GB2074201A

GB2074201A - Friction Spinning Rollers

Info

Publication number: GB2074201A
Application number: GB8112353A
Authority: GB
Original assignee: Platt Saco Lowell Ltd
Current assignee: Platt Saco Lowell Ltd
Priority date: 1980-04-19
Filing date: 1981-04-21
Publication date: 1981-10-28
Also published as: GB2074201B

Abstract

A roller for a friction spinning apparatus comprises a hollow externally coated perforated base member less than 0.125 inch.thick, the perforations provide a ratio of hole to total area of at least 25%. The coating may be chrome dioxide plasma less than 0.004 inch thick and the holes less than 0.03 inch diameter. <IMAGE>

Description

SPECIFICATION Apparatus for Open-end Spinning Yarn This invention relates to rollers for friction spinning apparatus.

There are now several patent specifications showing different forms of friction spinning apparatus in which fibres are spun into a yarn by being deposited on and twisted by a moving perforated surface.

The surface generally is formed by a hollow perforated roller or base member. However, the only specification which gives details of the structure of the roller and its surface is British Patent Specification No. 2 023 1 96-A of Vyzkumny Ustav Bavlnarsky. This shows various formations of perforations or holes in the surface and mentions that the base member can be coated with several possibilities for coatings being given. Other patents show the roller and its surface only schematically and none has yet formulated the requirements for a perforated surface of this kind.

The present invention therefore has as its object a perforated roller providing a surface for an apparatus of the above kind, the roller exhibiting the optimum characteristics for successfull spinning.

The invention is therefore characterized in that the thickness of the base member is less than 0.125 inches (3.2 mm) and the percentage of hole area to total surface area of the base member, measuring the hole area at the smallest cross-section of each hole, is greater than 25%.

The invention will become more apparent from the following description thereof in conjunction with the accompanying drawing showing the arrangement of holes in greatly enlarged form.

In our Published British Application No. 2 042 599 is disclosed an apparatus of the above kind including only one perforated roller. The roller of the present invention is specifically designed for use in this apparatus but could also be used in other apparatus of this kind.

The roller comprises a cylindrical shell formed of a readily worked metal or other strong support material. Preferably the shell is of aluminium as this is very easy to work and provides the necessary strength, but mild steel, brass or bronze can also be used.

The thickness of the shell is kept to a minimum to provide the necessary strength to support the structure. A thickness of 1/8 inch (3.2 mm) is too great in that it unduly restricts the passage of air through perforations. A thickness of 1/16th inch (1.6 mm) is fully satisfactory.

The strength of the roller which is necessary is that to avoid inadvertent deformation during handling since forces during spinning are relatively small.

The holes in the roller must provide the minimum resistance to the passage of air through the surface of the roller while preventing the passage of fibres or the trapping of any part of a fibre. In the preferred embodiment the holes are of .024 inch diameter (0.6 mm), but they may be as large as 0.030 inch (0.75 mm) and as small as 0.020 inch (0.5 mm). The holes are drilled mechanically with cylindrical shape as by a conventional drill.

The required number of holes is the maximum which can be provided consistent with leaving sufficient material towprovide the necessary strength. The maximum number of holes can be provided if, as shown in the drawing, the second one is offset from the first so that the centres lie on a line at approximately 450 to the first row. With holes of 0.024 inch diameter and a thickness of aluminium shell of 0.062 inch the minimum spacing of centres (Dimension B) is of the order of 0.046 inch in each longitudinal row with a spacing of 0.023 inch (half of Dimension A) from a centre in one row to the adjacent centre in the next circumferential row. This gives a total of 913 holes per square inch and 41% hole area.To obtain satisfactory air flow conditions a hole area of at least 25% is desirable and preferably greater than 30%. 30% hole area can be achieved using 0.020 inch holes at the same centre spacing as above.

The above percentages of hole area are calculated by measuring the area of each hole at its smallest cross-section. In this case the holes are cylindrical and hence the cross-section is constant.

Examples of suitable hole configuration are set out in the following table:

A inch B inch D inch Holes/sq. in % Hole Area 0.036 0.056 inch Holes/sq. in % 1,000 Area ~ 0.046 0.024 913 41.3 0.036 0.056 0.020 1,000 31.4 0.048 0.046 0.024 913 41.3 L I 0.024 1,000 45.2 Thus in a roller of 40 mm (1.57 inches) diameter there are preferably 88 holes per circumference arranged in 201 rows.

In order to provide a surface having suitable spinning characteristics and co-efficient of friction relative to fibres, and is resistant to wear the aluminium shell is coated with a ceramic material, preferably chrome-dioxide (Cr302) by a plasma coating method. Such a coating can be provided by Union Carbide under their classification LC4. The thickness of coating is preferably less than 0.004 inch and preferably of the order of 0.001 to 0.002 inch. The coating is allowed to enter the holes to give a rounded edge to the mouth of the hole but is thin to prevent undue restriction of the holes by the coating. Other ceramic coatings by plasma spray method or discharge gun method are possible.

Claims

1. A roller for a friction spinning apparatus comprising a hollow perforated base member having on its outer surface a coating, characterized in that the thickness of the base member is less than 0.125 inches (3.2 mm) and the percentage of hole area to total surface area of the base member, measuring the hole area at the smallest cross-section of each hole, is greater than 25%.

2. A roller as claimed in claim 1, wherein the thickness is of the order of 0.063 inches (1.6 mm).

3. A roller as claimed in claim 1 or 2, wherein the hole area is greater than 305/o.

4. A roller as claimed in claim 1,2 or 3, wherein the diameter of the holes is less than 0.03 inches (0.75 mm).

5. A roller as claimed in claim 4, wherein the diameter of the holes is of the order of 0.024 inches (0.6 mm).

6. A roller as claimed in any preceding claims, wherein the holes are of cylindrical shape.

7. A roller as claimed in any preceding claim, wherein the thickness of the coating is less than 0.004 inch (0.1 mm).

8. A roller as claimed in any preceding claim, wherein the base member is coated with a ceramic material.

9. A roller as claimed in claim 8, wherein the ceramic coating is a plasma coated chrome dioxide.

1 0. A roller as claimed in claim 1 and substantially as hereinbefore described.