< span style = "font size: 14px;" > the probability of failure of detection components is relatively high compared with NC devices. Cable damage, component fouling and collision deformation often occur. If it is suspected that it is the fault of the detection element, first check the broken, dirty and deformed wireless cable, and determine the quality of the detection element by measuring its output, which requires mastering the working principle and output signal of the detection element. Next, Siemens system is taken as an example

< span style = "font size: 14px;" > (1) output signal. The connection relationship between the position control module of Siemens CNC system and the position detection device

< span style = "font size: 14px;" > the output signal of incremental rotary measuring device or linear device has two forms: the first is voltage or current sinusoidal signal, in which exe is pulse shaping interpolator; The second is TTL level signal. Taking the sinusoidal current output grating ruler of heidenha1n company as an example, the grating is composed of grating ruler, pulse shaping interpolator (exe), cable and connector

< span style = "font size: 14px;" > during the movement of the machine tool, three groups of signals are output from the scanning unit: two groups of incremental signals are generated by four photocells. When two photocells with a difference of 180 ° are connected together, their push-pull forms a phase difference of 90 ° and an amplitude of 11 ° μ The two groups of IE1 and IE2 are similar to sine waves at around A. A, a set of reference signals are connected by two photocells with a difference of 180 ° to push-pull mode. The output is a peak signal ie0, and its effective component is about 5.5 μ A. This signal is generated only when it passes through the reference mark. The so-called reference mark is that a magnet is installed on the shell of the grating ruler and a dry reed is installed on the scanning unit. When approaching the magnet, the dry reed is connected and the reference signal can be output

< span style = "font size: 14px;" > two sets of incremental signals IE1 and IE2 enter the EXE through the transmission cable and connector. After amplification and shaping, they output two square wave signals ua1, UA2 and reference signal ua0 with a phase difference of 90 °. After appropriate combination and processing, these signals can generate five pulses in a signal cycle, i.e. 5 times frequency processing, and send them to the CNC position control module through the connector

< span style = "font size: 14px;" > (2) exe signal processing. The function of pulse shaping interpolator (exe) is to amplify, shape, double frequency and alarm the incremental signal output by grating ruler or encoder, and output it to CNC for position control. Exe consists of basic circuit and subdivision circuit