Method and device for a martensitic-free soldering process

Abstract

FIELD: soldering.SUBSTANCE: inventions relate to temperature-controlled soldering and can be used to attach an element made of an electrically conductive material to a metal surface. The heat required for soldering is generated by striking an electric arc between a carbon electrode and an electrically conductive connecting element, wherein the voltage and current are controlled by electronic control devices to achieve a temperature that results in martensitic soldering, wherein the applied direct current voltage uses the carbon electrode as a negative pole and the electrically conductive connecting element as a positive pole, wherein the end of the carbon electrode facing the electric arc is tapered, beveled or pointed.EFFECT: martensitic-free soldering, which also reduces energy consumption and heat generation and facilitates soldering of cable lugs for electrical wires with large cross-sections.16 cl, 15 dwg

Description

[0001] Field of technology to which the invention relates

[0002] The present invention relates to an improved soldering method, such as joining an element of an electrically conductive material, such as a metal, to a metal surface by means of an improved type of temperature-controlled soldering.

[0003] Technology Level

[0004] There are temperature-controlled brazing methods that, for certain types of materials, such as steel, can achieve martensite-free brazing, meaning brazing occurs without any harmful structural changes (martensite formation) in the component. This brazed joint is achieved so that the part underneath the brazed joint is more or less free of martensite formation, for example, in railroad tracks (rails), pipes / pipelines, and wind turbines. The present invention relates to an improved method and a device for implementing the improved method.

[0005] The development of rail transport is associated with ever-higher speeds and higher axle loads. This, in turn, places increased demands on the strength and wear resistance of railway tracks. Consequently, rails are manufactured from higher-alloy steel to meet these more stringent requirements. The material from which rails are made is sensitive to thermal influences, which can cause structural changes known as martensite formation (a hardening effect).

[0006] The formation of martensite can lead to cracks in the rail material, and under higher loads, the rail may break, resulting in catastrophic consequences for rail traffic. Therefore, it is crucial to securely solder signal and other wiring and cables to the rail using a method that does not cause martensite formation.

[0007] The prior art in this area includes document GB 2376202 B, which discloses a method and apparatus for a martensitic-free soldering process.

[0008] Essence of the invention

[0009] The most serious problem with current methods applied to railway tracks is the large amount of heat generated under the soldered joint, which is caused by the electric arc created during the soldering process and causes harmful structural changes or the formation of martensite.

[0010] The essence of the present invention includes a specially designed electrode used in the process and additional means for controlling the electrical voltage and current used in the process. The advantages of the method include reduced heat generation, lower power consumption, and the ability to successfully solder electrical conductors with a larger cross-sectional area compared to conventional technology. Currently, it is virtually impossible to connect large cables (i.e., those with a cross-sectional area greater than 25-35 square millimeters) using conventional soldering technology without significant martensite formation. Testing of the proposed method on a conductor with a cross-sectional area of ​​120 square millimeters demonstrated good results, with minimal or no martensite formation after soldering.

[0011] The present invention relates to a new temperature-controlled soldering method and apparatus for implementing said method, which reduces martensite formation, energy consumption, and heat generation. Furthermore, the new method facilitates soldering of cable lugs for electrical wires with large cross-sections.

[0012] The purpose of the present invention is to generate an electric arc using a carbon electrode so as to perform a soldered connection of a part with a rail without direct contact of the electric arc with the rail, and to obtain a connection of the same or better quality compared to the prior art, but with lower energy consumption and lower heat generation.

[0013] Another goal is to facilitate soldering of electrical conductors over a larger area than the state of the art allows.

[0014] In embodiments of the invention, the carbon electrode itself forms an electrical resistance during the soldering process, and the length, diameter and shape of the carbon electrode affect the electrical resistance in said process and, therefore, also affect the current and voltage during the soldering process.

[0015] The carbon electrode provides optimal arc length control during soldering because the carbon material has good heat-resistant properties, while the metal electrode melts. Consequently, the carbon electrode undergoes minimal length change during soldering compared to a melting metal solder pin.

[0016] Another goal of this soldering process, as applied to attaching a cable lug or other conductive contact joint to a steel rail, is to prevent direct contact of the electric arc with the component. This is achieved when the conductive contact joint consists of a continuous plate of a solid conductive material, such as copper. The soldering process in this context does not involve flux or solder from any soldering pin forming the electrode. Solder must not flow through the cable lug to the underlying component (the rail). Due to the design of the cable lug, the flux and solder are located under the electrical contact joint or the cable lug itself. The entire plate of solid conductive material, such as copper, forms a buffer, preventing excessive heat from affecting, for example, the rail and causing martensite formation.In addition, the electrode does not end up in the solder joint, thus eliminating the risk of adversely affecting the solder joint.

[0017] Another objective of the present invention is to control the current strength during the process. Raising the electrode increases the arc length. This, in turn, leads to a large voltage drop across the arc and a reduction in current in the electrical circuit. Arc length cannot be increased arbitrarily, as after a certain length, the arc is extinguished due to excessive resistance. A small distance between the electrode and the workpiece, the so-called rise height, reliably prevents arc extinguishing during soldering. A low current during the process is highly preferable, as this prevents the formation of martensite.

[0018] In the present invention, it is preferable to use a ceramic protective ring, but a protective ring consisting of a combination of both metal and ceramic materials may also be preferable because the result of the combination enhances the protection provided by the soldering gun.

[0019] The material and design of the containment ring play a significant role in energy consumption. The containment ring according to embodiments of the present invention is designed with a larger diameter to avoid high containment ring temperatures and to accommodate a larger volume of hot gases.

[0020] The protective ring and grip sleeve also prevent operator contact with the arc itself or the hot gases generated. This reduces the operator's need for protective equipment. It also eliminates the risk of eye injury for the operator and others looking toward the arc during the soldering process.

[0021] According to a first aspect of the invention, a method is provided for soldering an electrically conductive connecting element, such as a cable lug, made of an electrically conductive material to a part made of an electrically conductive material by means of a temperature-controlled soldering process, in which the heat required for soldering is generated by igniting an electric arc between a carbon electrode and the electrically conductive connecting element, this method includes the following steps:

[0022] - provide DC voltage between the carbon electrode and an electrically conductive connecting element, such as a cable lug;

[0023] - measure the voltage occurring on the specified arc; - measure the electric current of the specified arc;

[0024] - control the voltage applied between said carbon electrode and said first part and, therefore, on said arc;

[0025] - calculate in real time, continuously or permanently, the electrical power developed in the specified arc, wherein the method additionally comprises the steps of

[0026] - measure the current in the specified arc and the voltage on the specified arc continuously or constantly in real time, and

[0027] - calculate in real time, continuously or permanently, the corresponding developed electrical power as the mathematical product of the specified current and the specified voltage, and

[0028] - control the DC voltage and thus the specified developed electrical power,

[0029] wherein the applied DC voltage uses the carbon electrode as the negative pole and the conductive connecting member as the positive pole, and

[0030] in this case, the end of the carbon electrode facing the electric arc is tapered or pointed.

[0031] The method may also include the following:

[0032] - accept operator input data about the cross-sectional area of ​​the conductor, and

[0033] - Use the specified input data to adjust the calculations and control the DC voltage to achieve and maintain a suitable soldering spot temperature.

[0034] According to a second aspect of the invention, a device is provided for soldering an electrically conductive connecting element to a part made of an electrically conductive material by means of a temperature-controlled soldering process, in which the heat required for soldering is generated by igniting an electric arc between a carbon electrode and the electrically conductive connecting element, this device includes:

[0035] (a) a means for ensuring contact of an electrically conductive connecting element with a part, including a protective ring and a carbon electrode,

[0036] (b) an electrode support means comprising a means for moving the electrode between a position in which it contacts an electrically conductive connecting element, in turn contacting said contact providing means, and a retracted position in which it is raised therefrom;

[0037] (c) a DC voltage unit for providing and supplying a DC voltage of a specific polarity between said electrically conductive connecting element and said carbon electrode, wherein the DC voltage unit includes a voltage regulation unit,

[0038] (d) a voltage sensor for measuring the specified voltage between the conductive connecting element and the carbon electrode,

[0039] (e) a current sensor for measuring the electric current passing through said carbon electrode;

[0040] (f) processing means including means for generating an output signal controlling said voltage regulation unit, and further including means for calculating in real time, continuously or constantly, the electrical power developed in said arc,

[0041] (g) a switch configured to connect said means for applying voltage in an electrical circuit to said electrode and to said electrically conductive connecting element, whereby when said means for providing contact is applied and the switch is actuated to close said electrical circuit, said means for supporting and moving causes the electrode to be lifted from the part to strike an electrical arc between the electrode and the electrically conductive connecting element, and

[0042] (h) wherein the carbon electrode is provided with a pointed, tapered or beveled first end for an electric arc,

[0043] (i) wherein the DC voltage unit is configured such that the determined polarity is that the applied DC voltage uses the carbon electrode as a negative pole and the electrically conductive connecting member as a positive pole.

[0044] Furthermore, the device may be configured to automatically provide heating using a first electrical power during a first period of the total soldering time and a second electrical power during a second period of the total soldering time. Preferably, the first electrical power is set to quickly heat the soldering site, while the second electrical power is lower than the first electrical power and has a value that ensures maintaining the achieved temperature at the soldering site.

[0045] For additional heating customization, a process can be configured with three or more different periods of varying heat delivery. For example, a process could include four periods or stages: Stage 1 - rapid heating, Stage 2 - slow heating, Stage 3 - temperature maintenance, and Stage 4 - slow cooling.

[0046] The device may be further provided with input elements for setting the corresponding parameters of the electrical cross-sectional area of ​​the conductor to be soldered, and the processor is configured to calculate the time and voltage for soldering, taking into account the parameters, to ensure the corresponding voltage and time for generating the appropriate amount of heat during the corresponding period of time.

[0047] This will have the advantage that the soldering will be more precisely adjusted, such as in terms of time and temperature.

[0048] According to a third aspect, a cable lug for martensitic soldering is provided, wherein the front portion is formed as a solid plate capable of being soldered to a workpiece, the rear end is formed to define a cable cavity for the cable, and the cable lug is further configured such that the cable cavity is extended into a tapered cavity, which ensures that the cable lug has a uniform cross-sectional area along its length from the solid plate to the beginning of the cable cavity. Tests have convincingly shown that cable lugs provided with an extended cavity reduce the power required to perform the soldering process. Furthermore, the solid plate in the front portion can be provided with a solder, such as a certain amount of silver alloy with or without flux, which is preferably attached to the solid plate by pressing or melting.It is particularly preferable to manufacture a cable lug by pressing a soldering staple containing a silver alloy onto a hard plate.

[0049] Brief description of drawings

[0050] Embodiments of the present invention are disclosed below in more detail with reference to the accompanying drawings, in which:

[0051] Fig. 1A shows a schematic diagram of the soldering process;

[0052] Fig. 1B shows a fragment of Fig. 1A.

[0053] Fig. 1C schematically shows the directions of movement of ions and electrons of the soldering arc;

[0054] Fig. 1D schematically shows the directions of movement of ions and electrons of the soldering arc, with reverse polarity compared to Fig. 1C;

[0055] Fig. 2 shows a partial side view of a soldering gun according to an embodiment of the invention;

[0056] Fig. 3 shows a cross-sectional view of a soldering gun;

[0057] Fig. 4 shows a side view in partial longitudinal (axial) section;

[0058] Fig. 5 shows the soldering operation on the rail;

[0059] Fig. 6 shows the soldering operation on a section of a pipeline;

[0060] Fig. 7 shows a soldered joint between the outer and inner rims of the wheels of a railway car;

[0061] Fig. 8 shows an electrically conductive connecting element in the form of a cable lug, viewed from the side;

[0062] Fig. 9 also shows a side view of the cable lug;

[0063] Fig. 10A shows a top view of the cable lug;

[0064] Fig. 10B shows a rear view of the cable lug of Fig. 10A;

[0065] Fig. 10C shows a side view of the cable lug of Fig. 10A;

[0066] Fig. 10D shows a front view of the cable lug of Fig. 10A;

[0067] Fig. 11 shows a voltage / current / temperature graph of the soldering process according to the prior art;

[0068] Fig. 12A shows a voltage / current / temperature graph of the soldering process according to the new method applied to the first cross-sectional area;

[0069] Fig. 12B shows a current / voltage / temperature graph of the soldering process according to the new method applied to the second cross-sectional area;

[0070] Fig. 13 shows the front view of the main input panel for inputting the soldering parameter(s);

[0071] Fig. 14A shows a block diagram of the regulation and control of the soldering process;

[0072] Fig. 14B shows a block diagram of the steps of the method;

[0073] Fig. 15A shows a partial view of the front part of the soldering gun, partly in longitudinal (axial) section.

[0074] Fig. 15B, C, D are side views of carbon electrodes according to embodiments of the present invention;

[0075] Fig. 15E shows a top view of a round electrode, and below it a top view of a square electrode.

[0076] Implementation of the invention

[0077] Fig. 1A schematically illustrates the necessary components and the procedure of the soldering process itself according to the corresponding embodiment, wherein the typically used power source is a battery 1, from which current is supplied to the electronic unit 2. The electronic unit 2 is configured to process data received from the soldering gun 5 via the power cable and the signal cable, as well as data from an external power source. The electronic unit 2 is configured to process all information and regulate the current and voltage supplied to the soldering gun 5, for example, by electronically regulating the voltage level. By said regulation, it is possible to control the time and current consumption during the soldering process, and thus, it is possible to ensure satisfactory soldering with minimal energy consumption, as well as in combination with temperature control in the base material / part.

[0078] When the switch 3 closes the electric circuit containing the lifting magnet in the soldering gun 5, the carbon electrode 6 located in the electrode holder 7 first short-circuits the circuit with the cable tip 10, so that when the electromagnet then lifts the carbon electrode 6 from the cable tip 10 to ignite an electric arc 8, which is protected by one or more protective rings 9, it operates on the hard flat surface of the cable tip 10, with the cable tip forming one pole and the carbon electrode 6 forming the other pole. Heat is transferred through the cable lug 10 and activates the flux between the cable lug 10 and the solder 12 and prepares and cleans the soldering surface between the solder 12 and the cable lug 10, and when the solder 12 is heated, it activates the flux 13 on the part 14, whereby a soldered joint is formed on the part 14 using the solder 12.In this way, the cable lug 10 will be firmly soldered to the part 14 without direct contact of the electric arc 18 with the said part 14.

[0079] In addition, no unwanted sparks / arcs are generated between part 14 and cable lug 10 because the electrical circuit passes through the cable of cable lug 10 or through the protective ring 9, and not through part 14 itself.

[0080] In the new soldering process, the entire plate of a solid conductive material, such as copper, forms a buffer that prevents high temperatures, such as those experienced on a rail, from causing martensite formation. Copper particles will be ejected from the plate of the cable lug during soldering and deposited as a thin layer on the carbon electrode (see Fig. 1C). During the soldering process, a small cavity may form in the cable lug 10. The cable lug may be designed to accommodate such a cavity without significantly compromising the mechanical strength of the cable lug.

[0081] Figure 1D schematically shows the directions of movement of ions and electrons in a soldering arc with polarity reversed compared to Figure 1C. The oval area indicates the width of the arc, suggesting that a thinner, more focused arc is achieved using the polarity corresponding to the negative carbon electrode (Figure 1C), while a wider or more diffuse arc will be obtained by connecting the carbon electrode to the positive polarity. Tests have shown that choosing the negative polarity of the carbon electrode reduces the energy required to perform soldering. The reduction in energy consumption is approximately 30%.

[0082] From an energy perspective, the protective ring plays an important role during the soldering process. The protective ring 9 is designed to exhibit good heat insulation. The protective ring 9 can be made of a ceramic material and provided with a serrated lower edge. In this case, the hot gases generated during the soldering process are discharged radially. When the protective ring is made of metal with a smooth lower surface, the gases will leave the protective ring axially, and therefore more heat will be transferred to the protective ring 9. The protective ring 9 maintains its shape and function and remains stable throughout the soldering process. The heat absorbed by the protective ring is transferred to the cable lug 10. As a result, less electricity and / or power is consumed during the soldering process, and martensitic soldering is achieved.

[0083] Fig. 2 shows a side view of the soldering gun 5, in the front part of which the carbon electrode 6 is visible. Before the soldering process begins, the gun 5 together with the carbon electrode 6 is pressed against the cable tip 10, as a result of which the carbon electrode 6 will be pressed flush with the lower edge of the protective ring 9. The protective ring 9 is fixed in the ring holder 15. When the switch or start button 3 is pressed, a short circuit of the circuit occurs, after which the lifting magnet raises the electrode 6 to a certain height above the conductive connecting element and the arc 8 is ignited. The protective ring 9 and the gripping sleeve 18 protect the operator from the process. The drawing also shows a screw 16 for removing the protective ring and a screw 17 for removing the electrode. During the soldering process, the protective ring 9 can act as a terminal during the grounding operation if it is made of metal or other electrically conductive material.

[0084] Fig. 3 shows a section of the soldering gun 5 from the front, where the switch 3 is visible, and in the center of the neck of the gun there is a carbon electrode 6 in the electrode holder 7 together with the ring holder 15 and the gripping sleeve 18.

[0085] Fig. 4 shows a sectional view of the end portion of the soldering gun 5, showing the circuit breaker 3, the carbon electrode 6 in the electrode holder 7, and the protective ring 9 made of ceramic material in the ring holder 15 together with the gripping sleeve 18, the screw 16 for removing the protective ring, and the screw 17 for removing the electrode. The carbon electrode is a very important component in the soldering process, generating electrical resistance, and the electrical resistance in the process is influenced by the length, diameter, and shape of the carbon electrode. The current and voltage during the soldering procedure are controlled by electronic control means. The electronic control means are configured to provide voltage and current as a function of time in accordance with Fig. 12B, 12C, and 12D to achieve a suitable soldering temperature at the soldering point, see below.

[0086] Figure 5 shows a soldering gun 5 being applied to a rail 14. A conductive element in the form of a cable clamp is firmly soldered to the rail head. Soldering can also be performed on the rail neck or foot.

[0087] Figure 6 shows a soldering gun 5 being used on a component 14, which is a section of pipeline. A conductive connecting element 10, in the form of a cable lug, is firmly soldered to the pipe. Strict requirements are particularly imposed on pipelines at nuclear power plants, where soldering must be performed without introducing structural changes into the pipeline material that could lead to cracks. In cases where pipes are filled with gas or oil, as well as when they are filled with temperature-sensitive materials, such as in the chemical industry, the ability to work at low temperatures during soldering is essential.

[0088] Figure 7 shows a railway car wheel. The inner wheel 20 is attached to the wheel axle 21, and a damper 23, for example made of a rubber material, is located between the inner wheel and the outer wheel ring 19, the so-called tread. The drawing shows how a connecting element 22 made of an electrically conductive connecting material connects the inner wheel 20 to the outer wheel ring 19 to allow current to flow from the railway car to the track. Due to the risk of martensite formation and the associated cracking, no attempts have been made to use pin brazing in this connection.

[0089] This soldering process eliminates the formation of martensite in any case and allows soldering to be carried out in this area as well.

[0090] Fig. 8 shows a side view of a cable lug 10, a connecting element made of an electrically conductive material, where a terminal connector 24 with an electrical circuit is visible. The terminal connector 24 is attached to an electrical cable 25 leading to the cable lug 10, the other side of which consists of a solid plate 26 made of a hard material. Around this solid plate 26 made of a hard material, a soldering clip 27 is located, pressed to the plate 26 of the cable lug 10 itself during manufacture, and between the cable lug 10 and the soldering clip 27, a flux 28 is provided, which is activated during the soldering process.

[0091] Fig. 9 also shows a side view of the cable lug 10, in which the soldering itself is performed on a flat, solid plate 26 of the cable lug 10 using a soldering gun 5, and in which one can see a soldering clip 12 pressed onto the cable lug 10, a flux 11 heated between the bottom of the cable lug 10 and the soldering clip 12. Between the part 14 and the clip 27, another flux 13 is provided, which is activated when the soldering clip 27 is heated and begins to clean the part 14 before soldering the electrically conductive connecting element 10.

[0092] Soldering clip 12 has a uniform thickness before being applied to the part to which it is attached. After the solder melts under the heat applied through the hard plate 26 of the cable lug 10, the surface tension of the molten material wetting the hard plate 26 and the part 14 causes a thickness change, meaning that the distance between the hard plate 26 and the part, i.e., the area occupied by the solder, is minimized, ensuring strong adhesion and good electrical and thermal conductivity between the hard plate 26 and the part.Flux 11 and 13 perform the following tasks and have the following properties: 1) cleans the surfaces, 2) removes any oxides present, 3) prevents re-oxidation, 4) is displaced by the molten solder, 5) acts as an electrical conductor when the cable lug 10 is grounded via the rail, 6) facilitates heat dissipation due to the fact that it has good thermal conductivity, and 7) wets the surfaces to be joined.

[0093] Another requirement is that fluxes 28 and 29 must be activated within a specific temperature range. The flux, solder, and soldering process must be coordinated. The flux will be activated at the beginning of the soldering process and will continue to be active until the soldering is complete.

[0094] Soldering performed at temperatures above 500°C is called hard soldering, as opposed to soft soldering, which occurs at lower temperatures. The solder used in the soldering process described above is designed for hard soldering. However, the flux designed for hard soldering is not suitable for this process, as it occurs too quickly, in approximately 2 seconds. This soldering process uses flux 10, which is typically suitable for soft soldering and therefore activates at a lower temperature, but does not disintegrate before the soldering process is complete due to its short working time.

[0095] To achieve the required soldering temperature while using as little energy as possible, a high power input is required in a short period of time. Rail tracks, thick-walled pipes, and similar metal profiles are effective heat sinks. High power input creates a thermal front that moves through the cable lug into the rail, where the temperature becomes suitable for hard soldering but does not lead to martensite formation.

[0096] Cable lug 10 acts as a buffer against localized overheating and ensures a relatively smooth temperature distribution across the entire surface of the melt. Indirect heating occurs via carbon electrode 6. An electric arc 8 is formed between carbon electrode 6 and cable lug 10. This contrasts with conventional pin soldering, in which the arc acts directly on the rail and / or soldering with molten solder on the rail.

[0097] Fig. 10A shows a cable lug 10 in a top view. The front part is formed as a solid plate 26, on which a soldering clip 27 is mounted. The dotted line indicates the outline of the cable cavity 31 for the cable. The cable lug 10 is also formed such that the cable cavity 31 of the cable is extended into a narrowing cavity 33, designed to give the cable lug 10 a uniform cross-sectional area from the solid plate to the beginning of the inserted cable.

[0098] Fig. 10B shows a rear view of the cable lug of Fig. 10A.

[0099] Fig. 10C is a side view of the cable lug of Fig. 10A, and Fig. 10D is a front view of the cable lug of Fig. 10A.

[0100] A cable lug for martensitic soldering is provided, wherein the front portion is formed as a solid plate capable of being soldered to a workpiece, the rear end is formed to form a cable cavity for the cable, and the cable lug is further configured such that the cable cavity is extended into a tapered cavity designed to give the cable lug a uniform cross-sectional area along its length from the solid plate to the beginning of the cable cavity. Tests have convincingly shown that cable lugs provided with an extended cavity reduce the power required to perform the soldering process. Furthermore, the solid plate of the front portion can be provided with a solder, such as a certain amount of silver alloy with or without flux, which is preferably attached to the solid plate by pressing or melting.It is particularly preferable to manufacture a cable lug by pressing a soldering staple containing a silver alloy onto a hard plate, thereby attaching it to the hard plate.

[0101] In railway signaling systems and cathodic protection systems operating at low voltages and currents, it is especially important to have low total contact resistance in the solder joints 50 to prevent interference in the system.

[0102] At high currents and voltages, high contact resistance generates heat in the soldered joint, which can damage and / or melt it. For this reason, it is important to have low contact resistance in the soldered joint, as the joint must also withstand high reverse currents in the railway operating system. For the same reason, it is also important to have low contact resistance in protective grounding connections.

[0103] Fig. 11 shows a voltage / current / temperature graph of a soldering process according to the prior art.

[0104] Figures 12A and B show the voltage / current / temperature graph of the new soldering process. Compared to existing pin soldering, there is no such large current surge when a short circuit occurs. The voltage and current curves are comparatively more constant over time. The graph demonstrates that the present invention provides optimal control of the soldering process. Consequently, the temperature during the soldering process can also be adjusted and controlled, which is a prerequisite for achieving martensitic-free soldering.

[0105] Compared to some prior art non-martensitic soldering methods, the device and method according to the present invention may include a two-phase process in which the voltage is automatically controlled to provide heat using a first electrical power during a first period of the total soldering time and a second electrical power during a second period of the total soldering time. Preferably, the first electrical power is set to quickly heat the soldering points, and the second electrical power is lower than the first electrical power and has a value that ensures maintaining the achieved temperature at the soldering point.

[0106] Figure 12A shows the voltage / current / temperature graph of the soldering process according to the new method applied to the first cross-sectional area. A strength of the new method is the ability to achieve soldering of large cross-sectional areas. The soldered cross-sectional area underlying the graph in Figure 12A is 16 mm2.

[0107] Fig. 12B shows a current / voltage / temperature graph of the soldering process according to the new method as applied to a second cross-sectional area. The soldered cross-sectional area underlying the graph in Fig. 12B is 120 sq. mm.

[0108] Fig. 13 shows a front view of the main input panel for entering the soldering parameter(s). Buttons, keys, or input knobs are provided for entering the settings, i.e., by repeatedly pressing the settings button, a list is scrolled for selecting a setting from a list of preset settings for different cross-sectional areas, for example, 10, 16, 25, 35, 50, 70, 95, and 120 square millimeters. The settings may include voltage and / or current, as well as time periods for providing a certain voltage / current, as also shown in Fig. 12A and 12B. In addition, the panel includes a display showing the current setting. In addition, the panel may include fuses and / or control indicators, as well as an on / off button. In addition, the input panel may additionally have connectors for connecting plugs to a soldering gun, for connecting grounding, and for connecting a charger for charging the soldering device batteries.

[0109] Fig. 14A shows a block diagram of the regulation and control of the soldering process.

[0110] Fig. 14B shows a flow chart of the method steps. A method is provided for soldering an electrically conductive connecting element, for example, a cable lug made of an electrically conductive material to a part made of an electrically conductive material using a temperature-controlled soldering process, in which the heat required for soldering is generated by igniting 1410 an electric arc between a carbon electrode and the electrically conductive connecting element, this method comprises the following steps:

[0111] - provide 1401 electrically conductive connecting element, such as cable lug;

[0112] - provide 1401 parts of conductive material;

[0113] - provide 1405 carbon electrode;

[0114] - provide 1405 DC voltage between the carbon electrode and an electrically conductive connecting element, such as a cable lug;

[0115] - measure 1415 voltage occurring on the specified arc;

[0116] - measure 1420 electric current of the specified arc;

[0117] - control 1425 the voltage applied between said carbon electrode and said conductive connecting element and, therefore, on said arc;

[0118] - calculate 1430 in real time, continuously or permanently, the electrical power developed in the specified arc, wherein the method additionally has the steps in which

[0119] - measure 1435 the current in the specified arc and the voltage on the specified arc continuously or constantly in real time, and

[0120] - calculate 1440 in real time, continuously or permanently, the corresponding developed electrical power, as the mathematical product of the specified current and the specified voltage, and

[0121] - control 1445 DC voltage and thus the developed electrical power,

[0122] wherein the applied DC voltage uses the carbon electrode as the negative pole and uses the 1445 electrically conductive connecting member as the positive pole, and

[0123] in this case the end of the carbon electrode facing the electric arc is tapered, beveled or pointed.

[0124] The method may further include the steps of automatically providing heating using a first electrical power for a first period of time of the total soldering time and providing a second electrical power for a second period of time of the total soldering time. Preferably, the first electrical power is set to quickly heat the soldering site, and the second electrical power is lower than the first electrical power and has a value that ensures maintaining the achieved temperature at the soldering site.

[0125] Fig. 15A shows a sectional view of the front part of the soldering gun 5 with the gripping sleeve 18 in the retracted position, and the electrode extractor 40 is shown with a screw 16 for extracting the protective ring and a screw 17 for extracting the electrode. Also shown are the extracted carbon electrode 6 and the extracted protective ring 9.

[0126] Fig. 15B-15E show changing shapes of a carbon electrode having different angles Beta at the apex and angles Alpha a of the bevel, as shown in Fig. 15F. The carbon electrode can have a round or rectangular, in particular a square cross-section. A round cross-section is preferred. Thus, the carbon electrode is provided with a pointed or beveled end, preferably having an angle Beta β at the apex of from 90 to 150 degrees, and more preferably an angle of from 100 to 140 degrees, and even more preferably from 110 to 130 degrees, and most preferably from 118 to 122 degrees.

[0127] The basic concept of the present invention is to combine various functions and methods so that they interact to produce an improved soldering process. This interaction results in a new soldering process that avoids structural changes or martensite formation, saving energy and facilitating the soldering of conductors with large cross-sectional areas. The soldering process utilizes a carbon electrode, the length and diameter of which affect the resistance in the electrical circuit. The carbon electrode, equipped with a pointed or beveled end, acts as a temperature buffer and heat distributor. Furthermore, an electric arc is maintained between the carbon electrode and the smooth end of the cable lug (see below), which has a stabilizing effect on the arc and counteracts the tendency of currents to fluctuate over time.

[0128] The cable lug has at least one smooth end made of a solid, electrically conductive material, which is exposed to an electric arc from a carbon electrode. The underside of the cable lug has a solder clip, which is attached during manufacturing. Soldering creates a large-area solder joint, which reduces the overall electrical contact resistance. Flux is present between the cable lug and the solder clip, as well as between the solder clip and the component, and the flux, solder, and soldering process are appropriately matched. The solder is suitable for soft soldering and is therefore active in a low temperature range, ensuring a martensitic-free solder joint.

[0129] The advantages of using a guard ring during soldering, such as one made of metal or another similar material, include the overall process requiring less energy and simplifying the grounding procedure compared to previous methods. Grounding through a guard ring eliminates the need for special grounding contacts, such as ground terminals or magnetic grounding contacts, as well as the need for special preparation of the grounding holder. Since a new guard ring is used for each grounding situation, the contact surfaces are guaranteed to always be clean.

[0130] The device according to the invention reduces the length of the grounding circuit and eliminates additional transition resistance, as well as sources of secondary sparks and arcs between the cable lug and the workpiece. The shape of the protective ring, together with the gripping sleeve, protects the operator from electric arcs and hot gases during the soldering process.

[0131] Using metal shielding rings affects the soldering process because they use more energy generated as heat and direct it to the ferrule.

[0132] Therefore, in order to achieve satisfactory soldering in terms of temperature, not much electricity should be supplied to the soldering process.

[0133] In previously known methods, the total resistance in the circuit can be considered constant. Lower power consumption should, in practice, mean shorter process times. However, in this case, the time becomes too short to achieve satisfactory soldering.

[0134] By adjusting the additional resistance and / or adjusting the voltage, the duration of the soldering process can be controlled, and thus satisfactory martensite-free soldering can be achieved with minimal energy consumption, and in addition, the temperature of the base material / part can also be controlled.

[0135] Some previously known methods adopted broad limitations on the electrical power developed during the process, as well as the total energy released and the overall process duration. Current was limited either by incorporating a fixed electrical resistance into the circuit or, alternatively, by interrupting the process once the required amount of released energy had been expended. Neither battery voltage fluctuations depending on the battery's state of charge, discharge characteristics, or other factors were taken into account, nor were current changes during the same soldering operation due to changes in electrode length or arc oscillations, nor were current changes between different soldering operations due to changes in lift height.These variations, coupled with simple, imperfect mechanisms for estimating the amount of energy released, resulted in different times and different power outputs for otherwise comparable soldering processes, as well as difficulties in temperature control in the materials involved.

[0136] In the new soldering process described above, shown in Fig. 14, the soldering temperature and the resulting martensite formation can be controlled by calculating the developed electrical power and adjusting it in real time using either an analog procedure or a high-resolution digital procedure. The developed power is calculated by instantaneously measuring the current and voltage, and the actual power is calculated as the mathematical product of these quantities. The calculated result is processed and fed to a processing unit, the output of which affects the voltage regulation unit. In this way, the voltage and, consequently, the current are regulated, and the developed electrical power is adjusted to the desired value.The processing unit, which may either exist as a separate unit or may be included in the electronic unit 2, processes data in the form of current and voltage values, data from transmitting sensors and operating adjustments, externally connected units, as well as measured elapsed time, and processes these data taking into account physical, mathematical and logical structures in such a way that proper regulation of the developed power occurs over a period of time.

[0137] As an example, operator input data about the cross-sectional area of ​​the conductor is used by a processor, which is configured to adjust a control signal to control the voltage to create a current that produces the right amount of energy to heat and maintain a suitable temperature during soldering.

[0138] Furthermore, since regulation is independent of the power circuit's resistance, there is no need for a fixed resistor, resulting in energy savings due to the heat generated by the resistor. Furthermore, more energy can be recovered from the batteries, as at the end of the discharge cycle, the batteries can still discharge despite the low voltage level, as there is no fixed resistor.In addition, the formation of the arc at the starting point of the process is facilitated for two reasons: on the one hand, because the height of the electrode lift and thus the arc length and hence the subsequent starting inertia can be reduced to a minimum without any risk of excessive currents, which in some previous methods caused problems with temperature and problems with the control technology, while, on the other hand, much higher current and voltage values ​​are allowed at the starting point of the process than was possible until now, without being limited by a fixed resistance resistor, and therefore a reliable start of the process can be guaranteed.

[0139] In the new soldering process disclosed above, the aforementioned processing unit can also be configured to process signals from external transmitting sensors, such as temperature sensors, as well as operating adjustments whose values ​​affect the output of the processing unit. Furthermore, signals from external units, such as battery chargers, generators, and electric motors, are processed; these signals are also processed in the processing unit, generating appropriate control signals as output data to also control the unit(s) of this type.

[0140] The drawings illustrate only some embodiments of the invention, but it should be noted that many other modifications can be developed within the scope of the following claims.

[0141] In a preferred embodiment, the carbon electrode is provided with a tapered, pointed or beveled end having an apex angle Beta β of from 70 to 150 degrees, more preferably having an apex angle of from 70 to 110 degrees, and even more preferably an apex angle of from 90 to 110 degrees.

Claims

1. A method for soldering an electrically conductive connecting element (10) made of an electrically conductive material to a part (14) made of an electrically conductive material by means of a temperature-controlled soldering process, in which the heat required for soldering is generated by igniting an electric arc (8) between a carbon electrode (6) and the electrically conductive connecting element (10), this method comprising the following steps: - provide (1405) direct current voltage between the carbon electrode (6) and the conductive connecting element (10); - measure (1415), continuously or constantly in real time, the voltage arising on the specified arc (8); - measure (1420), continuously or constantly in real time, the electric current of the specified arc (8); - calculate (1430) in real time, continuously or permanently, the electrical power developed in the specified arc (8), as the mathematical product of the specified measured values ​​of voltage and electric current; - control (1425) said voltage applied between said carbon electrode (6) and said electrically conductive connecting element (10) and, consequently, on said arc (8), and, thus, said calculated electrical power, wherein the applied DC voltage uses the carbon electrode (6) as a negative pole and the conductive connecting element (10) as a positive pole, characterized in that This method is carried out using a carbon electrode (6), the end of which facing the electric arc (8) is made tapered, beveled or pointed.

2. The method according to claim 1, further comprising the steps of - accept operator input data on the cross-sectional area of ​​the conductor, and - use the specified input data on the conductor cross-sectional area to adjust the calculations and control the DC voltage to achieve and maintain a suitable solder point temperature.

3. The method according to claim 1 or 2, further comprising the step of automatically providing heating using the first electrical power during a first period of time of the total soldering time and the second electrical power during a second period of time of the total soldering time.

4. The method according to claim 1, further comprising the steps of lifting the electrode (6) from the first part (14) to ignite an electric arc (8) between the electrode (6) and the electrically conductive connecting element (10).

5. The method of claim 1, wherein the pointed, tapered or beveled end of the carbon electrode has an angle at its apex of from 90 to 150 degrees, more preferably from 100 to 140 degrees, and even more preferably from 110 to 130 degrees, and most preferably from 118 to 122 degrees.

6. A device for soldering an electrically conductive connecting element (10) to a part (14) made of an electrically conductive material by means of a temperature-controlled soldering process, in which the heat required for soldering is generated by striking an electric arc (8) between a carbon electrode (6) and the electrically conductive connecting element (10), wherein this device includes: (a) a means for ensuring contact of the electrically conductive connecting element (10) with the part (14), including a protective ring (9) and a carbon electrode (6), (b) electrode support means (6) comprising means for moving the electrode (6) between a position in which it is in contact with the electrically conductive connecting element (10), in turn in contact with said contact means, and a retracted position in which it is raised from it; (c) a DC voltage unit (1) for providing and supplying a DC voltage of a specific polarity between said conductive connecting element (10) and said carbon electrode (6), wherein said DC voltage unit (1) includes a voltage regulation unit, (d) a voltage sensor for measuring said voltage between the conductive connecting element (10) and the carbon electrode (6), (e) a current sensor for measuring the electric current passing through said carbon electrode (6); (f) processing means comprising means for generating an output signal controlling said voltage regulation unit and further comprising means for calculating in real time, continuously or permanently, the electrical power developed in said arc (8), (g) a switch (3) configured to connect said means for supplying voltage in an electric circuit to said electrode (6) and to said electrically conductive connecting element (10), wherein, when said means for ensuring contact is applied and the switch (3) is actuated to close said electric circuit, said means for supporting and moving ensures that the electrode (8) is lifted from the part (14) to ignite an electric arc (8) between the electrode (6) and the electrically conductive connecting element (10), and (h) wherein the DC voltage block (1) is designed such that the determined polarity is such that the applied DC voltage uses the carbon electrode (6) as a negative pole and the electrically conductive connecting element (8) as a positive pole, characterized in that The carbon electrode (6) is provided with a pointed, tapered or beveled end facing the electric arc (8).

7. The device according to claim 6, in which the voltage regulation unit is configured to automatically provide heating using the first electrical power during a first period of time from the total soldering time and the second electrical power during a second period of time from the total soldering time.

8. The device according to claim 7, in which the value of the first electrical power is set to quickly heat the soldering place, and the processing means is configured to calculate the value of the second electrical power, which is lower than the first electrical power, to maintain the achieved temperature at the soldering place.

9. The device according to claim 6, in which the device is provided with input organs for setting the corresponding parameters of the electrical cross-sectional area of ​​the conductor to be soldered, and the processor is configured to calculate the time and voltage for soldering taking into account the parameters to ensure the corresponding voltage and time for generating the appropriate amount of heat during the appropriate period of time.

10. The device according to paragraph 7, 8 or 9, including a gripping sleeve (18) around said protective ring (9), wherein the protective ring (9) together with the gripping sleeve (18) protects the operator from the arc (8) and from hot gases.

11. The device according to item 10, in which the gripping sleeve (18) is designed with the possibility of extracting the spent electrodes (6) and safety rings (9) during longitudinal movement.

12. The device according to any one of paragraphs 6-11, in which said processing means is further configured to control external units, such as battery chargers, generators and electric motors, for regulating them.

13. The device of any one of claims 6 to 12, wherein the pointed, tapered or beveled end of the carbon electrode has an apex angle of from 90 to 150 degrees, and more preferably an angle of from 100 to 140 degrees, even more preferably from 110 to 130 degrees, and most preferably from 118 to 122 degrees.

14. A device according to any one of paragraphs 6-13, in which the electrically conductive connecting element (10) has on one side a layer of solder metal (12), with a layer of flux (13) between the part (14) and the layer of solder metal (12).

15. The device according to claim 14, in which the layer of metal (12) of solder is provided with a soldering clip attached to said part.

16. The device according to claim 15, including an electrical connection to the connecting element (10) to provide a grounding contact for said device.