Doosan introduces multi-purpose VMC with tilting headstock

By Niraj M Wanikar, Chief Editor, CNCTimes.com, 2015-11-30 11:04:20

Making its North American introduction at IMTS 2014 is the Doosan VCF850LSR, a vertical machining center featuring a traveling column design with a tilting spindle head. The VCF series is capable of machining a wide range of parts — utilizing up to five axes simultaneously.
The VCF 850LSR is a large capacity, travelling column design, Vertical Machining Center with a tilting B-axis head. This extremely versatile design allows for machining on multiple sides of a work piece at once. The head can rotate 110 degrees on either side of vertical, enabling the VCF 850LSR to machine large and complex parts in a single setup, eliminating costly fixtures and downtime. With its included 500 mm (19.685") rotary table, up to 5 sides of a part can be accessed, further increasing the machines capabilities.
B-Axis Tilting Headstock
The headstock is mounted to a rigid swiveling base which is driven by a heavy duty and high precision worm gear. This design allows the spindle to present tooling to the work piece at any angle between +110 deg to -110 deg from vertical, enabling machining on multiple sides of the work piece at once. The B-axis is capable of 900 ft-lbs of torque during contour machining or can be locked down by means of a hydraulic piston with 1,475 ft-lbs of torque for heavy duty cutting. Oil cooling around the assembly maintains constant temperature, regardless of the cutting condition, to ensure accuracy.
Built-in Spindle Motor
The powerful, 12,000 rpm built-in drive spindle motor has 18.5 / 22 kW (25 / 29.5 hp) and 147.25 nm (108.60 ft-lbs) of torque. This design promotes thermal stability and keeps vibration at higher rpm to an absolute minimum. A refrigerated cooling control system circulates cooling oil around the spindle in order to maintain a constant temperature, increasing accuracy regardless of the ambient temperature of the cutting conditions. The CAT 40 Big Plus spindle system is a true cartridge type unit supported by high precision, permanently grease lubricated ceramic ball bearings with a spindle Acceleration \ Deceleration time of 0 - 12k (1.3 sec) \ 12k - 0 (1.5 sec). An encoder is attached to the spindle to allow rigid tapping, further increasing productivity.
Traveling Column Design
All castings are made from fine grain Meehanite cast iron with heavy ribbing to help prevent vibration and deformation during heavy cutting. Extra wide spacing of the three roller guide ways that support the saddle, provide enhance rigidity. Featuring a superior, traveling column design; the table, and therefore the work piece, remains locked during machining. This design provides a uniform load to the guideways, ball screws and motors.
Roller-Type Guideways
All axes are Roller-Type Linear Motion Guideways offering superior stiffness, accuracy, and surface finish than more common Ball Bearing Guide types. They are both heavy duty (X - 45 mm \ 1.772", Y - 45 mm \ 1.772", Z - 45 mm \ 1.772") and widely spaced (X - 655 mm (x2) \ 25.787", Y - 720 mm \ 28.346", Z - 560 mm \ 22.047"). Roller guide ways are 3 times more rigid with 2 times more life than ball bearing guide ways and provide for optimal weight and force distribution.
Ball Screws and Drives
Each axis is driven by a high precision double nut ball screw which is centered between the guide ways and supported on both ends by angular contact thrust bearings. All ball screws are cooled by circulated, refrigerated oil at all critical components including the ball nut, support bearings and the motor housing. This system, coupled with a double pretension design, provides outstanding positioning repeatability with virtually no thermal growth. All axes have large diameter ball screws (X - 63 mm \ 2.480", Y - 50 mm \ 1.968", Z - 50 mm \ 1.968") that are directly connected to oversize A.C. servo drive motors without gears or belts in order to help eliminate backlash.
Rotary Table
The supplied Doosan D500 rotary table allows for machining on multiple faces of the work piece without having to re-fixture. This allows for reduced number of setups and much higher precision of the finished component. With 4 + 1 axes of simultaneous motion, very complex shapes are able to be produced, and when coupled with the machine’s ability to rotate the spindle head (+110 deg \ -110 deg), it is possible to machine 5 sides of a work piece in a single setup.
Doosan Infracore Machine Tools designs, engineers and manufactures the industry’s widest breadth of CNC machine tools. The company, which is part of the larger Doosan Group, continues to increase its competitiveness in global machine tools while establishing a firm foundation to become the Global Leader in the machine tools industry, assisting its customers in performance under pressure.

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