The development of boom-type concrete pump trucks in my country began in the early 1980s. At first, it was basically the introduction of component assembly, or the introduction of technology production and the introduction of some parts through the combination of technology and trade. production mode.
In the 1950s, my country produced mechanical concrete pumps. Due to the low technical level at that time, the production batch was very small. In the early 1980s, the total number of domestic concrete pump trucks was less than 200. The boom-type concrete pump truck is even more blank. During this period, some large-scale concrete pouring projects in our country basically relied on imported equipment to a large extent.
Since the early 1980s, after more than 20 years of hard work, my country's boom-type concrete pump trucks have made great progress, and the design level and manufacturing capabilities have been greatly improved. According to statistics, there are currently more than 100 concrete pump manufacturers in my country, distributed throughout the country. However, due to the uneven technical level, production process, production capacity, etc. of each manufacturer, the product gap is also large. At present, domestic enterprises with production capacity are in the first echelon represented by Sany Heavy Industry, Zoomlion Heavy Industry, Xuzhou Heavy Machinery and Foton Heavy Machinery. In the second echelon are Liaoning Hainuo, Hubei Construction Machinery, Anhui Xingma and Shanghai Hongde. Mainly enterprises such as Li, whose output accounts for more than 90% of the entire industry.
my country's boom-type concrete pump trucks have developed rapidly in recent years. In terms of product stability and technology, although they are not as good as foreign products, they have made great progress compared with the products of the 20th century. Our products have obvious competitive advantages in terms of cost performance and after-sales service, and are more in line with the actual domestic construction conditions.
Among them, Zoomlion and Sany Heavy Industry are ahead of their peers in the research and development of boom-type concrete pump trucks. Zoomlion has formulated the "Concrete Pump Truck" standard and also developed a remote maintenance and positioning system for pump trucks. Sany Heavy Industry's concrete pump trucks are comparable to foreign brand products in terms of pumping pressure, pumping displacement, stability, reliability, etc. Its pumping machinery series products have been sold well to the Middle East, North Africa and South Asia.
It can be seen from the 123 pumping machinery patents announced by the National Patent Office that the patents obtained for domestic pumping machinery are mainly pumps, pump gates and pump controls, hydraulics, electrical appliances, etc. It shows that domestic enterprises pay more attention to research in these aspects, which is also an area in which domestic pumping machinery is relatively weak. Secondly, in terms of pump spare parts and booms, the number of patents in the past 20 years is only more than 100, including patents applied by foreign companies. This shows that Chinese companies have not invested enough in the research and development of boom pumping machinery. However, companies in my country with strong technology research and development capabilities, such as Sany Heavy Industry and Zoomlion, are increasing their research and development efforts and have achieved gratifying results.
Each major component of the boom-type concrete pump truck is leading the way
Due to the late start of domestic boom-type concrete pump trucks, in the past two years, domestic companies have strengthened the introduction of technology and Quality control, design and development of boom-type concrete pump trucks with independent intellectual property rights, technological innovation has become a booster for the development of domestic boom-type concrete pump trucks. The technological development trends of major components also represent the development direction of domestic boom-type concrete pump trucks
The chassis is diversified
The chassis engine is a boom-type concrete pump truck Provide power for work and driving. Therefore, the performance of the chassis engine directly affects the performance of the boom concrete pump truck. At present, the commonly used boom-type concrete pump trucks in China are Volvo, Mercedes-Benz, and Isuzu chassis. In 2005, boom-type concrete pump trucks using domestic chassis were launched on the market. As the domestic boom-type concrete pump truck market matures, the profit margin of the entire vehicle continues to decline. In order to adapt to the different needs of users, boom-type concrete pump trucks using domestic chassis and imported chassis will occupy their own place in the market. .
The chassis used in domestic boom-type concrete pump trucks is almost all imported. Among them, Isuzu chassis has mature technology, complete domestic services, and relatively cheap prices; Volvo and Mercedes-Benz chassis have luxurious appearance, comfortable driving, high degree of automation, and use diesel electronic injection technology to achieve low fuel consumption. At present, the engines used in the chassis of domestic boom-type concrete pump trucks all meet Euro II or above standards and can meet the environmental protection requirements of large and medium-sized cities.
Structural parts are more applicable
The operation of boom-type concrete pump trucks is often limited by the upper space, which requires the lowest top height when the boom is unfolded, and the boom with less than 4 sections is folded Generally a single R or Z shape is used. Due to space constraints, booms with more than 5 sections generally use the RZ combination folding type to realize the expansion and contraction of the boom. The applicability, maneuverability and flexibility are enhanced, especially in tunnels and indoor construction, and the efficiency is significantly improved. Initially, the length of domestically produced booms was mostly 37 m, and has become longer and longer in the past two years. In the next few years, as demand continues to increase, concrete pump trucks with longer booms will enter the market. The outrigger operations of boom-type concrete pump trucks are often limited by site space, especially for large-scale boom-type concrete pump trucks. Therefore, each manufacturer has to combine its own experience to find solutions. Therefore, the design of boom-type concrete pump truck legs shows personalized and diversified characteristics. At present, most of the products on the market are double swing and X-shaped legs.
Longer cloth boom and more flexible leg structure are the main trends in the development of boom-type concrete pump trucks. The mixed use of multiple folding methods makes the boom design more flexible and lighter. . The form of outriggers is also becoming more and more flexible, and the widespread use of single-sided outriggers enables boom-type concrete pump trucks to adapt to different construction site conditions.
The central pumping system has higher pressure and larger delivery volume
Higher pressure and larger delivery volume will become the development trend of the central pumping system of domestic boom-type concrete pump trucks in the future. . In the early days of the design of domestic boom-type concrete pump trucks, the concrete delivery cylinder diameter was about 200 mm, and the output displacement was mostly below 100 m3/h. Since 2004, the concrete delivery cylinder with a bore diameter of 200 mm has been withdrawn from the pump truck product, and is only available in It is used in towed concrete pump products. At present, the most common conveying cylinder diameter on the market is 230 mm, the stroke is 2100 mm, or even longer, and the output displacement is more than 120 m3/h. As the arm of the boom-type concrete pump truck becomes higher and higher, the vehicle model becomes larger and larger, and the bore of the delivery cylinder becomes larger and larger. The bore of the domestically used concrete pump truck has reached 260 mm, and the concrete output displacement is also larger. However, From the perspective of the overall configuration of the whole machine, due to the limitations of the height of the whole machine and the width of the frame, the application of larger diameter concrete delivery cylinders is greatly restricted in the boom-type concrete pump truck. At the same time, the larger the bore diameter of the concrete conveying cylinder, the greater the output displacement, and the greater the chassis engine power required. When the whole machine works with large displacement, the vibration caused by the boom will also be greater. Therefore, if a large-bore boom-type concrete pump truck wants to replace the general-purpose cylinder with a bore of 230 mm, a lot of work will have to be done and a long distance will need to be traveled. Source: Examination University
Due to the increasingly higher requirements on project progress, more and more projects require pumping displacement of 80 to 120 m3/h. Large displacement will become the boom type in the future. The development direction of concrete pump trucks. Additionally, the pumping pressure is getting higher and higher. Before 1971, most concrete outlet pressures did not exceed 2.94 MPa, and later increased to 5.88 to 8.38 MPa. Now they have reached 22 MPa, and there is a trend of continuing to increase.
The hydraulic system is developing towards integration.
The hydraulic system is the core part of the boom concrete pump truck. The quality of the hydraulic system will directly affect the performance and efficiency of the main engine. The hydraulic systems of domestic boom-type concrete pump trucks are mostly designed with imported technology. There are two types of control circuits, one is a closed hydraulic system circuit, represented by Xuzhou Heavy Industry, and the other is an open hydraulic system circuit, represented by Sany Heavy Industry as representative. Open circuits and closed circuits each have their own advantages and disadvantages. The closed circuit has small reversing impact, low heat generation, and simple structure; while the most prominent feature of the open circuit is that it can easily control the displacement of the pump according to the load, especially When pumping over short distances, the pumping volume is large and the engine power can be fully utilized. After years of experimental verification, these two hydraulic circuits are relatively mature in the application of boom-type concrete pump trucks. They each have their own characteristics in realizing various functions. Technically, there is no question of who is superior and who is inferior. There are only certain differences in the selection of hydraulic components.
Boom-type concrete pump trucks generally adopt open systems and constant power control. Especially for large-flow pumps, open systems have many advantages such as low oil temperature, high reliability, and easy maintenance. At the same time, full hydraulic control technology and computer control technology have made breakthrough progress.
For example, the fully hydraulic commutation and computer closed-loop control technology of Sany Heavy Industry products have been widely used.