| 摘要 |
1,221,759. Moulding pipes. HYDROTILE MACHINERY CO. 20 Nov., 1969 [22 July, 1969], No. 56935/69. Heading B5A. A vertical pipe casting machine in which a rotary packer head 28 is drawn upwardly and axially through a mould 13 whereby concrete fed on to the head by a conveyer 19 is spread radially by vanes 33 and formed into a pipe includes means to control the concrete feed to maintain the level of concrete above the head substantially constant. In Fig. 2 a probe 44 for sensing the concrete level is located in an electrical sensing circuit comprising a control unit 49 and a normally closed limit switch 48. The probe is adjustably attached to a tube 26 attached to the head, and when the concrete contacts the probe the control unit 49 operates to slow or stop the feed conveyer motor 42. The switch 48 is operated to stop the motor when the head reaches the top of the mould. In a modification the conveyer is driven by an hydraulic motor supplied with pressure fluid from a pump via two solenoid operated valves operated by the control unit whereby one or both of the valves are operated depending on the concrete level to stop or slow the conveyer motor. Alternatively instead of a probe the sensing unit comprises an air pressure chamber vented by a valve in response to the concrete level, and an electro-pneumatic transducer signals the control unit in response to the air pressure in the chamber. The sensing unit may comprise an ultra-sonic signal transducer which senses the concrete level with ultra-sonic signals, the control unit being operated by such signals; alternatively the sensing unit comprises a radar unit sensing the concrete level with electromagnetic signals which effect the operation of the control unit. |
