Siemens SINUMERIK 840D sl, Function Manual

Page: 1890 / 2184

Detailed Description
2.5 Toolholder with orientation capability
Basic logic functions: Tool Offset (W1)
102
Function Manual, 11/2006, 6FC5397-0BP10-2BA0
2.5.2 Kinematic interaction and machine design
Representation of the kinematic chain
The concept of the kinematic chain is used to describe the kinematic interaction between a
reference point and the tool tip.
The chain specifies all the data required for the toolholder data block in a schematic. To
describe the concrete case with a particular kinematic, the relevant components of the chain
must be assigned real vectors, lengths and angles. The chain represents the maximum
constellation. In simpler applications, individual components can be zero (e.g., kinematics
with one or no rotary axis).
The machine does not have to have axes that rotate the tool and/or workpiece table. The
function can be used even if the orientations are set manually by handwheels or
reconfiguration.
The machine design is described by the following parameters:
•
Two rotary axes (v
1
and v
2
), each with one angle of rotation (α
1
or α
2
), which counts
positively for clockwise rotation facing the direction of the rotation vector.
•
Up to four offset vectors (l
1
to l
4
) for relevant machine dimensions (axis distances,
distances to machine or tool reference points).
Zero vectors
Vectors v
1
and v
2
can be zero. The associated angle of rotation (explicitly programmed or
calculated from the active frame) must then also be zero, since the direction of the rotating
axis is not defined. If this condition is not satisfied, an alarm is produced when the toolholder
is activated.
Less than two rotating axes
The option not to define a rotating axis makes sense when the toolholder to be described
can only rotate the tool in one plane. A sensible minimum data block may, therefore, contain
only one single entry not equal to 0 in the toolholder data; namely, a value in one of the
components of v
1
or v
2
for describing a rotating axis parallel to the axis where the angle of
rotation α1 or α2 is determined from one frame.
Further special cases
Vectors v
1
and v
2
can be colinear. However, the degree of freedom for orientation is lost, i.e.,
this type of kinematic is the same as one where only one rotary axis is defined. All possible
orientations lie on one cone sheath. The conical sheath deforms to a straight line if tool
orientation t and v
1
or v
2
become colinear. Change of orientation is, therefore, not possible in
this special case. The cone sheath deforms to a circular surface (i.e., all orientations are
possible in one plane), if tool orientation t and v
1
or v
2
are perpendicular to each other.
It is permissible for the two vectors v
1
and v
2
to be zero. A change in orientation is then no
longer possible. In this special case, any lengths l
1
and l
2
, which are not equal to zero, act as
additional tool length compensations, in which the components in the individual axes are not
affected by changing the plane (
G17
-
G19
).