GB2277283A - Coiling apparatus - Google Patents

Abstract

Fine metal wire or tubing (18), particularly for incorporation in jewellery or ornaments, is coiled into a helix by being wrapped around a rotary mandrel (20) having a helical channel (25) in its surface. The wire or tube (18) is pressed into the channel by a former (16) having a complementary channel in an opposing surface, the former being movable longitudinally with the tube to be coiled, over at least a short distance. The former is carried by a rotatable cap (14) at one end of a large rod (12) controlling the spacing between the former and mandrel. The mandrel is carried by a bar (2) which is movable both axially and angularly relative to a pair of supports (8), which may in turn be secured to a workbench. The bar (2) may have a handwheel (4) fast with it at one end or be motor-driven. <IMAGE>

Description

COILING APPARATUS This invention relates to apparatus for coiling metal wire or tube into helices of finite length.

In the manufacture of jewellery and ornaments, there is a demand for a simple machine by means of which short lengths of metal tubing can be converted into helical coils of chosen diameter, the turns of which coils may then be severed by an axial cut into loops or part sections. These loops in turn may be twisted so that their ends lie opposite each other, with the single turn of each loop lying in a plane.

It is known to make tubes from flat metal strip by folding the strip along its axis by passing it through a die in which the strip edges are caused to abut to define a tube of circular cross-section. The strip is pulled through the die by means of a capstan driven by a motor.

The capstan may take the form of a cylinder with a helical groove in it, as disclosed in US-A-2 229 149.

The tube issuing from the die is wrapped around the groove in the capstan, which is able to move longitudinally as well as angularly. This ensures that the tube meets the capstan tangentially to the groove, and in line with it. This apparatus consumes so much energy in deforming the strip and tube that it has to be motor driven, and to be of relatively-massive construction, so as to be able to withstand the forces exerted on it in use.

The present invention aims at providing apparatus which can be operated manually or be motor-driven to coil lengths of preformed wire or tube into helical coils of finite length. Accordingly the present invention provides apparatus for coiling a short length of metal tube or wire into a helix, comprising a rotary mandrel having a helical channel, and a former presenting a surface of substantially U-shaped cross-section adapted to extend transversely to the axis of the mandrel and forming with the channel a space of suitable crosssectional shape of a size commensurate with the outside diameter of the tube or wire to be coiled, the mandrel and former being movable relatively to each other.

The mandrel and former may be moved relative to one another along the axis of the mandrel as it is rotated merely by the presence of the tube or wire interengaging with both, but preferably portions of the former are engaged by partial overlap between those portions and the crests of the ribs between adjacent turns of the channel on the mandrel.

The space is usually conveniently of circular crosssection, but it may be of elliptical or oval crosssection if the desired cross-section of the coiled tube or wire is other than circular.

The present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic perspective view of one form of tube-coiling apparatus of the present invention; Figure 2 is a perspective view, from a nearer and different view point from Figure 1, showing the mutual engagement of the tube being coiled with the former and mandrel; Figure 3 is a sectional view of parts of the apparatus of Figure 1, showing the cross-section of the tube being coiled with the former and mandrel; Figure 4 is a side elevation of the essential parts of another form of apparatus of the present invention; Figure 5 is a plan view of the apparatus shown in Figure 4, and Figure 6 is an end elevation showing the stands used for supporting the apparatus shown in Figures 4 and 5.

In the accompanying drawings, those components which are the same in different figures retain the same references.

In the apparatus shown generally in Figures 1 and 2, a bar 2 is intended to be rotated manually by means of a handwheel 4. The bar 2 extends through self-lubricated bushes 6 in uprights 8 which are secured to a brace 10 carrying a mounting 13 in which is a screw-threaded rod 12 having a cap 14 at its upper end. Cap 14 is coupled through a dove-tail slidable connection with a former 16 extending transversely to the axis of bar 2 and in close proximity to it. The rod 12 extends through the centre of the hollow cylindrical mount 13 and is coupled through a rotary coupling to a knurled adjustment sleeve 15, so that the height of former 16 above the brace 10 can be adjusted by rotation of sleeve 15. The spacing between the former 16 and the outside diameter of bar 2 is determined by rotating sleeve 15 (which has an internal screw-thread engaging the external thread on the mount 13), thus raising or lowering the rod 12 and the cap 14.

In use of the apparatus, extending in line with a Usectioned channel in the top of former 16, is a short length of tube 18 which may, if the tube is to be formed into a piece of jewellery, be formed of, or plated with, any precious or decorative metal.

In a section 20 of bar 2 intermediate the uprights 8, the bar is formed with a deep helical channel 23 between adjacent turns of a rib 22 having a pitch circle the same as, or different from, the outside diameter of bar 2. The cross-sectional shape of this channel is substantially semi-circular. As can be seen most clearly in Figure 3, the channel 17 in the upper surface of former 16 is also substantially semi-circular in cross-section. The crest of the rib 22 has rebates 23 on both side and the upper edges of the channel 17 are dimensioned to fit neatly into the rebates 23, as shown in Figure 3, so that when the former 16 has been raised to effect engagement between former 16 and channel 23, there is a substantially-circular opening formed having a diameter substantially the same as the diameter of the tube 18 to be coiled, into which opening the tube 18 fits snugly.

Although the bar 2 is shown as having an integral helical channel, the helix is preferably provided by a separate member, in driving connection at one end with that portion of bar 2 movable with handwheel 4, and nested at its other end in a tubular support forming a continuation of bar 2.

As indicated somewhat diagrammatically in Figures 1 and 2, the bar 2 has a tube clamp 24 secured to it by means of a screw 26 extending radially to bar 2. The jaw 24 of the clamp extends in cantilever fashion over one end of the helical channel 23 so that, at the start of a coiling operation, one end of a short length of tube (or wire) may be clamped between jaw 24 and the base of the channel by tightening screw 26 by any suitable means. In order to accommodate the outward projection of the clamp, the former 16 is movable axially of its length relative to cap 14, as by means of the step-section in the base of the former 16, which engages into roller 19 by means of a matching shape rebate set in cap 14. As the handwheel 4 is turned in the appropriate direction to start coiling the tube 18, the former 16 is moved longitudinally under the effect of friction between it and tube 18. If the length of tube to be coiled is greater than the length of former 16, the coiling process is stopped when the trailing end of the former 16 reaches cap 14. The column 12 is lowered by turning sleeve 15 until the former can be dragged back to its start position, with its leading end over the cap 14. The column 12 is then raised again, to establish the operating conditions, and the coiling restarted. The handwheel 4 is of diameter appropriate to the force needed to be applied by the operator in coiling the wire or tube 18.

Because cap 14 and rod 12 can rotate freely about a vertical axis, the channel 17 tends to align itself naturally with the channel 23. With the former 16 being fixed relative to the axis of bar 2, as the mandrel is rotated the bar 2 is forced to move longitudinally of the bearings in uprights 8 by virtue of the interengagement of former 16 and mandrel 20. This process may continue for as much or as little as is required of the axial extent of mandrel 20.

Although this has not been shown in the drawings, the mandrel 20 may be formed with an axially-extending slot intended to accept a circular saw blade edge, which can be moved along the length of the mandrel to cut the helical tube formed by the coiling operation into individual loops, each of which can be removed from the mandrel easily, either by rotation along the length of a dismantled mandrel, or by flexure of the loops to permit them to be expanded to a size whereafter they can be moved along the mandrel and off the end. Once each loop has been removed, its ends may be gently twisted into the same plane as each other to form a planar loop having a small interruption in its periphery. Such loops are useful in themselves for incorporation in jewellery and ornaments, substantially without any further work being done on the loops, if their surface finish is acceptable; otherwise they may be polished or otherwise treated.

In that embodiment of the invention shown in Figures 4 to 6, the mandrel 20 takes the form of a cylindrical block 27 secured to bar 2 in a manner preventing it from moving either axially or angularly with respect to the bar, as by means of stops 28 and 30. Either the mandrel block 27, or one of the stops 28, 30, may have a tube clamp associated with it to function analogously to clamp 24 of the Figures 1 and 2 embodiment. It will be seen that the diameter of mandrel block 27 is significantly greater than the diameter of bar 2. This is accommodated by lowering the rod 12 in brace 10 until it reaches the position shown in Figure 4 in which the shoulders of the channel 17 in former 16 are in contact with, or just spaced from, the rebates 23 on each side of rib 22 defining of the helical channel 25 in mandrel block 27.

Another major difference between the two embodiments is that the axial extent of the mandrel shown in Figure 4 is significantly less than in Figure 1, so that only fewer, but larger, turns of coiled tube can be made in a single operation. In the two embodiments illustrated, the actual peripheral length of each helical channel in the two embodiments is the same and corresponds to a standard one metre length of the small-diameter metal tubing used in jewellery and fashion ornaments. If tubing (or wire) of a different outside diameter is to be coiled, then both the mandrel 20 and the former 16 have to be replaced by correspondingly-dimensioned alternatives, but functioning in the same manner.

In this embodiment, as can be seen more clearly in Figures 5 and 6, the former 16 is relatively-short, and has a stop 33 projecting from it. After a short length of tube 18 has been coiled, the former moving with it is halted by contact of stop 33 with cap 14, after which the tube has to be dragged along the stalled channel 17, imparting a burnishing effect on part of the tube surface.

Another minor change, and one which can be seen most easily from Figure 6, is that the apparatus of the present invention may include, or be supported by, a stand having basically triangular-shaped end plates 34 having flanged bases 36, which flanges have apertures 38 extending through them by means of which the end plates 34 may be bolted to a workbench or other support structure.

It will also be appreciated that the handwheel 4 having a knurled cylindrical surface 40 may be replaced by an appropriately-dimensioned handwheel in the form of a circular rim connected by integral spokes to a central hub secured in turn to bar 2, or by a crank handle.

In the embodiment of the invention shown in Figures 1 and 2 the mandrel 20 is integral with bar 2, and has the same outside diameter, but this is a special case and not suited for flexible operation. Preferably the mandrel is separable from the bar, and most preferably the bar is itself in two axially-aligned sections which can be secured to the mandrel to form a rotatable mandrel assembly journalled in an appropriate framework. One such bar section may incorporate a drive dog or like coupling to entrain and rotate the mandrel. The driving bar section may be rotated by a handwheel, a motor-driven gear or other system. Suitable sliding bearings may enable the two bar sections to be axially slid apart, while retaining the mandrel on one of them, and so opening up a gap through which a helix of coiled wire or tube may be removed from the apparatus.

In both embodiments illustrated, the mandrel is designed to be turned by hand. It is preferable in some applications (though it adds to the cost and complexity of the apparatus) to provide means whereby the mandrel may be rotated by motor in a fashion generally more even than turning by hand.

Likewise in both embodiments illustrated, the shaft incorporating or supporting the mandrel is intended to move axially with respect to the frame, and the support for the former is fixed relative to the frame in that axial direction. It is possible to construct the apparatus to work the other way round, e.g. with an axially fixed shaft and with the former support mounted on a slideway or the like enabling it to move along the shaft as the mandrel is rotated.

Claims (9)

1. Apparatus for coiling metal tube or wire into a helix, comprising a rotary mandrel having a helical channel, and a former presenting a surface of substantially U-shaped cross-section adapted to extend transversely to the axis of the mandrel and forming with the channel a space of suitable cross sectional shape of a size commensurate with the outside diameter of the tube or wire to be coiled, the mandrel and former being movable relatively to each other along the axis of the mandrel.

2. Apparatus as claimed in Claim 1, in which the mandrel is mounted on, or forms part of, a cylindrical bar adapted to be journalled in two supports, one on each side of the mandrel, in which it is movable both axially and angularly.

3. Apparatus as claimed in Claim 2, in which the bar is formed of two axially-aligned separable sections.

4. Apparatus as claimed in Claim 2 or 3, in which the mandrel is separable from the bar and is of greater outside diameter, including means for detachably securing at least one end of the mandrel to the bar in a manner preventing movement relative thereto.

5. Apparatus as claimed in any one of claims 2 to 4 in which the supports for the bar and mandrel have feet adapted to be secured to a workbench or like surface.

6. Apparatus as claimed in any preceding claim, in which at least one end of the bar carrying the mandrel has a handwheel fast with it.

7. Apparatus as claimed in any one of the preceding claims, in which the former is carried on one end of a large-diameter rod movable along an axis which is perpendicular to that of the mandrel, the rod having at one end a rotatable cap carrying the former, which is movable along an axis extending substantially perpendicular to the plane containing the axes of the screw and mandrel.

8. Apparatus as claimed in Claim 7, in which the former is movable relatively to the cap along only a short distance which is significantly less than the developed length of the channel in the mandrel.

9. Apparatus for coiling tube or wire and substantially as hereinbefore described with reference to the accompanying drawings.