Automatic centering control method for hydraulic cylinder

Abstract

The invention relates to an automatic centering control method for a hydraulic cylinder, which adopts a control system consisting of a displacement sensor, a proportional valve and a programmable controller, the displacement sensor detects the displacement value of a piston rod of the hydraulic cylinder in real time, and the proportional valve receives control information sent by the programmable controller and controls the piston rod of the hydraulic cylinder to move. The method is novel and practical, the centering motion synchronism of the hydraulic cylinder is high through closed-loop control, the displacement is accurate, steel plates with different widths can be centered intelligently and automatically, the centering precision is high, and the centering precision is high. And the phenomena of hydraulic cylinder damage and clamping steel plate deformation and scrapping are avoided, the centering work efficiency is high, and the service life is long.

Description

Technical Field

[0001] This invention relates to a hydraulic cylinder centering device for steel plates, and more specifically to an automatic control method for hydraulic cylinder centering. Background Technology

[0002] When steel plates are rolled, trimmed at the ends, or cut to standard dimensions, a hydraulic cylinder centering device installed before or after the rolling mill or shearing machine is often needed to center the steel plate so that the center line of the steel plate coincides with the rolling or shearing center line. This ensures good symmetry of the steel plate in subsequent processing, thereby improving the dimensional control accuracy of the steel plate and the stability of the processing.

[0003] like Figure 2 As shown, the existing steel plate hydraulic cylinder centering device includes two push plates, four hydraulic cylinders, four hydraulic control valves, and a controller. The two push plates are symmetrically arranged on the left and right sides. Each push plate is connected to the piston rods of the two hydraulic cylinders at both ends on one side. Each push plate is driven by the two hydraulic cylinders. The four hydraulic cylinders are connected to the four hydraulic control valves through hydraulic system connecting pipes. The four hydraulic control valves are connected to the controller through wires. The centering control method of the existing steel plate hydraulic cylinder centering device is open-loop control. The push plate spacing value and the steel plate width value are input into the controller. After analysis and calculation, the piston rod extension value is obtained. The controller inputs control information to the hydraulic control valves. The hydraulic control valves control the extension, retraction, or stop of the hydraulic cylinder piston rods, so that the push plates move to center the steel plate. The existing hydraulic cylinder centering control method for steel plates has the following two shortcomings in actual production: First, the piston rods of the four hydraulic cylinders in the open-loop control have poor synchronization, which causes the push plate to deviate during operation, resulting in inaccurate positioning and centering. In severe cases, it may jam and cause damage to the hydraulic cylinder. Second, the steel plates being rolled, trimmed, or cut to standard dimensions are blank plates. The width value of the steel plate input during centering may differ from the actual width value of the blank plate, which may cause the push plate to clamp the steel plate, causing it to bend, deform, and become unusable. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an automatic control method for hydraulic cylinder centering. The method is novel and practical. Closed-loop control enables the hydraulic cylinder to achieve high synchronization and precise positioning during centering. It can intelligently and automatically center steel plates of different widths, eliminating the occurrence of hydraulic cylinder damage and steel plate deformation and scrapping. The centering work efficiency is high and the service life is long.

[0005] The technical solution adopted in this invention is: an automatic control method for hydraulic cylinder alignment, employing a control system composed of a displacement sensor, a proportional valve, and a programmable controller. The displacement sensor detects the displacement value of the hydraulic cylinder piston rod in real time. The proportional valve receives control information from the programmable controller and controls the movement of the hydraulic cylinder piston rod. The programmable controller reads and analyzes the displacement value detected by the displacement sensor and sends corresponding control information to the proportional valve. The control process of the automatic control method for hydraulic cylinder alignment is as follows:

[0006] (a) Input the push plate spacing value, steel plate width value, same-side threshold, two-side threshold and clamping plate threshold into the programmable controller.

[0007] (b) The programmable controller analyzes and calculates the push plate spacing and steel plate width to determine the piston rod extension value. The programmable controller then sends main control information to the proportional valve, which controls the movement of the hydraulic cylinder piston rod.

[0008] (c) The programmable controller reads and analyzes the displacement value of the piston rod of the hydraulic cylinder on the same side, calculates the displacement difference of the cylinder on the same side, compares and analyzes the displacement difference of the cylinder on the same side with the threshold value on the same side, calculates the additional value on the same side, and sends additional control information to the corresponding proportional valve.

[0009] (d) The programmable controller reads and analyzes the displacement values ​​of the piston rods of the two hydraulic cylinders, calculates the displacement difference between the two cylinders, compares the displacement difference between the two cylinders with the threshold values ​​on both sides, calculates the additional values ​​on both sides, and inputs the additional control information to the corresponding proportional valves.

[0010] (e) When the hydraulic cylinder piston rod extends a certain value, the programmable controller reads the displacement value detected by the displacement sensor on the hydraulic cylinder at a certain unit time reading frequency, puts a certain amount of displacement value into an array for analysis and calculation, calculates the array difference and variance, compares and analyzes the array difference and variance with the clamping plate threshold, when the array difference and variance are not within the clamping plate threshold range, the proportional valve controls the movement of the hydraulic cylinder piston rod according to the main control information issued by the programmable controller, when the array difference and variance are within the clamping plate threshold range, the programmable controller sends a stop information to the proportional valve, and the proportional valve controls the hydraulic cylinder piston rod to stop moving.

[0011] Compared with the prior art, the present invention has the following advantages: the method is novel and practical, the closed-loop control makes the hydraulic cylinder centering movement highly synchronized and precise, and can intelligently and automatically center steel plates of different widths, eliminating the occurrence of hydraulic cylinder damage and steel plate deformation and scrapping, resulting in high centering efficiency and long service life. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of the present invention.

[0013] Figure 2 This is a schematic diagram of the existing steel plate hydraulic cylinder centering device. Detailed Implementation

[0014] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0015] like Figure 1 As shown, an automatic control method for hydraulic cylinder alignment employs a control system composed of displacement sensors, proportional valves, and a programmable logic controller (PLC). Four displacement sensors are fixedly mounted on four hydraulic cylinders and connected to the PLC via wires. The displacement sensors detect the displacement value of the hydraulic cylinder piston rod in real time. Four proportional valves are also connected to the PLC via wires and hydraulic system connecting pipes. These proportional valves control the start, stop, and movement speed of the piston rods of the four hydraulic cylinders. The proportional valves receive control information from the PLC and control the movement of the hydraulic cylinder piston rods. The PLC reads and analyzes the displacement values ​​detected by the displacement sensors and sends corresponding control information to the proportional valves. The control process of the automatic hydraulic cylinder alignment control method is as follows:

[0016] (a) Input the pusher spacing value, steel plate width value, same-side threshold, two-side threshold, and clamping plate threshold into the programmable controller. The pusher spacing value is the actual distance between the two pushers in the steel plate hydraulic cylinder centering device. The steel plate width value is the width of the steel plate blank to be centered. The same-side threshold is 5mm, the two-side threshold is 5mm, and the clamping plate threshold is 0mm to 1mm.

[0017] (b) The programmable logic controller (PLC) analyzes and calculates the push plate spacing and steel plate width to determine the piston rod extension value. The PLC then sends main control information to the proportional valve, which controls the hydraulic cylinder piston rod. The piston rod extension value is calculated as (push plate spacing - steel plate width) / 2. The PLC outputs this piston rod extension value as the main control information to the proportional valve, enabling the proportional valve to accurately move the hydraulic cylinder piston rod to the designated position.

[0018] (c) The programmable controller (PLC) reads and analyzes the displacement values ​​of the piston rods of the hydraulic cylinders on the same side, calculates the displacement difference between the cylinders on the same side, compares the displacement difference with the threshold value on the same side, calculates the additional value on the same side, and sends additional control information to the corresponding proportional valve. The displacement difference between the cylinders on the same side is the absolute value of the difference between the displacement value of one cylinder on the same side and the displacement value of the other cylinder on the same side. The formula for calculating the displacement difference between the cylinders on the same side is: |displacement value of one cylinder on the same side - displacement value of the other cylinder on the same side|. The PLC reads the displacement values ​​detected by the displacement sensors on the two hydraulic cylinders on the same side, analyzes and calculates the displacement difference between the two hydraulic cylinders on the same side, and compares the displacement difference with the threshold value on the same side. Threshold comparison analysis is performed. When the displacement difference between cylinders on the same side is less than the threshold value, the proportional valve controls the piston rod movement of the hydraulic cylinder according to the main control information issued by the programmable controller. When the displacement difference between cylinders on the same side is greater than the threshold value, the programmable controller analyzes and calculates the displacement difference between cylinders on the same side, calculates the additional value, and identifies the slow-moving hydraulic cylinder. The programmable controller uses the additional value as additional control information and inputs it to the proportional valve of the corresponding slow-moving hydraulic cylinder. This causes the proportional valve of the slow-moving hydraulic cylinder to control the slow-moving hydraulic cylinder to start accelerating, gradually reducing the displacement difference between the two hydraulic cylinders on the same side. This allows the push plate on the same side to be pushed out synchronously, preventing deviation or jamming that could damage the hydraulic cylinder.

[0019] (d) The programmable controller reads and analyzes the displacement values ​​of the piston rods of the hydraulic cylinders on both sides, calculates the displacement difference between the two cylinders, compares the displacement difference between the two cylinders with the threshold values ​​on both sides, calculates the additional values ​​on both sides, and inputs additional control information to the corresponding proportional valves. The displacement difference between the two cylinders is the absolute value of the difference between the average displacement of the cylinders on one side and the average displacement of the cylinders on the other side. The average displacement of the cylinders on the same side is the sum of the displacement values ​​of one cylinder on the same side and the displacement values ​​of the other cylinder on the same side, divided by 2. The formula for calculating the displacement difference between the two cylinders is: |average displacement of the cylinders on one side - average displacement of the cylinders on the other side|. The formula for calculating the average displacement of the cylinders on the same side is: (displacement value of one cylinder on the same side + displacement value of the other cylinder on the same side) / 2. The programmable controller reads the displacement values ​​detected by the displacement sensors on the four hydraulic cylinders on both sides. After analysis and calculation, the displacement difference between the four hydraulic cylinders on both sides is calculated. This displacement difference is compared with threshold values ​​on both sides. When the displacement difference is less than the threshold values, the proportional valve controls the piston rod movement of the hydraulic cylinder according to the main control information issued by the programmable controller. When the displacement difference is greater than the threshold values, the programmable controller analyzes and calculates the additional values ​​on both sides. Simultaneously, it identifies the hydraulic cylinder on the slower side and inputs these additional values ​​as additional control information to the proportional valve of the corresponding slower-moving hydraulic cylinder. This causes the proportional valve of the slower-moving hydraulic cylinder to control its acceleration, gradually reducing the displacement difference between the four hydraulic cylinders on both sides. This allows the push plates on both sides to extend synchronously, ensuring that the push plates travel the same distance in the same amount of time, thus ensuring precise alignment.

[0020] (e) When the hydraulic cylinder piston rod extends a certain value, the programmable controller reads the displacement values ​​detected by the displacement sensor on the hydraulic cylinder at a certain reading frequency per unit time. A certain number of displacement values ​​are placed in an array for analysis and calculation, and the array difference and variance are calculated. The array difference and variance are compared with the clamping plate threshold. When the array difference and variance are not within the clamping plate threshold range, the proportional valve controls the movement of the hydraulic cylinder piston rod according to the main control information issued by the programmable controller. When the array difference and variance are within the clamping plate threshold range, the programmable controller sends a stop message to the proportional valve, and the proportional valve controls the hydraulic cylinder piston rod to stop moving. The array difference is the sum of all displacement values ​​in the array divided by the number of displacement values. Subtracting the difference of the first displacement value, the variance is the sum of the squares of the differences between each displacement value in the array and the average of all displacement values, divided by the number of displacement values. The programmable controller reads the displacement values ​​detected by the displacement sensor on the hydraulic cylinder at a reading frequency of 0.2 seconds, and reads them 10 times in a row. The 10 displacement values ​​are put into an array for analysis and calculation to calculate the array difference and variance. When the array difference and variance are within the threshold range of the clamping plate, the programmable controller analyzes and concludes that the push plate has clamped the steel plate. The programmable controller sends a stop message to the proportional valve, and the proportional valve controls the piston rod of the hydraulic cylinder to stop moving. It can intelligently and automatically center steel plates of different widths, and prevent the occurrence of deformation and scrap of the clamped steel plates.

[0021] Not limited to this, any variations or substitutions conceived without inventive effort should be included within the scope of protection of this invention. Therefore, the scope of protection of this invention should be determined by the scope defined in the claims.

Claims

1. An automatic control method for centering a hydraulic cylinder, characterized in that, The control system, composed of a displacement sensor, a proportional valve, and a programmable logic controller (PLC), uses the displacement sensor to detect the displacement value of the hydraulic cylinder piston rod in real time. The proportional valve receives control information from the PLC and controls the movement of the hydraulic cylinder piston rod. The PLC reads and analyzes the displacement value detected by the displacement sensor and sends corresponding control information to the proportional valve. The control process of the automatic hydraulic cylinder alignment control method is as follows: (a) Input the push plate spacing value, steel plate width value, same-side threshold, two-side threshold and clamping plate threshold in the programmable controller. (b) The programmable controller analyzes and calculates the push plate spacing and steel plate width to determine the piston rod extension value. The programmable controller then sends main control information to the proportional valve, which controls the movement of the hydraulic cylinder piston rod. (c) The programmable controller reads and analyzes the displacement value of the piston rod of the hydraulic cylinder on the same side, calculates the displacement difference of the cylinder on the same side, compares and analyzes the displacement difference of the cylinder on the same side with the threshold value on the same side, calculates the additional value on the same side, and sends additional control information to the corresponding proportional valve. (d) The programmable controller reads and analyzes the displacement values ​​of the piston rods of the two hydraulic cylinders, calculates the displacement difference between the two cylinders, compares the displacement difference between the two cylinders with the threshold values ​​on both sides, calculates the additional values ​​on both sides, and inputs the additional control information to the corresponding proportional valves. (e) When the hydraulic cylinder piston rod extends a certain value, the programmable controller reads the displacement value detected by the displacement sensor on the hydraulic cylinder at a certain unit time reading frequency, puts a certain amount of displacement value into an array for analysis and calculation, calculates the array difference and variance, compares and analyzes the array difference and variance with the clamping plate threshold, when the array difference and variance are not within the clamping plate threshold range, the proportional valve controls the movement of the hydraulic cylinder piston rod according to the main control information issued by the programmable controller, when the array difference and variance are within the clamping plate threshold range, the programmable controller sends a stop information to the proportional valve, and the proportional valve controls the hydraulic cylinder piston rod to stop moving.

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