In the 1960s, the first industrial robot in human history was born, which marked the development of human industry entered the robot era. Since then, developed countries in Europe and America have taken the research and development of industrial robots as an important way to improve their manufacturing level and scientific development level. A robot stacker is one of the typical representatives. It can imitate some actions of human hands, and automatically grab, carry and place according to a given direction and trajectory. It plays an increasingly important role in the packaging and logistics fields. Combining the manipulator with the packaging assembly line not only improves the efficiency of packaging but also reduces the expenditure of human resources so that contemporary enterprises can quickly adapt to the changing market demand and generate huge economic benefits.
 
Introduction of manipulators
 
A robot palletizer is a professional automatic handling and palletizing equipment, which can partially or completely replace manual handling and palletizing. It can not only improve the production efficiency of enterprises but also save a lot of human resources costs so that enterprises can achieve the effect of reducing staff and increasing efficiency. Therefore, it is favored by the manufacturing, chemical and logistics industries. The manipulator can be used for palletizing packaged products in bags, bottles, cans, cartons and other forms, especially in places with high temperature, high pressure, dust, noise and radioactive pollutants, and is more widely used.
 
In some simple and repetitive operations, especially heavy ones, using robots instead of people can avoid personal injury accidents caused by operational fatigue or negligence.
 
Development history and application status of the manipulator
 
1. The development history of foreign manipulators
In the 1960s, foreign countries began to study industrial robots, and manipulators appeared with the development of industrial robots. Japan and Sweden were the first countries to use industrial robot technology for stacking and transporting objects. At the end of the 1970s, Japan first applied robot technology to palletizing. In 1974, ABB Company of Sweden developed the world's first fully electronic industrial robot IRB6, which was mainly used for picking and placing workpieces and transporting materials. With the development of computer technology and artificial intelligence control technology, Germany, the United States, Japan and other countries have further studied the manipulator and launched their own products, such as the FUJI series in Japan, the ABB series in Sweden and KUKA series in Germany.
 
2. Development history and application status of domestic manipulators.
The research and application of industrial robots in China began in the 1970s when the development was slow and the level of research and application was low. After the 1980s, with the deepening of reform and opening up and the encouragement of national policies, China's industrial robot technology reached a certain level, and manipulator technology also developed rapidly. While learning from foreign advanced robot technology, we have actively researched and developed independent products, and a large number of representative enterprises have emerged. The situation that foreign robots dominate the world in our market has been broken. However, due to the late start of the research and application of manipulators in China, there is still a big gap compared with foreign countries, such as the reliability, accuracy and applicability of operation, which need to be improved. The development scale of manipulators in China is still very small, with many product specifications, and it has not formed a relatively uniform standard and specialized industry. Most of the parts and components of existing manufacturers are imported, with a long supply cycles and high costs. Therefore, we should be down-to-earth, conduct in-depth research on manipulator systems and structures, further improve related products of manipulators, and strive to improve the development level of our industrial robots.
 
3. Application of manipulator in polypropylene production
Technical index of the manipulator
Our company is using two manipulators of Shanghai Wodi Automation Equipment Co., Ltd., and their technical indicators are: (1) the snatch weight is 120kg; (2) Stacking times ≤800 times/hour (adjustable); (3) The number of motion axes is 4 axes; (4) The arm rotation angle is 330; (5) The power consumption is 4kW/h. (provided by data manufacturer)
 
The specific usage of manipulators in the company
Our company has two batch polypropylene production units, with a total of 14 polymerizers, with a production capacity of 107 kt/a. It is one of the largest batch polypropylene production units in China, and its output and main technical indicators rank among the top of similar products. The quality of polypropylene products is not only in the production process but also in the packaging process. The packaging quality of finished polypropylene is divided into product quality and product packaging quality. The application of manipulators in polypropylene production is illustrated by comparing manipulators with manual packaging.
 
Original manual packaging
Manual palletizing is 6 packs per floor on the 1st-6th floor and 4 packs per floor on the 7th floor, totaling 40 packs. Each package of products is 25kg, and one tray is just 1t. Disadvantages of manual stacking: ① The packing is solid above and below, and inclined when placed horizontally, resulting in the irregular shape of the whole stacking. ② Each side of each tray is not neat, and some material bags will protrude, resulting in untidy stacking, which is easy to fall or collapse during handling. ③ Due to the irregular stacking, the bag is broken due to the collision during forklift transportation, and the polypropylene leaks out. Broken bags not only cause waste of polypropylene granules and woven bags but also cause insufficient net content of products, which easily leads to customers' complaints about the insufficient weight of products. ④ Due to the irregular stacking, the manually packed stacking can only be placed on one floor in the warehouse, and no more products can be stacked on it, resulting in the warehouse space not being fully utilized. ⑤ Employees' high-intensity repetitive work can easily lead to fatigue, even waist sprain, fall, heatstroke and other work-related accidents.
 
Now the robot packaging
The robot palletizing situation is 5 packs per floor, total of 8 floors, and a pallet is also 1t. Advantages of robot packaging: ① As the product passes through the packaging machine, the pushing machine and the shaping machine on the packaging line, and then it is conveyed to the position of the robot by the belt, the whole package is rectangular, and the whole package is square and neat after stacking, so it is not easy to fall and collapse. ② The packet breakage rate is greatly reduced. Because the products are regular and neatly packed, the bag breaking rate is reduced from 0.47% of manual packaging to 0.15% now, which makes the damage in the transportation process reach the lowest point, and also protects the working environment, reducing the amount of polypropylene particle dust in the packaging site and warehouse. ③ The grasping efficiency of the manipulator can reach 800 packs/hour, while the efficiency of manual packaging is 220 packs/hour, which is far greater than that of manual packaging, thus improving the working efficiency of packaging posts. The following table is a comparison of the data of the mechanical packaging line and manual packaging line in our company.
 
Data comparison between the manipulator and manual packaging
 
Our company's current production capacity is 107kt/a, and the average daily output is at least 290t t. If we follow the manual packaging efficiency, we will not be able to achieve the annual production target, which shows that the robot plays an irreplaceable role in polypropylene production. ④ The manipulator has the characteristics of small floor area, high load, high efficiency, high stability, reliable performance and easy maintenance, which is conducive to the layout of production lines and increases the utilization rate of factory space.
 
Future development prospects of the manipulator
For the next research on the manipulator, we will focus on intelligent operation and networking, tap its deeper potential, make its function more powerful, and adapt to more complex working environments.
 
Intelligent operation aspect
At present, most manipulators used in various industries adopt touch-screen control mode. Although it has made great progress compared with the traditional sensor control mode, it still relies too much on people to participate in teaching, and its intelligence needs to be improved. Research and development of intelligent operation can realize the high flexibility and adaptability of robot operation to the environment, and at the same time reduce the complexity of operator participation. With the help of multi-sensor technology, the intelligent operations can realize self-teaching and self-improvement of the robotic stackers.
 
Networking aspect
Make the networked robot develop from an independent system to a group system. Manipulator is only an industrial robot used in packaging, and the future development of enterprises will promote robot technology in other production links. If these independent intelligent systems can be connected by using the network, self-judgment and mutual coordination can be realized in enterprise production, so it will be possible for operators to realize remote operation monitoring and maintenance.
 
Conclusion
Robot plays an important role in the field of automatic packaging. It can not only bear the high load but also its speed and quality are much higher than those of manual packaging, which improves the efficiency of packaging and reduces the expenditure of human resources. In today's society, if enterprises use manual production too much, it will inevitably increase the labor cost of enterprises. Chemical enterprises are more dangerous, and the more people there are, the more unsafe factors will be generated. Repeated labor for a long time is easy to cause occupational diseases and indirectly increases the burden of enterprises. It is an inevitable trend for the future development of enterprises to use mechanical automation instead of labor. With the progress of automation technology, manipulators will have a broader development prospect.