Piston for vehicle disc brake and manufacturing method thereof
View Patent ↗A piston has a piston main body including an aluminum alloy, and a covering layer formed on the outer surface of the piston main body, and the covering layer has a first plating layer including an iron-phosphorous alloy, and a second plating layer including a nickel-phosphorous alloy formed on the first plating layer.
1. A piston for a vehicle disc brake, the piston being accommodated via a piston seal in a cylinder hole formed in a caliper body of the vehicle disc brake so as to be movable in a disc shaft direction, the piston comprising:
a piston main body made of aluminum alloy; and
a covering layer formed on an outer surface of the piston main body, wherein
the covering layer includes a first plating layer made of iron-phosphorous alloy and a second plating layer made of nickel-phosphorous alloy,
the outer surface of the piston main body having undergone a zincate treatment before the formation of first plating layer of the covering layer thereon, and
the second plating layer being formed on the first plating layer.
2. The piston for a vehicle disc brake according to claim 1 ,
wherein the second plating layer further includes 10 to 30 volume percent of resin particles and the resin particles are made of polytetrafluoroethylene (PTFE).
3. The piston for a vehicle disc brake according to claim 1 ,
wherein the first plating layer has a film thickness of 1 to 15 μm and the second plating layer has a film thickness of 1 to 15 μm.
4. A method for manufacturing a piston for a vehicle disc brake, the piston being accommodated via a piston seal in a cylinder hole formed in a caliper body of the vehicle disc brake so as to be movable in a disc shaft direction, the method comprising the steps of:
forming a first plating layer made of iron-phosphorous alloy on an outer surface of a piston main body made of aluminum alloy using electrolytic plating, the outer surface having undergone zincate treatment; and
forming a second plating layer made of nickel-phosphorous alloy on a surface of the first plating layer using electroless plating.
5. The method for manufacturing a piston for a vehicle disc brake according to claim 4 ,
wherein a plating solution including an iron compound, a phosphinic acid compound, and organic acid is used in the process of forming the first plating layer.
6. The method for manufacturing a piston for a vehicle disc brake according to claim 5 ,
wherein the organic acid is glycine and L-ascorbic acid.
7. The method for manufacturing a piston for a vehicle disc brake according to claim 4 ,
wherein the second plating layer further includes 10 to 30 volume percent of resin particles and the resin particles are made of polytetrafluoroethylene (PTFE).
8. The piston for a vehicle disc brake according to claim 2 ,
wherein the first plating layer has a film thickness of 1 to 15 μm and the second plating layer has a film thickness of 1 to 15 μm.
9. The method for manufacturing a piston for a vehicle disc brake according to claim 5 ,
wherein the second plating layer further includes 10 to 30 volume percent of resin particles and the resin particles are made of polytetrafluoroethylene (PTFE).
10. The method for manufacturing a piston for a vehicle disc brake according to claim 6 ,
wherein the second plating layer further includes 10 to 30 volume percent of resin particles and the resin particles are made of polytetrafluoroethylene (PTFE).