JPH0288127A - Seating confirming device for screw thread - Google Patents

Abstract

PURPOSE:To accurately seat a screw thread tightening unit by using an ultrasonic wave detecting the screw thread tightening unit, when it is seated and not seated, with a tightened unit seating surface reducing its sound pressure reflecting rate and echo voltage level. CONSTITUTION:A tightened unit 21 tightens a screw thread tightening unit 16, and its head part 17 fits a socket of a seating confirming device 5, further a transducer 13 is connected to an upper surface of the screw thread tightening unit head part 17 by utilizing resilient force of a spring 18. Then an ultrasonic wave is transmitted to the transducer 13, and echo voltage output by the transducer 13, that is, reflected voltage in a seating surface 21' of the tightened unit 21 is monitored by an oscillograph 25. When the echo voltage is in a high value not less than a preset value, seating is not completed. AS a result unsure seating can be easily detected.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention detects the gap (seating) between the seating surface of a screw fastening object such as a bolt or nut and the seating surface of an object to be fastened. The present invention relates to a seating confirmation device that can confirm the fastening of a screw fastening body.

[Prior Art] In order to check the degree of tightening of a bolt, nut, or other screwed body to a fastened body using a screw tightening machine,
It can be roughly divided into torque detection method and seating method.

[Problems to be Solved by the Invention] In the former torque detection method, complete screw tightening is completed when the resistance to the screwing force is large due to irregular shape or deformation of the female or both female screws, for example. The set tightening torque may reach the torque value before the tightening is done, and a tightening error 13 (erroneous operation) may occur. The latter seating confirmation method uses microswitches, proximity sensors, etc. to detect the amount of gap between the seating surface of the screw tightening body and the seating surface of the fastened object. The seating confirmation method can only make a rough determination, and it is difficult to reliably determine whether a person is seated or not.

[Means for Solving the Problems] The present invention has been made by focusing on the above-mentioned problem, and in particular uses ultrasonic waves to improve the accuracy of the screw tightening body when it is seated and when it is not seated. , a seating confirmation device that can accurately confirm the seating of a screw tightening object by focusing on the fact that the sound pressure reflectance of the seating surface of the fastened object decreases and the voltage level of the echo of the seating surface of the fastened object decreases. Our goal is to provide the following.

[Example] The present invention will be described in detail below based on an example shown in the drawings.

In FIG. 1, 1 is a robot device of an automatic screw tightening machine, and a bracket 3 is attached to the tip of a robot arm 2 of this robot device. A seating confirmation device 5, which is a device of the present invention, is mounted and supported. Next, the mechanism of this seating confirmation device 5 will be explained based on FIG. 2. Reference numeral 6 denotes a support cylinder which is vertically attached to the bracket 3 with a mounting screw 7. A vertical support shaft 8 is supported on the support cylinder 6 so as to be movable in the vertical direction. A flange 9 is integrally formed at the lower end of.

A flange 11 of a transducer holder lO is joined to the lower surface of this flange 9, and both flanges 9.
11 are connected by mounting screws 12. A transducer 13 is fitted and held inside the transducer holder 10, and the transducer 13 is fixed within the transducer holder 1a by a mounting screw 14. 15 is a socket screwed onto the lower side of the transducer holder 1o;
The head 17 of the screw fastener 1b is loosely fitted into the screw fastener 1b. Reference numeral 18 denotes a spring that is interposed between a flange portion 19 formed on the outer periphery of the support cylinder 6 and the flange 9 of the support shaft 8 to constantly bias the support shaft 8 downward; 20 represents the upper end of the support shaft 8; This is a stopper screw attached to the support shaft 8 to prevent the support shaft 8 from coming out from the support shaft cylinder 6.

The structure of the seating confirmation device 5 of this embodiment has been described above, and its operation will be explained next. In FIG. 2, the screw fastened body 16 is screwed onto the fastened body 21, and now the head bearing surface 17° of the screw fastened body 16 and the fastened body 21 are screwed together.
Measure the gap a of 21° on the seat surface of 1, and
b< This is to detect whether or not the person is seated.

Therefore, when detecting this, the screw fastening machine 4
The socket of the seating confirmation device 5 is fitted into the head 17 of the screw fastened body 16 fastened to the object 21 to be fastened, and the transformer is fitted onto the upper surface of the screw fastened body head 17 using the elastic force of the spring 18. The deuser 13 is joined. Therefore, the tM sonic pulse generator 22 shown in FIG. 3 is driven to transmit ultrasonic waves to the transducer 13. By transmitting ultrasonic waves to this transducer 13, the transducer 1
3, that is, the reflected voltage at the seat surface 21'' of the object to be fastened 21 is monitored by the oscilloscope 25 via the receiver 23 and the gate circuit 24. That is, the echo voltage output by the seat surface 21" is monitored by the oscilloscope 25. 21', the larger the gap a, the higher the echo voltage will be output.In other words, if the gap a is small and the seating has been completed, the echo voltage will be low.Therefore, if the echo voltage is higher than the set value, the echo voltage will be output. Since this means that the seating has not been completed, if the display 26 displays or generates an alarm at this time, it is possible to easily detect that the seating is uncertain. The fastening machine 4 performs refastening, and then the seating confirmation device 5 performs a re-inspection, and if the seating is completed, the next screw fastening is performed.

As described above, according to this embodiment, the transducer 1 is mounted on the upper surface of the head 17 of the screw fastening body 16 screwed onto the fastened body 21.
3 and supplying ultrasonic waves to the transducer 13, the strength of the echo voltage obtained can be detected to properly and accurately detect the seating condition of the screw fastener 16.

In the above embodiment, the seating confirmation device 5 is replaced by the screw fastening machine 4.
However, the present invention is not limited to this, and the seating confirmation device 5 may be carried by the worker and handled independently.

[Effects of the Invention] As described above, the present invention includes a transducer 13 whose oscillation surface is joined to the upper surface of the screw tightening body head 17, and an ultrasonic pulse generator for transmitting ultrasonic waves to the transducer. Vessel 2
2, a receiver 23 that receives the echo signal from the transducer, and detects the echo voltage level of the seat surface of the fastened body 21 by receiving the signal from the receiver and the signal from the ultrasonic pulse generator. Since this device is a screw seating confirmation device that has a gate circuit 24 that detects the screw fastening body 16 by supplying ultrasonic waves to the transducer 13, it detects the strength of the echo voltage obtained. This has the effect of being able to accurately and accurately detect the seating situation of the person.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, FIG. 2 is a sectional explanatory diagram of only the screw seating confirmation device, and FIG. 3 is a processing circuit diagram thereof. 1...Robot 2...Arm 3...
・Bracket 4...Screw fastener 5...Seating confirmation device 6...Support tube 7...Mounting screw
8...Vertical support shaft 9...Flange lO...Transducer holder 11...Flange 12...Mounting screw 1
3...Transducer 14...Mounting screw 15
... Socket 16 ... Screw fastening body 17
...Head 17°...Seat surface 18...
・Spring 19...Flange part 20...
・Stopper screw 21... Fastened object 21'...
・Seating surface diagram 1

Claims (1)

[Claims] 1. A transducer (13) whose oscillation surface is joined to the upper surface of the screw tightening body head (17), and an ultrasonic pulse generator (22) for transmitting ultrasonic waves to the transducer. , a receiver (23) that receives an echo signal from the transducer; and a receiver (23) that receives the signal from the receiver and the signal from the ultrasonic pulse generator to detect the echo voltage level of the seat surface of the fastened body (21). A screw seating confirmation device characterized in that it has a gate circuit (24) for checking the seating of a screw. 2. A power screw tightening device equipped with the seating confirmation device described above. 3. A screw tightening robot device comprising the above-mentioned seating confirmation device and a powered screw tightening device.