Apparatus and method for feeding a through-bolt through a bore in a stator core

Abstract: An apparatus and method for feeding a through-­ bolt (3) through a bore (103) in a dynamoelectric machine (95) while initially feeding the same towards the end (105) of the bore along a line forming an acute angle with the axis of the bore (103). The apparatus (1) has a pair of opposed rotatable wheels (5, 5′) and a support plate (9) therefore, at least one guide roller (23) spaced from one end (17) of the support plate (9), and at least one guide roller (27) spaced from the other end (19) of the support plate (9). A carriage (31) aligns the wheels (5, 5′) and the rollers (23, 27) in two spaced parallel planes through which a through-bolt (3) will pass and a recipro­ cable member (35) on the carriage (31) effects relative movement between the pair of spaced rotatable wheels (5, 5′) and the first and second guide rollers (23, 27), in a direction transverse the parallel planes such that the through-bolt (3) is deflected from the acute angle at which it is being fed and coaxially aligned with the axis of the bore (103) and adapted to be fed therethrough.

Description: The invention relates to an apparatus and a method for feeding a through-bolt through coaxially aligned openings through a stator core of a dynamoelectric machine, which openings form a bore through the stator core, while initially feeding the through-bolt towards a first end of the bore along a line forming an acute angle with the axis of the bore. Large dynamoelectric machines such as generators typically have stator cores, which usually comprise many axially thin annular laminations that are assembled together and compressed to form a cylindrical stator core supported in a frame. Stator coils are received in radial slots in the radially inner periphery of the stator core which extend beyond both axial ends of the stator core and are interconnected to form a stator winding. The stator core laminations have coaxially aligned openings therethrough which form bores through the stator core, and through-bolts extend axially through the bores, with nuts provided on both axial ends of the through-bolts which are torqued or hydraulically tensioned to hold core support system in assembled position and maintain the axial continuity and integrity of the stator core. The through-bolts are insulated, with the nuts maintaining the laminations in axial compression. Such a dynamoelectric machine is described in U.S. 4,227,109, assigned to the assignee of the present invention, and which is directed to a system for providing uniform expansion of a stator. The through-bolts, without the nuts, are generally free to slide axially relative to the frame of the dynamoelectric machine and through the bores in the stator core. These machines, and the through-bolts are large assemblies, with a typical through-bolt being about 3.175 cm (1.25 inches) in diameter wrapped with dielectric insulation to give a total diameter of about 4.29 cm (1.69 inches) and being about 7.62 meters (300 inches) in length, with such bolts weighing on the order of about 45 Kg (100 pounds). At times, the removal of a through-bolt from a stator core is required, such as in retrofitting of the dynamoelectric machine. Often, however, the dynamoelectric machine, because of size, is disposed in a space below the normal floor line of a building, such that the machine is often partially below the floor line. Thus, difficulties often arise due to the lack of clearance available between the end of the stator core and the wall of the foundation or floor level of the building. Such an absence of sufficient clearance prevents the axial alignment for insertion of a through-bolt into the bore of the stator core. There are currently two known methods in use for the retrofitting of such through-bolts. One method requires that the entire generator and rotor be lifted out of the space below the floor level to allow new bolts to be inserted. This method is very expensive and time consuming. Also, when one lifts the generator, one runs the risk of causing misalignment which could cause increased rotor vibration. A second method of installation of a through-bolt requires the use of segmented through-bolts. A segment is partially inserted and then welded to a following segment. The assembly is fed further into the bore and a further segment attached thereto, and the sequence repeated until the attached segments form one long bolt running the length of the generator. Because of the welds, however, such segmented through-bolts are weaker than their one piece counterparts, and are simply too weak for some applications. This procedure also involves the use of a substantial amount of time and expense. It is an object of the present invention to provide a system that will enable the insertion of a through-bolt through the stator core of a dynamoelectric machine, which is disposed in a recessed space having insufficient clearance for axial aligning of the through-bolt with a bore in the stator core. With this object in view, the present invention resides in an apparatus and method for feeding a through-bolt through coaxially aligned openings through a stator core of a dynamoelectric machine, which openings form a bore through the stator core having first and second ends, while initially feeding the through-bolt towards the first bore end along a line forming an acute angle with the axis of the bore. The present invention consists in apparatus for feeding a through-bolt through coaxially aligned openings through a stator core of a dynamoelectric machine, which openings form a bore through the stator core having first and second ends, while initially feeding the through-bolt towards said first bore end along a line forming an acute angle with the axis of said bore characterized in that said apparatus has a pair of spaced rotatable wheels, each having a groove in the periphery thereof; a support plate, having first and second ends, each positioning one of said pair of wheels such that the wheels are aligned in a common plane; at least one first guide roller, having a groove in the outer periphery thereof spaced from said first end of the support plate; at least one second guide roller, having a groove in the outer periphery thereof, spaced from said second end of the support plate; a carriage for aligning and positioning said first and second guide rollers in the plane of said pair of spaced rotatable wheels with the line defined by the centres of said first and second guide rollers being parallel to but displaced from the line defined by the centres of the pair of spaced rotatable wheels by a distance sufficient to pass a through-bolt between the grooves of the said pair of spaced rotatable wheels on the one side and the grooves of said first and second guide rollers on the other side; and a reciprocable member on said carriage for effecting relative movement between said pair of spaced rotatable wheels and said first and second guide rollers, in a direction transverse the parallel lines defined by their centers, whereby the through-bolt is deflected from said acute angle, while being passed between said pair of spaced rotatable wheels and said first and second guide rollers, towards said first bore end and is positioned coaxially with the axis of said bore and adapted to be fed therethrough. Preferably, the first and second guide rollers each comprise a pair of adjacent guide rollers. In one embodiment, the carriage has a first pair of spaced end plates and shafts extending therebetween on which the first guide roller is disposed, a second pair of spaced end plates and shafts extending therebetween on which the second guide roller is disposed, a first link bar extending between the first end of the support plate and the first pair of spaced end plates, a second link bar extending between the second end of the support plate and the second pair of spaced end plates, a first beam extending between the first pair of spaced end plates and the reciprocable member, a second beam extending between the second pair of spaced end plates and the reciprocable member, with the reciprocable member extending between the beams and the support plate, a pivotable connection between each pair of end plates and a respective link bar, a pivotal connection between each pair of end plates and a respective beam, and a pivotal connection between each beam and the reciprocable member. In another embodiment, the carriage has a first pair of spaced end plates and shafts extending therebetween on which the first guide roller is disposed, a second pair of spaced end plates and shafts extending therebetween on which the second guide roller is disposed, a U-shaped tie beam having a central section extending between the first and second pairs of end plates and a leg section extending between the central section and a respective pair of end plates, the leg pivotally secured to the respective pair of end plates, with the reciprocable member being secured at one end to the central section of the U-shaped tie beam and at the other end thereof to the support plate. The invention will become more readily apparent from the following description of preferred embodiments thereof shown, by way of example only, in the accompanying drawings, wherein: Figure 1 is a side elevational view of a preferred embodiment of an apparatus of the present invention showing a through-bolt in straight line position therethrough; Figure 2 is a view taken along lines II-II of Figure 1 with the through-bolt removed for clarity; Figure 3 is a side elevational view of the embodiment of Figure 1 where the through-bolt is deflected therein; Figure 4 is a schematic illustration of another preferred embodiment of the apparatus of the present invention in position to feed a through-bolt to the bore end of a generator; and Figure 5 is a schematic illustration of the embodiment shown in Figure 4 feeding a through-bolt fed initially at an angle to the bore through a stator core, into the stator core bore in a coaxial direction therewith. The present apparatus and method are usable to insert a through-bolt through the stator core of a dynamoelectric machine, such as a generator, when the through-bolt cannot be axially aligned with the bore through the stator core due to space limitations. As described previously, such bolts can be on the order of 7.62 meters (300 inches) in length. Such bolts are generally formed from a steel alloy, such as a nickel based steel, for example a Nitronic steel alloy such as Nitronic 32. The bolt, as described previously is wrapped with a dielectric insulation, such as a tape insulation sold under the trade name Nomex. Such insulation must be protected during any manoeuvring of the bolt during installation into the stator core. Referring now to the drawings, an apparatus 1 is provided for feeding a through-bolt 3 through a bore in a stator core of a dynamoelectric machine. The apparatus 1, includes a pair of spaced rotatable wheels 5, 5′, each having a groove 7 in the periphery thereof, which are supported for free-wheeling movement by a support plate 9. The support plate 9 is preferably a pair of side plates 11, 11′ that have shafts 13, 13′ extending therebetween upon which the spaced rotatable wheels 5, 5′ are mounted, with additional spacing members 15 positioned therebetween to support the wheels 5, 5′. The support plate has a first end 17 and a second end 19 and positions the spaced rotatable wheels 5, 5′ such that the grooves thereof are aligned in a first common plane, indicated as 21 in the drawings. In a preferred embodiment, a first pair of adjacent guide rollers 23, 23′, which have grooves 25 in the outer periphery thereof are provided spaced from the first end 17 of the support plate 9, while a second pair of adjacent guide rollers 27, 27′, which have grooves 29 in the outer periphery thereof are provided spaced from the second end 19 of the support plate 9. A carriage 31 aligns and positions the first pair of adjacent guide rollers 23, 23′ and the second pair of adjacent guide rollers 27, 27′ in a second plane, indicated as 33 in the drawings, parallel to and spaced from the plane 21 of the pair of spaced rotatable wheels 5, 5′, a distance sufficient to pass a through-bolt 3 between the grooves 7 of the spaced rotatable wheels 5, 5′ and the first and second pairs of adjacent guide rollers 23, 23′, 27, 27′. A reciprocable member 35, such as a hydraulic cylinder with exposed plunger 36 is provided on the carriage 31 to effect relative movement between the pair of spaced rotatable wheels 5, 5′ and the first and second pairs 23, 23′, 27, 27′ of adjacent guide rollers, in a direction transverse the parallel planes 21, 33. In the embodiment illustrated in Figures 1 to 3, the carriage 31 contains a first pair of spaced end plates 37, 37′ with shafts 39, 39′ which extend therebetween and upon which the first pair of adjacent guide rollers 23, 23′ are disposed, and a second pair of spaced end plates 41, 41′ with shafts 43, 43′ which extend therebetween and upon which the second pair of adjacent guide rollers 27, 27′ are disposed. A first pair of link bars 45, 45′ extend between the first end 17 of the support plate 9 and the first pair of spaced end plates 37, 37′. The link bars 45, 45′ are pivotally connected to the support plate 9, preferably by pivotal attachment to the ends of the shaft 13, as indicated at 47, and are also pivotally connected to the pair of spaced end plates 37, 37′, preferably by pivotal attachment to the ends of a pivot pin 49 extending between the spaced end plates 37, 37′. The end plates 37, 37′ are, as illustrated, preferably triangular in shape, with the rollers 23, 23′ adjacent the base 51 of the triangle and the pivot pin 49 adjacent the apex 53 of the triangle. Similarly, a second pair of link bars 55, 55′ extend between the second end 19 of the support plate 9 and the second pair of spaced end plates 41, 41′. The link bars 55, 55′ are pivotally connected to the support plate 9, preferably by pivotal attachment to the ends of the shaft 13′, as indicated at 57, and are also pivotally connected to the pair of spaced end plates 41, 41′ preferably by pivotal attachment to a pivot pin 59 extending between the spaced end plates 41, 41′. The end plates 41, 41′ are also preferably triangular in shape, with the rollers 27, 27′ adjacent the base 61 of the triangle and the pivot pin 59 adjacent the apex 63 thereof. The reciprocating member 35 is attached to the support plate 9 by a fastener 65 and extends away from the support plate 9 in a direction normal to the plane 21 of the grooves 7 in wheels 5 and 5′. A first beam 67 extends between a clevis 69, on the plunger 36 of the reciprocating member distant from the support plate 9, and the first pair of end plates 37, 37′, while a second beam 71 extends between a clevis 73, on the plunger 36, and the second pair of end plates 41, 41′. The two beams 67 and 71 are pivotally secured to the clevises 69 and 73 by pivot pins 75 and 77 respectively, while the other ends thereof are pivotally secured to the respective end plates 37, 37′ and 41, 41′ by pivot pins 49 and 59, respectively. In the embodiment of the apparatus 1, designated as 81, illustrated in Figures 4 and 5, the carriage 31 contains a first pair of end plates 37, 37′ with shafts 39, 39′ which extend therebetween and upon which the first pair of guide rollers 23, 23′ are disposed, and a second pair of spaced end plates 41, 41′ with shafts 43, 43′ which extend therebetween and upon which the second pair of adjacent rollers 27, 27′ are disposed. A U-shaped tie beam has a central section 83 which extends between the first and second pairs of end plates 37, 37′ and 41, 41′, and two leg sections 85 and 87. Leg section 85 extends between the central section 83 and the first pair of spaced end plates 37, 37′ and is pivotally connected thereto through pivot pin 89, while the leg section 87 extends between the central section 83 and the second pair of spaced end plates 41, 41′ and is pivotally connected thereto through pivot pin 91. Cross braces 93 may be provided for strengthening the leg section and central section. The reciprocable member 35 is attached to the central section 83 of the carriage 31, and extends in a direction normal to the planes. While both embodiments of the apparatus 1 and 81 provide a reciprocable member on a carriage for effecting relative movement between the first pair of rotatable wheels and the first and second pairs of adjacent guide rollers, alternative movement is effected in the two embodiments. In the first embodiment of the apparatus 1, the plunger 36 moves the first and second pairs of adjacent guide rollers 23, 23′ and 27, 27′ towards the pair of rotatable wheels 5, 5′, while in the second embodiment of the apparatus 81, the plunger 36 moves the pair of rotatable wheels 5, 5′ towards the first and second pairs of adjacent guide rollers 23, 23′ and 27, 27′. In both embodiments, the through-bolt 3 is deflected from the acute angle at which it is initially fed, while being passed between the pair of spaced rotatable wheels and the first and second pairs of adjacent guide rollers, towards the end of the bore through the stator core and positioned coaxially therewith and adapted to be fed through the bore. Also, while the embodiments illustrated show a pair of adjacent guide rollers on each side of the rotatable wheels 5, 5′, one such guide roller could be substituted for each said pair, within the scope of the present invention. The practice of the present invention is illustrated with reference to Figures 4 and 5. As illustrated, a dynamoelectric machine 95 has a stator core 97 therein. The stator core is comprised of laminations 99 that have openings 101 therethrough, the openings 101 forming a bore 103 having a first end 105 and second end 107. As illustrated, the dynamoelectric machine 95 is often set into a space below the floor level or foundation 109 which prohibits straight axial placement of a through-bolt 3 into the first end 105 of the bore 103. The through-bolt is, according to the present invention, fed towards the first end 105 of the bore 103 along an acute angle α with the axis of the bore 103, with the leading end 111 approaching the bore 103, and the trailing end 113 distant therefrom. While the insulation on the through-bolt is under compression at the wheels 5, 5′ of the support plate, the rollers 23, 23′ spaced from one end 17 of the support plate 9, and the rollers 27, 27′ spaced from the other end 19 of the support plate 9, distribute the load on the outer surface of the through-bolt therebetween. The through-bolt 3 may be manually fed through the apparatus 1, and the apparatus 1 may be held manually or supported by an attachment means 115 releasably secured to the dynamoelectric machine 95 and/or on attachment means 117 releasably secured to an adjacent foundation 109 or other support surface, which attachment means comprise support legs 119. While the present apparatus is described for use in feeding a through-bolt to a bore in the stator core, it should be noted that the same can also be used to remove a through-bolt from a stator core where spacing is limited by reversing the steps above and feeding the coaxially fed through-bolt through the apparatus 1, so as to deflect the same into an acute angle with the bore and remove the same at such an acute angle.

Claims: An apparatus (1) for feeding a through-bolt (3) through coaxially aligned openings (101) through a stator core (97) of a dynamoelectric machine (95), which openings form a bore (103) through the stator core having first and second ends (105, 107), while initially feeding the through-bolt (3) towards said first bore end (105) along a line forming an acute angle with the axis of said bore (103) characterized in that said apparatus has: a pair of spaced rotatable wheels (5, 5′), each having a groove (7) in the periphery thereof; a support plate (9), having first (17) and second (19) ends, each positioning one of said pair of wheels (5, 5′) such that the wheels (5, 5′) are aligned in a common plane; at least one first guide roller (23), having a groove (25) in the outer periphery thereof spaced from said first end (17) of the support plate (9); at least one second guide roller (27), having a groove (29) in the outer periphery thereof, spaced from said second end (19) of the support plate (9); a carriage (31) for aligning and positioning said first and second guide rollers (23, 27) in the plane of said pair of spaced rotatable wheels (5, 5′) with the line defined by the centres of said first and second guide rollers (23, 27) being parallel to but displaced from the line defined by the centres of the pair of spaced rotatable wheels (5, 5′) by a distance sufficient to pass a through-bolt (3) between the grooves of the said pair of spaced rotatable wheels (5, 5′) on the one side and the grooves of said first and second guide rollers (23, 27) on the other side; and a reciprocable member (35) on said carriage (31) for effecting relative movement between said pair of spaced rotatable wheels (5, 5′) and said first and second guide rollers (23, 27), in a direction transverse the parallel lines defined by their centers, whereby the through-bolt (3) is deflected from said acute angle, while being passed between said pair of spaced rotatable wheels (5, 5′) and said first and second guide rollers (23, 27), towards said first bore end (105) and is positioned coaxially with the axis of said bore (103) and adapted to be fed therethrough. The apparatus (1) as defined in claim 1 characterized in that a first pair of adjacent guide rollers (23, 23′) is provided, each having a groove (25) in the outer periphery thereof, spaced from said first end (17) of the support (9), and a second pair of adjacent guide rollers (27, 27′) is provided, each having a groove (29) in the outer periphery thereof, spaced from said second end (19) of the support plate (9). The apparatus (1) as defined in claim 2 characterized in that said carriage (31) comprises a first pair of spaced end plates (37, 37′) and shafts (39, 39′) extend ing therebetween on which said first pair of adjacent guide rollers (23, 23′) are disposed, a second pair of spaced end plates (41, 41′) and shafts (43, 43′) extending therebetween on which said second pair of adjacent guide rollers (27, 27′) are disposed, a first pair of link bars (45, 45′) extending between the first end (17) of said support plate (9) and said first pair of spaced end plates (37, 37′), a second pair of link bars (55, 55′) extending between the second end (19) of said support plate (9) and said second pair of spaced end plates (41, 41′), a first beam (67) extending between said first pair of spaced end plates (37, 37′) and said reciprocable member (35), a second beam (71) extending between said second pair of spaced end plates (41, 41′) and said reciprocable member (35), with said reciprocable member (35) extending between said beams (67, 71) and said support plate (9), a pivotable connection (47, 57) between each said pair of side plates (11, 11′) and a respective link bar (45, 45′, 55, 55′), a pivotal connection (49, 59) between each said pair of end plates (37, 37′, 41, 41′) and a respective beam (67′, 71′), and a pivotal connection between each said beam (67, 71) and said reciprocable member (35). The apparatus (1) as defined in Claim 3 characterized in that said spaced end plates (37, 37′, 41, 41′) are triangular in shape, with said guide rollers (23, 23′, 27, 27′) adjacent the base (51) of said triangle and said beam (67, 71) and link bars (45, 45′, 55, 55′) are pivotally connected adjacent the apex of said triangle. The apparatus (1) as defined in Claims 3 or 4 characterized in that said reciprocable member (35) has opposed (69, 73) clevises on the end of said reciprocable member (35), and said first and second beams (67, 71) are pivotally connected to said opposed clevises. The apparatus (1) as defined in Claims 1 or 2 characterized in that said carriage (31) comprises a first pair of spaced end plates (37, 37′) and shafts (39, 39′) extending therebetween on which said first pair of adjacent guide rollers (23, 23′) are disposed, a second pair of spaced end plates (41, 41′) and shafts (43, 43′) extending therebetween on which said second pair of adjacent guide rollers (27, 27′) are disposed, a U-shaped tie beam having a central section (83) extending between said first and second pairs of end plates (37, 37′, 41, 41′) and leg sections (85, 87) extending between said central section (83) and a respective pair of end plates, said leg (85, 87) pivotally secured to said respective pair of end plates (37, 37′, 41, 41′) , with said reciprocable member (35) being secured at one end to said central section (83) of said U-shaped tie beam and at the other end thereof to said support plate (9). The apparatus (1) as defined in Claim 6 characterized in that said spaced end plates (37, 37′, 41, 41′) are triangular in shape, with said guide rollers (23, 23′, 27, 27′) adjacent the base (51) of said triangle and said legs (85, 87) are pivotally connected (89, 91) adjacent the apex of said triangle. A method of inserting a through-bolt through coaxially aligned openings through a stator core of a dynamoelectric machine, which openings form a bore through the stator core having first and second ends characterized in that: a through-bolt having a leading and a trailing end is fed towards the first end of said bore along a line forming an acute angle with the axis of said bore; said through-bolt is subjected to a bending force, intermediate said leading end and said trailing end, to position said leading end into coaxial relationship with said first end of said bore; and said through-bolt is further fed with said leading and passing through said bore until the leading end thereof passes through said second end of said bore. The method as defined in Claim 8 characterized in that said through-bolt is formed from a nickel based steel alloy and has a dielectric coating thereon.

Inventors: BUTLER III JOHN MEIGS, LICHTENFELS KURT KOTTMAN, BUTLER III, JOHN MEIGS, LICHTENFELS, KURT KOTTMAN
Applicants: WESTINGHOUSE ELECTRIC CORP, WESTINGHOUSE ELECTRIC CORPORATION
Application year: 1989
Main classification: H02K15
IPC codes: H02K15, B23P21, B23P19