JP2019084626A - Work-piece processing device and oxidized scale removal method - Google Patents

Abstract

To provide a work-piece processing device that can improve durability in a slurry pressure-feeding part and an oxidized scale removal method.SOLUTION: A work-piece processing device is provided with a slurry jetting part for jetting compressed air and slurry, a mixture of liquid and abrasive grain to a work-piece. The slurry jetting part is provided with a slurry pressure-feeding part for pressure-feeding the slurry. In the slurry pressure-feeding part, a rotating body is arranged in a casing 7. In a bottom part 3 of the casing 7 is provided a slurry introduction port part 4, and in a side wall part 5 consecutively arranged around the bottom part 3 of the casing 7 is provided a slurry derivation port part 6. The rotating body is provided with vane parts 9 that have a length in a radiation direction from a rotation center part of the rotating body and are convexly curved in a rotation direction.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a work processing apparatus and an oxidation scale removal method.

  Conventionally, after a long wire made of metal is repeatedly heated and drawn to the required diameter, it is used as it is as a bar or wire, or cut and molded into a bolt or nut. It is

  By the way, when the long wire for wire drawing is heat-treated, a hard oxide scale is produced on the surface of the long wire for wire drawing, but if this oxide scale is drawn while being attached to the surface, this wire drawing It is necessary to remove the oxide scale before the wire drawing process because the oxide surface which is dropped during the wire drawing process damages the surface of the material.

  Therefore, the applicant has proposed the oxide scale removing method disclosed in Japanese Patent Application No. 2017-210538.

  This oxidation scale removal method solves the problems of immersion in chemicals such as hydrochloric acid and dissolution removal, and methods of accelerating and projecting steel balls and breaking and removing oxide scales, etc. Can be removed.

Japanese Patent Application No. 2017-210538

  By the way, although the above-mentioned oxide scale removing method is carried out using a work processing apparatus (hereinafter referred to as a conventional apparatus) provided with a slurry injection part for injecting a slurry which is a mixture of liquid and abrasive grains, this conventional apparatus is in fact The removal of oxide scale was carried out using the above method, and the abrasive grain (stainless steel) used in this process has its specific gravity and cutting force compared to the abrasive grains (alumina, silicon carbide) used so far. It was found that the wear at each portion of the conventional apparatus was severe, particularly at the slurry pumping section 52 for pumping the slurry to the slurry jetting section.

  That is, as illustrated in FIGS. 12 and 13, the slurry pumping unit 52 is provided with the rotating body 58 in the casing 57, and the slurry introduction port 54 is provided in the bottom portion 53 of the casing 57, The slurry outlet port 56 is provided in the side wall 55 continuously provided around the bottom 53, and the rotor 58 is provided with a blade 59 having a length in the radial direction from the rotation center of the rotor 58. It is done. In addition, the blade | wing part 59 is the structure which coat | covered the synthetic resin to metal core material 59 '.

  Therefore, the slurry 30 introduced into the casing 57 from the slurry inlet 54 is radially induced from the rotation center of the rotating body 58 by the vanes 59, and is pumped out of the slurry outlet 56. (See FIG. 14), wear of the tip of the slurry extrusion surface 59a in the blade portion 59 is remarkable (see FIG. 15), so that the conventional device frequently requires replacement of the blade portion 59, resulting in high cost. There was a drawback. This is presumed to be because the collision pressure of the slurry 30 is concentrated because the slurry extrusion surface 59a of the blade portion 59 is a flat surface (linear surface).

  The present applicant focused on the above-mentioned problems and as a result of repeating various experiments and researches, developed an innovative work processing apparatus and an oxide scale removing method which are unprecedented.

  The subject matter of the present invention will be described with reference to the accompanying drawings.

  A work processing apparatus provided with a slurry injection unit 1 for injecting a slurry 30 which is a mixture of a liquid 30a and abrasive grains 30b together with compressed air onto a work W, the slurry for pumping the slurry 30 to the slurry injection unit 1 A pumping unit 2 is provided, and the slurry pumping unit 2 is provided with a rotating body 8 in a casing 7. A slurry inlet 4 is provided on the bottom 3 of the casing 7. The bottom of the casing 7 The slurry outlet port 6 is provided in the side wall 5 continuously provided around 3 and has a length in the radial direction from the rotation center of the rotating body 8 and is convex in the rotating direction. A curved blade portion 9 is provided, and the slurry 30 introduced into the casing 7 from the slurry inlet 4 is radially induced from the rotation center portion of the rotating body 8 by the blade portion 9, and the slurry 30 is Pumping from slurry outlet 6 The present invention relates to a work processing apparatus configured to be derived.

  Further, in the work processing apparatus according to the first aspect of the present invention, a plurality of the blade portions 9 are provided at predetermined intervals.

  Further, in the work processing apparatus according to any one of claims 1 and 2, the blade portion 9 has an arc shape in cross section whose width a becomes thicker as it goes outward from the rotation center portion of the rotating body 8. The present invention relates to a work processing apparatus characterized in that

  The work processing apparatus according to any one of claims 1 to 3, wherein the bottom portion 3 of the casing 7 has a downward slope toward the slurry introduction port portion 4. It is related.

  In the work processing apparatus according to claim 4, the gradient of the bottom portion 3 is 8 to 12 degrees.

  Further, in the work processing apparatus according to any one of claims 1 to 5, the slurry passage 21 formed between the rotating body 8 and the side wall 5 of the casing 7 is the slurry outlet port 6. The present invention relates to a work processing apparatus characterized in that the work processing apparatus is configured to be gradually wider toward the end.

A method for removing oxide scale produced on the surface of a workpiece W by using the workpiece processing apparatus according to any one of claims 1 to 6, wherein a fluid 30a and the following abrasives are applied to the surface of the workpiece W. The present invention relates to an oxide scale removing method characterized in that the slurry 30, which is a mixture with the particles 30b, is mixed with compressed air and jetted.
The abrasive grains 30b are made of stainless steel, the abrasive grains 30b have a Vickers hardness of 700 to 800 Hv, and 85% (by weight) of the abrasive grains 30b have a particle diameter of 90 μm to less than 200 μm.

  In the oxide scale removing method according to claim 7, the chromium content of the abrasive grains 30b is 30% (by weight) or more.

  In the oxide scale removing method according to any one of claims 7 and 8, the irregular scale particles shown in Fig. 10 are adopted as the abrasive grains 30b.

  In the oxide scale removing method according to any one of claims 7 to 9, according to the oxide scale removing method characterized in that an abrasive having an average particle diameter of about 150 μm is adopted as the abrasive 30b. is there.

  In the oxide scale removing method according to any one of claims 7 to 10, a wire for drawing having a Vickers hardness of 200 to 400 Hv is adopted as the work W. It is related.

  Since the present invention is configured as described above, the present invention can dramatically improve the durability in the slurry pressure-feeding section, and thus becomes an innovative work processing apparatus and oxide scale removing method which have not been achieved before.

It is use condition explanatory drawing of the workpiece processing apparatus which concerns on a present Example. It is explanatory drawing of the oxide scale removal method using the workpiece processing apparatus which concerns on a present Example. It is an explanatory sectional view of an important section concerning this example. It is a disassembled perspective view of the principal part concerning a present Example. It is explanatory drawing of the principal part which concerns on a present Example. It is operation | movement explanatory drawing of the principal part which concerns on a present Example. It is an explanatory sectional view of an important section concerning this example. It is a photograph which shows the abrasion state of the principal part which concerns on a present Example. It is a table | surface which shows the composition of the abrasive grain 30b used by the oxide scale removal method which concerns on a present Example. It is an enlarged photograph of abrasive grain 30b used by the oxide scale removal method concerning a present example. It is a table | surface which shows the comparison experimental result of the oxide scale removal method which concerns on a present Example, and the conventional method. It is an explanatory sectional view of an important section concerning a conventional example. It is a perspective view of the principal part concerning a prior art example. It is operation | movement explanatory drawing of the principal part which concerns on a present Example. It is a photograph which shows the abrasion state of the principal part which concerns on a present Example.

  The preferred embodiments of the present invention will be briefly described by showing the operation of the present invention based on the drawings.

  When the slurry 30 which is a mixture of the liquid 30 a and the abrasive grains 30 b is jetted onto the work W together with the compressed air, the slurry 30 is pressure-fed from the slurry pumping unit 2 to the slurry jetting unit 1.

  Specifically, the slurry 30 introduced into the casing 7 from the slurry inlet 4 in accordance with the rotation of the rotating body 8 is radially induced from the rotation center of the rotating body 8 by the vanes 9 to conduct the slurry The pressure is delivered from the outlet 6.

  By the way, the blade portion 9 provided on the rotating body 8 of the present invention has a shape having a length in the radial direction from the rotation center portion of the rotating body 8 and convexly curved in the rotational direction. Wear is reduced as much as possible.

  That is, unlike the conventional apparatus described above, the slurry extrusion surface 9a of the blade portion 9 of the present invention is not a flat surface (linear surface) but a convexly curved surface, but the slurry 30 intensively collides with a part. Because the slurry 30 escapes favorably and smoothly outward along the convex curve, the collision of the slurry 30 is not concentrated and dispersed, and the wear of the slurry extrusion surface 9a is reduced as much as possible. It is guessed.

  Specific embodiments of the present invention will be described based on the drawings.

  This embodiment is a work processing apparatus provided with a slurry injection unit 1 for injecting a slurry 30 which is a mixture of a liquid 30a and abrasive grains 30b together with compressed air onto a work W, and is made of metal as the work W described later It is used when implementing the method of removing the oxide scale S which arose on the surface by heat-processing the elongate material W for wire-drawing.

  Specifically, as illustrated in FIGS. 1 and 2, the workpiece processing apparatus includes a workpiece conveyance unit 11 that conveys the wire for drawing long W, and a wire for drawing long wire conveyed by the workpiece conveyance unit 11. The workpiece processing unit 12 performs wet blasting on W.

  As shown in FIG. 1, the work transfer unit 11 is configured by arranging a plurality of feed rollers 11a for placing the wire-drawing long material W in a bridged state in a box-like base 10 with a space between them. And a lead-out part disposed on the other side (downstream side) of the base 10 from an introduction part disposed on one side (upstream side) of the base 10 and a long wire W for wire drawing to be treated To be continuously transported.

  The long wire W for wire drawing conveyed by the work conveyance unit 11 is wet-blasted by the work processing unit 12 at the time of conveyance.

  Specifically, as shown in FIGS. 1 and 2, the workpiece processing unit 12 is disposed on the base 10 that allows the wire for drawing W to pass, and is disposed below the slurry jetting unit 1. The slurry storage unit 13 and a slurry transfer unit 14 for transferring the slurry 30 from the slurry storage unit 13 to the slurry injection unit 1 via the slurry pumping unit 2 described later, the slurry 30 injected from the slurry injection unit 1 Is sent to the slurry reservoir 13 for reuse.

  A plurality (six) of the slurry jet units 1 are provided in the base 10 and around the long wire W for wire drawing conveyed by the work conveyance unit 11 as illustrated in FIGS.

  The slurry transport unit 14 described above is connected to each slurry injection unit 1, and a compressed air transport unit 15 a provided in a separate circuit and extended from the compressed air supply unit 15 is connected to the slurry transport unit 14. The slurry 30 supplied from the above is accelerated by the compressed air supplied from the compressed air conveying unit 15a, and the slurry 30 is injected from the slurry injection unit 1 at a predetermined injection speed.

  In addition, as shown in FIG. 2, each slurry injection unit 1 is positioned at a predetermined distance in the conveyance direction of the long wire W for wire drawing (the axial deviation of the long wire W for wire drawing is equally spaced Position, and are provided at positions shifted at equal intervals (60 degree intervals) in the circumferential direction of the wire for drawing long wire W, and the circumferential direction of the wire for drawing long wire W is provided by six pieces. The slurry 30 is jetted over the entire surface.

  Therefore, the slurry 30 can be jetted to the long wire W for wire-drawing favorably without the slurries 30 jetted from the slurry jet units 1 colliding with each other.

  Further, in the present embodiment, two slurry injection units for injecting the slurry 30 over the entire circumferential direction of the wire for drawing long W by the six slurry jet units 1 are two in the conveying direction of the wire for drawing long W It is provided. Therefore, a total of 12 slurry jet units 1 are provided in the transport direction of the long wire W for wire drawing. In addition, the number of the slurry injection parts 1 is set suitably.

  Further, the present embodiment includes the slurry pumping unit 2 that pumps the slurry 30 to the slurry injection unit 1.

  The slurry pumping unit 2 is configured such that a rotating body 8 is provided in a casing 7 as illustrated in FIGS.

  Specifically, the casing 7 is configured by providing a hollow portion at the lower end portion of the cylindrical base 16 at the upper end portion of which the drive motor 17 is disposed, and the first case half integrally formed at the lower end of the base 16 It comprises a body 7 'and a second case half 7' 'which is fixed to the first case half 7' by polymerization.

  Further, a communication port 7a communicating with the inner space 16a of the base 16 is provided at the central portion of the top wall of the casing 7, and the drive motor penetrates the inner space 16a of the base 16 through the communication port 7a. The tips of the seventeen rotational drive shafts 17 a are disposed in the casing 7. A rotary body 8 is provided at the tip of the rotation drive shaft 17a.

  Further, a gap is provided between the inner space 16a of the base 16 and the circumferential surface of the rotary drive shaft 17a.

  The gap is an excess slurry passing portion 18 through which excess slurry 30 not drawn out from the slurry outlet 6 described later among the slurry 30 introduced into the casing 7 passes. An excess slurry discharge unit 19 is provided to discharge the excess slurry 30 that has passed through the passage unit 18.

  Further, in the present embodiment, a stainless steel cylindrical member 20 whose surface is plated with chromium is fitted around the rotation drive shaft 17a, and the inner surfaces of the excess slurry passing portion 18 and the casing 7 are synthetic resin. It is covered with a manufactured member (urethane).

  Therefore, the portions covered with the cylindrical body 20 and the synthetic resin member are protected so that the abrasive grains 30b do not come in contact with each other, and abrasion is prevented.

  A slurry inlet 4 is provided at the bottom 3 of the casing 7, and a slurry outlet 6 is provided at the side wall 5 continuously provided around the bottom 3.

  The bottom 3 of the casing 7 has a downward slope toward the slurry inlet 4.

  Therefore, when the flow of the slurry 30 is stopped by stopping the drive motor 17, the abrasive particles 30b in the slurry 30 try to deposit on the bottom portion 3. However, since the bottom portion 3 has a slope, the abrasive particles 30b flow Deposition reduces the deposition.

  In this embodiment, the slope of the bottom 3 is set to about 10 degrees (see FIG. 7).

  This is because abrasive grains 30b are less likely to be deposited as the slope of the bottom portion 3 becomes steeper, but if the slope is steeper, the slurry 30 introduced from the slurry inlet 4 will collide vigorously, resulting in severe wear. Become.

  Therefore, when the present inventors tried various angles, it is about 10 degrees (range of 8 to 12 degrees) as an angle at which the bottom 3 is hard to be worn while suppressing the deposition of the abrasive grains 30 b on the bottom 3. I found it to be suitable.

  Further, in the present embodiment, the slurry passage 21 formed between the rotor 8 and the blades 9 and the casing 7 (the bottom 3, the side wall 5 and the top) described later is directed to the slurry outlet 6 It is configured to become wider gradually (see FIG. 5).

  That is, the rotation center of the rotor 8 and the opening axis of the slurry introduction opening 4 coincide with each other, and the distance from the rotation center of the rotation body 8 and the opening axis of the slurry introduction opening 4 to the side wall 5 of the casing 7 is As it goes to the slurry outlet 6, it is configured to be longer.

  This is to reduce as much as possible the wear in the vicinity of the slurry outlet 6 where the speed of the slurry 30 induced by the rotation of the rotating body 8 is the highest and the wear is apt.

  In fact, when the comparative test on the durability of the present embodiment and the conventional device was conducted, the casing 57 (the first case half 57 'integrally formed on the lower end of the base 60 in the conventional device is polymerized and fixed) While it takes 3000 hours to replace the case half 57 "), it takes 5000 hours to replace the casing 7 (second case half 7") in this embodiment. The time and leap has been extended dramatically.

  Further, in the casing 7, a rotating body 8 provided at the tip of the rotation drive shaft 17a is disposed.

  The rotating body 8 is a disk-shaped body, and on the surface of the rotating body 8 is provided a blade portion 9 having a length in the radial direction from the rotation center of the rotating body 8 and convexly curved in the rotational direction. There is.

  The rotation of the rotating body 8 causes the slurry 30 of the slurry reservoir 13 to be drawn in and introduced from the slurry inlet 4, and the slurry 30 introduced into the casing 7 from the slurry inlet 4 is made by the blade 9. It is induced in the radial direction from the rotation center of the rotating body 8 and is pumped out of the slurry outlet 6.

  Further, the blade portion 9 has a structure in which a metal core material 9 ′ provided detachably at the lower end portion of the rotation drive shaft 17a is covered with a synthetic resin (blade member 9 ′ ′), and in the present embodiment A plurality (six) are provided at predetermined intervals (equal intervals) in the direction.

  Further, the wing portion 9 has a cross-sectional arc shape in which the width a becomes thicker as it goes outward from the rotation center portion of the rotating body 8, and the lower surface (tip surface in the height direction) has a shape along the bottom 3 (parallel ) (See FIG. 3).

  Therefore, the slurry pressing surface 9a of the blade portion 9 is a convex curved surface.

  The convex curved surface (the slurry pressing surface 9a) preferably has a radius of 50 mm to 60 mm, and is set to 54.5 mm in this embodiment.

  Since the present embodiment is configured as described above, when the slurry 30 which is a mixture of the liquid 30a and the abrasive particles 30b is sprayed onto the work W together with the compressed air, the slurry 30 is pumped from the slurry pumping unit 2 to the slurry jetting unit 1 Be done.

  Specifically, the slurry 30 introduced into the casing 7 from the slurry inlet 4 in accordance with the rotation of the rotating body 8 is radially induced from the rotation center of the rotating body 8 by the vanes 9 to conduct the slurry The pressure is fed out from the outlet 6 (see FIG. 6).

  The blade portion 9 provided on the rotating body 8 of the present embodiment has a shape having a length in the radial direction from the rotation center portion of the rotating body 8 and convexly curved in the rotational direction. Wear is reduced as much as possible.

  In fact, when the comparative test on the durability of the present embodiment and the conventional device is conducted, the time until the replacement of the blade portion 59 in the conventional device is required is 700 hours, while the blade portion in the present embodiment is The time to need to replace 9 increased dramatically with 2000 hours.

  Therefore, according to the present embodiment, the durability of the slurry pumping unit 2 can be dramatically improved.

  Further, in the present embodiment, since the plurality of blade portions 9 are provided at predetermined intervals, the slurry 30 can be reliably guided.

  Further, in the present embodiment, since the blade portion 9 has a circular arc shape in which the width a becomes thicker as going outward from the rotation center portion of the rotating body 8, the above-described effects can be reliably achieved. .

  Further, in the present embodiment, since the bottom 3 of the casing 7 has a downward slope toward the slurry inlet 4, the wear of the bottom 3 can be reduced while suppressing the deposition of the abrasive particles 30 b.

  Further, in the present embodiment, since the slope of the bottom portion 3 is 8 to 12 degrees, the above-described effects can be reliably achieved.

  Further, in the present embodiment, the slurry passage 21 formed between the rotating body 8 and the side wall 5 of the casing 7 is configured to be gradually wider toward the slurry outlet 6. Also in this point, the collision of the slurry 30 is not concentrated and dispersed, and the durability of the slurry pumping unit 2 can be improved.

  Moreover, the workpiece processing apparatus which concerns on a present Example is used when implementing the method of removing the oxide scale S which arose on the surface by heat-processing the metal long wire W for wiredrawings.

  Specifically, the slurry 30, which is a mixture of the liquid 30a and the abrasive grains 30b, is mixed with compressed air and sprayed onto the surface of the long wire W for drawing.

  As the abrasive grains 30b, stainless steel irregular-shaped particles (see FIG. 10) having the composition shown in FIG. 9 are employed.

  Using the workpiece processing apparatus having the above configuration, the surface treatment was carried out on a long wire W for wire drawing (Vickers hardness 200 to 400 Hv) under the following conditions.

Abrasive grains: Stainless steel grid / Vickers hardness 700 to 800 Hv / average particle size
150 μm (85% (weight) particle diameter is 90 μm or more and less than 200 μm)
Air pressure ・ ・ ・ 0.4MPa
Processing speed (conveyance speed of long wire W for wire drawing) ... 30 m / min

  The average particle diameter of the abrasive particles 30 referred to in the present specification is defined by the mode diameter (the particle diameter with the highest frequency of appearance in the distribution), and the numerical value thereof using a measurement method of irradiating the particles with laser light and measuring. You are getting

  When treated under the above conditions, the oxide scale S formed on the surface of the wire for drawing W was well removed, and the abrasive grains 30 themselves were not broken.

  Moreover, the result of the comparative experiment of the processing method (shot blast) currently performed from the present Example and the prior art is as FIG.

  The roughness (arithmetic mean roughness and roughness pitch) of the surface of the wire for drawing W after processing is smaller in this embodiment than in the prior art.

  Therefore, in the present embodiment, not only oxide scale S is removed from the surface of the long wire W for drawing but also fine irregularities are formed on the surface of the long wire W for drawing, Lubricant during wire drawing can be well retained.

  Moreover, the surface hardness after a process is low compared with the conventional method in a present Example.

  This is because, in the conventional method, the surface to be drawn is treated with an abrasive having a large average particle diameter (a steel ball having an average particle diameter of 0.3 to 1 mm) so as to strike the treated surface. On the other hand, in the present embodiment, the surface of the long wire W for wire drawing is treated because it is treated so as to scrape the treated surface with abrasive grains having a smaller average particle diameter than the conventional method. It is reduced as much as possible.

  Therefore, according to the present embodiment, it can be said that it is effective as a processing method of the long wire W for wire drawing (hardening of the surface of the long wire W for wire drawing is not good for wire drawing). .

  In addition, the abrasive particles 30 of this example are extremely resistant to rusting because the content of chromium which is a passive film to prevent rusting is 30% (by weight) or more, and in this respect as well, the abrasive used in wet blasting treatment Useful as grain 30.

  The present invention is not limited to this embodiment, and the specific configuration of each component can be designed as appropriate.

W work 1 slurry injection part 2 slurry pumping part 3 bottom part 4 slurry introduction port part 5 side wall part 6 slurry outlet port part 7 casing 8 rotor 9 blade part
21 Slurry passage
30 Slurry
30a liquid
30b abrasive grain

Claims (11)

  A work processing apparatus provided with a slurry injection unit for injecting a slurry, which is a mixture of liquid and abrasive grains, together with compressed air on a work, wherein the slurry injection unit is provided with a slurry pumping unit for pressure-feeding the slurry The slurry pumping unit is provided with a rotating body inside a casing, and a slurry inlet is provided at the bottom of the casing, and a slurry outlet is provided at a side wall continuously provided around the bottom of the casing. And a blade portion having a length in the radial direction from the rotation center of the rotating body and being convexly curved in the rotational direction is provided on the rotating body, and is introduced into the casing from the slurry introduction port portion. The work piece is characterized in that the slurry is radially guided from the rotation center of the rotating body by the blade part and is pressure-feed-out from the slurry outlet part. Apparatus.   The workpiece processing apparatus according to claim 1, wherein a plurality of the blade portions are provided via a predetermined interval.   The workpiece processing apparatus according to any one of claims 1 and 2, wherein the blade portion has an arc shape in cross section whose width becomes thicker as it goes outward from the rotation center portion of the rotating body. Work processing device.   The workpiece processing apparatus according to any one of claims 1 to 3, wherein the bottom of the casing has a downward slope toward the slurry inlet.   5. The work processing apparatus according to claim 4, wherein the slope of the bottom portion is 8 to 12 degrees.   The workpiece processing apparatus according to any one of claims 1 to 5, wherein the slurry passage formed between the rotating body and the side wall of the casing gradually widens toward the slurry outlet. A work processing apparatus characterized in that it is configured as follows. A method for removing oxide scale produced on the surface of a workpiece W using the workpiece processing apparatus according to any one of claims 1 to 6, wherein a mixture of a liquid and the following abrasive grains is provided on the surface of the workpiece A method of removing oxide scale, comprising mixing and injecting the slurry of the present invention with compressed air.
The abrasive grains are made of stainless steel, the abrasive grains have a Vickers hardness of 700 to 800 Hv, and 85% (by weight) of the abrasive grains have a particle diameter of 90 μm to less than 200 μm.   The oxide scale removing method according to claim 7, wherein the chromium content of the abrasive grains is 30% (by weight) or more.   The oxide scale removing method according to any one of claims 7 and 8, wherein amorphous particles shown in Fig. 10 are adopted as the abrasive grains.   The oxide scale removing method according to any one of claims 7 to 9, wherein an abrasive having an average particle diameter of about 150 m is employed as the abrasive.   The oxide scale removing method according to any one of claims 7 to 10, wherein a long wire for drawing having a Vickers hardness of 200 to 400 Hv is adopted as the work.