Apparatus for feeding wire to wire processing machines

An apparatus for feeding wire to wire-processing machines, in which the wire is drawn off from a pay-off reel holding a wire coil and rotatable about a spindle and fed to a wire feeder upstream of the wire-processing machine, wherein at least one wire-deflecting device, via which the wire drawn off from the pay-off reel is guided and released towards the wire feeder, is connected downstream of the pay-off reel in the wire draw-off direction, and wherein a wire-storage device is provided upstream of the wire feeder, this apparatus presents a guide path, forming a closed circuit, on which the wire runs and the diameter of which can be altered between a smaller value corresponding to an inner radial position of the guide path and a larger value corresponding to an outer radial position of the guide path, wherein the guide path is spring-pretensioned towards the outer radial position.

PRIORITY CLAIM

The present application is a National Phase entry of PCT Application No. PCT/EP2011/004466, filed Sep. 5, 2011, which claims priority from German Application Number 10 2010 047 531.9, filed Oct. 5, 2010, the disclosures of which are hereby incorporated by reference herein in their entirety.

FIELD OF THE INVENTION

The invention relates to an apparatus for feeding wire to wire processing machines.

BACKGROUND OF THE INVENTION

The intermittent feeders used in wire-processing machines draw off the wire from a wire coil placed on a pay-off reel, wherein they operate with high accelerations and brake applications. It is desired that the pay-off reel is to run as smoothly as possible, in order that the wire is continuously released. For this, deflecting means and/or swivel arms which are meant to compensate for irregularities in the drawing-off are usually used, as the very large mass of the wire coil for its part cannot be accelerated and decelerated very quickly.

However, the named remedial measures are often insufficient to ensure the desired smooth running of the pay-off reel or to achieve as little as possible to no movement of the swivel arm.

From DE 44 43 503 A1 an apparatus for feeding wire to wire-processing machines is known in which the wire coming from the pay-off reel is guided between the latter and the wire feeder of the downstream wire-processing machine in a loop, wherein the deflection of this loop is detected by a recognition unit. Besides the rotational movement for the unreeling, the pay-off reel can also perform a swivelling movement about the wire-feeding direction, the extent and direction of which is predetermined by the recognition unit. This makes it possible to compensate for the twisting of the wire, which is important in particular during the processing of hard-drawn wire types.

From JP 2004-122204 A a wire feeding is known in which a deflectable deflecting roller is used which is prestressed downwards in spring-loaded manner and functions similarly to a swivel an of a pay-off reel. The deflection of the deflecting roller is detected and the rotational speed of the pay-off reel is regulated accordingly.

In the wire-feeding apparatus, known from EP 0 255 507 B1, of the type named at the beginning, a spring-loaded, deflectable deflecting roller is likewise provided between a straightening rotor and a pay-off reel. In addition, after the straightening rotor, the wire is guided round in a freely running loop, the formation of which is monitored by means of switches. The spring-loaded, deflectable deflecting roller is associated with a sensing means which switches off the wire feeder and the straightening rotor when the length falls below a predetermined minimum value, while switches associated with the loop influence not only the conveying speed of the wire feeder, but also the rotational speed of the straightening rotor in the same direction.

Although these known apparatuses bring certain improvements with regard to a smoother running of the pay-off reels, it has been shown that the pay-off reel (and any swivel arm associated with it) still run far from smoothly in the case of intermittent draw-off movements.

SUMMARY OF THE INVENTION

An apparatus for feeding wire to wire-processing machines in which the wire is drawn off from a pay-off reel that holds a wire coil and rotates about a spindle and fed to a wire feeder upstream of the wire-processing machine, wherein at least one deflecting device downstream of the pay-off reel in the wire draw-off direction is provided via which the wire drawn off from the pay-off reel is guided and released towards the wire feeder, wherein a wire-storage device is provided upstream of the wire feeder that provides smoother running of the pay-off reel.

According to embodiments of the invention a wire-storage device defines a guide path, forming a closed circuit, on which the wire rests and is guided, and the diameter of which can be altered between a minimum value corresponding to an inner radial position of the guide path and a maximum value corresponding to an outer radial position of the guide path. In embodiments the guide path is spring-pretensioned towards adopting the outer radial position.

In embodiments of the invention, between the pay-off reel and the wire-processing machine, an additional wire-storage device which acts as a wire buffer from which the drawing-in movement can be operated, which contributes to a smoother running of the pay-off reel and any swivel arm associated with it. The intermittent draw-off force acts first on this wire-storage device in which, as a result of its guide path that can be altered in its radial position between an inner and an outer radial boundary position, and may be spring-pretensioned running towards the outer radial boundary position, jolts from the feeder of the wire-processing machine can be absorbed in spring-loaded manner and largely compensated for, before they can act with a then, however, significant attenuation (if at all) on the swivel arm of the pay-off reel for compensation there.

A feature and advantage of embodiments of the invention is that it is not necessary to use specific sensing means, such as are used when freely formed loops are employed to detect the current loop sizes in each case. Due to the design of the spring-pretensioning of the guide path, inside the wire-storage device its behaviour can in addition be designed such that the swivelling movement of a swivel arm associated with the pay-off reel is introduced only in the case of a comparatively large spring deflection.

In embodiments of the invention, one of the wire-deflecting devices used is provided in the form of a swivel arm, which is preferably associated with the pay-off reel, spring-pretensioned into a swinging-out direction. Such a swivel arm is combined with the further wire-storage device used according to the invention and they complement each other in such a way that a particularly smooth running of the pay-off reel can be achieved.

The wire-storage device can be attached to any suitable point upstream of the wire feeder in the apparatus according to the invention. However, it has proved particularly advantageous if the wire-storage device for its part is connected directly to the swivel arm or also immediately upstream of the wire feeder.

In embodiments of the invention the wire-storage device is rotatable about a spindle lying perpendicular to the wire-advance direction, aligned perpendicular to the spindle of the pay-off reel.

If in the invention the wire-storage device is attached directly to the pay-off reel, the spindle of the wire-storage device may be aligned approximately parallel to the spindle of the pay-off reel.

In embodiments of the invention, the wire-storage device is formed as a spring wheel, the guide path of which is defined by the radially outer ends of a large number of radially aligned compression springs attached to it. An ultimately uncomplicated structure of the wire-storage device is hereby achieved which can be produced at favourable cost and is extremely effective.

In embodiments of the invention, a spring wheel comprises two side parts, spaced apart from each other, the distance between which is smaller than the diameter of the radially aligned springs, wherein each spring is held in two recesses, arranged radially in both side parts and corresponding to each other in their position, the width of which (seen in the circumferential direction of the spring wheel) is smaller than the diameter of the spring, which is why the latter projects beyond the side parts on both sides. This creates a very simple seat for the radially arranged springs in the spring wheel that is easy to produce and yet extremely effective.

In embodiments of the invention, the wire-storage device is provided directly on a swivel arm associated with the pay-off reel, the wire is deflected, through approximately 180°, on the guide path of the wire-storage device.

In embodiments of the invention, the wire runs through 360° around the guide path of the wire-storage device.

In embodiments of the invention, the defining of the guide path in the wire-storage device with elements other than compression springs can preferably also be achieved by using radially aligned compression elements in the form of fluid-actuated spring elements, wherein in embodiments, the sides of the compression springs facing the circulating wire or the spring elements of the spring wheel are provided with caps made of wear-resistant material or with freely rotatable rollers. The wire-storage device for its part can be attached rotatably here, but can equally also be provided as a fixed, not rotatable device, as the use of wear-resistant caps or freely rotatable rollers on the sides of the compression springs hieing the wire or the spring elements of the spring wheel per se already makes it easily possible for the wire to run along the guide path then formed by these caps or the rotatable rollers in a circumferential movement relative to this.

In embodiments of the invention the guide path in the wire-storage device is formed by a circumferential layer consisting of an elastically compressible material, particularly preferably elastomeric material.

In embodiments of the invention, the compression springs are designed in the form of pistons, running in cylinders, which define the position of the guide path via the free ends of piston rods attached to them. Each piston or piston head and the associated cylinder bottom are formed from a magnetizable, preferably a permanently magnetic, material of identical polarization.

In embodiments of the invention, the wire-storage device comprises a large number of blades, attached around a central holding spindle, running radially outwards from the latter in an arc, freely projecting and consisting of spring-loaded material, which are arranged between two lateral walls (but are not attached to these) and the free end areas of which define the guide path as well as in each case running out into an end section curved in the circumferential direction of the wire. A simply constructed and yet very effective design is also achieved hereby for a wire storage device that can be used in the invention.

In embodiments of the invention, each blade rests, on its side lying in front in the circumferential direction of the wire, against a positioning element the radial position of which is adjustable and thus the length of the end section, running outwards from the latter, of the respective blade can be set. Thus, in a simple way and without large outlay on design, the lever arm of the end section of each blade projecting freely beyond the positioning element and thus also the rigidity of the blade active on the guide path can be set by corresponding adjustment of the positioning elements.

The blades can consist of any suitable and loadable elastic material. However, they are quite particularly preferably designed in the form of spring-steel blades.

DETAILED DESCRIPTION

InFIG. 1a basic side view of an embodiment variant of a wire-feeding apparatus1according to the invention is shown, such as can be used in a wire- or pipe-processing machine which works with a material from the coil2which rests on a rotatably driven pay-off reel3and is drawn off from the latter via deflecting means4and a swivel arm5.

The representation ofFIG. 1, between the swivel arm5and the processing machine, of which only one feeder6is basically indicated here, upstream of this a wire-storage device in the form of a spring wheel7is arranged which for its part has a spindle9lying horizontal as well as perpendicular to the direction of advance x of the wire8.

AsFIG. 1shows, the spring wheel7contains, distributed over its circumference, a large number of radially arranged and also radially acting spring elements10, preferably in the form of helical springs. These spring elements10may all have an identical shape.

InFIGS. 3 and 4, the structure of the spring wheel7is shown in detail. This has two circular side parts13which act as lateral limiting plates for the wire8and are spaced apart from each other by a distance α (seen parallel to the position of the spindle9). These side parts13are preferably produced from sound insulation sheets (of vibration-reducing composite material made of a viscoelastic plastic layer between two steel sheets, e.g. Bondal sheet from Thyssen Krupp Stahl), which is favourable particularly in the case of large diameters.

In these side parts13of the spring wheel7, in radial alignment and uniformly arranged over its circumference, rectangular recesses14are provided which act as seats for the spring elements10the spring ends11of which (cf.FIG. 3), in the assembled state, are bordered by stops12, which are the radially outer or inner end edges of the recesses14.

As can be seen fromFIG. 4, both the width B of each recess14(seen in the circumferential direction of the spring wheel7) and the distance α between the side parts13of the spring wheel7are in each case smaller than the diameter D of the spring elements10formed as helical springs. This results in the arrangement of the spring elements10shown in enlarged detail representation inFIG. 4with respect to the position of the side parts13of the spring wheel7. As can be seen fromFIGS. 3 and 4, the side edges, running approximately radially, of the rectangularly formed recesses14, seen in the circumferential direction of the spring wheel7, in each case form a lateral stop for the spring elements10which in addition also project outwards laterally beyond the side parts13.

AsFIG. 1shows furthermore, the wire8is deflected, in the wire draw-off direction x behind the swivel arm5, running through approx. 360° once around the spring wheel7and rests on the radially outer ends of the spring elements10which, together, define a guide path17in the circumferential direction of the spring wheel7(this guide path17is shown only inFIGS. 5 and 6, but is also present in entirely identical manner in the embodiment ofFIGS. 1 to 4).

Along this circumferential guide path17defined and predetermined by the radially outer ends11of the spring elements10, the wire8arriving at the spring wheel7is guided in a circumferential path, as can basically be seen inFIG. 1.

If the feeder6of the downstream wire-processing machine is operated and the wire8is drawn in by the latter, it presses the spring elements10together in radial direction during its circulation around the spring wheel7along the position of the guide path17initially predetermined by this and tightens the wire loop formed on the spring wheel7around the guide path17. As a result the feeder6thus “helps itself” from the supply of wire8stored in the spring wheel7.

During the drawing-in movement of the feeder6the spring wheel7rotates with it. If the drawing-in movement on the feeder6is now intermittent, the wire-storage means of the spring wheel7is filled again from the coil2when the feeder6is at a standstill, as the spring elements10are arranged on the spring wheel7in such a way that they are always pretensioned in the radially outward direction, thus towards the outermost possible radial position of the guide path17. During a subsequent drawing-in movement of the feeder6, the wire8is thus again provided very quickly and for the short term in the direction of a wire-storage means to compensate for fluctuations of the drawing-in movement.

FIG. 2shows a second embodiment of the apparatus1in which the wire-storage device in the form of the spring wheel7is here arranged directly on the free end of the swivel arm5as a deflecting element. The spindle9of the spring wheel7lies vertical and perpendicular to the wire8as well as parallel to the spindle22of the pay-off reel3. In this embodiment, the wire8runs around the spring wheel7, not along the whole extent of the guide path17, but only over roughly 180°.

In the previously used arrangements of a pay-off reel structure with deflecting means4and swivel arm5, the amount of wire needed in the short term had to be provided via the swivelling movement of the swivel arm5pretensioned radially outwards in spring-loaded manner or via the loops of the deflecting means4. However, this resulted in very large mechanical movements and loads.

The spring elements10of the spring wheel7or their spring-loaded restoring force acting on the wire8and the restoring force of the swivel arm5have to be designed in the embodiments shown in the figures such that the swivelling movement of the swivel arm5is introduced only in the case of a comparatively large compression travel of the spring elements10.

InFIGS. 5 and 6, two other embodiments for a spring wheel7with other formations of the spring elements10are represented, quite basically:

In the embodiment shown inFIG. 5, the spring wheel7has a central holding spindle15, from which, arranged uniformly over its circumference, spring-steel blades16freely project in an arc and radially outwards. These blades16are arranged between the side parts13of the spring wheel7, but are not secured to these, but only to the holding spindle15.

The representation ofFIG. 5as well as that ofFIG. 6each show the spring wheel7in which the side part13lying on top has been removed to represent the position of the spring elements10.

The spring elements in the form of the blades16run curved up to their freely projecting end, as can be seen fromFIG. 5. Each blade16is supported on its concavely curved side (which is the side that points in the circumferential direction y of the wire8) on a positioning element18in the form of a support pin. The positioning elements18are adjustable (not shown inFIG. 5) in their radial position, namely in such a way that in each case they are all adjusted radially at the same time and to the same extent.

The blades16are curved at their freely projecting end sections19in the circumferential direction y of the wire8, with the result that the end section19of each blade16runs at an acute angle α into the guide path17defined by the free ends of the blades16. This applies to all possible diameters of the guide path17.

If, as a result of the pull on the wire8due to the feeder6, the radial pressure of the wire8on the blades16predefining and supporting its guide path17increases, and these are pressed elastically inwards in their end section19still projecting radially outwards from the respective positioning element18, as is represented, in dashed lines, inFIG. 5in the case of a few blades16, the diameter of the guide path17which, in the starting state (when the blades16are not loaded by the wire), has a maximum value of d1becomes smaller as a result of the compression of the blade end areas19and falls to a value d2, as represented inFIG. 5. If the tension on the wire8decreases because for instance the feeder6stops, then as a result of the elasticity of the end areas19of the blades16pressed inwards and the restoring elastic force triggered by this the wire8is brought back to a guide path17with the diameter d1, wherein wire8is correspondingly subsequently fed from the coil2.

Due to the formation, shown inFIG. 5, of the arched, elastic blades16, there is a continuous spring-pretension of the blade end areas19towards their starting position (inFIG. 5: continuous shape of the blades), i.e. towards the formation of the guide path17with a maximum diameter d1.

The radial position of the guide path17thus varies depending on the state of tension of the circulating wire, wherein the diameter of the guide path17can be altered between a maximum outer radial position (diameter d1) and a minimum inner radial position (diameter d2), wherein as a result of the spring-pretension of the blades16(or also other spring elements10) the free ends of the spring elements10defining the guide path17are always pretensioned into their maximum outer radial position corresponding to the diameter d1of the guide path17. To put it briefly, the radial position of the guide path17is pretensioned into its radially outermost position.

In the embodiment ofFIG. 6, fluid-actuated spring elements20which are provided with freely rotatable rollers21at their freely projecting ends are now used as spring-loaded elements. These rollers21are attached to small piston rods23which run in radially aligned fluid-actuated pressure cylinders24. Here too, it is provided by a corresponding formation that in the starting position (with piston rods23maximally extended, cf. representation ofFIG. 6) the fluid pressure acting on the piston rods23in the pressure cylinders24is equally high in the case of all spring elements20.

In each pressure cylinder24e.g. an air or other gas filling is provided as pressurized fluid which builds up a corresponding spring-loaded counter pressure radially outwards when the associated piston rod23is pushed in radially. However, the spring elements20could equally also be constructed in such a way that they do not work with the pressure cylinders24filled with pressurized fluid, but e.g. pretensioned compression springs are arranged in them.

In the embodiment according toFIG. 6, the guide path17is circumferentially defined by the radially outermost points of the rollers21. The representation ofFIG. 6shows the radially outermost position of the guide path17corresponding to the diameter d1fromFIG. 5.

It is also favourable (cf.FIG. 7) to use pistons25, running in cylinders24, in which the piston head or the whole piston25and the cylinder bottom20consist of permanently magnetic material of identical polarization and air is otherwise present in the cylinder24. Here, as a result of the magnetic repulsive forces occurring between piston25and cylinder bottom26, a maintenance-free and very simply constructed spring element is created which is also very robust and reliable during operation. Naturally, electromagnetizable materials could also be used which, during use, alloy a certain control of the active repulsive forces and thus also of the spring properties through a corresponding influencing of the electrical excitation.

Other embodiments of the spring elements10or16or20are also directly conceivable, provided that these make it possible to alter the diameter of the guide path17with simultaneous continuous pretension of same into its radial outermost position.

Instead of the rollers21shown inFIG. 6at the radially outermost ends of the spring elements, caps made of a wear-resistant material (not shown in the figures) could also be attached, over which the wire8then runs.

If such caps made of wear-resistant material or freely rotating rollers21(FIG. 6) are provided, the spring wheel7for its part need not necessarily be arranged rotatable, as the wire8can then also simply run along the guide path17if the spring elements do not rotate. A rotatability only of the spring elements16or20inside the spring wheel7between (fixed) side parts13also represents an effective embodiment of this pressurized storage device.

Also in the embodiment according toFIG. 5, the spring wheel7can in principle be arranged non-rotatable and fixed, because the spring elements16elastically give way in the direction of travel y of the wire along the guide path17and thus a reduction of the diameter of the guide path17is also possible without rotation of the side parts13of the spring wheel7in the case of spring-pretension towards the maximum diameter d1.