Method and apparatus for the continuous production of fiber reinforced plastic pipes of variable wall thickness

Claim 2

In apparatus for the formation of shells of the type having a mandrel which both rotates and is moved axially at a uniform rate to provide two degrees of mandrel movement that are generally at right angles to each other, the improvement comprising: guide means positioned to one side of the mandrel for continuously feeding the materials which produce the shell onto the mandrel in a band having a width greater than said axial rate of mandrel movement; drive means for moving said guide means back and forth generally parallel to one of said degrees of mandrel movement and which synchronizes guide means movement with mandrel movement; and cyclic programming means causing said drive means to move said guide means in one of said degrees of movement at a rate no greater than that of said mandrel to produce one thickness of shell and then move said guide means in the opposite direction to produce a minimum thickness of shell.

Claim 3

The apparatus of claim 1 wherein said programming means causes said guide means to move in the direction of mandrel advance for another part of the cycle, and to move in the opposite direction for a final part of the cycle.

Claim 4

The apparatus of claim 1 wherein said guide means is constructed and arranged to simultaneously guide a ribbon of discontinuous fibers and continuous rovings to said mandrel, and wherein said programming means causes said guide means to move in the opposite direction to mandrel advance during a first portion of each cycle and then causes said guide means to move in the same direction and at the rate of mandrel advancement during a second portion of each cycle.

Claim 5

The apparatus of claim 1 wherein said means for moving and programming said guide means comprises a cam driven by said drive means for said mandrel, a cam follower operatively connected to said guide means to drive said guide means longitudinally of the mandrel, and said cam and cam follower being shaped to cause said guide means to move in the direction of advance of said mandrel for a first portion of cam rotation, to be stationary for a second period of cam rotation, and to move said guide means in the oppositE direction to mandrel advance for a third portion of cam rotation.

Claim 6

The apparatus of claim 1 wherein said means for programming said guide means comprises: a cam driven by said drive means for said mandrel; a cam follower operatively connected to said guide means to drive said guide means longitudinally of the mandrel, and said guide means being constructed and arranged to simultaneously guide a ribbon of discontinuous fibers and continuous rovings to said mandrel; said cam and cam follower being shaped to move said guide means relative to the surface of said mandrel and in the opposite direction to mandrel advance during a first portion of each rotation of the cam, and to move said guide means in the same direction and at the rate of mandrel advancement during a second portion of each rotation of said cam.

Claim 7

The apparatus of claim 5 wherein said guide means includes rib form feeding apparatus for feeding a form having a length equal to the circumference of said mandrel, and means starting said rib form feeding apparatus during said second portion of said cam rotation.

Claim 8

The apparatus of claim 1 wherein said means for moving and programming said guide means comprises a cam, a hydraulic servomotor having a control valve actuated by said cam, a first hydraulic displacement device actuated by said servomotor and a second hydraulic displacement device actuated by said first hydraulic displacement device with the ratio of the diameters of said first and second devices being such as to magnify the movement of said servomotor to cause said guide means to move in the direction of advance of said mandrel for a first portion of cam rotation, and to move said guide means in the opposite direction to mandrel advance for a second portion of cam rotation.

Claim 9

In shell forming apparatus comprising an axially extending mandrel which simultaneously advances in both rotational and axial directions at generally predetermined respective rates; feed means constructed and arranged to feed a band of predetermined width of fiber reinforcement materials to said mandrel to be wound thereon, said band being several times wider than said axial rate of advancement to produce a nominal overlap of materials on said mandrel that is a function of the band width divided by said axial rate of advance of said mandrel, support means for supporting said feed means for movement relative to said mandrel in one of said directions, and cyclic drive means which moves said feed means in said one of said directions a distance per mandrel revolution that is not greater than said predetermined rate of mandrel movement in said one of said directions for a period of time to produce a greater than nominal thickness of the reinforcement materials and then moves in the opposite direction for a period of time to produce less than said nominal thickness of the reinforcement materials, and whereby a section of shell having a thickness greater than nominal is produced while said feed means is moved in said one of said directions and a section of shell having a thickness less than nominal is produced while said feed means is moved in said other direction.

Claim 10

In shell forming apparatus comprising an axially extending mandrel which simultaneously advances in both rotational and axial directions at generally predetermined respective rates; feed means constructed and arranged to feed a band of predetermined width of fiber reinforcement materials to said mandrel to be wound thereon, said band being several times wider than said axial rate of advancement to produce a nominal overlap of materials on said mandrel that is a function of the band width divided by said axial rate of advance of said mandrel, support means for supporting said feed means for movement relative to said mandrel in one of said directions, and cyclic drive means which moves said feed means in said one of said directions a distance per mandrel revolution that is not greater than said predetermined rate of mandrel movement in said one of said directions for a period of time to produce a greater than nominal thickness of the reinforcement materials and then moves in the opposite direction for a period of time to produce less than said nominal thickness of the reinforcement materials, and whereby a section of shell having a thickness greater than nominal is produced while said feed means is moved in said one of said directions and a section of shell having a thickness less than nominal is produced while said feed means is moved in said other direction.

Claim 11

The apparatus of claim 8 wherein said feed means is moved in a path extending circumferentially over said mandrel.

Claim 12

In shell forming apparatus comprising an axially extending mandrel which simultaneously advances in both rotational and axial directions at generally predetermined respective rates; feed means constructed and arranged to feed a band of predetermined width of fiber reinforcement materials to said mandrel to be wound thereon, said band being several times wider than said axial rate of advancement to produce a nominal overlap of materials on said mandrel that is a function of the band width divided by said axial rate of advance of said mandrel, support means for supporting said feed means for movement axially of said mandrel, and cyclic drive means which moves said feed means a distance per mandrel revolution that is not greater than Said band width for a period of time to produce a greater than nominal thickness of the reinforcement materials and then moves in the opposite direction for a period of time to produce less than said nominal thickness of the reinforcement materials, and whereby a section of shell having a thickness greater than nominal is produced while said feed means is moved in the direction of axial mandrel advance and a section of shell having a thickness less than nominal is produced while said feed means is moved in the opposite direction.

Claim 13

In shell forming apparatus comprising an axially extending mandrel which simultaneously advances in both rotational and axial directions at generally predetermined respective rates; feed means constructed and arranged to feed a band of predetermined width of fiber reinforcement materials to said mandrel to be wound thereon, said band being several times wider than said axial rate of advancement to produce a nominal overlap of materials on said mandrel that is a function of the band width divided by said axial rate of advance of said mandrel, support means for supporting said feed means for movement axially of said mandrel, and cyclic drive means which moves said feed means a distance per mandrel revolution that is not greater than Said band width for a period of time to produce a greater than nominal thickness of the reinforcement materials and then moves in the opposite direction for a period of time to produce less than said nominal thickness of the reinforcement materials, and whereby a section of shell having a thickness greater than nominal is produced while said feed means is moved in the direction of axial mandrel advance and a section of shell having a thickness less than nominal is produced while said feed means is moved in the opposite direction.