BACKGROUND FIELD OF INVENTION
The present invention relates to twin spindle gantry type for Vertical Machining Center (VMC) with or without Auto Pallet Changer (APC) compatible for automation.
DISCUSSION OF PRIOR ART
There are a number of Vertical Machining Centers known in the art. However, there is not one which is automation friendly and have uniquely configured +2_Spindles + 2_Automatic Tool Changers (ATCs) & Auto Pallet Changer (APC) machine with the perfect blend of specifications (Capacities, speed and feeds) in order to meet very high production volumes requirement of smaller/medium sized components of automotive and general engineering industry with critical dimensional accuracy requirement.
Currently such requirements are being fulfilled by combinations of various type of products in market with multiple machines means multiple setups. Hence it was intentionally developed product with all such necessary configuration, specification and variants/options.
US 4781517 titled “Robotic automobile assembly” discuss robotic assembly system means for moving a tool mount through five axes. The invention provide robotic system for moving and assembling components in which the robotic mechanisms are mounted on gantries above the work piece and which are movable through five axes relative to the work piece to effect work upon the work piece.
US 6068431 titled “Machine tool having a gantry and a vertical spindle” discuss gantry machine tool which moves along an X axis and having a vertical spindle supported by the cross-member of the gantry. This machine performs quickly and accurately in a limited three-dimensional zone without moving the gantry.

US 20060242818 titled “Multi-axis, processor-controlled, tool head positioned” discuss multi-axis, processor-controlled, tool head positioning device with six degrees of freedom of movement, using only five axes, in a new and innovative configuration. CNC software is used to integrate operator instructions, machining operations, and the sequence of operations into an automatic and coherent machining package. The invention is a computerized numerically-controlled (CNC) positioning device for a myriad of tool head types.
US 8434657 titled “Positioning apparatus for multiple-spindle machining” discuss positioning apparatus for multiple-spindle machining. The invention is a method of machining simultaneously a sequence of surfaces on each of multiple sides of a work piece. This invention shows positioning assemblies using electrical linear motors and, more particularly, to such assemblies that accelerate and decelerate a movable working element at a rate approaching or exceeding one G.
SUMMARY OF THE INVENTION
The present invention relates to twin spindle gantry type Vertical Machining Centers (VMC) with or without Auto Pallet Changer (APC) compatible for automation. The proposed machine has the following inventive features:
1) The unique configuration of Gantry Type X-Y-Z axes including vertical twin spindles along with or without Auto Pallet Changer (APC) + 4th axes (2 Nos) and duplex Automatic Tool Change (ATC).
2) Chain type quick operating expandable capacity type Tool Magazine with maximum number of tool in the category is arranged with axes module as unique combination.
3) Machine is compatible for automation and provision (Top or front side access to machine fixture by robotic arm is provided) to interface gantry system for auto component load and unload component on pallet while machine is performing

cutting operations on other side of pallet in various positions of machines in production layout.
4) This Configuration also important to achieve many critical machine parameters
as
- Chip to chip time: Optimized axes movements along with twin spindle.
- High Rapid and acceleration rate for Axes: Compact & light weight elements.
- High RPM and Best in class torque: Slim series powerful spindle motors.
- High cutting parameters: Better torque & RPM combinations

5) This machine enclosure (guarding i.e. internal walls of sheet metal inside machine to restrict chips and coolant during cutting operation) and partitions designed with effective chip evacuation philosophy and the cutting zone is completely isolated from machine elements and closed area to collect chips effectively. This is to enhance machine components life and hence machine reliability.
6) Machine is built with modular concept to create variety of products with below mentioned various options and variants available to cater maximum component variety and hence larger market segment.
Variants/Options:-a) Inline type coupled motor Spindle or Motorized built in type Spindle.
b) Medium torque high RPM spindle or medium power medium RPM Spindle.
c) Machine with Twin Spindle or Single spindle Z-Axis.
d) Machine with Single 4th Axis or Two forth axes.
e) Machine with pallet changer or without pallet changer.
f) Machine with HSK-A-50 or BT-30 Type Spindle.

g) Machine with low pressure coolant or through spindle High pressure coolant provision.
h) Machine spindle with retentive collets type and with or without chip detection provision.
7) Mono block construction for machine and major peripheral systems except coolant tank. This is advantages for machine shifting or relocation with minimum down time.
8) Highly innovative Machine styling and graphics to benchmark product aesthetically.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 shows complete machine configuration plan view.
Figure 2 shows detail unique machine configuration of Auto Pallet Changer (APC).
Figure 3 shows unique machine configuration of Axes model.
Figure 4 shows unique machine configuration of Spindle & ATC orientation.
Figure 5 shows automation with robotic arm.
DETAILED DESCRIPTION OF THE ACCOMPANYING EMBODIMENTS
Figure 1 illustrates the complete machine configuration plan view describing the layout of machine along with auxiliary system 5 which includes coolant tank, chip conveyor and electrical cabinet position (not shown in the drawings). The base 1 is main structure of machine on which entire machine elements are mounted and aligned. The base 1 is made out of cast iron and having provision for leveling of machine. The base 1 is anchored to ground to prevent the machine vibration during machine working. Machine is enclosed with specially designed and styled guard with specific machine graphic 3. Machine is equipped with many auxiliary

systems 5 like hydraulic, pneumatic, coolant, chip conveyor, electrical & lubrication required for machine functioning (not shown in the drawings). They all are mounted on machine base and extended bracket on the backside of machine.
Figure 2 illustrates a unique machine configuration of Auto Pallet Changer 2 (APC) in detail. Machining centers have got pallet changer for simultaneous loading /unloading of component on operator side while the machining is happening on other side of pallet. This pallet changer is mounted on front side of base. At the centre of pallet there is partition guard to protect operator from chips and coolant during component load/unloading. Pallet will index 180 degree clockwise and anticlockwise to perform operation. The cables and pipes are routed through the centre of Auto Pallet Changer 2 (APC). There are two 4th axes 6 assemblies mounted on top of Auto Pallet Changer (APC) 2 for additional rotary movement of component for all four face operations. One 4th axis 6 will be on operator side and other in machine work during any condition of machine.
Figure 3 illustrates a unique machine configuration of Axes (X-Y-Z) model 7 with twin spindle unit 8 and column 9. The X-Y-Z module 7 is three direction moving element mounted on top of column 9. The X-Y-Z module 7 is used to provide three basic movements to machine spindles to perform various cutting operations on the component. The two spindles of the spindle unit 8 are mounted on X-Y-Z module 7 with in-line drive motor, retentive type collets & drawbar arrangement and through spindle coolant arrangement (not shown in the drawings). The column 9 is the bridge type main structure on base top and behind the pallet changer mounted. The column 9 will form the support for X-Y-Z module 7. The column 9 is firmly supported on base with adjustment provision through butting blocks (not shown in the drawings).
Figure 4 illustrates a unique machine configuration of Spindle unit 8 & Automatic Tool Changer (ATC) unit 4 orientations. Two tool magazines 10 and 11 are arranged at an angle with respect to spindle position and isolated from

cutting zone by providing sliding partition (not shown in the drawings). This Automatic Tool Changer (ATC) unit 4 is used for loading & unloading various types of tools in and out to spindle unit 8. This various types of tools will be used for performing variety of operations on component. This Automatic Tool Changer (ATC) unit 4 is mounted on back side of column and is provided with one arm 12 and a cam box 13 for each tool magazine.
Figures 5 illustrates robotic automation compatibility for component load and unload from Front Side bottom mounted or Top Side moving gantry mounted robotic arm. Computerized Numerical Control (CNC) interface is available for this automation. Multiple Machines can be arranged to form a production cell with single rotary bottom mounted robotic arm with face to face arranged four machine or gantry type moving robotic arm loading and unloading components on multiple machine arranged in linear cell concept. Since there is dedicated pallet for load and unload components possible during the cycle on for machining components on other side of pallet, this feature along with above unique configuration of machine adds value.
The major details of machine specification and operating parameters are given herein below, which are most important to establish with the esteemed concept of machine.
a) Rapid Traverse rates for X-Y-Z axes: 65 Meters per Min.
b) Axes acceleration rates for X-Y-Z axes: 1.2G.
c) Axes Strokes: X- 350mm, Y = 500mm & Z = 450mm.
d) Spindle Centre distance: 350mm.
e) Maximum Spindle Speed: 15000 RPM.
f) Maximum Spindle Torque: 51.3 Nm Max.
g) Maximum Spindle Power: 10.5KW Max.

h) Maximum Number of tools: 26 per Spindle (Total 52 Nos).
i) Pallet Indexing time: 3 Sec max (0-180 Deg).
k) Chip to chip time: 1.5 Secs (With adjacent pocket & std tool).
l) Tool to tool time: 0.8 Secs at 60Hz.
m) Compact Machine foot print: 1790mm(W) X 4000 (L) x 2600mm (H)
Note : Foot print size including chip conveyor.
Since this machine is designed on STD platform expandable to multiple configurations & Options,
1) The machine shall be modified with Single spindle ram unit (Z-axis), hence X-
Axis stoke change.
2) With respect to Sl. No.1 change the X-axis stroke shall be revised from 370mm
to 550mm.
3) Any one tool magazine shall be removed from current concept of two
magazines.
4) Tool holding capacity of tool magazines may be increased as and when
required in configuration.
5) Tool Magazine indexing shall be CNC axes based on the tool indexing time requirement.
6) Machine can be with or without pallet changer equipped.
7) Pallet changer shall be changed to servo driven or Hydraulic type.
8) No of CNC axes shall be modified as per requirement of configuration to total
11 Numbers.
9) Spindle shall be changed to motorized type (Built-in- motor) with pneumatic
tool clamping type.
10) Machine spindle type can be changed to High torque low RPM spindle.

11) Machine spindle shall be changed to BT type spindle too.
12) Y-Axis shall be change to dual servo driven type to achieve better
performance.
13) Machine lubrication method shall change to replenish able cartridge type lubrication system.
14) Machine spindle & related assemblies shall be modified with MQL (Minimal quantity lubrication) System for cutting.
15) Machine linear guide system shall be changed from ball type to roller type
for various application requirements.

WE CLAIM:
1. A twin spindle, gantry type vertical machining centre comprising:
a) Base 1 on which entire machine elements are mounted and aligned;
b) Column 9 having the bridge type structure mounted on base 1 top and behind the pallet changer 2;
c) X-Y-Z module 7 mounted on top of column 9;
d) Twin spindle unit 8 mounted on X-Y-Z module 7 with in-line drive motor, retentive type collets & drawbar arrangement and through spindle coolant arrangement;
e) Duplex Automatic Tool Change unit (ATC) 4 mounted on back side of column 9;
f) Two 4th Axes unit 6 mounted on top of Auto Pallet Changer (APC) 2 for additional rotary movement of component for all four face operations;
g) Auxiliary systems 5 like hydraulic, pneumatic, coolant, chip conveyor, electrical & lubrication which are required for machine functioning are mounted on machine base and extended bracket on the backside of machine; and
h) Machine enclosed with specially designed and styled guard with specific machine graphics 3.
2. The machining centre according to claim 1, wherein the base 1 is made out
of cast iron and having provision for leveling of machine and said base
being anchored to ground to prevent the machine vibration during machine
working.
3. The machining centre according to claim 1, wherein an Auto Pallet Changer
(APC) 2 is optionally mounted on front side of base 1 to enable simultaneous loading /unloading of components on operator side while the machining is happening on other side of pallet.

4. The machining centre according to claim 1, wherein the Auto Pallet Changer (APC) 1 includes a partition guard at the centre to protect operator from chips and coolant during component load/unloading, said changer indexes 180 degree clockwise and anticlockwise to perform operation.
5. The machining centre according to claim 1, wherein the X-Y-Z module 7 is a three directional moving element, which provides three basic movements to machine spindles to perform various cutting operations on the component.
6. The machining centre according to claim 1, wherein the column 9 form the
support for X-Y-Z module 7 and is firmly supported on base 1 with adjustment provision through butting blocks.
7. The machining centre according to claim 1, wherein the Automatic Tool
Change unit (ATC) 4 is used for loading & unloading various types of tools in and out to spindle 8.
8. The machining centre according to claim 1, wherein one of 4th axis 6 is on
operator side and other in machine work during any condition of machine always.
9. The machining centre according to claim 1, wherein the automatic tool
change unit 4 comprises of two tool magazines 10 and 11 which are
arranged at an angle with respect to spindle position, said change unit 4
being isolated from cutting zone by a sliding partition.

10. The machining centre according to claimed in claim 1, wherein the operating parameters comprises:
a) Rapid Traverse rates for X-Y-Z axes : 65Meters per Min.
b) Axes acceleration rates for X-Y-Z axes : 1.2G.
c) Axes Strokes : X- 350mm, Y = 500mm & Z = 450mm.
d) Spindle Centre distance : 350mm.
e) Maximum Spindle Speed : 15000 RPM.
f) Maximum Spindle Torque: 51.3 Nm Max.
g) Maximum Spindle Power: 10.5KW Max.
h) Maximum Number of tools: 26 per Spindle (Total 52 Nos).
i) Pallet Indexing time : 3 Sec max (0-180 Deg).
k) Chip to chip time : 1.5 Secs (With adjacent pocket & std tool).
l) Tool to tool time : 0.8 Secs at 60Hz.
m) Compact Machine foot print : 1790mm(W) X 4000 (L) x 2600mm (H)