MXPA98004990A - Union or electromagnetic welding of metali objects - Google Patents

Abstract

Two pieces of work are joined or welded together to induce movement in the first of the two pieces of work or a portion thereof by means of a magnetic force with pulsation, so that the first workpiece or first portion is impacted in the second of the pieces of work and later the two become or join or weld between

Description

UNION OR WELDING EI-EC TRAOMAGMETICA METAL OBJECTS FIELD OF THE. INVENTION The present invention relates generally to the field of metal works and relates to a method and apparatus for working metal workpieces. The present invention relates particularly to such a method and apparatus for working metallic workpieces by magnetic pulse energy.

BACKGROUND OF THE INVENTION AND PREVIOUS TECHNIQUE Magnetic pulse formation (PMF) is a process in which a metal work piece or a portion of it is put into rapid motion by a pulsed magnetic field which causes the workpiece to deform. An advantage of the PMF process is that the energy loss in this process is minimal as a result there is no or very little heating of the work piece. In addition, this process does not have the disadvantage of leaving tool marks, as in the case of several different techniques (see M. Cenanovic, Magnetic Metal Forming by Reverse Electromagnetic Forces, In Proceedings of the Fourth REF: 27757 - - 2 - IEEE Pulse Power Conference, Institute of Electrical and Electronic Engineering, 1983). The PMF process uses a discharge capacitor or a capacitor bank, a forming coil and often a field shaper to generate an intense magnetic field. The very strong magnetic field required for the PMF process is the result of a very rapid discharge of electrical energy, stored in the capacitor, in the formation coil. The parasitic currents resulting inducements in the workpiece generate magnetic repulsion between the work piece and the forming coil, and this causes the workpiece to deform. As the surface of the work piece is moves under the influence of repulsive force, absorbs energy from the magnetic field. In order to apply most of the energy available for training and reduce energy losses due to energy permeation in the workpiece material (which causes waste of energy by resistance heating), the magnetic pulse of formation is produced to be very short. In most PMF applications, the pulses have a duration between about 10 and about 250 μsec (duration of the first wave of the discharge current). • * - 3 - Background with respect to prior art apparatus and methods for working metal workpieces by the PMF process can be found in the following North American patents: 3,654,787 (Brower), 3,961,739 (Leftheris), 4,170,887 (Baranov), 4,531,393 (Weir), 4,807,351 (Berg et al.), 5,353,617 (Cherian et al.) And 5,442,846 (Snaper).

GENERAL DESCRIPTION OF THE INVENTION 10 In the following text, in order to simplify the description and facilitate a better understanding of the invention, sometimes the use of the following terms will be made: 15 Work piece: A metallic object which is deformed , according to the invention, by applied work on surfaces thereof.

Moving surface: A surface of a workpiece which is abruptly and rapidly moved by a magnetic force by pulses. According to the invention, the moving surface is a solid made to impinge on another surface (which can be to be stationary, or which may be a moving surface in an opposite direction) with a kinetic energy which causes the two surfaces to join or weld (with respect to "joint" and "welding" - see below).

Work: A process which is a result of the work applied to a work piece or to a portion thereof which causes the work piece or portion to deform. The work according to the invention is by means of PMF and must also lead to a change in the shape of the work piece, which leads to the joining of a surface of a work piece or portion thereof worked, to another surface.

Union: The work of an object or portion thereof in such a way as to cause a surface thereof to come into very close contact with another surface. The joint, for example, may be the act of tightening an essentially tubular workpiece against another cylindrical object within the interior of the workpiece so as to force the opposing surfaces to be joined very strongly and essentially permanently of the two objects between them. The purpose of the connection can be, for example, to ensure an airtight electrical contact, that is, with minimum electrical resistance between the two objects.

Welding: Formation of a first piece of work in such a way that the two opposite surfaces, initially separated, are integrated with each other. In welding such two surfaces in fact melt and then solidify together to become integral.

Worked in portion: Part or portion of a piece of work which is worked, that is, put in rapid motion by a force PMF, to join or weld the other portion of a piece of work. For example, in the case of a cable projection or connection, the portion that is worked on will consist of the portion which comprises a hollow receptacle which receives the cable and which is then tightened by means of the force PMF to join or solder with the cable contained in it. The portion on which one works is made of an electrically conductive material or has at least one surface coated by an electrically conductive material. The electrically conductive material may be constituted, for example, of metal or an electrically conductive polymer.

Opposite portion: A portion of a work piece which is to be joined or welded to the portion on which it is worked. The opposite portion may be included in a different work piece so that it comprises the portion on which it is worked (for example, in the case of joining, of cable in a cable projection, the portion on which it is worked will be the portion comprising the cable projection receptacle, as indicated above, and the opposite portion will be the portion of the cable containing the receptacle which is joined or welded to the portion being worked), although sometimes the opposite portion It can be included in the same work piece as the portion on which it is worked (for example, the welding of two flanges of a work piece to each other, when tightening a tube for joining or welding their walls together so that seal the end of a tube, etc). Sometimes, the opposite portion may also be the portion that is being worked on, this is the case, for example, when two portions are placed in rapid motion against each other to join or weld together (for example, this is the case in which the retaining walls of a tube to seal a tube end).

First piece of work: A piece of work which constitutes the portion on which one works which is going to be joined or welded to an opposite portion, in another, second piece of work (see below).

Second piece of work: A piece of work that includes the opposite portion in the case in which the metal portion on which one works is another piece of work. The present invention relates to the use of the PMF process to join or weld workpiece surfaces or workpiece portions together. According to the present invention, it is obtained by causing at least one workpiece or a portion of a workpiece comprising one of the surfaces to be joined or welded (the portion on which it is worked) to move quickly towards the other workpiece or a portion of a workpiece comprising the other surface to be joined or welded (the opposite portion). Rapid movement results from a PMF force applied to the portion to be worked, which is made of an electrically conductive material or has at least one surface which is coated by an electrically conductive material. The conditions of the PMF force are controlled so that, after two surfaces impinge against each other, they are joined or welded together. The control of the PMF force is typically such that the velocity of the moving surface will impart kinetic energy to the portion on which it is worked, before the impact, which is greater than the sum of the plastic deformation of the portion on which it works and of the elastic deformation of the opposite portion. The invention provides a novel process for joining or welding objects together, as well as structures obtained by such joining or welding. The process of the invention allows the manufacture of some objects or structures which are novel per se, for example a joint between a cable and a connector such as a cable projection in which the filaments or wires are compacted almost to the maximum with very little empty space (that approaches zero), that is to say, the filaments of wires fill essentially the totality of the lumen in which they are contained; or a superconducting cable having a filament embedded in a cable sheath or matrix with very little empty space; joints between two superconducting cables; a new cable or ground pole, - etc. Such novel objects or structures, regardless of the manner in which they are produced, also form an aspect of the invention. The invention provides a method for joining or welding at least two solid portions together, comprising inducing movement in at least one of the solid portions, which is made of an electrical material or has at least one surface coated by an electrically conductive material, by means of pulsing magnetic force so as to strike at least one other solid portion. The movement imparts a kinetic energy on at least one solid portion to cause at least two solid portions to join or weld together. The two solid portions that are to be joined or welded and are made of the same material or can be made of a different material. For example, both can be made of steel, stainless steel or bronze, copper, etc. Alternatively, one may be manufactured from such exemplary alloys or from an electrically conductive polymer, and the other may be made from another material such as metal, or an electrically non-conductive material, etc. According to a preferred embodiment, the invention provides a method for joining or welding at least two solid portions comprising forcing the solid portions against each other by inducing rapid movement in at least one of the solid portions so as to cause that at least one surface thereof impacts on the other solid portions, at least one of the solid portions is made of or consists of at least one surface made of an electrically conductive material and the movement is induced by a forming force pulsed magnetic which is at such a magnitude that the initial kinetic energy of at least one of the solid portions before impact is equal to or greater than the combined plastic deformation energy of at least one of the solid portions and the energy of elastic deformation of at least two solid portions after impact, so at least the two portions solid ones are joined or welded together. The two solid portions which are to be joined or welded together, are faced a priori with each other or are placed so that the opposite surfaces touch or are close to each other. The force PMF is then applied from a forming coil located close to a surface of the portion on which it is going to work different from that which is opposite a corresponding surface in the opposite portion, and in this way induces movement on the portion that is going to work (it should be noted that even when the two portions touch each other, there is sufficient separation between the two surfaces at the microscopic level to allow the acceleration and accumulation of kinetic energy in the portion on which it worked). As already indicated in the above, the portion on which one works and the opposite portion can both be in the same work piece. This may be the case, for example, of tightening a end of a tube, for example a metal tube, to join or weld internal walls together so as to seal the tube.

Alternatively, as also emphasized in the above, the portion on which one works can be an object and the opposite portion can be another object: for example, as in the case of the connection of a connector to an electric cable. In most cases, one of the solid portions to be joined or welded will be stationary and the other will be a portion that is being worked on which is placed in rapid motion by means of a PMF force. However, in some cases, both solid portions may be moved against each other, this is the case, for example, in the sealing of one end of a metal tube, as already indicated above. In this last case, where all the solid portions to be joined or welded are forced to move quickly, this will work both in the portions on which one works as well as in the opposite portions. According to one embodiment of the invention, the two portions to be joined or welded, each in a separate object (a first and a second workpiece) both are independently an elongated portion. According to this embodiment, at least the solid portion on which one works is a hollow elongated member, and the dimensions of the two portions initially are such that they can be placed one on top of the other. The method according to this embodiment comprises: (a) inserting one of the two portions in a hollow interior of the other; (b) causing the surfaces of a first elongated portion on which to work of the first workpiece to move towards opposite surfaces of the other elongated counterpart of a second workpiece by means of a magnetic force by pulses , so that the surfaces of the portion on which it is going to work are caused to impinge on the opposite surfaces of the opposite portion at a speed such that the kinetic energy of the portion on which it is going to work, which moves of the first work piece before the impact is greater than a combination of the plastic deformation energy of the portion moving in the plastic deformation energy of the opposite portion after impact; so the two portions are joined or welded together. Examples of the embodiment of this connection of an electric cable with a cylindrical workpiece or a portion of the workpiece, for example the connection of a cable with a cable projection or with another type of connection device; the joining or welding of two elongated objects, for example, two electric cables or two rods, by means of a tubular joining member; welding two tubes together; etc. According to another embodiment of the invention, the two portions to be joined or welded are essentially flat. Examples of this embodiment are the joining or welding of a metal board, panel or sheet to each other, welding one end of a metal band or sheet to the end of another metal band or sheet, etc. A further embodiment of the invention relates to the production of superconducting wires or cables. Such cables have a matrix, jacket or jacket made of an alloy, for example aluminum or copper, and have filaments, which are contained within the lumens or longitudinal perforations in the cable and which are made of another alloy, for example alloys of niobium or titanium - niobium. According to the invention, such composite wire or cable is prepared by inserting filaments into longitudinal perforations or the hollow lumen of a cable or wire which is then constricted by means of a PMF process. As a result, you get a very tight composite cable or fiber with very little, almost no empty space. Sometimes, the filaments themselves are a composite structure, and can also be prepared by a PMF process, according to the invention. A further embodiment of the invention relates to the production of an electrode or ground wire, particularly one that has an inner metal core coated with an insulating material, sometimes enclosed within another metal liner. An additional modality relates to the clamping and welding of walls of a metal tube so that they form a gas tight seal. A further embodiment relates to the tightening of a tube made of metal or of an electrically conductive polymer on an object made of an electrically non-conductive material so that the connection of the tube with the object occurs. According to other embodiments, the PMF process of the invention can also be used for joining or welding a first flat workpiece to a second spherical workpiece. As will be appreciated, the above embodiments are only examples of a myriad of modes, all of which are within the scope of the invention as defined herein.

The invention also provides a useful device in the above method. The device of the invention comprises a power source, one or more capacitors (which can store a large amount of electrical energy), current control circuits and a forming coil. The total shape and dimensions of the forming coil in the devices of the invention will determine the portion of metal on which it works which is joined or welded to the opposite metal portion as well as, sometimes, the final shape of the portion on the one that is worked For example, in the case of joining or welding two flat work pieces, the size and shape of the flat forming coil will determine the size and shape of the portion of the first work piece which is to work and which is then welded to the opposite portion in the second work piece. In the case of joining or welding of two elongated pieces, the length of the coil will determine the length of the portion on which it is worked which is welded or joined to the opposite portion. In addition, the shape of the forming coil, that is, the shape of the path traced by the coil, will be a factor that alters the shape of the final cross section of the portion on which one works after working on it. For example, when joining two tubular objects, a forming coil having a hexagonal shape can produce a final hexagonal shape of the portion on which it is worked. Generally, by using the available knowledge and the additional knowledge obtained in accordance with the invention, a person familiar with the art will have no difficulty in designing a training coil to meet the desired specifications. The manner of operation of the invention will now be illustrated with reference to a specific embodiment of the invention related to the joining or welding of two essentially cylindrical objects. The (first) portion on which one works in accordance with the above specific embodiment is preferably cylindrical, although it may also be in the form of a prism may have an elliptical or oval cross-sectional shape, etc. The (second) counter portion is also preferably cylindrical, but similarly of the first portion, it may also have a variety of cross-sectional shapes other than the circular. The second portion may have a cross-sectional shape similar to the first workpiece, ie, both will have a circular cross-sectional shape, both will have a hexagonal cross-sectional shape, etc. However, the first and second portions may also have different cross-sectional shapes, for example, the first portion will be cylindrical and the second portion will be prismatic, etc. In each case, the respective dimensions of the two portions must be such that insertion of the second portion into the lumen of the first portion or insertion of the first portion into the lumen of the second portion is permitted. The first portion is induced to rapid movement by magnetic force by pulses generated by a coil near one of its surfaces different from the surface which is welded or joined to the opposite surface in the second portion. In one embodiment of the invention, the second portion is inserted into the first portion and the first portion is then pressed onto the second portion, by means of a magnetic forming coil surrounding its outer surface. According to another embodiment, the first portion is inserted into the lumen of the second portion and then expanded by a magnetic force from an adjacent coil on its inner surface so as to cause it to strike in and then join with the walls of the second surrounding portion. The edges of a prismatic hollow object are sometimes more resistant to tightening than other parts of the walls of the prismatic object. Thus, in the case of a prismatic object, the PMF force must be adjusted in some way to consider this additional resistance. The resistance to the edges of the object decreases with an increase in the associated angle, which correlates with the increase in the number of sides of the prismatic object. Consequently, the edges of octagonal objects are less resistant to the forces of tightening than the edges of a hexagonal object (assuming the same wall thickness and the same metal alloy in both cases) and the edges of the hexagonal objects in turn are less resistant to tightening than those of a pentagonal or rectangular object. It is clear that when the number of sides of the prismatic hollow object increases, the force required for tightening approaches that of the cylindrical object. The additional force required in the case of a prismatic hollow object (as opposed to a hollow cylindrical object) can also be reduced by rounding the edges. A person skilled in the art will be able, without undue difficulties, to design a PMF device with a forming coil to satisfy a certain desired specification. In the following, the invention will be described with reference to a preferred embodiment in which both the first and second portions are cylindrical. At the moment of impact of the first portion that moves rapidly with the second portion, the kinetic energy of the first portion is at least equal to the sum of the plastic deformation energy of the first portion in motion after the impact and the elastic deformation energy of the second portion at rest. This can be represented by the following approximate equation (1): U = ^. { A + A2) / 1: D where U is the velocity of the moving surface of the first portion, before the impact, is the mass of the first portion, and Ai Y A-2 are I plastic deformation energy of the first portion, and the deformation energy elastic of the second portion, respectively, which can be calculated according to the following approximate equations (2) and (3): Aí = o1V1e1 ^. { 1 ^) / (r01 / r1-l) (2) lim-l / U + d, 2) j) i (3) s1 r1e J? IJ./ + o / (rQ2 / r2-l) 01 and r02, are, respectively, the radii of the first and second portions before the deformation, r? And r2 are, respectively, m the radii of the first and second portions after the deformation, ax and s2 are the tenacity of the alloys of which the first and second portions are manufactured, VJL and V2 are, respectively, the included volumes within the first and within the second portions after the deformation, d and d2 are the relative extent of the first and second portions, respectively, calculated according to the following equations (4) and (5): (4) - ^ oi r? - ^ 01 -r02 2 -02 (5) Based on previous energy requirements (A ± and A2) the working voltage (V) can be calculated by the following equations (6) and (7): km1U2Ll1 W 4p μ0r01h (6) where W is the energy stored in the capacitor's battery, V ~ 2W C is a coefficient which depends on the parameters of the PMF device (which includes the capacitance and the inductance itself) and the parameters of the work coil, is the total inductance of the electric discharge circuit (the coil, the pulse generator switch and the capacitor bank), 1 is the length of the work coil (and also the length of the deformation section of the work piece), μ0 is the magnetic permeation in vacuum, h is the thickness of the space between the coil of work and the work piece, U, my r01 are as defined in the above. When the object is different from a cylindrical object, sometimes it may be necessary to use the slightly altered parameters of the magnetic energy by pulses. For such objects it is necessary to define Ax and A2 and later the speed and voltage can be determined using equations (6) and (7). For example, when a prismatic hollow object is squeezed onto a cylindrical object therein, a slightly larger magnetic force will typically be required in view of the increased resistance of the edges to deformation. In addition, as will be appreciated, the above equations are applicable for a situation in which the length of the portion which deforms is greater than the diameter of the tube; where the potion is smaller than the diameter of the tube, some corrections must be taken into account in view of the resistance to deformations at one or both ends of the deformed portion. The kinetic energy which will be imparted in the first portion, will determine if the first and second pieces of work will be joined or welded together. Generally, the higher kinetic energy will result in a weld and the smaller the joint. Typically, when the speed of movement of the surfaces of the first workpiece is less than 300 meters / second, the first and second work pieces will be joined together. When the speed of movement of the surfaces of the first workpiece is greater than 300 meters / second, the surfaces of the first and second work pieces that are brought into contact are welded together. For welding, it is usually preferred to maintain a small gap between opposing surfaces of the first and second workpiece to allow the surface of the first workpiece to accelerate and reach the desired welding speed. For welding it is sometimes desired that the second workpiece, which does not move, be firmly immobilized so that it remains essentially motionless at the moment of the impact of the first workpiece thereon. Sometimes it may be desirable to induce movement of the portion on which one works by several magnetic pulses one after the other instead of a single magnetic pulse. This can be done, for example, in a device having a plurality of current discharge circuits, each of which is activated at different times. Such a device is novel and also forms part of an aspect of the invention. In the following, the invention will be exemplified by specific non-limiting embodiments, in which reference is made occasionally to the accompanying drawings. The exemplified modalities relate mainly to the work of metal work piece portions. However, it will be appreciated that the invention in general and in many of the embodiments described in particular is also applicable, mutatis mutandis, to working portions made of an electrically conductive material other than metal, for example, a conductive polymer. For example, a tube made of an electrically conductive polymer, in the manner illustrated in Figures 1-5 or 16, can be worked in a similar manner. In addition, instead of being completely composed of an electrically conductive material, the portion on the that one works from the exemplified embodiments may have one or more surfaces which are coated by a conductive material. A person familiar with the art, on the basis of the teachings of this invention, will have no difficulty in carrying out the invention with work portions made of electrically conductive material other than metal or consisting of only one or more surfaces made of electrically conductive material.

BRIEF DESCRIPTION OF THE DRAWINGS Figures 1 to 5 show a sequence of the joining of a multiple fiber cable and a cable projection; Figure 1 is a perspective view of an assembly consisting of a cable and a cable projection after the insertion of the end of the cable into the lumen of the projection of the cable; Figure 2 is a partially cross-sectional view, upper of the assembly of Figure 1; Figure 3 is a cross section through lines 3-3 in Figure 2; Figure 4 is a partially cross-sectional, top view of the assembly after the constriction of the cylindrical portion of the cable projection and the formation of a firm joint between the cable and the cable projection; Figure 5 is a cross-section through lines 5-5 in Figure 4; Figure 6A is an isometric view of a PMF device according to a useful embodiment of the invention, for example for the preparation of a joint between a cable and a cable projection, as shown in Figures 1 to 5; Figure 6B is a side view of a PMF coil according to another embodiment of the invention; Figure 7 shows a device according to another embodiment of the invention; Figure 8 shows a joint between a cylindrical object and a tube manufactured according to the invention using a device such as that shown in Figure 7; Figure 9 is a schematic representation of the manner of joining two poles, according to one embodiment of the invention; Figure 10 is a schematic representation of the manner of joining two superconducting cables together, according to one embodiment of the invention; Figure 11 is a schematic representation of another embodiment according to the invention for joining two superconducting cables; Figure 12 is a schematic, cross-sectional representation of the manner of production of a grounded cable, according to one embodiment of the invention; Figure 13 is a schematic cross-sectional representation of the manner of producing a superconducting cable according to the invention; Figure 14 shows a heating coil in which the coil and the electric pin are joined or welded together by means of a metallic sleeve constrained in the coil by a PMF process, according to the invention; Figure 14A is a side view of this device; Figure 14B shows a cross section through the lines 14a-14a in Figure 14a, - Figure 15 shows a device according to an embodiment of the invention; Figure 15A shows a way of using the device for joining or welding hollow cylindrical objects, using an insert or an appropriate setter of the two objects and supporting the walls; Figure 15B shows another way of using the device to join or weld two hollow cylindrical objects, if the use of such an insert; Figure 15C shows a longitudinal cross section through a joint between two tubes of different diameter, and welded together by the device of Figures 15A or 15B; Figure 16 shows the manner of tightening and welding to other walls of a metal tube to obtain an air tight seal, according to one embodiment of the invention; Figure 17 shows the adjustment for welding two flat metal objects; Figure 18 is a cross section through lines 18-18 in Figure 16; Figures 19 and 20 show two embodiments for welding metal workpieces initially flat to a spherical metal workpiece; Figure 21 is a schematic representation of the magnetic conductive circuit operating in a device according to an embodiment of the invention; and Figure 22 shows the magnetic conducting circuit in a device according to another embodiment of the invention.

DESCRIPTION OF SPECIFIC MODALITIES First reference is made to figures 1 to 5, which show the manner of joining a cable to a cable projection according to the invention. The cable projection 22 comprises a junction base 24 for attachment to another body, and an essentially tubular portion 25 with a lumen 26. The cable 28 comprises a plurality of conductive fibers 30, each having an essentially cylindrical cross-section. The cable 28 and the cable projection 22 are combined by inserting the end portion 32 of the cable into the lumen 26 of the cable projection, as can be seen in Figures 1 to 3. The cylindrical portion 24 has an original radius r01 and the cable has an original radius r02. In order to join the cable to the cable projection, pulsed magnetic force is applied to the cylindrical portion 24 and, consequently, the cylindrical portion 24 is tightened so that the inner faces thereof join with the portion 32 of end of the cable 28, as can be seen in Figure 4. As a result of this tightening, as shown in Figure 5, the fibers are compressed to be hexagonal. After tightening, the cylindrical portion 24 'has a radius rx and the cable has a radius r2. After tightening, there is some thickening of the walls of the tight tubular portion 24 '.

In a typical cable, the fibers fill up to approximately 65% of their internal space. After full compression, whereby the fibers become hexagonal, the fibers essentially fill 100% of the internal cable space. This means that the cable, after full compression, is tightened to approximately 80% of its original diameter. Consequently, when knowing r02, r2 can be calculated and it is considered to be equal to approximately 80% of r02. The term r2 is equal to the internal radius of the portion 25 after the constriction, and upon knowing the original thicknesses of the walls of the portion 25 the thickness can be calculated after the constriction and from this r1 can be derived (the radius of the cylindrical portion 25 (after the constriction) Then, using the equations 1-5 above, the magnetic parameters required for this process can be calculated.The connection of a cable with a cable projection is an example of the union of a cable with a cylindrical workpiece Other examples are the connection of two cables to each other through the use of an elongated connector with two hollow receptacles at both ends or through the use of a hollow tube, etc. Reference is now made to 6A, which shows, semi-schematically, a device suitable for carrying out the process as described in figures 1 to 5. The device generally designated with the number 40, comprises a control module 42 which can provide a fast intense current discharge, electric electrodes 43 and 44 for current transfer and a forming coil 46. The electric electrodes 43 and 44 are electrically connected to the bina 46 by means of the connectors 47 and 47a, and 48 and 48a. Typically the forming coil 46 protrudes from the surface, for example a work table, represented here by a surface 49 with dashed lines, and the rest of the constituents of the device are hidden below the surface. The forming coil 46 has a lumen 50 into which a workpiece that is to be tightened is inserted. The inner walls of the coil 46 are typically coated by an insulating coating material 51. In this specific embodiment, the device 40 is used for the production of a joint between a cable and a cable projection shown in Figures 1 to 5. As will be appreciated, the device can also be used for several different purposes, for example, the production of a cable connected to the ground, a superconducting cable, the union of two superconducting cables, and various other purposes, some of which are described below. The width of the coil 46 determines the length of the portion which will be tightened when current is discharged through the coil 46. In this specific example, an assembly 52 which comprises a cable projection 53 and the cable 54, which they are in loose association with each other, they are inserted into the lumen 50 so that the cylindrical portion 55 of the projection 53 of the cable is essentially complete within the lumen 50. Then, a strong current is rapidly discharged through the coil 56 and the PMF force which arises consequently of the same, induces the tightening of the walls of the cylindrical portion 55 on the end of the cable 54, so that the two are firmly joined to each other. Figure 6B shows a training coil designated generally with the number 56 which can serve a purpose similar to the coil shown in Figure 6A. To facilitate the description, elements with a function similar to those of the embodiment of Figure 6A have been provided with similar reference numbers with a quote, and the reader is referred to the above description for explanation of their function. As can be seen, the main difference of the coil 56 of the coil 46 in Figure 6A is that it has an arc-like structure. The advantage of such a structure is that, on the one hand, the current is restricted to a narrower space and thus is more effective in forming and, on the other hand, the arcs provide the required strength for such a coil. Figure 7 shows a device according to another embodiment of the invention which, in this specific example, is used for welding or joining a tube on a rod or rod. Similar to the embodiment shown in Figure 6, it is clear that this device can also be used for several different purposes. The device, designated generally with the number 57 comprises a forming coil 58 having a plurality of coils or windings (7 in this specific example) around a tube 59 which is made of an insulating material such as plastic. The device further comprises a power supply 60 connected in parallel to a capacitor bank 61 and a switch 62. The power generator 60 charges the capacitor 61 and, after actuation by means of the switch 62, current is discharged through the coil 58 of training. The two work pieces which are to be joined, which consist, in this example, of a metallic tube 63 and a metallic rod 64, are inserted inside the lumen 65 of the insulating tube 59. In order to weld the two workpieces together, preferably some space 66 is left between the two workpieces, typically about 5-20% of the internal diameter of the tube 63. As can be seen, before discharge of the capacitor 61 there is a fast and intense current flow through the coil 68 which causes eddy currents in the tube 63 and the resulting magnetic pressure causes it to quickly tighten on and to be welded with the rod 64. The length of the portion of the tube 63 which is tightened corresponds to the length of the coil 58. Figure 8 shows a seal 66 between a tube 67 and a rod 68 prepared in a manner described with reference to Figure 7. Based on the intensity of the magnetic pressure used to create the joint, and consequently the speed of movement of the cylinder before impact with the rod, there will be a welding between the two pieces of work or only a firm connection. Figure 9 shows a way of joining two ends of elongated metal objects, according to one embodiment of the invention. The ends 70 and 71 of elongated objects 72 and 73, respectively, are cut or beveled so as to produce two complementary oblique surfaces with a relatively obtuse angle versus the longitudinal axis of the body. The two objects are placed so that the bevels or cut ends touch each other, with their axis slightly out of line with respect to each other. Then, following the application of a strong magnetic force by pulses, as schematically shown by the arrows in Figure 8A, the two segments 70 and 71 impinge on each other and are welded, that is, they become integral with each other. Figure 10 shows a way of joining ends of two superconducting cables, according to one embodiment of the invention. Two superconducting cables 76 and 77, of which only the end portion is shown, consist of a metal matrix 78 made of a metal alloy and filaments 79 made of another metal alloy. In order to have adequate electrical continuity, it is necessary to join the two ends so that the filaments are coextensive. For this purpose, the ends 76 and 77 of the two cables are cut diagonally, similarly to the case of the rods of FIG. 8, and are brought into contact with each other within the lumen 80 of the cylindrical workpiece 82 (FIG. 10B), then, by applying a magnetic force by pulses, represented schematically by the arrows in Figure 10B, the cylindrical workpiece 82 is tightened on the superconducting cable and consequently a firm joint is obtained between the two cables, as shown in Figure 10C.

In figure 11 the way of joining two superconducting cables according to another embodiment of the invention is shown. The end faces 84 and 85 of the cables 86 and 87, respectively, are drilled to obtain a plurality of perforations 88, each corresponding to a filament 89 of the superconducting cable, as can be seen in Figure 11B. A joining member 90 is formed, consisting of projections 92 which correspond to the perforations 88 with the two ends of the superconducting cables, as shown in Figure 11C and then a cylinder 94 is placed on this assembly. Subsequently force is applied magnetic, as shown schematically by the arrows in Figure 10C, and as a consequence the cylinder 94 is tightened over the cable and as a result a firm seal is obtained, as shown in Figure 11D. Figure 12 shows the manner of preparation of a cable cost to earth or electrode, according to an embodiment of the invention. In Figure 12 A a conductor 100 is shown consisting of a core 102 made of an alloy, for example iron, and a coating 104 made of another alloy, for example copper. The conductor 100 can be prepared as explained in relation in figures 7 and 8. A cylinder or envelope made of insulating material such as polyethylene, a ceramic material, etc., is placed over the conductor, the cylinder or envelope that is superimposed for a metal, for example, a copper cylinder as can be seen in Figure 12B. After the application of a magnetic force, represented schematically by the arrows in Figure 12B, the metal cylinder 108 is tightened, which causes a constriction of the insulator 106 to exist so that a firm structure shown in Figure 12C is obtained. . Reference is now made to Figure 13, which shows the schematic representation of the manner of producing a superconducting cable according to an embodiment of the invention. A longitudinal die 110, which is made of an alloy, for example copper, comprises a plurality of longitudinal perforations 112 and filaments 114 made of another alloy and inserted into each of the perforations, as shown in Fig. 13A. After the application of magnetic force by pulses, represented by the arrows in Figure 13A, the entire cable is tightened and subsequently the walls of each of the perforations joins with the filaments to provide a superconducting cable with practically no empty space, as you can see in figure 13B. Reference is now made to Figure 14, which illustrates a heating element 115 consisting of a coil 116 and a bolt assembly 117. The coil 116 is helical and extends between the two bolts. The bolt assemblies 117 consist of an insulating member 118, made of plastic, a ceramic substance, etc., and an electric bolt 119 which extends through the insulating member 118 and terminates in a portion 120 which is in contact with the end portion of the coil 116. The element further comprises two metal sleeves 121 which wrap the ends of the coil 116 which overlap a portion 120 of the pin 119. The sleeve 121 which is tightened in the structure consisting of the portion 120 and the coil 116 and is in tight or firm union of the two elements together which ensures a high quality electrical contact which is highly resistant to erosion which may occur during continuous operation. In Figure 15 a device according to one embodiment of the invention is shown, for use in the joining or welding of elongated objects with one another (in longitudinal cross sections). The device designated generally with the number 122 comprises a forming coil 123 consisting of a plurality of windings, separated from one another by an insulating material 124. The device also comprises a field shaper 126.

As a result of the application of the magnetic force by pulses, a strong magnetic pressure will result in the lumen 128 of the field former and as a result, the cylindrical object is tightened within the lumen. Figure 14A shows two examples of how to use the device to join two hollow tubular workpieces which consist of a first tubular workpiece 130, of a relatively larger diameter, and a second tubular workpiece 132 of a smaller diameter. These two work pieces have respectively a portion 1134 and 136 which are to be welded together. A problem in such a weld is first to properly place the two work pieces so that they are coaxial and, furthermore, it is necessary to provide conditions so that before the impact between the two work pieces, the portion 136 of the second part 132 essentially remains no movement and therefore weld to the portion 134 of the first workpiece. In the example shown in Figure 15A, these two objectives are obtained by using the insert -138 which has the first portion 140 with a diameter equal to the internal diameter of the tubular workpiece 130, and has a second portion 142 which has a diameter equal to the internal diameter of the tubular workpiece 130. The two portions 140 and 142 are coaxial and, accordingly, the first workpiece 130 and the second workpiece 132 are also coaxial. In addition, the portion 142 of the insert 138 supports the portion 136 and therefore, by application of a magnetic force, the portion 134 moves rapidly toward the portion 136 which remains essentially motionless during impact, and therefore the two portions are welded together. The support of the internal walls of a tubular workpiece during impact by an external tubular workpiece can also be obtained by other diverse means. These include, for example, filling the entire cylinder with a non-understandable liquid such as water; introduce into the tube a magnetic liquid such as mercury, oil with suspended metal particles, etc., and then apply a constant magnetic field before PMF so that the magnetic liquid is concentrated in a portion where the support is required; by means of ice frozen in a respective portion; etc. Such support solutions are required, for example, when the inner cylinder is long and therefore it is not impossible to introduce an insert such as that shown in Figure 15A. Figure 15B shows how to use the same device without using an insert. In Figure 15B, the two work pieces are made to be coaxial by using the two annular members 142 and 144. These two ring members can be made from the same alloys as the work pieces 130 and 132, or they can be made from a different alloy. These two annular members help in some way in the conformation of the magnetic field and also serve to improve the quality of the welding: by applying the force PMF, the fast internal movement of the portion 134, the two annular members 142 and 144 are they melt with portions 134 and 136. In order to ensure optimal conditions, i.e., that there will be no constriction of portion 136 to impact, the PMF must be applied in very short pulses, typically for a time which requires approximately or slightly greater than T / 4 (T = 2pt / "LC) The following equation 8 provides an example of an approximate relationship between the various parameters which allows the necessary requirements to be met: 2 μ0Wn2 2 V - (9) where 1 is the length of the work coil n is the number of windings of the work coil, L is the total inductance of the discharge circuit. Figure 15C shows a joint between two tubular work pieces of different diameter. Reference is now made to Figure 16 which shows an embodiment of the invention related to the tightening of walls of a metal tube and internal surfaces welded together. An example of the use of this mode is in the sealing of metal tubes containing a cooling gas used in cooling or heating systems, in refrigerators or conditioning systems, or sealing tubes that contain flammable gas (eg gas for cooking, etc.). Figure 16A is a longitudinal schematic cross section showing a metal tube 145, a portion of which 146 is surrounded by a metal coil 147. By the rapid discharge of current through the coil 147, as shown in FIG. 16B, the magnetic pulses form tightening zones of the walls of the portion 146 and introduce or induce the welding of the inner walls of this portion between yes. As can be seen in Figure 16B, after tightening, there is a thickening of the walls of the portion 146.

Subsequently the portion 146 can be cut in its middle part which provides a sealed end 148 which provides gas outflow from the inside of the tube, represented by the arrows). Figure 17 shows a perspective view of an installation for welding two flat metal workpieces, and in figure 18 they are shown in cross section (in figure 17, the support structure of the coil has been removed with the purpose of illustration facility). In order to join two flat work pieces, essentially a flat coil is used. The flat coil 150 is shown in Figure 7 and has a general shape and size substantially equal to the shape and size of the area of the first workpiece 152, which is to be joined with the second workpiece 154. As s can be seen in Figure 18, the windings 156 of the coil are held in place by a support wall 158 which is fixed on a work plate by means of a fixing member 160. By passing pulses in the coil 150, a flat workpiece 152 moves rapidly downward and, if it impinges on the workpiece 154 fast enough, for example at a speed exceeding 300 m / sec, both Metal work pieces will be welded together. For this purpose, a magnetic force is applied from the direction represented by the arrows in these figures. Reference is now made to FIGS. 19 and 20 which schematically show the welding of a flat workpiece 162 and 162 'onto spherical objects 164 and 164, which are respectively a cylindrical object and a prism-shaped object (which it is shown in cross section.) Reference is now made to Figure 21, which shows a block diagram of an electrical circuit for providing pulsed magnetic force in a device according to an embodiment of the invention. of energy, which may be of multiple channels as in the embodiment shown, and one of a plurality of current circuits 174 (in that mode three are shown) and a field former 182. Each of the circuits 174 comprises a battery 176 capacitor, a forming coil 178 and a pulse discharge switch 180. Each of the switches 180 is under the control of a multiple channel activation generator 172. The electrical energy, which is provided by the power supply 170, is accumulated in a capacitor bank or capacitor bank 176 and follows an energizer provided by the generator 172, the accumulated potential is discharged through the coil 180. A device comprises a plurality of magnetic training circuits and is uniquely provided by the invention. The advantage of such a device is that a suitable synchronization of the activators to each of the switches 180, a series of magnetic forces per pulse can be applied which can be advantageous for numerous applications. In Figure 22 a circuit block diagram according to another embodiment of the invention is shown. In Figure 22, elements similar to those in Figure 21 have been given similar numbers with an indication with quotes. This mode is particularly useful to provide very intense energies. The device comprises a transformer 184 for each of the circuits 174"which comprise a primary coil 186 having a plurality of windings and a secondary coil 188 having a single winding All secondary coils 188 are connected in parallel to form the coil 188. 190 coil It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates. Having described the invention as above, property is claimed as contained in the following:

Claims (11)

1. A method for joining or welding at least two solid portions, characterized in that it comprises forcing the solid portions against each other by inducing rapid movement in at least one of the solid portions so that at least one surface of the portions is caused The same applies to the other of the solid portions, at least one of the solid portions is constituted of, or comprises at least one surface made of an electrically conductive material, and the movement is induced by a magnetic pulsing force which is at a magnitude such that the initial kinetic energy of at least one of the solid portions before impact is equal to or greater than the combined plastic deformation energy of at least one of the solid portions, and the elastic deformation energy of at least two solid portions after the impact, so that at least the two solid portions are joined or welded together. re yes

2. The method according to claim 1, for joining or welding the two solid portions, each one is an elongated portion on a separate workpiece; at least one first portion, which is a portion on which it is to be worked is hollow, the dimensions of the two solid portions initially being such that they can be placed one on top of the other; the method is characterized in that it comprises: (a) inserting one of the two solid portions into the hollow interior of the other; (b) causing the surfaces of the first elongated portion, on which to be worked, of a first workpiece, to move towards opposite surfaces of the other elongated counterpart of the second workpiece by means of a force magnetic field by pulses, so as to cause the surfaces of the portion to be worked on to impinge on the opposite surfaces of the opposite portion at a speed such that the kinetic energy of the portion on which it is to be worked, in movement, of the first work piece before impact is greater than a combination of the plastic deformation energy of the moving portion and the elastic deformation energy of the opposite portion after impact; so the two portions are joined or welded together.

3. The method according to claim 2, characterized in that the portion on which it is going to work is a cylindrical receptacle and the opposite portion is a cable.

4. The method according to claim 3, characterized in that the metallic cable is joined or soldered to a connector.

5. The method according to claim 2, characterized in that the first workpiece is a shell or matrix of a superconducting wire made of an alloy, and the second workpiece is one or more filaments made of a second alloy inserted in a lumen. or longitudinal perforations of the superconducting cable; the method comprises inserting the filaments into the lumen or perforations and then constricting the matrix or envelope by means of the magnetic force by pulses.

6. The method according to claim 2, characterized in that it is used for the production of an electrode connected to the ground.

7. The method according to claim 1, characterized in that it comprises inducing rapid movement in all of the solid portions.

8. The method according to claim 7, characterized in that it comprises constricting the walls of a tube and joining or welding the internal faces thereof to each other.

9. The method according to claim 2, characterized in that the velocity U of the surface of the portion of the solid on which it is worked, before the impact with the opposite surface of the opposite portion, is represented approximately by the following equation (1) : where U is the velocity of the moving surface of the portion on which it is going to work before the impact, mx is the mass of the portion on which it is going to work, and A ± and A2 are the deformation energy plastic of the portion on which it is going to work, and the elastic deformation energy of the opposite portion, respectively, which can be calculated according to the following approximate equations (2) and (3): (3) A, = s1V1eln 1/1 + d > )) / (r02 / r2-l) where r01 and r02 are, respectively, the radii of the portions on which it is going to work and on the opposite portion, before the deformation, r? And r2 are, respectively, the radii of the portions on which it is going to work and of the opposite portion, after the deformation, dL and d2 are the tenacity of the material, Vi and V2 are respectively, the volumes circumscribed within the portions on which one is going to work and inside the opposite portion, after the deformation and ° "and s2 are the relative extension of the portion on which it is going to work and of the opposite portion, respectively, calculated in accordance with the following equations (4) and (5) .- (4) or? r? »? -01 (5) • 02

10. The method according to claim 9, characterized in that the working voltage V is calculated by the following approximate equations (6) and (7): (6) km1U2Ll1 W = 4pμ0r01h (i) V c where W is the energy stored in the capacitor's battery, k is a coefficient which depends on the parameters of the PMF device and the parameters of the work coil, L is the total inductance of the electric discharge circuit, 1 is the length of the work coil, μ0 is the magnetic permeability in vacuum h is the thickness of the space between the work coil and the work piece, U, m and r01 are as defined in accordance with claim 9.

ll. The method according to claim 1, characterized in that at least two portions are essentially flat and are welded together.