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JUCRANK

JUCRANK - Non-circular grinding machines

Precise in a single set-up

The JUCRANK takes care of all grinding operations on crankshafts in a single clamping set-up. Whether single-stroke ultra-small or multi-stroke large-scale crankshafts – rough and finish grinding of crankshafts in all series sizes and wide-ranging geometries is possible using differently dimensioned platforms.

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

Grinding process descriptions

Pendulum grinding

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.

Pendulum grinding
Axially parallel

Axially parallel

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.

with adjusting axis (WK axis)

with adjusting axis (WK axis)

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.

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 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
9000 kg

Wheelhead JUCRANK 1S

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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
12000 kg

Wheelhead JUCRANK 3000

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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
14000 kg

Wheelhead JUCRANK 5000

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Technical data: JUCRANK 6XS

Wheelheader Number
1
Grinding Length
500 mm
Clamping Length
600 mm
Center Height
170 mm
Component Weight
130 kg
Grinding Wheel Diameter
500/700 mm
Swing Diameter
280/320 mm
WxDxH mm (without peripherals)
3260 x 3750 x 2350
Weight
17000 kg

Wheelhead JUCRANK 6XS

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Technical data: JUCRANK 6S

Wheelheader Number
1
Grinding Length
1000 mm
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
21000 kg

Wheelhead JUCRANK 6S

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Technical data: JUCRANK 6L

Wheelheader Number
1
Grinding Length
1800 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
24000 kg

Wheelhead JUCRANK 6L

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Technical data: JUCRANK 6XL

Wheelheader Number
1
Grinding Length
2800 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
28000 kg

Wheelhead JUCRANK 6XL

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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
69000 kg

Wheelhead JUCRANK 8S

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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
73000 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
77000 kg
84000 kg

Wheelhead JUCRANK 8XL

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Equipment and Options

LEARNING FUNCTION
Learning Function

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
Longitudinal and radial positioning

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
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.

C AXIS WITH DIRECT DRIVE
C axis with direct drive

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
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.

Clamping fixture
Clamping fixture

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
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.

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.

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.

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.

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.

STEADIES
Steadies

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
In-process measuring system

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
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.

Workpieces

  • Crankshaft

Product Brochures

JUCRANK.pdf

Special solutions

Large crankshafts

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

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

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.

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Address:

Erwin Junker Maschinenfabrik GmbH
Headquarters
Junkerstraße 2
77787 Nordrach
Germany