Apparatus for producing tubing, especially from material suitable for injection molding

Claim 1

In an apparatus for producing tubing from injection molding material which tubing is provided in its wall with an outwardly directed corrugation produced simultaneously with the injection molding step by means of a forming ring having alternating large and small radially displaceable individual segments which are withdrawn upon the completion of the injection molding steps inwardly toward the longitudinal axis of the apparatus, radially outer surfaces of said segments defining the inner diameter of the tubing to be molded; the improvement comprising guide means along all the flanks of the large and small segments facing each other and intercoupling said small and large segments whereby radial displacement of said small segments effects radial displacement of said large segments in the same direction and positive drive means operatively connected to said small segments, said drive means extending at an angle relative to said longitudinal axis of the apparatus, and comprising outrigger arms for radially moving said small segments, said outrigger arms extending at an angle relative to the longitudinal axis of the apparatus, said small segments having outwardly extending flanks forming an acute angle ( Beta ), said guide means comprising tapered slide guide means on said outwardly extending flanks, said large segments also having flanks with tapered slide guide means for cooperation with said guide means of the small segments, said flanks of the large segment having an included angle ( Alpha ) which is larger than the respective angle ( Beta ) of the small segments whereby all segments are included in a positive guide for their simultaneous movement radially inwardly and outwardly, a first and second disk, said segments being arranged between said disks, one of said disks having an outer diameter corresponding to the inner diameter of the tubing to be molded, collar bolts for interconnecting said disks and shoulder means for assuring a definite spacing between said disks for assuring a gliding movement of said segments between the disks, said large segments having longitudinal, radially extending apertures through which said collar bolts extend to permit a gliding movement of the segments relative to the respective collar bolt, and relative to said disks, whereby a positive driving force in the radial direction is applied to said small segment prior to the radial withdrawal of said outer surfaces which define the inner diameter of the tubing to be molded.