[0001 ] This invention relates to a process for producing completely finished thread-guiding grooved cylinders, of polyurethane resin filled with aggregates with wear-resistant treatment, for textile spooling machines, cylindrical and conical with fixed-pitch or variable-pitch screws with two, two and a half, three turns.

Field of the Invention

[0002] Spinning is conventionally translated into a series of operations that allow to transform the fibres into yarn. Spinning can be considered a complex process for treating wet yarns, dry yarns, semi-wet yarns, unbleached and bleached yarns with constantly improving characteristics of fineness, resistance and regularity. Spinning includes the so-called spooling phase, in which, independently of the spinning technique used, the thread of the fibre must be freed from the last impurities it still contains and rewound on a support suitable for its subsequent use. These are the spooling functions carried out on the spoolers. In the final analysis it is the last phase in the fibre spinning process before the fibre is supplied to the weaver or to the knitted fabric manufacturer.

[0003] Spooling is included in a processing phase that is made up of essential objectives, such as yarn slubcatching, in which flaws and

i impurities are identified and eliminated. Afterwards, yarn spooling, in which the spooling machines, equipped with grooved cylinders for guiding the threads, allow to wind the thread received from the continuous spinner in small bobbins on soft or hard conical or cylindrical reels of large sizes, for example with a diameter of about 18÷30 cm. Finally, yarn paraffining takes place, which is a necessary operation when it is expected to be used in knitwear.

[0004] Therefore, it is reasonable to consider as known that the thread-guiding grooved cylinders are used on the spooling machines of the textile sector, to carry out the yarn spooling operation, which more particularly consists in transferring the yarn from the initial packaging, tube or spool, onto a rigid cone in the shape of a crossed coil wound body. This processing is used for transferring the thread to a packaging more suitable for the subsequent processing operations.

Prior art

[0005] The applicant pointed out that the present production cycle for the construction of the thread-guiding cylinder requires a very long production lead time with a series of very complex and expensive processing operations, such as: moulding of the unprocessed body in cast iron; turning, milling of the screws, pantographing of the head and tail ends, carried out on CNC and non-CNC machines. Radiusing, corner rounding, adjustments and super finishing operations on machines are also necessary. The cycle is completed by balancing and a subsequent heat or surface treatment.

[0006] Also within a patent literature search, thread-guiding cylinders to be used in the sector of the textile industry are known, and the documents found are the following:

D1 CN1086492 (Yi et al.)

D2 CN201040672 (Jian)

D3 CN2325363 (Chen et al.)

D4 CN2361 606 (Che et al.)

More particularly, D1 describes a thread-guiding cylinder, in alloy, suitable for a double loom and a winding loom in the textile industry, and made of eutectic Zn-AI superplastic alloy whose main components are Al, Mg and a residue of Zn. Its characteristics are lightness, abrasion resistance, solidity and low costs. D2 describes a thread-guiding cylinder whose flat components flange and the inside of the cylinder are made of thermosetting plastic material for the whole internal cylinder. The internal cylinder and the external cylinder made of metal interfere with each other in such a way as to form an assembly. The production technology is substantially free from cutting, saving of material and work, with a high efficiency level. It reduces production costs and increases production capacity. D3 and D4 propose some solutions of thread-guiding cylinders in superplastic alloy.

[0007] From everything mentioned above it is thus reasonable to consider as known: □ A thread-guiding grooved cylinder in cast iron obtained by moulding and successively finished with finishing processes;

□ A cylinder in superplastic alloy that employs aluminium;

□ A cylinder in composite material whose internal cylinder is obtained from thermosetting resin and is combined with a metal external cylinder.

Drawbacks

[0008] Above all with regard to thread-guiding cylinders in cast iron, it is pointed out that the shape of the screw on the cylinder determines the quantity and the quality of the reel formation. As a consequence, the complexity of the subsequent processing operations, made on several machine tools, is a phase that does not guarantee the realization of perfectly identical cylinders above all with respect to a standard reference sample. Such flaws may imply more or less evident flaws in the reel conformation.

[0009] Still, there also exists a design limit to improve the shape of the thread-guiding screw of the cylinder because bound by the shape of the tools and by the machine tools. Therefore, any realization of the cylinder carried out with the removal of shaving from workable materials different from cast iron, obtained through various production processes, would actually present the same problems as the present cylinder in cast iron.

Summary of the invention

[001 0] These and other aims are achieved by the present invention according to the characteristics as in the attached claims, solving the mentioned problems by a method for producing a thread-guiding grooved cylinder in composite material of plastic origin for spooling machines in the textile industry, grooved cylinder in composite material that requires at least the following phases:

a) the moulding of a RTV (Room Temperature Vulcanizing) silicone rubber cavity, contained in the casting mould;

b) the subsequent moulding of the thread-guiding grooved cylinder by injection casting catalyzed polyurethane resin filled with aluminium hydroxide at 70%, the centrifugation in the mould, and the catalysis, said thread-guiding grooved cylinder being provided with overmoulded inserts;

c) demoulding;

d) the application of a wear-resistant coating of hard nickel by electroforming and of hard chromium by galvanic process.

Aims

[001 1 ] In this way, by the considerable creative contribution the effect of which constitutes an immediate and not technical progress, various and important aims are achieved.

[001 2] A first aim consisted in producing a finished thread-guiding grooved cylinder that does not need balancing, prior to wear- resistant treatment, because the process guarantees to reproduce cylinders with constant shape and size characteristics, with corner rounding and without moulding junctions.

[001 3] A second aim is to improve and simplify the way of constructing and producing the thread-guiding cylinders used on the spooling machines of the textile sector, with a reasonable drop in production costs and times.

[001 4] Another aim by means of the described production method enables to further modify the shape of the screws that will allow to improve both the shape of the reel and the amount of reels produced.

[001 5] Finally, these advantages have the not negligible value of obtaining a production method and a thread-guiding grooved cylinder with a good technological content.

[001 6] These and other advantages will appear from the following detailed description of a preferred embodiment with the aid of the enclosed schematic drawings whose details of execution are not to be considered limitative but only and exclusively illustrative.

Content of the drawings

Fig. 1 is the representation of the empty mould used for moulding the RTV silicone rubber cavity and of the cylinder in polyurethane resin compound filled with aggregate.

Fig. 2 is the representation of the mould with the sample cylinder for moulding the RTV silicone rubber cavity inserted.

Fig 3 is the RTV silicone rubber cavity in the demoulding phase and after being turned over.

Fig. 4 represents the mould with the RTV silicone rubber cavity for moulding the finished cylinder in polyurethane resin compound filled with aggregate, provided with sectors for balancing release and with the wear-resistant metal inserts on the top and tail ends, fitted on the equipment for centrifuging the compound in the casting phase. Fig. 5 is the silicone rubber cavity during the demoulding from the moulded cylinder and after being turned over.

Fig. 6 is the thread-guiding grooved cylinder with ceramic inserts before being glued.

Fig. 7 is a section of the thread-guiding grooved cylinder

Practical embodiment of the invention

[001 7] The process for producing at least one completely finished thread-guiding grooved cylinder (1 9) with thread-guiding screws (1 90) requires a cycle that comprises at least the following working phases (a, b, c, d), respectively:

[001 8] Phase a^: Moulding of the RTV silicone rubber cavity (1 0). One disassembles the upper flange (1 ) from the mould (9) (Fig. 1 ) and inserts the sample thread-guiding grooved cylinder (5) (Fig 2). One repositions the flange (1 ), rotating it so that the centering pin (6) places itself on the reference hole of the sample thread-guiding grooved cylinder (5). One rotates the flange (1 ) that by means of the pin (6) causes the sample thread-guiding grooved cylinder (5) to rotate, up to the reference provided for the locking to the central body (4). The RTV 5530 silicone rubber is prepared with the specific catalyst RTV 5530 B with a ratio of 1 00:1 00 in weight. The rubber is degassed and poured into the mould (9) until filling up the cavity, using the injection hole (7). The silicone rubber has the following characteristics: temperature of the compound 20°C. Temperature of the mould 20°C. Cross-linking time 24 hours. Degree of hardness after cross-linking from 20 to 40 Shore A, preferably 30 Shore A. After about 24 hours the flanges (1 , 2) are disassembled from the central body (4). By means of an extruder piston one extracts from the central body (4) the sample thread-guiding grooved cylinder (5) embedded in the cross-linked RTV silicone rubber cavity (10). The demoulding of the RTV silicone cavity (10) (Fig. 3) is carried out by means of an operation of widening and of unwinding. The so obtained RTV silicone rubber cavity (10) can be used for moulding the resin cylinder (1 9). In a further preferred embodiment the RTV silicone rubber cavity (10), rather than being obtained in a single monolithic piece, can also be obtained in at least two or more parts that, joined to each other, are configured as one achieving said RTV silicone rubber cavity (10).

[001 9] Phase b ⁾ : Moulding in polyurethane resin filled at 70% with aluminium hydroxide.

After disassembling the flanges (1 , 2) from the central body (4) of the mould (Fig. 1 ) and applying on them the sectors (1 1 , 12) (Fig. 4) that create on the sides of the cylinder the hollow for balancing, one applies the wax based release agent on all the internal surfaces of the mould. One positions the RTV silicone rubber cavity (10) inside the central body (4) in the suitable release sectors of reference. On the top and tail ends of the RTV silicone rubber cavity (10) one must insert the tempered plate inserts (13, 14). One reassembles and locks the flanges (1 , 2) onto the central body (4). After placing the mould onto the driving joint (1 7) keyed to the driving axle (16), the rotating live centre (18) is lowered, in order to be able to carry out the centrifugation phases in safety. After preparing the polyurethane compound, made up of casting rigid polyurethane resin PC 26 filled with aggregates at 70% ± 5%, in a 70% solution, with aluminium hydroxide TLV-107/S-MES and catalyzed with hardener G 226 with a ratio of 100:100 on the resin, one injects through the casting hole (1 5) the quantity intended for filling up the mould and the motor (16) is started for a centrifugation phase with the cycloconverter at 3000 RPM for a time of about 1 20 seconds. After the centrifugation, the mould (9) has to be placed on the storage equipment to complete the catalysis for about 1 2 hours. After completing the catalysis, one disassembles the flanges (1 , 2) from the central body (4) and by means of an extruder piston one extracts the moulded grooved cylinder (19) embedded in the RTV silicon rubber cavity (10). After extracting the moulded grooved cylinder (19) that is embedded in the RTV silicone rubber cavity (10), the latter must be removed by means of a demoulding phase.

[0020] During the execution of phase (b) the samples of the process have been moulded in polyurethane compound filled with aluminium hydroxide at 70% and centrifuged to have a minimum dimensional variation (shrinkage) compatible with the subsequent wear-resistant treatment of phase (d). For the casting in the mould (9) one could also use pure resins without the addition of fillers, which would make the filling of the mould very easy but the shrinkages on the pieces after hardening would be so great as to considerably modify the sizes of the moulded piece with respect to the sample cylinder, and therefore would compromise the functionality of the moulded grooved cylinder (19). The problem could be solved by making oversized sample grooved cylinders according to the shrinkage of the resin used. The operation is not simple to carry out, due to the complexity of the shape of the cylinder (screws, radiuses etc.). Compounds with polyester resin and compounds with epoxy resin have been tested. Acrylic and polyvinyl resins could also be used for the same purpose, (with shrinkages and characteristics of the materials to be assessed), therefore all the materials that can be cast by gravity or by injection could be used for the moulding of the cylinder. On the RTV silicon rubber cavity (10) it is possible to position at least two tempered metal inserts (13, 14), one on the top end and one on the tail end. It is also possible to realize on all the crossings the undercut seats on which to insert and glue ceramic inserts (20, 21 , 22) on all the crossings of the screws (190). Such inserts (13, 1 4, 20, 21 , 22) are able to ensure the use of the moulded grooved cylinders (19) for the spooling of all the kinds of yarns that are spooled. Centrifugation, too, is decisive to obtain a very compact crown of compound on the external crown of the moulded grooved cylinder (19) with much filler and very little resin, while at the centre of the moulded grooved cylinder (19) we will have a compound with much resin and little filler. In principle a single RTV silicone rubber cavity (10) can be used various times in the execution of the same grooved cylinders ( 1 9) obtained by moulding and in this case said RTV silicone rubber cavity (1 0) has been tested for a repetition of about 30 pieces.

[0021 ] Phase c): The demoulding of the RTV silicone rubber cavity (1 0) (Fig 5) is carried out by means of an operation of widening and rolling, subsequently performing a visual inspection of the moulded grooved cylinder ( 1 9).

[0022] After said phase (c), where provided, further phases can also be provided. A first substantially requires the possibility of gluing the crossing ceramic or metal inserts (20, 21 , 22) if during the moulding of the moulded grooved cylinder (1 9) one used a sample with some pockets, obtained in correspondence of the crossings of the screws. In this hypothesis one applies the Araldite adhesive on the pockets of the crossings, (Fig 6) and then inserts the crossing ceramic or metal inserts (20, 21 , 22) eliminating the exceeding adhesive clots. The catalysis of the adhesive is of 20 minutes at room temperature.

[0023] Phase d): the moulded grooved cylinder (1 9), once completed with the fixing of the crossing ceramic or metal inserts (20, 21 , 22), is subjected to an electroforming and hard chromium plating process by a galvanic process. More particularly, one first prearranges the surface of the moulded grooved cylinder (1 9) performing a mechanical mordanting operation with Scotch-Brite or, as an alternative, with a bath in a hydrochloric acid solution. This operation eliminates the glossy surface film of resin from the moulded surface without changing the roughness and ensures the grip of the coating that will make the surface of the cylinder to be treated by copper and nickel electroforming conductive. In order to be able to carry out the electroforming treatment on the moulded grooved cylinder (1 9) and ensure an excellent quality result on the treated pieces, with respect to the classic treatment, normally made by firms according to what is stated in the technical documentation (TRATTATO Dl GALVANOTECNICA II, E.BERTORELLE, HOEPLI EDITORE), the following operations have been carried out also introducing a specific expedient in the standard nickel electroforming process.

1 d) The moulded grooved cylinder (1 9) is degreased by dipping in a solution of hydrochloric acid HCL and distilled water for 2 minutes and successively rinsed three times with running water. Composition of the solution: l OOOcc distilled water H ₂ O+20% hydrochloric acid HCL;

2d) the moulded grooved cylinder (19) is dipped in a solution of 1000 cc distilled water H ₂ 0, 45cc hydrochloric acid HCL, 3.3 grams tin chloride (II) SnCI ₂ for 4 minutes to improve the grip of the subsequent copper and nickel deposit;

3d) to make the surface of the moulded grooved cylinder (19) to be covered in the copper and nickel electroforming conductive, one sprays with a double-nozzle gun the specially elaborated solutions: Concentrated solution 1 ;

4d) Into a 1000 cc phial one pours 500cc distilled water and 1 80 g silver nitrate melting it, and adds 280 cc ammonia NH ₃ at 28%. One stirs everything and adds distilled water until reaching 10OOcc. One stores the concentrated solution 1 in a dark glass bottle. Concentrated solution 2;

5d) Into another 1000 cc phial one pours 500cc distilled water and adds 100 g caustic soda NaOH, stirs everything generating an exothermic reaction. After the cooling of the solution one adds 106 cc ammonia NH ₃ at 28% and distilled water until reaching 1000 cc. One stores the concentrated solution 2 in a dark glass bottle. Reducing solution 3;

6d) Into a container one pours 3000cc distilled water and 90 g cane sugar, bringing to boil with a lid on the container. One then leaves to cool. One adds 1 3 cc formaldehyde at 40% and 5 cc nitric acid HN0 ₃ . One pours into a 5-litre container the prepared reducing solution. One pours into another container already filled with 2250 cc distilled water, 108 cc of the solution 1 and 94cc of the solution 2;

7d) From the two containers the two products are sucked by means of a pneumatic two-nozzle spray gun that nebulises the two components and allows to separate the silver on the surface of the moulded grooved cylinder (19), making the whole sprayed surface conductive;

8d) Electroforming in the bath of copper with sulphuric acid solution, for four hours in order to reach on the external surface (diameter) of the moulded grooved cylinder (19) a thickness of 0.25 mm;

9d) Reactivation of the cylinder before the nickel electroforming for about eight minutes, in a solution made up of 1 OOOcc distilled water H ₂ 0, 50cc sulphuric acid H ₂ S0 ₄ and 5 cc 130-volume hydrogen peroxide;

l Od) Rinsing the moulded grooved cylinder (19) with running water for three times;

1 1 d) Electroforming in the bath of nickel with fluoborate, with the addition of a hardener called toluene sulfonamide 0.044 grams per litre. The temperature of the bath must be of 43 C°. The moulded grooved cylinder (19) must remain in the bath for four hours in order to reach on the external surface (diameter) a thickness of about 0.1 5 mm, with a hardness equal to or greater than 45 HRC; 1 2d) Hard chromium plating by galvanic process with a thickness of 20-30 microns and a hardness of the external diameter equal to or greater than 65 HRC.

1 3d) Final visual control and balancing check with a balancing machine according to the values required on the moulded grooved cylinder (19) by the technical specifications.

[0024] The treatment described and provided on the moulded grooved cylinder (19) in resin makes the whole surface to be treated conductive, by means of the application of a silver sulphate film. On this surface is then laid a copper layer that allows to receive the thickness layer of hard nickel that one wants to apply. As for the cylinder, being it difficult to manage to lay on the screw bottom a suitable nickel thickness, it was necessary to provide on the external surface a nickel thickness equal to at least 0.1 5 mm in such a way as to ensure at least some hard nickel microns on the groove bottoms. To eliminate the wear due to the dragging of the reel on the external surface of said cylinder (1 9), there is also the application of 20÷30 microns hard chromium on the latter. The wear problems that also occur on the top and tail ends and on the screw crossings are solved by said overmoulding of two tempered metal inserts in the ends (13, 14), and by gluing the inserts (20, 21 , 22) on the pockets generated on the piece by the silicone rubber cavity (1 0).

Reference

(1 ) Upper flange forming the top base of the cylinder.

(2) Lower flange forming the tail base of the cylinder.

(3) Conical pin for forming the keying seat of the cylinder for the driving aisle of the spooling machine. On this pin it is possible to position a finished bush, which will be overmoulded by the compound cast into the mould.

(4) Central body of the mould, with the internal diameter being 6 mm greater than the external diameter of the sample cylinder, so that the RTV silicone rubber cavity has a thickness of 3 mm in the cylindrical binder, which makes the demoulding operation possible. (5) Sample cylinder with centering hole and with pockets in the crossings of the screws for housing the inserts.

(6) Pin for phasing the sample cylinder with the mould.

(7) Hole for injecting silicone rubber into the mould.

(8) Air outlet vents from the mould in the casting phase of the RTV silicone rubber. (9) Mould

(10) Single-piece RTV silicone rubber cavity turned over after demoulding.

(1 1 ) Sector for balancing release on the moulded cylinder.

(12) Sector for balancing release on the moulded cylinder.

(1 3) Tempered plate insert to be positioned on the top end (negative) of the silicone rubber cavity.

(14) Tempered plate insert to be positioned on the tail end (negative) of the RTV silicone rubber cavity.

(1 5) Casting hole of the polyurethane resin compound filled with aggregate.

(1 6) Electric motor for the rotation of the mould with inverter

(17) Joint for positioning and rotating the mould for centrifugation.

(1 8) Support with rotating live centre to perform the rotation of the mould safely.

(19) Moulded cylinder in polyurethane compound.

(20) Ceramic insert for the first screw crossing.

(21 ) Ceramic insert for the second screw crossing.

(22) Ceramic insert for the third screw crossing.

(190) Thread-guiding screws.