STAR ball screws with hollow-shaft motorMHS 40 drive unit

RE 83 315/2001-09 Rev.4

Linear Motion andAssembly Technologies

STAR ball screws

2 RE 83 315/2001-09 Rev.4

The conventional drive solutionis to have the screw driven byan AC servo motor eitherdirectly or by way of a V-belt.

The driven screw rotates and the nutperforms the required feed movement.

Axial rigidity values are limited by thelength of the screw and by the endbearings. Positioning accuracy is alsolimited as the result.

Today, a screw’s operating speed comesclose to its critical whirling speed,especially in high dynamic applications.This, combined with thermal influences,makes it very difficult for physical reasonsto implement a high dynamic machineconcept.

It is always a challenge, therefore, for themachine manufacturer to achieve theacceleration and linear speed valuespossible while at the same time obtaininga good level of positioning accuracy.

An alternative approach is todrive the nut

The rotary movement is not performed bythe screw but by the nut with anantifriction bearing. Normally the nut isdriven by way of a toothed belt so that thenut and the screw perform the feedmovement relative to each other. Screwrigidity can be increased by stretching the

The MHS 40 drive unit is anew-type combination of a ballscrew and a digital AC servomotor. Linking the electricdrive directly with themechanical components resultsin the highest traversingspeeds while at the same timeachieving the highest precisionof linear positioning.

In this new development themode of operation of a ballscrew, i.e. its transformation ofa rotary movement into alinear movement, has beenredefined.

screw. In this arrangement there are nolonger any limiting end bearings.Furthermore, it is possible to use a hollowmachined screw with liquid coolant todissipate the heat.

MHS 40 drive unit

Vertical axis of a machining center:

Ball screw with a driven nut and atoothed belt

RE 83 315/2001-09 Rev.4 3

The concept of the MHS 40drive unit goes one - decisive -step further.The nut is connected to the hollow-shaft motor without any additionaltransmission elements. This is anideal concept for high dynamicapplications and makes maximumuse of the dynamic possibilities ofthe ball screw.

The screw of the ball screw assembly ispassed through the hollow rotor shaft ofthe servo motor („hollow-shaft motor“).Transmission elements such as drive beltsor clutches are eliminated together withtheir normally negative effects onprecision. Arranging the servo motor andthe ball screw on one axis helps to savespace.

Vertical axis of a machining center,driven by an MHS 40 drive unit

Thus possibilities of new drive conceptsare given, e.g. more than one motor onone spindle for independent motions.

STAR ball screws

4 RE 83 315/2001-09 Rev.4

User benefits– Economy through the use of a complete

unit consisting of a ball screw, an ACservo motor and a brake

– Adaptation to various speeds and loadsby way of the screw lead

– Various power classes by using differentmotor versions

– Compact design requires littleinstallation space

– Minimal mounting effort by thecustomer and integral functionality

– Low system costs– High positioning accuracy by ball screw

positioning information system– Can be combined with a rail-integrated

measuring system (Star CatalogRE 82 350) for direct travelmeasurement in applications withparticularly demanding requirements

MHS 40 drive unit

Integrated holding brake

Stationary spindle, henceminimal torsional vibrationsand maximal stiffness

Rotating nut directly coupled to therotor

optional liquid coolingof the screw

RE 83 315/2001-09 Rev.4 5

Angular contact ball bearingfor highest axial forces

Integrated multiturn resolverfeedback

Motor winding

STAR ball screws

6 RE 83 315/2001-09 Rev.4

▼

▼

▼

MHS drive unit applications

Hexapod with

MHS actuators

Simulation stage with

MHS actuators

Machine tool axis with

MHS drive unit

All pictures simplified

RE 83 315/2001-09 Rev.4 7

▼

▼

▼

▼Two MHS drive units for

tire molds

Two drive units MHS for coilwinding / cutting

Press with MHS drive unit Tensile testing with MHS drive unit

STAR ball screws

8 RE 83 315/2001-09 Rev.4

MHS 095 B 40 x 5R x 3,5 - 5 66 17,5 26,3 70 3000 30,3 33,740 x 10R x 6 - 4 66 17,5 26,3 70 3000 30,4 33,840 x 12R x 6 - 4 66 17,5 26,3 70 3000 30,5 33,940 x 16R x 6 - 4 66 17,5 26,3 70 3000 30,6 34,040 x 20R x 6 - 3 66 17,5 26,3 70 3000 30,7 34,140 x 40R x 6 - 3 66 17,5 26,3 70 3000 31,6 35,0

MHS 095 C 40 X 5R x 3,5 - 5 88 23 34,5 70 3000 33,8 37,240 x 10R x 6 - 4 88 23 34,5 70 3000 33,9 37,340 x 12R x 6 - 4 88 23 34,5 70 3000 34,0 37,440 x 16R x 6 - 4 88 23 34,5 70 3000 34,1 37,540 x 20R x 6 - 3 88 23 34,5 70 3000 34,2 37,640 x 40R x 6 - 3 88 23 34,5 70 3000 35,1 38,5

Size Load ratingsdyn. stat.

d0 x P x Dw - i C C0(N) (N)

40 x 5R x 3,5 - 5 29100 6410040 x 10R x 6 - 4 50000 8640040 x 12R x 6 - 4 49900 8620040 x 16R x 6 - 4 49700 8590040 x 20R x 6 - 3 37900 6280040 x 40R x 6 - 3 37000 62300

Motor type Ball screw Drive torques Braking torque Max. speed MassSize Max (Nm) Duration* (Nm) (Nm) (min-1) without brake with brake

only Surface (kg) (kg)d0 x P x Dw - i convection cooling

MHS-E-B 40 x 40R x 6-3 1 2 P5 S 51K 309 51K 309 2500 1 1

*Duration at 60 K overtemperature at the motor windings

Ball screw with hollow-shaftmotor

d0 = nominal diameter

P = lead (r = right-hand)

Dw = ball diameteri = number of ball track turns

Technical details of the Star ball screw areto be found in the main catalogRE 83 301/12.99

MHS 40 drive unit

with high-resolution transmitter

options– liquid-cooled screw– integrated holding brake– cooling fan

Order code:

RE 83 315/2001-09 Rev.4 9

114 170 584 214 370 4 87 190 215 M12115 171 600 230 370 4 138 190 215 M12115 171 605 235 370 4 138 190 215 M12116 172 620 250 370 4 153 190 215 M12117 173 618 248 370 4 151 190 215 M12124 180 672 302 370 4 205 190 215 M12127 183 624 214 410 4 87 190 215 M12128 184 640 230 410 4 103 190 215 M12128 184 645 235 410 4 138 190 215 M12129 185 660 250 410 4 153 190 215 M12130 186 658 248 410 4 151 190 215 M12137 193 712 302 410 4 205 190 215 M12

LM180

45° 45°

D7

D6

LE

L10

L

D1

L4

Mass mom. of inertia Dimensions (mm)without brake with brake

(kgm2) 10-4 (kgm2) 10-4 L LM LE L4 L10 D1 D6 D7j6

STAR ball screws

10 RE 83 315/2001-09 Rev.4

51

Form Version Ball screw size Dimensions (mm)

d0 P L D1 DT1 L1 G1 LG1 S

Hex

sock

et

S

K

S

5/309 40 10/12/16/20/40 117 30 h6 83 M30x1,5 34 10

MHS-E-B 40 x 40R x 6-3 1 2 P5 S 51K 309 51K 309 2500 1 1

51

Application

None

Option (machining of end face)

Drive unit MHS screw end machining

Dimensions of liquidcooling on request

Order code:

D1

DT1

L1 LG1

G1

Undercut form F DIN 509

Thread undercut DIN 76 short

L

RE 83 315/2001-09 Rev.4 11

Drive unit

Drive unit MHS, Motor type B

1 ... standard seal 2*... reinforced seal

2 ... 5%

3 ... 2%

P1 P3 P5 ground-thread screw

(P5) T5 precision-rolled screw

R … precision-rolled S … ground-thread

MHS-E-B 40 x 40R x 6-3 1 2 P5 S 51K309 51K309 2500 1 1

Right screw end

Overall length (mm)

0 ... standard (acceptance test report)1 ... lead test report2 ... torque test report3 ...lead and torque test report

0 ... preserved 1 ... preserved and nut with basic grease

Screw

Documentation

see left screw end

Nominal diameter (mm)

Lead (mm)Direction of lead R ...rightBall diameter (mm)Number of ball track turns in the nut

N.B.: It is also possible, to process inquiries based on a customer´s drawings.

* for the precision-rolled version, note higher frictional torque.

Order Code

Form

Option S … hex socket

K … none

Version

Size

Seal

Preload

Precision

Left screw end

Lubrication

Linear Motion andAssembly Technologies

Certified by DQSaccording to ISO 9001

(Reg.-Nr. 1617)

Rexroth Star GmbHLinear Motion and Assembly TechnologiesD-97419 Schweinfurt, Germany

Telephone +49-97 21-9 37-0

Telefax +49-97 21-9 37-2 75(general)

Telefax +49-97 21-9 37-2 88(direct)

e-Mail info@rexroth-star.com

Internet www.rexroth-star.com

Star – Ball screws with hollow-shaft motorMHS 40 drive unitRE 83 315/2001-09 Rev.4

Printed in Germany - p 01/0911/-/-

Great care has been taken during the compilation of thispublication to ensure all the information contained isaccurate. We accept no responsibility however for anydamage resulting from incorrect or incompleteinformation contained.

For deliveries and other services in the course ofcommercial business, the general terms and conditions forsupplies and services contained in the valid price lists andthe confirmations of order apply.

As our products are constantly in the process of furtherdevelopment, they are subject to alteration withoutnotice.