Metal plate rocker arm and method of manufacturing same

Abstract

A method of manufacturing a metal plate rocker arm, comprising the steps of forming a raw plate having a specified outline and through-holes by punching out and forming one sheet of metal material, forming a pair of side wall parts generally parallel with each other and a connection part for connecting the lateral one end edges of these both side wall parts to each other by applying a bending operation to the raw plate by pressing, forming at least a pair of circular holes in these both side wall parts at the positions matching with each other, forming an engaging part in the state recessed more than the other part of the connection part on one surface of the connecting part by deforming the middle part of the connection part in a thickness direction, allowing a swelling part of trapezoidal shape in cross section projected in bank shape according to the formation of the engaging part to be present on the other surface of the connection part, and allowing the center part lateral both end edges of the swelling part corresponding to the upper side of the trapezoidal shape to be present on the lateral more inner side than the lateral both end edges of the engaging part.

Description

Technical field [0001] The present invention relates to an improvement of a rocker arm made of sheet metal manufactured by pressure processing with a metal plate assembled on the valve train of an engine. This rocker arm is used to convert the rotation of a camshaft into a valve body (intake valve and exhaust). Air valve) One of the reciprocating rocker arms. Background technique [0002] In addition to some two-stroke engines, reciprocating engines (reciprocating piston engines) are provided with intake valves and exhaust valves that open and close in synchronization with the rotation of the crankshaft. In such a reciprocating engine, the movement of the camshaft that rotates in synchronization with the rotation of the crankshaft (in the case of a four-stroke engine, at a rotation speed of 1 / 2) is transmitted to the intake valve and exhaust through a rocker arm. The air valve makes the intake valve and the exhaust valve reciprocate in the axial direction respectively. [0003] I...

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Problems solved by technology

[0029] In addition, although it is also desirable to increase the thickness of the fitting portion for this purpose, in the case of the above-mentioned manufacturing method of the previous invention, since the thickness of the rough-worked steel sheet is at most 5 to 40%, it is necessary to For example, let the thickness t of the connection part 3 constituting the above-mentioned fitting part 6 3 Approximate the thickness t of a pair of side walls 2.2 2 Twice or more than twice the thickness of the

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