DD290254A5 - MASS, SHAPE AND POSITIONING COMPOSITIONS FROM FIBER COMPOSITES - Google Patents

Abstract

The invention relates to Masz-, form and Lageverkoerperungen of fiber composites, which are preferably prepared using carbon and / or aramid fibers for large amounts. The aim of the invention is to ensure the consistency of Maszkonstanz this test even under unfavorable environmental conditions; The task is to exclude the absorption of moisture in the fiber composite. According to the invention, the composition, shape and positional composites are provided with a layer providing a diffusion-blocking layer, at least with regard to their surface accessible to the atmosphere. Such layers may be metal foils, vapor deposited metals, glass, ceramics, wax, and comparable materials in their effect. Examples of applications of the invention are tracer elements for measuring devices, geodesic measuring plates, endmasks, step endmasks and test elements for measuring machines, gauges, flexible stripper carriers and masonry implements implied in machines. {Fiber composite material; carbon fiber; aramid fiber; large lengths; unfavorable environmental conditions; diffusion barrier layer; Metal foils; vapor-deposited metals; Glass; ceramics; Wax}

Description

Explanation of the essence of the invention

The object of the invention is to exclude the absorption of moisture in Faeerverbundwerkstoff. According to the invention, dimensional, shape and positional embodiments of fiber composite material are provided with a diffusion barrier layer at least with respect to their surface accessible to the atmosphere. Such layers may be metal foils, vapor-deposited metals, glass, ceramics, wax and materials comparable in their effect. The applied layers preferably have a thickness that is comparatively small compared to the basic structure, so that their influence on its LTK is negligible. If this is technologically not possible or not appropriate, the LTK of the fiber composite material is to be designed in a known manner by varying the fiber and matrix material such that the LTK a _g "of the dimensional, shape and positional embodiment of the invention corresponds to the desired value, preferably zero ,

Thus, the use of the standards according to the invention in extension of the hitherto known applications, even under extreme environmental conditions, as z. B. occur within housed processing centers by the action of coolants or their spray.

embodiment

The invention will be explained below with reference to an exemplary embodiment.

Fig. 1 shows in section schematically the layer structure of a tube made of fiber composite material, as it can be used, for example, as a basic body for gauge blocks for large lengths (I ä 500mm).

The stiffness and strength, as well as the length-temperature coefficients of the tube defining layers are made of carbon fibers, glass fibers and an epoxy resin matrix according to the winding process. The pipe outside diameter is 35 mm in the example. Layer 1 represents the main layer of carbon-fiber-reinforced plastic (layer thickness approx. 3 mm). It follows outwardly a layer 2 made of glass fiber reinforced plastic (layer thickness about 0.5 mm), which in the present example primarily the function of an electrically insulating layer between the layers 1 and 3 (preventing an electrochemical element between the conductive carbon fibers and the outer metal layer). The layer 3 represents the actual outer, the laminate to the surrounding atmosphere towards diffusion-sealing barrier layer. It consists in the example of a 20Mm thick aluminum foil, the radial (with a small interface overlap) over the entire length around the pipe and glued iai. This layer can also be designed according to decorative outward (eioxiert, painted o. Ä.). To prevent the ingress of atmospheric moisture from the inside of the tube to the laminate there is also applied a moisture-diffusion-tight wax layer of about 0.2 mm thickness (layer 4). The comparatively soft wax layer is sufficient in the present application, since no wear-inducing mechanical stress occurs from the inside. Due to the comparatively thin diffusion barrier layers 3 and 4, the fiber composite material is protected on all sides towards the surrounding atmosphere.

Claims (4)

1. dimensional, shape and Lageverkörperungen of fiber composites, in particular using carbon and / or aramid fibers, characterized in that the fiber composite material is provided at least with respect to its surface accessible to the atmosphere with a diffusion barrier layer. 2. dimensional, shape and Lageverkörperungen according to claim 1, characterized in that the diffusion barrier layer of conductive material, preferably of metal or metal compounds. 3. dimensional, shape and Lageverkörperungen according to claim 1, characterized in that the diffusion barrier layer of non-conductive material, preferably glass, ceramic or wax. 4. dimensional, shape and Lageverkörperungen according to claim 1 and 2, characterized in that between the stiffness and strength and the length-temperature coefficient of the fiber composite material determining layer (1) made of carbon fiber reinforced plastic and the diffusion barrier layer (3) Layer (2) is inserted from electrically insulating material. For this 1 page drawing Field of application of the invention The invention relates to dimensional, shape and Lageverkörperungen of fiber composites, which are preferably made using carbon and / or aramid fibers for long lengths. Application examples of the invention are u. a. Carrier elements for measuring instruments, geodetic measuring rods, gauge blocks, step gauges and test specimens for measuring machines, measuring robots and machine tools, gauges, flexible scale carriers and standards in machining centers. Characteristic of the known state of the art Fiber composite materials have long been used in production metrology beroits for various, often complicated to be manufactured meter parts and main assemblies of Handmeßgeräten for long lengths. Internationally enforced e.g. the rod micrometer 8225 for measurements up to 11500mm of the company AB C. E. Johannson, Eskiltstuna / Sweden, whose cigar-shaped body consists of glass fiber reinforced plastic (GFP); also from GFP, there have been measuring tapes for many years (DD-AP30900). Since the mid-seventies more and more mass production of carbon fiber reinforced plastic (KFP) has become more and more common both in production measuring technology and in the Geodäse. So are u.a. Measuring instruments for internal and external measurements of long lengths (DD-WP 138835), a "Multivalent carrier element set for handheld measuring devices of large lengths" (DD-WP 156444), final dimensions or step gauges (DD-WP238665, DE-PS3806791, DE-PS3817174), " Specimens for coordinate measuring instruments "(DE-PS 3823684), but also various measuring tapes (DE-PS2950580, DD-WP250439, DD-WP248647, DD-WP263818), the KFP use as the main material known. In addition, Easislattan and Paßpunktsysteme are used as KFP-Maßverkörperungen for testing large components with geodetic measuring means. Furthermore, there is a first proposal to make the body of teachings, which serve the simultaneous dimensional, shape and attitude test, again preferably on large components, using KFP. The rigid KFP measuring graduations are generally characterized by very low mass with simultaneously high rigidity and a length-temperature coefficient (LTK) close to or equal to zero. Furthermore, if the material measure is made of several parts and made of different materials, the structure of the composite material is designed so that its LTK low negative and consequently the total construction is equal to zero (see DD-WP 238665). The advantage of such material measures is in addition to the high dimensional stability at virtually all ambient temperatures and thus higher reliability of the measurement also in the fact that the measurements immediately, and not only after the generally required temperature compensation between material standard and DUT (usual: 1.5 ... 4hl ) can be performed. Basically, the conditions are analogous to the use of aramid fibers instead of the previously preferred carbon fibers. Disadvantage of Faserverbiindwerkstoffe is that under certain environmental conditions, namely at high humidity in conjunction with relatively high temperature, to a moisture uptake by the polymer (preferably epoxy resin) and by the composite structure (in interlayers, vacuoles, etc.). This leads to an undesirable swelling of the material and possibly to changes in dimensions and mechanical properties. Object of the invention The aim of the invention is to ensure the dimensional stability of structures made of fiber composites, which are used as Maß-, form and Lageverkörperungen, even under unfavorable environmental conditions.