About turning with SINUMERIK
Turning with SINUMERIK
CNC turning covers a wide range of applications. The complexity of the workpieces to be produced tends to decrease with batch size. On the other hand, the degree of automation is increasing.
In addition to basic turning functions, SINUMERIK CNCs offer extensive technology functions and automation interfaces for turning. They enable the efficient machining of complex individual workpieces as well as the mass production of simple parts. This article introduces the most important of these functions.
Just a few CNC functions to master turning processes
Just a few specific CNC functions that go beyond the basic CNC functions for path control are enough to allow the user to master the turning process. These include, for example, adhering to a constant cutting rate, that is, adapting the spindle speed while turning along the diameter axis.
A further core function for producing rotation-symmetrical components is tapping. For this function, the position-controlled tool longitudinal axis must be synchronized with the speed-controlled spindle. In addition to the G33 DIN language command, SINUMERIK CNCs offer a high-performance thread cycle. This cycle makes it possible to program any longitudinal, face, tapered or linked threads directly on the machine. Thread tables make it easy to input the thread pitch and depth. Further parameters control the linear or degressive feed to alternating thread flanks.
The SINUMERIK thread cycle
... enables simple parametrization of various thread forms. The fully graphical ShopTurn work-step programming is intuitive and simple.
DIN-ISO programming with programGUIDE
... offers maximum productivity with minimum machining times, thus meeting all production requirements.
Programming time as an important factor
The choice of CNC programming method depends largely on the size of the production batch. In individual-part production, the programming time is the factor that determines productivity. ShopTurn work-step programming offers very intuitive graphical programming. In mass production, in contrast, the program runtime is decisive. SINUMERIK CNCs can therefore also be programmed using DIN/ISO language commands. The cycle support (programGUIDE) forms a seamless transition between DIN/ISO and the fully graphical ShopTurn programming, making SINUMERIK CNCs a versatile solution for any batch size.
Contour turning: the supreme challenge
One of the greatest challenges of a turning control system is machining freely defined machining profiles without a CAD/CAM system. Machining profiles created with an integrated contour calculator are transformed from a machining cycle into the desired motion sequences. In addition to the classic longitudinal or transverse stock removal, the SINUMERIK stock removal cycle also offers contour grooving and plunge-turning options.
In many cases, however, a machining profile cannot be produced with one sheet size or machining strategy. The SINUMERIK cycle therefore offers the option to limit the machining segment, that is to say, to manufacture successively with the right machining strategy. The automatic detection of residual material transfers the adapted blank to each subsequent machining step.
The SINUMERIK contour cycle
... provides three fundamentally different machining methods: traditional stock removal, grooving and, as shown here, plunge turning.
Driven tools: Extended machining spectrum
With the use of driven tools, the machining spectrum of turning machines is extended to include drilling and milling operations. For the purposes of component accuracy, a machine with a y-axis is certainly the first choice. But with Transmit, which transforms the right-angled workpiece coordinate system to the machine x-axis and the position-controlled spindle, even machines without a y-axis offer the option of face machining.
With Tracyl, any contour can be produced on the lateral surface of the turned workpiece. To do this, the y-axis in the workpiece coordinate system is mapped to the rotation of the position-controlled spindle. In both cases, the CNC programmer can program in a right-angled workpiece coordinate system. This means that all machining cycles developed for drilling and milling can be used on the face and lateral surfaces of turned workpieces.
Programming with Tracyl
Part programming takes place in the Cartesian coordinate system. The Tracyl transformation generates movements from this in the machine coordinate system.
A prerequisite for five-axis machining is met
A b-axis can bring about a quantum leap in the application flexibility of turning machines. This rotary axis can be used to orient the inclination of the tool carrier. In conjunction with the position-controlled main spindle (c-axis), the prerequisite for five-axis machining is therefore met. As in milling machines, drilling and milling operations can be performed on workpiece planes swiveled at any angle. The SINUMERIK swivel cycle thereby facilitates the easy programming of the plane swiveling.
If all the machine axes have sufficient dynamics, free-form surfaces can also be machined with dynamic workpiece orientation. SINUMERIK 840D sl provides the required five-axis transformation with tool-center-point programming. If there is a turning tool in the milling spindle, turning operations can also be considered five-axis machining. The main cutting angle can be set with the orientation of the b-axis. In addition, the adjacent cutting angle, and thus the chip flow, is adjusted with the orientation of the turning tool in the position-controlled milling spindle. The tool length resulting from the two orientation angles is calculated automatically by the SINUMERIK swivel cycle.
The Cycle800 swivel cycle
... allows for the static positioning of turning tools in machines with a b-axis, thus ensuring the universal use of cutting inserts.
Greatly reduced machining time
To increase productivity, turning machines are equipped with several independent tool carriers. In conjunction with a counter spindle, this leads to a huge reduction in the machining time. In the CNC, every tool carrier is assigned to its own CNC channel with a separate CNC program. The CNC programs working in parallel must be built and synchronized with each other in such a way as to minimize waiting periods. This CNC program optimization quickly becomes a never-ending task. This is precisely where the SINUMERIK programSYNC function package comes in.
A multi-channel editor with synchronous program representation makes it possible to set targeted synchronization marks. The automatic calculation of the machining times of individual program sequences facilitates time management. Furthermore, programSYNC allows for the secure and user-friendly running in of individual tool carriers or machining spindles. On turning machines with two tool carriers, four-axis turning is also possible, that is, machining two tools simultaneously on the same machining profile. In addition to an increase in the chip volume at a constant insert load, the balanced cutting serves to balance out the cutting forces for long workpieces.
The SINUMERIK stock removal cycle allows for four-axis turning of user-definable contours. The tool path guidance strategy can be set with just a few parameters thanks to the intuitive operator control.
... enables the simultaneous and reliable simulation representation of machining operations in multiple CNC channels.
... of CNC programs for multi-channel machining operations is clear and facilitates the efficient programming of multi-channel applications.
Automated flow of parts
The final step in increasing productivity is automating the workpiece flow. In horizontal turning machines, bar loaders and parts catchers are used for this purpose. A special cycle in the ShopTurn work-step programming organizes the flow of parts between the main spindle and counter spindle in coordination with the bar loader. In vertical turning centers, workpieces are fed in and removed automatically by a transport system already integrated by the machine manufacturer.
A further possibility for automating the flow of parts is the use of a handling robot. Here, SINUMERIK 840D sl offers the highest possible degree of system integration. Manage MyRobot makes it possible to move the robot axes and perform teaching processes using the SINUMERIK control unit. The robot program sequence is also displayed in the CNC and can therefore be synchronized optimally with the CNC program sequence. The simple term turning thus encompasses a wide range of applications. With an equally wide range of technology functions and automation interfaces, SINUMERIK CNCs are more than up to the challenge of controlling modern turning machines.
The counter spindle cycle
... in ShopTurn facilitates the graphical interactive programming of the counter spindle, from simple support to automated workpiece flow.