Sewing – Stitch forming – Blind stitch
Patent
1996-09-30
1998-11-03
Izaguirre, Ismael
Sewing
Stitch forming
Blind stitch
11247524, 156 93, D05B 124, B32B 708
Patent
active
058293736
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a blind stitching apparatus and in particular, but not exclusively, to such apparatus adapted for mounting on a robot arm for blind stitching of preforms of fabric for making up resin impregnated composite structures.
2. Description of Related Art
The term "blind stitching" is used to describe stitching performed where the stitching head has access to one side only of the material.
In the conventional manufacture of fibre composite materials, such as, e.g., carbon composites, a woven fibre material is pre-impregnated with a matrix material (typically thermo-setting polymers such as polyesters, phenols and epoxies). The pre-impregnated material (known as pre-preg) is cut to size and laid up in layers on a former which governs the final shape.
The lay-up is then cured in an autoclave under conditions of high temperature and pressure. However this conventional process has high costs associated with the handling and treatment of pre-preg material as well as the high cost of pre-preg material itself.
In order to reduce the cost of manufacture of composite materials, we have examined the possibility of using dry, i.e., non pre-preg, fabric, in a process where the dry fibres are processed in fabric form with the resin applied by a resin transfer moulding technique. We have noted that, to enable handling and to provide preform stability, the various fabric layers need to be joined, and we found that a single-sided blind stitching technique was particularly suitable. The advantages of a stitching technique include reinforcement in the direction of thickness of the preform; minimal inclusions in the composite; the ability to use threads compatible with the parent material, and automated stitching.
The technique of single-sided or blind stitching has been established for many years, but only for clothing or other conventional materials which are robust and which are not then subjected to impregnation or other similar processes.
A preferred requirement identified by us was for the blind stitching not to penetrate through to the other side of the material. We found that typical existing machines were not capable of stitching through only a portion of the thickness of the material, and also the feeding mechanism tended to drag the fabric and cause extensive damage to it. Furthermore, existing machines usually comprise a fixed stitching location to which the material is fed. For example, British Patent Specification 824,085 shows an arrangement in which blind stitching is achieved by folding two layers of material over a rib and stitching the folded region using a curved needle and a looper which executes a series of twisting and extending movements to provide a row of blind stitches. However in this device the material moves relative to the stitching machine and is not feasible for use where a stitching head is to apply a few stitches at spaced locations over a multi-layer pre-form.
Likewise British Patent 1,585,885 shows a stitching machine in which the material to be stitched moves relative to the machine. The machine provides regular invisible stitching between the outer and central ply of a three ply fabric. This requires the ply to be folded and does not provide blind stitching from one surface only of the workpiece.
British Patent Specification 811,956 shows an arrangement in which a curved needle co-operates with a bullet-shaped looper but the needle passes completely through the layers of material and this is not desirable for tacking together preform layers, on account of possible resin inclusions.
British Patent Specifications 524,751, 484,947, 425,522 and U.S. Pat. No. 4,712,495 all show arrangements in which a stitching machine passes a curved needle through a portion of material folded over a rib and in which the material moves relative to the machine.
British Patent 262,762 shows a shoe sewing machine which uses a curved needle and looper but in which the workpiece moves relative to the sewing machine.
U.S. Patent; and shows a
REFERENCES:
patent: 2257363 (1941-09-01), Arver
patent: 2655885 (1953-10-01), Kostro
patent: 2949086 (1960-08-01), McFaddin
patent: 3154034 (1964-10-01), Greco
patent: 3186367 (1965-06-01), Greco
patent: 4331091 (1982-05-01), Parker et al.
patent: 4628846 (1986-12-01), Vives
patent: 4712495 (1987-12-01), Jagielski
patent: 4913937 (1990-04-01), Engdahl et al.
patent: 5095833 (1992-03-01), Darrieux
British Aerospace Public Limited Co.
Izaguirre Ismael
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