To provide a method for forming an inner face groove of a copper tube capable of manufacturing the inner face grooved pipe of which the crystal granular diameter is small and the mechanical property is homogeneous.
After hot extrusion of phosphorous deoxidized copper billets, an extruded pipe is made to a mother pipe 18 by rolling, drawing and annealing it. The mother pipe is drawn to reduce a diameter by a dice 11 and a floating plug 12. The grooves 16 are formed by a rotatable grooved plug 13 connected to the floating plug via a tie rod and form-rolling balls 15 arranged on the outer side of the mother pipe. In this case, an average coding speed of the extruded pipe to cool down to 30°C after hot extrusion is more than 5°C/sec. As the mother pipe 18 to be used for a diameter reducing process, the copper pipe of which the average crystal granular diameter is 0.01-0.03 mm, the 0.2% proof stress is 75-130 N/mm2, and elongation is in the range of 45-52% is used. The proof stress of the copper pipe is increased 2.5-3.6 times by the diameter reducing process using the dice and the floating plug.
| JP3818151 | ROLL FOR FORMING BAR STOCK OF FINNED PLATE |
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SAEKI CHIKARA
KOSEKI KIYONORI
IWAMOTO HIDEKI
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