Tightening group for a rim of or for a tired wheel

1. A group for tightening a rim of or for a tired wheel comprising a base, a main wheel-holder or rim-holder plate or table, said table being supported by said base and defining at least three slide tracks or guides, at least three jaws or jaw or gripper components, each slidably mounted in a respective slide track or guide between at least one first approached position and at least one second moved-apart position, said jaw components being set to tighten a respective portion of a rim of or for a tired wheel in said at least one first approached position and/or in said at least one second moved-apart position, wherein said group comprises at least three actuators, each constrained or pivoted to a respective jaw component and set to move it between said at least one first and said at least one second position, said group for tightening further comprising means for synchronizing the movement of said at least three jaw components, said synchronization means being set to maintain said at least three jaw components at a same distance with respect to the center of said table, such that said jaw components apply the same tightening force to a respective portion of a rim mounted on said table, wherein said actuators are angularly movable with respect to said table and wherein said synchronization means are set to maintain said at least three actuators always in the same angular position with respect to each other, during the movement by said at least three actuators of said at least three jaw components between said at least one first and said at least one second position.

2. The group for tightening according to claim 1 , wherein said synchronization means comprise a frame pivoted to said table, while said actuators are fixed to said frame.

3. The group according to claim 2 , wherein said frame is centrally pivoted to said table.

4. The group according to claim 2 , wherein each of said actuators comprises a cylinder as well as a stem slidably mounted within the respective cylinder and wherein the cylinders or the stems of said actuators are cantileverly supported by said frame.

5. The group according to claim 1 , wherein the stems or the cylinders of said actuators are pivoted below a respective jaw component.

6. The group according to claim 1 , wherein said synchronization means comprise connection means and wherein each of said actuators comprises a cylinder as well as a stem slidably mounted within the respective cylinder, the cylinders or the stems of said actuators being pivoted to said table, while the stems or the cylinders of said actuators are constrained to one another by means of said connection means.

7. The group according to claim 6 , wherein said connection means include a main connection component as well as rod components set to kinematically connect the main connection component and said stems or said actuators.

8. The group according to claim 6 , wherein said connection means comprise fork components or mechanical fixing components between said stems or said cylinders of said actuators.

9. The group according to claim 8 , wherein said fork components or fixing components are set for constraining together at least two stems or cylinders, i.e. constraining or fixing the angular distance of the stems or of the cylinders.

10. The group according to claim 1 , comprising three jaw components slidably mounted in slide tracks or guides that are angularly spaced by about 120° with respect to each other or four jaw components slidably mounted in slide tracks or guides that are angularly spaced by about 90° with respect to each other.

11. The group according to claim 1 , wherein said actuators are pivoted with respect to said table and do not project with respect to the planar bulk of said at least one table or in any case do not increase the part of said actuators that is projecting with respect to the planar bulk of said table in the passage of said jaw components between said at least one first approached position and said at least one second moved-apart position.

12. The group according to claim 1 , wherein at least one actuator is at a level or distance from said table that is different with respect to another actuator.

13. The group according to claim 12 , wherein each of said actuators comprises a cylinder as well as a stem slidably mounted within the respective cylinder and wherein at least two stems of two respective actuators are staggered vertically or in any case according to a direction orthogonal to the main extension plane of said table, but crossed with reference to a plan view, i.e. the vertical plane where the extension direction of one of said stems lies intercepts the other of said two stems, such that the two stems can slide one over the other, in cross direction with respect to the other.

14. The group according to claim 1 , wherein said table comprises a solid of revolution around a symmetry axis, said solid of revolution being configured as a substantially flat discoid element, said slide tracks or guides each being defined by a through slot formed in said discoid element, the slots of said slide tracks or guides extending along lines belonging to the bundle of lines with center in the symmetry axis of said substantially discoid element.

15. The group according to claim 1 , comprising an actuator for each jaw component, such that all said jaws are driving, so that they can all simultaneously apply the same tightening force to a rim mounted on said table.

16. A tire mounting-demounting machine provided with a tightening group according to claim 1 .