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Market Application of Continuous Automatic Press Line

    Current situation and comparison of automotive stamping line market
    With the maturity and expansion of the Chinese automobile market, the automobile industry is developing rapidly. The shortened model development cycle and accelerated model iteration have directly prompted automobile manufacturers to improve traditional production technology and increase production efficiency. The use of information technology to promote industrial transformation is an inevitable trend in the development of modern automobile manufacturing. Among the four major production processes of stamping (stamping), welding (welding), coating (painting), and general (final assembly) in automobile manufacturing, the stamping process directly affects the production efficiency of the entire four major processes.
    As the main equipment of the stamping workshop, the stamping production line directly affects the production efficiency of the stamping workshop. According to statistics, in stamping production, only less than 20% of the time is actually used for sheet metal stamping, and the remaining time is mainly used for sheet metal handling and preparation. After nearly a decade of golden development, mainstream domestic automobile manufacturers have basically completed the transition from manual stamping lines to automated stamping lines. Manual stamping production lines that rely solely on human handling have been eliminated or transformed into robots/manipulators. Automated stamping line.
    Figure 1 Manual stamping line and automated stamping line provided by Yizhong
    The transformation from manual lines to automated lines not only effectively improved production efficiency, but also fundamentally reduced the labor intensity of workers and greatly reduced the rate of personal safety accidents. But at present, in my country’s robot automated stamping production line, the coordination relationship between the robot and the press is mostly in an intermittent mode (ie, static coordination). In this production mode, the press slider must stop at the top dead center position and wait for the robot to complete the loading/unloading action before it can continue to move and complete a complete stroke.
    Figure 2 shows the running trajectory of the manipulator (blue and green curves at the upper part of the vertical 0 point) and the running trajectory of the press slider relative to the manipulator (the red and the lower part of the vertical 0 point are red and Purple curve), Figure 3 shows the moving track of the discontinuous operation mode under the same equipment conditions.
    Simply comparing the loading trajectory (ie blue and red curves) on the left side of the level 0 of the two figures, it can be seen that when the loading manipulator’s running trajectory is exactly the same, the relative running trajectory of the slider is in two different modes: continuous/intermittent Presents a completely different trajectory. That is, the slider keeps following the same manipulator in continuous mode, and does not stop waiting for the manipulator during the period. At this time, the production cycle is consistent with the press operation cycle, both of which are 12 times per minute.
    Figure 2 Continuous operation mode (13SPM) of a project 1# press
    Figure 3 Intermittent operation mode (10SPM) of a project 1# press
    Table 1 The actual measurement of continuous/intermittent production beats of an automated stamping line
    In contrast to the intermittent mode, in order to avoid the collision between the slider and the manipulator, the press must wait for the manipulator to safely enter the inside of the press (the red curve and straight part) before starting to move. At this time, the press production cycle is 12 times/min, but Due to the waiting phenomenon of the press running, the actual production cycle is only 10 times/min.
    In the past, the intermittent production mode was mainly used as a compromise to safe production due to the imperfect synchronization control. This result not only greatly reduces the production efficiency of stamping, but also doubles the workload of the press clutch, and even shortens the service life of the equipment.
    Principle of continuous automated press line
    In recent years, due to the actual need to further improve production efficiency and the rapid development of PLC logic programmable control technology, more and more stamping line manufacturers and integrators have begun to develop and promote automated stamping lines with continuous production mode.
    Compared with the traditional discontinuous mode production line, the continuous mode production line is equipped with a synchronization controller to improve the synchronization and coordination of each press during operation. The robot position signal extracted by the robot motion controller and the press stroke encoder, position sensor, etc. The detected press position signal is analyzed and compared to realize the feasibility of synchronous control on the hardware. On this basis, by writing the phase difference control program between the presses and the synchronization control program between the robot and the press and the safety distance interlocking program, the problem of ensuring the continuous safe movement of the press and the robot at the control level is completely solved. . See Table 1 for the actual measurement of continuous/intermittent production beats of an automated stamping line.
    Advantages of continuous automated press lines
    The continuous mode automatic stamping production line not only has the above-mentioned special advantages of high production efficiency, but also has the following characteristics due to its own control method.
    ⑴The forming process is better, which effectively improves the yield. When the press line adopts the continuous mode, the press motion beat is the production beat. For example, to ensure that the production cycle is 12 times per minute, in the intermittent mode, since the slider has to stop at the top dead center position, in this case the press motion cycle often reaches 18 times per minute. When the continuous mode is adopted, as long as the beat of the press movement reaches 12 times/minute, the production beat of 12 times/minute can be ensured, as shown in Figure 2. Under the same production cycle, the continuous mode of stamping speed is only 0.67 of the intermittent mode. The extension of the single stretch time can effectively improve the first pass rate of stamping products.
    Especially for aluminum plates with higher drawing sensitivity, limited by the allowable drawing speed, if the traditional steel plate intermittent production line is used for production, the plate may be cracked. The continuous mode effectively solves this problem because it extends the drawing time and reduces the drawing speed.
    ⑵The movement speed of the press is reduced, which improves the service life of the mold. As the moving speed of the press is reduced, the speed and impact when the upper and lower molds are in contact are correspondingly reduced, heat and wear are reduced accordingly, which can effectively improve the service life of the mold, reduce the production auxiliary time such as mold repair and trial time, and effectively improve the use of equipment effectiveness. Figure 4 shows the mold repair and trial mold time occupy most of the time in production.
    Fig. 4 Revision and trial time
    (3) The operation impact is small and the working environment is improved. Because the slider does not stop at the top dead center in the continuous mode, the press acceleration/deceleration becomes more coherent and linear, and the speed distortion is significantly reduced, which can effectively reduce the speed impact between gears and connecting rods. This not only increases the service life of key transmission components, but also fully reduces impact noise and further improves production conditions. The main transmission components in the upper beam are shown in Figure 5.
    ⑷The clutch action is reduced, and the operation is energy-saving and efficient. In the continuous mode, the slider moves continuously and does not stop, and the clutch brake does not act when the slider is at the top dead center position, which avoids the repeated engagement and disconnection of the clutch in the intermittent mode, which reduces the workload of the clutch and brake and increases its service life , It also fully reduces the release of frictional heat, and the whole machine runs more energy-saving and efficient.
    ⑸High repeat positioning accuracy, more accurate loading and unloading actions. After the continuous production mode is adopted, since the press and the robot/manipulator are in continuous motion, there is no longer mutual pause and waiting for action. Therefore, the acceleration/deceleration amplitude of the robot/manipulator responsible for handling in this operating mode is synchronously reduced and is improving At the same time, the life of the equipment makes the equipment repeat positioning accuracy higher, and the loading and unloading actions are more accurate.
    Figure 5 Main transmission components in the upper beam
    Concluding remarks
    Under the current market background of improving quality and efficiency and the policy background of energy saving and emission reduction, the continuous mode automatic stamping production line has good process formability, low requirements for sheet metal stretchability, high production efficiency, long equipment life, and movement. A series of inherent advantages such as small impact, low energy consumption and low noise. Although the introduction of hardware and software such as synchronous controllers has increased equipment procurement costs, compared with the huge economic benefits brought by the improvement of production efficiency and the reduction of labor and maintenance costs after the application of continuous mode, the increased cost of this part is also It seems trivial. Therefore, more and more automobile OEMs have chosen continuous automated stamping lines as their first choice for procurement.
    Thanks to the advancement of automation control technology and the increasingly extensive market demand, as a mainstream supplier of automated stamping production lines, Yizhong has also continuously increased the research and development of such products and updated product sequences in recent years, and has gradually obtained domestic and foreign automotive Corporate acceptance and recognition. We have reason to believe that the popularization and promotion of continuous automated stamping production lines will surely drive a new round of revolution in the automobile manufacturing industry and inject new strength into the high-quality development of the national economy.