Following Error Compensation For Thread Cutting; Multiple Thread - Siemens SINUMERIK 840C Installation Instructions Manual

12 Functional Descriptions

12.8 Following error compensation for thread cutting

12.8 Following error compensation for thread cutting
This function is used to correct the starting angle of the spindle by the calculated following
error. This is to ensure that the same number of thread turns is cut at a high speed as at a low
speed.
The offset caused by the following error no longer occurs. This compensation only functions
perfectly when cutting a thread with a constant lead. Depending on the size of the lead
increase the decrease, deviations can occur.
Prerequisites:
• MD 5025, bit 2 "Level-up thread" must be set.
• The servo gain factors of all the axes involved in the thread cutting function must be the
same.
• The value of the servo gain factor in the MD must not be < 200, otherwise alarm no. 2192
"Following error compensation not possible" is triggered.
Operation:
If all the above conditions are fulfilled no further steps are necessary.
However, if the compensation is not functioning perfectly, MD 164 (default value: 36) can be
set to produce a fine compensation (8 to 48). The speed should be constant within one turn.
Depending on the speed increase/decrease, deviations can occur with tapered threads with
constant speed (G96).

12.8.1 Multiple thread

A multiple thread can be cut using a starting angle with this function. Here, the channel-
specific starting angle of the leading spindle is programmed directly via G92A ... for the
individual thread turn.
Example:
The part program will run first with the angle 0 degrees, then 120 degrees and then 240
degrees to produce a three-start thread.
The starting angle is stored in a channel-specific setting data (No. 202*), and is displayed in
the setting data display "Spindle data" where it can be altered.
This setting data can only be written if the MD is set (directly with @410 K202* K.. or using
G92 A.. and direct input via the setting data display), otherwise the alarm "Option not
available" is triggered.
The angle is entered and displayed in 3.5 format. Maximum input value = 999.99999 degrees,
-5
input resolution = 10 degrees, without a sign.
The specified angle is always calculated modulo 360 degrees. Up to five places after the
comma are accepted.
R parameter chaining is possible.
The last angle to be entered remains active after power off.
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SINUMERIK 840C (IA)