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With the development of science and technology in our country and the increasing demands in production, the capacity and belt speed of belt conveyors have seen significant improvements. In particular, for belt conveyors with a belt speed of V≥3.15 m/s, higher requirements are placed on the radial runout of the idlers, which must be ≤0.5 mm. If the radial runout of the idlers in a high-speed belt conveyor is too large, the high-speed rotation of the conveyor will cause the belt to oscillate. This reduces the fatigue resistance of components such as the conveyor drums, idlers, drive equipment, and frame, making these components prone to fatigue damage. In particular, the service life of the idlers is reduced, and this directly affects the overall performance of the conveyor. Therefore, it is very important to control the radial runout of the idlers during the manufacturing process. 1. Selection of pipes: The precision of the pipes used for idler rollers directly affects the radial runout of these rollers. If the ellipticity, curvature, and wall thickness variations of the pipes are not within acceptable limits, the radial runout of the resulting idler rollers will be excessive. To address this issue, our company uses high-frequency welded high-precision steel tubes for manufacturing idler rollers. Such tubes are required to have a bending degree of no more than 0.3 mm/m, an outer diameter ellipticity of no more than 0.4 mm, and a wall thickness tolerance of no more than 0.3 mm; they are thus the preferred material for manufacturing roller skins. 2. The concentricity between the outer circle and the inner hole of the stamped bearing seat, as well as the straightness of the inner hole and the outer circular end surfaces, are the main factors that affect the radial runout of idlers during their manufacturing process. If the concentricity does not meet the required specifications, then after the bearing seat is welded inside the steel tube to form an idler, it will result in an abnormal concentricity between the shaft and the surface of the roller, causing the roller’s radial runout to be outside acceptable limits ； If the straightness of the bearing housing is out of spec, after the bearing housing is installed in the steel pipe and welded, the reverse center line of the pipe will deviate from the reverse center line of the bearing housing, forming an angle; this too can cause the radial runout of the idler roller to be out of spec. To address this issue, we fix the stamped bearing seat on a 20-ton lathe and machine its outer surface as well as the opposite side of its end face. The machining procedure is as follows: first, a mandrel is machined on the lathe so that it fits tightly with the stamped bearing seat, with the maximum gap not exceeding 0.03 mm; then, the inner hole of the stamped bearing seat is inserted onto this mandrel, which is secured in place using a tailstock center, allowing the bearing seat to rotate along with the lathe’s spindle. A cutting tool is used to machine the outer surface and the opposite side of the end face of the stamped bearing seat. The dimension for machining the outer surface is D0 – 0.05 (where D is the diameter of the outer surface of the stamped bearing seat plus the fit dimension with the pipe’s shoulder). The machining of the end face continues until it is fully finished; the radial dimension for end face machining is 3 mm inward from the outer surface. The stamped bearing seats produced in this way have a concentricity of no more than 0.05 mm, and the straightness between the end face and the inner hole is no more than 0.06 mm. Additionally, the qualified rate for the radial runout of the rollers produced is 95%, which **exceeds** the standard, thereby improving the precision of roller manufacturing. 3. The roller processing step is a key and crucial process in roller manufacturing; the quality of work done in this step directly affects the quality of the rollers, particularly their radial runout. If the diameter of the end face of the tube processed in the tube processing step is too small to be inserted smoothly into the stamping bearing seat, it may cause the bearing seat to become misaligned. If the dimensions of the machining shoulder are too large, causing a large gap between the outer surface of the bearing housing and the tube shoulder, this will result in poor concentricity between the inner bore of the bearing housing and the tube surface, thereby leading to excessive radial runout of the roller. If the wall thickness difference between the end face of the processed pipe and the pipe surface does not meet the requirements, after the bearing housing is installed, both the inner hole of the bearing housing and the pipe surface will become eccentric; as a result, the radial runout of the idler roller will definitely exceed the specified limits. To address this issue, we perform accurate measurements of the steel pipe and the mold used in the special tube processing machine before each tube is processed. If the fit accuracy between the steel pipe and the mold during processing is satisfactory, the pipe can be directly processed using this mold. If the positioning dimension of the fixture obtained from the measurement is 0.1 mm larger than the outer diameter of the pipe, measures must be taken to precisely adjust the fixture. The method involves using a fixture that does not meet the requirements to position the pipe and then performing patch welding; after that, rough machining is carried out on the lathe with a remaining margin of 0.5 mm on one side. Then, the mandrel is installed on the tube bending machine; based on the measured outer diameter of the tube, the machine’s own cutting tools are used to shape the inner diameter of the mandrel’s positioning shoulder, with this diameter not exceeding the tube’s outer diameter by 0.1 mm. Next, the machining accuracy of the pipe end face is verified; it is required that the dimensions of this end face fit closely with the outer diameter of the stamped bearing seat after processing. The desired dimension for the end face is D0+0.05mm, which ensures that the bearing seat fits concentrically within the pipe end face, meeting the specified tolerance requirements. As a result, the pass rate for the radial runout of the assembled idler rollers can exceed 95%. 4. For welding the idler rollers, it is required to carefully drive the stamped bearing seat into the pipe end, and then place it on a specialized pipe welding machine for welding. It is usually quite simple to weld the bearing seat off-center, causing the outer diameter of the tube to be out of alignment with the bearing seat. The reason is that the welding process involves using nose and tail fixtures to apply pressure while rotating for welding; pressure is exerted from the tail cylinder. If this pressure is too high, it causes the bearing housing to deform and tilt, resulting in excessive radial runout of the idler rollers after assembly. Therefore, the pressure of the cylinder at the rear of the welded pipe machine should not be too high; adjusting it to 2–3.5 MPa based on the pressure exerted by the pipe is the most suitable value.