HEIDENHAIN ND 760 User Manual
User’s Manual
ND 760 E
Position Display Units
for EDM
English (en)
1/2002
Status display:
SET = Datum setting
REF = Blinking:
Traverse the
reference points.
On continuously:
Reference points
have been traversed.
D = SHIFT function
1 2 Datum 1 or 2
Inch = Display in inches
SCL = Scaling factor
->II<- = Touch-off / Centerline
ND 760 E Position Display Unit
(for 3 axes)
HEIDENHAIN
Keys
• Select coordinate axis
• Select axis-specific operating
parameters
Trigger points 1 and 2 before reaching the erosion
depth
Trigger point with respect to MIN position
Keys
Numerical input
• Select datum 1 or 2
• Page backward in the list of special functions
• Page backward in the parameter list
• Cancel entry
• Reset the operating mode
• Zero the selected axis (if activated with P80)
• Select parameter: CL plus two-digit number
• Select the special functions
- Probe for center line
- mm/inch switchover
- Parameter entry
• Page forward in the list of special functions
Add key for the erosion depth
TP3, TP4
Additional switching points, defined with
respect to the top of the workpiece = 0
Trigger point for start position (HOME)
Trigger point for the erosion depth
Switchover from actual position display to MIN
position display
• Change algebraic sign
• Call the most recent dialog
• In the parameter list: change the parameters
SHIFT key
Use of double-function keys
• Confirm entry
• Page forward in the parameter list
3
4
This Manual describes the ND 760 E position display
unit with the following software number or higher:
Part I Operating Instructions
ND 760 E for three axes 366 590-01
About this manual
This manual is divided into two parts:
Part I: Operating Instructions
Fundamentals of positioning
ND functions
Part II: Installation and Specifications
Description of operating parameters
Switching inputs, switching outputs
Fundamentals 6
Switch-on, Traversing the Reference Marks 12
Datum Setting 13
Working with a Scaling Factor 16
MIN Position Display in the EDM Axis 17
Programming the Trigger Points 18
Add Key 19
Description of Switching Output Functions 20
Error Messages 23
Part II
Installation and Page 25
Specifications and following
Part I Operating Instructions
5
Fundamentals
The ND 760 E position display unit was conceived for use on
electrical discharge machines (EDM).
The following functions support operation with EDMs:
7 switching outputs for the EDM axis
Fundamentals
Display of the MIN position, the distance-to-go, and the
total depth in the EDM axis. Because of the quick up-anddown motion of the EDM axis, HEIDENHAIN
recommends displaying only the last minimum position
value.
Simple compensation of the erosion depth with the aid of an
add key.
Simple setup function for finding the center line between
two edges.
6
You can skip this chapter if you are already familiar with
coordinate systems, incremental and absolute dimensions,
nominal positions, actual positions and distance-to-go.
+Y
+Z
Graduation
Coordinate system
To describe the geometry of a workpiece, the Cartesian* coordinate
system is used. The Cartesian coordinate system consists of three
mutually perpendicular axes X, Y and Z. The point of intersection of these
axes is called the datum or origin of the coordinate system.
Think of the axes as scales with divisions (usually in millimeters) which
allow us to fix points in space referenced to the datum.
To determine positions on a workpiece, the coordinate system is laid
onto the workpiece.
The machine axes are parallel to the axes of the coordinate system.
The Z axis is normally the tool axis.
*) Named in honor of the French mathematician and philosopher
René Descartes (1596 to 1650)
Y
–X
+X
Datum or
origin
–Z
–Y
Fundamentals
Z
X
7
Datum setting
The workpiece drawing is used as the basis for machining the workpiece.
To enable the dimensions in the drawing to be converted into traverse
distances of machine axes X, Y and Z, each drawing dimension requires
a datum or reference point on the workpiece (since a position can only be
defined in relationship to another position).
Fundamentals
The workpiece drawing always indicates one absolute datum (the datum
for absolute dimensions). However, it may contain additional relative
datums.
In the context of a numerical position display unit, datum setting means
bringing the workpiece and the tool into a defined position in relation to
each other and then setting the axis displays to the value which
corresponds to that position. This establishes a fixed relationship
between the actual positions of the axes and the displayed positions.
You can set up to 9 absolute datum points and store them in
nonvolatile memory.
1225
750
320
Absolute
datum
0
700
125
216,5
900
950
250
216,5
125
0
-125
-216,5
Relative
datums
250
-250
-250
-125
-216,5
150
0
-150
0
300±0,1
0
0
325
450
8
Absolute workpiece positions
Each position on the workpiece is uniquely defined by its absolute
coordinates.
Z
Example Absolute coordinates of position
X = 10 mm
Y = 5 mm
Z = 0 mm
If you are working according to a workpiece drawing with absolute
dimensions, you are moving the tool to the coordinates.
Relative workpiece positions
A position can also be defined relative to the previous nominal position.
The datum for the dimension is then located at the previous nominal
position. Such coordinates are termed incremental coordinates or chain
dimensions. Incremental coordinates are indicated by a preceding I.
Example Relative coordinate of position 2 referenced to
position 1
If you are working according to a workpiece drawing with incremental
dimensions, you are moving the tool by the dimensions.
Sign for incremental dimensioning
A relative dimension has a positive sign when the axis is moved in the
positive direction, and a negative sign when it is moved in the negative
direction.
:
IX = 10 mm
IY = 10 mm
:
1
Y
X
1
5
10
Fundamentals
Z
Y
10
1
5
2
10
1
10
X
9
Nominal position, actual position and distance-to-go
The position to which the tool is to move is called the nominal position
S
). The position at which the tool is actually located at any given
(
moment is called the actual position (I).
The distance from the nominal position to the actual position is called the
distance-to-go (
).
R
Fundamentals
Sign for distance-to-go
When you are using the distance-to-go display, the nominal position
becomes the relative datum (display value 0). The distance-to-go is
therefore negative when you move in the positive axis direction, and
positive when you move in the negative axis direction.
Y
Z
I
S
R
X
10
Position encoders
The position encoders on the machine convert the movements of the
machine axes into electrical signals. The ND display unit evaluates these
signals, determines the actual position of the machine axes, and displays
the position as a numerical value.
Z
Workpiece
Y
If the power is interrupted, the relationship between the machine axis
positions and the calculated actual positions is lost. The reference marks
on the position encoders and the REF reference mark evaluation feature
enable the ND to quickly re-establish this relationship again when the
power is restored.
Reference marks
The scales of the position encoders contain one or more reference
marks. When a reference mark is crossed over, a signal is generated
which identifies that position as a reference point (scale datum =
machine datum).
When these reference marks are crossed over, the ND's reference
mark evaluation feature (REF) restores the relationship between axis
slide positions and display values which you last defined by setting the
datum. If the linear encoders have distance-coded reference marks,
you need to move the machine axes a maximum of only 20 mm to do
this.
X
Position
encoder
Scale in Distance-coded
linear encoder reference marks
Reference marks
Fundamentals
11
Switch-on, Traversing the Reference Marks
12
0 è 1
ENT...CL
ENT
Crossing over the reference marks stores the most recently defined
assignment of display values to axis slide positions for datum points 1
and 2 in nonvolatile memory.
Note that if you choose not to traverse the reference marks (by clearing
the dialog ENT ... CL with the CL key), this relationship will be lost if the
Switch-on, Traversing the Reference Marks
power is interrupted or when the unit is switched off.
If you wish to use multipoint axis error compensation, you
must traverse the reference marks (see Multipoint axis error
compensation)!
Turn on power (switch located on rear panel). REF
in the status display starts blinking.
Confirm reference traverse mode. REF indicator
stops blinking and stays on. Decimal points blink.
Cross over the reference marks in all axes (in any
sequence). Each axis display becomes active when
its reference mark is crossed over.
Datum Setting
If you want to save the datum points in nonvolatile
memory, you must first cross over the reference
marks.
Only after crossing over the reference marks can you set new
datums or activate existing ones.
In P70, you can select:
Two datum points: The selected datum point
is displayed via 1 or 2
Nine datum points: The selected datum point
is displayed in the uppermost axis via d1 to d9.
You set a datum by first pressing the corresponding axis key
and then entering a numerical value. To transfer the new
datum, press the ENT key. The CL key can be used to clear
an incorrect entry.
To call a datum you have set, proceed as follows:
You have set two datum points in P70:
Select datum 1 or 2.
You have set nine datum points in P70:
Press the datum key (d starts
blinking).
ENT
1
Enter a datum number (1 to 9).
Datum Setting
13
Probing workpiece edges to find a centerline datum
The edges to be probed run parallel to the Y axis.
Follow the procedure below for all centerlines between two edges.
Z
Datum Setting
PROBE MIDP.
1ST POS X (appears only briefly)
14
SPEC
FCT
ENT
X
Select a datum number (see page 13).
Select the special functions.
Confirm the probe centerline
function. SET lights.
Select the X axis (if not already selected).
The >❘❘<- status symbol starts blinking.
Touch the workpiece edge 1 with the tool.
Y
2
1
M
X = 0
X
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