Workholding MetalTech Report: Riding high
- April 22, 2003
Modular clamp for five axis machinine
The Triag 5axes Clamp features what the company describes as a breakthrough clamping design that minimizes interference so machine spindles have full access to workpieces, even in high density applications in five axis machining. It combines the characteristics and performance of a dedicated fixture platform but is completely modular and can be retooled as needed.
The Unilock line of five axis workholding products are designed to provide flexibility and functionality for five axis machining and five-sided machining via multiple part transfers. These solutions are also for machines with retrofit 4th/5th axis tables.
The multi-axis workholding products locate and stabilize the workpieces without obstructing access to the top and sides of the part. They also allow a clamped workpiece to be flipped into new orientations for subsequent machining operations without unclamping it from the workholding.
The 5-Axis Duo Bridge, with Dual 45° 105/65 base plates, are integratable solutions that can be mounted directly on the top of a five axis table or loaded through a pair of zero-point chucks. Unilock’s 5-Axis riser chucks, extensions and reductions, with a working diameter of 80 mm, are available on base plates, or as stacking modules in heights of 75 mm and 100 mm. The adjustable First Grips and Dovetail Grips are only limited by the length of the thread that pulls the jaws together.
Hilma’s NC-series vises offer better performance to most standard vises, due to built-in hydraulics. With a few cranks of the handle, hydraulic pressure can be built up to 11000 lb of clamping force (on the largest size). Switch from clamping small to large parts quickly simply by pulling the pin on the NC vise, sliding the power unit back, and reinserting the pin. In three sizes, the NC vise is easy to maintain, has a repeatability of 0.0004 in. (0.010 mm), and comes with a clamp force indicating gauge for enhanced precision and repeatability.
Universal ball lock chuck
The newest version of the original UBL (universal ball lock) concept chuck is the N.A. Woodworth ABL featuring a “Quick-Lock” jaw mounting system along with a weight-reducing, non-metallic composite core that provides high strength with the advantages of low mass operation. The weight reduction and Q-C jaw system deliver secure, accurate workholding performance. The lightweight and quick jaw change chucks are available as three jaw, self-centering, or compensating systems and in sizes ranging from 160 to 460 mm (6 to 18 in.) diameters. A variety of machine mounting styles, plates and adapters are also offered to match virtually all major machine structures and designs.
The quick-change jaw design allows changeovers to be accomplished in under 60 seconds, ideal for low-volume, part-to-part runs and the frequent changeover requirements of job shop environments. The “Quick-Lock” no loose screw, style mount eliminates the need for master jaw sets,helping to minimize investment costs, tooling inventories and weight, yet is configured to provide high levels of precision, set-up ease, and excellent repeatability.
The low weight composite core construction—establishing an approximate 40 per cent weight reduction when compared to like capacity, conventional chucks—reduces power consumption for lower utility costs and “green” operations. Because of the chuck’s diminished mass, spindle life will typically improve as machine components are exposed to minimized wear and tear, resulting in reduced costs for maintenance, repairs and replacement parts.
Quick-change interface system
A new quick-change workholding system for turning centres, centroteX, allows change-over for any workholding device within five minutes or less while maintaining accuracies, claims the company. It eliminates the need for an operator to indicate the workholding system during change-overs and decreases machine downtime. The system has a flange plate fitted to the machine spindle along with a bayonet mount on the drawtube. The sub plate with chuck or fixture is mounted to this, rotated 15° and locked via quick-connect fasteners. The system can be mounted on any CNC machine and with most workholding or fixture device.
Sure-Grip power chucks are lever-operated, counter-centrifugal and dynamically balanced. The design has several advantages over wedge-type designs, claims the company. With the lever-operated system, the drawtube is connected to the jaws through a pivoting lever mounted on pins inside the chuck body. The lever system has reduced friction and increased mechanical advantage compared to a wedge-operated chuck for a given draw bar pressure. The lever system has reduced internal bearing surface over the wedge-operated closure, making it less sensitive to lack of lubrication. The design results in reduced wear on the operating cylinder, increasing component life.
In the counter-balanced chuck design, weights are incorporated into the actuating levers of the chucks at the opposite end of the fulcrum or pivot-point of the jaws. Centrifugal force acts upon this weight just as it does on the top jaws. Since the weight is at the opposite side of the lever from the top jaws, the upward thrust generated counteracts some of the jaw force loss. It means the counter-balanced lever design has more gripping force at high rpms than that of a non-counter-balanced style.
The major advantage of the Sure-Grip power chuck is the configuration of the drawtube that actuates the chuck. The chuck’s drawtube threads directly into the machine’s draw bar, and can be done in ten minutes or less.
Upholding 345 mm through-hole design
A new state-of-the-art rotary table design with a compact body exhibits a four times smaller footprint than conventional NCRT designs, with 440 pounds less weight distribution. Even with a significantly smaller body and lower weight, the TP530 upholds a mega through-hole design at 13.6 in. (345 mm), matching conventional NCRT’s without exceeding table load limitations. Unlike the larger 31.6 in. (803 mm) rotary tables, the TP530 features a low centre height of 12.2 in. (310 mm) and high Z axis clearance. This also provides a comfortable fit within most machines, rather than purchasing a new machine to fit around the rotary table due to excessive size. This through-hole model still upholds accuracy, withstands heavy cutting conditions and retains a high clamping force of 6100Nm /4,499 ft-lb.; which is a perfect design for machining large workpieces such as oil pipes.
Smaller vises for small part machining
Two new MaxLock five axis vise models feature a 2-1/2 in. (63.5 mm) and a 4-1/2 in. (114 mm) jaw width in addition to the present 4 in. (102 mm) jaw width model.
The new, smaller models are designed for precision small part machining. They are ideal for clamping parts for continuous five axis cutting motion of complex pockets, sculptured and contoured surfaces, and intricate 3D features with repeatable high precision.
The MaxLock has a self-centering design along with Kurt’s patented Anglock feature. They align parts in the vise and reduce part lift to a minimum by pulling parts down and holding them with maximum rigidity for close tolerance repeatability in all axes. Holding parts up to 6-1/2 in. (165 mm) in length (with machined jaws), these self-centering vise model sizes clamp both OD and ID. They feature an adjustable centre line. Their tall jaws provide increased spindle clearance and are machinable to include a “step” for eliminating the need for parallels. The jaws also are reversible, providing even more flexible clamping options.
The two new vise models have quick alignment features. They have SHCS for mounting and 5/8 in. (16 mm) dowel holes for fast mounting on risers using sine keys. They also feature auxiliary clamping slots for mounting flexibility.
Vice for five axis milling
The unique design of the Genius five axis vise maximizes clamp force at the top of the jaws by pulling them closed at the top with a collapsing lead screw, while holding the bottom of the jaws in place with an opposing force screw. Available from Lexair Inc., the dual-screw, pull-to-close vice eliminates the tendency of traditional vise jaws to splay apart at the top, which requires machine operators to hammer a workpiece down against the stops as the jaws close and clamp force increases. By holding the vise jaws apart
at the bottom and pulling
closed at the top, the Genius vise pulls the workpiece down against the stops as closing force increases. It is available in two sizes, capable of holding parts up to 8 in. (203 mm), with maximum clamp force of 9,000 lb (4000 kg).
The vise is designed for precision five axis milling with trunnion-table machines. It secures oddly-shaped workpieces and presents them to the spindle with minimal obstruction, reducing setups and ensuring repeatability of 0.0008 in. (0.020 mm).