
JUCRANK - Non-cylindrical grinding machines
Precise in a single set-up
The JUCRANK non-cylindrical grinding machine accomplishes all grinding tasks on crankshafts. Maximum accuracy and quick cycle times are achieved through oscillation grinding in a single clamping set-up and through the productive machine concept. Ideal dimensional stability and high process reliability are ensured through in-process measurements, for example.
Rough and finish grinding of crankshafts in all batch sizes can be carried out on platforms with various dimensions. For main, pin and thrust bearings, diverse geometric shapes as well as plane surfaces and radii can be ground. Internationally renowned engine manufacturers place their trust in the versatile, productive JUCRANK non-cylindrical grinding machine.

Highlights
- High process reliability due to complete grinding in a single set-up
- Optimum grinding quality due to automatic compensation of disturbance variables
- High dimensional stability due to in-process measuring system
- Flexible use for wide-ranging different cylinder numbers by CNC resetting
- Extreme smooth running due to directly driven grinding and work piece spindles
- Optimum support provided with self centering three point steady rests
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Grinding process descriptions
The pendulum grinding method enables crankshafts to be rough and finish ground in a single clamping set-up. The crankshaft rotates around its central axis and the grinding wheel follows the circular motion of the pin bearing by interpolation of the workpiece spindle (C axis) with the grinding spindle (X axis).
To achieve top concentricity quality, crankshafts are frequently supported on a steady. The rough grinding process relieves any hardening stress in the material and an in-process measuring system supplies correction data for finish grinding.
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Axially parallel
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The grinding wheels and the workpiece are arranged in axially parallel formation, enabling straight plunge grinding of the bearings. The grinding wheels are dressed to ensure the geometric shape of the bearings.

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with adjusting axis (WK axis)
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Pendulum grinding is made more flexible by a new development from JUNKER: The WK axis. This axis swivels the grinding spindle, on which narrow grinding wheels are mounted, within the micron range during grinding. Benefit: Every main and pin bearing can be given its own profile shape – compensating for tapers and without the need to exchanging the grinding wheel.

Special solutions

Large crankshafts
The JUCRANK 8 grinds crankshafts with a peripheral diameter of 470 mm and a clamping length of up to 4800 mm completely in a single clamping set-up. The crankshaft is supported by CNC-controlled steadies, measured following rough grinding and then selectively finish ground with the aid of the WK axis – all ensuring that only GO parts ever leave the machine.

Used crankshafts
In the interests of sustainability: Used crankshafts can be reground. Using an automatic work cycle, whereas the crankshafts are measured in the machine and subsequently ground without operator intervention.

Coolant tracking
When using large grinding wheels, a CNC-controlled swivel motion of the coolant nozzles follows the pin along the grinding wheel at a constant distance. This guarantees optimum cooling, as the coolant is directed permanently towards the grinding zone.
Technical data: JUCRANK 1S

- Wheelheader Number
- 1
- Grinding Length
- 150 mm
- Clamping Length
- 150 mm
- Center Height
- 100 mm
- Component Weight
- 5 kg
- Grinding Wheel Diameter
- 350 mm
- Swing Diameter
- 80 mm
- WxDxH mm (without peripherals)
- 1800 x 2500 x 2100
- Weight
- 10.000 kg
Wheelhead JUCRANK 1S
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/50
Technical data: JUCRANK 1000

- Wheelheader Number
- 1
- Grinding Length
- 150 mm
- Clamping Length
- 150 mm
- Center Height
- 100 mm
- Component Weight
- 5 kg
- Grinding Wheel Diameter
- 350 mm
- Swing Diameter
- 80 mm
- WxDxH mm (without peripherals)
- 1500 x 2500 x 2100
- Weight
- 9000 kg
Wheelhead JUCRANK 1000
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Technical data: JUCRANK 3000

- Wheelheader Number
- 1
- Grinding Length
- 400 mm
- Clamping Length
- 400 mm
- Center Height
- 150 mm
- Component Weight
- 15 kg
- Grinding Wheel Diameter
- 350 mm
- Swing Diameter
- 150 mm
- WxDxH mm (without peripherals)
- 3400 x 2800 x 2100
- Weight
- 12.000 kg
Wheelhead JUCRANK 3000
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3000/50
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/50S
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/60
Technical data: JUCRANK 5000

- Wheelheader Number
- 1
- Grinding Length
- 700 mm
- Clamping Length
- 700 mm
- Center Height
- 170 mm
- Component Weight
- 130 kg
- Grinding Wheel Diameter
- 500 mm
- Swing Diameter
- 280 mm
- WxDxH mm (without peripherals)
- 4900 x 3400 x 2350
- Weight
- 14.000 kg
Wheelhead JUCRANK 5000
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5000/50
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Technical data: JUCRANK 6S

- Wheelheader Number
- 1
- 2
- Grinding Length
- 1000 mm
- 750mm
- Clamping Length
- 1200 mm
- Center Height
- 170 mm
- Component Weight
- 150 kg
- Grinding Wheel Diameter
- 500/700 mm
- Swing Diameter
- 280/320 mm
- WxDxH mm (without peripherals)
- 4100 x 3750 x 2450
- Weight
- 21.000 kg
- 25.000 kg
Wheelhead JUCRANK 6S
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/13
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/50S
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Technical data: JUCRANK 6L

- Wheelheader Number
- 1
- 2
- Grinding Length
- 1800 mm
- 1500 mm
- Clamping Length
- 2000 mm
- Center Height
- 170 mm
- Component Weight
- 200 kg
- Grinding Wheel Diameter
- 500/700 mm
- Swing Diameter
- 280/320 mm
- WxDxH mm (without peripherals)
- 4900 x 3750 x 2450
- Weight
- 24.000 kg
- 28.000 kg
Wheelhead JUCRANK 6L
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Technical data: JUCRANK 6XL

- Wheelheader Number
- 1
- 2
- Grinding Length
- 2800 mm
- 2500 mm
- Clamping Length
- 3000 mm
- Center Height
- 170 mm
- Component Weight
- 300 kg
- Grinding Wheel Diameter
- 500/700 mm
- Swing Diameter
- 280/320 mm
- WxDxH mm (without peripherals)
- 6400 x 3750 x 2450
- Weight
- 28.000 kg
- 32.000 kg
Wheelhead JUCRANK 6XL
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/13
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/50
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/50S
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Technical data: JUCRANK 8S

- Wheelheader Number
- 1
- Grinding Length
- 3000 mm
- Clamping Length
- 3000 mm
- Center Height
- 530 mm
- Component Weight
- 1000 kg
- Grinding Wheel Diameter
- 1000 mm
- Swing Diameter
- 470 mm
- WxDxH mm (without peripherals)
- 7600 x 4200 x 3400
- Weight
- 69.000 kg
- 76.000 kg
Wheelhead JUCRANK 8S
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/10
Technical data: JUCRANK 8L

- Wheelheader Number
- 1
- Grinding Length
- 4000 mm
- Clamping Length
- 4000 mm
- Center Height
- 530 mm
- Component Weight
- 1000 kg
- Grinding Wheel Diameter
- 1000 mm
- Swing Diameter
- 470 mm
- WxDxH mm (without peripherals)
- 8600 x 4200 x 3400
- Weight
- 73.000 kg
- 80.000 kg
Wheelhead JUCRANK 8L
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Technical data: JUCRANK 8XL

- Wheelheader Number
- 1
- 2
- Grinding Length
- 4800 mm
- 4600 mm
- Clamping Length
- 4800 mm
- Center Height
- 530 mm
- Component Weight
- 1000 kg
- Grinding Wheel Diameter
- 1000 mm
- Swing Diameter
- 470 mm
- WxDxH mm (without peripherals)
- 9600 x 4200 x 3400
- Weight
- 77.000 kg
- 84.000 kg
Wheelhead JUCRANK 8XL
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/10
Equipment and Options
- LEARNING FUNCTION
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The control system comes with automatic compensation of runout and disturbing variables such as temperature influences, grinding allowance fluctuations or material changes. Even minimal deviations between the target and actual position of the grinding wheel are automatically corrected.
- LONGITUDINAL AND RADIAL POSITIONING
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In order to generate a precise width and angular position of the main and pin bearing, the position must be precisely determined when clamping the crankshaft. For this, a touch probe measures the radial position of the pin bearing and the longitudinal position of the main and pin bearing. The measured values are automatically integrated in the grinding process by the control system.
- CONTROL SYSTEM
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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.
- C AXIS WITH DIRECT DRIVE
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Torque motors are used for direct drive of the C axis. This ensures impressive quiet running, high torque rigidity and superb dynamics in the C axis. Torsionally unstable crankshafts are driven by two C axes.
- Axis drive and guidance
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The X axes, with linear roller ways with high pre-load, takes care of ultra-precise positioning of the grinding and regulating wheel head. Drive is executed by a precise, intrinsically rigid ball screw with infinitely variable servo drive and glass scale.
The B axis of the wheelheads is driven by a backlash-free gear. Every angular position is programmable; the position sensor system has a sensational resolution of 0.00001 of a degree. Extreme low noise (vibration) levels are guaranteed with the JUNKER grinding spindles with direct drive – an in-house development – complete with a structure-borne sound sensor and dynamic balancing system in one or two planes.
- Clamping fixture
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The patented 3-point mounting interface allows grinding and dressing wheels as well as work holdings to be mounted and centered on grinding spindles, workpiece spindles and tailstock sleeves in record time. Adjustment of the tailstock and, where applicable, the workhead take place using optionally using a chain wheel, a hydraulic cylinder or a CNC axis with rack and pinion drive. An airlift function simplifies position adjustment. Depending on the workpiece, in addition a wide range of clamping systems are also available
- MACHINE BED
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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.
- ABRASIVE
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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.
- DRESSING UNIT
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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.
- LOADING SYSTEMS
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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.
- MEARSUREMENT SYSTEMS
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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.
- STEADIES
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As an option, self-centering three-point steadies ensure stable support. Tracking hydraulic jaws guarantee a balanced ratio of forces at all three support points, and with it a grinding process with repeat accuracy.
- IN-PROCESS MEASURING SYSTEM
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A swivel-in measurement probe carries out an in-process measurement of the diameters of the main and pin bearing. The control system logs the measured values, calculates
the correction data and generates the precise shape. After grinding, the Machine is able to measure the entire geometry of the crankshaft – depending on requirements:
from the bearing width through the lift height to the taper of each element. - FIRE PROTECTION AND LTA AIR FILTERS
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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.
Workpieces
- Crankshaft