JP2008115447A - Sliding member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sliding member which is excellent in wear resistance and seizure resistance, less hostile to a mating material, and has small friction coefficient. <P>SOLUTION: This sliding member comprises: a first member (shift fork) 1 having a first base material 11 and a first sliding layer 12 formed on the first base material 11; and a second member (a hub sleeve) having a second base material 21 and a second sliding layer 22 which is formed on the second base material 21 to slide with the first sliding layer 12. The first sliding layer 12 is a Sn plating layer. The second sliding layer 22 is a diamond-like carbon layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sliding member, and more particularly to a sliding member in which a specific sliding layer is formed on the surface of a substrate. The sliding member of the present invention can be suitably used for, for example, a sliding portion between a claw portion of a shift fork and a groove portion of a hub sleeve in a manual transmission of a vehicle.

  A shift fork in a manual transmission of an automobile is for transmitting an operation of a shift lever to a hub sleeve of a synchronizer. In this shift fork, a claw portion that slides with the groove portion of the hub sleeve is provided at the distal end of the fork portion that bifurcated from the base end portion having the boss portion into which the rod is inserted. The claw portion of such a shift fork slides in contact with the groove portion of the hub sleeve rotating at a high speed with a high surface pressure. For this reason, high wear resistance is required for the sliding surface of the claw portion of the shift fork.

  As a material for the shift fork, steel, cast iron, Al alloy or the like is generally used. However, these materials cannot satisfy the wear resistance required for the sliding surface as they are. For this reason, the sliding surface of the base material made of steel or the like is subjected to hardening treatment such as induction hardening, soft nitriding or gas soft nitriding, hard chrome plating treatment or ceramic dispersion Ni-P plating treatment, Mo Mo or A sprayed layer such as a hypereutectic Al—Si alloy is formed, or polyamide or a fluororesin is coated or impregnated.

  Moreover, what formed the dissimilar metal layer which has the diffusion layer excellent in abrasion resistance in the nail | claw part surface of the shift fork is also known (for example, refer patent document 1).

In the shift fork described in Patent Document 1, an aluminum layer is temporarily formed on the surface of a base material made of an iron-based material, and then subjected to diffusion treatment by high-frequency heating while pressing the surface side of the aluminum layer. A diffusion layer made of Fe-Al intermetallic compound (Fe ₃ Al) is formed at the interface between the aluminum layer and the aluminum layer, and an aluminum layer having a diffusion layer made of Fe ₃ Al having excellent wear resistance is formed on the nail surface. Forming.

In addition, a thermal spray layer made of a hypereutectic Al-Si alloy or Mo is formed on the surface of the base material of the shift fork claw, and a resin coating layer made of polyamide, polyimide, or the like is formed on the thermal spray layer. It is known (see, for example, Patent Document 2).
JP 7-310161 A JP 63-303048 A

  By the way, if the nail | claw part of a shift fork is worn out, the backlash of shift operation will become large and it will become easy to generate | occur | produce shift omission. For this reason, the claw part of the shift fork is required to have high wear resistance as described above. Further, if the groove portion of the hub sleeve, which is the counterpart material, is worn, the same problem is caused. Therefore, the pawl portion of the shift fork is required to have a low opponent attack property. Further, in the shift operation, the frictional force between the claw portion of the shift fork and the groove portion of the hub sleeve becomes the pressing force between the hub and the spline tooth surface of the hub sleeve. Affects the magnitude of the shift operation force, and the smaller the friction coefficient, the smaller the shift operation force and the better the shift feeling.

  Accordingly, the claw portion of the shift fork is required to be comprehensively excellent in various characteristics such as wear resistance, seizure resistance, friction coefficient, and opponent attack.

  However, some of the conventional shift forks described above can be satisfied to a considerable extent in terms of wear resistance alone. However, not only the wear resistance but also the seizure resistance, opponent attack and friction coefficient are comprehensive. In consideration, none of these characteristics can be fully satisfied at the same time.

  The present invention has been made in view of the above circumstances, and it should be solved to provide a sliding member that has excellent wear resistance and at the same time, excellent seizure resistance, low counter attack, and low friction coefficient. It is a technical issue.

  The sliding member of the present invention that solves the above problems includes a first base member, a first member having a first sliding layer formed on the first base member, a second base member, and the second base member. A second member having a second sliding layer formed thereon and sliding with the first sliding layer, wherein the first sliding layer is a Sn plating layer, and the second sliding layer is a diamond-like layer. It is a carbon layer.

  In a preferred aspect of the sliding member of the present invention, the Sn plating layer has a thickness of 3 to 10 μm.

  In a preferred aspect of the sliding member of the present invention, the diamond-like carbon layer has a Vickers hardness of Hv 1000 to 5000.

  In a preferred aspect of the sliding member of the present invention, the diamond-like carbon layer has a surface roughness of 0.5 μmRz or less.

  The sliding member of the present invention is formed on the first base material and the first member having the first sliding layer formed on the first base material, on the second base material and on the second base material. And a second member having a second sliding layer.

  The material of the first base material and the second base material is not particularly limited, and may be an iron-based material or a non-ferrous material. For example, steel plates, steel materials such as carbon steel for machine structures, various alloy steels, hardened steel, cast iron materials such as flake graphite cast iron and spheroidal graphite cast iron, Al alloys, Mg alloys, and the like can be suitably used. The material of the first base material and the material of the second base material may be the same or different.

  In the sliding member of the present invention, the first sliding layer is an Sn plating layer, and the second sliding layer is a diamond-like carbon layer (hereinafter referred to as a DLC layer).

  That is, in this sliding member, the Sn plating layer as the first sliding layer and the DLC layer as the second sliding layer slide. In this sliding member in which the sliding layers of such a combination slide with each other, the wear resistance and seizure resistance are improved in the first member having the first sliding layer, as shown in Examples described later, and Further, the opponent attack property and the friction coefficient are lowered, and the wear resistance of the second member having the second sliding layer is improved.

  The thickness of the Sn plating layer is preferably 3 to 10 μm. When the thickness of the Sn plating layer is less than 3 μm, the wear amount of the first member increases. On the other hand, when the thickness of the Sn plating layer exceeds 10 μm, the treatment layer is formed by performing electrolysis or the like, so that the surface of the Sn plating layer is roughened or peeled off, and the wear amount of the first member also increases. Therefore, the thickness of the Sn plating layer is more preferably 3 to 7 μm, and particularly preferably 4 to 6 μm.

The formation method of this Sn plating layer is not specifically limited, Electroplating, hot dipping, vacuum plating (evaporation) etc. can be utilized, for example, bath composition: about 30-50 g / l of stannous sulfate, temperature: By performing electroplating under conditions of about 20 to 30 ° C., current density: about 1.5 to 2.5 A / dm ² , and cell voltage: about 4.5 to 5.5 V, the surface of a predetermined portion of the first base material An Sn plating layer can be formed on the substrate.

  The DLC layer preferably has a Vickers hardness of Hv 1000 to 5000. When the VLC hardness of the DLC layer is less than Hv1000, the amount of wear of the second member increases. On the other hand, when the Vickers hardness of the DLC layer exceeds Hv5000, the wear amount of the first member as the counterpart material increases. Therefore, the Vickers hardness of the DLC layer is more preferably Hv 2000 to 4000, and particularly preferably Hv 2000 to 3000.

  The DLC layer preferably has a surface roughness of 0.5 μm Rz or less. When the surface roughness of the DLC layer exceeds 0.5 μm Rz, the wear amount of the first member as the counterpart material increases. From the viewpoint of further reducing the wear amount of the first member as the counterpart material, the surface roughness of the DLC layer is more preferably 0.3 μmRz or less, and particularly preferably 0.1 μmRz or less.

  The thickness of the DLC layer is preferably 1 to 5 μm. When the thickness of the DLC layer is less than 1 μm, the wear amount of the second member increases. On the other hand, if the thickness of the DLC layer exceeds 5 μm, cracks may occur on the surface. Therefore, the thickness of the DLC layer is more preferably 1 to 3 μm, and particularly preferably 2 to 3 μm.

  Further, from the viewpoint of improving the adhesion of the DLC layer to the second base material, it is preferable to first form an intermediate layer on the surface of the second base material and then form the DLC layer on the intermediate layer. The type of the intermediate layer is not particularly limited as long as it can improve the adhesion of the DLC layer, and Cr, Ti, W, or the like can be adopted. The thickness of the intermediate layer can be about 0.5 to 1 μm.

  The method for forming the DLC layer is not particularly limited, and a sputtering method, a CVD method, an ion plating method, or the like can be employed.

  Such a sliding member of the present invention can be suitably used for, for example, a sliding portion between a claw portion of a shift fork and a groove portion of a hub sleeve in a vehicle manual transmission. That is, if the first member having the Sn plating layer as the first sliding layer is applied to the claw portion of the shift fork and the second member having the DLC layer as the second sliding layer is applied to the groove portion of the hub sleeve In the claw portion having the Sn plating layer, the wear resistance and seizure resistance are improved, the aggression and the friction coefficient are lowered, and the wear resistance in the groove portion having the DLC layer is improved.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

(Example 1)
The sliding member of this embodiment shown in FIG. 1 has a shift fork 1 as a first member having a claw portion 1a, and a groove 2a in which the claw portion 1a engages and slides as a second member. Hub sleeve 2.

  The shift fork 1 includes a first base material 11 and a first sliding layer 12 formed on the surface of the first base material 11 at a portion corresponding to the claw portion 1 a of the shift fork 1.

  The 1st base material 11 consists of hardened steel which carburized and hardened chromium steel (SCr420).

The first sliding layer 12 is made of a Sn plating layer formed by electroplating. This electroplating was performed under the conditions of bath composition: stannous sulfate (40 g / l, temperature: 20 ° C., current density: 1.5 A / dm ² , cell voltage: 5 V. Thereby, the thickness was 5 μm. A first sliding layer 12 made of an Sn plating layer was formed on the surface of the claw portion 1 a of the first base material 11.

  The hub sleeve 2 is formed on the surface of the second base material 21 and the surface of the second base material 21 corresponding to the groove 2a of the hub sleeve 2, and the surface of the intermediate metal layer 23. And a second sliding layer 22.

  The 2nd base material 21 consists of hardened steel which carburized and hardened chromium molybdenum steel (SCM420).

The 2nd sliding layer 22 consists of a DLC layer formed by sputtering method. In this sputtering method, the substrate temperature was 200 ° C., the negative bias voltage applied to the substrate was 100 V, and Ar (argon) gas and CH ₄ (methane) gas were used. As a result, a second sliding layer 22 made of a DLC layer having a thickness of 2 μm, a Vickers hardness of Hv 3000, and a surface roughness of 0.5 μm Rz was formed on the surface of the groove 2 a of the second base material 21.

  In this embodiment, in order to improve the adhesion of the second sliding layer 22 to the second base material 21, an intermediate metal layer 23 is first formed on the surface of the second base material 21 by a sputtering method. A second sliding layer 22 was formed on the metal layer 23. The intermediate metal layer 23 is made of Cr and has a thickness of 0.5 μm.

  In addition, the surface roughness of the second base material 21 was 0.5 μm Rz in a base state before the intermediate metal layer 23 was formed.

  Thus, in the first embodiment, as shown in Table 1, the Sn plating layer as the first sliding layer 12 is formed on the surface of the claw portion 1a of the shift fork 1, and the surface of the groove portion 2a of the hub sleeve 2 is formed. In addition, a DLC layer as the second sliding layer 22 is formed.

(Comparative Example 1)
The first embodiment is the same as the first embodiment except that the first sliding layer 12 is not formed on the surface of the first base material 11 corresponding to the claw portion 1a of the shift fork 1.

  That is, in this comparative example 1, as shown in Table 1, the claw portion 1a of the shift fork 1 is made of carburized hardened steel of SCr420, which is the material of the first base material 11, and the groove portion of the hub sleeve 2 A DLC layer as the second sliding layer 22 is formed on the surface 2a.

(Comparative Example 2)
Except for forming a hard chromium plating layer instead of forming the Sn plating layer as the first sliding layer 12 on the surface of the first base material 11 corresponding to the claw portion 1a of the shift fork 1, Similar to Example 1.

  That is, in this comparative example 2, as shown in Table 1, a hard chrome plating layer is formed on the surface of the claw portion 1a of the shift fork 1, and the second sliding layer 22 is formed on the surface of the groove portion 2a of the hub sleeve 2. The DLC layer is formed.

(Comparative Example 3)
The same as Example 1 except that the intermediate metal layer 23 and the second sliding layer 22 are not formed on the surface of the groove 2a of the hub sleeve 2.

  That is, in this comparative example 3, as shown in Table 1, the Sn plating layer as the first sliding layer 12 is formed on the surface of the claw portion 1a of the shift fork 1, and the groove portion of the hub sleeve 2 is 2 It is made of carburized and quenched steel of SCM420, which is a material of the base material 21.

(Comparative Example 4)
The first sliding layer 12 is not formed on the surface of the first base material 11 corresponding to the claw portion 1a of the shift fork 1, and the intermediate metal layer 23 and the second sliding layer are formed on the surface of the groove 2a of the hub sleeve 2. The same as Example 1 except that the layer 22 is not formed.

  That is, in Comparative Example 4, as shown in Table 1, the claw portion 1a of the shift fork 1 is made of carburized and hardened steel of SCr420, which is the material of the first base material 11, and the groove portion of the hub sleeve 2 Is made of carburized and hardened steel of SCM420, which is the material of the second base material 21.

(Comparative Example 5)
Instead of forming the Sn plating layer as the first sliding layer 12 on the surface of the first base material 11 corresponding to the claw portion 1a of the shift fork 1, a hard chrome plating layer is formed, and the hub sleeve 2 is formed. This example is the same as Example 1 except that the intermediate metal layer 23 and the second sliding layer 22 are not formed on the surface of the groove 2a.

  That is, in this comparative example 5, as shown in Table 1, a hard chromium plating layer is formed on the surface of the claw portion 1a of the shift fork 1, and the groove portion of the hub sleeve 2 is made of the material of the second base material 21. It consists of a carburized and hardened steel of SCM420.

(Evaluation of wear resistance, seizure resistance, opponent attack and friction coefficient)
About the sliding member which concerns on the said Example 1 and Comparative Examples 1-5, abrasion resistance, seizure resistance, opponent attack property, and a friction coefficient were evaluated.

  That is, while producing a cylindrical test piece using each nail | claw part material shown in Table 1, the flat plate test piece was produced using each groove part material similarly shown in Table 1.

  The cylindrical test piece has an inner diameter of 20 mmφ, an outer diameter of 25.6 mmφ, a height of 17 mm, and a surface roughness of 1.6 μmRz. The flat test piece has a size of 30 × 30 × 5 mm and a surface roughness of 0.5 μm Rz.

  Using these cylindrical test pieces and flat plate test pieces, a seizure test is performed to determine the seizure limit, and a wear test (actual wear test) is performed under mild conditions that do not cause seizure in actual use of the shift fork and hub sleeve. Went.

  Here, the seizure test was performed for 2 minutes under the condition of splash lubrication with a lubricating oil (trade name “ATF Dexron II”) at 8600 rpm (9.6 m / sec) using a mechanical laboratory type frictional wear tester. Each time, the load was increased by 250 N, and the load when the friction coefficient became 0.2 or more or when the wear became extremely large was defined as the seizure load (N).

  In addition, the actual machine wear test was performed after being installed in an actual transmission, filled with lubricating oil, operated for 1 second under conditions of a hub sleeve rotation speed of 4800 rpm, an oil temperature of 120 °, and a shift fork operating load of 100 kg. 30,000 cycles of resting for 5 seconds were carried out, and the amount of wear of the shift fork and hub sleeve was examined.

  The results of seizure load and friction coefficient in these seizure tests are shown together in Table 1 above, and the amount of wear in the actual machine wear test is shown in FIG.

  As shown in Table 1 and FIG. 2, in this embodiment, the seizure load is remarkably large as 3750 N, the seizure resistance is excellent, the friction coefficient is as small as 0.018, and the shift fork claw portion and the hub sleeve groove portion are provided. Both wears were small.

(Relationship between surface roughness of DLC layer and friction and wear characteristics)
Next, in order to investigate the influence of the surface roughness of the DLC layer as the second sliding layer 22, as shown in Table 2, a flat plate test piece and an actual machine hub sleeve having different surface roughness were manufactured, The seizure test and the actual machine wear test were performed in the same manner.

  Since the surface roughness of the DLC layer as the second sliding layer 22 is greatly affected by the surface roughness of the substrate (second base material 21) before coating the DLC layer, the surface roughness of the substrate is changed. The surface roughness of the DLC layer was changed variously.

  The results of seizure load and friction coefficient are shown in Table 2, and the amount of wear in the actual machine wear test is shown in FIG.

  From Table 2 and FIG. 3, when the surface roughness of the DLC layer as the second sliding layer 22 is 0.5 μmRz or less, the seizure load is as large as 3750 N or more, the seizure resistance is excellent, and the friction coefficient is 0. The amount of wear was small at 018 or less, and both the shift fork claw and the hub sleeve groove were small.

It is sectional drawing which shows typically the sliding member which concerns on a present Example. It is a figure which shows the result of having investigated the abrasion amount by the actual machine abrasion test about the sliding member which concerns on Example 1 and Comparative Examples 1-5. It is a figure which shows the result of having investigated the abrasion amount by the actual machine abrasion test, in order to investigate the influence of the surface roughness of a DLC layer about the sliding member of Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Shift fork (1st member) 1a ... Claw part 2 ... Hub sleeve (2nd member) 2a ... Groove part 11 ... 1st base material 12 ... 1st sliding layer 21 ... 2nd base material 22 ... 2nd sliding layer

Claims (4)

A first member having a first base material and a first sliding layer formed on the first base material; and a second base material and sliding on the first sliding layer formed on the second base material. And a second member having a second sliding layer.
The sliding member, wherein the first sliding layer is a Sn plating layer, and the second sliding layer is a diamond-like carbon layer.   The sliding member according to claim 1, wherein the Sn plating layer has a thickness of 3 to 10 μm.   The sliding member according to claim 1 or 2, wherein the diamond-like carbon layer has a Vickers hardness of Hv1000 to 5000.   4. The sliding member according to claim 1, wherein the diamond-like carbon layer has a surface roughness of 0.5 μm Rz or less.

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