JP3184845U - Cold drawn steel - Google Patents

Abstract

The present invention provides a cold drawn steel material in which the black skin of a rod-like steel material for cold drawing is removed well to improve the surface roughness after the cold drawing process.
The black skin is removed by applying wet blasting (S1) to the rod-shaped steel material with black skin. Thereafter, a cold drawn steel material having a surface roughness improved to 0.3 μmRa or less is manufactured by performing a cold drawing process (S2) and a correction process (S3).
[Selection] Figure 1

Description

  The present invention relates to a cold-drawn steel material subjected to a surface treatment.

  Conventionally, shot blasting has been known as a method for removing the black skin of a rod-like steel material for cold drawing with a black skin (oxide film). In this shot blasting process, the black skin is removed by causing solid particles (media) called a sharpener to collide with pressurized air (pressurized air) on the surface of the rod-shaped steel material. . The rod-shaped steel material from which the black skin has been removed is subjected to a cold drawing process, and then subjected to a straightening process, etc., to become a cold drawn steel material with improved surface roughness.

JP 2005-138146 A

  However, in the above-described shot blast treatment, the media is projected in the air by the impeller and diffused and collides with the surface of the rod-shaped steel material, so that the scouring force is reduced. Therefore, it is necessary to increase the particle size of the media in order to obtain a black skin scouring force. From this, after removing the black skin of the rod-shaped steel material by shot blasting, when the cold drawn steel material is manufactured by performing the cold drawn steel material, the surface roughness of the cold drawn steel material is improved to 0.4 μmRa or less. There is a problem that it is difficult to do. Ra is a parameter representing the surface roughness and represents the arithmetic average roughness. Arithmetic average roughness is the average length of the deviation from the average line of the extracted part to the measurement curve, and the average value is expressed in μm. It is.

  The present invention has been made in view of the above-mentioned problems, and cold drawing in which the black skin of the rod-like steel material for cold drawing is removed well to improve the surface roughness after the cold drawing process. It is an object to provide a steel material.

  In order to solve the above problems, the cold drawn steel material of the present invention is obtained by subjecting a rod-shaped steel material with black skin to wet blasting to remove the black skin, and then performing cold drawing to perform surface roughening. The thickness is 0.3 μmRa or less.

  Here, the wet blast treatment is a rod-shaped steel material that is a processing object together with pressurized air, which is a mixture (slurry) of solid particles (media) and liquid (for example, water) as the above-described abrasive. Are sprayed onto the surface of the film to perform a uniform treatment. A wet blasting apparatus, which is an apparatus that performs this wet blasting process, includes a slurry storage unit, a nozzle, an air injection unit, and the like, and stores the slurry stored in the slurry storage unit together with the pressurized air injected from the air injection unit. It is ejected from the nozzle. In wet blasting, microparticles are used as the media and the process is performed by mixing microparticles and liquid, so that uniform processing is possible while suppressing heat generation during processing and alteration or deformation of the processing object. It can be performed. Further, the surface treatment can be satisfactorily performed without generating dust or attaching dirt with the treatment.

  According to the present invention, by performing the above-described wet blasting treatment, the black skin of the rod-shaped steel material is satisfactorily removed, and the surface roughness of the cold drawn steel material after the cold drawing treatment is improved to 0.3 μmRa or less. be able to. That is, the surface roughness of the cold-drawn steel material can be further improved as compared with the case where the conventional shot blast treatment is performed.

  In addition, the rod-shaped steel material may be a solid rod-shaped material or a tubular material having a shaft hole, and may be a carbon steel or alloy steel having a round, hexagonal, square, or flat cross-sectional shape used for machine structures and various parts. Good. Further, after the cold drawing process, it is preferable to perform a straightening process on the cold drawn steel material.

  According to the present invention, a cold-drawn steel material with improved surface roughness can be provided.

It is a figure which shows the flow of the process of the steel materials in this embodiment. It is a figure which shows the outline of a cold drawing process. It is a figure which shows the outline of a correction process. It is a figure which shows the surface roughness of the cold drawn steel material in the case of performing a wet blasting process. It is a figure which shows the surface roughness of the cold drawn steel material in the case of performing the conventional shot blasting process.

  Hereinafter, the cold-drawn steel material of the present embodiment will be described with reference to the drawings. FIG. 1 is a diagram showing a flow of processing in this embodiment of the rod-shaped steel material 1. In the present embodiment, as shown in FIG. 1, the process proceeds in the order of wet blasting (step S1, step is omitted), cold drawing (S2), and correction (S3).

  First, wet blasting is performed on the rod-shaped steel material 1 that is the object to be treated (S1). This rod-shaped steel material 1 is a solid round bar, made of, for example, structural carbon steel such as S48C, and has a surface with a black skin (oxide film) or the like. The material of the rod-shaped steel material 1 is not limited to structural carbon steel, but may be alloy steel or the like.

  In the wet blast treatment, the surface is treated by spraying a mixture (slurry) of solid particles (media) and a liquid as a polishing agent onto the object to be treated together with pressurized air. The media functions as an abrasive. The material of the media is, for example, made of stainless steel. In addition, various media such as alumina and silicon carbide media may be used. The particle size of the media is assumed to be 200 μm or less, for example. The pressure of the pressurized air is, for example, 0.35 MPa to 0.45 MPa. For example, water is used as the liquid. In addition, you may mix chemicals, such as a rust preventive agent, in water.

  This wet blasting process is performed by a wet blasting apparatus (not shown). The wet blasting apparatus includes a slurry storage unit, a nozzle, an air injection unit, and the like. The wet blasting apparatus performs surface treatment of a processing object by injecting the slurry stored in the slurry storage part onto the processing object from the nozzle together with the pressurized air injected from the air injection part. In this wet blasting apparatus, air and slurry are jetted at a constant pressure in a uniformly mixed state. This makes it possible to prevent processing unevenness from occurring on the processing object. Note that the surface roughness of the object to be processed can be controlled by controlling conditions such as air pressure, particle size, and jetting time.

  The rod-shaped steel material 1 is conveyed to the above-described wet blasting apparatus and subjected to wet blasting (S1). When wet blasting is performed, foreign matter such as black skin (oxide film) or oil attached to the surface of the rod-shaped steel material 1 is minimized. Specifically, the surface, which is a fine particle, is scraped off by rubbing the surface of the rod-shaped steel material 1. Thereby, the black skin etc. which adhered to the surface of the rod-shaped steel material 1 are removed. At this time, the water accelerated by the pressurized air causes the media to flow, so that the media hardly collide with each other and the media is smoothly conveyed. Moreover, since the scraped scraps of the rod-shaped steel material 1 and the worn media are mixed with water and flowed, no dust is generated due to the treatment. Furthermore, the water cooling action can instantaneously remove the heat generated by the collision between the medium and the rod-shaped steel material 1, and the rod-shaped steel material 1 can be prevented from being altered or deformed due to the generation of heat. Further, the surface of the rod-shaped steel material 1 is covered with water, thereby preventing dirt and the like from reattaching.

  When wet blasting is performed in this way, a uniform surface treatment is performed on the rod-shaped steel material 1, and the surface roughness of the rod-shaped steel material 1 is improved. In this embodiment, the surface roughness of the rod-shaped steel material 1 after the wet blast treatment is 2.5 μmRa or less.

  Next, lubricating oil is applied to the rod-shaped steel material 1 (not shown). This lubricating oil is for reducing the frictional resistance between the rod-shaped steel material 1 and the die 3 in the cold drawing process described later. The surface roughness of the rod-shaped steel material 1 is improved by the above-described wet blast treatment (S1). For this reason, as for the rod-shaped steel material 1, lubricating oil is apply | coated favorably to the surface.

  Next, the rod-shaped steel material 1 is subjected to a cold drawing process (S2). The rod-shaped steel material 1 passes through the die 3 while being drawn in the direction of the arrow (left to right) shown in FIG. The rod-shaped steel material 1 is deformed by passing through the die 3. At this time, the sticking of the rod-shaped steel material 1 and the die 3 is prevented by the action of the lubricating oil described above.

  The die 3 is cylindrical. The inner diameter of the die 3 gradually decreases from upstream to downstream (left to right in FIG. 2). The rod-shaped steel material 1 passes through the die 3 while undergoing plastic deformation and is processed until the minimum inner diameter of the die 3 is reached, thereby forming a cold drawn steel material 2 having a desired size. In this cold drawing process (S2), the rod-shaped steel material 1 becomes a cold drawn steel material 2 having excellent dimensional accuracy.

  In the case of round steel, after the cold drawing process, the cold drawn steel material 2 is subjected to a straightening process (S3). This straightening process is a process for improving the straightness of the cold drawn steel material 2, and is performed by the straightening machine 4 shown in FIG. The straightening machine 4 is composed of two rolls, a concave roll 5 and a convex roll 6. The concave roll 5 and the convex roll 6 are arranged such that the roll axes are oblique to each other. The straightening machine 4 sandwiches the cold drawn steel material 2 between the concave roll 5 and the convex roll 6. The cold drawn steel material 2 advances while rotating in the direction of the white arrow shown in FIG. 3 (from left to right). The straightening machine 4 improves the straightness of the cold drawn steel material 2 by repeatedly bending the cold drawn steel material 2 with the concave roll 5 and the convex roll 6. After passing through the straightening machine 4, the curvature of the cold drawn steel material 2 becomes close to zero.

  FIG. 4 is a diagram (roughness curve) showing the surface roughness of the cold drawn steel material 2 when the cold drawing process (S2) and the straightening process (S3) are performed after the wet blasting process (S1). ). The surface roughness of the cold-drawn steel material 2 is improved to an arithmetic average roughness of 0.22 μmRa (see FIG. 4). Thus, according to the cold drawn steel material 2 of this embodiment, it is possible to make the surface roughness 0.3 μmRa or less.

  As a comparative example, FIG. 5 shows that after the shot blast treatment is performed on the same rod-shaped steel material as the rod-shaped steel material 1, the cold-drawing process (S2) and the straightening process (S3) are similarly performed. It is a figure (roughness curve) which shows the surface roughness of the said cold drawn steel material in the case of manufacturing steel materials. In the example shown in FIG. 5, the surface roughness of the cold drawn steel material is 1.06 μmRa in terms of arithmetic average roughness. When the surface roughness when the shot blasting process shown in FIG. 5 is performed and the surface roughness when the wet blasting process shown in FIG. 4 is compared, the surface roughness of FIG. 5 is larger than that of FIG. You can see that That is, the cold drawn steel material 2 when the wet blasting treatment of the present embodiment is performed can improve and improve the surface roughness than the cold drawn steel material when the shot blasting treatment is performed.

  As described above, the cold-drawn steel material 2 of the present embodiment is obtained by removing the black skin of the bar-shaped steel material 1 with a black skin by wet blasting (S1), and then performing cold drawing (S2). The surface roughness is 0.3 μmRa or less.

  According to this configuration, by performing wet blasting, the black skin of the rod-like steel material 1 for cold drawing is removed well, and cold after cold drawing (S2) and straightening (S3). The surface roughness of the drawn steel material 2 can be improved to 0.3 μmRa or less (in the above embodiment, 0.22 μmRa) (see FIG. 4). Thereby, the cold-drawn steel material 2 with excellent surface roughness and high quality can be manufactured.

  Conventionally, in order to improve the surface roughness to 0.4 μmRa or less, the grinding / polishing process is performed after the correction process (S3). However, according to the present invention, the grinding / polishing process is not performed. The manufacturing process can be simplified.

  In addition, this invention is not limited to embodiment mentioned above, A various change can be given in the range which does not deviate from the summary of this invention.

  For example, in this embodiment, although the case where the process of this invention was applied to the solid rod-shaped steel material 1 was demonstrated, it is not restricted to this, It uses for the tubular steel material which has a shaft hole, machine structure, and various components. The present invention may be applied to carbon steel and alloy steel having a round, hexagonal, square, or flat cross-sectional shape.

  Further, in the straightening process (S3), the straightening machine 4 including the two rolls of the concave roll 5 and the convex roll 6 is used. However, the invention is not limited to this. For example, a three-roll straightening machine or a multi-roll straightening machine may be used. Good.

DESCRIPTION OF SYMBOLS 1 Bar-shaped steel material 2 Cold-drawn steel material 3 Dies 4 Straightening machine 5 Concave roll 6 Convex roll

Claims (4)

  Cold drawn steel with a surface roughness of 0.3 μmRa or less by performing a cold drawing after removing the black skin by performing a wet blast treatment on the black steel with a black skin .   The rod-shaped steel material is any one of a solid bar shape, a tubular shape having a shaft hole, a carbon structure and a steel alloy having round, hexagonal, square, and flat cross sections used for mechanical structures and various parts. The cold-drawn steel material according to claim 1.   The cold-drawn steel material according to claim 1 or 2, wherein the cold-drawn steel is subjected to a straightening process after the cold-drawing process.   The cold-drawn steel material according to any one of claims 1 to 3, wherein the surface roughness after the wet blasting is 2.5 µmRa or less.

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