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Application Introduction of Dual-frequency Wire Drawing Machine

Abstract:

Mini-drawing machines controlled by dual frequency are used widely in manufacturers of wire and cable of copper and aluminum basic materials, while as for most wire manufacturers, in the light of the characteristics of steel materials, straight wire drawing machines are employed, among which the dual frequency ones are most widely used, and are the most representative. Introduced in the following are the process and electric control principle of Sunfar electric dual frequency wire drawing machine.

Keywords: Dual-frequency Wire Drawing Machine
       Mini-drawing machines controlled by dual frequency are used widely in manufacturers of wire and cable of copper and aluminum basic materials, while as for most wire manufacturers, in the light of the characteristics of steel materials, straight wire drawing machines are employed, among which the dual frequency ones are most widely used, and are the most representative. Introduced in the following are the process and electric control principle of Sunfar electric dual frequency wire drawing machine.

I. Preface

In metallurgic industry, wire drawing machine is the important equipment in production of metal wires, and its main function is to draw the wires into fine ones of different specifications. There are straight machines, looping ones, wet ones (dual frequency wire drawing machines) and so on according to the working forms and mechanical structures. As to products of different precisions and specifications, as well as different metal types, wire drawing machines of different specifications can be chosen from. Mini-drawing machines controlled by dual frequency are used widely in manufacturers of wire and cable of copper and aluminum basic materials, while straight wire drawing machines are employed more in most manufacturers of steel wires in the light of the characteristics of steel materials, among which dual frequency wire drawing machines are used most widely and are most representative. Introduced in the following are the process and electric control principle of Sunfar electric dual frequency wire drawing machine.

II. Introduction of process

1 Process flow diagram

 

2. Introduction of process

(1) Pay-off: Accuracy requirement of wire pay-off process is not quite high in the wire drawing machine. Dual-frequency wire drawing machine uses wire tension disc for drawing, which is to pay off automatically by the tension of the later drawing.

(2) Drawing: Drawing differs a lot in different metals, product accuracy and requirements. It is controlled by a main motor (called the hose). Metal wire is guided by internal wheel and drawn gradually by molds of each level to produce required wires. When drawing is started, cooling liquid is open to cool molds.

(3) Winding: Winding is of great importance in dual-frequency wire drawing machines, plays a decisive role in performances and is also a vital basis for evaluating electrical performances. Winding is realized by a winding motor. The winding motor drives the winding plate to wind wires. After getting out of drawing, wires go through the tension swing bar, which feeds current tension signal back to the slave machine. Then the slave machine adjusts output frequency on that signal to ensure constant tension.

The wires rise to a guided wheel through the tension swing bar, then are guided to a guide wheel of the traversing machine, which is driven to make to-and-fro motion by a separated small motor, and whose function is to arrange the wires uniformly on the winding plate; the winding motor guide the winding plate to rotate and wind automatically the wires guided by the traversing machine on the winding plate.

Ⅲ. Wiring diagram

1 Wiring diagram of the inverter

 

                                                                    Figure 1

2 Control loop diagram

 

 Figure 2

3 Introduction of the wiring diagram

       Figure 1 is the wiring of the main motor and the winding inverter. The speed of the main motor is set through terminal VC2 by the potentiometer on the operating table. The start signal is given by the start relay KA2, and what is different from other inverter is that the start, stop and speed of the slave motor are given by communicating with the main motor RS485, where separate signal is unnecessary. The feedback signal of the swing bar is input to VC2, and the difference between the given frequency of the main motor and the feedback signal is regarded as the output frequency.

       When going through the wires, the jog control of the main motor is achieved by the pedal switch, but the main motor jogs while the slave one doesn’t. Therefore, the jog signal is only transmitted to the main motor, and meanwhile the main motor is set not to jog simultaneously when setting the parameters.

       Figure 2 is the control loop. Press SB3 to start the main motor, and SB2 to stop it. After being started, the motor speeds up till the start frequency set on the slave motor, (which is usually set at 2HZ, and the minimum at 1HZ), and then control the slave motor to run at the output frequency by the communication through RS485.

       The start of the traversing machine is set by the parameter FDT of the slave motor. If FDT is 2HZ, OCI outputs signal to start the traversing machine when the frequency of the slave motor reaches 2HZ. Travel switches SQ1and SQ2 change the forward and reverse rotation of the traversing machine by the connection or disconnection of contactor KM2.

       A sensor is installed on the main axle of the main motor or the slave one. One circle of the axle rotation output the signal of one pulse to the meter counter, whose function is to set the size of every winding according to the user’s requirement. When the counted meter reaches the set value, the counter outputs signal s to the start circuit of the main motor, so that the system stops automatically. The meter counter need to be reset before restart the main motor next time.

       There are two methods for the brake signal output, one of which is to output directly through the emergency stop button on the control panel, and the other is to be set by the slave motor according to the parameter F8.12-F8.16, and when the condition is achieved, OC2 will output a brake signal. When the brake signal is effective, the main motor and the slave one stop simultaneously, and the brake circuit brakes the winding plate.

IV. Commission

1 Correction of feedback position of swing bar:

By monitoring parameter D-9, adjust parameters F2.2 and F2.3 to make the actual position of the swing bar to the feedback value (that is to make sure that the lowest position of the swing bar D-9=0, and the highest D-9=100, with linear change tend). At the beginning of the start, the swing bar position should be at the lowest feedback value, and when the start is finished, the balance point of the swing bar should be at the set PID position.

2 Commission of the start and stop of the motor:

(1) Acceleration and deceleration time of the main motor: the longer the acceleration and deceleration time of the main motor is, the more stable the start and stop is. It is usually recommended to employ 50s and the above.

(2) Acceleration and deceleration time of the slave motor: there are acceleration and deceleration time 1 and acceleration and deceleration time 4, among which the former is that of the output frequency of the inverter, and the later is that of PID ring output of front feed PID. To ensure the start and stop of the inverter and the rapid response during stable operation, both acceleration and deceleration time should be as little as possible, with the guarantee of no alarm output of the inverter.

(3) Start of the swing bar: the start time of the swing bar refers to the time when the swing bar is drawn to the desired position after starting the slave motor. The longer it is, it is more likely to cause disconnection alarm of the slave motor. The shorter it is, it is more likely to result in the vibration of the swing bar. Linear start is better for the drawing of the swing bar, and F8.0 should be set at a proper value according to the wire specifications.

(4) Linkage ratio: Sunfar inverter has the function of automatically correcting the linkage ratio (set FC.6 as 1, the default value). When commissioning for the first time or change the wires, there is no need to set the linkage ratio, and the slave motor track it automatically by the feedback position of the swing bar after start. Monitor D-22 to see the linkage ratio.

3 Commissioning of stability of swing bar

      The stability of swing bar is the standard to test the performance of the inverter. PID parameter can choose single parameter group, or two parameters to adjust automatically according to the operation frequency. The following is to introduce the commissioning method of PID parameter group.

       (1) Proportional gain: Proportional gain influences the rapid response of PID link, and when large overshoot occurs during the start and stop or stable operation of the swing bar, the parameter can be increased at a proper degree.

       (2) Integration time: Integration time constant is the key parameter to ensure the PID link stable. Increase of the integration time can decrease the vibration of the swing bar in stable operation. Too large integration time constant tends to cause large overshoot of the swing bar.

       (3) Rate time: Rate time constant can enable PID link to make pre-judgment, so as to control the overshoot of the swing bar, but if the parameter is too large, vibration will occur.

       The specific parameters should be commissioned according to the site.    

V. Parameter setting

Parameter setting of the main motor

Function code

Name

Default value

Reference value

Parameter description

F0.0

Operation mode

0

0

Apply the common mode

F0.1

Frequency channel

3

5

Choose VC2 as the frequency setting

F0.4

Running command method

0000

0001

External terminal controls start-stop

F0.6

Steering control

0010

0010

Reverse prevention is effective

F0.8

Upper limiting frequency

50

80

Upper limiting frequency 80

F0.10

Acceleration time1

1

50

Acceleration time 50

F0.11

Deceleration time 1

1

50

Deceleration time 50

F2.9

Max corresponding frequency

50

80

Max analogue corresponding frequency 80

F3.0

X1 function

1

6

X1 jog control

F3.1

X2 function

16

17

X2 external failure output

F3.2

X3 function

3

16

X3 free stop instruction

F9.0

Communication setting

0014

0014

Communication basic setting

F9.3

Communication setting

0010

1111

Communication setting of main motor

Parameter setting of the slave motor

 

Function code

Name

Default value

Reference value

Parameter description

F0.0

Mode selection

0001

0001

Wire drawing mode

F0.1

Frequency input channel

2

2

RS485 frequency input selection

F0.4

Run command channel

0002

0002

RS485 start-stop control selection

F0.6

Steering control

0010

0010

Reverse prevention is effective

F0.8

Upper limit frequency

50

80

Set upper limit frequency as 80Hz

F0.10

Acceleration time

×

1

Acceleration time 1S

F0.11

Deceleration time

×

1

Deceleration time 1S

F2.2

VC2 input lower limit

0

0.5

Minimum feedback voltage of swing bar of 0.5V

F2.3

VC2 input upper limit

10

9.8

Maximum feedback voltage of swing bar of 9.8V

F3.0

Input terminal 1 selection

16

17

External failure emergency stop

F3.6

Output terminal 1 selection

0

2

OC1 choose traversing machine output

F3.7

Output terminal 2 selection

22

22

OC2 brake output

F3.8

Relay output

16

16

Inverter failure output

F3.10

FDT level set

2

2

Traversing machine 2Hz start

F3.11

FDT output delay

0.1

0.1

Traversing machine delays for 0.1S

F4.17

Second acceleration time

1

0.4

PID ring acceleration time

F4.18

Second deceleration time

1

0.4

PID ring deceleration time

F7.0

PID feedback channel

0

1

Choose VC2 for feedback channel

F7.1

PID function setting

0021

0001

Adjust PID using only the first group of parameters

F7.2

Proportional gain 1

1

0.95

Proportional gain 1 is 0.95

F7.3

Integration time 1

10

15

Integration time constant 1 is 15

F7.4

Rate time 1

2

4

Rate time constant 1 is 4

F7.8

PID upper limit amplitude

20

20

PID amplitude of 20

F8.0

Start delay gain

10

8

Start delay is 8

F8.1

Initial action frequency

6

1.5

Start after frequency of main motor is 1.5Hz

F8.12

Disconnection test method

0

2

Test according to the feedback bar

F8.13

Lowest frequency of disconnection test

10

10

Start to test since the slave motor exceeds 10Hz

F8.14

Lower limit of disconnection test

10

20

Lower limit of swing bar 20% test

F8.15

Start delay of disconnection test

6

25

Start delay of disconnection is 2.5S

F8.16

Judge delay of disconnection test

2

0.5

Judge delay of disconnection is 0.5S

F8.17

Automatic reset of disconnection failure

0

1

Automatic reset of failure is effective

F8.18

Automatic reset of disconnection failure

15

7

Automatic reset time of disconnection failure

F9.0

Communication setting

0014

0014

Communication basic setting

F9.3

Communication assistant configuration

0010

0010

Set the station as slave motor

 

 

VI. Matters that should be paid attention o during the commission.

1     The position of the swing bar must be corresponding to the feedback channel in linear relationship, which is the lowest position D-9 is 0, and the highest is 100. If not, it is necessary to adjust the maximum and minimum value of the feedback channel.

2     When the slave motor starts, if the long-time drawing of swing bar is so slow to meet the condition of disconnection, it is possible that the system regards it as disconnection and makes disconnection alarm (FU24). The value of parameter F8.0 should be decreased properly, and it should be checked whether the parameters relevant to disconnection test are set properly.

3     During normal operation, if the tension bar swings violently while the parameter adjusting PID can’t play an effective role, check the cooperating space of the large and small cogs between the feedback potentiometer and the swing bar. It occurs that two much cooperation space of the two cogs causes large swing of the tension bar at the site.

4     When the system runs at a low speed, the tension is stable, but the tension bar swings during high-speed operation, employ two groups of PID parameters, change F7.1 into0021, and adjust it according to the operation frequency. Meanwhile, adjust the second group of parameter in accordance with the adjusted group of parameter.

5     If periodic sudden fluctuations occur during normal operation, pay attention to the position of the travel switch of the traversing machine. If it is not in good position, unevenness on both sides of the winding plate will be caused, so as to change the winding diameter, further influencing the stability of the tension bar.

VII. Characteristics and instructions of monitoring parameter of inverter for wire drawing machine

1     Linkage ratio can be corrected automatically, without considering the linkage ratio or its setting. The wire speed and diameter of the winding plate will be monitored automatically after the start.

2     When stopping or starting at any position, the quality of start-stop will not be influenced by the change of the winding diameter.

3     The main motor and the slave one are controlled by RS485 communication, which makes it convenient to realize the start-stop and frequency giving of the slave motor, decreases the analogue disturbance and simplify the control circuit.

d-0: output frequency of the inverter

d-6: front feed stack frequency

d-8: set value of position of the swing bar

d-9: feedback value of position of the swing bar

d-21: PID ring output frequency

d-22: self-adaption simultaneous gain

VIII. Additional instructions

       On some device, the converting system of the wire drawing machine is compose of the main motor of other brand and the slave motor of Sunfar, and then the remolding is the core in such a situation. The following are matters needing attention when remolding the machine with Sunfar as the slave motor:

(1) The main motor and the slave one cannot be controlled by communication, and the start and stop of the slave motor and the main frequency giving are different from that of the communication control of the main and slave motors. The main motor outputs a FDT signal to give the start signal to the slave motor, and an analogue corresponding to the frequency to be the given main frequency of the slave motor.

(2) In the old system of wire drawing machines, the start and stop of most traversing machines is controlled on the basis of the output frequency of the main motor, which, if the linkage ratio changes a lot, will cause the sign that the traversing machine cannot track the winding plate to start and stop at the proper frequency, resulting in unevenness of the traversing of the winding plate. Based on no change of the original external circuit, the start of traversing is controlled by the slave motor.

(3) In the original system, the brake signal is also controlled by the main motor, and some of the brake time is controlled by the relay. During the remolding, if the brake signal is still controlled by the main motor, it will occur that the brake signal opens without stop of the slave motor, causing blockage alarm of the slave motor.

(4) When changing the original circuit, pay attention to the voltage of all circuits and the coil voltage of the relay, and make it clear whether it is DC or AC.