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The solution to the problem of gravity axis falling in NC lathe

Article source:CNC machiningResponsible editor:adminauthor:Kang Ding hardwarePopularity: Publication time:2017-04-21 16:58 font size:【 large middle Small
The solution to the problem of gravity axis falling in CNC lathe

  The machine tool gravity axis or inclined shaft, in the case of sudden power failure or alarm, there will always be varying degrees of fall. In order to reduce the degree of fall, an analysis is made on the occurrence of this situation, and some solutions are put forward.

  CNC lathe axis of gravity, in the event of servo alarm or emergency stop, would suddenly fall, this happens, will cause the tool damage even threaten the safety of operating personnel, put forward methods to solve this problem this paper from three aspects of system parameters, hardware connection and PLC, in order to avoid the whereabouts of the axis of gravity.

System parameters

FANUC 0i-TD system, in terms of servo parameters, in order to solve the gravity shaft falling, provides the following parameters.


0: emergency stop stop distance shorten function type 2 effective

1: emergency stop stop distance shorten function type 2 invalid

2373 lifting capacity

Setting range: -32769 ~ 32767

Set unit: Um 2374 upgrade time

Set range: 8 ~ 32769

Set unit: ms


0: brake control function is invalid;

1: brake control function

2083 brake control timer

Set range: 0 ~ 16000

Set unit: msec

2210#6, #5

#6 ESPTM1 ESPTM0 #5 delay time (unit: ms)





  Parameters 2373 and 2374 together, to achieve the gravity shaft in the case of servo alarm or emergency stop, gravity shaft lift and stop it. Parameter 2373 is the amount of ascension, the numerical value of this parameter, depending on the degree of gravity axis fall, the greater the distance, the greater the value of the parameter set of 2373. Parameter 2374 is the lifting time, FANUC system requirements, the lifting time of the size of 8ms integer times. This parameter is used to determine the lift time from the emergency stop, which is to reduce the impact of the gravity shaft falling off when the amplifier is switched off. The actual operation of the machine tool, because it is in the lifting process of braking, so the lifting and lifting time is different from the actual situation on the value. When the machine meets the servo alarm, regardless of the rest of the servo shaft is normal, all the shaft amplifier MCC are disconnected; when pressing the emergency stop button of the machine tool, all shaft amplifier MCC are disconnected.

  In order to prevent the gravity axis from falling, the gravity shaft is equipped with a mechanical braking device. However, the following will happen, the servo amplifier MCC in the mechanical brake device before the action in the OFF state, which will lead to the whereabouts of the gravity axis, causing damage to the tool. This time, we can set the parameters of the 2083, the amplifier MCC in mechanical device later in the OFF state; by setting the parameters of 2210#5 and #6, the *ESP signal is SVM in the action at maximum after 400ms. So that the overall movement of the machine to achieve the effect shown in figure B, so as to avoid the occurrence of the gravity axis of the machine tool.

  Two. Hardware connection

  Brake control circuit part, directly controlled by the relay, by observing the PLC signal timing, can be found in the emergency stop signal input to the X8.4 PLC, after 8ms, the emergency stop signal G8.4 will change, at the same time, F0.6 also changed, brake control signal output Y3.4. From the emergency stop switch is pressed to the brake control signal Y3.4 change, there will be a delay of 16ms, this period has fallen a distance.

  In this case, if we in the brake control circuit directly increases a stop switch signal, so, in the emergency stop button is pressed at the same time, brake immediately action, braking device lock, so you can avoid the gravity shaft falling.

  Three.PLC treatment

  If we directly through the F0.6 the signal control machine brake device, this process in fact there is a delay, when we press machine emergency stop button, after the emergency stop signal is transmitted to G8.4 through PLC, after a time, reaction to changes in the F0.6 state, then the braking device will lock. From the analysis of the action, we can find that there is a time difference between the emergency stop switch and the actual action of the mechanical braking device. This distance is about -0.010 ~ +0.010, and because the implementation of components to complete the action time, can not ensure that the same time, all the whereabouts of the fluctuations will be relatively large. If you do not use the gravity shaft lifting function, gravity axis will only fall, falling range of -0.010 ~ 0

  If we control signal circuit of the brake device to increase the emergency stop signal G8.4 or X8.4, this time, if people press the emergency stop button, the brake control device immediately action, can reduce the maximum distance of fall.

  Four. Summary

  Using any of the above methods which can reduce the gravity shaft falling distance, if you use two or more than two, the whereabouts of the distance is reduced to a very low level, about plus or minus 0.002. And, from the cost considerations, the original equipment adjustment, only the original emergency stop relay to replace the 4 open point of the 4 closed point specifications can meet the needs.

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