Method for Forming a Cam-Engaged Rocker Arm

Abstract

Valve guides are formed on a U-shaped sheet metal rocker arm by the horizontal displacement inwardly of surface metal from the outboard portion of the rocker arm. A rocker arm body made by forming a steel flat blank into a U-shape cross-section comprising sidewalls that connect a pad end and an opposite socket end. The pad end is defined by a central section and two outboard surfaces. The valve guide walls are formed by displacing material from the outboard surface portions of the pad end and forcing it centrally. This changes, i.e., diminishes, the thickness of the outboard portions of the pad end of the rocker arm which are not aligned with valve contact central surface. The valve contact area defined by horizontal surface and by the vertical sides of the formed guide extensions is created by a tool having a width to accept a known valve stem diameter. The valve guide extensions are parallel to and offset from the pad end rocker arm sidewalls and are created to have the proper thickness as well as suitable height to survive in the rocker arm application. The surface extremity, i.e., height as well as the thickness of the valve guide wall, is determined by the amount of material displaced from surfaces of the outboard portion of the pad end of the rocker arm. Valve guide extension height and thickness dimensions can be achieved that were not attainable by known prior art methods.

1 . A method of forming guide elements on a rocker arm formed by bending a sheet metal blank into a U-shaped intermediate having a pad end, a mid-portion and a socket end comprising the steps: 
 (a) displacing material laterally from the surfaces of the outboard portions at the bottom of the pad end and forcing controlled portions of the displaced material laterally inwardly to form valve guides and thereby diminishing the thickness of said outboard portions while essentially retaining the thickness of the central pad section contained within said outboard portion;    (b) maintaining the lateral displacement of material such that guides that extend substantially perpendicularly from the pad end surface and have a width conforming to the desired valve stem diameter are formed; and    (c) continuing the displacement of said displaced material from the outer sections of the pad end to create valve guides of the desired height.    
   
   
       2 . The method of  claim 1  applied to form valve guides for a roller follower rocker arm.  
   
   
       3 . The method of  claim 1  applied to form valve guides for a flat rocker arm.  
   
   
       4 . The method of  claim 1  applied to for valve guides for a center pivot rocker arm.