Method for making fiber reinforced resin tank forming mandrel

Claim 1

A method of making a mandrel for forming a fiber reinforced resin tank structure, said method being readily adapted for making tank structures of larger or smaller diameters, where the tank structure being made has a cylindrical configuration of a preselected diameter, circumference and degree of curvature, said method comprising: a. providing a plurality of substantially planar forming sheets, each of which is readily bendable into a curve about a vertical axis, each of said sheets having a predetermined lateral dimension, the total of which dimensions equals the circumference of the tank structure at the inner surface thereof; b. selecting a plurality of rigid forming segments for said forming sheets, each of which selected segments has an arcuate forming edge surface having a degree of curvature equal to that of the tank, and a length substantially equal to the width dimension of its related sheet, c. forming each of said sheets into a substantially rigid arcuate forming section by curving each of the sheets from its planar configuration to conform the sheet against the forming edge surfaces of at least two of said segments, and securing each of said sheets with respect to its related segments, with each sheet and its secured segments thus comprising a forming section having a degree of curvature closely corresponding to that of the tank structure being formed, d. accurately locating the forming sections, vertically erect and proximate one another, along a base circumference location of a closed circle corresponding to the circular connfiguration of the inner surface of the tank to be formed, e. providing at the vertical edge portions of each forming sections locating means having a predetermined rigidly fixed angular relationship with its related section, and f. rigidly interconnecting each of said forming sections to its two adjacent sections to form a substantially rigid forming cylinder having a continuous outer cylindrical surface corresponding within close tolerances to the inner surface of the tank to be formed, whereby fiber reinforced resin material can then be laid against said cylindrical surface to form said tank structure.

Claim 2

A method of making a mandrel for forming a fiber reinforced resin tank structure, said method being readily adapted for making tank structures of larger or smaller diameters, where the tank structure being made has a cylindrical configuration of a preselected diameter, circumference and degree of curvature, said method comprising: a. providing a plurality of substantially planar forming sheets, each of which is readily bendable into a curve about a vertical axis, each of said sheets having a predetermined lateral dimension, the total of which dimensions equals the circumference of the tank structure at the inner surface thereof; b. selecting a plurality of rigid forming segments for said forming sheets, each of which selected segments has an arcuate forming edge surface having a degree of curvature equal to that of the tank, and a length substantially equal to the width dimension of its related sheet, c. forming each of said sheets into a substantially rigid arcuate forming section by curving each of the sheets from its planar configuration to conform the sheet against the forming edge surfaces of at least two of said segments, and securing each of said sheets with respect to its related segments, with each sheet and its secured segments thus comprising a forming section having a degree of curvature closely corresponding to that of the tank structure being formed, d. accurately locating the forming sections, vertically erect and proximate one another, along a base circumference location of a closed circle corresponding to the circular connfiguration of the inner surface of the tank to be formed, e. providing at the vertical edge portions of each forming sections locating means having a predetermined rigidly fixed angular relationship with its related section, and f. rigidly interconnecting each of said forming sections to its two adjacent sections to form a substantially rigid forming cylinder having a continuous outer cylindrical surface corresponding within close tolerances to the inner surface of the tank to be formed, whereby fiber reinforced resin material can then be laid against said cylindrical surface to form said tank structure.