production of bearing pipe

Manufacturing bearing rings used in pipe production. Bearing steel pipe for high dimensional precision tubing, with two, three roller Oblique Rolling Machine (see pipe Oblique Rolling), the hot-rolled production, smaller specifications required by the cold-rolled, cold-drawn production. Production of the bearing sleeve with a long steel pipe instead of a single piece of forged or round steel turning savings of metal, simplify the bearing manufacturing processes and reduce the cost of bearing.

Bearing steel into chromium bearing steel and chromium bearing steel.

Used chromium containing 1.30% to 1.65% bearing steel processing performance and pipe production characteristics are as follows:

The plasticity (perforation performance) (1). Bearing steel with good ductility and perforation performance at high temperatures, but the heating temperature is not too high, the general control around 1150 ℃ high temperature prone to grain growth (overheating), lower perforated metal performance.

(2) thermal conductivity. The bearing steel thermal conductivity slightly lower than the low-carbon steel, should be appropriate to control the temperature of the furnace tail (especially large cross section of the bearing steel billet heating).

(3) mechanical properties. Room temperature bearing steel tensile strength than those containing the C0.3% carbon steel is much higher (approximately double), and high hardness, cold working deformation is difficult to conduct spheroidizing annealing, and thus before the cold deformation, in order to improve the plasticity and reduce hardness, very little difference to the above 1000 ℃. Bearing steel, hot-rolled not have much difficulty.

(4) The deformation resistance. Bearing steel having a higher deformation resistance (see the metal deformation resistance), and the temperature sensitivity of the larger, the lower the temperature deformation resistance higher.Should take strict precautions rolled cold steel when hot rolling bearing steel pipe. Production of bearing steel pipe sometimes by sizing mill and straightening machine capacity constraints, this is because the bearing pipe wall thickness, coupled with high deformation resistance at low temperatures, so that the rolling force and straightening force increased significantly. Cold drawn bearing steel tube drawing force than for drawing carbon steel pipe about 50%.

(5) wide exhibition. Spread ratio of carbon steel of the bearing steel by about 10% to 20%, but little change within the temperature range of 885 ~ 1195 ℃, which metallic transverse deformation brought convenience to the production control.

(6) of the cooling of the bearing steel. Cooling after hot rolling should be so that the bearing pipe has a good microstructure, i.e. fine flaky pearlite No mesh carbide precipitation. Such organizations in order to create conditions for fine globular pearlite bearing steel ball annealing. Chromium bearing steel pipe hot rolled after cooling to 850 ~ 900 ℃ large number of carbide precipitation and reticular distribution, and finish rolling temperature should be controlled in more than 850 ℃, and take rapid cooling to prevent carbide precipitation. In order to achieve the rapid cooling, generally set at the roller in the cooling bed or the cooling bed input blower or spray apparatus.

Chromium bearing steel in the hot rolled condition usually available to qualified carbide network level. Similarly to prevent the tube end is heated before the cold-drawn hammerhead as well as the cooling after the hammerhead carbide precipitation.

(7) the life of the bearing steel. Industrial machinery and vehicles, such as the development of bearing high load and speed requirements, bearing life by the special attention. Before developed new bearing steel having a higher life, improving the life of the primary means of bearing steel is to improve the purity of steel, because even in the presence of small amounts of oxides, sulfides, nitrides in steel inclusions will greatly reduce the service life. This requires the smelting bearing steel should adopt various means to reduce inclusions Senior bearing steel electroslag remelting use more to get the tube to reduce inclusions.

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