Assembly method of oil cylinder piston

The invention discloses a method for assembling an oil cylinder piston. The method comprises the following steps that a, a cylinder head of an oil cylinder is detached from a cylinder barrel; b, a clamping ring groove or a tool withdrawal groove in the inner wall of the cylinder barrel is filled with filler, and the surface of the filler is made to be smooth and flush with the inner wall of the cylinder barrel; c, the piston is pulled out of the cylinder barrel; d, installing or replacing an oil seal on the piston; e, the piston is assembled in the cylinder barrel; f, the filler in the clamping ring groove or the tool withdrawal groove is removed; and g, the cylinder head is installed on the cylinder barrel again, and assembly of the piston is completed. The clamping ring groove or the tool withdrawal groove in the inner wall of the cylinder barrel is filled and leveled up through the filler, then the piston is assembled in the cylinder barrel, and due to the fact that the smooth curved surface is formed in t