JPH0216285Y2 - - Google Patents

Description

[Detailed description of the invention] Conventionally, when inspecting internal cracks that have occurred in the shaft or thread of a tightening bolt using an ultrasonic flaw detection test, the machining accuracy of the bolt head and shaft end face, the coating quality, etc. Depending on the severity, even if cracks actually exist, they often cannot be detected.

This invention was devised from this perspective,
To reliably detect internal cracks occurring in bolt shafts and threaded parts from the bolt head or shaft end face without loosening bolts in a tightened state and regardless of the machining accuracy of the detection surface and whether or not it is painted. The purpose of this invention is to provide a jig for bolt flaw detection using ultrasonic waves.

Now, an example of the implementation of the present invention will be explained in detail with reference to the drawings. The jig of the present invention has a head 3 of a bolt 2 fastened to an object 1 to be fixed, or a nut 5 screwed onto a threaded portion 4 of the bolt 2. In this embodiment, as shown in FIG. The case where the tool is attached will be explained. It has a fitting recess 7 that can be tightly fitted from the outside to the outer peripheral side of a nut 5 screwed into the threaded portion 4 of the bolt 2 tightening the object 1, and the outer end of the fitting recess 7 In order to allow the tip of the threaded portion 4 to pass through the center of the side plate 8 which is bent inward and connected to the fitting recess 7, a through hole having a diameter larger than the diameter of the threaded portion 4 is provided. 9, and a fixing socket 11 is formed by providing a packing 10 around the inner circumferential surface of the through hole 9, which tightly contacts the outer circumferential surface of the threaded portion 4 to prevent leakage of couplant 15, which will be described later. The fixing socket 11 is tightly fitted and fixed to the nut 5 by screwing a fixing screw 13 into a screw hole 12 drilled at an appropriate position.

Further, a cylindrical contact socket 14 is slidably fitted on the outer peripheral surface of the fixed socket 11, and a couplant such as glycerin is inserted between the inner peripheral surface of the contact socket 14 and the side plate 8 of the fixed socket 11. A contact plate 17 is fixedly mounted with a couplant injection interval 16 for injecting the couplant 15, and an injection port 18 for the couplant 15 is bored in the contact socket 14 above the couplant injection interval 16. , and couplant injection interval 16
The width of the contact socket 14 can be adjusted by moving the contact socket 14 left and right on the fixed socket 11 according to the diameter of the bolt 2, and an air vent hole is provided in the contact socket 14 below the couplant injection interval 16. 19 is bored and the air in the couplant injection interval 16 is removed by means of a screw 20 screwed thereto;
The couplant 15 is filled via the injection port 18 within the couplant injection interval 16 . Further, a point-focusing probe 21 is applied to the outer side of the contact plate 17 to transmit ultrasonic waves into the inside of the bolt 2 through the contact plate 17 and couplant 15, but in this case, as shown in FIG. The outer surface of the contact plate 17 is provided with an outer surface of the contact plate 17 so that the ultrasonic waves concentrate and hit the crack 22 in a directional manner.
Depending on the diameter of the bolt 2, a flaw detection guide groove 23 is provided which is inclined at a suitable angle θ so that ultrasonic waves can be incident from the center in the circumferential direction. Normally, within the range of the angle θ shown in FIG. 6 for the sound waves traveling inside the bolt 2 with respect to the center line of the bolt axis, the ability to detect cracks 22 increases as the angle increases, but conversely, the identification resolution decreases. do. As a result of experiments, the appropriate angle θ of the flaw detection guide groove 23, which provides the best detection ability and identification resolution, was in the range of 2 to 5 degrees, as shown in FIG. By providing the flaw detection guide groove 23 at an appropriate angle θ on the contact plate 17, the incident sound can always be accurately made to enter from the head 3 of the bolt 2 or the tip of the threaded portion 4 when inspecting the bolt 2. be.

As described above, the present invention includes a fitting recess 7 that can be fixed to either the head 3 of the bolt 2 or the nut 5 of the threaded part 4, and the fitting recess 7 inward at the outer end of the fitting recess 7. A side plate 8 formed by bending, a fixing socket 11 formed with a through hole 9 in the center of the side plate 8, and an ultrasonic wave incident on the outside in a circumferential direction from the center according to the diameter of the bolt 2. A contact plate 1 equipped with a flaw detection guide groove 23 inclined at an angle θ suitable for
7, and a couplant 1 of a predetermined width formed by the side plate 8 and the contact plate 17 on the fixed socket 11.
5, and a contact socket 14 that can be fitted into the contact socket 14. Therefore, it is possible to avoid loosening the bolt 2 which is in a tightened state, and to improve the machining accuracy of the flaw detection surface and the coating. Regardless of whether or not the crack 22 occurs in the threaded portion 4 and shaft portion 6 of the bolt 2, it is possible to reliably detect the crack 22.

[Brief explanation of the drawing]

The drawings show an example of the implementation of the present invention. Fig. 1 is a front view showing the state in which the fixed object is tightened with bolts and nuts, Fig. 2 is a longitudinal sectional view of the main part, and Fig. 3 is a contact FIG. 4 is a front view of the plate, FIG. 4 is a side view thereof, FIG. 5 is a vertical cross-sectional view showing the inspection state, and FIG. 6 is a table showing the resolution of screw threads and artificial flaws. In the figure, 2 is a bolt, 3 is a head, 4 is a screw part, 5
is a nut, 7 is a fitting recess, 8 is a side plate, 9 is a through hole,
11 is a fixed socket, 14 is a contact socket, 15
16 is a couplant injection interval, 17 is a contact plate, and 23 is a flaw detection guide groove.

Claims (1)

[Claims for Utility Model Registration] Head 3 of bolt 2 or nut 5 of threaded portion 4
A fitting recess 7, a side plate 8 bent inward at the outer end of the fitting recess 7, and a through hole 9 in the center of the side plate 8, which can be fixed to any of the fitting recesses 7. a contact plate 17 having a flaw detection guide groove 23 on the outside thereof inclined at an angle θ suitable for the incidence of ultrasonic waves from the center in the circumferential direction according to the diameter of the bolt 2; The fixed socket 11 has a couplant injection gap 16 for injection of a couplant 15 of a predetermined width, formed by the side plate 8 and the contact plate 17, and an ultrasonic contact socket 14 comprising a fittable contact socket 14. Treatment tool for bolt flaw detection.