# US 2017/0254355 A1 · Transmission Shaft and Method for Producing Same

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- Number: US 2017/0254355 A1
- Document ID: US20170254355A1
- Status: Published application
- Kind: A1
- Application number: 15/509,702
- Filed: 2015-09-09
- Published: 2017-09-07
- Earliest claimed: 2014-09-09
- Assignees: BD Invent
- Applicants: BD Invent SA
- Inventors: Benoît Boveroux
- Web page: https://patentgrep.com/patent/US20170254355A1

## CPC

- F16C 3/026: {Shafts made of fibre reinforced resin}
- B29C 53/56: Winding and joining, e.g. winding spirally {(winding in general B65H)}
- B29C 70/86: Incorporated in coherent impregnated reinforcing layers, {e.g. by winding}
- B29L 2031/75: {Shafts}
- F16C 2326/06: Drive shafts
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES

## Abstract

The invention relates to a method for producing a transmission shaft (1) comprising a body (2) made from composite and a coupling piece (3) at one end of the body (2), said coupling piece (3) being hollow and having splines (4) on the inner surface thereof, the base (6) of the splines (4) delimiting the perimeter of a circle of diameter D2 and the head (5) of the splines (4) delimiting the perimeter of a circle of diameter D1, characterized in that said method comprises the successive steps of:—providing a mandrel (10) having an expandable part (12) and a non-expandable part (11);—producing the body (2) by winding pre-impregnated fibre filaments around the mandrel (10);—positioning the coupling piece (3) around the body (2) on the expandable part (12) of the mandrel;—expansion of the expandable part (12) of the mandrel (10) in order to fill the base (6) of the splines (4) with the impregnated fibres of the body (2);—curing the body (2) provided with the coupling piece (3).

## Claims

### Claim 1

A method for producing a transmission shaft (1) comprising a composite body (2) and a coupling part (3) at one end of the body (2), said coupling part (3) being hollow and having splines (4) on the inner surface thereof, the base (6) of the splines (4) delimiting the perimeter of a circle of diameter D2 and the head (5) of the splines (4) delimiting the perimeter of a circle of diameter D1,
characterized in that said method comprises the following successive steps:
providing a mandrel (10) having an expandable portion (12) and a non-expandable portion (11),
producing the body (2) by winding pre-impregnated fiber filaments about the mandrel (10),
positioning the coupling part (3) about the body (2) on the expandable portion (12) of the mandrel (10),
expanding the expandable portion (12) of the mandrel (10) in order to fill the base (6) of the splines (4) with the pre-impregnated fibers of the body (2),
curing the body (2) provided with the coupling part (3),
removing the mandrel (10).

### Claim 2 (depends on 1)

The method as claimed in claim 1, wherein the coupling part (3) is positioned about the body (2) before the body is cured.

### Claim 3 (depends on 1)

The method as claimed in claim 1, wherein the external diameter of the body (2) formed by filament winding is slightly less than the diameter D1.

### Claim 4 (depends on 1)

The method as claimed in claim 1, wherein the mandrel (10) is metal.

### Claim 5 (depends on 1)

The method as claimed in claim 1, wherein the splines (4) extend along the entire length of the coupling part (3).

### Claim 6 (depends on 1)

The method as claimed in claim 1, wherein the inner surface of the coupling part (3) has a groove (7) extending perpendicular to the splines (4), and the expansion of the expandable portion (12) of the mandrel (10) also enables the groove (7) to be filled with the pre-impregnated fibers of the body (2).

### Claim 7 (depends on 1)

The method as claimed in claim 1, wherein the transmission shaft (1) has a coupling part (3) at each of the ends of same, and wherein the mandrel (10) comprises the non-expandable portion (11) bookended at each end by the expandable portion (12).

### Claim 8

A transmission shaft (1) having a composite body (2) and a hollow coupling part (3) positioned about the body (2) at one of the ends of same, the inner surface of said coupling part (3) having splines (4), said composite body (2) filling the splines (4) entirely such as to ensure contact at every point between the body (2) and the splines (4), leaving no interstices, characterized in that the splines (4) extend parallel to the longitudinal axis of the body (2) to optimize torsional load bearing.

### Claim 9 (depends on 8)

The transmission shaft (1) as claimed in claim 8, wherein the splines (4) extend along the entire length of the coupling part (3).

### Claim 10 (depends on 8)

The transmission shaft (1) as claimed in claim 8, wherein the inner surface of the coupling part (3) has a groove (7) extending perpendicular to the splines (4).

### Claim 11 (depends on 8)

The transmission shaft (1) as claimed in claim 8, including a coupling part (3) at each end of the body (2).

### Claim 12

A hollow coupling part (3) having splines (4) on the inner surface of same that extend along the entire length of the coupling part (3) and parallel to the longitudinal axis of said part (3).

### Claim 13 (depends on 12)

The coupling part (3) as claimed in claim 12, including one or more grooves (7) on the inner surface of same extending perpendicular to the splines (4).

### Claim 14 (depends on 12)

The coupling part (3) as claimed in claim 12, wherein the base (6) of the splines (4) is flat.

### Claim 15 (depends on 12)

The coupling part (3) as claimed in claim 12, wherein the opening angle of the heads (5) of the splines (4) is equal to or less than 55°.

### Claim 16 (depends on 12)

The coupling part (3) as claimed in claim 12, wherein the heads (5) of the splines (4) are truncated.