This application is based upon and claims the benefit of priority from Japanese Patent Applications No. 2014-037603, filed on Feb. 27, 2014 and No. 2015-019037, fled on Feb. 3, 2015; the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a method of manufacturing a rotor coil and a rotary electrical machine.
A rotor coil of a variable-speed generator motor used for pumped-storage power generation and so on is manufactured by applying a manufacturing method in which, for example, a long copper band is formed into a coil state by so-called an edgewise-bending, a manufacturing method in which strip-state plural copper bands are connected by brazing or a TIG (Tungsten Inert Gas) welding to form into the coil state, and so on.
Here, in the rotor coil of the variable-speed generator motor, a reinforcing member whose rigidity is high is joined by the TIG welding and so on to an end part of a wire strand in which plural wires are bundled to prevent deformation of a coil end part by a centrifugal force. Note that copper, copper alloy, and so on are generally used for materials of the wire strand and the reinforcing member.
However, copper and copper alloy are materials which are difficult to be welded. Therefore, in the manufactured rotor coil, defects are easy to occur at welded parts, and the sufficient mechanical strength cannot be obtained after welding, and further, deformation after the welding, and so on are worried.
Problems to be solved by the embodiments are to provide a method of manufacturing a rotor coil and a rotary electrical machine capable of securing desired mechanical strength while suppressing occurrences of defects and deformations.
A method of manufacturing a rotor coil according to an embodiment includes preparing a wire strand including a plurality of wires and a reinforcing member configured to reinforce the wire strand, each of the wires being bundled to form the wire strand; arranging the wire strand and the reinforcing member to bring an end of the wire strand and an end of the reinforcing member into contact with each other, the wire strand being arranged to have a longitudinal direction perpendicular to a boundary between the wire strand and the reinforcing member and to include the plurality of wires with an inclined longitudinal direction thereof on a first outer surface inclining with respect to the longitudinal direction of the wire strand; rotary driving a tool at the boundary on the first outer surface so as to enter the boundary; and moving the rotary driven tool on the boundary along the first outer surface.
Hereinafter, embodiments are described based on the drawings.
The rotary electrical machine 10 includes a stator 3, a rotor 5, and so on. Besides, the rotary electrical machine 10 includes a cooling mechanism and so on having, for example, fans 15 and airflow ducts symmetrically provided at both ends of a rotation shaft 9 of the rotor 5 respectively. The rotation shaft 9 is supported by a structure part including the stator 3 via a bearing mechanism. The stator 3 includes a stator coil 12 and a stator core 14. On the other hand, the rotor 5 includes a rotor core 8 and the rotor coils 7 integrally provided with the rotation shaft 9.
As illustrated in
Besides, the rotor coil 7 is made up of a wire strand 31, an insulating layer 21, an electric field relaxation layer (low-resistance corona prevention layer) 22, and so on as illustrated in
Here, in the rotor coil 7 for the variable-speed generator motor (variable-speed rotary electrical machine), a coil end part is made up by joining a reinforming member 32 to an end part of the wire strand 31 as illustrated in
Accordingly, the reinforcing member 32 has a rectangular parallelepiped solid structure to obtain the rigidity (mechanical strength) higher than the wire strand 31 in which the wires are bundled. Note that the reinforcing member 32 is supported by a rotor main body via a predetermined supporting member. Besides, the reinforcing member 32 and the wires 20a of the wire strand 31 are made up by using copper and copper alloy as materials. Note that it is also possible to make up the reinforcing member 32 and the wires 20a of the wire strand 31 by using aluminum and aluminum alloy as the materials.
Next, a method of manufacturing a rotor coil of the present embodiment which suitably enables the joining between the wire strand 31 and the reinforcing member 32 is described mainly based on
Here, groove shapes of the wire strand 31 and the reinforcing member 32 to be joining objects are each so-called an I groove (I-shape groove). Namely, respective whole interfaces (respective facing end faces of the end parts 31a, 32a with each other) of the wire strand 31 and the reinforcing member 32 which are directly brought into contact in the contact step are both formed by flat surfaces.
Next, in the first joining step, as illustrated in
The tool 30 is a joining tool in approximately a stepped columnar shape having a large diameter shoulder part 30a and a small diameter projecting part 30b provided at a tip part side of the shoulder part 30a. Besides, the tool 30 is movable in triaxial directions and rotates (rotary drives) while using an axial center of itself as a rotation center. The projecting part 30b is a penetration part directly penetrated into the boundary part 25 (joining object parts 30c, 30d). A projecting length of the projecting part 30b is appropriately set in accordance with a thickness of the boundary part 25 in a penetrating direction.
Besides, operations of the tool 30 are adjusted such that a rotation speed in the arrow S1 direction is, for example 800 rpm to 1400 rpm, a moving speed in the arrow B1 direction is, for example, 20 cm/min to 30 cm/min, and a load penetrating the projecting part 30b into the boundary part 25 becomes, for example, 2000 kgf to 5000 kgf.
Here, in the first joining step, as illustrated in
In more detail, in the method of manufacturing the rotor coil of the present embodiment, as illustrated in
Note that individual wires 20a making up the wire strand 31 are bundled in a state in which longitudinal directions of the individual wires 21a are inclined (each having an inclination of an angle θ) relative to the longitudinal direction of the wire strand 31 main body (the arrows X1-X2 direction) when it is seen from the first outer surface F1 side as illustrated in
As mentioned above, in the first joining step, as illustrated in
At this time, the tool 30 rotary driving in the arrow S1 direction generates a friction stir force which winds up the end parts of the respective wires 37b (the end part 37a of the wire strand 37) each inclining in the wire strand 37 in the arrow S1 direction, and acts to change a direction of the end part of each inclining wire 37b to be perpendicular to the interface 25a. As a result, adhesiveness between an end face of each wire 37b of the wire strand 37 and the end face of the reinforcing member 32 improves, and it becomes possible to increase a joining strength.
As stated above, according to the method of manufacturing the rotor coil of the first embodiment, it is possible to improve the joining strength between the wire strand 31 and the reinforcing member 32. As a result, according to the manufactured rotor coil, it is possible to obtain desired mechanical strength.
Therefore, according to the method of manufacturing the rotor coil of the present embodiment, it is possible to suppress lowering of strength resulting from the thermal effect at the boundary part 25 (base material), and to secure the desired mechanical strength. Besides, in the method of manufacturing the present embodiment, the reinforcing member 32 and the wire strand 31 made of copper and copper alloy being the material difficult to be welded are joined with each other without using the welding technology such as the TIG welding (by using the friction stir welding which is not accompanied by a melting phenomenon being a process suitable for the joining of the material difficult to be welded), and therefore, it is possible to suppress occurrences of defects and deformations at the joining part. Further, according to the method of manufacturing the present embodiment, it is not necessary to process the groove shape at the joining part, to perform preheating, and so on which are, for example, required when welding is performed, and it is possible to reduce a manufacturing cost.
Besides, according to the rotary electrical machine 10 including the rotor coil 7 manufactured as stated above, it is possible to increase the suppression effect for the deformation and so on of the coil end part resulting from the centrifugal force at the operation time accompanied by the speed change. Further, in the rotary electrical machine 10, it is possible to substantially improve the mechanical strength at the joining part between the wire strand 31 and the reinforcing member 32, and therefore, it is possible to closely dispose the joining part between the wire strand 31 and the reinforcing member 32 in a vicinity of the rotor core 8 where a large stress is structurally easy to be applied.
Here, the method of manufacturing the rotor coil of the present embodiment may have a coating removal step (removing the insulation coating) before the contact step. This coating removal step is a step removing the insulation coating 20b in advance from at least the end parts (a part making up a part to be friction stir welded) at a side to be in contact with the reinforcing member 32 of the plural wires 20a illustrated in
Namely, as illustrated in
Besides, in the method of manufacturing the rotor coil of the present embodiment, as illustrated in
Further, as illustrated in
Besides, in the method of manufacturing the rotor coil of the present embodiment, the contact step and the first joining step are performed, and thereby, as illustrated in
Note that as illustrated in
Next, a second embodiment is described based on
In a method of manufacturing a rotor coil of the present embodiment, a second joining step (the second joining step having rotary driving a tool at the boundary on a second outer surface, and moving the rotary driven tool on the boundary along the second outer surface) as well as the contact step and the first joining step is performed.
Namely, in the second joining step, the wire strand 31 and the reinforcing member 32 in which the joining object part 30c is friction stir welded are turned over so that a second outer surface F2 side positioning at a rear surface side of the first outer surface F1 becomes an upper surface as illustrated in
In more detail, in the second joining step performed from the second outer surface F2 side, for example, the step is performed while the rotation direction and the sliding direction of the tool 30 are reversed from the first joining step performed from the first outer surface F1 side. At this time, the tool 30 generates the friction stir force which winds up the end parts of the respective wires 20a in the arrow S2 direction, and acts to change the direction of the end part of each inclining wire 20a to be perpendicular to the interface 25a also in this case, and thereby, as described in the first embodiment, it becomes possible to increase the joining strength. Note that in the second joining step, the rotation direction and the sliding direction of the tool 30 may be set to be the same directions as the first joining step by appropriately adjusting and so on, for example, the rotation speed of the tool 30, the moving speed when the tool 30 is slided, and so on.
As it is already described, in the method of manufacturing the rotor coil of the present embodiment, the wire strand 31 and the reinforcing member 32 are friction stir welded by being divided into two passes (two times) of the first outer surface F1 side and the second outer surface F2 side, and therefore, it is possible to narrow down the thermal effect range where the boundary part 25 (base material) is affected by the thermal effect by the friction stir.
Namely, for example, when the boundary part 25 is friction stir welded in one pass, the friction stir is performed for a whole of a thickness direction of the boundary part 25 at one time, and therefore, for example, a tool whose size is enlarged is applied in consideration of rigidity and so on to incur a result of widening the thermal effect range. On the other hand, according to the method of manufacturing the present embodiment in which the boundary part 25 is friction stir welded in two passes, a tool whose size is rationally set small is applied by being divided into two times, and therefore, it is possible to narrow down the thermal effect range as a result.
Therefore, according to the method of manufacturing the rotor coil of the present embodiment, it is possible to suppress lowering of strength resulting from the thermal effect at the boundary part 25 (base material), and to secure the desired mechanical strength.
Next, a third embodiment is described based on
In a method of manufacturing a rotor coil of the present embodiment, the first joining step is performed (or the first and second joining steps are respectively performed) while cooling at least the boundary part 25 between the wire strand 31 and the reinforcing member 32. The cooling in this case is enabled by, for example, a cooling member inside which a coolant flows is brought into contact with the wire strand 31 and the reinforcing member 32, and so on.
Specifically, as illustrated in
Besides, instead of the above, as illustrated in
Therefore, according to the method of manufacturing the rotor coil of the third embodiment, heat generation generated at the friction stir welding time can be suppressed, and therefore, it is possible to suppress the lowering of the strength of the boundary part 25 (joining object part) resulting from the thermal effect, and thereby, it is possible to secure desired rigidity at the boundary part 25 where the wire strand 31 and the reinforcing member 32 are joined.
Next, a fourth embodiment is described based on
In a method of manufacturing a rotor coil of the present embodiment, as illustrated in
Further, when performing to the first joining step (or when performing to the first and second joining steps), as illustrated in
According to this manufacturing method, it is possible to prevent that the wires 20a are taken to pieces from the wire strand 31 main body, and so on in addition that it is possible to suppress that joining marks at the friction stir welding time by the projecting part (penetration part) 30b of the tool 30 remain at a surface (upper surface) of the boundary part 25 and so on. Note that after the joining of the boundary part 25, the joined pair of holding members 53, 54 may be removed from the wire strand 31 and the reinforcing member 32 sides.
Besides, a method of manufacturing a rotor coil illustrated in
The protective member 55 is a rectangular thin sheet with a thickness of 2 mm or more whose material is copper or copper alloy. This protective member 55 is disposed to cover over the boundary part 25 (a boundary line on the first or second outer surface F1, F2) while aligning its own longitudinal direction in the sliding direction (the arrow B1 direction) of the tool 30, and is fixed at this position via a jig and so on. Besides, a length in a short side direction of the protective member 55 is made up to be a length of a diameter of the shoulder part 30a of the tool 30 or more. Further, a thickness of the protective member 55 is made up to be a thickness of a dent or more capable of being generated by the sliding with, for example, the end face of the shoulder part 30a of the tool 30 at the friction stir welding time.
After the protective member 55 as stated above is disposed, when performing to the first joining step (or when performing to the first and second joining steps), the rotary driving tool 30 is penetrated into the boundary part 25 via the protective member 55 from the first or second outer surface F1, F2 side, and is slided (moved) along the interface 25a. According to the manufacturing method as stated above, it is possible to compensate a degree of the dent generated by the sliding with the shoulder part 30a of the tool 30 with the thickness of the protective member 55, and to secure the joining strength of the boundary part 25 (joining object part).
Instead of the manufacturing method as stated above, it is possible to apply a method of manufacturing a rotor coil illustrated in
As illustrated in
After the joining auxiliary member 56 as stated above is disposed, when at least the first joining step is performed, the rotary driving tool 30 is penetrated into the one holding part 56b of the joining auxiliary member 56 from the first outer surface F1 side, and is slided (moved) on the other holding part 56c along the interface 25a of the boundary part 25. Note that when the second joining step is performed, after for example, the protective member 55 illustrated in
As it is already described, according to the method of manufacturing the rotor coil illustrated in
It goes without saying that instead of the above, a protective member 61 and the pair of holding members 53, 54 which are each made up by individual members as illustrated in
According to at least one embodiment described hereinabove, it is possible to manufacture a rotor coil capable of securing desired mechanical strength while suppressing occurrences of defects and deformations.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
Number | Date | Country | Kind |
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2014-037603 | Feb 2014 | JP | national |
2015-019037 | Feb 2015 | JP | national |