A method of automatically pushing the blades of a double-sided shears

Abstract

The application discloses a method for automatically pushing blades of double-sided shears, and belongs to the field of blade replacement of double-sided shears. The method comprises the following steps: designing an automatic blade pushing device, designing automatic control of a blade pushing equipment, and designing automatic positioning function of a blade replacement trolley. The application not only improves production efficiency, but also reduces production cost. Since the pushing and positioning processes of the blades are automated, manual intervention and errors are reduced, thereby improving the consistency and stability of production. At the same time, since the pushing process is more accurate and efficient, waste and loss in the production process are also reduced, further reducing the production cost. On the other hand, since the automatic blade pushing device is put into use, a series of safety problems caused by poor communication between post operators in two places are eliminated, and the original blade replacement time is shortened.

Description

Technical Field

[0001] This invention relates to the replacement of the blades of a double-sided scissor, and more particularly to a method for automatically pushing the blades of a double-sided scissor. Background Technology

[0002] The 4.2M double-sided shearing machine in the heavy plate mill, as a key piece of equipment on the production line, is ingeniously designed and powerfully functional. It mainly consists of a three-axis, three-eccentric rolling double-sided shearing machine meticulously crafted by SMS Group. The primary task of this machine is to precisely trim the edges of steel plates to meet the stringent width requirements of the finished steel plates.

[0003] In the design of double-sided shears, both the fixed and moving blades are equipped with a blade-changing device to ensure that the shearing quality of steel plates consistently meets high industry standards. However, currently, the blade changing operation on both sides of the double-sided shear still mainly relies on manual operation. This blade-changing device has a complex structure, including a blade-changing trolley, guide rails, a traverse trolley, a transmission device, lifting rollers, and blade transport rollers. The lifting and traverse movement of the changing trolley utilizes advanced hydraulic cylinder technology, while the movement of the traverse trolley is achieved by a motor driving a sprocket.

[0004] Currently, the blade replacement of the double-sided shears is all done manually. Every machine action requires manual operation step-by-step execution before the next action can proceed. The entire blade replacement process is slow and time-consuming; with three operators, replacing the blade on each side takes approximately 60 minutes. The entire blade replacement device is based on technology from ten years ago, far behind current automation levels. Manual blade replacement poses significant safety hazards and urgently needs improvement. Furthermore, while the double-sided shears blade replacement device is equipped with local control boxes on both sides, primarily responsible for on-site equipment access control and action execution, the blade lifting, lateral movement, and blade replacement arm are located close to the shear machine body, resulting in a dark and oily internal environment. These three components are also far from the local control boxes. Because blade replacement is a manual operation, daily blade replacement requires one operator at the control panel and another inside to direct the blade's ascent, ensuring it's in the correct position before locking it to prevent it from falling onto the scrap conveyor. Communication between the two operators is limited to walkie-talkies, shouting, or verbal communication. This results in low blade replacement efficiency and unclear communication of instructions, leading to equipment malfunctions and blades falling into the scrap pit, indirectly extending replacement time (as the scrap pit is small and dimly lit, pulling the blades out takes up to 2 hours). Unclear instructions also compromise the safety of the operator in charge, posing significant safety hazards. Furthermore, the double-sided shear blade transport roller conveyor primarily handles blade transport; currently, it uses mechanical rollers without any drive mechanism, requiring manual pushing to move the blades towards the lateral transport trolley. Each shear blade weighs approximately 1 ton, and the process of pushing it onto the traverse carriage for replacement takes more than 5 minutes. For operators with less strength, this can be even more time-consuming. If the operator's position is incorrect or the shear blade is not level, it can cause the operator to fall or the blade to slip off the roller conveyor and injure their feet. The entire shear blade pushing process poses significant safety hazards. Furthermore, manually pushing the shear blade to the lifting roller conveyor cannot guarantee accurate positioning, and the blade often falls off during the process, prolonging the blade replacement time (each blade drop takes 30 minutes to resolve) and reducing overall blade changing efficiency. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a method for automatically pushing the shear blades of a double-sided shear.

[0006] Technical solution: A method for automatically pushing the shear blades of a double-sided shear, comprising: (1) Design an automatic blade pushing device Based on the various process steps of the pusher, a complete automated pusher device was designed to automatically move the new and old shear blades on the auxiliary roller conveyor. (2) Design of automated control for pusher equipment Based on the manual push-knife process steps and the structure of the newly added mechanical equipment, automatic control of the push-knife equipment is achieved by adding electrical equipment such as photoelectric sensors, proximity switches, encoders, PLCs, frequency converters, and servo controllers. (3) Design the automatic positioning function of the tool changing trolley. After adding a position detection device to the tool changer carriage based on the original equipment on site, the L1 program of the tool changer carriage needs to be modified. After interrupting the original carriage movement process and adding two positions, the L1 program is modified to realize the automatic positioning of the tool changer carriage at the two newly added positions.

[0007] Preferably, the automated blade pushing equipment mainly includes: a blade pushing carriage, a side positioning device, a lateral moving device, and a conveyor roller conveyor; the blade pushing carriage is used to push the old blade to the designated position and push the new blade onto the lateral moving carriage. The blade pushing carriage achieves precise positioning by controlling the movement of the drive gears and racks through motor frequency conversion and encoder control, and limit position proximity switches and zero point proximity switches are set at the front and rear positions; the side positioning device consists of two 80 cylinders for side positioning of the new blade; the lateral moving device is used to switch the pushing position of the blade pushing carriage at different positions. The lateral moving device achieves precise positioning by controlling the movement of the drive gears and racks through stepper motor control, and limit position proximity switches and zero point proximity switches are set at the front and rear positions; the conveyor roller conveyor mainly consists of a passive roller conveyor and a guide plate. The passive roller conveyor supports the blade, and the guide plate guides the flow so that the blade slides smoothly during the pushing process.

[0008] Preferably, the automatic control process of the pusher device is as follows: (1) The new shear blade is lifted by the crane to the material feeding position of the conveyor roller, the side positioning device pushes the shear blade to the side for positioning, and the cylinder retracts after a 5-second delay; (2) The old upper shear blades that have been replaced are transported to the designated position by the transverse trolley. The shear blade pusher pushes the old upper shear blades that have been replaced to the position of the upper shear blade discharge roller. (3) The shear blade trolley returns to the designated position and pushes the old lower shear blade that was replaced to the upper shear blade discharge roller position; (4) The shear blade trolley switches the shear blade position and pushes the new shear blade to the designated position on the transverse trolley; (5) The side positioning cylinder pushes the remaining shear blade to the side positioning again, and the cylinder retracts after a 5-second delay. (6) Push the shear blade trolley back to the designated position and push the new lower shear blade to the fixed position of the exit traverse trolley; (7) Push the shear blade trolley back to the original position, and the work is finished.

[0009] Beneficial Effects: The application of this invention not only improves production efficiency but also reduces production costs. Because the pushing and positioning process of the shear blades is automated, manual intervention and errors are reduced, thereby improving production consistency and stability. Simultaneously, the more precise and efficient pushing process also reduces waste and losses during production, further lowering production costs. Furthermore, the use of the automatic blade-pushing device eliminates a series of safety issues caused by poor communication between operators in different locations and shortens the original blade-changing time. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the automatic pusher device of the present invention; Figure 2 This is a schematic diagram of the closed-loop control of the pusher device. Detailed Implementation

[0011] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0012] A method for automatically pushing the shear blades of a double-sided shear, comprising: (1) Design an automatic blade pushing device Based on the various steps of the blade pushing process, a complete automated blade pushing device was designed for the automatic movement of new and old shear blades on an auxiliary roller conveyor. It mainly consists of a blade pushing carriage, a side positioning device, a lateral movement device, and a conveyor roller conveyor. The blade pushing carriage is responsible for pushing the old shear blade to the designated position and pushing the new shear blade onto the lateral movement carriage. The blade pushing carriage achieves precise positioning through motor frequency conversion and encoder control of the drive gear and rack mechanism, with limit position proximity switches and zero point proximity switches at the front and rear positions. The side positioning device consists of two 80mm cylinders responsible for the side positioning of the new shear blade. The lateral movement device is responsible for switching the pushing position of the blade pushing carriage at different locations. The lateral movement device achieves precise positioning through stepper motor control of the drive gear and rack mechanism, with limit position proximity switches and zero point proximity switches at the front and rear positions. The conveyor roller conveyor mainly consists of a passive roller conveyor and guide plates. The roller conveyor supports the shear blade, and the guide plates guide the flow, allowing the blade to slide smoothly during the pushing process.

[0013] The selection calculation is as follows: Since the shear blade weighs 500 kg, the friction coefficient of the rolling mill is approximately 0.1. According to the dynamic friction formula F = μF... n , where μ=0.1, F n =500Kg×9.8N / Kg=4900N, therefore F=490N, meaning the thrust required by the transmission device is approximately 490N.

[0014] Decompose the shearing action. At the beginning of the shearing process, the pushing force is greater than or equal to the static friction force of the shear blade on the rolling bed. Use the equilibrium condition method to solve for the static friction force. Since static friction force is a passive force, it varies with the external force acting on the object. The range of static friction force is: 0 ≤ F ≤ F max It is unrelated to the normal force of the object, so the formula F=μF cannot be used. n calculate.

[0015] The maximum static friction force is equal to the external force along the contact surface when the object just begins to slide; it is the maximum static friction force greater than the sliding friction force. The formula is F. max =μ 静 ×F n μ of the rolling bed 静 The value is approximately 0.13, therefore the maximum static friction force that the transmission device needs to overcome at the beginning of startup is approximately 637 N.

[0016] The system is designed with a motor output torque of 115 N / m, a gearbox rack and pinion mechanism with a reduction ratio of 22.6, an output speed of 62 r / min, a gear pitch circle diameter of 100 mm, and a trolley pusher speed of approximately 19.47 m / min. Calculate the motor thrust F. 推 =115N × 22.6 = 2599N. This means the maximum thrust of the system design is far greater than the static and dynamic friction of the shear blades. The system operating speed of 19.47 m / min also meets the production rhythm requirements.

[0017] Similarly, the static friction and sliding friction required for the cylinder to push the shear blade are calculated as follows: F max =500Kg×9.8N / kg×2×0.34=3332N F 推 =500Kg×9.8N / Kg×2×0.3=2940N The system is designed with cylinder model 80-300, air pressure 5 bar, and cylinder thrust = 4×4×3.14×5×9.8=2461.7N.

[0018] Since there are 2 cylinders installed, the total cylinder thrust = 2461.7N × 2 = 4923.5N > F max >F 推 It fully meets the maximum thrust required for the lateral thrust of the shear blade.

[0019] (2) Design of automated control for pusher equipment Based on the manual push-knife process and the structure of the newly added mechanical equipment, automatic control of the push-knife equipment is achieved by adding electrical equipment such as photoelectric sensors, proximity switches, encoders, PLCs, frequency converters, and servo controllers. Figure 1 (As shown). The automatic control process is as follows: (1) The new shear blade is lifted by the crane to the material feeding position of the conveyor roller, the side positioning device pushes the shear blade to the side for positioning, and the cylinder retracts after a 5-second delay; (2) The old upper shear blades that have been replaced are transported to the designated position by the transverse trolley. The shear blade pusher pushes the old upper shear blades that have been replaced to the position of the upper shear blade discharge roller. (3) The shear blade trolley returns to the designated position and pushes the old lower shear blade that was replaced to the upper shear blade discharge roller position; (4) The shear blade trolley switches the shear blade position and pushes the new shear blade to the designated position on the transverse trolley; (5) The side positioning cylinder pushes the remaining shear blade to the side positioning again, and the cylinder retracts after a 5-second delay. (6) Push the shear blade trolley back to the designated position and push the new lower shear blade to the fixed position of the exit traverse trolley; (7) Push the shear blade trolley back to the original position, and the work is finished.

[0020] The shear blade pushing action during equipment operation is achieved by a variable frequency motor driving the lead screw, the lateral movement of the baffle pushing the shear blade is achieved by a stepper motor, and the lateral movement of the shear blade on the roller bed is achieved by a cylinder.

[0021] The pusher motor uses closed-loop speed control with an encoder (e.g.) Figure 2 As shown in the figure, the automatic positioning of the pusher device is achieved by combining the specific position values ​​of the encoder. The encoder used for detection plays an important role in the control process. The overall control accuracy of the equipment is closely related to the detection accuracy of the encoder and the sampling period. Therefore, obtaining accurate feedback values ​​is also particularly important.

[0022] The closed-loop control system incorporates both speed and current negative feedback control. A speed PID controller and a current PID controller are connected in series. The output of the speed controller is used as the input of the current controller, and the output of the current controller then controls the triggering device of the inverter bridge thyristors. This combination of inner and outer loop regulation achieves precise motor control. Conventional PID is the most widely used control algorithm in industry, characterized by its simple structure, easily adjustable parameters, and independence from the precise mathematical model of the controlled system. For the motor speed control in this project, PI control generally provides satisfactory results. Considering that the frequency converter control system is a sampled-sample control system, the system employs a discretized, recursive incremental form of the PI control algorithm. Ek=Ui-Uk Pk=KcEk+Qk Qk=Pk-KpEk In the formula: Kp is the proportional coefficient; Kc = Kp(1+Ki), Ki is the integral coefficient; Ui is the setpoint; Uk is the measured value of the Kth sample; Qk is equivalent to the integral part of the correction quantity, and the initial value can be taken as Qk=0. In a digital PI control system, when the system starts, stops, or the setpoint changes significantly, the system output will show a large deviation. After the integral term accumulates, integral saturation may occur, thereby increasing the system settling time and overshoot, affecting the control effect. Therefore, measures to prevent integral saturation should be added to the PI algorithm.

[0023] According to the system design of the present invention: when the sampling period T=50ms, Kp=0.85, Kc=1.02, the speed error of the motor should be less than 1.0%, and the position accuracy should be within ±5mm, which fully meets the requirements of the field for position control accuracy.

[0024] (3) Design the automatic positioning function of the tool changing trolley. The original tool changer's mechanical structure and positioning principle, along with its control system using an S7-400 PLC, employ sequential step control with each step cycling sequentially. Adding a position detection device to the tool changer on-site necessitates modifying the L1 program. This involves interrupting the original trolley's movement to add two new positions, and then modifying the L1 program to achieve automatic positioning of the tool changer at these new positions (e.g., ...). Figure 2 (As shown). Example

[0025] In the loading process, the overhead crane plays a crucial role. It is responsible for precisely lifting the new blade to the designated loading position on the conveyor rollers. Once the new blade reaches the predetermined position, the operator will activate the cylinder extension button to ensure that the new blade is accurately positioned. To ensure positioning accuracy, the operator will perform a manual inspection to confirm that the new blade is fully in place. Once confirmed, the operator will press the cylinder retraction button to retract the cylinder.

[0026] The next step is to remove the old upper blade. In this step, the lateral movement pusher will initially remain at its origin. The operator activates the forward button on the pusher carriage, moving it to the retraction start position. Subsequently, the operator can manually control the pusher to move to the appropriate pusher working position using the left / right movement buttons. During the movement, the operator must remain highly vigilant to ensure that the pusher does not collide with the equipment or other components. Once the pusher has moved to the appropriate position, the operator will manually confirm that everything is correct before activating the reverse button on the pusher carriage, pushing the replaced old upper blade to the discharge roller conveyor position.

[0027] After the old upper blade is pushed out, the next step is to push the new upper blade. The operator first activates the left-shift button to return the lateral movement pusher to its initial position. Then, the operator activates the reverse button for the blade-pushing carriage, moving it to the starting position. Next, using the left-shift button, the operator manually controls the lateral movement device to move to the appropriate position. Again, only after manual confirmation can the forward button be activated to push the new upper blade from the conveyor rollers onto the blade-carrying carriage.

[0028] After the push is complete, the lateral movement device will return to its original position, and the blade-pushing carriage will also return to its original position. At this time, the operator will activate the cylinder extension button again to position the new lower blade. After positioning, the operator will manually check to confirm that the new lower blade is fully in place, and then press the cylinder retraction button to retract the cylinder.

[0029] In manual control, waiting for tool loading and unloading is an unavoidable step. Operators need to wait patiently to ensure these operations are performed at the correct time. The process of removing the old lower cutting edge and pushing the new lower cutting edge is similar to removing the old upper cutting edge and pushing the new upper cutting edge, only the objects being operated on are different.

[0030] The entire manual control process requires operators to possess extensive experience and keen insight to ensure the accuracy and safety of each step. Through manual control, operators can respond more flexibly to various situations, ensuring the smooth operation of the production process.

[0031] In the automated control process, the system achieves automated operation by monitoring the position of the tool transport carriage. First, the system uses proximity switches to detect whether the tool transport carriage is in retraction position 1 or retraction position 2. If the system does not detect a position signal, it will not perform any action. Only when the system detects that the tool transport carriage is in the correct retraction position will it begin the retraction operation.

[0032] During the tool retraction process, the push-edge carriage advances to the tool retraction start position, and then the lateral movement device moves to tool retraction position 1. Subsequently, the push-edge carriage begins to retreat, and the system controls its speed and position based on signals from proximity switches. When the push-edge carriage retreats to the tool retraction deceleration position, the system begins to decelerate until it senses the tool retraction stop proximity switch and stops. At this point, the tool retraction operation is complete, and the lateral movement device and the push-edge carriage return to their original positions.

[0033] Next comes the blade-pushing operation. The system first initiates the cylinder extension and lateral positioning process to ensure the new blade is accurately positioned. Then, the blade-pushing carriage retracts to the blade-pushing start position, and the lateral movement device moves to the blade-pushing position. Subsequently, the blade-pushing carriage begins to move forward, and the system controls its speed and position based on signals from proximity switches. When the blade-pushing carriage reaches the blade-pushing deceleration position, the system begins to decelerate until it senses the blade-pushing stop proximity switch and stops. At this point, the blade-pushing operation is complete, and the lateral movement device and blade-pushing carriage return to their original positions.

[0034] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for automatically pushing the shear blades of a double-sided scissor, characterized in that, include: (1) Design an automatic pusher device Based on the various process steps of the pusher, a complete automated pusher device was designed to automatically move the new and old shear blades on the auxiliary roller conveyor. (2) Design of automated control for pusher equipment Based on the manual push-knife process steps and the structure of the newly added mechanical equipment, automatic control of the push-knife equipment is achieved by adding electrical equipment such as photoelectric sensors, proximity switches, encoders, PLCs, frequency converters, and servo controllers. (3) Design the automatic positioning function of the automatic pusher device The automated blade-pushing equipment mainly includes: a blade-pushing trolley, a side positioning device, a lateral moving device, and a conveyor roller conveyor. The blade-pushing trolley is used to push the old blade to the designated position and push the new blade onto the lateral moving trolley. The blade-pushing trolley achieves precise positioning by controlling the movement of the drive gears and racks through a motor frequency converter and encoder. Limit position proximity switches and zero point proximity switches are set at the front and rear positions. The side positioning device consists of two 80mm cylinders and is used for side positioning of the new blade. The lateral moving device is used to switch the pushing position of the blade-pushing trolley at different positions. The lateral moving device achieves precise positioning by controlling the movement of the drive gears and racks through a stepper motor. Limit position proximity switches and zero point proximity switches are set at the front and rear positions. The conveyor roller conveyor mainly consists of a passive roller conveyor and a guide plate. The passive roller conveyor supports the blade, and the guide plate guides the flow so that the blade can slide smoothly during the pushing process. The automatic control process of the pusher device is as follows: (1) The new shear blade is lifted by the crane to the material feeding position of the conveyor roller, the side positioning device pushes the shear blade to the side for positioning, and the cylinder retracts after a 5-second delay; (2) The old upper shear blades that have been replaced are transported to the designated position by the transverse trolley, and the shear blade pusher pushes the old upper shear blades that have been replaced to the position of the upper shear blade discharge roller conveyor. (3) The shear blade trolley returns to the designated position and pushes the old lower shear blade that was replaced to the upper shear blade discharge roller position; (4) The shear blade trolley switches the shear blade position and pushes the new shear blade to the designated position on the transverse trolley; (5) The side positioning device pushes the remaining shear blade to the side positioning again, and the cylinder retracts after a 5-second delay; (6) Push the shear blade trolley back to the designated position and push the new lower shear blade to the fixed position of the exit traverse trolley; (7) Push the shear blade trolley back to the original position, and the work is finished.

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