GB1576268A - Welding leads for example of armatures - Google Patents

Description

(54) WELDING LEADS FOR EXAMPLE OF ARMATURES (71) We, INTERNATIONAL BUSINESS MACHINES CORPORATION, a Corporation organized and existing under the laws of the State of New York in the United States of America, of Armonk, New York 10504, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement-: This invention relates to a method and apparatus for arc welding together tips of each group of leads in an array of spaced groups, and is particularly applicable to the production of armatures.

Electric arc welding with inert gas shielding, such as the Tungsten Inert Gas Process (TIG), is well known in the prior art. It is often referred to as a continuous welding process since it is generally used for making continuous welds. Whenever the TIG process is used for making continuous welds, the noise which is generated by the TIG welder is usually considered to be within acceptable limits. One restriction in the use of this type of welding stems from the fact that the noise produced by an HF arc-initiating current, when the process is used for making non-continuous welds, runs almost continuously and may become objectionable. In order to deal with the noise, workers may need to wear hearing protection, or the welding apparatus may need to be contained within a soundproof enclosure.

In greater detail generally, a continuous welder such as a TIG welder incorporates energising means having two separate and distinct circuits, a high frequency start circuit, and an AC or DC circuit for providing an arc-maintaining welding voltage.

The function of the HF circuit is to initiate the welding arc. Once the arc is initiated, the welder automatically switches and runs on the DC or AC circuit.

The high frequency circuit produces noise, but it is operational during a continuous welding proces only momentarily, i.e. to initiate the welding arc at the start of the entire welding operation, and it is not usually considered objectionable. The DC or AC circuit produces a low level noise which is within tolerable levels.

However, if the welding were to be a non-continuous weld, the apparatus would always be operating in the start mode which is noise producing. Stated another way, in making intermittent or noncontinuous welds, the high frequency circuit would initiate the arc, but the arc would again be extinguished before energisation of the arc was transferred to the DC or AC circuit.

A theoretical consideration, apart from noise, is that the welds would tend to be less homogeneous and less strong if they resulted from operation of the high frequency circuit only.

According to one aspect of the invention, there is provided a method of arc welding together tips of each group of leads in an array of spaced groups, comprising clamping the array in position for welding by a clamping means having at least one electrically conductive portion adjacent and in electrical contact with the grouped tips, causing relative movement between a welding electrode and the groups so that the groups move relatively past the welding electrode in succession, the welding electrode having energising means which automatically switches between applying a high frequency arc-starting voltage and an AC or DC arc-maintaining welding voltage, the arrangement being such that when the arc has been initiated, it is maintained by the arc-maintaining voltage while the welding electrode is opposite the spaces between adjacent groups by an arc circuit completed through the conductive portion of the clamping means, when the arc goes to the conductive portion.

The invention also concerns welding apparatus and, in particular, armatures made by the method or apparatus.

The invention will be further explained by way of example with reference to the accompanying drawings, in which: Figure 1 is an elevational view of an armature; Figure 2 is an elevational and diagrammatic view of welding apparatus in accordance with the invention; Figure 3 is an enlarged diagrammatic cross section of part of Figure 2; Figure 4A is an elevational view, to an enlarged scale and unclamped and removed from the mandrel, of a clamping assembly of the apparatus of Figure 2; and Figure 4B is an exploded perspective view of the clamping assembly and mandrel.

A tubular electric motor armature 10 (Figure 1) has end portions 12 and 14, at which welding processes in accordance with the present invention are to be carried out.

Each end portion comprises a plurality of double tabs, the armature being formed from two overlying printed circuits (see armature 10 in Figure 3). For example, end portion 12 comprises double tabs 1,2,3,4...N. Similarly, end portion 14 com prises double tabs a a,b,c,..n. Each double tab is separated by a space 16 or 18. One example of such an armature 10 is given in the specification of our Letters Patent No.

1,307,803.

In order to weld, for example double tab a, an arc is directed from a welding electrode 24 (Figure 2) to the selected double tab a. This takes place while the armature is being rotated, and when the double tab a leaves the welding electrode 24, which then becomes opposite one of the spaces 16 or 18, the arc would be extinguished unless the apparatus has the features of the present invention. As soon as double tab b is positioned opposite the electrode 24, the arc would again be initiated. Such repetitive extinguishing and initiation of the welding arc would make this process noisy.

Armature 10 is fabricated from two printed circuit cards, each made by laminating a copper sheet to a suitable backing member, for example, a fibreglass backing.

A pattern of conductors is formed by chemically etching the copper from the backing. The backing is removed from the end portions 12 and 14 (Figure 1) of these conductors to provide the tabs to be welded. The cards are then placed, one round the other, such that the fibreglass from the inner card forms the inside diameter of the tubular armature and the fibreglass of the outer card insulates it from the inner card. The conductors are related so that when the ends are welded a coiled armature is formed. The cards are glued together in correct alignment on a mandrel (described hereinafter under reference 44) and the double tabs are then welded. The cards may be formed into the armature as described in the Specification of our Letters Patent No. 1,315,273. However, the invention is not only applicable to tubular armatures, but can be applied to a disc-shaped printed circuit armature such as is described in United States Patent Specification No. 3,312,846.

The welding apparatus according to the invention, which is used for welding the tabs of the armature 10, includes a welding means 22 (Figure 2) in the form of a conventional TIG welder. It includes a high frequency circuit which is used for initiating a welding arc, and an AC or DC circuit which sustains the arc for welding after the arc has been initiated. It also includes switching circuitry which automatically switches operation from the high frequency circuit to the DC or AC circuit once the welding arc is initiated. Welding electrode 24 is mounted from base 20 of the welding means by a series of supporting members which can move in the directions shown by arrows 26, 28 and 30 respectively. This enables the electrode to be appropriately positioned during setting up of the apparatus relative to the double tabs to be welded. The welding electrode has a supply of a monatomic shrouding gas G.

The apparatus frame 32 supports pedestals 34 and 36. A shaft 38 is mounted in pedestal 36 via a spring loaded connector 40, which allows some axial movement of the shaft (see arrow 42). As will be discussed later, the axial adjustability of shaft 38 allows mandrel 44, upon which the armature is positioned for welding, to be removed and inserted in the apparatus.

Connecting means 46 is attached to the free end of shaft 38. This connecting means functions to receive one end of mandrel 44. The other end of mandrel 44 is received in connecting means 48 which is carried by pedestal 34.

In order to rotate the armature so as to move the individual double tabs past the welding electrode 24, mandrel 44 is rotated in either direction (see double headed arrow 110) by a variable speed motor 50 which is connected to a speed reducer 52, which in turn is connected to the connecting means 48. Any conventional variable speed motor with suitable motor speed controller 53 can be used for driving mandrel 44. In the preferred embodiment of this invention, a variable speed motor, having an average speed of 1200 revolutions per minute, was used. The speed reducer 52 has a 110 to 1 gear reducing ratio.

This means that the mandrel, with its associated armature workpiece, is driven at an approximate speed of 11 revolutions per minute. As such, each end of the armature requires an approximate time of five seconds for welding.

Referring to Figures 2 and 3, the double tabs (e.g. a) of the armature 10 are clamped between a clamping assembly (shown only diagrammatically in Figure 3) and mandrel 44. Both the mandrel 44 and the clamping assembly 54 are electrically conductive and form a clamping means of the apparatus. The clamping assembly 54 is grounded by an electrical connection 60 between the welding means 22 and a spring loaded brush 56 which rides on a slip ring 58. Another spring loaded brush 62 rides upon mandrel 44 and operates to define a second conductive path between the mandrel and ground.

Figure 3 also illustrates the welding operation. Tab a is positioned opposite electrode 24 and an arc 64.passes between electrode 24 and Tab a. The arc rapidly weldes tab a while the tab a passes the electrode 24. However, next, a blank space, for example 18 (Figure 1), comes into position opposite the welding electrode. As is well known in basic electrical theory, electrons tend to flow along a path of least resistance. This being the case, the arc now passes along the paths 65 and 66, which are sufficiently short in length to allow the arc to continue and not be extinguished.

As soon as the space is rotated past the electrode 24, and a new tab comes opposite the electrode 24, the arc again will be between the new tab and the electrode along path 64. This process continues for one revolution of the armature until all the tabs on the right-hand end of the armature 10 are welded. Of course, the apparatus can be operated with just the clamping assembly 54 or the mandrel 44 grounded.

However, it is preferred to ground both, since this appears to give better quality welded joints. Once the arc is initiated at the start of the welding operation, it is maintained continuously either via path 64, or paths 65, 66 and, therefore, the apparatus remains operated by the arcmaintaining DC or AC circuit without generating undesirable high frequency noise due to continuous operation of the high frequency starting circuit.

Figure 4A shows the external surfaces of the clamping assembly when the clamping assembly is removed from the mandrel.

Figure 4B shows the mandrel 44 and the internal surfaces of the clamping assembly, when removed from the mandrel. Mandrel 44 includes a central portion 68 and two end portions 70 and 72 respectively. End portions 70 and 72 are machined so that they can be fitted into connecting means 46 and 48 (Figure 2). The central portion, 68, of mandrel 44 has a substantially cylindrical shape, and Figure 3 shows the armature 10 fitting snugly on the mandrel.

In order to achieve the electrical conducting function, copper conducting rings 74 and 75 are positioned one on each end of central portion 68. The armature is grounded by way of the mandrel by positioning the armature on the mandrel 44 so that the double tabs to be welded are in contact with one of the conducting rings (Figure 3) and then grounding the mandrel by spring loaded brush 62 (Figure 2). In order to form an electrical isolation between the conducting mandrel and the frame 32, inter alia pedestals 34 and 36 (Figure 2) are manufactured from electrically insulating material.

Clamping assembly 54 includes three separate, but identical sections identified as portions 76, 78 and 80 respectively which together form a cylindrical body. Each portion includes two electrically conductive end ring sections 82 and 84, which are interconnected via an inner conductor 86.

Each conductor 86 is connected to a respective sector of conducting ring 58 via screws 88, 90 and 92 respectively. The portions 76, 78 and 80 have interconnecting hinges 94, 96. When the clamping assembly is positioned round the armature on the mandrel, it is closed by latching means 98, 100, 102 and 104 attached to end portions 80 and 76 respectively.

Latching means 98 and 104 are mated, as are latching means 100 and 102. Brush assembly 56 always rides on that sector of conducting ring 58 which is on that one of the portions 76, 78 and 80 adjacent the welding electrode 24.

It will be noted that in Figure 3, both the copper ring 75 and the clamping assembly 54 are in good thermal contact with the tabs a, so that they act as heat sinks for heat generated at the tabs during welding.

WHAT WE CLAIM IS: 1. A method of arc welding together tips of each group of leads in an array of spaced groups, comprising clamping the array in position for welding by a clamping means having at least one electrically conductive portion adjacent and in electrical contact with the grouped tips, causing relative movement between a welding electrode and the groups so that the groups move relatively past the welding electrode in succession, the welding electrode having energising means which automatically

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (12)

**WARNING** start of CLMS field may overlap end of DESC **. this invention, a variable speed motor, having an average speed of 1200 revolutions per minute, was used. The speed reducer 52 has a 110 to 1 gear reducing ratio. This means that the mandrel, with its associated armature workpiece, is driven at an approximate speed of 11 revolutions per minute. As such, each end of the armature requires an approximate time of five seconds for welding. Referring to Figures 2 and 3, the double tabs (e.g. a) of the armature 10 are clamped between a clamping assembly (shown only diagrammatically in Figure 3) and mandrel 44. Both the mandrel 44 and the clamping assembly 54 are electrically conductive and form a clamping means of the apparatus. The clamping assembly 54 is grounded by an electrical connection 60 between the welding means 22 and a spring loaded brush 56 which rides on a slip ring 58. Another spring loaded brush 62 rides upon mandrel 44 and operates to define a second conductive path between the mandrel and ground. Figure 3 also illustrates the welding operation. Tab a is positioned opposite electrode 24 and an arc 64.passes between electrode 24 and Tab a. The arc rapidly weldes tab a while the tab a passes the electrode 24. However, next, a blank space, for example 18 (Figure 1), comes into position opposite the welding electrode. As is well known in basic electrical theory, electrons tend to flow along a path of least resistance. This being the case, the arc now passes along the paths 65 and 66, which are sufficiently short in length to allow the arc to continue and not be extinguished. As soon as the space is rotated past the electrode 24, and a new tab comes opposite the electrode 24, the arc again will be between the new tab and the electrode along path 64. This process continues for one revolution of the armature until all the tabs on the right-hand end of the armature 10 are welded. Of course, the apparatus can be operated with just the clamping assembly 54 or the mandrel 44 grounded. However, it is preferred to ground both, since this appears to give better quality welded joints. Once the arc is initiated at the start of the welding operation, it is maintained continuously either via path 64, or paths 65, 66 and, therefore, the apparatus remains operated by the arcmaintaining DC or AC circuit without generating undesirable high frequency noise due to continuous operation of the high frequency starting circuit. Figure 4A shows the external surfaces of the clamping assembly when the clamping assembly is removed from the mandrel. Figure 4B shows the mandrel 44 and the internal surfaces of the clamping assembly, when removed from the mandrel. Mandrel 44 includes a central portion 68 and two end portions 70 and 72 respectively. End portions 70 and 72 are machined so that they can be fitted into connecting means 46 and 48 (Figure 2). The central portion, 68, of mandrel 44 has a substantially cylindrical shape, and Figure 3 shows the armature 10 fitting snugly on the mandrel. In order to achieve the electrical conducting function, copper conducting rings 74 and 75 are positioned one on each end of central portion 68. The armature is grounded by way of the mandrel by positioning the armature on the mandrel 44 so that the double tabs to be welded are in contact with one of the conducting rings (Figure 3) and then grounding the mandrel by spring loaded brush 62 (Figure 2). In order to form an electrical isolation between the conducting mandrel and the frame 32, inter alia pedestals 34 and 36 (Figure 2) are manufactured from electrically insulating material. Clamping assembly 54 includes three separate, but identical sections identified as portions 76, 78 and 80 respectively which together form a cylindrical body. Each portion includes two electrically conductive end ring sections 82 and 84, which are interconnected via an inner conductor 86. Each conductor 86 is connected to a respective sector of conducting ring 58 via screws 88, 90 and 92 respectively. The portions 76, 78 and 80 have interconnecting hinges 94, 96. When the clamping assembly is positioned round the armature on the mandrel, it is closed by latching means 98, 100, 102 and 104 attached to end portions 80 and 76 respectively. Latching means 98 and 104 are mated, as are latching means 100 and 102. Brush assembly 56 always rides on that sector of conducting ring 58 which is on that one of the portions 76, 78 and 80 adjacent the welding electrode 24. It will be noted that in Figure 3, both the copper ring 75 and the clamping assembly 54 are in good thermal contact with the tabs a, so that they act as heat sinks for heat generated at the tabs during welding. WHAT WE CLAIM IS:

1. A method of arc welding together tips of each group of leads in an array of spaced groups, comprising clamping the array in position for welding by a clamping means having at least one electrically conductive portion adjacent and in electrical contact with the grouped tips, causing relative movement between a welding electrode and the groups so that the groups move relatively past the welding electrode in succession, the welding electrode having energising means which automatically

switches between applying a high frequency arc-starting voltage and an AC or DC arcmaintaining welding voltage, the arrangement being such that when the arc has been initiated, it is maintained by the arcmaintaining voltage while the welding electrode is opposite the spaces between adjacent groups by an arc circuit completed through the conductive portion of the clamping means, when the arc goes to the conductive portion.

2. A method according to claim 1, in which the electrically conductive portion is in good thermal contact with the grouped tips and acts as a heat sink for heat generated at the tips during welding.

3. A method according to claim 1 or 2, in which the clamping means has opposed electrically conductive portions between which the array is clamped, the arc going to both portions while the welding electrode is opposite the spaces between adjacent groups.

4. A method according to any preceding claim, in which the array is annular.

5. A method according to claim 4, in which the leads are leads of a cylindrical armature.

6. A method according to claim 1, substantially as described with reference to the accompanying drawings.

7. Welding apparatus for arc welding together tips of each groups of leads in an array of spaced groups, comprising clamping means for clamping the array in position for welding, the clamping means having at least one electrically conductive portion which in operation is adjacent and in electrical contact with the grouped tips, a welding electrode and means for mounting and relatively moving the clamping means and the welding electrode in the apparatus, so that in operation the groups move relatively past the welding electrode in succession, the welding electrode having energising means arranged automatically to switch between applying a high frequency arc-starting voltage and an AC or DC arcmaintaining welding voltage, the apparatus being such that, in operation, when the arc has been initiated it is maintained by the arc-maintaining voltage while the welding electrode is opposite the spaces between adjacent groups by an arc circuit completed through the conductive portion of the clamping means, when the arc goes to the conductive portion.

8. Apparatus according to claim 7, in which the clamping means has opposed.

electrically conductive portions between which the array is clamped, one of the portions being a mandrel which in operation is mounted for rotation in the apparatus, but which is readily removable therefrom.

9. Apparatus according to claim 8, in which the mandrel is so electrically connected that the arc goes to the mandrel and to the opposed portion while the welding electrode is opposite the spaces between adjacent groups.

10. Apparatus according to claim 7, 8 or 9, in which the clamping means has an.

electrically conductive portion including a plurality of sectors which together in operation form a cylindrical body, the body having electrical slip ring means extending therearound by way of which electrical contact is made thereto.

11. Welding apparatus according to claim 7, substantially as described with reference to the accompanying drawings.

12. An armature having tips of each group of leads, in an array of spaced groups, welded together by a method as claimed in any of claims 1 to 6, or by apparatus as claimed in any of claims 7 to 11.