JP2757627B2 - Floating device for screw tightening device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floating device for a screw tightening device using a nut runner as a driving device.

[0002]

2. Description of the Related Art For example, in assembling an engine to a vehicle body in an automobile manufacturing line, the engine is pushed up from below the vehicle body supported by an overhead conveyor with a lifter, and then screwed and fixed by a screw tightening device. I have to.

FIG. 6 is a view showing one example of such a case.
A skid 52 is placed on the top, and an engine 53 is positioned on the skid 52. Then, the engine 53 is attached to the base 54 and the skid 52 with respect to the vehicle body 54.
The nut runner 55 attached to the base portion 51 is pushed up by a cylinder 56, and the stud bolt on the vehicle body 54 side via a floating device 57 is pushed up by a lifter (not shown). The nut 59 is tightened with respect to 58.

That is, when the socket portion 60, which is the output shaft on the nut runner 55 side, is fitted to the lower end of the extension rod 61 of the floating device 57 by the upward movement of the nut runner 55, the extension rod 6
The nut 59 accommodated in the socket portion 62 at the upper end of the extension rod 61 is tightened with respect to the stud bolt 58 by activating the nut runner 55 in this state.

The floating device 57 is provided for absorbing a relative position error between the stud bolt 58 and the nut 59, and is configured, for example, as shown in FIGS. In the upper and lower housings 63, 64 of the floating device 57, a small-diameter inner cylinder 65 or 66 and a large-diameter inner cylinder 67 or 68 are tapered.
0 and the other housing 6
Large-diameter guide portions 71 and 72 are formed on the extension rod 61 which is inserted and supported in the up-down direction on the extension rods 3 and 64.

When the extension rod 61 is lowered, as shown in FIG.
The housing 6 is slidably contacted with the small-diameter inner cylinder portions 65 and 66.
Extension rod 61 is centered so that 3, 64 and extension rod 61 are concentric. On the other hand, when the extension rod 61 is raised, a gap G is formed because the guide portions 71, 72 are separated from the small-diameter inner cylinder portions 65, 66 as shown in FIG. 8, and the extension rod 61 is moved within the range of the gap G. Floating in the radial direction absorbs the relative position error between the stud bolt 58 and the nut 59 described above,
The state in which the nut 59 cannot be mounted is prevented from occurring.

FIGS. 9 and 10 show a floating device which replaces the above structure. This is achieved by interposing a plurality of rubber-based elastic bodies 84 between a guide 82 that guides the extension rod 81 and a frame 83,
The relative position error between the stud bolt 58 and the nut 59 described above is absorbed by the elastic deformation of the rubber elastic body 84.

[0008]

In the structure of the conventional floating device shown in FIGS. 7 and 8, for example, when the screwing operation is performed from an oblique direction, if the floating device 57 is tilted in accordance with the screwing operation, the extension rod 61 will be under its own weight. It is extremely deviated, and the original purpose of screw tightening work cannot be performed.

On the other hand, in the structure shown in FIGS. 9 and 10, when the spring constant of the rubber-based elastic body 84 is reduced, the return force near the centering position of the extension rod 81 is reduced, and the centering position accuracy becomes unstable. Conversely, if the spring constant of the rubber-based elastic body 84 is increased, the return force is increased when the relative positional error between the stud bolt 58 and the nut 59 is large, so that the stud bolt 58 and the nut 59 must be matched. Becomes difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a floating device which solves the above-mentioned disadvantages of the conventional structure and in particular improves the centering accuracy. is there.

[0011]

In the floating device according to the present invention, a socket portion for accommodating a screw member is formed at an upper end, and a fitting portion to which an output shaft of a nut runner is fitted is formed at a lower end. An extension rod, a rod holder that supports the extension rod so as to be able to move up and down and is displaceable in the radial direction, and a plurality of extension rods that are provided at equal positions on the inner periphery of the rod holder and that can slide in the radial direction of the extension rod. It has between the slide shoe, and a spring member for biasing said slide shoe in the radial direction center of the extension rod, further
In the no-load state of the extension rod, the extension rod is centered at the centering position by the pressing force of each slide shoe and restrained, and the extension rod is slid to the extension rod provided by the spring member at the centering position of the extension rod. pressing force of the shoe is characterized in that the position <br/>置規braking position regulating means either one of the slide shoe and the spring member so that the zero is provided.

[0012]

According to this structure, since the relationship between the floating amount of the extension rod and the return force depending on the spring member has a characteristic as shown in FIG. 4, for example, the relative positional error between the screw member and the mating screw member is reduced. Is relatively small, the centering of the extension rod can be ensured. Even when the relative position error is large, the return force does not become extremely large, so that the matching position between the screw member and the mating screw member can be smoothly searched.

[0013]

FIG. 1 is a view showing an embodiment of a floating device according to the present invention. An extension rod 2 of the floating device 1 is supported by a rod holder 3 and a guide sleeve 4 so as to be vertically movable and radially displaceable. And
The lower end of the extension rod 2 is formed with a hexagonal column-shaped fitting portion 5 into which a socket portion 60 as an output shaft of the nut runner 55 (see FIG. 6) is fitted.
A socket portion 7 for accommodating a nut 6 as a screw member is integrally connected to the upper end portion.

A cushion rubber 12 for buffering is mounted on the upper end of the rod holder 3, and the rod holder 3 is provided at six equally spaced positions on the inner periphery of the rod holder 3 as shown in FIG. A slide shoe 8 is provided for each of them. A relatively deep groove 9 is formed on the back side of each slide shoe 8,
A leaf spring 10 as a spring member bent into a hairpin shape is accommodated in the groove 9 in a state where a predetermined spring force is applied. Each slide shoe 8 is urged toward the radial center of the extension rod 2 by a leaf spring 10, but the leaf spring 10 is restricted by the wall surface of the groove 9.

Therefore, when the extension rod 2 is not loaded, the extension rod 2 is centered by the pressing force of each slide shoe 8 (position coaxial with the rod holder 3) as shown in FIG.
In this centering state, the distal end portion 10a of the leaf spring 10 is restricted by the wall surface 11 which is a position restricting means, so that each slide shoe 8 pushes on the extension rod 2. The force becomes substantially zero, so that the slide shoe 8 is not pushed further on the extension rod 2 side.

In such a structure, after the extension rod 2 is pushed up by the nut runner 55 shown in FIG. 6, the extension rod 2 is driven to rotate, and as shown in FIG.
The nut 6 previously inserted into the socket part 7 is tightened against the stud bolt 58 while being pressed against the stud bolt 58.

At this time, if there is a relative positional error between the nut 6 and the stud bolt 58, the socket portion 60 on the nut runner 55 side and the fitting portion 5 of the extension rod 2
And there is a gap G between the extension rod 2 and the rod holder 3 and the guide sleeve 4. Therefore, as shown in FIG. 2 floats while pushing one of the slide shoes 8 back to absorb a relative position error between the nut 6 and the stud bolt 58. In the example of FIG. 3, the force for pushing back the extension rod 2 during the floating operation of the extension rod 2 is applied to the one leaf spring 10 (1).
0A), the leaf spring 10 (10
The force B) does not act on the extension rod 2 at all.

After the tightening of the nut 6 is completed, when the extension rod 2 is separated from the nut 6, the extension rod 2 is returned to the centering position by the push-back force of the leaf spring 10 (10A).

As described above, according to the structure of the present embodiment, the relationship between the floating amount of the extension rod 2 and the return force by the leaf spring 10 has the characteristic shown in FIG. Therefore, even when the relative position error (the amount of eccentricity) between the nut 6 and the stud bolt 58 is small, a relatively large return force acts, and the centering accuracy of the extension rod 2 is improved. Even if the relative position error is large, the return force does not become extremely large, so that the matching position between the nut 6 and the stud bolt 58 can be smoothly explored.

FIG. 5 is a view showing another embodiment of the present invention. In this embodiment, a ring-shaped spring 24 is used in place of the leaf spring 10 of the first embodiment. As shown in FIG. 5, the plurality of slide shoes 22 provided on the rod holder 21 are slidable respectively, but the extension rod 2 is in the centering state with each slide shoe 22 most advanced. ,
The forward limit position of each slide shoe 22 is a position regulating means.
Is regulated by the snap ring 23. A single ring-shaped spring 24 shared by the plurality of slide shoes 22 is disposed at the rear end of the slide shoes 22, whereby each slide shoe 22 is directed toward the radial center of the extension rod 2. An urging force has been applied.

In this embodiment, each slide shoe 2
Since the forward limit position is restricted, the same operation and effect as in the first embodiment can be obtained.

[0022]

As described above, according to the present invention, when the extension rod is in a no-load state, the extension rod is centered and restrained at the centering position by the pressing force of each slide shoe. The position of one of the spring member and the slide shoe is regulated such that the pressing force of the slide shoe applied to the extension rod by the spring member becomes zero.

Therefore, unlike the conventional structure, the intended purpose can be achieved even when the device is used in an oblique posture, and the load-displacement characteristic of the return force of the spring member and the floating amount of the extension rod can be improved. It is suitable for both centering and floating of the rod, improving centering accuracy and smoothing out the matching position between the screw member and the mating screw member, improving reliability. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line aa of FIG. 1;

FIG. 3 is a view showing one embodiment of the present invention, and is a cross-sectional view when the extension rod floats from the state of FIG. 1;

FIG. 4 is a characteristic diagram showing a relationship between a floating amount of an extension rod shown in FIG. 1 and a return force of a leaf spring.

FIG. 5 is a sectional view of a main part showing another embodiment of the present invention.

FIG. 6 is a configuration explanatory view showing a relationship between a conventional floating device and a nut runner.

FIG. 7 is a sectional view of the floating device shown in FIG. 6;

FIG. 8 is a sectional view when the extension rod is raised from the state of FIG. 7;

FIG. 9 is an explanatory diagram of a main part configuration showing another example of a conventional floating device.

FIG. 10 is a view taken in the direction of arrow b in FIG. 9;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Floating device 2 ... Extension rod 3 ... Rod holder 5 ... Fitting part 6 ... Nut as a screw member 7 ... Socket part 8 ... Slide shoe 10 ... Leaf spring as a spring member 11 ... Wall surface (position regulating means) 21 ... Rod holder 22 ... Slide shoe 23 ... Snap ring (position control means) 24 ... Ring-shaped spring as a spring member 55 ... Nut runner 58 ... Stud bolt as a mating screw member 60 ... Socket portion as output shaft

Continuation of the front page (56) References JP-A 60-97231 (JP, U) JP-A 63-102587 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23P 19 / 06

Claims (1)

(57) [Claims] 1. A floating device for supporting an extension rod interposed between an output shaft of the nut runner and a screw member in a floating manner when the screw member is fastened to a mating screw member by the nut runner. Is formed with a socket portion for accommodating the screw member, and at the lower end thereof is formed an extension rod having a fitting portion to which an output shaft of the nut runner is fitted, and the extension rod is vertically movable and radially movable. A rod holder that is displaceably supported on the rod holder; a plurality of slide shoes provided at equally spaced positions on the inner periphery of the rod holder and slidable in the radial direction of the extension rod; and and a spring member for biasing further, In the no-load state of the extension rod, the extension rod is centered and restrained at the centering position by the pressing force of each slide shoe, and at the centering position of the extension rod, the slide shoe is applied to the extension rod by the spring member. Either the slide shoe or the spring member so that the pressing force becomes zero
Floating apparatus screwing apparatus, wherein a position regulating means for regulating the position of the disposed.