MANUFACTURE OF HEAT INSULATING PIPE,申请号JP19860008740-传众专利搜索

MANUFACTURE OF HEAT INSULATING PIPE

申请公布号：JPS62167023(A)

申请号：JP19860008740

申请日期：1986.01.17

申请公布日期：1987.07.23

申请人：

MITSUBISHI CABLE IND LTD

发明人：YAMAMOTO YUKIO;ISHIBASHI SUSUMU

分类号：B29C47/02;B29K23/00;B29K105/04;B29L23/00

主分类号：B29C47/02

摘要：PURPOSE:To improve the adhesion between a coated layer and a metal pipe and prevent only the coated layer from separating from the metal pipe by a method wherein foamed polyethylene with high extent of foaming is directly covered onto the outer peripheral surface of the metal pipe with an extruder after the metal pipe is preheated up to a predetermined temperature in advance in the manufacturing method of a heat insulating pipe. CONSTITUTION:A copper pipe 10 is preheated with a preheating mechanism up to a temperature of 50-60 deg.C. The well-known nipple 40 and die 42 are arranged radially outside the copper pipe 10 so as to feed expandable polyethylene resin 44 through a first step screw and a second step screw to an annular passage made between the nipple 40 and the die 42. The expandable polyethylene resin 44, which is extruded at about 140 deg.C onto the outer peripheral surface 10a, contacts the outer peripheral surface 10a and consequently the inner peripheral surface 46 of the expandable polyethylene resin 44 is once cooled so as to form an inner peripheral layer 48. Because the inner peripheral layer 48 solidifies quicker as compared with a bubble layer 50 at the center of the resin 44, no bubble 52 enters in the inner peripheral layer 48.