A chuck device in a robot hand is used when receiving a primary formed workpiece from electrode chucks. After receiving the primary formed workpiece, and before inserting the primary formed workpiece from its shaft stem part into an insertion hole in a forging press main body, a portion held by the electrode chucks of the primary formed workpiece is gripped by a chuck device different from the chuck device, to release the gripping of the primary formed workpiece by the chuck device. Therefore, it is possible to insert the holding portion held by the electrode chucks from the side of the shaft stem part of the primary formed workpiece into the insertion hole. Thereby providing a bar material transfer method capable of accurately inserting the bar material from its one end into a predetermined positioning hole even if a bar material serving as a workpiece is short.

A precision forming method of a high-efficiency and near-net hollow valve blank of an engine is provided, wherein the precision performing is realized by the cross wedge rolling mold, under the rolling the metal tubing for the valve deforms, with a middle part sunken and two ends elongating, the middle part forms a stem part of a hollow valve, the two ends form disk parts to be machined, and the connection sections between the disk parts and the stem part form neck parts having arced concave faces and a frustoconical lateral face in structure, achieving better consistency among the acquired hollow valve blanks. The disk part of each acquired hollow valve preformed blank is machined by the die-forging forming mold that is matched with the disk structure of the manufactured hollow valve, the hollow valve preformed blank is directly placed in the cavities of the die-forging forming mold for forging.

A method and an apparatus for supplying inert gas into a poppet valve intermediate are provided that are capable of properly filling the inert gas without waste into the poppet valve intermediate of any size. After a negative pressure is achieved by suction in an internal space (Win) of a poppet valve intermediate (W) as compared to an ambient pressure (Pa) of the poppet valve intermediate (W), the inert gas is supplied into the internal space (Win) until a pressure (F) of the internal space (Win) reaches the ambient pressure (Ps) of the poppet valve intermediate (W).

A method and an apparatus for supplying inert gas into a poppet valve intermediate are provided that are capable of properly filling the inert gas without waste into the poppet valve intermediate of any size. After a negative pressure is achieved by suction in an internal space (Win) of a poppet valve intermediate (W) as compared to an ambient pressure (Pa) of the poppet valve intermediate (W), the inert gas is supplied into the internal space (Win) until a pressure (F) of the internal space (Win) reaches the ambient pressure (Ps) of the poppet valve intermediate (W).

A hollow poppet valve has an internal cavity which extends from within its valve head into a valve stem portion and is partly filled with a coolant. A manufacturing method includes forming a coolant rod by cutting clayish coolant to a coolant rod of a predetermined length from the coolant material extruded from an extruder; a coolant-rod insertion step in which a coolant rod is inserted into a cavity formed in an intermediate valve product through its opening; and a step of sealing the opening of the hole. In the coolant-rod insertion step, coolant-rods are inserted into the cavity separately in multiple times. Since each coolant rod is short, it is little deformed or bent, so that it has little interference with the inner periphery of the cavity, which permits use of a thick rod and increase the amount of the coolant in the cavity.

A hollow poppet valve has an internal cavity which extends from within its valve head into a valve stem portion and is partly filled with a coolant. A manufacturing method includes forming a coolant rod by cutting clayish coolant to a coolant rod of a predetermined length from the coolant material extruded from an extruder; a coolant-rod insertion step in which a coolant rod is inserted into a cavity formed in an intermediate valve product through its opening; and a step of sealing the opening of the hole. In the coolant-rod insertion step, coolant-rods are inserted into the cavity separately in multiple times. Since each coolant rod is short, it is little deformed or bent, so that it has little interference with the inner periphery of the cavity, which permits use of a thick rod and increase the amount of the coolant in the cavity.

A method for manufacturing a poppet valve 10 from an intermediate valve products is disclosed. The intermediate valve products have an intermediate valve head 14 with a pressing protrusions 15. A peak 15a of the pressing protrusions 15 is located in a normal direction X2 of the seat surface N, which is positioned on a normal line X2 passing a reference point P3 set on a line segment K connecting a base point P1 in an inner side and a base point P2 in an outer side of the seat surface N; a position of the reference point P3 is set such that a relation between a length L1 from the base point P1 to the reference point P3 and a length L2 from the base point P2 to the reference point P3 meets a formula of L1/L20.5.

A method for manufacturing a poppet valve 10 from an intermediate valve products is disclosed. The intermediate valve products have an intermediate valve head 14 with a pressing protrusions 15. A peak 15a of the pressing protrusions 15 is located in a normal direction X2 of the seat surface N, which is positioned on a normal line X2 passing a reference point P3 set on a line segment K connecting a base point P1 in an inner side and a base point P2 in an outer side of the seat surface N; a position of the reference point P3 is set such that a relation between a length L1 from the base point P1 to the reference point P3 and a length L2 from the base point P2 to the reference point P3 meets a formula of L1/L20.5.

A hollow poppet valve (10) is provided with an additional flange shape cavity (S1a), in addition to an ordinary valve head cavity (S1) formed in the valve head (14) of the valve (10) in communication with a valve stem cavity (S2) formed in a valve stem (12). A coolant (19) is loaded in the cavities to facilitate dissipation of heat out of the valve. This flange shape cavity (S1a) extends radially outwardly round a bottom portion of the valve head cavity (S1), extending close to a valve seat, thereby significantly facilitating heat transfer between the coolant (19) and the valve seat of the valve, yet, since the flange shape cavity (S1a) does not influences the thickness of other regions of the valve, it does not degrade durability of the valve.

An intake valve for a combustion engine is described. The intake valve has a head portion that is designed to improve the flow of air-fuel mixture around the head portion and into the combustion chamber. The head portion has a beveled or rounded edge at the top surface. The angle changes from the underside surface to the top surface are rounded to prevent separation of the air-fuel mixture from the surface of the intake valve. In addition, the underside surface of the head portion has a plurality of helical grooves that induce a circular flow to improve mixing of the air-fuel mixture in the chamber. The helical grooves also improve heat exchange between the air-fuel mixture and the intake valve.