Windable flexible shaft capable of withstanding high tractive forces and torsional stresses and process for manufacturing the same

Claim 2

Process for manufacturing a windable flexible shaft including the following successively performed operations: placing a first anchoring layer of elastomeric or thermoplastic material on a flexible inner core, wrapping under slight tension a first armoring layer on the first anchoring layer, said first armoring layer being formed of helical windings of wire or cables, covering said first armoring layer by winding under tension a first strip of small thickness constituting a thin hooping and separating layer, and subjecting the whole assembly to a first thermal treatment providing for the inlaying of said first armoring layer into said first anchoring layer by softening of the latter combined with said tension applied to said armoring layer, said thermal treatment being performed with simultaneous application of a longitudinal traction to said flexible shaft to prevent the formation of sinuousities in the wires or cables of the armoring layer during reduction in the diameter of the armoring layer as a consequence of penetration of the armoring layer into the anchoring layer during the thermal treatment operation, the material selected for said first strip being capable of withstanding said thermal treatment without flowing and adhering to adjacent structures and of permanently shrinking to increase the hooping action under the conditions of said thermal treatment such that said first strip is prevented from being integrally formed with said first anchoring layer during the thermal treatment operation.

Claim 3

Process according to claim 1, wherein said thermal treatment operation consists in applying to said whole assembly and during a predetermined interval of time a temperature comprised between 100*C to 300*C in accordance with the nature of the materials constituting said anchoring layer and said hooping and separating layer.

Claim 4

Process according to claim 1, wherein said flexible inner core is a tubular member and is subjected to a preliminary thermal treatment so as to prevent a deformation of said core when said whole assembly is subjected to said thermal treatment.

Claim 5

Process according to claim 1, further comprising the following operations following said first thermal treatment operation: placing a second anchoring layer of elastomeric or thermoplastic material on said first strip, wrapping under slight tension a second armoring layer on the second anchoring layer, said second anchoring layer being formed of helical windings of wire or cables, covering said second armoring layer by winding under tension a second strip of small thickness constituting a thin hooping and separating layer, and subjecting the whole assembly to a second thermal treatment providing for the inlaying of said second armoring layer into said second anchoring layer by softening of the latter combined with said tension applied to said second armoring layer, said second thermal treatment being performed with simultaneous application of a longitudinal traction to said flexible shaft to prevent the formation of sinuousities in the wires or cables of the second armoring layer during reduction in the diameter of the second armoring layer as a consequence of penetration of the second armoring layer into the second anchoring layer during the second thermal treatment operation, the material selected for said second strip being capable of withstanding said thermal treatment without flowing and adhering to adjacent structures and of permanently shrinking to increase the hooping action under the conditions of said second thermal treatment such that said second strip is prevented from being integrally formed with said second anchoring layer during the second thermal treatment operation.

Claim 6

Process according to claim 4, wherein said thermal treatments consist in applying to said whole assembly and during predetermined intervals of time a temperature comprised between 100*C. to 300*C. in accorDance with the nature of the materials constituting said anchoring layers and said hooping and separating layers.

Claim 7

Process according to claim 4, wherein said flexible inner core is a tubular member and is subjected to a preliminary thermal treatment so as to prevent a deformation of said core when said whole assembly is subjected to said first and second thermal treatments.

Claim 8

Process according to claim 4, further comprising the following operations following said second thermal treatment: placing a third anchoring layer of elastomeric or thermoplastic material on said second strip, wrapping under slight tension a third armoring layer on the third anchoring layer, said third armoring layer being formed of a helical winding of wire or cables, covering said third armoring layer by winding under tension a third strip of small thickness constituting a thin hooping and separating layer, covering said third strip with a coating having thermal plastic characteristics comparable to said third anchoring layer, and subjecting the whole assembly to a third thermal treatment providing for the inlaying of said third armoring layer into said third anchoring layer by softening of the latter combined with said tension applied to said third armoring layer, said third thermal treatment being performed with simultaneous application of a longitudinal traction to said flexible shaft to prevent the formation of sinuousities in the wires or cables of the third armoring layer during reduction in the diameter of the third armoring layer as a consequence of penetration of the third armoring layer into the third anchoring layer during the third thermal treatment operation, said third strip being discontinuous over its surface and said coating being flowable during said third thermal treatment whereby said coating is integrally formed with said third anchoring layer during the third thermal treatment.

Claim 9

A process for manufacturing a flexible shaft which includes wrapping around a flexible core at least two armoring layers of helical windings each embedded in an elastomeric or plastic material to be cured through a thermal treatment, this process comprising the successive steps of wrapping a first of said armoring layers embedded in said material around the flexible core, wrapping a thin separating layer around said first armoring layer, wrapping the second of said armoring layers embedded in said material around said separating layer, and subjecting the so-constituted assembly to said thermal treatment for curing said elastomeric material, said separating layer being made of a material capable of withstanding said thermal treatment without flowing and adhering to adjacent structures so as to prevent adherence between said two armoring layers during said thermal treatment and substantially without expanding so that said separating layer maintains a permanent hooping action on said first armoring layer during and after said thermal treatment.

Claim 10

A process for manufacturing a flexible shaft which includes wrapping around a flexible core at least two armoring layers of helical windings each embedded in an elastomeric or plastic material to be cured through a thermal treatment, this process comprising the successive steps of wrapping a first of said armoring layers embedded in said material around the flexible core, wrapping a thin separating layer around said first armoring layer, wrapping the second of said armoring layers embedded in said material around said separating layer, and subjecting the so-constituted assembly to said thermal treatment for curing said elastomeric material, said separating layer being made of a material capable of withstanding said thermal treatment without flowing and adhering to adjacent structures so as to prevent adherence between said two armoring layers during said thermal treatment and substantially without expanding so that said separating layer maintains a permanent hooping action on said first armoring layer during and after said thermal treatment.

Claim 11

Process according to claim 1, wherein the covering of said first armoring layer by winding under tension the first strip of small thickness includes positioning said first strip so as to substantially cover all of the outwardly facing surface area of said first armoring layer.

Claim 12

Process according to claim 4, wherein the covering of said first armoring layer by winding under tension the first strip of small thickness includes positioning said first strip so as to substantially cover all of the outwardly facing surface area of said first armoring layer and wherein the material of said first strip is capable of withstanding said second thermal treatment without flowing and adhering to adjacent structures, whereby said first armoring layer is prevented from being integrally formed with said second armoring layer during said second thermal treatment operation by said first strip.

Claim 13

Process according to claim 7, wherein the covering of said first armoring layer by winding under tension the first strip of small thickness inclUdes positioning said first strip so as to substantially cover all of the outwardly facing surface area of said first armoring layer, wherein the covering of said second armoring layer by winding under tension the second strip of small thickness includes positioning said second strip so as to substantially cover all of the outwardly facing surface area of said second armoring layer, and wherein said first and second strips are capable of withstanding said first, second and third thermal treatments without flowing and adhering to adjacent structures, whereby said first armoring layer is prevented from being integrally formed with said second armoring layer and said second armoring layer is prevented from being integrally formed with said third armoring layer during said thermal operation by said strips.