Laser Beam and Water Jet Cutting

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1 Laser Beam and Water Jet Cutting Trumpf Increasingly, materials are being employed in aircraft construction that are innovative, extremely hard or difficult to cut and which can be machined with conventional chip removal or EDM only at high costs or in limited circumstances only. One alternative to conventional manufacturing processes is to use a laser. In contrast to conventional methods, the laser operates without contact, force-free and with no wear to tools. This technology can be utilized with geometric flexibility and with the highest possible precision and is independent of the hardness and conductivity of the material to be machined. Water jet machining has also been adopted by a large number of aircraft builders and suppliers. The strengths of high pressure are particularly apparent in the cutting of composite materials and temperature-sensitive light-weight metals. Aside from the classical chip removal cutting process, Siemens, as a supplier of control and drive technology, also plays a leading role in these technologies. In cooperation with the leading machine manufacturers of the industry, solutions have been developed based on the standard control SINUMERIK 840D which completely exhausts the potential of these machining technologies. Intro Laser Beam and Water Jet Cutting: Intro A01 A02 A03 A04 A05 A06 A07 A08 A09 A10 A11 A12 A13 A14 B01 B02 B03 B04 B05 C01 C02 D01 D02 E01 E02 E03 E04 A12-1

2 Requirements Laser beam cutting is a powerful, highly productive machining process which places especially high demands on process management and motion control. Typical workpieces for laser machining have many different size holes of varying shapes, as well as complex outer contours which require an exact, speedy adjustment of the jet to the actual situation of use. As in the case when milling very crooked contours with the laser, milling necessitates special machining strategies. Independent of the situation of use and path velocity, the laser power must be adjusted quickly and dependably. Decisive influence on the cutting result is exercised by the real time control of the clearance between workpiece and machining head which is to be constantly kept in the range under 10 micrometers. Productivity is enhanced by the capacity to continue a machining program after a disruption at the exactly cut contour with the same cutting parameters. For higher throughput when cutting regular contours, such as gratings with holes the manufacturers of laser-cutting machines currently use strategies in which the contour is divided into longitudinal and transverse sections. For this purpose, it must be possible to switch the laser beam off and on with extreme precision. Last, but not least, the movement control of the laser head must be equipped with progressive motion control functionality to arrive at an optimal result at highest possible path velocity, surface quality and contour accuracy. An intelligent motion control and feed control are also imperative for water machining to achieve optimal contours, e.g., during travel in curves. Many other requirements are similar to those in laser technology, e.g., resumption of machining following an interruption, without further adjustment. Trumpf Requirements at a Glance Laser Beam and Water Jet Cutting Intelligent motion control functions for the machining head Power control of the laser Retrace support for resumption of machining Quick switching of the laser Clearance control Motion control for water jet machining A12-2 Laser Beam and Water Jet Cutting: Requirements A12

3 Intelligent Motion Control Functions Intelligent motion control functions for the machining head Power Control Power control of the laser Solution The progressive functions of the SINUMERIK 840D are employed to reliably direct the movement of the machining head. Functions to control the velocity of the feed drives in the primary and auxiliary motion guarantee high contour accuracy with simultaneous high dynamic. Spline Interpolation, Look Ahead and Constant Path Velocity permit the maximum to be drawn from the technology and enable speedy accommodation to the changing requirements governing velocity, precision and quality of cut edges. Sharp edges are rounded off as defined with the aid of tangential transitions to prevent burn in the corners due to brief stopping. Precontrol algorithms and automatic quadrant error compensation are available in order to maintain the exact radius during round cuts. The SINUMERIK control permits the adjustment of laser power in three different ways and is therefore a control that can be used universally for all laser applications in aerospace machining. Laser power as a function of path velocity This function guarantees optimal process conditions during contour cutting. The laser power can be accommodated to the corresponding feed speed. Laser power as a function of time Both the laser power and the pressure for the auxiliary gases can be raised to enable the clean plunge cut into the thick material to be performed under time control. Laser power as a function of path length In a special situation such as the welding of materials with growing material thickness, the laser power can also be controlled as a function of path distance traveled or individual axis positions. Laser Beam and Water Jet Cutting: Solution A01 A02 A03 A04 A05 A06 A07 A08 A09 A10 A11 A12 A13 A14 B01 B02 B03 B04 B05 C01 C02 D01 D02 E01 E02 E03 E04 A12-3

4 Solution Retrace Support Retrace support for resumption of machining The technology function Resume machining Retrace Support (RESU) is a compile cycle which has as its purpose the ability to resume interrupted machining at a specific location of the machining program. A resynchronization is necessary, for example, if the cutting process is interrupted during laser beam machining and the machining is to be restarted at the point at which it was interrupted. It is possible to employ a block search run using the standard function Block search with calculation on the contour. This requires precise know-how of the machining program however, if it is to be possible to specify the block number of the machining program block required for the block search run. RESU supports repositioning on the contour as far as the selected resynchronization point via the following subfunctions: automatic determination of the parts program block belonging to the program continuation point block search run with calculation on the contour to the determined parts program block repositioning onto the contour at the continuation point continuation of machining program To move exactly to the required continuation point, the operator can also repeatedly change between reverse and forward on the contour. A12-4 Laser Beam and Water Jet Cutting: Solution A12

5 Quick Switching Quick switching of the laser Clearance Control Motion Control Motion control during water jet machining Solution High velocity laser beam machining and innovative cutting strategies require speedy switching of the laser beam with precise reference to the cutting path in the range of a few microseconds. The loadable compile cycle Fast Laser Switching Signal for SINUMERIK 840D switches the laser appropriately on and off at the right moment in accordance with the pertinent cutting mode and positioning mode. A positive or negative path offset can be programmed to compensate for the operating delay of the laser s drive circuit. The laser beam is switched when the programmed feed exceeds or drops below a specified threshold. As a loadable, optional Compile Cycle for SINUMERIK 840D, a clearance control can be integrated between machining head and workpiece so that the clearance is kept constant. Both in 1D and 3D applications, the clearance control has a highly dynamic response characteristic. The closed-loop characteristics can be optimized by the use of the high-performance NCU573 X which allows for even higher cycle time. With the aid of special NC commands it is possible to program various characteristics, such as The evaluation of various sensor characteristics, Voltage offset to adjust the clearance of the laser head, Closed loop gain, Reaction to a signal to immediately lift the laser head in case of a collision of the sensor. The function CC_VADAPT (Corner Velocity Adaptation) was designed especially for water jet machining. This function continuously reduces the feed to a programmed value before the cut reaches a corner and raises it back to the last value programmed after the corner has been turned. Basically, the jet is deflected opposite to the feed direction starting at the point at which it penetrates into the material and continues to do so until it exits the material. If a curve or corner is cut, the feed must be reduced in order to avoid contour damages at the cut edges, especially when cutting thick material. Laser Beam and Water Jet Cutting: Solution A01 A02 A03 A04 A05 A06 A07 A08 A09 A10 A11 A12 A13 A14 B01 B02 B03 B04 B05 C01 C02 D01 D02 E01 E02 E03 E04 A12-5

6 Benefit The complete potential of laser beam and water jet cutting can be obtained if the control technology is optimally attuned to this demanding technology. The high-performance NC control SINUMERIK 840D and the well-devised software expansions developed especially for the laser processes offer you: Safe, reliable process control Faster passes High productivity Safe production. More information Trumpf Functionality / Software Options with SINUMERIK 840D 2nd Additional Machining Channel and Maximum Memory Expansion 3D-Tool Radius Compensation Advanced Position Control Axial Coupling in Machine Coordinate System Axis Synchronisation, Gantry Axis Clearance Control Continued Machining at the Contour Corner Velocity Adaptation Cross-mode Action Dynamic Stiffness Control Electronic Gear Unit Evaluation of Internal Drive Variables Extended Stop and Retract (ESR) Fast Laser Switching Signal, Compile Cycle Generator Operation Interrupt Routines with High-Speed Retraction from the Contour Laser Clearance Control, Compile Cycle Laser Switching Signal, High Speed Machining Package 5-Axes, TRAORI Master/Slave for Drives Master Value Coupling and Curve Table Interpolation Measurement Level 2 Multi- Channel Sequence Programming NCU Link OEM-Transformation Oscillation Functions (block-related, modal and asynchronous) Path Velocity Dependent Analog Output Polynom-Interpolation Precontrol Acceleration Dependent Program Preprocessing Quadrant Error Compensation Retrace-Support, RESU-Compile-Cycle Safety Integrated Sag Compensation, Multi Dimensional Spline Interpolation for 5-Axis Machining, Compressor Synchronized Actions Level 2 (up to 255 parallel actions) Synchronous Spindle/Multi Edge Turning Temperature Compensation Trailing Axes (Trail) Transformation 7-Axes, OEM-Transformation Transmit/Peripheral Surface Transformation Travel to Fixed Stop with Force Control Volumetric Compensation Weight Compensation A12-6 Laser Beam and Water Jet Cutting: Benefit A12