| 摘要 |
The nozzle having a plurality of channels is particularly appropriate as a burner nozzle for welding apparatuses, cutting torches or heating burners. The nozzle (26') is obtained first by compression of a mixture of metal powders about mandrels used for forming the channels. The body of the nozzle is then sintered. In order to obtain smooth walls for the channels, the cross-section area is reduced after sintering, and during this reduction sizing mandrels (35, 36, 37, 38, 39) are inserted into the channels. To obtain the reduction of the cross-section area, the sintered bodies (26) are pressed through a reduction die (28) having a bore (34) comprising a reduction section (34b). During the reduction of the cross-section area, the material is pressed under the effect of the decrease of volume of the pores and is configured to the shape of the sizing mandrels (35 to 39). The manufacture with the use of powders allows to obtain an optimum shape for the channels from the point of view of the flow. The channels may be very thin. The waste ratio is substantially lower than that obtained with the manufacturing process currently used wherein the channels are obtained by boring. |
