Textiles: knitting – Feeding – Plating
Reexamination Certificate
1999-11-01
2001-02-06
Falik, Andy (Department: 3741)
Textiles: knitting
Feeding
Plating
C066S141000, C066S111000, C264S328200
Reexamination Certificate
active
06182475
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a yarn guiding device for knitting device and more particularly a yarn guiding device for guiding the yarn unreeled from the creel, which is located above the knitting machine, before feeding the yarn in a guided manner to a knitting needle.
BACKGROUND OF THE INVENTION
Generally, the yarn guiding member of a yarn guiding device for knitting machine, which member is a component coming directly into contact with the running yarn, is mainly composed of a high grade steel for the sake of a high tenacity and erosion resistance.
While the guiding member of a yarn guiding device, consisting of the steel, can be used for a long period without a problem in the case of handling cotton yarns, the member can cause a hairy feathering on the knitting yarn or a breakage of the yarn owing to the wear of the area in contact with the passing yarn in the case of processing tough synthetic fiber yarns.
Thus, in recent years, a method was practised to improve the wear resistance of the yarn guiding device, wherein the inner wall of the yarn passage hole is coated with a hard film of metals or metal compounds such as chrome, titanium nitride or the like through plating process, but there was posed a problem in that the small dimension of the hole with its diameter of only about 1 mm and the shape of hole tapering toward the hole exit made an elaborate coating deep into the hole very difficult and moreover the duration life of the coating was short compared to the high preparation cost, requiring frequent replacements, whereby the efficiency of operation was extremely low.
To overcome the above-described problem, a yarn guiding member
4
of a yarn guiding device A′ as shown in
FIG. 7
was tried, which member was molded overall from an ordinary ceramic material excellent in wear resistance and hardness. However the product which experienced a distortion and deformation during the sintering process due to the spatial variation of shrinkage depending on the forming pressure was met with frequent breakage of the yarn guiding member,
4
when this member was firmly joined with a bracket
1
made of steel through a connecting hole
3
positioned in the upper part of the member. The sintered product was weak to impact and was also difficult to have a precise contour and smooth surface finishing to accelerate the wear of the knitting needle coming into contact with the yarn guiding member
4
up to the breakage of the needle, whereby the fed yarn is damaged to degrade the quality of the final knitgoods and sometimes even causes the stop of operation of the knitting machine.
SUMMARY OF THE INVENTION
The object of the present invention which was intended to resolve the above described drawbacks is to provide a yarn guiding device with a yarn guiding member which permits a smooth guide of knitting yarn under a constant tension without a hairy feathering and yarn breakage, which can contribute to the reduction in the price of yarn product through its simple and easy manufacturing and finishing process, and which can elevate the operating efficiency of a knitting machine through the improvement in its hardness, wear resistance and durability.
The object of the present invention is fulfilled through the improvement in the construction and material of the yarn guiding device according to the present invention which provides a yarn guiding device having a yarn guiding member, which member can be used for a long time due to a reduction in the wear from the contact with the knitting yarn, which does not only produce hairy feathers thanks to the excellent surface roughness in contact with the knitting yarn but also can prevent the wear of the knitting needle, and which is resistant to breakage and is able to maintain a high precision.
According to the invention, there is provided a yarn guiding device for a knitting machine, with a rectangular main body, which is formed on its upper part with a connecting hole for fixing a yarn guiding plate having yarn guiding holes and which is provided with yarn paths on its lower part, and with a bracket, which is joined to the main body through a connecting member so that the main body can be pivoted forward and which is disposed in the knitting section of a knitting machine, characterized in that the main body is broken down into two parts of a supporting member and a yarn guiding member, and the supporting member is formed on its lower part with a slot below which a connecting hole for the yarn guiding member is positioned, wherein the yarn guiding member is a molded article from 80 to 95 vol. % of zirconium oxide and 5 to 20 vol. % of yttrium oxide, and the yarn guiding member is formed with a recess in the form of U for connection with the supporting member through a slot and the connecting hole each formed on the supporting member and also formed with a number of yarn paths.
In addition, there is also provided according to the invention a process for manufacturing a yarn guiding member for a yarn guiding device as a molded article comprising the mixing process for raw materials, the pulverizing process wherein the mixed raw material is finely ground before pelletizing so as to be fitted for molding, the injection molding process wherein the mixed raw material is fused and withdrawn under pressure in a molding machine and then cooled, the thermal decomposition process wherein a porous article is formed by thermally decomposing the adhesive in the molded product, the sintering process wherein the burr or the like on the porous molded product is removed and subjected to crystallization at a high temperature and the finishing process wherein the molded product is polished and subjected to a gloss treatment to improve the surface smooth, characterized in that in the mixing process for raw materials, an inorganic mixture of zirconium oxide of 80 to 95 vol. % and yttrium oxide of 5 to 20 vol. % is mixed with the wax and organic adhesive at the blending ratio of 45:55 by volume at around 160° C. for 30 to 40 minutes, the injection molding is conducted under the pressure of 1000 to 1500 kg/cm
2
at the temperature of 160 to 170° C. for the retention time of 20 to 30 seconds or less to result in a molded density of 2.5 to 3.5 g/cm
3
; the thermal decomposition process is conducted at 330 to 550° C. for 73 to 76 hours; and the sintering process is run for 15 to 20 hours as the temperature is raised up to 1500 to 1600° C. starting from 0° C.
Moreover, in one aspect of the present invention, the mixture of raw materials for molding the yarn guiding member of a yarn guiding device includes, beside the main components of zirconium oxide of 80 to 95 vol. % and yttrium oxide of 5 to 20 vol. %, a trace amount of aluminium oxide(Al
2
O
3
), calcium carbonate(CaCO
3
), titanium oxide(TiO
2
) and ferric oxide(Fe
2
O
3
).
REFERENCES:
patent: 436996 (1890-09-01), Power
patent: 1578710 (1926-03-01), Byrd
patent: 2796752 (1957-06-01), Hauberg
patent: 3643476 (1972-02-01), Overdyck et al.
patent: 3887387 (1975-06-01), Sturhahn
patent: 5160097 (1992-11-01), Josefsson et al.
patent: 5989492 (1999-11-01), Larsson
patent: WO 94/20660 (1994-09-01), None
patent: WO 94/23105 (1994-10-01), None
Agarwal, P.C. Dinesh
Falik Andy
Keumyong Machinery Co., Ltd
LandOfFree
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