The invention relates to a method for work-hardening a crankshaft (4) comprising connecting rod journals (5), main bearing journals (6) and crank webs (7), the connecting rod journals (5) and the main bearing journals (6) being provided with oil holes (31). According to the invention, at least one end (30) of one of the oil holes (31) and/or at least one cylindrical portion (38) of the oil holes (31) is/are work-hardened.

The invention relates to a method for post-processing a crankshaft (4), in particular in order to correct concentricity errors and/or for a length correction. Sectors (S1,S2,S3,S4,S5,S6) of the crankshaft (4) which produce and/or characterize concentricity errors are detected and/or a length deviation (L1 L2, L3) from a target length (L1,L2, L3) is determined for at least one section of the crankshaft (4). An impact force (Fs) is then introduced into at least one defined transition radius (8) between connecting rod bearing journals (5) and crank webs (7) and/or between main bearing journals (6) and the crank webs (7) of the crankshaft (4) by means of at least one impact tool (16) in order to correct the concentricity errors and/or the length deviation (L1 L2, L3).

A method of manufacturing a crankshaft includes the steps of: (1) forming a crankshaft blank via a first half and a second half; (2) measuring a plurality of surface variations between a predetermined surface in a first region and a corresponding predetermined surface in a second region of the crankshaft blank; (3) calculating centering offset data based on the plurality of surface variations; (4) machining a pair center holes based on the centering offset data; (5) machining a counterweight and a journal relative to the pair of center holes to produce a partially machined crankshaft; (5) milling and grinding the partially machined crankshaft to produce a finished machined crankshaft; and (6) rotating the finished machined crankshaft typically on the outermost main journals in a final balancing machine and then modifying the counterweights to eliminate undesirable vibration generated during the rotation and engine operation.

The invention relates to a method for the impact treatment of transition radii (8) of a crankshaft (4, 4), in particular transition radii (8) between connecting rod bearing journals (5, 5) and crank webs (7, 7) and/or transition radii (8) between main bearing journals (6, 6) and the crank webs (7, 7) of the crankshaft (4, 4). The crankshaft (4, 4) is then rotated along a rotational direction into an impact position by means of a drive device (3, 3). A locking device (12) is provided in order to lock the crankshaft (4, 4) in the impact position, and an impact force is then introduced into at least one transition radius (8) by at least one impact tool (16, 16).

A production method includes a forging step, a flash-trimming step, and a pressing step. In the forging step, a finish-forged product with flash is formed by an upper forging, die and a lower forging die. In the forging step, an excess portion is formed on at least one crankarm which is connected to a first or third pin, in a portion near the first or third pin, on an outer periphery of a lateral part near the upper forging die, such that the excess portion protrudes from the outer periphery. In the pressing step, the excess portion is pressed by an upper die such that the excess portion bulges toward a journal. This method allows production of a forged crankshaft with a reduced weight and a sufficient rigidity in a simple facility.

Systems and methods of making a cast steel alloy crankshaft for an internal combustion engine are provided. The method comprises providing a mold of the crankshaft. The mold has cavities to form the crankshaft. The method further comprises melting a first metallic material at between 1400 degrees Celsius ( C.) and 1600 C. to define a molten metallic material. In addition, the method further comprises feeding the molten metallic material at a riser connection angle of between 30 and 75 in the cavities of the negative sand cast mold. The method further comprises cooling the molten metallic material at a solidification time of between 5 seconds (sec) and 20 sec in the negative sand cast mold with at least one chill member to define a solidified metallic material having dimensions of the cast steel alloy crankshaft. Furthermore, the method comprises separating the solidified metallic material from the negative sand cast mold to define the cast steel alloy crankshaft.

The disclosed production method includes a die forging step of obtaining a forged blank with flash having a crankshaft shape, and a trimming step of removing the flash from the forged blank while nipping the forged blank with a pair of holding dies. In the forged blank, at least one of the rough crank arms have, in a region near an adjacent rough pin, a first excess portion protruding from an outer periphery of a side portion of the rough crank arm. When the forged blank is nipped with the pair of holding dies, the first excess portion is deformed by the pair of holding dies to bulge toward an adjacent rough journal.

The invention discloses a hard-rolling roller head with two separate housings for deep rolling the outside radii of adjoining crankpins of a split-pin crankshaft. The hard-rolling roller head provides an effective support of the two housings against one another, when machining split-pin crankshafts, and simultaneously prevents the upper areas of these housings from drifting apart.

Provided is a production method, including a first preforming process, a second preforming process, a final preforming process, and a finish forging process. In the first preforming process, regions to be a pin and a journal are pressed respectively from a direction perpendicular to an axial direction of the billet, thus reducing cross sectional areas of each region and forming a plurality of flat parts. In the second preforming process, the first preform is pressed in the pressing direction, which is a width direction of the flat parts. In the final preforming process, the second preform is pressed from a direction perpendicular to an axial direction of the second preform, and further a region to be a counterweight and a region to be a crank arm integrally including a counterweight are pressed in the axial direction of the second preform.

A forged crankshaft assembly for an engine, and a method of manufacturing the same, has a forged crankshaft and a removable counterweight to provide access for core drilling or milling a cavity. The forged crankshaft has a pin bearing journal, a main bearing journal, a first crank arm supporting the pin bearing journal, a second crank arm supporting the pin bearing journal and connecting the pin bearing journal and the main bearing journal, and at least one milled crank arm cavity formed within at least a portion of the second crank arm. The removable counterweight extends radially outward from the first crank arm, wherein the crank arm cavity is configured to be accessible to a core drill or mill cutter only when the removable counterweight is removed from the first crank arm and inaccessible to the core drill or mill cutter when the removable counterweight is coupled to the first crank arm.