Single Side Stitching, an innovative textile ... - Mechanical Engineering
Single Side Stitching, an innovative textile ... - Mechanical Engineering
Single Side Stitching, an innovative textile ... - Mechanical Engineering
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For each machine segment compact units were developed with 96 flexible light guides which are<br />
led to the predestinied positions in the machine frame. If the carriers move over this stationary<br />
measuring points they cast shadow upon the open ends of the optical guides. This signals are used<br />
to control the carrier positions. Information about the actual condition of the yarn (ok or broken<br />
respectively. run out) on each moving carrier are tr<strong>an</strong>sferred in the same way from the new developed<br />
carrier with integrated light guides to the stationary measuring points.<br />
All 96 single sensors are joined in a specially developed adapter <strong>an</strong>d brought on the high-resolution<br />
matrix-chip of <strong>an</strong> asynchronous CCD-camera via <strong>an</strong> optical input element. With the aid of a frame<br />
grabber this picture is digitised <strong>an</strong>d evaluated in a compact industry PC. With a special learning<br />
program the position of each sensor c<strong>an</strong> be detected fully automatically, so that <strong>an</strong> assignment of<br />
the single sensors resp. light guide ends is not necessary. The interface to the machine control has<br />
been realised by CAN-Bus. The nominal data of each single machine segment are tr<strong>an</strong>sferred to the<br />
control system via CAN-Bus. After the internal comparison of nominal/actual data in the multi-sensoric<br />
system only the error message with detailed information of kind <strong>an</strong>d position of error is<br />
returned to the machine control.<br />
Examples of realised 3D-braids<br />
After a phase of intensive work to solve basic problems (fibre damage, occurrence of pre-braids)<br />
recognised during braiding technical fibres as carbon or glass, braids were realised for different<br />
applications. The most serious restriction in the selection of the application examples were based on<br />
the limited cross-section areas to be realised with the available prototype machine. Areas of 200 to<br />
300 mm² are in general are to low for aeronautic or automotive structural structures .<br />
Two examples of 3D-braided fibre preforms are shown in figure 8.<br />
87 mm<br />
40 mm<br />
Fig.8: 3D-braided axle with varying cross-section for a compressor stator v<strong>an</strong>e<br />
<strong>an</strong>d T-profile for application in stiffened p<strong>an</strong>el<br />
In the braided fibre preform for <strong>an</strong> axle of a compressor stator v<strong>an</strong>e two tr<strong>an</strong>sition zones of the<br />
cross-section geometry were realised. This was done by taking out part of the braiding yarns of the<br />
process <strong>an</strong>d ch<strong>an</strong>ging the geometry online from round to rect<strong>an</strong>gular. The unused fibres have to be<br />
removed before impregnation. In this way a better coupling of the aerodynamic blade to the axle is<br />
guar<strong>an</strong>teed. Furthermore different T-profiles were m<strong>an</strong>ufactured for reinforcement for p<strong>an</strong>els as<br />
they are used in aeropl<strong>an</strong>e structures. An example too is shown in fig 8. The profile was realised<br />
with a set-up of 111 braiding yarns (24K carbon fibre roving) <strong>an</strong>d 50 st<strong>an</strong>ding yarns (2x24K carbon<br />
fibre rovings) yarns. For the actual prototype machine bobbin set-ups of this r<strong>an</strong>ge at the moment<br />
are the limit with respect to profile dimension.<br />
6
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