Abstract: An extrusion die for a hollow member includes: a male die for defining a plurality of hollow portions of the hollow member, the male die including an annular base portion and a bridge portion bridging the annular base portion; a female die for defining an outer peripheral portion of the hollow member, the female die being fitted in the annular base portion; and a mandrel having a plurality of forming protrusions, the mandrel being inserted and held in a mandrel holding slit formed in a center of the bridge portion in a fore-and-aft direction. The mandrel includes a mandrel main portion divided into a plurality of divided members and a plurality of rigid pins each arranged in a fore-and-aft direction of the mandrel main portion, and wherein the rigid pins are pinched by and between the divided members of the mandrel main portion with tip portions of the rigid pins protruding from an front end of the mandrel main portion, whereby the tip portions constitute the forming protrusions.

Abstract: An extrusion die for a hollow member includes: a male die for defining a plurality of hollow portions of the hollow member, the male die including an annular base portion and a bridge portion bridging the annular base portion; a female die for defining an outer peripheral portion of the hollow member, the female die being fitted in the annular base portion; and a mandrel having a plurality of forming protrusions, the mandrel being inserted and held in a mandrel holding slit formed in a center of the bridge portion in a fore-and-aft direction. The mandrel includes a mandrel main portion divided into a plurality of divided members and a plurality of rigid pins each arranged in a fore-and-aft direction of the mandrel main portion, and wherein the rigid pins are pinched by and between the divided members of the mandrel main portion with tip portions of the rigid pins protruding from an front end of the mandrel main portion, whereby the tip portions constitute the forming protrusions.

Abstract: A metal hollow member having a plurality of hollow portions extending in a longitudinal direction thereof and communication apertures formed in a partitioning wall partitioning adjacent hollow portions is formed by: extruding a molten extrusion material through a die comprising a female die for forming an outer peripheral portion of the metal hollow member and a male die including a plurality of hollow-portion-forming protrusions corresponding to the plurality of hollow portions; and intermittently supplying fluid insoluble in the molten extrusion material into the partitioning wall from a bottom portion of a groove formed between the adjacent hollow-portion-forming protrusions while extruding the molten extrusion material, whereby the plurality of communication apertures are formed by fluid-released-apertures from which the fluid is released.

Abstract: A male die (2) is composed of an annular base (7), a bridge (8) and a forming lug (9), and a female die (3) tightly fits in the annular base (7) of the corresponding male die (2). A distance between a forming slit (28) and a location where the male die (2) engages with the female die (3) is decreased such that the misalignment of the forming lug (9) with a forming hole (26) is prevented from occurring during an extrusion process. The male die in combination of the female die enables the production of hollow articles of a high dimensional precision free of any unevenness in wall thickness.

Abstract: The object of the present invention is to provide a die assembly of a compact structure adapted for simultaneously extruding two or more hollow metallic articles of a high precision in size and shape. A male die 2 has two apertures 15 in a bridge 13 of a core holder 6 and two cores 5 respectively inserted in the aperture 15, and a female die 3 has two bearing edges 21 to contour an outer periphery of a hollow article `E`. When the male die 2 combines with the female die 3, a plurality of forming slots 22 are independently formed in one die assembly.

Abstract: A hollow die (5) for extruding elongate hollow articles has a thick cylindrical body (15), whose cavity (23) extends in the axial direction of the die. This cavity receives and holds a core (7), a female member (21) and other necessary parts in alignment with each other in the axial direction. The hollow die is thus of such a high rigidity that higher extrusion rates will not cause any intolerable distortion or the like deformation in the die, thereby enhancing the productivity and the dimensional precision of the extrudates. The hollow die is particularly adapted for use with the continuous extrusion forming apparatuses.

Abstract: A die (1) has a thin rod-shaped mandrel (2) tightly surrounded by the segments (11) of a gripper (3), the mandrel (2) being placed in the axial bore (5) of a mandrel holder (4). The inner peripheral surface of the axial bore (5) is shrinkage-fitted or otherwise fixedly fitted on outer peripheral surfaces of the gripping segments (11), thereby urging them to keep the thin rod-shaped mandrel (2) in place in the holder (4). The mandrel can have an extremely fine orifice forming end (9) of a diameter of 3 mm or less, such an fine can be prepared easily and precisely, and maintenance of the die can be done inexpensively when the orifice forming end will have been worn out or damaged.

Abstract: A die assembly has at least one core (7), a male die supporter (8) and at least one female member (5). The male die supporter is composed of an annular base (15), a core holder (16) and bridges (17) formed integral with the annular base and the core holder. Each core (7) is shrinkage-fitted in and integral with a cylindrical recess (21) formed in the core holder. The die assembly further has a die retaining mechanism such that the pressure of the material being extruded causes a latchable member to engage with a latching member. Each female member (5) is shrinkage-fitted in and integral with the annular base (15), so that the die assembly can produce hollow articles free from any unevenness in wall thickness, the abraded portion of this assembly can be renewed inexpensively, and the core is surely protected from slipping off.

Abstract: An apparatus has first propellers (20) and second propellers (21) alternating with the first propellers. Each propeller has one or more helical biting edges (24a) protruding into a guide passage (28) through which a raw material (W) advances. The biting edges are formed along an inner periphery of each propeller at a predetermined lead angle so as to bite an outer periphery of the raw material (W). The apparatus further has a drive mechanism for rotating the first propellers (20) in a direction opposite to that in which the second propellers (21) are driven. The helical biting edges (24a) are inclined such that the raw material (W) may be forced towards a pressure vessel (2) by all the propellers, notwithstanding the opposite directions in which the first and second propellers ape driven, so that a strong thrust is applied to the raw material, without causing any torsion of the material which is being forced towards the pressure vessel.

Abstract: A core body (60) is disposed in a feed passage (40) in rear of an extrusion die (5), with the passage being provided to transport an extrusile material. One or more annular passageways (63) are formed between the outer periphery of the core body and the inner periphery of the feed passage, so that helical edges (50a, 55a) protrude into the annular passageways. As the helical edges (50a, 55a) are driven to rotate, a strong thrust is applied to the extrusile material (M) within the feed passage (40) towards the extrusion die (5), so that the extrusion pressure is raised to improve the extrudability of various raw materials.

Abstract: A female die 3 is composed of a plate-shaped bearing tip 31, a backup block 32 and a cylindrical holder 33 for receiving and setting in place the tip together with the block, in which the bearing tip 31 made of a hard metal and the backup block 32 also made of the hard metal are such that they can be manufactured simply and easily, and in which only the bearing tip 31 need be replaced with a new one if and when the bearing portion of the die has been abraded.

Abstract: The combination die assembly comprises male die which is composed of a core 12 formed with at least one opening 16 piecing the body portion of the core, a stopping pin 13 having its side ends 13a protruding from the opening, and a mold 14 for holding the core 12. The mold 14 is formed with a core-holding aperture 21 having inside shoulders which bear the side ends 13a of the pin 13, so that the core 12 is easily manufactured, any undesirable stress concentration onto the member for support of the core is avoided, and the reliability in mechanical strength of the core is improved.