Plate conveying line system based on bidirectional control and priority management and control method

Abstract

This invention discloses a plate conveyor system and control method based on bidirectional control and priority management, including a motor-driven plate conveyor line and a control box; a first photoelectric detection switch, a mechanical lifting stop, a foot control switch, and a plate detection switch are installed on the trolley side; a laser detection switch, a vehicle stopper, and a second photoelectric detection switch are installed on the forklift side; the system controller is electrically connected to the laser detection switch, the foot control switch, the plate detection switch, the first photoelectric detection switch, and the second photoelectric detection switch; the first control output terminal of the system controller is electrically connected to the motor; the second control output terminal of the system controller is electrically connected to the push rod motor of the mechanical lifting stop. This invention enables a single conveyor line to handle bidirectional flow of fully loaded and empty pallets simultaneously, while introducing an unloading priority principle, automatically shielding the loading request at the other end during the unloading process, avoiding control signal competition and conflict, and improving equipment utilization and space efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field of automated transportation, and in particular to a plate conveyor system and control method based on bidirectional control and priority management. Background Technology

[0002] Plate conveyor lines are widely used in warehousing logistics and production workshops for palletized material handling. Traditional plate conveyor lines are mostly unidirectional, with limited functionality, and cannot flexibly adapt to complex scenarios with both full-load pallet input and empty pallet output, as well as reverse logistics needs. In existing technologies, for applications requiring bidirectional flow, two independent conveyor lines or complex mechanical transfer mechanisms are typically required, but this approach results in high equipment costs and large footprints. Furthermore, when both ends of the plate conveyor line require simultaneous operation, signal conflicts or misoperations can easily lead to system malfunctions, equipment interference, or even material damage, posing safety hazards.

[0003] Therefore, the problem that this invention aims to solve is to design a control scheme that is low-cost, compact in layout, and capable of safely and efficiently handling the bidirectional automated transfer of pallets. Summary of the Invention

[0004] In response to the aforementioned problems, this invention proposes a plate conveyor system and control method based on bidirectional control and priority management. The aim is to overcome the shortcomings of the prior art and provide a plate conveyor system and control method that is compact in layout, intelligent in control, safe and reliable. It can realize bidirectional automated flow of full-loaded pallets and empty pallets, and avoid control conflicts through priority management.

[0005] The specific technical solution of the present invention is as follows: A plate conveyor system based on bidirectional control and priority management includes a motor-driven plate conveyor and a control box equipped with a system controller. The two ends of the plate conveyor line are the forklift side and the trolley side, respectively. The trolley side is equipped with a first photoelectric detection switch, a mechanical lifting stop, a foot control switch, and a trolley detection switch; the forklift side is equipped with a laser detection switch, a vehicle stop device, and a second photoelectric detection switch. The signal input terminal of the system controller is electrically connected to the laser detection switch, foot control switch, trolley detection switch, first photoelectric detection switch and second photoelectric detection switch; The first control output terminal of the system controller is electrically connected to the motor, and is used to control the motor to start and make the plate conveyor line run towards the trolley side according to the trigger signals of the laser detection switch and the second photoelectric detection switch; The second control output terminal of the system controller is electrically connected to the push rod motor of the mechanical lifting stop and the motor. According to the joint trigger signal of the trolley detection switch and the foot control switch, and when the first photoelectric detection switch detects that the tray is located at the unloading station, the mechanical lifting stop is controlled to descend and the motor is controlled to start so that the plate conveyor line runs a preset distance towards the trolley side.

[0006] Preferably, the mechanical lifting stop further includes a stop arm driven by the push rod motor and a position detection mechanism for detecting the lifting and lowering state of the stop arm, wherein the signal output terminal of the position detection mechanism is electrically connected to the signal input terminal of the system controller.

[0007] More preferably, the position detection mechanism includes an up-to-position limit switch and a down-to-position limit switch.

[0008] Preferably, the laser detection switch is equipped with a laser reflector baffle, which is positioned opposite to the laser detection switch on the forklift side to form a through-beam detection light curtain.

[0009] Preferably, the forklift side is provided with a fixed stop that is fixedly installed at the end of the plate conveyor frame, and the fixed stop is an L-shaped steel structure.

[0010] Preferably, the first photoelectric detection switch and the second photoelectric detection switch are through-beam photoelectric switches.

[0011] Preferably, the forklift side and / or trolley side are further provided with limit switches for detecting pallet over-extension. The signal output terminal of the limit switch is electrically connected to the system controller and is used to trigger an emergency stop of the plate conveyor line when pallet over-extension is detected.

[0012] Preferably, the power supply circuit of the motor is equipped with a frequency converter, the control terminal of the frequency converter is electrically connected to the first control output terminal of the system controller, and the power output terminal of the frequency converter is electrically connected to the motor.

[0013] Preferably, the control box is equipped with an operation indicator light that is electrically connected to the system controller.

[0014] Another object of the present invention is to provide a plate conveyor control method based on bidirectional control and priority management. The plate conveyor system based on bidirectional control and priority management includes the following steps: S1: Perform full pallet loading When the laser detection switch and the second photoelectric detection switch detect that the target is in place, the system controller starts the first delay. After the first delay ends, the system controller controls the plate conveyor line to run a first preset distance toward the trolley side and then stops. S2: Perform full-load tray unloading When the trolley detection switch detects that the trolley is in place and the foot control switch is triggered to lower, if the first photoelectric detection switch simultaneously detects that the tray is located at the unloading station, the system controller executes an unloading operation. The unloading operation steps include: S201: Control the mechanical lifting stop to descend; S202: Start the second delay. After the second delay ends, control the plate conveyor line to run a second preset distance toward the trolley side so that the operator can transfer the pallet to the trolley. When the foot pedal control switch is triggered to rise, it controls the mechanical lifting stop to rise. During the period from the moment the foot pedal control switch is triggered to lower the device until the mechanical lifting stop is raised and reset, the system controller disables the initiation of step S1. S3: Perform empty pallet transfer, the steps of which include: S301: Perform empty pallet loading When the system is in the state that allows empty pallet loading, and the second photoelectric detection switch detects that the empty pallet is in place, and the foot control switch is triggered to descend, the system controller controls the mechanical lifting stop to descend, starts the third delay, and after the third delay ends, controls the plate conveyor to run a third preset distance toward the forklift side, and then controls the mechanical lifting stop to rise. S302: Perform empty tray unloading When the second photoelectric detection switch detects that the forklift is in place, the system controller starts the fourth delay. After the fourth delay ends, the system controller controls the plate conveyor to run a fourth preset distance toward the forklift and then stops. During the execution of step S302, the system controller disables the initiation of step S301.

[0015] The beneficial effects of this invention are: 1. Two-way flow, dual-purpose machine: Through control logic definition, a single conveyor line can simultaneously handle the two-way flow of full-loaded pallets and empty pallets, greatly improving equipment utilization and site space efficiency.

[0016] 2. Priority management and intelligent conflict prevention: The "unload priority" principle is introduced. When the system executes the uninstallation process, it automatically blocks the loading request from the other end, which fundamentally avoids the competition and conflict of control signals and ensures the orderliness and security of the operation process.

[0017] 3. High safety and reliability: It employs multiple safety measures, including fixed and lifting stops, photoelectric detection, foot switch confirmation, and limit overload protection, forming a complete safety protection system that effectively prevents accidents such as pallet drops and equipment interference.

[0018] 4. Excellent human-machine collaboration: The foot switch and delayed start design provide operators with ample operation time, achieving seamless integration between automated equipment and manual operation, balancing automation efficiency and operational flexibility. Attached Figure Description

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless specifically indicated, these drawings are intended only to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0020] Figure 1 This is a planar schematic diagram of the present invention; Figure 2 This is a side view schematic diagram of the present invention; Figure 3 This is a partial three-dimensional schematic diagram of the present invention; In the picture: 1-Plate conveyor line; 2-Control box; 3-Run indicator light; 4-Motor; 5-First photoelectric detection switch; 6-Mechanical lifting stop; 7-Foot control switch; 8-Trolley detection switch; 9-Vehicle stopper; 10-Laser detection switch; 11-Laser reflector baffle. Detailed Implementation

[0021] First, it should be noted that the specific structure, features, and advantages of the present invention will be described in detail below by way of examples. However, all descriptions are for illustrative purposes only and should not be construed as limiting the present invention in any way. Furthermore, any single technical feature described or implied in the embodiments mentioned herein, or any single technical feature shown or implied in the accompanying drawings, can still be arbitrarily combined or deleted among these technical features to obtain more other embodiments of the present invention that may not be directly mentioned herein. Additionally, for the sake of simplifying the drawings, the same or similar technical features may be indicated only in one place in the same drawing.

[0022] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] The following is in conjunction with the appendix Figure 1 - Appendix Figure 2 This invention will be described in detail.

[0024] Example 1:

[0025] A plate conveyor system based on bidirectional control and priority management includes a plate conveyor 1 driven by a motor 4 and a control box 2 equipped with a system controller. The two ends of the plate conveyor line 1 are the forklift side and the trolley side, respectively. The trolley side is equipped with a first photoelectric detection switch 5, a mechanical lifting stop 6, a foot control switch 7, and a trolley detection switch 8; the forklift side is equipped with a laser detection switch 10, a vehicle stopper 9, and a second photoelectric detection switch. The signal input terminal of the system controller is electrically connected to the laser detection switch 10, the foot control switch 7, the trolley detection switch 8, the first photoelectric detection switch 5, and the second photoelectric detection switch; The first control output terminal of the system controller is electrically connected to the motor 4, and is used to control the motor 4 to start and make the plate conveyor line 1 run towards the trolley side according to the trigger signals of the laser detection switch 10 and the second photoelectric detection switch; The second control output terminal of the system controller is electrically connected to the push rod motor of the mechanical lifting stop 6 and the motor 4. According to the joint trigger signal of the trolley detection switch 8 and the foot control switch 7, and when the first photoelectric detection switch (5) detects that the tray is located at the unloading station, the mechanical lifting stop 6 is controlled to descend and the motor 4 is controlled to start so that the plate conveyor line 1 runs a preset distance towards the trolley side.

[0026] Working principle: This invention is mainly used for the automated transfer of fully loaded and empty pallets between forklifts and trolleys. The pallet conveyor line 1 can operate in two directions, one on the forklift side and the other on the trolley side, to complete the loading and unloading processes respectively. The system has clearly defined operation priorities to ensure that conflicting processes are not initiated due to accidental triggering during critical processes, thus guaranteeing operational safety and smooth process flow.

[0027] This system consists of a mechanical component, a detection and sensing component, and a control component, among which: Mechanical parts: The plate conveyor line 1 is used for material carrying and transmission. It adopts a chain plate structure and is driven by a three-phase asynchronous motor 4 through a reducer. It is preferable to use a frequency converter for control to achieve smooth start and stop. The power of motor 4 is selected according to the conveying load.

[0028] The mechanical lifting stop 6 is a key safety device, installed on the side of the trolley and driven by a push rod motor. It is used to block or release pallets on the side of the trolley. The push rod motor is DC 24V, with a thrust of 500kg and a stroke of 200mm.

[0029] Detection and sensing components: The forklift side is equipped with: Vehicle stopper 9 is used to prevent vehicles from accidentally entering.

[0030] The laser detection switch 10 and the laser reflector baffle 11 are used to detect whether a fully loaded pallet has been placed in place by a forklift.

[0031] The second photoelectric detection switch is used to detect the forklift or the pallet on the forklift being in place to trigger the loading process.

[0032] Limit switches are used to detect whether the pallet has been delivered to the correct position.

[0033] The trolley side is equipped with: The trolley detection switch 8 is used to detect whether the trolley is in position.

[0034] Foot control switch 7 is installed on the side of the trolley in a position easily accessible to the operator. It is a dual-pedal type, with one pedal labeled "Lower" and the other labeled "Up," and contains a self-resetting normally open contact. Foot control switch 7 is activated by the operator's foot to issue unloading / loading commands and is crucial for safety interlocking.

[0035] The first photoelectric detection switch 5 is used to assist the detection trolley.

[0036] The position detection mechanism is used to detect whether the mechanical lifting stop is raised or lowered in place.

[0037] The control section is equipped with: Control box 2 contains a system controller, which in this embodiment is a programmable logic controller (PLC). The core logic of the system controller is to dynamically define the material flow direction and implement the unloading priority principle.

[0038] All the signals from the aforementioned detection and sensing components are connected to the input point of the system controller, while the output point controls the push rod motor of motor 4 and mechanical lifting stop 6.

[0039] The running indicator light 3 displays the system's running status to the user.

[0040] The frequency converter is used to control the speed of motor 4.

[0041] Furthermore, in the embodiments, the mechanical lifting stop 6 may also include a stop arm driven by the push rod motor and a position detection mechanism for detecting the lifting and lowering state of the stop arm, wherein the signal output terminal of the position detection mechanism is electrically connected to the signal input terminal of the system controller.

[0042] In this embodiment, the stop arm is made of steel. Furthermore, in some embodiments, the position detection mechanism may include an up-to-position limit switch and a down-to-position limit switch.

[0043] In this embodiment, the upper limit switch and the lower limit switch are magnetic limit switches.

[0044] Furthermore, in the embodiments, the laser detection switch 10 may be equipped with a laser reflection baffle 11, which is disposed opposite to the laser detection switch 10 on the forklift side to form a through-beam detection light curtain.

[0045] Furthermore, in the embodiments, it can also be considered that the forklift side is provided with a fixed stop that is fixedly installed at the end of the frame of the plate conveyor line 1, and the fixed stop is an L-shaped steel structure.

[0046] In this embodiment, a fixed stop is installed at the end of the forklift side as the final physical limit. The fixed stop adopts an L-shaped steel structure and is firmly installed at the end of the conveyor frame with high-strength bolts. Two stops are installed, and their height is higher than the bottom of the pallet for final mechanical protection.

[0047] Furthermore, in the embodiments, the first photoelectric detection switch 5 and the second photoelectric detection switch may be through-beam photoelectric switches.

[0048] In this embodiment, the first photoelectric detection switch 5 on the trolley side and the second photoelectric detection switch on the forklift side are the same type of photoelectric element, and both have a detection distance of 5 meters. The first photoelectric detection switch 5 is used to detect the trolley's positioning to trigger the unloading process, and the second photoelectric detection switch is used to detect the forklift or the pallet on the forklift's positioning to trigger the loading process.

[0049] Furthermore, in the embodiments, the forklift side and / or trolley side may also be provided with a limit switch for detecting pallet over-extension. The signal output terminal of the limit switch is electrically connected to the system controller to trigger an emergency stop of the plate conveyor line 1 when pallet over-extension is detected.

[0050] In this embodiment, limit switches are installed in the over-displacement protection areas on both the trolley and forklift sides. Heavy-duty lever roller type limit switches are used as hard-wired safety protection against excessive pallet displacement. During the process, if a limit switch is triggered, the system controller immediately forces the motor 4 to stop, triggering an emergency stop for the plate conveyor line 1.

[0051] Furthermore, in the embodiments, a frequency converter can be provided in the power supply circuit of the motor 4, the control terminal of the frequency converter is electrically connected to the first control output terminal of the system controller, and the power output terminal of the frequency converter is electrically connected to the motor 4.

[0052] Furthermore, in the embodiments, the control box 2 may be equipped with an operation indicator light 3 that is electrically connected to the system controller.

[0053] Example 2:

[0054] A control method for a plate conveyor line based on bidirectional control and priority management, applying the aforementioned plate conveyor line system based on bidirectional control and priority management, includes the following steps: S1: Perform full pallet loading When the laser detection switch 10 and the second photoelectric detection switch detect that the target is in place, the system controller starts the first delay. After the first delay ends, the system controller controls the plate conveyor line 1 to run a first preset distance toward the trolley side and then stops. S2: Perform full-load tray unloading When the trolley detection switch 8 detects that the trolley is in place and the foot control switch 7 is triggered to descend, if the first photoelectric detection switch 5 simultaneously detects that the tray is located at the unloading station, the system controller executes an unloading operation. The unloading operation steps include: S201: Control the mechanical lifting stop 6 to descend; S202: Start the second delay. After the second delay ends, control the plate conveyor line 1 to run a second preset distance toward the trolley side so that the operator can transfer the pallet to the trolley. When the foot pedal control switch 7 is triggered to rise, it controls the mechanical lifting stop 6 to rise. During the period from the moment the foot pedal control switch 7 is triggered to descend until the mechanical lifting stop 6 is raised and reset, the system controller disables the initiation of step S1. S3: Perform empty pallet transfer, the steps of which include: S301: Perform empty pallet loading When the system is in the state that allows empty pallet loading, and the second photoelectric detection switch detects that the empty pallet is in place, and the foot control switch 7 is triggered to descend, the system controller controls the mechanical lifting stop 6 to descend, starts the third delay, and after the third delay ends, controls the plate conveyor line 1 to run a third preset distance toward the forklift side, and then controls the mechanical lifting stop 6 to rise. S302: Perform empty tray unloading When the second photoelectric detection switch detects that the forklift is in place, the system controller starts the fourth delay. After the fourth delay ends, the system controller controls the plate conveyor line 1 to run a fourth preset distance toward the forklift and then stops. During the execution of step S302, the system controller disables the initiation of step S301.

[0055] The detailed implementation process of the control software flow is as follows: After the system is powered on, the PLC first performs a self-test and initializes the mechanical lifting stop 6 to the rising state. Then, the system enters the main loop, waits for and executes the following process: 1. Fully loaded pallet loading process Triggering condition: When the laser detection switch 10 and the second photoelectric detection switch simultaneously detect that the target (forklift and pallet) is in place, the PLC determines that the triggering condition is met.

[0056] Execution process: The PLC initiates the first delay, prompting the forklift driver to place the pallet and leave. After the delay ends, the PLC controls the frequency converter to start, driving motor 4 to make the plate conveyor line 1 run a first preset distance towards the trolley side, accurately transporting the fully loaded pallet to the unloading station on the trolley side.

[0057] Complete: Conveying has stopped; awaiting unloading.

[0058] 2. Full-load pallet unloading process Triggering conditions: Triple confirmation is required. The PLC will only execute the unloading operation when all three conditions are met simultaneously: the trolley detection switch 8 detects that the trolley is in place, the first photoelectric detection switch 5 detects that the tray is in the unloading station, and the operator presses the "lower" pedal of the foot control switch 7.

[0059] Execution process: a. The PLC controls the mechanical lifting stop 6 to descend until it reaches the lowered position and the limit switch activates to confirm that the stop has been lowered.

[0060] b. Initiate the second delay to stabilize the stopping action.

[0061] c. After the second delay, the PLC restarts the motor, causing the plate conveyor line 1 to move a short second preset distance towards the trolley. The purpose of this design is to utilize the power of the conveyor line to assist the operator in easily pushing the pallet onto the waiting trolley, achieving semi-automatic unloading through human-machine collaboration.

[0062] Reset: When the operator presses the "rise" pedal, the PLC controls the stop to rise and reset.

[0063] Priority Management: From the moment the "Lower" pedal is pressed until the stop fully rises and resets, a "Unloading in Progress" flag (M0.0) ​​inside the PLC is set. In this state, the system will completely block the triggering of the "Full Pallet Loading Process," ensuring that the unloading operation is not disturbed.

[0064] Even if a forklift accidentally places a pallet, triggering the laser detection switch 10, the plate conveyor line 1 will not activate, effectively preventing conflicts with the unloading process and ensuring the safety of the trolley operator.

[0065] 3. Empty pallet transfer process Empty pallet loading: When the system allows and the second photoelectric detection switch detects that the empty pallet is located on the forklift side, the PLC controls the mechanical lifting stop 6 to descend, and after a delay, drives the plate conveyor line 1 to run a third preset distance towards the forklift side, retrieving the empty pallet from the trolley side onto the plate conveyor line 1.

[0066] Empty pallet unloading: When the second photoelectric detection switch detects that the forklift is in position and ready to pick up an empty pallet, the PLC starts the conveyor line to move a fourth preset distance towards the forklift, delivering the empty pallet for the forklift to pick up. During this process, the empty pallet loading action is also disabled to prevent process conflicts.

[0067] In the above process, over-position protection and interlock protection are adopted.

[0068] Over-limit protection: In any process, once the limit switch is triggered, the PLC will immediately and unconditionally execute the emergency stop procedure, cut off the motor power, forcibly stop the operation of the motor 4, and alarm on the human-machine interface (HMI). The fault needs to be manually reset.

[0069] Interlock protection: The program interlocks the "up" and "down" outputs of the lifting and lowering stops with software, and sets an interlock between the conveyor running direction and the stop status to prevent misoperation.

[0070] In summary, the advantages of the system of the present invention are as follows: High degree of automation: It enables automatic transfer of pallets between forklifts and trolleys, reducing manual intervention.

[0071] High safety: Through mechanical stops, vehicle stop devices, and strict electrical interlocking logic and priority management, it effectively prevents equipment collisions and personnel injuries.

[0072] The process is clear and reliable: each step has clear sensor detection and condition judgment, and the logic is rigorous, avoiding misoperation.

[0073] Efficiency Improvement: Two-way operation and automatic control optimize the material flow path and improve handling efficiency.

[0074] Application Example 1: Based on Example 2, this application example records the execution process of the PLC's internal program as follows: A: System power-on and self-test After the system is powered on, the PLC first performs a self-test to check whether the status of each input point is normal. Then, the PLC outputs a pulse signal to drive the mechanical lifting stop 6 to perform an "up" action until the "stop is in position" signal is valid, ensuring that the system starts in a safe protective state.

[0075] B: Fully loaded pallet loading process 1. Waiting and detection: The PLC continuously monitors the signal of input point I0.0, that is, the second photoelectric detection switch. When I0.0 changes from OFF to ON, it indicates that the forklift has entered the loading position.

[0076] 2. Delayed start: The PLC starts an internal timer T1 (set value = 15 seconds, which can be modified via HMI). At the same time, the HMI will display "Loading preparation, please place the tray".

[0077] 3. Operation execution: The forklift driver must place the fully loaded pallet on the conveyor line and drive away safely before the T1 timer ends, so that I0.0 returns to the OFF state.

[0078] 4. Conveying Execution: If timer T1 expires and I0.0 is OFF, confirming that the forklift has left, the PLC will execute the following actions: Set Q0.1 to the direction towards the trolley side.

[0079] Set Q0.0 to start the frequency converter and the plate conveyor 1 will start running.

[0080] The PLC controls the operating distance by using pulses fed back from the frequency converter or another timer, set to 15 seconds, corresponding to 1.5 meters.

[0081] 5. Stop and Complete: After reaching the preset running distance, the PLC resets Q0.0, the plate conveyor 1 stops, and one loading process is completed.

[0082] C: Full-load tray unloading process - unloading priority is reflected 1. Prerequisite check: The PLC continuously monitors I0.1, which is the signal of the first photoelectric detection switch 5. Only when I0.1 is ON, that is, when the trolley is in position, is it allowed to respond to the command of the foot control switch 7.

[0083] 2. Mechanical lifting stop 6 (lowering): When the operator presses the "lower" foot switch, I0.4 is ON. After the PLC detects the rising edge of I0.4, it executes: When Q0.2 is set, the mechanical lifting stop 6 descends. The push rod motor M2 actuates, and the stop arm descends.

[0084] Wait until I0.7 is ON, the stop drops to SQ2, then reset Q0.2 and start timer T2 (set value 10 seconds).

[0085] 3. Conveying Execution: After timer T2 ends, the PLC sets Q0.0 and Q0.1, and the plate conveyor 1 starts moving towards the trolley. The operator can then push the pallet onto the trolley.

[0086] 4. Stop and Reset: After reaching the preset running distance, the PLC automatically stops the plate conveyor 1. When the operator presses the "Up" foot switch (I0.5 ​​is ON), the PLC sets Q0.3, and the mechanical lifting stop 6 rises until I0.6 (SQ1) is ON and then stops.

[0087] Throughout the entire process, from the moment the "lower" foot switch is pressed until the mechanical lifting stop is fully raised and reset (I0.6 is ON), a "unloading in progress" flag (M0.0) ​​inside the PLC is set. When M0.0 is ON, the program will completely skip the response to the "full pallet loading process," and even if the second photoelectric detection switch on the forklift side is triggered, the pallet conveyor 1 will not start, thus achieving "unloading priority."

[0088] D: Empty pallet transfer process The loading (from the trolley side to the conveyor line) and unloading (from the conveyor line to the forklift side) processes for empty pallets are symmetrical and in the same principle as the above processes, but the control direction is reversed (PLC output Q0.1 is low level), and they also follow the "unloading priority" principle (when unloading an empty pallet, loading an empty pallet is disabled). Their delay times (T3, T4) can be set independently.

[0089] E: Security Protection Logic Over-limit protection: In any process, if the limit switch is triggered, the PLC will immediately and unconditionally reset, lock the inverter fault, and simultaneously display an alarm message on the HMI: "Pallet over-limit, please check!" The fault requires manual reset before operation can continue.

[0090] Interlock protection: The "raise" and "lower" outputs of the lifting stops are interlocked in the program to prevent simultaneous power supply. The running direction of the plate conveyor 1 is also interlocked with the status of the stops at both ends to ensure that the plate conveyor 1 cannot run in that direction when the stops are not raised.

[0091] The above embodiments have provided a detailed description of the present invention, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A plate conveyor system based on bidirectional control and priority management, characterized in that: Includes a plate conveyor line (1) driven by a motor (4) and a control box (2) with a system controller. The two ends of the plate conveyor line (1) are the forklift side and the trolley side, respectively. The trolley side is equipped with a first photoelectric detection switch (5), a mechanical lifting stop (6), a foot control switch (7) and a trolley detection switch (8); the forklift side is equipped with a laser detection switch (10), a vehicle stopper (9) and a second photoelectric detection switch. The signal input terminal of the system controller is electrically connected to the laser detection switch (10), foot control switch (7), trolley detection switch (8), first photoelectric detection switch (5), and second photoelectric detection switch; The first control output terminal of the system controller is electrically connected to the motor (4) and is used to control the motor (4) to start and make the plate conveyor line (1) run towards the trolley side according to the trigger signals of the laser detection switch (10) and the second photoelectric detection switch; The second control output terminal of the system controller is electrically connected to the push rod motor of the mechanical lifting stop (6) and the motor (4). According to the joint trigger signal of the trolley detection switch (8) and the foot control switch (7), and when the first photoelectric detection switch (5) detects that the tray is located at the unloading station, the mechanical lifting stop (6) is controlled to descend and the motor (4) is controlled to start so that the plate conveyor line (1) runs a preset distance to the trolley side.

2. The plate conveyor system based on bidirectional control and priority management according to claim 1, characterized in that: The mechanical lifting stop (6) also includes a stop arm driven by the push rod motor and a position detection mechanism for detecting the lifting and lowering state of the stop arm. The signal output terminal of the position detection mechanism is electrically connected to the signal input terminal of the system controller.

3. The plate conveyor system based on bidirectional control and priority management according to claim 2, characterized in that, The position detection mechanism includes an upward limit switch and a downward limit switch.

4. The plate conveyor system based on bidirectional control and priority management according to claim 1, characterized in that: The laser detection switch (10) is equipped with a laser reflector (11), which is positioned opposite to the laser detection switch (10) on the forklift side to form a through-beam detection light curtain.

5. The plate conveyor system based on bidirectional control and priority management according to claim 1, characterized in that: The forklift side is provided with a fixed stop that is fixedly installed at the end of the frame of the plate conveyor line (1). The fixed stop is an L-shaped steel structure.

6. The plate conveyor system based on bidirectional control and priority management according to claim 1, characterized in that: The first photoelectric detection switch (5) and the second photoelectric detection switch are through-beam photoelectric switches.

7. The plate conveyor system based on bidirectional control and priority management according to claim 6, characterized in that: The forklift side and / or trolley side are also provided with limit switches for detecting pallet over-extension. The signal output terminal of the limit switch is electrically connected to the system controller and is used to trigger the emergency stop of the plate conveyor line (1) when pallet over-extension is detected.

8. The plate conveyor system based on bidirectional control and priority management according to claim 1, characterized in that: The power supply circuit of the motor (4) is equipped with a frequency converter. The control terminal of the frequency converter is electrically connected to the first control output terminal of the system controller, and the power output terminal of the frequency converter is electrically connected to the motor (4).

9. The plate conveyor system based on bidirectional control and priority management according to claim 1, characterized in that: The control box (2) is equipped with an operation indicator (3) that is electrically connected to the system controller.

10. A control method for a plate conveyor line based on bidirectional control and priority management, using the plate conveyor line system based on bidirectional control and priority management as described in any one of claims 1-9, characterized in that, Includes the following steps: S1: Perform full pallet loading When the laser detection switch (10) and the second photoelectric detection switch detect that the target is in place, the system controller starts the first delay. After the first delay ends, the system controller controls the plate conveyor line (1) to run a first preset distance to the trolley side and then stops. S2: Perform full-load tray unloading When the trolley detection switch (8) detects that the trolley is in place and the foot control switch (7) is triggered to descend, if the first photoelectric detection switch (5) simultaneously detects that the tray is located at the unloading station, the system controller executes an unloading operation, the unloading operation steps of which include: S201: Control the mechanical lifting stop (6) to descend; S202: Start the second delay. After the second delay ends, control the plate conveyor line (1) to run a second preset distance toward the trolley side so that the operator can transfer the pallet to the trolley. When the foot pedal control switch (7) is triggered to rise, the mechanical lifting stop (6) is controlled to rise. During the period from the start of the descent triggered by the foot pedal control switch (7) until the mechanical lifting stop (6) is raised and reset, the system controller disables the start of step S1. S3: Perform empty pallet transfer, the steps of which include: S301: Perform empty pallet loading When the system is in the state of allowing empty pallet loading, and the second photoelectric detection switch detects that the empty pallet is in place, and the foot control switch (7) is triggered to descend, the system controller controls the mechanical lifting stop (6) to descend, starts the third delay, and after the third delay ends, controls the plate conveyor line (1) to run a third preset distance to the forklift side, and then controls the mechanical lifting stop (6) to rise. S302: Perform empty tray unloading When the second photoelectric detection switch detects that the forklift is in place, the system controller starts the fourth delay. After the fourth delay ends, the system controller controls the plate conveyor line (1) to run a fourth preset distance toward the forklift and then stops. During the execution of step S302, the system controller disables the initiation of step S301.

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