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JUPITER

JUPITER - Centerless grinding machines

Productive all the way

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.

Highlights

  • Rapid set-up due to patented CNC height adjustment of the support blade
  • Minimized undulations with grinding wheel balancing on two planes
  • Extremely low running noise due to grinding spindle with direct drive
  • Optimum grinding quality as a result of market-leading rigidity
  • Optimized grinding process due to automatic grinding gap geometry setting
  • Individual CNC dressing of grinding wheel and regulating wheel

Grinding process descriptions

Centerless grinding

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.

Centerless grinding
Throughfeed grinding

Throughfeed grinding

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.

Plunge-cut grinding

Plunge-cut grinding

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.

Technical data: JUPITER 125

Grinding Length
125 mm
WxDxH mm (without peripherals)
1600 x 3600 x 2200
Weight
8000 kg

Technical data: JUPITER 200

Grinding Length
200 mm
WxDxH mm (without peripherals)
1600 x 3700 x 2200
Weight
11000 kg

Technical data: JUPITER 250

Grinding Length
250 mm
WxDxH mm (without peripherals)
1250 x 3730 x 2100
Weight
15000 kg

Technical data: JUPITER 500

Grinding Length
500 mm
WxDxH mm (without peripherals)
4410 x 2600 x 2200
Weight
18000 kg

Equipment and Options

8° INCLINED BED
8° inclined bed

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.

MACHINE BED
Machine bed - mineral cast

The machine bed made of mineral cast provides impressive damping behavior and torsional rigidity. The temperature stability allows fluctuations in the ambient temperature to be compensated with a minimum of effort, ensuring a high level of dimensional stability throughout the whole day.

CONTROL SYSTEM
Control system

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.

Axis drive and guidance
Axis drive and guidance

With platforms 1 to 8, the wheelheads traverse along the Z axis. The mechanical direct drive uses the rack and pinion to perform play-free positioning depending on both load and temperature – thanks to two drive motors per slide. With platforms 1000 to 5000, the grinding table traverses on a flat prism guide with pre-tensioned ball screw.

The X axis with hydrostatic round guide carries out stick-slip-free positioning with minimal wear and maintenance requirement – due to the absence of any metal contact between the guide column and housing. Drive takes place by means of an ultra-precise hydrostatic feed spindle which is suitable for extremely high forces and has no acceleration limit.

The B axis of the wheelheads is driven by a play-free gear or torque motor. Every angular position is programmable; the path measuring system has a sensational resolution of 0.00001 degrees. The directly driven grinding spindles – manufactured by JUNKER – ensure extremely low-noise running, with structure-borne sound sensor and dynamic balancing system on one or two levels.

DRESSING UNIT
Dressing unit

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.

SUPPORT BLADE
Support blade

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.

STATIONARY GRINDING GAP
Stationary grinding gap

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.

PARTIAL AND FULL ENCLOSURE
Partial and full enclosure

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.

ABRASIVE
Abrasive

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.

FIRE PROTECTION AND LTA AIR FILTERS
Fire protection and LTA air filters

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.

MEARSUREMENT SYSTEMS
Measurement 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.

LOADING SYSTEMS
Loading systems

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.

Workpieces

  • Gear shaft
  • Cardan joint
  • Needling
  • Pipe
  • Rod
  • Rolling element

Product Brochures JUPITER

JUPITERJUPITER

Special solutions

One pass, multiple operations

One pass, multiple operations

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.

Inclined plunge-cut grinding

Inclined plunge-cut grinding

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.

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Address:

Erwin Junker Maschinenfabrik GmbH
Headquarters
Junkerstraße 2
77787 Nordrach
Germany