JP6139208B2 - Copper alloy sliding member - Google Patents

Description

  The present invention relates to a sliding member.

  For a sliding member having a sliding portion such as a bearing or a brake disk, a copper alloy that hardly damages the counterpart member and has high slidability is often used. As the copper alloy sliding member, a cast product obtained by processing a member obtained by casting as it is, a sintered product obtained by applying pressure to a copper alloy powder produced by an atomizing method, or the like is used. It has been. Specifically, those having a small friction coefficient are suitable, and those having good seizure resistance that are difficult to seize even when used at a high surface pressure are suitable. These performances are collectively called slidability.

  In order to improve these slidability, the improvement of adopting a material having a high lubricating effect has been conventionally made. For example, in Patent Document 1, iron is 0.3 mass% or more and 6.0 mass% or less, tin is 3.0 mass% or more and 16.0 mass% or less, and sulfur is 0.3 mass% or more and 3.0 mass% or less. % Or less, a bronze-based copper alloy containing 0.01 mass% or more and 0.3 mass% or less of phosphorus, and the balance of copper and unavoidable impurities is described as exhibiting high slidability.

Japanese Patent No. 4658269

  However, the seizure resistance, particularly the seizure resistance, is approaching the limit only by improving the lubrication characteristics, and a sliding member having more excellent seizure resistance has been demanded.

  Then, this invention aims at manufacturing the sliding member excellent in the seizure resistance.

  The present invention solves the above problems by using a sliding member having a metal structure obtained by modifying a copper alloy by friction welding or friction stirring on the sliding surface. A copper alloy that has been modified by heating, pressure, or the like by friction welding or friction stirring has a more modified structure than the original material, and has excellent seizure resistance.

  In the case of friction welding, a joined body of a copper alloy used for the sliding surface and a metal material having a higher melting point that presses the copper alloy can be suitably used.

  In addition, when a bronze-based copper alloy is used as a material to be disposed on the sliding surface, it becomes more excellent from the original high slidability. Furthermore, if it contains sulfur and has a component that acts as a solid lubricant with the sulfur compound, it becomes a sliding member with more excellent slidability.

  According to the present invention, a sliding member having excellent seizure resistance can be efficiently produced with high accuracy.

(A) A perspective view showing an example of a copper alloy member and a back metal member used in the first embodiment, (b) a side view of a pressure contact member in which the member of (a) is brought into sliding pressure contact, (c) (b) The perspective view of the cutting member cut out from the press-contact member of (A) A perspective view showing an example of a copper alloy member and a back metal member used in the second embodiment, (b) a side view of a pressure contact member in which the member of (a) is brought into sliding pressure contact, (c) (b) The perspective view of the cut | judging base material cut out from the press-contact member of this, The perspective view of the strip-shaped sliding member cut out from (d) (c) Conceptual diagram of friction stirring according to the third embodiment Front view and plan view of a ring-on-disk friction tester used in the examples The graph which shows the sliding test result of Example 1 The graph which shows the sliding test result of the comparative example 1 The graph which shows the sliding test result of Example 2 The graph which shows the sliding test result of the comparative example 2

  The present invention will be specifically described below. The present invention is a sliding member having a sliding surface made of a copper alloy, and performs a modification that alters the metal structure from the original bronze-based copper alloy at a portion constituting the sliding surface by friction welding or friction stirring. The seizure resistance is improved.

  First, the form which modifies | reforms the metal structure | tissue used as a sliding member by friction welding as 1st embodiment is demonstrated using FIG. As materials, a cylindrical copper alloy member 11 that constitutes a sliding surface and a cylindrical back metal member 12 made of a metal material having a melting point higher than copper, such as a steel-based material, are used. The outer diameter and the inner diameter constituting the annular bottom surface of these members are the same. The back metal member 12 is disposed below and fixed, the copper alloy member 11 is disposed above, and the annular bottom surfaces 11a and 12a are brought into contact with each other while the copper alloy member 11 is rotated around the axis of the annular bottom surface. Apply downward pressure (FIG. 1 (a)). Then, both the copper alloy member 11 and the back metal member 12 are red-hot by frictional heat, but the copper alloy member 11 is softened at a lower temperature, so that a part of the copper alloy member 11 and the back metal member 12 protrude in the outer diameter direction due to downward pressure The vicinity of the lower bottom surface of the copper alloy member 11 is crushed. Overall, this compression gradually reduces the height. After compression to an appropriate level, the rotation of the copper alloy member 11 is stopped and cooling is performed while pressure is applied. A side view at this stage is shown in FIG. The combined pressure contact member 13 has a height smaller than the total height of the copper alloy member 11 and the back metal member 12.

The portions that were originally the copper alloy member 11 and the back metal member 12 in the vicinity of the combined contact surface of the pressure contact member 13 are cut into rings. Among these, the copper alloy member 11 is softened and compressed by high heat and then cooled and solidified, whereby the entire structure near the contact surface is modified from the original structure. However, since this change is less likely to occur as the distance from the contact surface increases, it is desirable to cut the portion that was originally the copper alloy member 11 as close to the contact surface as possible. In addition, it is desirable that the thickness of the portion derived from the copper alloy member 11 is small also in that the overall strength increases as the proportion of the back metal member 12 increases. This is because the copper alloy member 11 is provided in order to improve the slidability of the sliding surface, so that only the surface needs to be covered with the modified material derived from the copper alloy member 11. Specifically, preferably the thickness L ₁ of the segment from the copper alloy member 11 is 5mm or less, and more preferably less than 3mm. However, since it is difficult to cut with less than 1 mm, it is desirable that it be 1 mm or more. On the other hand, the back length L ₂ of the metal member 12 at a portion is not particularly limited, and may be prepared such that the size required when used as a sliding member as a whole. However, if it is too close to the contact surface, the requirement for cutting accuracy becomes severe, so it is preferable that the distance is 2 mm or more.

  Here, it is assumed that it is cut by a dashed line in FIG. A perspective view of the obtained cutting member 14 is shown in FIG. The portion (11b) that protrudes during compression is also removed. The cut surface 11c of the portion (copper alloy layer) that was the copper alloy member 11 becomes the surface of the sliding member. However, since the surface is rough immediately after cutting, the cut surface 11c that becomes the surface of the sliding member is finished as a sliding member by general machining. The cut surface 11c is compressed and deformed during the above-described friction welding, and becomes an excellent material having higher seizure resistance than using the original copper alloy member 11 as a sliding member as it is.

  The modified sliding surface of the sliding member thus obtained is red-hot by frictional heat and pressure is applied during cooling, so that the entire surface is suitably modified and has excellent slidability. It will be a thing.

  Moreover, it is good also as a sliding member which consists only of the part derived from a copper alloy which cut | disconnected or grind | polished and removed the back metal side of the material once joined with the back metal.

  By the way, although the cylindrical material which can be originally used as a sliding member in FIG. 1 was used, after friction welding the larger diameter disk-shaped materials together, the material cut out from there is used as various sliding members. It may be used. A second embodiment in which the cut material is used for a slide bearing will be described with reference to FIG.

  Each of the copper alloy member 21 and the back metal member 22 uses the same material as the copper alloy member 11 and the back metal member 12 described above, and is a member having a columnar shape instead of a cylindrical shape (FIG. 2A )). In the same manner as above, the bottom surfaces are aligned and rotated while applying pressure, and the copper alloy member 21 is partially protruded and the vicinity of the contact surface is compressed and friction welded (FIG. 2B). Similarly, cooling is performed while applying pressure, and the vicinity of the contact surface is cut from the obtained pressure contact member 23 to obtain a disk-shaped cut base material 24 (FIG. 2C). After the surface of the cut base material 24 is processed smoothly, a strip-shaped sliding member 25 is cut out (FIG. 2D). The sliding surface 21d that is one surface of the sliding member 25 is made of a modified copper alloy. When this sliding member 25 is wound one turn so that the sliding surface 21d is positioned on the outer peripheral side or the inner peripheral side and the ends are joined together to produce a slide bearing, the sliding surface is made resistant by modification. Excellent seizure property.

  Next, as a third embodiment, a case where modification is performed by friction stirring will be described. In this embodiment, a copper alloy member 31 having a shape that can be originally used as a sliding member is used. A cylindrical tool 32 made of hot die steel or the like is pressed against this while applying pressure. As shown in FIG. 3A, the tip of the tool 32 is not a flat plate, but a protrusion for facilitating stirring is provided in the center. The portion of the copper alloy member 31 that is in contact with the tool 32 is heated and softened by frictional heat generated by rotation, and the surface structure is stirred. The tool 32 is scanned so that this stirring is caused on the entire surface of the copper alloy member 31. In the portion 33 after the scanning, the tissue is reformed in the process of being temporarily pressurized and stirred and then cooled. Thereby, the material excellent in seizure resistance which improved the whole surface of copper alloy member 31 can be obtained.

  Compared to the friction welding method, the modification by friction stirrer only needs to stir the surface of the original material, so there is no need to go through steps such as cutting the member or removing the protruding portion. A modified sliding surface can be obtained without waste. However, since no pressure is applied during cooling, the reforming effect may be inferior compared to friction welding.

  In any of the embodiments, a bronze-based copper alloy is desirable as a material for the copper alloy member used in the present invention, because it is likely to improve the seizure resistance due to the modification, and the originally high slidability can be further improved. As a specific composition of the bronze-based copper alloy, a general bronze-based copper alloy containing a solid lubricant that reduces the friction coefficient may be used. Here, the solid lubricant is, for example, sulfide (Fe—S compound, molybdenum disulfide, etc.), Pb, Bi, carbon, or the like. By containing a solid lubricant, it is possible to impart further seizure resistance and improve slidability while maintaining a low friction coefficient. As such a material, for example, iron is 0.15 mass% or more and 6.0 mass% or less, tin is 3.0 mass% or more and 16.0 mass% or less, and sulfur is 0.3 mass% or more and 3.0 mass% or less. % Or less, phosphorous is contained in an amount of 0.01% by mass or more and 0.3% by mass or less, and a bronze-based copper alloy in which the balance is made of copper and a residual component is included. The above-mentioned residual component is a component that may be intentionally included to impart a beneficial effect without impairing the beneficial properties of the alloy even though it is a minor component, or an impurity that is inevitably included. Thus, the copper alloy member and the properties after stirring are not included.

  Hereinafter, the example which manufactured the sliding member concerning this invention concretely is shown concretely. First, an example of manufacturing by friction welding will be shown.

Example 1
First, by casting, tin: 9.85% by mass, sulfur: 0.58% by mass, iron: 0.23% by mass, phosphorus: 0.0165% by mass, copper: remaining bronze copper alloy, outer diameter A cylindrical copper alloy member having a diameter of 52 mm, an inner diameter of 24 mm, and a height of 60 mm was produced. This itself can be used as a normal sliding member, and the same one is used as Comparative Example 1 in the test described later. On the other hand, as a back metal member, a member made of steel (S45C material) and having the same shape and size as a cylindrical copper alloy member was manufactured. The contact surfaces where the cylindrical copper alloy member and the back metal member contact each other were contacted after finishing with a No. 2000 grindstone.

These were friction welded with a FF-60IICM-K type friction welding machine manufactured by Nitto Seiki Co., Ltd. Specific conditions are as follows. The back metal member is fixed, and the annular surface of the copper alloy member which has been axially rotated at a rotational speed of 600 rpm is brought into contact with the annular surface, and a pressure of 2.3 kgf / cm ² is applied for 3 seconds to obtain a copper alloy. The member was softened. After the copper alloy member was softened, a pressure of 7.0 kgf / cm ² was applied, and the pressure was continuously applied until it was pushed in 5 mm from the contact position. Next, after stopping the rotation, the copper alloy member was pressed at a pressure of 7.0 kgf / cm ² and further pressed by 1 mm. (6mm from the abutment surface) Although the copper alloy member protruded in the outer diameter direction at the joined portion, the volume was pushed and reduced ({26mm × 26mm-12mm × 12mm} × π × 6mm) It was clear from the visual observation that the tissue was compressed near the contact surface.

  Cut from the bonded contact surface at a 7 mm position on the copper alloy side and a 1 mm position on the back metal side, and cut off the protruding part on the outer diameter side of the bonded member, and machine it with a lathe from the back metal side. Then, the back metal member was removed to expose the copper alloy-derived surface as a sliding surface, and an annular sliding member having the same outer diameter and inner diameter as the member before joining and having a thickness of 5 mm was obtained. A copper alloy side surface mirror finished with a No. 2000 grindstone is referred to as Example 1. This sliding surface is a region less than 1 mm from the original bonding surface, and is a region sufficiently affected by the tissue modification.

(Example 2)
First, tin: 10.15% by mass, lead: 9.61% by mass, nickel: 0.58% by mass, phosphorus: 0.20% by mass, copper: residue, containing lead as a solid lubricant A cylindrical copper alloy member made of a copper alloy and having the same shape as in Example 1 was manufactured. This itself is used as Comparative Example 2 as it is. On the other hand, using the same back metal member as in Example 1, the contact surface was similarly polished, and then friction welding was performed under the same conditions using the same friction welding machine as in Example 1. Similarly, Example 2 was obtained by cutting off the protruding portion by cutting a ring at a position of 7 mm on the copper alloy side and a position of 1 mm on the back metal side from the contact surface.

<Sliding test>
A ring-on-disk friction tester was used as a tester. On the surface of a disk 41 having an outer diameter of 50 mm, an inner diameter of 26 mm, and a thickness of 7 mm obtained by cutting the samples obtained in Examples 1 and 2 (surface polishing) and the samples of Comparative Examples 1 and 2 which are only a part of them A ring 42 (outer diameter 40 mm, inner diameter 30 mm, height 15 mm) of steel (S45C. Hardness: equivalent to Hv700) was brought into contact with the ring, and the ring was rotated at a speed of 333 rpm. The relationship between the ring 42 and the disk 41 is shown in FIG. Adding a load from the ring upper surface 42a side, the contact surface of the ring lower surface 42b, 2.5 kg (surface ^{pressure: 0.45kgf / cm 2), 7.83kg} ( surface pressure 1.42kgf ^/ cm 2), 9.89kg The pressure coefficient was adjusted to (surface pressure 1.80 kgf / cm ² ), and the change in the friction coefficient was measured while increasing stepwise every 30 seconds. The results are shown in FIGS.

  In Example 1 (FIG. 5) in which an alloy containing a sulfide compound as a solid lubricating component was modified by sliding, the load remained stable after increasing the load, and the test was continued until 90 seconds had elapsed. However, there was no significant fluctuation and good results as a sliding material were shown. On the other hand, in Comparative Example 1 (FIG. 6), which is an unmodified material as it is, the sample is removed as the friction coefficient starts to gradually increase after 60 seconds (third stage). Although it did not appear in the graph, the image sticking occurred at the instant of 90 seconds.

  In Example 2 (FIG. 7) in which an alloy containing Pb as a solid lubricating component was modified by sliding, the load remained stable after increasing the load once. There was no fluctuation and good results as a sliding material were shown. On the other hand, in Comparative Example 2 (FIG. 8), which is a sample of an unmodified material as it is, the friction coefficient increased with an increase in load, and burned in at 75 seconds.

  In any of the examples, the surface of the sample was seized, whereas the sample of the modified example exhibited higher slidability and seizure resistance.

11, 21 Copper alloy member 11a, annular bottom surface 11b, protruding portion 11c, cutting surface 12, 22 back metal member 12a, annular bottom surface 13, 23, pressure contact member 14, cutting member 21d surface (sliding surface)
24 Cut base material 25 Sliding member 29 Bearing 31 Copper alloy member 32 Tool 33 Scanned portion 41 Disk 42 Ring 42a Ring upper surface 43b Ring lower surface

Claims (6)

A sliding member having a sliding surface made of a more modified metal structure of copper alloy friction pressure contact.   It consists of at least two layers of a plate-like back metal member and a copper alloy layer joined to the back metal member, and the joining is performed by friction welding the copper alloy member serving as the copper alloy layer to the back metal. The said sliding surface is cut | disconnected in the contact surface vicinity of the members which are the parts reformed in the case of friction welding among the parts which were the said copper alloy members. The sliding member.   The sliding member according to claim 1 or 2, wherein the copper alloy is a bronze-based copper alloy.   The sliding member according to claim 3, wherein the bronze-based copper alloy contains a solid lubricant.   The bronze-based copper alloy is composed of 0.15 mass% or more and 6.0 mass% or less of iron, 3.0 mass% or more and 16.0 mass% or less of tin, and 0.3 mass% or more and 3.0 mass% of sulfur. 5. The sliding member according to claim 4, wherein the sliding member contains 0.01% by mass to 0.3% by mass of phosphorus, and the balance is made of copper and inevitable impurities. 0.15 mass% to 6.0 mass% of iron, 3.0 mass% to 16.0 mass% of tin, 0.3 mass% to 3.0 mass% of sulfur, 0.01% of phosphorus contains more mass% 0.3 mass%, remainder consists of copper and unavoidable impurities, the sliding surface made of modified metal tissue by stirring rubbing friction bronze based copper alloy containing a solid lubricant A sliding member having.

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