JP4848821B2 - Sliding member - Google Patents

Description

  The present invention relates to a sliding member having a predetermined shape that can be used for an engine block, a hydraulic pump, a compressor component, a bearing, or the like whose partial surface is a sliding surface.

  Generally, sliding members are indispensable for various machines that perform reciprocation, rotational movement, and the like. For example, various sliding members are used for engines and compressors.

  Generally, on the sliding surface, it is desirable that the sliding surface is a mirror surface in order to reduce the amount of wear due to friction. However, if the sliding surface is a mirror surface, the frictional resistance can be kept low when the mirror-finished metals are rubbed together via oil, but a certain amount of heat is generated, and there is a risk of seizure. For this reason, a sliding surface having an appropriate surface roughness is required for each application.

  In general, the sliding surface is supplied with an appropriate lubricant to reduce frictional force, wear or other forms of surface damage. In order to ensure a sufficient oil film thickness, the sliding surface needs to hold an appropriate amount of lubricant. In order to hold an appropriate amount of lubricant, for example, a method has been used for a long time, for example, by attaching a cross-shaped streak called a cross hatch on the sliding surface and retaining the lubricant in the streak.

  Patent Document 1 discloses that the porosity of the surface portion from the surface of the sliding surface made of 5-50% by weight of TiCN and the rest of the iron-based alloy to 1 mm depth is 7-20% by volume, and the internal voids. An iron-based sliding material with a reduced rate is described. It is disclosed that when the iron-based sliding material described in Patent Document 1 is used in a condition in which lubricating oil exists, the lubricating oil is impregnated into the pores in the surface portion and frictional wear can be significantly improved.

  Patent Document 2 discloses that a sintered alloy contains Ca, Sr, Ba oxides, carbides, sulfides and their mutual solid solution or at least one dispersed phase in carbon, and 4a and 5a in the periodic table. , 6a group metal carbides and nitrides, and iron-based firing comprising at least one hard phase among these solid solutions and a binder phase composed of an alloy containing the remaining ferrite, austenite, martensite or Fe as a main component. It describes an iron-based sintered alloy in which the dispersed phase is removed from the surface portion of the bond gold to form fine pores. The iron-based sintered alloy described in Patent Document 2 discloses that a fine material formed in a surface portion can be impregnated with a lubricating material and reduce a friction coefficient.

Patent Document 3 discloses that shot peening is performed on a sliding surface of a sliding member (material: carbon steel, chromium steel, chromium molybdenum steel) using a shot having a particle size of 0.6 to 1.0 mm. It is disclosed that the surface form of the sliding surface is changed so as to reduce the friction coefficient at the initial stage of sliding (so that the tip of the surface shape after the shot becomes a rounded convex shape). It is disclosed that the frictional heat generation can be suppressed and the deterioration of the lubricating grease can be suppressed by reducing the friction coefficient at the initial stage of sliding.
Japanese Patent Publication No. 63-1383 JP-A-6-279959 JP-A-9-268319

  However, it is well known that the above-described method of applying a streak to the sliding surface causes the streak to gradually wear during use, resulting in a decrease in the retention of the lubricant. In addition, in the case of the above-mentioned Patent Document 1, it is difficult to control the amount and size of the pores in the press molding or firing process, and the production control that the size of the obtained pores and the variation in the porosity are large. There is a quality control problem. Moreover, in the case of the said patent document 2, the alloy containing the above special substances is used.

  In addition, Patent Document 3 is a shot peening treatment for suppressing frictional heat generation and suppressing deterioration of lubricating grease, and is not intended for retaining a lubricant.

  Accordingly, there is a need for a sliding member having a sliding surface capable of holding an appropriate amount of lubricant that solves the above problems.

  The present invention has been made in view of such circumstances, and has a fine hole on the sliding surface, and the fine hole forms an oil reservoir, thereby effectively reducing the friction coefficient on the sliding surface. It aims at providing the sliding member which can be reduced.

  Therefore, the present inventors have intensively studied to solve this problem, and as a result of repeated trial and error, in a sliding member having a structure in which an iron-based porous material is cast with an aluminum alloy, shot blasting is performed on the sliding surface. By performing the treatment, it was discovered that a concave portion can be formed only in the aluminum alloy portion of the sliding surface, and the present invention has been completed.

That is, the sliding member of the present invention is a sliding member having a predetermined shape and a part of the surface of which is a sliding surface, an iron-based porous material, and an aluminum alloy cast with the iron-based porous material The sliding surface is present in the surface of the iron-based porous material and in the pores of the iron-based porous material, and has been subjected to shot blasting to form a recess on the surface. and the surface of the aluminum alloy, Tona is, shotblasting conditions,
Shot grain material: Zinc
Shot grain size: 200 μm or more and 800 μm or less
Air pressure: 0.1 MPa or more and 0.3 MPa or less
Injection distance: 50mm or more and 150mm or less
Projection time: 5 seconds or more and 45 seconds or less
It is characterized by being.

  The sliding member of the present invention is preferably a cylinder bore.

  Since the sliding member of the present invention has a configuration in which an iron-based porous material is cast into an aluminum alloy, the sliding member has higher strength than an aluminum alloy alone. Moreover, since an iron-type porous material is porous, it can ensure adhesiveness with an aluminum alloy.

  The aluminum alloy has a lower hardness than the iron-based porous material. Therefore, when shot blasting is performed on the sliding surface of the sliding member, the concave portion can be selectively formed only in the aluminum alloy.

  The amount of the recess, the hole diameter, and the like are controlled by controlling the shot blasting conditions. Therefore, the concave portion can be an oil reservoir for the lubricant or the like when a lubricant or the like is used.

  Therefore, the sliding member of the present invention can have a recess only in the aluminum alloy part of the sliding surface, and the entire sliding surface is not damaged, and the lubricant is properly used when using the lubricant. The amount can be maintained, so that it can have a low coefficient of friction.

  Therefore, the sliding member of the present invention can have good sliding characteristics.

  In addition, by applying the sliding member of the present invention to the cylinder bore, good sliding characteristics can be obtained without changing the dimensional accuracy of the sliding surface in the cylinder bore with severe dimensional accuracy.

  The sliding member of the present invention is a sliding member having a predetermined shape and a part of the surface of which is a sliding surface, and has a structure in which an iron-based porous material is casted with an aluminum alloy.

  Moreover, the said sliding member has a recessed part selectively only in the aluminum alloy part of a sliding surface. The recess is formed by subjecting the sliding surface to shot blasting.

  The sliding member in the present invention has a predetermined shape. The predetermined shape is not particularly limited, and is adapted to the use as a sliding member. For example, the sliding member of the present invention can be used for an engine block, a hydraulic pump, a compressor component, a bearing, or the like whose partial surface is a sliding surface.

  The iron-based porous material in the present invention is not limited in material and shape as long as it is an iron-based porous material. The porous material is more preferably a porous material formed by sintering.

  For example, the material of the iron-based porous material may include Cr, Mo, Si, V, W, Cu, C, Mn, P, S, and Ni.

  The shape of the iron-based porous material may be, for example, a cylindrical shape, a ring shape, a plate shape, or a disk shape.

  The iron-based porous material desirably has a porosity of 12% to 50%. If it is a porous material with the porosity of this range, it will become a sliding member with favorable adhesiveness and intensity | strength with an aluminum alloy.

  The iron-based porous material may be used for the entire sliding member or may be used for a part of the periphery of the sliding surface.

  The aluminum alloy in the present invention can contain Cu, Si, Mg, Zn, Fe, Mn, Ni, Sn, and Ti.

  For example, JIS standard A2000 series and ADC12, AC8A, AC4C, AC2B etc. are mentioned as an aluminum alloy.

  The sliding member of the present invention has a configuration in which the iron-based porous material is cast with the aluminum alloy. A manufacturing method is a normal casting method, and there is no limitation in particular.

  For example, in a predetermined shape according to the purpose, placed in a mold of a predetermined shape so that the iron-based porous material is located on the sliding surface, the aluminum alloy is impregnated and cast at a predetermined pressure and a predetermined temperature, An iron-based porous material is cast and the aluminum alloy is impregnated into the pores of the porous material.

  Then, it cools at predetermined temperature and takes out a sliding member from a type | mold.

  Next, the sliding surface of the sliding member taken out from the mold is mirror finished with a honing machine. By applying the mirror finish, the sliding surface becomes a surface on which both the iron-based porous sintered body surface and the aluminum alloy surface exist. Further, the mirror surface is processed, so that the sliding surface becomes a surface having a low coefficient of friction.

  Next, a shot blasting process is performed on the sliding surface subjected to the mirror finish under the following conditions.

  Shot grain material: Zinc, Shot grain size: 200 μm or more and 800 μm or less, Air pressure: 0.1 MPa or more and 0.3 MPa or less, Injection distance: 50 mm or more and 150 mm or less, Projection time: 5 seconds or more and 45 seconds or less.

  The said conditions are conditions which can form a recessed part only in the surface of an aluminum alloy, without damaging an iron-type porous material.

  The formed recess has a depth from the surface of 0.1 μm to 5 μm, and the diameter of the recess is 5 μm to 100 μm.

  The recess formed in this way can become an oil reservoir for a lubricant or the like when a lubricant or the like is used.

  For this reason, the sliding member can hold a proper amount of the lubricant when using the lubricant without causing any new scratches on the surface, and thus can have a low coefficient of friction and good sliding characteristics. I can do it.

  Further, since the shot blasting process can be partially performed on the necessary surface, the process can be easily performed at a lower cost than the electrolytic corrosion process conventionally performed.

  Below, the manufacturing method of the test example of the sliding member of this invention is demonstrated using FIG.

  FIG. 1 is a partial explanatory view (cross-sectional view) of a method for manufacturing a sliding member according to a test example of the present invention.

  A cylindrical iron-based porous sintered body 1 having a porosity of 18%, which is an iron-based porous material, was prepared. Pure iron (KIP440B) was used as the material of the iron-based porous sintered body 1. The iron-based porous sintered body 1 has a cylindrical shape with a diameter of 86 mm, a height of 160 mm, and a cylinder with a thickness of 5 mm.

  As shown in FIG. 1, the iron-based porous sintered body 1 was placed on a die 2 of a cylinder block so that the iron-based porous sintered body 1 faces a sliding surface. The mold 2 is a cylinder block mold and has a cylindrical shape as shown in FIG.

  An aluminum alloy (ADC12) was poured into the mold 2 from the outer peripheral surface side and the bottom surface of the iron-based porous sintered body 1. The casting conditions at this time were a molten metal temperature of 680 ° C., a mold temperature of 250 ° C., preheating of the iron-based porous sintered body 1 at 800 ° C., and a molten metal pressure of 83 MPa.

  In this way, the molten aluminum alloy was impregnated from the outer peripheral surface side and the bottom surface of the iron-based porous sintered body 1 into the interior. The sliding inner peripheral surface of the cylinder bore 3 thus obtained was mirror-finished with a honing machine.

  Using the cylinder bore 3 manufactured as described above, shot blasting was performed under various conditions, and the surface was observed.

  The shot blasting process was performed using the shot blasting device 4 on the inner surface of the cylinder, which is the sliding surface of the cylinder bore 3, as shown in the lower diagram of FIG. The shot blasting device used was made by Shinto Brater.

  Table 1 shows the shot blasting conditions implemented. FIG. 2 shows the SEM observation result of the sliding inner peripheral surface of some cylinder bores subjected to the shot blasting process under the conditions shown in Table 1.

  The surface roughness of each sample performed under each shot blasting condition was measured with a contact-type surface roughness meter and listed in the column of Rz (μm) in Table 1. In addition, description No. described in Table 1 Corresponds to the numbers in the SEM picture of FIG.

  No. in Table 1 and FIG. No. 1 (description No. 0) (hereinafter, No. will be described using the description No.) is a mirror-finished machining with a honing machine and no shot blasting is performed. Description No. in FIG. As can be seen in the 0 SEM photograph, honing-processed cross-hatch streaks were observed on the surface of the sample, but no depressions that should be seen black on the SEM photograph were observed.

  When the sliding inner peripheral surface of the mirror-finished cylinder bore was observed, a surface in which the aluminum alloy entered the void portion of the iron-based porous sintered body was observed. Therefore, both the iron-based porous sintered body surface and the aluminum alloy surface existed on the surface.

  Description No. in FIG. 1 represents a surface SEM photograph of shot particles subjected to shot blasting under the conditions described in Table 1 with shot particles made of alumina (manufactured by Shinto Brater Co., Ltd., product number AF80 particle size: about 200 μm).

  Since alumina is harder than iron and aluminum alloys, the description No. 1 in FIG. As can be seen from FIG. 1, it is observed that both the aluminum alloy and the iron-based porous sintered material are entirely scraped by alumina particles, and the surface is largely uneven. As can be seen from Table 1, the surface roughness (Rz) is as large as 16.9 μm.

  Description No. in FIG. 2-2 represents a surface SEM photograph of shot particles subjected to shot blasting under the shot conditions described in Table 1 with shot particles made of iron (manufactured by Shinto Blator, product number SB-3, particle size: about 300 μm).

  Since shot particles of iron are used, the surface of both the aluminum alloy and the iron-based porous sintered material is scraped as a whole by shot blasting, and as shown in Table 1, the surface roughness Rz is 8.8 μm or more. became.

  Although the surface roughness is a large value, the description No. in FIG. As seen in 2-2, there are few fine recesses on the surface.

  Description No. in FIG. 2-4 represents a surface SEM photograph of shot particles subjected to shot blasting under the shot conditions shown in Table 1 with shot particles made of zinc (manufactured by Shinto Brater Co., Ltd., product number AD-4, particle size of about 400 μm).

  As shown in Table 1, the surface roughness is less than 5 μm. As seen in 2-4, it was observed that there were many fine recesses on the surface. Various shapes of the recesses can be seen, but when they are approximately circular, recesses having a diameter of about 2 μm to 20 μm were observed.

  Since the zinc shot particles are harder than the aluminum alloy and softer than the iron-based porous sintered material, the aluminum alloy portion can be selectively cut without damaging the iron, so the surface roughness (Rz) is not increased so much. It is thought that many fine recesses could be formed.

  A sliding experiment was performed using each cylinder bore sample prepared under the above conditions.

In the sliding experiment, a piston ring (nitrided SUS) is used as the material to be slid, and using a reciprocating sliding tester, stroke / speed: 40 mm · 500 cpm, load: 3 kgf, maximum surface pressure Hertz stress: 20 kgf / mm ² A sliding test was performed under the condition of a test temperature of 70 ° C., and a friction coefficient before baking and a baking time (minute) were measured. As the lubricating oil, E / G oil for CC class diesel, application: 0.13 mg / cm ² was used.

  Table 2 shows the friction coefficient and seizure time of each sample before seizure. FIG. 3 shows a graph comparing the surface roughness (Rz) and the seizing time (minutes), and FIG. 4 shows a graph comparing the surface roughness (Rz) and the friction coefficient before seizure.

  For the sliding test, the sample description No. 0, 1, 3, 2-3, 2-4.

  Description No. which is not shot blasted. The sample No. 0 had a surface roughness (Rz) of 0.7 μm and was burned in a short time of 0.15 minutes in the sliding test. Moreover, the friction coefficient before baking was as high as 0.64.

  Further, description No. in which shot blasting was performed using alumina. Sample No. 1 has a high surface roughness (Rz) of 16.9 μm, and large irregularities were observed in SEM observation. Description No. Sample No. 1 had a seizure time of 29 minutes in the sliding test, and the coefficient of friction before seizure was 0.3.

  On the other hand, description No. in which shot blasting was performed using zinc. Samples 3, 3, 2-3, and 4 have a surface roughness (Rz) of 2 to 5 μm, and many concave portions were observed in SEM observation. Description No. In the samples 3, 2, 3 and 2-4, although the Rz was low, the burn-in time was significantly improved as compared with the other samples. In addition, the coefficient of friction before baking was lower than that of other samples.

  It is considered that the sample using zinc as shot particles was able to retain the lubricating oil because the recesses became an oil reservoir due to the presence of many recesses on the surface. Therefore, it is considered that the friction coefficient can be reduced in the sliding test, and the seizing time can be increased.

  As described above, the sliding member can retain an appropriate amount of lubricant and the like by forming the oil reservoir in the sliding surface, and has a low coefficient of friction without newly scratching the surface. It is possible to provide a sliding member that can utilize the lubricating effect of oil.

The partial explanatory drawing (sectional drawing) of the manufacturing method of the test example of the sliding member of this invention is represented. The SEM observation result of the internal peripheral surface of the sliding member of the test example of this invention is represented. The graph which compared surface roughness (Rz) and image sticking time (minutes) is shown. The graph which compared surface roughness (Rz) and the friction coefficient before image sticking is shown.

Explanation of symbols

1. Iron-based porous sintered body, 2, mold, 3, cylinder bore, 4-shot blasting device.

Claims (2)

A sliding member having a predetermined shape and partially having a sliding surface,
It is composed of an iron-based porous material and an aluminum alloy in which the iron-based porous material is cast,
The sliding surface is the surface of the iron-based porous material, the surface of the aluminum alloy that is present in the pores of the iron-based porous material and has been subjected to shot blasting to form a recess on the surface,
Tona is,
The shot blasting conditions are:
Shot grain material: Zinc
Shot grain size: 200 μm or more and 800 μm or less
Air pressure: 0.1 MPa or more and 0.3 MPa or less
Injection distance: 50mm or more and 150mm or less
Projection time: 5 seconds or more and 45 seconds or less
Sliding member, characterized in that it. The sliding member according to claim 1, wherein the sliding member is a cylinder bore.

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