The present disclosure relates to a welding method of Copper wire with Dumet wire, and particularly relates to a method of weld ability of braided stranded Copper wire with thermistor Dumet wire, using resistance welding.
BACKGROUND
Welding of Copper wire with Thermistor Dumet wire has been known in the industry for a long time. In conventional technology, there is no direct way of joining a braided Copper wire with the thermistor Dumet wire. In fact, it is difficult to join them together and is not preferred for manufacturing. Conventionally, a terminal is known to be used as an intermediate part between the braided Copper wire and the thermistor NTC element part Dumet wire (semiconductor for measuring resistance with respect to temperature). The terminal being used as the intermediate part acts as a compatible material to join the two.
Terminal crimping process is one of the most reliable processes to join terminal and copper wire, wherein a terminal and wire crimping is done in the crimping machine. The terminal is placed into the Applicator (Terminal Crimping Tool), then at a wire exit end with fixed measured length is stripped and inserted into the terminal at desired location in the applicator tool placed in the crimping machine. In some machines wire stripping is done separately, then terminal and wire crimping and in some machine machines wire stripping and terminal with wire crimping is done in auto terminal crimping machine in sequence by auto. Machine senses the position of the wire after placement and vertical stroke operated by motor mechanism pushes the crimping punch with the bottom anvil resulting in completion of crimping process. Terminal is crimped with the wire and with the

insulation wire. This process is a widely accepted weld process in a manufacturing industry and ensures a repetitive and good strength joint.
However, the conventional methods have a few demerits, one of them being that the terminal is an additional item and increases overall costs of materials being used. Further, braided wire stripping and trimming are additional processes that require machines, thereby adding to equipment costs and conversion costs. Furthermore, terminal crimping with wire is an additional critical process and requires special tooling and machinery. In addition, terminal manufacturing requires manufacturing tool, plating, which adds to the overall costs. Moreover, when using the existing techniques, defects are generated in wire and terminal crimping process, such as voids, less crimping force, terminal cut section profile, terminal crimping on wire insulation, and terminal bends, etc.
SUMMARY
This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention.
The present disclosure relates to a method of welding of braided stranded Copper wire with a Dumet wire. The method involves resistance welding of copper wire with thermistor Dumet wire. This helps in eliminating the need of using a terminal, thereby helping in reducing the extra machinery and material costs involved when a terminal is used for the welding process.
In an embodiment, a method for welding a Dumet wire to a copper wire includes creating an anchor at an end of the Dumet wire, wherein the anchor has an open end and a loop end. In addition, the method includes anchoring a wiring end of the copper wire by passing an end of the copper wire through the anchor of the

Dumet wire. Further, the method includes pressing the anchor to close the open end of the anchor and trapping the wiring end between the open end and the loop end to form a temporary joint. The method also includes joining the anchor to the wiring end at the temporary joint using resistance welding.
To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Figures 1A represents a top view and a side view of the thermistor used with wire and terminal crimping general process;
Figure IB depicts a method wherein the terminal is being used as an intermediate between the Copper wire and Dumet wires for welding;
Figures 2 illustrates a method for joining the ends of a thermistor having Dumet wire with copper wires, according to an embodiment of the present disclosure
Figure 3 A which illustrates a setup for trimming the wiring ends of the copper wire, according to an embodiment of the present disclosure;

Figure 3B which illustrates the wiring end of the copper wire where wire stripped and Wire Twisting done, according to an embodiment of the present disclosure;
Figure 3C which illustrates stripped twisted wire being wire compacting through resistance welding process (Solidification of wire strands into single joint namely illustrated as compacted wire),cutting of a pigtail of the wiring end, according to an embodiment of the present disclosure;
Figure 3D illustrates an anchoring setup to form a temporary joint between an anchor of the Dumet wires and the copper wire, according to an embodiment of the present disclosure;
Figure 3E illustrates a pair of anchors at the ends of a first compacted wire and second compacted wire, according to an embodiment of the present disclosure;
Figure 3F illustrates temporary joint trapping of the wiring end in the anchor, according to an embodiment of the present disclosure;
Figure 3G illustrates anchoring of the wiring end of the compacted copper wire to the Dumet wire, according to an embodiment of the present disclosure;
Figure 4 illustrates an alternate joining method of spiralling the Dumet wire around the copper wire, according to an embodiment of the present disclosure; and
Figures 5 illustrates a resistance welding setup for converting the temporary joint into a permanent joint, according to an embodiment of the present disclosure.
Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have necessarily been drawn to scale. For example, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

DETAILED DESCRIPTION OF FIGURES
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the invention and are not intended to be restrictive thereof.
Reference throughout this specification to "an aspect", "another aspect" or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a nonexclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or subsystems or elements or structures or components proceeded by "comprises... a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.
It should be understood at the outset that although illustrative implementations of the embodiments of the present disclosure are illustrated below, the present invention may be implemented using any number of techniques, whether currently known or in existence. The present disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary design and implementation illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.
The term "some" as used herein is defined as "none, or one, or more than one, or all." Accordingly, the terms "none," "one," "more than one," "more than one, but not all" or "all" would all fall under the definition of "some." The term "some embodiments" may refer to no embodiments or to one embodiment or to several embodiments or to all embodiments. Accordingly, the term "some embodiments" is defined as meaning "no embodiment, or one embodiment, or more than one embodiment, or all embodiments."
The terminology and structure employed herein is for describing, teaching, and illuminating some embodiments and their specific features and elements and does not limit, restrict, or reduce the spirit and scope of the claims or their equivalents.
Reference is made herein to some "embodiments." It should be understood that an embodiment is an example of a possible implementation of any features and/or elements presented in the attached claims. Some embodiments have been

described for the purpose of illuminating one or more of the potential ways in which the specific features and/or elements of the attached claims fulfil the requirements of uniqueness, utility, and non-obviousness.
Use of the phrases and/or terms such as but not limited to "a first embodiment," "a further embodiment," "an alternate embodiment," "one embodiment," "an embodiment," "multiple embodiments," "some embodiments," "other embodiments," "further embodiment", "furthermore embodiment", "additional embodiment" or variants thereof do NOT necessarily refer to the same embodiments. Unless otherwise specified, one or more particular features and/or elements described in connection with one or more embodiments may be found in one embodiment, or may be found in more than one embodiment, or may be found in all embodiments, or may be found in no embodiments. Although one or more features and/or elements may be described herein in the context of only a single embodiment, or alternatively in the context of more than one embodiment, or further alternatively in the context of all embodiments, the features and/or elements may instead be provided separately or in any appropriate combination or not at all. Conversely, any features and/or elements described in the context of separate embodiments may alternatively be realized as existing together in the context of a single embodiment.
Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
Figures la and lb illustrate aspects of a conventional resistance welding method of a thermistor 100 having NTC Dumet wire 102 with a Copper braided wire 104 using a Terminal 106. Particularly, Figure 1A represents a top view and a side view of the thermistor 100, whereas Figure IB depicts a method wherein the terminal 106 with copper wire 104 is being used as an intermediate between the Dummet Wire 102 for welding. The thermistor 100 includes the Dumet wire 102 that is integrated NTC Thermistor Assembly. As shown in Figure 1 A, the ends of

the Dumet wire 102 and the copper wire 104 are not connected directly, but instead, are connected to the terminal 106. Thus, the thermistor 100 with dummet wire 102 requires an additional component in ideal case. Further, as shown in Figure IB, the terminal 106 and one ends of Dumet wire 102 need to be joined by resistance welding by placing the Dumet wire 102 and the terminal 106 between the pair of electrodes 108 and 110 to perform the resistance welding. On the other hand, the terminal 106 and the copper wire 104 are joined by wire and terminal crimping process. As may be understood, the ends of terminal 106 and the copper wire 104 are crushed which can weaken the joint and can fail under stress. Thus, the conventional technique to couple the copper wire to the Dumet wire 102 warrant the use of additional component and is not robust.
The present disclosure relates to method 200 for joining the ends of a thermistor having Dumet wire with copper wires. The technique of the present disclosure eliminates the use of a terminal by creating a temporary joint which can be made permanent by resistance welding. Thus, the technique of the present disclosure enables direct joining of the Dumet wire with the copper wire.
The order in which the method steps are described below is not intended to be construed as a limitation, and any number of the described method steps can be combined in any appropriate order to execute the method or an alternative method. Additionally, individual steps may be deleted from the method without departing from the spirit and scope of the subject matter described herein.
Referring now to Figure 2, the method 200 begins at step 202 at which the copper wire is stripped and twisted simultaneously and compacted through resistance welding process, flattening the wire strands forming solid wire.
Further, at step 204, an anchor is created at an end of the Dumet wire, such that the anchor has an open end and a loop end. Further, at step 206, a wiring end of the copper wire is anchored to the anchor by passing an end of the copper wire

through the anchor of the Dumet wire. Furthermore, at step 208, the anchor is pressed to close the open end of the anchor and trap the wiring end between the open end and the loop end to form a temporary joint. Finally, at step 210, the anchor is joined to the wiring end at the temporary joint using resistance welding.
Details of the aforementioned method 200 are better illustrated with respect to Figure 3A which shows a setup 300A for trimming the wiring ends of the copper wire 302A, 302B, Figure 3B which shows the copper wire stripped process dully twisted in machine and left over portion wire end as pig tail wiring end of the copper wire. Figure 3C which shows compacting process through resistance welding 310 a on the stripped and twisted braided strands copper wire portion and then cutting of a pigtail 316 of the wiring end. Further, Figure 3D shows an anchoring setup 300D to form a temporary joint between an anchor of the Dumet wires 306 and the copper wires 3 02A, 302B and Figure 3E shows a pair of anchors at the ends of a first compacted copper wire 3 02A and second compacted copper wire 302B. Further, Figure 3F shows temporary joint trapping of the wiring end in the anchor and Figure 3G shows anchoring of the wiring end of the copper wire 3 02 A, 302B to the Dumet wire 306.
In one example, the copper wire 302A, 302B may be a single-strand copper wire. Alternatively, the copper wire 302A, 302B can be a braided copper with multiple strands as shown in Figure 3B. In case of multiple strands 310, the multiple strands 310 are compacted to form a single strand. One of the ways to compact the multiple strands to form the single strand is by twisting the multiple strands 310. In one example, compacting the multiple strands 310 may result in the formation of pigtail 316 as shown in Figure 3B. Referring now to Figure 3C, the pigtail 316, in one example, may be trimmed to achieve a single strand of uniform thickness. The uniform thickness of the single strand allows the better engagement between the copper wire 302A, 302B and the Dumet wire 306. In one example, the pigtail 316 is trimmed by clamping the wiring end on a fixture plate 318 of the trimming setup 300A. Thereafter, a lever 320 may be operated which pushes a cutter 322 on the

pigtail 316 to cut off the pigtail 316. Once the pigtail 316 is trimmed, the copper wire 302A, 302B is ready for anchoring. Prior to the anchoring, the wiring end may be stripped off any protective coating over the strands to facilitate the anchoring.
Referring now to Figures 3D to 3G, the thermistor 300 has a bulb end with a pair of Dumet wires 306. Further, the Dumet wire 306 may have a coating to protect it from heat. In order to attach to the copper wire 302A, 302B, the ends of the Dumet wire 306 may be modified to clamp the wiring ends. In one example, to clamp the wiring ends of the copper wire 302A, 302B, the ends of the Dumet wire 306 may be converted to an anchor as shown in Figure 3E. The anchor can either be made by manually bending the ends of the Dumet wire 306 or by bending with the help of the anchoring setup 300D. Referring now to Figure 3D, the anchoring setup 300D may include a platform 324 on which thermistor 300 can be placed when the anchors are formed. The anchoring setup 300D also has a clamp 326 that secures the Dumet wires 306, such that the ends of each Dumet wire 306 hangs from a side of the anchoring setup 300D.
The ends can be transformed by creating an anchor at the end. In one example, the anchor can be created by bending the end of the Dumet wire 306 up to a length of the copper wire 302A, 302B. The anchor so formed may have an open end 328A and a closed end 328B. The anchor can be either formed manually by hand or by use of a tool or a machine setup. Once the anchor is formed, the copper wires 302A, 302B may be attached to the Dumet wire 306. Referring now to Figure 3F, a wiring end of a first copper wire 3 02 A is passed through the anchor of the first Dumet wire 306 and a wiring end of a second copper wire 302B may be passed through the anchor of the second Dumet wire 306. In the illustrated example, the passing of the wiring end is done either manually or by a dedicated setup. Once passed, the wiring ends of the first copper wire 3 02 A and the second copper ends 302B are passing through an opening formed by the open end 328A and the closed end 328B.

Referring now to Figure 3G, the anchored wiring ends may be secured temporarily to the anchor using the anchoring setup 300G. The anchoring setup 300G may include a fixture 330 having a slot 332 to secure the thermistor 300 thereon. The anchoring setup 300G also includes a puncher 334 having a punch profile 336. As clearly shown, the punch profile 336 is designed to press both the anchors of the first compacted copper wire 3 02 A and the second compacted copper wire 302B. Further, the puncher can be actuated by an actuator 338, such as a manually operated lever or pneumatic plunger. The actuator 338 is adapted to press the sides of the anchor, such that the open end 328 A may be closed and the wiring end is trapped between the open end 328A and the closed end 328B. Once pressed, a temporary joint is formed which can further proceed to obtain a permanent joint.
While the foregoing embodiment relates to the formation of a U-shaped anchor to attach the wiring end, other techniques may be employed in case the Dumet wire 306 is long. For instance, for a Dumet wire 306 of length up to 10 mm, forming the U-shaped anchor may be implemented. On the other hand, in the case of long Dumet wire 306, the wiring end of copper wire 302A, 302B can be wrapped around the end of the Dumet wire 306. An exemplary embodiment is shown in Figure 4 which shows a method of spiralling the copper wire 3 02 A, 302B around the Dumet wire 306. As shown in Figure 3D, the spiralling can be formed on an anchoring setup 300D. Specifically, a tip of the wiring end of the first copper wire 302A is worn around the end first Dumet wire 306. thereby forming many loops around the end of the first compacted copper wire 302A as seen in (A) of Figure 4. A similar operation the repeated to spiral the second copper wire 302B around the end of the Dumet wire 306 as seen in (B) of Figure 4.
Referring now to Figure 5 which shows a welding setup 500 for converting the temporary joint into a permanent joint, according to an embodiment of the present disclosure. The welding setup 500 may be an assembly of various welding units 503A, 503B, and 503C, commonly referred to as 502 hereinafter, Further, each welding unit 502 may include a pair of movable jaws 504 that holds the copper

wire 302A, 302B and a clamp 506 opposite to the pair of movable jaws 504. The clamp 506 may hold the Dumet wire 306 and is positioned adjacent to the jaws 504, such that a gap is formed therebetween. The setup 500 may also include a pair of electrodes 508 that are installed in the gap between the clamps 506 and the jaws 504. Further, the electrodes 508 is positioned can travel orthogonal to the clamp 506 and the jaws 504 and can make contact with the temporary joint.
In order to join the wiring end 3 02 A, 302B to the end of the Dumet wire 306, the pair of electrodes 508 may be made pushed against the opposite sides of the anchor and pressure may be applied for a predefined time. In one example, the predefined time is in the range of 150 to 170 milliseconds. Thereafter, electric current may be applied across the sides in accordance with various control parameters. The electric current can be either a direct current or an alternating current and the electrode can be made of Tungsten
In one example, the parameters can be following:

Parameter name Value Unit
Pressure 140-170 Milliseconds (mS)
Weld Current 2.3-2.8 Kilo volt ampere (kVA)
Voltage 0.4 Volt
Power 0.2 Kilowatt
Weld Time 170-220 mS
Hold Time 180-300 mS
Force 145-185 Newton (N)
The permanent joint so formed is capable of withstanding a pulling force of about 1.5 Kilogram Force (KgF). As a result, the copper wire is joined with the Dumet wire 306 having adequate strength without the use of a terminal. As a result, the joint so formed is strong, has less parts and thus is more robust.

While specific language has been used to describe the present disclosure, any limitations arising on account thereto, are not intended. As would be apparent to a person in the art, various working modifications may be made to the method to implement the inventive concept as taught herein. The drawings and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment.

We Claim:

1. A method for welding a Dumet wire (306) to a copper wire (302A, 302B),
comprising:
creating an anchor at an end of the Dumet wire (306), wherein the anchor has an open end (328A) and a closed end (328B);
anchoring a wiring end of the copper wire (3 02 A, 302B) by passing an end of the copper wire (302A, 302B) through the anchor of the Dumet wire (306);
pressing the anchor to close the open end (328A) of the anchor and trap the wiring end between the open end (328A) and the closed end (328B) to form a temporary joint; and
joining the anchor to the wiring end at the temporary joint using resistance welding.
2. The method as claimed in claim 1, wherein the copper wire (302A, 302B) is one of a single strands copper wire and a braided copper wire having multiple strands (310).
3. The method as claimed in claim 2, comprising compacting multiple strands (310) of the wiring end (306) to form a single strand of the wiring end prior to the anchoring.
4. The method as claimed in claim 3, comprising trimming a pig tail formed during the compacting of the multiple strands (310).
5. The method as claimed in claim 1, wherein anchoring the wiring end comprises spiralling the wiring end around the anchor.
6. The method as claimed in claim 1, wherein joining the anchor to the wiring end comprising:

mounting the temporary joint on a fixture and contacting the opposite sides of the joint by a pair of electrodes (508);
applying a pressure for a predefined time by the pair of electrodes (508) across the joint; and
passing an electric current across the temporary joint in accordance with a set of predefined control parameters to fuse a portion of the trapped wiring end and the anchor to form a permanent joint.
7. The method as claimed in claim 6, wherein the predefined time is in range of 140 to 170 milliseconds (mS).
8. The method as claimed in claim 6, wherein the set of control parameters comprising:
welding current in range of 2.3 to 2.8 Kilo volt ampere (kVA);
voltage of about 0.4 Volts;
power of about 0.2 Kilowatt (KW);
welding time in range of 170 to 220 mS;
hold time in range of about 180 to 300 mS; and
force in range of about 145 to 185 Newtons (N).
9. The method as claimed in claim 6, comprising stripping a protective coating the wiring end prior to the anchoring.
10. A thermistor (300) comprising a first Dumet wire (306) and a second Dumet wire (306) coupled to the first copper wire (302A) and the second copper wire (302B) resulting by a method as claimed in claim 1.