WORKPIECE PROCESSING APPARATUS AND OXIDE SCALE REMOVAL METHOD

Abstract

 An object of the present invention is to provide an original and innovative workpiece processing apparatus and oxidation scale removal method. The present invention provides a workpiece processing apparatus provided with slurry jetting parts (1) for jetting a slurry (30), which is a mixture of a liquid (30a) and abrasive grains (30b), together with compressed air to a workpiece (W), the workpiece processing apparatus being provided with a slurry pressure-feeding part (2) for pressure-feeding the slurry (30) to the slurry jetting parts (1), a rotating body (8) being provided inside a casing (7) in the slurry pressure-feeding part (2), a slurry inlet part (4) being provided in a bottom section (3) of the casing (7), a slurry outlet part (6) being provided in a side wall section (5) provided so as to be continuous with a periphery of the bottom section (3) of the casing (7), and the rotating body (8) being provided with a blade part (9) which has a length in a radial direction from a rotational center of the rotating body (8) and which curves convexly in a rotation direction.

Description

TECHNICAL FIELD

[0001] The present invention relates to a workpiece processing apparatus and to a method for removing oxidation scale.

BACKGROUND ART

[0002] Conventionally, a metal-made long material for wire drawing is subjected to repeated heat treatment and wire drawing and drawn to the necessary diameter, and then utilized without modification as rod stock or wire rod, or cut and formed into bolts, nuts, and the like.

[0003] When the long material for wire drawing is heat treated, a hard oxidation scale forms on a surface of the long material for wire drawing, but when wire drawing is performed with this oxidation scale adhering to the surface, the material surface is damaged by oxidation scale that falls off during the wire drawing process. There is therefore a need to remove the oxidation scale prior to wire drawing.

[0004] The present applicant has proposed the oxidation scale removal method disclosed in Japanese Patent Application No. 2017-210538.

[0005] This oxidation scale removal method overcomes the problems of methods in which a material is dipped in hydrochloric acid or another chemical to remove oxidation scale by dissolution, methods in which oxidation scale is removed by accelerating and projecting steel balls to the material to break the oxidation scale into pieces, and other methods, and can satisfactorily remove oxidation scale.

[Prior Art Documents]

[Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application No. 2017-510538

DISCLOSURE OF THE INVENTION

Problems to Be Solved by the Invention

[0007] The oxidation scale removal methods described above are performed using a workpiece processing apparatus (referred to below as the conventional apparatus) provided with a slurry jetting part for jetting a slurry which is a mixture of a liquid and abrasive grains, but when oxidation scale removal was actually performed using this conventional apparatus, it was determined that because of the high specific gravity and cutting force of the abrasive grains (stainless steel) used in the removal process relative to abrasive grains (alumina, silicon carbide) heretofore used, abrasion was severe in parts of the conventional apparatus, and abrasion was particularly severe in the slurry pressure-feeding part (52) for pressure-feeding the slurry to the slurry jetting part.

[0008] In other words, in this slurry pressure-feeding part (52), a rotating body (58) is provided inside a casing (57), a slurry inlet part (54) is provided in a bottom section (53) of the casing (57), a slurry outlet part (56) is provided in a side wall section (55) provided so as to be continuous with a periphery of the bottom section (53), and the rotating body (58) is provided with blade parts (59) which have a length in a radial direction from a rotational center of the rotating body (58), as illustrated in FIGS. 12 and 13. The blade parts (59) are structures in which a metal-made core material (59') is coated with a synthetic resin.

[0009] Therefore, a slurry (30) introduced into the casing (57) from the slurry inlet part (54) is guided by the blade parts (59) in the radial direction from the rotational center of the rotating body (58) and forced out from the slurry outlet part (56) (see FIG. 14), but due to severe abrasion of distal-end parts of slurry extrusion surfaces (59a) of the blade parts (59) (see FIG. 15), the problem arises in the conventional apparatus that the blade parts (59) require frequent replacement, and cost is increased. The reason for this is thought to be that collision pressure of the slurry (30) is concentrated due to the flat (linear) shape of the slurry extrusion surfaces (59a) of the blade parts (59).

[0010] In view of the problems described above, and as a result of various experiments/research, the present applicant developed an original and innovative workpiece processing apparatus and oxidation scale removal method.

Means for Solving the Problems

[0011] The gist of the present invention is described below with reference to the attached drawings.

[0012] A first aspect of the present invention pertains to a workpiece processing apparatus provided with slurry jetting parts (1) for jetting a slurry (30) together with compressed air to a workpiece (W), the slurry (30) being a mixture of a liquid (30a) and abrasive grains (30b), the workpiece processing apparatus characterized in that a slurry pressure-feeding part (2) is provided for pressure-feeding the slurry (30) to the slurry jetting parts (1), and the slurry pressure-feeding part (2) is configured so that a rotating body (8) is provided inside a casing (7), a slurry inlet part (4) is provided in a bottom section (3) of the casing (7), a slurry outlet part (6) is provided in a side wall section (5) provided so as to be continuous with a periphery of the bottom section (3) of the casing (7), the rotating body (8) is provided with a blade part (9) which has a length in a radial direction from a rotational center of the rotating body (8) and which curves convexly in a rotation direction, and the slurry (30) introduced into the casing (7) from the slurry inlet part (4) is guided by the blade part (9) in the radial direction from the rotational center of the rotating body (8) and forced out from the slurry outlet part (6).

[0013] A second aspect of the present invention pertains to the workpiece processing apparatus according to the first aspect, characterized in that a plurality of the blade part (9) are provided at predetermined intervals.

[0014] A third aspect of the present invention pertains to the workpiece processing apparatus according to the first aspect, characterized in that the blade part (9) has an arcuate cross-sectional shape which increases in width (a) progressively outward from the rotational center of the rotating body (8).

[0015] A fourth aspect of the present invention pertains to the workpiece processing apparatus according to the second aspect, characterized in that the blade parts (9) have an arcuate cross-sectional shape which increases in width (a) progressively outward from the rotational center of the rotating body (8).

[0016] A fifth aspect of the present invention pertains to the workpiece processing apparatus according to the first aspect, characterized in that the bottom section (3) of the casing (7) is sloped so as to incline downward toward the slurry inlet part (4).

[0017] A sixth aspect of the present invention pertains to the workpiece processing apparatus according to the second aspect, characterized in that the bottom section (3) of the casing (7) is sloped so as to incline downward toward the slurry inlet part (4).

[0018] A seventh aspect of the present invention pertains to the workpiece processing apparatus according to the third aspect, characterized in that the bottom section (3) of the casing (7) is sloped so as to incline downward toward the slurry inlet part (4).

[0019] An eighth aspect of the present invention pertains to the workpiece processing apparatus according to the fourth aspect, characterized in that the bottom section (3) of the casing (7) is sloped so as to incline downward toward the slurry inlet part (4).

[0020] A ninth aspect of the present invention pertains to the workpiece processing apparatus according to the fifth aspect, characterized in that the slope of the bottom section (3) is 8 to 12 degrees.

[0021] A tenth aspect of the present invention pertains to the workpiece processing apparatus according to the sixth aspect, characterized in that the slope of the bottom section (3) is 8 to 12 degrees.

[0022] An eleventh aspect of the present invention pertains to the workpiece processing apparatus according to the seventh aspect, characterized in that the slope of the bottom section (3) is 8 to 12 degrees.

[0023] A twelfth aspect of the present invention pertains to the workpiece processing apparatus according to the eighth aspect, characterized in that the slope of the bottom section (3) is 8 to 12 degrees.

[0024] A thirteenth aspect of the present invention pertains to the workpiece processing apparatus according to any one of the first through twelfth aspects, characterized in that a slurry passage (21) formed between the rotating body (8) and the side wall section (5) of the casing (7) is formed so as to gradually widen toward the slurry outlet part (6).

[0025] A fourteenth aspect of the present invention pertains to a method for removing oxidation scale formed on a surface of a workpiece (W), using the workpiece processing apparatus according to the first aspect, the oxidation scale removal method characterized by comprising mixing a slurry (30) with compressed air and jetting the slurry and compressed air at the surface of the workpiece (W), the slurry (30) being a mixture of a liquid (30a) and abrasive grains (30b) described below:
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.

[0026] A fifteenth aspect of the present invention pertains to the oxidation scale removal method according to the fourteenth aspect, characterized in that a chromium content of the abrasive grains (30b) is 30% (by weight) or greater.

[0027] A sixteenth aspect of the present invention pertains to the oxidation scale removal method according to the fourteenth aspect, characterized in that amorphous particles, which are illustrated in FIG. 10, are employed as the abrasive grains (30b).

[0028] A seventeenth aspect of the present invention pertains to the oxidation scale removal method according to the fifteenth aspect, characterized in that amorphous particles, which are illustrated in FIG. 10, are employed as the abrasive grains (30b).

[0029] An eighteenth aspect of the present invention pertains to the oxidation scale removal method according to the fourteenth aspect, characterized in that abrasive grains having an average particle diameter of approximately 150 µm are employed as the abrasive grains (30b).

[0030] A nineteenth aspect of the present invention pertains to the oxidation scale removal method according to the fifteenth aspect, characterized in that abrasive grains having an average particle diameter of approximately 150 µm are employed as the abrasive grains (30b).

[0031] A twentieth aspect of the present invention pertains to the oxidation scale removal method according to the sixteenth aspect, characterized in that abrasive grains having an average particle diameter of approximately 150 µm are employed as the abrasive grains (30b).

[0032] A twenty-first aspect of the present invention pertains to the oxidation scale removal method according to the seventeenth aspect, characterized in that abrasive grains having an average particle diameter of approximately 150 µm are employed as the abrasive grains (30b).

[0033] A twenty-second aspect of the present invention pertains to the oxidation scale removal method according to any one of the fourteenth through twenty-first aspects, characterized in that a long material for wire drawing, having a Vickers hardness of 200 to 400 Hv, is employed as the workpiece (W).

Effect of the Invention

[0034] Through the present invention configured as described above, an original and innovative workpiece processing apparatus and oxidation scale removal method is obtained whereby durability in the slurry pressure-feeding part can be remarkably enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] 

FIG. 1 is an explanatory drawing illustrating a working state of a workpiece processing apparatus of the present example;

FIG. 2 is an explanatory drawing illustrating an oxidation scale removal method which uses the workpiece processing apparatus of the present example;

FIG. 3 is a sectional view illustrating relevant parts of the present example;

FIG. 4 is an exploded perspective view illustrating relevant parts of the present example;

FIG. 5 is an explanatory drawing of relevant parts of the present example;

FIG. 6 is an explanatory drawing of the operation of relevant parts of the present example;

FIG. 7 is a sectional view illustrating relevant parts of the present example;

FIG. 8 is a photograph showing the state of abrasion of relevant parts of the present example;

FIG. 9 is a table indicating the composition of abrasive grains (30b) used in an oxidation scale removal method of the present example;

FIG. 10 is an enlarged photograph of the abrasive grains (30b) used in the oxidation scale removal method of the present example;

FIG. 11 is a table indicating the results of comparative testing of the oxidation scale removal method of the present example and the conventional method;

FIG. 12 is a sectional view illustrating relevant parts of a conventional example;

FIG. 13 is a perspective view of relevant parts of the conventional example;

FIG. 14 is an explanatory drawing of the operation of relevant parts of the present example; and

FIG. 15 is a photograph showing the state of abrasion of relevant parts of the present example.

BEST MODE FOR CARRYING OUT THE INVENTION

[0036] Preferred embodiments of the present invention are briefly described below with reference to the diagrams while indicating the effects of the present invention.

[0037] During jetting of a slurry (30) together with compressed air to a workpiece (W), the slurry being a mixture of a liquid (30a) and abrasive grains (30b), the slurry (30) is pressure-fed from a slurry pressure-feeding part (2) to slurry jetting parts (1).

[0038] Specifically, the slurry (30) introduced into a casing (7) from a slurry inlet part (4) in accordance with rotation of a rotating body (8) is guided by blade parts (9) in a radial direction from a rotational center of the rotating body (8) and forced out from a slurry outlet part (6).

[0039] The blade parts (9) provided to the rotating body (8) in the present invention are shaped having a length in the radial direction from the rotational center of the rotating body (8), and are curved convexly in a rotation direction, and this configuration reduces abrasion of the blade parts (9) as much as possible.

[0040] In other words, slurry extrusion surfaces (9a) of the blade parts (9) in the present invention are convexly curved rather than being flat surfaces (linear surfaces), in contrast with the conventional apparatus described above, and it is estimated that because the slurry (30) does not collide intensively with one portion of each slurry extrusion surface (9a), and the slurry (30) satisfactorily and smoothly escapes to the outside along the convex curve, slurry (30) collisions are dispersed rather than being concentrated, and abrasion of the slurry extrusion surfaces (9a) is reduced as much as possible.

Examples

[0041] Specific examples of the present invention are described below with reference to the diagrams.

[0042] The present example is a workpiece processing apparatus provided with slurry jetting parts (1) for jetting a slurry (30) together with compressed air to a workpiece (W), the slurry (30) being a mixture of a liquid (30a) and abrasive grains (30b), and the workpiece processing apparatus is used in the application of a method for removing oxidation scale (S) that forms as a result of heat treatment on a surface of a metal-made long material (W) for wire drawing as the workpiece (W) described hereinafter.

[0043] Specifically, as illustrated in FIGS. 1 and 2, the workpiece processing apparatus is provided with a workpiece conveyance part (11) for conveying the long material (W) for wire drawing, and a workpiece processing part (12) for performing a wet blast processing of the long material (W) for wire drawing conveyed by the workpiece conveyance part (11).

[0044] In the workpiece conveyance part (11), as illustrated in FIG. 1, a plurality of feed rollers (11a) on which the long material (W) for wire drawing is loaded in a bridging state are provided in a row at intervals inside a box-shaped base (10), and the long material (W) for wire drawing to be processed is continuously conveyed from an introduction part provided on one side (upstream side) of the base (10) to an outlet part provided on the other side (downstream side) of the base (10).

[0045] The long material (W) for wire drawing conveyed by the workpiece conveyance part (11) is subjected to wet blast processing by the workpiece processing part (12) while under conveyance.

[0046] Specifically, as illustrated in FIGS. 1 and 2, the workpiece processing part (12) is provided in the base (10) through which the long material (W) for wire drawing is passed, is provided with slurry jetting parts (1), a slurry storage part (13) provided in a lower position, and a slurry conveyance part (14) for conveying the slurry (30) from the slurry storage part (13) to the slurry jetting parts (1) via a slurry pressure-feeding part (2) described hereinafter, and is configured so that the slurry (30) jetted from the slurry jetting parts (1) is sent to the slurry storage part (13) and reused.

[0047] As illustrated in FIGS. 1 and 2, a plurality of (six) slurry jetting parts (1) are provided on the periphery of the long material (W) for wire drawing that is conveyed by the workpiece conveyance part (11) inside the base (10).

[0048] The slurry conveyance part (14) described above is connected to the slurry jetting parts (1), compressed-air conveyance parts (15a) provided in a separate circuit and extending from a compressed-air supply part (15) are connected to the slurry jetting parts (1), and the slurry jetting parts (1) are configured so that the slurry (30) supplied from the slurry conveyance part (14) is accelerated by compressed air supplied from the compressed-air conveyance parts (15a) and jetted from the slurry jetting parts (1) at a predetermined jetting speed.

[0049] The slurry jetting parts (1) are also provided in positions (positions offset at equal intervals in an axial direction of the long material (W) for wire drawing) at predetermined intervals in a conveyance direction of the long material (W) for wire drawing, as illustrated in FIG. 2, and are furthermore provided in positions offset at equal intervals (60-degree intervals) in a circumferential direction of the long material (W) for wire drawing, and are configured so that the slurry (30) is jetted on the entire circumferential surface of the long material (W) for wire drawing by six slurry jetting parts (1).

[0050] Consequently, the slurry (30) can be satisfactorily jetted to the long material (W) for wire drawing without jets of the slurry (30) from the slurry jetting parts (1) colliding with each other.

[0051] In the present example, two slurry jetting units in which the slurry (30) is jetted over the entire circumferential surface of the long material (W) for wire drawing by six slurry jetting parts (1) are provided in the conveyance direction of the long material (W) for wire drawing. Consequently, a total of twelve slurry jetting parts (1) are provided in the conveyance direction of the long material (W) for wire drawing. The number of slurry jetting parts (1) is set as appropriate.

[0052] In the present example, a slurry pressure-feeding part (2) is provided for pressure-feeding the slurry (30) to the slurry jetting parts (1).

[0053] As illustrated in FIGS. 1 and 3, the rotating body (8) is provided inside the casing (7) in the slurry pressure-feeding part (2) .

[0054] Specifically, the casing (7) is configured such that a hollow portion is provided at a lower end section of a cylindrical base (16) in which a drive motor (17) is disposed in an upper end section thereof, and the casing (7) is constituted from a first case half (7') molded integrally with the lower end of the base (16), and a second case half (7'') overlapped with and fastened to the first case half (7').

[0055] A communicating opening (7a) communicated with an inside space (16a) of the base (16) is provided in a top-wall center part of the casing (7), and a distal-end part of a rotary drive shaft (17a) of the drive motor (17), penetrating through the inside space (16a) of the base (16) via the communicating opening (7a), is disposed inside the casing (7). The rotating body (8) is provided to the distal-end part of the rotary drive shaft (17a).

[0056] A gap is provided between the inside space (16a) of the base (16) and a circumferential surface of the rotary drive shaft (17a).

[0057] This gap is an excess-slurry passage section (18) through which passes excess slurry (30) that is not conducted from the slurry outlet part (6) described hereinafter, from among the slurry (30) introduced into the casing (7), and the base (16) is further provided with an excess-slurry discharge part (19) for discharging the excess slurry (30) passing through the excess-slurry passage section (18).

[0058] In the present example, a stainless steel cylindrical body (20), a surface of which is chrome plated, is fitted on the periphery of the rotary drive shaft (17a), and inner surfaces of the excess-slurry passage section (18) and the casing (7) are furthermore coated with a synthetic resin member (urethane).

[0059] Consequently, the cylindrical body (20) and each portion coated with a synthetic resin member are protected from contact with the abrasive grains (30b), and abrasion thereof is prevented.

[0060] The slurry inlet part (4) is provided in a bottom section (3) of the casing (7), and the slurry outlet part (6) is provided in a side wall section (5) provided so as to be continuous with the periphery of the bottom section (3).

[0061] The bottom section (3) of the casing (7) is also sloped so as to incline downward toward the slurry inlet part (4).

[0062] Consequently, although the abrasive grains (30b) in the slurry (30) begin to accumulate on the bottom section (3) when the flow of slurry (30) is stopped by stopping of the drive motor (17), because the bottom section (3) is inclined, the resultant downstream flow of the abrasive grains (30b) reduces the accumulation thereof.

[0063] In the present example, the incline of the bottom section (3) is set to approximately 10 degrees (see FIG. 7).

[0064] The reason for this is that, although the abrasive grains (30b) are less prone to accumulate the steeper the incline of the bottom section (3) is, a steep incline causes the slurry (30) introduced from the slurry inlet part (4) to collide more vigorously, leading to more severe abrasion.

[0065] Therefore, having tested various angles, the present applicant discovered that an angle of approximately 10 degrees (in the range of 8 to 12 degrees) is a suitable angle for making the bottom section (3) less prone to abrasion while suppressing accumulation of the abrasive grains (30b) on the bottom section (3).

[0066] In the present example, a slurry passage (21) formed between the casing (7) (bottom section (3), side wall section (5), and top section) and the rotating body (8) and blade parts (9) described hereinafter is configured so as to gradually widen toward the slurry outlet part (6) (see FIG. 5).

[0067] In other words, a configuration is adopted in which the rotational center of the rotating body (8) and an opening axial center of the slurry inlet part (4) coincide, and a distance from the rotational center of the rotating body (8) and the opening axial center of the slurry inlet part (4) to the side wall section (5) of the casing (7) increases progressively toward the slurry outlet part (6).

[0068] This configuration is adopted so as to reduce abrasion as much as possible in the vicinity of the slurry outlet part (6), where the speed of the slurry (30) guided by the rotation of the rotating body (8) is most increased and abrasion is prone to occur.

[0069] In actual comparative testing of durability of the present example and the conventional apparatus, a casing (57) (second case half (57'') overlapped with and fastened to a first case half (57') molded integrally with a lower end of a base (60)) required replacement after 3000 hours in the conventional apparatus, whereas the casing (7) (second case half (7")) in the present example required replacement after a remarkably longer time of 5000 hours.

[0070] The rotating body (8) provided to the distal-end part of the rotary drive shaft (17a) is disposed inside the casing (7).

[0071] The rotating body (8) is a disc-shaped body, and blade parts (9) are provided on the surface of the rotating body (8), the blade parts having a length in the radial direction from the rotational center of the rotating body (8) and being curved convexly in the rotation direction.

[0072] By the rotation of the rotating body (8), the slurry (30) in the slurry storage part (13) is drawn in and introduced from the slurry inlet part (4), and the slurry (30) introduced into the casing (7) from the slurry inlet part (4) is guided by the blade parts (9) in the radial direction from the rotational center of the rotating body (8) and forced out from the slurry outlet part (6).

[0073] The blade parts (9) are structures in which a metal-made core material (9') detachably provided to a lower end part of the rotary drive shaft (17a) is coated with a synthetic resin (blade member (9'')), and a plurality (of six) blade parts (9) are provided at predetermined intervals (equal intervals) in the circumferential direction in the present example.

[0074] The blade parts (9) also have an arcuate cross-sectional shape which increases in width (a) progressively outward from the rotational center of the rotating body (8), and lower surfaces (distal-end surfaces in a height direction thereof) thereof are shaped so as to follow (be parallel to) the bottom section (3) (see FIG. 3).

[0075] Consequently, the slurry extrusion surfaces (9a) of the blade parts (9) are convexly curved surfaces.

[0076] The convexly curved surfaces (slurry extrusion surfaces (9a)) are preferably arcs having a radius of 50 mm to 60 mm, and the arc radius of the blade parts (9) is set to 54.5 mm in the present example.

[0077] Because the present example is configured as described above, when the slurry (30) as a mixture of the liquid (30a) and abrasive grains (30b) is jetted together with compressed air to the workpiece (W), the slurry (30) is pressure-fed from the slurry pressure-feeding part (2) to the slurry jetting parts (1).

[0078] Specifically, in accordance with the rotation of the rotating body (8), the slurry (30) introduced into the casing (7) from the slurry inlet part (4) is guided by blade parts (9) in the radial direction from the rotational center of the rotating body (8) and forced out from the slurry outlet part (6) (see FIG. 6).

[0079] The blade parts (9) provided to the rotating body (8) in the present example have a length in the radial direction from the rotational center of the rotating body (8) and are shaped so as to curve convexly in the rotation direction, and through this configuration, abrasion of the blade parts (9) is reduced as much as possible.

[0080] In actual comparative testing of durability of the present example and the conventional apparatus, blade parts (59) in the conventional apparatus required replacement after 700 hours, whereas the blade parts (9) in the present example required replacement after a remarkably longer time of 2000 hours.

[0081] Therefore, durability in the slurry pressure-feeding part (2) can be remarkably enhanced through the present example.

[0082] In the present example, a plurality of blade parts (9) are provided at predetermined intervals, and the slurry (30) can thereby be reliably guided.

[0083] In the present example, the blade parts (9) also have an arcuate cross-sectional shape which increases in width (a) progressively outward from the rotational center of the rotating body (8), and the operation and effect described above is thereby reliably demonstrated.

[0084] In the present example, the bottom section (3) of the casing (7) is sloped so as to incline downward toward the slurry inlet part (4), and it is thereby possible to reduce abrasion of the bottom section (3) while suppressing accumulation of abrasive grains (30b).

[0085] In the present example, the slope of the bottom section (3) is 8 to 12 degrees, and the operation and effect described above is thereby reliably demonstrated.

[0086] In the present example, the slurry passage (21) formed between the rotating body (8) and the side wall section (5) of the casing (7) is formed so as to gradually widen toward the slurry outlet part (6), and by this feature as well, slurry (30) collisions are therefore dispersed rather than being concentrated, and the durability of the slurry pressure-feeding part (2) can be enhanced.

[0087] The workpiece processing apparatus of the present example is used in the application of a method for removing oxidation scale (S) that forms as a result of heat treatment on the surface of a metal-made long material (W) for wire drawing.

[0088] Specifically, a slurry (30) which is a mixture of a liquid (30a) and abrasive grains (30b) is mixed with compressed air and jetted to the surface of the long material (W) for wire drawing.

[0089] Stainless steel amorphous particles (see FIG. 10) having a composition indicated in FIG. 9 are employed as the abrasive grains (30b) .

[0090] Surface processing of the long material (W) for wire drawing (having a Vickers hardness of 200-400 Hv) was performed under the conditions below using a workpiece processing apparatus configured as described above.

[0091] Abrasive grains: Stainless steel grid/Vickers hardness of 700 to 800 Hv/average particle diameter of 150 µm (85% (by weight) having a particle diameter of 90 µm to less than 200 µm)
Air pressure: 0.4 MPa
Processing speed (conveyance speed of long material (W) for wire drawing): 30 m/min

[0092] The average particle diameter of the abrasive grains (30) referred to in the present specification is defined by the mode diameter (the particle diameter appearing with the highest frequency in the distribution), and the numerical value thereof was obtained using a measurement method involving measurement by radiating laser light to the particles.

[0093] When processing was performed under the above conditions, oxidation scale (S) formed on the surface of the long material (W) for wire drawing was satisfactorily removed, and there was also no damage to the abrasive grains (30).

[0094] The results of comparative testing of the present example and the conventional processing method (shot blasting) are as shown in FIG. 11.

[0095] The surface roughness (arithmetic mean roughness and roughness pitch) of the surface of the long material (W) for wire drawing after processing is less in the present example than in the conventional example.

[0096] Consequently, not only is oxidation scale (S) removed from the surface of the long material (W) for wire drawing in the present example, but fine recesses and projections are formed on the surface of the long material (W) for wire drawing, and a lubricant used during wire drawing can be satisfactorily retained thereon.

[0097] Surface hardness after processing is also lower in the present example than in the conventional method.

[0098] In the conventional method, the surface to be processed is processed by abrasive grains (steel balls having an average particle diameter of 0.3-1 mm) having a large average particle diameter, in such a manner as to be struck thereby, and the surface of the long material (W) for wire drawing is therefore hardened. In the present example, however, the surface to be processed is processed in a scraping manner by abrasive grains having a smaller average particle diameter than in the conventional method, and hardening of the surface of the long material (W) for wire drawing is therefore reduced as much as possible.

[0099] The method of the present example can therefore be said to be effective as a method for processing the long material (W) for wire drawing. (Hardening of the surface of the long material (W) for wire drawing is considered to be undesirable in wire drawing.)

[0100] The content of chromium, for forming a passive coating for preventing rust, in the abrasive grains (30) is 30% (by weight) or greater in the present example, and the abrasive grains (30) are therefore extremely rust resistant and thus also useful in this respect as abrasive grains (30) for wet blast processing.

[0101] The present invention is not limited by the present example; the specific configuration of constituent elements thereof may be designed, as appropriate.

Claims

1. A workpiece processing apparatus provided with slurry jetting parts for jetting a slurry together with compressed air to a workpiece, the slurry being a mixture of a liquid and abrasive grains, said workpiece processing apparatus characterized in that a slurry pressure-feeding part is provided for pressure-feeding said slurry to said slurry jetting parts, and the slurry pressure-feeding part is configured so that a rotating body is provided inside a casing, a slurry inlet part is provided in a bottom section of the casing, a slurry outlet part is provided in a side wall section provided so as to be continuous with a periphery of the bottom section of the casing, said rotating body is provided with a blade part which has a length in a radial direction from a rotational center of the rotating body and which curves convexly in a rotation direction, and said slurry introduced into said casing from said slurry inlet part is guided by said blade part in the radial direction from the rotational center of said rotating body and forced out from said slurry outlet part.

2. The workpiece processing apparatus according to claim 1, characterized in that a plurality of said blade part are provided at predetermined intervals.

3. The workpiece processing apparatus according to claim 1, characterized in that said blade part has an arcuate cross-sectional shape which increases in width progressively outward from the rotational center of said rotating body.

4. The workpiece processing apparatus according to claim 2, characterized in that said blade parts have an arcuate cross-sectional shape which increases in width progressively outward from the rotational center of said rotating body.

5. The workpiece processing apparatus according to claim 1, characterized in that the bottom section of said casing is sloped so as to incline downward toward said slurry inlet part.

6. The workpiece processing apparatus according to claim 2, characterized in that the bottom section of said casing is sloped so as to incline downward toward said slurry inlet part.

7. The workpiece processing apparatus according to claim 3, characterized in that the bottom section of said casing is sloped so as to incline downward toward said slurry inlet part.

8. The workpiece processing apparatus according to claim 4, characterized in that the bottom section of said casing is sloped so as to incline downward toward said slurry inlet part.

9. The workpiece processing apparatus according to claim 5, characterized in that the slope of said bottom section is 8 to 12 degrees.

10. The workpiece processing apparatus according to claim 6, characterized in that the slope of said bottom section is 8 to 12 degrees.

11. The workpiece processing apparatus according to claim 7, characterized in that the slope of said bottom section is 8 to 12 degrees.

12. The workpiece processing apparatus according to claim 8, characterized in that the slope of said bottom section is 8 to 12 degrees.

13. The workpiece processing apparatus according to any one of claims 1 through 12, characterized in that a slurry passage formed between said rotating body and the side wall section of said casing is formed so as to gradually widen toward said slurry outlet part.

14. A method for removing oxidation scale formed on a surface of a workpiece, using the workpiece processing apparatus according to claim 1, said oxidation scale removal method characterized by comprising mixing a slurry with compressed air and jetting the slurry and compressed air at the surface of said workpiece, the slurry being a mixture of a liquid and abrasive grains described below:
Said abrasive grains are made of stainless steel, said abrasive grains have a Vickers hardness of 700 to 800 Hv, and 85% (by weight) of said abrasive grains have a particle diameter of 90 µm to less than 200 µm.

15. The oxidation scale removal method according to claim 14, characterized in that a chromium content of said abrasive grains is 30% (by weight) or greater.

16. The oxidation scale removal method according to claim 14, characterized in that amorphous particles, which are illustrated in FIG. 10, are employed as said abrasive grains.

17. The oxidation scale removal method according to claim 15, characterized in that amorphous particles, which are illustrated in FIG. 10, are employed as said abrasive grains.

18. The oxidation scale removal method according to claim 14, characterized in that abrasive grains having an average particle diameter of approximately 150 µm are employed as said abrasive grains.

19. The oxidation scale removal method according to claim 15, characterized in that abrasive grains having an average particle diameter of approximately 150 µm are employed as said abrasive grains.

20. The oxidation scale removal method according to claim 16, characterized in that abrasive grains having an average particle diameter of approximately 150 µm are employed as said abrasive grains.

21. The oxidation scale removal method according to claim 17, characterized in that abrasive grains having an average particle diameter of approximately 150 µm are employed as said abrasive grains.

22. The oxidation scale removal method according to any one of claims 14-21, characterized in that a long material for wire drawing, having a Vickers hardness of 200 to 400 Hv, is employed as said workpiece.

Drawing