Magic of the towers and pyramids

At first glance, it is unspectacular – but when you look closely, it is as diverse as hardly any other clamping device: clamping towers and clamping pyramids are considered mysterious, probably also because they change their face from machine to machine. When used carefully, they multiply the number of workpieces in the machine room and thus offer ideal conditions for reducing idle times and catapulting the unmanned machine runtime upwards with great flexibility – provided the clamping devices are carefully matched to this.

4-axis horizontal machining centers with integrated pallet change have always been the domain of clamping towers. The basic idea is always the same: the clamping tower multiplies the machine’s own clamping surface, so that high machine utilization is achieved and idle times are minimized. Cleverly planned, workpieces can be fully automated over a period of several days, for example in ghost shifts at the weekend. The same basic idea is followed by clamping pyramids, which have recently been particularly successful on 5-axis machines. With no concessions on accessibility, the unmanned machine runtime can be increased with them – especially if the loading is done from the machine’s own or external pallet stores. For good reason, the competence leader for gripping systems and clamping technology SCHUNK has been consistently expanding its clamping tower and clamping pyramid portfolio for years. The starting point is a comprehensive modular system consisting of basic pallets, basic profiles and clamping surfaces, which are combined with an impressive variety of clamping devices and can be used efficiently using a wide range of standard clamping jaws.

Eliminate non-productive times

The basic principle is simple: one or, ideally, several workpieces can be clamped on each side of the tower, which are then machined one after the other. With the help of modern CAD / CAM systems, it is possible in this way to produce even the smallest batch sizes down to individual parts with high efficiency. Setup is based on workpiece-specific setup plans, ideally outside the machine room at machine-own or external setup stations. The machine is then loaded with the clamping tower or the clamping pyramid using the machine’s own transfer systems, alternatively by crane or robot. Unproductive non-productive times such as reclamping, aligning or determining the zero point are consequently banished from the machine with the help of the towers and pyramids.

Vibration-damping hollow body construction

SCHUNK KONTEC clamping towers are usually constructed in one piece: The base plate and clamping column are made as a monoblock from cast EN-GJL-250 and, thanks to their stable hollow body construction, ensure high rigidity, good vibration damping and high basic accuracy, so that they no longer have to be milled over before use. They are available as standard with two base plate sizes (400 x 400 mm, 500 x 500 mm) for all common standard machine pallets type DIN 55 201 and JIS 6337-1980. In addition, individual interfaces are also possible. The perpendicularity to the base plate is 0.01 mm to 200 mm, the surfaces are finely milled and have a roughness of Ra 1.6. This ensures exact positioning of the clamping devices and workpieces. The clamping towers can be mounted quickly and precisely on existing machine tables via a centering Ø 50 H6.

Numerous variants

Tension towers and pyramids are available in a variety of versions and designs. The SCHUNK clamping tower range alone comprises five basic profiles: double angles with two clamping surfaces, triangles with three clamping surfaces, cubes or crosses with four clamping surfaces, and octagons with eight clamping surfaces. Another special form is the clamping pyramid, which enables multiple clamping on 5-axis machines with excellent accessibility and, not least because of the increasing number of machines with workpiece storage, is becoming increasingly important. The interference contours and thus the accessibility for the spindle and tools can be optimized by selecting the shape that suits the workpiece and the machining. The height of the standard tension towers is 710 mm or 1,000 mm depending on the variant.

Flexibility with the clamping surface and clamping devices

There are four options for the clamping surface: The 50 mm Hole grid creates a high degree of flexibility. It is suitable for holding a wide variety of clamping devices, but also for conventional clamping using clamping claws. The reduced grid, in turn, is specially designed for SCHUNK KONTEC clamping devices. In both cases, the grid holes are equipped with hardened fitting bushes and galvanized threaded bushes. With the help of dowel screws Ø12 / M12, the clamping devices can be positioned and attached directly to the tower. The third variant, a raw clamping surface, can be individually adapted by the user to the respective requirement. The fourth variant offers the greatest flexibility, namely the equipment with SCHUNK VERO-S NSE-T 138 zero-point clamping modules. These act as a quick-change system and allow a quick, high-precision clamping device change without complex screwing. Uniform SCHUNK VERO-S clamping bolts allow zero point clamping modules to be combined with a wide range of clamping devices from the SCHUNK standard range. This means that users benefit from a unique variety of different clamping modules, ranging from the power clamping block to manual single, double and multiple clamps to multi-jaw chucks. With the SCHUNK range of jaws and quick-change jaw systems, the clamping devices can be flexibly and quickly adapted to different families of parts, so that a high degree of individuality is guaranteed with the greatest possible precision and economy. Uniform SCHUNK VERO-S clamping bolts allow zero point clamping modules to be combined with a wide range of clamping devices from the SCHUNK standard range. This means that users benefit from a unique variety of different clamping modules, ranging from the power clamping block to manual single, double and multiple clamps to multi-jaw chucks. With the SCHUNK range of jaws and quick-change jaw systems, the clamping devices can be flexibly and quickly adapted to different families of parts, so that a high degree of individuality is guaranteed with the greatest possible precision and economy. Uniform SCHUNK VERO-S clamping bolts allow zero point clamping modules to be combined with a wide range of clamping devices from the SCHUNK standard range. This means that users benefit from a unique variety of different clamping modules, ranging from the power clamping block to manual single, double and multiple clamps to multi-jaw chucks. With the SCHUNK range of jaws and quick-change jaw systems, the clamping devices can be flexibly and quickly adapted to different families of parts, so that a high degree of individuality is guaranteed with the greatest possible precision and economy. Double and multiple clamps up to multi-jaw chucks are sufficient. With the SCHUNK range of jaws and quick-change jaw systems, the clamping devices can be flexibly and quickly adapted to different families of parts, so that a high degree of individuality is guaranteed with the greatest possible precision and economy. Double and multiple clamps up to multi-jaw chucks are sufficient. With the SCHUNK range of jaws and quick-change jaw systems, the clamping devices can be flexibly and quickly adapted to different families of parts, so that a high degree of individuality is guaranteed with the greatest possible precision and economy.

Tension tower systems – fully configured with clamping devices

In addition to this freely configurable module program, SCHUNK also has a large number of preconfigured clamping towers in its range, which are offered as a complete system including clamping devices. These tensioning tower systems usually include two or four stationary tensioners from the SCHUNK KONTEC range, which are configured as tensioning towers either as a monoblock or in combination with an EN-GJL-250 cast core. There is a choice of clamping tower systems from the KONTEC KSO single clamps in monoblock construction, from KONTEC KSC-D double clamps, from KONTEC KSM or KONTEC KSM2 multiple clamping systems, from modular KONTEC KSG machine vices and from spring-operated clamping blocks TANDEM KSF plus. The latter enable secure voltage supply without media supply and, due to their compact dimensions, are becoming increasingly important, particularly in storage solutions.

Application-specific special solutions

If the wide standard range is not sufficient, SCHUNK also implements application-specific special solutions, for example vibration-damped clamping towers made of gray cast iron GGG40 or clamping towers with optimized internal geometry, with which the clamping tower weight can be reduced. Highly rigid tensioning towers for demanding milling operations are also possible. Special tilting tables, on which the tensioning towers can be swiveled, rotated and loaded either upright or lying down, also enable particularly ergonomic loading.