This application claims the priority of German Patent Application No. 10 2005 030 632.2-26, filed on Jul. 19, 2005, the subject matter of which, in its entirety, is incorporated herein by reference.
The invention relates to a heald for a heald shaft, having features as defined in the preamble of claim 1.
It has long been a desideratum to reduce the mass of weaving components which include heald shafts and healds. A reduction of the mass of weaving components is being sought after for significantly relieving the shaft drive and the shed forming machines, for saving energy and also, for achieving higher rpm's, while no increase in wear occurs but, on the contrary, even a reduction in wear may be obtained.
During shed-forming, the healds move the warp yarns, running through their yarn eyelet, out of the plane of the warp yarns, while other warp yarns running between the healds are moved by another other heald shaft in the same, or in the opposite direction. In this manner during each shed-forming process, the tensioned warp yarns run along the outer side of a heald. Such an occurrence causes an extreme stress on the yarns which may lead to warp yarn damage and, in an extreme case, to warp yarn breakage.
DE 43 36 362 C1 discloses a heald having a specially shaped yarn eyelet. The lead consists of a suitably shaped flat material. In the region of the yarn eyelet it is twisted in such a manner that the flat sides are oriented at an inclination to the warp yarn direction. The warp yarns which are situated between the healds and which do not run through the yarn eyelet, have to brush against the outer edges of the yarn eyelet and may thus be damaged.
The same document further discloses a heald which is not twisted in the region of its yarn eyelet, but in which the two webs bordering the yarn eyelet are merely bent in opposite directions. In this manner both lateral surfaces of the heald are, along their respective entire length, oriented in the warp yarn direction. It is noted, however, that because of bending the yarn eyelet webs, in the yarn eyelet at both the upper and the lower end a respective sharp corner is formed which may tend to provide a cut in a warp yarn. Further, the outward laterally bent legs do not prevent the adjoining healds from approaching one another so closely that one leg of an adjoining heald intersects the yarn eyelet of the other heald. This too, may result in the warp yarns to gun up and down on the more or less sharp edges of the heald to thus cause yarn damage.
EP 0403429 discloses a heald made of a fiber-reinforced plastic. The heald body is provided with rounded edges in the region of the yarn eyelet, as well as in portions extending away therefrom. Similarly to the previously discussed heard, here too, adjoining yarn eyelets may overlap one another. This may cause damage to the yarns which run between the healds and which must pass by the yarn eyelet during shed-forming. This applies particularly at high operating speeds.
Accordingly, it is the object of the invention to provide an improved heald.
The heald according to the invention has a heald body which is provided with a spacer means at the yarn eyelet. The spacer means prevents adjoining healds in the region of the yarn eyelets from overlapping, as looking in the warp yarn direction. In this manner a yarn, running between the healds, is only inappreciably, if at all, forced out of the warp yarn direction when it passes by the yarn eyelets of the adjoining healds. In particular, the warp yarn is not forced onto the edges of the healds or the edges of the yarn eyelets on which the warp yarn could be damaged. Particularly thermally sensitive yarns, which could be damaged not only by the sharp edges, but also by friction heat, may be processed in this manner at high operating speeds. By avoiding a heald overlap, particularly in the region of the yarn eyelets, a low-deflection and thus low-friction run of the warp yarns is possible both as concerns their longitudinal motion (in the warp yarn direction) and their shed-forming motion.
The lateral surface is oriented preferably in the warp yarn direction along its entire length which is effective in shed-forming. This applies particularly for the regions-adjoining the yarn eyelet and the yarn eyelet itself. In this manner damage to the yarn passing by the heald is prevented precisely at the constriction formed by the yarn eyelet.
In this arrangement it is advantageous to round the front and rear edges of the healds; this further reduces stress on the yarns.
The lateral surface is preferably a planar surface at the yarn eyelet. The webs bounding the yarn eyelet need not be laterally arcuate; rather, they may be essentially straight. In this manner the possibility is provided for defining the inner contour of the yarn eyelet in such a manner that no upper or lower pointed corners are obtained in which the warp yarn may be wedged and damaged. Further, the yarn running past the yarn eyelet is prevented from remaining suspended thereon.
The spacer means is preferably formed by a portion of the lateral surface which adjoins the yarn eyelet. Such a surface portion can be found, for example, immediately above or below the yarn eyelet, assuming a vertical length direction of the heald. In such a region the heald body is as thick as the distance of the lateral surfaces of the webs in the region of the yarn eyelet. In this manner yarn eyelets of adjoining healds cannot overlap. A yarn, running past the yarn eyelet between the healds during shed-forming, crosses over the yarn eyelets essentially without hindrance.
The lateral surfaces are preferably formed as ramp surfaces for securely guiding the yarn crossing over the yarn eyelet. The ramp surfaces are preferably planar; they may be, however, slightly arcuate.
The distance between the two oppositely located lateral surfaces in the region of the yarn eyelet, that is, the thickness of the heald body above and below the yarn eyelet is greater than the width of the yarn eyelet measured in the same direction. Such an arrangement contributes to maintaining the desired yarn eyelet distance. Stated differently, the division given by the warp yarn running through the yarn eyelet, that is, the center distance between adjoining yarn eyelets may not become less than the external width of the yarn eyelets and definitely not less than the inside width thereof, even if adjoining healds move toward one another to the closest possible extent.
The yarn eyelet is preferably bordered by webs whose inner sides form guiding surfaces which are parallel to the lateral surfaces. Such an arrangement results in a gentle handling of the yarn as it runs through the yarn eyelet. Further, the yarn eyelet is adjoined at the top, as well as at the bottom, by preferably planar or slightly arcuate surfaces which extend in the warp yarn direction and which are essentially smooth to also serve for a gentle handling of the yarn during its run. These surfaces are arcuate in a direction away from the yarn eyelet at the yarn-inlet side of the heald and, if required, also at the yarn-outlet side of the heald. This results in a gentle handling of the yarn, particularly in case of an open shed.
The webs bordering the yarn eyelet are preferably offset with respect to one another relative to the warp yarn direction, whereby a warp direction distance is obtained. Further, the webs are offset with respect to one another transversely to the warp yarn direction, whereby a transverse distance is obtained. The warp direction distance is preferably greater than the transverse distance. In this manner an automated yarn draw-in is readily feasible in such healds, while the healds remain sufficiently slender for processing even very thin yarns.
The lateral surface may be provided with a recess, such as a groove extending in the length direction L of the heald. Such an arrangement substantially reduces the mass of the heald without appreciably adversely affecting the strength thereof. The heald body may be made of plastic which has advantages concerning weight. Further, the heald may be of a fiber-reinforced material, such as aluminum with boron fibers which results in a light and strong structure. It is also feasible to form the heald body seamlessly from one and the same material to thus obtain a one-piece component. This prevents weak locations and provides for a simple manufacture. The heald body may be provided in its entirety or partially, with a wear-reducing coating, for example, particularly in the region of the yarn eyelet, inside as well as at its lateral surfaces. Such a measure particularly prevents a yarn from sawing itself into the yarn eyelet.
The yarn eyelet may also be made of a wear-resistant insert, such as ceramic, tungsten carbide, or a hard metal and, if required, the insert may be provided with a coating. In this manner light and, at the same time, highly wear-resistant healds are obtained.
Special details of embodiments of the invention result in further advantages and are subject of the drawing, the description or the claims. Exemplary embodiments of the invention are shown in the drawing.
As concerns these fundamental features, the heald 4 according to
In the previously described embodiments the heald body 8 consists preferably entirely or in part of a plastic, for example, a fiber-reinforced synthetic material. Carbon fibers, glass fibers or other type of fibers may be used as reinforcing fibers. The fiber length may be uniform and may be, for example, 2 mm. It is also feasible to utilize fiber mixtures having different fiber lengths. The fibers may be oriented purposefully, for example, in the length direction L of the heald 4 or may be embedded into the plastic without a preferred orientation. In this connection preferably glass fiber are used as short fibers in which case then the heald bodies 8 may be manufactured in a usual casting process
In the alternative, the healds 4 may be, in their entirety or limited only to the heald bodies, made by hot-pressing or forging from a suitable metal, such as magnesium, aluminum, a magnesium alloy or an aluminum alloy. The healds 4 may be provided with a wear-resistant coating, particularly for processing aggressive warp yarns. This applies particularly in the zone of the yarn eyelet 6 as well as the lateral surfaces of the heald body. In case of a heald, which is cast or forged, for example, from an aluminum alloy, the coating is preferably an Eloxal layer.
In the above described embodiments the end eyelet 9, 10 may be a single piece with the heald 4. This means that the end eyelet 9, 10 seamlessly joins the heald body 8 and is made of the same material as the latter. It is, however, possible in the alternative to append the end eyelets on the heald body 8 and, if required, make them from a different material. Embodiments in this connection are illustrated in
For the end eyelets a particularly wear-resistant material, such as tempered steel, tungsten carbide, or ceramic may be used. The attachment of the end eyelets 9, 10 to the heald body 8 is effected, for example, by a form-fit or a material bond by gluing or soldering. If a casting process is used, the heald body 8 may be cast onto the end eyelet 9, 10. In such a case it is possible to form the transverse pin from the heald material to thus become a component of the heald body 8. A separately formed transverse pin is not necessary in such a case.
As particularly well seen in
Another particularity of the heald 4 according to the invention resides in the configuration of the yarn eyelet 6. The latter is arranged in the thickest region of the heald body 8. The portion of the heald body 8, situated above and underneath the yarn eyelet and shown in
The yarn eyelet 6 is laterally bounded by two flank-parallel webs 39, 40. The outer sides of the webs 39, 40 are formed by the lateral surfaces 23, 24. The inner sides are formed by the guiding surfaces 41, 42 which are oriented parallel to one another as well as parallel to the lateral surfaces 23, 24. The webs 39, 40 extend parallel to the length direction L of the heald body 8. The webs 39, 40 are offset relative to one another with respect to the warp yarn direction K as well as transversely thereto. Between themselves they form, for the warp yarn, a passage oriented in the warp yarn direction K. The webs 39, 40 are, along their entire length in the length direction L, spaced from one another by the thickness of the approximately rectangular envelope 48. They are in this manner laterally mutually offset and are each substantially flat, planar and substantially thinner than the heald body 8 in the vicinity of the yarn eyelet. They are set on the heald body 8 transversely to the warp yarn direction K at locations spaced from one another which is particularly well seen in
The yarn eyelet 6 is bounded at its upper and lower ends by respective, preferably essentially planar or groove-shaped yarn guiding surfaces 43, 44. They may flare in a funnel-like manner particularly toward the yarn-inlet side, but also, as shown in
The angle 51 between the envelopes 47, 48 is preferably at least 30°; in the present instance it amounts to 90°. Further, the envelope 47 is preferably wider than the envelope 48. It is sufficient for the latter if its width equals that of the warp yarn to be guided. In the yarn eyelet 6 of
The healds 4 described up to this point operate as follows:
The surface regions 37, 38 lie in a common plane with the outer side of the web 40, they adjoin the latter upward and downward relative to the length direction L and extend, in case the web 40 is situated at the rearward end of the heald body 8 relative to the warp yarn direction K, up to the frontal end of the heald body 8. In case the web is arranged at the frontal narrow side, as, for example, the web 39, the respective surface regions, lying in the same plane, extend up to the rearward narrow side of the heald body 8.
It is to be noted that the transverse passage represented by the envelope 47 may be dispensed with; this depends from the extent of automation of the yarn draw-in. The webs 39, 40 extend in such a case, for example, over the entire width or almost the entire width of the heald body 8 as viewed in the warp yarn direction K and leave free only the narrow passage having the envelope 48.
The heald 4 according to the invention has a heald body 8, whose thickness increases toward the yarn eyelet 6. The lateral surfaces 23, 24 of the heald body 8 constitute guiding surfaces which are oriented in the warp yarn direction and which, adjacent the yarn eyelet 6, serve as spacer means 35, 36 for holding at a distance adjoining yarn eyelets 6 of adjoining healds.
Number | Date | Country | Kind |
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102005030632.2-26 | Jul 2005 | DE | national |