收敛段 meaning in English

constrictor
contraction section
contractor
converging portion
convvergent portion

For conventional high - speed mass production of flexible tubes , the skirt of the tube must be obtained directly by extrusion with a thickness at least six times lower , under conditions so that it is difficult or even impossible , to control the action of the blowing agent in the screw , then in the convergent zone of the extruder , so that a skirt is obtained with a expanded extruded layer with significant irregularities in thickness , which does not make it possible to provide an acceptable industrial packaging
对于软管的常规高速批量生产，必须通过将管的厚度挤压到至少为原来的六倍以下来直接得到管裙，在这样的情况下很难甚至不可能控制膨胀剂在螺杆中，然后在挤压机收敛段的运动，这样，获得的管裙具有厚度明显不规则的挤出层，其不可能提供可接受的工业包装。