Super-thick plate trolley type heating furnace trolley structure and control method

Abstract

This invention discloses a trolley structure and control method for an extra-thick plate trolley-type heating furnace, comprising a trolley body. The trolley structure is characterized by: a composite sealing system comprising sand-sealing blades located on both sides of the trolley and a sealing block located at the rear end of the trolley; a traveling mechanism located below the trolley body; and support legs located at the bottom of the furnace chamber for contacting and supporting the trolley after it enters the furnace. The trolley structure also includes a detection system comprising a laser rangefinder sensor mounted on the furnace end wall and an encoder mounted on the drive motor shaft. The control system is electrically connected to the laser rangefinder sensor, encoder, traveling mechanism, and support legs. This invention's extra-thick plate trolley-type heating furnace trolley structure and control method exhibits a high degree of automation, good sealing performance, strong practicality, and promising application prospects.

Description

Technical Field

[0001] This invention belongs to the field of heating furnace technology in the metallurgical industry, and more specifically, relates to a trolley structure and control method for an extra-thick plate trolley-type heating furnace. Background Technology

[0002] The bogie-type heating furnace is a key piece of equipment for pre-rolling heating of extra-thick slabs. It loads and unloads slabs by moving a bogie carrying the extra-thick slab into and out of the furnace chamber. Extra-thick slabs are typically 360mm or thicker, resulting in a large weight load per unit area on the bogie. During operation, inertia can easily cause slippage between the bogie and the track, leading to errors in the bogie's programming data. Existing bogie-type heating furnaces for extra-thick slabs mainly suffer from the following technical problems: Poor sealing performance leads to severe heat loss and structural damage: Necessary clearance exists between the trolley and the furnace side and tail walls, and the trolley is prone to colliding with the end walls, causing cracks, damage, or even tilting of the end walls, affecting the sealing effect and resulting in losses. Existing sealing methods (such as simple sand seals or labyrinth seals) have limited effectiveness, leading to a large amount of high-temperature flue gas escaping. This not only causes significant heat loss, but the escaping high-temperature flue gas also directly burns the steel structures on both sides and the bottom of the trolley, causing deformation and oxidation, and shortening the equipment's lifespan.

[0003] In the prior art, CN202021607914.1 discloses a U-shaped integral sealing groove structure for a heat treatment trolley furnace, which solves the side sealing problem by cooperating with the upper and lower drive components and the sealing components, but does not involve end sealing; CN92111238.6 discloses a fully enclosed sealed micro-oxidation infrared trolley furnace, which adopts a fully enclosed integral seal, but it mainly solves the static sealing problem and does not consider the impact of positioning accuracy on the sealing effect during dynamic operation.

[0004] Existing control systems largely rely on encoders mounted on the drive motor to calculate the travel distance. Due to factors such as wheel slippage, track wear, and mechanical clearances, cumulative errors can occur between the encoder count and the actual displacement. Over time, this can lead to the trolley failing to reach its designated position or overshooting, requiring frequent manual calibration. Furthermore, the lack of end-point hard limit protection makes it prone to trolley collisions with the furnace end walls during manual or semi-automatic control. In addition, the furnace loading and unloading processes require multiple operator interventions, resulting in inconvenience and low automation. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art, such as poor sealing of the trolley, low degree of automation, and short service life, and to provide a trolley structure and control method for an extra-thick plate trolley-type heating furnace with high degree of automation and good sealing.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The provided trolley structure for an extra-thick plate trolley-type heating furnace includes a trolley body, characterized in that: the trolley structure is equipped with a composite sealing system, the composite sealing system including sand sealing blades disposed on both sides of the trolley and a sealing block disposed at the rear end of the trolley; a traveling mechanism is provided below the trolley body; a support leg is provided at the bottom of the furnace chamber for contacting and supporting the trolley after it enters the furnace; the trolley structure is also equipped with a detection system, the detection system including a laser rangefinder sensor mounted on the end wall of the furnace body and an encoder mounted on the shaft end of the drive motor; the control system is electrically connected to the laser rangefinder sensor, the encoder, the traveling mechanism and the support leg respectively.

[0007] The trolley body adopts a grid-like frame structure, which is composed of crisscrossing reinforcing ribs; the traveling mechanism is a steel wheel, which is directly fixed to the drive shaft by expansion sleeves or key connections.

[0008] The laser rangefinder is installed at the geometric center of the furnace end wall, and its measuring optical axis coincides with the center normal of the fiber module sealing block at the tail end of the trolley.

[0009] The support legs are provided at the four corners near the trolley; the support legs are L-shaped, and the middle of the support legs are supported and connected by a pivot. The support legs are driven by a drive cylinder, and the telescopic rod end of the drive cylinder is connected to one end of the support leg.

[0010] A control method for the trolley structure of an extra-thick plate trolley-type heating furnace, characterized by the following steps: Step 1) The operator clicks the "Automatic Furnace Entry" button on the HMI; Step 2) The PLC checks that the support legs have been retracted and issues a start command, causing the trolley to move into the furnace; Step 3) When the laser rangefinder shows a distance of less than 2m from the end wall, the PLC controls the trolley to slow down; Step 4) When the distance is less than 200mm, the PLC performs precise stopping control and makes fine adjustments based on encoder feedback and stored error compensation values; Step 5) When the laser rangefinder reading reaches the set value, the PLC immediately cuts off the motor power, and the trolley comes to a complete stop; Step 6) After confirming that the trolley has stopped, the PLC controls the support legs to start and complete the support; Step 7) The unloading process is the reverse: the support legs retract first, and then the trolley starts.

[0011] The absolute distance between the tail of the trolley and the end wall of the furnace body is collected in real time by a laser rangefinder sensor installed on the end wall of the furnace body, while the relative displacement value of the trolley is collected by an encoder installed on the end of the drive motor shaft.

[0012] The encoder feedback value is used as the inner loop control parameter to control the trolley's running speed and coarse travel; the laser rangefinder sensor's absolute distance value is used as the outer loop control parameter to perform precise positioning control of the trolley.

[0013] After each trolley completes its furnace entry action and comes to a stop, the actual positioning distance value of the laser rangefinder is recorded. At the same time, the cumulative pulse value of the encoder at that actual positioning distance value is read, and the deviation between the cumulative pulse value and the theoretical pulse value corresponding to the preset standard positioning distance is calculated. This deviation is stored as a system error compensation value. During the next furnace entry control, the positioning control of the encoder is pre-compensated according to the system error compensation value, and the laser rangefinder performs precise calibration in the final positioning stage.

[0014] The absolute distance value collected by the laser rangefinder is used as a hard limit signal. When the absolute distance value is less than the preset safety limit distance, the control system immediately issues an emergency stop command and cuts off the motor power.

[0015] The retracted state of the support legs located at the bottom of the trolley is interlocked with the trolley travel permission signal. The trolley is only allowed to move when the support legs are retracted and locked. The start-up support state of the support legs is interlocked with the trolley entering the furnace position signal. The support legs are only allowed to support when the trolley enters the furnace position and stops.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The trolley structure and control method of the extra-thick plate trolley heating furnace of the present invention effectively solves the problems of poor furnace gas sealing, low positioning control accuracy, insufficient automation and poor reliability of key components. In particular, it solves the coupling problem between sealing effect and positioning accuracy, and realizes the synergy of high-precision positioning and efficient sealing. It has strong practicality and good application prospects. Attached Figure Description

[0017] The following is a brief explanation of the contents depicted in the accompanying drawings and the markings therein: Figure 1 This is a schematic diagram of the trolley structure of the extra-thick plate trolley-type heating furnace in an embodiment of the present invention; Figure 2 yes Figure 1 Schematic diagram of the local method structure in AA; Figure 3 This is a schematic diagram of the laser ranging sensor arrangement structure in an embodiment of the present invention.

[0018] The diagram is marked as follows: 1. Cart body; 2. Sand sealing knife; 3. Sealing block; 4. Steel wheel; 5. Support leg; 6. Laser rangefinder sensor; 7. Furnace end wall; 8. Sand sealing groove. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0020] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0021] This invention discloses a trolley structure for an extra-thick plate trolley-type heating furnace. The trolley structure includes a trolley body 1, employing a grid-like frame structure composed of multiple layers of interlaced reinforcing ribs to form a high-rigidity support structure, significantly improving overall bending and torsional resistance and ensuring minimal deformation under extreme heavy loads. The trolley structure utilizes a composite sealing system, including sand-sealing blades 2 located on both sides of the trolley and a sealing block 3 located at the rear end of the trolley. The sealing block 3 is made of high-temperature resistant fiber modules. The sand-sealing blades 2 cooperate with sand-sealing grooves 8 below the furnace sidewall to form a dynamic sand seal. A buffer block, also made of high-temperature resistant fiber modules, is located on one side of the furnace endwall opposite the sealing block 3. The buffer block is supported and connected by a retractable buffer device. After the trolley enters the furnace, the sealing block 3 flexibly fits against the buffer block on the furnace endwall, both filling gaps to prevent flame ejection at the furnace tail and providing a buffering effect.

[0022] In this invention, a laser rangefinder 6 is installed at the geometric center of the furnace end wall 7, and the measuring optical axis of the laser rangefinder 6 coincides with the center normal of the fiber module sealing block at the tail end of the trolley. With this configuration, the absolute distance measured by the laser rangefinder directly corresponds to the compression amount of the fiber sealing block, enabling visual monitoring of the sealing status. When the measured value deviates from the preset compression range (80-120mm), the control system determines that the seal has failed and issues an alarm.

[0023] This invention includes a traveling mechanism comprising solid, wear-resistant steel wheels 4. These wheels are directly fixed to the drive shaft via expansion sleeves or key connections. A chain plate connects all the steel wheels. Each wheel has a raised edge in the middle, positioned within the gap between the double rails at the bottom of the trolley and the ground. The wheel edge exerts force on the upper and lower rails, eliminating the need for traditional bearing structures and the risk of bearing damage at high temperatures. Support legs 5 are installed at the bottom of the trolley to control and support it after the trolley enters the furnace, sharing the weight of the billet, reducing the load on the traveling wheels, and improving the static stability of the trolley during the heating process.

[0024] The trolley structure of this invention includes a detection system, which comprises a laser rangefinder 6 mounted on the furnace end wall 7 and an encoder mounted on the drive motor shaft. The control system is electrically connected to the laser rangefinder, encoder, traveling mechanism, and liftable support legs, respectively, and is used to execute the control method of this invention.

[0025] In this invention, a laser rangefinder sensor is installed at the geometric center of the furnace end wall, with its measuring optical axis coinciding with the central normal of the fiber module sealing block at the tail end of the trolley. The support legs are driven by hydraulic cylinders, electric push rods, or lead screw and nut mechanisms. The high-temperature resistant fiber module sealing block is a zirconium-containing ceramic fiber module, detachably mounted to the tail end of the trolley using bolts. A zirconium-containing ceramic fiber module (e.g., zirconium aluminosilicate fiber) is fixedly installed on the steel structure at the tail end of the trolley using heat-resistant steel anchors. This module possesses high refractoriness (>1400℃), low thermal conductivity, and excellent elastic recovery performance. When the trolley fully enters the furnace and reaches the set position, the tail end of the trolley, under precise control of the drive system, gently presses against the fiber module installed in a movable box with a buffer device at the furnace tail. This fiber module box is positioned at the bottom of the end wall corresponding to the fiber module at the tail end of the trolley, achieving soft contact and compression between the trolley and the bottom of the end wall. The fiber module is moderately compressed to form a tight, shock-absorbing, flexible seal that completely seals the tail gap.

[0026] In one embodiment of the present invention, the support legs are driven by a drive cylinder. Support legs are located at each of the four corners near the trolley; the support legs have an L-shaped structure, with the middle of the support leg supported and connected by a pivot. The support legs are driven by a drive cylinder located below the furnace wall, with the extension rod end of the drive cylinder connected to one end of the support leg. When the drive cylinder is activated, the extension rod end extends, causing the support leg to rotate around the central pivot, and the upper end of the support leg supports the trolley upwards. When the extension rod retracts, the support leg rotates in the opposite direction, the upper end disengages from the trolley, and the trolley falls, with its wheels contacting the track. In this invention, the drive cylinder is located below the furnace wall and is protected by insulation and air cooling to better ensure its normal operation.

[0027] In this invention, double-layered sand-sealing knives and sand-sealing grooves are provided on both sides of the trolley to achieve a better sealing effect during movement. Specifically, sand-sealing grooves are provided on both the trolley and the furnace sidewall. The sand-sealing groove on the furnace sidewall is a frame-shaped groove facing the opening of the trolley, filled with quartz sand. A sand-sealing knife extends downwards from the upper edge of the groove, reaching into the sand-sealing groove on the trolley. The sand-sealing groove on the trolley opens upwards, is filled with quartz sand, and the sand-sealing knife extends downwards into the sand-sealing groove on the furnace sidewall. The sand-sealing knife is made of heat-resistant stainless steel, with an insertion depth of 50-100mm into the sand-sealing groove, which is 100-200mm deep and filled with 40-70 mesh quartz sand. The tail fiber module is 400mm thick, with a compression design of 50-120mm. An industrial laser rangefinder with a range of 0-10m and an accuracy of ±1mm was selected and installed in a protective box equipped with air purging, located at the furnace tail hole to detect the heat-resistant components at the rear of the trolley. A multi-turn absolute encoder with 17-bit resolution was used and mounted on the variable frequency motor. The controller employed a high-performance PLC with a built-in adaptive error compensation algorithm.

[0028] This invention discloses a control method for the trolley structure of an extra-thick plate trolley-type heating furnace, comprising the following steps: Step 1) The operator clicks the "Automatic Furnace Entry" button on the HMI; Step 2) The PLC checks that the support legs have been retracted and issues a start command, causing the trolley to move into the furnace; Step 3) When the laser rangefinder shows a distance of less than 2m from the end wall, the PLC controls the trolley to slow down; Step 4) When the distance is less than 200mm, the PLC performs precise stopping control and makes fine adjustments based on encoder feedback and stored error compensation values; Step 5) When the laser rangefinder reading reaches the set value, the PLC immediately cuts off the motor power, and the trolley comes to a complete stop; Step 6) After confirming that the trolley has stopped, the PLC controls the support legs to start and complete the support; Step 7) The unloading process is the reverse: the support legs retract first, and then the trolley starts.

[0029] In this invention, after the trolley stops in place in step 5), when the laser rangefinder detects the original position of the trolley, the encoder value is cleared once to eliminate accumulated errors.

[0030] In this invention, the trolley enters the furnace at a low speed, then accelerates, then decelerates, and finally stops. The trolley cannot start too quickly upon entering the furnace, otherwise inertia will cause the steel wheels to slip, increasing the travel error. During the unloading process, before starting the trolley, the start button must be pressed, and the support legs must be lowered to the correct position before the trolley can move. The trolley's movement proceeds at a low speed, then accelerates, then decelerates, and finally stops. The stopping value is set based on the trolley's complete movement to the appropriate position.

[0031] The working process of the trolley structure of the extra-thick plate trolley-type heating furnace of this invention is as follows: The operator clicks the "enter furnace" button on the HMI; after the system checks various safety conditions (such as the furnace door being in position and the hydraulic lifting devices on both sides of the trolley being in position), the motor is started; the trolley initially moves at a low speed, and the control system uses the laser absolute position as the master command and the encoder speed feedback for smooth speed adjustment; when the laser detects that the trolley is 100mm away from the target point, the system automatically switches to low-speed crawling mode; when the target point is reached, the motor stops precisely, and the control system records the encoder deviation value Δ at this stop and stores it in the "entering furnace endpoint" deviation register; the fiber module at the rear of the trolley gently presses against the furnace wall to form a seal; the next time the trolley enters the furnace, the system will automatically subtract the Δ value for pre-compensation when calculating the target position, thereby reaching the same physical position more accurately.

[0032] If the feedback deviation between the laser rangefinder and the encoder exceeds ±20mm, the PLC will automatically alarm and interrupt the automatic furnace feeding process.

[0033] This invention discloses a trolley structure and control method for an extra-thick plate trolley-type heating furnace, based on a programmable logic controller (PLC). It features one-button automatic operation: after the operator selects the "enter furnace" or "exit furnace" command on the human-machine interface, the PLC automatically executes the complete control sequence; dual closed-loop precise positioning control: the inner loop uses motor encoder feedback to control the trolley's running speed and coarse travel; the outer loop uses the absolute distance feedback from a laser rangefinder as the core control parameter, with preset safe deceleration distance and precise stopping distance within the PLC. Adaptive error compensation: After each trolley completes its furnace entry action and comes to a complete stop, the PLC records the actual distance value displayed by the laser rangefinder and the cumulative pulse value of the encoder. The deviation between the theoretical value and the actual pulse value of the encoder is stored as a system error compensation value. This compensation value is superimposed during the next furnace entry control for prediction, and finally, the laser rangefinder performs precise calibration. Safety interlocking and protection: The measurement value of the laser rangefinder is used as a hard limit signal. When the measurement value is less than the preset safety limit distance, the PLC immediately issues an emergency stop command. The "retract" signal of the support legs is interlocked with the "allow to move" signal of the trolley, and the "start" signal is interlocked with the "furnace entry in place" signal of the trolley.

[0034] This invention employs dual-loop precise positioning control. The encoder feedback value serves as the inner-loop control parameter, controlling the trolley's speed and coarse travel distance to achieve speed closed-loop and coarse positioning. The absolute distance value from the laser rangefinder is used as the outer-loop control parameter for precise trolley positioning control. The encoder zero-position value is corrected after the trolley enters its designated position to eliminate accumulated encoder error. After the trolley enters the furnace, the value measured by the laser rangefinder is the trolley's position value, which can be used as the trolley's zero-position value. As the trolley enters, the encoder value gradually decreases, stopping when it reaches the zero position measured by the laser rangefinder, and the encoder's accumulated error value is reset to zero. When the trolley exits, the encoder value increases to measure the trolley's displacement data. System error compensation can also be implemented simultaneously. This eliminates accumulated error and, through system error compensation during each reciprocating motion of the trolley, self-learns to reduce error, allowing for more accurate calculation of the trolley's travel distance data via the encoder.

[0035] The present invention discloses a control method for the trolley structure of an extra-thick plate trolley-type heating furnace, the method comprising the following steps: Step 1: Dual Sensor Data Acquisition The absolute distance between the tail of the trolley and the furnace end wall is collected in real time by a laser rangefinder sensor mounted on the furnace end wall, while the relative displacement of the trolley is collected by an encoder mounted on the drive motor shaft. The laser rangefinder sensor has no cumulative error and can provide an absolute position reference; the encoder has a fast response speed and is suitable for process control.

[0036] Step 2: Dual Closed-Loop Precision Positioning Control The encoder feedback value is used as the inner-loop control parameter to control the trolley's speed and coarse travel, achieving speed closed-loop control and coarse positioning. The absolute distance value from the laser rangefinder is used as the outer-loop control parameter to perform precise positioning control of the trolley. After the trolley enters its designated position, the encoder zero-position value is corrected to eliminate accumulated encoder errors. When the trolley approaches the target position, the control system switches to or merges the laser rangefinder data to eliminate accumulated encoder errors, forming a dual-closed-loop control architecture of "coarse positioning + fine positioning".

[0037] Step 3: Adaptive Error Compensation After each trolley completes its furnace entry and comes to a complete stop, the actual distance reached by the laser rangefinder is recorded, and the cumulative pulse value of the encoder at that actual distance is read. The control system calculates the deviation between this cumulative pulse value and the theoretical pulse value corresponding to the preset standard distance, and stores this deviation as a system error compensation value. This compensation value reflects the system error under the current operating conditions (such as wheel wear, track condition, etc.).

[0038] Step 4: Apply the compensation value to the next control cycle. During the next furnace feed control, the control system pre-compensates the encoder's positioning control based on the stored system error compensation value. Specifically, it begins deceleration or stopping preparation when the encoder's accumulated pulses reach the theoretical value minus the compensation value, and then performs precise calibration using a laser rangefinder during the final positioning stage. In this way, the system can adaptively eliminate accumulated errors caused by factors such as wheel slippage and track wear.

[0039] The adaptive error compensation method includes the following detailed steps: Step A: Initialization. After the trolley runs for the first time or the control system is reset, the stored error compensation value ΔS is initialized to 0. Step B: Standard positioning learning. After the trolley completes automatic furnace entry and stops stably for the first time, the control system records the actual distance value L-actual of the laser rangefinder at this time, and reads the cumulative pulse count P-actual of the encoder at the same time; according to the preset standard positioning distance L-target, the theoretical pulse count that the encoder should reach is calculated as P-theory = k×L_target, where k is the encoder pulse equivalent (mm / pulse). Step C: Deviation calculation and storage. Calculate the system deviation Δ = P - actual - P - theory for this run, and store the deviation value Δ in non-volatile memory as the error compensation value for the next control. Step D: Compensation value filtering. When the cumulative number of runs reaches N (N≥3), the control system adopts a sliding window filtering algorithm to take the weighted average of the most recent M (M≥3) effective deviation values ​​as the current compensation value to eliminate random measurement errors. Step E: Compensation application. During the next automatic furnace feeding, the control system superimposes the compensation value in the encoder positioning control. That is, when the encoder's cumulative pulse reaches P-target = P-theory - Δ-comp, the control system starts to execute the deceleration and stop procedure. Step F: Compensation value update. After each furnace feed, the system recalculates the deviation and iteratively updates the stored compensation value. The update formula is Δnew = α×Δcurrent + (1-α) ×Δhistory, where α is the weighting coefficient (0.5-0.8), realizing adaptive tracking of slowly changing system errors.

[0040] Furthermore, the method also includes a safety interlock protection step: the absolute distance value collected by the laser rangefinder is used as a hard limit signal. When the absolute distance value is less than the preset safety limit distance, the control system immediately issues an emergency stop command, which can prevent the trolley from hitting the furnace end wall regardless of the encoder status.

[0041] Furthermore, the method also includes a support leg interlocking control step: interlocking the retracted state of the liftable support leg located at the bottom of the trolley with the trolley travel permission signal, so that the trolley is only allowed to move when the support leg is fully retracted and locked; interlocking the start-up support state of the support leg with the trolley entering the furnace position signal, so that the support leg is only allowed to support when the trolley enters the furnace position and stops, ensuring operational safety.

[0042] Furthermore, the method also includes a one-click automatic operation step: in response to a single "into furnace" or "outto furnace" command input through the operation interface, the programmable logic controller automatically executes a complete control sequence, including motor start, speed adjustment, precise positioning, stopping, and support leg lifting operations, without the need for intermediate manual intervention.

[0043] In one embodiment of the present invention, the trolley structure of an extra-thick plate trolley-type heating furnace is as follows: Figure 1 As shown, the car body frame is welded from Q345 heat-resistant steel plates into a box-shaped beam. An internal transverse partition is installed every 800mm, and three longitudinal stiffening plates are arranged to form a robust grid-like support structure. Sand sealing blades 2, made of 310S heat-resistant stainless steel, are fixedly installed along the sides of the trolley and extend downwards. These blades are inserted into sand sealing grooves 8 with a depth of 150mm, and the grooves are filled with 40-70 mesh quartz sand. A row of zirconium-containing ceramic fiber modules is bolted to the rear end of the trolley to form an end sealing block 3, which has a thickness of 300mm after compression.

[0044] In this embodiment of the invention, the laser rangefinder 6 is installed at the geometric center of the furnace end wall 7, and its measuring optical axis coincides with the center normal of the fiber module sealing block 3 at the tail end of the trolley, ensuring that the measured absolute distance directly corresponds to the compression amount of the fiber sealing block. This setup enables visual monitoring of the sealing status. When the measured value deviates from the preset compression range of 80-120mm, the control system determines that the seal has failed and issues an alarm.

[0045] In this embodiment of the invention, the walking mechanism uses multiple solid alloy cast steel wheels 4 with a diameter of 800mm, which are connected to the drive shaft via expansion sleeves. It features a bearingless design and connects the front and rear steel wheels together via connecting chain plates. These wheels are positioned within the gap between the double rails at the bottom of the vehicle and the corresponding double rails on the ground. Each of the four corners of the vehicle's bottom is equipped with a controllable support leg 5 driven by a hydraulic cylinder.

[0046] In this embodiment of the invention, the control system uses a Siemens S7-1500 series PLC as the main controller, the motor drive uses a frequency converter, and the motor shaft is equipped with an incremental encoder.

[0047] After the operator clicks the "Automatic Furnace Feed" button on the human-machine interface, the PLC executes the following control sequence: The PLC checks that the liftable support leg 5 has been fully retracted, issues a start command, and the trolley gradually accelerates towards the furnace at a speed of 3m / min → 10m / min to avoid inertia causing the billet on the trolley to sway and to prevent the steel wheels from slipping, which could increase the error in the stroke calculation. When the laser rangefinder 6 shows a distance of less than 2m from the end wall, the PLC controls the trolley to reduce its speed to a low 3m / min. When the laser rangefinder 6 shows a distance of less than 200mm from the end wall, the PLC enters the precise stop control stage. At this time, the PLC makes a comprehensive judgment based on encoder feedback and stored error compensation values, and controls the trolley to decelerate to a stop. When the laser rangefinder 6 reading reaches the set range of 100±5mm, the PLC immediately cuts off the motor power, the transmission mechanism brake is energized and locked, and the trolley comes to a stable stop. After confirming that the trolley is stopped, the PLC controls the four hydraulic support legs 5 to simultaneously lift the trolley upwards until the pressure sensor shows that the set value has been reached, completing the support. The unloading process is the reverse. The PLC first controls the support leg 5 to retract and lock. After confirmation, the motor is started, and the trolley starts at low speed, exits the furnace at high speed, and stops at low speed along a production trajectory. If the feedback deviation between the laser rangefinder and the encoder exceeds ±20mm, the PLC automatically alarms and interrupts the automatic furnace feeding process. The trolley is equipped with a braking mechanism to prevent gaps from forming when the fiber module at the rear of the trolley contacts and presses against the fiber module in the buffered movable box at the bottom of the end wall after stopping, thus avoiding affecting the sealing effect.

[0048] To address encoder cumulative error and automation issues, this invention employs a multi-loop closed-loop control strategy combining absolute positioning, relative positioning, and adaptive learning compensation. The trolley is zeroed at its initial position. Compensation is applied adaptively only for the error during the single round trip from furnace exit to furnace entry, preventing multiple external interferences from hindering the achievement of the adaptive learning compensation target value.

[0049] In this invention, a laser rangefinder serves as the absolute position reference. A high-precision, dustproof, and high-temperature-resistant laser rangefinder is installed on the end wall of the furnace body, with its laser beam pointing towards a reflective target positioned on the side of the trolley. This sensor directly and continuously measures the absolute linear displacement of the trolley relative to the furnace body, and the measured value is unaffected by wheel slippage or wear. An encoder provides relative speed and displacement feedback. A high-resolution absolute encoder is installed on the shaft end of the trolley drive motor to monitor the motor's rotational speed and the theoretical number of wheel rotations in real time, providing a high-frequency relative displacement signal. The intelligent controller integrates the above sensor signals and runs the core control algorithm.

[0050] This invention employs a dual-loop collaborative control method and error compensation mechanism. The main control loop uses the absolute position fed back by the laser rangefinder as the primary control target. The controller compares the current absolute position of the trolley with the preset target position (e.g., "furnace entry point" or "furnace exit point") and generates speed commands. The secondary control loop, forming an inner loop with real-time speed-displacement signals provided by the encoder, is used to achieve drive start-up, acceleration, smooth speed adjustment, and disturbance suppression. The adaptive error compensation algorithm is the core intelligence of this system. Each time the trolley completes a full entry / exit cycle and stops at the target point, the system records the deviation between the encoder reading and the theoretical encoder value of the absolute position measured by the laser sensor. This deviation value is stored and associated with the target point. When the trolley moves towards the same target point again, the control system incorporates the stored deviation value as compensation into the control command at the end of the stroke, thereby pre-correcting systematic errors caused by local track unevenness, wheel diameter differences, etc. This process iterates continuously, allowing the positioning accuracy to be continuously optimized with the increase of the number of runs.

[0051] Based on a highly reliable positioning system, the operator only needs to click the "into furnace" or "outto furnace" button on the HMI, and the system will automatically complete all actions, including starting, speed adjustment, precise positioning, stopping, and sealing contact. The system is equipped with multiple safety interlocks, such as laser sensor signal loss alarm, emergency braking for position deviation, and anti-collision buffer zone (automatic speed reduction at a certain distance from the end wall), completely eliminating the risk of human error.

[0052] This embodiment describes in detail the execution process of the adaptive error compensation method: Step A: Initialization. After the system is put into operation for the first time or the PLC is reset, initialize the error compensation value Δ in the non-volatile memory to 0.

[0053] Step B: Standard positioning learning. After the trolley automatically enters the furnace and stops stably for the first time, the laser rangefinder 6 displays the actual distance value L-actual = 100mm. At this time, the cumulative encoder pulse count P-actual = 102500 is read. Given that the encoder pulse equivalent k = 0.01mm / pulse, the theoretical pulse count corresponding to the standard positioning distance L-target = 100mm is P-theory = 100 / 0.01 = 10000.

[0054] Step C: Calculate the deviation Δ = 102500 - 10000 = 2500 pulses, which is equivalent to a 25mm stroke deviation. Store this deviation value in memory.

[0055] Step D: Compensation value filtering. After running 5 times consecutively, record the 5 deviation values ​​as follows: 2500, 2480, 2520, 2510, and 2490. Remove the maximum value of 2520 and the minimum value of 2480, and take the average of the remaining three values ​​to get (2500+2510+2490) / 3=2500 pulses.

[0056] Step E: Compensation Application. During the 6th automatic furnace feeding, the PLC superimposes compensation values ​​in the encoder positioning control. When the encoder's accumulated pulses reach P-target = 10000 - 2500 = 7500 pulses, the PLC starts executing the deceleration and stopping procedure, and finally, the laser rangefinder precisely calibrates the stopping position.

[0057] Step F: Iterative update of the compensation value. After the 6th run, the encoder's cumulative pulses at the actual arrival point are 102480. Calculate the deviation Δcurrent = 102480 - 10000 = 2480 pulses. Use exponentially weighted moving average update: take α = 0.7, Δnew = 0.7 × 2480 + 0.3 × 2500 = 2486 pulses, and store it in memory as the compensation value for the next control.

[0058] After 720 hours of system operation, the compensation value is automatically reset to zero, and standard positioning learning is re-executed to adapt to nonlinear drift that may occur during long-term operation. If, during a certain operation, the deviation between the laser ranging value and the encoder calculated value exceeds 5000 pulses (equivalent to 50mm of travel), the system determines it as abnormal operation (such as wheel slippage), this deviation will not be included in the compensation value update, and an alarm will be issued.

[0059] In this application, the adaptive error compensation method also includes a time validity judgment of the compensation value: when the continuous running time of the trolley exceeds a preset threshold (e.g., 72 hours) or the ambient temperature changes by more than ±50℃, the system automatically sets the stored compensation value to zero and relearns. In addition, the system uses a sliding window filtering algorithm to perform a weighted average of the most recent N (N≥5) compensation values ​​to eliminate random errors.

[0060] This invention employs a three-level safety interlock protection architecture. Level 1 protection (software limit): The PLC presets a deceleration point of 200mm and a stopping point of 100mm. When the laser ranging value is less than 200mm, the PLC automatically reduces the trolley speed to 3m / min; when it is less than 100mm, the PLC issues a stop command. Level 2 protection (redundant comparison): The PLC compares the encoder pulse-calculated displacement with the laser ranging value in real time. When the difference exceeds a preset threshold (equivalent to a 50mm travel distance), the system determines an anomaly and issues an alarm, prompting the operator to check. Level 3 protection (hardware limit): The 4-20mA analog signal output from the laser rangefinder is simultaneously connected to the PLC's analog input module and a safety relay. When the distance value corresponding to the analog signal is less than 50mm, the safety relay directly cuts off the power supply to the motor's main circuit contactor coil, achieving a hardware-level emergency stop without PLC logic judgment.

[0061] In existing technologies, end fiber sealing and trolley positioning control are treated as two independent technical problems to be solved separately. However, when the trolley positioning error exceeds ±10mm, an uneven gap will occur between the fiber sealing block and the furnace wall end face. High-temperature flue gas will be ejected at high speed from the gap, causing not only heat loss but also direct erosion of the fiber sealing block edge, leading to seal failure. Therefore, there is a strong coupling relationship between sealing effect and positioning accuracy. Only by improving the positioning accuracy to within ±5mm can the expected lifespan of the end flexible seal be achieved. The encoder-based single positioning method cannot meet this coupling requirement due to the cumulative error (which can reach over ±20mm). In this invention, through dual closed-loop control of laser absolute positioning and encoder relative positioning, the trolley positioning accuracy is stably controlled within ±5mm for the first time, thereby truly realizing the technical effect of the end flexible seal.

[0062] Testing revealed that the trolley-type heating furnace employing the technical solution of this application maintained a stable positioning error within ±3.2mm after 30 days of continuous operation, as indicated by the laser rangefinder. In contrast, the control group, which used only encoder positioning, exhibited an error of ±18mm after only 7 days of operation. Inspection of the end fiber sealing blocks after 12 months of operation showed no obvious signs of high-temperature ablation, while the control group showed edge carbonization and pulverization after only 4 months of operation.

[0063] This invention discloses a trolley structure and control method for an extra-thick plate trolley-type heating furnace, primarily applied to trolleys with thicker plates. The technical features are not simply superimposed, but rather work synergistically to produce effects exceeding the sum of the individual effects of each feature. In this invention, positioning and sealing are coordinated, and dual closed-loop control using laser and encoder improves the stopping accuracy to ±5mm, ensuring accurate contact between the end fiber sealing block and the furnace wall, preventing high-temperature flue gas from burning the seals and extending the seal life from the conventional 3-6 months to 12-18 months. The combination of side sand seals and end seals forms a three-dimensional seal, which, combined with high-precision positioning to eliminate gaps, reduces the furnace gas leakage temperature from 300-500℃ to below 80℃, reducing heat loss by more than 15%. Laser ranging values ​​are used simultaneously for positioning control and safety hard limit switches, forming a redundant protection architecture with one sensor serving two purposes. This simplifies system configuration and provides more reliable safety protection than traditional independent limit switches. An adaptive error compensation mechanism automatically learns gradually changing errors such as wheel wear and track settlement, eliminating the need for manual calibration of positioning parameters during continuous operation and significantly reducing maintenance workload.

[0064] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in the details for the sake of brevity.

[0065] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

[0066] The present invention has been described above by way of example with reference to the accompanying drawings. However, the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention or any direct application to other situations shall fall within the protection scope of the present invention.

Claims

1. A trolley structure for an extra-thick plate trolley-type heating furnace, comprising a trolley body, characterized in that: The trolley structure is equipped with a composite sealing system, which includes sand sealing blades located on both sides of the trolley and a sealing block located at the rear of the trolley. A traveling mechanism is located below the trolley body. Support legs are located at the bottom of the furnace to contact and support the trolley after it enters the furnace. The trolley structure is also equipped with a detection system, which includes a laser rangefinder sensor mounted on the furnace end wall and an encoder mounted on the drive motor shaft. The control system is electrically connected to the laser rangefinder sensor, the encoder, the traveling mechanism, and the support legs.

2. The trolley structure of the extra-thick plate trolley-type heating furnace according to claim 1, characterized in that: The trolley body adopts a grid-like frame structure, which is composed of crisscrossing reinforcing ribs; the traveling mechanism is a steel wheel, which is directly fixed to the drive shaft by expansion sleeves or key connections.

3. The trolley structure of the extra-thick plate trolley-type heating furnace according to claim 1, characterized in that: The laser rangefinder is installed at the geometric center of the furnace end wall, and its measuring optical axis coincides with the center normal of the fiber module sealing block at the tail end of the trolley.

4. The trolley structure of the extra-thick plate trolley-type heating furnace according to claim 1, characterized in that: The support legs are provided at the four corners near the trolley; the support legs are L-shaped, and the middle of the support legs are supported and connected by a pivot. The support legs are driven by a drive cylinder, and the telescopic rod end of the drive cylinder is connected to one end of the support leg.

5. A method for controlling the structure of a trolley-type heating furnace with extra-thick plates, characterized in that, Includes the following steps: Step 1) The operator clicks the "Automatic Furnace Entry" button on the HMI; Step 2) The PLC checks that the support legs have retracted, issues a start command, and the trolley moves into the furnace; Step 3) When the laser rangefinder shows a distance of less than 2m from the end wall, the PLC controls the trolley to slow down; Step 4) When the distance is less than 200mm, the PLC performs precise stopping control and makes fine adjustments based on encoder feedback and stored error compensation values; Step 5) When the laser rangefinder reading reaches the set value, the PLC immediately cuts off the motor power, and the trolley comes to a complete stop; Step 6) After confirming that the trolley has stopped, the PLC controls the support legs to start and complete the support; Step 7) The furnace unloading process is the reverse: the support legs retract first, and then the trolley starts.

6. The method for controlling the trolley structure of an extra-thick plate trolley-type heating furnace according to claim 5, characterized in that: The absolute distance between the tail of the trolley and the end wall of the furnace body is collected in real time by a laser rangefinder sensor installed on the end wall of the furnace body, while the relative displacement value of the trolley is collected by an encoder installed on the end of the drive motor shaft.

7. The method for controlling the trolley structure of an extra-thick plate trolley-type heating furnace according to claim 6, characterized in that: The encoder feedback value is used as the inner loop control parameter to control the trolley's running speed and coarse travel; the laser rangefinder sensor's absolute distance value is used as the outer loop control parameter to perform precise positioning control of the trolley.

8. The method for controlling the trolley structure of an extra-thick plate trolley-type heating furnace according to claim 7, characterized in that: After each trolley completes its furnace entry action and comes to a stop, the actual positioning distance value of the laser rangefinder is recorded. At the same time, the cumulative pulse value of the encoder at the actual positioning distance value is read, and the deviation between the cumulative pulse value and the theoretical pulse value corresponding to the preset standard positioning distance is calculated. This deviation is stored as a system error compensation value. During the next furnace feeding control, the encoder positioning control is pre-compensated based on the system error compensation value, and precise calibration is performed by the laser rangefinder during the final positioning stage.

9. The method for controlling the trolley structure of an extra-thick plate trolley-type heating furnace according to claim 5, characterized in that: The absolute distance value collected by the laser rangefinder is used as a hard limit signal. When the absolute distance value is less than the preset safety limit distance, the control system immediately issues an emergency stop command and cuts off the motor power.

10. The method for controlling the trolley structure of an extra-thick plate trolley-type heating furnace according to claim 5, characterized in that: The retracted state of the support legs located at the bottom of the trolley is interlocked with the trolley travel permission signal. The trolley is only allowed to move when the support legs are retracted and locked. The start-up support state of the support legs is interlocked with the trolley entering the furnace position signal. The support legs are only allowed to support when the trolley enters the furnace position and stops.

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