Device and method for providing a metal wire with a thinned wire end

Abstract

A device (100, 200, 300, 400) for providing a metal wire (290) with a thinned wire end, the device (100, 200, 300, 400) comprising, at opposite sides of a path for axial motion of the wire, one or more pairs of jaws (102, 104; 202, 204; 302, 304; 402, 404) and a pull tool for pulling the wire along the path. The one or more pairs of jaws comprise a plurality of blocks (110-116; 210-216; 310-316; 410-416) distributed along said path, said blocks (110-116; 210-216; 310-316; 410-416) having corners, wherein the jaws (102, 104; 202, 204; 302, 304; 402, 404) of each pair of jaws (102, 104; 202, 204; 302, 304; 402, 404) are configured to be moveable with respect to each other for closing the jaws (102, 104; 202, 204; 302, 304; 402, 404) such that the blocks (110-116; 210- 216; 310-316; 410-416) of the jaws (102, 104; 202, 204; 302, 304; 402, 404) engage, thus inducing the wire, when pulled along said path, to zig-zag so that the wire drags over the corners of the blocks (110-116; 210-216; 310-316; 410-416) of both jaws (102, 104; 202, 204; 302, 304; 402, 404) to elongate the wire until fracture.

Description

Device and method for providing a metal wire with a thinned wire end.Technical field of the invention

[0001] The present invention pertains to the technical field of metal wire processing, specifically to devices and methods for mechanically thinning and pointing the ends of metal wires to facilitate threading through drawing dies.Background of the invention

[0002] The field of metal wire manufacturing is a critical component of various industries, including construction, automotive, electronics, and more. One of the essential processes in wire manufacturing is the preparation of the wire end for subsequent drawing operations. The drawing process involves pulling the wire through a series of dies to reduce its diameter and achieve the desired size and properties. To initiate this process, the end of the steel wire must be threaded through a drawing die, which requires the wire end to be pointed or tapered to facilitate entry into the die.

[0003] In the current state of the art, several techniques are employed to create a pointed end on a steel wire. The method chosen often depends on the diameter and material composition of the wire. For larger diameter wires, one common technique involves rolling the wire end between grooved rollers to create a taper. The grooves have a gradually diminishing diameter over the circumference of the roller. An alternative way of the use of rollers to diminish the wire end diameter is disclosed DE 2134273, a device that keeps the wire end stationary and wherein the rollers go back and forth.

[0004] Another method involves applying tensile force to a heated wire, followed by pulling to fracture to stretch and narrow the diameter. For thinner wires, a manual process is sometimes used where the wire is rubbed against a hook until it heats up, and then a quick pull creates a pointed end.

[0005] Still another device to taper the end of a wire is described in US1567960. Therein a rotor whereon a series of pairs of oppositely positioned rollers are rotatably mounted locally rolls the wire to a smaller diameter, as the wire is being pushed through the device.

[0006] These existing methods have their limitations and challenges. The rolling technique may not be suitable for all wire diameters or materials and canrequire significant adjustments to the equipment for different wire sizes. The heating and tensile stretching method can be difficult to control and leads to burn injuries. Additionally, heating up a metal wire may influence its mechanical properties and even its metallurgical structure. The manual rubbing method is labor-intensive, can lead to accidents as the wire suddenly breaks, and needs skill from the operator to obtain a good quality of the pointed ends.

[0007] Despite the variety of techniques available, there are still challenges in consistently producing a pointed wire end efficiently and safely. The need for a reliable and versatile method that can accommodate different wire diameters and materials without compromising the wire's properties is evident. Additionally, reducing the labor intensity and improving the safety of the pointing process are ongoing concerns in the industry.

[0008] Therefore, there is a clear need for further advancements in the field of metal wire manufacturing, particularly in the development of methods and devices for efficiently and consistently creating pointed wire ends that are suitable for threading through drawing dies. These advancements would contribute to the overall efficiency and safety of the wire drawing process, which is a critical step in the production of metal wires for various applications.Summary of the invention

[0009] It is an object of embodiments of the present invention to provide an improved device and method for providing a metal wire with a thinned wire end.

[0010] This objective is accomplished by a device and method for providing a metal wire with a thinned wire end according to the invention.

[0011] It is an advantage of embodiments of the present invention that a metal wire with a thinned wire end can be obtained through a mechanical process that does not significantly alter the material properties of the wire.

[0012] It is a further advantage of embodiments of the present invention that the wire end may be thinned without the formation of burrs, which can be detrimental to the subsequent processes that the wire may undergo.

[0013] In a first aspect, the present invention relates to a device for providing a metal wire with a thinned wire end. The device comprises, at opposite sides of a path for axial motion of the wire, one or more pairs of jaws comprising aplurality of blocks distributed along said path, said blocks having corners. The jaws of each pair of jaws are configured to be moveable with respect to each other for closing the jaws such that the blocks of the jaws engage, thus inducing the wire, when pulled along said path, to zig-zag so that the wire drags over the corners of the blocks of both jaws to elongate the wire until fracture. With ‘engage’ is meant that a block of one jaw enters the space between adjacent blocks of the facing jaw. The blocks may have a rectangular, square or triangular shape in a cross section in a plane parallel to the plane of movement.

[0014] As the wire is being dragged over the corners of the blocks, friction between the wire and the corners of the blocks may result in heating of the wire, increasing the flexibility and ductility of the wire. Furthermore, due to the zigzagging, the wire is bent, resulting (in combination with the heat) in plastic elongation of the wire. The heated wire may be plastically elongated by said pulling of the wire, resulting in thinning of the wire, and, ultimately, fracture of the wire. The end of the wire will thus show a reduced diameter suitable for insertion in the orifice of the drawing die, the diameter of the orifice being smaller than that of the original wire diameter. Rectangular or square shaped blocks have the advantage that per block there are two corners against which the wire is dragged.

[0015] As the wire is deformed in a zig-zag path due to the closing of the jaw pair and at the same time pulled in longitudinal direction over the corners of the blocks a considerable force has to be exerted on the wire to initiate and maintain movement. Therefore the device is provided with a pull tool, for pulling the wire along the axial motion path.

[0016] In embodiments, the blocks, or at least the material forming the corners of the blocks, may be formed of a material having a hardness lower than the hardness of the wire end to be thinned. This embodiment ensures that the wire will not be damaged during the thinning process and that there will be sufficient friction between the wire and the block material. Friction is needed to generate enough heat on the wire. If the hardness of the block material is higher than that of the wire to be thinned, the wire will scraped, shaved and thus be damaged.

[0017] In embodiments, the blocks, or at least the material forming the corners of the blocks, may be formed of a material having a hardness of from 35 to200HB, preferably of from 50 to 175HB. These embodiments may provide blocks having a low hardness, which may prevent damage to the wire during the thinning process and increased friction . Indeed, this range of hardness facilitates plastic elongation of the wire, which is beneficial for achieving the desired thinning without compromising the wire's integrity. For example, the blocks may be formed of copper, hardened AW-6060 aluminium, mild steel or carbon steel, or annealed stainless steel or inox, or brass alloys, e.g., CuZn40Pb2.

[0018] Generally, in wire forming devices - that are designed to give a permanent shape to a wire - the forming tool for bending the wire will be harder than the wire, to prevent wear of the tool. ‘Wire forming’ devices are devices where the wire does not move substantially relative to the tool when being formed and the resulting form of the wire is not straight. Examples of wire forming devices are described in CN 207127147, FR 2490446A1, EP 4175139A1.

[0019] Within the context of the present invention, the hardness (in HB) of the material from which the blocks are made may refer to the Brinell hardness, which may be measured using a standardized test that quantifies the indentation hardness of materials through the scale of penetration of an indenter. For example, the Brinell hardness may be determined using the standard ISO 6506. The Brinell hardness may be determined using a test method within the subgroup HB5, e.g., using test method HBW 5 / 125 (i.e., using a tungsten ball of 5 mm diameter and applying a force of 125kgf), or within the subgroup HB10, e.g., using test method HBW 5 / 250 (i.e., using a tungsten ball of 5 mm diameter and applying a force of 250kgf).

[0020] The device may comprise a single pair of jaws, which may result in a comparatively simple device. Alternatively, the device may comprise a plurality of jaws, which may provide more flexibility in the design of the device. A plurality of jaws can e.g. be placed in series to reduce the wire end even more, enabling more dies to be threaded on the wire end in one operation.

[0021] In embodiments, for each pair of jaws, the jaws may be configured to be moveable with respect to each other for closing the jaws by a translational motion and / or by a rotational motion of the jaws. This flexibility in movement allows for various methods of engaging, which can be tailored to the specific requirements of the thinning process.

[0022] In embodiments, when the jaws of the pair of jaws are open, a transversal distance between consecutive blocks of the jaws at opposite sides of the path may increase in a direction of said axial motion of the wire. Although this may be inherent to embodiments wherein the jaws are moveable with respect to each other for closing the jaws by a rotational motion of the jaws, these embodiments may also be applicable when the jaws are moveable with respect to each other for closing the jaws by a translational motion. In embodiments, when the jaws of the pair of jaws are engaged, a transversal distance between corners at opposite sides of the path may diminish in a direction of said axial motion of the wire. These embodiments may be advantageous for effectively thinning the wire as it is pulled through the device. These embodiments result in less bending (corresponding to an increasing radius of curvature) of the wire along the direction of the axial motion of the wire. The bending action on the wire is gradually reduced in concord with the diameter reduction of the wire.

[0023] In embodiments, a radius of curvature at the corners of the blocks may be smaller than a diameter of the wire. This design may ensure that, as the wire is dragged along said corners, the wire is bent sufficiently so that an outer, convex part of the zig-zagging wire may be stretched effectively. In preferred embodiments, the radius of curvature at the corners of the block are smaller than three quarter, or half of the wire diameter. The smaller the radius of curvature at the corners is the more plastic deformation takes place at the outer bend of the wire.

[0024] In embodiments, when the jaws of the pair of jaws are engaged, a distance between blocks of the jaws at opposite sides of the path may be at least equal to a diameter of the wire, and preferably at most 100 times the diameter of the wire. These embodiments may ensure that the wire is not overly constricted or even get clamped on closure, which could lead to damage or fracture at undesired locations. By preference this distance is 1.5 to 2 times or more the wire diameter.

[0025] In embodiments, the device may comprise an aperture or slot for receiving the wire after moving between the jaws. These embodiments may be advantageous for safely containing the pointed end of the wire after fracture, preventing it from becoming a hazard. Said hazard could result from the wire,on fracture, moving towards a person or delicate apparatus. For example, a pig’s tail or a plate may comprise the aperture.

[0026] In embodiments, the device may comprise a capstan as a pull tool, the capstan having an axis in a plane substantially perpendicular to a direction of said path for axial motion of the wire, for pulling said wire along the path for axial motion. The capstan may, alternatively, be called a bobbin or spool or wheel, and may comprise a cylinder for winding up the wire and to, thereby, apply tension to the wire. The capstan may be provided with a clamp for holding the wire and guidance on the capstan. The capstan may provide a controlled means of pulling the wire, which may facilitate consistent thinning and pointing. It is an advantage of embodiments comprising the capstan that the wire may be wound up during the pointing process.

[0027] In embodiments the pull tool may be a hydraulic cylinder with sufficient stroke length ending with a wire clamp. In still another embodiment, the pull tool may be a caterpillar system that clamps the wire in V- shaped links that engage and pull the wire without needing a wire clamp. In still other embodiments the pull tool may be a simple lever system, with a wire clamp at the load arm end, a fulcrum and an effort arm. In still other embodiments the pull tool may be a block-and-tackle system with one of the block holding a wire clamp.

[0028] The pull tool must be able to provide sufficient force to pull the wire until break. That is: the pull tool must be able to exert a force that is equal or larger than the breaking load of the wire to be thinned.

[0029] In embodiments, the device may comprise holders along the path for axial motion of the wire at both ends of the jaws, for holding the wire, when present, laterally in position. These embodiments may ensure that the wire remains aligned with the blocks during the thinning process, which may facilitate achieving a uniform pointed end.

[0030] The holders may comprise several slots or apertures at the entrance and / or exit of the jaws. The slots can take the form of a comb. As the blocks may tend to wear during use, recesses, tracks will form in the material of the blocks where the radius of curvature of the block becomes prohibitively high. By selection another slot at the entrance and / or exit the wire will be guided aside the track already formed. In this way the full width of the blocks can be used and replacement of the blocks is postponed.

[0031] In embodiments, the jaws may be hingedly connected to each other. These embodiments may provide a simple and effective means of opening and closing the jaws, which is beneficial for ease of operation.

[0032] In embodiments, each jaw may comprise at least 2 blocks. More blocks may result in a more efficient elongating of the wire until fracture.

[0033] In embodiments, the device may furthermore comprise an actuator for closing the jaws. The actuator may be controlled manually or automatically, providing ease of use and potential for automation. The actuator may allow for automated control of the jaw movement, which can improve the precision and repeatability of the thinning process.

[0034] In embodiments, the device may furthermore comprise a controller for automated control of the actuator. The controller may be configured for controlling means of pulling the wire along the path of axial motion, e.g., for controlling the capstan while controlling the actuator for closing the jaws. This embodiment provides a higher level of automation, which can lead to increased efficiency and consistency in the wire thinning process. In embodiments, the controller may be configured for pulling the wire along the path of axial motion, e.g., by rotating the capstan, while closing the jaws. The pulling and closing may be set in the controller on the basis of the properties of the wire such as diameter of the wire, material of the wire and / or tensile strength, carbon content or any other suitable parameter.

[0035] In a second aspect, the present invention relates to a method for providing a metal wire with a thinned wire end. The method comprises providing the metal wire. The method further comprises, while pulling the wire along the path of axial motion in a device in accordance with any embodiments of the first aspect, closing the jaws of each pair of jaws of said device such that the blocks of the jaws engage, inducing the wire to zig-zag, so that the wire drags over corners of the blocks of both jaws to elongate the wire until fracture.

[0036] In embodiments, said closing may comprise gradually closing the jaws while pulling the wire along said path of axial motion. The gradual closing of the jaws makes the wire zig-zag in between the blocks, wherein the friction causes the wire to heat up. As soon as the wire is hot enough, the operator may close the jaws a bit more so that the wire snaps.

[0037] In embodiments, when initiating said closing of the jaws, a length of the wire at a side of entrance of the device for the wire may be at least 3 times a length of the jaws. The length of the jaws may be defined as a distance, along the path of axial motion, between the center of a first block of the jaw and the center of a last block of the jaw. Herein, the first and last block are the first and last block of the device that the wire passes along the path of axial motion of the wire. This embodiment ensures that there is sufficient wire length to properly engage with the blocks and undergo the thinning process.

[0038] In embodiments, said inducing the wire to zig-zag may comprise stretching an outer, convex part of the zig-zagging wire by at least 3%. Said stretching is in the axial direction of the wire. This specific amount of stretching is beneficial for achieving the desired elongation and thinning of the wire without causing premature fracture. In other preferred embodiments of the method this elongation may be more than 3.5% or even 4%. In any case an elongation of more than 10% at outer bend may be too much.

[0039] Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate and not merely as explicitly set out in the claims.

[0040] The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.Brief description of the drawings

[0041] FIG. 1 is a schematic representation of a side view of a first exemplary device for providing a metal wire with a thinned wire end according to embodiments of the present invention, illustrating the jaws and wire before engagement of the jaws.

[0042] FIG. 2 is a schematic representation of a side view of the first exemplary device shown in FIG. 1, showing the jaws in an engaged position according to embodiments of the present invention.

[0043] FIG. 3 is a schematic representation of a side view of a second exemplary device in accordance with embodiments of the present invention, illustrating the jaws, blocks, and wire before engaging the jaws according to embodiments of the present invention.

[0044] FIG. 4 is a schematic representation of a side view of the second exemplary device of FIG. 3, showing the jaws in an engaged position according to embodiments of the present invention.

[0045] FIG. 5 is a detailed view of a single block and a wire, highlighting the radius of curvature at the corner of the block and the diameter of the wire, in accordance with embodiments of the present invention.Description of illustrative embodiments

[0046] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

[0047] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0048] Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

[0049] It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying thepresence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. The term “comprising” therefore covers the situation where only the stated features are present and the situation where these features and one or more other features are present. The word “comprising” according to the invention therefore also includes as one embodiment that no further components are present.

[0050] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may do so. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[0051] Similarly it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

[0052] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0053] Furthermore, some of the embodiments are described herein as a method or combination of elements of a method that can be implemented by a controller, PLC, or processor of a computer system or by other means of carrying out the function. Thus, a processor with the necessary instructions for carrying out such a method or element of a method forms a means for carrying out the method or element of a method. Furthermore, an element described herein of an apparatus embodiment is an example of a means for carrying out the function performed by the element for the purpose of carrying out the invention.

[0054] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0055] The invention will now be described by a detailed description of several embodiments of the invention. It is clear that other embodiments of the invention can be configured according to the knowledge of persons skilled in the art without departing from the technical teaching of the invention, the invention being limited only by the terms of the appended claims.

[0056] The present invention relates to a device and method for providing a metal wire with a thinned wire end.

[0057] In a first aspect, the present invention relates to a device for providing a metal wire with a thinned wire end. The device comprises, at opposite sides of a path for axial motion of the wire, one or more pairs of jaws comprising a plurality of blocks distributed along said path, said blocks having corners. The jaws of each pair of jaws are configured to be moveable with respect to each other for closing the jaws such that the blocks of the jaws engage, thus inducing the wire, when pulled along said path, to zig-zag so that the wire drags over the corners of the blocks of both jaws to elongate the wire until fracture.

[0058] In a second aspect, the present invention relates to a method for providing a metal wire with a thinned wire end. The method comprises providing the metal wire. The method further comprises, while pulling the wire along the path of axial motion in a device in accordance with any embodiments of the first aspect, closing the jaws of each pair of jaws of said device such that theblocks of the jaws engage, inducing the wire to zig-zag, so that the wire drags over corners of the blocks of both jaws to elongate the wire until fracture.

[0059] Example 1: Device for providing a metal wire with a thinned wire end, configured for closing the jaws by a translational motion

[0060] Referring to FIG. 1 , a schematic illustration of a device (100) in accordance with embodiments of the present invention is shown. The device (100) is for providing a metal wire (190) with a thinned wire end. In the example illustrated, the device (100) comprises a single pair of jaws (102, 104) that are moveable relative to each other. However, the present invention is not limited thereto and the device (100) could, instead, comprises more than one pair of jaws.

[0061] The jaws (102, 104) are located on opposite sides of a path for axial motion of the wire (190). The jaws (102, 104) may be located at any two opposite sides of the path. In the example illustrated, a first jaw (102) is located below the said path, and a second jaw (104) is located above said path. In the example illustrated, the wire (190) is located at, or along, said path, and may be moved along said path, i.e. , along its axis.

[0062] Each jaw (102, 104) comprises a series of blocks (110-116) positioned along the path of the wire (190). In the example illustrated, the first jaw (102) contains four blocks (110, 112, 114, 116), each having similar dimensions. In the example illustrated, the second jaw (104) contains three blocks (111 , 113, 115) of which a dimension in a direction perpendicular to the direction of axial movement increases along the path, in the direction of axial movement of the wire (190). The direction of axial movement of the wire (190) is in the direction along the path towards the capstan (192), which pulls the wire (190) along said path. The direction of axial movement is, thus, from left to right in FIG. 1. When the jaws (102, 104) are open, the transversal distance (L1, L2, L3) - in a direction perpendicular to the path of axial motion - between consecutive blocks (110-116) of the jaws (102, 104) at opposite sides of the path may increase in the direction of the axial motion of the wire. In the example illustrated, a dimension of the three blocks (111, 113, 115) in a direction parallel to the direction of axial movement decreases along the path as well.

[0063] In the example illustrated, the axial distance (W1, W2, W3, W4, W5, W6) - in a direction along the path of axial motion - between consecutive blocks (110- 116) of the jaws (102, 104) at opposite sides of the path is substantially the same. Said axial distance (W1, W2, W3, W4, W5, W6) is at least equal to a diameter of the wire (190). Otherwise the wire would get clamped.

[0064] Although a particular configuration for the blocks (110-116) is described in this example, different configurations of the blocks (110-116) are within the scope of the present invention as well. For example, the axial distances (W1, W2, W3, W4, W5, W6) between consecutive blocks (110-116) may, instead, vary. Furthermore, although, in the present example, along the path, blocks (110, 112, 114, 116) of the first jaw (102) alternate with blocks (111, 113, 115) of the second jaw (104) so that consecutive blocks (110-116) along the path of axial motion of the wire (190) are always of different jaws (102, 104), instead, some consecutive blocks along the path of axial motion of the wire (190) could belong to the same jaw (102, 104).

[0065] In the example illustrated, the first jaw (102) is a static jaw, which may be rigidly fixed to a base, such as a table. The second jaw (104) is moveable. In particular, the second jaw (104) is translatable towards the first jaw (102) for closing the jaws (102, 104). In the example illustrated, the device (100) comprises an actuator for closing the jaws (102, 104) by translating the second jaw (104) towards the first jaw (102), said actuator comprising a guide sleeve (120) in which a rod (118) to which the second jaw (104) is fixed is movable. Said actuator may further comprise a motor, or hydraulic or pneumatic cylinder (not shown) for moving the rod (118) through the guide sleeve (120), and for applying a downward force (F) on the second jaw (104). The actuator may further comprise a controller (not shown) for controlling the motor. However, this is not required, and instead, a person (not shown) may move the rod (118) by means of a lever or by force of hand. .

[0066] The wire (190) is guided over the capstan (192) and fixed thereto by clamp blocks (194). The capstan (192) has an axis in a plane substantially perpendicular to the direction of the path for axial motion of the wire (190), so that the capstan (192) may pull the wire (190) along said path by winding up the wire (192). Said axis (indicated with '+’) of the capstan (192), around which the capstan (192) rotates, is, in the example illustrated, normal to the plane of FIG. 1, i.e., horizontally along the direction pointing into the paper.Alternatively, the axis of the capstan (192) could be oriented vertically or diagonally.

[0067] In the example illustrated, the device comprises holders along the path for axial motion of the wire at both ends, e.g., the entrance end and the exit end, of the jaws (102, 104), for holding the wire (190) laterally in position along the path between the jaws (102, 104). The first holder (122) is located at the entrance end for guiding the wire (190) properly along the path between the jaws (102, 104). The first holder (122) may be a vertical slot in a block. Alternatively, the first holder (122) may comprise a ridge or comb comprising a plurality of slots in a block so that a new position or slot for the wire (190) can be chosen once a track is worn into the blocks (110-116). The capstan (192) functions as the second holder at the exit end. Alternatively, a separate second holder, which may have the same features independently as described for the first holder (122), could be provided for holding the wire (190) laterally in position.

[0068] The device (100) further comprises an aperture or slot (124) for receiving the wire (190) after moving between the jaws (102, 104). The aperture (124) may be that of a "pig's tail" (124), as is shown in FIG. 1. The aperture (124) is provided so that the wire (190), on breaking, is kept in position and does not move freely, which could result in a dangerous situation.

[0069] The wire (190) may be pulled by the capstan (192) while the actuator closes the jaws (102, 104). The closing of the jaws (102, 104) makes the wire zigzag in between the blocks (110-116) so that the wire (190) drags over the corners of the blocks (110-116) of both jaws (102, 104).

[0070] Referring to FIG. 2, the device (200) is depicted after a force has been applied by the actuator, in particular, via the rod (218) moving through the guide sleeve (220), to the second jaw (204) so as to close the jaws (202, 204), causing the wire (290, 291) (that is in FIG. 2 shown after breaking) to drag over the corners of the blocks (210-216). Thereby, the wire (290, 291) is heated and elongated until the point where the wire (290) breaks, leaving a pointed end on the wire (291). The "pig's tail" (224) keeps the wire (290) in position so that the wire (290) does not whip up.

[0071] This process is now described in more detail. Preferably, the jaws (202, 204) are closed gradually while pulling the wire (290) along said path of axial motion. When the jaws (202, 204) are closed so as to engage the blocks(210-216) of the jaws (202, 204), the wire (290) drags over corners of the blocks (210-216). In the example illustrated, the friction of said dragging causes part of the wire (290, 291) (before said fracture) to heat up. The heated part of the wire (290, 291) is typically flexible and may be plastically deformable, so that said pulling may result in an elongation of the heated part of the wire (290, 291) and, thus, thinning or a reduction of its diameter. Gradually closing the jaws (202, 204) further, will result in further heating and elongation of the part of the wire (290, 291). As soon as the part of the wire (290, 291) is thinned enough, the actuator may yet further close the jaws (202, 204) so that the wire (290, 291) elongates further until it breaks or snaps (typically at said thinned part). The wire (290, 291) may break into a wire (290) wound on the capstan (292) which is typically the wire (290) for further use and may contain the thinned or pointed end and a wire (291) still located between the jaws (202, 204). The snapped end of the wire (290) wound on the capstan (292) is pointed due to said thinning. The pointed end of the wire (290) facilitates threading of the wire (290) into and through a drawing die.

[0072] When the jaws (202, 204) are engaged, a transversal distance between corners at opposite sides of the path diminishes in a direction of said axial motion of the wire (290, 291). When the jaws (202, 204) are engaged, blocks (211 , 213, 215) of the second jaw (204) move or protrude into the spaces between adjacent blocks (210, 212, 214, 216) of the first jaw (202). Similarly, when the jaws (202, 204) are engaged, blocks (210, 212, 214, 216) of the first jaw (202) move or protrude into the spaces between adjacent blocks (211 , 213, 215) of the second jaw (204). The blocks (210-216) physically contact the wire (290, 291) and push the wire (290, 291) into said spaces, thereby inducing the wire (290, 291) to zig-zag.

[0073] In the example illustrated, the distance that the blocks protrude into said spaces reduces in the direction of axial motion of the wire (290, 291). In other words, blocks (211, 212) at the entrance side of the path between the jaws (202, 204) protrude farther into the spaces between blocks (210-213) of the opposing jaw (202, 204) than blocks (214, 215) at the exit side of the path between the jaws (202, 204) protrude into the spaces between blocks (213- 216) of the opposing jaw (202, 204). This configuration may ensure that the wire (290, 291) bends most at the entrance side of the path between the jaws (202, 204), and that the wire (290, 291) may drag more and experience moredrag and friction at said entrance side and hence heats up quickly. The further bending ensures further plastic elongation of the wire that brings an associated reduction of diameter with it. This configuration appears to yield particularly good results. Without being bound by theory, it is believed that the particularly strong drag at the entrance side may result in a large traction of the wire (290, 291) at the entrance side and hence a corresponding heating. The large traction at the entrance side may be advantageous for achieving sufficient heating of the wire while blocks away from said entrance side may be advantageous for further bending and further plastically elongating the wire the wire (290, 291).

[0074] Typically, good results are achieved when the wire (290, 291) is bent at least three times. Therefore, good results are achieved when each jaw (202, 204) comprises at least two blocks (210-216) comprising corners over which the wire (290) is dragged.

[0075] The hardness of the blocks (210-216) - or at least of the material forming the corners of the blocks (210-216) - may range from 35 to 200HB, preferably from 50 to 175HB. The hardness of the blocks (210-216) - or at least of the material forming the corners of the blocks (210-216) - is preferably low so as to prevent damage to the wire (290, 291) when being dragged over the corners and facilitate plastic elongation of the wire (290, 291). The hardness is chosen such that the wire contacts the corner of the block well and sufficient friction is generated. The hardness of the blocks (210-216) is preferably not so low that the blocks (210-216) themselves would be deformed or damaged when the wire (290, 291) is being dragged over the surfaces of the corners of the blocks (210-216). In the example illustrated, the blocks (210-216) are formed of a material having a hardness lower than the hardness of the wire (290) end that is thinned, i.e., the part of the wire (290, 291) that is elongated or thinned to fracture. Usually, the complete wire (290, 291) is formed of the same material, so that the blocks (210-216) may be formed of a material having a hardness lower than the hardness of the complete wire (290).

[0076] Example 2: Device for providing a metal wire with a thinned wire end, configured for closing the jaws by a rotational motion.

[0077] Referring to FIG. 3, a side view of a wire thinning device (300) in accordance with embodiments of the present invention is shown. The device (300)features a set of jaws (302, 304), wherein the jaws (302, 304) are arranged on opposite sides of the path of axial motion of the wire (390). The jaws (302, 304) comprise a series of blocks (310-316) on opposite sides of the path of axial motion of the wire (390), through which the metal wire (390) is to be pulled. When the jaws (302, 304) are open, a transversal distance between consecutive blocks (310-316) of the jaws (302, 304) at opposite sides of the path increases in a direction of said axial motion of the wire (390).

[0078] A capstan (392) is provided for winding up the wire (390), thereby pulling the wire (390) along the path for axial motion, so that the wire (390) to be thinned or pointed is wound up in the process. An axis of the capstan (392) is located in a plane substantially perpendicular the direction of the path of axial motion of the wire (390). The capstan (392) comprises clamp blocks (394) for fixing the wire (390) to the capstan (392).

[0079] In the example illustrated, the jaws (302, 304) are configured to be moveable with respect to each other for closing the jaws (302, 304) by a rotational motion. In the example illustrated, a first jaw (302) is fixed, e.g., on a surface, and a second jaw (304) is movable, in particular, rotatable around a hinge (320). In the example illustrated, the jaws (302, 304) are connected to each other by the hinge (320) at one side, which may be called the entrance side, of the jaws (302, 304). At another side of the second jaw (304), a lever (322) comprising a knob (318) is mounted to the second jaw (304) to push the second jaw (304) towards the first jaw (302). In the example illustrated, the lever (322) comprising the knob (318) forms an actuator. When a force (F) is applied to the knob (318) of the lever (322), the jaws (302, 304) may be pushed together so as to engage the blocks (310-316) of the jaws (302, 304). Said force (F) may be applied by a person or by an actuator.

[0080] Referring to FIG. 4, the device (400) is schematically illustrated after a force (F) has been applied at the knob (418) at the end of the lever arm (422), and the second jaw (402) has rotated around the hinge (420) to close the jaws (402, 404). The jaws (402, 404) are engaged, so that blocks (411, 413, 415) of the second jaw (404) push the wire (490) into spaces between adjacent blocks (410, 412, 414, 416) of the first jaw (402). Similarly, when the jaws are engaged, blocks (410, 412, 414, 416) of the first jaw (402) push the wire (490) into spaces between adjacent blocks (411, 413, 415) of the second jaw (404). Thus, the blocks (410-416) induce the wire (490) to zig-zag.

[0081] When the jaws (402, 404) are engaged, a transversal distance between corners at opposite sides of the path diminishes in a direction of said axial motion of the wire (490). When the jaws (402, 404) are engaged, an axial distance - i.e. along the path of the wire - between blocks (410-416) of the jaws (402, 404) at opposite sides of the path is at least equal to a diameter of the wire (490). If the distance between blocks (410-416) of the jaws (402, 404) would be smaller than a diameter of the wire (490), the wire (490) may become fixed between adjacent blocks (410-416) when the jaws (402, 404) are engaged, or the jaws (402, 404) may not be able to engage at all so that the blocks (410-416) may not be able to induce zig-zagging of the wire (490), hampering proper functioning of the device (400).

[0082] In the example illustrated, the distance that the blocks push the wire (490) into said spaces reduces in the direction of axial motion of the wire (490). Thereby, the wire (490) bends more strongly at the entrance side of the jaws (402, 404) than on the exit side of the jaws (402, 404).

[0083] While closing the jaws (402, 404), the capstan (492) continues rolling up the wire (490), thereby pulling the wire (490) along the path for axial motion, so that the wire (490) drags over corners of the blocks (410-416). The jaws (402, 404) may be gradually closed further while pulling the wire (490) along said path of axial motion to create more drag and increase the friction between the corners of the blocks (410-416) and the wire (490). The friction between the corners and the wire (490) heats up the wire (490) so that, in combination with the pull force exerted by the capstan (492), the wire (490) plastically deforms and elongates until fracture (not shown), thereby providing the wire (490) on the capstan with a thinned end.

[0084] Example 3: Radius of curvature of the blocks.

[0085] Referring to FIG. 5, a simplified representation of a block (512) of a jaw (502) is shown. Also, a wire (590) having a diameter (D) is schematically shown. In the example illustrated, a radius of curvature (R) at the corners of the block (512) is smaller than a diameter (D) of the wire (590). This may ensure that an outer, convex part of the zig-zagging wire (590) is stretched sufficiently, to facilitate elongation and thinning of the wire (590). Preferably, the outer, convex part of the zig-zagging wire (590) is stretched (in an axial direction of the wire (590)) by at least 3%. As the wire (590) is typically dragged overcorners of blocks (512) on opposite sides of a path of axial motion of the wire (590), the wire (590) may be stretched on opposite sides of the wire (590).

[0086] It is to be understood that although preferred embodiments, specific constructions and configurations, as well as materials, have been discussed herein for devices according to the present invention, various changes or modifications in form and detail may be made without departing from the scope of this invention. Steps may be added or deleted to methods described within the scope of the present invention.

Claims

Claims1 . A device (100, 200, 300, 400) for providing a metal wire (290) with a thinned wire end, the device (100, 200, 300, 400) comprising, at opposite sides of a path for axial motion of the wire (190, 290, 390, 490), one or more pairs of jaws and a pull tool for pulling said metal wire along said path for axial motion, said one or more pairs of (102, 104; 202, 204; 302, 304; 402, 404) comprising a plurality of blocks (110-116; 210-216; 310-316; 410-416) distributed along said path, said blocks(110-116; 210-216; 310-316; 410-416) having comers, wherein the jaws (102, 104; 202, 204; 302, 304; 402, 404) of each pair of jaws (102, 104; 202, 204; 302, 304; 402, 404) are configured to be moveable with respect to each other for closing the jaws (102, 104; 202, 204; 302, 304; 402, 404) such that the blocks (110-116; 210-216; 310-316; 410-416) of the jaws (102, 104; 202, 204; 302, 304; 402, 404) engage, thus inducing the metal wire (190, 290, 390, 490), when pulled along said path by said pull tool, to zig-zag so that the metal wire (190, 290, 390, 490) drags over the corners of the blocks (110-116; 210-216; 310-316; 410-416) of both jaws (102, 104; 202, 204; 302, 304; 402, 404) to elongate the wire (190, 290, 390, 490) until fracture.

2. The device (100, 200, 300, 400)according to claim 1 , wherein the blocks (110-116; 210-216; 310-316; 410-416) are formed of a material having a block material hardness, said metal wire to be thinned having a wire material hardness, said block material hardness being lower than said wire material hardness.

3. The device (100, 200, 300, 400) according to any one of the previous claims, wherein the blocks (110-116; 210-216; 310-316; 410-416) are formed of a material having a hardness of from 35 to 200HB, preferably of from 50 to 175HB.

4. The device (100, 200, 300, 400) according to any one of the previous claims, wherein, when the jaws (102, 104; 202, 204; 302, 304; 402,404) of the pair of jaws (102, 104; 202, 204; 302, 304; 402, 404) are engaged, a transversal distance between corners at opposite sides of the path diminishes in a direction of said axial motion of the wire (190, 290, 390, 490).

5. The device (100, 200, 300, 400) according to any one of the previous claims, wherein the corners of said blocks (512) have a radius of curvature (R), said metal wire to be thinned having a wire diameter (D), wherein said radius of curvature is smaller than said diameter (D) of the wire (190, 290, 390, 490).

6. The device (100, 200, 300, 400) according to any one of the previous claims, wherein said wire to be thinned having a wire diameter (D), wherein when the jaws (102, 104; 202, 204; 302, 304; 402, 404) of the pair of jaws (102, 104; 202, 204; 302, 304; 402, 404) are engaged, a distance between blocks (110-116; 210-216; 310-316; 410-416) of the jaws (102, 104; 202, 204; 302, 304; 402, 404) at opposite sides of the path is at least equal to said wire diameter (D) and preferably at most 100 times said wire diameter.

7. The device (100, 200, 300, 400) according to any one of the previous claims, wherein, for each pair of jaws(102, 104; 202, 204; 302, 304; 402, 404), the jaws (102, 104; 202, 204; 302, 304; 402, 404) are configured to be moveable with respect to each other for closing the jaws (102, 104; 202, 204; 302, 304; 402, 404) by a translational motion and / or by a rotational motion of the jaws (102, 104; 202, 204; 302, 304; 402, 404).

8. The device (100, 200, 300, 400) according to any one of the previous claims, wherein said pull tool is one out of the group comprising a capstan, a hydraulic cylinder, a caterpillar system, a lever, a block and tackle system.

9. The device of any one of the previous claims, wherein said pull tool is a capstan (192, 292, 392, 492) having an axis in a plane substantially perpendicular to a direction of said path for axial motion of the wire (190, 290, 390, 490), for pulling said wire (190, 290, 390, 490) along the path for axial motion.

10. The device (100, 200, 300, 400) of any of the previous claims, comprising holders along the path for axial motion of the wire (190, 290, 390, 490) at both ends of the jaws (102, 104; 202, 204; 302, 304; 402, 404), for holding the wire (190, 290, 390, 490), when present, laterally in position.11 . The device (100, 200, 300, 400) of any of the previous claims, wherein each jaw comprises at least 2 blocks (110-116; 210-216; 310-316; 410- 416).

12. The device (100, 200, 300, 400) of any of the previous claims, furthermore comprising an actuator for closing the jaws (102, 104; 202, 204; 302, 304; 402, 404).

13. A method for providing a metal wire (290) with a thinned wire end, comprising: providing the metal wire (190, 290, 390, 490), and while pulling the wire (190, 290, 390, 490) along the path of axial motion in a device (100, 200, 300, 400) in accordance with any of the previous claims, closing the jaws (102, 104; 202, 204; 302, 304; 402, 404) of each pair of jaws (102, 104; 202, 204; 302, 304; 402, 404) of said device (100, 200, 300, 400) such that the blocks (110- 116; 210-216; 310-316; 410-416) of the jaws (102, 104; 202, 204;302, 304; 402, 404) engage, inducing the wire (190, 290, 390, 490) to zig-zag, so that the wire (190, 290, 390, 490) drags over comers of the blocks (110-116; 210-216; 310-316; 410-416) of both jaws (102, 104; 202, 204; 302, 304; 402, 404) to elongate the wire (190,290, 390, 490) until fracture.

14. The method of claim 12, wherein said closing comprises gradually closing the jaws (102, 104; 202, 204; 302, 304; 402, 404) while pulling the wire (190, 290, 390, 490) along said path of axial motion.

15. The method of any of claims 12 or 13, wherein said inducing the wire (190, 290, 390, 490) to zig-zag comprises stretching an outer, convex part of the zig-zagging wire (190, 290, 390, 490) by at least 3%.

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