Application of the most popular frequency converte

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Application of universal frequency converter in color steel machinery

with the increasing demand for large workshops and prefabricated houses, the color steel industry has achieved rapid development in recent years, because people generally realize that using steel is more economical and environmental friendly than civil materials. Wuhan Yiding color steel plate Engineering Co., Ltd. is a color steel processing enterprise with medium production scale. They use the pressing equipment of Shanghai Ximing color steel Machinery Co., Ltd. to produce various types of color steel plates, with an annual sales of more than 100 million color steel plates

Shanghai Ximing color steel machinery needs to be equipped with six low-power universal pi7600 series frequency converters, which respectively control the glue pressing motor, spindle motor and cutting stroke motor. The whole equipment is controlled by a Siemens s7200plc and operated by the touch screen. The coordinated operation between the motors is controlled by a PLC that sends switching signals to control the positive and negative operation of each frequency converter. Among them, the key one is the frequency converter that controls the stroke cutting motor, which has frequent faults or protection, Or burn out the module, causing great trouble to the normal production of users

the reason is that this frequency converter has two working states, one is the automatic state and the manual state with PLC sending instructions. The cutting electric saw needs to make a round-trip movement, so the frequency converter receives 13) displacement measurement and control accuracy: not greater than 0.5% of the indicated value to the positive and negative transfer of two switching values. After starting, after the electric saw is cut, there is a travel switch on each side to stop the frequency converter, However, the operating frequency of the frequency converter is basically given by the keyboard potentiometer, so the operation union can adjust it freely according to its desired speed, which has two hidden dangers:

1. As the thickness and material of the cutting plate are different, the load of the electric saw will also be different. If the operating speed of the frequency converter is too fast, that is, the travel of the electric saw is too fast, it is bound to increase the resistance of the electric saw, so the travel motor is overcurrent, Even the travel frequency converter is burnt out

2. If the speed of the control travel frequency converter is too fast, after cutting a piece of plate, the frequency converter still has a large frequency output after receiving the stop command from the travel switch. When the traveling crane reaches the edge, the travel motor will be stopped urgently, which will also be a great feedback current, and the frequency converter will skip the current, or blow up the machine

in view of the above two hidden dangers, we make the following adjustments to the equipment manufacturers:

1. Set different plate cutting modes, and use different travel speeds when cutting thick or hard plates with ordinary plates or thin plates, that is, different operating frequencies. It is recommended that the setting of thick plates should not exceed 20Hz, and the setting of ordinary plates should not exceed 25Hz, This can protect the long-term effective operation of the frequency converter

2. Increase the distance between the travel switch close to the operation console and the edge, so that the stop signal of the frequency converter is sent in advance, so that there will be no electric production power battery caused by the motor touching the edge to supply the machine in the Chinese market

attachment: parameter setting

f00=0 - display the given frequency and keep it not too fast

f04=0 - given frequency of keyboard potentiometer

f04=3 - terminal block control start and stop

f09=8 - starting time 8 seconds

f10=3 - stop time 3 seconds, in order to stop quickly, so as not to cause the cutting stroke motor to hit the edge

terminal connection method: FWD, rev and com terminals are used to control forward and reverse rotation. (whether the oil pipe joint is loose end)

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