JPWO2017221894A1 - Projection material and method for surface treatment of metal products using the projection material - Google Patents

Abstract

In the cast steel projection material used for removing the scale formed on the surface of the metal product by blasting, the particle diameter d1 is a projection material group belonging to the first particle diameter section d1max ≧ d1> d1min, The first group having the maximum frequency P1 in the particle diameter section and the projection material group in which the particle diameter d2 belongs to the second particle diameter section d2max ≧ d2> d2min, and has the maximum frequency P2 in the second particle diameter section. And the first group and the second group satisfy the relationship of d1max = d2min, and the particle size frequency distribution of the projection material composed of the first group and the second group is substantially It is continuous.

Description

  The present disclosure relates to a cast iron projection material used in a process of removing oxide scale attached to the surface of a metal product manufactured by hot forging and the like, and a surface treatment method using the projection material.

  Conventionally, when a scale made of an oxide adheres to the surface of a metal product (for example, processing such as forging), a projection material made of hard particles is projected onto the surface of the metal product in order to perform blasting to remove the scale. Shot blasting is performed (for example, Patent Document 1).

JP 2001-121205 A

  In many metal products, after the scale is removed, the dimensions are adjusted as necessary, and then the final product is completed through finishing processing according to the target metal product. For example, when manufacturing a sliding component such as a bearing, a process of providing a large number of small depressions (dimples) for holding lubricating oil on the surface is performed. Therefore, in the step of removing the scale, if the metal surface can be roughened and an appropriate dimple can be formed, it contributes to cost reduction. However, there are no projectiles and blasting methods that have the ability to remove scale and form appropriate dimples on the surface of metal products.

  In addition to the sliding parts, it is necessary to grip a metal product with a jig in finishing. For this reason, the surface of the metal product needs to be roughened to such an extent that the gripping force can be increased. In order to roughen the surface of the metal product, it is necessary to use a relatively large diameter projection material. However, when the size of the projection material is increased, the coverage (actual impact area of the projection material per fixed area) is reduced. Therefore, the efficiency of removing scale is reduced. Furthermore, removal of defects existing in the surface layer portion of metal products, for example, sealing of microcracks, is also required to be performed simultaneously with scale removal.

  That is, there is a demand for efficient removal of scale and roughening, or removal of defects existing in the surface layer portion in a single process. However, there is no projectile material and surface treatment method that makes it possible.

  Therefore, in the present disclosure, for the metal product on which the scale is formed, the projection material capable of efficiently removing the scale, roughening the surface, or removing defects existing in the surface layer portion, and A surface treatment method using the projection material is provided.

  One aspect of the present disclosure is a cast steel projection material used for removing a scale formed on a surface of a metal product by blasting. This projection material includes a first group and a second group of projection materials. The first group is a projection material group in which the particle diameter d1 belongs to the first particle diameter section d1max ≧ d1> d1min, and has the maximum frequency P1 in the first particle diameter section. The second group is a projection material group in which the particle diameter d2 belongs to the second particle diameter section d2max ≧ d2> d2min, and has the maximum frequency P2 in the second particle diameter section. The first group and the second group satisfy the relationship d1max = d2min. The particle size frequency distribution of the projection material composed of the first group and the second group is substantially continuous.

  The first group of projection materials mainly contributes to efficient removal of scales, and the second group of projection materials removes scales by blasting and roughening the surface of the metal product, or This contributes to the removal of defects present in the surface layer of metal products. In the projection material of the present disclosure, by adjusting the particle size distribution of the projection material so that both the first group of projection materials and the second group of projection materials exist, the respective advantages are maintained and the blast is insufficient. Complement processing capacity. That is, the scale can be efficiently removed from the metal product on which the scale is formed, the surface can be roughened, and defects present in the surface layer portion of the metal product can be sufficiently removed.

  In one embodiment, d1min = 0.710 mm and d2max = 1.700 mm, and d1max may be 1.000 mm or 1.180 mm. In this case, it is possible to effectively roughen the surface of the metal product or remove defects present in the surface layer portion of the metal product.

  In one embodiment, the metal product may be a hot forged product, and the projection material may have a Vickers hardness of HV300 to HV600. When the projection material is HV300 or higher, the projection material has a sufficient hardness with respect to the blast treatment target, and when the projection material is HV600 or less, the projection material has sufficient toughness. For this reason, by setting it as the projection material whose Vickers hardness is HV300-HV600, it can have sufficient hardness and toughness, and even if a metal product is a hot forging product, it can fully surface-treat. .

  In one embodiment, the metal product is a sliding part, and the maximum frequency P1 has a particle diameter section 1.180 mm ≧ d1> 1.000 mm, and the maximum frequency P2 has a particle diameter section 1.700 mm ≧ d2> 1.400 mm. May be present.

  In one embodiment, d1min = 0.600 mm and d2max = 1.180 mm, and d1max may be 1.000 mm or 1.180 mm. In this case, the metal product may be a hot forged product, and the projection material may have a Vickers hardness of HV300 to HV600. Further, the metal product is a sliding part, and the maximum frequency P1 is present in the particle diameter section 1.000 mm ≧ d1> 0.850 mm, and the maximum frequency P2 is present in the particle diameter section 1.180 mm ≧ d2> 1.000 mm. Good.

  In one embodiment, d1min = 0.600 mm and d2max = 1.180 mm, and d1max may be 1.000 mm or 1.180 mm. In this case, the metal product may be a hot forged product, and the projection material may have a Vickers hardness of HV300 to HV600. Further, the metal product is a sliding component, and the maximum frequency P1 is present in a particle diameter section 1.000 mm ≧ d1> 0.850 mm, and the maximum frequency P2 is present in a particle diameter section 1.700 mm ≧ d2> 1.400 mm. Good.

  In one embodiment, the entire projection material may be formed with a convex curved surface. In this case, for example, dimples having an infinite number of curved surfaces can be formed. Further, since the contact area of the projection material is uniform and wide, the plastic deformation of the metal product can be performed efficiently, and the defects present in the surface layer portion of the metal product can be efficiently removed.

  Another aspect of the present disclosure is a metal product surface treatment method using the above-described projection material, the projection material loading step of loading an unused projection material into the blasting device, and the operation of the blasting device. An operating mix forming process for forming an operating mix in which a constant particle size distribution is stable, and a projection material is projected onto the metal product by a blasting device to remove the scale of the surface of the metal product, A surface treatment step of roughening the surface or removing defects present on the surface layer portion of the surface of the metal product.

  According to this disclosure, using the above projection material, in a state where the operating mix is formed in the operating mix forming step, the scale of the surface of the metal product is removed and the surface of the metal product is roughened, or Defects present in the surface layer portion on the surface of the metal product can be efficiently removed.

  In one embodiment, the particle size distribution of the projection material after the operating mix formation step is 0.250 mm to 1.700 mm and may have maximum frequencies P1 and P2. In this case, both removal of the scale and roughening with the projection material of the particle size distribution group having the maximum frequency P1 or removal of defects existing in the surface layer portion can be achieved for a long time.

  In one embodiment, the maximum frequencies P1 and P2 may satisfy P2 ≦ P1.

  In one embodiment, the particle size distribution of the projection material after the operating mix formation step is the same as that of the unused projection material, and the frequency V between the maximum frequencies P1 and P2 is the maximum without changing the positions of the maximum frequencies P1 and P2. You may increase relatively with respect to frequency P1 and P2. When comprised in this way, the particle size distribution between maximum frequency becomes broad, maintaining the effect of the projection material of the 1st group, and the effect of the projection material of the 2nd group. For this reason, since the magnitude | size of the dent by a projection material has a continuous distribution, a coverage can be increased and surface treatment can be performed efficiently. Note that “the frequency V between the maximum frequencies P1 and P2 increases relative to the maximum frequencies P1 and P2” means that the difference between the maximum frequency P1 and the frequency V and the maximum frequency P2 and the frequency V It means that at least one of the differences becomes smaller.

  In one embodiment, the metal product is a sliding part formed by hot forging. The surface treatment process removes the scale of the surface of the sliding part, and JIS-B0601: 2000 (JIS: Japan Industrial). The ten-point average roughness Rz defined by Standards) may be 50 μm to 60 μm. In this case, in the surface treatment process of the sliding component, it can be adjusted to a suitable surface roughness in post-processing or the like.

  For a metal product on which a scale is formed, a projection material capable of efficiently removing the scale and roughening the surface or removing defects existing in the surface layer portion and the projection material are used. A surface treatment method is provided.

It is explanatory drawing which shows typically the particle diameter distribution of the projection material of this indication. (A) is explanatory drawing which shows a projection density when coverage has reached 100%. (B) is explanatory drawing which shows the number of the projection materials per kg with respect to the particle diameter of a projection material. It is explanatory drawing which shows the relationship between the particle diameter of a projection material, and collision energy. It is explanatory drawing which shows the relationship between the particle diameter of a projection material, and the lifetime value of a projection material. It is explanatory drawing which shows typically the particle diameter distribution after the operating mix formation process of the projection material of an Example compared with the particle diameter distribution before an operating mix formation process. It is a particle size distribution before the operating mix formation process of the projection material of an Example. It is a particle size distribution after the operating mix formation process of the projection material of FIG. It is a particle size distribution before the operating mix formation process of the projection material of an Example. It is a particle size distribution after the operating mix formation process of the projection material of FIG.

  The projection material according to the present disclosure is a cast material made of cast iron (made of cast steel) that can be used to remove scale from the surface of a metal product by blasting. Here, the hardness of the projection material can be appropriately selected according to the metal product to be scale-removed. This embodiment demonstrates the projection material which can be used for the surface treatment of the metal product manufactured (molded) by hot forging, such as a gear, a cylinder, and a sliding component.

  The projection material is a spherical shot made of an iron-based material (cast iron) selected from the range of Vickers hardness HV300 to HV600. Here, as such an iron-based material, for example, C: 0.8% to 1.2% by weight, Mn: 0.35% to 1.20%, Si: 0.40% to 1.50 %, P ≦ 0.05%, S ≦ 0.05%, the balance containing Fe and inevitable impurities, tempered martensite structure and / or bainite structure, quenched martensite structure or similar Particles having a texture can be employed. Such particles can be prepared by a known method such as a water atomizing method. Here, the projection material has sufficient hardness for the blast treatment target at HV300 or higher, and the projection material has sufficient toughness at HV600 or lower. Thus, since the projection material of this indication has sufficient hardness and toughness, it can be used for the blast process of the surface of a hot forging product. Here, the Vickers hardness HV is based on Japanese Industrial Standard JIS Z 2244 (2009).

  FIG. 1 schematically shows the particle size distribution of the projection material. The horizontal axis is the particle size, and the vertical axis is the weight fraction. The projection material is a projection material group belonging to the first particle diameter section d1max ≧ d1> d1min (particle diameter d1) that mainly contributes to removal of scale, and the first group having the maximum frequency P1 in the particle diameter section. And a projection material group belonging to the second particle diameter section d2max ≧ d2> d2min (particle diameter d2), which mainly contributes to the roughening of the surface of the metal product or the removal of defects existing on the surface layer portion of the metal product. And a second group having a maximum frequency P2 in the particle diameter section. Here, the first group and the second group satisfy the relationship d1max = d2min. Moreover, the particle diameter frequency distribution of the projection material comprised by the 1st group and the 2nd group is substantially continuous. Hereinafter, the frequency between the maximum frequencies P1 and P2 is assumed to be V (V1, V2,...).

  Here, “particles having a particle diameter interval d1max ≧ d> d1min” passed through a standard sieve having a nominal aperture d1max in JIS Z8801 (2006) and captured by a standard sieve having a nominal aperture d1min (passed). Not) Indicates particles. For example, “particles having a particle diameter section of 1.700 mm ≧ d> 1.400 mm” pass through a standard sieve having a nominal aperture of 1.700 mm in JIS Z8801 (2006) and having a nominal aperture of 1.400 mm. Shows particles trapped (not passed) through a sieve. In addition, it is allowed to contain about 5% at maximum of small-diameter particles having a particle diameter interval equal to or lower than the lower limit value. In each figure, the particle diameter on the horizontal axis shows the lower limit of the particle diameter section as a representative value. For example, when the particle diameter is expressed as 1.400 mm, “a particle having a particle diameter section of 1.700 mm ≧ d> 1.400 mm” is indicated.

  The first group of projectiles needs to increase the coverage with a smaller projection amount in order to efficiently remove the scale. FIG. 2A is a graph showing the relationship between the particle diameter and the projection density when the coverage reaches 100%. The horizontal axis is the particle diameter, and the vertical axis is the projection density. The projection density was evaluated by using an impeller-type blasting device and causing the projection material to collide with the workpiece 1 and the workpiece 2 on a SUJ2 (high carbon chromium bearing steel) target having a projection speed of 73 m / s and a hardness of HV200. The projected work was photographed with a microscope and the coverage was evaluated by comparison with a standard photograph.

  It was recognized that the smaller the particle diameter, the more the coverage reached 100% at a small projection density. This is because the smaller the particle diameter, the greater the number of projection materials per unit mass, and thus the greater the chance that the projection material contacts the metal product. (B) of FIG. 2 is a graph of the number of projection materials per kg with respect to the particle diameter of the projection material. The horizontal axis is the particle diameter, and the vertical axis is the number of projection materials per unit mass. It can be seen that when the particle diameter of the projection material is 1.000 mm or less, the number of projection materials per unit mass is increased. Therefore, in order to efficiently remove the scale, the particle diameter can be set to 1.000 mm or less. In addition, a projection material having a particle size of 0.500 mm or less is easily removed by a separator or a dust collector in a blasting process described later, leading to a reduction in the lifetime of the projection material. For this reason, the particle diameter may exceed 0.600 mm.

The second group of projectiles removes the scale by blasting and has sufficient impact energy to roughen the surface of the metal product or to remove defects present on the surface layer of the metal product. It is necessary to have. FIG. 3 is a graph showing the relationship between the particle size of a single particle size projection material and the collision energy. The horizontal axis is the particle diameter, and the vertical axis is the collision energy per grain. Here, the collision energy was calculated from ½ × M × V2 (M = ρ × 4/3 × πr ³ ) at the projection material weight M and speed V. Note that ρ = 7.5 g / cm ³ and V = 70 m / s. For roughening the surface of the hot forged product, at least 0.01 J / piece of collision energy is required. For this reason, a particle diameter can be 1.000 mm or more. Moreover, the particle diameter of 1.200 mm or more can be used for removal of defects existing in the surface layer portion of the metal product, for example, microcrack sealing treatment.

  Next, the appropriate particle diameter was examined from the lifetime of the projection material. FIG. 4 is a graph showing the relationship between the particle diameter of the projection material and the lifetime value. The horizontal axis is the particle diameter, and the vertical axis is the lifetime value. The life test of the projecting material conforms to 100% Replacement Method defined in SAE J445 (SAE: Society of Automotive Engineers), uses an Irvine type life tester, the projection speed is 60 m / s, the target hardness is HRC65 (HRdwell Wells) ), And the cut-off value was measured with a sieve mesh under one screen. The blasting material crushed at every fixed number of collisions was removed by sieving, the weight of the remaining blasting material was measured, and the test was performed until the remaining blasting material was 30% or less of the first. The value obtained by integrating the life curve indicating the relationship between the number of collisions obtained by this test and the weight ratio of the residual projection material was defined as the life value.

  As the particle diameter of the projection material is larger, the life tends to be shorter. The life value of the projection material is often required to be 1000 cycles or more. For this reason, the 2nd group projection material can be 1.700 mm or less. In addition, when a projection material having a large particle size is used, damage to the blasting apparatus, for example, wear of parts increases. For this reason, it is not necessary to increase the particle size more than necessary.

  Only the first group of projectiles can improve the coverage, so that the scale can be removed efficiently. However, the surface of the metal product is roughened, or the defects present on the surface layer of the metal product are removed. The removal cannot be performed sufficiently.

  On the other hand, only the second group of projection materials can sufficiently roughen the surface of the metal product or remove defects present on the surface layer of the metal product, but the number of particles per unit weight is small. Therefore, it leads to a decrease in the coverage (actual dent area of the projection material per certain area).

  In the projection material of the present disclosure, by adjusting the particle size distribution of the projection material so that both the first group of projection materials and the second group of projection materials exist, the respective advantages are maintained and the blast is insufficient. Complement processing capacity. That is, the scale can be efficiently removed from the metal product on which the scale is formed, the surface can be roughened, and defects present in the surface layer portion of the metal product can be sufficiently removed. Here, the first group and the second group may satisfy the relationship d1max = d2min. Moreover, the particle diameter frequency distribution of the projection material comprised by the 1st group and the 2nd group is substantially continuous. Thereby, since the size of the dents by the surface treatment has a continuous distribution, the coverage can be increased and the surface treatment can be performed efficiently. In order to achieve this effect, d1max = d2min may be 1.000 mm or 1.180 mm.

  Here, in order to effectively perform the roughening or the removal of defects existing in the surface layer portion, the ratio of the first group of projection materials is adjusted so that the maximum frequencies P1 and P2 satisfy P2 ≦ P1. Good.

  When the metal product is a sliding part, the maximum frequency P1 exists in the particle diameter section 1.000 mm ≧ d1> 0.850 mm, and the maximum frequency P2 exists in the particle diameter section 1.700 mm ≧ d2> 1.400 mm. A projectile can be used. Alternatively, a projection material in which the maximum frequency P1 exists in the particle diameter section 1.180 mm ≧ d1> 1.000 mm and the maximum frequency P2 exists in the particle diameter section 1.700 mm ≧ d2> 1.400 mm may be used. When it is desired to reduce the surface roughness, the maximum frequency P1 is present in the particle diameter section 1.000 mm ≧ d1> 0.850 mm, and the maximum frequency P2 is present in the particle diameter section 1.180 mm ≧ d2> 1.000 mm. A projectile can be used.

  The particle size distribution of the projection material can be appropriately changed according to the properties (shape, material, scale state, etc.) of the metal product as the workpiece and the purpose of the surface treatment. For example, d1min = 0.710 mm and d2max = 1.700 mm, and d1max may be 1.000 mm or 1.180 mm. Alternatively, d1min = 0.600 mm and d2max = 1.180 mm, and d1max = d2min may be 1.000 mm or 1.180 mm. Alternatively, d1min = 0.600 mm and d2max = 1.700 mm, and d1max = d2min may be 1.000 mm or 1.180 mm. In any case, having the maximum frequency P1 and P2 and having a substantially continuous particle size distribution effectively removes the scale from the scaled metal product, The surface can be roughened, and defects present in the surface layer portion of the metal product can be sufficiently removed.

  The blasting material is classified using sieving sieves specified in JIS Z 8801 (2006) using a known method such as a water atomizing method, and mixed and adjusted so as to obtain a desired particle size distribution. Can be produced.

  Next, a surface treatment method for performing scale removal and roughening or sealing treatment by blasting using the above-mentioned projection material will be described.

  In order to perform the surface treatment of the metal product using the projection material of the present disclosure, for example, a known centrifugal blasting device as described in Patent Document 1 can be used. Note that the blasting method of the present disclosure is not limited to the method using the blasting apparatus.

  The blast device includes a hopper that stores and supplies a fixed amount of the projection material, an impeller unit that projects the projection material, a circulation device that circulates the projection material, a separator that separates the projection material from sand and scale, and a dust collector. .

  The projection material is thrown into the impeller unit from the hopper, and the projection material thrown into the impeller unit is accelerated in the impeller unit and projected onto the metal product arranged in the projection chamber. Thereby, the blasting of the metal product is performed.

  The projected blast material is collected by the circulation device together with the scale removed from the metal product by the blasting process, and sent to the separator.

  In the separator, the projection material is dropped into an apron, and sand, scales and pulverized fine projection material are selected by the air flow generated by the dust collector, and they are discharged out of the dust collector and the apparatus. The projection material effective for the blasting process is again supplied to the impeller unit and recycled.

  Since the amount of projection material in the apparatus decreases by the amount discharged to the outside of the apparatus, it is necessary to replenish the amount of projection material corresponding to the amount of decrease (projection material loading step of loading unused projection material into the blast device). . The decrease in the blast material is detected by the load current value of the impeller unit, and a new blast material is automatically or manually supplied to the hopper.

  As a result of a series of operations for repeatedly performing the above-described projection, fine powder discharge from the device, and replenishment, the particle size distribution of the in-device projection material is stabilized at a constant particle size distribution different from the particle size distribution of the unused projection material ( An operating mix forming step of forming an operating mix in which the particle size distribution of the projection material is stabilized by the operation of the blasting apparatus). This state of stable particle size distribution is called operating mix. After the operating mix formation process, the projection material is projected onto the metal product with a blasting device to remove the scale on the surface of the metal product, and the surface of the metal product is roughened or a defect present on the surface of the metal product surface. Is removed (surface treatment step). It is important that the projection material is managed so that the particle size distribution of the projection material in the apparatus after forming the operating mix can be efficiently blasted.

  When the projection material of the present disclosure is used, the particle size distribution in the blasting apparatus after the operating mix forming step is broad (for example, 0.250 mm to 1.700 mm) and is maximum without using a special apparatus or method. It is possible to have frequencies P1 and P2. And compared with an unused projection material, the position (particle diameter) of maximum frequency P1 and P2 does not change, but frequency V between maximum frequency P1 and P2 increases relatively with respect to maximum frequency P1 and P2. A characteristic distribution can be obtained. According to this, the particle size distribution between the maximum frequencies becomes broad while maintaining the effect of the first group of projection materials and the effect of the second group of projection materials. Since the size of the dents by the projection material has a continuous distribution, the coverage can be increased and the surface treatment can be performed efficiently.

  Further, in order to effectively perform roughening or removal of defects existing on the surface layer portion while performing efficient scale removal, the maximum frequency P1 in the particle size distribution in the blasting apparatus after the operating mix formation step. And P2 may satisfy P2 ≦ P1.

  The entire projection material may be formed of a convex curved surface. When the surface treatment process is performed using a projection material that is entirely formed with a convex curved surface, for example, dimples having an infinite number of curved surfaces on the surface can be formed. For this reason, the dimple for holding lubricating oil on the surface can be formed without losing the slidability of the metal product. Further, since the contact area of the projection material is uniform and wide, the plastic deformation of the metal product can be performed efficiently, and the defects present in the surface layer portion of the metal product can be efficiently removed. Note that “the whole is formed of a convex curved surface” refers to a shape having no corners. In addition to spherical particles, for example, particles having a shape obtained by chamfering and rounding corners of cylindrical particles are also included.

(Example of change)
The form of the projection material is not limited to shots, and grit, cut wires, and the like can also be used.

  The projection material and the surface treatment method of the present disclosure can be applied to the surface treatment of a metal product of a material in which a scale is formed and a manufacturing method other than a hot forged product made of steel. For example, it can be applied to scale removal of a rolled steel sheet.

(Effect of embodiment)
According to the projection material of the present disclosure and the surface treatment method using the projection material, the scale is efficiently removed from the metal product on which the scale is formed, and the surface is roughened or formed on the surface layer portion. Existing defects can be removed. In particular, it can be used for surface treatment of a hot forged product by appropriately setting the hardness and particle size distribution of the projection material.

  Hereinafter, examples performed for confirming the effects of the present disclosure will be described.

The scale was removed using the projection material of the present disclosure, and the surface roughness after the surface treatment was evaluated. The workpiece used in this test is made of SUJ, the shape is a cylinder (inner ring of a tapered roller bearing), and the projection test apparatus used for the test is a shot blasting SNTX-I type (Shinto Kogyo Co., Ltd.). The projection speed was 73 m / s. The projection density was the projection density when reaching 100% coverage. Projection ^density was ^{150kg / m 2 ~300kg / m 2} . The evaluation item was surface roughness, and the ten-point average roughness Rz (μm) defined in JIS-B0601: 2000 was adopted as the measurement method.

  The projecting material was a steel shot having a hardness of HV450, and a projecting material in which the particle diameter at the maximum frequencies P1 and P2 and the ratio between the maximum frequency P1 and the maximum frequency P2 was changed was prepared and used for the test. In the test, the projection material was thrown into the projection test apparatus, and continuous operation and replenishment were repeated to form an operating mix, and then the projection test was performed.

The particle size distribution of the projection material used for the test is shown below.
(1) The particle diameter of the first group maximum frequency P1 is 0.710 mm (particle diameter section 0.850 mm ≧ d1> 0.710 mm), 0.850 mm (particle diameter section 1.000 mm ≧ d1> 0.850 mm), Three levels of 1.000 mm (particle diameter section 1.180 mm ≧ d1> 1.000 mm) (2) The particle diameter at which the second group maximum frequency P2 is 1.400 mm (particle diameter section 1.700 mm ≧ d2> 1.400 mm) ), 1.180 mm (particle diameter section 1.400 mm ≧ d2> 1.180 mm), 1.000 mm (particle diameter section 1.180 mm ≧ d2> 1.000 mm)

  Table 1 shows the surface roughness measurement results under each condition. Thus, the surface roughness can be adjusted by selecting an appropriate particle size corresponding to the maximum frequencies P1 and P2. For example, in the surface treatment process of the sliding component manufactured by hot forging, the surface roughness Rz can be adjusted to about 50 μm to 60 μm, which is suitable for post-processing.

  Hereinafter, the particle size distribution is shown in a graph. FIG. 5 is an explanatory diagram schematically showing the particle size distribution after the operating mix forming step of the projection material of the present disclosure in comparison with the particle size distribution before the operating mix forming step. In the first group, the particle diameter of the maximum frequency P1 is 0.850 mm, and in the second group, the particle diameter of the maximum frequency P2 is 1.400 mm. “Initial” is the particle size distribution before the operating mix forming step, and “Operating mix” is the particle size distribution after the operating mix forming step. The difference between the maximum frequencies P1, P2 and the frequency V1 after the operating mix formation step is smaller than the difference between the initial maximum frequencies P1, P2 and the frequency V1. Further, the difference between the maximum frequencies P1, P2 and the frequency V2 after the operating mix formation step is smaller than the difference between the initial maximum frequencies P1, P2 and the frequency V1. In this way, the frequency V (V1, V2) between the maximum frequencies P1 and P2 increases relative to the maximum frequencies P1 and P2 without changing the positions of the maximum frequencies P1 and P2. It was confirmed that Referring to Table 1, by using this projection material, the surface roughness can be adjusted to about Rz 54.13 μm.

  FIG. 6 is a particle size distribution before forming an operating mix of the projection material of the example. The horizontal axis is the particle size, and the vertical axis is the weight fraction. The first group has a particle diameter of 1.000 mm, and the second group has a particle diameter of 1.400 mm. n is the test number, and the average is the average value of the test results indicated by the test number. FIG. 7 is a particle size distribution after forming the operating mix of the projection material of FIG. Thus, the position (particle diameter) of the maximum frequencies P1 and P2 does not change, and the frequency V between the maximum frequencies P1 and P2 becomes a characteristic distribution that increases relative to the maximum frequencies P1 and P2. It was confirmed. The maximum frequency P2 in the average after the formation of the operating mix: The maximum frequency P1 is 18:23, which satisfies P2 ≦ P1.

  FIG. 8 is a particle size distribution before forming an operating mix of the projection material of the example. The horizontal axis is the particle size, and the vertical axis is the weight fraction. The first group has a particle diameter of 0.850 mm, and the second group has a particle diameter of 1.000 mm. n is the test number, and the average is the average value of the test results indicated by the test number. FIG. 9 is a particle size distribution after forming the operating mix of the projection material of FIG. Thus, the position (particle diameter) of the maximum frequencies P1 and P2 does not change, and the frequency V between the maximum frequencies P1 and P2 becomes a characteristic distribution that increases relative to the maximum frequencies P1 and P2. It was confirmed. The maximum frequency P2 in the average after the formation of the operating mix: The maximum frequency P1 is 23:24, which satisfies P2 ≦ P1.

Claims (12)

In the cast steel projection material used to remove the scale formed on the surface of the metal product by blasting,
A first material group in which the particle diameter d1 belongs to a first particle diameter section d1max ≧ d1> d1min, and has a maximum frequency P1 in the first particle diameter section;
A projection material group in which the particle diameter d2 belongs to the second particle diameter section d2max ≧ d2> d2min, and the second group having the maximum frequency P2 in the second particle diameter section,
The first group and the second group satisfy the relationship d1max = d2min,
The particle diameter frequency distribution of the projection material comprised by the said 1st group and the said 2nd group is a projection material which is substantially continuous.   The projection material according to claim 1, wherein d1min = 0.710 mm and d2max = 1.700 mm, and d1max is 1.000 mm or 1.180 mm. The metal product is a hot forged product,
The said projection material is a projection material of Claim 1 or 2 whose Vickers hardness is HV300-HV600. The metal product is a sliding part,
The projection material according to claim 3, wherein the maximum frequency P1 is present in a particle diameter section 1.180 mm ≧ d1> 1.000 mm, and the maximum frequency P2 is present in a particle diameter section 1.700 mm ≧ d2> 1.400 mm.   The projection material according to claim 1, wherein d1min = 0.600 mm and d2max = 1.180 mm, and d1max is 1.000 mm or 1.180 mm.   The projection material according to claim 1, wherein d1min = 0.600 mm and d2max = 1.700 mm, and d1max is 1.000 mm or 1.180 mm.   The said projection material is the projection material as described in any one of Claims 1-6 currently formed in the convex curve. It is the surface treatment method of the metal product using the said projection material as described in any one of Claims 1-7,
A projection material loading step of loading an unused projection material into a blasting device;
An operating mix forming step for forming an operating mix in which the particle size distribution of the projection material is stabilized by the operation of the blasting device; and
The projection material is projected onto the metal product by the blasting device to remove the scale on the surface of the metal product, and the surface of the surface of the metal product is roughened or present on the surface of the metal product. A surface treatment process for removing defects;
A surface treatment method for a metal product.   9. The surface treatment method for a metal product according to claim 8, wherein a particle size distribution of the projection material after the operating mix forming step is 0.250 mm to 1.700 mm and has a maximum frequency P <b> 1 and P <b> 2.   The surface treatment method for a metal product according to claim 9, wherein the maximum frequencies P1 and P2 satisfy P2 ≦ P1. Particle size distribution of the projection material after the operating mix formation step,
Compared to unused projectiles
The position of the maximum frequencies P1 and P2 does not change, and the frequency V between the maximum frequencies P1 and P2 increases relatively with respect to the maximum frequencies P1 and P2. The surface treatment method of the metal product of description.   The metal product is a sliding part molded by hot forging. The surface treatment process removes the scale of the surface of the sliding part, and the ten-point average roughness defined in JIS-B0601: 2000. The surface treatment method for a metal product according to any one of claims 8 to 11, wherein Rz is set to 50 µm to 60 µm.

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