RU2530014C1 - Lock member of large electric machine stator - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: lock member preventing fastening nuts from self-unscrewing at the deformation and vibration of a core is installed at the threaded ends of longitudinal keybars of the core behind the end plates under the fastening nuts. The element comprises a thin-walled ring with the outer diameter being greater than the fastening nut diameter, its protruding part is folded onto the edge of the fastening nut. The ring body is fitted by a local protrusion and a locking "socket" in the end plate under the fastening nut with the protrusion being set in the "socket". The ring is mounted behind the fastening nut, is increased by its thickness at least up to the half of the fastening nut thickness. The ring is also fitted by a local protrusion at the end face on the side of the hole eccentricity and on the side turned to the fastening nut. The area of the protrusion amounts to 1/4 of the area of the cut-off ring on the side turned to the fastening nut by oval grooves with designed depth outside along the side surface symmetrically to the slot. The ring is also fitted by two passage holes and a clamping bolt with a nut and a lock washer.

EFFECT: improved clamping of keybar thread without increase of a lock member size, its improved reliability and fabricability.

4 cl, 6 dwg

Description

The invention relates to the field of electrical engineering and for fastening the stator core of large electrical machines, such as turbogenerators.

Known designs of the stators of electric machines, in which the core is sewn onto longitudinal coupling ribs with threaded ends, axially pressed using powerful pressure plates and pressure fingers, is locked from movement by fixing nuts, and the locking nuts are locked by ring lock washers with protrusions that are located in the slots of the pressure plates under the fixing nuts of the stator core ("Turbogenerators. Damage and repair." SI Hazan. M .: "Energy" 1971, "Turbogenerators. Calculation and design I am. "Vladimir Titov, GM Khutoretsky et al., ed. N. Ivanov and R. Luther. L .:" Energy ", 1967).

Known designs for locking fastening nuts with one-piece joints by welding to a pressure plate, for example, a corner that abuts against one of the faces of the nut.

The disadvantage of the design with lock washers is the gradual unfastening of the fixing nuts during operation of the machine due to relaxation of the varnish film of the segments, shrinkage and "trimming" of the stator core. In this case, the insertion force of the core is reduced, the tightening of the fastening nuts is weakened, and the variable electrodynamic effects from the magnetic fields of dispersion and the forces from thermal expansions and vibration of the core gradually bend or crush the protrusions in the lock washers of the nuts, some of the fastening nuts are rotated, the pressing of the sheets of the electrical steel core is weakened more, which already leads to more intense wear of the varnish film, damage to the housing insulation of the stator winding by the edges of the segments, breakdown of the insulator tion rods and failure. Considering also that during the operation of the turbogenerator, the magnetic field of the rotor creates significant electrodynamic forces acting on the core, which manifest themselves as an “ellipse running around the circumference of the core”, i.e. there is a continuous temporary deformation of the core and all its fastening elements, and therefore there is a need for a more reliable locking of the fastening nuts.

Locking the fixing nuts with the help of angle welding complicates the tightening of the fixing nuts of the core when the turbogenerator stops for scheduled preventive maintenance.

Also known are designs of locking elements that are used in other branches of technology, for example, in mechanical engineering. This is the so-called split type lock nuts, having additional protrusions with holes on both sides of the cut, a coupling bolt and an additional blind slot along the inside diameter opposite the through cut, or ordinary split lock nuts, in which the through and threaded holes for the coupling bolt are made directly in the body nuts (Pat. US 439660 dated 04.11.1890, Pat. US 1097218 dated 05/19/1914, Pat. US 4033394 from 07/05/1977, Pat. JP 2002081416 from 03/22/2002).

The use of such locking elements in electrical engineering, for example, in turbogenerators, is impossible without the necessary modifications due to the low compression efficiency of the prism thread, since a large friction force arises between the locking element and the fastening nut, which significantly reduces the compression force of the prism thread locking element.

To increase the compression force of the prism thread, it will be necessary to increase the dimensions of the split nut, the coupling bolt and, accordingly, the length of the threaded part of the prism and change its shape. All this leads to an increase in the dimensions of the stator.

The basis of the invention is the task of improving the design of the locking element of the stator core in such a way as to increase the compression force of the threads of the prisms without increasing its dimensions, as well as to ensure that the design is technological, maintainable and reliable.

The problem is solved in that the locking element of the stator of a large electric machine located on the threaded ends of the longitudinal coupling prisms of the core behind the pressure plates under its mounting nuts, preventing them from unscrewing during deformation and vibration of the core, containing a thin-walled ring with an outer diameter larger than the diameter of the fixing nut, the protruding part of which is bent to the edge of the nut; the local protrusion on the body of the ring and the locking "socket" in the pressure plate under the fastening nut in which the protrusion, in accordance with the invention, is located, in order to increase the safety of the locking, said ring is located behind the fastening nut, increased in thickness to at least half the thickness mounting nut, and the hole is offset to the edge by half of its radius and processed as a split lock nut, while on the outside from the slot side, the ring is cut from 3 sides along the chords in the shape of a clamp and a wrench and additionally Abzheno: local protrusion at the end from the side of the eccentricity of the hole and from the side facing the mounting nut, and the area of the protrusion is ¼ part of the area of the trim ring from the side facing the mounting nut; oval grooves of the estimated depth, symmetrically cut through the outside on the side surface; two through holes; a coupling bolt with a nut and a lock washer with a square head and a sphere at the interface with the passage hole; recesses for the bolt head, nut and washer, made of different depths and lengths; oblique cuts from the end from the side of the through slot; conical bore at the interface between the sphere of the bolt and the hole.

A comparative analysis of the proposed locking element with the prototype allows us to conclude about its novelty and effectiveness, because the friction force between the fastening nut and the trimming ring is practically absent when tightening its split part, and the compression force of the prism thread is significantly increased, which contributes to the reliable locking of the fastening nut.

The fixing nut will no longer be able to break the thread of the locking element and with it unscrew from the threaded part of the prism and fall onto the stator winding. The elastic steel of the trimming ring will allow you to use it when locking repeatedly. To improve the flexibility of the cut part of the trim ring and maintain the integrity of its thread during compression of the thread of the prism on the outside, oval grooves of the calculated depth are made on the side surface. Since when tightening the bolt with the nut of the platform under the bolt head and nut, they go away from parallelism and the total force from tension and bending acts on the bolt head, there is a possibility of destruction, tearing of the head, which is fraught with an accident, because a severed head can get on the stator winding and damage the core insulation. To reduce mechanical stresses in the aforementioned connection, the head is made spherical, that is, a hinge is introduced to eliminate the head misalignment.

The foregoing is illustrated by the drawings. Figure 1 shows a longitudinal section of the stator of a turbogenerator; figure 2 - remote element A "locking the fixing nut"; figure 3 is a section bb In figure 2; figure 4 - the pairing of the locking element with a fixing nut, where the protrusion on the trim ring and the gap formed between the ring and the fixing nut; figure 5 shows a trimming ring, a graphical construction; Fig.6 - remote element G, the installation of a bolt in a split nut, shows a sphere on the head and a counter chamfer in the nut.

The stator core 1 is laced with segments of electrical steel 2 onto the longitudinal coupling prisms 3 of the core frame 4. After the segments are lined, the core is pressed onto the umbrella press through the pressure plates 5 and pressure fingers 6.

Under pressure from the press, washers 8 and fixing nuts 9 are installed on the threaded ends 7 of the coupling prisms 3, which are tightened with a wrench. After the final tightening of the fastening nuts, the locking elements 10 are installed with the protrusions 11 facing the fastening nuts 9. The trimming rings 12 of the locking elements 10 are also tightened with a wrench until the protrusions 11 are tightly attached to the end surface of the fastening nuts 9. After installing the trimming rings 12, the fastening bolts 13 are installed , lock washers 14 and nuts 15. The bolts 13 are installed so that the bolt head face 16 is located on the side of the recess wall 17, since when tightening the nut 15, the bolt will slightly turn and he rested in the angle of the edge wall of the recess 17, ie, self-locking bolt. The washer 14 is pre-bent before installation and the bent portion is placed in the gap 18. After tightly tightening the nuts 15, the trim parts of the rings 19 and 20 converge to each other and their planes under the bolt head and nut lose parallelism, but the spherical part of the bolt head 13 slides along the conical bore 21, occupying a stable position with support around the entire circumference of the sphere, eliminating undesirable additional forces on the bolt head. In this case, the bolt 13 only works in tension. The friction of the movable parts of the trim ring 12 against the end surface of the nut 9 is practically absent, which allows the thread of the ring to smoothly compress the thread 7 of the prism 3. This is facilitated by oval grooves 22, made on the side surface of the ring of the estimated depth.

By lightly tapping the hammer on the side surface of the ring, the density of the thread 24 of the ring to the thread 7 of the prism 3 is determined by the nature of the sound (deaf or sonorous). From the slot side, the tightness of the thread is controlled using the probe from the side of the oblique sections 23 of the ring. In the case of a loose fit, the locking element is removed and the depth of the oval grooves 22 is adjusted and adjusted at the desired location. After tightening the locking elements 10, their nuts 15 are locked with washers 14, bending the free sides on the verge of nuts.

As can be seen from the description and drawings, with all the above improvements, the dimensions of the locking element do not increase the dimensions of the machine. The proposed design simplifies the assembly of the stator core during its manufacture (previously it was time-consuming work when bending a thin ring onto the face of the nut due to difficult access, since the fixing nut and retaining ring were recessed in the deep bore of the pressure plate) and the process of tightening the loose fixing nuts in operation when the turbogenerator is stopped for scheduled preventive inspection.

Claims (4)

1. The locking element of the stator core of a large electric machine, such as a turbogenerator, mounted on the threaded ends of the longitudinal coupling prisms of the core behind the pressure plates under the mounting nuts, preventing them from unscrewing during deformation and vibration of the core, containing a thin-walled ring with an outer diameter larger than the diameter of the mounting nut, protruding part of which is bent to the edge of the fixing nut; the local protrusion on the body of the ring and the locking "socket" in the pressure plate under the fastening nut, in which the protrusion is located, characterized in that in order to increase the reliability of the locking, said ring is located behind the fastening nut, increased in thickness to at least half the thickness of the fastening nuts, and the hole is offset to the edge by 1/2 of its radius and processed as a split lock nut, while on the outside on the side of the slot, the ring is cut from three sides along the chords in the shape of a clamp and a wrench and is additionally equipped with: m protrusion at the end from the eccentricity of the hole and from the side facing the fastening nut; moreover, the protrusion area is ¼ part of the area of the trimming ring from the side facing the fastening nut with oval grooves of the calculated depth from the outside along the side surface symmetrically of the slot; two through holes; a coupling bolt with a nut and a lock washer with a square head and a sphere at the interface with the through hole, to which the sphere of the bolt adjoins; recesses for the bolt head, nut and washer, made of different depths and lengths; oblique cuts from the end from the side of the through slot; conical bore at the interface between the sphere of the bolt and the hole. 2. The locking element according to claim 1, characterized in that the fixing nut on the side of the locking element is provided with a cylindrical groove made at the location of the lock washer of the coupling bolt so that the groove does not interfere with the free installation of the lock washer. 3. The locking element according to claim 1, characterized in that the said ring is made of elastic steel, and the coupling bolt is made of high strength steel, for example, steel 40X. 4. The locking element according to claim 1, characterized in that the height of the protrusion on the edged end must be optimal and guarantee the free movement of the moving parts of the edged ring when tightening the nut of the coupling bolt.

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