For 20 years now, the firm Kellenberger has been part of the Hardinge Grinding Group. From the very start, the Kellenberger VARIA universal cylindrical grinding machine model range has stood for the best in working and surface quality among Kellenberger’s range of products. More than 1000 machines are already in use around the world. The VARIA machine concept has constantly been updated with new developments and has always been a step ahead of the various technical standards. But now, with its larger work space, distinctly longer machine table, and distance between centers of 1600 mm, it is ready for even more comprehensive machining possibilities.[youtube]W8qsvdFutXA[/youtube]
Optimized for a demanding range of applications
VARIA’s features are aimed at the demanding requirements involved in high-precision production of prototypes and small and medium-size series. Typical areas of use include machine construction, the production of tools and molds, the fabrication of precision components for the automotive, electronics, and aircraft industries, and job shops with their wide variety of needs.
Hydrostatic guideways have always been a feature of the VARIA universal cylindrical grinding machine, providing the best in shape accuracy for all grinding tasks involving interpolating axes. The newest generation of hydrostatic guideways in the VARIA is the result of 25 years’ experience. They provide excellent damping, stick-slip-free operation, high rigidity, and a constant machine temperature, resulting in outstanding surface quality and productivity and more process and operation reliability, without any friction loss and wear. Because of the direct drives on the rotary axes, high positioning speeds and accuracy are guaranteed.
Stability is crucial for achieving high precision and productivity. In the new VARIA the solid machine table with the reinforced machine bed once again improves rigidity. The increase in stability means VARIA can now work with workpieces of up to 300 kg.
With larger heights of and distances between centers, the new VARIA is faster and more precise, offering consistently better performance. Drives optimized for performance move the longitudinal and cross slides at speeds of up to 20 m/min., and at an axis resolution of ten nanometers.
The hydrostatic B axis is equipped with a direct drive too. This means that the revolving wheelhead pivots roughly three times as fast as without a direct drive, and positions with a precision of less than one arc second. This reduces non-productive times, so it raises productivity, especially when the work at hand demands the pivoting-in of different grinding wheels.
Unique machine concept
The VARIA is available with distances between centers of either 1000 or 1600 millimeters, and heights of centers of either 200/250 or 300 mm, as required. Travel on the X axis and Z axis has been extended. Due to the modular machine concept, the task at hand defines the position of the wheelhead within the machine and this way ensures an optimum in distance and dressing conditions. More than 30 wheelhead variations with external and internal grinding spindles permit an array of machining possibilities, and the right application-specific configuration at all times.
The new machine casing is an important contributor to process reliability, as well as operator and service-friendliness. The thickness of the sheet metal casing has been increased considerably. This makes it possible to use larger grinding wheel diameters of up to 125 mm for internal grinding.
With their large viewing field, generously-sized doors ensure optimal control over the work process and make it easier to access the work space. The triple-glazed door elements offer a maximum in safety and are practically maintenance-free. This makes replacement of the panes at regular intervals – a requirement of the polycarbonate panes commonly used on the market – unnecessary. This saves time and money. A visual status display integrated in the doors signals potential disruptions.
Elements such as the power supply, electrics cubicle, and a central connection point for lubricating coolant, water cooling system, and compressed air have all been integrated in the casing. Ideally positioned service and maintenance doors ensure unimpeded access to all machine components.
Like its predecessor the KEL-VARIA, the VARIA is known for the compactness of the space it requires for setup. The proven integrated transport concept (hook transport) has been retained, which considerably reduces the time needed to get it operating.
The VARIA is equipped with the latest Heidenhain GRINDplus640. In addition to the Heidenhain controls with user-guided ISO programming and selective help images, for the first time Kellenberger has its own controls, with a graphical programming and collision monitor. The controls allow faster working speeds at even higher precision. Axis control in the nano range translates into highly accurate profiling and track accuracy for contour grinding. Optionally, the VARIA can be equipped with the Fanuc 31i, as in previous models. The new remote maintenance concept with integrated IT security ensures higher security when connecting to the customer network via VPN tunnel or mobile communication.
Low-pressure hydrostatics and a new, optimized cooling system with bypass regulation valve are two of many new features. Proven features of VARIA machines include low-friction linear axes, play-free spindle drive, drives optimized for performance, thrifty valve technology, a lubrication circulation system with no oil loss, and options to switch off unused consumers.
Source Hardinge Grinding Group