Abstract:
A hot worked steel material, such as a bar, or tube, has a surface layer improving its fatigue strength despite the non-metallic inclusions which it may contain, or the cracks which it may have. The surface layer is formed by heating a nickel layer on the steel surface to cause the diffusion of nickel therethrough.
Abstract:
A common rail includes a main pipe rail having a circulating passage extending in its inside in the axial direction thereof, branch holes formed in an axial peripheral wall portion of the main pipe rail, and branch connectors connected to the respective branch holes integrally or via separate connecting members. A Ni-diffused fatigue strength reinforcing layer is formed by heating a Ni layer plated in advance on at least a portion of an inner circumferential surface of the common rail. The increased strength and the action of the fatigue strength reinforcing layer lowers the degree of fatigue concentration to increase fatigue strength against inner pressure.
Abstract:
A common rail has a main pipe rail with a peripheral wall. A boss is provided on the peripheral wall, and a branch hole extends through the boss and into the main pipe rail. The branch hole has a pressure receiving seat face. A branch pipe has a pressing seat face that is urged into the pressure receiving seat face by a fastening nut. An orifice pipe is mounted in the branch hole and abuts against an end of the branch pipe without effecting sealing performance between the pressing seat face and the pressure receiving seat face.
Abstract:
There is provided a common rail which can effectively restrict a generation of a stress in a lower end inner peripheral edge portion of a branch hole and can improve an internal pressure fatigue strength in a branch pipe connecting portion, so that a secure and stable function can be obtained by having an excellent durability and preventing a fluid leakage due to a generation of the crack generation and a method of manufacturing a common rail in which a pressure application process by the press is only added to a normal manufacturing process, no complex equipment is required, a common rail having a high quality can be manufactured by a low cost without generating problems that an equipment cost is increased by an increase of the process and a productivity is reduced. In the method of the invention, there is provided a method of manufacturing a common rail comprising at least one branch hole provided in an axial peripheral wall portion of a main pipe rail having a communication passage inside an axial core, a pressure receiving seat surface communicating with a branch pipe having a communication passage communicating with the communication passage in a peripheral surface portion of the branch hole and open to an outer portion, thereby bringing a pressing seat surface portion constituted by a connection head portion disposed in an end portion of the branch pipe into contact and engaging therewith, and a joint metal fitting surrounding an outer peripheral portion of the main pipe rail and a nut previously assembled in the branch pipe end which are meshed with each other so as to be pressed under a neck portion of the connection head portion, thereby being fastened and connected, wherein a pressing force is applied to the main pipe rail near the branch hole from an outer portion to a diametrical direction by a press method, thereby generating a compression residual stress at a portion near the open end portion of the communication passage of the main pipe rail in the branch hole.
Abstract:
A method is provided for manufacturing common rails, such as a high-pressure fluid manifold or a block rail that may be use in an accumulator fluid injection system. The method includes providing a main tubular rail with a flow passage extending in an axial direction. A bottomed lower hole is formed generally transverse to the axial flow passage. A pressing force is applied to the bottomed lower hole to generate a residual compressive stress in a circumferential part of the end portion of the bottom hole. The bottom lower hole then is made to communicate with the flow passage in the main rail. Defects that may have been caused by the application of the pressing force then are cut off. The removal of the defects improves an internal pressure fatigue strength, achieves high durability and ensures freedom from leakage.
Abstract:
A common rail includes a generally cylindrical peripheral wall having a communication passage extending axially therethrough. At least one branch hole extends through the peripheral wall and is aligned perpendicular to the axis of the common rail. The intersection of the branch hole with the outer surface of the main pipe rail defines an outwardly flared pressure receiving seat for receiving the connection head portion of a branch pipe. A sleeve nipple is welded or brazed to the outer surface of the main pipe rail and surrounds the branch hole. Inner surface regions of the peripheral wall surrounding the branch hole have a compression residual stress imparted thereto. The creation of the compression residual stress may cause a portion of the inner surface of the main pipe rail surrounding the branch hole to assume a non-cylindrical configuration.