WO2012000733A1

WO2012000733A1 - Welded product, welding method, and circuit breaker

Info

Publication number: WO2012000733A1
Application number: PCT/EP2011/058929
Authority: WO
Inventors: Zhang Yao Bao; Ren Jun Cao; Hua Shen; Fu Jian Su; Gang Zhou
Original assignee: Siemens Aktiengesellschaft
Priority date: 2010-06-28
Filing date: 2011-05-31
Publication date: 2012-01-05
Also published as: CN102299027A; CN102299027B

Abstract

The present invention provides a welded product which comprises a first element and a second element, and further comprises a third element, wherein the melting point of said third element is between that of the material of said first element and the material of said second element, one end of said first element is fixed into an accommodation space formed by said third element and said third element is welded onto said second element. It is made easy to weld together two parts to be welded by way of the medium effects of the third element, so that the welded product can meet the application requirements regarding mechanical strength and electric strength.

Description

Welded product, welding method, and circuit breaker Technical field

The present invention relates to a welded product, a welding method, and a circuit breaker and, particularly, to a welded product and a welding method using an accessory component for welding and a circuit breaker comprising the welded product.

Background art

Nowadays, with the continuous development of low-voltage electric appliances, the use of thermal elements (for example thermal bimetal sheets or bimetal elements) plays a very important role in the development of the entire field.

Thermal bimetal sheet is a relatively simple automatic control element used for realizing temperature control, which is composed of two layers of metals (or alloys) with

different thermal expansion coefficients. The layer with larger thermal expansion coefficient is the active layer and the layer with smaller thermal expansion coefficient is the passive layer. When the thermal bimetal sheet is heated, the length of free expansion of the active layer is greater than that of the passive layer, however, since the two layers are firmly bonded together, the thermal bimetal sheet is bent into an arc shape, it is to the contrary when cooled, and this deformation can be utilized to turn on or switch on a circuit, and drive a mechanical enlarging mechanism to realize the functions needed by a product, so as to make a circuit breaker.

The materials of the active layer and passive layer in the thermal bimetal sheet have certain constituents, for example, the components of the active layer are Mn 75%, Ni 15% and Cu 10%, or Ni 20%, Mn 6%, and the balance of iron, with the thermal expansion coefficients thereof being 27><10^~ ⁶/°C and 20xl0^"6/°C between 20°C and 100°C, respectively; while the components of the passive layer are Ni 36% and the balance of iron or Ni 42% and the balance of iron, with expansion coefficient thereof being ( 1.8-4.8 ) ^χ 10^~6/ °C . The methods for bonding thermal bimetal sheets comprise cold- rolling bonding, melting bonding, hot-rolling bonding, etc.

There is no doubt that welding is the most widely used among the way for thermal element applications, therefore, the welding processes for thermal elements are also being improved gradually. However, there is still a rather

difficult problem to be solved, namely, the problem of the welding quality between a soft copper wire and a thermal element . In Chinese patent application no. 200810029403.3,

entitled "an electric resistance welding method", in order to weld copper or a copper alloy with iron-steel or an iron- steel alloy together, this patent application discloses an electric resistance welding method for welding copper or a copper alloy with iron-steel or an iron-steel alloy together, in which spot welding or loop projection welding is carried out to weld copper or a copper alloy with iron-steel or an iron-steel alloy together by using the general principles of electric resistance welding by means of a specially made electric resistance welding electrode tip and a special welding power source, using a process of segmental

application of impulse current and segmental application of pressure. In this case, the welding DC current is provided by a welding power source, the discharge time is in the range from 110 ms to 280 ms, the maximum current is in the range from 36 KA to 280 KA, the current frequency before

rectification is 1000 Hz, 1200 Hz or 1500 Hz, the welding current between a workpiece and the electrode tip is DC, and the pressure is in the range from 1 Kgf/cm² to 5.9 Kgf/cm².

However, in practical products as shown in Fig. 1, among the various current processes for welding soft copper wire and thermal elements, the widely adopted way is to have the soft copper wire 1 directly welded onto one end 3a of the thermal element 3.

Contents of the invention

The object of the present invention is to provide a welded product and a welding method, which is capable of reducing the requirements for adjusting welding parameters, etc., and ensuring the reliability and stability of quality of the welded products.

In order to achieve the abovementioned objects, the present invention proposes a welded product which comprises a first element and a second element, and further comprises a third element, the melting point of said third element is between that of the material of said first element and the material of said second element, one end of said first element is fixed into an accommodation space formed by said third element, and said third element is welded onto said second element.

Preferably, the absolute value of the difference between the melting point of said first element and the melting point of the material of said third element is greater than the absolute value of the difference between the melting point of said second element and the melting point of the material of said third element, and since the melting points of the second element and the third element are relatively close to each other, the second element can be more conveniently welded together with the third element.

Preferably, said first element is a wire, said second element is a thermal element, and said third element is a piece of iron sheet. Preferably, the material of said second element is a ferroalloy .

Preferably, the material of said first element is copper. Preferably, the material of said third element is iron, with the melting point thereof being closer to that of the second element.

Said third element is most preferably made of a copper- preplated iron sheet, so that not only the corrosion

resistance of the third element can be improved, but also the electric performance of the assembly can be improved.

Preferably, the end of said first element is mechanically fixed into an accommodation space formed by said third element, so as to realize the relatively tight bonding between the first element and the third element. Moreover, as a preferred embodiment, said mechanical fixing is by way of press connection, and the bonding between the first element and the second element will be tighter under the effects of a strong external pressure, which will not cause damage to the end of the first element which has been processed into a flat shape; furthermore, since such mechanical fixing avoids further welding of the first element, it therefore not only ensures the electric performance and mechanical performance of the first element, but also ensures the reliability and stability of the quality of the welded assembly.

Preferably, the end of said first element is

substantially in a flat shape, which makes it easy to fix the third element into the first element, and at the same time it becomes easier to process the third element into a shape with a relatively large contact area and easier to weld it

together with the second element.

Preferably, said third element is formed by bending a sheet-like material with two ends thereof having toothed edges, and it is relatively difficult for the first element to fall off from the junction part after the first element has been placed therein, thus it can work better to ensure the electric performance of the welded assembly. The present invention further provides a circuit breaker in which the abovementioned welded product is included. The present invention further provides a welding method, in which one end of a first element is fixed into an

accommodation space formed by a third element, and said third element is welded onto a second element, wherein the melting point of said third element is between that of the material of said first element and the material of said second

element .

Preferably, the end of said first element is mechanically fixed into the accommodation space formed by said third element.

Preferably, said mechanical fixing is by press

connection . Preferably, said third element is made by bending a sheet-like material with two ends thereof having toothed edges .

By using the welded product, the circuit breaker, and the welding method provided by the present invention, what the third element (such as an enclosing element) uses is a material with a melting point close to the melting point of the material of the second element and between that of the first element (such as a wire) and the material of the second element (such as a thermal element) , and since the thermal element is usually a ferroalloy, such a material (such as iron sheet) with the melting point thereof between that of the two kinds of materials is readily available, and since the sheet process meeting the requirements is already

relatively mature and price thereof is inexpensive,

consequently, the costs will not be increased greatly.

Compared with the price of the assemblies which failed due to unstable welding, the embodiments of the present invention can still realize the requirements for reducing the production costs of the products.

Moreover, when the first element is fixed into the accommodation space formed by the third element, mechanical press connection can be adopted to enclose the end of the first element, which will not cause damage to the end of the first element which has been processed into a flat shape (such as elongate body) , and since such mechanical fixing avoids welding of the ends of the first element again in the next welding procedure, therefore it not only ensures the electric performance and mechanical performance of the first element, but also ensures the reliability and stability of the quality of the welded assembly.

Also, the material performance of the third element is close to that of the material of second element, therefore the requirements for adjusting the welding parameters, etc. can be reduced, and furthermore it is more favorable to select surface plating material with good electrical

conductivity to process the third element, for example, a copper-preplated iron sheet can be used, so that not only the corrosion resistance of the third element can be improved, but also the electric performance of the welded products can be improved.

Brief description of the accompanying drawings

The following accompanying drawings are only intended to illustratively describe and explain the present invention and are not intended to limit the scope of the present invention.

In the drawings,

Fig. 1 is an illustrative diagram of a welded product in the prior art;

Fig. 2 is an illustrative diagram of an embodiment of a welded product of the present invention;

Fig. 3a is a local schematic diagram of a wire used as a first element in an embodiment of the welded product of the present invention; Fig. 3b is an illustrative diagram of an enclosing element used as a third element in an embodiment of the welded product of the present invention before processing;

Fig. 3c is an illustrative diagram of an enclosing element used as a third element in an embodiment of the welded product of the present invention;

Fig. 3d is a schematic diagram of the cooperation between a wire used as a first element and an enclosing element used as a third element in an embodiment of the welded product of the present invention; and

Fig. 4 is an illustrative diagram of an embodiment of welding a welded product in the present invention.

Exemplary embodiments

For the sake of better understanding of the technical features, objects, and effects of the present invention, the particular embodiments of the present invention will now be described with reference to the accompanying drawings. In the present specification, the words "upper", "lower",

"front", "back", "left", "right", etc. are merely used for representing the positional relationships between related parts, and are not intended to limit their absolute

positions .

In the present specification, "illustrative" means

"acting as an example, an instance or illustration", and diagram and embodiment which are described as "illustrative" shall not be interpreted as a more preferred or more

advantageous technical solution.

As shown in Fig. 2, the present invention provides a welded product 10 which comprises a first element (wire 1) and a second element (thermal element 3) and further

comprises a third element (enclosing element 2), with the melting point of the third element being between that of the material of the first element and the material of the second element, one end of the first element being fixed into the accommodation space formed by the third element, and the third element being welded onto the second element.

Such a first element can be the wire 1, such as a soft copper wire commonly used in electric appliances, while the second element can be the thermal element 3, such as a material (such as ferroalloy) the melting point of which is higher than that of the wire 1, and the third element can be the enclosing element 2 which encloses the first element.

However, the melting point of the wire 1 (its material can be copper) is relatively low and the melting point of the thermal element 3 (its material can be ferroalloy) is

relatively high, and although the way for the wire 1 and the thermal element 3 to be directly welded together is simple, since the difference between the melting points of the two materials is relatively large it is difficult to control the parameters at the time of welding the two together, for example, it is rather difficult to control the parameters such as welding current, initial pressure, pre-pressing time, the selection of welding electrodes, etc. In particular, when the oxidation phenomenon such as an oxidation layer exists on the surface of the thermal element 3, it further affects the welding quality, and it is more difficult to reach the requirements regarding electric performance and mechanical performance at the time of welding, thus causing failed parts and assemblies.

While, in the embodiments of the present invention, an enclosing element 2 is additionally used, and the absolute value of the difference between the melting point of the enclosing element 2 and the melting point of the material of the third element 3 is smaller than the absolute value of the difference between the melting point of the enclosing element 2 and the melting point of the material of the wire 1, in other words, what the enclosing element 2 uses is a material with a melting point close to the melting point of the material of the thermal element 3 and between that of the materials of the wire 1 and the thermal element 3, and since the thermal element 3 is usually a ferroalloy, it is easy to find a material (such as iron sheet) with a melting point between that of the two kinds of materials, and the

processing technique of the sheet meeting the requirements is already relatively mature and price thereof is inexpensive, therefore the price of the wire parts will not be increased significantly after this process has been added, and compared with the price of the assemblies which failed due to unstable welding, the new process can still realize the requirements in reducing the production costs of the products.

In another embodiment, since the material performance of the enclosing element 2 is close to that of the material thermal element 3, all the requirements for adjusting the welding parameters etc. can be reduced, and also it is more favorable to select surface plating material with good electrical conductivity to process the enclosing element 2, for example, a copper-preplated iron sheet can be used as the material of the enclosing element 2, so that not only the corrosion resistance of the enclosing element can be

improved, but also the electric performance of the assembly can be improved. As shown in Fig. 3a, the end la of the wire 1 generally can be processed into a flat shape, so as to realize a better fixing with the enclosing element 2. The end la of the wire is mechanically fixed into the accommodation space formed by the enclosing element 2 such as by way of press connection and rivet-pressing, so that the enclosing element 2 can have a better contact therewith. Since the end la of the wire is enclosed by way of mechanical press connection, rivet- pressing, etc, which will not cause damage to the end which has been processed into a flat shape, and furthermore, since such mechanical fixing avoids secondary welding of the end la of the wire in the next welding procedure, it not only ensures the electric performance and mechanical performance of the wire 1, but also ensures the reliability and stability of the quality of this welded assembly.

As to the enclosing element 2, it can be formed by bending a sheet-like material, this sheet-like material preferably being roughly formed into a quadrilateral shape with two ends thereof having toothed edges (as shown in Fig. 3b), and the enclosing element 2, which is made by bending twice along folding lines substantially parallel to the toothed edges, correspondingly has a toothed junction part

(as shown in Fig. 3c) . As shown in Fig. 3d, it would be more difficult for the wire 1 to fall off from the junction part after the wire 1 has been placed therein, so that it can better ensure the electric performance of the welded

assembly.

It can be seen that by using the embodiments provided by the present invention the requirements regarding the

consistency of parts at the time of welding can be

effectively reduced, and even if an oxidation layer exists on the surface of the thermal element, an effective melt nugget can still be formed between the two parts so as to meet the requirements regarding the electric performance and

mechanical performance.

In circuit breakers, it is usually necessary to weld a copper wire onto the winding filaments as a thermal element, and since the melting point of the winding filaments is higher than that of copper, the welded products in the embodiments of the present invention can be applied in the circuit breakers, so as to ensure a better welding quality.

The present invention further provides a welding method, in which one end la of a first element (the wire 1) is fixed into an accommodation space formed by a third element (the enclosing element 2), and the third element (the enclosing element 2) is welded onto a second element (the thermal element 3) , wherein the melting point of the third element (the enclosing element 2) is between that of the material of the first element (the wire 1) and the material of the second element (the thermal element 3) . As mentioned above, the end la of the wire is mechanically fixed into the accommodation space formed by the enclosing element 2, preferably the mechanical fixing of rivet-pressing being employed. However, as to the enclosing element 2, the enclosing element 2 can be made by bending a sheet-like material with two ends thereof having toothed edges.

As shown in Fig. 4, a new part (the enclosing element 2) can be mechanically attached to the end la of the wire (such as by way of press connection and rivet-pressing) , then the end la of the wire which has attached the enclosing element 2 is welded together with the thermal element 3. The attached enclosing element 2 employs a material (generally a

ferroalloy) with a melting point close to that of the

material of the thermal element 3 and between that of the wire 1 and the thermal element 3, and then it is processed into a sheet shape to enclose the end la of the wire 1, and during the subsequent welding, the two parts which are to be actually welded together are the thermal element 3 and the enclosing element 2 which encloses the wire 1 from outside, therefore the wire 1 and the enclosing element 2 are welded together and the enclosing element 2 and the thermal element 3 are also welded together under the effects of the current and pressure between the two welding electrodes (4a, 4b) , and finally the effective connection between the wire 1 and the thermal element 3 is achieved and the stability of the thermal element in the application of the products is

realized.

Of course, the wire used as the first element in the embodiments of the present invention is merely for

illustrative description, and those skilled in the art would appreciate that other elements such as plate-like materials and bar-like materials can also be used as the first element. What are described above are merely illustrative particular embodiments of the present invention and are not intended to limit the scope of the present invention. Any equivalent variation, modification, and combination made by anyone skilled in the art without departing from the concept and principles of the present invention shall belong to the protective scope of the present invention.

Claims

1. A welded product (10), comprising a first element (1) and a second element (3) , characterized in that it further comprises a third element (2), with one end of said first element (1) being fixed into an accommodation space formed by said third element (2) and said third element (2) being welded onto said second element (3) , wherein the melting point of said third element (2) is between that of the material of said first element (1) and the material of said second element (3) .

2. The welded product (10) as claimed in claim 1, characterized in that the absolute value of the difference between the melting point of said first element (1) and the melting point of the material of said third element (2) is greater than the absolute value of the difference between the melting point of said second element (3) and the melting point of the material of said third element (2) .

3. The welded product (10) as claimed in claim 1, characterized in that said first element (1) is a wire, said second element (3) is a thermal element, and said third element (2) is an iron sheet.

4. The welded product (10) as claimed in claim 1, characterized in that the material of said first element (1) is copper.

5. The welded product (10) as claimed in claim 1, characterized in that the end of said first element (1) located in the accommodation space formed by said third element is substantially in a flat shape.

6. The welded product (10) as claimed in claim 1, characterized in that the material of said second element (3) is a ferroalloy.

7. The welded product (10) as claimed in claim 1, characterized in that the material of said third element (2) is iron.

8. The welded product (10) as claimed in claim 1, characterized in that said third element (2) is made of a copper-preplated iron sheet.

9. The welded product (10) as claimed in claim 1, 7 or 8, characterized in that said third element (2) is formed by bending a sheet-like material with two ends thereof having toothed edges.

10. The welded product (10) as claimed in claim 1, characterized in that the end of said first element (1) is mechanically fixed into the accommodation space formed by said third element (2) .

11. The welded product (10) as claimed in claim 10, characterized in that the end of said first element (1) is fixed into the accommodation space formed by said third element (2) by way of press connection.

12. A circuit breaker, characterized in that it comprises the welded product (10) as claimed in any one of claims 1 to

11.

13. A welding method, characterized in that one end of a first element (1) is fixed into an accommodation space formed by a third element, and said third element (2) is welded onto a second element, wherein the melting point of said third element (2) is between that of the material of said first element (1) and the material of said second element (3) .

14. The welding method as claimed in claim 13,

characterized in that the end of said first element (1) is mechanically fixed into the accommodation space formed by said third element (2) .

15. The welding method as claimed m claim 14,

characterized in that said mechanical fixing is a

connection .

16. The welding method as claimed in claim 13,

characterized in that said third element (2) is made by bending a sheet-like material with two ends thereof having toothed edges.