JP2016196922A - Method for manufacturing slide member and slide member manufactured by the manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a slide member that can reduce generation of stick slip and has excellent durability at low cost, and to provide a slide member manufactured by the manufacturing method.SOLUTION: In the manufacturing method of a slide member, the slide member 11 is formed by coating an external surface of a substrate 26 with a coat 18 having a coefficient of friction that is lower than that of the external surface of the substrate 26. The slide member 11 is a spline shaft and the external surface of the substrate 26 does not have a sharp part.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a manufacturing method of a sliding member such as a propeller shaft and the sliding member manufactured by the manufacturing method.

  Usually, a sliding member such as a propeller shaft is required to slide smoothly. However, stick-slip is known as a phenomenon that hinders smooth sliding of the sliding member. Stick-slip is self-excited vibration caused by microscopic adhesion between the friction surfaces and repeated sliding. This self-excited vibration occurs when the damping due to friction of the mechanical vibration system has a negative characteristic, and it occurs when the friction coefficient decreases as the sliding speed increases or when discontinuous friction changes from static friction to dynamic friction. Occurs when a drop occurs.

  In order to suppress the occurrence of such stick-slip, Patent Documents 1 and 2 disclose that the sliding surface of the propeller shaft is subjected to a solid lubricating film of electroless NiP plating or resin coating to reduce the friction coefficient. Is described.

No. 2014-190370 2013-189568 gazette

  In the technique of Patent Document 1, the occurrence of stick-slip can be suppressed by coating electroless NiP plating. However, the cost is high. Further, the resin-coated solid lubricant film described in Patent Document 2 is less expensive than electroless NiP plating. However, compared with electroless NiP plating, the strength (hardness) is poor, and there is a problem in wear resistance.

  The present invention has been made in view of the above problems, and provides a manufacturing method of a sliding member that can reduce the occurrence of stick-slip, is low in cost, and has excellent durability, and a sliding member manufactured by the manufacturing method. For the purpose.

  In order to solve the above-mentioned problem, in the manufacturing method of the sliding member according to claim 1, wherein the outer surface of the base material is formed by coating a coating having a lower coefficient of friction than the outer surface of the base material, , A spline shaft, and the outer surface of the substrate does not have a sharp portion.

  Thus, there are no sharp parts on the outer surface of the substrate. For this reason, when a film is formed on the outer surface of the substrate, it is possible to suppress the occurrence of excessive stress on the film due to the sharp part, so the surface pressure on the film during sliding decreases, Abrasion resistance of the film is improved. Therefore, even if an inexpensive film is used, it is possible to provide a low-cost sliding member that has excellent durability and can reduce the occurrence of stick-slip.

  In order to solve the above-mentioned problem, the sliding member according to claim 9 is a spline shaft, and is formed by coating the outer surface of the base material with a film having a lower friction coefficient than the outer surface of the base material. The outer surface of the material does not have a sharp portion. Thereby, the sliding member similar to claim 1 can be provided.

It is an axial sectional view showing the configuration of the sliding spline shaft of the embodiment. It is a flowchart of the manufacturing method of a male spline. Partial enlarged sectional view of the surface of the male spline formed on the spline shaft material It is an expanded sectional view showing a part of processing process at the time of spline processing of a male spline. It is an expanded sectional view showing a part of processing process at the time of spline processing of a male spline. FIG. 4 is a partially enlarged cross-sectional view for explaining a male spline after removing a sharp portion from the male spline in FIG. 3. It is a partial expanded sectional view of the male spline containing the membrane | film | coat in embodiment. It is a radial direction partial expanded sectional view of the male spline of the sliding-type spline shaft of embodiment. It is an image figure which shows the magnitude | size of the stress which generate | occur | produces in a film | membrane when forming a film | membrane on the male spline of a prior art. It is an image figure which shows the magnitude | size of the stress which generate | occur | produces in a film | membrane when forming a film | membrane on the male spline of embodiment. It is a flowchart of the manufacturing method of the male spline in a modification. It is a partial expanded sectional view of the male spline containing the membrane | film | coat in a modification.

(1. Overview)
As this embodiment, a sliding spline shaft used for a propeller shaft of an automobile will be described as an example. However, the spline shaft of the present invention can be applied to other propeller shafts having a sliding spline shaft in addition to the propeller shaft of an automobile. Further, the present invention can be applied not only to the propeller shaft but also to other spline shafts engaged with the spline.

  As shown in FIG. 1, the propeller shaft 10 includes a male spline shaft 11 having a male spline 11a and a female spline shaft 21 having a female spline 21a. The male spline shaft 11 corresponds to a sliding member (spline shaft) according to the present invention. The male spline shaft 11 is spline-fitted to the female spline shaft 21, and is provided so as to be relatively slidable in the axial direction. With such a configuration, the male spline shaft 11 and the female spline shaft 21 can transmit rotational torque to each other and rotate relative to each other in the axial direction when rotating around the axis. Although not shown, grease as a lubricant is present at a spline sliding portion between the male spline 11a and the female spline 21a that are engaged with each other.

  The male spline shaft 11 is subjected to a sharp part removing step (S20) described later and coating of a film after the male spline 11a is hobbed by a known hobbing machine on a material (steel material) made of a cylinder. It is formed. An example of the material of the material forming the male spline shaft 11 is S30C. In addition, in this embodiment, although the raw material of the male spline shaft 11 is formed by S30C, if it is steel materials or a metal material, it will not be restricted to this.

  Hereinafter, for convenience of explanation, the material of the male spline shaft 11 is referred to as a material 16, and the male spline formed by hobbing the material 16 is referred to as a male spline 16a. Further, the male spline shaft after the sharp part removal described later is performed on the male spline 16a is defined as a base material 26, and the male spline of the base material 26 is defined as a male spline 26a. Further, the male spline shaft 11 in which the coating 26 is coated on the base material 26 is referred to as a male spline shaft 11. That is, the male spline 16a having the sharp part 16a1, the male spline 26a not having the sharp part 16a1, and the male spline 11a in which the film 18 is coated on the male spline 26a will be described separately.

(2. Details of manufacturing method of male spline shaft 11)
Next, the manufacturing method of the male spline shaft 11 which concerns on this invention is demonstrated based on FIGS. As shown in the flowchart of FIG. 2, the manufacturing method of the male spline shaft 11 includes a hobbing process (S10), a sharp part removing process (S20), and a coating process (S30).

  In the hobbing step (S10), the hobbing machine hobbs the material 16 of the male spline shaft 11 (corresponding to the spline shaft) at a predetermined pitch P as shown in FIG. Is a step of forming a male spline 16a having a sharp portion 16a1 (to be described in detail later). FIG. 3 shows a cross-sectional shape of the side surface of the tooth of the male spline 16 a cut in the axial direction of the material 16.

  As shown in FIGS. 4A and 4B, the hobbing machine rotates a hob 40 having a large number of blades arranged in a spiral shape on a cylindrical outer peripheral surface, and a material 16 on which a male spline 16a is formed, This is a processing device that cuts the material 16 in the tooth trace direction (the axial direction of the material 16) by the blade while feeding the hob blade in the tangential direction of the material 16 (the rotational axis direction of the hob 40).

  As shown in FIG. 3, fine irregularities are formed on the surface of the male spline 16 a by the hob 40. The fine irregularities are formed by cutting the work surface of the material 16 with the blades 410 and 411 of the hob 40. The projections at the apexes of the convex and concave portions with fine irregularities correspond to the sharp portions 16a1 according to the present invention.

  More specifically, in the male spline processing, first, the blade 410 of the hob 40 hits the material 16 and the surface of the material 16 is cut (FIG. 4A). Thereafter, the blank 16 moves (sends) in the axial direction, and the blade 411 of the next hob 40 hits a position slightly shifted from the previous cutting position as shown in FIG. It is cut in the same way. Then, when the blade of the next hob 40 is further displaced, the surface of the material 16 is similarly cut. This cutting is repeated to form the male spline 16a.

  As shown in FIGS. 4A and 4B, the blade tips 410 and 411 of the hob 40 cut the material 16 (contact portions that cut the material 16) draw an arc instead of a straight line. As shown in FIG. 4B, fine irregularities are formed by the arcs drawn by the blades 410 and 411 of the two consecutive hobbs 40. In the male spline 16a, the processing with the hob 40 is repeated, whereby the material 16 having the fine unevenness shown in FIG. 3 having the sharp portion 16a1 is formed.

  The uneven shape on the surface of the male spline 16a can be determined by the processing conditions of the hob 40. Specifically, the distance (pitch P) between the convex tips of the concavo-convex shape can be adjusted by adjusting the feed speed of the material 16 during processing by the hob 40. When the feed speed of the material 16 is increased, the moving distance from FIG. 4A to FIG. 4B becomes longer, and the pitch P becomes larger (wider). As the speed becomes slower, the pitch P becomes smaller (narrower). The pitch P may be set arbitrarily in consideration of ease of removal when the sharp portion 16a1 is removed later in the sharp portion removing step (S20).

  Similarly, the height H (concave depth) of the convex tip (sharp part 16a1) can be adjusted by adjusting the feed rate. When the feed speed of the material 16 is increased, the convex height H is increased (the concave depth is deep), and when it is slowed, the convex height H is decreased (the concave depth is shallow). The convex height H may be arbitrarily set based on the same reason as the pitch P.

  On the other hand, the female spline 21a of the female spline shaft 21 is processed by a broaching machine. Although not shown, the broaching machine cuts and forms the female spline 21 a by pulling out a rod-shaped broach having a blade formed on the outer peripheral surface thereof from the material of the female spline shaft 21.

  Thus, in this embodiment, the processing apparatus which forms the male spline 16a of the raw material 16 used as the basic shape of the male spline 26a of the base material 26 differs from the processing apparatus which forms the female spline 21a. Therefore, the processed cutting surface (tooth surface) state is different. That is, as shown in FIG. 3, the above-described irregularities are formed along the axial direction on the cut surface of the side surface of the male spline 16a. On the other hand, the cutting surface (side surface) of the side surface of the female spline 21a is formed to be flatter than the cutting surface of the male spline 16a.

  The sharp portion removing step (S20) is a step of removing (D) the sharp portion 16a1 of the male spline 16a generated by hobbing to generate the male spline 26a (see FIG. 5) of the base material 26. As a specific method, for example, known shot blasting can be exemplified. That is, a plurality of minute steel balls are sprayed on the sharp part 16a1 to remove the sharp part 16a1. Whether or not the sharp portion 16a1 has been removed may be determined by checking with a magnifier one by one. As another method, a condition for shot blasting that can surely remove the sharp portion 16a1 may be acquired in advance, and shot blasting may be performed based on the condition. The actual shot blasting embodiment is not limited. Any spraying member and method may be used. By this step, the base material 26 after the sharp portion removing step (S20) is in a state where it does not have the sharp portion 16a1 on the outer surface of the male spline 26a.

  The coating step (S30) is a step of coating the outer surface of the base material 26 generated by the sharp part removing step (S20) with a film having a lower friction coefficient than the outer surface of the base material 26. As shown in FIGS. 6 and 7, in the coating step (S <b> 30), the base layer 17 and the film 18 that is a resin coating film are formed on the surface of the male spline 26 a of the base material 26. That is, the foundation layer 17 is formed on the surface of the base material 26 made of a steel material, and the film 18 as the surface layer is formed on the surface of the foundation layer 17. An inexpensive dry film (dry coat) in which a resin is used as a binder and a solid lubricant is blended is applied to the film 18. Thus, the cost can be reduced by applying a dry film instead of an expensive film such as NiP plating.

  The coating 18 of the male spline 26 a is a coating that can slide on the surface of the female spline 21 a of the female spline shaft 21. In the present embodiment, the base layer 17 and the coating 18 are formed on the surface of the male spline 26a and the coating 18 is not formed on the surface of the female spline 21a. However, the coating 18 is also formed on the surface of the female spline 21a. May be formed. In this case, similarly to the male spline 26a, a base layer may be formed on the surface of the female spline 21a, and then the film 18 may be formed.

  The underlayer 17 is formed of a phosphate layer having a thickness in the range of 1 to 5 μm on the surface of the male spline 26a. The underlayer 17 exhibits a function of protecting (corrosion resistance) the male spline 26a (base material 26) made of steel and a function of improving the bondability between the male spline 26a (base material 26) and the coating 18 (resin coating). Any surface treatment layer that can be used is not limited. That is, any surface treatment layer capable of exhibiting the above functions can be replaced with other known surface treatment layers, and examples thereof include a treatment film with a phosphate and a treatment film with a coupling material.

  Specific processing of the underlayer 17 will be described. In order to form the base layer 17, the surface of the male spline 26a of the base material 26 is washed by an alkaline degreasing process, whereby the base layer 17 made of a phosphate such as zinc phosphate or manganese phosphate is formed. The foundation layer 17 improves the adhesion with the film 18.

  Subsequently, the coating film 18 which becomes the surface layer is applied by spraying on the surface of the underlayer 17 in a solution state in the air atmosphere, and then fired in the air atmosphere. In addition, although it demonstrated that baking was implemented in an air atmosphere since it was cheap, you may implement it in nitrogen atmosphere.

  As shown in FIG. 6, the film 18 (resin coating) includes a resin binder 31 made of a mixture of an epoxy resin (EP) and a phenol resin (PF), and a solid lubricant bonded to the resin binder 31. Sulfide 33, polytetrafluoroethylene (PTFE) 34 and polyethylene (PE) 32 are included. These component ratios are as shown in Table 1 below.

In addition, although the mixture of an epoxy resin and a phenol resin is used for the resin binder 31, it may be only an epoxy resin or only a phenol resin. In the solid lubricant, molybdenum disulfide (MoS ₂ ) is described as an example as the disulfide 33. Of course, tungsten disulfide (WS ₂ ) is also applicable as the disulfide. Further, graphite and carbon nanotubes can be applied to the solid lubricant. In the present invention, the carbon nanotube includes fullerene. In this embodiment, the solid lubricant shown in Table 1 is used, but these lubricants may be used alone or in different combinations. Furthermore, the film 18 may appropriately contain other conventionally known additives.

  The film 18 has a thickness in the range of 5 to 100 μm, more preferably in the range of 10 to 40 μm from the viewpoint of adhesion and wear resistance, and more preferably 10 from the viewpoint of production efficiency. The thickness is in the range of ˜30 μm.

  In the present embodiment, the mixing ratio (mass ratio) of the epoxy resin and the phenol resin in the resin binder 31 is not limited as long as it can function as a binder for binding the solid lubricant. It is 25-100 mass% of phenol resins with respect to 100 mass% of resin. A preferable mass ratio is 65-75 mass% of phenol resin with respect to 100 mass% of epoxy resins.

  The specific material, mass ratio, and particle size (average particle size) of the solid lubricant bound to the resin binder 31 are not limited. The polyethylene 32 has an average particle diameter of 1 to 30 μm, and the mass ratio with respect to the entire coating 18 is 5 to 10 mass%. The average particle diameter of the polyethylene 32 is appropriately selected according to the film thickness of the coating 18. The disulfide 33 has an average particle diameter of 1 to 5 μm, and the mass ratio with respect to the entire coating 18 is 10 to 15 mass%. PTFE 34 has an average particle diameter of 1 to 10 μm, and the mass ratio to the entire coating 18 is 10 to 15 mass%. In the present embodiment, the ratio of disulfide 33, PTFE 34, and polyethylene 32 is preferably disulfide (molybdenum disulfide): PTFE: polyethylene = 3.8: 3.8: 2.5. Thus, at least the ratio of polyethylene 32 is the same as or less than that of disulfide 33 and PTFE 34.

  The film 18 can be formed by applying a solution having the composition shown in Table 2 and applying the solution. Examples of the solvent of the solution may include one or more mixed solvents selected from methyl ethyl ketone, toluene, xylene, propylene glycol monomethyl ether acetate, isopropyl alcohol, 1-butanol, methyl isobutyl ketone, phenol, and orthocresol. it can. Thereby, the male spline shaft 11 is formed.

(3. Comparison with conventional technology)
In this embodiment, since the removal process of the sharp part 16a1 is performed by the sharp part removing step (S20), the outer surface of the male spline 26a of the base material 26 does not have the sharp part 16a1. Therefore, the coating 18 is coated on the male spline 26a that does not have the sharp portion 16a1 by the coating process (S30), and the male spline shaft 11 (male spline 11a) is formed. However, the prior art does not have a sharp part removal step after hobbing. For this reason, after the coating of the film 18, the surface of the male spline SP has a cross-sectional shape as shown in FIG. 8 (image diagram).

  In the film 18 in the vicinity of the sharp portion T at this time, the stress generated when sliding with the female spline is a large stress Sb as shown in FIG. 8 (see the range filled in black in FIG. 8). It becomes. For this reason, the film 18 is worn early and has low durability. However, in the present embodiment, as shown in the image diagram of FIG. 9, the coating 18 is coated on the outer surface of the male spline 26 a that does not have the sharp portion 16 a 1 to form the male spline shaft 11. As a result, as shown in FIG. 9, the stress Ss generated in the film 18 when sliding with the female spline 21a is reduced (see the range filled in black in FIG. 9). For this reason, even if it slides between the female splines 21a, the wear resistance is improved by the amount that the stress generated in the coating 18 is smaller than that of the prior art. As described above, the simple method of removing the sharp portion 16a1 from the male spline 16a makes it possible to use the low-cost coating 18 (dry resin coating). Therefore, the male spline shaft is highly reliable at low cost. 11 is obtained.

  In the above-described embodiment, it has been described that the sharp part 16a1 is removed by shot blasting in the sharp part removing step (S20), but the present invention is not limited to this aspect. The sharp portion 16a1 may be removed by cutting with a predetermined processing machine, or may be removed by electric discharge machining. Further, the sharp portion 16a1 may be removed by cold coining. The same effect can be obtained by these.

<Modification>
Next, a modification is demonstrated based on FIG. 10, FIG. In the said embodiment, in order to manufacture the male spline shaft 11, it had a hobbing process (S10) and the sharp part removal process (S20). However, the present invention is not limited to this, and the hobbing process (S10) and the sharp part removing process (S20) may be replaced with the electric discharge machining process (S100). That is, the method for manufacturing the male spline shaft 111 according to the second embodiment includes an electric discharge machining step (S100) and a coating step (S110) as shown in FIG.

  In the electric discharge machining step (S100), as shown in FIG. 11, the base material 126 is formed by forming the male spline 126a on the outer surface of the material of the male spline shaft 111 by electric discharge machining. At this time, a smooth surface F having no sharp portion is simultaneously formed on the outer surface (side surface) of the male spline 126a (see). Thus, since the male spline 126a (base material 126) does not already have a sharp portion at the end of the electric discharge machining step (S100), the sharp portion removing step is unnecessary.

  Next, in the coating step (S110), the coating 18 is coated on the outer surface of the base material 126 generated by the electric discharge machining step (S100) by the same method as the coating step (S30) in the first embodiment. Thereby, the male spline shaft 111 which has the same effect as 1st embodiment is obtained.

(4. Effects of the above embodiment)
According to the embodiment and the modification, in the method for manufacturing a sliding member formed by coating the outer surfaces of the base materials 26 and 126 with the coating 18 having a lower friction coefficient than the outer surfaces of the base materials 26 and 126, sliding is performed. The members are male spline shafts 11 and 111 (spline shafts), and the outer surfaces of the base materials 26 and 126 do not have sharp portions 16a1.

  Thus, there are no sharp portions 16a1 on the outer surfaces of the base materials 26 and 126. For this reason, when the film | membrane 18 is formed on the outer surface of the base materials 26 and 126, it can suppress that an excessive stress generate | occur | produces on the film | membrane 18 by the sharp part 16a1. Thereby, the surface pressure on the film 18 when sliding with the female spline 21a is reduced, and the wear resistance of the film 18 is improved. Therefore, the male spline shafts 11 and 111 (sliding members) that are excellent in durability and can reduce the occurrence of stick slip can be provided.

  Further, according to the above embodiment, the manufacturing method of the male spline shaft 11 (sliding member) is performed by hobbing the material 16 of the male spline shaft 11 (spline shaft) with a predetermined pitch P set in advance. A hobbing step (S10) for forming a male spline 16a (spline) having a sharp portion 16a1 on the outer surface, and a sharp portion removing step (S20) for removing the sharp portion 16a1 generated by the hobbing to generate the base material 26. ) And a coating step (S30) for coating the coating 18 on the outer surface of the substrate 26 generated by the sharp portion removal step (S20). Thereby, it is possible to provide male spline shafts 11 and 111 (sliding members) that are excellent in durability and can reduce the occurrence of stick-slip.

  Moreover, according to the said embodiment, a sharp part removal process (S20) removes the sharp part 16a1 produced | generated on the side surface of the tooth | gear of the male spline 16a (spline). Thus, since the sharp part 16a1 is removed with respect to the sliding part between the male spline 11a and the female spline 21a of the male spline shaft 11, the durability between the male spline 11a and the female spline 21a is improved. In addition, the occurrence of stick-slip can be effectively suppressed.

  Further, according to the above embodiment, the film 18 coated on the male spline 11a is a resin coating film, and the resin coating film is used as a binder, as at least one of an epoxy resin and a phenol resin, and as a solid lubricant. And at least one of molybdenum sulfide and tungsten disulfide, polytetrafluoroethylene (PTFE), and polyethylene. In this way, the coating 18 can be handled at a lower cost than NiP plating. Thereby, the male spline shafts 11 and 111 (sliding members) that are excellent in durability and can reduce the occurrence of stick-slip can be provided at low cost.

  10 ... Propeller shaft 11, 111 ... Male spline shaft (spline shaft), 11a, 16a, 26a, 126a ... Male spline, 16 ... Material, 16a1 ... Sharp part, 17 ...・ Underlayer, 18 ... film, 26,126 ... base material, 31 ... resin binder, 32 ... polyethylene, 33 ... disulfide, 40 ... hob, S10 ... Hobbing process, S20 ... sharp part removing process, S30, S110 ... coating process, S100 ... electric discharge machining process.

Claims (9)

A method for manufacturing a sliding member formed by coating a film having a lower coefficient of friction than the outer surface of the base material on the outer surface of the base material,
The sliding member is a spline shaft,
The said outer surface of the said base material is a manufacturing method of a sliding member which does not have a sharp part. The manufacturing method of the sliding member is:
Hobbing the spline shaft material at a predetermined pitch set in advance to form a spline having the sharp part on the outer surface;
A sharp part removing step of removing the sharp part generated by the hobbing to produce the base material;
A coating step of coating the coating on the outer surface of the substrate generated by the sharp part removal step;
The manufacturing method of the sliding member of Claim 1 provided with these.   The said sharp part removal process is a manufacturing method of the sliding member of Claim 2 which removes the said sharp part by shot blasting.   The said sharp part removal process is a manufacturing method of the sliding member of Claim 2 which removes the said sharp part by cutting.   The said sharp part removal process is a manufacturing method of the sliding member of Claim 2 which removes the said sharp part by electrical discharge machining.   The said sharp part removal process is a manufacturing method of the sliding member of any one of Claims 2-5 which removes the said sharp part produced | generated on the side surface of the tooth | gear of the said spline. The manufacturing method of the sliding member is:
For the material of the spline shaft, an electric discharge machining process for forming the base by forming splines on the outer surface by electric discharge machining, and simultaneously forming the outer surface on a smooth surface without the sharp part,
A coating step of coating the coating on the outer surface of the base material generated by the electric discharge machining step;
The manufacturing method of the sliding member of Claim 1 provided with these. The film to be coated is a resin coating film,
The resin coating film is
As a binder, at least one of an epoxy resin and a phenol resin,
As a solid lubricant, at least one disulfide of molybdenum disulfide and tungsten disulfide, polytetrafluoroethylene (PTFE), and polyethylene,
The manufacturing method of the sliding member of any one of Claims 1-7 containing these. A sliding member formed by coating a film having a lower coefficient of friction than the outer surface of the substrate on the outer surface of the substrate,
The sliding member is a spline shaft,
The said outer surface of the said base material is a sliding member which does not have a sharp part.

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