JP2773548B2 - Pitch change mechanism of multi-shaft nutrunner 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 pitch change mechanism for a multi-axis nut runner device for simultaneously tightening a plurality of bolts or nuts.

[0002]

2. Description of the Related Art Conventionally, a multi-shaft nut runner device for shortening a working time by simultaneously tightening a plurality of bolts is known. This type of apparatus is disclosed in, for example,
As shown in No. 130141, a socket for tightening a nut is connected to a drive shaft through a universal joint,
The support portions for supporting the socket are integrally fixed so as to correspond to the nut pitch intervals for tightening.

[0003]

However, in the nut runner device in which the pitch interval is fixed as described above, it is inevitable to be dedicated to the work to be tightened. In the line, a dedicated nut runner device must be provided for each vehicle type, which is not preferable in terms of effective use of space and safety. For this reason, it has been considered to incorporate a mechanism for changing the arrangement intervals of the sockets in the nut runner device, that is, to incorporate a pitch change mechanism. Particularly, in the case of tightening a hub bolt or attaching a flywheel to a crankshaft, a narrow pitch is required. Assembling the pitch change mechanism in the nut runner device for tightening a plurality of bolts and nuts has not been able to obtain a preferable one in terms of strength and pitch accuracy. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described drawbacks of the related art, and has as its object to provide a nut runner device capable of changing pitch with high strength and high pitch accuracy even when tightening a plurality of bolts and nuts having a small pitch.

[0004]

SUMMARY OF THE INVENTION The present invention provides a plurality of nut runner shafts each having a socket at a tip, a plurality of sliding members incorporating a bearing for rotatably supporting each nut runner shaft, and a plurality of sliding members opposed to the sliding members. And a cam configured to be able to move each sliding body in a radial direction by a predetermined stroke by the swing thereof, and to reduce the diameter between the plurality of nut runner shafts via the sliding body by the swing of the cam. The first is that the diameter is enlarged and the pitch is changed.
More specifically, more specifically, a plurality of nut runner shafts having a socket at the tip, a plurality of sliding bodies incorporating a bearing that rotatably supports each nut runner shaft, and a plurality of sliding bodies facing the sliding bodies. And a cam that defines the radial movement stroke of each sliding body is housed in the housing, and further provided in the housing is a movement guide section for the sliding body,
By providing a follower that engages with the cam on the sliding body, even in a multi-shaft nut runner device having a large number of nut runners built in at a small pitch interval, the pitch change can be performed simply and accurately by the swinging motion of the cam. Becomes possible,
Sufficient strength can be secured. According to the first feature, when the pitch circle diameter (PCD) of the nut runner shaft needs to be changed due to a change in the work or the like, the cam drive device is operated to swing the cam. Then, the follower engaged with the cam groove moves the sliding body in the radial direction according to the locus of the cam groove along with the swinging motion of the cam. For this reason, the nut runner shafts built into the sliding body via bearings can approach and separate from each other to quickly and easily change the pitch circle diameter corresponding to each work, and to achieve a predetermined pitch. Is obtained.

Further, a second feature of the present invention is that the housing provided in the main body is formed in a cylindrical shape, and a partition is provided inside the housing to face the cam, and all the nut runner shafts are divided into at least two sets. A plurality of guide portions corresponding to the number of shafts of each set are equally arranged on both surfaces of the partition wall, and further, the sliding bodies and cams are arranged with different phases for each set, whereby the number of nut runner shafts is reduced. At most, since the number of the runner shafts can be divided and controlled in units of groups, it is possible to cope with even smaller pitches. Further, by supporting the front and rear end portions of each nut runner shaft in the housing with a pair of sliding bodies, the nut runner shaft can be stably held and the strength can be further ensured.

It is preferable that the sliding body is supported at two positions axially separated from each other with respect to each nut runner shaft, and the cam is provided at the stop position at both ends of the stroke. It is preferable that the nut runner shaft be connected to a drive shaft via a universal joint. In this way, a large number of nut runner shafts can be arranged so as to be changeable to a reduced or enlarged position, and each nut runner shaft is supported at two places, and further, at a stop position, the movement of the housing in the radial direction is regulated and held. Stable tightening is possible.

[0007]

Next, an embodiment of the present invention will be described with reference to the drawings. However, the dimensions, materials, shapes, relative positions, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, unless otherwise specified. It is only an example. FIG. 1 is a cross-sectional view showing a pitch change mechanism 1 of a multi-shaft nut runner device according to the present invention. Although not shown, the main body is driven by a drive motor incorporated in an industrial robot, for example, to a work station. The bolt is tightened to a predetermined position of the conveyed work.

The pitch change mechanism 1 has a cylindrical shape, and a socket 2 is biased toward the distal end by a spring 18 at a distal end in a cylindrical housing 4 provided at the distal end of the pitch change mechanism. A large number of nut runner shafts 3 (the total number is five in the present embodiment, but only two are shown in the drawings for convenience) are rotatably housed via a needle bearing 5. The needle bearing 5 is incorporated in a strip-shaped sliding body 6 as shown in detail in FIGS. Further, the rear end of the nut runner shaft 3 is spline-coupled to the drive shaft 10 via a universal joint 7a, and the drive shaft 10 is connected to a drive shaft 11 incorporating a servo mechanism via a universal joint 7b. Feedback control is performed by the servo mechanism so that the nut runner can tighten the screw at a predetermined position and a predetermined torque.

As described above, the cylindrical housing 4 formed at the front end of the pitch change mechanism 1 has donut-shaped bottoms 19a and 19b at the front and rear ends, respectively. The partition portions 13 and 14 are provided in the partition. The partition portions 13 and 14 have a plurality of guide grooves 12a to 12a.
Reference numeral 12e is formed in the radial direction, and a sliding body 6 incorporating a needle bearing 5 is slidably inserted into each guide groove. In this embodiment, another narrower guide groove 24 is provided at the bottom of the guide groove 12, and the protrusion 17 provided at the lower portion of the slide body 6 is engaged with the guide groove 24 to Is more accurately guided in the radial direction.
Bottom portions 19a, b of the pitch change mechanism 1 and the partition 13,
A cam rotation shaft 20 that enables the cam 8 to swing is inserted into the center hole 15 of the cam 14. Each nut runner shaft 3 has its front end and rear end supported in the housing 4 by a pair of sliding members 6a and 6b, respectively. For this reason, each nut runner shaft 3 does not cause a problem such as whirling during screw tightening, and extremely stable screw tightening is possible.

In this embodiment, there are five nut runner shafts incorporated in the nut runner device,
It is divided into a set of books. As shown in FIG. 2, three radial guide grooves 1 are formed on one side 13a of the partition walls 13 and 14.
At the same time as providing 2a, 12b and 12c, the other two radial guide grooves 12d and 12e are provided on the opposite surface 13b as shown in FIG. Since the other partition 14 has the same structure, the description is omitted. In the partition portions 13 and 14, the nut runner shaft 3 incorporated into the sliding body 6 via the needle bearing 5 is provided with a cam 8 to be described later.
Can be moved in the radial direction along with the rocking motion of, to change the mutual pitch. The housing 4 has five long holes 1 that allow the sliding body 6 to move in the radial direction as described above.
6 is bored, and a nut runner shaft is inserted through the elongated hole 16. Further, each sliding body 6 is provided with a roller 17 projecting therefrom, and the roller constitutes a follower engaged with a cam groove 21 provided in the cam 8.

The cam 8 is composed of two donut-shaped discs 8a and 8b opposed to each other with the partition 13 or 14 of the housing interposed therebetween, as is apparent from FIGS.
Two sets of these are swingably incorporated in a cylindrical housing 4 of the pitch change mechanism 1. Each of the disc-shaped cams 8a and 8b is integrally formed at a connecting portion 22. In this embodiment, the five nutrunner shafts are divided into three sets and two sets, so that the cam disk 8a forms a locus defining the radial movement of the three slides 6a. The three cam grooves 21 are recessed. As is clear from FIG. 2, a roller protruding from the sliding body 6 that supports the nut runner shaft 3 is engaged with each cam groove 21 as the follower 17 in the cam groove 21. Further, as shown in FIG. 3, two sets of nut runner shafts 3 are attached to the disk-shaped cam 8a, which is opposite to the disk-shaped cam 8a via a partition wall 13 provided on the casing 4, as shown in FIG. Are formed, and a roller 17 similarly protruding from the sliding body 6 is engaged with the cam groove 21. Each of the cams 8a and 8b is provided with a cam driving cylinder 23, and each of the cams 8a and 8b is
8b, so that a pitch change of PCD (pitch circle diameter) of 54 mm and 44 mm becomes possible.

The state shown in FIG. 2 and FIG.
(Pitch circle diameter) is 54 mm. When it is necessary to reduce the PCD from this state to, for example, 44 mm PCD as shown in FIG. 4, the cam drive cylinder 23 is moved in the direction of arrow A. Then, the cam 8 moves in the direction of arrow B.
(The swing range is indicated by θ in FIG. 2.) Then, the roller (follower) 17 engaged with the cam groove 21 rotates according to the locus of the cam groove 21 with the swing motion of the cam 8. While sliding, the sliding body 6 is forcibly moved inward in the radial direction. Further, by moving the cam driving cylinder 23 in the direction of the arrow Aa from the position shown in FIG. 4, the cam 8a is swung in the direction of the arrow Bb in the same manner as described above, and the roller (the follower) 2), the pitch can be changed to the PCD 54 mm shown in FIG. And when the predetermined pitch is determined as described above,
Rotational torque is transmitted from the drive source to the nut runner shaft 3 via the drive shaft 10. In this state, work is performed by lowering the pitch change mechanism 1 to the screw tightening portion of the work.
When the screw tightening work progresses and reaches the predetermined rotational torque,
The rotation of the drive shaft stops and the tightening operation is completed. If it is necessary to change the pitch, the cam 8 is swung to move the nut runner shaft 3 in the radial direction until a predetermined pitch is reached. The drive transmission of these operations is performed by a servo mechanism or the like. When the nut runner shaft reaches the predetermined pitch, the swing of the cam is stopped, the rotation is transmitted to the drive shaft again, and the screw tightening operation is resumed.

Therefore, in this embodiment, FIGS.
As shown in (1), the nut runner shafts 3 incorporated into the sliding body 6 via the needle bearings 5 approach each other to reduce the pitch circle diameter (PCD), or increase the distance apart from each other. In this embodiment, the apparatus having five nut runner shafts is shown. However, in an apparatus having a large number of nut runner shafts exceeding six, the device is divided into three or more sets according to the number of nut runner shafts. It is possible to deal with this by increasing accordingly. or,
In the embodiment of the present invention, the pitch defined by the cam groove 21 is shown in two cases of large and small. However, it is possible to determine the cam groove shape in correspondence with three or more kinds of pitches. Needless to say.

Since the multi-shaft nut runner device according to the present invention has the above-described structure, when screws are tightened on a work at a predetermined pitch, it becomes necessary to screw the work having different pitches. Then, only by driving the cam driving cylinder 23 to swing the cam 8, the sliding body 6 inserted in the guide groove 12 formed in the partition 13 of the pitch change mechanism is moved in the radial direction along the cam groove 21. Therefore, the predetermined pitch of the nut runner shaft can be obtained easily and quickly, and the strength of the nut runner shaft can be sufficiently ensured.

[0015]

As described above, according to the present invention, the pitch circle diameter of the nut runner shafts can be easily set to an extremely small pitch according to the shape of the cam, so that the flywheel can be fastened to the crankshaft. Even in the case of a very narrow pitch, sufficient strength can be ensured. In addition, if the cams are arranged with different phases for each nut runner shaft set and the guides of all nut runner shafts are equally arranged in the housing, many sliding bodies can be moved in the radial direction despite the narrow space. Can be done. Further, if each nut runner shaft is supported at the front and rear ends thereof via a pair of sliding members, each nut runner shaft does not swing and can be extremely stably screwed. And so on.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of a multi-shaft nut runner device according to the present invention.

FIG. 2 is an enlarged sectional view taken along the line AA of FIG. 1, showing one surface of a partition wall portion provided in a casing of the main body of the present invention.

FIG. 3 is an enlarged sectional view taken along line BB of FIG. 1 and shows the other surface of the partition wall portion provided on the casing of the main body of the present invention.

FIG. 4 is an enlarged sectional view showing the same portion as FIG. 2, but showing a state in which the pitch between the nut runner shafts is smaller than in FIG.

FIG. 5 is a front view of a cam in which another facing cam is indicated by a dotted line.

[Description of sign]

 2 Socket 3 Nut runner shaft 4 Housing 5 Bearing 6 Sliding body 8 Cam 17 Follower 21 Cam groove

Continuation of the front page (56) References JP-A-61-192423 (JP, A) JP-A-2-32 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23P 19 / 06

Claims (2)

(57) [Claims] 1. A plurality of nut runner shafts each having a socket at a tip thereof, a plurality of sliding bodies incorporating a bearing for rotatably supporting each nut runner shaft, and a plurality of sliding bodies which are engaged and arranged to face the sliding bodies, and are provided with a swinging motion. A cam configured to be able to move each sliding body by a predetermined stroke in the radial direction by movement, to reduce or increase the diameter of the plurality of nut runner shafts via the sliding body by swinging the cam, thereby performing a pitch change. In the pitch change mechanism of the multi-shaft nut runner device configured to perform the above operation, the plurality of nut runner shafts are divided into at least two or more groups, and the diameter between the runner shafts is reduced or expanded in each runner shaft group unit. A pitch change mechanism for a multi-shaft nutrunner device, wherein a phase of a sliding body to be diametrically arranged and a cam are differently arranged. 2. A pitch change mechanism for a multi-shaft nut runner device according to claim 1, wherein a guide for guiding the sliding body in a radial direction is provided in a housing for housing said sliding body.