Defect training and cause diagnosis
(1) overtime
An alarm to the range occurs when the movement of the power supply exceeds the flexible limit defined by the software or the hard limit determined by the limit switch. The alarm content will generally be displayed on the CRT. Depending on the CNC system instructions, you can help out and delete the alarm.
(2) overload
When the load of the movement of food is too large, frequent front and rear movements, and poor lubrication of the transmission chain will cause an overload alarm. Generally, alarm information such as the overload of the servomotor, the overheating or the overcurrent will be displayed on the CRT. At the same time, on the power training unit in the solid electric cabinet, the indicator or the digital tube will invite the driver’s unit for overload, overcurrent and other information.
(3)
The phenomenon of lighting occurs during power supply, and the reasons include: ① The speed measurement signal is unstable, such as the failure of the speed measurement device, the feedback signal of the speed measurement is disturbed, etc.; ② The speed control signal is unstable or disturbed; ③ The wiring terminals are poorly contacted, such as loose screws, etc. When the contractions occur at the time of the switching between the forward movement and the inverted movement, it is generally caused by the opposite difference in the supply chain of power supply or the excessive gain of the Servo system.
(4) crawl
It occurs during the start -up acceleration stage or low -speed power supply, which is generally caused by factors such as poor lubrication status of the supply chain, a low gain of servomotor system and excessive external load. It is particularly important to note that the coupling used to connect the servomotor and the ball screw is not synchronized due to loose connections or coupling defects itself, such as cracks, causing the rotation of the ball screw And the rotation of the servo The engine is not synchronized, causing the movement is rapid and slow, causing a ramp.
(5) Vibration
When the tooltip operates at high speed, vibrations can occur and an overcurrent alarm will occur. The vibration problems of tooltips are generally a speed problem, so you have to look for the speed ring, that is to say for any problem related to speed, you must search for the cruise control. Therefore, the problem of vibrations should look for the cruise control. The defect is mainly found from the three aspects of the given signal, the feedback signal and the cruise control itself.
① First check the signal input into the cruise control, that is to say the given signal. The given signal is sent by the position deviation counter, converted into an analog VCMD via the D / A converter, then introduced into the cruise control. You must check if this signal has a vibration component. D / A converter or a position deviation counter to find the problem. If it is normal, turn in search of problems with speed test generators and servomotors.
② Check the speed test generator and the servomotor. When the machine-tool vibrates, this means that the speed of the machine-tool oscillates and that the feedback of the waveform of the speed measurement generator must also oscillate. Currently, it is preferable to measure if there is a precise proportional relationship between the frequency of vibration of the machine tool and the speed of rotation of the engine. The engine or speed measurement generator must be taken into account. First, check if the engine is defective, check the surface condition of its carbon brush and its switch.
③ Care regulator failure. If the above method cannot completely eliminate vibrations and there is no improvement, the problem of the cruise control itself must be taken into account.
④ Check the relationship between the frequency of vibrations and the power speed. If the two are proportional, with the exception of the reasons for the resonance of the machine, most of them are caused by the precision of interpolation of the CNC system or the position detection gain is too high, and an adjustment of ‘Interpolation and adjustment of the detection gain are necessary. If it is not linked to the power speed, there may be reasons such as setting the speed control unit does not correspond to the machine tool, the speed control unit n ‘is not well adjusted, the speed gain of the tree is too large, or the printed circuit card of the speed control unit is bad.
Example: repair of defects of the oscillation of the X axis
Fault phenomenon: a CNC machine with Fanuc OMC, the load of the X axis of the machining center sometimes rises 80%, and the engine of the X axis is buzzing;
Analysis and processing process: Observation on site revealed that the frequency of the engine bundle of the X axis is low, it is therefore judged that the oscillation of the X axis occurs. The reasons for the oscillation are: ① The gain in the tree position of the tree is inappropriate; After checking that the position gain of the X axis has not changed, the load is also normal. Since this machine tool has been rectified, the release of the X axis is important and the difference is offset. After having verified the compensation parameter of space X 0535, the adjustment value is 250 and the difference in the real X axis is measured using the dial counter to compensate for the transition; at 200.
(6) The servomotor does not turn
In addition to the input of the speed control signal in the power drive unit, the CNC system also has a Servo activation control signal, which is generally a DC + 24 relay coil voltage V. ① Check if the CNC system has a speed control signal output; ② Check if the activation signal is activated. Observe the I / O status via CRT and analyze the PLC scale diagram of the machine (or the flow graph) to determine whether the starting conditions of the power tree, such as lubrication, cooling , etc. are filled; , electromagnetic braking must be verified if the movement is released; ④ The food driving unit is defective;
(7) Position error
When the Servo axis goes beyond the position tolerance range, the CNC system will generate alarms with an excessive position error, including tracking error, outline error and positioning error. The main reasons are: ① The tolerance range defined by the system is small; Balance device (like the balance cylinder when the pin box is moved vertically, etc.) unstable.
(8) Drive
When the control value is zero, the coordinate axis is still moving, resulting in a position error. Eliminated by drift compensation and zero speed adjustment on the drive unit.
(9) Back to the default of the reference point
The defaults of the reference point are generally divided into two categories: cannot find the point of reference and cannot find the point of reference. The type of previous defect is generally the signal failure generated by the point of redirection of the reference point or the zero pulse signal. This last type of defect is the reference point switch.
(10) The servomotor automatically turns after starting
The main reasons are: ① polarity error in position feedback;
Diagnosis of FLOW OF FOOD CORAGES
1. DC drive
PWM speed regulation uses a pulse width modulator to control the switching time of a high power transistor. Convert the speed control signal into a square wavestation of a fixed frequency and apply it to the two ends of the CC servomotor frame. , thus controlling the reinforcement current, then controlling the servo. The regulation of the speed of the thyristor uses a cruise control to control the angle of conduction of the thyristor and modifies the voltage at the two ends of the frame by modifying the magnitude of the angle of conduction, thus achieving the purpose of the speed regulation.
1. The CRT has an alarm display defect. The reasons for the overheating alarms are as follows: ① The cutting conditions of the tool-machine and the friction torque of the tool-tool, which operates the overload relay in the main circuit; The transformer itself is defective, which operates the thermal control switch of the transformer. Thermal switch in the engine to operate.
2. For the defects indicated by the alarm indicator, for the alarm lights on the circuit cards printed in the Fanuc system and the control unit of the Siemens system, the functions, the causes of the failures and Troubleshooting methods can be referred to the corresponding machine tool manual.
3. Faulages without alarm display: ① The machine tool is out of control. The speed feedback signal is a positive feedback signal, which often occurs during maintenance and debugging it, and is generally caused by a poor connection of the cable signal line. ② Vibration of the machine. The errors of adjusting the parameters of the system linked to the position control, such as errors in the adjustment of the magnification of the CRM command and the DMR detection magnet. Check the vibration cycle of the machine tool. like the contact of the brush of the speed measurement generator on the servomotor; If it is weakening and the frequency of vibrations is of several tens of hertz to several hundred hertz, that is to say the frequency of vibration inherent in the machine-tool, it can be resolved by the relevant parameters of the printed circuit card. If the vibration does not weaken, it means that the printed circuit card is defective. ③ Low positioning precision. In addition to the large error in the machine’s supply chain of the machines, it is also linked to the low gain of the Servo system. ④ The engine works too much noise. The surface roughness of the servo switch is mediocre or damaged; ⑤ The servomotor does not turn. The permanent magnet of the engine falls;
2. AC power drive
1. Basic inspection of the AC servomotor. In principle, the AC servomotor may not require repair because it is not damaged. However, as the ACA servomotor contains a precision detector, it can cause failure when there is a collision or an impact. Normally, by hand; ③ With the brake, the brake is normal;
2. Precautions for the installation of AC servomotors. Once the maintenance is completed, the following points must be paid attention when installing the servo:
① Since the waterproof structure of the servo system is not very tight, if cutting the liquid, lubrication oil, etc. enter inside, it will lead to a degradation of insulation performance or short-circuits of winding. the infiltration of the cutting fluid as much as possible;
② When the servomotor is installed on the gearbox, when filling the lubrication oil, you must pay attention to the height of the surface of the lubrication box of the gearbox which must be lower than the tree out of the servo to prevent lubrication oil from entering the interior.
③ When fixing the servo couplings, gears, synchronous belts and other connections, in all circumstances, the force acting on it cannot exceed the authorized radial and axial load.
④ Make correct connections between the servo and the control circuit according to the instructions.
3. SUPPORTS OF AC Servomotors. Including the following points:
① The rotor position detection device is defective. When a hall switch or a photoelectric pulse coder fails, it will cause loss of control and vibrations of the food.
② Use a multimeter or a bridge to measure the CC resistance of the reinforcement of the reinforcement, check if the circuit is broken and use a megohmmeter to check if the insulation is good.
③ Set the mechanical device and turn the rotor by hand. times and stop freely, the engine has damaged;
④ Replacement of the pulse coder. If the Pulse Coder of the Servo AC is poor, the pulse coder must be replaced.
3. Drive of the steps
The step -by -step engine is the most used service service system in open loop control systems. The open loop power supply system has a simple structure, is very practical for debugging, repair and use, is reliable in work and is inexpensive. It has been widely used in machine tools which generally require low precision.
During use, the Pas D En Pas D engine drive system has the following common defects:
1. Engine overheating alarm. The working environment may be too severe and the room temperature is too high;
2. During work, the cries do not turn. The possible reason is that the input pulse frequency is too high, causing a blockage, which can be eliminated by reducing the input pulse frequency; The input pulse frequency is too high, which can be eliminated by reducing the input pulse frequency.
3. During parking during work, a sudden parking failure occurs under normal working conditions.
4. Step by step engine fails or several stages.
5. The operation is uneven and there are tremors. It is reflected in the treatment of the part which has vibration marks and has a great roughness of the surface.
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