JPH0966425A - Automatic bolt fastening device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic bolt fastening device capable of preventing transmission of over-torque to the device-body, and easily performing positioning of the bolt fastening device on a bolt head. SOLUTION: The automatic bolt fastening device is provided with a bolt fastening part 8 having a pair of nut runners 10 and fastening sockets 11 to be driven by the respective nut runners 10, a wrist 6 of a robot 5 as a positioning part for hanging the bolt fastening part 8 to position it at a desired position, and a joint part 7 for supporting the bolt fastening part 8 so that it can be freely tilted with respect to the wrist part 6 and be turned in the horizontal plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic bolt tightening device for automatically tightening bolts using a nut runner.

[0002]

2. Description of the Related Art Conventionally, as an automatic bolt tightening device for tightening bolts using an automatic machine, a socket driven by a nut runner grips the bolt, and the bolt is tightened into a tightening hole (female screw) of an object to be fastened. There is known a bolt automatic tightening device which is inserted into a screw and rotates a socket for tightening.

However, in such a bolt automatic tightening device, translational deviation and angular deviation may occur between the socket and the bolt, which may adversely affect the tightening quality.
Therefore, in order to solve such problems of translational deviation and angular deviation, an automatic screw tightening device using a combination mechanism of a flexible coupling and an RCC (remote center compliance) mechanism is disclosed in, for example, JP-A-59-1.
No. 87430.

As shown in FIGS. 5 (a) and 5 (b),
In the automatic screw tightening device disclosed in this publication,
The RCC mechanism 101 includes a circular fixed plate 101a fixed to a support member (not shown), a movable plate 101b facing the fixed plate 101a, and an elastic member 101c arranged between the plates. Mechanism 10
1. The flexible coupling 103 is attached to the tip of the shaft 102 of the nut runner that is supported without touching the shaft 1.
The shaft 104a of the socket 104 is connected via the shaft 104a, and the shaft 104a is supported by the socket support fitting 105 mounted on the lower surface of the movable plate 101b via the bearing 106. With such a configuration, even if the positional accuracy of the female screw 108 of the work 107 and the inclination accuracy of the bolt 109 are poor and translational deviation and angular deviation occur, as shown in FIG.
1 and the function of the flexible coupling 103, the translational deviation and the like are corrected.

[0005]

However, in the combination mechanism of the flexible coupling and the RCC mechanism as disclosed in the above publication, the mechanism of the tip portion of the bolt tightening device is complicated and large and should be handled. There is a problem that the target work is limited. Further, in such a mechanism, in the case of tightening a large-diameter bolt that generates high torque, the tightening reaction force is applied to the main body of the device, so that there is a problem in that the device itself needs to be extremely sturdy. is there.

In order to solve the above problems, the present invention prevents the transmission of overtorque to the main body of the apparatus and automatically tightens the bolts so that the bolt heads can be easily aligned. To provide a device.

[0007]

In order to achieve the above-mentioned object, an automatic bolt tightening device according to the present invention comprises (a) a pair of nut runners and a tightening socket driven by each nut runner. And (b) a positioning part for suspending and positioning the bolt tightening part at a desired position, and (c) the bolt tightening part is tiltable with respect to the positioning part and swivels in a horizontal plane. It is characterized in that it is provided with a joint portion that supports it freely.

In the bolt automatic tightening device of the present invention,
The bolt tightening part is positioned at the desired position by the positioning part, and each nut runner is rotated with the tip of each socket in this bolt tightening part pressed against the bolt head, and tightening is performed while synchronizing the nut runner shafts. Be seen. At this time, the bolt tightening portion tilts with respect to the positioning portion by the joint portion and swivels in the horizontal plane, so that the socket tip portion is smoothly fitted to the bolt head portion. Also, in this tightening, before the final tightening, there is looseness between the socket and the bolt, so the reaction force of the tightening torque tries to be transmitted to the positioning part at the start of the final tightening, but the joint tightens the bolt tightening part. The reaction force is not transmitted to the positioning portion because it is allowed to freely move in the turning direction. Further, in this final tightening, a large torque is generated in each nut runner, but since the bolt tightening part has a structure with a pair of nut runners, the reaction force is received by the tightening reaction force between these pair of nut runners. It is not transmitted to the club. Therefore, it is not necessary to make the positioning part a sturdy structure to withstand the tightening reaction force, and to install a special device for aligning the socket and the bolt head at the tip of the nut runner, which simplifies the device. It is possible to reduce the size and size, and solve the problem of interference between the bolt tightening portion and the target work.

In the present invention, it is preferable that the bolt tightening portion has a ball screw mechanism capable of adjusting a distance between the pair of nut runners. With such a configuration, the position of the nut runner can be freely adjusted according to the shape of the target work.

Further, it is preferable that the joint portion has a fixing mechanism for fixing the bolt tightening portion to the positioning portion. By doing so, when the bolt tightening portion is positioned at the desired position, the bolt tightening portion can be restrained, and this positioning becomes easier.

Further, the joint portion includes an upper frame fixed to the positioning portion, and a lower frame whose lower surface is supported by a self-aligning roller bearing and whose upper surface is pressed by a spherical jack. It is preferable that the structure has

Other objects of the present invention will become apparent from the detailed description given below. However, while the detailed description and specific examples describe the most preferred embodiments, various modifications and variations within the spirit and scope of the invention will be apparent to those skilled in the art from the detailed description, and therefore, specific examples As described below.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific embodiments of the automatic bolt tightening device according to the present invention will be described with reference to the drawings.

An overall perspective view of an automatic bolt tightening device according to an embodiment of the present invention is shown in FIG. In the automatic bolt tightening apparatus 1 of the present embodiment, a vertical articulated robot 5 having a plurality of arms 2, 3 and 4 as a flexible moving machine that is moved to a bolt tightening location of a target work and positioned. The robot 5 has a wrist portion (positioning portion) 6 on which a bolt fastening portion 8 is suspended via a joint portion 7.

The bolt tightening portion 8 is provided with a main body frame 9 extending horizontally. The main body frame 9 has its central portion suspended from the joint portion 7 and sandwiches the joint portion 7. It is provided with a pair of nut runners 10, 10 mounted vertically on both sides. These nut runners 10 and 10 are attached to the nut runner 1 through an elastic mechanism such as a spring (not shown) at the tip (lower end).
It has a tightening socket 11 driven by 0, and is made to approach / separate by a ball screw mechanism 12 provided in the main body frame 9 in synchronism with the arrow AB direction. The wrist 6 of the robot 5 has X, Y,
Movement in the Z-axis direction and rotation around each of those axes (TX, T
It has a total of 6 degrees of freedom (Y, YZ).

The detailed structure of the joint portion 7 is shown in FIGS. The joint portion 7 is a housing (upper frame) integrally fixed to the wrist portion 6.
13, a swing frame (lower frame) 15 supported on the bottom surface of the housing 13 via a thrust self-aligning roller bearing 14, and a spring case 16 provided above the center of the swing frame 15. The body frame 9 of the bolt tightening portion 8 is fixed to the lower portion of the swing frame 15.

A spherical jack 17 is attached to the spring case 16.
Is built in, and a disc spring 18 for pushing down the spherical jack 17 and a pushing plate 19 for pushing down the disc spring 18 are built in. The upper surface of the pushing plate 19 is the top plate 13a of the housing 13. By abutting on the tip of the bolt 20 to be screwed, the upper surface of the central portion of the swing frame 15 is pressed down with a strong force via the disc spring 18 and the spherical jack 17.

The swing frame 15 has a bilaterally symmetrical shape, and has a pair of guide bodies 22 and 23 on the top surface of the tip of a support member 21 that projects in the left-right direction. As shown in FIGS. 3 and 4, each guide body 22, 23
Taper surfaces 22a and 23a are formed on the upper surfaces of both side portions, and a groove portion 22b having a shape gradually narrowing toward the center of the swing frame 15 is formed in the center.
23b is formed.

On the other hand, the side plates 13b, 13 of the housing 13
Air cylinders 24 and 25 are attached to c, respectively, and pushers 26 and 27 are attached to the tip ends of the cylinder rods of the air cylinders 24 and 25, respectively. Each extruded body 2
6 and 27 are tapered surfaces 22 of the guide bodies 22 and 23.
The surfaces facing a and 23a are tapered surfaces 26a and 27a having the same inclination angle as the tapered surfaces 22a and 23a.
Further, a pin 28 having a diameter slightly smaller than the narrowest portion of the groove portions 22b and 23b is planted in the central portion of the lower surfaces of the extruded bodies 26 and 27. The air cylinders 24 and 25, the extruded bodies 26 and 27, and the like constitute a fixing mechanism of the swing frame 15.

Thus, in the state where the push-out members 26 and 27 are pulled out by the operation of the air cylinders 24 and 25 (the solid line position in FIG. 2), the swing frame 15, in other words, the bolt tightening portion 8, is The lower plate 1 of the swing frame 15 is centered on the center 17a of the spherical jack 17.
The upper surface of 5a can freely move in the α direction (tilting direction) within a range in which the upper surface of 5a abuts the lower surface of the bottom plate 13d of the housing 13. It is possible to freely move in the β direction (the turning direction in the horizontal plane) within the range constrained by the groove portions 22b and 23b of 22 and 23. When the push-out members 26 and 27 are pushed inward from the pulled-out state of the push-out members 26 and 27 by the operation of the air cylinders 24 and 25 in accordance with an external signal (the position indicated by the chain line in FIG. 2), the pins 28 of the push-out members 26 and 27 are formed. Are guided by the groove portions 22b, 23b of the guide bodies 22, 23, so that the tapered surfaces 22a, 26a;
27a are engaged with each other and the swing frame 15 is attached to the housing 1
3, the bolt tightening portion 8 is fixed to the wrist portion 6.

Next, the work procedure for bolt tightening by the automatic bolt tightening device 1 of this embodiment will be described.

First, prior to tightening the bolts, the ball screw mechanism 12 is operated to adjust the distance between the pair of nut runners 10 in accordance with the distance between the pair of bolts to be tightened. Next, in a state where the swing frame 15 of the joint portion 7 is restrained by the housing 13, the robot 5 moves the bolt tightening portion 8 close to a pair of bolts to be tightened, and the tip portions of the sockets 11 and 11 are pressed against the head portion of the bolt. In this state, the push-out members 26 and 27 are pulled out by the operation of the air cylinders 24 and 25 in response to a signal from the outside, and the bolt tightening portion 8 is brought into a state where it can move freely in the α direction and the β direction.

When the nut runners 10 and 10 are rotated in this state, the chamfered portions provided on the edges of the inner surfaces of the sockets 11 and 11 are also assisted by the elastic force of the tips of the nut runners 10 and 10 and the rotational force of the nut runners 10 and 10. The bolt tightening portion 8 moves in the α direction and the β direction along (not shown) so that the sockets 11, 11 fit into the bolt heads. In this way, the pair of sockets 11 and 11 are fitted to the head of the bolt before the bolt is seated. After this, a pair of nutrunners 1 with snug torque.
Synchronize 0 and 10 and tighten.

In this tightening, before the final tightening, the reaction force of the tightening torque tries to be transmitted to the wrist 6 at the start of the final tightening due to the looseness between the socket 11 and the bolt. Tightening part 8
Is allowed to freely move in the β direction, so that its reaction force is not transmitted to the wrist portion 6. Further, in this final tightening, a large torque is generated in each of the nut runners 10, 10, but since the bolt tightening portion 8 has a structure having a pair of nut runners 10, 10, the pair of nut runners 10, 10 are connected to each other. The tightening reaction force is not transmitted to the wrist 6.

After tightening, the bolt tightening portion 8
After removing the bolt from the head of the bolt, the rocking frame 15 is restrained by the operation of the air cylinders 24, 25 by a signal from the outside to move to the next tightening position at high speed without burdening the joint portion 7. can do.

In this embodiment, the case where a vertical articulated robot is used as a mobile unit has been described.
The mobile device is not limited to the robot and any other mobile device can be used as long as it has a function of supporting and moving the bolt tightening portion 8.

As mentioned above, it is obvious that the present invention can be variously modified. Such modifications are within the spirit and scope of the invention, and all such variations and modifications apparent to those skilled in the art are intended to be within the scope of the following claims.

[Brief description of drawings]

FIG. 1 is an overall perspective view of an automatic bolt tightening device according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a joint portion.

FIG. 3 is a plan view of a swing frame.

FIG. 4 is a front view of a joint portion shown with a part broken away.

FIG. 5 is a view showing a conventional automatic screw tightening device.

[Explanation of symbols]

 1 Automatic bolt tightening device 5 Robot 6 Wrist part (positioning part) 7 Joint part 8 Bolt tightening part 10 Nut runner 11 Socket 12 Ball screw mechanism 13 Housing (upper frame) 14 Thrust self-aligning roller bearing 15 Swing frame (lower frame) ) 17 Spherical jack 24,25 Air cylinder 26,27 Extruded body

Claims (4)

[Claims] 1. A bolt tightening portion having (a) a pair of nut runners and a tightening socket driven by each nut runner, and (b) a positioning portion for suspending and positioning the bolt tightening portion at a desired position. And (c) an automatic bolt tightening device comprising a joint part that supports the bolt tightening part with respect to the positioning part so as to be tiltable and rotatable in a horizontal plane. 2. The automatic bolt tightening device according to claim 1, wherein the bolt tightening portion has a ball screw mechanism capable of adjusting a distance between the pair of nut runners. 3. The automatic bolt tightening device according to claim 1, wherein the joint portion has a fixing mechanism that fixes the bolt tightening portion to the positioning portion. 4. The joint portion includes an upper frame fixed to the positioning portion, and the upper frame,
The automatic bolting device according to any one of claims 1 to 3, wherein the lower surface is supported by a self-aligning roller bearing and the upper surface is pressed by a spherical jack.