Claims:WE CLAIM:
1. Uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center comprising a guide ring (1) mounted on machine spindle (S) and supports a clamping ring (2), which transmits torque/cutting force to cutter (200) accommodated in spindle cone (4), wherein the clamping ring (2) is secured to the guide ring (1) by means of a fastener (3).

2. The uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center as claimed in claim 1, wherein the clamping ring is having two segments clamped on the guide ring with the help of the fastener including a screw.

3. The uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center as claimed in claim 1 or 2, wherein said clamping ring segment is placed on the guide ring such that angle a deg & ß deg of the clamping ring touches the same angle in the guide ring and ? deg touches the flank in the tool holder.

4. The uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center as claimed in any of the preceding claims, wherein when the screw (3) is tightened, the clamping ring slides through the angle a & ß and moves in lateral direction and provides a clamping force on the cutter flank.

5. The uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center as claimed in any of the preceding claims, wherein the outer diameter of the guide ring is same as the diameter of the machine spindle and said guide ring is integrally provided with key.

6. The uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center as claimed in any of the preceding claims, wherein the angle a & ß deg are provided on the guide ring on which the clamping ring (2) rests.

7. The uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center as claimed in any of the preceding claims, wherein a plurality of holes having dimension H are provided in the guide ring so as to clamp on the machine spindle & multiple holes having dimension of H2 are provided in the guide ring for clamping ring (2).

8. The uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center as claimed in any of the preceding claims, wherein the diameter D3 of the clamping ring (2) is greater than the shank diameter of the cutter.
9. The uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center as claimed in any of the preceding claims, wherein angles a & ß of the clamping ring are same as the angles of the guide ring (1), in which multitude of holes H3 are provided in the clamping ring so as to clamp the clamping ring on the guide ring (1).

10. The uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center as claimed in any of the preceding claims is associated with the advantageous features such as herein described.
, Description:Uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center
FIELD OF INVENTION
[001] The present invention is related to uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center. It enhances rigidity of tool clamping on existing horizontal milling machine spindle for uniform distribution of clamping & cutting force. More particularly, the present invention is related to a device which is capable to distribute the load uniformly during clamping of self-holding taper tools on spindle of horizontal machining center and also to prevent the wear in machine’s spindle cone leading to inaccuracies in machining as well as replacement of the cone.

BACKGROUND/PRIOR ART

[002] Steam Turbine broadly consists of 3 modules, namely High Pressure (HP), Intermediate Pressure (IP) and Low Pressure (LP) module.

[003] High volume of steam at low pressure & temperature passes through last stages of LP module of steam turbine. To accommodate this high volume of steam the size of these stages blades is quite long with free standing end. In order to accommodate these long and heavy blades, perfect fitting of blade in groove of the LP Rotor is required for the safety of turbine running at very high rpm under actual working conditions.

[004] In case of LP Rotor shaft, curved fir-tree shaped grooves (201) (as illustrated in Fig-1) are machined on horizontal machine center for fitting of aforesaid blades, using full form fir-tree shaped milling cutter (200) (as illustrated in Fig-2). These cutters are employed on a curved profile path for machining of these grooves so as to achieve profile & shape of grooves as per design accuracies.

[005] The geometrical & dimensional accuracies of required machining for these grooves are very stringent. The firtree profile of required accuracies, as available on the cutter, need to be generated on the groove of the rotor by machining. However, the measurement or verification of machined dimensions of the groove following complete machining is not feasible due to complicated shape & accessibility constraints.

[006] In view of the above, it is of utmost importance to have machining free from vibrations, chattering and deflection of cutter to get smooth and accurate machined surface. Perfect contact of load bearing surfaces of groove with matching surfaces on the blade root need to be ensured during blade fitting so as to meet design requirements. The machining starts from one end of the curved path and relieves at other end. With repetitive movement of cutter having full contact of cutter profile at full cutting load tends the cutter to deflect owing to non-uniform cutting forces and thus, creates inaccurate surface as well as cause wear in machine’s spindle cone leading to further inaccuracies.

[007] Therefore, rigid clamping of cutter with machine’s spindle ensuring uniform diametric distribution of cutting load on the cutter is of paramount relevance & importance. There should not be any play between spindle cone & taper of the cutter’s shank/adapter. Load, during machining operation, should be uniformly distributed on machine spindle cone surface.

[008] The process of machining of fir-tree grooves in LP rotor using full form firtree milling cutter with its rigid clamping & uniform distribution of cutting load is very critical in order to achieve following results.

a) Geometrical tolerances, positional accuracy & required assembly conditions according to the design needs.
b) Maximum process reliability at high cutting forces and material removal in the course of machining.
c) Low & consistent cutting load on machine’s spindle cone.
d) High accuracy in the position & shape of the fir tree groove.
e) Designed flow path of blades to be used on LP rotor.
f) Recommended natural frequency of blades to be used on LP rotor.

[009] According to known art, full-form firtree milling cutter is directly mounted on the spindle cone of machine. For the same, reference may be made to figure 3, wherein the cutter is clamped on machine’s spindle. Self-holding taper (T) of cutter is inserted in the cone of spindle (4). Cutter is pulled in the cone cavity with the help of pull stud (5). Required machining force/torque is transmitted with the help of keys (K) mounted on the machine spindle (S). However, the drawbacks associated with the above provision can be discussed hereinunder.

[0010] As curved path that cutter follows is unidirectional, cutting load is unevenly distributed, due to which spindle cone deforms in one direction. Hence, after some time, there is wear on the spindle cone due to which there comes a play between spindle cone and taper of cutter’s shank leading to inaccurate machining. As a result of this, it is difficult to achieve positional & geometrical accuracies of fir tree groove. Further, spindle cone is frequently required to be replaced with new spindle cone to meet the process requirements.

[0011] Hence, there was need of an alternative which can address afore-discussed issues of the prior art(s) and could be mounted on the cutter mounting system to ensure uniform distribution of cutting load. This in turn can prevent the wear of spindle cone and its frequent replacement thus, resulting in accurate & trouble-free machining, financial saving against avoidance of frequent replacement of spindle cones & rework as well as enhancing the capability of existing machine to take up required machining without any constraint.

OBJECTS OF THE INVENTION

[0012] The object of the present invention is to provide uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center which obviates shortcomings of the prior art(s).
[0013] Another object of the present invention is to provide uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center which results in enhanced capability of the machine as well as quality of machining at reduced cost.

[0014] Still another object of the present invention is to provide uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center which can be clamped on existing machine spindle.

[0015] Yet another object of the present invention is to provide uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center which can achieve more consistent cutting forces at high material removal rate.

[0016] Further object of the present invention is to provide uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center which can minimize wear/replacement of the spindle cone.

[0017] Still further object of the present invention is to provide uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center which is portable and light in weight, easily mountable and rigid enough to sustain the machining forces while using on horizontal milling machine.

SUMMARY OF THE INVENTION

[0018] According to the invention, there is provided uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center comprising a guide ring mounted on machine spindle(S) and supports a clamping ring, which transmits torque/cutting force to cutter accommodated in spindle cone, wherein the clamping ring is secured to the guide ring by means of a fastener.

[0019] The clamping ring is having two segments clamped on the guide ring with the help of the fastener including a screw.

[0020] Said clamping ring segment is placed on the guide ring such that angle a deg & ß deg of the clamping ring touches the same angle in the guide ring and ? deg touches the flank in the tool holder.

[0021] The screw is tightened, the clamping ring slides through the angle a & ß and moves in lateral direction and provides a clamping force on the cutter flank.

[0022] The outer diameter of the guide ring is same as the diameter of the machine spindle and said guide ring is integrally provided with key.

[0023] The angle a & ß deg are provided on the guide ring on which the clamping ring rests.

[0024] A plurality of holes having dimension H are provided in the guide ring so as to clamp on the machine spindle & multiple holes having dimension of H2 are provided in the guide ring for clamping ring.

[0025] The diameter D3 of the clamping ring is greater than the shank diameter of the cutter.

[0026] Angles a & ß of the clamping ring are same as the angles of the guide ring, in which multitude of holes H3 are provided in the clamping ring so as to clamp the clamping ring on the guide ring.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0027] Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings of the exemplary embodiments and wherein:-

Fig. 1 shows: The rotor groove arrangement.
Fig. 2 shows: The form cutter to be used in machining of rotor groove.
Fig. 3 shows: Provision according to prior art.
Fig. 4 shows: Uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center according to present invention.
Fig. 5 shows: Guide ring in accordance with the invention.
Fig. 6 shows: Clamping ring of present invention.

DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS OF PREFERRED EMBODIMENTS

[0028] The present invention is pertinent to uniform load distribution device for rigid clamping of cutter on spindle of horizontal machining center. Now, reference may be made to figure 1 illustrating rotor groove arrangement. Form cutter (101) enters from the side of rotor groove and follows the curved path (102). Machining of the groove is carried out in downward direction on a curved path, wherein rotor groove profile is shown in the fig. 1.

[0029] Now referring to Fig. 2 showing the form cutter (200) to be used in machining of rotor grooves (201, Fig.1). Shape of the grooves/stations machined in the rotors is corresponding to cutter profile.

[0030] The invention lies in the design of a load distribution device for rigid clamping of cutter and uniform distribution of cutting load on spindle of horizontal machining center. Said device as best seen in figure 4 includes a guide ring (1) clamped on the machine spindle using key slot on the spindle(S) in such a manner that it provides the guide/clamping base to the clamping ring (2) and also transmits the required torque/cutting force to the cutter. The clamping ring (2) is having two segments clamped on the guide ring (1) with the help of fastener including a screw (3). Said clamping ring segment is placed on the guide ring in such a manner that angle a deg & ß deg touches the same angle in the guide ring and ? deg touches the flank in the tool holder. When the screw (3) is tightened, the clamping ring slides through the angle a & ß and moves in lateral direction and provides a clamping force on the cutter flank. As a result, this cutter is pushed in the cone cavity (4) and at the same time a uniform radial support is also provided on the cutter shank.

[0031] Now, reference may be made to Fig. 5 showing particulars of the guide ring (1). The outer diameter of the ring is same as the diameter of the machine spindle. Said guide ring is integrally provided with key having dimensions of WxL. Angle a & ß deg are provided in the ring on which the clamping ring (2) rests. A plurality of holes having dimension H are provided in the guide ring so as to clamp the same on the machine spindle & multiple holes having dimension of H2 are provided in the guide ring for clamping ring (2).

[0032] Fig.6 shows the clamping rig (2) divided in two equal segments for easy installation. Diameter D3 of the ring (2) is greater than the shank diameter of the cutter. Angles a & ß deg of the clamping ring are the dimensionally same angle as of the guide ring (1) and multitude of holes H3 are provided in the clamping ring so as to clamp the clamping ring on the guide ring (1).

Operation of present invention (Fig. 4)

[0033] Firstly, the guide ring (1) is placed on the face of machine spindle and clamped with the help of screw. Thereafter the cutter is inserted in the spindle cone cavity (4). Clamping ring (2) segments are now clamped on the guide ring. As the screw (3) is tightened the clamping ring (2) slides on the angle provided on the guide ring (1). Now the tool clamping system of the machine starts working & cutter is pulled in the cone cavity (4) with the help of pull stud (5). Further tightening of screws and clamping ring segments lead to a rigid clamping on the shank of the cutter (200).

[0034] Advantageous Features: -

- provides uniform load distribution for rigid clamping of cutter on spindle of horizontal machining center,
- enhanced capability of the machine as well as quality of machining at reduced cost,
- can be clamped on existing machine spindle,
- consistent cutting forces on machine’s spindle at high material removal rate,
- minimizes wear & need for replacement of the spindle cone,
- portable and light in weight,
- easily mountable and rigid enough to sustain the machining forces while using on horizontal milling machine,
- facilitates to achieve geometrical tolerances, positional accuracy & required assembly conditions as per the design needs,
- renders the invention reliable at machining conditions of high cutting forces and material removal,
- lowers cutting load on machine’s spindle cone.

[0035] 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”.

[0036] It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-