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METALLICS I MACHINING
There are currently two variants in
the SPC range: the 4-axis 7120 and 7140 models, with the main difference being capacity. The 7120 has a machining volume of 1,200mm x 900mm x 1,200mm in X, Y and Z whereas the 7140 offers a larger 1,450mm x 1,100mm x 1,300mm. 5-axis versions are to be launched at this month’s IMTS exhibition in Chicago.
Titaninum Technology Days: SIP’s Jean-Daniel Isoz shows off the new SPC
for lower cost manufacturing by use of increased productivity and are frequently questioning whether they require such high tolerances on certain parts,” adds SIP managing director Jean-Daniel Isoz. “That trend is quite new compared to the automotive industry but we need to be able to offer this functionality.” With production taking place at SIP’s
temperature controlled Geneva facility, each machine undergoes around 200 hours of hand scraping with the base, linear guideways, ballscrews, spindle heads and axes all treated, offering as close to perfect geometry as possible for long-term precision. There has also been extensive
design consideration given to thermal management throughout the machine, with the use of additional thermal shields to improve isolation from heat sources, temperature and elongation sensors in key components, active coolant temperature compensation and controlled cooling of the direct drive rotary table, spindle gearbox and ballscrews. A thermosymmetrically designed bed ensures that the weight and mass of components each side is closely matched allowing for even expansion across the machine and an air stream barrier helps to prevent build-up of air between the floor and the interior.
Building a beast The other major piece of product news at the event was the new horizontal BTP (Big Titanium Profiler) 5000/2, one of the largest machines ever to be produced by the company and available with one or two fully independent spindles, effectively doubling capacity for long, thin aerospace parts such as stringers, engine pylons and control surfaces. Weighing in at 200 tonnes, the machine has spent four years in development and over a year to build, requiring 15 trucks to deliver. The machine can deliver strokes in the single spindle version of 5,000-6,000mm in X, 2,000mm in Y and 1,200mm in Z, with ±100˚ in A and 360˚ rollover in B. Although StarragHeckert typically
offers both gear and motor spindles for its machines to meet individual requirements, the BTP range uses only gear spindles for several important reasons. “While the purchase cost is identical,” expands Brinken, “overhaul on a gear spindle is usually $40,000- $60,000 whereas for a motor spindle it can be $20,000k-$300,000 because the bearings are very expensive. Motor spindles also have to go back to the manufacturer and can take several weeks to repair. More significantly though, there is an EU eco design directive coming for machine tools. We are not sure when exactly but it will be in the next few years, basically meaning that high electrical consumption components will no longer be acceptable.” Key features of the machine are the
37kW gear driven spindle developing 940Nm of torque and achieving up to
8,000rpm spindle speed, and a steel on steel worm drive A-axis with constant gear driven torque. Hydraulically supported twin ballscrews on all guideways yielding maximum stiffness and minimising wear, sturdy machine structure and heavy-duty drive motors have all been designed to ensure vibrations are minimised, maximising tool life and allowing for maximum chip removal. Automation has also been a prime consideration, with a double pallet changer available, capable of lifting up to 18 tonnes unbalanced. Important also for machines of this
size is thermal management, which has been extensively developed. The bearings of the gearbox, power train spindle and vertical slide are all catered for by a compressor cooling circuit, the column and Z-bed using process coolant adapted to the machine temperature. A unique patented flexiture system ensures parallelism between the spindle and workpiece sides of the machine to dial out inaccuracies. Having already designed and produced
the first BTP 5000/2 machine for a major aerospace OEM, the company is convinced that the efficiency of the horizontal dual spindle design will be of real benefit in allowing for larger and
more ambitious component designs. ❙
www.starragheckert.com
Dr Frank Brinken: CEO, StarragHeckert Group
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