Method for realizing full-automatic packing of cold-rolled threaded steel bar production line

Abstract

The method for realizing full-automatic packing of cold-rolled threaded steel bar production line is realized on the existing semi-automatic packing machine and the manual conveying system of cold-rolled threaded steel bar, A: setting length measuring roller B: setting waiting position proximity switch and hoisting position proximity switch on the manual conveying system; C: realizing information exchange communication between the conveying system and the semi-automatic packing machine; D: calculating the distance from each lashing position to the head of the bale during packing, Ln=(Lc-Lh-Lt) / (n-1)+Lh, wherein Lc: total length of the bar product to be packed; Lh: head turn distance; Lt: tail turn distance; n: total turn number; E: real-time measuring the length of the bale passing through the center line of the semi-automatic packing machine, when the length is equal to the length of a turn in the previous n-1 turns, the semi-automatic packing machine runs lashing. The method can realize automatic packing.

Description

Technical Field

[0001] This invention relates to cold-rolled wire rod packaging, and particularly to a method for achieving fully automated packaging in a cold-rolled rebar production line, belonging to the field of cold-rolled wire rod technology. Background Technology

[0002] On hot-rolled wire rod and bar production lines, coil balers and bar balers developed from them have been largely domestically produced, with automation levels comparable to foreign counterparts, and the gap in durability and stability is narrowing. However, the baling process on domestic cold-rolled rebar production lines has not been fully automated, for the following reasons:

[0003] 1) Most cold-rolled rebar bar manufacturers are small and medium-sized enterprises. The operators are unwilling to invest too much money to purchase expensive packaging machines and their supporting automation equipment. In their view, the investment and return ratio is not worthwhile.

[0004] 2) The existing cold-rolled rebar production line has a low speed, and the demand for full automation of the packaging process is not so strong.

[0005] 3) Packaging machine suppliers often only provide the main packaging machine, and the supporting feeding and conveying system is usually required to be solved by the enterprise itself. However, these small and medium-sized enterprises do not have the technical ability to design an automatic feeding and conveying system that matches the packaging machine, and cannot achieve full automation of packaging.

[0006] Based on the above points, the current control of the bar packaging process in cold-rolled rebar production lines is either fully manual or semi-automatic. The implementation methods and advantages and disadvantages of the two methods are as follows:

[0007] 1. Fully manual

[0008] The most common type of manual bar baling machine is the pneumatic baling machine, which is powered by compressed air and uses strapping. Users typically mount the baling machine on a movable baling cart. The bundle of bar material to be baled remains stationary. The operator first manually moves the baling cart to the baling position, then operates the baling machine to begin baling, baling one turn at a time. After baling one turn, the baling cart is moved to the next baling position to perform the next turn, until the entire bundle is baled. Generally, 9 meters of bar material requires 9 turns, which means the baling cart needs to be moved 9 times and the baling machine needs to be operated 9 times manually. The advantages of this method are low investment, simple equipment and control methods, and ease of implementation. The disadvantages are high labor intensity and low efficiency; when the production line speed exceeds 200 meters per minute, even a skilled worker will find it difficult to keep up with the production pace.

[0009] 2. Semi-automatic

[0010] Semi-automatic refers to the automatic completion of the bar baling process itself, but the operation of auxiliary baling equipment, the start and stop of the baling feeding conveyor system, and signal exchange still require manual operation. Semi-automatic bar baling machines are generally fully hydraulic systems. A baling cycle includes wire threading, tightening, twisting, shearing, resetting, and flattening, all of which can be completed automatically by the baling machine. The auxiliary equipment of the baling machine refers to the forming device, which holds the material bundle tightly throughout the baling process, making the bales more uniform and compact. After baling, the forming device releases, and the feeding conveyor system activates. The advantages of semi-automatic baling are lower equipment investment, simpler electrical control systems, and the ability to complete the entire baling operation from a single control panel. It also reduces labor intensity and can accommodate higher production speeds. The disadvantages are that it still requires operators, and the baling speed is relatively limited, making it unsuitable for the ever-increasing speed of rebar bar production lines. Although semi-automatic baling is a significant improvement over manual baling, it still lags behind in the face of trends towards intelligent, high-speed, and large-scale production. Cold-rolled rebar bar production lines urgently need low-cost, fully automated solutions for the baling process. Summary of the Invention

[0011] The purpose of this invention is to overcome the aforementioned problems in the packaging of cold-rolled threaded steel bars in current production processes, and to provide a method for achieving fully automated packaging in a cold-rolled threaded steel bar production line.

[0012] To achieve the objective of this invention, the following technical solution is adopted: a method for fully automated packaging of cold-rolled threaded steel bars in a production line. This fully automated packaging method is implemented on existing semi-automatic packaging machines and manual conveying systems for cold-rolled threaded steel bars, using the following method:

[0013] A: A length measuring roller is installed between the manual conveying system and the semi-automatic baling machine. When the cold-rolled threaded steel bar is conveyed to the semi-automatic baling machine, it drives the length measuring roller to rotate. A rotary encoder is installed on the length measuring roller and connected to the PLC control system.

[0014] B: A waiting position proximity switch is installed on the manual conveying system before the semi-automatic baling machine to detect the cold-rolled threaded steel bars. After the cold-rolled threaded steel bars trigger the waiting position proximity switch, the manual conveying system stops, and the cold-rolled threaded steel bars are in the baling waiting position. A lifting position proximity switch is installed on the manual conveying system after the semi-automatic baling machine to detect the bagged cold-rolled threaded steel bars. After the bagged cold-rolled threaded steel bars trigger the lifting position proximity switch, they stop and wait for lifting. After lifting is completed, the PLC control system receives the stop position proximity switch signal. The above manual conveying system is connected to the PLC control system to form a conveying system.

[0015] C: A dry contact method is used to achieve information exchange and communication between the conveyor system and the semi-automatic packing machine. The specific information to be exchanged is as follows:

[0016] 1. Semi-automatic baling machine to conveyor system:

[0017] 1.1 Ready: This signal indicates that the semi-automatic baler is in good working order and ready to go; if it is not, it indicates that the semi-automatic baler is malfunctioning and the conveyor system is prohibited from feeding materials into the baler.

[0018] 1.2 Original position: This indicates that the semi-automatic baler is currently at the original position after being operated in manual or automatic mode. This signal is a safety interlock signal, and the conveying system is allowed to operate and the bales can pass through the baler only when it is valid.

[0019] 1.3 Packaging complete: The semi-automatic packaging machine activates this signal once after packaging one turn. The conveying system uses this signal to count the number of turns and as a trigger signal for the next action in the automatic control process.

[0020] 1.4 Response Signals: To ensure the reliability of communication, after receiving two signals from the conveyor system, the packaging system will send two response signals to the conveyor system accordingly.

[0021] 2. Manual conveyor to semi-automatic packing machine:

[0022] 2.1 Ready: This indicates that the conveying system is functioning correctly and the baler can operate in automatic mode.

[0023] 2.2 Packaging Request: This signal is valid once after the conveyor system completes each packaging positioning, and sends a packaging request signal to the semi-automatic packaging machine;

[0024] 2.3 Response Signals: After receiving the three signals sent by the packaging system, the conveying system will send three response signals to the semi-automatic packaging system accordingly.

[0025] D: Calculate the length of each bundle based on the bar length, number of bundle turns, distance between the first and last bundle turns, and distance between the first and last bundle turns. The distance between the first and last bundle turns refers to the distance between the first bundle turn and the end of the bundle. Obtain the distance from each binding wire position to the head of the bundle using the following formula:

[0026] Ln = (Lc - Lh - Lt) / (n - 1) + Lh (n ≥ 2)

[0027] In the above formula:

[0028] Ln: The target position of the nth turn of the packing wire;

[0029] Lc: Total length of the bar stock to be packaged;

[0030] Lh: Distance between the first and second turns;

[0031] Lt: Tail turn distance;

[0032] n: Total number of turns to be packaged;

[0033] E: During the conveying process of the material bundle, the length of the material bundle passing through the center line of the semi-automatic baler is measured in real time. When this length is equal to the length of a certain turn in the previous n-1 turns, the conveying system stops and the semi-automatic baler runs to tie the binding wire onto the material bundle.

[0034] The length of the material bundle passing the center line of the semi-automatic baling machine is obtained by the following formula:

[0035] Lg = Cp × (Lp / Pn) - Lb

[0036] In the above formula:

[0037] Lg: The length of the bundle of material passing the center line of the semi-automatic packaging machine;

[0038] Cp: ​​The number of pulses received by the PLC high-speed module from the encoder;

[0039] Lp: Circumference of the measuring roller;

[0040] Pn: Number of lines in the encoder;

[0041] Lb: Distance from the measuring roller to the center line of the semi-automatic packing machine;

[0042] F: After the semi-automatic baler attaches the binding wire to the bundle, it sends a signal to the conveying system, which then feeds the material to the semi-automatic baler. Step E is repeated until the binding wire at position n-1 is attached to the bundle.

[0043] F: When determining the position of the binding wire of the nth turn, the conveying system adopts time control, as follows: The average time taken by the conveying system to convey the length of the bundle between two adjacent turns from the 1st turn to the (n-1th turn) is calculated in the control system. After the (n-1th turn) binding wire is completed, the average time taken by the conveying system to feed the semi-automatic packaging machine is adopted.

[0044] G: After completing the nth turn of wire binding, the conveying system will transport the bundle to the hoisting position. After the bundle triggers the hoisting position proximity switch, the conveying system will stop, and the length counter and the number of turns counter will be reset to zero.

[0045] Furthermore, in step D, the setting of the head turn distance and tail turn distance takes into account the inertial distance of the conveying system. The inertial distance refers to the distance traveled by the conveying system during the time it takes for the control system to completely stop after issuing a stop command; wherein: head turn distance = set head turn distance + inertial distance; tail turn distance = set tail turn distance - inertial distance; the set head turn distance and set head and tail turn distance are the values ​​set on the touch screen of the control system.

[0046] The beneficial technical effects of this invention are as follows: the equipment configuration is basically the same as the semi-automatic method, with only the addition of speed measurement, calculation, communication with the packing machine, and logic control components. The cost increase is extremely limited and can be basically ignored. It truly achieves full automation in the packing process of cold-rolled threaded bar production, eliminating the need for manual intervention and significantly increasing packing efficiency. Due to the significantly improved accuracy of automatic feeding and positioning, the number of turns in each finished product is exactly the same, virtually eliminating the occurrence of extra or missing turns, ensuring safety and reliability during transportation. The number of turns and the position of the wires can be "arbitrarily" modified and set according to the process or customer's specific requirements, improving the adaptability of the entire control system. It can be directly transplanted to almost all applications in the industry without any further modifications. Multiple applications of this method in various projects and production lines of different specifications have shown that it fully achieves the expected design results and is an ideal alternative to the semi-automatic packing method. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the packaging system used in this method. Detailed Implementation

[0048] The invention will be explained in detail with reference to the accompanying drawings, in which the following labels are used: 1: Packing machine; 2: Forming device A; 3: Forming device B; 4: Measuring roller; 5: Rotary encoder; 6: Conveying system section A; 7: Conveying system section B; 8: Packing waiting position; 9: Lifting waiting position. Items 1, 2, and 3 are present in current semi-automatic packing machines; 6 and 7 are present in manual conveying systems; 4 and 5 are newly added to achieve fully automatic packing; and 8 and 9 are set in the control system via proximity switches.

[0049] The hardware used in the method of this invention mainly includes a PLC (Programmable Logic Controller), an HMI (Handheld Machine), a PLC high-speed counting module, a PLC digital input / output module, a photoelectric rotary encoder, a motor controller, and proximity switches. The original semi-automatic bar packaging machine had its own separate control system; the control system in this solution only needs to complete the necessary signal interaction with it.

[0050] The PLC main unit (CPU) mainly performs logic control and positioning control related calculations for the positioning conveyor system and the forming machine; the HMI completes the setting, display, and monitoring of various parameters; the PLC high-speed counting module counts the pulses sent by the encoder at high speed, and the PLC completes the calculation of the actual corresponding length; the motor controller drives the positioning conveyor system to complete positioning-related actions such as start and stop; proximity switches are used to determine the positions of the packaging waiting position, hoisting position, forming machine clamping and releasing position, etc., and complete the acquisition of related equipment actions and safety signals.

[0051] 3. HMI parameter settings

[0052] To complete the calculation of positioning and conveying data and cooperate with the packaging machine control system, the PLC system needs to work together to achieve truly fully automated packaging. The following parameters need to be preset on the HMI:

[0053]

Product Length

[0054]

Number of Turns for Packing

[0055]

First Turn Distance

[0056]

Tail Bundle Distance

[0057]

Encoder Pulse Count

[0058]

Circumference of measuring roller

[0059]

Length Measurement - Packaging Axis Distance

[0060] This example of a packing and positioning conveyor system does not use a servo or frequency converter drive system; instead, it uses the most economical motor controller, similar to a contactor. This is not precision positioning control, and given the large inertia of the material bundles, there is a certain time required from the control system issuing a stop command to the conveyor system completely stopping. This means that the bar material bundles will have an overshoot distance in the conveyor. To ensure uniform packing distance between the head and tail of the packing wires, the "head wrap distance" and "tail wrap distance" parameters can be modified. For example, we want both the head and tail wrap distances to be 350mm, but there is an overshoot of 50mm every time the conveyor stops feeding. Multiple engineering examples have verified that the overshoot distance is basically a constant value. Therefore, we can set the "head wrap distance" and "tail wrap distance" to 300mm and 400mm respectively. If the control logic, process, and principle remain unchanged, and some cost is increased by replacing the positioning conveyor system with a frequency converter or servo drive, the positioning control effect will likely be better, and the inertial momentum will be reduced.

[0061] 4. Calculations related to the positioning of the conveyor system

[0062] Packaging and positioning conveying systems are a type of motion control, specifically positioning control. To achieve positioning control, one must first know the target location and then the current location.

[0063] The target location in this solution is the distance from each bundling position (i.e., the tie wire position) to the head of the bundle. Based on the parameters set on the HMI, the position of each bundle of tie wire can be easily calculated using the following formula:

[0064] Ln=(Lc-Lh-Lt) / (n-1)+Lh (n>=2)

[0065] In the formula:

[0066] Ln: The target position of the nth turn of the packing wire;

[0067] Lc: Total length of the bar stock to be packaged (HMI preset parameter);

[0068] Lh: One turn head distance, which is also the target position of the first turn of packing wire (HMI preset parameter);

[0069] Lt: End-turn distance (HMI preset parameter);

[0070] n: Total number of turns to be packaged (HMI preset parameter);

[0071] In this solution, "current position" refers to the length of the material bundle that the feeding and positioning conveyor system passes through the center line of the baling machine during the transport of the bundle to be packaged. The calculation formula is as follows:

[0072] Lg = Cp × (Lp / Pn) - Lb

[0073] In the formula:

[0074] Lg: The length of the bundle of material passing through the center line of the baler;

[0075] Cp: ​​The number of pulses received by the PLC high-speed module from the length encoder;

[0076] Lp: Circumference of the measuring roller of the measuring device (HMI preset parameter);

[0077] Pn: Number of lines of the length measuring encoder (HMI preset parameter);

[0078] Lb: Distance from the length measuring roller to the packaging center line (HMI preset parameter);

[0079] Each positioning process of the conveying system is actually the process of the control system continuously comparing the size of Lg and Ln. When Lg = Ln, the positioning is completed, the conveying system stops, and packaging begins.

[0080] 5. Communication between the conveyor control system and the baling machine control system:

[0081] The conveyor control system and the packaging machine control system are two independent systems. To achieve fully automated packaging, these two control systems must be able to communicate to exchange certain specific information. In this solution, the information that needs to be exchanged between the two systems is relatively limited, and communication is conducted via dry contacts. The information to be exchanged is as follows.

[0082] 1) From the baler to the conveyor

[0083] 1.1 Ready: This signal indicates that the baler is in good working order and ready to go; if it is not, it indicates that the baler is faulty and the conveyor system is prohibited from feeding materials to the baler.

[0084] 1.2 Original position: This indicates that the baler is currently at the original position after being operated in manual or automatic mode. This signal is a safety interlock signal. Only when it is valid can the conveying system be allowed to operate and the bales be allowed to pass through the baler.

[0085] 1.3 Packaging complete: This signal is valid once for each turn the packing machine completes. The conveying system uses this signal to count the number of turns and as a trigger signal for the next action in the automatic control process.

[0086] 1.4 Response Signals: To ensure the reliability of communication, after receiving two signals from the conveyor system, the packaging system will send two response signals (handshake signals) to the conveyor system accordingly.

[0087] 2) Conveyor – Packing Machine

[0088] 2.1 Ready: This indicates that the conveying system is functioning correctly and the packing machine can operate in automatic mode.

[0089] B Packaging Request: This signal is valid once after the conveyor system completes a packaging positioning, and sends a packaging request signal to the packaging machine.

[0090] Response signals: After receiving the three signals sent by the packaging system, the conveying system will send three response signals to the packaging system accordingly.

[0091] 6. Packaging of the final coil

[0092] Due to space constraints, the distance Lb from the measuring roller to the packing center line may be greater than the distance of the last turn. In this case, when the last turn is made, the entire bundle of material has already detached from the measuring roller, making it impossible to position.

[0093] To address this issue, the control system no longer relies on encoder data for positioning the final turn; instead, it uses time control. Except for the first turn, the conveyor distance is the same for each subsequent turn. Since the conveyor is controlled by a motor controller, its speed is also consistent during each positioning run, therefore the running time should also be the same. To ensure positioning accuracy, the system measures the running time during each turn's positioning process (except for the first turn), filters and averages this time data, and then uses this average as the conveyor system running time for the final turn's positioning. Practice has shown that this method does not affect the accuracy of the packaging positioning. This method was only used in the first project.

[0094] By implementing the above detailed method and converting it into a relevant control program according to the fully automatic packaging flowchart, the fully automatic control of the bar packaging machine can be achieved.

[0095] Those skilled in the art will clearly understand that various changes and modifications can be made without departing from the scope and spirit of the above patent. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention, and the invention is not limited to the implementation of the examples given in the specification.

Claims

1. A method for achieving fully automated packaging in a cold-rolled rebar bar production line, wherein the fully automated packaging method is implemented on an existing semi-automatic packaging machine and a manual conveying system for cold-rolled rebar bars, characterized in that: The following methods are used: A: A length measuring roller is installed between the manual conveying system and the semi-automatic baling machine. When the cold-rolled threaded steel bar is conveyed to the semi-automatic baling machine, it drives the length measuring roller to rotate. A rotary encoder is installed on the length measuring roller and connected to the PLC control system. B: A waiting position proximity switch is installed on the manual conveying system before the semi-automatic baling machine to detect the cold-rolled threaded steel bars. After the cold-rolled threaded steel bars trigger the waiting position proximity switch, the manual conveying system stops, and the cold-rolled threaded steel bars are in the baling waiting position. A lifting position proximity switch is installed on the manual conveying system after the semi-automatic baling machine to detect the bagged cold-rolled threaded steel bars. After the bagged cold-rolled threaded steel bars trigger the lifting position proximity switch, they stop and wait for lifting. After lifting is completed, the PLC control system receives the stop position proximity switch signal. The above manual conveying system is connected to the PLC control system to form a conveying system. C: A dry contact method is used to achieve information exchange and communication between the conveyor system and the semi-automatic packing machine. The specific information to be exchanged is as follows:

1. Semi-automatic baling machine to conveyor system: 1.1 Ready: This signal indicates that the semi-automatic baler is in good working order and ready to go; if it is not, it indicates that the semi-automatic baler is malfunctioning and the conveyor system is prohibited from feeding materials into the baler. 1.2 Original position: This indicates that the semi-automatic baler is currently at the original position after being operated in manual or automatic mode. This signal is a safety interlock signal, and the conveying system is allowed to operate and the bales can pass through the baler only when it is valid. 1.3 Packaging complete: The semi-automatic packaging machine activates this signal once after packaging one turn. The conveying system uses this signal to count the number of turns and as a trigger signal for the next action in the automatic control process. 1.4 Response Signals: To ensure the reliability of communication, after receiving two signals from the conveyor system, the packaging system will send two response signals to the conveyor system accordingly.

2. Manual conveyor to semi-automatic packing machine: 2.1 Ready: This indicates that the conveying system is functioning correctly and the baler can operate in automatic mode. 2.2 Packaging Request: This signal is valid once after the conveyor system completes each packaging positioning, and sends a packaging request signal to the semi-automatic packaging machine; 2.3 Response Signals: After receiving the three signals sent by the packaging system, the conveying system will send three response signals to the semi-automatic packaging system accordingly. D: Calculate the length of each bundle based on the bar length, number of bundle turns, distance between the first and last bundle turns, and distance between the first and last bundle turns. The distance between the first and last bundle turns refers to the distance between the first bundle turn and the end of the bundle. Obtain the distance from each binding wire position to the head of the bundle using the following formula: Ln = (Lc - Lh - Lt) / (n - 1) + Lh (n ≥ 2) In the above formula: Ln: The target position of the nth turn of the packing wire; Lc: Total length of the bar stock to be packaged; Lh: Distance between the first and second turns; Lt: Tail turn distance; n: Total number of turns to be packaged; E: During the conveying process of the material bundle, the length of the material bundle passing through the center line of the semi-automatic baler is measured in real time. When this length is equal to the length of a certain turn in the previous n-1 turns, the conveying system stops and the semi-automatic baler runs to tie the binding wire onto the material bundle. The length of the material bundle passing the center line of the semi-automatic baling machine is obtained by the following formula: Lg = Cp × (Lp / Pn) - Lb In the above formula: Lg: The length of the bundle of material passing the center line of the semi-automatic packaging machine; Cp: ​​The number of pulses received by the PLC high-speed module from the encoder; Lp: Circumference of the measuring roller; Pn: Number of lines in the encoder; Lb: Distance from the measuring roller to the center line of the semi-automatic packing machine; F: After the semi-automatic baler attaches the binding wire to the bundle, it sends a signal to the conveying system, which then feeds the material to the semi-automatic baler. Step E is repeated until the binding wire at position n-1 is attached to the bundle. F: When determining the position of the binding wire of the nth turn, the conveying system adopts time control, as follows: The average time taken by the conveying system to convey the length of the bundle between two adjacent turns from the 1st turn to the (n-1th turn) is calculated in the control system. After the (n-1th turn) binding wire is completed, the average time taken by the conveying system to feed the semi-automatic packaging machine is adopted. G: After completing the nth turn of wire binding, the conveying system will transport the bundle to the hoisting position. After the bundle triggers the hoisting position proximity switch, the conveying system will stop, and the length counter and the number of turns counter will be reset to zero.

2. The method for fully automated packaging of cold-rolled threaded steel bar production line according to claim 1, characterized in that: In step D, the setting of the head turn distance and tail turn distance takes into account the inertial distance of the conveying system. The inertial distance refers to the distance the conveying system travels during the time it takes for the control system to completely stop after issuing a stop command. Wherein: head turn distance = set head turn distance + inertial distance; tail turn distance = set tail turn distance - inertial distance; the set head turn distance and set head and tail turn distance are the values ​​set on the touch screen of the control system.

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