Magnetorheological fluid-assisted tube expansion and compression forming device and processing technique, and relates to the technical field of tube high-pressure forming

Abstract

The invention discloses a magnetorheological fluid-assisted tube expansion and compression forming device and a processing technique, and relates to the technical field of tube high-pressure forming.The device comprises a casing film of an annular structure, pressing dies, electromagnetic devices, an initial tube blank and diamagnetic fluid filling tubes filled with magnetorheological fluid; thepressing dies are embedded at the two ends of the casing film; the end ports of the outer sides of all the pressing dies are each provided with the electromagnetic device; the initial tube blank is embedded in the pressing dies; and the diamagnetic fluid filling tubes are embedded in the two ends of the initial tube blank correspondingly. The areas of the two end ports of the initial tube blanks each internally forms a solid-like self-sealing plug under the action of magnetorheological fluid and a magnetic field, and the sealing problem of existing internal high-pressure forming technologies is solved; and through the diamagnetism of the diamagnetic fluid filling tubes, in the expansion process, liquid is continuously charged into an inner cavity of the initial tube blank, internal high pressure is formed, an overflow passage is formed in the pressure-maintaining step in the tube forming process, and the effects that fluid is charged for expansion at first and then forming pressing iscarried out under constant pressure support condition can be achieved.

Description

technical field [0001] The invention relates to the technical field of high-pressure forming of pipes, in particular to a device and process method for expansion and compression forming of pipe fittings assisted by magneto-rheological grease. Background technique [0002] In today's society, energy saving, emission reduction and environmental protection have always been the goals pursued by the society. This trend is particularly evident in the recent rapid development of the aerospace and automobile manufacturing industries. The requirements for lightweight parts, high precision, and low consumption have received more and more attention. In order to adapt to this development trend, the internal pressure forming technology of pipes has been widely used and developed rapidly. Compared with the traditional forming technology, the internal high pressure forming technology can control the dimensional accuracy of the parts more accurately, and it is more convenient to cooperate ...

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Problems solved by technology

Problems in the prior art: 1. If the inner cavity of the bulging area of ​​the target formed pipe fitting is large, the liquid volume initially filled into the tube blank is difficult to meet the bulging requirements of the pipe fitting (the volume of the magnetorheological fluid after solidification is basically no change), and the existing technology cannot continue to supplement the force transmission medium in the bulging, so the existing technology is limited in the bulging ratio (bulging ratio = maximum cross-sectional circumference of the tube bulging / initial section circumference of the tube blank ) large pipe fittings, or the application of large deformation pipe fittings such as long-axis special-shaped pipe fittings; 2. The core of the existing process is to use magnetorheological technology to convert the force transmission liquid into a solid state, and overcome the difficulty of high-pressure liquid sealing Therefore, the pressure head can be used to directly load the medium to obtain the high pressure inside the tube blank

However, the existing technology completely solidifies the liquid in the lumen, and does not have the functions of replenishing and draining, so it is difficult to achieve precise processing of complex pipe fittings

4. The medium used in the prior art is magnetorheological fluid, which has weak curing shear resistance and anti-settling ability, so the sealing effect on the pipe end is poor

Therefore, the medium loading method of the existing technology is only suitable for the forming of pipes with a short force transmission path, such as straight-through pipes with a small height-to-diameter ratio. The loading method of the process is difficult to obtain a large internal pressure in the deformation zone, and it is difficult to bulge the tube blank to the target shape

The conversion of liquid into solid state is a requirement for easy sealing, and the change of force transmission performance after solidification makes loading control inconvenient. This is a pair of contradictory problems. Therefore, the existing technology is used for non-straight pipes with large height and diameter or curved axes. There are technical bottlenecks in the preparation

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