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JUMAT

JUMAT - Cylindrical grinding machines

Versatile in every regard

Quality, productivity, availability – the JUMAT external and internal cylindrical grinding machine leaves nothing to be desired. Various sizes and a large number of wheelhead versions offer unrivaled versatility. Paired with the concentrated expertise of JUNKER, each machine is specially matched to the customer‘s requirements.

Highlights

  • High dimensional accuracy thanks to various measuring systems
  • Long tool life through use of CBN or diamond grinding wheels
  • Versatility due to a large number of wheelhead versions
  • Minimized undulations due to grinding wheel balancing on two levels
  • Fast changeover through patented 3-point mounting interface

Grinding process descriptions

External and internal grinding

The cylindrical grinding machines of the JUMAT series can perform both OD and ID grinding in a single clamping set-up. CBN and diamond grinding wheels enable high-speed grinding, provide for high cutting performance and enable grinding of difficult materials.

External and internal grinding
External cylindrical grinding

External cylindrical grinding

During external cylindrical grinding, the workpieces are clamped between tips or in a collet chuck. To increase productivity, grinding wheel sets are used for some applications. The JUMAT uses the straight and inclined plunge-cut grinding process.

With straight plunge-grinding, the cutting and feed movement is carried out radially to the workpiece. The diameters are ground either in one feed or with several feeds and axial twisting.

With inclined plunge-cut grinding, the grinding wheel is at an angle and the wheelhead (B-axis) is swiveled. The X and Z-axis interpolate. This makes it possible to grind the diameter and flat surfaces in a single feed.

To grind grooves or to pre-grind threads, a galvanically bonded grinding wheel is usually used.

Internal cylindrical grinding

Internal cylindrical grinding

Internal cylindrical grinding enables precise grinding of inside functional surfaces, such as drilled holes, cones or flat surfaces. High-speed grinding spindles are used to achieve the desired cutting speed, despite the smaller grinding wheel diameter.

Technical data: JUMAT 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
10000 kg

Wheelhead JUMAT 1S

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Technical data: JUMAT 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 JUMAT 1000

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Technical data: JUMAT 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 2200
Weight
12000 kg

Wheelhead JUMAT 3000

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Technical data: JUMAT 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 JUMAT 5000

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Technical data: JUMAT 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 2450
Weight
17000 kg

Wheelhead JUMAT 6XS

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Technical data: JUMAT 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 JUMAT 6S

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Technical data: JUMAT 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 JUMAT 6L

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Technical data: JUMAT 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 JUMAT 6XL

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Equipment and Options

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.

WHEELHEAD VERSIONS
Wheelhead versions

The broad range of wheelhead versions provides for great flexibility. Up to three grinding spindles are mounted on each wheelhead. As a result, even complex workpieces requiring several grinding tasks can be ground in one machine and in a single clamping set-up.

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

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.

TAILSTOCK AND WORKHEAD WITH CNC
Tailstock and workhead with CNC

The position of both the tailstock and the workhead can be adjusted with CNC. This option is used both for combined external and internal grinding and for the automatic conversion of workpieces of various lengths or in individual part production.

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.

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.

LONGITUDINAL POSITIONING
Longitudinal positioning

A touch probe measures the longitudinal position of the workpiece on a flat surface to compensate for unmachined part fluctuations. The measured values are automatically integrated in the grinding process by the control system.

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.

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.

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.

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.

Workpieces

  • Axle
  • Starter shaft
  • Drive shaft
  • Countershaft
  • Bolt
  • Bushing
  • Electric motor shaft
  • Excentric shaft
  • Gear shaft
  • Piston pin
  • Piston ring
  • Ball screw spindle
  • Ballscrew-threaded spindle
  • Steering nut
  • Motor shaft
  • Pump piston
  • Pump pinion
  • Pinion shaft
  • Pipe
  • Roller
  • Worm wheel
  • Rotor
  • Rotor shaft
  • Worm shaft
  • Spindle
  • Rod
  • Stator shaft
  • Stud
  • Turbine shaft
  • Cylinder
  • Rolling element
  • Shaft
  • Tool holder
  • Tool Blank
  • Gearwheel
  • Gear rod
  • Spigot
  • Cylinder rollers
  • Cardan joint

Product Brochures

JUMAT.pdf

Special solutions

Center drive

Center drive

The center drive is a special drive system which clamps the workpiece in the center and drives it via a servomotor. This enables both workpiece ends to be ground at the same time.

Grinding of steering rods

Grinding of steering rods

In the automotive industry, electromechanical, axially parallel power steering systems are increasingly used. The JUMAT grinds the outside thread of the steering rod in as single clamping set-up from a solid blank. Pre-grinding is carried out with galvanically bonded grinding wheels, and finish grinding with vitrified bonded CBN grinding wheels.

Grinding of ball screw nuts

Grinding of ball screw nuts

The double workpiece headstock, with two opposing clamping devices, minimizes the downtime when grinding threads of ball screw nuts: While grinding is being carried out on one side, loading and unloading, positioning and clamping are carried out on the other. The only downtime: Swiveling by 180 degrees in less than 3 seconds.

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Address:

Erwin Junker Maschinenfabrik GmbH
Headquarters
Junkerstraße 2
77787 Nordrach
Germany