JPS5850831B2 - bolt tightening device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a bolt tightening device.

Recently, the tightening control of bolts and nuts has become important, and the tightening torque needs to be adequately controlled.

For this reason, electric bolt tightening devices are now frequently used.

This method takes advantage of the fact that the torque of a motor is almost proportional to the input current, and when a bolt or nut is tightened and the current reaches a preset value, the motor is stopped and the tightening torque is managed at a nearly constant level. be.

Also, in rare cases, a torque detector is installed in the middle of the rotating output shaft of the power wrench via a slip ring, electromagnetic induction, or wireless device to control and record the tightening torque.

However, an electric bolt tightening device uses electric current to control the torque, and a hydraulic power wrench uses oil pressure to control the torque, so in a strict sense, the torque itself is not controlled.

This is because it is necessary to correct the torque for acceleration/deceleration and the increase in tightening torque due to inertia force after input cutoff.

Further, in the case of a torque detector attached to a rotating shaft, there is a problem that the device becomes complicated in order to send a signal from the rotating part to the fixed part.

Although FIGS. 1 to 3 show the bolt tightening device of the present invention, a conventional bolt tightening torque detection method will be explained using these drawings.

There is also a torque detector 13c attached to the claw 13b of the reaction force receiver 13, but in this case, due to the pitch error in the tightening position of the bolt/nut to be tightened, the bolt/nut adjacent to the claw 13b receiving the reaction force may The points of contact vary.

For this reason, it was impossible to detect the correct actual tightening torque with the torque detector 13c.

In addition, when the torque detector 13c is attached to the cylindrical portion 13a of the reaction force receiver 13, since the claw 13b is attached to the cylindrical portion 13a, the rigidity of the cylindrical portion 13a is not uniform, so the mounting position of the torque detector 13c is The detected torque changes significantly due to
It was not possible to detect the correct actual tightening torque.

In order to eliminate these conventional drawbacks, the inventor of the present application has conducted various experiments and measurements, and has found that in order to detect the correct actual tightening torque, the mounting position of the torque detector 13c should be set at the reaction force receiver 13. It has been found that there is a close relationship with the position of the claw 13b attached to the cylindrical portion 13a.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a DC series-wound commutator motor, the output of which is transmitted to a spur gear 5 via a spur gear 3 and a pinion 4 by a pinion 2 geared at one end of an armature shaft.

The output transmitted to the spur gear 5 is transmitted through a pinion 6' (in this case, the pinion 6' becomes the sun gear of the planetary gear 7) and a planetary gear. 7
is transmitted to the planetary frame 9 via an internal gear 8a geared on the inner surface of the housing 8.

A pinion 91 geared to one end of the planetary frame 9 serves as a sun gear of the planetary gear 10, and transmits high torque to the output shaft 11 via an internal gear 8b geared to the inner surface of the housing 8.

At the shaft end of this output shaft 11 is a square socket mounting portion 14'.
, and the socket 12 is fitted therein.

Furthermore, a reaction force receiver 13 is fitted onto the corner portion 14 of the main body, and fixed with a set screw 15 to prevent it from falling off.

As shown in FIGS. 2 and 3, the reaction force receiver 13 has a cylindrical portion 13.
A claw 13b is provided at the tip of the bolt a, and the other end is configured to fit into a corner 14 of the bolt tightening machine body.

In addition, since the claw 13b receives reaction force, the adjacent bolt
A vertical plane that includes the point O' in contact with the nut 17 and the straight line O'0 passing through the center O of the reaction force receiver 13 is the cylinder between the lower end of the shoulder 13d of the reaction force receiver 13 and the upper surface of the claw 13b. Take a point that intersects with the center outer circumferential line 16 passing through the center of the part 13a as a reference point S,
A point within an angle of 30° to 60° along the central outer circumferential line 16 of the reaction force receiver 13 from the reference point S is set as a reference point B,
In order to configure a bridge circuit with four torque detectors 13c, torque detectors are installed at positions B, 0', B', and 0, which are equally divided into four parts along the central outer circumferential line 16 of the reaction force receiver 13. 13c is installed, and these four torque detectors 13c form a bridge circuit. This eliminates the influence of the temperature of the torque detector 13c and the length of the lead wire, so that the actual tightening torque can be detected correctly. This is what I did.

As a result of various experiments and measurements, it has been found that the actual tightening torque can be detected correctly in this manner.

That is, regarding bolts M16, M2O, and M24,
In order to test the torque detector 13c, the torque detector 13c was first installed at a position that divided the center outer circumferential line 16 of the reaction force receiver 13 into four equal parts with the reference point S as the base point, but the The variation in tightening torque is extremely large.
It was not thought that it would be practical.

However, as a result of various tests, it has been found that in order to accurately detect the tightening torque, the mounting position of the torque detector 13c is closely related to the position of the claw 13b.

Therefore, along the central outer circumferential line 16 of the reaction force receiver 13 of the torque detector 13c, the angle is 30' and 45° from the reference point S.

For each case where the base point is a position 60° apart, a torque detector 13 is installed at a position that divides the center outer circumferential line 16 into four equal parts.
Install c, configure a bridge circuit, and tighten bolt Ml 6
, M2O, and M24 were subjected to static load tests and tightening tests.

As a result of investigating the relationship between the tightening torque and strain of each bolt through a static load test, the results were almost the same in each case. The full scale characteristics and hysteresis are shown in the table below.

In addition, torque detectors 13c were installed at positions that divided the center outer circumferential line 16 into four equal parts with the reference point S as the base point, and a bridge circuit was configured to perform a static load test on the bolt M16. The table below shows the hysteresis and hysteresis in full scale.

The definitions of nonlinearity (%) and hysteresis (%) here are as follows.

That is, as shown in Fig. 5, the horizontal axis represents the bolt tightening torque, and the vertical axis represents the output of the torque detector corresponding to this tightening torque.The origin is Q, and the tightening torque is calculated from O to the maximum value. The forward curve representing the change in the output of the torque detector when the torque is increased to T is QES', and then the tightening torque is set to the maximum value T.
An ideal proportional straight line connecting the return curve representing the change in the output of the torque detector when it is decreased from is QGS', and the points on the forward curve, return curve, and ideal proportional curve at tightening torque T1 are respectively E,
Assuming F and G, the ideal proportional straight line QGS' and the forward curve Q
The difference GE between the return curve S'F Q and the forward curve QES' represents the hysteresis. The ratio to S'T expressed in % is the nonlinearity (
%), and the ratio of the maximum value of FE to the maximum output S'T of the torque detector expressed in % is defined as hysteresis (%).

From the above static load test results, 30° from the reference point S,
Since it was found that non-linearity and hysteresis were extremely small and practical when using positions 45° and 60° apart as reference points, a tightening test was next conducted.

That is, after sequentially tightening bolts M16, M2O, and M24 to torques of 20, 40, 60, and 80 kg-m, the torques were sequentially reduced to 80, 60, 40, and 20.0 kg-m, As a result of the tightening torque detection test, almost the same results were obtained in each case.

FIG. 4 shows a portion of the test results recorded above, where the reference point is a position 45° away from the reference point S.

The vertical axis indicates torque (kg-m), and the horizontal axis indicates the feeding direction of the recording paper.

Figure 4 a shows the bolt M16 with a torque of 20.40°60kg.
- m, then the torque was reduced to 60, 40, 20, 0 kg-m and the torque detected by the torque detector 13c was recorded when the bolt M16 was released. The left side of the graph is for tightening, the right side is indicates the case where the restriction is lifted, and the variation with respect to the actual torque value is small, indicating a value that suits the actual situation.

Figures 4 and 4 show the results after tightening the bolts M20 and M24 with a torque of 20, 40, 60, sokg-m, respectively, 80, 60, 40, 20. Okg - This is a record of the detected torque by the torque detector 13c when the door is released by the torque of the door.The left side of each graph shows the case of tightening, and the right side shows the case of release. The variation in torque values is small and shows values that match the actual situation.

On the other hand, in FIG. 6, torque detectors 13c are located at positions where the center outer circumferential line 16 is divided into four equal parts with the reference point S as the base point.
, configure the bridge circuit, and sequentially tighten the bolts M16 to torques of 10, 20, 30, 40° and 50 kg-m, and then reversely tighten them to 50° and 40.30, 20, 10. O
This figure shows the results of a tightening test by sequentially reducing the door weight and torque.Compared to the results of the tightening test for the M16 bolt shown in Figure 4a, it is approximately 10 kg-m less. This shows that there is a large variation in the actual torque value.

In addition, one cross gauge each is used as a torque detector at positions B and 0 where the center outer circumferential line 16 of the reaction force receiver 13 is divided into four equal parts.
', B', C, or the opposing 2 of the four equally divided positions B, 0', B', 0.
Place one cross gauge at each location B, B' or 0.0'.
You can attach them one by one, or you can attach them to the four equally divided positions B.
, 0', B', and 0 may each have one or two single gauges installed.

Furthermore, two single gauges may be attached to each of the two opposing positions B, B' or 0, O' among the four equally divided positions B, 0', B', and C.

As described above, the tightening torque is controlled and recorded using the signal from the torque detector 13c attached to the reaction force receiver 13.

As described above, according to the present invention, the correct actual tightening torque can be controlled by the signal from the torque detector installed at the appropriate position of the reaction force receiver provided at the tip of the bolt tightening machine. It is easier to record, and since the torque detector is attached to a fixed part such as a reaction force receiver, it is easier to take out the signal, the equipment is simpler, and more precise torque management is possible. is an industrial jounin.

[Brief explanation of drawings]

Fig. 1 is a front view showing the main parts of the present invention in cross section, Fig. 2 is a perspective view of the reaction force receiver, Fig. 3 is a view taken in the direction of arrow A in Fig. 2, and Fig. 4 shows test data. 5 is an explanatory diagram of nonlinearity and hysteresis of the torque detector, and FIG. 6 is a diagram showing test data. 1...DC series commutator motor, 6...
Shaft, 8... Housing, 11... Output shaft, 1
3...Reaction force receiver, 13a...Cylinder part, 13
b...Claw, 13C...Torque detector. O... Center of reaction force receiver 13 0/... Point where claw 13b is in contact with adjacent bolt/nut 17, S... Reference point, B... ...Base point, B,
0, B', C! '...Torque detector 13
c Mounting position.

Claims (1)

[Claims] 1. A vertical plane including the point O' where the claw of the reaction force receiver attached to the tip of the bolt tightening machine contacts the adjacent bolt/nut and the straight line o'o passing through the center O of the reaction force receiver is , take as a reference point a point S that intersects with the central outer circumferential line passing through the center of the cylindrical part between the lower end of the shoulder of the reaction force receiver and the upper surface of the claw of the reaction force receiver, and from the reference point S, 30° along the center perimeter of
A bolt tightening device characterized in that a torque detector is installed at a position that divides the center outer circumferential line of the reaction force receiver into four equal parts with a point B within an angle 60 degrees away from the base point.