Anchor Frame Collar For L46C Mast

Products Specification

Type , Model: Anchor Frame Collar For L46C Mast

Size: 1.6m for 1.6M L type mast

Materials: Q345B

Process: Blasting derusting, 

Painting:  Under painting , Middle painting, Surface painting.

Our factory produce and supply almost all famous brand tower crane :Mast section, Anchor Frame, Fixing angle ,Adaptor and so on as good quality and price.

Anchor Frame Collar For L46C Mast

Tower Crane Knowledge sharing：

Analysis of piston fracture of jacking hydraulic cylinder of QTZ125 tower crane

The QTZ125 tower crane is an important type and is widely used. This paper describes a case of piston fracture of jacking hydraulic cylinder of QTZ125 tower crane, analyzes this case, and puts forward improvement measures to prevent accidents.

Anchor Frame Collar For L46C Mast

1 case overview

During the jacking process of QTZ125 tower crane in a construction site, the piston rod root of the jacking hydraulic system suddenly broke. Fortunately, it was found earlier and the jacking height was small (about 20cm apart between the standard section and the rotary support). Moreover, the operator took effective measures in time to avoid a major safety accident.

2 analysis of fracture reasons

The top of the hydraulic system in normal work, due to the top of cylinder are hinged connection, so the piston has been suffered by the axial force (moment), if not considering the influence of the piston weight and lower beam shrinkage when the.

The piston is in the process of work has been under axial pressure, it should be said that the normal stress state when the piston rod work is difficult to break.

It is understood that the oil cylinder is only used for jacking the tower crane after being randomly purchased in 1995, and has not been used for other purposes or used on other tower cranes.

It has been carried out according to technical requirements in the process of assembly and disassembly, loading and unloading, transportation and storage without any abnormal damage. Field inspection found that the cylinder is well maintained, no human damage.

Therefore, improper use or improper storage of the piston rod damage caused by the possibility of fracture is also very small. After cutting the piston, we found that:

Anchor Frame Collar For L46C Mast

(1) the entire piston is composed of three parts: the upper piston rod, the piston rod base and the intermediate connecting shaft (as shown in FIG. 2). The fracture occurs at the junction of the intermediate connecting shaft and the two parts with thinner tube wall and greater stress concentration of the tubular piston rod.

(2) the middle connecting shaft cutting about 3cm2 from the top to the bottom of the fracture cannot be separated from the tubular piston rod, and there is no thread buckle, indicating that the upper tubular piston rod and the middle connecting shaft are not threaded.

(3) the inner end face of the fracture surface (width of about 2mm) is smooth and smooth, with traces of organic processing (lathe cutting).

(4) the fracture surface has pores formed by welding and is accompanied by residual welding slag.

(5) the outside of the fracture part forms an inner depression surface, while the inside is flat, indicating that the fracture surface material is not dense.

Since the manufacturer of tower crane or oil cylinder could not be contacted, the detailed drawing and processing technology could not be obtained. It can only be speculated that the piston manufacturing process is as follows: firstly, weld the upper piston rod to the intermediate connecting shaft (the plug welding groove is reserved by machining), and then carry out machining and heat treatment.

It can be seen from the phenomenon (4) that the obvious non-compliance of welding quality is the main reason for the fracture of the piston rod, but if the design is more reasonable, it will effectively reduce the impact of welding quality and improve the degree of safety essence.

Anchor Frame Collar For L46C Mast

3. Suggestions for improvement measures

In the construction practice, the tower crane jack-up piston hydraulic system failure is rare, as one of the most important parts of tower crane, top quality of parts of hydraulic system is related to the safety of personnel and property, whether in design, manufacturing defects or the use of improper maintenance, are likely to people's lives and property caused a huge loss, the author thinks that, this case give us at least three implications:

(1) the piston rod design and processing technology of the jacking hydraulic system shall be improved. The author thinks that the simple plug welding (and in thin wall, stress concentration) is not desirable, if the internal thread connection on the basis of plug welding, post-machine processing and heat treatment effect will be better

(2) attach importance to processing quality and inspection procedures. From this case, it should be said that the piston rod of the jacking hydraulic system has obvious defects in the quality of plug welding, but it can be inspected out of the factory and put into use, if there is a major accident, the manufacturer must be culpable.

Anchor Frame Collar For L46C Mast

(3) the user should attach great importance to the key and important parts of the equipment and carry out inspection and maintenance seriously. Even the parts that have never had accidents before or the parts that are not required by the technical specifications and operating instructions cannot be ignored.

(4) when choosing a tower crane, it is necessary to select the products of the normal tower crane manufacturers, instead of focusing only on the price of the tower crane and ignoring the product quality.

Anchor Frame Collar For L46C Mast