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HS Suprema
 

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Philosophy

Squaring the circle

Main features

Conformation

Structure

Sliding guides

RAM rigidity

Strokes and performances

Movement transmission

                                                                                                               

 

 

Suprema HS… adds up the best of different technologies of guides sliding and therefore allows to face any machining without compromises. 

Philosophy

The need still not satisfied of many uses of medium/large milling machines is to have a machine with the dynamic, the speed, the precision and the repeatability that allow the guides with rolling elements and at the same time: the smoothness, the damping and the exporting capacity that is typical of the prismatic guides with plastic strips.

Squaring the circle

A specifically targeted design to be able to increase significantly the number of rolling elements in contact and to  increase the length of the driving segment that meets the vibrations transmission, has allowed to increase more than double the number of pads for each rail (compared with current applications) without falling into the dangers of hyperstatics that this may cause.
Due to the very high number of pads used, the STS
Suprema HS milling machine combines the undoubted advantages of the guides with rolling elements (recirculating rollers) the damping and smooth behaviour that for some machining, it causes to regret the hydrostatic or creeping guideways. Having summed up in one machine the best features of different technologies creates the most important competitive advantages of this model that can handle any processing, without the compromises of having one technology rather than another.

Main features

STS HS Suprema milling machines are machines with high speed and high dynamic created where the speed, the acceleration and the precision are never enough.

  •  Working speed close to those theoretical planned

  • super mirror finished surfaces

  •  low tool wear because they work at almost constant speed

STS Milling machines Suprema HS model are machine tools for the machining of flat surfaces, of simple or complex profile grooves, of gears, etc. by means of a  interchangeable tool, depending on the type of application. The main features of the machine are:

  •  high productivity

  • excellent surface finish

  • excellent dimensional accuracy of  the parts machined

Conformation

The High-Speed milling machine HS (High Speed) Suprema has a structure with the moving column on the longitudinal axis while the vertical axis is the cradle of the ram transversal axis that carries the head complete with the spindle. The working table is still unless it is equipped with rotary tables or systems rotating-translating systems.

Structure

The longitudinal bedplate, the vertical carriage and the transversal ram are in electro-welded steel and are widely over-dimensioned.

Moreover, the special ribbed structure at closed box make the structures particularly rigid. This structure is unfeasible as a casting.
The column is also made of electro-welded steel, and this choice was dictated by the particular shape of the same column. Infact, the complexity of the ribs and the big  jumps of section between sectors would not have allowed the homogeneity of the casted material.
All the structures suffer more thermal cycles of certificates distension  that eliminate the tensions caused by the various stages of preparation and stabilize them.
All the structures in movement, therefore except the longitudinal basement, are "closed loop" type and this, together with the high number of pads, can very well absorb pressures and vibrations.

Sliding guides

The over dimensional and the large safety margins feature each aspect of the milling machines.  For example the choice of the guides and the pads with recirculating rollers: less than half of the pads would have been sufficient to guarantee rigidity and weight capability with large safety features. The longitudinal movement with ratchet movement transmission with double pinion, double gearbox, two motors and recovery of electronic gap is supported by 15 pads (12 under the column and 3 for the gear carriage), the ram carriage with 8 pads, while the ram reaches 4 guides and 16 pads, 

Nominal load permitted on pads of the table for an ideal length of time (>100Km) for each pad

148.000N

Advised safety factor

1,5

Ideal safety factor

2,0

                                                                                     Longitudinal : pads present 6 for each guide, total of 12.

Excluding those dedicated to the movement transmission carriage and support of the tool exchanger on board.

Safety factor obtainable with 4 pads

4,5

Safety factor obtained with 12 pads

13,5

Nominal load with 12 pads

1.776.000 N

                                                                                     Vertical: pads present 4 for each guide, total of 8.

Safety factor obtainable with 4 pads

9,8

Safety factor obtained with 8 pads

19.6

Nominal load with 8 pads

1.184.000 N

 

Vertical: pads present 4 for each guide for 4 guides, total of 16

Safety factor obtainable with 4 pads

9,85

Safety factor obtained with 16 pads

78.8

Nominal load with 8 pads

2.368.000 N

RAM rigidity

The rigidity of all the machine is particularly high on the transversal axis too, which is the most critical one in this conformation of machine.

The four guides react each with a deformation of 0.010 mm. each 20.000N for each pad and therefore a rigidity of 8.000 N/mm. or 8.000 N/µdimm for each guide which is supported by 4 pads.

The rollers of the guides machine on 45° angles and therefore react on both the orthogonal axes to the guides and for each guide have a reaction both in the longitudinal and the vertical sense.

We will therefore have for each guide a reaction in the longitudinal and the vertical sense.

Having the RAM four guides (therefore 16 pads) the axis will have a rigidity of:

8.000.000 N/mm * 4 guides

therefore 2.000.000 N/mm for 16 pads

 

 

Therefore we will have:

Vertical direction

Total Rigidity pads = 32.000.000 N/mm.

espressed in micron = 32.000 N/µdimm

Longitudinal direction

Total Rigidity pads = 32.000.000 N/mm.

espressed in micron = 32.000 N/µdimm

 

 

 

 

Strokes and performances

The strokes of the machine are: longitudinal 4.500 mm, 6.000 mm and 8.000 mm, transversal 1.200 mm and vertical 2.000 mm.

Another point of strength of the Suprema HS milling machine is the high dynamic. The machine is capable of reaching the best performances compaired to the traditional milling machines:

 *           Feed speed 30m/min.

*           Acceleration of 2 m/s2.

 It is known that these high performances  are easily reached by using linear motors; in our case instead we obtain them with simple brushless motors.

To reach these results, we have developed a machine in a different way to the traditional: we did not start from the design of the mechanical part and then pass to the electronic way, but we chose to do the opposite.

We considered first the part concerning the motors and the movements and on the basis of our choices we have “dressed” the machine around it.

The Suprema HS milling machine can be equipped both with tool magazines with changing places number, at column edge, or with the rack magazines with eight places to be installed on the working table.

The magazines rack type are particularly suggested for all those users that want a functional tool magazine without investing important sums.

To finish the technical features of the Suprema HS, we point out that several controls are available:

           Selca

           Heidenhain

           Siemens

           D.Electron

 

The system is managed by a numerical control with high technology that allows to use each function of the machine using at most all the capabilities.

All the movements of the machine axes and of the automatic tool exchanger group (where foreseen) are checked from numerical control and/or PLC integrated in the same.

 

Movement transmission

Even the movement transmissions have been chosen with generous criteria.

The longitudinal axis is moved by two motors through two precision gears which control two pinions that work on a ratchet. The recovery of the gap is electronically obtained by the numerical control with the two motors.

This allows not to declass the movement transmission of the longitudinal axis.

The transversal and vertical axes, with hydraulic balancing (stroke Z 2.000) have a screw with recirculating spheres Ř63 thread 30mm pre-loaded with double spiral and important with double principle. The double principle allows to have the double of spheres on which distribute the load and therefore cut the wear in half, increasing by double the rigidity. The result is the safety factor compaired to nominal work loads is > of 4 compaired to 1.8 considered ideal by the screw producer.

The movement transmission chains of the linear axes are made by toothed belt transmissions and screw coupling, with single spiral with recirculating spheres, preloaded for the recovery of the mechanical gaps.

The detecting systems of the linear axes, of direct type, are made by linear scales (features of changeable type according to the function of the installed numerical control), fixed along the different working strokes.

All the axes of the machine are moved by motors with alternative electricity (brushless).

All the sliding surfaces and the movement parts are protected against dusts and cutting liquids.

The electro-spindle head, at horizontal axis, is complete with automatic tool blocking and unblocking device.

The position of the electric cabinet can change according to the machine model and the available space. Inside the cabinet (protected from infiltrations) are the electric equipment for the axis of the motor and the spindle, the CNC and all the other electrical equipment.

Suprema HS

                                                                      

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Ultimo aggiornamento: 27-11-09