Concrete pump elbow life shortening factor

Causes of declining quality of concrete pump elbow and analysis of the main methods of attention:
1、 In pure bending, the outer tube wall of the neutral layer under the action of external force M under the action of tensile stress &1 is thinned, and the inner side is under compressive stress. Thickened by action, resultant forces N1 and N2 change the cross section of the tube. Based on this factor, the main reason for the deterioration of the concrete pump elbow is RX and SX. Therefore, in GBJ235-82, the RX value and the external thinning amount under various pressure levels have been clearly defined. The purpose is to Control the RX and SX values to ensure quality.

2、 As mentioned in the previous article, the outer side of concrete pump elbow material is pulled. The position of the inner compression neutral shaft is different from that of the concrete pump elbow method. When the top bending type (compression bending) is working, the neutral shaft is away from the outer wall. About 1/3 of the time, the neutral shaft is located at 2/3 of the outer wall during the bending (back bend) operation. Therefore, the thin-walled pipe is bent, and it is beneficial to use the rolling method.

concrete pump elbow.jpg

3、 The precision of the bent tires is also one of the factors affecting the quality of the concrete pump elbows. In the manufacture of bent tires, in addition to the specification and size requirements being controlled within a certain tolerance range, users are also required to select the corresponding bent tires according to the bending diameter when they are used.
4、 The bendability and surface corrosion of the pipe itself may also affect the quality of the concrete pump elbow. During on-site construction, operators also need to understand the material of the pipeline being processed, the processing performance, and the judgment of the surface corrosion.

5、 now provide R. (Bending Radius/Tube Outside Diameter) The relationship curve (as shown in the figure) is for reference by the user when selecting the relationship between the tube diameter and the wall thickness. This figure focuses on the effect of relative bending radius and relative wall thickness on the quality of concrete pump elbows. According to the acceptance criteria for pipeline processing, cold-formed steel pipelines are 4D for medium and low pressure and 5D for high pressure. Therefore, the design of our bent tires is R=4D (special circumstances are determined separately). Therefore, for the concrete pump elbow machines produced by our company, the relative thickness SX is mainly chosen, and it is difficult to design and manufacture special spindles. The operation is not very convenient, so generally our factory will not supply. Special circumstances can be agreed upon.

related articles:The production standard of different concrete pump pipe bend.

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