Claims:1. A system (101) for testing performance of high speed integrated motor spindle, the system (101) comprises:
an electrical cabinet (1);
plurality of digital displays (8, 9, 10, 11, 12 and 13) provided at the top of front side of the electrical cabinet (1)
a digital insulation tester (14) provided below the digital display (11) at the front side the electrical cabinet (1);
plurality of selector switches (16, 17, 18, 19, 20 and 21) provided below the plurality of digital displays (8, 9, 10, 12 and 13);
an encoder testing device (15) provided at the bottom-left side of the electrical cabinet;
plurality of operational push-buttons (2) provided below the digital insulation tester (14) at the right of front side of the electrical cabinet (1), and;
a feed rate potentiometer (28) installed on bottom right side of the electrical cabinet (1),
wherein the digital insulation tester (14) tests insulation of motor spindle in offline testing mode through selector switch (16),
wherein the system () tests performance of high speed integrated motor.
2. The system (101) as claimed in claim 1, wherein the electric cabinet (1) further comprises of a filter module (3), a HF communication choke (4), an in-feed regenerative feedback module (5), a power module (6), a universal controller card (7), a surge arrestor, a pre-assembled encoder cable and a motor power cable.
3. The system (101) as claimed in claim 1, wherein the digital display (8) is provided to check motor speed.
4. The system (101) as claimed in claim 1, wherein the digital display (9) is provided to check motor current.
5. The system (101) as claimed in claim 1, wherein the digital display (11) is provided to check tool clamp/ unclamp feedback for voltage sensor.
6. The system (101) as claimed in claim 1, wherein the digital display (12) is provided to check tool clamp/ unclamp feedback for current sensor.
7. The system (101) as claimed in claim 1, wherein the digital display (13) is provided to check bearing temperature.
8. A method (200) for testing performance of high speed integrated motor spindle, the method (101) comprises:
installation (110) of repaired mechanically assembled spindles on a testing stand;
run-out checking (111) on the testing stand;
testing (112) of insulation of motor spindle through selector switch (16) with the help of digital insulation tester (14);
selecting (113) the online testing mode through selector switch (16) and open loop feedback through selector switch (17);
mounting (114) of an encoder (32) in the motor spindle () in front of encoder wheel (34);
connecting (115) the encoder feedback cable with the encoder testing device (15) through connector (35);
selecting (116) spindle though selector switch (19) for parameter set changeover;
checking (117) the spindle clamping force from 18KN to 21KN, and;
performing (118) performance validation test by selecting required parameters.
9. The method (200) as claimed in claim 8, wherein the run-out checking 111 of the high speed motor spindle is carried out by carrying out run-out check of spindle taper (29), run-out check of spindle face (30) and run-out check of arbour (31) in spindle at 300mm.
, Description:A system and process for testing performance of a high speed integrated motor spindles
FIELD OF INVENTION
[001] The present invention in general relates to a test control system and process for performance validation of high speed integrated motor spindles. In particular, the present invention relates to a system and process for testing performance of new, repaired or reconditioned high speed integrated motor spindles.
BACKGROUND OF THE INVENTION
[002] Machine tool spindles basically fulfill two tasks, one, to rotate the tools (drilling, milling and grinding) or work piece (turning) precisely in space and, two, to transmit the required energy to the cutting zone for metal removal. Obviously, spindles have a strong influence on metal removal rates and quality of the machined parts.
[003] Facilities world-wide use five axes interpolating machining cells for manufacturing of complex job profiles wherein such machines use high speed motor (HSM) spindles for best cutting performance and cutting speed. Manufacturers are constantly looking for various ways and means to improve the productivity of machine tools through improved power densities, higher speeds, greater flexibility and more multitasking of operations. A spindle plays a vital role in the quality of the final product and enhances the overall productivity and efficiency of the machine tool itself.
[004] Contrary to most of rotating machines, a large variety of force spectra is applied to a milling spindle during its lifetime. Indeed, many machining operations are carried out, with different tools (number Z), various tool profiles and various cutting conditions (spindle speed, width of cut, etc.).
[005] A high speed machining requires high speed and high power spindles to obtain high quality and productivity. One of the most critical applications for the spindle concerns the manufacturing of steam turbine blades made of high chrome steel alloy. Indeed, high material removal rates required during the long rough milling operations, leading to high power and force transmitted to the spindle bearing.
[006] Besides, very high cutting speed, i.e. shaft speed, is used, In this way, HSM spindle is an extremely critical bearing application. It is highlighted by the dm.N criterion (product of bearing mean diameter, in mm, and shaft speed, in rpm) that can reach 3,000,000 for HSM spindles; versus less than 500,000 for classical bearing applications.
[007] The High Speed Machining requires high speed and high power spindles to obtain high quality and productivity. One of the most critical applications for the spindle concerns the manufacturing of steam turbine blades made of high chrome steel alloy. Indeed, high material removal rates required during the long rough milling operations, leading to high power and force transmitted to the spindle bearing
[008] The motorized spindle vibration is inevitable during machining, which not only changes the relative position of work pieces and machining cutters to influence the machining accuracy, but also accelerates the wears of cutter, further influencing the machining accuracy. For high speed machine tools with high accuracy, the influence of vibration is even more serious.
[009] After the shaft of the spindle rotates for certain time, the axial deflection in spindle end position gets increased.
[0010] Due to high ratio of ‘power to volume’ active cooling is often required, which is generally implemented through water based cooling. The coolant flows through a cooling sleeve around the stator of the motor and often the outer bearing rings. Often during service, numerous issues can affect the required rate of cooling thereby affecting manufacturing execution.
[0011] The machining load may result in wear of a tool fitting hole of the spindle, breakage of a collet and Belleville springs for clamping a tool and wear and tear of the bearings. In most cases, the breakdown of the spindle appears in the spindle itself i.e. within the spindle or in the bearings.
[0012] In addition to various issues that can occur to a high speed motorized spindle as stated above, there are other problems as well which are frequently observed such as: High spindle radial & axial run-outs leading to rework and rejection of the jobs; Tool not getting correctly and rigidly clamped, clamping unit worn or damaged; Tool cannot be released, tool holder () getting stuck/jammed; Tool released during operation; Spindle vibration; Setup fault is displayed on the sensor controller; Spindle jamming; Stator winding damaged and requires rewinding, Temperature sensor in stator windings indicates error; Oil pressure (tool unclamping) too low, oil level too low; Frictional corrosion (rust) on taper in consequence of extreme vibrations; Hydraulic cylinder defective or any other defect; Metal chips, too much grease or dirt restrict the clamping process; Adjustment of clamping cone not correctly set, lock screw loose; Cup springs broken, clamping force insufficient or any other defect;
[0013] When such breakdown or failure is fixed at the site where the machine tool is used, conduits for supplying a fluid and air pressure for the lubrication, cooling and cleaning and electric wirings to the motors and limit switches are required to be removed. Then, the spindle device is disassembled to replace/repair the spindle, the parts within the spindle or the bearings, thereafter the spindle device is reassembled. The repaired/ reconditioned spindles need to be checked and performance validated properly before installation on the machine.
[0014] It is evident that there is always a critical need to test these repaired/ reconditioned, high speed integrated motor spindles for repair purpose as these motor spindles are highly expensive as compared to conventional spindles with a guaranteed life of 6000 working hours only and need frequent repair/replacement on the machines after the completion of their guaranteed working life given their susceptibility for failure owing to aggressive machining parameters.
[0015] As per prior art, such HSM spindle performance validation related requirements are met by installation on the concerned machines. This process is time consuming and does not permit open loop testing in between the repair work. The result of installation on machine generally leads to at least a few times of re-work.
[0016] Therefore, a need exists to develop and design the required capabilities/ facilities and the necessary ergonomics to overcome such issues. A state of the art ‘Test control unit’ with closed loop/open loop testing and repair of spindles having similar electronic configuration as used on the machines, all test instruments, requisite safety for part by part testing, change-over between spindle types and ratings and digital display of all monitoring parameters has been conceived. With this ‘Test control unit’, as elaborated in this specifications, the testing and repair setup will be covering all aspects of quality & reliable repair.

OBJECTIVE
[0017] A main objective of the present invention is to provide a system for validation of performance of a high speed spindle.
[0018] Another objective of the present invention is to provide a process to perform validation test of performance of a high speed spindle.
[0019] Yet another objective of the present invention is to provide a system and process for closed loop/open loop testing and repair of high speed spindles.
[0020] Still another objective of the present invention is to save considerable amount of time of re-installation i.e. to reduce down-time of machine tool in case of faulty repair.
SUMMARY OF THE INVENTION:
[0021] The present invention relates to a system and process for testing the performance of high speed motor spindle. The system comprises of an electrical cabinet. The electrical cabinet further is mounted with components installed at the front side of the electrical cabinet. The electrical cabinet comprises of plurality of digital displays provided at the top of front side of the electrical cabinet. A digital insulation tester is also provided on the front side of the electrical cabinet. Further, the electrical cabinet consists of an encoder testing device that is provided at the bottom-left side of the electrical cabinet. A plurality of operational push-buttons is provided below the digital insulation tester at the right of front side of the electrical cabinet. A feed rate potentiometer is installed on bottom right side of the electrical cabinet.
[0022] In an aspect, the electric cabinet further comprises of a filter module, a HF communication choke, an in-feed regenerative feedback module, a power module, a universal controller card, a surge arrestor, a pre-assembled encoder cable and a motor power cable.
[0023] In an aspect, the digital display is provided to check motor speed.
[0024] In an aspect, the digital display is provided to check motor current.
[0025] In an aspect, the digital display is provided to check tool clamp/ unclamp feedback for voltage sensor.
[0026] In an aspect, the digital display is provided to check tool clamp/ unclamp feedback for current sensor.
[0027] In an aspect, the digital display is provided to check bearing temperature.
[0028] In an aspect, the method for performance validation of high speed motor spindle comprises of installation of repaired mechanically assembled spindles on a testing stand; run-out checking on the testing stand; testing of insulation of motor spindle through selector switch with the help of digital insulation tester; selecting the online testing mode through selector switch and open loop feedback through selector switch; mounting of an encoder in the motor spindle in front of encoder wheel; connecting the encoder feedback cable with the encoder testing device through connector; selecting spindle though selector switch for parameter set changeover; checking the spindle clamping force from 18KN to 21KN, and; performing performance validation test by selecting required parameters.
[0029] In an aspect, the run-out checking of the high speed motor spindle is carried out by carrying out run-out check of spindle taper, run-out check of spindle face and run-out check of arbour in spindle at 300mm.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0030] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0031] Fig. 1 schematically illustrates front view of the electrical cabinet of the testing system over which operational components are installed.
[0032] Fig. 2 schematically illustrates front view of the electrical cabinet of the testing system, emphasizing another set of installed operational components.
[0033] Fig. 3 schematically illustrates inside view of the electrical cabinet.
[0034] Fig. 4 schematically illustrates run-out checking of the motor spindle.
[0035] Fig. 5 illustrates flow chart of process for performance validation of a high speed spindle.

DETAILED DESCRIPTION OF THE CURRENT INVESTIGATION
[0036] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
[0037] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and detailed in the following description. Descriptions of well-known components and processing techniques are omitted to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0038] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0039] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0040] There is always a critical need to test these repaired/ reconditioned, high speed integrated motor spindles for repair purpose as these motor spindles are highly expensive as compared to conventional spindles with a guaranteed life of 6000 working hours only and need frequent repair/replacement on the machines after the completion of their guaranteed working life given their susceptibility for failure owing to aggressive machining parameters. High Speed Motor spindle performance validation related requirements are met by installation on the concerned machines. This process is time consuming and does not permit open loop testing in between the repair work. The result of installation on machine generally leads to at least a few times of re-work. Therefore, a need exists to develop and design the required capabilities/ facilities and the necessary ergonomics to overcome such issues.
[0041] In the present invention to check and validate performance of a high speed motor spindle a system 101 is provided for testing and validating performance of a high speed spindle motor. In reference to Fig. 1, the system 101 comprises of an electrical cabinet 1. The electrical cabinet 1 further comprises of a set of operational push buttons 2 that are mounted on the front side of the electrical cabinet 1. Further, the electrical cabinet comprises of a plurality of digital displays 8, 9, 10, 11, 12 and 13 provided at the top of front side of the electrical cabinet 1. The plurality of digital displays is provided to check motor speed 8, motor current 9, motor temperature 10, tool clamp/ unclamp feedback for voltage sensor 11, tool clamp/ unclamp feedback for current sensor 12 and bearing temperature 13.
[0042] A digital insulation tester 14 is provided below the digital display 11 at the front side the electrical cabinet 1. The digital insulation tester 14 is provided with back-lit display for visual display in insulation testing mode. Further, a plurality of selector switches 16, 17, 18, 19, 20 and 21 are provided below the plurality of digital displays 8, 9, 10, 12 and 13. The two-position selector switch 16 is provided for offline/online testing for selection of insulation testing mode and disabling of drive/motor operation. The two-position selector switch 17 is provided for closed/open loop operations. The three-position selector switch 18 is provided for phase for insulation testing. The two-position selector switch 19 is provided for display and parameter set change-over. The two-position selector switch 20 is provided for selection of tool clamp sensors. And the three-position selector switch 21 is provided for selection of bearing temperature sensors.
[0043] Further, an encoder testing device 15 is provided at the bottom-left side of the electrical cabinet 1 to check the encoder feedback for correct functioning of the motor spindle in the closed loop feedback system. Further, a feed rate potentiometer 28 is installed on bottom right side of the electrical cabinet 1.
[0044] In reference to Fig.2, the operational push-buttons 2 with LED light indicators have been provided on front side of electrical cabinet 1 for performing ON & OFF functions. The push button 22 is mounted for performing ON & OFF functions for motor spindle. The push button 23 is mounted for performing ON & OFF functions for hydraulic unit ON &OFF. The push button 24 is mounted for performing clamping and unclamping of tool. The push button 25 is mounted for performing pneumatic ON & OFF. The push button 26 is mounted for water coolant motor ON & OFF. And the push button 27 is mounted for performing ON & OFF of water coolant valve.
[0045] In reference to Fig.3, the electrical cabinet 1 further comprises of components installed inside the electrical cabinet 1. The AC drive for control of asynchronous motor comprising of a filter module 3, a HF communication choke 4, an in-feed regenerative feedback module 5, a power module 6, a universal controller card 7, a pre-assembled encoder cable, a motor power cable and a surge arrestor/overvoltage limiter is installed inside the electrical cabinet. The surge arrester/overvoltage limiter is installed to be suitable for all the other modules installed inside the electrical cabinet.
[0046] In reference to Fig. 4, it illustrates run-out checking of the motor spindle. The high speed motor spindle that is to be checked is installed on a testing stand and subsequently run-out checking is performed. Firstly, run-out check of spindle taper 29 is performed, followed by run-out check of spindle face 30 and then run-out check of arbour 31 in spindle is performed at 300mm.
[0047] In reference to Fig. 5, the flow chart illustrates steps that are carried out in the process of testing of performance of high speed spindle. The process to carry out testing of performance of high speed spindle comprises of installation 110 of repaired mechanically assembled on testing stand. The run-out checking 111 of the spindle is clearly illustrated by Fig. 4. The process further comprises of testing 112 of motor spindle in offline testing mode through selector switch 16 with the help of digital insulation tester 14. In this case, drive/motor operation is disabled. The insulation resistance (IR) of each winding is checked through a phase select switch 18.
[0048] Further, selection 113 of the online testing mode through selector switch 16 and open loop feedback through selector switch 17 to run the motor spindle at desired rpm without monitoring encoder feedback to check that mechanical assembly of the motor spindle has been done correctly and no noise or abnormalities have been observed during rotation of the motor spindle. Otherwise, the noise or abnormalities are rectified and again the motor spindle is checked.
[0049] The subsequent step in the process is to mount the encoder in the motor spindle in front of the encoder wheel at marked up position and air gap is set between wheel tooth and encoder.
[0050] Further, the process comprises of connecting encoder feedback cable with encoder testing device 15 through connector 35 provided on the electrical panel 1 followed by switching on the testing device, rotating the motor spindle by hand and observe the measuring values by selecting through push buttons provided over the electrical panel 1.
[0051] Then the spindle is selected through selector switch 19 for parameter set changeover. Tool clamp/unclamp voltage values are checked on digital display 11 in case of voltage sensor and the tool clamp/unclamp current values on the digital display 12 is displayed in case of current sensor.
[0052] The next step comprises of checking the spindle clamping force from 18KN to 21KN.
[0053] The subsequent step comprises of selecting the closed loop feedback through selector switch 17, selection of spindle through selector switch 19, selecting the online testing mode through selector switch 16, switching ON the spindle through push button 22. These process checks performance of the spindle and validates if the spindle is ready to be installed on machine.