JUPITER series centerless grinding machines offer substantial production benefits: The patented CNC height adjustment of the support blade minimizes tooling times, automatic adjustment of the grinding gap geometry optimizes the grinding process and the inclined bed guarantees maximum dimensional precision. Depending on the application, corundum, CBN or diamond is used as an abrasive.
During centerless cylindrical grinding, the workpiece is not clamped but lies in the grinding gap between the grinding wheel, regulating wheel and support blade. The grinding pressure presses the workpiece against the regulating wheel, which brakes the workpiece to its own peripheral speed.
For this to work, the friction at the regulating wheel must be greater than the friction at the grinding wheel. The friction is achieved by the rubber bond at the regulating wheel and by inclining the support blade and machine bed.
Throughfeed grinding is among the most productive methods used in the field of grinding technology. It entails workpieces traveling through the machine in a continuous stream without interruption. The grinding wheel has defined roughing, finishing and ultra-fine grinding zones, enabling it to grind all the workpieces to one diameter. The throughfeed rate is determined by the incline and speed of the regulating wheel.
The centerless plunge-cut grinding method entails grinding workpieces with offset or profiled diameters. Here, the grinding wheel is given the negative profile of the desired workpiece contour. In this way, all the diameters which have to be produced at the workpiece can be ground in a single plunge cut operation. The workpieces are positioned, then ground and finally unloaded by means of an axial stop on the support blade.
Inclined plunge-cut grinding is a special process variant of this method. In contrast to the straight arrangement of the grinding wheel axis, the axes of both the workpiece and the regulating wheel are inclined by 15°. This enables shoulders and end faces to be ground, in addition to diameters.
Rough, intermediate and finish grinding in a single pass: Using the throughfeed grinding method, the JUPITER 500 replaces the rough and intermediate grinding processes by using a special CBN grinding wheel set. This saves the user the need to perform several work processes, increasing output many times over.
The JUPITER 125 can be reset within minutes for angular plunge-cut grinding operations. This allows not only diameters but also shoulders and face ends to be ground to a high standard of precision and reproduction accuracy. The JUNKER software tool, the CNC height adjustment of the support blade and the CNC-controlled workpiece stop all help to optimize the grinding process.
The 8° inclined bed increases friction at the regulating wheel, as gravity causes a larger proportion of the workpiece weight to shift from the support blade to the regulating wheel. This makes for easier rotation of the workpiece prior to grinding and ensues greater friction at the regulating wheel during the grinding process, creating a better braking effect. The inclined bed also causes the coolant and grinding sludge to drain away naturally.
The Erwin Junker Operator Panel was specifically developed to control grinding machines. All machine components are controlled using the operator panel – irrespective of the series and the used control system. The identical structure, intuitive menu guidance and visualization of the workpiece geometry make for extreme user convenience and flexibility in operation. Programming takes place directly using the operator panel or an external programming tool.
Grinding wheel dressing is CNC controlled. A driven diamond dressing wheel or a workpiece-dependent diamond profile roller can be used. Dressing takes place manually or using an automatic dressing program with grinding wheel compensation.
The patented CNC height adjustment of the support blade has two decisive benefits. Firstly, it ensures a faster set-up as all three grinding gap components (grinding wheel, regulating wheel and support blade) can be controlled from the operator panel. Secondly, the support blade compensates for changes in diameter keeping the workpiece axis on the same level during the entire grinding process. This exerts a positive influence on workpiece quality during centerless grinding.
The wheel heads of the grinding and regulating wheel are each equipped with an X axis. The stationary grinding gap enables low-cost loading systems to be used which do not require a tracking axis.
For throughfeed grinding with emulsion, JUPITER series grinding machines are also available with a partial enclosure. This simplifies access to the machine components for maintenance and servicing work, as well as mechanical adjustment of the B axis.
Depending on the application, the abrasive CBN or diamond is used. The basic bodies of the grinding wheels comprise steel or carbon. In conjunction with CBN, it can make sense to use a carbon base body: It is light, has vibration-damping properties and remains dimensionally stable even at high speeds.
In case of an fire, the machine interior is automatically hermetically sealed, suffocating a fire before it has a chance to spread. If required, extinguishers (CO² or water mist systems) and exhaust air purification systems can be additionally installed. A competent partner for fire protection and filtration solution solutions is LTA Lufttechnik GmbH, which also belongs to the JUNKER Group and which researches, develops and produces filtration systems for industrial air purification.
The Filtration systems
The measurement systems are also individually adjusted to the various workpieces and customer specifications. The measurement processes entail evaluating the recorded measured values and utilizing them for measurement correction in line with the prepared measurement strategy. A grinding wheel measuring system to determine the diameter, axial position and width of the grinding wheel completes the wide range of systems on offer.
JUNKER offers both internal and external loading systems for all its machine series, depending on customer and workpiece requirements. The loading systems can be combined with different infeed and discharge systems such as conveyor belts or custom tailored systems.