AUXILIARY SUB-NOZZLE FOR FLUID JET TYPE LOOM AND PRODUCTION THEREOF

Abstract: This invention relates to an auxiliary nozzle for a loom which jets a pressurized gas in order to prevent the slowdown of a weft to be crossed with warp and to a method of producing the same. At least the tip of an auxiliary nozzle body is composed of an integrally molded ceramic material having extremely small surface coarseness, high tenacity and high strength, which makes it possible to remarkably reduce the occurrence of damage to the warp and to obtain a high quality woven product. Particularly when zirconia ceramic is employed, the moldability and durability of the nozzle can be improved drastically. Further when partially stabilized zirconia is used as a matrix, the moldability, borability and wear resistance can be improved and a high precision auxiliary nozzle can be obtained.

Description: The present invention relates to an auxiliary nozzle for looms according to the preamble of claim 1 which jets a pressurized gas in order to prevent a stall of a weft inserted into warp shedding, and to a method of manufacturing the nozzle, according to the preamble of claim 8. Such a nozzle is known e.g. from JP-U-62-28887. [BACKGROUND OF THE INVENTION] Conventionally, an auxiliary nozzle for a loom is formed into a hollow rod-like member by press drawing process or by seamless welding metal sheet, as disclosed in Japanese Unexamined Patent Publications (Kokai) Nos. 54042/1983, 106541/1984 and the like. The following conditions should be fulfilled in terms of functional or positional restriction thereof. First, in weft insertion, a tip portion of an auxiliary nozzle has to be moved into a warp shedding and moved backward from the warp shedding before beating up takes place. At this time, the tip portion of the auxiliary nozzle is moved into the warp shedding while forcing through the sheet-like warps, and therefore the outer peripheral surface thereof rubs against the warp. Therefore, a sectional width of the auxiliary nozzle has to be made as small as possible in order to avoid a friction with the warp, to minimize an increase of friction and tension of the warp and not to impede jetting of air for carrying weft from the auxiliary nozzle. The auxiliary nozzle, in a state wherein pressurized air stays therein, jets air for carrying weft from a small jet orifice at a predetermined flow velocity. Therefore, the larger the internal area near the jet orifice, the speed of a jet flow increases, and therefore, the volume thereof should be made as large as possible. On the other hand, a length (depth) of the jet orifice need have a dimension value in excess of a predetermined value in connection with a diameter of the jet orifice in order to stabilize and straighten the direction of the jet flow. Such a theoretical elucidation is disclosed in, for example, Japanese Patent Publication (Kokoku) No. 32733/1985. As described above, the auxiliary nozzle of this kind needs to be fulfilled by the reciprocal requirement in which the dimension of the outside diameter is made as small as possible and the internal volume made large, and a metal nozzle manufactured by the above-described processing method has a limit to fulfill this requirement. Since the tip portion of the auxiliary nozzle is moved into and backward from the warp shedding while rubbing against the warp, the outer peripheral portion of the auxiliary nozzle becomes worn, and surface flaws, cracks, burrs or the like occur. If these become large, the warp becomes damaged and cut or fluff, deteriorating the quality of woven fabric. Therefore, the surface of the nozzle should have an excellent wear resistance. Japanese Unexamined Utility Model Publication (Kokai) No. 28887/1987 discloses a nozzle body which is formed of a cermet material excellent in toughness in order to improve the wear resistance of surface. However, the inner wall surface of the jet orifice should be as smooth as possible to converge and straighten the jet flow. The roughness of the surface need be 0.5 µm or less. In the normal cermet, grains thereof are large and the cermet comprises a composition of hard grains and a metal binder, and, therefore, as the wear progresses, the hard grains project, as a result of which the surface and inner wall surface become rough, failing to fulfill the condition for the surface roughness. Furthermore, it has an insufficient wear resistance, and it is difficult to mold a pipe-like configuration on which one end is closed. It is also very difficult to mold so as to have a one-sided wall thickness, failing to obtain a thin auxiliary nozzle. Moreover, it is contemplated that a ceramics layer is formed by flame coating processing in order to improve the wear resistance, which however involves a problem of drilling a jet orifice. That is, a jet orifice for jetting air must be provided at the fore end portion of the auxiliary nozzle but when the ceramics is subjected to flame coating processing after a jet orifice has been made in the nozzle body, an uneven layer of the ceramics layer occurs in the inner surface of the jet orifice because it is difficult to apply even flame coating to the inner peripheral surface of the jet orifice. If the inner surface of the jet orifice is uneven, the jet flow becomes unstabilized and in addition the flame coated layer of the surface of the nozzle body possibly peels off, thus failing to provide a sufficient function as an auxiliary nozzle. Moreover, in the manufacture of auxiliary nozzles, drilling processing is also important, which processes include electric discharge machining process, diamond drilling, laser process, supersonic vibration machining process, etc. Among these processes, as the process of making a jet orifice of an auxiliary nozzle, the electric discharge machining is most effective since burring of an open surface of a jet orifice and chamfering after the process need not to be applied, finishing is good in terms of jet characteristic of fluid, drilling with high accuracy becomes possible, and drilling process is inexpensive as well as volume production is possible. As described above, it is desirable to employ a conductive material for manufacturing an auxiliary nozzle. [DISCLOSURE OF THE INVENTION] It is therefore an object of the present invention to provide an auxiliary nozzle and a method for manufacturing the same, in which the auxiliary nozzle can be formed to be thin, as well as of a one-sided wall thickness, has a wear resistance and a small roughness of surface, and is totally fulfilled with all the requirements required for the auxiliary nozzle for looms such as workability of a jet orifice. An auxiliary nozzle is provided having at least a tip portion formed of integrally molded ceramics according to claim 1 to thereby achieve the aforementioned object. It is desirable that the above-described ceramics material has relative density - 98 % or more, hardness in H R A - 89 or more, bending strength - 50 kg/mm² or more, modulus of elasticity - 1.4 × 10⁴ kg/mm² or more and homogeneouS structure. Further, in terms of coefficient of friction of hardness, that is, slidability, zirconia or a composite material using zirconia as a matrix is most excellent, preferably, relative density - 99 % or more, hardness in H R A - 89.5 or more, bending strength - 70 kg/mm² or more and modulus of elasticity - 1.8 × 10⁴ kg/mm² or more. As the zirconia material, chemically stable zirconia is suitable. Particularly, as the stabilizer, yttrium oxide, calcium oxide or magnesium oxide, cerium oxide or the like is added to provide a partially stabilized zirconia. The partially stabilized zirconia ceramics or zirconia used comprises, for example, zirconia partially stabilized by yttrium oxide of 2 - 5 mol %. For example, as described in Japanese Unexamined Patent Publication (Kokai) No. 103078/1985, the partially stabilized zirconia is obtained by stabilizing fine powder of zirconium oxide by a stabilizer of 2 - 6 (mol %) such as yttrium oxide, adding thereto powder of 40 (capacity %) such as titanium carbide, tungsten carbide or the like as an agent for applying conductivity, followed by sintering to provide a conductive ceramics which is excellent in wear resistance at least in the surface of the auxiliary nozzle as compared with metal and cermet, and at the same time, the electric discharge machining of the auxiliary nozzle body becomes possible. As the above-described ceramics material, the ceramics material having a high toughness and high strength which comprises ultrafine grains can be used to obtain an auxiliary nozzle having a surface roughness of 0.5 µm or less by electric discharge machining. The characteristics required for formation of a partially stabilized zirconia sintered body from the aforesaid starting powder material are sinterable at low temperature, ultrafine powder properties, small grain-growth rate during sintering and the like. As the material powder which fulfills these conditions, material produced by chemically neutral coprecipitation process [Japanese Patent Publication (Kokoku) No. 39367/1984], hydrolysis process [Japanese Patent Publication (Kokoku) No. 39366/1984] or other processes, and zirconium oxide obtained by adding yttrium salt in the amount of approximately 3 (mol %) in conversion of oxide to water soluble zirconium salt can be used as starting material, and the partially stabilized zirconia ceramics as a sintered body has a high strength and high toughness and is an optimal mechanical structural material. In place of the partially stabilized zirconia, various materials such as, in addition to alumina, zirconia-alumina, silicon carbide, silicon nitride and sialon, composite ceramics comprising a composition of more than two kinds selected from oxide, carbide, nitride and boron can be used. This ceramics material is generally excellent in wear resistance as compared with metallic material and cermet. However, in the auxiliary nozzle for uses of the present invention, the characteristics of the ceramics material preferably include relative density - 98 % or more, hardness in H R A - 89 or more, bending strength - 50 kg/mm² or more, modulus of elasticity - 1.4 × 10⁴ kg/mm² or more, and homogeneous structure, more preferably, relative density - 99 % or more, hardness in H R A - 89.5 or more, bending strength - 70 kg/mm², and modulus of elasticity - 1.8 × 10⁴ kg/mm² or more. Those of hardness in H R A less than 89 are insufficient in wear resistance of a tip portion in frictional contact with the yarn and a jet orifice, and cannot expect a service life ten times or more that of a stainless steel auxiliary nozzle. Those of relative density less than 98 % are poor in wear resistance and slidability with yarn, and if the bending strength is less than 50 kg/mm², the nozzle is possibly damaged by repeated stress over a long period of time. The modulus of elasticity should be at least 1.4 × 10⁴ kg/mm² which is not to subject to plastic deformation under the using condition as in metal material. As the molding methods for the auxiliary nozzle, injection molding method, centrifugal casting method, casting method, rubber press method and wet type press method for clay-like kneaded body can be employed. It is suggested that a binder suitable for these molding methods be mixed in advance into a sintering raw material. A method for manufacturing an auxiliary nozzle is provided by claim 7. It is contemplated to bore the orifice by grinding, supersonic, discharge process or the like after a nozzle body has been sintered. However, a method for drilling an orifice in the stage of a green molded body formed into a predetermined shape in terms of processing efficiency and smoothness of an inner surface of the orifice can be employed. The green molded body is sintered at a temperature corresponding to properties of the used ceramics material. The average structural crystal grain of the auxiliary nozzle is 3 µm or less, which need be a dense sintered body. Therefore, it is preferred to be sintered by HIP method. In the auxiliary nozzle of the present invention, the tip portion of the nozzle body formed from integrally molded ceramics is converged, and one substantially flat surface of the jet orifice is made thick to the base end, which is formed with a jet orifice communicated with the exterior from an internal space. The sintered body for the auxiliary nozzle, according to the present invention, comprises at least a nozzle tip formed from a ceramics sintered body having a homogeneouS structure. In the manufacture of an auxiliary nozzle provided with an opening for jetting high pressure air in a plane portion in the vicinity of the tip portion, it is obtained by sintering so that the ceramics sintered body has the relative density of 98 % or more after a jet orifice has been made in the stage of the green molded body. In case of the conductive ceramics material, a jet orifice can be made by use of a drill in the stage of the green molded body or by the electric discharge machining process after completion of sintering. The following effects can be obtained by the present invention. The auxiliary nozzle according to present invention is rich in durability and exhibits a stable performance over a long period of time since ceramics having high hardness and high toughness and stable heat shock and coefficience of thermal expansion. Since the nozzle is excellent in wear resistance and formed from fine grains, the surface thereof is smooth, and even if the surface comes into frictional contact with the warp, no partial wear occurs, and even if the wear progresses, the lapping-like surface is always maintained and even during movement into and out of the warps, the frictional resistance is small and the partial wear is small. Since the surface is smooth, less surface peeling occurs and the smoothness of the surface can be maintained over a long period of time when compared with those formed by surface coating of hard metal having a high hardness to base material. In the shape, at least those portions not determining a length of a jet orifice can be formed thin in wall thickness, and therefore, the volume can be increased without increasing the dimension of outside diameter to thereby enhance the rate of a jet flow, or the dimension of outside diameter can be made small without decreasing the volume to thereby suppress an influence on the warp. Since the tip portion can be prepared to be more flat, the tip portion of the nozzle can easily enter between the warps. In addition, in the state wherein the tip portion is moved in and between the warps, no great bending occurs in the warp and the tension of the warp is not temporarily increased, and therefore the damage of warp or warp cut can be prevented. Furthermore, the wall thickness of a portion in the periphery of the jet orifice can be suitably adjusted to easily secure a jet flow angle as required. It is possible to obtain a complicated shaped auxiliary nozzle which is thin and has an enlarged tip portion. Moreover, since the auxiliary nozzle of the present invention is manufactured by a powder metallurgy process, it has homogeneous structure and excellent wear resistance, thus occurring no catch in warp and preventing warp fluffing. Other features of the present invention will become more apparent from the following description of preferred embodiments. In the case where the surface of the auxiliary nozzle is formed of conductive ceramics, the electric discharge machining of a jet orifice becomes possible, and sharp edges disappear after being processed, and thereafter the jet flow becomes stabilized. In the case where the whole auxiliary nozzle has the conductivity, even if the auxiliary nozzle or warp is charged with static electricity by the frictional sliding between the auxiliary nozzle and the warp, unexpected trouble resulting from the charge of static electricity can be prevented because the conductivity let the static electricity out. In the case where a jet orifice is bored in the stage of a green molded body, drilling work becomes easier, and the shape characteristic of the jet orifice itself is excellent. Particularly, the jet orifice itself bored with an orifice has a surface roughness of 0.5 µm or less. Accordingly, high pressure air jetted out of the jet orifice will not produce a turbulance, and therefore, a high-speed air flow of 1.2 times or more as compared with a metal nozzle is obtained. Since the high pressure air is jetted at an accurate jet flow angle, the weft can be accelerated, and the number of nozzles to be mounted can be reduced to approximately 2/3. Since the specific gravity of the nozzle body can be decreased as compared with that of cermet or the like, reduction in weight of members relevant to beating up is effectively attained. [BRIEF DESCRIPTION OF DRAWINGS] The accompanying drawings show embodiments of the present invention. Figs. 1 and 2 show a first embodiment of the present invention. Fig. 1 is a longitudinal sectional view; and Fig. 2 is a sectional view taken on line V - V vertical to the lengthwise. Figs. 3 to 5 show a second embodiment. Fig. 3 is a longitudinal sectional view of an auxiliary nozzle 30; Fig. 4 is a sectional view vertical to the lengthwise; and Fig. 5 is an explanatory view of the discharge process for a jet orifice. Fig. 6 shows a loom to which the auxiliary nozzle according to the present invention has been applied. First Embodiment A nozzle body 21 (indicated by hatched lines) of an auxiliary nozzle 20 shown in Fig. 1 is formed of zirconia fine powder of high purity, to which is added 3 mol % of yttrium oxide as a stabilizer, simultaneously followed by stabilization and sintering to provide integral structure. A base end 22 of the nozzle body 21 is of an open true cylinder so that it may be connected to a pressurized air source through a holder 23, the nozzle body 21 having a tip portion 24 being formed of the same material and closed in the form of a convergent shape, and a portion from the tip to the base end 22 is formed into a flat form. Therefore, a section of the tip portion 24 is of an oval or ellipse as can be seen in Fig. 2. One flat surface of the tip portion 24 has a thick wall while the other surface is formed to be thinner than the former. As a result, the internal volume of the flat portion can be increased in volume as large as possible by making the wall thereof thin. Fig. 2 shows an example in which the tip portion is made thin in the mode of scraping off an inner portion of an oval or elliptical portion. The thick portion is formed in the substantially central position of the tip portion with a jet orifice 25 in a direction, for example, at a right angle to the flat surface. Since the jet orifice 25 extends through the thick portion from the internal space to the exterior, the length thereof or the depth of orifice has a necessary and sufficient dimension in connection with the diameter thereof in order to orient the jet fluid therein with respect to the exterior in a stable state and jet in a state with the least turbulence. In the manufacture of an auxiliary nozzle which is a thin hollow article, it is molded by a molding method using as a material, a zirconia slurry partly stabilized by yttria, and a jet orifice is bored by a cemented carbide drill or a diamond drill in the stage of a green molded body, and thereafter sintered for 2 hours at a temperature of 1450 °C in an atmospheric furnace. A test piece prepared under the same conditions as those used in the above-described process has specific gravity - 6.0, hardness H R A - 89.8, modulus of elasticity - 1.55 × 10⁴ kg/mm², and bending strength - 125 kg/mm². The thus obtained auxiliary nozzle has excellent strength, with bending strength of 120 kg/mm² or more, the surface roughness of a flat portion after lapping finish - 0.1 µm or less, and the surface roughness of the inner surface of the jet orifice - smooth surface of 0.5 µm or less. A plurality of auxiliary nozzles as mentioned above are arranged along the widthwise of warp (a) as shown in Fig. 6, and air is jetted out of a jet orifice 2 under the pressure of 1 to 4 kg/cm² to accelerate a weft (c). Even after use of for 3,000 hours under the aforementioned conditions, the weft (c) was able to be inserted in a stable manner without adverse affect on the warp (a). Although the auxiliary nozzle is sometimes somewhat worn due to the frictional contact between it and the warp (a), the surface after having been worn always maintains its smooth surface without producing a flaw or crack in the surface of the body, unlike the metal auxiliary nozzle. Moreover, the aforementioned test piece sintered at 1450 °C and the auxiliary nozzle were subjected to HIP treatment under the conditions of temperature of 1,000 to 1,500 °C and pressure of 1,000 kg/mm² or more in the atmosphere of inert gas (Ar), the specific gravity was 6.05 and hardness H R A was 91.3, and the performance of the auxiliary nozzle was further improved. Said orifice can be formed by drilling in the stage of a green molded body, or by supersonic vibration machining process after sintered, process by use of diamond drill, or in case where carbide or the like as a conductive material is mixed into fine power as a raw material, by electric discharge machining. For the purpose of comparison, a auxiliary nozzle having the same configuration as that of a conventional metal auxiliary nozzle and a auxiliary nozzle having the same internal volume as that of prior art have been prepared in trial according to the present invention. As shown in Fig. 2, let T₁, T₂, t₁ and t₂ be the dimensions of parts, those of prior art are as indicated below: T₁ = 4.5 (mm) T₂ = 2.5 (mm) t₁ = 0.5 (mm) t₂ = 0.5 (mm) An article manufactured by way of trial is molded with dimensions noted below: T₁ = 4.5 (mm) T₂ = 2.5 (mm) t₁ = 0.5 (mm) t₂ = 0.2 (mm) From the above dimension and according to the calculation, in the article of the present invention, the internal volume in the vicinity of the jet orifice has been increased by 52 % without hardly changing the external dimension. Second Embodiment A nozzle body 31 (indicated by hatched lines) forming an auxiliary nozzle 30 for a fluid jet type loom according to the present invention shown in Fig. 3 is formed of conductive zirconia type ceramic. In this conductive zirconia type ceramics, yttrium oxide in the quantity of approximately 3 mol % is added as a stabilizer to zirconia fine powder of high purity, and a carbide such as titanium carbide, tungsten carbide or the like in the amount of 17 - 40 volume % is added as an agent for applying conductivity to the aforesaid mixture, which is molded, simultaneously followed by stabilization and sintering to provide in integral structure. A base end 32 of the nozzle body 31 is of an open round cylinder so that the former may be connected to a pressure air source through a holder 33, the nozzle body 31 having a tip portion 34 closed in the form of a convergent shape, and a portion from the tip to the base end molded into a flat shape. To this end, a section of the tip portion 34 is of an elliptical shape as can be seen in Fig. 4. Moreover, one flat surface of the tip portion 34 is thick whereas the other surface is molded to be thinner than the former. As a result, the internal volume of the flat portion is increased in volume as large as possible by making it thin. The thick portion of the tip portion 34 is formed with a jet orifice 35 in a direction, for example, at a right angle to the flat surface in the substantially central position on the side of the tip. The jet orifice 35 is bored in the stage of a green molded body or processed by a electric discharge machining as shown in Fig. 5 after having been sintered. In the discharge processing, the nozzle body 31 is positioned in a state wherein the body 31 is made to correspond to one electrode 36 of the electric discharge machining and a processing position of the jet orifice 35 as the other electrode is moved close to an electrode 36. In this state, a discharge voltage is applied between one electrode 36 and the nozzle body 31 as the other electrode to form the jet orifice 35, and the inner and outer open surfaces of the jet orifice 35 are formed to have a surface which is free from burr, has an adequate curved surface and is smooth. As compared with other conductive ceramics, the conductive zirconia ceramics in the present embodiment, has high toughness and good durability and can provide a stable performance over a long period of time without change in passage of years, and the auxiliary nozzle can be formed into a flat configuration without impairing the mechanical strength. The auxiliary nozzle according to the present invention can be utilized for a auxiliary nozzle for an air jet loom within a shuttleless loom, and the method for the manufacture thereof can be utilized for manufacturing a nozzle member made of ceramics of the same kind.

Claims: An auxiliary nozzle (20) for a fluid jet type loom comprising a jet orifice (25), characterized in that at least a tip portion (24) of the nozzle body (21) is formed of integrally molded ceramics, in that said tip portion (24) comprises sections of substantially flat surfaces, one said section having a thicker wall than another section, and in that said jet orifice (25) is formed in said section having a thicker wall. An auxiliary nozzle according to claim 1, characterized in that said nozzle body (21) formed of integrally molded ceramics has an inner surface of a jet orifice (25) and an inner surface of the nozzle body which have a surface roughness of 0.5 µm or less. An auxiliary nozzle according to claim 1 or 2, characterized in that said nozzle body (21) formed of integrally molded ceramics has a flat surface wall thickness of 0.2 to 0.5 mm. An auxiliary nozzle according to claim 1, 2 or 3, characterized in that the ceramics comprises zirconia type ceramics. An auxiliary nozzle according to claim 4, characterized in that the zirconia type ceramics comprises partially stabilized zirconia ceramics. An auxiliary nozzle according to claim 5, characterized in that the partly stabilized zirconia ceramics is conductive. A method for manufacturing an auxiliary nozzle for a fluid jet type loom comprising a jet orifice (25), characterized by forming at least a tip portion (24) of the nozzle body (21) of integrally molded ceramics, said tip portion (24) being formed into sections of substantially flat surfaces, one said section having a thicker wall than another section, wherein said jet orifice (25) is formed in said section having a thicker wall. A method for manufacturing an auxiliary nozzle according to claim 7, characterized by boring said jet orifice (25) in a state wherein said molded ceramics body is in a green state, and sintering said molded ceramics body to the relative density of 98 % or more to form a sintered body having homogeneous structure. A method for manufacturing an auxiliary nozzle according to claim 7, characterized in that the sintering comprises a HIP (hot isostatic press) process.

Inventors: ATAKA RYOSUKE C O NIPPON TUNGS, MIYAHARA MICHITO C O NIPPON TU, NAKAGAWA TOORU, OKESAKU MASAHIRO, ATAKA, RYOSUKE C/O NIPPON TUNGSTEN CO. LTD., MIYAHARA, MICHITO C/O NIPPON TUNGSTEN CO. LTD., NAKAGAWA, TOORU, OKESAKU, MASAHIRO
Applicants: NIPPON TUNGSTEN, OKESAKU MASAHIRO, TSUDAKOMA IND CO LTD, NIPPON TUNGSTEN CO., LTD., OKESAKU, MASAHIRO, TSUDAKOMA CORPORATION
Application year: 1988
Main classification: D03D47
IPC codes: D03D47