Fabrication and evaluation of HDDS cells Dec. 1012, ISG9, KEK T. Kume, KEK (Presented by T. Higo) Mechanical evaluation of HDDS cells and estimation toward HDDS1 (H60VG3S18)

HDDS1 Machining procedure 1/3 1. Cut (logging) 2. Rough cut (turning) –finish allowance of mm 3. Anneal –at 500 o C, 2 hours by N 2 substitution or vacuum furnace 4. Machine tuning holes (drilling) 5. Finish OD (turning) –with a soft jaw 6. Semi-finish cup side & finish nesting ID (turning) –with a collet chuck (tong hold of ~3 mm) –constant circumferential speed (2000 rpm, m/rev) –one-stroke-turning for ellipse & cup end –start cutting from the ellipse top (2a) –semi-finishing with an allowance of 20 m on end surface –Finish inside cup

HDDS1 Machining procedure 2/3 7. Semi-finish disk side & finish nesting OD (turning) –with a collet chuck (tong hold of ~7 mm) –check the deflection of the disk end (< 4 m) –constant circumferential speed (2000 rpm, m/rev) –start cutting from the ellipse top (2a) –semi-finishing with an allowance of 20 m 8. Dimension check 9. Milling –8 o relief angle of milling tool(R0.5-flat <12 o ) –large radius of tool path (R2 and 2b <5 o ) 10. Finish cup side (turning) –finish end surface 11. Stamp the number on the disk side

HDDS1 Machining procedure 3/3 12. Finish disk side (turning) –same as 10 but together with the elliptical part 13. Clean & check dimensions 14. Ultraprecision turning of the both end surfaces –at KEK

Fabrication status Quality estimation on HDDS cell fabrication in studying test cells for following two cases 1. HDDS0 dia. 45mm 6 replacement cells for H60VG3N 2. HDDS1 dia. 61mm H60VG3S18

Measurement positions for turning evaluation –radial direction

Turning error-radial direction (samples: HDDS ,2,4 for cutting test) Tolerance: +/-0.02 mm Accuracy: +/-0.01 mm Repeatability: +/ mm Limited by accuracy of lathe

Measurement positions for Turning evaluation -axial direction

Turning Error-axial direction (samples: HDDS ,2,4 for cutting test) Tolerance: p +/-0.01 mm t +/-0.02 mm Accuracy: +/-0.02 mm Limited by operator skill, caused by scratch correction after finish

Measurement positions for Milling evaluation

Milling Error (samples: HDDS ,2,4 for cutting test) Tolerance: h +/ mm HOM +/-0.05 mm Accuracy: ~0.02 mm Repeatability: ~0.005 mm h: Caused by work alignment error HOM: tool diam.

Angle measurement positions

Milling tool path Intersection between 2b and r2 Escape circle radius 2mm for HDDS0 (45mm dia.) 9mm for HDDS1 (61mm dia.)

2b – r2 Typical in HDDS0

Angle between R2 and 2b (samples: HDDS , 7 for RF test, and HDDS for SLAC) Tolerance: <= 5 deg Results: 5-11 deg Caused by work alignment error and tool path along an escaping circle with radius 2mm Shift to escaping circle radius at 9mm for HDDS1, close to b.

R0.5flat tool Milling radius tool for HDDS0 Tool reliaf angle was changed to 8 degrees for HDDS1 In case of HDDS0 Too severe depth control to get rid of edge mark at end of 3 degree wing Escape towards less cutting (floating) side Crossing at circular part Uncontrollable crossing angle Between flat surface to r0.5mm rounding

R0.5 – flat shape in HDDS0 RF test cell #7 cup side Elliptical Slot end point R0.5

Angle between R0.5 and flat (samples: HDDS , 7 for RF test, and HDDS for SLAC) Tolerance: <= 12 deg Caused by tool positioning (axial) error, relief angle of the tool (3 deg), and correction turning after finish against scratch Change relief angle to 8 deg for HDDS1

Elliptical shape and connection RF test cell #7 cup side connection 2a top Elliptical to flat

Angle between ellipse and flat end (samples: HDDS , 7 for RF test, and HDDS for SLAC) Tolerance: <= 1deg Results: 1-3 deg Limited by accuracy of lathe and/or additional flat-part cut without continuous cutting to elliptical part For HDDS1, require continuous cutting between flat part and elliptical part

Turning roughness Elliptical shape Ry=1.7 trace due to tool shape? Flat part Ry=0.5 RF test cell #7 cup side

Roughness of the turned surface (samples: HDDS , 0, 7 for RF test, HDDS for SLAC, HDDS for cutting test) Tolerance: Ry 0.7 m Roughness: ~0.6 m (straight, 1D), ~1.6 m (curve, 2D) Difference of ~1.0 m is caused by tool periphery shape

Milling roughness Roughness Ry 1.6 m Wave 3 m/2mm Slot end turning point with r=1.1mm

Roughness of the milled surface (sample: HDDS for RF test) Tolerance: Ry 1 m Results: m (seems to be) caused by tool mark

Disk flatness (samples: HDDS ,2 and HDDS ,2,4 for cutting test) Tolerance: 2 m More than 30 pts by CMM Result: 13 m (seems to be) limited by lathe accuracy and deformation due to chucking and turning

Cup-side flatness (samples: HDDS ,2 and HDDS ,2,4 for cutting test) Tolerance: 2 m More than 30 pts by CMM Result: 23 m (seems to be) limited by lathe accuracy and deformation due to chucking (Turning only is with copper without annealing)

Parallelism between disk and cup (samples: HDDS ,2 and HDDS ,2,4 for cutting test) Tolerance: 5 m Result: 25 m (seems to be) limited by lathe accuracy and chucking

Conclusion to make H60VG3S18 Mechanical dimension: OK within tuning range Junction angle: should be OK Surface finish: Acceptable Surface flatness: Improve with diamond turning at KEK