Title of Invention

A METHOD FOR JOINING COMPONENTS OF LOW-VOLTAGE CIRCUIT BREAKERS AND COMPONENTS OF LOW-VOLTAGE CIRCUIT BREAKERS OBTAINED BY THE METHOD

Abstract A method for joining components of thermostatic systems and thermal relays for low-voltage circuit breakers, the components being constituted by at least one bimetallic element constituted by a lamina with a first face and a second face and at least one connection element that has a substantially flat end part with a third face and a fourth face, its particularity consisting of the fact that it comprises the steps that consist in: overlapping and coupling the end part of the first face of the bimetallic element with respect to the third face of the end part of the connection element; subjecting the end part of the second face of the bimetallic element to the welding action of laser means to provide a weld between the bimetallic element and the connection element.
Full Text

COMPONENTS OF THERMOSTATIC UNITS AND LASER WELDING
METHOD FOR PRODUCING THE COMPONENTS j
DESCRIPTION ■ Tlie present invention relates to components for thermostatic units (of the Iqnd
5 used in thermostatic systems with a bimetallic element for environments! or leclinical systems or m thermal protection relays for low-voltage circbit breakers), particularly to bimetallic elements and their connections to otlier components of said thermostatic units, and to a method for producing them. In particular, the present invention relates to a method for joining the bimetallic
10 elements to other components of the thermostatic units by means of a laiser welding process.
In low-voltage circuit breakers in the current art, the bimetallic element cjan generally be joined to the other components of thermostatic units, for exam|)le braids or terminal connection elements of a thermostat or the moving contacts
15 of a circuit breaker, by mechanical coupling or by braze welding.
The mechanical joining of said bimetallic elements is performed traditionajlly by using rivets, nails, pressure-based systems or similar joining systeijis. Although this method provides an efficient joining system, it has drawbacks.jln
particular, electrical conductivity proximate to the contact points is not ideal
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20 and can vary among parts. Furthermore, the mechanical joining operation still requires a larger number of parts (for example rivets or nails) than strictly required for the functionality of the thermostatic unit, thus introducilng complications in the assembly process and entailing in any case an increase in production costs.
25 As an alternative to mechanical coupling, the bimetallic element and the other components of the thermostatic imits can be joined by virtue of conventioial braze welding processes. These methods do not entail the drawbacks noted above, but entail other different ones, linked to the considerable application of
CONFIRMATION COPY

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PCT/EP02/14.(04

IS a
heat required by this technoloj^y. As is known, the application of heat critical element in the welding of bimetallic elements, since it can entail structural variations of said bimetallic element. Accordingly, its performancj^e is reduced, and therefore the number of substandard parts increases and in | any
5 case the behavior is uneven among parts.
It is evident, from what has been described above, that the current art needs to have components of thermostatic units that have a uniform behavior and cati be manufactured efficiently. It is also evident that the current art needs to havb an efficient method for joining components of thermostatic systems and theijmal
10 relays for low-voltage circuit breakers and particularly for joining bimetallic elements to the other components of the corresponding thermostatic units. | The aim of the present invention is to provide components of thermostatic Units that can be manufactured efficiently and have a uniform behavior. Within the scope of this aim, an object of the present invention is to provijie a
15 method for joining conq)onents of thermostatic units, and particularly bimetallic elements to the other components of thermostatic systems jand thermal relays for low-voltage circuit breakers that does not entail metallic
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joining systems.
Another object of the present invention is to provide a method for joii|iing 20 components of thermostatic units and particularly bimetallic elements to the
other components of thermostatic systems and thermal relays for low-voliage
circuit breakers that does not entail scarcely controllable heat applic^ion
systems.
Another object of the present invention is to provide a method for joining 25 components of thermostatic units and particularly bimetallic elements to the
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other components of thermostatic systems and thermal relays for low-voltage circuit breakers that does not determine structural variations in said bimetallic element.

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Another object of the present invention is to provide a method for joiriing components of thermostatic systems and thermal relays for low-voltage circuit breakers and particularly bimetallic elements to the other componentsi of thermostatic systems and thermal relays for low-voltage circuit breakers that 5 ensures mass reproducibility.
Another object of the present invention is to provide a method for joinEng components of thermostatic systems and thermal relays for low-voltage circuit breakers and particularly bimetallic elements to the other components | of themiostatic systems and thermal relays for low-voltage circuit breakers that
10 has a modest cost and is economically competitive.
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This aim, these objects and others that will become better apparent hereinafter
are achieved by means of a method for joining components of thermostatic
units, said components being constituted by at least one bimetallic element
constituted by a lamina with a first face and a second face and at least one
15 connection element that has a substantially flat end part with a third face anjd a
fourth face, characterized in that it comprises the steps that consist in: — overlapping and coupling the end part of the first face of said bimetallic element with respect to the third face of the end part of said cormectfon element;
20 ~ subjecting the end part of the second face of said bimetallic element to the
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welding action of laser means to provide a weld between said bimetallic
element and said connection element. It has been found in fact that by using a laser welding system and by working on one face of the bimetallic element according to the method of the present 25 invention, a joint is provided between the bimetallic element and the connection element that does not have the drawbacks of the known art, since the mechanical coupling means are avoided and there is no application of heat that is critical for the bimetallic element.

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Further characteristics and advantages of the method according to the present invention will become better apparent hereinafter with reference to the description given hereafter and to the accompanying drawing, given merelV by way of non-limitative example cind wherein the only figure is a schematic ^Hew
5 of a system for welding components of themiostatic units provided accor^iing to the invention.
In the accompanying figure, the bimetallic element is designated by | the reference numeral 1. Said element is constituted by a lamina with a first fac^ 10 and a second face 20. A connection element, for example the connection pf a
10 thermostatic system or relay, is designated by the reference numeral 2. the connection element 2 has a flat end part with a third face 30 and a fourth face 40. The end part of the first face 10 of the bimetallic element is superimpcjsed and coupled to the third face 30 of the end part of the connection element. Ilhe end part of the second face 20 of the bimetallic element is subjected to!the
15 welding action of laser means 50, so as to provide a weld between jthe bimetallic element and said connection element.
Preferably, in the method according to the invention the laser weld is not a ^pot weld but a continuous weld. For tliis purpose, the laser means 50 scan the second face 20 of the bimetaUic element according to a predefined path. |t is
20 evident to the person skilled in tlie art that said scan can be performed by virtue of a relative movement of the laser means with respect to the components tcj be welded during the welding operation, hi practice, said relative movement can be performed by keeping the components to be welded motionless and moving the laser means, or by keeping the laser means motionless and moving the
25 components to be welded, or by moving both.
Preferably, said scan according to a preset path follows a curved profile, as shown in the figure. As an altemative, however, it is possible to perform said scan along mixed and even discontinuous broken lines (curved and straight

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portions). Said lines can also be rephcated in multiple regions of the face to be
welded for example in a substantially parallel manner.
The speed, power, angle of incidence, frequency.-, amplitude and other physical
characteristics of the scanning beam can be chosen and modulated according to 5 the characteristics of the elements to be welded, such as for example ttieir
chemical nature or their thickness.
Although it is possible to use laser means of a different type, it is highly
preferable to use a solid-state laser, for example a Nd-crystal laser. In this cjase
also, the characteristics of use of the laser, such as for example the firequeiiicy, 10 power and angle of incidence, can be chosen and modulated as a function of
the characteristics of the elements to be welded and of the results to! be
obtained.
It has been found in practice that by using the method according to ithe
invention it is possible to weld the bimetallic element to various components of 15 thermostatic systems and thermal relays for low-voltage circuit breakersj In
particular, it has been found that it is possible to weld the bimetallic elemenlt to
rigid connections and also to connecting braids.
In this last case, the end part of the connecting braids must be machined ^nd
shaped appropriately so as to allow coupling to one face of the bimet^lic
20 element and its welding thereto. ■ i
The method according to the invention solves the problems of the known art
and has many advantages over it.
In particular, it is not necessary to use mechanical connecting elements, tiius
reducing the number of parts to those strictiy necessary for the functionality of 25 the circuit breaker. The assembly operations, moreover, are simplifijcd,
consequently saving on production times and costs.
Moreover, the use of laser means allows to avoid applications of heat that
would be critical and damaging for the bimetallic element. In general, the

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efficiency and reproducibihty from part to part of the method according to the invention are greater than those of the methods of the known art, thus reducing the number of rejects and substandard parts and increasing the overall econ(|)my of the production process.
5 With the method according to the invention it is therefore possible to obbin components of thermostatic systems and thermal relays for low-voltage circuit breakers that have improved characteristics with respect to the componentfe of the known art. These components, like the devices (for example circuit breakers) that comprise them, constitute an additional aspect of the pre$ent
10 invention.
In practice it has been found that the method according to the invention andj the
components of low-voltage circuit breakers obtained therewith fiilly achieve
the intended aim and objects. The method thus conceived is susceptible of
numerous modifications and variations. 15 All the details may furthermore be replaced with other technically equivalent
elements. I


A method for joining components of thermostatic systems and thermal
relays for low-voltage circuit breakers, said components being constituted
by at least one bimetallic element constituted by a lamina with a first iace
and a second face and ai: least one connection element that has a
substantially flat end part with a third face and a fourth face, characterized
in that it comprises the steps that consist in:
— overlapping and coupling the end part of the first face of said bimetallic element with respect to the third face of the end part of said connection element;
— subjecting the end part of the second face of said bimetallic elemeni: to the welding action of laser means to provide a weld between said bimeta(llic element and said connection element.
The method for joining components of thermostatic systems and thertnal relays for low-voltage circuit breakers according to claim 1, characteriized
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in that said laser means scan the second face of said bimetallic elenient
along a predefined path.
The method for joining comiponents of thermostatic systems and thermal
relays for low-voltage circuit breakers according to claim 2, characterijzed
in that said predefined path follows a curved profile.
The method for joining components of low-voltage circuit breal^ers
according to claim 2, characterized in that said predefined path follows pne
or more mixed, open or closed lines, also in the variation of parallel
repetitions.
The method for joining components of low-voltage circuit breakers
according to one or more of the preceding claims, characterized in that said
laser means are constituted by a solid-state laser.
The method for joining components of low-voltage circuit breakers
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according to one or more of the preceding claims, characterized in t|iat at least one connection element is constituted by the circuit breaker protection relay connection.
The method for joining components of low-voltage circuit breakers
according to one or more of claims 1 to 6, characterized in that at least one
connection element is constituted by a connecting braid.
Components of low-voltage circuit breakers obtained with a method
according to one or more of the preceding claims. I I
The low-voltage circuit breaker, comprising one or more compoi|ents according to claim 8.
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10. A method for joining components of thermostatic systems substantially as hereinldescribed
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with reference to the accompanying drawings. i


Documents:

1639-CHENP-2004 AMENDED CLAIMS 28-02-2011.pdf

1639-CHENP-2004 AMENDED PAGES OF SPECIFICATION 28-02-2011.pdf

1639-CHENP-2004 CORRESPONDENCE OTHERS 21-06-2010.pdf

1639-CHENP-2004 EXAMINATION REPORT REPLY RECIEVED 28-02-2011.pdf

1639-chenp-2004 form-1 28-02-2011.pdf

1639-chenp-2004 form-3 28-02-2011.pdf

1639-CHENP-2004 OTHER PATENT DOCUMENT 28-02-2011.pdf

1639-chenp-2004 power of attorney 28-02-2011.pdf

1639-chenp-2004 abstract.pdf

1639-chenp-2004 claims.pdf

1639-chenp-2004 correspondence others.pdf

1639-chenp-2004 correspondence po.pdf

1639-chenp-2004 description (complete).pdf

1639-chenp-2004 drawings.pdf

1639-chenp-2004 form-1.pdf

1639-chenp-2004 form-18.pdf

1639-chenp-2004 form-3.pdf

1639-chenp-2004 form-5.pdf

1639-chenp-2004 form-6.pdf

1639-chenp-2004 pct.pdf

1639-chenp-2004 power of attorney.pdf


Patent Number 246830
Indian Patent Application Number 1639/CHENP/2004
PG Journal Number 11/2011
Publication Date 18-Mar-2011
Grant Date 16-Mar-2011
Date of Filing 26-Jul-2004
Name of Patentee ABB S.p. A.
Applicant Address VIA VITTOR, PISANI 16, I-20124 MILANO
Inventors:
# Inventor's Name Inventor's Address
1 MAURA, MASSIMO VIA COLLE SAN SEBASTIANO, 55, I-03023 CECCANO (FR)
2 GAMBA, FEDERICO VIA PESCARIA, 7/B, I-24123 BERGAMO
PCT International Classification Number B23K26/24
PCT International Application Number PCT/EP02/14404
PCT International Filing date 2002-12-17
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 MI2001A002836 2001-12-28 Italy