Oulun frequency converter straight wire drawing machine solution

1. Process requirements

1. Wear a mold

 Before the whole machine is started, the front end of the raw materials must be manually polished and passed through the mold step by step. At the scene, the motor is jogged at a low speed through the foot switch, and the tool is used to pull the wire from the front end to the rear end of the mold. After passing the mold, the front end of the wire must be polished or pulled in order to pass the next level of mold. Fine, and then can pass the next level of mold. In this process, the motor is required to have a large and stable torque at start-up and low-speed operation, a stable running speed, and the motor does not reverse during deceleration and shutdown.

2. Brushed

 After finishing the die manually, the whole machine can be run to achieve continuous stretching. Straight-line wire drawing machine is usually controlled by multiple motors, and after multiple drawing dies, the raw material is drawn to the desired wire diameter at one time. In this process, the motor is required to respond quickly, the wire tension is constant, the tension balance bar fluctuation is small, and the wire is not loose.

3. Rewind

 The winding part is driven by an independent motor, and the finished product after stretching needs to be synchronously wound on the I-shaped wheel. As the wire wound on the I-shaped wheel becomes thicker and thicker, the motor speed slows down accordingly. When the thickness of the winding reaches the set value, the system provides automatic detection and shutdown function. Throughout the process, regardless of whether it is starting acceleration, stopping deceleration or stable constant speed, the linear speed of the winding motor and the front-end motor is required to be synchronized, and the wire is not loose. The speed response of the winding motor is required to be fast and speed. Control is precise.

4. Cable

 Generally, the finished wire is wound on the I-shaped wheel in layers. On the horizontal axis of the I-shaped wheel, the wires should be arranged in parallel and tightly round by round. In this process, a wire arrangement device is required to complete the reciprocal arrangement of the wires from the upper end to the lower end of the horizontal axis. The reciprocating speed of the cable arrangement device can be a fixed speed or can be controlled according to the speed of the winding motor. According to the requirements of mechanical design, there are many solutions to realize the cable, such as mechanical and frequency conversion.

Second, the system solution

1. Emergency stop brake

During the operation of the equipment, if an emergency occurs, the entire equipment is required to stop quickly. The process requires that the wire will not be broken after the shutdown process is completed, so as to ensure a smooth start next time.

 During the operation of the equipment, if the equipment detects disconnection or other failures, the entire equipment needs to stop working immediately. The brake circuit can be provided outside the equipment, and the brake signal is output by the equipment to control the operation of the brake circuit, so that the machine can stop quickly. Of course, it is also possible to add a braking resistor inside the inverter to control the complete machine to stop quickly.

2. System composition

The system consists of N general-purpose frequency converters and a tension-specific frequency converter.

 Each general-purpose inverter controls an independent motor, and the wire is stretched step by step through different molds. According to the principle that the volume of the wire is unchanged, as the wire is drawn thinner and thinner, the wire will become longer and longer, which requires that the linear speed of the back-end motor is higher than the linear speed of the front-end motor. The main frequency of the motor of the previous stage comes from the motor of the latter stage. The inverter can use the pulse mode or analog voltage mode to transmit the current frequency of the motor.

 The Nth motor runs at a fixed frequency. The frequency reference can come from the communication RS485 setting, external potentiometer or digital setting. The 1st~N-1th motors use the compound AB frequency operation mode. The main frequency comes from the rear The operating frequency and auxiliary setting of the first-level motor are derived from the PID control of the pneumatic arm balance bar.

 The pneumatic arm is mainly used to sense the tension of the wire, and is passed into the inverter through the AI signal. The system uses the PID function to fine-tune the inverter speed. If the tension is too high, the inverter will properly reduce the frequency, if the tension is too low, the inverter will increase the frequency appropriately. This can make the wire drawing process more stable without breaking or loosening the wire.

 The winding motor is controlled by a tension-specific frequency converter and supports closed-loop adjustment mode with tension swing rod and open-loop adjustment mode without tension swing rod.

 The system controls the operation of the Nth motor through a DI signal, and the operation signal of the previous motor is derived from the operation state of the latter motor, and the winding motor's operation signal is also derived from the operation state of the Nth motor.

 Each inverter provides a broken wire (fault) detection function. If the system detects a broken wire, it will immediately output a signal to the brake circuit. The brake circuit controls the whole machine to stop running, and the signal will be transmitted in the state of an external fault. Give each inverter. The disconnection detection methods include PID feedback detection and DI signal input.

3. Jog

 In order to realize manual threading, the system supports the jog function. The user can set the jogging frequency (E0.00), jog acceleration time (E0.01) and jog deceleration time (E0.02) to achieve the speed of die wear.

The site usually uses the terminal to control the jog. The user can set the X terminal function as forward jog or reverse jog.

The way of jog stop can be controlled by jog deceleration mode (E0.03).

4. Closed-loop control mode

 The tensioning air arm balance bar is connected to the winding inverter. The system can use tension control mode or VF/vector control.

When using the tension control mode, the control method is similar to the previous open-loop tension mode, except that the system has an additional PID closed loop for fine-tuning the tension to ensure that the online tension is more stable.

 If VF/vector control is used, the system can calculate the winding diameter according to the principle of constant linear velocity, V=f*PI*R, where V is the front-end linear velocity, f is the inverter reference frequency, and R is the reel radius. At the same time, the tension arm balance bar is connected to the inverter AI, and the PID is used for closed-loop fine-tuning. As the coil diameter becomes larger and the linear velocity at the front end is stable, the frequency of the inverter reference becomes smaller and smaller.

When the winding diameter of the reel reaches the maximum winding diameter, the system can set the inverter to stop or continue running.