Fig. 1. Basic information of TWT helix. (a) Helix's outline; (b) distribution of pitch

Fig. 2. Traditional placement of helix

Fig. 3. Variable pitch at start position

Fig. 4. Measurement error of pitch based on point measurement algorithm. (a) Measurement direction deviates from helix axial direction; (b) schematic of error source

Fig. 5. Change of placement height of helix with cone angle in outer diameter (not scaled)

Fig. 6. Pitch boundary was hidden from view

Fig. 7.

Device of placement and adjustment of helix. (a) Isometric view; (b) top view; (c) section view of A-A; (d) partial enlarge view of B; (e) supported position and angle of helix

Fig. 8. Workpiece coordinate system on the placement device. (a) Top view; (b) left view

Fig. 9. Automatic filtering effect based on linear viewfinder. (a) Schematic diagram of burr; (b) effective filtering; (c) invalid filtering

Fig. 10. Error of distance between intersection points caused by unparallel boundary of helix strip

Fig. 11. Repeatability of pitch measurement results

Fig. 12. Outer diameter measurement block

Fig. 13. Schematic of outer diameter measurement

Fig. 14. Inner diameter measuring device

Fig. 15. Automatical search results for the edge of inner diameter. (a) Before optimization; (b) after optimization

Fig. 16. Scanning cloud chart of helix's outer surface. (a) Optical microscope imaging; (b) laser confocal microscope imaging