JPS6239200A - Method of detecting abnormality of nozzle of high-pressure water jet cutter using abrasive material - 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] <Industrial Application Field> The present invention provides a method for detecting nozzle abnormality in a high-pressure water jet cutting machine using an abrasive material, and in particular, detects nozzle damage at an early stage to prevent major accidents. The present invention relates to a nozzle abnormality detection method.

<Prior Art> There is a method of using a high-pressure water jet for full bending and other processing, but in order to improve the efficiency of cutting and polishing the workpiece, there is a method of mixing an abrasive in the nozzle part. A nozzle of a high-pressure water jet cutting machine using such an abrasive material has conventionally had a structure as shown in FIG. This nozzle 1 consists of a substantially cylindrical tube having a water hole 1a in its center, through which a high-pressure water jet mixed with an abrasive material passes.

<Problems to be Solved by the Invention> However, in the conventional nozzle 1 as described above, severe wear occurs inside the nozzle 1 when high-pressure water and abrasive material pass through the water hole 1a.

In this case, if the nozzle 1 itself is normal, the inner diameter of the water passage hole 1a will gradually expand approximately evenly, so the nozzle is replaced after a certain life time. However, when uneven wear occurs in the water passage hole 1a of the nozzle 1, the inner diameter does not expand uniformly, but expands partially, resulting in partial destruction as shown in FIG. Then, the high-pressure water mixed with the abrasive material flows out from the broken portion 2, and the flow rate from the tip of the nozzle 1 decreases, resulting in a significant decrease in cutting ability.

Such a situation occurs suddenly, and it is difficult to predict nozzle destruction. Furthermore, it has been impossible for two people to constantly monitor the nozzle due to the presence of flying objects and the risk of the nozzle being destroyed.

The present invention has been made in view of these conventional problems, and its purpose is to monitor the condition of the nozzle, understand the state of wear, determine when it is time to replace the nozzle, and detect the very early stages of breakage or the like. The object of the present invention is to solve the above-mentioned conventional problems by providing a method that can detect an abnormality immediately before it occurs.

<Configuration of the Invention> In order to achieve the above object, the present invention configures a nozzle abnormality detection circuit by attaching a plurality of strain gauges to the outer circumferential surface of the nozzle of a high-pressure water jet cutting machine that uses an abrasive material, and detects the output of these strain gauges. The gist of this system is to detect nozzle abnormalities based on the following.

<Function> If high-pressure water mixed with abrasive is injected to Geno 1 while current is passed through the circuit for detecting nozzle abnormality, if the water passage hole of the nozzle is uniformly worn, a large strain will occur in the nozzle. does not occur. However, when a nozzle breaks due to uneven wear, bending stress is applied to the nozzle due to the force of the water jet ejected from the broken part, causing the nozzle to deform. This deformation is detected by strain gauges to detect nozzle abnormalities.

<Example> FIG. 1 is a sectional view showing a nozzle portion of a high-pressure water jet cutting machine using an abrasive material to which the nozzle abnormality detection method of the present invention is applied. This nozzle part is a high-pressure water generator (not shown)
The nozzle base 11 is coupled to the nozzle base 11 and receives high-pressure water supplied from the nozzle base 11, a nozzle holder 14' attached to the tip of the nozzle base 11, and a nozzle 19 held by the nozzle holder 14.

The nozzle base 11 has a threaded fastening hole 20 that connects to a hose or piping, and a high-pressure water passage 21 that extends in communication with the fastening hole 20. A filter 12 is arranged in the high-pressure water passage 21. It is set up. The nozzle base 11 and the nozzle holder 14 are fastened together by a mounting thread 22, and an orifice mount 13 for generating a high-pressure jet water stream is disposed at the joint between the two members. A water path 23 is formed inside the nozzle holder 14 and communicates with the high-pressure water passages 2 and 1 via the orifice mount 13, while an abrasive supply path 24 is branched to join the water passage 23.
is formed.

The nozzle holder 14 and the nozzle 19 are connected to each other by a nozzle adapter 16 fastened to the nozzle holder 14 by a mounting thread 25 .

That is, the base end of the nozzle 19 is inserted into the nozzle adapter 16, and the fitting member is firmly connected with the screw 17 of the compression nut 18, and the nozzle adapter 16 is further screwed onto the nozzle holder 14 to attach the nozzle 19. A tapered sleeve 15 is interposed between the base end of the nozzle 19 thus attached and the tip of the nozzle holder 14. The nozzle 19 has a longitudinally extending jet passage 26 in its center. The tapered sleeve 15 has a tapered hole 27 having a large diameter almost the same as the waterway 23 on the base end side and a small diameter almost the same as the jet passage 26 on the distal end side, which gradually widens from the tip to the rear end. are doing. Further, the nozzle 19 is made of a flexible material such as metal, and a plurality of strain gauges 30, 31 are attached to the outer peripheral surface of the body of the nozzle 19. In this embodiment, two strain gauges are attached and arranged with an angular interval of 0 (=90 degrees) from each other with respect to the central axis of the nozzle 19. Lead wires 32.33 extend from each strain gauge 30.31, and wire leads 32.33 extend from each strain gauge 30.31.
33 is connected to an amplifier not shown, and further a strain gauge 3
0.31, or connected to a comparator that compares the current value (or voltage value) between the strain gauges 3o and 31,
It constitutes an abnormality detection circuit for the nozzle 19.

With this configuration, high-pressure water is supplied from the high-pressure water jet cutting machine main body, and when this high-pressure water becomes a high-pressure water jet mixed with an abrasive and flows out from the tip of the nozzle 19,
The state of the nozzle is monitored by supplying current to the nozzle abnormality detection circuit. As time passes, the nozzle 19 is subjected to wear on the inner wall of the jet passage 26, and the diameter of the jet passage 26 gradually increases. When this expansion change is normal, no part of the nozzle 19 suffers uneven wear and no bending stress is applied to the nozzle 19 itself, so the values detected by the strain gauges 30 and 31 are the same. However, when uneven wear occurs in the jet passage 26 and wear progresses significantly in a portion of the nozzle 19, the nozzle 19 breaks at the portion where the wear has progressed to an extreme degree. As shown in FIG. 4, when a part of the jet water stream 34 is ejected from the broken part 19a of the nozzle, a reaction force by the jet stream acts on the nozzle 19 due to its momentum, and if an extreme force is applied, the nozzle In the same state as when bending stress is applied to the nozzle 19, the nozzle 19 bends, that is, bends and deforms. Due to this bending deformation, among the strain gauges attached to the nozzle 19, the strain gauge 31 has a compressive strain, and the strain gauge 31 has a compressive strain.
Tensile strain occurs at zero, and each strain is detected and amplified, and either displayed on an indicator meter or taken out as a comparator output. The operator can then learn of any abnormality in the nozzle 19 by reading a meter or lighting a warning lamp at a remote location.

<Effects of the Invention> As described above, according to the present invention, a plurality of strain gauges are attached to the outer surface of a nozzle, and abnormalities in the nozzle can be detected by reading or comparing the outputs of these strain gauges. Because I did it.

It is possible to detect failure of the nozzle at the same time as the destruction of the nozzle, and it is possible to improve the efficiency of machining work using a high-pressure water jet cutting machine.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of a jetting part of a high-pressure water jet cutting machine using a nozzle to which the present invention is applied, FIG. 2 is an external view showing a nozzle according to an embodiment of the present invention, and FIG. Fig. 2 is an enlarged view of the main parts of the nozzle shown in Fig. 2, Fig. 4 is a perspective view showing bending deformation when the nozzle shown in Fig. 2 is broken, and Fig. 5 schematically shows the structure of a conventional nozzle. FIG. 6 is a perspective view showing a state in which the nozzle shown in FIG. 5 is partially destroyed. 1.19... Nozzle, 11... Nozzle base, 14... Nozzle holder, 26... Jet passage, 30.31... Strain gauge, 32.33... Lead wire.

Claims (1)

[Claims] A nozzle abnormality detection circuit containing the strain gauges is constructed by attaching multiple strain gauges to the outer circumferential surface of the nozzle of a high-pressure water jet cutting machine that uses abrasive material, and the strain gauges are used to detect bending deformation of the nozzle due to nozzle breakage. A method for detecting abnormality in a nozzle of a high-pressure water jet cutting machine using an abrasive material, characterized in that an abnormality in a nozzle is detected.