# US 8,782,898 B2 · Method for twisting hollow bars

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- Number: US 8,782,898 B2
- Document ID: US8782898B2
- Status: Granted
- Kind: B2
- Application number: 13/003,710
- Filed: 2009-02-19
- Published: 2011-12-01
- Granted: 2014-07-22
- Earliest claimed: 2009-02-19
- Applicants: Kian Yong Heng
- Inventors: Kian Yong Heng
- Web page: https://patentgrep.com/patent/US8782898B2

## CPC

- B21D 11/14: Twisting
- B21D 47/04: composite sheet metal profiles
- E04C 2003/0417: {demountable}
- E04C 2003/043: {the hollow cross-section comprising at least one enclosed cavity}
- E04C 2003/0447: {circular- or oval-shaped}
- E04C 2003/0465: {square- or rectangular-shaped}
- Y10T 29/49616: Structural member making
- Y10T 29/49623: Static structure, e.g., a building component
- Y10T 29/49631: Columnar member
- Y10T 29/49826: Assembling or joining
- Y10T 29/49908: Joining by deforming
- Y10T 29/49924: of parallel side-by-side elongated members
- Y10T 428/12333: Helical or with helical component
- B21D: WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL (working or processing of wire B21F)
- E04C: STRUCTURAL ELEMENTS; BUILDING MATERIALS (for bridges E01D; specially designed for insulation or other protection E04B; elements used as building aids E04G; for mining E21; for tunnels E21D; structural elements with broader range of application than for building engineering F16, particularly F16S)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method for fabricating a hollow bar that forms elements of a grille or railing of a metalwork piece where the bar is twisted manually, machine-assisted or automated machinery, into a spiral form for decorative or ornamental purposes. By providing the hollow bar to be comprised of separate longitudinal parts which may be hinged-joined to complementarily fastened to each other to form the hollow bar, the longitudinal joints are thus amenable to increased torsional stress, such that each of the parts may be twisted without breaching the material's fatigue limit and the bar as a whole capable of being twisted with more spiral turns within its elasticity limits. The twisted bar may thus be released for re-working for adjustments or re-installation. A number of exemplary joint embodiments, internal and external bracing accessories are also disclosed to cater for the different longitudinal part fabrication, e.g. by extrusion or roll-milling.

## Claims

### Claim 1

A method of longitudinally twisting a hollow elongate member to a desired spiral form comprising:
(a) fabricating a plurality of longitudinal parts integral with joint means complementarily fastenable to each other into forming said hollow elongate member;
(b) fastening said plurality of longitudinal parts with said joint means to assemble said hollow elongate member;
(c) twisting said assembled hollow elongate member to said desired spiral form; and
(d) bracing to maintain the hollow elongated member in the desired twisted spiral form,
wherein the bracing step includes integrally fabricating features with the longitudinal parts which features, upon assembly, form internal bracing features within the hollow elongate member,
wherein the internal bracing features include a sleeve formed by complementary semi-cylindrical halves integral with each of the longitudinal parts,
and wherein said semi-cylindrical halves are joinable to each other by sleeve joints.

### Claim 2 (depends on 1)

The method according to claim 1 wherein the joint means accommodate limited pivotal movement due to moment of force arising from the twisting.

### Claim 3 (depends on 1)

The method according to claim 1 wherein the joint means are provided along the connecting edges of each of the longitudinal parts enabling a continuous longitudinal joint.

### Claim 4 (depends on 1)

The method according to claim 1 wherein the joint means are selected from any one or combination of tongue-in-groove type including hinge joint, ball-and-socket joint, pivot joint and uniaxial joint.

### Claim 5 (depends on 1)

The method according to claim 1 wherein the longitudinal parts are fabricated by any one or combination of extrusion, roll-milling, stamping, pressing or bending processes.

### Claim 6 (depends on 1)

The method according to claim 1 wherein the hollow elongate member comprises a pair of identical longitudinal parts complementarily forming said hollow elongate member.

### Claim 7 (depends on 1)

The method according to claim 1 wherein the hollow elongate member has a cross-sectional profile selected from the group consisting of triangle, rectangle, square, rhomboid, cuboid, parallelogram, ellipse, and oval.

### Claim 8 (depends on 1)

The method according to claim 1 further comprising inserting a rod into the sleeve and transfixing said sleeve and rod with retaining pins at each ends of the hollow elongate member to keep the desired spiral form from unraveling.

### Claim 9 (depends on 1)

The method according to claim 1 wherein the bracing step includes providing a rod affixed with a plurality brace plates disposed therealong at suitable intervals and orientation to internally support the desired twisted spiral form of the hollow elongate member.

### Claim 10 (depends on 9)

The method according to claim 9 wherein the brace plates are provided with slots for insertion of the seam formed by the edges of roll-milled longitudinal parts.

### Claim 11 (depends on 1)

A method according to claim 1 wherein the bracing step comprises providing end bracing means at each of the hollow elongate member's ends to keep the desired twisted spiral form from unraveling.

### Claim 12 (depends on 11)

A method according to claim 11 wherein the end bracing means is provided in series for a row of hollow elongate members.