With the CNC automatic lathe TNK42, developed for high productivity and precision, TRAUB GmbH & Co. KG replaces the previous TRAUB TNK36, extending the successful CNC sliding/fixed headstock automatic lathes of the TNL18 and TNL32 series with a fixed headstock lathe in the larger diameter range. The user-friendly production control TRAUB TX8i-s and the use of innovative and field-proven components combine to allow the production of both typical turned parts up to 250 mm in length and of geometrically complex workpieces in large and medium volumes.
The compact machine design of the TNK42 on a footprint of approx. 5,5 m2 (without bar loader) and with up to 3 simultaneously working tool carriers not only ensures high productivity, but also provides a high performance density with a main spindle of 42 mm bar capacity and a swivel counter spindle for extensive rear end machining.
The CNC turret indexing axes (H-axes), already known from the TNL series, and the standard interpolated Y-axes combine to allow significant increase in productivity and time savings for the complete machining of workpieces.
Y functionality for both tool turrets
The “interpolated” Y-axis known from the TNL series is also used for the TNK42 on the two turrets. The Y-axis is formed by the interpolated movement of the CNC turret indexing H-axis and simultaneously by the C-axis of the work spindle as well as the X-axis of the tool carrier. Through the combined motion in conjunction with a powerful tool drive (with max. 5 kW / 8 Nm / 12,000 rpm), the TNK42 provides a large Y-travel of ± 50 mm = 100 mm for all turrets, e.g., to mill surfaces and grooves on workpieces, to drill axis-parallel off-center holes, and to realize off-center deep-hole drilling. With effective programming, the travel paths for selection and removal of tools can be optimized. The high precision and rigidity of the Y-axis is ensured by high-resolution incremental encoders on the C-axis and by the H-axis integrated in the turret, in conjunction with stable position control.
Upper tool carrier with tool turret (10 stations, X=140 mm, Z=300 mm)
The precision of the workpieces is ensured by a direct measuring system in the X-axis. All stations in the upper turret can be equipped with live tool holders on the TNK42. Turret indexing is designed as an NC rotary axis with a direct measuring system without mechanical lock, thereby allowing fast positioning of the turrets at any angle. This allows multiple tool assignments at each station, so that the upper tool carrier can be equipped easily with up to 20 tools. By eliminating the mechanical lock, short chip-to-chip times of 0.4 seconds from station to station can be realized. As with the TNL32, the TNK42 is also available with the optional “Dual Drive” system for the upper turret. This tool drive system has two separate drive trains to ramp up the speed for the next tool while still cutting with the current tool. The new tool is then indexed to the machining position at full speed. This not only reduces secondary processing times, the live tool holders also experience a significantly longer service life.
Dual function of the lower X/Z slide
Apart from its function as a lower tool turret with 9 stations – as on the TNL32 – the lower cross-slide with travels of also X = 140 mm and Z = 300 mm also serves as a swivel counter spindle for rear end machining of workpieces. The swivel movement of the counter spindle is achieved via the CNC turret indexing axis (H-axis). The TNK42 thus provides a counter spindle with a C-axis that can be moved in three axes (X/H/Z), allowing unrestricted counter spindle machining at 7,000 rpm and 42 mm spindle clearance as well as 12 kW (25% DC) drive power and 22,5 Nm (25% DC) torque. The counter spindle also allows the machining of parts with a chuck diameter up to 110 mm. Alternatively, hollow clamping up to 200 mm clamping depth or the attachment of mandrels can be realized. For extensive rear end machining, 8 tool stations are available which can accommodate the same tool holders as in the turret tool. Five of them can be used for live tools at a speed of max. 6,000 or 12,000 rpm and a torque of up to 8 Nm (25% DC) at 5 kW (25% ED) drive power. Two stations with stationary tools are suitable for simultaneous centric machining on the counter spindle as well as in parallel with the 2nd tool turret on the main spindle.
Dynamic main spindle
High cutting performance is ensured by the rigid and precise work spindle with C-axis and a power of 29 kW (40% DC) at up to 7,000 rpm. With a spindle clearance of 42 mm for bar work, the TNK42 also allows the use of chucks up to 110 mm in diameter at a torque of 65 Nm (40% DC).
Tool mounting system
The tool holder system of the TNK42 is compatible with the compact shank system known from the TNL32. With a diameter of 45 mm, this system offers the known robust and accurate mounting of tool holders in the turret and the back working attachment. The tool holders are seated deep in the tool carrier, which results in less leverage effect and, thus, higher stiffness. For live tool holders, the large shank diameter enables insertion of roller bearings with large diameters. This increases the performance and life of the tool holders.
Fast and gentle workpiece removal
Workpieces are removed fast and gently by a CNC-controlled shuttle. In parallel to the upper turret working on the main spindle, the counter spindle switches from the turret’s axial effective range and moves to the right to the transfer position to the workpiece gripper. There, the finished part is taken over by the workpiece gripper of the shuttle unit during secondary processing time and placed without damage on a timed part removal conveyor outside the machine.
Practical user benefits
The vertical design of the machine with a setup-friendly work area not only provides good conditions for unobstructed chip flow but also significantly better ergonomics which facilitates setup operations. The basis for this is a vertical cast machine bed with a highly ribbed, enclosed modular design that is mounted on a heavy machine base. A total weight of 6.5 t and the associated vibration damping are the basic requirements for high-precision machining of difficult-to-cut and high-strength materials. Although even long workpieces (up to 250 mm) can be manufactured on the TNK42, the machine with a footprint of only 4,070 x 1,380 mm needs only approx. 5,5 m² of floor space (without bar loader). Furthermore, all functionally important elements such as the headstock, tool carrier guides, gear drives, and workpiece removal unit are mounted on the machine bed, providing the basis for high quality of the machine geometry. The distance from the upper tool carrier to the spindle center is exactly the same as the distance of the lower tool carrier, resulting in the thermo-symmetrical structure of the machine. The thermo-symmetric headstock, low projection of the tool holders and thermal insulation to the machine further contribute to the precision. Instead of intensive-care telescopic plates, a one-piece sheet metal is used for the vertical inside cover of the work area in X and Z. The work area is easily accessible to the operator by its generous sliding door.
High manufacturing precision with elaborate cooling concept
The symmetrical design, the vertical arrangement of the work area, the actively cooled main spindle, glass scales in the X-axes, and the hydraulic-free (cold) technology of the turrets with direct measuring systems in the turret indexing axes ensure high temperature stability of the machine. Lost heat that is generated in the spindles, the control cabinet and the hydraulic unit is dissipated from the machine by a central fluid circuit. A water interface integrated into the TNK42 allows two solutions to heat dissipation: either connecting to a local cooling unit or to a central system. By cooling off the production area and by eliminating the traditional fans, noise and heat emissions in the machine environment are reduced to a minimum.
The CNC control for use in the field – TRAUB TX8i-s
The CNC control TRAUB TX8i-s tailored to the TRAUB TNK42 is designed based on the TRAUB TX8i series and combines performance with high reliability. Your advantage: It is possible to use the components of the proven TX8i series. Customer requirements and user needs could therefore be optimally considered and incorporated into the development. Data is displayed on a 15-inch LCD display and is entered directly via a separate ASCII keyboard. A 64-bit RISC processor and an additional PLC high-performance processor provide fast data processing and support short production times. The well-known TRAUB programming convenience was also implemented in the TNK42 and is fully available. Furthermore, all expansion levels of the popular TX8i control are optionally available. For example, the proprietary WinFlexIPSPlus programming system can be used on an external PC/notebook or directly on the machine. Installed on the machine, WinFlexIPSPlus provides the added safety of 3D collision protection in manual mode and during setup of the machine. Also for programming, the control used is fully compatible with the TX8i series. A philosophy that represents a tradition at TRAUB: Since the launch of the TRAUB control TX8 over 30 years ago, the principle of user-friendly upward compatibility of the CNC control has been continuously and consistently maintained at TRAUB.
Source INDEX-Werke GmbH & Co. KG