With Associated Bath Of Liquid Flux Or Filler Patents (Class 228/31)
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Patent number: 6164516Abstract: An automatic soldering apparatus includes a conveyor for conveying a printed circuit board along a predetermined path, a heater located below the conveyor and adapted to heat the lower surface of the printed circuit board on which leads of chips and other electronic parts are to be electrically connected to circuits as printed, a flux applicator located downstream of the heater and arranged to apply a molten flux to the surface of the printed circuit board, and a supply of solder located downstream of the flux applicator and arranged to solder the leads to the circuits. The flux applicator includes a supply of flux for feeding flux in solid form at room temperature, a heater for heating the flux to a temperature above its melting point to provide a molten flux, and a spray nozzle for spraying the molten flux to the surface of the substrate.Type: GrantFiled: June 9, 1998Date of Patent: December 26, 2000Assignee: Senju Metal Industry Co., Ltd.Inventors: Masahiro Watanabe, Hoshiro Takahashi
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Patent number: 6143639Abstract: Methods of forming electrically conductive interconnections and electrically interconnected substrates are described. In one implementation, a first substrate having an outer surface is provided and a layer of material is formed thereover. Openings are formed within the layer of material and conductive masses are formed within the openings. A second substrate having conductive interconnect surfaces is provided. The conductive interconnect surfaces are then contacted with the conductive masses and deformed thereby. In one aspect, the interconnect surfaces are deformed in part by portions of the layer of material proximate the conductive masses. In another aspect, the layer of material is removed and the interconnect surfaces are deformed by the conductive masses themselves.Type: GrantFiled: October 29, 1999Date of Patent: November 7, 2000Assignee: Micron Technology, Inc.Inventors: Curtis M. Medlen, Mark E. Tuttle
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Patent number: 6110760Abstract: Methods of forming electrically conductive interconnections and electrically interconnected substrates are described. In one implementation, a first substrate having an outer surface is provided and a layer of material is formed thereover. Openings are formed within the layer of material and conductive masses are formed within the openings. A second substrate having conductive interconnect surfaces is provided. The conductive interconnect surfaces are then contacted with the conductive masses and deformed thereby. In one aspect, the interconnect surfaces are deformed in part by portions of the layer of material proximate the conductive masses. In another aspect, the layer of material is removed and the interconnect surfaces are deformed by the conductive masses themselves.Type: GrantFiled: February 12, 1998Date of Patent: August 29, 2000Assignee: Micron Technology, Inc.Inventors: Curtis M. Medlen, Mark E. Tuttle
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Patent number: 6065552Abstract: An earth-boring bit has cutting elements inserted within holes in the cutter support. The cutting element has a body of a fracture-tough material, preferably tungsten carbide which contains a binder of a soft metal. A layer of a composite carbide which is substantially free of a binder is attached to the cutting end of the body. One cutting element has a chisel-shaped cutting end with two flanks that converge. One of the flanks has the layer of binderless carbide. This insert is located at a junction between the gage surface and heel surface for engaging the sidewall of the bore. Also, gage inserts located in the gage surface have outer ends containing a layer of binderless carbide.Type: GrantFiled: July 20, 1998Date of Patent: May 23, 2000Assignee: Baker Hughes IncorporatedInventors: Danny E. Scott, James L. Overstreet
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Patent number: 5897927Abstract: A method for permanently sealing an ultra-high vacuum within a glass enclosure. This is accomplished by first forming a hole, either in one of the flat plates that form the enclosure or in one of the standoffs that separate the plates, and then sealing a metal tube to the glass. In one embodiment, the metal tube is positioned so as to be partly inside the hole while in another a flange at the end of the tube is positioned to cover the hole. In both cases, a glass frit paste is then applied all around the glass metal interface. This is followed by heating so that the frit softens and becomes a glass-to-metal seal. Once the structure has cooled down the attached metal tube is used as a pumping port to evacuate it and, while still under vacuum, the metal tube is pinched off to form a permanent seal.Type: GrantFiled: June 30, 1997Date of Patent: April 27, 1999Assignee: Industrial Technology Research InstituteInventors: Kuang-Lung Tsai, Chung-Hsing Chao, Wei-Chiang Chen
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Patent number: 5549237Abstract: An apparatus for coating and bonding parts in a vacuum includes a floating mount assembly holding one part and applying a bonding load to the parts. A pivoting mount assembly holds one part and is pivoted between a coating position and a bonding position. At least one coating source is provided for depositing a thin film of a metal onto a surface of each of the parts to improve the cold weld between the two parts. A restraining lever controls the application of the bonding load to the parts. The coating and bonding process occurs in a vacuum chamber with a single set-up.Type: GrantFiled: February 16, 1995Date of Patent: August 27, 1996Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Richard C. Oeftering, Floyd A. Smith
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Patent number: 5261589Abstract: Apparatus for cold butt welding of wire provides a die made in one or two pieces with square or angled ends. Its four members can move in both horizontal and vertical directions and still maintain their alignment. Spring forces, similar to those in tuning forks, help maintain alignment without adjustment. The die can be "tuned" for optimal performance with a particular kind or size of wire. Making the die from a single piece of metal greatly simplifies its manufacture.Type: GrantFiled: August 19, 1992Date of Patent: November 16, 1993Inventor: Raymond Williams
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Patent number: 5238175Abstract: Disclosed is a method and apparatus for applying flux and solder in order to attach connectors to printed circuit boards (PCBs). Flux is applied to the connector tails and the PCB pads by means of a roller mounted above a flux reservoir. The piece parts are then exposed to a solder wave such that the solder sticks only to the selected area to which the flux was applied.Type: GrantFiled: July 29, 1992Date of Patent: August 24, 1993Assignee: AT&T Bell LaboratoriesInventors: Ronald R. Hughey, Joseph M. Salva
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Patent number: 5148958Abstract: A cold welding system in which a dual sputtering device is rotated into a coating position between two stationary aligned substrates on a press and simultaneously coats both substrates and then is rotated out of the coating position so the coated substrates can be pressed together.Type: GrantFiled: December 23, 1991Date of Patent: September 22, 1992Assignee: Xerox CorporationInventors: Joseph Eskandari, Russell B. Rauch
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Patent number: 5147085Abstract: The machine is provided with a set of two pairs of die halves 60, 62 (FIG. 7) mounted in a framework on hydraulically actuated piston and cylinder assemblies. The die halves 60 and 62 of each pair are relatively radially reciprocable to grip or release a workpiece 102, 104 and the two pairs of die halves are relatively axially reciprocable to effect cold pressure welding together of end portions of the workpieces 102, 104. Adjoining end faces of the die halves are formed with nose portions 100 having inner anvil edges for effecting welding flash removal from the workpieces.Type: GrantFiled: October 5, 1990Date of Patent: September 15, 1992Assignee: BWE LimitedInventors: Daniel J. Hawkes, Leslie J. Webb, Douglas E. Anderson
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Patent number: 5116228Abstract: A method and apparatus is provided for forming bumps on a plurality of IC chips arranged in a checkered pattern on a wafer. The bumps are formed from bump bases fixed to each IC chip. A forming tool having a recessed part of a height that is greater than the height of the bump bases is used to deform the bump bases into bumps. The forming tool is pressed by an elevating driving device against the bump bases under pressure sufficient to deform a respective part of each of the bump bases secured to each IC chip into a shape corresponding to that of the recess defined by the forming tool.Type: GrantFiled: October 23, 1989Date of Patent: May 26, 1992Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Akira Kabeshita, Yoshifumi Kitayama
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Patent number: 4896813Abstract: Metals to be bonded are drawn from pay-off reels and passed around holding rollers which are grounded cathodes, each roller being partially exposed in an etching chamber having an anode area at least three times the exposed area of the cathode. Each chamber has an inert gas at from 10.sup.-4 to 10.sup.-1 Torr and is subjected to RF power with a frequency from 1 to 50 MHz, which by a magnetic field produced by fixed magnets in the holding roller produces a glow discharge plasma which etches the metal in the chamber. Etched surfaces of the strips are then rolled together in a vacuum of from 10.sup.-6 to 10.sup.-3 Torr and a temperature to 300.degree. C. at a rolling pressure sufficient to effect a thickness reduction from 0.1 to 30%.Type: GrantFiled: April 3, 1989Date of Patent: January 30, 1990Assignee: Toyo Kohan Co., Ltd.Inventors: Kinji Saijo, Tsukasa Fujimura, Kazuo Yoshida
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Patent number: 4844320Abstract: A displacement transducer is used to continuously monitor the distance between two fixtures securing parts to be welded. The signal from the displacement transducer is used to stop the welding process when a desired amount of material has been extruded from the weld. The control strategy will automatically take into account part nonuniformities that normally result in poor welds in welding processes that use time as the control variable.Type: GrantFiled: November 1, 1988Date of Patent: July 4, 1989Assignee: General Electric CompanyInventors: Vijay K. Stokes, Louis P. Inzinna
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Patent number: 4821412Abstract: A method of production of an electric contact including a contact base member of one metal and a contact member of another metal of hardness lower than that of the contact base member joined to the contact member at one end portion thereof, with the method comprising the steps of forming a blind hole at the one end portion of the contact base member and applying pressure simultaneously to the contact base member and the contact member after the contact member is inserted and filled in the blind hole, to thereby cause the metals of the two members undergo plastic deformation to join them together in intimate contact with each other.Type: GrantFiled: June 28, 1985Date of Patent: April 18, 1989Assignee: Hitachi, Ltd.Inventors: Tatsuhiro Tani, Masaaki Ishiguri, Rokuro Kikuchi, Akio Ohyama
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Patent number: 4815648Abstract: A hand-held welding device utilizes a multiple upset cold pressure welding technique to join abutting end surfaces of a pair of wire members. The welding device includes a pair of spaced-apart, parallel tie rods for supporting a stationary V-block in spaced apart relationship with a moveable V-block. A welding die assembly is positioned between and is actuated by the two V-blocks. An end plate is secured to one end of the tie rods adjacent the stationary V-block, while a fixed handle is adjustably secured to the opposite end. A moveable handle is pivotally mounted relative to the fixed handle and includes a working roller which engages the moveable V-block to force the V-blocks against the die assembly. As the V-blocks are forced against the die assembly, the die assembly is operated to force the ends of the wire members against one another to form a cold pressure weld.Type: GrantFiled: October 26, 1987Date of Patent: March 28, 1989Assignee: Heintz CorporationInventor: Walter J. Rozmus
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Patent number: 4772498Abstract: A capillary for use in ball bonding tools designed to bond metal leads to the bonding pads on a microchip and pads or leads on a chip support is formed by chemically vapor depositing a substantially smooth silicon carbide coating having high electrical resistivity onto a substrate which is then removed by etching or combustion.Type: GrantFiled: November 20, 1986Date of Patent: September 20, 1988Assignee: Air Products and Chemicals, Inc.Inventors: Robert Bertin, Michael B. Miller, Burl M. Moon, Robert C. Post
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Patent number: 4744502Abstract: There is described an improved process for the production of tri-metallic contact rivets, in the course of which a cylindrical slug is formed with increased diameter under constant plastic deformation (upsetting) from three wire segments, and on this slug a head is then formed on one end by transformation.Type: GrantFiled: March 26, 1982Date of Patent: May 17, 1988Assignee: Dr. Eugen Durrwachter Doduco Kg.Inventor: Erwin Bollian
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Patent number: 4709844Abstract: The bonding apparatus has a holding device, a pressing device for pressure welding substances to be bonded to each other, and a superhigh vacuum bonding chamber provided with the holding device and the pressing device. A superhigh vacuum bonding preparatory chamber is connected with the superhigh vacuum bonding chamber through a gate valve and a conveyor is arranged for conveying the substances to be bonded between the superhigh vacuum bonding preparatory chamber and the superhigh vacuum bonding chamber. The preparatory chamber is provided with a rotary preparatory table having a plurality of stages for releasably supporting holders for holding the substances to be bonded, the preparatory table being moved to successive positions to register with the conveyor.Type: GrantFiled: March 13, 1986Date of Patent: December 1, 1987Assignees: Life Technology Research Found., Hiroyasu Funakubo & Sumitomo Elec. Ind., Ltd.Inventors: Yukio Sekiguchi, Hiroyasu Funakubo, Hitoyuki Sakanoue, Osamu Komura
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Patent number: 4684544Abstract: Solder flux is applied to the face of a printed circuit board (24) or the like by flowing a foam (30) of liquid flux bubbles upwardly through the top of a chimney flue (10) and into contact with the board face which is top passed over the top of the flue. The size of bubbles adjacent the face of the board is controlled by placing a grid screen (26) within and immediately beneath the top of the flue. The openings (26a) in the grid screen allow passage therethrough of smaller bubbles (34) but prevent passage of larger bubbles (32). The force of the board face on the foam urges the larger bubbles downwardly into contact with the grid screen where the grid wires of the screen pierce and thereby break the larger bubbles into smaller bubbles which then rise to the face of the board.Type: GrantFiled: February 19, 1986Date of Patent: August 4, 1987Assignee: General Motors CorporationInventor: Richard K. Arnett
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Patent number: 4619396Abstract: A cold pressure-welding apparatus has a pressure-welding load detector and a displacement detector for detecting the displacement of pressure-welding parts which are mounted on a cold pressure-welding apparatus main body; and an arithmetic operation control circuit which receives output signals from the detectors to detect yield points on a load-displacement curve, calculates an optimum load for optimally performing cold pressure-welding on the basis of a yield load at a second yield point, and outputs to the cold pressure-welding apparatus main body a signal for stopping cold pressure-welding when an actual pressure-welding load reaches the optimum load.Type: GrantFiled: September 17, 1984Date of Patent: October 28, 1986Assignee: Kabushiki Kaisha ToshibaInventor: Toshio Yamamoto
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Patent number: 4614292Abstract: A die bonder for bonding a semiconductor die to a substrate is disclosed. The die bonder comprises a support assembly within a frame, which assembly supports an arm. Attached to said arm is a means for holding a die, e.g. a vacuum collet. A variable electrical scrubbing means comprises a plunger which oscillates reciprocally within an electromagnetic coil and contacts the arm, or a tab integral with said arm. This provides a corresponding uniform scrubbing action, perpendicular to said arm in the plane of the interface between the die and the substrate, between a die held by the holding means and a solder material interposed between the die and substrate.Type: GrantFiled: September 30, 1985Date of Patent: September 30, 1986Assignee: RCA CorporationInventors: Carl Polansky, Frank Z. Hawrylo
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Patent number: 4541559Abstract: A method of making electrical connections between metal foils laminated to opposing surfaces of a flexible insulating layer, such as may be configured with spiral patterns in the respective metal foils to form inductive-capacitive circuits useful as detectable markers in RF antipilferage systems, and wherein an electrical connection is provided between the opposing foils by first extruding the laminate to shear the insulating layer and to contact the opposing metal foils in the vicinity of the sheared insulator layer and by subsequently forcing the extrusion back into a substantially planar relationship relative to the remainder of the laminate.Type: GrantFiled: November 16, 1983Date of Patent: September 17, 1985Assignee: Minnesota Mining and Manufacturing CompanyInventor: Philip W. O'Brien
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Patent number: 4468161Abstract: In a preferred embodiment, a metal nut compacted and welded within the thickness of a metal sheet, within a sheet-aperture of lesser diameter than a top of the nut, spaced-apart compacted edge portions of the nut's top having a larger diameter than the nut's top at other edge locations in the compacted state, and the sheet's malleable metal of bottom portions thereof adjacent the aperture being compacted against and welded to malleable metal of a circumscribing side wall of the nut.Type: GrantFiled: May 6, 1981Date of Patent: August 28, 1984Inventor: Guenther Krueger
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Patent number: 4429458Abstract: Immediately after a composite electric contact is made from wires by cold welding and in a manner as it has been cold welded, it is brought onto a supporting metal and subjected to pressure and resistance heat exerted by a pair of electrodes whereby the contact and the supporting metal are spot welded in situ without adversely affecting the supporting metal such as warping thereof and whereby cold welded abutting ends of the contact are released from stress which is produced by cold welding and the contact is annealed in whole.Type: GrantFiled: December 18, 1980Date of Patent: February 7, 1984Assignee: Chugai Denki, Kogyo K.K.Inventor: Akira Shibata
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Patent number: 4414742Abstract: Two or more pieces of wire of precious and non-precious metals are cold welded at their free ends, for producing a composite electrical contact or contact material, contact surface of which is made of said precious metal or alloys thereof. One of, a plurality of, or all of said free ends are provided with one or more projections of a diameter less than that of the wires which are expanded and flow under welding pressure over the abutting surfaces of the free ends to form bonded surfaces of wires without undesired or unexpected expansion of the wire pieces in their diameters.Type: GrantFiled: November 21, 1980Date of Patent: November 15, 1983Assignee: Chugai Denki Kogyo K.K.Inventor: Akira Shibata
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Patent number: 4319708Abstract: An electrically conductive path through an insulating plate (10) is produced by forcing sheets of conductive material (13, 14) into contact through a hole (11) in the plate (10). The sheets (13, 14) are forced together with sufficient force to produce a cold weld junction, which is then plated with a conductive metal (102). Dies for producing the cold weld utilize metallic spheres (110), rods (188) or chemically etched projections (228). Shaped dies (268, 272) form a crimped joint without a cold weld, and offset dies (246, 250) produce a raised junction (252) for use as a mount for a planar component. In manufacturing a printed circuit board (160) the cold weld die (158) is produced with the same drill hole pattern as used to form the drill holes in the printed circuit board (160).Type: GrantFiled: November 15, 1978Date of Patent: March 16, 1982Inventor: Robert B. Lomerson
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Patent number: 4281786Abstract: A pressing machine has opposingly spaced-apart compacting surfaces movable toward each other to weld malleable metal of a metal sheet having a nut-receiving circular aperture therethrough, into a welded state with a malleable metal of circumscribing side-walls of a cylindrically-shaped undercut nut mounted in the aperture. The nut's top has a greater diameter than the aperture. A bottom one of the compacting press surfaces has a raised rim or ridge, and an upper one of the compacting press surfaces has a plurality of raised portions, arranged in a circular array to overlap edge portions of the sheet at its aperture. With the plurality of raised portions pressing downwardly, and the ridge in a circular shape around an annulus hole of the bottom press surface, the compacting surfaces in a single compacting movement in compacting the sheet carrying the inserted nut having overlapping top edges, results in an article in which the metal sheet has become welded to the nut.Type: GrantFiled: August 25, 1980Date of Patent: August 4, 1981Inventor: Guenther Krueger
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Patent number: 4232812Abstract: A tri-metallic electrical contact consisting of a head wire piece and a base wire piece which abut to an intermediate piece at its opposite ends, is produced by cold press operations performed by first and second die and punch sets. The first die and punch set causes plastic deformation of approximately only a half part of the aligned wire pieces, while keeping another half part of these pieces not deformed. The second die and punch set imparts, subsequent to, and independently from, the cold press operation performed by the first die and punch set, plastic deformation to the other half part of the pieces, whereby the abutting surfaces of the three wires are prevented from sliding movements laterally relative to each other during the cold press operations, and whereby irregular or insufficient deformation of the wires due to the differences of yield points of the wires is prevented.Type: GrantFiled: July 24, 1978Date of Patent: November 11, 1980Assignee: Chugai Denki Kogyo Kabushiki-KaishaInventor: Akira Shibata
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Patent number: 4196837Abstract: A method of indirectly connecting two parts, such as an acousto-optical building component composed of lead glass and a piezo electric transducer composed of lead-zirconium titanate, whereby at least one mono-molecular layer (having a maximum thickness of 100 nm) composed of a lead-free glass is directly applied under vacuum onto the surfaces of the parts to be joined and metal layers are then applied under vacuuum onto such glass layer and/or the surfaces to be joined so that when the free surfaces of such free metal layers are brought into contact with one another under vacuum, a bond forms therebetween and such bonds indirectly connect the parts with one another. The glass layer prevents diffusion of atoms or ions from the materials (such as lead) on either side of such layer so that the parts so-joined and/or the bonds so-formed are not impaired in any way.Type: GrantFiled: July 27, 1978Date of Patent: April 8, 1980Assignee: Siemens AktiengesellschaftInventors: Klaus Burkart, Manfred Wintzer
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Patent number: 4073425Abstract: A double-contact rivet is formed from wire portions cut from wire supplies. The wire portions are aligned so that outer portions of electric contact material are located on either side of a central portion of support material, and the two outer portions are cold-welded to the central portion. One end of the body so formed is punched to provide a contact head while the bead formed by the cold-welding at the other end is pressed to a substantially flat ring form and hardened by rapid cooling. The hardened ring bead is cleanly cut from the remainder of the rivet.Type: GrantFiled: December 2, 1976Date of Patent: February 14, 1978Assignee: Eugen Durrwachter DoducoInventor: Erwin Bollian
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Patent number: 4066200Abstract: A mechanism having first means for moving a tool or the like in an up and down direction and second means for moving such device in a fore and aft direction. The mechanism is suitable for a number of different uses and is especially adapted for die bonding operations wherein a die is picked up at one location and transferred to a second location. The mechanism also has means for imparting reciprocatory motion to the device so that, if the device is a die placement tool, the tool can be utilized to provide a scrubbing action for the die on a substrate therebelow.Type: GrantFiled: March 22, 1976Date of Patent: January 3, 1978Inventor: John C. Diepeveen
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Patent number: 4029252Abstract: An apparatus for making a copper-aluminum transition joint characterized by utilizing a combination die and metal shears mounted between a pair of abrading brushes and wire feeding devices that are operable, respectively, to feed a copper wire and an aluminum wire into overlapping relationship between relatively movable die surfaces, after the wires have been abraded to remove oxidized portions thereof and to remove contaminants from the wires. The respective wire feeding devices cooperate with limit stops formed in the relatively movable dies to assure rapid, accurate positioning of the two wires over a punch in a double-action die that operates to form a cold welded transition joint between the wires when the dies are closed. The wire feed devices also selectively retract the sheared ends of the wires from the transition joint to facilitate rapid ejection of the joint from the die.Type: GrantFiled: May 17, 1976Date of Patent: June 14, 1977Assignee: General Electric CompanyInventor: Kenneth G. Hawkins
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Patent number: 4019668Abstract: A tool for transfering a semiconductor die from one location to the other is mounted in a holder comprised of a shaft which is normally horizontally disposed and extends forwardly from a plate which moves up and down so that the tool can be raised and lowered. The shaft also moves longitudinally through the plate so that the tool can be moved fore and aft. A first lever driven by a cam rotated by a first motor causes the plate to move downwardly and first bias means urges the plate in an upward direction. A second lever is pivoted in a vertical plane and is coupled to a rotatable member driven by a second motor. The lever shifts the shaft fore and aft, and second bias means urges the shaft toward the lever. In a second embodiment, the first lever is omitted and a handle and linkage is substituted therefor for manual up and down control of the shaft.Type: GrantFiled: December 30, 1974Date of Patent: April 26, 1977Inventor: John C. Diepeveen
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Patent number: 4014494Abstract: Machine for cold butt welding of metal blanks, wherein one of the blank clamping devices mounts on its housing a carriage with blades for cutting off the ends of the blanks, adapted for possible displacement in the direction of the force upsetting the blanks to position these blades at such distances from the device housings that assure the upsetting of an amount of metal as needed for the welding. The machine is provided with guide members carrying blank clamping devices, single-endedly fixed, that is in a cantilever fashion, in a power drive housing installed on a bed of the machine and adapted for set turning in at least one vertical plane in relation of the upsetting force. The blanks may be in different relationships in space. The invention can be successfully employed in welding aluminum and copper blanks of any cross-sectional shapes: circular, square, rectangular, rhombic, etc.Type: GrantFiled: July 5, 1974Date of Patent: March 29, 1977Inventors: Nikolai Alexeevich Glagolev, Gennady Alexeevich Klimenko, Anatoly Ivanovich Chvertko, Boris Ivanovich Kononets, Pavel Ivanovich Gursky, Vladimir Alexandrovich Nosachev, Leonid Grigorievich Kravchenko, Valentin Georgievich Basov, Larisa Evgenievna Bogomolova, Viktor Andreevich Ivanov, Konstantin Konstantinovich Khrenov
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Patent number: 3946928Abstract: An adjustable die set for a coldwelding machine that is adjustable to facilitate its use with workpieces of varying dimensions. Specifically the die set includes pairs of dies having a screw threaded adjustable stop interconnecting them for adjusting the spacing between the dies.Type: GrantFiled: January 2, 1973Date of Patent: March 30, 1976Assignee: Kelsey-Hayes CompanyInventor: Leonard Di Grasso
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Patent number: RE29012Abstract: A tool for cold pressure welding workpieces such as coaxial cables together. The tool has a compact arrangement so that it may be hand held and operated. A hydraulic pump and motor are incorporated for providing a force amplification which lends to the compactness and light weight of the assembly. The hydraulic motor operates pairs of dies which dies first grip the ends of the workpieces to be welded and then force these ends into engagement to achieve a cold pressure weld. A pressure relief valve is interposed in the hydraulic circuit for limiting the force applied to the dies. The dies are held in pivotally supported parts of the tool so that the tool may be conveniently opened for inspection, replacement or cleaning of the dies.Type: GrantFiled: January 20, 1975Date of Patent: October 26, 1976Assignee: Kelsey-Hayes CompanyInventors: William E. Good, Arthur S. Davies