Forcing Work Into Or Within Closed Die; E.g., Forging Patents (Class 72/352)
  • Patent number: 4640116
    Abstract: A press for converting ends for cans and the like is provided with a conveyor extending sideways through the press to carry shells for processing into can ends along an end converting path. Upper and lower conversion tooling is located along the end converting path at the top and bottom of the conveyor, defining a plurality of stations on opposite sides of the center of the tooling for working progressively on shells moved by the conveyor along the end converting path. First and second tab tooling, auxiliary to the main tooling means, is located on opposite sides of the conveyor extending transversely thereof and defining a tab forming path which bridges the end converting path. Opening tabs are formed from a strip of metal stock fed through the tab tooling and the strip with completed tabs is guided in a loop from the tab tooling back to a staking and attachment station on the end converting path for removal from the strip and attachment to the shells.
    Type: Grant
    Filed: September 3, 1985
    Date of Patent: February 3, 1987
    Assignee: Dayton Reliable Tool & Mfg. Co.
    Inventor: Omar L. Brown
  • Patent number: 4621513
    Abstract: A process for making a rigid packaging container which contains a "rolled lip" which comprises deforming a sheet of metal, plastic or paper composite material over a mold into a desired formed shape which contains a "lip", advancing a trimming means from the convex or bottom side of the shape while said shape is supported so that said shape does not deform; and trimming the shape from the convex or bottom side of the shape at a point on the lip of the shape which undercuts the periphery of the shape while, at the same time, forcing open the undercut of the lip of the shape.
    Type: Grant
    Filed: October 28, 1985
    Date of Patent: November 11, 1986
    Assignee: Shell Oil Company
    Inventor: John F. Bradford, Jr.
  • Patent number: 4601186
    Abstract: A process and apparatus for achieving narrow workpiece tolerances in isothermal drop-forging, the relative movement of the two die halves (1, 2) in an xy plane perpendicular to the pressing direction z being measured and monitored by means of an optical measuring device (10, 11, 12, 14) or mechanical measuring device (14, 15, 16) and being corrected by means of a mechanical adjusting device (6, 17, 21, 23, 24, 25, 26) for one die half (2). A first workpiece is forged, and the divergence from the nominal value is measured, with the die halves (1, 2) closed, the die halves (1, 2) are opened, the first workpiece is removed, the position of one die half (2) is corrected, and a new workpiece is introduced and forged completely, without the workpiece having to be cooled and remeasured and without the die having to be cooled and reheated.
    Type: Grant
    Filed: February 14, 1985
    Date of Patent: July 22, 1986
    Assignee: BBC Brown, Boveri & Co., Ltd.
    Inventors: Roland Kunzli, Hans Rydstad
  • Patent number: 4593598
    Abstract: An apparatus for resizing rifle cartridge cases comprising the die fixedly positioned with respect to a frame and a ram operated by a lever mechanism adapted to raise a case into a resizing cavity within the die. A punch is loosely supported in the die and includes an extractor pin at one end for removing the primer from the head of the rifle case. The die is covered by a head cap including a threaded stem adapted to abut against the punch. The head cap includes a lateral flange adapted to be engaged by levers for forcing the punch against the head of the case when the case is to be removed from the die. The punch also includes an expansion sleeve for resizing the neck of the cartridge as the case is extracted from the die and an expanded end of the punch loosely suspends the punch within the die when the case has been removed.
    Type: Grant
    Filed: September 7, 1984
    Date of Patent: June 10, 1986
    Inventor: James A. Gunder
  • Patent number: 4592220
    Abstract: A system for the automatic adjustment of the pressure pad holding force in accordance with the thickness of the workpiece and the forming tool stroke includes a force transducer and a displacement transducer. The force transducer is used to monitor the force between the pressure pad and the workpiece. The output of the displacement transducer is continually read as the part is being formed. The workpiece thickness and forming tool stroke are used to calculate the optimum holding force. The pressure of a fluid system is adjusted to change the holding force to the optimum value.
    Type: Grant
    Filed: August 7, 1984
    Date of Patent: June 3, 1986
    Assignee: RCA Corporation
    Inventors: Miguel R. Martinez, Zygmunt M. Andrevski, William J. Mitchell, Jr.
  • Patent number: 4587828
    Abstract: A method of forging a crank shaft at least including: a first step of forming a pair of fitting grooves in an outer periphery of a crank throw portion of a billet at an axially central portion of the billet, said grooves extending perpendicular to an axis of the crank throw portion as well as to a diametral line thereof; a second step of subjecting said billet to rough forging by using a rough forging mold which comprises upper and lower molds having respective recesses which are adapted to determine the position of the billet in cooperation with the fitting grooves of the crank throw portion and a journal portion, in which step, an outflow of burr is restricted by means of an inclined offset surface disposed opposite to the outflow direction of said burr while the crank throw portion is forced to move towards a crank pin position; and a third step of subjecting said billet to finish forging by using a finish forging mold which comprises upper and lower molds having respective recesses formed corresponding to
    Type: Grant
    Filed: July 3, 1985
    Date of Patent: May 13, 1986
    Assignee: Honda Giken Kogyo Kabushiki Kaisha
    Inventors: Kou Matsumoto, Toshio Oota, Yuji Asaka, Mitsuki Nakamura
  • Patent number: 4586360
    Abstract: Fine die stamping of workpieces from sheet metal is effected by clamping the workpiece between a die plate and guide plate, supporting the portion of the material to form the article by an ejector which is displaced along with the punch, and driving the supported portion of the material into a hole in the die plate having flanks tapered away from the guide plate and punch so that swaging occurs on the separated portion with or upon its separation from the balance of the workpiece material.
    Type: Grant
    Filed: July 6, 1984
    Date of Patent: May 6, 1986
    Assignee: Dako-Werkzeugfabriken David Kotthaus GmbH & Co. KG
    Inventors: Willi Jurgensmeyer, Friedrich-Wilhelm Honsberg, Kurt Halbach
  • Patent number: 4571977
    Abstract: A forging method for producing a flanged shaft such as, for example, a crankshaft, provided at its intermediate portion with a flange with the flanged shaft being formed from a blank having a diameter which is smaller than the diameter of the shaft end portions but large enough to prevent buckling of the blank when the latter is compressed in the axial direction. The blank is placed within a closed die apparatus and is axially compressed by a punch so that it is possible to produce the flanged shaft at a high dimensional precision and at a high yield, while reducing the time and labor for finishing work conducted after the forging, without requiring any large-size press.
    Type: Grant
    Filed: September 21, 1982
    Date of Patent: February 25, 1986
    Assignee: Hitachi, Ltd.
    Inventors: Keii Ueno, Masanobu Ueda, Minoru Tanikawa, Masami Suzuki
  • Patent number: 4555925
    Abstract: A preheated billet (A) is disposed in a billet receiving region (20) of a lower die (B). The lower preforming die defines a throat region (30) which is smaller in transverse cross section than the billet receiving region and disposed immediately therebelow. The lower die further defines an enlarged relief region (40) which is larger in all transverse dimensions than the throat region and disposed immediately therebelow. An upper die (C) includes a billet engaging surface (50) which has substantially the same transverse cross section as the billet receiving region. The upper die is forced downward by a hydraulic press or the like into engagement with the billet. As the upper preforming die continues downward, the billet engaging surface is telescopically received within the billet receiving region pushing and deforming the billet ahead of it.
    Type: Grant
    Filed: June 11, 1984
    Date of Patent: December 3, 1985
    Inventors: Ralph D. Delio, Donald J. Diemer
  • Patent number: 4513600
    Abstract: A cam actuated ejector is provided with a shell press having a crankshaft for reciprocating a slide to which die tooling is mounted and having a forming station in which the die tooling forms a part to be ejected. The ejector includes a kicker bar slidably received within a recess in the press and which is in close proximity to and substantially coplanar with a part to be ejected. The kicker bar is positively reciprocated by a cam assembly that is synchronously engaged with the crankshaft, which operates the press slide, such that an end of the kicker bar cyclically moves at a first rate of movement from a first position outside the forming station to an intermediate position wherein the end contacts a part to be ejected.
    Type: Grant
    Filed: January 3, 1983
    Date of Patent: April 30, 1985
    Assignee: The Minster Machine Company
    Inventors: Arthur L. Grow, Charles J. Gregorovich, Donald N. Seyfried
  • Patent number: 4466566
    Abstract: A method of forming a thin walled annular channel or semi-toroidal shell from a flat rectalinear sheet, including forming the sheet into a cylindrical band and welding or otherwise securing the abutting free ends of the band. The cylindrical band is then forced into a die set having a cylindrical opening which smoothly blends into an inwardly curving semi-toroidal space defined by opposed concave and convex die surfaces. The cylindrical band is curled inwardly and compressed by the die surfaces, accurately conforming the band and the weldment to the outer concave die surface and eliminating tensile fracture of the weldment.
    Type: Grant
    Filed: August 26, 1981
    Date of Patent: August 21, 1984
    Assignee: Koppy Corporation
    Inventor: William K. Good
  • Patent number: 4462238
    Abstract: A method for increasing strength and/or hardness of a preshaped metal specimen by cold working is disclosed. Compressive force is applied to the specimen slowly so that the yield strength of the specimen progressively increases and the specimen exhibits squirming instability as its diameter increases.
    Type: Grant
    Filed: December 20, 1982
    Date of Patent: July 31, 1984
    Assignee: UTI Corporation
    Inventor: Glenn B. Goodfellow
  • Patent number: 4372144
    Abstract: A wrap ring assembly for cooperation with an associated forging press which includes a punch having a first cavity and means for moving the punch up and down which includes a punch holder. The apparatus includes a wrap ring having a bore therein and means for carrying the wrap ring on the punch holder which allows relative motion therebetween and which includes biasing means for urging the punch holder and the wrap ring apart. A wrap die is dimensioned for cooperation with the punch and has an exterior surface dimensioned for cooperation with the bore of the wrap ring. The apparatus may further include means for gripping the wrap ring and urging the wrap ring away from the punch holder. The apparatus may further include means for heating the wrap ring at least before the initiation of forging operations.
    Type: Grant
    Filed: April 27, 1981
    Date of Patent: February 8, 1983
    Inventors: John J. Valentine, Julius J. Fera
  • Patent number: 4369077
    Abstract: A method of manufacturing stationary electromagnetic cores utilizes mild steel having a carbon content of up to 0.01% by weight and an impurity content of less than 0.31% by weight. Use of this material lowers the cost of manufacturing electromagnetic cores by shortening the drawing process and obviating the necessity for magnetic annealing.
    Type: Grant
    Filed: October 24, 1980
    Date of Patent: January 18, 1983
    Assignee: Fuji Electric Company, Ltd.
    Inventor: Shigemasa Saito
  • Patent number: 4319477
    Abstract: The invention relates to a method and a tool (6,8) for producing a bushing structure (1,2) having a bushing (1) and a polygonal flange (2) said flange initially being formed with a circular circumference (5) having an outer diameter equalling the diameter of the inscribed circle (5) of the polygon to be made whereafter by means of cold deformation the material of the flange at the location of the angles of the polygon to be made is forced to flow outwards by means of a die (8) having projections (9) the inner surfaces (10) of which are steep with respect to the axis of the die and the bottom surface (11) of which run obliquely and arching by upwards and outwards the radial width of said projections decreasing from the center to both sides.
    Type: Grant
    Filed: January 25, 1980
    Date of Patent: March 16, 1982
    Assignee: Koninklijke Emballage Industrie Van Leer B.V.
    Inventor: Frans A. W. Tasseron
  • Patent number: 4299112
    Abstract: A planar blank material to be press-formed is confined in a space formed by punch means having peripheral flange part provided with gear teeth corresponding to those of the hollow product, a mandrel provided slidably in the central hole of said punch means and having outer diameter corresponding to the inner diameter of the hollow product, and a die means having bottom surface and through hole having inner contour corresponding to the outer contour of the boss part of the product. By the pressing action, the peripheral flange part having teeth of the product is formed and simultaneously boss part of the product is formed whereby the synchronizer ring product is formed by one step and the blank material corresponding to the through hole of the product and the product are both ejected out by returning the punch means, mandrel, and die means.
    Type: Grant
    Filed: October 13, 1978
    Date of Patent: November 10, 1981
    Assignee: Kabushiki Kaisha Wako
    Inventors: Kazuyoshi Kondo, Yoshiaki Nakamura
  • Patent number: 4290326
    Abstract: A forged mowing finger for use in mowers having reciprocable cutter blades has a body which is elongated transverse to the direction of reciprocation of the cutter blades and which has a surface adapted to face and coact with the cutter blades. The surface is bounded by lateral faces which define with the surface respective cutting edges. The lateral faces each include with the surface of the body a cutting angle which is smaller than 90.degree.. A method of making such a finger is also provided.
    Type: Grant
    Filed: January 17, 1979
    Date of Patent: September 22, 1981
    Assignee: Carl Sulberg
    Inventors: Adolf Ibach, Heinz Konen
  • Patent number: 4238949
    Abstract: Process and apparatus for making a metal annular member of precise tolerances and desired surface finish. An external die has a continuous die surface of the configuration desired for the external surface of the metal annular member and an annular ridge surrounding the inside of the die for seating one end of an annular sheet metal blank. A first punch engages the sheet metal blank and drives it into the external die so as to reduce the external diameter of the blank and seat it against the ridge. The precise tolerance of the die surface of the external die determines both the external and at least a portion of the internal dimensions produced in the annular sheet metal blank. The first punch is axially movable to an endmost position wherein substantially all of the blank has been forced into the die. An ejector punch is positioned inside of the external die and operates to provide a portion of the forming die surfaces as well as to eject the completed workpiece.
    Type: Grant
    Filed: August 28, 1978
    Date of Patent: December 16, 1980
    Assignee: The General Tire & Rubber Company
    Inventor: Ralph E. Roper
  • Patent number: 4222260
    Abstract: Rod end caps and the method of forming same comprising the steps of using a flashless, closed die set, a predetermined shape and volume billet, warm forging temperatures, and a unique ejector. The ejector pin defines part of the mold cavity when retracted, ejects the finished parts when extended, and locates new billets when in an intermediate position.
    Type: Grant
    Filed: May 15, 1978
    Date of Patent: September 16, 1980
    Assignee: WSP Industries Corporation
    Inventor: Richard P. McDermott
  • Patent number: 4208899
    Abstract: A press for producing machine elements, such as balls, rivets and the like, especially machine elements of relatively small dimensions, e.g. balls having a diameter of 1 mm, from wire sections, which includes a wire intake device, a device for shearing off the wire, a device for conveying the wire sections to and in front of a stationary matrix, and a punch associated with the matrix and adapted to be reciprocated back and forth in axial direction with regard to the matrix. If desired, there may also be provided ejectors for the punch or the matrix. The punch is, axially with regard to the matrix, movably guided in a tool carrier which in pressing direction is stationarily arranged in the machine frame. Furthermore, the punch is drivingly connected to a rotatable cam disc through the intervention of a pick-up roller.
    Type: Grant
    Filed: November 29, 1977
    Date of Patent: June 24, 1980
    Assignee: Gebr. Hilgeland
    Inventor: Wilhelm Pieper
  • Patent number: 4204418
    Abstract: A machine and method whereby a metallic stick is pressed into a mold which is moved along two axes substantially perpendicularly to the stick so as to make the end of the stick follow the mold while it is softened by heat produced by passage of an electric current between the mold and the stick, the stick only being moved in its axial direction while the mold is only moved in the two substantially perpendicular directions to this axial direction.
    Type: Grant
    Filed: September 15, 1978
    Date of Patent: May 27, 1980
    Assignee: Nippon Dentan Co., Ltd.
    Inventor: Toraji Mochizuki
  • Patent number: 4168619
    Abstract: A single step in the form of a heavy forward displacing forging operation is used to manufacture cylindrically bored ferrous-metal multiple diameter nozzles with an outside diameter of at least 22 inches, weighing at least 4,000 lbs. and possessing an exterior configuration comprising a round cylindrical base section of largest diameter with an outwardly-extending flange at one extremity, spaced second cylindrical section of smaller diameter, and an interconnecting and intercommunicating frusto-conical section.
    Type: Grant
    Filed: April 17, 1978
    Date of Patent: September 25, 1979
    Inventor: Charles H. Moore
  • Patent number: 4148233
    Abstract: A punch for forming a fastener head has a shaped projection at each end and is releasably secured in a holder with one end abutting against a ledge on the inside of the holder and the other end extending beyond the holder. The shaped projections are formed simultaneously by a pair of hobs in one press stroke.
    Type: Grant
    Filed: March 29, 1978
    Date of Patent: April 10, 1979
    Assignee: Procor Limited
    Inventor: William H. Wang
  • Patent number: 4114217
    Abstract: A die assembly comprising a reinforcement case formed with a tapered bore, a forming die inserted into the tapered bore from therebelow, and a stock die supporting the forming die in fitting contact with the bottom of the forming die and formed at its lower portion with a guide stem of reduced diameter. The guide stem extends downward through the center of a threaded bore formed in the lower portion of the reinforcement case. A pushing-up member having a center bore through which the guide stem extends freely movably is screwed in the threaded bore of the reinforcement case and supports the stock die. The forming die and the stock die are formed with knockout pin passageways in alignment with each other.
    Type: Grant
    Filed: September 19, 1977
    Date of Patent: September 19, 1978
    Assignee: Akamatsu Alloy Tool Co., Ltd.
    Inventor: Motoji Akamatsu
  • Patent number: 4109503
    Abstract: There is disclosed a planar sheet having at least one longitudinal corrugation for substantially the entire width of the panel. On at least one end portion of the sheet the corrugation terminates into a plurality of smaller gathered corrugations resulting in closed ends. Apparatus is also disclosed for producing the aforementioned smaller gathered corrugations including an anvil having appropriate cavities therein and a punch system for upsetting a corrugated panel to produce said mini-corrugation.
    Type: Grant
    Filed: February 2, 1977
    Date of Patent: August 29, 1978
    Inventors: Jean Francon, Francis Francon
  • Patent number: 4096730
    Abstract: A forging press and method of forging to enable workpieces of exceptionally large diameter to be forged. The invention is an improvement over a press and method disclosed in an earlier patent in which a rectangular set of top dies is used with a circular set of bottom dies, and the bottom dies are indexed through a pattern of arcs to move a workpiece successively to positions in which it is forged throughout its area. The present invention utilizes a set of bottom dies which is of larger diameter than that of the indexing means and has overhanging edge portions. These portions are additionally supported at diametrically opposed locations where the force of the top dies is absorbed.
    Type: Grant
    Filed: July 1, 1976
    Date of Patent: June 27, 1978
    Assignee: United States Steel Corporation
    Inventor: Wayne A. Martin
  • Patent number: 4083219
    Abstract: Apparatus and method for forming cylindrical tubular lateral extensions on cylindrical or oval body tube by swaging them from around an oval opening, which is narrower along the sides to compensate for the body curvature, the apparatus including a circular male swaging die with a profile that tapers at progressively decreasing angles to the stroke direction, i.e. a series of progressively steeper conical surfaces or a sphere. The die may be a complete ball which is rolled into a formed body tube; positioned over an opening therein and pushed therethrough by a ram driven through the opposite, aligned opening. The body tube may then be inverted and another ball rolled therein to be pushed through the opposite opening.
    Type: Grant
    Filed: November 1, 1976
    Date of Patent: April 11, 1978
    Assignee: Grove Valve and Regulator Company
    Inventors: Marvin G. Combes, Roger L. Ripert
  • Patent number: 4073178
    Abstract: A device is provided for precision cold forging of hollow, spherical heads of ball-joint pivots of the type used in the steering and suspension joints of automobiles, which includes a pair of hemispherical forming dies closing on a joint plane passing almost through the center of the ball-joint. One of the dies containing the pivot rod of the ball-joint pivot is clamped onto a tool-holder unit against a bearing edge situated almost on a level with the center of the ball-joint and of the joint plane, with an end part thereof receiving a thrust from a flexible element which opposes the forming pressure of the hollow, spherical head and assures that the die is permanently supported on the bearing edge. Precision cold forging of hollow, spherical forms, mass-produced with finite dimensions is thus available.
    Type: Grant
    Filed: August 26, 1976
    Date of Patent: February 14, 1978
    Assignee: Regie Nationale des Usines Renault
    Inventors: Maurice Dutartre, Yves Roger
  • Patent number: 4061098
    Abstract: A process for bending on a press a metal sheet through a desired angle and an inner bend radius less than the thickness of the sheet, without causing damages such as cracking in a bend. According to this process, a metal sheet is first bent through an angle approximating a desired angle, with an inner bend radius being greater than the thickness of the metal sheet, and then the metal sheet thus bent is further bent through a desired angle, with the inner bend radius being less than the thickness of the metal sheet, and with the stretching of a material of the metal sheet on the outer side of the bend being suppressed.
    Type: Grant
    Filed: February 17, 1977
    Date of Patent: December 6, 1977
    Assignees: Toyota Jidosha Kogyo Kabushiki Kaisha, Hosei Brake Industry Company
    Inventors: Koji Horie, Takashi Mune
  • Patent number: 4055975
    Abstract: A process of precision forging of titanium or a titanium alloy in which the forging stock and a segmented die are first heated to forging temperature while separated, and are then assembled together and heated again to that temperature, with the stock being covered by a protective coating preferably containing glass grit, and the die sections being coated with lubricant. The heated die and contained heated forging stock are then inserted in a heated holder and the stock subjected to forging force, to partially but not completely deform the stock to the shape of the die cavity, following which the die and stock are separated and the stock allowed to cool, flashing is removed from the stock, the die is cleaned, the die and stock are recoated and then reheated separately and then together, and the stock is forged again to assume more closely the shape of the die cavity.
    Type: Grant
    Filed: April 1, 1977
    Date of Patent: November 1, 1977
    Assignee: Lockheed Aircraft Corporation
    Inventors: Tibor Serfozo, Rod F. Simenz
  • Patent number: 4045644
    Abstract: A welding electrode made of dispersion strengthened metal wherein the electrode tip is pressure formed or forged to reorientate and/or destroy the coaxial fiber structure and form a non-axial grain structure in the electrode tip portion. The electrode is produced in a method for pressure flowing a blank by applying axial pressure to pressure flow the blank transverse to the axially applied pressure whereby the overall strength of workpieces such as welding electrode rods is substantially increased.
    Type: Grant
    Filed: July 24, 1975
    Date of Patent: August 30, 1977
    Assignee: SCM Corporation
    Inventors: William M. Shafer, Anil V. Nadkarni
  • Patent number: 4034456
    Abstract: Ball-ender apparatus for securing an annular ball to a wire musical instrument string. A carriage reciprocable between front and rear positions carries a rotatable ball support spindle. An upstanding ball feed tube receives a column of balls from an oscillating hopper and has retractable gating pins for dropping a ball at a time on the forward end of the ball support spindle. Wire is fed behind the ball and past a substantially L-cross-section guide plate. The length of wire fed is determined in proportion to rotation of a timing wheel. A de-reeling device leads the wire from a supply reel in a serpentine path and reduces starting tension on the wire. Upon rearward movement of the carriage, spindle and ball, which severs the fed wire length upstream of the ball and forms the wire length into a U-shape about the ball, clamp actuator cones cause clamp members to engage the legs of said wire U-shape forward of the ball tightly.
    Type: Grant
    Filed: December 11, 1975
    Date of Patent: July 12, 1977
    Inventor: Robert H. Bowers
  • Patent number: 3991455
    Abstract: A ring assembly includes two side-by-side flat ring members of uniform rectangular cross-section each being split, with the confronting split ends having radially overlapping fingers to define a circumferentially sealing joint. The ring members are dimensioned to be received in a common piston groove with the ring members being non-rotatably coupled so that the joint of one member will always be rotationally spaced from the joint of the other to define an axial seal for the ring assembly. A non-rotational coupling is provided by an integral tab formed in one member and projecting transversely therefrom and received in a mating transverse recess in the other member, with the recess having a larger dimension than the tab to permit sliding movement of the ring members relative to each other within the groove. Two forms of tabs include a partially sheared and bent tab and a partially displaced shear plug.
    Type: Grant
    Filed: March 7, 1974
    Date of Patent: November 16, 1976
    Inventor: Alfred Bergeron
  • Patent number: 3958441
    Abstract: A skid resistant ribbed floor member has crack-free depressions formed in the ribs thereon using a punch and die in which the punch has a width greater than the transverse width of the rib and the die has an aperture generally less than the transverse width of the rib and less than the width of the punch.
    Type: Grant
    Filed: December 26, 1974
    Date of Patent: May 25, 1976
    Assignee: Aluminum Company of America
    Inventors: Roger C. Haddon, Jean-Pierre J. Habets
  • Patent number: 3937053
    Abstract: A die assembly for forming nuts or the like in which a die cavity is formed to extend into two abutting members of super hard alloy, the cavity extending through one member and having a bottom surface in the other. The hard alloy members rest on a hardened steel stock die and the three elements are shrink fitted in a reinforcement ring. A passageway communicates with the interface between the hard alloy members and extends to a position adjacent but spaced from the interface between those members. When forming pressure is applied to a workpiece in the cavity, the stock die yields resiliently to permit a slight separation between the hard alloy members and thus provide a vent passage for trapped air to the exterior of the assembly. The interface between the die members and the reinforcement ring permits such downward movement of the lower alloy die member but prevents upward ejection of the die members from the reinforcement ring upon operation of a work ejecting mechanism.
    Type: Grant
    Filed: August 27, 1974
    Date of Patent: February 10, 1976
    Inventor: Mototsugu Akamatsu