JPH042421A - Screw tightening device - Google Patents

Abstract

PURPOSE:To facilitate screw tightening to a prescribed torque by detecting torque applied to a wrench at the time of screw tightening with a torque transducer, and improving response to the torque applied to the wrench. CONSTITUTION:If the output shaft 7a of a reduction gear is rotated, rotational force is transmitted to an output shaft 9 through the first element 16, the third element 18, and the second element 17. If torque is applied to the shaft 9 by the screw tightening, the element 18 attempts to rotate with a spindle 23 centered together with an intermediate member 22 by its reaction force. Namely, if such torque is applied to the shaft 9, the corresponding torque is applied to the element 16 and the element 17, and then the element 18 attempts to displace itself according to the torque applied between them. The force where the intermediate member 22 attempts to rotate works so as to make a flexible plate 25 warp, and its bending amount corresponds to the torque. Next, the bending amount of the flexible plate 25 is detected by a detecting element 27, and torque can be determined from an output signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a screw tightening device used for tightening screws such as bolts or NANDs.

[Conventional technology]

FIG. 12 is a diagram showing an outline of the screw tightening device.

The rotation of the motor 6 rotating at high speed is reduced by a reducer 7, the torque is increased, and the torque is transmitted to the output shaft 9. Turn the bolt with a wrench 10 attached to the output shaft. A torque transducer 51 is located between the reducer 7 and the mounting base 3. Its structure includes a toque 9-by-pipe 52 with one end attached to the mounting base 3 and the other end attached to the case of the reducer 7, which can be twisted by the reaction of the wrench 10. tone pin pipe 5
A strain gauge 53 is attached to 2 so that the torque can be determined from the output thereof. A wrench 10 tightens the bolt, and when a predetermined torque is reached, the motor 6 is stopped.

[Problem to be solved by the invention]

In this conventional screw tightening device, the torque transducer 51 generates an output corresponding to torque in the following manner.

That is, due to the reaction of the wrench 10, the part where the motor rotor and the reducer 7 are integrated rotates in the opposite direction, and the torsion pipe 5
Twist 2. The twisting deforms the strain gauge, and the strain gauge produces an output corresponding to the torque.

However, the motor 6 and the reducer 70 are replaced by the wrench 10.
Since the bolt is extremely heavy and therefore has a large inertia, even if the bolt reaches a predetermined torque, the output of the torque transducer 51 has not yet reached the value corresponding to the torque. That is, there is a significant time lag between the torque experienced by the bolt and the torque experienced by the torque transducer. For this reason, there was a problem in that it was difficult to tighten the bolts to the correct torque value.

The present invention was made in order to solve the above-mentioned problems (technical tricks! It is an object of the present invention to provide a screw tightening device that can perform the following operations.

[Means to solve problems]

In order to achieve the above object, the present invention takes the measures as described in the claims above, and its effects are as follows.

[Effect]

The rotational force of the drive mechanism is transmitted to the wrench through first and second elements in the torque transducer. When tightening a screw with the wrench, a torque corresponding to the torque applied to the wrench is applied between the first element and the second element in the torque transducer. The torque causes the third element in the torque transducer to undergo a displacement corresponding to the torque. The displacement of the third element is detected by the detection element.

〔Example〕

The drawings showing the embodiments of the present application will be described below.

In FIG. 1, 1 indicates a screw tightening device, 2 is a stand in the device, and 3 is a mounting base.
It is mounted so that it can move up and down.

5 shows a nut runner attached to the mounting base 3.

To explain this naph runner 5, 6 is a motor;
7 is a reduction gear, which is shown as a drive mechanism of the napht runner. 8 is a torque transducer, 9 is an output shaft of a nut runner, and a wrench 10 is attached thereto.

When tightening the workpiece 11 to the workpiece 12 with the bolt 13 using the screw tightening device configured as described above,
First, the wrench 10 is fitted onto the bolt head 13a. Next, the motor 6 is activated. Then, the rotational force is reduced by 1fi
After being decelerated at step 7, the torque is applied from the output shaft 9 to the wrench 10 via the torque transducer 8, and the wrench 10 rotates the bolt 13. Bolt ff1 in bolt 13
When 3a is seated on the workpiece 11, the torque applied to the wrench 10 increases. The increase in torque is detected by the torque transducer 8 and its output signal causes the motor 6 to stop operating.

Next, the structure of the torque transducer 8 in the screw tightening device 1 will be explained in detail with reference to FIGS. 2 to 5. Incidentally, FIG. 5 shows the principle of the mechanism of the torque transducer. In these figures, a base frame 15 also serves as a case, and its lower end is attached to the mounting base 3, and the case of the speed reducer 7 is fixedly attached to the upper end of the base frame 15. Reference numeral 16 denotes a bevel gear exemplified as the first element, which is fixed to the output shaft 7a of the reduction gear 7 so as to receive the driving force from the reduction gear which is the previous stage. Reference numeral 17 denotes a bevel gear illustrated as a second element, which is fixed to the output shaft 9. Reference numeral 18 denotes a bevel gear illustrated as a third element, which meshes with the first element 16 and the second element 17, and can be displaced in accordance with the torque applied between the first element 16 and the second element 17. It is supported by a support mechanism 20, which will be described below.

Next, the support mechanism 20 will be explained. 21 is a support plate fixed to the base frame 15, 22 is an intermediate member, and an integrally provided support shaft 23.23 is supported by the support plate 21 and rotates about the same axis as the output shafts 7a and 9. It is now possible to do so. Reference numeral 24 denotes a support shaft that is integrally provided with the intermediate member 22, and the third element IB is rotatably mounted on this support shaft 24. 25 is a distortion plate, one end of which is fixed to the intermediate member 22 (integrally formed), and the other end 25a fixed to the base frame 15 as a fixed end.

Next, 27 is a detection element adapted to detect the amount of displacement of the third element 18, for example a strain gauge is used, and is attached to the strain plate 25.

In the above configuration, when the output shaft 7a of the reducer rotates, the rotation force is transmitted to the first element 16, the third element 18, and the second element 16.
It is transmitted to the output shaft 9 via the element 17 in turn. When torque is applied to the output shaft 9 by tightening the screws in the above state, the third element 18 receives the reaction force and tends to rotate together with the intermediate member 22 about the support shaft 23 . In other words,
When the above torque is applied to the output shaft 9, a corresponding torque is applied between the first element 16 and the second element 17, so the third element 18 is displaced ( Intermediate member 22 to which third element 18 is attached
The force that causes the intermediate member 22 to rotate as described above bends the distortion plate 25 so as to warp it. Naturally, the amount of bending corresponds to the above torque. The above amount of bending of the distortion plate 25 needs to be detected! 27, and the magnitude of the torque can be known from the output signal therefrom.

Next, FIGS. 6 to 8 showing different embodiments of the present application will be described. These figures show an example of a torque transducer 8e using a planetary gear mechanism. In the figure, 31 is a sun gear illustrated as a first element, and is fixed to the output shaft 7ae of the reducer. Reference numeral 32 denotes a planetary gear illustrated as a second element, which is connected to the output shaft 9e via a planetary carrier 33. The planetary carrier 33 has a well-known structure; 34 is a plate fixed to the output shaft 9e;
5 is a support shaft fixed to the plate 34, and the planetary gear 3 is attached to this support shaft.
2 is rotatably mounted. Reference numeral 36 denotes an internal gear exemplified as a third element, which can be displaced in accordance with the torque applied between the sun gear 31 and the planetary gear 32.
The boss portion 36a is rotatably attached to the output shaft 7ae, and the strain plate 25e is connected to the boss portion 36a.

With such a configuration, the rotational force of the output shaft 7ae is transmitted through the sun gear 31 and the planetary gears 32 to the output shaft 9e.
can be conveyed to.

When torque is applied to the output shaft 9e in this state, a corresponding torque is applied between the sun gear 31 and the planetary gears 32. Then, the third element 36 attempts to rotate in response to the reaction force from the second element 32, thereby bending the distortion plate 25e. As a result, a signal corresponding to the torque can be obtained at the detection element 27e.

It should be noted that parts that are considered to have the same or equivalent structure as those in the previous figure in terms of function are given the same reference numerals as in the previous figure with the letter e, and redundant explanations are omitted.

(Furthermore, the same concept will be used in the next and subsequent works, and the redundant explanation will be omitted by adding "f" for alpha vent.) Next, Figs. 9 to 11 show further different embodiments of the structure of the torque transducer. It is.

In the figure, 41 is a pulley illustrated as the first element,
It is fixed to the output shaft 7af of the speed reducer. A pulley 42 is illustrated as a second element, and is fixed to the output shaft 9f. Reference numeral 43 denotes a belt for connecting both pulleys 41 and 42, and a belt is passed between the pulleys 41 and 42 via a pulley 44, which will be described next. The pulley 44 is illustrated as a third element, and is supported by a support mechanism 45 so as to be able to be displaced in response to the torque applied between the first and second elements 41 and 42. Next, this support mechanism 45 will be explained. Reference numeral 46 is a support arm rotatably attached to the output shaft 7af so as to be able to rotate around the output shaft 7af. A third element 44 is rotatably supported, and further this support arm 46
As shown in FIG. 10, a strain plate 25f is connected to the tip.

In the above configuration, when the output shaft 7af of the speed reducer rotates, the rotational force is transmitted from the first element 41 to the output shaft 9f via the belt 43 and the second element 42.

When torque is applied to the output shaft 9f in this state, a corresponding torque is applied between the first element 41 and the second element 42. The third element 44 receives the reaction force, and the output shaft 7a
Trying to rotate around f. The rotational force is the support arm 46
Since the distortion plate 25f is deflected through the detection element 27f, a signal corresponding to the above-mentioned torque can be obtained from the detection element 27f.

〔Effect of the invention〕

As described above, in the case of screw tightening, by detecting the torque applied to the wrench lO with the torque transducer 8, the present invention not only makes it possible to tighten the screw to a predetermined torque value, but also enables the screw tightening to a predetermined torque value. Detection can be performed with good responsiveness, and the screw can be easily tightened to the predetermined torque value.

[Brief explanation of the drawing]

The drawings show an embodiment of the present application, and Fig. 1 is a side view of the screw tightening device, Fig. 2 is a longitudinal sectional view of the torque transducer, Fig. 3 is a sectional view taken along the line ■■ in Fig. 2, and Fig. 4 is a sectional view of the torque transducer. 5 is a perspective view showing the relationship between the intermediate member, strain plate, and strain gauge; FIG. 5 is a diagram showing the principle of the torque transducer shown in FIG. 2; FIG. Figure 7 is a sectional view taken along the line ■-■ in Figure 6.
The figure shows the principle of the torque transducer in Figure 6.
FIG. 9 is a longitudinal sectional view showing a further different embodiment of the torque transducer, FIG. 10 is a sectional view taken along the line X-X in FIG. 9, FIG. 11 is a diagram showing the principle of the torque transducer of FIG. 9, and FIG. The figure is a partially cutaway view showing the main parts of a conventional screw tightening device. 6...Motor, 7...Reducer, 8...Torque transducer, 9...Output shaft, 10...Wrench, 16
...first element, 17...second element, 18...third
element. Figure G

Claims (1)

[Claims] A screw tightening device comprising a drive mechanism and a wrench rotated by the drive mechanism, and a torque transducer interposed between the drive mechanism and the wrench, wherein the torque transducer is It has a first element connected to a drive mechanism to receive a driving force therefrom, and a second element connected to the wrench, and the first element and the second element are connected to the first element. said torque transducer is interconnected to transmit said driving force to said first element.
A screw tightening device comprising: a third element that is configured to be displaced in accordance with the torque applied between the element and the second element; and a detection element that is configured to detect the displacement of the third element. .