Machine element or mechanism – Elements – Cranks and wrist pins
Reexamination Certificate
1999-09-23
2001-12-11
Estremsky, Sherry (Department: 3681)
Machine element or mechanism
Elements
Cranks and wrist pins
C074S595000
Reexamination Certificate
active
06327933
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to the casting of crankshafts. More particularly, the present invention relates to a cast crankshaft parting line strategy that aids in the molding and trimming processes of the crankshaft without detrimental design impact.
BACKGROUND ART
In the manufacture of metal casting, superfluous metal is often formed about the periphery of the casting coincident to where the parting line of the casting mold intersects the casting cavity. One common cause of such superfluous metal is the flashing of metal along the parting line due to imperfectly mating parting surfaces on the opposite elements on the mold. Various attempts to minimize flashing have been utilized, however, it is virtually impossible to eliminate all flash during the casting process on a consistent basis. Thus, subsequent processes must be utilized in order to remove the flash before the cast metal part may be commercially utilized.
An example of a cast metal part is a crankshaft for an internal combustion engine, which is typically formed from known casting processes. These casting processes are no different than other metal casting processes, in that metal flashing typically remains on the crankshaft coincident to the parting line after the crankshaft has been removed from the mold. Therefore, subsequent processes must be utilized in order to remove the metal flash that accumulates on the crankshaft parting line. These subsequent processes are relatively time consuming and expensive.
One of the problems with the removal of flash with current crankshaft configurations is that the parting lines are located along the edges of some of the parts and are therefore perpendicular to the axis of the crankshaft. This perpendicular orientation of the metal flash is extremely stiff and very difficult to remove with current trim die machines. In fact, the stiffness of the flash that results from the perpendicular orientation of the metal flash with respect to the crankshaft edges generates a tremendous load on the trim die machine, which can cause failure of the machine and thus significantly increase the expense of the manufacturing process. Because of the inability of the trim die machines to adequately remove the metal flash, the flash is often removed by hand which further increases, the cost of and the time required to complete the manufacturing process.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a cast parting line strategy for a crankshaft that facilitates the molding and deflashing operations.
It is a further object of the present invention to provide a crankshaft configuration that results in metal flash at mold parting lines that can be easily removed mechanically.
In accordance with the objects of the present invention a crankshaft with an improved parting line strategy is provided. The crankshaft includes a plurality of cheeks, including a three cheek, a four cheek, a five cheek, and a six cheek. The three cheek and the four cheek are connected by a two pin, the four cheek is in turn connected to the five cheek by a main journal pin, and the five cheek is connected to the six cheek by a three pin. The crankshaft parting line has a plurality of portions. The first parting line portion extends generally across an outer surface of the two pin along its centerline. The second parting line portion extends generally upward and diagonally across the face of the four cheek beginning at one edge at a point along the centerline of the two pin and terminating at an opposing edge of the four cheek at a point along a centerline of the main journal pin. The third parting line portion extends generally across an outer surface of the main journal pin along its centerline. The fourth parting line portion extends generally upward and diagonally across the face of the five cheek beginning at one edge at a point along the centerline of the main journal pin and terminating at an opposing edge of the five cheek at a point along a centerline of the three pin. The fifth parting line portion extends generally across an outer surface of the four pin along its centerline. The sixth parting line portion extends generally downward and diagonally across the face of the six cheek beginning at one edge at a point along the centerline of the three pin and terminating at a point along a centerline of a five pin.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.
REFERENCES:
patent: 3897817 (1975-08-01), Nieman
patent: 4829642 (1989-05-01), Thomas et al.
patent: 5481942 (1996-01-01), Baek
patent: 24 24 590 A1 (1975-12-01), None
patent: 58-132342 (1983-08-01), None
patent: 63-5839 (1988-01-01), None
Mathews Shaji
Sears Ronald M.
Williams Rick L.
Drouillard Jerome R.
Estremsky Sherry
Ford Global Technologies
Lewis Tisha D.
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