The trend towards automated loading of machine tools continues. This also affects the clamping technology: clamping devices are being increasingly tailored to the requirements of unmanned processes. In addition to process reliability, accessibility, flexibility, as well as energy and cycle time efficiency are also gaining in importance. Technology studies go even further: tomorrow’s smart clamping devices will enable intelligent networking with the machine tool and the handling systems.
Additional effects for variance, cycle times and energy efficiency
For the power chuck ROTA NCO, for example, SCHUNK has developed a special jaw quick-change system that enables manual, tool-less jaw change in less than a minute with a repeat accuracy of up to 0.02 mm. Using different standard jaw sets and individually configured special jaws, a large part variance can be covered by automated loading with minimal set-up times. SCHUNK is now even going a step further and is installing its first applications with fully automated jaw change, dispensing with the need for any operator intervention. The handling system then not only takes on the loading of the lathe chuck, but also the changing of the clamping jaws, either on a single jaw-for-jaw basis or a complete jaw set at once (particularly efficient).
A different approach is taken by the SCHUNK ROTA NCE lightweight lathe chuck, which has been trimmed for maximum efficiency in large series production and can also be loaded automatically It combines the aspects of lightweight construction, maximum load capacity and a large drill hole in a single lathe chuck Compared to conventional lathe chucks, the inertia has been reduced by up to 40% depending on the size. Consequently, the lathe chuck can accelerate and decelerate much faster than conventional power chucks. Especially in large series production, the reduced mass results in shorter cycle times and reduced energy consumption. SCHUNK pursues a similar strategy with the specially sealed, low-maintenance power chuck ROTA NCA, which has also been reduced in weight and, thanks to its special geometry, enables good accessibility, especially on modern lathes/milling centers. With its large through-hole, this energy-efficient and cycle-time-efficient chuck is also perfect for automated bar loading.
SCHUNK TANDEM plus clamping force blocks are specially designed for the requirements of automated machine loading. In this lean automation solution, they are combined with a SCHUNK VERO-S NSL plus clamping station and loaded via the machine’s own axes.
High clamping repeat accuracy during automated operation
In addition to power chucks, especially in the case of high-precision, circular stresses, hydraulic expansion solutions also have their advantages in automated loading (e.g. in generating grinding, milling cutting, slotting, turning and planning, but also in balancing, measuring and testing). Slim hydraulic expansion tools with the SCHUNK patented axial pullback, for example, are an effective solution to minimize set-up times with the highest accuracy and to save additional costs. They center and clamp the workpieces within a very short time with a repeat accuracy < 0.003 mm per interface. In addition, the axial pullback ensures a completely flat work surface, whereby the workpiece is axially pulled to the flat surface by a membrane. This prevents even the smallest tube imbalance and provides high stability during machining. As the hydraulic-expansion technology centers precisely on the center of the axis, processes can be fully automated with the shortest cycle times, without the need for measuring cycles. Upon request, there are lathe chucks or expansion arbors that are always produced on a workpiece-specific basis and equipped with a second hydraulic transfer and an air connection to enable contact monitoring.
For small and medium-sized lots, the SCHUNK VERO-S NSA plus palletizing system ensures high process reliability, flexibility and efficiency.
The SCHUNK TANDEM plus clamping force blocks are specially designed for automated machine loading. With their square base and compact dimensions, the vises enable a dense arrangement so that the largest possible number of workpieces can be clamped and processed at all times. In the spring-action variant, the vises are ideally suited to be prepared for tombstones and clamping pallets, to be stored in a workpiece storage and simultaneously to be loaded into the machine for processing. The optimized outside contour, a special design of the base jaws as well as covering strips, minimum clearance and cover plugs for the fastening screws prevent dust pockets from forming or chips and dust from getting into the vises and settling there permanently. During automated operation, the vises can be actuated either pneumatically, hydraulically or by spring-action with a clamping repeat accuracy of up to 0.01 mm. With the standardized long stroke versions, it is also possible to clamp different component sizes or to bridge interfering contours. Inductive proximity switches enable continuous process monitoring.
SCHUNK KONTEC KSM multi clamping vises enable many different clamping solutions for serial parts and can be set up quickly and easily.
Set-up friendly and compact
Even if automated loading is performed via pallet systems and tombstones, it has proven useful to use specially adapted mechanical clamping devices. They offer advantages in terms of process reliability, accessibility and compactness, as well as operation at the set-up station. For example, the manually operated SCHUNK KONTEC KSC basic clamping vises are particularly efficient all-rounders for machining raw and finished parts with automatic workpiece storage. They combine high clamping forces, convenient operation, and short set-up times. With comparably low torques, they can achieve high clamping forces of 50 kN (size 160), meaning that a separate stamping station for form-fit clamping is no longer needed. As the clamping takes place by tension, the bending load on the base body and thereby the lifting up of the vises are minimized, which adds to the accuracy and rigidity of the clamping. A pre-tensioned center bearing without spindle reverse clearance and specially adjusted slides guarantee an excellent repeat accuracy of +/- 0.015 mm. The fully encapsulated drive and an integrated chip outlet ensure particularly high process stability and minimum wear. The basic clamping vises are available as centric clamping vises or as single-acting vises with a fixed jaw. They offer fast adjustment of the clamping range, a flat design, and low weight – the perfect conditions for unmanned workpiece handling. SHUNK KONTEC KSM2 multi clamping vises also have the advantage that several workpieces may be clamped next to each other in confined spaces. Slim chuck jaws without protruding interfering contours provide you with particularly high part density and optimum accessibility. Hardened and ground fine serration ensures maximum robustness, precision, and form stability. Regardless of the workpiece size, the workpiece is automatically pulled down during the clamping process by means of a wedge clamping system. As a result, safe and precise machining is ensured even at high feed rates. A single actuation key is required to clamp workpieces, remove chuck jaws completely by means of the quick-change system or quickly and flexibly convert the clamping system to different workpieces. A wide chuck jaws modular system is provided for this purpose.
The quick-change module VERO-S NSE-A3 138 was specially developed for automated applications.
Slim palletizing systems for maximum flexibility
Standardized palletizing systems, such as the SCHUNK VERO-S NSA plus flat palletizing module, which—unlike other clamping systems—does not require any energy during processing, enable particularly flexible and process-stable changing of clamping devices. An internal spring package ensures constant and safe tension, even if the pressure in the air system should suddenly drop. Thanks to a patented fast stroke system, it reaches pull-down forces of up to 15,000 N and clamping forces of more than 100,000 N. All functional components such as base bodies, clamping slides, and clamping rings are made with hardened stainless steel and are therefore absolutely resistant to corrosion. During the automated change, a positively driven air flow cleans the flat surfaces and the short taper, and therefore ensures that the work surface of the pallet is chip-free and flat. Centering sleeves then ensure precise positioning to a reference point. Clamping slides ensure form-fit, self-locking mounting. Through dynamic pressure monitoring, all process steps can be reliably monitored. In combination with the slim, SCHUNK NSR lightweight couplings with minimal interfering contours, a particularly process-stable pallet change can be implemented, which can be monitored using inductive proximity switches.
The smart clamping devices and gripping systems measure, identify, and monitor gripped components and the ongoing production process in real time.
Automation component with integrated media transfer unit
The automation component SCHUNK VERO-S NSE-A3 138 demonstrates that classic zero-point clamping modules can also be optimized for automated processes. For process-reliable workpiece and clamping device changes, the automation component is equipped with a powerful blow-off function, which carefully cleans the bearing surface during the changing process. In addition, a spring-actuated cone seal prevents chips or dirt from penetrating into the changing interface. An enormous pull-down force of 8,000 N or 28,000 N with activated turbo function and a high dimensional stability of the module body benefit the rigidity of automated quick-change solutions. Thus, even high tilting moments and shear forces can be reliably absorbed. Centering inserts with flexible elements ensure positional orientation with a high repeat accuracy and maximum process reliability in automated operations. Due to the conical fitting, the clamping pins can be attached in the component incredibly easily. By means of an integrated media transfer unit, fluids with permissible system pressures of up to 300 bars can be transferred (e.g. to control clamping devices or to supply components for automated monitoring).
SCHUNK hydraulic expansion toolholders with axial pull-down function are highly efficient set-up time optimizer when performing highly precise machining work. They can be loaded automatically, and the clamping device can be changed quickly with no time wasted aligning it and screwing it in.
The Trend Towards Digitalization
The latest technology studies from SCHUNK clearly show the direction of travel: in addition to their mechanical qualities, tomorrow’s clamping devices will offer more and more digital features. For example, the smart quick-change pallet module SCHUNK VERO-S NSE-S3 138 enables permanent monitoring of the pull-down force and clamping slide position. For this purpose, SCHUNK has strain gauges, measuring amplifiers and inductive analog sensors directly integrated into the module. Furthermore, the presence of the workpieces or clamping pallets can be detected by means of inductive proximity switches. This ensures that the entire clamping process runs under optimal conditions. A decisive advantage of the smart modules is definitely their compatibility with the purely mechanical VERO-S program: in this way, all intelligence has been cleverly integrated into the clamping module so that the dimensions are completely identical to those of the mechanical VERO-S NSE3 Going one technological step further, we have the clamping force block SCHUNK TANDEM KSE 100. In addition to integrated monitoring of the clamping path and clamping force, this intelligent powerhouse is also capable of individually adjusting the clamping force and position of each chuck jaw to the respective workpiece. This makes it possible to pre-position the clamping jaws in the ongoing process and to reduce the cycle time. In addition, it is possible to reduce the clamping force for deformation-sensitive parts, in order to prevent deformation or damage to the surface. The required sensor technology is also fully integrated into the component.