Analysis on the design of automation system for continuous press line
The new energy automobile industry has experienced considerable development in recent years, and new forces in vehicle manufacturing have continued to emerge. The Ideal Automobile Jiangsu ECG project is the company’s first production base and an important benchmark project for Internet vehicle manufacturing. In the first phase of the project, an automated stamping line is planned for the stamping workshop to provide the factory with body panels and large structural parts. The press line consists of 5 Jinfeng presses (2400t+1200t+1000t×3), and the automation system is provided by Shanghai ABB Engineering Co., Ltd. The production line is a continuous stamping line, which requires the production of aluminum and steel stamping parts. During production, it does not stop at the top dead center, and the robot and the press slide are positioned correspondingly and run synchronously.
The stamping line automation system consists of a destacking trolley, automatic splitting device, automatic detection device for material height/end material/double material, sheet material conveying/transition/line end conveyor belt, washing machine, oiling machine, centering device, robot and grasping Take the structure (end picker), control system and other components. Through this project, this article briefly describes the requirements of the continuous press line for the press, and analyzes the problems that need to be considered in the planning and design of some automation equipment.
Requirements for the press
As the first continuous stamping line in China that uses robots for loading and unloading, in addition to increasing the power of the main motor to meet the stamping energy requirements at low speeds, the press also needs to meet the following requirements.
⑴For the press with a work surface of 5000mm×2600mm, in order to provide enough space for the loading and unloading robot to pick and place parts, the stroke of the multi-link press at the beginning of the line is required to be ≥1400mm, and the stroke of the rest of the press is ≥1200mm.
⑵The press needs to increase the Simotion synchronization controller. The synchronous controller needs to keep the operating speed of the press and the phase difference between the presses constant, and the synchronization accuracy is controlled within ±5 degrees. The running speed of the entire line and the phase difference between the presses are adjustable, which are set by the automatic loading and unloading equipment .
(3) The press synchronization controller Simotion communicates with the automation complete line controller in real time through Profinet to achieve the following data transmission and format requirements. Simotion sends the virtual axis angle and speed to the automation controller, as well as the real-time angle and speed of the press. The speed signal sent by Simotion to the automation controller must be accurate to three decimal places, and the position signal of the press sent by Simotion to the ABB system must be accurate to One digit after the decimal point, Simotion also receives the data sent by the automation controller.
⑷ During an emergency stop, the press slider will have a certain braking distance. In order to avoid collision between the robot and the press slider, a certain safety distance must be left between the robot and the press slider. In order to increase the speed of the entire line, it is necessary to minimize the safety margin between the loading and unloading robot and the press slider. The general requirements for the brake angle of the press are shown in Table 1.
⑸The PLC of the press communicates with the complete line controller of the automation through Profinet (the same way as the intermittent line communication, the exchange of information is increased).
⑹Automation equipment needs to separately obtain the position information of the press slider, so the press needs to reserve a slider position encoder output shaft for automatic installation of the encoder.
Table 1 Braking angle requirements of the press
⑺ The press needs to have two production modes, intermittent and continuous, and easy to switch.
Automatic splitting system
The automatic splitting system (Figure 1) is composed of two elevating destacking trolleys and an automatic splitting device, which cooperate with the destacking robot to automatically call when stacking materials are switched one by one.
⑷The destacking trolley is equipped with a final material detection device on the table. When the pallet is empty, the robot automatically turns to another destacking trolley for destacking. At this time, the system sends out a sound and light alarm to remind the operator to replace the material. The operator presses the button to notify the PLC, and the destacking trolley automatically moves out of the work area to the designated loading position. The operator unloads the empty pallet and loads the pallet with sheets. When the destacking trolley passes through the grating, the grating fails.
⑸ Each destacking station is equipped with a set of stacking material splitting device (Figure 2), which is separately placed on the feeding belt conveyor and sent to the press for stamping.
⑴The destacking trolley of this project needs to meet the production of the largest sheet material, the table size is 4500mm×2400mm, and the load is 12t. Two destacking trolleys are respectively arranged on two parallel tracks, driven by a motor, and the speed is controlled by a frequency converter, and move between the loading station and the destacking station. Two trolleys work alternately. One trolley will automatically return to the loading station after destacking, and then back to the destacking station after manual loading. The destacking trolley must be equipped with a stop limit switch in place to prevent the worktable from moving when it is in place.
⑵The stacking trolley is equipped with a stacking lifting mechanism, which adopts a scissor support structure. The height of the stack on the trolley is detected by the photoelectric sensor. During the destacking process, when the sensor senses that the height of the stack is reduced, the lifting mechanism automatically raises the stack to the working height of the stack.
⑶ The platform of the destacking trolley needs to be equipped with a positioning device. The positioning device can be quickly removed and installed in other positions. The positioning device and positioning hole will be designed according to the specifications of all the racks of the production line to adapt to the positioning of all pallets. In addition, for stacks without pallets, the destacking trolley is equipped with a laser-assisted positioning device. For each different part, the system will save the laser positioning parameters, and the layout is the first 8 and the rear 8, and the splitting device is installed on the guide rail. The whole is fixed on the ground frame and driven by their respective cylinders. When feeding, the splitting head returns to the moving range of the destacking trolley, and will not interfere with the moving destacking trolley. When the destacking trolley completes loading and reaches the destacking position, the cylinder drives the magnetic splitting head to move toward the stack until it is close to the stack.
Figure 1 Automatic splitting system
Figure 2 Stacking and splitting device
⑹The splitting head can automatically adjust the angle to fit the stack material according to the shape of the sheet, and the angle adjustment range is 0°～30°. For ferromagnetic sheets, according to the principle of magnetic homogeneity repulsion, strong magnets are used for splitting. The strong magnets are installed inside the splitting device and have the function of pneumatic separation; for non-ferromagnetic sheets (such as aluminum plates, 304 stainless steel, etc.), use Air knife blowing and splitting method. Air knives are installed on both sides of the splitting head. When using air knife splitting, there is a greater demand for air pressure and flow. Pressure boosting equipment and air storage devices are required. Generally, the air pressure is ≥0.8MPa, The capacity of the gas storage device needs to be calculated based on the number of air knives, working rhythm, and blowing time. For example, in this project, the calculation result requires a gas storage tank capacity of 1.5m3. The specific parameters are shown in Table 2.
Table 2 Calculation of gas tank capacity
Destacking end picker
The tool used by the depalletizing robot to grab the sheet is the depalletizing end picker. The traditional press line depalletizing robots are only equipped with a set of universal depalletizing end pickers. The product blanks of this project are complex and diverse, and one set of end pickers is difficult. Meet the production of all products.
⑴In the design of the scheme, 3 sets of destacking end pickers are adopted, which are connected to the robot through a quick change device (Figure 3), and the end pickers are hung on the steel structure around the robot when not in use. When selecting the quick-change device, the load must be calculated. The heaviest sheet material of this project is 40kg, the destacking end picker is 50kg, and the quick-change device of model SWS-110 is selected, and the maximum load is 150kg.
Figure 3 Quick change device
⑵Equipment (depalletizing trolley, waste box, feeding belt conveyor) is arranged on the front, rear, left, and right sides of the destacking robot. In terms of the spatial arrangement of the automatic end picker replacement (ATC) bracket, the ATC bracket is considered in this design In the air, it is installed on a closed steel structure of the entire line. This design meets the needs of ATC and saves space, as shown in Figure 4.
Figure 4 ATC layout of the depalletizing robot
⑶In order to ensure that the 3 sets of end pickers can cover the production of all products, each suction cup of the end picker needs to be controlled separately, and each end picker is equipped with a valve island to control a suction cup. Choose the appropriate one according to the shape of the product during debugging. The end picker and the corresponding suction cup are stored in the product plan. In the later production switch, you only need to enter the product number to be produced, and the system will send the end picker and suction cup selection information to the robot according to the plan. The robot will automatically grab the end picker of the next product, and the end picker valve island will automatically follow the plan. Select the suction cup to be used. This design expands the product range of the production line and makes it easier to switch in later production.