CNC Portique / 1 ou 2 VAB sur l'axe X?

[dotrick]

Bonjour,

Quels sont les paramètres qui déterminent s'il faut mettre une VAB (vis à bille) ou deux sur l'axes des X ?

J'ai pensé aux cas suivants:
- Portique large (Y)
- Efforts importants d'usinage
- Pièce à usiner non centrée sur la table
- Le prix de la CNC!!!

Pour une dimension de X (900) Y (600) Z (200) et de l'usinage d'aluminium en grosse passe (1000N d'effort).

Combien de VAB faut il mettre?

Est ce que cela se démontre par calcul ou simulation? Histoire de voir combien on a de marge...

Merci!

 

[dotrick]

J'ai trouvé une partie de réponse à mes questions sur cnczone : http://www.cnczone.com/forums/diy_cnc_router_table_machines/105679-single_vs_dual_ballscrews.html.

There are several advantages of the two motor/dual drive approach:

1. No under table components (as mentioned). Big advantage for larger tables and any plasma or flame cutting design.
2. Ability to fine tune each side separately so even minor variations can be accounted for
3. Double the torque
4. Ability the have separate home switches to force the gantry to square every time you do a REF.
5. Less mechanical complexity. Less mechanical loss.
6. Easier to do independent mounting and gear mesh control for R & P designs
7. Less rigid gantry construction and rail systems needed
8. Proven design. It is reliable and efficient.

We have four production tables. Three are dual drive and one is a router only single axis drive. The single drive table has a single screw down the middle drive and an Box frame gantry (Top and bottom cross structure). We are limited on speeds and depth of cut on the single drive axis and even with linear precision slides there is some racking when doing heavier cuts. The Dual drive tables have been running for years and are reliable.

TOM caudle
http://www.CandCNC.com