Description:DESCRIPTION
“STRUCTURAL MEANS AND METHOD FOR ACCURATE MANUFACTURING OF LARGE SIZE TURBO GENERATOR SPRING”

FIELD OF THE INVENTION
[001] This invention relates to a structural means for obtaining great accuracy in manufacturing of springs of a large size turbo generator.
BACKGROUND OF THE INVENTION AND PRIOR ART
[002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[003] A Turbo generator is an electric generator connected to the shaft of a steam turbine or gas turbine for the generation of electric power. Rotor and stator are essential parts of a Turbo-Generator.
[004] Main components of stator are stator core and stator frame.
[005] Springs are used for mounting/suspension of stator core in stator frame and these are vibration/shock absorbing by nature. Due to suspension of stator core in stator through these springs, vibration of stator core during operation of machine is absorbed by these springs and is not directly transferred to stator frame and foundation.
[006] Manufacturing/machining of spring is essential for turbo generator manufacturing.
[007] Over time and during use of the dynamoelectric machine, if these springs are not machined with precise dimensional accuracy, there will be improper assembly of core in stator which will lead to tremendous increase in vibration in core, During operation of machine, these high vibrations can cause catastrophic failure in an electric generator. Such vibration in core is obviously undesirable and it is required that these springs are accurately manufactured without fault or err. The present method and means of manufacturing these springs are designed to minimize vibrations in core during operation of the machine, as a result of electrical and mechanical forces.
[008] The methods as per prior art included performing different operations on springs on plurality of manufacturing machines which not only resulted in expensive time delays in multiple job and related tool settings but also in transferring the said springs on different machine. Also, all these machines are required to be sequentially lined up to accommodate, without delay, these springs in their manufacturing schedule. Multiple job settings not only created operator fatigue but also reduced the job quality for obvious reasons well known to person skilled in the art.
[009] Thus, the prior art is associated with disadvantages such as poor manufacturing quality, high job setting time, high quality inspection time and low production efficiency.
[0010] It has been observed that through the use of a specially designed method as discussed herein through which not only it is desired to have to save significant time and with lesser resources to manufacture such springs with accuracy but also with means that makes this achievable with an arrangement having low initial cost and upkeep, great and continuing accuracy inherent in its design and operation, ruggedness and simplicity in its construction and operation, all to the ultimate end of faithfully and consistently reproducing in and through the desired quality of machining of said springs.
OBJECTS OF THE INVENTION
[0011] It is, therefore, the general object and purpose of present invention to provide structural means and associated method for machining springs of a large size turbogenerator, which obviates shortcomings of the prior art(s).
[0012] Another object of present invention is to provide structural means and associated method for machining springs of a large size turbogenerator, which provides enhanced ergonomics and reduced operator fatigue.
[0013] Still another object of present invention is to provide structural means and associated method for machining springs of a large size turbogenerator, which makes it possible that a number of operations are performed on single means to significantly reduce setting/machining time and expensive delays in machining of springs on different machines.
[0014] Yet another object of present invention is to provide structural means and associated method for machining springs of a large size turbogenerator, which makes it possible that a number of quality check operations like thickness checking, perpendicularity and parallelity checks are performed on single means to significantly reduce expensive delays in quality inspection of springs.
[0015] One another object of present invention is to provide structural means and associated method for machining springs of a large size turbogenerator on any available machine as the locking key in mentioned means can be custom made as per the width of T slot keyway of a particular machine bed.
[0016] Yet another object of present invention is to provide structural means and associated method for machining springs of a large size turbogenerator such that job spring can be transferred in under machining stage or complete machined along with invented means (while job i.e. spring is clamped on invented means) to any other machine or to free one machine to accommodate machining of any other critical job.
[0017] Still another object of present invention is to provide structural means and associated method for machining springs of a large size turbogenerator such that job i.e. spring can be properly and tightly clamped, and vibrations in job during machining can be drastically minimized and hence enabling machining of spring at much improved working parameters and use of most advanced cutting tools.
[0018] It is also an additional object of the invention to provide structural means and associated method for machining springs of the above character wherein the said means have minimum number of structurally durable parts cooperatively assembled in a compact organization and the said method is simple, economical, foolproof and inherently free from tendency to err or fall out of adjustment.
[0019] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.
SUMMARY OF THE INVENTION
[0020] One or more drawbacks of conventional systems and process are overcome, and additional advantages are provided through the apparatus/composition and a method as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be part of the claimed disclosure.
[0021] According to the invention, there is provided a Structural means (D) for obtaining accuracy in manufacturing of spring of large size turbo generator, the said means comprising of:
- a base plate 100 serving as base for the structural means;
- the base plate 100, top face of which is provided with at least two grooves 200 for holding ring 800, wherein depth of the groove 200 is maintained higher than height of protruded part 220 of ring 800 that the face 820 of the ring 800 butts with the top face of base plate 100;
- plurality of rectilinearly arrayed holes 240 disposed on corners of the base plate 100, locking key grooves 600 for fitment of locking keys 700 to lock rotational degree of freedom of base plate 100;
- threaded hole 610 at center of each key groove 600 for threadedly securing key 700;
- plurality of circularly arrayed holes 250 disposed around each groove 200 on top face of the base plate 100 so as to lock the ring 800 to the base plate 100;
- hole 210 at center of each groove 200 for lifting of proposed apparatus using eye bolts;
- plurality of clamp portions 500 with a peripheral through hole 510 and corresponding threaded holes 270 in the ring 800 to threadedly clamp spring from its top face;
- cutter paths 220 in base plate 100 to accommodate milling cutter depth in the base plate;
- plurality of counter holes 710 in ring 800 to clamp ring on the base plate 100.
Further, according to the invention there is provided a method of using said structural means comprising steps of:
- assembling locking keys 700 in key groove 600;
- securing base plate 100 in the T-slots on the flat planar top surface of machine table by locking means 700 and by threadedly affixing plurality of clamping element including T-bolts using hole 240;
- clamping ring over base plate 100 by snuggly fitting extruded portion 220 of ring 800 in the groove 200 of base plate 100 followed by threadedly fixing ring 800 using threaded bolts passing through counter holes 710 in ring 800 and accessing corresponding threaded holes 250 in base plate 100;
- inserting individual spring including inner bores in spring snuggly fits into rings 800 clamped over base plate 100 and base of spring butts with the top face of base plate 100;
- fastening clamp portions 500 over and across top surface of spring using plurality of threaded bolt that passes through holes 510 in and access corresponding threaded holes 270 in ring 800 that spring is held over top surface of base plate 100 upon tightening while other end of clamp portion 500 is rested on threaded support in threaded hole 260;
- performing machining operations on top surface of spring;
- turning spring upside down by unclamping clamp portion 500 and repeating the process to machine the opposite face.
[0022] According to another aspect of the invention, the depth of the grooves 200 is more than height of extruded part 220 of ring 800 that face 820 of ring 800 butts with top face of the base plate 100.
[0023] The grooves 200 inner diameter is as per outer diameter of extruded part 220 of ring 800 with very close tolerances that ring is inserted over the base plate 100.
[0024] The base plate 100 and ring 800 are made of material including alloy steel.
[0025] The threaded holes 210 are used by i-bolts to lift entire fixture for transportation among different machines.
[0026] The plurality of grooves 410 are configured on base plate 100 for quality check instruments including a Vernier Caliper/micrometer for measuring thickness of spring while machining and job clamping in associated means and to ensure production quality.
[0027] The diameter of the groove 200 is maintained that the protruded outer diameter 220 of ring 800 snuggly fits therein.
[0028] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.
[0029] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.
[0030] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0031] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and processes that are consistent with the subject matter as claimed herein, wherein:-
[0032] Figure 1 shows: Cross sectional view of a turbogenerator, with core inserted in stator;
[0033] Figure 2 shows: Arrangement of springs in stator frame;
[0034] Figure 3 shows: Insertion of core in stator frame;
[0035] Figure 4 shows: Core inserted in stator frame;
[0036] Figure 5 shows: Isometric view of the proposed apparatus base plate in accordance to the present invention;
[0037] Figure 6 shows: Top and bottom view of the proposed apparatus base plate in accordance to the present invention;
[0038] Figure 7 shows: Isometric view of the ring in accordance to the present invention;
[0039] Figure 8 shows: Top and bottom view of the ring in accordance to the present invention;
[0040] Figure 9 shows: Proposed apparatus having rings & keys assembled on base plate and clamps assembled on rings in accordance to the present invention;
[0041] Figure 10 shows: Proposed apparatus in which job is placed & secured according to the present invention;
[0042] Figure 11 shows: Illustrative view of spring according to the present invention.
[0043] The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAIL DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION WITH REFEENCE TO THE ACCOMPANYING DRAWINGS
[0044] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[0045] Before describing in detail, apparatus for accurate manufacturing springs of a large size turbogenerator, it should be observed that the present invention resides primarily in a novel and non-obvious combination of hardware elements and method steps. Accordingly, these elements and steps have been represented by conventional elements and steps in the drawings, showing only those specific details that are pertinent to the present invention so as not to obscure the disclosure with details that will be readily apparent to those skilled in the art having the benefit of the description herein.
[0046] The present invention makes a disclosure regarding a technology pertaining to invention on structural means and method for accurate manufacturing of large size turbo generator spring.
[0047] Referring now to figure 1 in detail, which illustrates a general construction of a turbogenerator stator, stator body 10 with inserted stator core 11.
[0048] Referring now to figure 2 in detail, which illustrates a general construction of a turbogenerator stator body 10, showing arrangement of springs T welded into inside face of stator frame. These springs support the weight of core and windings and absorb the vibrations in core assembly, during operation of machine.
[0049] Referring now to figure 3 in detail, which illustrates insertion of core 11 in stator body 10. It shows how springs T give support and take loads of core.
[0050] Referring now to figure 4 in detail, which illustrates inserted core 11 in stator body 10, in which the weight of core is supported on springs T.
[0051] However, power plant turbogenerators operate at 3000 rpm and under high centrifugal forces thereof, if these springs are not machined with precise dimensional accuracy, there will be misalignment in assembly of core in stator which will result in excessive vibration in core during operation of machine, which will be transmitted to stator body and foundation through springs, which can cause catastrophic failure in an electric generator. Such vibration is obviously undesirable and it is required that these springs are accurately manufactured without fault or err. To this end, the present invention proposes structural means D as shown in figure 5 comprising of a base plate 100 that primarily affixes with the standard machine table in a horizontal plane parallel to that of the machine table and perpendicular to vertical axis to hold spring.
[0052] As shown in figure 5 to 7, parallelepiped base plate 100, is made using alloy steel and having parallel top and bottom faces and keyway for locking means 600 on its bottom face. Locking key 700 is assembled into each keyway slot 600 and thus this extruded locking means 700 longitudinally sits in one of the T-slots of the machine table to lock rotational degree of freedom of base plate 100, plurality of holes 240 rectilinearly arrayed and disposed on corners of base plate 100 are used by plurality of clamping elements, generally T-bolts and corresponding nut, for threadedly securing base plate 100 to the flat planar top surface of said, not shown in figures, standard machine table. Because the shoulders of such T-bolts are made carefully plane, the T-bolts will project at right angles with respect to the base plate 100 axis to keep in a horizontal plane and is known to someone skilled in the art.
[0053] Further, the said base plate 100 is provisioned, on its top face, with circular grooves into which extruded part of ring 800 snugly fits.
[0054] The depth of circular groove 200 is selected in such a way that it ensures to accommodate extruded cylindrical collar of ring 800 in a way that bottom face of ring 800 butts with the top face of the base plate 100.
[0055] The inner diameter of circular groove is selected in such a way that it ensures snuggly fitting of extruded collar of ring 800 into it.
[0056] The ring 800 is clamped on top face of base plate 100.
[0057] The job (spring) is placed over top face of base plate 100, with at least two bores snuggly fitted into outer diameter of ring 800, so as to facilitate critical machining operations in spring such as thickness milling, radius milling, maintaining perpendicularity of faces.
[0058] The outer diameter of ring 800 is selected in such a way that it ensures snuggly fitting of inner diameter of job spring.
[0059] As shown in figure 9 and 10, once the base plate is secured in the machine table, the ring 800 is clamped over base plate and then spring is clamped over top face of the base plate 100.
[0060] After placing the spring over the base plate 100 as mentioned hereinabove, plurality of clamp portions 500 are threadedly used to clamp spring from top face. The said clamp portions 500 are fastened in a horizontal plane over and across spring as shown in figure 10 such that one end of clamp portions 500 partially overlaps and rests over protruding height H of top surface of spring, while the other end of said clamp portions 500 rests on a grub screw threadedly disposed to similar height H in corresponding threaded hole 260. A power screw such as a plurality of threaded bolt passes through holes 510 on clamp portion 500 and access corresponding threaded holes 270 in ring 800 such that tightening of said power screws adequately compresses spring to additionally secure, along with its bores snuggly fitted into outer diameter of rings 800, the said spring from rattling or from vibrations while it is subjected to various machining forces. It being imperative that the congruent surfaces between spring and top face of base plate 100 and outer dia. of ring 800 be free and clear of debris such as chips or cuttings.
[0061] Once all the milling operations on one surface of spring is completed, clamp portions 500 on top surface of spring are unfastened and spring is over turned and again clamped with opposite face B in a similar manner to repeat machining operation on surface B of spring.
[0062] To ensure that milling cutter does not hit base plate 100, it is imperative that depth of cutter paths 220 in such a way that that is accommodates the maximum diameter of milling cutter.
[0063] Plurality of grooves 410 on base plate 100 lateral to base plate axis are configured in order to provide an approach for quality check instruments such as a Vernier Calliper or micrometer for measuring thickness of spring and to ensure production quality.
[0064] The structural means as described hereinabove shall be really useful in accurately machining these critical parts as springs in which thickness is to be made in very close tolerances and perpendicularity and parallelism is to be stringently checked and are highly prone to dimensional inaccuracy and issues such as spring bending, improper perpendicularity, improper parallelism if not held rigidly during machining.
[0065] The present invention proposes a mechanism to lock and prevent any movement of jobs during machining by rigidly holding the same.
[0066] Further, it will be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its scope.
ADVANTAGES OF INVENTION
-Provides enhanced ergonomics and reduced operator fatigue;
-Reduction of setting/machining time and expensive delays in machining of springs on different machines;
-Reduction of expensive delays in quality inspection of springs;
-Job spring can be transferred in under machining stage or complete machined along with invented means to any other machine or to free one machine to accommodate machining of any other critical job;
-Vibrations in job during machining can be drastically minimized and hence enabling machining of spring at much improved working parameters and use of most advanced cutting tools;
-Means has minimum number of structurally durable parts cooperatively assembled in a compact organization;
-The method is simple, economical, foolproof and inherently free from tendency to err or fall out of adjustment.
TEST RESULT

Reduction in cycle time – approx. 81.25 percent.
Reduction in rejection – Remarkable nearly 100 percent in one embodiment
Reduction in rework – Remarkable nearly 100 percent in one embodiment

[0067] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0068] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.
[0069] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particulars claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogues to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B”.
[0070] The above description does not provide specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.
[0071] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[0072] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[0073] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims. , Claims:We Claim:
1. A Structural means (D) for obtaining accuracy in manufacturing of spring of large size turbo generator, the said means comprising of:
- a base plate 100 serving as base for the structural means;
- the base plate 100, top face of which is provided with at least two grooves 200 for holding ring 800, wherein depth of the groove 200 is maintained higher than height of protruded part 220 of ring 800 that the face 820 of the ring 800 butts with the top face of base plate 100;
- plurality of rectilinearly arrayed holes 240 disposed on corners of the base plate 100, locking key grooves 600 for fitment of locking keys 700 to lock rotational degree of freedom of base plate 100;
- threaded hole 610 at center of each key groove 600 for threadedly securing key 700;
- plurality of circularly arrayed holes 250 disposed around each groove 200 on top face of the base plate 100 so as to lock the ring 800 to the base plate 100;
- hole 210 at center of each groove 200 for lifting of proposed apparatus using eye bolts;
- plurality of clamp portions 500 with a peripheral through hole 510 and corresponding threaded holes 270 in the ring 800 to threadedly clamp spring from its top face;
- cutter paths 220 in base plate 100 to accommodate milling cutter depth in the base plate;
- plurality of threaded holes 250 to clamp ring on the base plate 100.
2. A method of using said structural means as claimed in claim 1 comprising steps of:
- assembling locking keys 700 in key groove 600;
- securing base plate 100 in the T-slots on the flat planar top surface of machine table by locking means 700 and by threadedly affixing plurality of clamping element including T-bolts using hole 240;
- clamping ring over base plate 100 by snuggly fitting extruded portion 220 of ring 800 in the groove 200 of base plate 100 followed by threadedly fixing ring 800 using threaded bolts passing through counter holes 710 and accessing corresponding threaded holes 250 in base plate 100;
- inserting individual spring including inner bores in spring snuggly fits into rings 800 clamped over base plate 100 and base of spring butts with the top face of base plate 100;
- fastening clamp portions 500 over and across top surface of spring using plurality of threaded bolt that passes through holes 510 in and access corresponding threaded holes 270 in ring 800 that spring is held over top surface of base plate 100 upon tightening while other end of clamp portion 500 is rested on threaded support in threaded hole 260;
- performing machining operations on top surface of spring;
- turning spring upside down by unclamping clamp portion 500 and repeating the process to machine the opposite face.
3. The Structural means and method as claimed in claim 1 or 2, wherein the depth of the grooves 200 is more than height of extruded part 220 of ring 800 that face 820 of ring 800 butts with top face of the base plate 100.
4. The Structural means and method as claimed in claims 1-3, wherein the grooves 200 inner diameter is as per outer diameter of extruded part of ring 800 with very close tolerances that ring is inserted over the base plate 100.
5. The Structural means and method as claimed in claims 1-4, wherein the base plate 100 and ring 800 are made of material including alloy steel.
6. The Structural means and method as claimed in claims 1-5, wherein the threaded holes 210 are used by i-bolts to lift entire fixture for transportation among different machines.
7. The Structural means and method as claimed in claims 1-6, wherein plurality of grooves 410 are configured on base plate 100 for quality check instruments including a Vernier Caliper/micrometer for measuring thickness of spring while machining and job clamping in associated means and to ensure production quality.
8. The Structural means and method as claimed in claims 1-7, wherein the diameter of the groove 200 is maintained that the protruded outer diameter 220 of ring 800 snuggly fits therein.