| 摘要 |
1498545 Moulding double walled hose G GILEAD 25 Feb 1976 [25 Feb 1975] 15292/77 Divided out of 1498544 Addition to 1431118 Heading B5A [Also in Divisions A1 and F2] A drip or trickle irrigation hose comprises two concentric plastic tubes whose confronting surfaces are fused together over part of their area so as to define fluid passageways between the parts of their areas which are not fused. The interior of the hose communicates with the exterior through the fluid passageways via axially spaced openings provided in the tube walls. The hoses of Figs. 1-3 are made by extrusion of one tube over the other, the tubes being subsequently fused in the linear moulding path of a continuous moulding machine by bringing together around the hose, a pair of mould halves having inwardly directed projections corresponding to the portions to be fused; the hose elements and/or the mould halves being at an elevated temperature. The hose shown in Fig. 5 is made by bringing mould halves together around the inner tube to form the passageway 26, extruding an outer tube 22 on to it, and fusing the tubes at their points of contact. The openings in the tube walls preferably comprise slits 20, 28. |
