New-Concept, Two-Spindle Turning/Milling Center

Sept. 16, 2010
Simultaneous, independent 5-axis machining of bar stock to 65 mm on both spindles

At IMTS 2010, INDEX Corporation is introducing to North America a new concept in turning/milling centers, allowing the machine to accomplish complex machining on difficult materials in half the time that convention turn/mills still require. The new INDEX R200/300 turning/milling centers include two powerful motorized milling spindles and two movable work spindles that allow them to machine equivalent workpieces almost twice as fast as commercially available turning/milling centers that use only a motorized milling spindle. One motorized milling spindle and one work spindle are assigned to each other in two subsystems, one located above the other, permitting highly productive and flexible machining, including simultaneous and independent 5-axis machining of bar stock to 65 mm on both spindles.

The axis arrangement produces directional kinematics, which enables “comprehensive and complete machining,” according to the builder. Within the design the main spindle moves in Z, the sub-spindle in X and Z, milling spindle 1 (top) in X/Y/B, and milling spindle 2 (bottom) in Y/B. As a result the machine offers two independent subsystems, with exceptional stiffness and dynamic response. Workpieces can be machined efficiently and in parallel on the front and reverse sides.

The R200 can accomplish full reverse side machining as well as parallel machining. Both heavy-duty roughing operations and highly accurate fine-turning operations can be performed simultaneously on the main spindle and sub-spindle.

To ensure a high degree of thermal stability and vibration dampening to enable machining of difficult-to-cut and high-strength materials, the R200 has a vertical cast machine bed with a heavily ribbed, enclosed modular design.

Minimal chip-to-chip times
Two separate shuttle units independently load the two motorized milling spindles with the HSK-A40 tools required in each case from a common chain tool magazine. With 80 or 120 places, the INDEX R200 has an extensive tool stock. Short chip-to-chip times of approximately four seconds contribute significantly to minimizing secondary processing times. While machining is performed on the main spindle, the lower milling spindle can load a new tool, protected from falling chips and coolant. The results in high productivity and improves process reliability.

The two quill-guided motorized milling spindles are located in the center of the machine bed. This diagonal arrangement allowed the usual cross-slide to be omitted. When combined with the play-free and wear-free hydrostatic circular guide, an overall system with exceptional stiffness is produced.

The R200 exhibits high acceleration and rapid traverse rates due to the powerful drives and weight-optimized assemblies. Impressive key data, such as 11 kW power and 18,000 rpm, milling spindles as well as 0.9 s ramp-up time (0 to 5000 rpm) make possible the high-performance machining operations.

The generous B-axis swivel ranges of 270 and 230 degrees, and the rapid traverse rate of 45 m/min explain the machining flexibility and speed. The data for the identically rated work spindles in synchronous design include maximum power rating of 33 kW, maximum speed of 5000 rpm, and peak torque of 150 Nm.

Two linear tool carriers affixed to the side of each milling spindle allow fast, high-precision access to 6 stationary tools without a tool change. The exclusive INDEX W-toothing in the base of the toolholders minimizes the associated setup effort and ensures a force-locking and form-locking tool fit: this represents the optimum precondition for precise turning operations comparable to that of a turret. Bar stock is fed by a material guide channel mounted to be moveable in the Z-direction and permanently connected to the main spindle. The INDEX SBL (sliding bar loader) is designed for bar stock with a diameter of 20 to 65 mm and a length up to 3,000 mm. The large material bar stock supports unmanned operation of the machine.

The current INDEX C200-4D SL control is based on the field-proven Siemens Sinumerik S840D solution line and has been enhanced by INDEX with user-friendly functions. Specially developed cycles simplify the most complex machining operations. They support multi-axis milling and turning operations and provide maximum functional reliability.

INDEX VirtualMachine programming
The INDEX VirtualLine software packages support economical use of the new turning/milling center from the very first workpiece. These packages complement each other in terms of their functions and guide the programmer and operator to the right solution for the machining task: both on the PC during the preparation stage and directly at the machine in the factory.

In conjunction with the 3D simulation of the INDEX Virtual Machine, machining programs can be created, checked, and optimized on the PC. The CNC Programming Studio provides more advanced support for programming and operating the INDEX R200.

The INDEX R200 is also designed with advanced technologies to support energy efficiency requirements: weight-optimized components for reduction of energy consumption and for increasing the dynamic response; energy recovery by means of regenerative drives; energy shutdown of units that consume large amounts of energy after a user-defined time (standby mode); minimized friction based on optimally paired materials and low-friction bearings (hydrostatic circular guide); intelligent cooling principles for targeted cooling of the machine, economical use of waste heat, or climate-neutral heat discharge from the production hall.

The cooling concept of INDEX ensures that the spindles, hydraulics, and control cabinet are cooled constantly and that the heat can be fed to another useful application via a “water interface,” e.g., for service water heating or as process heat for other manufacturing steps.

“Enormous productivity benefits in milling and turning combined with maximum flexibility are the key advantages of the new INDEX R200 turning/milling center,” according to an INDEX representative. “This is achieved by means of unrivaled kinematics with two motorized milling spindles, two work spindles, four linear tool carriers, and a large tool stock with fast access. The innovative design and arrangement of proven components provide for maximum stiffness and optimum vibration damping as well as for optimum thermal and dynamic stability. This enables the INDEX R200 to deliver impressive machining results for challenging materials and machining tasks, up to and including 5-axis machining.”

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