Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L15/00—Screw-threaded joints; Forms of screw-threads for such joints
  • F16L15/006—Screw-threaded joints; Forms of screw-threads for such joints with straight threads
  • F16L15/009—Screw-threaded joints; Forms of screw-threads for such joints with straight threads with axial sealings having at least one plastically deformable sealing surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
  • B23P19/00—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes
  • B23P19/04—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes for assembling or disassembling parts
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49826—Assembling or joining
  • Y10T29/49908—Joining by deforming

Definitions

• the subject of the present patent is a novel method or technique for leak tight junctions (or YTTJ - Vacuum Tight Threaded Junctions), for making heterogeneous or homogeneous junctions between weldable or non- weldable materials, compatible with high vacuum conditions.
• the new technique has been developed in the framework of research on controlled thermo-nuclear fusion, with the goal of obtaining reliable vacuum tight junctions between copper and steel for components subjected to a high heat flux.
• the new technique is also usable in several other industrial applications to make junctions with materials that can even be different from steel and copper, can require or not require vacuum tightness and on components that can be subjected or not subjected to high heat fluxes.
• junctions can be of heterogeneous or homogeneous type.
• welding between metallic materials designates a process by means of which the two materials to be welded are joined through the formation of atomic and/or molecular links, due to the action of heat and/or pressure.
• Gas welding which uses a combustible gas combined with a comburent, i.e. oxygen, to produce flame that is the heat source necessary to melt the joining material.
• a combustible gas combined with a comburent, i.e. oxygen, to produce flame that is the heat source necessary to melt the joining material.
• Arc welding is also known, which uses the heat generated by an electric arc between an electrode and the piece to be welded to obtain melting. This technique is however usable only with some types of materials.
• Resistance welding is also known, which uses the electrical resistance of the components to be welded to obtain the necessary heat, and wherein the junction is obtained by applying also a suitable pressure.
• Friction welding is known, ' where the heat is generated through friction, obtained by mechanical rubbing between the surfaces of the components to be welded, for example deriving from the relative rotation of the components.
• the parts to be welded are the joined by applying a sufficient pressure to generate the link.
• This technique is however usable only with some types of materials, and depends on the metallurgical state of the materials to be welded.
• Ultrasonic welding where the surfaces to be welded are subjected to a normal static force and a tangential force oscillating with a given frequency.
• Electron beam welding is known, which is a melting process to be carried out under vacuum conditions, generating a local melting of the materials by means of a beam of electrons that create a common lattice by transforming the kinetic energy of the electrons into thermal energy when they impact the materials.
• This technique is very expensive, requires large equipment that cannot be transported and specialized personnel.
• Brazing or weld brazing techniques are also .known, which do not require melting of the base material, in these processes, a metal having a melting temperature lower than that of the materials to be joined is melt and forced to flow so as to fill the capillaries of the surfaces to be joined.
• a metal having a melting temperature lower than that of the materials to be joined is melt and forced to flow so as to fill the capillaries of the surfaces to be joined.
• the junctions obtained in this way have limited mechanical strength and pose other drawbacks.
• Patent US 3 388 931 relates to a welding between a holed plate and a tube including the use of two members suited to be interposed between the holed plate and the tube, and in particular a heat-shrinking plastic insert suited to be inserted in the hole, and a cylindrical ferrule, made of plastic or metal, suited to be inserted between the tube and the insert, and wherein the application of heat causes the insert to shrink and thus the tube to be engaged into the hole of the plate.
• Patent US 2 658 706 relates to a metliod for constraining a pipe projecting from a floor or a wall wherein a cylindrical sleeve is used to loosely surround the pipe and a pair of clamping members surround the pipe and are tapered so that their smaller ends are inserted in said sleeve, and pressing said clamping members towards said sleeve makes them clamp the pipe and complete the fixing operation.
• VTTJ technique is suitable for making a wide range of heterogeneous and homogeneous junctions between weidable or non- weldable materials.
• VTTJ technique could be used to make junctions on heat exchangers, hydraulic plants, boilers, heating systems, etc. in the manufacturing, chemical, food, pharmaceutical, oil industries, etc, and in power plants.
• the invention concerns a method or technique for making heterogeneous or homogeneous junctions between weldable or non-weldable materials.
• the junction is obtained between a first body comprising at least a tubular portion or tube and made of a first material, and a second body made of a second material and featuring a hole for the insertion of said tube of the first body.
• Said first material, of which said first body is made, and said second material, of which said second body is made, can be the same or different materials, suited to be welded to each other or not.
• the new technique includes the following phases:
• said conical or cylindrical ring and said cylindrical or conical recess have such a shape and size that, when said tube of the first body is at least partially inserted into said hole in the second body, and said tube is screwed in said second body, said conical or cylindrical ring is forced in said cylindrical or conical recess, causing the plastic deformation of said ring and/or of said recess.
• Figure 1 shows a sectional view of the first body (A), in the shape of a tubular element or tube (Al).
• Figure 2 shows a sectional view of the second body (B), in the shape of a plate with a hole ( ⁇ ) defining a duct for the insertion of part (A2) of said tube (Ai).
• Figure 3 shows a sectional view of the first body (A) joined to the second body (B).
• Figure 4 shows a detailed sectional view of the junction area between said first body (A) and said second body (B) obtained through mechanical interference.
• Figure 5 shows a sectional view, according to a first embodiment, of the first body (A) joined to the second body (B) through electrode-position (D).
• Figure 6 shows a sectional view, according to a second embodiment, of the first body (A) joined to the second body (B) through electrode-position (D).
• Figure 7 shows a sectional view of the first body (A) joined to the second body (B), wherein said first body (A) and said second body (B) are made according to an alternative solution, with a raised edge or rib (A5, B4) for the successive welding, illustrated in detail in Figure 8.
• Figure 9 shows a schematic view 1 of a section of the first body (A) with a portion (A8) with non-circular cross section suited to allow gripping by- means of a screwing tool.
• the new joining technique includes the steps described here below, for example to make a junction between a body (A), for example a tubular element or tube (Al) made of a first material, for example steel, and a body (B) made of a second material, for example copper in the shape of a. plate.
• a body for example a tubular element or tube (Al) made of a first material, for example steel
• a body (B) made of a second material for example copper in the shape of a. plate.
• At least one hole (Bl) is made in said copper plate (B), for example by milling, said hole being cylindrical or in any case defining a duct for the insertion of part of said tube (Al). in particular for the insertion of at least the end (A2) of said tube (Al).
• the steel tube (Al) to be fixed to said copper plate or body (B) is at least partially threaded (A3) on its external surface (A4). for example in proximity to said end (A2) to be inserted in said hole (Bl) of the plate or body (B).
• the inside of said hole (Bl) is preferably at least partially threaded (B3) at the level of said thread (A3) of said tube (Al).
• Said conical ring (A5) and said cylindrical recess (B2) have such a shape and size that, once the tube (Al) has been screwed into the hole (B l) of the plate (B), said conical ring (A5) is forced in the cylindrical recess (B2), causing the plastic deformation of the plate (B) and/or of the tube (A), depending on the material of which they are made.
• the diameter (A5a) of the lower end of said conical ring (A5) is smaller than the diameter (B2d) of the cylindrical recess (B2), so as to allow for insertion, while the diameter (A5b) of the upper end is larger than the diameter (B2d) of the cylindrical recess ( B2). so as to obtain the interference (A6).
• said maximum diameter (A5b) of the conical ring ⁇ AS) is about 0.1-0.2 mm larger than the diameter (B2d) of the cylindrical recess (B2).
• the dimensions ca however vary as a function of the geometry of the junction and of the materials used.
• the steel tube (Al ) is screwed in the corresponding hole (B l) of the copper plate (B).
• the plastic deformation of the cylindrical recess (B2) in the hole (B l ) of the copper plate (B) takes place, and a seal is consequently obtained.
• the material of the first body (A) is softer than that of the second body (B), there will be a plastic deformation of the conical ring (AS), owing to which a seal will equally be obtained. If the materials of the First body (A) and of the second body (B) feature a similar degree of hardness or if said first body (A) and said second body (B) are made of the same material, the plastic deformation will take place both in said cylindrical recess (B2) and in said conical ring (AS) and, analogously to the previous cases, a seal will be obtained through plastic deformation.
• Vacuum leak tests with a leak finder were carried out on several prototypes using helium as a sample gas. These tests showed that the junction made with the VTTJ technique have no leaks. Analogous tests were successively performed after cyclic loading with an internal pressure of 30 bars repeated 10 times, showing again total absence of leaks. Finally, analogous tests were performed after a heat treatment lasting one hour at 200°C, showing also in this case total absence of leaks.
• the present technique can include further operations of electrodeposition, electron beam welding or brazing, to be executed after screwing the steel tube (Al) into the copper body (B), in order to make the junction compatible with use in particularly severe conditions, for example with high thermal and/or mechanical-structural loads.
• a strip (D) of a suitable material for example a copper layer, can be electrodeposited along the junction edge (C) and on the surrounding area.
• This further copper layer (D) that has been deposited has the main function to guarantee a vacuum tight seal also in the presence of particularly severe operating conditions, for example with high mechanical and/or thermal loads.
• a thin layer of copper can be electrodeposited on the steel tube, at the level of said conical ring ( A5) and in proximity to its .non-threaded portion, to improve adhesion for the following electrodeposition.
• the portion of the tube immediately above the conical ring can be connected to the ring itself with a fitting (A7) featuring a suitable radius.
• each one of the joined edges of said tube (Al) and said copper body (B), i.e, said conical ring (A5) and said cylindrical recess (B2) are positioned on a raised edge or rib (A5, B4) to allow for the following electron beam welding.
• said tube (Al) can at least partly (A8) feature a non-circular cross section, in such a way as to allow said tube (Al) to be gripped with suitable tools and screwed into said second body (B), wherein said portion (A8) with non-circular section is located at a certain distance from said conical ring ( A 5).
• FIGS 10 and 1 1 show two possible variant embodiments of the same innovative concepts.
• a conical recess diverging towards the inlet of the hole (Bl) is created in said hole (Bl) in the second body (B), in addition to a cylindrical ring that is provided on said tube (Al) of the first body (A), so that, once said tube (Al ) of the first body (A) has been at least partially inserted in said hole (Bl) in the second body (B) and said tube (Al) has been screwed in said second body (B), said cylindrical ring is forced in said conical recess, thus producing the plastic deformation and consequently obtaining a seal through interference between said first body and said second body.
• the diameter (B2b) of the inlet opening of said conical recess (B2) is larger than the diameter (A5d) of the cylindrical ring (A5), so as to allow for insertion, while the diameter (B2a) of the opposite end is smaller than the diameter (A5d) of the cylindrical ring (A5) so as to obtain the interference (A6).
• a conical recess diverging towards the inlet of the hole (Bl) is created in said hole (Bl) in the second body (B),
• a conical ring that is provided on said tube (Al) of the first body (A)
• the taper of said conical ring of the first body (A) is different from the taper of the conical recess of the second body (B)
• the diameter (A5a) of the lower end of said conical ring (A5) is smaller than the inlet diameter (B2b) of the conical recess, so as to allow for insertion, while the diameter (A5b) of the upper end is at least larger than said inlet diameter (B2d) of the conical recess (B2) so as to obtain the interference (A6).

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Welding Or Cutting Using Electron Beams (AREA)
• Non-Disconnectible Joints And Screw-Threaded Joints (AREA)
• Gasket Seals (AREA)
• Pressure Vessels And Lids Thereof (AREA)
• Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (8)

Cited By (1)

Families Citing this family (1)

Citations (4)

Family Cites Families (19)

• 2012
  • 2012-06-07 IT IT000186A patent/ITPD20120186A1/it unknown
• 2013
  • 2013-05-31 EP EP13739787.3A patent/EP2859262A1/en not_active Withdrawn
  • 2013-05-31 WO PCT/IB2013/054504 patent/WO2013182962A1/en not_active Ceased
  • 2013-05-31 CN CN201380027613.8A patent/CN104350319A/zh active Pending
  • 2013-05-31 IN IN2362MUN2014 patent/IN2014MN02362A/en unknown
  • 2013-05-31 JP JP2015515617A patent/JP5958651B2/ja not_active Expired - Fee Related
  • 2013-05-31 US US14/405,138 patent/US20150113788A1/en not_active Abandoned
  • 2013-05-31 KR KR20147033191A patent/KR20150011820A/ko not_active Ceased

Patent Citations (4)

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