pushes the steel ball when it slides against the locking spring to release it from its engaged and held position; and a reset collar that is provided on the fixed frame; An automatic screw tightening device comprising: a reset plate that comes into contact with the reset collar at the retraction limit of the drive cylinder and slides the reset collar against the lock spring.