LGG 300 / 700 | Generating and profile grinding machines

LGG 300 - 500 / 700 M

The allrounder.

Highlights

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Flexibility

Technological diversity

Powerful

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Machine design

Generating grinding, profile grinding and internal grinding in one machine

Flexibility is essential for job shops and small lot sizes. The new LGG series has been specially designed for universal use, as well as for large series production. It combines three technologies: Generating grinding, profile grinding and internal grinding. This technological diversity provides the universal user with maximum benefit and a secure investment for the future.

This machine can be configured for individual applications, so it is perfect for use in the production of large batches. This is where external automation systems such as a plastic chain conveyor or a robot system are used.

The LGG is the most powerful generating and profile grinding machine of its class on the market. With the new GH 320 CB grinding head, it is now also possible to efficiently grind superior quality workpieces up to module 14. The LGG 700 M is a manual gear grinding machine that can grind workpieces up to 500 mm (generating) and up to 700 mm for profile grinding.

_{X1 - radial movement of column slide | V1 - tangential movement of tool | Z1 - axial travel of grinding head | B1 - rotary movement of tool | C2 - rotary movement of workpiece | A1 - swivel movement of tool | Z4 - vertical travel of steady column | C3 - rotary movement of ringloader}

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LGG 700 M

Liebherr also offers a manual generating and profile grinding machine for small batch sizes and outstanding flexibility.

Generating grinding max. workpiece diameter (mm): 500
Profile grinding max. workpiece diameter (mm): 700

The machine is exclusively loaded manually. A handling device (crane) mounted on the machine roof and an NC-swiveling tailstock make manual loading much more simple.

External and internal grinding heads

Process-optimized external grinding heads and internal grinding arms are available for the LGG. Balancing systems inside the spindle are used in both external grinding heads (GH 320 and GH 240 CB). On the GH 320 CB, the balancing system is integrated in the arbor.

High drive power and speeds are major advantages – for example, when using new grinding materials. The modern tool holding makes it possible to replace the grinding arbor quickly and easily.

Small grinding tool diameters are available for collision-critical workpieces and for special tooth corrections.

With the GH 320 CB grinding head, it is now also possible to efficiently grind optimal-quality workpieces up to module 14 mm.

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GH 240 / 200 CB

Technical data GH 240 CB

Speed (rpm): 12,000
Grinding spindle drive power (kW): 28.5
Max. grindable module generating grinding (mm): 7
Max. grindable module profile grinding (mm): 14
Electro-plated CBN tools: Yes
Dimensions of grinding worm: (DxLxW): 240x200x76.2

Technical data GH 200 CB

Speed (rpm): 17,000
Grinding spindle drive power (kW): 28.5
Max. grindable module generating grinding (mm): 5
Max. grindable module profile grinding (mm): 14
Electro-plated CBN tools: Yes
Dimensions of grinding worm: (DxLxW): 240x200x40 (76.2)

GH 320

Speed (rpm): 7000
Grinding spindle drive power (kW): 28.5
Max. grindable module generating grinding (mm): 9
Max. grindable module profile grinding (mm): 14
Dimensions of grinding worm (DxLxW) (mm): 275(320)x160x160

GH 320 CB

Drive power (kW): 28.5
Speed (rpm): 10,000
Max. cutting speed (m/s): 80
Max. grindable module generating grinding (mm): 14
Max. grindable module profile grinding (mm): 14
Max. shift distance (mm): 350
Dimensions of grinding worm (DxLxW) (mm): 320x250x110
Feature: Internal grinding arms are available for all grinding heads.

_{Can be used with LGG 300, LGG 380, LGG 500 and LGG 700 M}

Fast and easy changeover

The adaptable internal grinding arms can be mounted quickly and easily on the external grinding head and are driven using the main drive. Other grinding heads can be provided on request.

In only 30minutes from external to internal grinding

Video

Generating grinding planetary gears, module 14, on the LGG 500 generating and profile grinding machine

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On-board inspection: Gear check in the machine

All grinding heads can be equipped with an optional swivel-in probe for gear checking.

Gear measurement

Proﬁle and lead
Concentricity, single and cumulative pitch
Twist check
Measuring system for grinding stock removal
Rolling measurement
Determining dimension measurement

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Mobile or stationary meshing sensor

Technology

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Prepared for the future

Type of gears

Asymmetric profile
Beveloid gears
Double helical gears
Cycloidal gears

Gear modification

Profile and lead modification
Free flank form

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Cycloidal gears

For cycloidal drives, certain requirements must be met, such as dimensional precision, a high-quality surface, an excellent profile and pitch as well as rollers that fit perfectly to the inner ring. Liebherr has developed something new for cycloidal gears: Now, cam disks with an external gear can be produced via generating grinding using not only single but also perfectly adapted double clamping. Depending on the individual batch-size requirements, which means that besides conventional profile grinding, an additional grinding method for cam disks is now available to users.

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Generating grinding asymmetric gears

Asymmetric gears compensate for unequally distributed loads.

The advantages of asymmetric gears are obvious:

Reduced tooth root clamping forces and Hertzian flank stresses
Improved specific sliding
Increased surface durability and tooth root strength
Increased power density (load capacity in relation to gear size)
Longer service life
Increased efficiency
Reduced noise and vibration excitation
Increased operational reliability

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Requirements when generating grinding asymmetric gears

Machine technology:

Centering of the dresser/grinding worm
Centering of the asymmetric grinding worm/workpiece
Initial profiling and tracking of the asymmetric profile at every dressing cycle
Precise control technology for dynamic tooth flank contact sequences

Technology:

Coordination of dressing and grinding parameters
Selection of appropriate grinding worm specifications

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Topological modifications

TF twist-free grinding
DFT deviation-free topological grinding
GER generated triangle-shaped end relief

Modifications for noise reduction

SSG noise-reduction shift strategy
NEO noise excitation-optimized modifications

Generating grinding with small tools

Finishing grinding or polishing

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Why modified and/or super-finished leads?

Motivation:

Improved wear behavior
Reduction of friction losses
Increased flank and tooth root strength
Increased efficiency
Longer service life (gear and gearbox)

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Our solution: Finish grinding or polishing

Lower surface roughness can be achieved with finish grinding or polishing. This increases the power density and gear efficiency.

Generating or profile grinding with dressing-free CBN

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CBN generating grinding

Short machining times (two-cut strategy)
No dressing required
Very low risk of grinding burn (short contact time, good thermal conductivity of CBN and steel basic body)
Universal tool design
Very long tool life
Robust process with high process stability
Module range 1.0 - 5.0mm
External gears with a high toothed length
Large batches, perfect for three-shift operation

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Mono worm and rough-and-finish combination
Available in various dimensions:
Diameter 60 /140 / 170mm
Width 2x 96 / 140 / 200mm
Tool design:
Steel basic body, mono-layer CBN coating
Can be re-coated 10-15 times
Metallic, nickel-based bond
Standard CBN grain sizes:
B76 and B91 for finishing
B251 for roughing

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CBN profile grinding

Very high profile quality
Pressure angle can be corrected by CNC (A, V and X axes)
Long tool life
Grinding of non-generating profiles and complex geometries
Module range 1.0 - 8.0mm
External and internal gears
Collision-critical gears (discs Ø < 30mm)
Small and medium-sized batches

Integrated centrifugal device

Automation

Easy to operate

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The new optimized control panel LHStation & LHMobile

With the control panel, Liebherr intelligently divides the programming and operation of the machine between two system parts: The large, fixed monitor unit LHStation for data input and process monitoring and the standardized, mobile handheld terminal LHMobile with context-sensitive user guidance during setup. Both units have a multi-touch surface as well as tactile elements for optimum operating speed and operating safety.

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Mobile handheld terminal LHMobile

10-inch multi-touch as standard
Context-sensitive views such as PLC/NC keys and program statuses
Wired signal transmission for maximum safety

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The programming system by Liebherr: 25% faster setup time

With the LHGearTec software, the system constantly guides users when entering workpiece and tool data, as well as during workpiece correction and process monitoring. The user guidance has been defined in intensive cooperation with designers and users.

More information

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