FORM 2
THE PATENT ACT 1970 (39 of 1970)
&
The Patents Rules, 2003 COMPLETE SPECIFICATION
(See Section 10, and rule 13)
1. TITLE OF INVENTION
A VERTICAL MACHINING CENTER
2. APPLICANT(S)
a) Name : PREMIER LIMITED
b) Nationality : INDIAN Company
c) Address : 58, NARIMAN BHAVAN,
NARIMAN POINT, MUMBAI-400 021, MAHARASHTRA, INDIA
3. PREAMBLE TO THE DESCRIPTION
and the manner in which it is to be performed : -

FIELD OF INVENTION
The present invention relates generally to Vertical Machining Center machine and more specifically to a new and unique CNC (computer numeric control) Vertical Machining Center which is adapted for high-speed production of parts, greater stability, less vibration, chatter and which require cutting coolants to prevent heat build-up during the machining process.
BACKGROUND OF THE INVENTION
Vertical machining center machines are much known in the art. They are required for producing various type of work pieces of desired finish for different requirements. The challenges faced in the field vertical machining technology primarily comprise of producing high quality work pieces which are error free and possess precise surface finish. Producing larger number of such precise work pieces is an additional challenge looking at the manual tooling time and installation and uninstallation procedures. Further such manual setting of work pieces and tool not only increased production time but also increased the chances of human error in manufacture. Thus there is along felt need in the art to find a completely automated Vertical machining center which will produce finished work piece after a single installation possessing no interim manual work over and/or change in installation of work piece or tooling thus in turn lowering the overall production time.
The error free and high precision machine tool products are required to meet the continuous demand of Engineering, Automobile and Government Sector Industries like Power Sectors, Railways, Defense etc. In recent years there has emerged a need to machine number of work pieces with the high productivity and accuracies. Complex machining operations such as Milling, Facing, Boring, Drilling, Tapping, Deep Boring etc. are needed to be performed in single set up. Such are required in the field of valves, casings, cylinder blocks, gear box housing, aerospace components and bearings blocks for internal combustion engines of rails.

Vertical Machining Centers are generally adapted to produce a wide variety of parts, and thus are capable of operating at a wide variety of speeds and holding a large number of different cutting tools which can be interchanged during the machining process to produce the particular part desired. While conventional machining centers are well adapted to perform a wide variety of machining operations, there are unfortunately several drawbacks with existing machining centers. For example, low production rate, accuracy etc.
Thus there existed a long felt need in the art to produce a Vertical Machining Center machine which would overcome the above-mentioned problems in the art and would produce more precise and accurate work pieces in reduced manufacturing time. The Vertical Machining Center machine in accordance with the present invention meets the aforesaid long felt need.
All through out the specification including the claims, the words "work piece", "tool", "machine head", "machine guard", "cross slide", "machine base", "pulley", "timer belt", "milling", "boring", "turning", "ball screws", "guide ways", "motors", and "control panel" are to be interpreted in the broadest sense of the respective terms and includes all similar items in the field known by other terms, as may be clear to persons skilled in the art. Restriction/Limitation if any, referred to in the specification, is solely by way of example and understanding the present invention.
OBJECTS OF THE INVENTION
The principal object of the present invention is to produce a Vertical Machining Center which possess increased accuracy and reduced operation time for machining.
It is another object of the present invention to produce a Vertical Machining Center which performs a wide variety of machining at one go using a variety of tooling set.

It is a further object of the present invention to produce a Vertical Machining Center which results in zero error and more precisely finished work pieces.
It is yet another object of the present invention to produce a Vertical Machining Center which requires no manual intervention saving substantial machining time.
It is another object of the present invention to produce a Vertical Machining Center which provides much faster machining compared to Vertical Machining Center known in art.
It is another object of the present invention to produce Vertical Machining Center machine which possess electronic means for overall process control and precision.
How the foregoing objects are achieved and the other aspects of the present invention will be clear from the following description, which is purely by way of understanding and not by way of any sort of limitation.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a vertical machining center, comprising at least one Machine Base , a Column, a Cross Slide and a Table operatively mounted on said machine base, a Milling Head and an Auto Tool Changer driven by an electrical control for machining a workpiece.
In accordance with preferred embodiments of the vertical machining center of the present invention:
- said Column houses a suitably mounted cutting assembly;
- said Milling Head houses a spindle assembly;

- said Spindle Assembly is counterbalanced by a Hydraulic Counterbalance Cylinder;
- the spindle is rotated at a rate of 1-10000 revolutions per minute;
- said spindle direct drive assembly comprises a flexible coupling mounted to a motor shaft and a ball-screw to eliminate backlash;
- said Counter balance assembly is secured to Column and Milling Head .
- said machine comprises a tool holder/gripper means mounted on a storage device enabling a tool holder to be transferred between a tool holder station and said spindle.
- said machine comprises a Chip Conveyor , further comprising, a Coolant Tank and Chip trolley for the removal of chips.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The nature and scope of the present invention will be better understood from the accompanying drawings, which are by way of illustration of some preferred embodiments and not by way of any sort of limitation. In the accompanying drawings,
Fig 1(a) illustrates the perspective layout of the Vertical Machining
Center according to the present invention;
Fig 1(b) illustrates the Side View of the Vertical Machining Center
according to the present invention;

Fig 1(c) illustrates the Plan View of the Vertical Machining Center
according to the present invention;
Fig 2a, 2b and 2c illustrates the X-Axis Drive Assembly, Y-Axis Drive Assembly and Z-Axis Drive Assembly of the Vertical Machining Center according to the present invention;
Fig 3 illustrates the X-Axis Kinematics drawing of the Vertical
Machining Center according to the present invention;
Fig 4 illustrates the Y-Axis Kinematics drawing of the Vertical
Machining Center according to the present invention;
Fig 5 illustrates the Z-Axis Kinematics drawing of the Vertical
Machining Center according to the present invention;
Fig 6 illustrates the Milling Head Spindle Assembly of the Vertical
Machining Center according to the present invention
DETAILED DESCRIPTION OF THE INVENTION
The following describes some preferred embodiments of the present invention, which are purely for the sake of understanding the present invention and not by way of any sort of limitation.
The present invention provides a dedicated Vertical Machining Center which is able to produce a finished work piece or a number of work pieces at very high speed. The invention includes a motor adapted to run at very high speeds and which is connected to the Milling spindle through a direct drive arrangement. The table being of sufficient mass and area to provide a damping force that facilitates reducing vibrations and harmonics generated by the machine. The drive arrangement

efficiently transfers rotational power from the motor to the spindle with no wear and backlash of the rotating parts.
The Vertical Machining Center Model as disclosed in the present invention is a compact configuration type design comprising an Integral mechanical - electrical construction minimizing floor space requirement and to enhance productivity per unit space. It has a Machining Zone of 610x460x510 mm.
As illustrated in Figure 1 (a,b,c) the Machine Base (1), Column (2), Cross Slide (3), Table (4), Milling Head (Spindle Assembly) (5) are designed with special grade Cast Iron in sturdy box type construction duly ribbed to ensure stable and heavy duty cutting. The axes movements of Vertical Machining Center are through large diameter precision ground ball screws, driven by AC Servomotor. The Ball Screws are laid out symmetrically with respect to the slide ways for achieving better accuracies. It is equipped with Linear Motion(LM) Guide ways for all axes ensuring excellent positional accuracy and repeatability. Rapid traverse rates of 32m/min for X, Y and Z Axis and feed rates upto 10000 mm/min with absolute encoder.
The Milling Head (Spindle Assembly) (5) is equipped with high precision spindle of nitrided steel mounted on special class high precision preloaded angular contact ball bearings. The shape of the spindle nose is so designed as to enable easy access into the workpiece / fixture, for accurate, cost effective and high speed machining. This assembly is equipped with electrical orientation system for quick orientation straight from rotation.
The Milling Head (Spindle assembly) (5) is driven by an AC Motor through a two speed gear box which ensures availability of full power even at lower rpm, thereby eliminating the necessity of providing excessively high powered motor. To secure better machining parameters, the machine is equipped with a direct drive, lOOOOrpm Cartridge type Milling Head (Spindle Assembly) (5) with Oil Chilling Unit.

A twin arm Auto Tool Changer unit having disc type magazine accommodating 20 Tools. It features a one motion system where the tool is accepted while being tilted. This greatly reduces tool change time to 2.5 seconds enhancing reliability. Meticulous consideration is provided so that the tool is easily removed from the ATC Magazine during tool changing set up. The Auto Tool Changer Software utilizes the latest random selection system where in the previous tool goes to the pocket emptied by the new tool and after each tool change, the computer updates the data relating to the tool number and pocket number.
The state of art Operator friendly CNC technology equipped with a powerful programmable logic controller for sequencing the machine function and interfacing to the CNC system. It also provides ample Input/ output diagnostic facility for quick location of faults on the machine side. All commonly used user functions available with array of optional features to enhance machining capability and programming ease. It is also designed to consider Total Productivity Maintenance (TPM) concept.
The Chip Conveyor (7) system to have efficient swarf disposal is placed in the front of the machine guard (8) to collect the chips directly from machining zone. The economically superior design of Vertical Machining Centre ensures minimum operators fatigue by way of centralized pendant type operation panel, easy chip disposal, easy accessibility etc.
As illustrated in Figure la, lb and lc, a typical Vertical Machining Center (VMC) machine includes a Machine Base (1), Column (2), Cross Slide (3), Table (4) and the Milling Head (Spindle Assembly) (5). The Table (4) assembly holds a piece of stock material relative to the Milling Spindle (5) for machining. The motor and spindle drive assembly used for rotating the spindle at a desired speed. Cutting Tools used for machining the stock material. The Automatic Tool Changer (6) which holds a variety of cutting tools and allows for a number of cutting tools to be interchanged for use in machining a part. Typically, Vertical Machining Center also includes a

CNC system which controls the positioning of a cutting tool with respect to the Table (4) and the work-piece to produce a part of the desired shape.
The Vertical Machining Center having milling spindle nose taper is designed to accommodate maximum load on the table for machining of 400 kg work piece. It is equipped with major parts such as Machine base (1) Cast Iron construction with heavy ribbing. Hardened and ground Linear Motion Guide ways, Pre- tensioned, Ball Screws. The Servomotors are directly coupled by a flexible coupling to the Ball Screw for zero backlash and improved positioning accuracy. A floating type tool de-clamp system eliminates the unclamping forces generated by the tool release cylinder substantially prolonging the bearing and spindle life. Side mounted swing arm type Automatic Tool Changer (6) is driven by an electrical motor for accurate and shorter toohchange time. High pressure coolant spray efficiently takes out chips and prevents heat build-up during deep-hole machining enhancing tool cutting performance and delivering consistent part accuracy.
Additionally, the typical Vertical Machining Center is designed to be highly versatile, it often requires the spindle speed to be adjusted depending upon the stock material. The Automatic Tool Changer (6) to house number of cutting tools to improve the flexibility and versatility of the machine.
The present invention will now be discussed with reference to the accompanying drawings. A preferred embodiment of the present invention is shown in fig 1(a), 1(b) and 1(c). The Vertical Machining Center is designed and adapted as a machine dedicated to the manufacture number of different parts at a very high rate. As such, the Vertical Machining Center (VMC) is designed with a minimal number of moving parts and assemblies with minimal vibration and chatter. The Vertical Machining Center includes a Machine Base (1), Column (2), Cross Slide (3), Table (4) and Milling Head (Spindle assembly) (5). The Machine Base (1) and Column (2) are designed with adequate mass and structural rigidity to provide significant damping

to the machine to reduce harmonics and vibrations (i.e., chatter) generated by cutting action of the machine and the motion of the slides.
On CNC Vertical Machining Center and more specifically to a new and unique VMC the following operations can be performed.
1. Milling
2. Drilling
3. Boring
4. Tapping.
Fig 1 (a, b and c) illustrates the Machine Layout. The Column (2) and the Cross Slide (3) are mounted on the Machine Base (1). Milling Head (Spindle Assembly) (5) is mounted the Column (2). The Table (4) is mounted on the Cross-Slide (3). Direct Drive with AC Servomotors and flexible coupling are used to drive the X-Axis, Y-Axis and Z-Axis Slides. An Automatic Tool Changer (6) mounted on the Column (2) can carry upto 20 Tool for performing the various operations required on the work-piece. The thermo-symmetric column (2) is a cast iron structure. It is mounted at the rear side and at the top of the Machine Base (1). The column (2) carries the Z-Axis LM guides and the Milling Head (5) traverses up/ down on the Column (2) Guideways. The Milling Head (Spindle Assembly) (5) is balanced by means of a Hydraulic Counterbalancing Cylinder. The figures 1&, lb and lc further identifies the position of the chip conveyer (7), machine guard (8), operator pendent control box (9),electrical control cabinet (10), hydro cyclone filtration unit (11), and AC for control cabinet (12).
Automatic lubrication system is used which provides lubrication in pressurized state to all moving elements like ball screws, Ball screw support bearing etc.
Chip conveyor (7) is designed for maximum chip carrying capacity. Chip conveyor (Slat Type) (7) is very suitable to carry curly chips. Coolant tank is of 300 Litres

capacity is integral with the chip conveyor (7). On this tank is mounted the Coolant pumps for Cutting and Bed Flushing.
Electrical Control Cabinet (9) is mounted on rear side of machine and provided with AC for Cooling (12). Economically designed Swiveling type Operator Control Pendent Box (9) with AC for Cooling is mounted on machine front.
Appropriate control of the motors, as can be accomplished through known control systems, which permits the cutting tool to be guided along the desired path relative to the work-piece for machining the desired shape.
Fig 2 (a, b and c) illustrate the X-Axis Drive Assembly/ Y-Axis Drive Assembly and the Z-Axis Drive Assembly. The X, Y and Z axis and has high precision, large size ball screws which provides good repeatability and fast traverse. All the sliding surface of the assembly are hardened and ground for accurate sliding and long service. Ball screw is supported on both ends. Ball screws (2.2, 3.2, 4.2) are directly driven by servo motor (2.1, 3.1, 4.1) and connected by flexible coupling which gives accurate drive without backlash. Oil Lubrication facility is adapted for LM Guideways (2.3,4.3) and Ball Screws. For holding the feed axis at a standstill without backlash during operating, a holding torque is generated by the servo motor. The figures 2a and 2b additionally illustrate the position of the telescopic covers (4.4,3.3).
The axis drive servomotor for the vertical Z-Axis is equipped with a holding brake to prevent the Milling Head (Spindle Assembly) (5) from dropping down on power fail condition. The permanent magnet holding brake operates according to the principle of the closed circuit current. When the permanent magnet is used, it exerts, by means of its magnetic field, a fractional force on the armature brake disc. When de-energized the brake is closed and the motor shaft is held.

Fig 3,4 and 5 illustrates the Kinematics of the X-Axis Drive Assembly, Y-Axis Drive Assembly and the Z-Axis Drive Assembly. Figure 3, 4 and 5 further explains the Coupling (4.5,3.4,2.4) between the ball screw and the motor.
Fig. 6 illustrates the Spindle (5.1) driven by AC spindle motor of 7/11RW (Continuous / 30 mins Intermediate) power and l0000 rpm capacity directly through Coupling. The Spindle is stopped dynamically to bring it to a standstill at an oriented position for Tool Change. Bearings of the spindle are grease lubricated for life.
Hydraulic power pack is used to actuate the Tool De-clamp Cylinder for unclamping the tool. By means of solenoid direction control valve hydraulic cylinder actuates and de-clamping is done.
The present invention represents an advancement over machines of the prior art by providing a mechanically stiffer machine, exhibiting improved dynamic characteristics and yet one which is less costly to produce. The inventive machine can be made more reliable than the Vertical Machining Center of the prior art.
The present invention has been described with reference to some examples and preferred embodiments, purely for the sake of understanding and not by way of any limitation and the present invention includes all legitimate developments within the scope of what has been described hereinbefore and claimed in the appended claims.

WE CLAIM:
1. A Vertical Machining Center, comprising at least one Machine Base (1), a Column (2) a Cross Slide (3), and a Table (4) operatively mounted on said machine base, a Milling Head (5) and an Auto Tool Changer (6) driven by an electrical control (10) for machining a workpiece.
2. The Vertical Machining Center as claimed in claim 1, wherein said Column (2) houses a suitably mounted cutting assembly.
3. The Vertical Machining Center as claimed in claim 1, wherein said Milling Head houses a spindle assembly.
4. The Vertical Machining Center as claimed in claim 1 and 3, wherein said Spindle Assembly (5) is counterbalanced by a Hydraulic Counterbalance Cylinder.
5. The Vertical Machining Center machine of claim 1 and 3, wherein the spindle is rotated at a rate of 1-10000 revolutions per minute.
6. The Vertical Machining Center machine of claims 1 and 3, wherein said spindle direct drive assembly comprises a flexible coupling mounted to a motor shaft and a ball-screw to eliminate backlash.
7. The Vertical Machining Center machine of claims 1 and 4f wherein said Counter balance assembly is secured to Column (2) and Milling Head (5).
8. The Vertical Machining Center as claimed in claim 1, wherein said machine comprises a tool holder/gripper means mounted on a storage device enabling a tool holder to be transferred between a tool holder station and said spindle.

9. The Vertical Machining Center as claimed in claims 1 wherein said machine comprises a Chip Conveyor (7), further comprising, a Coolant Tank (11) and Chip trolley (7) for the removal of chips.
10. A Vertical Machining Center substantially as described herein particularly with reference to the accompanying drawings.