BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings,
FIG. 1 is a front view of a piston system with the piston pin pivotally connected between a connecting rod and a piston;
FIG. 2A is a pictorial drawing of a wider included angle in the first taper forming operation showing the next station punch at the initial contact point, and
FIG. 2B is a pictorial drawing of a narrower included angle in the first taper forming operation showing the next station punch at the initial contact point, and
FIG. 3 is a pictorial drawing representing an exemplary two-way center-web extrusion method of manufacturing tapered piston pins, and
FIG. 4 is a pictorial drawing representing an exemplary one-way webless extrusion method for manufacturing tapered piston pins.
DETAILED DESCRIPTION OF DRAWINGS
FIGS. 3 and 4, views A through D, illustrate typical processes of manufacturing piston pins. These processes begin with bar or coil steel. Generally, carbon steel wire is used for reasons relating to carbon steels' physical and mechanical properties that are attractive for forming piston pins as well as providing the necessary characteristics to the end product cost effectively. Nonetheless, alternative metals could also be used depending on the application involved. The metal wire is unrolled and straightened. After exiting the unrolling machine, the metal coil is cut into separate pieces. These pieces are shaped roughly cylindrical. Next, the pieces are prepared for the extrusion processes. Depending on the specifications required by the customer, tapering of piston pins may be required. The tapering process will be further described with reference to subsequent figures.
With reference to FIG. 3, a typical two-way/center-web extrusion forming sequence relating to the manufacturing of a piston pin is illustrated. Anyone familiar with cold forming understands that this is only an example of how to form a piston pin. The purpose of this invention is to use this only as an example and the invention applies to all methods of forming tapers in a tubular extruded blank.
With reference to FIG. 4, a one-way/end-web extrusion forming sequence relating to the manufacturing of a piston pin is illustrated. Anyone familiar with cold forming understands that this is only an example of how to form a piston pin. The purpose of this invention is to use this only as an example and the invention applies to all methods of forming tapers in a tubular extruded blank.
Referring now to FIG. 2A, from the tubular formed blank, item 50, the invention demonstrates the forming operation for developing a taper in both ends of the inner portion of the piston pin blank. This figure reflects the forming of the taper to a larger included angle, item 58, than the finished requirement, item 52, at a predetermined length which would be shorter or equal to the finished taper length in the axial direction of the piston pin. The ultimate finished contour is shown at 56. This is only an example. Anyone familiar with forming technology understands that this could be completed in one or multiple stations, but this invention focus' on the most cost effective method of forming tapers in the inner portion of a tubular blank. However, the intent of this invention is to cover all multiple sequences of forming tapers in the inner portion of a tubular blank.
FIG. 2B is an example of forming the piston pin to the finished requirements from a blank, item 68, from a previous taper forming operation. This figure shows the finishing tool, item 62, above a previously former tapered blank wall 168. The ultimate finished contour is shown at 66. Anyone familiar with forming technology understands that this could be completed in one or multiple stations, but this invention focus' on the most cost effective method of forming tapers in the inner portion of a tubular blank.
The above-described method for tapering piston pins is an example implementation. The method illustrates one possible approach for forming tapers in piston pins, without the need for an expensive machining, coating or additional forming processes. The actual implementation may vary from the arrangement discussed. Moreover, various other improvements and modifications to this invention may occur to those skilled in the art, and those improvements and modifications will fall within the scope of this invention as set forth in the claims below.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. Therefore, the scope of the invention is not limited to the specific exemplary embodiment described above. All changes or modifications within the meaning and range of equivalents are intended to be embraced herein.
Patent Application
20080047125
