Design Features and Manufacturing Technology of Concrete Pump Chassis

Concrete pump truck chassis mostly by the rotary base, legs, swing cylinder, telescopic cylinder composition. As the main force component of concrete pump truck, most of its chassis structure is designed into a box-shaped structure, which also has both oil tank and water tank , its design is reasonable or not, directly affects the reliability of concrete pump truck, machine stability Sex and the whole weight. In BAUMA CHINA2004 International Expo, many internationally renowned domestic and foreign enterprises have demonstrated their own new products or high-quality products, but also shows the chassis design and manufacturing level and style. With the rapid development of domestic construction machinery, the gap between the design and manufacturing technology of the domestic concrete pump chassis and the advanced foreign countries has become smaller and smaller. At the same time, the domestic manufacturers in the chassis structure technology and design also made considerable progress in the study, combined with many years of structural design and manufacture of pump parts work experience and many times to participate in large-scale exhibition experience, talk about China The current design and manufacture of concrete pump chassis technology, as well as with the foreign advanced level of the gap faced.
First, the characteristics of concrete pump chassis structure and the main connection

Concrete pump truck chassis structure is mainly composed of rotary base and outriggers, rotary base mainly as a get-off chassis, take on the work of the boom weight and vibration; leg role is to ensure the safety of concrete pump truck at work Sexual and stability. Since concrete pump trucks do not have the same counterweight as a crane , a large overturning moment is generated when the pump truck is extended horizontally. These overturning moments are mainly balanced by the reaction force of the outriggers. Therefore, Outriggers should have adequate structural dimensions, enough support area. At the same time turn the base and legs also have sufficient strength and fatigue resistance.

Chassis structure in accordance with the support of the leg extension is divided into: swing-type front and rear legs, telescopic front and rear legs, the former telescopic swing leg.

Front and rear oscillating legs in the form of the chassis structure, legs open around the pivot base pivot point to complete the swing, the work of good stability, simple structure, but the pump truck must have enough space on both sides , The site has been subject to certain restrictions. Due to the limitation of vehicle's overall dimensions and the stability of the whole vehicle, most of the concrete pump manufacturers at home and abroad adopt such structure.

Front and rear retractable legs, also known as XH legs, means that the legs horizontally extend and retract within the box-shaped frame of the swivel base. The legs on the left and right sides of the truck can cross in an X-shape or extend in parallel. Due to the width and width of the pump truck, the structure size and extension length of the leg are greatly restricted, the manufacturing precision of the box frame of the rotary base is relatively high, and the weight of the entire chassis structure is also relatively heavy, And the need to use built-in fuel tank, disassembly and maintenance difficulties, so the level of 37 meters and above series have few manufacturers. Only in the early stages of the development of pump truck used by most manufacturers, but because of its more flexible work space, there are still manufacturers in the use of this structure. Such as Italy CIFA 37 m pump truck, MEBC037 m pump truck.

The feature of the front telescopic swinging leg structure is that the telescopic supporting leg is connected to the front end of the rotating base and the swinging leg is connected to the rear. Due to the advantages of the former two structures, the underframe structure of the utility model has the advantages of reduced weight, The advantages of a narrow site construction, more and more manufacturers are used. In 2004, Xugong Heavy Industries was the first company in China to launch HB40, a former telescopic swinging leg structure pump. Its foreign manufacturers mainly include the following series of 42 m or less in Germany PM Company and the series of all-40 m and below in Korea.

Second, concrete pump chassis design and manufacture of the difficulties and priorities

Swing base as the chassis structure of the main connection structure, because of the complexity of the structure, that is, to ensure that the work of the dynamic strength and rigidity, but also to make the weld with the ability to withstand vibration, so how to effectively calculate the correct, come to the whole Rotating the base of the stress distribution is the design of the difficulties. Xugong Heavy vigorously carry out the study of finite element, the calculation of the rotary base has been successfully explored and made valuable design experience. At the same time, the interior of the rotary base is mostly designed as a tank and a water tank. How to avoid the occurrence of delayed cracking in the welding area is a manufacturing difficulty; and effectively preventing the leakage of the weld joint is also a major manufacturing task. Magnetic particle inspection plus kerosene leakage detection method and its ultrasonic detection method are good detection methods. What kind of economic approach, the domestic manufacturers but also according to their own equipment for comparative analysis and finalized.

Under normal circumstances, due to the connection of slewing ring and slewing reducer in the slewing area of ​​concrete pump truck chassis, in order to ensure good meshing characteristics of swivel reducer and swivel support, slewing parts are designed with greater rigidity. The design of this area All manufacturers have explored an effective solution, the widely used approach is to increase the overall rigidity of the thin ring plate reinforcement method and thick seat plate connection method.

Italy CIFA company in this area has been a good exploration, the company adopted a thick ring plate steel casting program, so that the simplified whole and seat plate weld seam down, both to ensure the high rigidity of the swing area, and Effectively solve the problem of welding deformation of the seat plate.

In order to make the anti-fatigue performance of the leg structure in the underframe stronger, new materials such as WELDOX700 and WELDOX960 are widely used in the design of the leg structure, while the main force-bearing welds are mostly processed into bevel Projection welding, enhanced weld fatigue caused by vibration characteristics, so that the degree of stress concentration to a minimum. Therefore, the main structure of the leg support force how to deal with should be taken as a key point to grasp.

The connecting area between the pivot base and the leg hinge is the most dangerous area of ​​the chassis structure. Therefore, the structural design of the pivot joint between the pivot base and the leg is another focus of the chassis structure design. Due to the calculation method, experience and experimental methods. In the chassis structure hinge point design presents a diversified and personalized trend: Italy ANTONELLI companies in the hinge point of the design tend to box-shaped structure, this design idea and manufacturing more in line with the domestic manufacturers of ideas, as Many manufacturers imitate the basket. Italy CIFA companies are using thick plate docking connection structure, because of this structure has its advantages of small folding space, there are still many manufacturers. This form of construction requires a good deal of welding in the plate and thin plate docking, pre-heat plate welding problems. Germany PM company in the handling of the hinge point of the most distinctive characteristics of a Bocaizhongzhu, diversification, the following series of 42 meters using thick-thin plate butt connection, 42 meters above the level series uses a box-shaped connection structure, showing its Design and manufacturing technology research specific, in-depth.

Third, the design optimization theory and calculation methods in the design and manufacture of applications

The calculation theory and calculation method used in the concrete pump truck design also have a great influence on the structure design of the legs and the rotating base in the chassis. Well-known enterprises have their own research institutions, the calculation of the concrete pump truck chassis theory, manufacturing processes have in-depth study, the FEM has been widely used (finite element method) and other new methods of calculation, greatly reducing the machine's weight. Many Chinese enterprises also use FEM calculation methods, but generally only check. The calculation theory used is basically based on the calculation of the crane frame in the seventies and eighties. Many local structures are designed empirically or simply. In addition, we study welding, bending and other internal stress generated by the process, the deformation is also very small, many studies just stay in theory, rarely used in product design, resulting in many of our products at the technical level, in-kind There are big differences in quality.

As the chassis structure to withstand the overturning of the vehicle and pump pumping system vibration, the local damage is mostly based on the fatigue of the local structure of the main failure. Due to the poor working conditions of the concrete pump truck, the fatigue characteristics of the under-frame structure, especially in the high-stress areas such as the hinge point, are studied deeply and the optimization research of the underframe structure will be the most important part of the design work ; To effectively reduce the welding stress, how to avoid the occurrence of delayed cracks in the welding area such as fuel tanks and water tanks will be an important issue in the manufacturing work.

Chassis structure is an important part of concrete pump truck, its appearance, weight, a direct impact on the shape and performance of the machine. The emergence of new materials, the rapid development of liquid and electricity technologies and manufacturing processes have provided huge catalysts for the development of concrete pump trucks. The unified design of the series of concrete pump truck legs provides the possibility of parametric design. In order to reduce the gap between Chinese products and advanced foreign countries, firstly, we should strengthen the optimization research on the influence of calculation theory, manufacturing technology and outrigger structure on the stability of the vehicle, and the problems that arise during the use of the product Summarize, and rise to the theoretical height; Second, continue to improve the tooling, technology, improve the technical level of staff, rough production for refined production, improve the physical quality of products; Finally, emphasis on practicality in the design of new products and Economic and creative and new ideas, when the product development to a certain extent, creativity and new ideas to better enhance the customer 's desire to buy, better reflect their own product differentiation and core competitiveness .

Fourth, the development trend of concrete pump chassis structure

From BAUMACHINA2004 International Fair and various large-scale exhibitions can also draw: The manufacturers in order to show their own technical strength, have introduced a longer cloth boom truck, 42 ​​meters above the level of series due to the structure size, vehicle height, Stability and other aspects of the impact of the manufacturers and trends are consistent, basically have adopted the structure of the front and rear swing legs connected.

Due to the application of new materials, calculation methods and experimental means more perfect, the design of the chassis structure is more dexterous, artistic, easier to manufacture.

Germany's Waitzinger company launched the perfect shape and art style "dragon" leg structure of the 36-meter truck, reflecting the perfect unity of design and art. Schweitzer launched a super-X arc support system, the integrated stabilization device to avoid the phenomenon of rebound, and saving pump construction space and weight loss both have a greater breakthrough, so that the use of functional design and made a huge leap.

The application of proprietary technologies, such as unilateral support systems, made construction on a narrow street or restricted site a reality. Such as the German SCHWING company's EASY system and Germany's PM company's OSS system, are used to control the locking device to control the swing range of the cloth rod, the view of the unilateral leg support.

With the development of electrical and mechanical fluid technology, the structure of the flexible chassis design, the pump adapted to a variety of site conditions as possible. In order to achieve product differentiation and strive for a greater selling point, the structural design of the chassis manufacturers have introduced their own characteristics, to diversify, personalized, proprietary development.

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