Product category:
Machinery and Production Equipment
News Release from: StarragHeckert UK | Subject: Hermle C800 vertical machining centre
Edited by the Engineeringtalk Editorial
Team on 11 October 2001
Up to 40,000 revs/min on vertical
machining centre
The Hermle C800 mid-range CNC vertical machining centre has options of up to 40,000 revs/min spindle and is a gantry design which provides a far stiffer structure
The Hermle C800 mid-range CNC vertical machining centre, marketed by Traub Heckert UK Limited of Brackley, has options of up to 40,000 revs/min spindle and is a gantry design which provides a far stiffer structure in order to meet the high precision specification The machine design eliminates any spindle overhang typical of a C-frame machine construction and allows the table to be fixed
In this configuration all three main axes are achieved by moving the spindle and the relative motions are divorced from any influence of component weight and therefore become more predictable.
One of the drawbacks with a conventional gantry design using two guideways, a single servo drive motor and ballscrew drive, is the propensity to twist or crab.
This is caused by the high angular reaction generated on the bed guides due to the span between the guideways.
This becomes exaggerated by any off-set cutting force created whenever the path of the cutter is not in direct line with the feed drive.
Hermle's solution is a bed with three separate guideways, the third being central to and set back from the two outer guideways which, in effect, halves the span.
By placing a single drive unit in line with the central carriage on the bridge reduces the angular reaction force on the two outer guides to more manageable proportions, while forces on the central guide are vertical.
Another benefit of the C800's gantry style is a bed design with the guideway axes and drive components positioned outside and above the machining area.
As a result, contamination from swarf and coolant on the guideways is eliminated, while guarding of the guideways is simple and becomes very cost-effective.
The C800's bed is a mineral casting giving a low thermal expansion with excellent shock absorption.
Also, its single unit construction significantly reduces manufacturing costs.
Further, the black high quality appearance of the cast surface eliminates the need for painting, which is a significant cost factor in machine tool finishing.
The tool changer support on the C800 is positioned just behind and close to the spindle, negating the need for a change arm.
The 30 tool capacity disc magazine rotates in a horizontal plane and is driven by an AC servo motor through planetary gearing.
This design, plus the light weight, glass reinforced polyamide tool nests, results in a fast tool change time of five seconds chip-to-chip.
Tool exchange takes place through an opening in the rear of the machine.
Working volume is 800 mm by 600 mm by 500 mm and spindle power is 15 kW with 130 Nm high torque drive and high speed options up to 40,000 revs/min.
Control is via the high specification Heidenhain TNC 430 with direct measuring scales giving a resolution of 0.0001 mm and positional accuracy of 0.008 mm.
The C800's modular design allows it to be applied in different application areas.
The fixed table arrangement makes it easier to integrate a pallet change and additional fourth and fifth axes.
As a result, the C800 is available in three different types; the basic C800V is a three-axis machine with a fixed table, the C800P has twin-indexing pallets and the top of the range C800U, can be specified in several versions.
To meet customer specific tasks, the C800U can be ordered as a full five-axis machine with a two-axis trunnion table, as a four-axis machine with a four-sided clamping yoke that can hold multiple fixtures on each face or as a four-axis machine with a chuck and tailstock for machining rota-symmetric components.
• StarragHeckert UK: contact details and other news
• Email this article to a colleague
• Register for the free Engineeringtalk email newsletter
• Engineeringtalk Home Page
