GB2145967A - Spinning head for plastics filaments, means for treating filament with liquids - Google Patents

Abstract

A die head for extruding continuous filaments of plastics material is provided which has a generally cylindrical configuration and comprises a spinneret plate 14,117, of annular form. The die head includes flow passages 16,119, for directing plastics material supplied from an extruder to said spinneret plate. There is also provided a liquid treatment dispensing arrangement comprising a chamber arranged to receive a supply of liquid treatment there and to release said liquid treatment at an edge of said arrangement. The arrangement is located between a die head and a first take off roller (21) such that each and every filament (F) drawn from the die head is continuously in contact with the liquid treatment at the said edge of said arrangement whilst the die head is operational. <IMAGE>

Description

SPECIFICATION Die head for extruding continuous filaments This invention relates to apparatus for extruding continuous filaments and, more particularly, to the extrusion of continuous filaments of plastics materials.

It is well known in the art to extrude continuous filaments from a die head and wherein the die head has the general configuration of a rectangular block, plastics material is supplied from an extruder to an inlet in one face of the block, passages in the block distribute the plastics material in the length direction of the block and in the direction twoards that face of the block opposite to the supply inlet and, at that face of the block remote from the inlet, the diverted plastics material is extruded through the openings in a spinneret plate and the extruded filaments are collected by a winding mechanism.

Disadvantages of the conventional rectangular die head reside in the problem of maintaining the rectangular block at uniform temperature and in the restrictions on the size of the die head, primarily due to the fact that as the length dimension of the die head increases, to increase the length of the spinneret plate, the problem of uniformally distributing the supply of plastics material to the spinneret plate increase, the residence time of the plastics material in the die head increases, and the problems of maintaining the block at uniform temperature increase.

According to the present invention there is provided a die head for extruding continuous filaments of plastics material characterized in that, the die head has a generally cylindrical configuration, the spinneret plate has an annular form, and the die head includes flow passages for directing plastics material supplied from an extruder to said spinneret plate.

In one embodiment the spinneret plate has the axes of its openings arranged generally parallel to the axis of the head.

In an alternative arrangement the axes of the openings in the spinneret plate extend generally radially to the axis of the head.

In one embodiment in accordance with the invention plastics material from the extruder is supplied to a single radial inlet to the die head and the die head includes an annular chamber of varying radial depth, to assist in presenting a substantially uniform pressure in the plastics material supplied to the spinneret plate.

In an alternative arrangement the die head includes a single inlet for plastics material and said inlet communicates with so-called "family tree" within the die head and whereby the plastics material is so split by the flow passages of the family tree as to be supplied to circumferentially spaced apart locations adjacent the spinneret plate via paths of equal length.

In the production of continuous filaments it is advantageous to apply a lubricant or other liquid treatment to the filaments and, in order that each filament can have the liquid treatment applied thereto, it is most advantageous if the liquid treatment is applied to the filaments before the filaments are bunched up on the winding rollers.

Thus, the liquid treatment is most advantageously applied to the filaments between the spinneret plate and the first wind-up roller.

In the past, application of liquid treatment to the filaments between the spinneret plate and the first wind-up roller has only been possible by spraying.

As is well known in the art there are many disadvantages to spraying, the principal disadvantages being that the liquid treatment is applied to the filaments as droplets and is, therefore, not uniformally distributed along the lengths of the filaments, and the apparatus must include means for collecting those droplets of the spray which do not impinge and adhere to the filaments. Because the filaments are spaced apart at the spray location less than 50% of the liquid treatment in the spray will adhere to the filaments and whilst many prior art systems will include a collecting and re-cycling arrangement there is always the danger of contamination of recirculated liquid treatment material.

According to this aspect of the invention there is provided a liquid treatment dispensing arrangement comprising a chamber arranged to receive a supply of liquid treatment there and to release said liquid treatment at an edge of said arrangement, the arrangement being located between the die head and the first take off roller such that each and every filament drawn from the die head is continuously in contact with the liquid treatment at the said edge of said arrangement whilst the die head is operational.

When the die head is of cylindrical figuration the liquid dispensing arrangement conveniently has an annular, disc like, configuration with the said chamber releasing liquid treatment along a periphery of the arrangement and with such a construction the arrangement is supported within the cone of filaments being drawn from the die head to the first collection roller.

In one embodiment the said liquid dispersing arrangement is supported by the die head but in an alternative and preferred arrangement the arrangement is supported by an arm which extends, from a fixed part of the machine frame through the filaments.

The invention will now be described further by way of example with reference to the accompanying drawings in which the single figure shows, to the right hand side of the centre line one construction in accordance with the invention and to the left hand side of the centre line a second construction in accordance with the invention.

In the embodiment illustrated to the right of the centre line a die block 11, of annular form, is arranged with its axis vertical and concentrically supports a mushroom 12, via spiders 13, which allow the cooling air to be passed up the bore of the block 11 and diverted by the head of the mushroom 12 towards filaments F issuing from an annular spinneret plate 14 set concentrically in the upper surface of the die block 11.

The die block 11 is supplied with plastics material from an extruder (not shown) and discharges said plastics material via a duct 16 to a "family tree" distribution system formed by four stacked annular plates 17, 18, 19 and 20, concentric with the axis of the die head 11.

The "family tree" construction defined by plates 17, 18, 19 and 20 may conveniently be identical with the family tree construction illustrated in Figures 7, 8, 9, 10 and 11 of co-pending European Patent Application No. 83301641.3 filed 24 th March, 1983 and whereby, the single supply via bore 16 is distributed, via arcuate channels in the radial faces, and bores through the thickness of, the stacked plates 17, 18, 19 and 20 to 16 outlets on the upper surface of the plate 20 equally spaced circumferentially about the upper surface of the plate 20, via paths of equal length.

The outlets for plastics material at the upper surface of the plate 20 discharge through a static mixer 15, again of annular form and located directly beneath the spinneret plate 14 whereupon an intimate mixing of the plastics material is effected before the said material is released to the spinneret plate 14.

The continuous filaments F drawn from the spinneret plate 14, cooled by the radial air released between the upper surface of the die block 11 and the under surface of the mushroom 12, pass over a first collecting roller 21.

Between the upper surface of block 11 and the roller 21 the filaments F are engaged by a liquid treatment arrangement comprising two disc like members 22 and 23, secured together by screws 24, the member 23 being rigidly supported concentric with the axes of the die block 11 by an arm 25 secured to a fixed part of the machine frame M.

The arm 25 is of narrow width, viewed in the planned direction of the die head 11, so as to pass between filaments F with the minimum of contact therewith and without unduly deflecting adjacent filaments F.

The disc like member 22 is supported in spaced apart relationship from disc like member 23 by radial walls 26, of small circumferential thickness, and the said disc like members 22 and 23 define between them an annular chamber, outwardly of the ribs 26, which reduces in depth towards the peripheries of the discs 22, 23.A pipe 27 pumps liquid treatment from a supply source (not shown) to the central regions of the chamber defined between disc like members 22 and 23, the pipe 27 being located in a slot 25a in arm 25 where the said pipe passes through the paths of filaments F adjacent the arm 25, so as to prevent contact between the pipe 27 and the filament F, and liquid treatment supplied by pipe 27 to the inner regions of the chamber between disc like members 22 and 23 passes radially outwardly of said chamber, between the ribs 26, and into the outer regions of said chamber where the reducing depth of the chamber ensures a substantially uniform pressure in the liquid treatment in the circumferential direction.

The embodiment described above operates as follows: Plastics material supplied from the extruder to bore 16 is distributed by the family tree formed by plates 17, 18, 19, 20 and released at the 16 outlets, equally spaced circumferentially about the upper surface of plate 20, into the static mixer 15 where said plastics material is effectively mixed before being passed to the spinneret plate 14. By this means the plastics material supplied to the spinneret plate has arrived via paths of equal length and has a relatively uniform thermal history, the ideal conditions for the extrusion of filaments of uniform and continuous characteristics.

Further, as the die block 11 has an annular configuration, there is little difficulty in maintaining the block 11 at uniform and constant temperature.

The filaments F issueing from the spinneret plate 14 are collected by the first collecting roller 21 and, in issueing from apertures spaced around the spinneret plate 14, the filaments F between plate 14 and roller 21 define a substantially hollow, conical configuration within which the liquid treatment arrrangement is supported by arm 25.

The discs 22 and 23 are so located in the axial direction of the cone of filaments F that each filament F contacts at least the periphery of disc 23 and is slightly deflected thereby. Liquid treatment, supplied by pipe 27 and flowing outwardly between discs 22 and 23 is, via the reducing depth of the chamber between discs 22 and 23, released at the outer regions of said chamber uniformly about the periphery of the gap between discs 22 and 23 and, in effect, forms a "bead" of liquid through which, or against which, each filament F passes before engaging the disc 23.

Thus, by this means, each filament F has liquid treatment applied continuously along the length, the liquid treatment is applied to the filaments before the filaments engage the disc 23 and therefor the said filaments are lubricated and can pass through quite substantial deflections in passing around the periphery of the disc 23 without sustaining damage.

Although the die block 11 is illustrated as being of one-piece construction, for illustration purposes, it will be appreciated that said block will be of composite form to allow the plates 17, 18, 19, 20, and mixer 15 and spinneret plate 14 to be securely supported in the locations illustrated.

In the example illustrated in the drawings to the left of the centre-line the die head comprises a substantially solid core member 111 with a major uniform diameter section 112 and a reduced section 113, and a tubular member 114 of such bore diametere as to receive diameter section 112 of member 111 in fluid tight relationship therein.

When member 111 is assembled with member 114 as illustrated in the drawings and when a disc like end plate 115 is secured to the upper end of member 111 via bolts 116, the end regions of tubular member 114 are spaced from the end plate 115 and an annular spinneret plate 117, with an annular static mixer 118 radially inwardly thereof, is located and retained in the space between member 114 and end plate 115.

The shoulder 112a between major diameter section 112 and reduced section 113 of member 111 lies in a plane inclined to the axis of the member 111 and upwardly of the highest point of shoulder 112a (as viewed in the drawings) the reduced section is machined to provide a corrugated profile as can be seen in the drawings.

The reduced section 113 thus forms a chamber within the bore of member 114, between the shoulder 112a and end plate 115, a bore 119 through member 114 opens to the lower regions of the chamber (as viewed in the drawings) and allows plastics material supplied from an extruder (not shown) to be discharged into said chamber, and the plastics material leaves said chamber by flowing between the upper regions of tubular member 114 and end plate 115 and, thereby, radially outwardly through the static mixer 118 and through radial apertures in the spinneret plate 117.

The special shape given to reduced section 113 initially encourages circumferential as well as axial flows in the plastics material in the lower regions of the said chamber and, as the plastics material flows up the said chamber, the varying radial depth of the chamber, caused by the corrugated profiles of the reduced section 113, encourage circumferential flows in the plastics material so that the plastics material is presented to the static mixer 118 at substantially uniform pressure circumferentially of said mixer 118.

With this type of head the filament F issue radially from the spinneret plate 117.

A pedestal, defined by an annular flange 119 secured to end plate 115 by bolts 116 with an externally threaded shaft 120 upstanding therefrom, is concentric with the axis of the die head and supports a first liquid treatment arrangement and a second liquid treatment arrangement.

The first liquid treatment arrangement is defined by two members 121 and 122 secured on shaft 120 between two nuts 123 and 124.

The member 121 comprises an annular planar section 121a with an outwardly and downwardly depending skirt section 121b. In the like manner the member 122 comprises an annular planar section 122a with an outwardly and downwardly depending skirt section 122b but the member 122 further includes an upstanding annular wall 122c, pierced by a plurality of equally spaced apart radial bores 122d, which locate the members 121 and 122 to define an inner annular chamber between planar sections 121a and 122a and a chamber between skirt section 121b and 122b which reduces in depth towards the spaced apart peripheries of members 121, 122.

An annular body 124, of semi-circular cross sections, is attached to the periphery of members 121 and 122 and is made of a porous material.

A bore 120a in shaft 120 is open to a bore 111a in member 111 and a supply a liquid treatment supplied to bore 111a from a source (not shown) flows up bore-Il Ia, up bore 120a, through a radial bore 120b in shaft 120 into the annular chamber between members 121, 122 and said liquid treatment flows from said chamber through radial bores 122d into the chamber between skirt sections 121b and 122b and escapes therefrom through the porous body 124.

Filaments F extruded radially from the die head are passed around the porous body 124 before passing upwardly towards the collection roller 121 and as the surface of the porous body 124 is continuously wetted by the pressure liquid treatment passing therethrough each filament F is wetted and lubricated to pass around the body 124 with minimal damage.

The skirt 122b further includes an annular deflection plate 122e and pressure cooling air, supplied to axially extending bores 125 in member 111 from a source (not shown) and passing through bores 126 in flange 119 into the head space beneath member 122, is deflected by plate 122e through the filaments F issueing from spinneret plate 117 to cool said filaments.

The second liquid treatment arrangement comprises disc like members 127, 128, the member 127 being screwed onto the upper regions of shaft 120 and secured by a nut 129, and the member 128 being secured to member 127 by screws 130.

The member 128 includes downwardly depending radially extending ribs 128a, of small circumferential dimension, which space apart the members 127, 128 whilst allowing liquid treatment, released from the exposed upper end of bore 120a into the space between members 127, 128 to flow radially outwardly to release from the periphery of the chamber between members 127, 128 as "a bead" through which, or against which, the filaments F pass in contact before being taken up by roller 21.

It will be seen that with this arrangement the filaments F extruded radially from the die head are "turned" by the two liquid treatment arrangements before being taken up by roller 21, and in each case the filaments are lubricated by the liquid treatment before being deflected, thus to minimise damage to the filaments F.

As in the prior example it will be appreciated that the circular form of the die head is advantageous for maintaining the die head at uniform and constant temperature.

It will be appreciated that whilst in the said second embodiment of the invention the filament F may be turned through more than 90" between the spinneret plate 117 and the collection roller 21 by two liquid treatment arrangements more than two liquid treatment arrangements may be used to reduce the angle of turn imparted to the filaments F at each arrangement, whereby to further minimise damage to the filaments.

Claims (13)

1. A die head for extruding continuous filaments of plastics material, the die head having a generally cylindrical configuration and comprising a spinneret plate of annular form, the die head including flow passages for directing plastics material supplied from an extruder to said spinneret plate.

2. A die head according to Claim 1, wherein the spinneret plate has the axes of its openings arranged generally parallel to the axis of the die head.

3. A die head according to Claim 1, wherein the axes of the openings in the spinneret plate extend generally radially of the axis of the die head.

4. A die head according to any of the preceding claims, wherein the die head includes an annular chamber of varying radial depth, to assist in presenting a substantially uniform pressure in the plastics material supplied to the spinneret plate.

5. A die head according to any one of Claims 1 to 4, wherein the die head includes a single inlet for plastics material and said inlet communicates with a "family tree" within the die head and whereby the plastics material is so split by the flow passages of the family tree as to be supplied to circumferentially spaced apart locations adjacent the spinneret plate via paths of equal length.

6. A die head according to any one of the preceding claims, comprising means to apply a lubricant or other liquid treatment to the filaments.

7. A die head according to claim 6, wherein the means to apply the lubricant or other liquid treatment is arranged to provide the application to the filaments between the spinneret plate and a first wind-up roller.

8. A liquid treatment dispensing arrangement comprising a chamber arranged to receive a supply of liquid treatment there and to release said liquid treatment at an edge of said arrangement, the arrangement being located between a die head and a first take off roller such that each and every filament drawn from the die head is continuously in contact with the liquid treatment at the said edge of said arrangement whilst the die head is operational.

9. An arrangement according to Claim 8, wherein the die head is of cylindrical figuration the arrangement has an annular, disc like, configuration, and the said chamber is adapted to release liquid treatment along a periphery of the arrangement, the arrangement being supported within the cone of filaments being drawn from the die head ta the first collection roller.

10. An arrangement according to Claim 8 or Claim 9, wherein the arrangement is supported by the die head.

11. An arrangement according to Claim 8 or Claim 9, wherein the arrangement is supported by an arm which extends, from a fixed part of a frame through the filaments.

12. A die head substantially as hereinbefore described with reference to the accompanying drawing.

13. A liquid dispensing arrangement substantially as hereinbefore described with reference to the accompanying drawing.