4.RTCP (Rotating Tool Centre Point)

4.1 G117 RTCP for rotating heads

The function G117 manages spindle heads mounted on rotating axes. The head may rotate around a single axis (mono-rotating head) or around two cascaded axes, the leading and the following (bi-rotating head). G117 computes the tool displacement generated by head rotations. G117 can be used in two modes: 4.1.1 Static G117 (G117 KA2) The static G117 generates offsets (similar to origins) added to the displayed positions of linear axes (XYZ), without inducing any movement on the axes. The static G117 is used, for example, in three axes machining with fixed slant head . When the static G117 is activated (by G117KA2), the linear axes doesn’t move, but their displayed positions change as a function of the rotating axes positions. Warning : When one rotating axis is moved with static G117 active, the connected linear axes don’t move, nor change the displayed positions. If, after moving the rotating axes, an updating of the correction due to head slant is desired, it is necessary to program again the static G117 with G117KA2. The syntax of static G117 is as follows: G117 KA2 [RA..] [I.. J.. K..] RA : not programmed (or RA0 ) activates spindle parameters set 0 (in the machine setup, up to three parameter sets may be inserted for mono/bi-rotating spindle heads; the RA parameter selects the set used) RA1 spindle parameters set 1 is activated RA2 spindle parameters set 2 is activated I , J , K set the point around which the rotation is made. These values are added to the distance between spindle nose and tool tip, along the three linear axes (XYZ). Their computing must be done by thinking to the machine when the rotating axes are all on their zero point Sample programming for G117KA2 mono-rotating (rotating axis B). The linear axes where G117 acts are X and Z: G0X0Y0Z0 G0B30 (tilts the heads for 30 degrees without moving the linear axes) G117KA2 (computes the offsets along X and Z due to head slant, adding them to displayed positions) … machining with head slanted by 30 degrees … G117KA0 deactivation of static G117 The G117 KA2 doesn’t rotate the working plane. To activate the working plane rotation, it is necessary to combine the usage of G117 and G116.

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