CLIAMS:1. A method of forming a contact button on a terminal, said method comprising steps:
roughening surface of the terminal;
fixing a wire material on the roughened surface; and
forming the wire material into the contact button.
2. The method of claim 1, wherein the roughening of the surface is in form of serrations.
3. The method of claim 2, wherein the serrations are formed by embossing.
4. The method of claim 2, wherein the serrations are in any or a combination of shape of regular or irregular lines, regular or irregular triangular, rectangles, pentagons, hexagons, rings, semicircle.
5. The method of claim 2, wherein ridges of the serrations do not project outside total thickness of the terminal.
6. The method of claim 1, wherein the fixing of the wire material on the roughened surface is carried out by welding.
7. The method of claim 1, wherein the button is a preformed button.
8. The method of claim 7, wherein the preformed button is fixed to the terminal by welding.
,TagSPECI:TECHNICAL FIELD
[0001] The present disclosure relates to low and medium voltage electrical equipment. More particularly, the present disclosure relates to a method for improving bonding strength between contact buttons and corresponding electrical terminal.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art
[0003] Electrical contacts have widespread applications in our everyday life ranging from use of electrical contacts in household appliances to industrial electrical equipment. Electrical contacts are the core parts of electrical equipment responsible for the make and break of electrical current. Though direct electrical terminals can be provided, the preferred and time honored method is to provide button contacts on terminals/ blades through which the primary electrical contact between two terminals/ blades is provided. This is because the end of terminals are subjected to very high temperatures/ heat/ etc., particularly during make/ break/ short-circuiting/ sparking etc., and terminal thus needs to be protected for ensuring reliability and increasing their operational life. Contact buttons on the other hand can be made from harder materials or materials, which have better resistance to high temperature/ short circuit/arcing etc. Thus longer operational life, higher reliability and temperature sensitivity can be provided to electrical terminals by use of contact buttons. Thus performance of contact buttons and its reliability has direct bearing on the make-break capacity, service life and reliability of the whole electrical equipment that they are applied to. Depending on their usage/ application, electrical contact/ terminals with contact button are manufactured in different shape and sizes. Contact buttons are generally attached to the base material of terminals/ blades by riveting, brazing, welding, etc. Welding can be a two stage process wherein the first stage can include the process of welding of wire material (same as that of contact button) on base material and second stage can consist of formation and shaping of the contact button into a desired shape.
[0004] Another factor that affects performance of contact button can be bonding strength between the terminal and the contact button. Contact buttons in the past have been fixed with terminals using various methods, , by riveting, welding, brazing etc., depending on the requirements and use of the terminal. Many times decision for selection of material, method of attachment, etc., is primarily dictated by requirement of adhesive bond strength between terminal and contact button, available technology, fast or slow operations, etc., and such decisions are always tempered with cost considerations. But whatever be the material or technology selected the requirement of further improving the reliability and strength of bonding between contact button and terminal cannot be overlooked/ ignored.
[0005] Prior art US 2706759 discloses a method of producing refractory contacts which have projection welding type ferrous metal backings. Welding type ferrous metal backings are made between two layers of contact button and/ or one side of contact button (the side which is attached/ welded to base material of terminal). However this method has the disadvantage that special tools are required to make projections on the contact button. Since contact buttons are of small size and too much time is required to make such projections. Further contact buttons can easily deform during this process.
[0006] There is therefore a need in the art to design and develop systems and methods by which above shortcomings and disadvantages can be overcome and whereby the bonding strength between contact button and terminal and the operational life of terminal can be further increased.
[0007] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0008] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0009] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0010] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0011] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

OBJECTS OF THE INVENTION
[0012] It is an object of the present disclosure to provide a method for fixing a contact button on a terminal whereby bonding strength between contact button and base metal of the terminal is increased.
[0013] It is another object of the present disclosure to provide a method for fixing a contact button on a terminal whereby the reliability and operational electrical life of contact button is increased substantially.
[0014] It is an object of the present disclosure to provide a method whereby the reliability and operational life of bonding between contact button and base metal terminal is increased.
[0015] It is an object of the present disclosure to eliminate process variations that result in variation of bonding strength between contact button and base material from piece to piece.

SUMMARY
[0016] The Present disclosure relates to electrical terminals fixed with contact buttons. More particularly, the present disclosure relates to a method and system for fixing the contact button to the terminal that improves the bonding strength between the base material of terminal and contact button.
[0017] In an aspect the disclosed method comprises steps of formation of serrations on the terminal or base metal by making/ roughing up the surface of base material or terminal on which the contact button has to be formed, fixing of wire material on serrated area of terminal, and working of fixed wire material into a desired shape for formation of the contact button. In another embodiment of the present disclosure, a contact button whether in form of wire material or a preformed contact button can be attached to the serrated/roughened area of terminal/base material of terminal by direct welding. In another embodiment, method of fixing a contact button on terminal can also include riveting or brazing.
[0018] In another embodiment the process of button formation on the terminal can semi-automatic or fully automatic process.
[0019] In another embodiment of the present disclosure, serration /making/ roughing up the predefined/ identified area of the base material for attachment of contact button can be done either manually or through semi-automatic process or through fully automatic process.
[0020] In another embodiment, the serrations can be in shape of regular or irregular lines, regular or irregular triangular/ rectangles/ pentagons/ hexagons/ etc., or in shape of rings, semicircle, etc. or any other regular or irregular shape or size and design. In yet another embodiment of the present disclosure, the ridges of the serrations do not project outside the total thickness of terminal. In another embodiment of the present disclosure, the serrations can project out from the base material of terminal.
[0021] In an embodiment of the present disclosure, contact buttons can be formed/ attached on one or two or more sides of the terminal. In yet another embodiment, multiple contact buttons can be formed on one terminal.
[0022] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components

BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0024] FIG. 1A illustrate a typical terminal without serrated/roughened area in accordance with prior art.
[0025] FIG. 1B illustrates an exemplary terminal with serrated/roughened area in accordance with an embodiment of the present disclosure.
[0026] FIG. 2 illustrates an exemplary terminal with contact button attached to roughened area in accordance with an embodiment of the present disclosure.
[0027] FIG. 3 illustrates an exemplary process flow chart of method used for fixing contact bottom on a terminal in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION
[0028] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0029] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0030] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0031] Embodiments of present disclosure provide a method for fixing a contact button on a terminal, the method includes steps of formation/generation of serrations on the surface of terminal or base metal on which the contact button has to be attached/ formed, fixing of wire material on base terminal and working of the wire material for formation of the contact button of a desired shape. Alternatively a preformed contact button can be fixed to serrated area of the terminal. In another embodiment of the present disclosure, wire material or a preformed contact buttons can be attached to the serrated/roughened surface of the terminal/base material of terminal by direct welding. In another embodiment, method of fixing can also include riveting or brazing or any other suitable process.
[0032] In an embodiment, formation of serrations/roughening of base material of terminal also improves the hardness on account of cold working and along with increased surface roughness contributes to increase in bonding strength between base metal/terminal and contact button. In example embodiment, size, shape, design selected for roughened area can vary based on requirements of size and shape of contact button.
[0033] In an aspect formation of serrations on the terminal surface results in increased bonding area between contact button and base material that can result in increased bonding strength. The increase in bonding strength can be of the order of 5% to 30% or even more. Bonding strength between base terminal/metal and contact button can depend on the method and size, shape, design selected for roughened area. In another aspect increased bonding strength can also result in many fold increase in electrical and operational life of the terminals.
[0034] In another embodiment of the present disclosure, serration/making/ roughing up the predefined/ identified area of the base material for forming of contact button can be done either manually or through semi-automatic process or through fully automatic process. The process can depend on size of the surface to be worked upon and/or extant/shape/size of serration/making/ roughing up required.
[0035] In another embodiment, the serrations can be in shape of regular or irregular lines, regular or irregular triangular/ rectangles/ pentagons/ hexagons/ etc., or in shape of rings, semicircle, etc. or any other regular or irregular shapes of different sizes and design. In yet another embodiment of the present disclosure, the ridges of the serrations do not project outside the total thickness of terminal. In another embodiment of the present disclosure, the serrations can project out from the base material of terminal.
[0036] In another embodiment of the present disclosure, the process followed for formation of contact button on the base material of terminal is a fully automatic process.
[0037] In an embodiment of the present disclosure, contact buttons can be formed on one or two or more sides of the terminal. In yet another embodiment, multiple contact buttons can be formed on one terminal.
[0038] Embodiments of the present disclosure and their advantages can be best understood by reference to attached drawings.
[0039] FIG. 1A illustrates a typical terminal 100 without serrated/roughened area in accordance with prior art. As depicted therein the terminal 102 has a smooth surface on which contact button 104 has been formed. With such a method of fixing a contact button on the terminal, the bonding strength between contact button 104 and terminal 102 may not exhibit consistency and in few instances the contact button may come off under different and especially adverse operating conditions such as passage of high current rendering the electrical equipment unusable. Therefore, the process of fixing the contact button 104 to the base terminal 102 needs to be further improved so as to provide a consistently strong bond between base terminal 100 and contact button 102 that is maintain over long periods of time. The bond should be capable of withstanding current fluctuations, abnormal situations, such as short circuit, extra heating etc.
[0040] FIG. 1B illustrates an exemplary electrical terminal 150 with serrated/roughened surface in accordance with an embodiment of the present disclosure. Depicted therein is the contact button 154 placed over serrated surface156 of the terminal 152. In an embodiment of the present disclosure, a contact button 154 can be fixed to the terminal 152 by any one of the welding, brazing or riveting processes. Also contact button 154 can be formed in desired shape after fixing of a wire or a preformed contact button can be formed over the serrated/roughened surface 156 by any of the mentioned processes. In an aspect increased bonding area between the two parts as a result of formation of serrations, bonding strength between base metal 152 and contact button 154 can be consistent and strong enough to hold the contact button in position over a long time without weakening the bonding. In an example embodiment, serration can be provided only on the base metal/terminal 152 before fixing the contact button 154 over it. In another embodiment, serration can be provided on base metal/terminal 152 as well on bottom face of the contact button154.
[0041] In example embodiment, introduction of serrations on base metal/terminal 152 can also increases hardness besides surface roughness of the base metal and two together can provide consistently good bonding strength between the welded/fixed component such as contact button 154 and terminal 152. In an example embodiment, contact button 154 that is fixed with base metal/terminal 152 can be of preformed shape, size and design, or shape, size and design of contact button 154 can be formed during or after welding .
[0042] FIG. 2 illustrates an exemplary terminal 200 with contact button formed on roughened area in accordance with an embodiment of the present disclosure. Depicted therein is roughened/serrated area 206 of the terminal 202 to which contact button 204 can be formed in accordance with an embodiment of the present disclosure. The contact button 204 can be formed on the base metal/terminal 202 through the process of welding or by any other known process such as riveting, brazing, welding, etc. In example implementations, the size of roughened area 206 can be either more than or less than the contact surface area of contact button 204 with base terminal 202. Further the roughened area 206 can be of any shape or size or design as per aesthetic and practical requirements.
[0043] As discussed earlier, the contact button 204 can be shaped after welding or can be preformed contact button. Contact button 204 can be composed of any material or a combination of materials. Terminal 202 can be of any shape, size and design and all shape, size and design of terminal 202 and contact button 204 are encompassed within the scope of the present disclosure.
[0044] In an embodiment, contact button 204 can be formed on the base terminal 202 by a manual or semi-automatic or fully automatic process. In another embodiment making/ roughing up the predefined/ identified area /serration area 206 on the base metal/terminal 202 for formation of contact button 204 can be done either manually or through semi-automatic process or through fully automatic process.
[0045] The process of serration, or creation of rough and hard surface on base metal/terminal 202, can be done by a programmable system that can receive the input such as size, and design of serration from a user or can create a serration area 206 based on a predefined pattern.
[0046] In another embodiment of the present disclosure, making/ roughing up of the area 206 on base material of terminal 202 can be done by making serrations on the base material. In another embodiment, the serrations can be in shape of regular or irregular lines, regular or irregular shapes such as triangular/ rectangles/ pentagons/ hexagons/ etc., or in shape of rings, semicircle, etc. or any other regular shape or size and design.
[0047] In another embodiment of the present disclosure, contact button 206 can be made of any material or a composite material, or a riveted contact, or a profiled contact, or a staked contact assembly, or a welded contact assembly, or a contact tape plate, or a brazing contact, etc.
[0048] FIG. 3 illustrates an exemplary process flow chart 300 for fixing a contact button over a base terminal in accordance with an embodiment of the present disclosure. The process of present disclosure for fixed a contact button on a base terminal provides consistent and improved bonding strength between contact buttons and base terminal that is maintained over extended period of time. The method includes steps of, selecting a region of interest on base metal/terminal where a contact button needs to fixed/placed, processing the base metal/terminal to create serration/roughening of selected region of interest, and fixing the contact button over the select and serrated area. As illustrated in FIG. 3, at step 302, selection is made for area of interest on base metal where the contact button needs to be fixed. Selection /marking of area of interest can be done either through a manual or semi-automatic or automatic process. In an example implementation, a programmable system can take user input to create an area of interest or can use pre-defined parameters to mark the area of interest. At step 304, the base metal/terminal can be processed to create serration/roughening of selected region of interest marked in the previous step 302. In example implementations, the earmarked area can be roughened by embossing.
[0049] In an embodiment of the present disclosure, step 302 and step 304 can be performed simultaneously. At step 306, contact buttons are attached to the roughened area of the terminal by either welding or riveting or brazing or any other such process whereby the contact button and terminal are joined together by a firm, reliable and strong bond.
[0050] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0051] The present disclosure provides a method for fixing a contact button on a terminal that enhances the bonding strength between the two by 10 to 30%.
[0052] The present disclosure provides a method for fixing a contact button on a terminal that enhances the operational/ electrical life for terminal up to 100%.
[0053] The present disclosure provides a method for fixing a contact button on a terminal that enhances the reliability of bonding between the two.