| 摘要 |
PURPOSE:To provide a core which has an excellent shape and good initial characteristic and has the strength to side pressure and to decrease the transmission loss after extrusion of the core by working the core under the condition within 30 deg.C difference between the temp. of a waterproof intimate mixture during injecting of said mixture and the temp. of cooling water after extrusion. CONSTITUTION:The shape of a tube collapses largely from out of roundness and the transmission loss increases according to the setting of the cooling water temp. and the waterproof intimate mixture temp. and therefore the loose core is cooled within 30 deg.C difference between the temp. of the waterproof type intimate mixture and the cooling water temp. in order to improve such problem in the case of producing the waterproof type Routh core by packing the waterproof intimate mixture such as, for example, the jelly of petrolactum into the tube. The adequate cooling water temp. is <=90 deg.C in terms of cost and therefore the waterproof type intimate mixture is preferably fluidized at >=120 deg.C. On the other hand, 60 deg.C cooling water temp. is more desirable to obtain the core having the good characteristics.
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