JPS5815678A - Clamping device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] This invention relates to the improvement of a tightening device that uses impact force to tighten a fastener. Conventionally, impact wrenches and electric nut runners have been known as devices for tightening fasteners. The former type of impact wrench is widely used because it is easy and inexpensive, but it is difficult to achieve high-quality tightening. Therefore, electric nut runners and the like are used for those that require high-quality tightening, but these nut runners are large and expensive, and have drawbacks such as a large reaction force when tightening four nuts.

This invention was made with the aim of improving such conventional drawbacks, and aims to provide a relatively inexpensive tightening device that can perform high-precision tightening with the same ease as a conventional impact wrench. .

The present invention will be described in detail below.In general, when a fastener is tightened with an impact wrench or the like, if either the fastener or the member reaches a plastic region, the amount of strain will be greater than the force required for tightening. growing. Therefore, when further impact force is applied to the fastening tool, the relationship between the number of impacts and the axial force is as shown in Figure 1. When tightening, the axial force does not increase, and K is eventually broken. The relationship between the rotation angle and the tightening force after the fastener is seated is as shown in FIG. 2, and the increment of the rotation angle is K as shown in FIG. 3.

In other words, when a fastener is tightened, when the fastener or clamp member reaches its yield point, an inflection point will appear from the relationship between the number of blows and the rotation angle increment, so it is necessary to detect this and stop tightening. This makes it possible to perform tightening with high precision without breaking the fastener. This is the principle of the present invention.Next, an embodiment of the present invention will be described in detail with reference to the drawings shown in Figure 4 and below. A rotation angle detector 6 detects the rotation angle of the transmission shaft 5 from a disc 61 attached to the shaft 71 which generates a striking force by being driven by the hammer part 3. A strike detector is provided for detecting the number of strikes from the vibrations generated during strikes. The signal 1 detected by the impact detector 7 is inputted to the pulse converter 9 via the four-bass filter, where it is compared with the set value inputted from the level setting device 10, and the signal 1 is The signal is input as a pulse signal C to the first counter 11 and the second counter 12, respectively. First counter 11
Now, at the same time as the pulse signal O is input, the rotation angle detector 6
The pulse signal a inputted from the controller is counted until the next hitting signal C is inputted, and the count value is transferred to the memory 13, and simultaneously the next signal 00A force is output.
Counting of signal a is started again. As a result, the fixing tool rotation angle 0n-1 for each l impact is stored in the memory 13, and the number n of input impact signals O is counted by the second counter 12.

On the other hand, the rotation angle θn-1 for each blow stored in Memory Lo 3
is input to the subtracter I4 at the next rotation angle #h and 4, where #n-all-1 is calculated, and the difference d is output to the comparator I5. The comparator 15 receives a reference value from the rotation angle increment reference circuit 16, compares it with the output d of the subtracter 14, and when the rotation angle increment reaches the reference value e, the output is sent to the drive unit via the gate circuit 17. At the same time, the solenoid valve 18 provided at tx2 counter 12 is turned off to finish tightening the fastener, and at the same time, a count stop signal f is output to the tx2 counter 12 to stop counting. Further, the number of blows n counted by the second counter I2 is outputted to the comparator 19 and compared with the reference number of blows g input from the blow number tree quasi-circuit 20. The comparator 19 determines that a low-rigidity material has been mixed into the fixing tool if the number of hits is less than or equal to the reference number of hits, and that a high-rigidity material has been mixed in if the number of hits is greater, and displays this on the display 21.

Note that 22 in the figure is a drive unit start switch.

As described in detail above, this invention detects the rotation angle for each blow applied to the fixing tool during tightening, and finishes tightening when the increment of the rotation angle matches a preset reference incremental angle. K, it is possible to perform high-precision, high-quality tightening using small and inexpensive tightening devices such as impact wrenches, and tightening does not require a reaction force receiver to support the reaction force. Moreover, it is possible to tighten fasteners with high quality even in narrow places where conventional nut runners cannot tighten. Furthermore, by comparing the number of blows until completion of tightening with a standard value and displaying the result on the display, tightening can also be used to check the material quality of the material, and tightening can also be used to check the reliability of parts. It can be improved further.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the number of blows and the axial force for tightening, Figure 2 is a diagram showing the relationship between the number of hits and the rotation angle and axial force for tightening, and Figure 3 is a diagram showing the relationship between the number of blows and the rotation angle. 4 is a diagram showing the relationship between increments, and FIG.
The figure is a pull diagram of the same control system - 1 is the device main body for tightening, 2 is the drive section, 3 is the /S damper section, 4
is a socket, S is a transmission shaft, 6 is a rotation angle detector, F is a blow detector, Snow 1 is a counter, 14 is a subtractor, and 15 is a comparator. Applicant Komatsu Ltd. Representative Patent Attorney Masaaki Yonehara Patent Attorney Tadashi Hamamoto

Claims (1)

[Claims] The tightening device is made up of a drive part 2, a hammer part 3 which is driven by the drive part 2 and generates a striking force, and a transmission shaft 5 which transmits the striking force generated in the hammer part 3 to a socket 4. 1
In the vicinity of the hammer portion 3 and the transmission shaft 5, there are provided a strike detector 7 for detecting a strike from vibrations generated during a strike, and a rotation angle detector 6 for detecting a rotation angle from the rotation of the transmission shaft 50, and these detectors. 6. The signal detected by the counter IIK is inputted to the counter IIK, and the rotation angle count for each impact is calculated by the subtracter 14.
The rotation angle increment is calculated by inputting the input into Tightening is done by equipment/