| 摘要 |
PURPOSE:To control within the regulated value the thickness reduction and flatness caused at the small R bending time of aluminum tube in a hot compression side pressure increase bending by adding a compression bending device, side bending device and heating device to the draw bending device of a bender. CONSTITUTION:A side bending is performed by actuating a side die 5 simultaneously with performing a draw bending and compression bending by actuating a draw bending die 3 and compression die 6 thereafter by heating an aluminum pipe upto about 250 deg.C by a heater 11 prior to the bending start of the aluminum pipe 1. In this case, the compression bending load by the compression die 6 is made about 10% excess than the draw-bending load by the draw bending die 3 and about 5% excess than the draw-bending speed as well and further the side bending speed by a side die 5 is made about 105 excess than the compression bending speed. The compression heating bending can thus be performed and the thickness reduction and flatness in the small R bending of the aluminum tube 1 can be controlled.
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