Abstract:
A tool is disclosed for driving a slide under a wedge within a slot of an armature or field of a dynamoelectric machine. The tool comprises a frame including a pair of elongated rail members; a force application block located between the rail members; a drive connected to the frame, substantially intermediate opposite ends of the frame; a lead screw threadably engaged at one end with the force application block and connected at an opposite end to the drive such that the drive rotates the lead screw when actuated. Rotation of the lead screw causes axial movement of the force application block. The armature or field includes a core, and this core may have one or more vent slots for facilitating ventilation of the armature or field. A slot plate for locating the tool relative to the slide is present, and a portion of the slot plate extends into one or more vent slots. The slot plate establishes a reaction point for forces applied by the force application block to the stator slide.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to dynamoelectric machines and, in particular, to a tool for installing a stator slide under a stator wedge in the stator core of a generator. 
         [0002]    Dynamoelectric machines, such as generators, typically employ a stator or armature core comprised of stacked laminations of magnetic material forming a generally annular assembly. An array of axially extending circumferentially spaced stator core slots are formed through the radial inner surface of the annular assembly. Armature or stator windings are disposed in these slots. A rotor or field is coaxially arranged within the stator core and contains field windings typically excited from an external source to produce a magnetic field rotating at the same speed as the rotor. With the foregoing arrangement, it will be appreciated that electrical output is generated from the armature windings. 
         [0003]    Stator or armature windings are seated within the stator core slots and are held in place by a slot support system that includes stator wedges, stator slides, filler strips and ripple springs. These support components are employed in order to maintain the stator armature windings in a radially tight condition within the slots. The armature windings of generators operate under continuous strain of electromagnetic forces that must be completely contained to prevent high voltage armature winding insulation damage. Insulation damage can also be exacerbated by relative movement between the armature windings and stator core. The wedges, slides, filler strips and ripple springs impose radial forces on the armature windings and aid the windings in resisting magnetic and electrically induced radial forces. 
         [0004]    The stator wedges are received within axial dovetail slots on opposite sidewalls of the radial slots. During the process of tightening the stator wedges, it is necessary to install a stator slide against each stator wedge. For the sake of convenience, reference will be made herein to “stator wedges” that are seated in the dovetail slots and “stator slides” that are used to tighten the wedges. The stator slide can be, but is not necessarily, pre-gauged and pre-sized to have a significant interference fit relative to the slot contents, i.e., the windings, fillers and ripple springs. The force required to install the stator slide may be thousands of pounds. 
         [0005]    Several methods have been used to provide the force required to install the stator slides. For example, stator slides have been manually installed using a drive board and a large hammer, or by using a modified pneumatically operated hammer. These methods, however, are time consuming and place considerable strain on the operator. They also subject the operator to fatigue, the risk of repetitive motion injury and/or hearing damage, and pose a risk to the integrity of the stator core and armature windings. The hammering technique can also cause snapped stator slides, which result from off-center hits, or an operator can inadvertently miss the slide and hit the stator core, resulting in damage to the core and a lengthy and time-consuming process to fix the damaged core portions. The uniformity and consistency of the stator wedge and stator slide tightness is also poor using the above-described methods. 
         [0006]    Accordingly, a need exists in the art for a device that can be used to drive stator slides that minimizes operator fatigue and injury, minimizes stator core damage, minimizes installation time, and maximizes uniformity and consistency of stator wedge and stator slide tightness. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0007]    This invention provides a new stator slide driver device that enables a smooth, controlled, non-impacting stator slide assembly technique, with significant reduction or elimination of the aforementioned risks. 
         [0008]    A tool is disclosed for driving a slide under a wedge within a slot of an armature or field of a dynamoelectric machine. The tool comprises a frame including a pair of elongated rail members; a force application block located between the rail members; a drive connected to the frame, substantially intermediate opposite ends of the frame; a lead screw threadably engaged at one end with the force application block and connected at an opposite end to the drive such that the drive rotates the lead screw when actuated. Rotation of the lead screw causes axial movement of the force application block. The armature or field includes a core, and this core may have one or more vent slots for facilitating ventilation of the armature or field. A slot plate for locating the tool relative to the slide is present, and a portion of the slot plate extends into one or more vent slots. The slot plate establishes a reaction point for forces applied by the force application block to the stator slide. 
         [0009]    A tool is disclosed for driving a slide between a wedge and armature winding in a dynamoelectric machine. The dynamoelectric machine includes an armature core and a plurality of armature winding slots. The armature core includes one or more vent slots for facilitating ventilation of the armature core. The tool comprises a frame including a pair of elongated rail members, the frame having opposing frame ends disposed near the ends of the elongated rail members; force application means located generally between the elongated rail members, the force application means comprising a wedge driving member, the wedge driving member making contact with the slide, the force application means and the wedge driving member for applying force to the slide to drive the slide between the wedge and the armature winding; a vent slot plate located near one of the opposing frame ends, a portion of the vent slot plate extending into the one or more vent slots, and for establishing a reaction point for forces applied by the force application means to the slide. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0010]      FIG. 1  is a partial, axial cross-sectional illustration of a stator core slot with a stator slide and a stator wedge in place. 
           [0011]      FIG. 2  is a perspective illustration of one embodiment of a tool that may be used to drive the stator slides shown in  FIG. 1 . 
           [0012]      FIG. 3  is an exploded perspective illustration of one embodiment of a tool that may be used to drive the stator slides shown in  FIG. 1 . 
           [0013]      FIG. 4  is a partial, perspective illustration of a stator core. 
           [0014]      FIG. 5  is a cross-sectional illustration of one embodiment of a tool used to drive the stator slides. 
           [0015]      FIG. 6  is an enlarged, partial perspective illustration of a stator core, and shows the interrelation between the stator slots and the stator wedges and stator slides. 
           [0016]      FIG. 7  is an enlarged, partial perspective illustration of the tool in place above a stator slot, showing the inter-relation between the stator wedge, stator slide, ripple spring and tool, according to one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]    Referring to  FIG. 1 , a magnetic stator core for a generator is partially shown at  100 . The drawing is not necessarily to scale and the individual elements are shown to illustrate the interaction between the various elements. The stator core can be formed of many laminations of a magnetic steel or iron material. Typically, laminations are arranged in groups, and each group is separated by a spacer (not shown in  FIG. 1 ). The spacers define axially spaced gaps between groups of laminations, and these gaps permit ventilation and cooling of the stator core  100 . A plurality of radially oriented stator slots  105  extend axially along the stator core, with armature windings  110  seated therein. Typically, one or two armature windings  110  are present in each slot  105 , but three or more could also be present. Each slot  105  is formed adjacent its mouth with a dovetail groove or undercut  115  in opposed side walls of the slot  105 , permitting several to many stator wedge  120  and stator slide  125  components to be inserted in an axial direction along the length of the slot  105 . It will be understood that flat filler strips  130  and ripple springs  135  may be disposed between the windings  110  and the stator wedges  120  and stator slides  125  as shown in  FIG. 1 . In this regard, the individual stator wedges  120  and slides  125  are generally between about 3 and 12 inches in length, and the stator core may have a length of between about 50 and 350 inches, and a diameter of between about 3 to 12 feet. Accordingly, up to 3,000 or more stator slides  125  may need to be installed in a typical generator. 
         [0018]    The stator wedges  120  and stator slides  125 , as well as the filler strips  130 , can be constructed of a woven glass fabric combined with a high temperature resin. This material has excellent mechanical strength and electrical properties at elevated temperatures. The ripple springs  135  can be constructed of a unidirectional glass fabric combined with epoxy resin. The ripple springs have a wavy or sinusoidal shape along their length. This waviness gives the ripple springs resiliency, and this resiliency helps to absorb the expansion and contraction of the armature windings  110  during the various operating cycles of a generator, while maintaining the armature windings  110  tightly constrained within the stator slot  105 . Alternatively, any other suitable material can be used for the stator wedges, stator slides, filler strips and ripple springs. In other embodiments, the material may also include magnetic particles, to enhance the magnetic characteristics of the stator core. 
         [0019]    With reference now to  FIGS. 2-4 , and in accordance with one embodiment of the present invention, the stator slide driving tool  200  can be a pneumatic tool. Alternatively, the tool may be powered by batteries, fuel cells, AC or DC electrical power, or any other suitable power source. The tool  200  includes an air inlet  205 , a motor  210 , bumper  215 , clamp  220 , gear housing  225 , end bumpers  230 , end handle  235 , bottom rail  240 , bottom bumper  245 , screw shaft  250 , driver block  255 , mounting plate  260 , handle  265 , and an operating lever  270 . A reverse button (not shown) can be present on the opposite side of motor  210 . A side plate  305  (see  FIG. 3 ) can extend from bottom rail  240  to mounting plate  260  on both sides of the tool. This side plate can be opaque or transparent, and be made from a variety of materials such as, but not limited to, aluminum, fiber composites, steel or plastic. 
         [0020]    The bumpers  230  and  245  can be formed of a polymeric or plastic material, and function to protect the stator core during use of the tool  200 . Other materials could also be used for the bumpers, as long as they are relatively soft, in comparison to the material of the stator core. 
         [0021]    Handles  235  and  265  are used by the operator to aid in placing the tool  200  in position on the stator core, and in removing or repositioning the tool. Only one handle  235  is shown on one of the bumpers  230 , however, handles could be placed on each end bumper  230 , or multiple handles could be placed on one or both end bumpers. Handle  265  could also be mounted in a variety of positions and orientations on mounting plate  260 . Motor  210  can also be used as a handle, with proper care not to actuate the lever  270  inadvertently. 
         [0022]      FIG. 3  illustrates an exploded view of the tool  200 , in accordance with one embodiment of the present invention. Push block tip  310 , which is generally “T” shaped, is the element that makes contact with the stator slide  125 . Push block  312  is connected to the driver block  255 . Push block tip  310  is connected to push block  312  with removable fasteners, such as, screws or bolts. This enables push block tip  310  to be easily removed and/or exchanged with a push block tip having a different size, length, shape or configuration. In addition, elongated slots (not shown in  FIG. 2 ) can be formed in push block tip  310 . The elongated slots allow some variation in the placement of the fasteners relative to tip  310 , and this enables the distance the bottom of the “T” extends below the surface of the bottom bumpers  245 , to be adjusted and customized for the particular generator that is presently being serviced or manufactured. 
         [0023]    Driver block  255  rides on a rail  320  at its upper portion, and is driven by a screw shaft  250 , via push block  312 , at its lower portion. Driver block  255  is securely fastened or bonded to push block  312  and any movement experienced by the push block  312  is immediately transferred to driver block  255 . Screw shaft  250  is driven by motor  210  via gears  330 .  FIG. 3  illustrates a spur or linear gear arrangement, but any other suitable gearing arrangement could also be employed, including but not limited to, bevel, epicyclic, helical, or worm gears. A rack and pinion drive system could be used as well, and in this example the rack would take the place of the screw shaft. Gears  330  are typically manufactured from a steel or steel-alloy material, but other materials, such as, non-ferrous alloys, cast iron, iron alloys or even plastics could also be used. Gears  330  are contained within gear housing  225 . 
         [0024]    Motor  210  is preferably a pneumatic or air-powered motor, but other types of motors, capable of driving the gears  330  can also be employed. For example, motor  210  could be electrically powered via AC or DC voltage. Batteries or fuel cells could also be used to power motor  210 . However, in one of the currently described embodiments of the invention, the motor is pneumatic, and is powered from a compressed air source, such as, an air compressor (not shown). Air inlet  205  is used to couple the motor  210  to an air compressor via hoses suitable for transferring compressed air. 
         [0025]    With reference to  FIG. 4 , the stator core  100  has a plurality of stator slots  105 , generally extending in an axial direction, which contain the armature windings  110 . As one example, two armature windings  110  may be contained within each stator slot  105 . The stator core is comprised of many laminations of magnetic steel or iron material. The laminations form groups, and these groups are separated by spacers. The spacers define vent gaps  410 , which are generally orthogonal to the stator slots  105 . The vent gaps  410  between the groups of laminations allow for ventilation and cooling of the stator core. 
         [0026]    With reference to  FIGS. 4 and 6 , the armature windings  110  are housed in the lower portion of the stator slots  105 . Various filler strips  130  and ripple springs  135  may be installed above the armature windings. A dovetail wedge  120  is inserted into dovetail groove  115  and a slide  125  is subsequently driven under the wedge  120  using tool  200 . 
         [0027]    Vent slot plate  340  (see  FIG. 3 ) has a pair of downwardly extending projections  342 . The projections  342  extend into the vent gaps  410  and leverage the strength of the core to lock the tool in place during operation.  FIG. 3  illustrates a vent slot plate having two projections, but one or three or more projections could also be employed. By lock, it is to be understood that a solid point of contact is made to resist the drive force exerted while driving stator slides  125  under stator wedges  120 . Vent slot plate  340  is fastened to end frame cap  345  with removable fasteners, such as screws or bolts. The vent slot plate  340  is designed to be removed an exchanged with differently sized or dimensioned vent slot plates. By enabling the vent slot plate to be interchanged, a wide variety of generators can be accommodated and serviced with tool  200 . The main interchangeable items, for accommodating generators with different specifications (e.g., width of stator slot, width or length of vent gap, depth of stator slide, etc.) are bottom bumpers  245 , push block tip  310  and vent slot plate  340 . The size, width, length and other features of these elements can be tailored to the specific machine currently under repair, service or manufacture, so that tool  200  can be used with a wide variety of generators. Other elements of tool  200  may be interchanged as well to suit the specific requirements of various generators. 
         [0028]    A method for installing a stator slide  125  under a stator wedge  120  will now be described with reference to  FIG. 5 . The armature windings  110  are first installed within stator slot  105 . The filler strips  130  and ripple springs  135  may then be inserted into one or a group of stator slots  105 . A stator wedge  120  is then inserted into a portion of the dovetail groove  115  in a conventional fashion. The stator wedges  120  are axially disposed within the slots  105  and dovetail grooves  115 . The wedges  120  may be installed one at a time in a sequential fashion or in groups comprising multiple stator slots  105 . A stator slide  125 , which can have a slight taper at one end, is partially inserted under a stator wedge  120 . The tool  200  is then placed over the slide  125  and the vent slot plate projections  342  are aligned with and inserted into the vent slot  410 . The bottom bumpers  245 , which have projections extending downwardly as well, are aligned with and extend into the stator slot  105 . In this manner the tool  200  is automatically aligned in the proper manner, so that the stator slide  125  can be driven in line with the stator slot  105 . The tool  200 , so positioned, maintains the slide  125  in proper alignment and prevents the slide from “popping up” during the driving process. In the prior art hammering process, the slide  125  was subject to repeated “hits” and a common occurrence was that the slide  125  would start to vibrate and oscillate in a radial direction. This vibration could become pronounced and if the next blow from the hammer was miss-timed, the slide  125  could break. An advantage of tool  200  is that the slide is kept sandwiched between the tool and the ripple spring  135 , so that no excessive vibration occurs, and the slide is properly aligned during the entire driving process. 
         [0029]    The stator slide  125 , now positioned partially under stator wedge  120 , as shown in  FIG. 5 , with tool  200  directly above can be driven. The operator depresses lever  270  and causes push block tip  310  to be driven towards stator slide  125 . Push block tip  310  makes contact with stator slide  125  and forces the stator slide  125  under stator wedge  120 . The force exerted on stator slide  125 , by push block tip  310  is a consistent and uniform force. Typically the force exerted can be around 2,200 pounds force. However, the force can be adjusted to vary between 100 to 2,500 pounds force or more by properly adjusting the compressed air source. This variability in force is very useful when using the tool on different types of generators. 
         [0030]    As the stator slide  125  is forced under stator wedge  120 , the tool  200  is supported and braced, in the axial direction, by vent slot plate projections  342 , which make contact with the stator core portion in vent gap  410 . The stator core is very rigid and strong, and makes an excellent point of leverage during the driving process. When the stator slide  125  is fully driven under stator wedge  120  the operator can release the lever  270 , depress the reverse button (not shown) and depress lever  270  again. This withdraws the push block tip  310  from the stator slide  125  and enables the operator to remove the tool  200  and reposition it to a new location to drive the next stator slide. 
         [0031]      FIG. 7  illustrates an enlarged, partial perspective view showing tool  200  in place above the stator wedge  120  and stator slide  125 . Stator slide  125  is shown partially driven under wedge  120 . Push block tip  310  is shown contacting one end of stator wedge  125 . Ripple spring  135  can be seen under stator slide  125 , and the ripple spring has a wavy or undulating shape. These undulations are used to give the ripple spring its “spring like” characteristics, and function to keep all elements (e.g., stator wedge  120 , stator slide  125 , filler strips  130  and armature windings  110 ) tightly constrained within stator slot  105 . The ripple spring  135  also has resiliency to absorb fluctuations in armature winding dimensions caused by thermal expansion and contraction of the armature windings  110 . The vent slot plate projection  342  can be seen to project down into stator slot  105 . The stator core  100  is omitted from this figure for clarity, but it is to be understood that projections  342  make contact with the stator core and function to securely support tool  200  during the driving process. 
         [0032]    While the invention has been described in connection with what is presently considered to be one of the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.