( MATR. N° 5029007 )


STANDARD EQUIPMENT supplied with the machine :
Coolant equipment complete with pump and tank
Table inclination adjusting device complete with dial gauge
Straight wheel dressing unit (diamond optional) mounted on tailstock
Grinding wheel diam. mm. 760, thickness mm. 100, hole mm. 305
1 wheel flange
Wheel balancing arbor
Wheel extractor
Additional pulley for wheel motor
2 hard metal tipped centers
Set of levelling screws and plates
2 cloth bellows for protection of table guides
Set of splash-guards
Set of service spanners
Set of hexagonal spanners
5 Kg. oil for wheel spindle lubrication
5 Kg. oil for guide lubricating
Instruction manual

PLC control
The PLC programme is permanently loaded on FLASH EPROM
Wheelhead and table movement controled by a.c. brushless motor
Electronic handwheels for manual movement of wheehead and table
Incremental optic rule for positioning control of wheelhead

PLC controls :

  • the movement of the wheel head (axis X) in both automatic and manual
  • the long. movement of the table (axis Z) in both automatic and manual
  • the possibility to programme up to 4 different diameters in one grinding cycle
  • the possibility to programme for each programmed diameter the Z position of table
  • the correction of the grinding quotes of each programmed diameter
  • the automatic compensation of all the grinding quote after dressing
  • electronic handwheels for manual wheelhead and table movement
  • selection of the handwheel increments
  • grinding cycles, plunge and pass with parameters :
    • scrap – rough and finish
    • automatic increments – rough and finish, for pass grinding cycles
    • feeds – rough and finish, for plunge cycles
    • dwell – table inversion
    • sparkout time
    • sparkout pass


Robbi grinding machines are according to the international precision normes ISO 2433.
The table movement linearity is guaranteed by a max. deviation of 0,002 mm/mt.
The obtainable grinding roundness is :
– Grinding between centers 0,5  (**)
– Grinding with live center 0,7  (**)
Surface finish degree from 0,8 to 0,2 Ra .(**)
(**) for a test workpiece ground in our factory during machine testing


Max. distance between centers mm. 5000
Max. grinding length mm. 5000
Height of centers over table mm. 500
Swing over table mm. 995
Max. weight on centers with steady rests Kg. 4000
Spindle hole diameter mm. 70
Spindle stroke mm. 80
Spindle diameter mm. 120
Internal center taper CM 6
Wheel dimensions mm. 1200 x 305
Wheel width min. – max.. mm. 50-150
Wheelhead motor Kw. 18
Workhead Kw. 8

The Grinding Machine is composed of :

Structure in normalised and stabilised cast iron with large ground guides. In the middle of the base, there is positioned the re-circulating ball screw with double preloaded nut for the table longitudinal movement. On all the lower part of the perimeter are situated the recesses for machine levelling. Considering the base structure, usually a foundation is suggest, when the floor structure is not strong enough.

The table is manufactured in one piece in normalised and stabilised cast iron.
The lower part is lubricated by means of a constant oil flow distributed over the complete length.
The upper part is orientable in both ways to permit conic piece grinding. It’s equipped with a micrometric device with centesimal dial gauge to control conicity.

The structure in normalised, stabilised and well ribbed cast iron, allows to support the workpiece weight and the force generated by the grinding operation. It is equipped with dead and live spindle. The spindle rotates on high precision ball bearings, guaranteeing restricted tolerance and maximum rigidity in the working. The spindle rotation is by means of a AC motor and the r.p.m. adjustment is programmable by an electronic variator. The spindle rotation may be intermittently manual or automatic in the two ways, when pusshing the button for the hydraulic rapid approach of the wheelhead. The rotation automatically stps at the end of cycle after wheelhead gets out. The workhead positioning on the table is facilitated by an air flow.

The structure is composed of two carriages in normalized cast iron..
The upper carriage where the hydrodynamic spindle is located, has a manual positioning stroke of 300 mm. The movement on air cushion facilitates the sliding.
The lowe part slides on guides covered with anti-friction material with temporized lubrication.
The lower carriage has two movements: the rapid approach movement by hydraulic cylinder and the working feed by a re-circulating ball screw with double preloaded nut.
The brushless motor which moves the screw, is controlled with a closed ring by the millesimal optic rule, which guarantees a positioning precision on the complete stroke of 0,001 mm.

Hydrodynamic type, rotates on anti-friction metal bushes, which guarantees an high finish degree. The rotation is by means of an a.c. motor. On request, the speed may be regulated by an inverter. The transmission is by means of pulleys and Poly-V belt. Also, on request, the machine may be equipped with a second right side wheel.

Together with the workhead the tailstock supports the workpiece weight and the force generated by the grinding operation. The structure in normalised and stabilised cast iron, is in two parts, so as to permit the cylindrical manual correction. Equipped with hydraulic treadle drive tailstock and safety device against accidental opening. The spindle opening is possible only when the grinding wheel is in the back position.

Electronic type by encoder Equipped with double scale : one with division of 0,01 mm. and the other with division of 0,001 mm. The handwheel has a selector to stop to size.

Electronic type by encoder Equipped with double scale : one with division of 0,1 mm. and the other withi division of 0,01 mm.

The diamond dressing device is very strong and is positioned on the tailstock.

In a cabinet, separate from the machine.
Complete with : PLC unit, power circuites, starts for the axis motors and various electronic components. Equipped with a ventilation system where air is preventively filtred.

The hydraulic power pack, is separate from the machine and activates the hydraulic cylinder of the tailstock. It is equipped with an oil-air heat exchanger at thremostatic action. Supplied without hydraulic oil.

The lubrication power pack, is separate from the machine and supplies continuous oil to the wheelhead guides and to the re-circulating ball screw nuts, for the working feeds. The recovered oil is filtred and then returned to the power pack.

Has the function to make lighter, during the manual movements: workhead, tailstock, table and wheelhead over-slide.

Large capacity tank for the coolant water, complete with electric pump. The coolant flow and stop is automatically controlled by an electrovalve with pneumatic servo-control.
On request, coolant magnet cleaner and coolant paper roll cleaner, may be supplied.

For the protection of the operator all movable parts are covered with suitable guards. Precisely: protection casing for belts, protection casing for grinding wheel and bellows for guides. The front protections are sheet sliding doors with poly-carbonate shields. A movable shield in sheet, controlled by a pneumatic cylinder, protects the operator, when the grinding wheel is in rotation and the front sliding doors are open. A safety device, does not permit the automatic cycle to start if the front sliding doors are open.