The LHC Collimation project

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04.11.2005 Review of Mechanical Movement and Motorization for LHC Collimators The LHC Collimation The LHC Collimation project project LHC Collimators for Phase 1 LHC Collimators for Phase 1 Alessandro Bertarelli TS-MME Direct and reverse torque required for different collimator configurations LHC Collimator Review 04/11/2005

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The LHC Collimation project. LHC Collimators for Phase 1. Direct and reverse torque required for different collimator configurations. LHC Collimator Review 04/11/2005. Alessandro Bertarelli TS-MME. Torque calculations. Outline Actuation system layout Assumptions and hypotheses - PowerPoint PPT Presentation

Transcript of The LHC Collimation project

Page 1: The LHC Collimation project

04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

The LHC Collimation projectThe LHC Collimation project

LHC Collimators for Phase 1LHC Collimators for Phase 1

Alessandro Bertarelli TS-MME

Direct and reverse torque required for different collimator configurations

LHC Collimator Review 04/11/2005

Page 2: The LHC Collimation project

A. Bertarelli TS/MME 04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

Torque calculationsTorque calculations

Outline• Actuation system layout• Assumptions and hypotheses• Some formulas• Minimum motor torque required for direct

motion (pull-in torque)• Maximum admissible residual torque for back-

drive motion (detent torque)• Outlook and risks

Page 3: The LHC Collimation project

A. Bertarelli TS/MME 04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

Actuation system layoutActuation system layout

Motor Pull-in Torque T

Friction Torque C

(bearings, rotating components, etc.)

Resistive force F (weight component,

springs, vacuum, friction …)

Direct mode

Page 4: The LHC Collimation project

A. Bertarelli TS/MME 04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

Actuation system layoutActuation system layout

Motor Detent Torque M

Friction Torque C

(bearings, rotating components, etc.)

Active resulting force F

Reverse mode(auto-retraction)

Page 5: The LHC Collimation project

A. Bertarelli TS/MME 04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

Design data and assumptionsDesign data and assumptions• Motor specifications:

• 400 steps/rev hybrid stepping motor• 3.5 Nm Nominal Torque• 80 mNm maximum Detent Torque

• Re-circulating roller screw • Diamter (d) 12mm –lead (p) 2mm – useful stroke (c) 35 mm – efficiency ()

0.67

• Springs (two versions)• Wire Ø5 – K=5.15 N/mm – Preload=75mm• Wire Ø6.3 – K=12.98 N/mm – Preload=55mm

• Effects taken into account:• Spring loads • Weight of jaw and table assembly• Effect of bellow (both elastic and vacuum)• Ball bearing friction• RF contacts friction• Table friction• No safety margins!!

Page 6: The LHC Collimation project

A. Bertarelli TS/MME 04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

Torque calculationsTorque calculations

Some basic formulas

• Practical direct efficiency:

• Reverse screw efficiency:

• Required torque for direct drive:

• Back-driving torque available at motor

shaft:

501

2 .

MpxF

Tp

2)(

CMpxF

T

2

)(

6090 .. p

Page 7: The LHC Collimation project

A. Bertarelli TS/MME 04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

0 5 10 15 20 25 30 350

100

200

300

400

500

600

700

800

900

1000

1100

12001200

0

T x T1 K hi L hi N mm

T x T2 K lo L lo N mm

c

mm

0 x

mm

Minimum Motor Torque (Pull-in)Minimum Motor Torque (Pull-in)

Spring Ø6.3

Spring Ø5

Orientation Orientation =0° =0°

C-C jawC-C jaw

Full outJaw position

(mm)

Full in

centerline

Pu

ll-in

To

rqu

e(N

mm

)

Page 8: The LHC Collimation project

A. Bertarelli TS/MME 04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

0 5 10 15 20 25 30 350

100

200

300

400

500

600

700

800

900

1000

1100

12001200

0

T x T1 K hi L hi N mm

T x T2 K lo L lo N mm

c

mm

0 x

mm

Minimum Motor Torque (Pull-in)Minimum Motor Torque (Pull-in)

Spring Ø6.3

Spring Ø5

Orientation Orientation =90° =90°

Metal jawMetal jaw

Full outJaw position

(mm)

Full in

centerline

Pu

ll-in

To

rqu

e(N

mm

)

Page 9: The LHC Collimation project

A. Bertarelli TS/MME 04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 0.22 0.24 0.26 0.28 0.30

5

10

15

20

25

30

35

4040

0

c b M K lo L lo mm

c b M K hi L hi mm

300N mm0 M

Return stroke (quasi-static) versus Return stroke (quasi-static) versus Motor Detent TorqueMotor Detent Torque

Spring Ø6.3

Spring Ø5

Orientation Orientation =0°=0°

(C-C jaw)(C-C jaw)

Full in

Full out

Beam axis

Jaw

po

sit

ion

(mm

)

Page 10: The LHC Collimation project

A. Bertarelli TS/MME 04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 0.22 0.24 0.26 0.28 0.30

5

10

15

20

25

30

35

4040

0

c b M K lo L lo mm

c b M K hi L hi mm

300N mm0 M

Return stroke (quasi-static) versus Return stroke (quasi-static) versus Motor Detent TorqueMotor Detent Torque

Spring Ø6.3

Spring Ø5

Orientation Orientation =-90°=-90°

(Metal jaw) (Metal jaw)

Full in

Full out

Jaw

po

sit

ion

(mm

)

Page 11: The LHC Collimation project

A. Bertarelli TS/MME 04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

Maximum Return stroke (dynamic) Maximum Return stroke (dynamic) versus timeversus time

Spring Ø6.3Detent Torque 115 Nmm

Orientation Orientation =0°=0°

(C-C jaw) (C-C jaw) Operating

position

Full out

Spring Ø5Detent Torque 54 Nmm

Jaw

po

sit

ion

(mm

)

Page 12: The LHC Collimation project

A. Bertarelli TS/MME 04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

Maximum Return stroke (dynamic) Maximum Return stroke (dynamic) versus timeversus time

Spring Ø6.3Detent Torque 74 Nmm

Orientation Orientation =-90°=-90°

(Metal jaw) (Metal jaw) Operating

position

Full out

Spring Ø5Detent Torque 12 Nmm

Jaw

po

sit

ion

(mm

)

Page 13: The LHC Collimation project

A. Bertarelli TS/MME 04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

Torque calculationsTorque calculations

Outlook and risks (1)• Maximum required torque (Pull-in) is ~1 Nm for the worst

configuration (metal jaw – vertical configuration – strong spring)

• In a quasi-static motion, full back-driving in the worst case is ensured for any jaw opening only if motor detent torque is smaller than 40 Nmm (or mNm)

• If a maximum detent torque of 80 Nmm is assumed, quasi-static self-retraction is not possible in the worst configuration for strokes smaller than 14mm

• If the jaw is assumed to be in the full-close position (30 mm stroke), full self-retraction is obtained up to ~80 Nmm detent torque

Page 14: The LHC Collimation project

A. Bertarelli TS/MME 04.11.2005Review of Mechanical Movement and Motorization for LHC

Collimators

Torque calculationsTorque calculations

Outlook and risks (2)• No specific safety margins are used for these calculations!• Friction prediction is very difficult and not necessarily

conservative!• Though big care has been paid in its qualification, the

main concern is given by possible degradation of the roller screw efficiency (no auto-retraction is possible if the efficiency is smaller than 0.5)!

• An adequate safety margin should be taken for the minimum pull-in torque and the maximum detent torque (at least 1.5, plus an additional marging from Failure Mode Effect Analysis).