Turning larger parts and machine shops’ need to speed finishing times are two trends addressed by Doosan with its introduction of four new turning centers in its Puma GT series: the Puma GT2600, GT2600M, GT2600L, and GT2600LM now join the Puma GT2100 and GT2100M, introduced in late 2013. The new machines’ distinguishing features include a ridged, 30° single-piece slant-bed design, box guideways, a non-lifting servo-driven turret, and EZ Guide conversational programming system.
Turning larger parts is possible with the GT series, which has a standard chuck size of 10 in. (a 12-in. option is available, too), with a maximum swing-over-bed of 24.8 in., and swing-over-saddle of 18.1 in. The turning length is 25.9 in. on the standard Puma GT2600 and 24 in. for Puma GT2600M. On the long-bed versions, the turning length is 42.4 in. on the Puma GT2600L and 40.6 in. on the Puma GT2600LM. On all four models, the maximum bar-working diameter is 3.2 in.
Box Guideways — Box guideways are applied to all axes to increase dampening and rigidity, and providing a reliable platform for taking deep, powerful cuts. The Puma GT’s 30° single-piece, slant-bed design reduces the center of gravity for the spindle and cross slide by 12%. This minimizes thermal expansion, and improves the system ergonomics for operators. Rapid travels: 945 ipm (X-axis) and 1181 ipm (Z-axis.)
Powerful Spindle — The spindle design features three angular ball bearings in the front and cylindrical roller bearings in the rear, minimizing thermal expansion and increasing precision. The optimized spindle overhang design has minimized the rotational inertial load, enhanced rigidity, and reduced acceleration/deceleration time. The spindle motor is rated at 30 hp, with a maximum spindle speed of 3,500 rpm, and maximum spindle torque of 459 ft. lbs.
Turret and Driven Tools — Turret indexing times are lightning fast on the Puma GT2600, due to a servo-driven, non-lifting design, with a high torque motor. Also, the new design is more reliable than previous version, with 53% fewer moving parts. There are 12 tool stations: size, 1.0 x 1.0 in.; maximum boring bar size, 2.0 in. for the Puma GT2600 (L), 1.5 in. for the Puma GT2600M(LM); turret indexing time, 0.15 sec.
Puma GT2600M and GT2600LM feature a BMT55P top plate that secures each tool with four bolts and keys to provide powerful machining performance with high efficiency, high rigidity, and a high precision internal drive system. A bevel drive gear and air /oil cooling deliver low heat generation, minimizes thermal growth, while providing silent vibration free performance. Rotary tool speed is 5000 rpm with a 7.5-hp rotary tool motor.
Easy Operation Panel — The operating console features a Doosan-Fanuc i control with a 10.4-in. color TFT LCD monitor, with USB port, PCMCIA Card, embedded Ethernet connectivity, and full QWERTY keypad. Several single-touch Hot Keys are available to simplify set-up and operation. For more convenience, the pendant is designed to swing 88°.
Doosan’s EZ Guide i is a standard feature, offering shop floor conversational type programing. Roughing, finishing, castings, grooving, threading, peck drilling and more are all accomplished through EZ Guide’s menu-driven functions. Programs are generated easily using cycles instead of long hand code.
Further, the new Puma GT2600 is easier to load. The distance from front cover to spindle center is reduced from 17.2 to 15.3 inches. According to Doosan, for a machine with similar specifications, the new Puma GT2600 series are 14-25% more compact than the previous models — which affects shop performance because of the value of production floor space.
The Puma GT2600 guarding has been designed to provide easy access for adjustment, maintenance and service. The chip conveyor is designed to bolt directly to the machine so that the chip pan and coolant tank slide out independently. This design eliminates coolant leakage and makes it easy to access and clean the tank. The tail stock guide ways on the new Puma GT2600 series are covered and fully protected from chips. This eliminates the ongoing cleanup time required on previous models.
Energy savings are achieved thanks to a 23% more efficient hydraulic unit. An LED work light being used now lasts 10 times longer than the previous halogen type, and generates little heat. This helps to keep the work area a little cooler and thermally stable. LED lights also consume much less energy. Auto power-off functions further reduce power consumption and heat.