FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
METHOD AND APPARATUS FOR SHEET METAL CUTTING BY FIBER LASER WITH LINER MOTOR
2. APPLICANT:
(a) ALP Multitech Pvt. Ltd.
(b) NATIONALITY: an Indian Company
(c) 4, Manichandra -I,
Near Surdhara Circle,
SAL Hospital Road, Thaltej, Ahmedabad - 380 054. Gujarat, India.
3. PREMABLE TO THE DESCRIPTION

PROVISIONAL
The following specification describes the invention.

COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

METHOD AND APPARATUS FOR SHEET METAL CUTTING BY FIBER LASER WITH LINER MOTOR
The present invention relates to a laser cutting method for cutting sheet metal using source of the fiber laser with liner motor.
In the present scenario, laser cutting using a laser source of the CO2 type to generate a laser beam with a wavelength of 10.6 m and power ranging up to 6 kW, is widely used in industry.
The present method is used in particular for cutting sheet metal. In the present invention CO2 laser is replaced by fiber laser. The present method has higher electrical efficiency without laser generating gas. The present invention method has higher cutting speed hence per hour cost is decreased by 2.5 times then that of CO2
However, the cutting speeds that can be achieved and the cutting quality that results are very variable, depending on the material to be cut and moreover depending on the cutting method parameters adopted, such as the nature of the assistance gas, the diameter of the focused beam, the power of the incident laser etc.
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Thus, C02 laser cannot be used with assistance gases of low-ionization potential, for example such as argon, without the risk of generating parasitic plasmas that could impair the method
Furthermore, CO2 laser are limited in terms of power, thereby directly impacting the cutting speed.
In addition, the fact of having to guide the laser beam from the laser generator right to the focusing head, that is to say the cutting head, has drawbacks, especially as regards alignment of the optics in the optical path. This is because guiding optics are generally polished and/or coated copper mirrors and their positions determine the path followed by the laser beam. Therefore, the alignment of the mirrors must be perfect in order to ensure optimum entry of the laser beam into the focusing head or cutting head. Now, the position of these mirrors is generally adjusted by mechanical means, which may easily go out of alignment according to the wear of parts and the environmental conditions, such as the ambient temperature, moisture content, etc.
In addition, the optical path of the beam must necessarily be kept in an inert atmosphere in order to avoid any contamination and to maintain a medium with a constant optical index, which is necessary for good propagation of the beam. These conditions make it possible for the properties relating to the beam diameter and the transverse distribution of
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the beam energy, and also the beam quality properties, to remain satisfactory for the method, the quality factor for beam parameter product (BPP) of the high-power C02 laser beams used in cutting generally being between 3 mm.mrad and 6 mm.mrad. Such an atmosphere also makes it possible to preserve the guiding optics and to prevent them from deteriorating.
However, this is not practical in an industrial situation, as it complicates the installation and incurs additional costs.
To overcome such limitations the present invention relates to METHOD AND APPARATUS FOR SHEET METAL CUTTING BY FIBER LASER WITH LINER MOTOR is invented.
The present invention is described with greater specific and clarity with reference to following drawings:
Fig. 1 Side view of sheet metal cutting by fiber laser with liner
motor
Fig. 2 Top view of sheet metal cutting by fiber laser with liner
motor
Fig. 3 Front view of sheet metal cutting by fiber laser with liner
motor
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Fig.4 graph of laser cutting speed with thickness of 2k fiber laser
Fig.5 Comparison graph for C02 and fiber laser cutting speed with
thickness
Fig. 6 front view of liner motor
Fig. 7 Laser cutting cost charge for Laser source.
Many of solid state lasers are configured to operate near the diffraction limited beam performance to maintain a very small kerf width. In order to meet yields and up-time requirements reliable laser operation and low maintenance are required. The fiber laser concept could provide benefits in order to maintain high up-time and high yields. The single mode fiber laser does not need mirror alignment. Diode pumped fiber laser also reduce maintenance as flash lamp changes are eliminated. Flash lamp pumped ND:YAG is an established tool for micro-cutting applications, certain resonator designs achieve the beam quality and pulse power levels required for micro-cutting applications. However there are several disadvantages of conventional flash-lamp pumped solid state laser such as low wall-plug efficiency, high running costs and poor thermal stability. Significant improvements have been made in order to improve the thermal stability but most conventional lamp-pumped laser systems on the production floor still requires a high level of maintenance
Now it is proven that Single mode fiber laser is an efficient, reliable and compact solution for micro machining. Since overall efficiency is high,
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most fiber lasers are powered by a standard 110V supply. Average power levels upto 100W are possible with air-cooling.
Fiber laser cutting system consists of CNC motion system, fiber laser source, beam collimator and cutting head. Cutting head includes a focusing optic and an assist gas nozzle.
The principle of operation of a synchronous liner motor is based on a conductor, through which current flows, when this conductor is then placed in a permanent magnetic filed force is exerted on it which causes it to move. The closed loop control system comprising CNC control, servo controller and sensor system ( liner Scale) transforms this into a precision positioning drive system. The motors consist of primary section (1) and a secondary section is made up of individual elements (segments) to suit the traversing range. Through parallel operation of the motor. Force and length can be scaled beyond the available spectrum. Ballscrew system Vs. Liner Motors: Liner motors offer enhanced dynamic response and speed significantly velocities up to 300m/min and acceleration of up to 45g are theoretically possible. In Practice, today's machines already reach federates of lOOm/min and accelerations of 1.5g. Following is the typical benchmark test result comparing ball screw system and liner motor.
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The present system comprises of 20W to 10000W laser source. Laser has variable parameter of laser power from 10 % to 100%. This power variation can be done on process by CNC controller through analogue port 0-10 power variation feature. Laser power can be varied offline or can be part of ongoing process i.e. for on process it is by G-code of CNC system also.
This feature will make possible to cut small thickness of sheet metal. Modulation of power will make piercing cycle efficient.
Laser power can switch on/off by 24V signal. It is interfaced with CNC M-function (high speed i/o) so, that it can be offline & online with help of programming. By modulation of variable frequency and pulse width, this input can make piercing cycle smooth also. Simultaneously, it synchronies different thickness with contour of small to big shapes with good cutting quality, less distortion and heat affected zone.
From laser source to sheet metal (i.e. workpiece), laser beam is delivered by fiber of 50 /100 /150 / 200 micron with the help of collimator of 40x / 60x / lOOx / 120x. So that beam diversion is reduceo) and beam coming out from collimator would be of 5-mm to 20-mm collimated. This collimated beam is focused on workpiece by different focusing lens (50mm-400 mm focal length) according to spot size and depth of field required. This makes possible to cut variable thickness.
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Fiber[E], collimator and lenses are mounted on a capacitive focusing head that kept on Z-axis[C]. Z-axis travel range is from 50mm - 500mm. Z-axis is close loop controlled by stand off distance adjustment capacity of focusing head electronics. In auto cutting mode, the focusing will be automatically controlled by height sensor (capacitive), CNC system and Z-axis.
X & Y-axis [A and B] Gantry, mounted with linear (magnetic) motor and LM guide having max speed of 250 mt/min at 3 G or more moves laser cutting head fast which makes positioning and cutting process fast. X & Y linear motor is selected with suitable torque, speed, acceleration and gantry load.
Sheet metal can be mounted on a flexible table independent of X & Y axis. Auto sheet loader or shuttle table controlled by CNC system can be used for sheet metal mounting. Auto sheet loader and shuttle table are driven either by hydraulic or by electrical actuator driver. The flexible table is replaced by hydraulic or rack & pinion or chain-drive mechanism.
Fiber laser cutting system has no or low maintenance as compare to CO2 laser cutting. The Fiber laser cutting system has no internal or external optics. The fiber laser cutting system running with very low cost. The
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fiber laser cutting system has higher cutting thickness with same power and higher cutting speed with same power & thickness. The fiber laser cutting system is easily integrated for 3D cutting.
Fiber laser system is used in the field of micromachining, thermal printing, engraving, cutting, drilling, welding and sintering.
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We Claims:
1. METHOD AND APPARATUS FOR SHEET METAL
CUTTING BY FIBER LASER WITH LINER MOTOR
comprises of 20W to 10000W laser source wherein laser has variable parameter of laser power from 10% to 100% and laser power can switch on/off by 24V signal, Laser beam delivered by fiber of 50/100/150/200 microns with the help of collimator of 40x/60x/100x/ 120x and focused on workpiece by different focusing lens with 50mm to 400mm focal length.
2. METHOD AND APPARATUS FOR SHEET METAL
CUTTING BY FIBER LASER WITH LINER MOTOR as
claimed in claim 1 wherein power variation can be done on process by CNC Controller through analogue port 0-10 V power variation features.
3. METHOD AND APPARATUS FOR SHEET METAL
CUTTING BY FIBER LASER WITH LINER MOTOR as
claimed in claim 1 wherein laser power is varied offline or be a part of ongoing process i.e. for on process it is by G-code, m -code of CNC system.
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4. METHOD AND APPARATUS FOR SHEET METAL
CUTTING BY FIBER LASER WITH LINER MOTOR as
claimed in claim 1 wherein fiber laser source, collimator and lenses are mounted on a capacitive focusing head that kept on Z axis.
5. METHOD AND APPARATUS FOR SHEET METAL
CUTTING BY FIBER LASER WITH LINER MOTOR as
claimed in claim 4 wherein Z axis travel range is form 50mm-500mm.
6. METHOD AND APPARATUS FOR SHEET METAL
CUTTING BY FIBER LASER WITH LINER MOTOR as
claimed in claim 5, in the auto cutting mode the focusing will be automatically controlled by height sensor (capacitive), CNC system and Z-axis.
7. METHOD AND APPARATUS FOR SHEET METAL
CUTTING BY FIBER LASER WITH LINER MOTOR as
claimed in claim 1 wherein X-axis and Y-axis of Gantry, mounted with liner (magnetic ) motor and LM guide having Max speed of 250mt/min at 3G or more moves laser cutting head fast which makes positioning and cutting speed fast.
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8. METHOD AND APPARATUS FOR SHEET METAL
CUTTING BY FIBER LASER WITH LINER MOTOR as
claimed in claim 7 wherein X & Y axis liner motor is selected with suitable torque speed, acceleration and gantry load.
9. METHOD AND APPARATUS FOR SHEET METAL
CUTTING BY FIBER LASER WITH LINER MOTOR as
claimed in claim 1 wherein sheet metal can be mounted on a flexible table independent of X & Y axis.
10.METHOD AND APPARATUS FOR SHEET METAL CUTTING BY FIBER LASER WITH LINER MOTOR as
claimed in claim 1 wherein auto sheet loader or shuttle table controlled by CNC system can be used for sheet metal mounting.
11.METHOD AND APPARATUS FOR SHEET METAL CUTTING BY FIBER LASER WITH LINER MOTOR as
claimed in claim 10 wherein auto sheet loader and shuttle table are driven either by hydraulic or by electrical actuator driver.
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12. METHOD AND APPARATUS FOR SHEET METAL CUTTING BY FIBER LASER WITH LINER MOTOR
substantially herein described with reference to the foregoing description and the accompanying drawings.

Date this on 26th July 2007


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ABSTRACT
METHOD AND APPARATUS FOR SHEET METAL CUTTING BY FIBER LASER WITH LINER MOTOR system has no or low maintenance as compare to CO2 laser cutting system. The Fiber laser cutting system has no internal or external optics. The fiber laser cutting system running with very low cost. The fiber laser cutting system has higher cutting thickness and higher cutting speed with same power. The fiber laser cutting system is easily integrated for 3D cutting. Fiber laser system is used in the field of micromachining, thermal printing, engraving, cutting, drilling, welding and sintering.