JPH0239752Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a nut rotating device for a bolt tensioning machine.

(b) Prior Art When joining a lid to the main body of a pressure vessel, a bolt tensioner is used that tensions a stud bolt and rotates a nut. For example, as a conventional bolt tensioning machine,
-There is something like the one shown in Publication No. 37065,
Such bolt tensioning machines use a hydraulic cylinder to apply tension to the stud bolt and an air motor to rotate the nut.

(c) Problems that the invention attempts to solve However, such conventional bolt tensioning machines have
There is a problem in that final adjustment and tightening work is required manually. In other words, simply pulling the stud bolts with a predetermined force and tightening the nuts with an air motor will not bring the elongation of all the bolts within the specified range, and if the stud bolts are outside the specified range, work will be required. It was necessary for a person to rotate the nut by an angle corresponding to the over-extension or under-extension of the stud bolt. For this reason, it is necessary for workers to work in close proximity to the pressure vessel, and in the case of a pressure vessel for a nuclear reactor, the exposure dose increases, which is undesirable from a health and safety perspective. In addition, the work takes time and there is a problem in terms of work efficiency. The present invention aims to solve these problems.

(d) Means for solving the problems The present invention solves the above problems by causing the rotation of the nut to be performed by an electric motor, and by detecting the rotation of the nut and controlling the operation of the electric motor. . That is, the nut rotating device for a bolt tensioning machine according to the present invention includes an electric motor capable of rotationally driving a nut, a motor control device that controls the operation of the electric motor according to a given rotational speed signal, and a rotation detection device that detects the rotation of the electric motor. a stall rotation speed setting device that sets the high rotation speed of the motor, an adjustment rotation speed setting device that sets the low rotation speed of the electric motor, and the rotation speed from the stall rotation speed setting device and the adjustment rotation speed setting device. A speed/rotation direction selector for selecting a desired one of the signals and commanding a desired rotation direction, and turning on/off the input of the rotation speed signal from the speed/rotation direction selector to the motor control device. A switching device, a rotation command self-holding device for controlling the switching device that is set when a rotation start signal is given, and a rotation command self-holding device that is set when a rotation start signal is given, and a rotation command self-holding device that is set when a signal from the rotation detector indicates that the rotation of the nut has stopped. a stall state discriminator that gives a reset signal to the nut, a counter that measures the number of rotations of the nut based on a signal from the rotation detector, and an adjustment tightening rotation speed setting device that sets the rotation speed of the adjustment tightening;
It has a comparator that compares the nut rotation speed from the counter and the set rotation speed from the adjustment/tightening rotation speed setter and provides a reset signal to the rotation command self-holding device when the two match.

(e) Action First, rotate the nut at high speed while pulling the stud bolt with a predetermined hydraulic pressure. That is, the signal from the stall rotation speed setting device is selected by the speed/rotation direction selector, thereby rotating the electric motor and tightening the nut. When the nut has been tightened, the rotation command self-retainer is reset by the stall state discriminator, and the rotation of the electric motor is stopped. After tightening all nuts in this manner, measure the amount of elongation of the stud bolts, and adjust and tighten any stud bolts that are not within the specified range as follows. That is, the required number of rotations of the nut is calculated from the amount of excess or deficiency in the elongation of the stud bolt, and this is set by the adjustment/tightening rotation speed setting device. Further, the speed/rotation direction selector selects the signal from the adjustment/tightening rotation speed setting device, and also selects the rotation direction of whether to tighten or loosen the nut. This causes the motor to rotate at a low speed and rotates the nut. The rotation speed of the nut is measured by a counter, and when this matches the rotation speed set on the adjustment tightening rotation speed setting device, the comparator resets the rotation command self-retainer,
Stop the rotation of the electric motor. As a result, the nut is rotated by a predetermined amount in a predetermined direction, and the elongation of the stud bolt falls within a predetermined range.

(F) Example The following is an example of the present invention as shown in Figures 1 and 2 of the attached drawings.
This will be explained based on the diagram.

As shown in FIG. 1, an electric motor 10 is connected to a nut tightening mechanism 12 consisting of gears and a clutch, thereby enabling a nut 14 to be driven in rotation. The nut 14 is attached to a stud bolt 18 passing through the flange 16. Electric motor 1
0 is provided with a rotation detector 20 constituted by a rotary encoder, which can detect the rotation of the electric motor 10 (that is, the rotation of the nut 14). The rotation of the electric motor 10 is controlled by an electric signal from a motor control device 22 (amplifier). A switch 24 turns on and off the input of a signal indicating a predetermined speed to the motor control device 22 . That is, one of the signals indicating the high and low rotational speeds set by the stall rotational speed setter 26 and the adjustment tightening rotational speed setter 28, respectively, is selected by the speed/rotational direction selector 30. is input to the switch 24,
Switching of whether or not to input this signal to the motor control device 22 is controlled by a signal from the rotation command self-holding device 32. The rotation command self-holding device 32 is set by inputting a rotation start signal (this signal is generated, for example, by an operator's switch operation), and is also set by a reset signal from either the stall state discriminator 34 or the comparator 36. It is configured to be reset by. The stall state discriminator 34 can detect that the rotation of the nut 14 has stopped based on the signal from the rotation detector 20. In this case, a reset signal is output. Further, the comparator 36 outputs a reset signal when the counted value of the counter 38 reaches the value set in the adjustment tightening rotation speed setting device 40. The counter 38 counts the integrated value of the number of rotations of the nut 14 based on the signal from the rotation detector 20. An example of a specific circuit configuration of the configuration shown as a block diagram in FIG. 1 is shown in FIG. 2, and reference numerals corresponding to those in FIG. do.

Next, the operation of this embodiment will be explained. A high rotation speed is set in the stall rotation speed setter 26, and a low rotation speed is set in the adjustment tightening rotation speed setter 28. In the speed/rotation direction selector 30, the rotation speed of the stall rotation speed setting device 26 is first selected by a signal generated by a switch operation by the operator, and the normal rotation direction is selected as the rotation direction. In this state, the specified stud bolt 18
is pulled with a predetermined force by a hydraulic cylinder (not shown). The tensile force applied to the stud bolt 18 is calculated in advance based on the length, diameter, elastic modulus, etc. of the stud bolt 18 so as to obtain a predetermined amount of elongation. In this state, the nut tightening mechanism 12 is engaged with the nut 14,
The nut 14 is made rotatable by the electric motor 10. When the start button is operated and a rotation start signal is given to the rotation command self-holding device 32, the rotation command self-holding device 32 enters the set state and holds the switch 24 in the on state. As a result, a signal from the speed/rotation direction selector 30 is input to the motor control device 22, and the motor control device 22 operates the motor 10 at the rotation speed set by the stall rotation speed setting device 26. As a result, the nut 14 is tightened to a position where it contacts the end surface of the flange 16. The rotation of the electric motor 10 is detected by the rotation detector 20, and when the stall state discriminator 34 detects that the electric motor 10 has stopped, a reset signal is given to the rotation command self-holding device 32. As a result, the switch 24 is turned off, and the rotation of the electric motor 10 is stopped. This completes the first tightening of the nut 14. All stud bolts 18 and nuts 14 provided in the pressure vessel are tightened in the same manner as above. As a result, the amount of elongation of the stud bolts 18 should be a predetermined value, but when the stud bolts 18 are tightened one after another, the flanges 16 will gradually deform, so the stud bolts 18 once tightened will also become more difficult to tighten than other studs. Stud bolts whose elongation changes due to the effects of tightening the bolt 18, and whose elongation does not fall within the specified range due to variations in hydraulic pressure, variations in the dimensions of the stud bolt 18, variations in material, etc. 18 occurs. Therefore, the amount of elongation is measured for all stud bolts 18. This measurement is performed using, for example, a microgauge. If the amount of elongation is within the specified range as a result of this measurement, the second adjustment tightening is performed as follows. First, calculate the difference between the measured elongation amount and the target elongation amount,
Based on this and the pitch of the stud bolt 18, it is calculated how many more rotations the nut 14 should be tightened or loosened, and the result is set in the adjustment/tightening rotation speed setting device 40. Speed/rotation direction selector 3
0 operates to select the signal of the adjustment tightening rotation speed setter 28, and also commands whether to rotate forward or reverse depending on whether the stud bolt 18 is overextended or underextended. When a rotation start signal is input to the rotation command self-holding device 32 in this state, the switch 24 is turned on and the electric motor 10 rotates at a low speed in a predetermined direction. In addition, in this case as well, stud bolt 1
Since a tensile force is applied to the nut 1 by a hydraulic cylinder, the rotational force of the electric motor 10 is applied to the nut 1.
4 can be rotated. The rotation of the electric motor 10 (that is, the rotation of the nut 14) is detected by the rotation detector 2.
0, which is input to the counter 38. The counter 38 counts the number of rotations of the nut 14 based on the signal from the rotation detector 20. The signal from the counter 38 is input to the comparator 36, and the comparator 36 compares the setting value set by the adjustment tightening rotation speed setting device 40 with the value from the counter 38. When the numerical value reaches the set value, a reset signal is output to the rotation command self-holding device 32. As a result, the switching device 24
is turned off, and the rotation of the electric motor 10 is stopped. Accordingly, the nut 14 is screwed in or loosened by the number of rotations set by the adjustment rotation speed setting device 40. Thereafter, the hydraulic pressure is released and the tensile force on the stud bolt 18 is removed, so that the stud bolt 18 stretches to a predetermined amount. All stud bolts 18 whose elongation did not fall within the specified range at the first tightening should be tightened in this manner.
Do about. This allows all stud bolts 18
The amount of elongation will be within the specified range.

(g) Effects of the invention As explained above, the nut rotation device of the bolt tensioning machine according to the invention is capable of two functions: nut stall tightening, which tightens the nut at high speed, and nut adjustment, which tightens the nut by directly controlling the amount of extension of the stud bolt. Since the nut adjustment and tightening work, which previously had to be done manually, can now be done automatically by remote control, the amount of radiation exposure can be reduced, and the amount of work and work time has also been shortened. Ru.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a nut rotating device for a bolt tensioning machine according to the present invention, and FIG. 2 is a diagram showing a specific circuit configuration of the nut rotating device for the bolt tensioning machine shown in FIG. 10...Electric motor, 12...Nut tightening mechanism, 1
4... Nut, 16... Flange, 18... Stud bolt, 20... Rotation detector, 22... Motor control device, 24... Switching device, 26... Stall rotation speed setting device, 28... Adjustment tightening Rotation speed setter, 30...Speed/rotation direction selector, 32...Rotation command self-retainer, 34...Stall state discriminator, 36...Comparator, 38...Counter, 40
...Adjustment tightening rotation speed setting device.

Claims (1)

[Claim for Utility Model Registration] A nut rotating device for a bolt tensioning machine that tightens a nut while applying a tensile force to a stud bolt. A motor control device that controls the operation, a rotation detector that detects the rotation of the motor, a stall rotation speed setting device that sets the high rotation speed of the electric motor, and an adjustment rotation speed setting device that sets the low rotation speed of the electric motor. , a speed/rotation direction selector for selecting a desired one of the rotation speed signals from the stall rotation speed setter and the adjustment tightening rotation speed setter and commanding a desired rotation direction; and a speed/rotation direction selector for commanding a desired rotation direction. a switch for turning on and off the input of the rotation speed signal from the motor to the motor control device; a rotation command self-retainer for controlling the switch that is set when a rotation start signal is given;
A stall state discriminator that gives a reset signal to the rotation command self-retainer when the signal from the rotation detector indicates that the nut has stopped rotating, and measures the number of rotations of the nut based on the signal from the rotation detector. Compare the nut rotation speed from the counter and the set rotation speed from the adjustment tightening rotation speed setting device to set the rotation speed for adjustment tightening, and when the two match, the rotation will start. A nut rotating device for a bolt tensioning machine, comprising: a comparator that provides a reset signal to a command self-holding device.