Machining inner surface of cylindrical bore in workpiece e.g. cylinder crankcase using roll forming operation, by rolling a roller element of a machining tool under a contact pressure against a segment of a curved workpiece to be machined

摘要

The machining method comprises rolling a roller element (180A, 180B, 180C) of a machining tool under a contact pressure against a segment (198) of a curved workpiece (200) to be machined. An outer surface of the roller element comprises a rough surface structure in a working segment intended for rolling contact with a workpiece surface (210). The contact pressure is set so that a rough roll-formed structure is generated when rolling by locally deforming a workpiece material without removing material in the area of the workpiece surface is machined. The machining method comprises rolling a roller element (180A, 180B, 180C) of a machining tool under a contact pressure against a segment (198) of a curved workpiece (200) to be machined. An outer surface of the roller element comprises a rough surface structure in a working segment intended for rolling contact with a workpiece surface (210). The contact pressure is set so that a rough roll-formed structure is generated when rolling by locally deforming a workpiece material without removing material in the area of the workpiece surface is machined. The roll forming operation at the workpiece surface of the rough roll-formed structure with an average surface roughness of 10 mu m is generated. The generated average roughness is 30-100 mu m. A coating is applied by thermal spraying after the roll forming operation on the workpiece surface, where the coating is directly applied on the rough roll-formed structure generated by the roll forming operation or the roll-formed structure is reworked after the roll forming operation using post-processing method for generating a modified roll-formed structure. The coating is subsequently applied on the modified roll-formed structure. A cleaning of the workpiece surface is performed during and/or after the roll forming operation in the form of the roll-formed structure, and is produced for removing material particles bound to the workpiece surface by the roll forming operation, where the roll-formed structure is brushed and/or pneumatically free-blown by relatively soft non-abrasive brushes. A suction of a processing residue of the roll forming operation takes place during and/or after the roll forming operation and is free-blown to the suction of the workpiece surface. One of the roll forming operations downstream in form of the roll-formed structure changes a post-processing for generating the modified roll-formed structure that comprises an elimination of tips in a range of elevations for producing a plateau with a flattened structure and lies between slots at the workpiece surface. The tips in the range of elevations are removed by a material. The roller element of the machining tool is rolled under the contact pressure against the segment of the curved workpiece to be machined, in which the machining tool is guided in a predefined distance from the workpiece surface along a predefined path. A course of the predefined path of the machining tool is dependent on a curvature of the workpiece surface as well as dependant on the contact pressure. The rolling step is effected for machining the inner surface of the cylindrical bore, in which the machining tool is used in a bore filling that is formed as a rotary tool and is rotationally driven around the tool axis. An independent claim is included for a machining tool for machining the inner surface of a bore in a workpiece cylinder crankcase or cylinder liner.