| 摘要 |
The head box for a paper making machine joins the main distribution channel with an outlet nozzle that extends over the width of the machine. The head box has a plurality of linear, tubular flow channels extending from the distribution channel to the outlet nozzle. Just before entry into the outlet nozzle, each channel widens continuously, forming a continuous diffuser communicating into the outlet nozzle. In each tubular flow channel, a respective channel piece of reduced inside diameter is provided at or just upstream of the continuous diffuser. The entrance into the channel piece is developed as a step-like reduction in cross-section of the tubular channel, as compared with the cross-section of the tubular channel just upstream. The channel piece with the reduced cross-section may be defined at the entrance end of one part of the channel that is installed into a wider diameter second part of the channel that is immediately upstream, may be located at or just upstream of the continuous diffuser at the end of the tubular flow channel, or may be a bushing inserted into the tubular flow channel upstream of the continuous diffuser at the end thereof. Furthermore, a plurality of channel pieces, each with a reduced cross-section entrance, may be inserted in series in the main tubular channel. |
