Stacking planes precisely Problem: when many planes are stacked on - - PowerPoint PPT Presentation

20.02.2014 Ulrich Landgraf

Stacking planes precisely

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Problem: when many planes are stacked on top of each other, errors in the thickness of the individual planes will add up Note: we encountered this problem when we wanted to build a precise field cage for a TPC-like chamber Solution: Establish a precise reference for each

• plane. Press each plane indiviually with

some elastic element against this reference

Donnerstag, 20. Februar 2014

20.02.2014 Ulrich Landgraf

Stacking planes precisely

2 1 1 2 2 3 3 4 4 5 5 6 6 A A B B C C D D

State Changes Date Name

Physikalisches Institut Universitt Freiburg Hermann-‑Herder-‑Str. 3

Drawn Checked Standard

Date Name

11.02.2014

• U. Landgraf

General Tolerances Form Tolerances Edge Dimensions Surface

DIN 7167 DIN 7168-‑m DIN ISO 1302 DIN 6784

Scale: Quantity: 5:1 1

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Spacing Planes

ATLAS-‑NSW-‑Micromegas

DEMO

A3

1 /1

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File Name: D:\ATLAS Data\Micromegas\Mechanics\Spacing_Planes.idw

Precision spacer O-‑ring Position of lower surface of the upper panel is defined by upper surface of lower spacer Upper surface of spacer has to be higher than lower plane by at least the planarity of the lower panel upper panel lower panel

0,010 A

A Bolt to press precision spacers together

Donnerstag, 20. Februar 2014

20.02.2014 Ulrich Landgraf

Stacking planes precisely

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Remarks:

• The elastic elements must not be O-rings, also several spring washer types

can be used:

• Also if there are small gaps between the planes the assembly can

be gas tight:

• If applied in many places around the frame this can even flatten a bent plane
• provided the elastic force of the O-rings exceeds the one of the plane!

Compression Ratio

The compression ratio is the ratio between compression squeeze and the uncompressed O-ring cross-section.

Recommended Value

Piston- or Rod-Type Seal Minimum: 5% Target: 20% Maximum: 30% Face-Type Seal Minimum: 10% Target: 25% Maximum: 35%

Calculation

Compression Squeeze Compression Ratio (%) = x 100 CS Compression ratio is typically expressed as a percentage.

taken from Simrit catalog Tolerance for tightness is 25%

• f diameter,

i.e. 750 µm for an O-ring with OD = 3 mm

Compression Squeeze CS H

Donnerstag, 20. Februar 2014

20.02.2014 Ulrich Landgraf

Current FE board model imported

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Full 3D-model of the FE board from board designers imported: Can check now for problems easily!

Donnerstag, 20. Februar 2014