Means For Molding Powdered Metal Patents (Class 425/78)
  • Patent number: 4140449
    Abstract: Improvement of a press for powder metallurgy having one or more rotatably arms mounting horizontally and respectively on an axis which is set up vertically at suitable portion of front and or rear walls of housing of the press. The arm has a box for supporting a die set and a metal mold on an end. The die set and the metal mold being supported in the box are easily transferred to a receiving portion thereof of an entrance of the press by rotation of the arm to horizontal direction, and the transferred die set and the metal mold are installed in accurate portion of the press by hand or a driven power means.
    Type: Grant
    Filed: September 16, 1977
    Date of Patent: February 20, 1979
    Assignee: Yoshizuka Seiki Co., Ltd.
    Inventors: Katagiri Takeshi, Ozu Masaaki
  • Patent number: 4137026
    Abstract: A brickmaking press comprises a segmental ring, a brick shaping mold supported by the segmental ring in the mold cavity defined thereby, a clamping ring surrounding and enclosing the segmental ring, and the clamping and segmental rings defining an annular chamber maintained under fluid pressure.
    Type: Grant
    Filed: July 27, 1977
    Date of Patent: January 30, 1979
    Assignees: Veitscher Magnesitwerke-Actien-Gesellschaft, Oesterreichisch-Amerikanische Magnesit Aktiengesellschaft
    Inventor: Rudolf Gerstl
  • Patent number: 4134716
    Abstract: A punch press remotely disengageable from the punch drive mechanism, particularly useful where the press must operate in a hostile environment. The press includes a punch block, supporting one or more punches, which is laterally inserted into connection with the punch drive apparatus. A die set is provided for supporting one or more dies, and the die set is associated with the punch block such that the punch is guided into a preselected position relative to the die by the drive apparatus. A structural frame is provided for seating the die set, which can be laterally inserted and removed from the frame. Guide rails are also provided which can extend laterally from the frame and support the die set in a position removed from the normal operating position within the frame. The guide rails also support the die set in the operating position.
    Type: Grant
    Filed: September 23, 1977
    Date of Patent: January 16, 1979
    Assignee: Westinghouse Electric Corp.
    Inventor: Clarence D. John, Jr.
  • Patent number: 4126451
    Abstract: A powder-metallurgy process, product, and assembly particularly adapted for manufacturing plates of hard-to-work materials, such as chromium and its alloys, are disclosed. The assembly is formed by placing a metal powder into the cavity of a die and disposing one punch or two opposed punches to intrude into the cavity and enclose the powder. Preferably, the powder is compacted by applying pressure to the punches, and the punches are fixed to the die with their outer ends protruding from the die. The enclosed powder may be purified, outgassed, and sealed under vacuum. The enclosed powder is consolidated and elongated by heating and compressing, preferably by rolling one or more times in a conventional rolling mill. The composite product is cooled slowly and cut to the desired size. Remnants of the die and punch may serve as frame and backing for the consolidated powder layer. The plates have application, for example, as sputtering targets.
    Type: Grant
    Filed: March 30, 1977
    Date of Patent: November 21, 1978
    Assignee: Airco, Inc.
    Inventor: Harbhajan S. Nayar
  • Patent number: 4124338
    Abstract: A hot briquetting press having a stationary anvil and a reciprocating ram movable through a chip-box that includes a water-cooled jacket to remove excessive heat therefrom. The cooling jacket includes an arcuate wall that is spaced from the reciprocating ram a distance that permits a layer of discrete chips to be disposed therein as an insulation barrier intermediate the reciprocating ram and the water-cooled jacket to preclude the cooling of the hot chips adjacent the ram before they are pressed into a briquette.
    Type: Grant
    Filed: October 3, 1977
    Date of Patent: November 7, 1978
    Assignee: Combustion Engineering, Inc.
    Inventor: Robert D. Mitchell
  • Patent number: 4123210
    Abstract: A briquette forming apparatus for compressing a mass of metallic chips into uniformly dense briquettes. The chips are first heated to reduce their yield strength and to simultaneously remove volatile contaminants therefrom. The hot chips are then transferred to a reciprocating press where the chips are compacted in a flared die between a convex anvil and a reciprocating ram.
    Type: Grant
    Filed: October 3, 1977
    Date of Patent: October 31, 1978
    Assignee: Combustion Engineering, Inc.
    Inventor: Albert C. Schulz
  • Patent number: 4102679
    Abstract: An improvement in a powder metallurgic manufacturing process where metal powder is compressed and heated in a mould and heat is produced by conducting electric current through the mould and the metal powder as well as through at least one electrically resistive fireproof body in actual contact with the mould where heat produced in the body is transferred to the mould and the metal powder. The improvement comprises maintaining electric tension between 2 and 200 volts; the current efficiency per unit volume of the mould between 20 and 200 W/cm.sup.3 ; and the resistivity of the electrically resistive fireproof body between 0.03 and 100 ohm .times. cm.
    Type: Grant
    Filed: December 6, 1976
    Date of Patent: July 25, 1978
    Assignee: L.A. Levanto Oy
    Inventor: Aukusti Arvela
  • Patent number: 4087221
    Abstract: Apparatus for forming a powder metal compact having an undercut or a reentrant angle in which the portion of the die that results in the compact undercut or reentrant angle is axially movable relative to a stationary part of the die means along the axis of pressure in order to permit automatic straight line ejection of the compact.
    Type: Grant
    Filed: January 31, 1977
    Date of Patent: May 2, 1978
    Assignee: Remington Arms Company, Inc.
    Inventors: Harold C. Munson, Ronald A. Sadlon
  • Patent number: 4080128
    Abstract: An apparatus for producing compacts having layers of different composition. More particularly, each metal powder layer is charged in a separate work station and each is pressed in a separate work station with an individual constant pressing pressure. This is achieved by moving a number of pressing tools corresponding to the number of work stations intermittently from station to station by cyclic interchange. After each movement, charging, pressing and ejecting occur simultaneously at the respective work stations.
    Type: Grant
    Filed: January 13, 1977
    Date of Patent: March 21, 1978
    Assignee: Siemens Aktiengesellschaft
    Inventors: Horst Schreiner, Bernard Rothkegel
  • Patent number: 4065299
    Abstract: A magnesium reclamation process whereby magnesium and magnesium alloy fines, chips and scraps may be recovered and remelted for reuse. The method is comprised of the steps of pelletizing the magnesium by first compacting the magnesium with a low pressure press so as to initially expel the majority of the air, followed by a high pressure press under a controlled environment to form a compact pellet. The pellets are then melted either by stacking on the cold heel of a pot and heating under a controlled environment or pre-heating in a basket over a melt, and then subsequently immersing the load. Melting can also be accomplished by controlled melting, utilizing an induction melting furnace whereas temperature can be slowly increased. Pelletizing pressures range from approximately the yield pressure to the cold welding pressure of the material being reclaimed. A typical pelletizing environment is 20% SF.sub.6 and 80% CO.sub.2 and a suitable melting environment is 98% CO.sub.2 and 2% SF.sub.6.
    Type: Grant
    Filed: October 23, 1975
    Date of Patent: December 27, 1977
    Assignee: Teledyne Industries, Inc.
    Inventors: Gregory Todhunter Roberts, David Vincent Owens, Raymond Frank Goodspeed
  • Patent number: 4061452
    Abstract: A press apparatus for compacting powder material into generally spherical articles by way of a tooling arrangement comprising a die having a bore, a punch having an upper face defining a generally hemispherical cavity reciprocably movable along the axis of the die bore and a counterpunch positionable over the opening of the die bore. The lower face of the counterpunch defines a generally hemispherical cavity of the same diameter as the generally hemispherical cavity defined by the face of the punch. The generally hemispherical cavities are in alignment with each other and define a spherical mold cavity. During the compacting step, the counterpunch is positioned with its lower face abutting the upper surface of the die plate and compaction of the powder material is achieved entirely by movement of the punch in an upward direction.
    Type: Grant
    Filed: January 21, 1977
    Date of Patent: December 6, 1977
    Assignee: Wolverine Aluminum Corporation
    Inventor: Raymond P. DeSantis
  • Patent number: 4061453
    Abstract: An apparatus for compacting powder material into a mold cavity formed at least between an upper and a lower reciprocally movable punch. The lower punch reciprocates in the center bore of a die and has an end face defining a portion of the mold cavity. The upper punch is reciprocable so as to be placed over the die bore and has an end face defining another portion of the mold cavity. The upper punch end face is coated with, or made of, an elastomeric material. The upper face of the lower punch may be flat or contoured. The compaction of the powder material in the mold cavity is accomplished by the upward movement of the lower punch which forces the powder material to conform to the configuration of the mold cavity. After compaction, the upper punch is withdrawn and the compacted product is ejected.
    Type: Grant
    Filed: January 21, 1977
    Date of Patent: December 6, 1977
    Assignee: Wolverine Aluminum Corporation
    Inventor: Raymond P. DeSantis
  • Patent number: 4060359
    Abstract: An isostatic press comprises a pressure vessel defined by a tubular jacket and by two end plugs. The jacket is, in the direction of its longitudinal axis, displaceble between two positions. The jacket surrounds a third plug centrally located between the two positions of the jacket so that, when the jacket is in one of its end positions, the central plug closes one end of the jacket, and vice versa. The two jacket positions alternatingly serve as pressing and charging positions so as to permit recharging of the press at one position simultaneously with carrying out a pressing operation at the other position. This arrangement approximately doubles the productivity of the press.
    Type: Grant
    Filed: February 9, 1977
    Date of Patent: November 29, 1977
    Assignee: AB Carbox
    Inventors: Sten Trolle, Ake Jonson
  • Patent number: 4056347
    Abstract: An apparatus for isostatic compression of pulverulent materials comprises a pressure vessel housing two liquids which by a flexible diaphragm are held out of mutual contact. One liquid flows through a pumping circuit and constitutes a primary pressurization agent the pressure of which is, via the diaphragm, transferred to the other liquid surrounding a basket enclosing a soft walled container for the material to be compacted. According to the invention the basket is deformable so that the diaphragm can be pressed against it without being damaged by reactional forces. The result of the deformation capability of the basket is a reduction of the overall size of the pressure vessel.
    Type: Grant
    Filed: December 27, 1976
    Date of Patent: November 1, 1977
    Assignee: AB Carbox
    Inventor: Sten Trolle
  • Patent number: 4053267
    Abstract: A unitary punch and die assembly for tooling a powder material compacting apparatus, or press, the assembly comprising a die plate mounted in the press table, which removably holds a die bushing clamped in position by a threaded retainer provided with a peripheral thread of the buttress type, and a punch removably supported in a punch holder plate actuatable along guideposts supported by the die plate. A second plate slidably mounted in the guideposts and reciprocated by the press ram is rigidly interconnected with the punch support plate for reciprocation thereof. For compacting articles such as toroidal articles, cylinders, and the like, a core rod supported by an appropriate support plate adjustably fastened on the guide posts projects through a longitudinal bore provided in the punch and punch support plate.
    Type: Grant
    Filed: October 22, 1976
    Date of Patent: October 11, 1977
    Assignee: Wolverine Aluminum Corporation
    Inventor: Raymond P. DeSantis
  • Patent number: 4047864
    Abstract: An apparatus for compressing powder material into at least partially spherical articles, comprising a die and upper and lower reciprocally movable punches. The die has a center bore through which the lower punch is reciprocable. The wall at the upper part of the die bore is enlarged to form a spherical zone portion of a hemispherical cavity. The end face of the lower punch has a concave shape to form a segment of the hemispherical cavity when the face of the lower punch is flush with the die cavity wall. The lower face of the upper punch defines a hemispherical cavity which mates with the hemispherical cavity of the die. In operation, the bore and die cavity are charged with powder material and the upper punch is brought into engagement with the die. A compaction stroke by the lower punch then forces the powder material into the spherical cavity. The upper punch is then withdrawn and the compacted spherical article is removed from the die.
    Type: Grant
    Filed: October 6, 1975
    Date of Patent: September 13, 1977
    Assignee: Wolverine Aluminum Corporation
    Inventor: Raymond P. DeSantis
  • Patent number: 4023966
    Abstract: This invention involves a method for the hot isostatic compaction of particulate material into an article of intricate configuration. It comprises providing a removable pattern in the appropriate precompaction configuration of the article to be produced, coating the pattern with a first layer of conductive material and a second layer of metallic material, the two layers cooperating to provide a self-supporting and gas-impervious shell around the pattern and removing the pattern from the shell to provide a self-supporting and gas-impervious container having an internal configuration corresponding to the precompaction shape of the article to be produced. The container is then filled with particulate material, evacuated and sealed, and isostatically compacted in a pressure vessel at elevated temperature until the particulate material is compacted into a dense article of complex shape. The container is thereafter removed to obtain the compacted article.
    Type: Grant
    Filed: November 6, 1975
    Date of Patent: May 17, 1977
    Assignee: United Technologies Corporation
    Inventors: Joseph Frederick Loersch, Peter Alan Hurwitz, Lester Warren Jordan
  • Patent number: 4017570
    Abstract: The preparation of three dimensional skeletal structures using the step of deforming rounded beads to form a mold or matrix is described. A filler material is introduced and then rigidified to form the skeletal structure. The deformable beads are composed of materials which deform upon compression or expansion due to pressure from adjacent beads and included, for instance, metals, waxes, salts, polymers, and ceramic compositions in their plasticly deformable states. The filler material which rigidifies to form the skeletal structure can be composed of solidifiable materials such as metals, polymers, or ceramic compositions. The solid material volume of the skeletal structure so formed upon removal of the beads is between about 2% to 20% of a corresponding volume of a non-skeletal solid material. The corresponding porosities representing the interconnected void volumes are between about 80% and 98% of a corresponding volume of a non-skeletal solid material.
    Type: Grant
    Filed: April 2, 1973
    Date of Patent: April 12, 1977
    Assignee: Chemotronics International, Inc.
    Inventors: Warren A. Rice, Clarence S. Vinton, Hugh Richard Norris
  • Patent number: 4014634
    Abstract: A powder molding press, for compression-molding a raw powder between a pair of metal molds coupled to a pair of metal mold securing devices. At a preset spacing, the movement of the metal mold securing devices toward each other is electrically detected in order to cut off the driving means advancing the metal mold securing devices. In addition, the movement of the metal mold securing device is mechanically stopped by means of stoppers, with the result that the final position of the metal molds can be precisely regulated.
    Type: Grant
    Filed: May 26, 1976
    Date of Patent: March 29, 1977
    Assignee: Iwatani & Co., Ltd.
    Inventor: Masayuki Hoshino
  • Patent number: 4013394
    Abstract: The invention relates to means for establishing an equalized pressure across the insulating sheath of a hot isostatic press system. Tubes are positioned in the outer, insulation portion of the sheath to provide a substantially resistance free passage between a source of high pressure gas input to the system and the upper portions of the sheath. The invention also tends to reduce convection currents in the furnace chamber.
    Type: Grant
    Filed: August 18, 1975
    Date of Patent: March 22, 1977
    Assignee: National Forge Company
    Inventors: Donald E. Witkin, Arnold G. Bowles
  • Patent number: 4009977
    Abstract: Superior densification of particulate material is achieved by the superimposition of an axial load on material under isostatic pressure. Such an axial load is imposed through the use of a floating plunger, eliminating the need for an external compacting plunger inserted through the isostatic compacting cylinder. This floating plunger is composed of two end sections, having different surface areas. One end section is acted on by the pressurized media, while the other end section (generally the smaller) coacts on the compact. Pressurization of the chamber with an isostatic media, thereby results in a stress along the vertical axis of the compact, which is different from the isostatic stress on the circumferential surface of the compact.
    Type: Grant
    Filed: April 29, 1976
    Date of Patent: March 1, 1977
    Assignee: United States Steel Corporation
    Inventor: Hung-Chi Chao
  • Patent number: 4008023
    Abstract: A compactible mold pack useful for forming articles of complex inner and outer contour and substantial uniform density directly from metal powder is disclosed. The mold pack includes first and second porous, compactible mold sections defining therebetween a cavity in the outer contour of the article to be made, a porous, compactible core suspended in the cavity to define the inner contour and metal powder disposed in the cavity between the mold sections and core, the mold sections and core having an initial porosity substantially equal to that of the metal powder to be consolidated. The mold pack may be compacted to size by conventional forging and pressing techniques to consolidate the metal powder therein into the desired article.
    Type: Grant
    Filed: June 24, 1976
    Date of Patent: February 15, 1977
    Assignee: United Technologies Corporation
    Inventor: Joseph M. Wentzell
  • Patent number: 4008021
    Abstract: An apparatus for forming a sinterable compact of a powder comprises a pair of respective shafts displaceable toward one another by the action of respective cams and serving to displace opposing ram members to compact a powder between them. Respective plates carrying the ram members are entrained with the shafts and are displaced in the opposite direction by respective pairs of pneumatic cylinders. The rams are thereupon displaced at high rate against the precompacted powder by energizing a disk-shaped coil which repels electrodynamically the plate carrying the rams.
    Type: Grant
    Filed: May 9, 1975
    Date of Patent: February 15, 1977
    Assignee: Schwelmer Eisenwerk Muller & Co. GmbH
    Inventors: Renzo Fedrigo, Bartolomeo Borrini, Vittorio Garattini, Giovanni Pino
  • Patent number: 4005956
    Abstract: Activation of metallic powders by subjecting the powder to bombardment with electrons, ions, or molecules in an inert or reductive atmosphere. Improved densities result in sintering, as do improved catalytic actions. Simultaneous pulverization of coarse particles or bodies is also achieved where desired. The pretreatment is, in some instances, combined with loading the activated particles directly into a mold, for compaction or sintering, preferably with some additional activation, all done in an integrated system. The corpuscular particle bombardment of powder is advantageously effected by exposing the powder to a glow discharge produced between a pair of electrodes in a rarefied non-oxidizing atmosphere with the pressure of the atmosphere and the distance between the electrodes being such that their product in mm Hg times cm is in a range between 10.sup.-2 and 10.
    Type: Grant
    Filed: October 21, 1975
    Date of Patent: February 1, 1977
    Assignee: Inoue-Japax Research Incorporated
    Inventor: Kiyoshi Inoue
  • Patent number: 4000231
    Abstract: Method of using an opposed ram hydraulic press for compressing powder in a die to form a compact. The press including hydraulic and electrical control circuits for decompressing the compact progressively and smoothly to a relatively low punch hold down force and maintaining this hold down force relatively constant until the compact is substantially completely ejected from the die.
    Type: Grant
    Filed: September 16, 1974
    Date of Patent: December 28, 1976
    Assignee: Hydramet American Inc.
    Inventor: William M. Peterson
  • Patent number: 3995979
    Abstract: An apparatus for lubricating the internal wall of moulds for blanks comprises a corona charger for charging electrically the lubricant which is then injected into the mould. This latter is maintained at an electric potential such as to attract the lubricant and cause it to be deposited on the inside walls of the mould.
    Type: Grant
    Filed: November 1, 1974
    Date of Patent: December 7, 1976
    Assignee: Ing. C. Olivetti & C., S.p.A.
    Inventor: Renzo Fedrigo
  • Patent number: 3989438
    Abstract: A method of producing hot pressed products, especially products of complex shapes, wherein the material from which the component is formed is hot pressed between a plurality of die parts of which at least one is of substantially uniform density and substantially compressible. This enables the shape of the die part to conform exactly or nearly so to the shape of the body being sintered throughout hot pressing, thereby resulting in obtainment of products of complex shapes.
    Type: Grant
    Filed: July 28, 1972
    Date of Patent: November 2, 1976
    Assignee: Joseph Lucas (Industries) Limited
    Inventors: Dexter William Smith, Roland John Lumby
  • Patent number: 3988088
    Abstract: Apparatus for converting particulate metallic matter into a billet or a forged article in which the material is fed in measured quantity from a hopper to a furnace for outgassing and other heat treatment and thence to a press in which the particulate material is compacted into a container or mold to form either a billet or forged article. When the billet is formed, the press also applies a cover to the container to keep the material free of contamination until a later heat treatment or forging operation. Mechanism is provided for removing the completed billet or mold from the press and insertion of a new container.
    Type: Grant
    Filed: December 4, 1975
    Date of Patent: October 26, 1976
    Assignee: United Technologies Corporation
    Inventors: Jerry A. King, Vernon F. Manz, Donald G. MacNitt, Jr.
  • Patent number: 3986803
    Abstract: In a compacting press, the container in which the material is compacted is sealed by a cover which is positioned in the open end of the filled container before the container is removed from the press. The cover positioning device is movable into and out of operative position to permit operation of the press and the apparatus is remotely controlled externally of the vacuum chamber in which the press is located.
    Type: Grant
    Filed: December 4, 1975
    Date of Patent: October 19, 1976
    Assignee: United Technologies Corporation
    Inventor: Donald G. MacNitt, Jr.
  • Patent number: 3981725
    Abstract: An industrial process and system are described for forming finished parts from powder metal. Known steps of compacting the metal powder into a preliminary part having an intermediate shape, followed by heating and forming the preliminary powder into a finished part having a final shape and density are integrated into a single automated process and system by steps and equipment which provide for a rearranging of a continuous flow of preliminary parts into separate batches at a sintering station so that the separate batches of the preliminary parts can be uniformly heated to a selected sintering temperature level. After sintering, the separate batches are removed from the sintering station and rearranged back into a flow of parts which can be conveyed to a final forming station. This arrangement provides for advantages in starting up and stopping the system in a typical industrial application.
    Type: Grant
    Filed: March 6, 1974
    Date of Patent: September 21, 1976
    Assignee: The Gleason Works
    Inventor: William F. Dixon
  • Patent number: 3973886
    Abstract: A hot isostatic press which includes a mantle interposed between heating elements and the wall of the press and means associated with the press for equalizing the pressure on both sides of said mantle during operation of the press or during pressurization or depressurization.
    Type: Grant
    Filed: May 6, 1975
    Date of Patent: August 10, 1976
    Assignee: National Forge Company
    Inventor: Andrew Stephenson Dalgleish Crum
  • Patent number: 3972670
    Abstract: A press for making castings of powder or granular materials, wherein a ram provided on a press frame, for the movement of a first press tool part, in particular an upper die, as well as a linkage provided on the press frame, for the movement of a second press tool part, in particular a mold, are guided movable in the same direction in relation to a clamping plate provided for the attachment of a third press tool part, in particular a lower die, and the ram is firmly connected to a ram traverse, through which, during an adjustable phase of its approach to the clamping plate, it transmits a movement produced by a driving device, in particular a toggle-lever drive, to a linkage traverse firmly connected to the linkage, the transmission being effected by means of a thrust piece which, in order to make possible a residual stroke of the ram for the purpose of secondary compression of the pressed casting, is deflected laterally when the linkage traverse reaches a predetermined final press position.
    Type: Grant
    Filed: May 20, 1975
    Date of Patent: August 3, 1976
    Assignee: Gebruder Netzsch, Maschinenfabrik
    Inventor: Ernst August Wilhelm Henkel
  • Patent number: 3972662
    Abstract: The invention is concerned with apparatus for manufacturing gas turbine engine components e.g. guide vanes and blades, in dense silicon nitride starting with silicon nitride in a powder form.Guide vanes are usually in the form of an aerofoil portion and two shroud portions and according to the invention, the aerofoil portion is made in a first mould by hot pressing a mixture of silicon nitride powder and a fluxing agent, such as magnesia. The formed aerofoil is placed in a second mould so that each end extends partly into a space which is to be filled with a further mixture of silicon nitride powder and a fluxing agent. The further mixtures are hot pressed both to form the shroud portions and to amalgamate the shroud portions with the aerofoil portion.Features, such as, flanges and webs can be formed in the shrouds during the moulding process or they can be machined into the shrouds after the vane is removed from the second mould.
    Type: Grant
    Filed: November 24, 1975
    Date of Patent: August 3, 1976
    Assignee: Rolls-Royce (1971) Limited
    Inventor: Jack Raymond Bird
  • Patent number: 3943617
    Abstract: A method of converting scrap or other small pieces of metal into a useful, commercial product while maintaining the metal in a solid state. According to the process, the pieces are maintained together for further processing. They are impacted, while heated, to produce a metal body and thereafter subjected to continued impaction so that the pieces forming the body are welded together into a cohesive, homogeneous slab. There is also disclosure of a novel press and method of operating the press. The press is of the harmonic type. Its novel aspects include control of movement of novel platens during rotation of shafts which drive the platens and perimetral constraint of a workpiece being forged to achieve rapid impaction and self feed of a workpiece.
    Type: Grant
    Filed: July 16, 1973
    Date of Patent: March 16, 1976
    Assignee: Republic Steel Corporation
    Inventors: Mark E. Whalen, Norman W. Trepanier, Robert A. Kraus, Joseph W. Malleck
  • Patent number: 3938920
    Abstract: The specification describes a device for limiting the pressing force to a pre-established value in mechanical presses with an upper punch, which is mounted on the upper tup via a hydraulic cushion, which is connected via an overpressure valve and a pump with a pressure medium supply held in a pressureless condition. At the connection between the hydraulic cushion and the excess pressure valve, a duct is connected which opens in a pressureless manner and this duct is closed by valve whose closing pressure can be adjusted.
    Type: Grant
    Filed: February 11, 1974
    Date of Patent: February 17, 1976
    Assignee: Dorst-Keramikmaschinen-Bau
    Inventor: Roland Fleissner