Application of time servo system in high-position steel tapping machine project

1. Introduction

In China's steel market, the profit margin of medium (thick) plates is relatively large, so the medium (thick) plate production lines of major steel mills have the reputation of "money printing machines". However, with the increasingly fierce market competition and the increasing quality requirements of users for medium (thick) plates, the transformation investment of medium (thick) plate production lines by major domestic steel mills has also increased accordingly. At present, the slab discharge method used by most manufacturers is: after the slab is heated in a three-stage continuous push-steel heating furnace, the pusher located behind the furnace pushes the hot slab out of the front of the furnace, and the hot slab slides along the inclined surface between the heating furnace outlet and the conveying roller by its own weight to the roller to complete the steel discharge process. Such a steel discharge process not only scratches the lower surface of the slab, affecting the surface quality of the slab, but also causes great impact and noise to the conveying roller and buffer, seriously affecting the service life of the equipment. How to discharge steel smoothly has become a difficult problem in the domestic medium (thick) plate production line for many years.

2. Introduction to high-level steel discharge machine

In response to the problems existing in the current steel discharge machine, Shiguang Technology and a system integrator in the industry jointly developed a high-level steel discharge machine. The high-position steel-out machine is mainly used in the field of medium (thick) plate processing in the steel industry. It solves the problem of lower surface slippage of medium (thick) plates during the production process and improves the product quality of the final product of medium (thick) plates. Since this set of steel-out machines is the first to be used in China, there is no competitor in China, and the whole set of equipment has high added value and high profits. The whole set of equipment is advanced in technology: the closed-loop hydraulic lifting device and servo control to achieve accurate positioning of each station are both domestic leading technologies. The whole set of equipment has a wide range of applications and is applicable to all medium (thick) plate production lines in China.

(1) Mechanical structure

The high-position steel-out machine consists of a main beam, a trolley, a small trolley, a gantry and an L-shaped hook for taking out the billet (see Figure 1). The L-shaped hook has three degrees of freedom: the lateral movement for completing the channel selection is performed by the trolley, and the drive form adopts a motor-reducer-drive shaft-gear-rack structure; the longitudinal movement for completing the billet taking out is completed by the trolley, and the drive form is the same as the trolley; the vertical movement is completed by the gantry located in the U-shaped groove of the front column of the trolley, and the hydraulic cylinder drive form is adopted.

Figure 1 High-position steel tapping machine

(2) Working process

The steel pusher behind the furnace pushes the slab to the steel tapping position of the furnace door. This position is measured by laser. Then the furnace door is opened. The trolley drives the steel tapping machine forward until the L-shaped hook is directly below the slab in the furnace and then stops running. The L-shaped hook rises and lifts the slab off the slide rail in the furnace. The trolley drives the steel tapping machine back to the top of the conveyor roller in front of the furnace. The furnace door is closed, and the L-shaped hook descends at a steady speed, placing the slab steadily on the conveyor roller. The roller rotates to transport the slab away, and the L-shaped hook rises to its original position again. At this point, the steel tapping machine completes a steel tapping cycle. The trolley moves horizontally as needed to align the L-shaped hook with the steel tapping position of the left, middle or right track of the heating furnace. This is to facilitate the realization and completion of the next steel tapping cycle.

(3) Electrical control system The

electrical control system of the high-position steel tapping machine is composed of Siemens programmable controller, Shiguang IMS servo controller, etc. The system structure scheme is shown in Figure 2. [page]

Figure 2 System configuration scheme

a. The motor can be operated smoothly in the working range of 0.01Hz to 250Hz.

b. When the motor running speed is lower than 60Hz, 3 times the rated torque output of the motor can be achieved, including 3 times the rated torque output of the motor when the motor is locked at 0Hz (effectively solving the variable frequency starting torque compensation and the motor brake input when starting and stopping).

c. Using the built-in PLC function (16 inputs/13 outputs) of the Shiguang IMS servo controller, the upper PLC is informed of whether the controlled motor has completed the accurate positioning action using the I/O method. The upper PLC verifies whether the actual mechanical positioning result meets the requirements through the corresponding proximity switch signal. The IMS servo controller realizes the accurate positioning of the controlled motor and meets the system requirements once the positioning is completed, effectively avoiding repeated positioning, repeated actions and other links. It not only improves the working efficiency of the system and enhances the anti-interference performance of the system, but also greatly simplifies the calculation work of the upper computer.

d. The program compiled using the QMCL language can not only realize various types of gap compensation by electrical means, but also set the size of the gap by user parameters. It effectively avoids the positioning error caused by the change of mechanical gap after the equipment is put into use for a long time.

e. The system parameters can arbitrarily set the S curve and torque limit value when the motor is running.

f. It has 2 programmable D/A outputs, which can realize the analog output of any monitoring item.

g. After using the Shiguang IMS servo controller to control the motors of the trolley and the car, the upper computer Siemens PLC can fully realize the positioning control and detection of the trolley and the car only through electrical contact input/output (that is, the system adopts a semi-closed loop control method), reducing the relevant wiring, effectively avoiding the introduction of more susceptible links to the entire system, and enhancing the stability and reliability of the entire system.

h. Due to the high ambient temperature at the front end of the car, it is not convenient to install electrical components such as proximity switches, but the system requires that the water cooling equipment be turned on after the car moves to a certain position, and the target position arrival signal is given after reaching the target position. Therefore, the controller needs to understand the position of the car during its movement and be able to give corresponding input/output signals. The IMS servo controller itself comes with an integrated PLC function (16-point input/13-point output), and with the encoder feedback pulse data, the above functions can be achieved by executing the program compiled by the QMCL language software.

i. The unique 0Hz lock function of the IMS servo controller can realize the "electrical brake" action of the motor. It not only effectively guarantees the final positioning accuracy after the positioning control is completed, but also saves the wear of the motor brake plate by the mechanical brake and the position offset generated during the mechanical brake process. In order to ensure that the system will not bring safety hazards in the event of power failure, the system does not remove the mechanical brake of the relevant motor, but the function of the motor mechanical brake is limited to power-off protection.

j. Due to the use of flexible QMCL software programming, whenever the final customer's requirements change or increase or decrease during the debugging process, the IMS servo controller can make corresponding changes at any time according to the customer's latest requirements to meet their needs.

3. Operation effect

(1) Operation of large vehicle

Transverse speed: 1.574～314.8mm/s
Actual working stroke from middle lane to left lane: 2300 mm
Actual working stroke from middle lane to right lane: 2300 mm
Positioning accuracy: 0.002373mm

(2) Operation of small vehicle

Forward and backward speed: 1.574～314.8mm/s
Actual working stroke: 2998.74 mm
Positioning accuracy: 0.002373mm (end)