Claims:WE CLAIM:
1. A process (100) for dismantling a high-speed integrated motor spindle 7 (HSM) spindle comprising the steps of:

Removing a coolant rotary union 1, used for coolant supply through the spindle, located at rear side of spindle 7;
Removing a hydraulic clamping unit 32 from rear side of spindle 7;
Removing a upper Housing of the spindle from rear side spindle 7;
Removing analog sensor 10, encoder 6 & their mounting;
Removing rear housing chuck nut with the rear side chuck nut
opening tool 4;
Removing taper cone required for sensing the clamping/unclamping through analog sensors 10, which are required for the measurement of contact characteristics of the spindle–holder taper interface, critical for the evaluation of the performance of a machine tool spindle system;
Removing locking screw of taper cone with tie rod & then the taper cone mounting thereby completing the rear side dismantling of the spindle 7;
Removing encoder wheel 31 used for sensing the position of spindle 7;
Removing rear end bearings 11 in bearing case provided for rotationally supporting the rear part of the spindle 7, bearing case fitted in the rear housing 20;
Removing the collet 2 from front and then removing the tie rod and the front supporting rings, stud;
Removing the front chuck using rear side shaft locking tool 16, key 17 to lock shaft with rear side locking tool 16, front side chuck nut locking tool 18 and dowel pins 19;
After locking the rear shaft with chuck nut with rear side shaft locking tool 16 and key 17 to lock shaft with rear side locking tool, affix the front side chuck nut locking tool 18 with dowel pins 19 and the plurality of bolts 29;
Applying the levering action on the both side fixed tools to remove front chuck nut of the spindle 7;
Removing front bearings 9 from the front housing 21, bearing retainer 25, draw bar 26 and the springs 27;
Separating front housing 21, along with the front bearings 9 and the spindle 7, from the rear housing 20 by untightening screw bolts; and
Removing rotor 13, provided onto the spindle 7 with a small radial gap provided relative to the stator 15 and secured to a sleeve 14 by shrinkage fit, from stator of the built-in motor is provided inside of the rear housing 20.

2. The process (100) as claimed in claim 1, wherein the actual clamping state is calculated by measuring the axial displacement of the clamping cylinder.

3. The process (100) as claimed in claim 1, wherein the coolant rotary union 1, used for coolant supply through the spindle, located at rear side of spindle 7 is removed by untightened of the screw bolts from the rear side of the machine tool to remove the coolant, hydraulic & pneumatic supply pipe.
, Description:FIELD OF INVENTION
[001] The present invention relates to repair, reconditioning and salvaging of motor spindles. More particularly, the present invention relates to a method and tool for dismantling and reassembly of 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. Spindles have a strong influence on metal removal rates and quality of the machined parts.

[003] Classically, main spindles were driven by belts or gears and the rotational speeds could only be varied by changing either the transmission ratio or the number of driven poles by electrical switches. Later simple electrical or hydraulic controllers were developed, and the rotational speed of the spindle could be changed by means of infinitely adjustable rotating transformers. The need for increased productivity led to higher speed machining requirements which led to the development of new bearings, power electronics and inverter systems. The progress in the field of the power electronics (static frequency converter) led to the development of compact drives with low-cost maintenance using high frequency three-phase asynchronous motors. Today, the overwhelming majority of high productivity, speed, and accuracy based machine tools are equipped with motorized spindles. Unlike externally driven spindles, the motorized spindles do not require mechanical transmission elements like gears and couplings.
[004] Through the early 1980's high spindle speeds were achievable only by using better technologies which includes high speed ceramic bearings presently. Continuous developments in bearings, lubrication, the rolling element materials and drive systems (motors and converters) have allowed the construction of direct drive motor spindles which currently fulfill a wide range of niche machining requirements.
[005] 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.
[006] It can also be mentioned that, 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 (with different teeth number Z), various tool profiles and various cutting conditions (spindle speed, width of cut, etc.).
[007] Today's spindle designs offer the manufacturers and machine builders much greater performance and reliability than ever before. Users can increase productivity in any industry by properly applying the advanced spindle technologies in specific applications. The powerful, flexible and faster machine tool spindles can reduce the number of cuts/ passes in manufacturing by half and increase the cutting feed-rates up to 5000 mm/min which is more than 4-5 times faster. High-speed spindles are more or less designed with the motor directly flanged to the spindle shaft.
[008] High speed, precision, ultra-precise machining technology is an important trend of advanced manufacturing engineering, and high-speed machining is a promising advanced manufacturing technology for increasing productivity and reducing production costs dramatically. High speed machine tool with high speed motor spindle is the precondition for realizing high speed machining. Compared with conventional spindle, motorized spindle is equipped with a built-in motor, so that power transmission devices such as gears and belts are eliminated and "zero transmission" loss is realized.

[009] A high speed motorized spindle is driven by an in-built asynchronous motor and the rotation speed of the motor is continuously variable via the static frequency converter which is a CNC controlled digital drive in most cases. The spindle shaft is fixed in the spindle sleeve by four angular contact hybrid bearings and these bearings are lubricated. To dissipate the operational heat associated with such spindles, high pressure internal coolant with rotary unions are provided in a way that the cooling system is integrated in the spindle sleeve. The tool clamping system is driven by a hydraulic cylinder and the unclamping unit consists of a hydraulic cylinder for the tool clamping system and a retention device for the spindle shaft during the unclamping procedure for tool management and operational control of PLC. Two analog sensors provide two channel feedback regarding the tool clamping system and an encoder measures and monitors the spindle position and the rotation speed of the spindle shaft. Thermal sensors monitor the bearing and the stator temperatures.
[0010] Motor spindles essentially have two separate manageable units that on the one hand have an outer, static structure or essential parts of the Stators and on the other hand, the rotating components including the bearings. Motor spindle for a machine tool generally resides in a spindle housing and with a spindle shaft, wherein the spindle shaft is a component of a module unit that can be inserted into the spindle housing, wherein the spindle shaft has a front, working side region, radially held by means of at least two spindle bearing, axially spaced apart inside the module unit, and a rear, housing-side range, which projects into the spindle housing.
[0011] The built-in motor introduces additional mass to the spindle shaft, besides, since it’s very high working speed, some high-speed rotational effects, including centrifugal forces and gyroscopic moments on the spindle, thus complicating its mechanical-dynamic behaviors. Also heat generation and subsequent damage of motorized spindle and bearings are frequent because of the power loss of motor and bearing friction. When the spindles speed of the shaft increases the temperature of shaft also gets increased. This causes service life of bearing to be decreased and bad influence on spindle’s precision as its temperature-rise becomes higher. For high-speed applications using motorized spindles, the internal heat generation can be much higher than belt driven spindles; this can reduce the bearing internal clearance and sometimes cause failure at high-speed.
[0012] 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. 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) x (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.
[0013] 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. The spindle of the shaft rotates for certain time the axial deflection in spindle end position gets increased.
[0014] 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.
[0015] 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, within the spindle or in the bearings.

[0016] 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;
- 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;
- Position of tool is not sufficiently lined up with tool changer;
- Adjustment of clamping cone not correctly set, lock screw loose;
- Cup springs broken, clamping force insufficient or any other defect;
[0017] 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.
[0018] It is evident that there is always a critical need to dismantle these 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.
[0019] In the present practice, spindles used to be replaced with new ones as no repair setup and such special tools were not available. However, in absence of lack of know-how and know-why available from the OEMs, it is very difficult to disassemble such spindles and the problem becomes complex and aggravated. Therefore, a need exists to propose a method and means having required capabilities and the necessary ergonomics to overcome such issues by proposing a tool for dismantling and re-assembly of high speed motor spindles in order to repair & recondition such faulty spindles.
OBJECTS OF THE INVENTION
[0020] It is an object of the present invention is to propose method and means for dismantling and reassembly of high speed motor spindles for repair and retrofitting purposes directed to solve the above-described problems of the prior art.
[0021] Other object of the present invention is to propose method and means for dismantling and reassembly of high speed motor spindles for repair, reconditioning and salvaging purposes directed to enable a person skilled in the art to replace the spindle and the bearings at a site, where the machine tool is used, easily and in short time so that the downtime of the machine tool is reduced as much as possible.
SUMMARY OF THE INVENTION
[0022] The present invention relates to a process for dismantling a high-speed integrated motor spindle (hsm) spindle. During dismantling of the spindle (7), it is seen that front chuck cannot be opened without holding the rear shaft of the spindle. Therefore, the structure/dimensions of the rear side locking tools were decided accordingly. It was decided to have bar like structure having a hole in middle, of the size of the diameter of rear shaft of spindle (7). To hold the shaft, it was decided to utilize the slit on the shaft of spindle by inserting a key (tool no. 17) to lock the rear side locking toll (tool no. 16). This key goes into the slit on the rear shaft through the slit at middle of tool no. 16. To provide additional holding torque, a cylindrical hole at side of tool no. 16 is made. By inserting a rod into this cylindrical hole, additional torque can be provided to hold the rear shaft. Levering action from rear side can also be provided from this rod if needed. After locking the rear shaft with rear side shaft locking tool 16 and key 17 to lock shaft with rear side locking tool, affix the front side chuck nut locking tool 18 with dowel pins 19 and the plurality of bolts 29. Now by applying the levering action on the both side fixed tools, the front chuck nut can be removed.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0023] The foregoing and other features of the invention will be apparent from the following more particular description of the invention, as illustrated in the accompanying drawings, in which like reference characters refer to the same parts throughout the different figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
Figure 1: is a cross-sectional view of a high-speed motorized spindle of similar type and it may be noted that minor changes with respect to the object of the invention may be present in the cross-sectional view.
Figure 2: is a 3D illustration of the developed tool 16 to lock the shaft of spindle after dismantling the rear parts;
Figure 3, 4, 5: are line representation of side, top cut section, front view of the developed tool 16 to lock the shaft of spindle after dismantling the rear parts;
Figure 6: is a 3D illustration of the developed tool 18 to lock the front chuck nut of HSM spindle 7;
Figure 7, 8, 9: are line representation of isometric, side and top view of the developed tool 18 to lock the front chuck nut of HSM spindle 7;
Figure 10: is a 3D illustration of the developed tool 4 to open rear side chuck nut of HSM spindle 7 along with plurality of dowel pin 19 and plurality of bolts 29;
Figure 11, 12, 13: are line representation of isometric, side and top view of the developed tool 4 to open rear side chuck nut of HSM spindle 7 along with plurality of dowel pin 19 and plurality of bolts 29;
Figure 14: is a line representation of key pin 17 to lock rear shaft with rear side shaft locking tool of HSM spindle 7;

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

[0024] The present invention will now be described more specifically with reference to the following specification.
[0025] 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 1-14.
[0026] The present invention is directed to solve the above-described problems of the prior art and to provide a method and means for dismantling and reassembly of high speed motor spindles of a machine tool for repair, reconditioning and salvaging and to enable to replace the spindle and the bearings where the machine tool is used, easily and in short time so that the downtime of the machine tool is reduced as much as possible.
[0027] Structurally and functionally, spindles are very complex in nature, in an example, the details of specification of these high-speed integrated motor spindles are:

- Power: 19-28 kW
- maximum RPM: 15000
- Encoder: 1 VPP Sin/Cos
- Analog sensors for clamping feedback: 4-20 mA
- temperature sensors for motor winding: KTY84-130
- Temperature sensors for bearings: PT100

[0028] Figure 2 represents a 3D illustration of the developed tool 16 to lock the shaft of spindle after dismantling the rear parts. Tool no 16 is rear side shaft locking tool. The raw material required is X22 chromium alloy steel. The length of this tool is 360 cm & width is 81 cm. During dismantling of the spindle (7), it is seen that front chuck cannot be opened without holding the rear shaft of the spindle. Therefore, the structure/dimensions of the rear side locking tools were decided accordingly. It was decided to have bar like structure having a hole in middle, of the size of the diameter of rear shaft of spindle (7). To hold the shaft, it was decided to utilize the slit on the shaft of spindle by inserting a key (tool no. 17) to lock the rear side locking toll (tool no. 16). This key goes into the slit on the rear shaft through the slit at middle of tool no. 16. To provide additional holding torque, a cylindrical hole at side of tool no. 16 is made. By inserting a rod into this cylindrical hole, additional torque can be provided to hold the rear shaft. Levering action from rear side can also be provided from this rod if needed. After locking the rear shaft with rear side shaft locking tool 16 and key 17 to lock shaft with rear side locking tool, affix the front side chuck nut locking tool 18 with dowel pins 19 and the plurality of bolts 29. Now by applying the levering action on the both side fixed tools, the front chuck nut can be removed.
[0029] In accordance with an embodiment of the present disclosure, a process 100 for dismantling a high-speed integrated motor spindle 7 (HSM) spindle comprises of:
[0030] Removing the coolant rotary union 1, used for coolant supply through the spindle, located at rear side of spindle 7. The screw bolts are untightened from the rear side of the machine tool to remove the coolant, hydraulic & pneumatic supply pipe.
[0031] Removing the hydraulic clamping unit 32 from rear side of spindle 7.
[0032] Removing the Upper Housing of the spindle from rear side spindle 7.
[0033] Removing analog sensor 10, encoder 6 & their mounting as these analog sensors are used to give the actual feedback to the main CNC control about the tool clamping state. The actual clamping state is calculated by measuring the axial displacement of the clamping cylinder. Three important clamping states must be detected here i.e., tool unclamped, tool clamped and collet clamped without tool. An analog signal that is proportional to the displacement and provides feedback relating to the clamping state. This type of position feedback allows the clamping state to be monitored continuously during the machining process. Continuous monitoring of the clamping state not only improves results on the actual machined workpiece, but also increases the reliability of the overall clamping system.
[0034] Removing rear housing chuck nut with the rear side chuck nut opening tool 4 (refer figure 10).
[0035] Removing the taper cone required for sensing the clamping/unclamping through analog sensors 10, which are required for the measurement of contact characteristics of the spindle–holder taper interface, critical for the evaluation of the performance of a machine tool spindle system.
[0036] Removing the locking screw of taper cone with tie rod & then the taper cone mounting thereby completing the rear side dismantling of the spindle 7.
[0037] Removing encoder wheel 31 used for sensing the position of spindle 7.
[0038] Removing rear end bearings 11 in bearing case provided for rotationally supporting the rear part of the spindle 7, bearing case fitted in the rear housing 20.
[0039] Removing the collet 2 from front and then removing the tie rod and the front supporting rings, stud.
[0040] Removing the front chuck using rear side shaft locking tool 16 (Refer figure 2, 3, 4, 5), key 17 (Refer figure 14) to lock shaft with rear side locking tool 16, front side chuck nut locking tool 18 (Refer figure 6, 7, 8, 9) and dowel pins 19 (Refer fig 10). After locking the rear shaft with chuck nut with rear side shaft locking tool 16 and key 17 to lock shaft with rear side locking tool, affix the front side chuck nut locking tool 18 with dowel pins 19 and the plurality of bolts 29 (Refer fig 6).
[0041] Applying the levering action on the both side fixed tools to remove front chuck nut of the spindle 7. Removing front bearings 9 from the front housing 21, bearing retainer 25, draw bar 26 and the springs 27. The front housing 21 is separated, along with the front bearings 9 and the spindle 7, from the rear housing 20 by untightening screw bolts.
[0042] Removing rotor 13, provided onto the spindle 7 with a small radial gap provided relative to the stator 15 and secured to a sleeve 14 by shrinkage fit, from stator of the built-in motor is provided inside of the rear housing 20.
[0043] After removing the rotor parts, the spindle 7 is fully dismantled and a person skilled in the art can now replace the wear out parts and repair the spindle. The inspections, and, if necessary, the repairs are carried out after dismantling the spindle while laying it down on a support or vice.

[0044] Although embodiments for the present subject matter have been described in language specific to package features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/device of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.
[0045] 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.