JP3079787B2 - 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 device for tightening screws such as bolts and nuts.

[0002]

2. Description of the Related Art In the case of a tightening device for screws, the rotation axis of the tightening device may not exactly coincide with the rotation axis of the screws, and it is necessary to ensure that the screws are still tightened. . A technique for this is disclosed in Japanese Utility Model Laid-Open No. 60-80868. In this technique, the structures shown in FIGS. 5 and 6 are proposed. In the figure, reference numeral 22 denotes a rotary drive shaft, in which a sleeve 23 is slidably accommodated. A long hole extending in the axial direction is provided in a side wall of the rotary drive shaft 22, and both ends of a pin 24 fixed in a radial direction to a rear end of the sleeve 23 are loosely fitted in the long hole. The sleeve 23 is bendable around the rear end of the rotary drive shaft 22 within a predetermined range. An intermediate portion of the sleeve 23 is formed with a tapered surface 23 a for axial center alignment.
Has a circular hole 22a centered on the axis. A spring 26 is interposed between the sleeve 23 and the rotary drive shaft 22, and as shown in FIG. 5, the taper surface 23 a for aligning the shaft center is always in contact with the circular hole 22 a, and Axes coincide with each other. As shown in FIG.
When the sleeve 23 is retracted, the taper surface 23 for axial centering is set.
a is detached from the circular hole 22a, and the sleeve 23 can be bent.

According to this structure, the rotary drive shaft 22 is normally
When the axis of rotation of the screw and the axis of rotation of the rotary drive shaft are misaligned, the sleeve 23 is bent as shown in FIG. Screws can be tightened.

[0004]

However, in such a tightening device, the sleeve 23 cannot be bent unless the sleeve 23 is retracted and the tapered surface 23a for axial centering is separated from the circular hole 22a. That is, as long as a considerably large force acts between the temporarily fixed screw 25 and the sleeve 23 and the sleeve 23 does not retreat against the force of the spring 26,
The sleeve 23 does not bend. For this reason, there is a problem in that a relatively large force acts on the screws 25 before the head of the screw is fitted with the fitting hole 23c at the tip of the sleeve 23. Therefore, the present invention is intended to realize a structure in which the sleeve can bend with respect to the rotary drive shaft with a weaker force.

[0005]

For this purpose, the present invention has a rotary drive shaft, a sleeve, and a spring, and the rotary drive shaft is formed with a bearing surface perpendicular to the rotary shaft center. Has a fitting hole that fits into the head of the screw, a contact surface perpendicular to the axis of the sleeve is formed on the rear end side of the sleeve, and is provided between the rotary drive shaft and the sleeve. Both are bendable within a predetermined range, and a torque transmitting portion for transmitting the torque of the rotary drive shaft to the sleeve is formed, and the spring has a corresponding contact surface between the rotary drive shaft and the sleeve on the bearing surface. A screw tightening device characterized by being interposed so as to abut is produced.

[0006]

According to the tightening device of this structure, the contact surface and the bearing surface are always in contact with each other, and the sleeve and the rotary drive shaft are in the same axial center. On the other hand, if the rotational drive shaft and the rotational axis of the screws are misaligned, the sleeve bends.
At this time, if the bearing surface and the contact surface are slightly inclined, the sleeve can be bent, so that the sleeve bends with a small force.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS For convenience of explanation, an embodiment having a simple structure (see FIG. 3) will be described first. In FIG. 3, reference numeral 1 denotes a fixed rotary drive shaft, which is rotationally driven by a motor (not shown). The fixed rotary drive shaft 1 is formed with a cylindrical surface 1a for axial centering and a rectangular section 1b for torque transmission. 2 in the figure
Denotes a replacement rotary drive shaft, which is detachable from the fixed rotary drive shaft 1. The replacement rotary drive shaft 2 has a guide surface 2a for centering the shaft and a rectangular hole 2b for torque transmission. Both fixed shafts 1 and 2 are detachable and can transmit torque with the shafts aligned when mounted. Fixed to

On the tip end side of the replacement rotary drive shaft 2, a square section 2d for transmitting torque and a projection 2e for stopper are formed. In the drawing, reference numeral 3 denotes a sleeve, and a hole 3a having a rectangular cross section is formed in the sleeve 3. This hole 3a is fitted with a small clearance to the above-described square section 2d for transmitting torque, and transmits the torque of the rotary drive shaft 2 to the sleeve 3, and the sleeve 3 can be bent to the rotary drive shaft 2 within a predetermined range. (See also [B] of FIG. 2). Hole 3a
The retainer 4 is screwed to the rear end of the sleeve 3 via the ring plate 5 in a state where the compression spring 6 is inserted therein and the torque transmitting portion 2d of the rotary drive shaft 2 is pushed into the hole 3a. As a result, the sleeve 3 is prevented from coming off the rotary drive shaft 2. In the mounted state of the ring plate 5, the front end face 5 a is orthogonal to the axis of the sleeve 3. That is, this is the contact surface of the present invention. The rear end surface 2c of the torque transmitting portion 2d is orthogonal to the rotation axis of the rotary drive shaft 2 and serves as a bearing surface.

At the end of the sleep 3, there is formed a fitting hole 3c for fitting into the head of the bolt / nut, and the magnets 12 are fixed to both sides thereof. According to the tightening device of this structure, as long as there is no lateral external force acting on the sleeve 3,
The contact surface 5a on the side of the sleeve 3 and the bearing surface 2c on the side of the rotary drive shaft 2 are contacted by the spring 6, and the sleeve 3 and the rotary drive shaft 2
Have the same axis. That is, the tip position of the sleeve 3 can be controlled in this state. If the axes of the temporarily fixed screws and the axis of the rotary drive shaft 2 are displaced, an external force acts on the sleeve 3 laterally, and the sleeve 3 is bent. As a result, the heads of the screws are fitted into the fitting holes 3c of the sleeve 3, and the screws can be tightened. At this time, if a slight gap is formed between the bearing surface 2c and the contact surface 5a, the sleeve 3 can be bent, so that the sleeve 3 is easily bent. When the rear end face 3b abuts on the protruding face 2e, the sleeve 3 does not retreat further.

As described above, according to the present embodiment, before the sleeve 3 is fitted to the screw head, the sleeve 3 is aligned with the axis of the rotary drive shaft 2 and does not rattle. Can easily be fitted. If the position of the screw head is shifted, the sleeve 3 is easily bent.
At this time, since the sleeve 3 is easily bent, the work or the like is prevented from being damaged.

Next, an example in which a movable sleeve 7 is added to the sleeve 3 will be described with reference to FIG. This embodiment has the same structure except that a movable sleeve 7 is added to the structure of FIG. 3, and therefore only different points will be described.

In this case, a guide hole 3c is formed along the axis from the distal end side of the sleeve 3, and the guide surface 7a of the movable sleeve 7 is slidably housed therein. The movable sleeve 7 has a through hole 7b formed in the radial direction. A long hole 3d extending in the axial direction is formed on a side wall of the sleeve 3 at a position corresponding to the through hole 7b. The pin 8 is inserted through the long hole 3d, the through hole 7b, and the long hole 3d, so that the movable sleeve 7 is prevented from rotating with respect to the sleeve 3, and is slidable. The protruding end of the sleeve 3 of the pin 8 is connected to an O-ring 10 through a ring 9.
To prevent the pins 8 from falling off. At the tip of the movable sleeve 7, there is provided a fitting hole 7c for fitting to the head of the screw, and the magnets 12 are fixed to both sides.

According to this embodiment, since the movable sleeve 7 can slide, the screws can be tightened without moving the rotary drive shafts 1 and 2 in the axial direction. Further, since the movable sleeve 7 can slide, the sleeves 3 and 7 bend more easily and do not damage the work.

In this embodiment, since the tip end side of the fixed rotary drive shaft 1 relative to the replacement rotary drive shaft 2 can be replaced as a whole, various sleeves can be mounted on the same tightening machine. . In this embodiment, the center of the fixed rotary drive shaft 1 and the replacement rotary drive shaft 2 are aligned by the guide surfaces 2a, 1a. Can be secured. Further, the sleeve can be directly attached to the fixed rotary drive shaft.

[0015]

According to the present invention, since the rotary drive shaft and the sleeve are always coaxial, the positioning of the tip of the sleeve is easy, and the screw shaft having the axis shifted from the axis of the rotary drive shaft. The sleeve bends easily when tightening. For this reason, smooth tightening is performed and the work is not damaged.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment.

FIG. 2 is a cross-sectional view of one embodiment.

FIG. 3 is a longitudinal sectional view of another embodiment.

FIG. 4 is a diagram showing a state of bending and screwing;

FIG. 5 is a diagram showing a conventional technique.

FIG. 6 is a diagram showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed rotary drive shaft 2 Replacement rotary drive shaft 2d Torque transmitting cross section 2c Bearing surface 3 Sleeve 3a Torque transmitting cross section rectangular hole 5 Guide ring 5a Contact surface 6 Spring 7 Movable sleeve

Claims (1)

(57) [Claims] 1. A rotary drive shaft, a sleeve, and a spring, wherein the rotary drive shaft is formed with a bearing surface orthogonal to the rotation axis, and a tip of the sleeve is fitted to a head of screws. A contact surface perpendicular to the axis of the sleeve is formed on the rear end side of the sleeve, and both can be bent within a predetermined range between the rotary drive shaft and the sleeve. A torque transmitting portion for transmitting the torque of the rotary drive shaft to the sleeve is formed, and the spring is interposed between the rotary drive shaft and the sleeve such that a corresponding contact surface abuts on the bearing surface. A screw tightening device, comprising: