JP7360692B2 - Metal sampling equipment and how to use it - Google Patents

Description

The present invention relates to a spherical cutting grindstone used to collect samples for inspecting cracks, fracture surfaces, etc. of metal welded parts such as steel plates and steel materials, a metal sample collection device using the same, and a method for using the same. .

During open inspections of metal structures such as tanks and bridges during construction or use, it is essential to inspect welded parts of steel plates and steel materials. Even if the welding at the time of construction is adequate, the welded parts are particularly susceptible to stress due to changes in load and climate during service, resulting in problems such as ductile fracture, brittle fracture, fatigue fracture, and stress corrosion cracking. Easy to occur.

For this purpose, various inspection methods are known, one of which is the replica method, also known as the Sumpp method. In this method, the surface to be inspected is mirror-finished and etched on-site, a resin replica of the metal surface structure is taken, and the replica is inspected using a microscope or the like in an inspection laboratory. Although this method can be applied to flat surfaces, it is impossible to sample the fracture surface of the fractured part, and since the replica is only a copy, it is inevitably less accurate than the actual surface structure.
In addition, if you try to sample the necessary part with a flat cutting wheel to see the inside of the welded part, it will leave large scratches on the steel plate or steel material after sample collection, and when repairing the surface grinding scratches after sample collection. Repairing by overlaying by welding requires a large amount of time and is not practical.

Additionally, there is a known tool for making a hole in the trepanning process described in Patent Document 1 to obtain a cylindrical sample at the center, but this leaves a hole that is quite large compared to the size of the resulting sample. .

Publication Practical Publication No. 2-107414

In view of the above-mentioned prior art, the present invention provides a metal sample collecting device for collecting a metal sample while leaving as few scars as possible on the surface of an object to be inspected, and a method for using the same.

The present invention provides a spherical cutting wheel for metal sampling. The present invention further includes a broken sphere cutting wheel and a shaft disposed to extend from the center of the broken sphere cutting wheel in a direction perpendicular to the tangential direction and toward the center of curvature of the broken sphere cutting wheel. Provided is a metal sampling device comprising:

Further, the present invention provides a metal sample collecting device, which includes a rotation drive unit that is detachably fixed to the broken sphere cutting grindstone and rotates the broken sphere cutting grindstone.

The present invention provides a broken-spherical cutting wheel, a shaft arranged to extend from the center of the broken-spherical cutting wheel in a direction perpendicular to the tangential direction and toward the center of curvature of the broken-spherical cutting wheel; A method of using a metal sampling device comprising a rotation drive unit for rotating a broken spherical cutting grindstone and a fulcrum member including a fulcrum, the method comprising: fixing the fulcrum member at a first position on a metal surface; a first grinding step of grinding a metal surface, which is a member to be ground, by rotating the broken spherical cutting whetstone by the rotary drive unit while pressing the tip of the shaft; and a second grinding step at a predetermined second position different from the first position. A step of fixing a fulcrum member in a position, and performing the same or the same procedure as the first grinding step using the fulcrum of the fulcrum member in a second position to grind one surface of the member to be ground. and a second grinding step of obtaining a sample having a shape consisting of two partially spherical surfaces.

1 is a perspective view showing an embodiment of a metal sample collecting device according to the present invention. FIG. 2 is a schematic diagram showing the principle of sample collection operation of the metal sample collection device according to the present invention. FIG. 2 is a schematic view showing the dimensions of each part of the metal sample collecting device according to the present invention and the dimensions of the sample to be collected as seen from each direction.

An embodiment of a metal sampling device 1 of the present invention is shown in FIG. In this embodiment, the metal sample collecting device 1 includes a cutting whetstone 2 having a broken sphere shape and a shaft 3 fixed to a rotating shaft (not shown) of a rotation drive unit 10 that rotates the cutting whetstone 2. . A missing ball is a shape in which a part of a ball (a hollow sphere) is cut out with a flat surface. Generally, a shape obtained by cutting a sphere with a flat surface is called a "missing sphere", but the round cutting grindstone 2 of the present invention is a rotating body having a shape of a flat plate bent roughly along the spherical surface, and is rotationally symmetrical. It has become. In other words, the broken sphere shape as used in the present invention means that the part of the cutting wheel used for cutting only needs to have a broken sphere shape with a certain radius of curvature R, and the other parts have a circular plane or a shape with a certain curvature radius. There are shapes such as a spherical surface with a larger radius and a two-step circular plane with a step (offset). The center of the cutting wheel will also require an optional joint, such as a hole for connection to the rotary drive described below. In other words, the broken-spherical cutting wheel refers to a cutting wheel with a broken-spherical shape in which the portion used for cutting has a constant radius of curvature R.

A cutting wheel generally consists of abrasive grains and a binder (glass cloth or the like may be used for reinforcement), and is manufactured by firing. During use, the abrasive grains wear out and create new cutting edges, and when they become dull, they fall off, creating a self-growth effect in which new abrasive grains appear. Therefore, the diameter of the cutting wheel gradually becomes smaller as it is used. If the diameter is too small, the rotary drive unit 10 such as a grinder will interfere with the work surface, work efficiency will drop, and usability will deteriorate, so a range of diameters (outer diameters) suitable for use is naturally determined. It is sufficient that the cutting wheel has the shape of a part of a sphere within that range. In other words, the joint portion of the cutting whetstone with the rotation drive unit 10 may be a flat surface, or may have a shape in which the joint portion is offset as in a general cutting whetstone, if necessary. There is a hole at the center of rotation of this cutting whetstone 2, so that it can be connected to the rotation shaft of the rotation drive unit 10. As the binder, feldspar, soluble clay, Bakelite, etc. can be used. If it is feldspar or soluble clay, it is baked at a high temperature of 1,300 degrees Celsius after it is completely dried, and if it is Bakelite, it is hardened at about 200 degrees Celsius. Further, the blade thickness is about 0.3 mm to 7 mm, although it depends on the diameter of the cutting wheel and the binder. The diameter is not particularly limited, but is preferably about 100 mm. The thickness, diameter, and material of the cutting wheel are selected in consideration of the thickness, hardness, and material of the workpiece to be ground.

The shaft 3 used in the present invention is a rigid metal or synthetic resin rod. It may be a straight round bar with a sharp tip, but there are no particular restrictions on its shape or material as long as its tip can be fixed to a suitable fulcrum 5 as described below. There is no particular limitation on the method of joining this shaft 3 and the fulcrum 5, which will be described below. The shaft 3 can be made into a two- or three-stage shape with a thicker base and a thinner tip, or it can be made by combining existing screws, steel rods, nuts, etc. This shaft 3 may be detachably coupled to the rotation shaft of the rotation drive unit 10 at the joint between the rotation drive unit 10 and the cutting whetstone 2, or the shaft 3 may be attached to the center of the spherical cutting whetstone 2. It may be fixed in a direction perpendicular to the tangential direction of the grindstone, or it may be removably coupled to the above-described rotary drive unit 10 at the joint with the cutting grindstone 2. The length of the shaft 3 (the length from the position in contact with the cutting wheel 2 to the tip of the shaft 3) is determined in accordance with the radius of curvature R of the broken sphere shape of the cutting wheel 2. In other words, the length of the shaft 3 will be the inner radius of curvature R if the cutting whetstone 2 is entirely in the shape of a broken ball, but it depends on the shape of the joint of the cutting whetstone 2 with the rotary drive unit 10. The length may vary slightly. The length of the shaft 3 is determined so that the tip of the shaft 3 is located at the center of curvature of the spherical cutting grindstone 2.

As the rotary drive unit 10 for the spherical cutting grindstone 2, easily portable devices commonly sold as baby grinders, angle grinders, hand grinders, etc. can be used. As a driving method, electricity (including battery driving), compressed air, etc. are used. As the rotation drive unit 10, a device with a rotation speed suitable for the work of grinding a metal surface and collecting a sample is selected.

Note that the metal members to be ground are not particularly limited, and include general steel plates, H-shaped steel, steel pipes, steel structural members, cast iron members, aluminum alloy and stainless steel alloy plates and pipes, structural members, etc. .

FIGS. 2(A) and 2(B) show schematic diagrams for explaining the principle of the present invention. In FIG. 2, the broken sphere-shaped cutting grindstone 2 is represented by a line, but it actually has a certain degree of thickness. It may be considered that the radius of curvature R and the like shown below are based on the inner surface of the spherical cutting grindstone 2. A fulcrum member 4 for fixing the tip of the shaft 3 is shown. This is for pressing the tip of the shaft 3 against a fulcrum 5 on this fulcrum member 4 to keep the tip of the shaft 3 in a fixed position during rotation of the shaft 3. The fulcrum member 4 may be made of any material such as metal or synthetic resin as long as it has a certain degree of hardness, and its size is not particularly limited. Further, the fulcrum 5 itself may be made of a shallow drill hole or a depression made by hitting with a punch depending on the material, as long as it can be fixed by pressing the tip of the shaft 3. In other words, the fulcrum 5 may be anything that can rotate the tip of the shaft 3 and provide a catch to the extent that it does not move easily. Further, a plurality of fulcrums 5 of different heights can be made on one fulcrum member 4 to provide versatility. This support member 4 can be fixed to the metal surface 6 of the subject by any method, such as by a fixing tool commonly sold as a "magnetic holder stand" or "magnetic block", or by using an adhesive.

Moreover, such a fulcrum member 4 is only an example, and many other aspects are also conceivable. In short, it is only necessary to hold the tip of the shaft 3 in a certain position when grinding the metal surface of the member to be ground, and one possible means for this is to use a universal joint. Note that by adjusting the angle of the joint of such a universal joint, it is also possible to grind the corner of the metal structure of the member to be ground with the spherical cutting wheel 2 and collect a sample.

FIG. 2A shows a schematic side view of the embodiment of the present invention before grinding begins. A state in which the fulcrum member 4 is fixed at a first position on the metal surface 6, the tip of the shaft 3 is pressed against the fulcrum 5 of the fulcrum member 4, and the cutting whetstone 2 is placed on the metal surface 6 is shown. Although the rotation drive unit 10 is required, it is not necessary for explaining the principle and will therefore be omitted here. Holding the rotary drive unit 10 in your hand, press the cutting wheel 2 against the metal surface 6 while pressing the tip of the shaft 3 against the fulcrum 5. That is, grinding is performed with the center of the spherical shape of the cutting whetstone 2 placed on the fulcrum 5.

Figure 2(B) shows how the cutting progressed. It can be seen that the cutting wheel 2 cuts into the metal. Next, the fulcrum member 4 is fixed at a predetermined second position different from the first position, the fulcrum 5 of the fulcrum member 4 is brought to the right, and the orientation of the cutting wheel 2 and the shaft 3 is reversed. Make a notch opposite to the notch. As a result, it is possible to collect a sample from the metal surface that has a boat shape, or rather a shape that is formed by combining one surface (flat or curved surface) of the workpiece to be cut and two partial spherical surfaces obtained by cutting.

Figures 3(A) and 3(B) show how the size of the resulting sample is determined. FIG. 3(A) shows the dimensions of each part in this embodiment. The size of the sample that can be collected is determined from the height h of the fulcrum 5, the inner radius of curvature R and the plane diameter D of the cutting wheel 2, and the grinding depth ds.

Assuming that the dimensions of the broken spherical cutting grindstone 2 are that the outer diameter D is 100 mm and the radius of curvature R is 82 mm, the depth d of the curved surface is 17 mm. When the maximum grinding depth ds is set to 5 mm, 10 mm, 15 mm, and 20 mm, respectively, the height h of the fulcrum 5 and the width w and length L of the obtained sample are as shown in Table 1 below. As shown in Table 1, by changing the height h of the fulcrum 5, the size (width w, length L, depth ds) of the obtained sample can be changed.

At the site, grinding can be started by determining in advance the left and right positions in which the fulcrum member 4 is to be placed and the direction in which the cut will be made, and by drawing a diagram showing these on the metal surface 6. First, by making a notch on either the right or left side, and then making a notch on the opposite side, it is possible to obtain a metal sample with a boat shape or a shape that usually consists of one flat surface (or curved surface in some cases) and two half-spherical surfaces made by grinding. I can do it. In the case of inspecting a welded part, it is generally possible to inspect for cracks in the weld by taking a sample of a size that can be cut out, such as a cube of about 10 mm. After the inspection is completed, the area where the sample was taken is usually repaired by welding or the like.

By using the metal sample collecting device and its device of the present invention, metal samples can be collected not only from smooth surfaces but also from parts welded at an angle. An example of a part that is welded at this angle is the weld between the bottom plate and side plate of a cylindrical tank. For example, the fulcrum members 4 are fixed at a predetermined angle to the surface of the metal side plate or the metal bottom plate of a cylindrical tank using a universal joint, and the spherical cutting grindstone is inserted from the position of each fulcrum member 4. By grinding the metal surface in step 2, it is also possible to collect a sample from the welded area (commonly known as the area around the top plate) between the bottom plate and the side plate.

As explained above, according to the above-described embodiments of the present invention, a sample can be obtained without extensive use of grinding or drilling and without leaving large scratches on the metal of the object. As a result, not only the work of sample collection becomes easier and more efficient, but also the repair work after collection becomes easier. It is also possible to reduce the vulnerability caused by scars caused by sample collection. In addition, the sample can be taken back to the inspection laboratory and necessary inspections can be carried out without stress, improving inspection efficiency.

1 Metal sampling device
2 Spherical cutting grindstone
3 Axis 4 Fulcrum member 5 Fulcrum 6 Metal surface 10 Rotation drive unit

Claims (4)

A broken-spherical cutting wheel whose portion used for cutting has a constant radius of curvature , and a part arranged to extend from the center of the broken-spherical cutting wheel in a direction perpendicular to the tangential direction and toward the center of curvature of the broken-spherical cutting wheel. A metal sampling device comprising: a shaft whose tip is pressed against a fulcrum; 2. The metal sample collecting device according to claim 1, further comprising a rotation drive unit that is removably fixed to the broken sphere cutting grindstone on the opposite side of the shaft with the broken sphere cutting grindstone in between, and rotates the broken sphere cutting grindstone. The metal sample collecting device according to claim 1, further comprising a fulcrum member that can be fixed to a metal surface of a subject and has a fulcrum against which the tip of the shaft is pressed . a broken-spherical cutting wheel; a shaft disposed to extend from the center of the broken-spherical cutting wheel in a direction perpendicular to the tangential direction and toward the center of curvature of the broken-spherical cutting wheel; A method of using a metal sampling device comprising a rotation drive unit that rotates a rotation drive unit, and a fulcrum member including a fulcrum, the method comprising: fixing the fulcrum member at a first position on a metal surface that is a member to be ground; a first grinding step of grinding a metal surface, which is a member to be ground, by rotating the broken-spherical cutting wheel by the rotary drive unit while pressing the tip of the shaft against the grinding wheel; A step of fixing a fulcrum member at the second position, and a procedure similar to the first grinding step using the fulcrum of the fulcrum member at the second position, and grinding one surface of the member to be ground. a second grinding step of obtaining a sample having a shape consisting of two partially spherical surfaces.

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