What is A Robot-Assisted Bending System

Bending is widely used in modern industrial sheet metal processing. However, most of the bending processing is manual, which requires a large amount of labor and low production efficiency. The manual production process is prone to errors and has a certain degree of danger, which may lead to personal injury accidents. With the industrialization and scale of the sheet metal manufacturing industry, the previous manual production methods have been unable to keep up with the rapidly growing market demand in terms of efficiency, safety, and quality. Therefore, the robot-assisted bending system can improve production efficiency and reduce failure rates. , It is imperative to reduce labor intensity. To this end, combined with the characteristics of the processed products, the whole process from raw material extraction to workpiece positioning to robot bending to finished product off-line is fully automated, and the plate adsorption detection design and the high-precision positioning of the backstop finger of the bending machine are added. The detection and bending follow-up system greatly improves the accuracy and reliability of the entire production process, and realizes multi-variety, small-batch sheet processing according to customer requirements, and can quickly and easily complete new product commissioning, compatible with 500-2500mm range Various sheets.

System Composition

The robot-assisted bending system is mainly composed of a six-axis robot, a robot gripper, a transfer machine, a feed roller line, a discharge roller line, a bending machine, a face adjustment frame, a sheet metal positioning and centering unit, and a rear finger displacement It is composed of the detection unit, electric control system, etc.

Working Process

After the specification and quantity of the plates to be processed are sent from the operating table, the plates to be processed are automatically transported from the rear warehouse to the bottom of the transplanter. After real-time detection of the incoming material, the transplanter will automatically drop and pick up the plates and transport the plates to the roller conveyor line. , The roller conveyor line transports the plate to the plate positioning and centering unit on the robot side, and the centering unit cooperates with the roller conveyor line to realize the positioning on the plate line body. After the positioning is completed, the robot sucks the plate to the bending machine through the claw and completes the bending of the product accurately and quickly through the real-time communication between the robot and the bending machine and the product process program. After the product is bent, the robot puts the finished product into the discharge material. Roller line, and send a command to inform the finished product warehouse to put the products into the warehouse. The two robots equipped in this system can process the same product at the same time, or process different products at the same time, and can also select a product to process together according to the cutter head used by the bending machine, which improves the applicability and flexibility of the system; at the same time; The double anti-collision protection of hardware and software is set in the cross working area of the two robots, which improves the safety of the system.

• Transplanting machine

It mainly completes the picking up of each sheet from the feeding trolley in the sheet storage and placing it on the roller line body. The main structure of the transfer machine is made of structural steel. The walking mechanism is driven by a motor and a rack and pinion. The lifting mechanism is driven by a servo motor and a ball screw module. The claw part is designed as a frame-type vacuum suction cup array, and the suction cups are grouped. Drive control. The lifting mechanism sensor can accurately locate the grabbing position of the plate. The servo motor quickly moves to 2cm above the plate according to the position information of the plate, and then slowly moves down until the suction cup is completely in contact with the plate to pick up the plate, and then quickly moves up, while the walking mechanism quickly moves to the roller Above the track line, the servo motor puts the plate on the roller track line and returns to the initial position.

• Roller line and centering unit

The roller line is mainly composed of a driving mechanism, a tensioning mechanism, a workpiece positioning mechanism, and an in-position detection sensor. The line body is driven by a sprocket and chain and is adjustable by frequency conversion. The centering device is located at the end of the feeding direction of the roller line and is independent of the roller line. The main structure uses a servo motor to drive the double helix ball screw to drive the stopper to position and clamp the workpiece.

The roller line conveys the plates sent by the transplanter to the end of the line body. When the line tail sensor detects the plate, the roller line will run down to maintain the position of the running side of the roller line and notify the centering device to perform centering. , The centering unit can judge whether the positioning of the plane perpendicular to the running direction of the roller table is completed through the clamping torque of the plate. When the clamping torque reaches the set value, the centering unit is released and waits for the robot to grab it.

• Robot gripper

According to the size and process requirements of the workpiece (single-side bending, two-side bending, or four-side bending, flattening), the gripper is designed as shown in the figure. The gripper is mainly composed of a servo drive module, a precision linear guide, or a straight line. It consists of bearings, cylinders, vacuum devices, etc. The gripper can be compatible with workpieces with large differences in size through telescopic transformation. The suction cups are controlled in groups and are equipped with a check valve to prevent the suction of a single suction cup from affecting other suction cups when it leaks.

• Adjusting frame

It is mainly used to complete the flip-side suction plate or double-station collaborative processing by another slave robot to absorb the workpiece. The surface adjustment frame is designed as a tilted fixed F-shaped column structure. The table is equipped with positioning suction cups. The suction cups are controlled by groups and equipped The check valve prevents air leakage of a single suction cup from affecting the adsorption of other suction cups. When turning over and bending are required, the two exchange tables are respectively coordinated with each robot to bend; when exchange bending is required, any one of the exchange tables can be used for bending.

• Bending following system

Since the maximum size of the plate to be processed is 2500mm, small size and angular deviations may cause the bending size to be unqualified. Therefore, high-precision displacement sensors are added to the two rear finger sides of the bending machine to correct the alignment and robot gripper. The position deviation when grabbing and moving ensures accuracy when pressing and bending under the press brake. Due to the variety of processed plates, the size, bending angle, and position of each product may be different. For the situation where the bending follow-up workload is relatively large, a sheet metal follower program module has been developed, and only a few simple teachings are required. The bending follow-up can be completed to ensure the angle accuracy, and the processing size accuracy is ≤±0.15mm, and the bending angle accuracy is ≤±0.5°.

Electric Control System

The robot bending control system uses Siemens’ new generation process PLC-CPU317T2DP, which integrates logic control, motion control, and transmission parameterization functions. It completes up to 12-axis servo control through Profibus isochronous mode and IM174 module, and Through the ET200M point-to-point communication module to complete the remote sub-station expansion. The library system, robots, and on-site variable frequency drives are all connected to the PLC via Profibus to ensure the reliability and real-time nature of information transmission. The I/O control of the transplanting machine, roller line, surface adjustment frame, and plate positioning and the centering unit is connected to the Profibus Fieldbus expansion module near the station, making the wiring simpler and faster, and the execution of each station The status can be reflected in the indicator light of the station module, which brings great convenience to future maintenance and overhaul.

Main Functions of The System

The system functions mainly include automatic product identification, flexible processing, process monitoring, product accuracy control, etc. The details are as follows:

• Automatic product identification

Since the production task is issued by the Liku operating system, each time the task is executed and the plate is extracted, the product information including the size, the processing program serial number and the quantity to be processed will be sent to the main control system PLC, PLC through the Profibus bus system. According to the information transmitted by the operating system of the library, the workpiece to be processed can be automatically identified and the corresponding processing program can be called, which improves the reliability and efficiency of product processing.

• Flexible processing

At the beginning of the design, in addition to the production of 30 customized products, as long as the bending size is within the size range of 400～1000mm in width and 500～2500mm in length, all other plates can be easily expanded into the bending system. The PLC control program, touch screen, and robot bending program are all reserved for expansion interfaces to meet the possibility of customers increasing the types of processed products.

• Process monitoring

The operation and fault status of all equipment, as well as the quantity to be processed and processed quantity of the system, are displayed on the touch screen with audible and visual warnings. The running speed of the roller line, the lowering, ascending position, and ascending and descending speed of the transplanter, the clamping torque and speed of the centering unit, and the accuracy range of the finger after bending can be set through the touch screen.

• Product accuracy control

The plate centering accuracy ≤0.25mm ensures the accuracy and speed of subsequent bending; the robot gripper adopts servo synchronous control to ensure the consistency of each grasping position; the backstop finger uses a high-precision displacement sensor with a sub-meter rate of 0.001mm, and The bending dimension accuracy is ≤±0.15mm, and the bending angle accuracy is ≤±0.5°.

The system has entered the formal production stage. The entire production line only needs one operator to complete the tasks of the previous four people, and the efficiency has been doubled. The four-side bending and flattening of the most complex plate processing can be completed within 2 minutes. The operator only needs to set the specifications and quantity of the plates to be processed, and the system will automatically start production. The operator is completely free from the heavy labor in the past, and these operations are set outside the protected area. Once the operator enters the protected area, the system will automatically pause It also has sound and light alarms to avoid the occurrence of mechanical injury accidents during processing. The high-precision sensor and motion control unit ensures the dimensional and angle accuracy of the bending. The handgrips, special machines, and software specially designed for the on-site process can meet the processing needs of a wide range of multi-variety plates and facilitate the debugging of new products.

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