Why is the pump truck wear plate wear-resistant?

Why is the pump truck wear plate wear-resistant?

 The pump truck wear plate, also known as the wear-resistant plate, is an important part of the concrete pump truck. It gets its name because of its glasses-like shape. It is a component of the pump truck's pumping distribution valve and is connected to the concrete delivery cylinder. The moving part, the S-tube, swings from one concrete cylinder port to the other under the drive of the swing cylinder. The cutting ring swings against the wear plate along with the S-tube, forming a cutting friction force with the wear plate. Due to the rapid swing of the cutting ring, the wear plate and the concrete generate strong friction, and at the same time, it has to bear the impact force generated when cutting stones. Therefore, under normal working conditions, the wear plate must withstand impact force, shear force, and very strong friction force. The main failure forms of the wear plate are wear, fragmentation, and chipping. The wear between the wear plate and the cutting ring is abrasive wear. It first manifests as the blunting of the edges and corners of the cutting ring and the orifice of the wear plate, forming a small arc-shaped wedge mouth. As the particle size of the abrasive involved in wear increases, the wear gap also increases. When the gap reaches a certain value, it will affect the construction due to serious slurry leakage. Moreover, with the increase of the pumping height, the impact shear on the wear plate will increase, the wear will be more severe, and fragmentation and chipping are prone to occur. The concept of abrasive wear, the wear mechanism of the wear plate, and influencing factors is below.

1. Concept In the process of friction, the loss or material loss caused by the extrusion of hard particles or hard micro-convex bodies on the friction pair surface and their movement along the surface.

2. Wear mechanism

 (1) Cutting: Sharp hard abrasives cut the soft surface, and the cut-off material becomes abrasives.

(2) Fracture: The phenomenon where hard particles cause microcracks to initiate, propagate, and fracture and fall off on the material surface.

(3) Extrusion spalling: Abrasives are pressed into the friction surface under load to produce indentations, squeezing the surface of plastic materials into layered or scaly spalled debris.

(4) Fatigue: The surface material peels off due to fatigue under the cyclic contact stress generated by abrasives on the friction surface.

3. Influencing factors

 (1) The higher the material hardness and the lower the abrasive hardness, the better the wear resistance. When the abrasive hardness is between 0.7 and 1.0 of the material hardness, no abrasive wear or only slight abrasive wear occurs. In the working environment of the wear plate, the abrasives are concrete, including cement, stones, sand, etc. Their hardness is basically stable and difficult to reduce. Therefore, increasing the material hardness of the wear plate is an effective way to reduce abrasive wear.

(2) Abrasive wear is also related to the shape, size, and sharpness of the abrasives. This is not easy to control during concrete pumping, so it will not be discussed in depth.

 (3) The linear wear degree is proportional to the material surface pressure. When the pressure reaches the turning value, the linear wear degree becomes flat with the increase of pressure, which is due to the transformation of the abrasive wear form. The turning pressure values of various materials are different. During the swing of the wear plate, the swing angle and the design structure of the wear plate itself will affect the surface pressure. The friction can be reduced by optimizing the structure and designing a wear plate shape more in line with the mechanical structure.

(4) The number of repeated frictions and the relative movement speed also affect the degree of abrasive wear of the material. The wear plate swings back and forth in the concrete during work, with long working hours, high intensity, a large number of repetitions, and fast relative movement speed, so the wear is particularly serious. However, this is difficult to avoid without reducing production efficiency. From the above analysis, it can be concluded that on the premise of not increasing the workload and not reducing production efficiency, improving the material hardness, impact resistance, and surface smoothness of the wear plate is an economical and feasible measure to improve the service life of the wear plate and reduce wear.