Seamless steel pipes, straight seam welded steel pipes, forged steel pipes, precision steel pipes, high-precision precision steel pipes, and other steel pipes will cause different degrees of curves in the longitudinal direction (i.e. length direction) of the steel pipe body during the production process, some the curve degree of the finished steel pipe can be visually seen with the naked eye. The steel pipe in question is already a substandard product. As long as it is a regular manufacturer, such products are definitely not allowed to leave the factory. Some require special instruments and equipment to measure them. Straightness. The degree of this curve is expressed in numbers, which is called the curvature of the steel pipe or the straightness of the steel pipe.
The standard of straightness of steel pipes is not very demanding in general pipelines for fluid transportation. This kind of pipes mainly requires the concentricity of the pipe mouth to facilitate the welding of the pipes. But if steel pipe is used in processing machinery and equipment, especially rubber rollers, central shafts, etc., they have higher requirements for straightness or curvature, and this is also a very important indicator for them.
Because it involves a problem of processing volume, the size of the processing volume directly affects the size of the production cost. If it cannot be processed, the steel pipe will be directly scrapped. Therefore, when purchasing seamless steel pipes or straight-seam steel pipes, manufacturers similar to those producing roller equipment pay special attention to the detection of the straightness of the steel pipes.
Among seamless steel pipes, straight seam steel pipes, and forged steel pipes, the best straightness is forged steel pipes. Because the outer diameter is machined bit by bit by processing equipment, there is generally no problem with straightness. Seamless steel pipes are second. The production process of this kind of steel pipes has a three-roller straightening machine (those with high accuracy requirements include 6-roller straighteners, 9-roller straighteners, 12-roller straighteners, and ultra-high straightness). The required pipes are processed using a computer-controlled multifunctional integrated hydraulic straightening machine imported from South Korea, which can basically meet the customer’s requirements for straightness. The worst thing is the straight steel pipe. Although the basic process also has this process, it is made of steel plates or rolled plates. If the internal stress inside the steel cannot be released well, it will also cause the steel pipe to deform after processing.
There are generally two types of calculations for straightness or curvature:
1. Local curvature of seamless steel pipe or straight-seam steel pipe: Use a ruler with a length of one meter to measure the maximum bend of the steel pipe and measure its chord height (mm), which is the local curvature value, and its unit is mm /m, expressed as 2.5mm/m. This method also applies to tube end curvature.
2. The total curvature of the full length of the steel pipe: use a thin rope to tighten from both ends of the pipe, measure the maximum chord height (mm) at the end of the steel pipe, and then convert it into a percentage of the length (in meters), which is the length of the steel pipe direction of full-length curvature. For example: if the length of the steel pipe is 10m, and the measured maximum chord height is 30mm, then the curvature of the entire length of the pipe should be 0.03÷10m×100%=0.3%. For steel pipes with relatively high straightness requirements, there is professional testing equipment to detect: The straightness of the produced steel pipes after straightening by precision machines can reach: 0.1mm/m. It is widely used in precision machinery that requires high straightness in precision instruments.
Post time: May-22-2024