Application of the hottest safety components in th

2022-08-24
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Application of safety components in new stamping lines

the old stamping production lines built in the 1980s and 1990s are basically all manual operations, and the safety of personnel and equipment cannot be fully guaranteed. In order to meet the increasing demand for production capacity, SAIC GM Wuling (SGMW) built an automatic stamping line in Liuzhou factory in 2006. The stamping line consists of 1 set of 22500knk Machine size: about 720 × five hundred × 1900mm (length × wide × It is composed of three 10000kN presses and seven automatic manipulators. The whole line is about 80m long and 20m wide, with a height of about 11m above the ground and an underground depth of about 6.5m. This is a stamping workshop with the highest safety level, and many typical safety components and systems are applied. In the production and construction of Qingdao Branch, we also introduced safety PLC and safety i/o

two handed buttons - the design concept of restricting the danger at the source

two handed buttons are mainly used to control the slider movement of the press. In the commissioning stage of the production line or when the press is operated manually, it is necessary to use two hand buttons for operation

in the initial stage of production, due to the constraints of product quality and personnel training, safety production cannot be effectively and strictly implemented. Many operators often adopt various "deceptive" means for convenience. For example, if one of the buttons is fixed and closed, only the other button is operated, and the other hand is used to transport sheet metal, there are great safety hazards in this operation mode. In order to avoid this situation, project technicians have summed up experiences and lessons from years of project operation and production, and realized that the selection of equipment is the key

based on this starting point, we chose Rockwell 800p2 when selecting the two hand button: the fixture equipped with the machine should be coated with anti rust oil for storage; Because the hydraulic oil used as the power source needs to be wiped frequently to keep clean -f2cav series products, rather than simply selecting two buttons for combination. This series of two hand buttons not only has a special shell structure design, but also adopts a safety monitoring module (also known as safety relay) to form a safe two hand control system (see Figure 2). In dangerous places, especially machines with manual feeding, stamping equipment and machines with cutting tools, the device can only operate effectively when the buttons of both hands are pressed at the same time and the time difference should not be less than 0.5s; If the time difference exceeds 0.5s, it can be used again only after both hands are released, so as to ensure that the operator's hands leave the dangerous area and avoid injury

the two normally open and two normally closed signal contacts of the two hand buttons are connected to the safety monitoring module, and the safety monitoring module judges the state of the two hand buttons. When and only when the two buttons are pressed simultaneously within 0.5s, the safety monitoring module will have an output, and the system can start the machine action; The fault of any contact can be monitored and judged; When any hand leaves the button, the safety device will immediately stop output and cut off the power source, so as to achieve the purpose of personnel protection. There will be no danger if any button works in advance or late (see Figure 3)

it is an important principle of project technical management to cut off the source of danger and avoid the risks that may be caused by any misoperation. This operation concept of two hand buttons is also applicable to inching, fine-tuning and other operation modes: press the button at the same time, and the press acts; Release at the same time, and the press stops; If one hand is suddenly released, the press stops abruptly

safety protection system MPs - the design concept of giving consideration to both safety production and maintenance

the transition from manual line to automatic line, and the leap from simple human production to high automation, is by no means overnight. At the beginning of the design of the automatic line, we introduced the MPS energy control concept in consideration of the requirements of maintaining July while safety and production. MPs is the energy monitoring and locking system. The MPS operation box on site is shown in Figure 4

first, we divide the actions involved in the press into primary actions and secondary actions. The so-called main actions are actions that may cause serious injury or death, such as the pressing action of the slider of the press and the trajectory movement of the robot. Secondary actions are actions that cause slight or no harm to people, such as the action of air valve, the action of robot vacuum sucker, etc. The purpose of safety is achieved by controlling the power supply or logic program of primary and secondary actions

after the introduction of MPS energy monitoring system, there is a significant improvement in both production beat and personnel protection. If the operator wants to enter the mold cavity area, it must prohibit the main actions. On the automatic stamping production line, it means selecting pos1 (position 1, see Figure 4) to stop the slider action, open the fence door, lock the robot action, close the waste door, and enter the area to perform maintenance tasks after the safety indicator light is on (green column light shown in Figure 4)

for example, when the production time is too long, there will be metal chips stuck to the mold in the mold cavity, even these small metal chips are not allowed by the production quality. The traditional solution is to stop the production line or the press, and the operator enters the die cavity of the press to remove the metal chips, and then restart the press to resume production. This is indeed out of safety considerations, but for the main motor of more than 400 kW, multiple restarts not only affect the service life, but also consume production time

here, we compare the production data before and after the transformation of SGMW Liuzhou automatic stamping line. Data of line stoppage in x month: 30 times/shift, 3min each time, half of the time to clean the mold cavity, about a dozen times; It is used to clean the mold cavity about 17 times per shift. If the main motor is stopped, the time required: 3 × 17=51min; After introducing MPs transformation, if the main motor is not stopped, the time required to clean the mold cavity: 1 × 17=17min; Time saved per shift: =34min; Three shifts a day, saving time: 34 × 3=102min。

in an automobile factory, one hour may mean 70 cars. Cleaning the mold cavity alone saves nearly two hours of production time, greatly improving the production capacity

if you want to choose to perform other MPs tasks, such as teaching robot, you can also choose to use pos2 (position 2), pos3 (position 3), etc. Of course, it can also be used in conjunction with other status displays, such as the slider lock display LED board. Through this intuitive safety status display, the safety of personnel entering the dangerous area is better guaranteed

safety PLC and i/o module - the design concept of introducing the most advanced safety control products

2007 was a year when GMW upgraded safety equipment with s but still a low proportion of extruder exports, which was perfectly reflected in the production line construction of Qingdao Branch. Different from Liuzhou production line, due to the introduction of safety PLC and safety i/o, the safety relay was eliminated almost overnight due to its cumbersome wiring and installation

take the safety PLC of AB as an example, the safety PLC series logix5561&5562 usually has a safety partner logix55lsp. This type of PLC can connect both safety i/o and ordinary non safety i/o, such as Siemens IP20. Different from the conventional products of AB, safety PLC is a safety controller with a specific SIL level. It uses various levels of redundant mechanisms to provide the overall safety of the system. Its security control architecture is shown in Figure 5

plc safety system includes safety i/o, which helps us get rid of the traditional way of hardwired safety relay in Liuzhou project and replace it with a more flexible controller that can realize programming functions. The Qingdao project is to distribute and configure the safety i/o by using the safety network DNET and eNet, which not only saves the wiring, installation cost and project time, but also ensures that the standard control system and human-machine interface can obtain diagnostic information at any time. The fundamental difference between the intelligent safety i/o module and the traditional i/o module is that the safety i/o can monitor the safety circuit connected to it by itself, and realize the field level diagnostic function of field equipment

the test pulse on the output end of the safety i/o can detect the internal circuit when the external input circuit is connected. Using this function, when a short circuit occurs between two inputs or between the input and the power supply (+), the safety i/o module can detect it by itself. For example, when the module has output, the test pulse can automatically disconnect 470us when each cycle is 648 MS; When a fault is detected, the output data and the output safety status indication are automatically disconnected. The safety test pulse is shown in Figure 6

the program locking function of the supporting safety system is more convenient for program management after the project is completed. After programming and equipment debugging, technicians can lock the completed program. Only those with management authority can modify and maintain the necessary program through password protection, ending the era of a repairman and a computer modifying the production program

conclusion

using safe components to ensure production safety is not only to avoid personal injury and property damage, but also to ensure the smooth progress of production and business activities, which is of positive significance to prevent and reduce production safety accidents and promote the healthy development of manufacturing industry

here, we only introduce two hand buttons, safety protection system MPs, safety PLC and i/o module. In addition, many safety components and systems are also applied in the stamping production line, such as emergency stop button, safety carpet and safety light curtain. In actual production, these safety products play an inestimable role in protecting personal and equipment safety

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