Abstract: A method for making flexible, corrugated rubber tubing with internal reinforcement. An extruded sleeve of uncured rubber is slid axially onto an elongated internal forming member, after which an external forming means is placed around the assembled sleeve and used to form corrugations. The resulting product is heat-treated to set the corrugations and thus to form a flexible corrugated tube length. A helix formed of flexible, resilient wire rod is pulled through the corrugated tubing in an axial direction and simultaneously rotated in a direction to thread the helical rod into the internal helical groove in the corrugated product. At the same time, the helix is axially extended to reduce its helix diameter. When the helix has been completely extended through the corrugated tubing, it is released to that it expands radially into tight conformance with the internal helical groove.

Abstract: A method for making flexible, corrugated rubber tubing of dual composition from two extruded sleeves of uncured rubber. The inner diameter of one of the sleeves is approximately equal to the outer diameter of the other sleeve. The first sleeve is slid axially onto an elongated internal forming member, after which the second sleeve is slid over the first sleeve. An external forming means is then placed around the assembled sleeve and used to form corrugations in the pair of sleeves simultaneously, and thus intermittently interlock the two sleeves in a preshaped condition to form a unitary corrugated product. The resulting product is then heat-treated to set the corrugations and form a flexible corrugated tube length of dual composition.

Abstract: A method for making flexible tubing with helical corrugations by forming two tube lengths simultaneously while superposed one on top of another. Two extruded sleeves of different diameter formed of uncured vulcanizable stock are slid successively in superposed relation over an elongated internal forming member having a helical surface form with helical ridges and grooves. The resulting assembly is then wrapped with a flexible cord under tension such that successive turns of the cord are in spaced, generally parallel relation and in the grooves of the forming member to press adjacent portions of the two sleeves into the grooves. The sleeves are heat-treated in this wrapped condition to form two flexible, corrugated lengths of tubing simultaneously. The cord is then unwrapped from the lengths of tubing and the lengths are removed in reverse order of assembly.

Abstract: A method and apparatus for making flexible rubber tubing with axially spaced annular or helical corrugations. A sleeve of uncured vulcanizable rubber is slipped over a forming mandrel and an external form comprising a length of flexible, corrugated, axially compressible rubber tubing is positioned over the sleeve. The interior wall of the external form defines a shaping surface for use in forming embryonic corrugations in the sleeve. The sleeve is radially expanded into the shaping surface and the form and sleeve are axially compressed concertina-fashion to increase the radial dimensions of bulged portions of the sleeve between the corrugations of the external form to make embryonic corrugations in the sleeve. The sleeve and external form are then removed from the forming mandrel and the sleeve is placed on a curing mandrel with the corrugations at desired spacings, after which the sleeve is cured.

Abstract: A method and apparatus for making flexible rubber tubing with axially spaced annular or helical corrugations. A sleeve of uncured vulcanizable rubber is slipped over a forming mandrel and an external form comprising a length of flexible, corrugated, axially compressible rubber tubing is positioned over the sleeve. The interior wall of the external form defines a shaping surface for use in forming embryonic corrugations in the sleeve. The sleeve is radially expanded into the shaping surface and the form and sleeve are axially compressed concertina-fashion to increase the radial dimensions of bulged portions of the sleeve between the corrugations of the external form to make embryonic corrugations in the sleeve. The sleeve and external form are then removed from the forming mandrel and the sleeve is placed on a curing mandrel with the corrugations at desired spacings, after which the sleeve is cured.

Abstract: Apparatus for making flexible corrugated tubing of relatively large diameter and wall thickness from an extruded sleeve of uncured vulcanizable stock. The sleeve is placed on a cylindrical forming mandrel and radially expanded into an axially extensible and compressible forming member having interior edges that define successive convolutions coaxial with the mandrel and which form creases in the sleeve when it is radially expanded. The mandrel is supported at its opposite ends by two spaced forming head assemblies that surround the ends of the sleeve and which also engage the opposite ends of the forming member. When the sleeve is radially expanded to form bulges between the interior edges, the forming head assemblies are simultaneously moved in an axial direction toward one another by power means to compress the forming member and sleeve and thus, to produce embryonic corrugations in the sleeve.