JPH0592332A - Screw tightening device - Google Patents

Abstract

(57) [Summary] [Purpose] The screw can be stably held regardless of the direction of the screw, and thus adapted to an industrial robot. [Structure] A rotational force transmission unit 12 is supported by a rotary shaft 10 rotated by a rotary drive unit 8 so as to be expandable and contractable in the axial direction. The rotational force transmitting portion 12 is urged by the spring 3 in the extending direction. The rotating force transmitting portion 12 is provided with a tightening portion 4 having an engaging portion at its tip end that engages with the head of the screw 5. When the spring 3 is compressed, the tightening portion 4 is
A grip 2 is provided which is capable of gripping the shaft portion of the screw 5 engaged with. The shaft of the screw 5 is gripped by the grip 2, and the tightening portion 4 is pressed against the head of the screw 5 by the urging force of the spring 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw tightening device for automatically tightening a screw (including bolts), which is installed in, for example, an industrial robot or other assembling device.

[0002]

2. Description of the Related Art In a conventional screw tightening device, when a screw is held in a tightening portion having an engaging portion for engaging the screw head, the chuck claw, negative pressure of air, magnetic force of a magnet, etc. There is one that is held by using the holding means. An example of the screw tightening device is disclosed in Japanese Utility Model Laid-Open No. 58-51972.

[0003]

However, all of the conventional ones are aimed at tightening the screws from the upper side to the lower side, and in the directions other than the downward direction,
In particular, it did not take into consideration the tightening of screws in the lateral direction or upward direction. Therefore, if you try to tighten the screws in the lateral direction using a conventional one, the screws will become unstable due to the influence of gravity, and the screws will hang down or fall. do it,
Problems such as improper tightening or screw tightening may occur. Therefore, even if the conventional hand is mounted on the hand of the industrial robot and it is desired to perform automatic tightening, the hand can be operated in various directions, for example, in six directions (front-back, left-right, up-down, pitching, yawing, rolling). Therefore, in the conventional device, there is a concern that the above-mentioned trouble may occur, and it is difficult to apply the problem. For these reasons, there is a demand for a screw tightening device that can be applied to an industrial robot.

Therefore, the present invention has been made in order to solve the above-mentioned problems, and its purpose is to be able to stably hold the screw regardless of the direction of the screw, and thus be applicable to an industrial robot. To provide a screw tightening device.

[0005]

SUMMARY OF THE INVENTION A screw tightening device of the present invention which solves the above-mentioned problems is provided with a rotary shaft which is rotated by a rotary drive unit, and which is supported by the rotary shaft so as to be expandable and contractible in the axial direction thereof and is extended by a spring. The rotational force transmitting portion that is biased in the direction, a tightening portion that has an engaging portion provided at the rotational force transmitting portion and that engages with the head of the screw at the tip, and the tightening portion when the spring is compressed. And a grip capable of gripping the shaft portion of the screw engaged with the attachment portion. A universal joint may be interposed between the rotational force transmitting portion and the tightening portion.

[0006]

According to the above-mentioned means, while the screw is engaged with the engaging portion of the tightening portion and the spring is compressed, the shaft portion of the screw is gripped by closing the grip, and The tightening portion is pressed against the head by the biasing force of the spring. As a result, the screw is stably held by the cooperation of the grip by the grip and the biasing by the spring. In this state, the screw is moved to the tightening portion, and the grip of the screw is released by opening the grip with the shaft end of the screw pressed against the tightening hole. Then, while the screw is pressed toward the tightening hole by the spring, the tightening part is rotated together with the rotational force transmitting part as the rotation shaft is rotated by the rotation driving part, so that the screw is tightened. Tightened in the hole. Further, in the case where the universal joint is interposed between the rotational force transmitting portion and the tightening portion, there is a positional deviation (center misalignment) between the tightening hole and the rotational force transmitting portion when tightening the screw. Even in this case, the universal joint can transmit the rotational force in a state where the tightening portion is tilted, so that the screw can be tightened while absorbing the positional deviation.

[0007]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a screw tightening device in a sectional view. The upper half of FIG. 1 shows the screw holding state and the lower half of the screw tightening state. The nut runner 8 serving as a rotation drive unit has an output shaft 8a protruding from the front surface of the main body 9.
have. The nut runner 8 is mounted on a hand of an industrial robot (not shown). Also, the output shaft 8
A rotary shaft 10 forming the same axis as that of a is linked to the a by engagement so as to be interlocked. Nut runner 8
Can be replaced by an electric motor.

A rotating force transmitting portion 12 having the same axis as the rotating shaft 10 is supported by engagement so as to be expandable and contractable in the axial direction. More specifically, an engaging shaft portion 10a having, for example, a quadrangular cross section is formed at the distal end portion of the rotating shaft 10, and the rotational force transmitting portion 12 has a substantially cylindrical shape, and the engaging hole 12a formed at the base end portion thereof is the engaging member. The mating shaft portion 10a is slidably engaged. A coil spring 3 is interposed between the rotating shaft 10 and the torque transmitting portion 12. The spring 3 always biases the rotational force transmitting portion 12 in the extending direction (leftward in the drawing).

One shaft 6a of the universal joint 6 is attached to the tip of the rotational force transmitting portion 12. The universal joint 6 is, as is well known, a hook type universal joint, a top type universal joint, or a similar type shaft joint that enables power transmission while the two shafts 6a and 6b respond to changes in angle. There is. The bit 4 is fixed to the other shaft 6b of the universal joint 6 via a known chuck device 14. The engaging portion 4a formed at the tip of the bit 4 is engageable with the head of the screw 5, more specifically, the cross groove (not shown) of the head. The bit 4 corresponds to the tightening portion in the present invention.

On the front surface of the nut runner body 9, a cylindrical grip opening / closing cylinder 1 for opening and closing a grip 2 described later is provided with the same axis as the output shaft 8a. The open / close cylinder 1 includes a fixed cylinder 15 fixed to the nut runner body 9 and a fixed cylinder 15
The movable cylinder 16 is slidably fitted in the front and rear bearings 17 therein. Front and rear annular walls 15a and 15b are formed on the inner peripheral surface of the fixed cylinder 15, and the outer peripheral surface of the movable cylinder 16 is divided into two front and rear compartments 18a and 18b. The piston wall 16a is formed. Each of the compartments 18a, 18b
Air piping (not shown) is provided in each chamber 18
The moving barrel 16 is moved back and forth by sucking and discharging air with respect to a and 18b. The amount of extension of the rotational force transmission portion 12 is limited by the portion (the flange of the shaft 6a in the figure) on the transmission portion 12 side contacting the portion of the movable barrel 16 projecting to the inner circumference of the distal end portion. Further, the rotation of the movable barrel 16 about its axis is restricted by the engaging means that is slidably engaged with the fixed barrel 15 in the axial direction.

A pair of connecting pieces 20 are symmetrically attached to the tip of the moving barrel 16. Each connecting piece 2
At the front end position of 0, a substantially L-shaped grip 2 having a screw grip portion 2a at its tip is attached to the fixed barrel 15 via support pins 21 so as to be openable / closable. In the figure, the portion of the fixed cylinder 15 corresponding to the mounting portion of the support pin 21 is omitted. Both ends of a connecting link 23 are rotatably connected to the base end of each grip 2 and the corresponding tip of the connecting piece 20 by pins 24 and 25, respectively. Therefore, when the moving cylinder 16 is moved forward by the extension operation of the grip opening / closing cylinder 1, the grip 2 is closed as shown in the upper half of FIG. 1, and the moving operation is performed by the shortening operation of the opening / closing cylinder 1. By retracting the tube 16, the grip 2 is opened as shown in the lower half of FIG. The screw grip 2
As shown in the sectional view of FIG. 5, symmetrical V-shaped grooves 2b are formed on the facing surfaces of a, respectively. The V-shaped groove 2b can grip the shaft portion of the screw 5 such that the shaft end is exposed.

The operation of the screw tightening device will be described. 2 is a sectional view showing a screw holding state, FIG. 3 is a sectional view showing a screw tightening state, and FIG. 4 is a schematic explanatory view showing an operating procedure of the screw tightening device. .. First, in the screw tightening device, the grip 2 is closed by the extension operation of the grip opening / closing cylinder 1. Further, as shown in FIG. 4A, the bit 4 is in a state of penetrating between the screw grip portions 2 a of the grip 2 by the biasing force of the spring 3. A large number of screws 5 are planted in the screw magazine 27.

From this state, screws 5 of the screw magazine 27
In order to obtain the bit, the hand is moved by the operation of the industrial robot, and the bit 4 is made to have substantially the same axis as the screw 5 as shown in FIG. The engaging portion 4a is pressed against the head of the screw 5. At this time, by driving the nut runner 8, the bit 4 is rotated at a low speed together with the rotary shaft 10 and the rotational force transmitting portion 12, and the rotation is utilized to engage the engaging portion 4a of the bit 4.
Is engaged with the cross groove of the screw 5. After that, the driving of the nut runner 8 is stopped. Further, the screw 5 idles on the screw magazine 27 together with the bit 4 from the time when the bit 4 is engaged with the screw 5 until the driving of the nut runner 8 is stopped. Further, by the movement of the hand, the nut runner 8 resists the elasticity of the spring 3 and the screw magazine 2
By being pressed toward 7, the bit 4 is pressed by the reaction force of the screw 5, and the spring 3 is compressed. At the same time, the grip 2 is opened by the shortening operation of the grip opening / closing cylinder 1. Then, when the screw grip portion 2a corresponds to the shaft portion of the screw 5, the grip 2 is closed by the extension operation of the cylinder 1. As a result, the shaft portion of the screw 5 is gripped by the screw grip portion 2a of the grip 2 (see FIG. 4B).

After that, the nut runner 8 is retracted from the screw magazine 27 by the movement of the hand, the screw 5 is extracted from the screw magazine 27, and then moved to a desired tightening portion. At this time, the screw 5 is gripped by the grip 2 as shown in FIG. 2, and the bit 4 is pressed against the head of the screw 5 by the urging force of the spring 3. Therefore, the screw 5 is stably held by the cooperation of the gripping by the grip 2 and the biasing by the spring 3. Therefore, even if the hand moves in various directions, for example, in 6 directions (front-back, left-right, up-down, pitching, yawing, rolling), the screw 5 does not hang down or drop.

Further, by the movement of the hand, the screw 5 at the tip of the bit at the tightening portion forms substantially the same axis as the tightening hole 29a of the tightening object 29, as shown in FIG. 4 (c). Then, the shaft end of the screw 5 is pressed against the tightening hole 29a. When the grip 2 is opened by the shortening operation of the grip opening / closing cylinder 1, the grip of the screw 5 is released. Further, by driving the nut runner 8 to rotate the bit 4 together with the rotating shaft 10 and the rotational force transmitting portion 12, the screw 5 is tightened in the tightening hole 29a (see FIGS. 3 and 4 (d)). ).

At this time, even if there is a positional deviation (center misalignment) between the tightening hole 29a and the rotational force transmitting portion 12 as indicated by the symbol X in FIG. The universal joint 6 allows the rotational force to be transmitted in a state where the bit 4 is tilted, so that the screw can be securely tightened while absorbing the positional deviation. After tightening the screw, the driving of the nut runner 8 is stopped, the grip 2 is closed by the extension operation of the grip opening / closing cylinder 1, and then the hand moves for the next screw tightening. In this way, the screw tightening work is repeated.

According to the screw tightening device, the screw 5 can be stably held by the cooperation of the grip 2 and the biasing force of the spring 3, so that the screw 5 can be properly tightened regardless of the direction of the screw 5. Therefore, it can be adapted to industrial robots. Further, since the screw 5 can be tightened while absorbing the positional deviation between the tightening hole 29a and the rotational force transmitting portion 12 by the universal joint 6, a highly reliable robot system can be established and the application by the robot system can be expanded. Be done.

[0018]

According to the present invention, the following effects can be obtained. In the screw tightening device according to the first aspect, the screw can be stably held by the cooperation of the grip by the grip and the biasing by the spring, so that the screw can be properly tightened regardless of the direction of the screw, and therefore, the industrial use Can be adapted to robots. The device is not limited to the industrial robot, and may be used in other assembly devices. In the screw tightening device of the second aspect, it is possible to absorb the positional deviation of the rotational force transmitting portion with respect to the tightening hole, and it is possible to perform proper tightening even when the positional deviation occurs.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a screw tightening device.

FIG. 2 is a sectional view showing a screw holding state.

FIG. 3 is a cross-sectional view showing a screw tightened state.

FIG. 4 is a schematic view illustrating an operating procedure of a screw tightening device.

FIG. 5 is a sectional view of a screw grip portion of the grip.

[Explanation of symbols]

 2 Grip 3 Spring 4 Bit (tightening part) 5 Screw 6 Universal joint 8 Nut runner (rotary drive part) 10 Rotating shaft 12 Rotating force transmitting part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Hideto Uematsu 100 Kanayama, Ichiriyama-cho, Kariya city, Aichi Prefecture Toyota Auto Body Co., Ltd. (72) Shinichi Hirose 100 Kanayama, Ichiriyama-cho, Kariya city, Aichi prefecture Toyota In-body Co., Ltd. (72) Inventor Masahiro Taki 100 Kanayama, Ichiriyama-cho, Kariya city, Aichi Toyota In-vehicle Co., Ltd. (72) Inventor Harumi Ami 1, Toyota-cho, Toyota-shi, Aichi Inside Toyota Automobile Co., Ltd. (72 ) Inventor Tadanori Suzuki 3580, Kobaba, Oshinomura, Minamitsuru-gun, Yamanashi Prefecture

Claims (2)

[Claims] 1. A rotary shaft that is rotated by a rotary drive unit, a rotary force transmitting unit that is supported by the rotary shaft so as to be capable of expanding and contracting in the axial direction, and is urged by a spring in the extending direction, and the rotary force transmitting unit. And a grip capable of gripping the shaft portion of the screw engaged with the tightening portion in a compressed state of the spring. A screw tightening device equipped. 2. The screw tightening device according to claim 1, wherein a universal joint is interposed between the rotational force transmitting portion and the tightening portion.