JPH0438540B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a nut runner that automatically tightens nuts, etc., and particularly relates to an improvement of a nut runner equipped with a tightening torque detection means.

(Prior Art) The drive mechanism of a nut runner includes a driven cam that is fixed in the axial direction and a drive cam that is movable in the axial direction. The driving force is transmitted to the tightening shaft through mutual engagement. Here, the tightening torque of the pressure spring can be set by the spring load, and when the tightening torque reaches the set value, the tightening torque exceeds the spring load, and the rotation of the driving cam and the driven cam is The driving cams are out of phase with each other, and the driving cam disengages from the driven cam, cutting off power transmission to the tightening shaft. However, unless the rotation of the drive shaft is stopped in this state, the drive cam will continue to rotate, and the drive cam will repeatedly engage and disengage from the driven cam, spinning idly, causing vibration and accelerating cam wear. .

The invention disclosed in Utility Model Publication No. 57-1095 eliminates these inconveniences. This idea is
Regarding electric screwdrivers, when the tightening torque increases and exceeds the spring load, the drive cam starts moving relative to the driven cam, and a micro switch etc. detects when this movement amount reaches a set value. to stop the rotation of the drive shaft.

(Problem to be Solved by the Invention) However, according to such conventional technology, the detection switch is turned on and off depending on whether the amount of movement of the drive cam reaches a set value, and the amount of movement and therefore the torque It was not possible to monitor the amount continuously and quantitatively. Therefore, changing the tightening torque is generally difficult, as it requires changing the spring load setting, for example.

Therefore, the present invention can continuously and quantitatively monitor the amount of movement of the drive cam relative to the driven cam, and thus the amount of torque, and can easily set and change the upper and lower limits of tightening torque. The purpose is to provide a nut tranner that is

(Means for solving the problem) The means for solving the above problem consists of a driven cam connected to the tightening shaft and fixed in the axial direction, and a driven cam that is removably engaged with the driven cam and has a predetermined position. A drive cam that starts to move in the axial direction when a tightening load is reached, and a drive that engages with this drive cam via a ball and restrains the drive cam in the circumferential direction by the ball and allows the drive cam to move in the axial direction. a shaft, a spring that presses the drive cam against the driven cam with a predetermined spring load, a housing that coaxially accommodates the driven cam, the drive cam, the drive shaft, and the spring, and a drive that drives the drive shaft. In the nut runner, a movement amount detection means is provided on the side of the housing to continuously detect the movement amount of the drive cam in the axial direction and control the drive section, and the movement amount detection means includes: an arm that comes into sliding contact with the rotation of the drive cam and follows the axial movement of the drive cam; a movable element that integrally supports the arm and moves in the axial direction within the case;
It is constructed of a spring that biases the movable element in the axial direction and a sensor for measuring the amount of movement provided coaxially with the movable element.

(Operation by the above means) According to the above means, the amount of movement of the drive cam can be continuously monitored and the drive can be stopped at an arbitrary amount of movement, that is, at an arbitrary tightening torque.

For this reason, for example, problems such as those caused when the drive cam is rotated idly to accelerate wear are eliminated.

Also, in this case, as the movement amount detection means provided on the side of the housing, the mover was moved via an arm that slidably contacted the rotation of the drive cam and followed it in the axial direction, so the drive cam rotated when the nut runner was driven. However, there is no need to move the sensor position.

In addition, by aligning the moving direction of the mover, the biasing direction of the spring, and the extending direction of the sensor with the direction of the tightening axis, it is possible to minimize lateral overhang. Can be placed in parallel.

(Embodiment of the Invention) Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view of a nut runner according to an embodiment of the invention. The nut runner is made up of a drive motor 1, a reduction mechanism 3, and a drive mechanism 6, and the end plate 8c of the drive mechanism 6 is fixed to a mounting frame 40 with bolts 41 to fixedly support the entire nut runner. below,
These components will be explained.

The drive motor 1 is, for example, an air motor, and drives a vane by supplying pressurized air from the outside.
to rotate the output shaft 2. This motor 1
The rotation of the output shaft 2 is transmitted to a speed reduction mechanism 3 consisting of, for example, a planetary gear, and the output shaft 4 of the speed reduction mechanism 3 obtains a desired rotational speed. The drive motor 1 and the speed reduction mechanism 3 are housed in cylindrical housings 1a and 3a, respectively, and are connected to each other by screws formed at each end thereof.

The drive mechanism 6 is for transmitting the rotation of the output shaft 4 of the deceleration mechanism 3 to the tightening shaft 10 or for canceling this transmission, and has a driven cam 12,
It includes a drive cam 14, a drive shaft 16, and a coil spring 18. The housing 8 is made up of two cylindrical parts 8A and 8B having different diameters,
A thread is formed on the inner diameter part of the end 8a of the portion 8A, and is screwed into the housing of the speed reduction mechanism 3, thereby connecting the parts 8A and 8A to each other. Further, as described above, a flange-shaped end plate 8c is integrally fixed to the end portion 8b of the portion 8B. This flange-like end plate 8c
As shown in FIG. 2, it has an oval shape that protrudes in the vertical direction. The tightening shaft 10 is attached to the end plate 8c.
The tightening shaft 10 extends outward in the axial direction, and its tip has a predetermined shape corresponding to the nut to be tightened.This tightening shaft 10 is rotatably supported by a bearing 9a and a thrust bearing 9b. A driven cam 12 is integrally formed at the end in the embodiment.
As shown in FIGS. 3 and 4, the driven cam 12 has slopes 12b, 12b symmetrically formed on the disc 12a at positions 180 degrees apart from each other, and these slopes 12b, 12b form a recessed portion having a trapezoidal cross section. 12c, and a drive cam 14 described later is formed in this recess 12c.
The male and female cams are formed by fitting and engaging the protruding cam portion 14b, and the flat surface 12d of the driven cam 12 that engages with the tightening shaft 10 makes surface contact with the thrust bearing 9b.

As shown in FIGS. 3 and 4, the drive cam 14 is provided with protruding portions 14b, 14b forming part of a circular arc at positions 180 degrees apart from each other on the disc 14a. engages with the recess 12c of the driven cam 12, and the drive cam 14
, a cylindrical portion 14c is provided on the opposite side of the disk 14a from which the protruding portion 14b is formed, and a drive shaft 16 connected to the output shaft 4 of the deceleration mechanism 3 passes through the center of the cylindrical portion 14c. The tip 16a is rotatably inserted into the axial hole 12e of the driven cam 12. The side of the drive shaft 16 connected to the output shaft 4 of the reduction mechanism 3 is connected to a cylindrical end block 19 disposed and fixed within the housing 8.
The driving shaft 16 is rotatably supported by a bearing 20a and a thrust bearing 20b fixed to the shaft, and as is clear from FIGS. A groove 16c extending in the direction is formed, and this groove 16c and the drive cam 14
Balls 15 are arranged and interposed between the cylindrical portions 14c and similar grooves 14d formed so as to face the inner diameter portions thereof. The balls 15 are each regulated by a pin 17 so as not to escape from the cylindrical portion 14 of the drive cam 14, and therefore,
The drive cam 14 is movable in the axial direction along the drive shaft 16 by rolling in the grooves 16c and 14d of the balls 15, and is also rotatable together with the drive shaft 16, so that the outer diameter of the main shaft portion 16b and the cylindrical portion A clearance ΔS is formed between the inner diameter of 14c and the inner diameter of 14c. Such a driving cam 14 is pressed against the driven cam 12 by a coil spring 18 disposed between the thrust bearing 20b and the coil spring 18.
The spring load of is determined as appropriate depending on the required tightening torque.

Further, a sensor 30 is disposed on the portion 8B of the housing 8 behind the area of the flange portion 8C, and a movable member 31 provided so as to face the sensor 30 is attached to an arm 32.
The movable element 31 and the sensor 30 are housed in a case 33 provided at the rear of one of the flange parts 8c of the housing 8.
is movable in the axial direction and is normally pressed forward by a return spring 34 to maintain a gap of ΔX between it and the sensor 30. Such a change in the amount of movement or displacement of the drive cam 14 can be detected by a magnetic sensor, various sensors that can detect changes in inductance or capacitance, a potentiometer, etc. that can detect the amount of movement by a change in resistance value, or an image. The drive cam 14 is optically driven by a sensor, etc.
Various types of devices can be used, such as those capable of monitoring the displacement of the edges of the device.

Next, the operation will be explained. When the drive motor 1 operates, the speed reduction mechanism 3 generates a predetermined rotational torque on its output shaft 4 and transmits it to the drive shaft 16. Initially, the drive cam 14 is engaged with the driven cam 12 in the state shown in FIGS. 3 and 4, and is pressed against the driven cam 12 by the spring 18. For this reason,
The drive shaft 16, drive cam 14, driven cam 12, and tightening shaft 10 rotate together to tighten the nut (not shown).
Tighten. At this time, the rotation of the drive shaft 16 is transmitted via the ball 15 to the drive cam 14 and the driven cam 12.
Therefore, even though the drive cam 14 is movable in the axial direction, there is no play in the axial or radial direction during the tightening rotation, and proper tightening is possible without the shaft center swinging. As such tightening progresses and the tightening torque increases, the tightening torque will exceed the spring load. For this reason,
Although the driving cam 14 rotates, the driven cam 12 no longer follows the same phase, and the protruding portion 14 of the driving cam 14 rotates.
b begins to move along the slope 12b of the driven cam 12, the entire drive cam 14 moves backward against the spring 18, and the movable element 31 moves in the direction of the sensor 30 so that ΔX
changes, the sensor 30 continuously and quantitatively monitors this amount of movement, and sends a signal to stop the supply of pressurized air to the motor, cutting off the supply of pressurized air and ending the tightening, thereby achieving the desired result. Tightening torque control can be performed.

In the above, since ΔX can be monitored continuously and quantitatively by the sensor, the tightening torque can be controlled by setting ΔX, unlike conventional on/off control.

In the embodiment, since the sensor 30 is provided behind the oval flange portion 8c, it does not protrude from the outer shape of the nut runner, and therefore a large number of nut runners can be arranged in parallel. Also, since ball 15 was used, cam 1
4 is moved more smoothly in the axial direction than in the conventional telescopic type, ensuring smooth operation.

(Effects of the Invention) According to the present invention as described above, by continuously and quantitatively detecting the displacement of the drive cam as the tightening torque increases, a nut runner having the following effects can be obtained.

In other words, the upper and lower limits of the tightening torque can be determined and quantitative torque control is possible, resulting in high reliability.Secondly, the set value of the tightening torque can be easily changed by the control system, and the setting value of the tightening torque can be easily changed by the movement amount detection means. There is no need to change the configuration, and because the ball is interposed between the drive shaft and drive cam, accurate tightening is possible without radial play even though the drive cam can be displaced in the axial direction. In addition, since the movement of the cam is smooth and highly reliable, and the movement amount detection means is configured to fit behind the flange of the end plate, when arranging multiple nut runners as shown in Fig. It has the advantage of being busy, such as being able to easily deal with situations in which several nuts are tightened at the same time.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a nut runner according to an embodiment of the present invention, FIG. 2 is a view taken from two directions in FIG. FIG. 5 is a sectional view of the main part taken along the line 5--5 in FIG. 1. In the drawing, 1 is a drive motor, 3 is a reduction mechanism, and 8 is a drive motor.
8c is a flange-like end plate of the housing 8; 10 is a tightening shaft; 12
is a driven cam, 14 is a driving cam, 15 is a ball, 1
6 is a drive shaft, 16c is a groove, 17 is a pin, 18 is a coil spring, and 30 is a movement amount detection means.

Claims (1)

[Claims] 1. A driven cam connected to the tightening shaft and fixed in the axial direction, and a drive that detachably engages with the driven cam and starts moving in the axial direction when a predetermined tightening load is reached. a cam, a drive shaft that engages the drive cam via a ball, restrains the drive cam in the circumferential direction by the ball, and allows movement in the axial direction; A nut runner comprising: a spring that presses with a spring load; a housing that coaxially accommodates the driven cam, the drive cam, the drive shaft, and the spring; and a drive section that drives the drive shaft; , a movement amount detection means for continuously detecting the amount of movement of the drive cam in the axial direction and controlling the drive section is provided; An arm that follows the movement in the direction, a movable element that integrally supports this arm and moves along the axial direction in the case, a spring that biases this movable element in the axial direction, and an arm that is coaxial with the movable element. A nut runner comprising a sensor for measuring the amount of movement provided in the nut runner.