Apparatus and method for straightening metal wires - Patents.com

Abstract

The present invention relates to a device (10) for straightening a metal wire (W), comprising a support structure (11) to which at least a straightening unit (12) configured to reduce tension in the metal wire (W), a main tension unit (13) configured to apply a constant pulling force to advance the metal wire (W), and an exit unit (14) configured to guide the metal wire (W) along an exit axis (X). The present invention also relates to a method for straightening the metal wire (W).

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for straightening metal wire that can be used in feeding machines for processing elongated metal products of the type that can be used, for example, in the manufacture of building reinforcement materials. In the following description, metal wire is understood to mean both rods and precut bars, as well as actual metal wire. [Background technology]

[0002] Devices for straightening metal wire for use in machines for producing electrowelded mesh, stirrup bending machines, or bending / forming machines are known.

[0003] Known straightening devices comprise a straightening unit comprising a series of one or more rollers through which the metal wire passes, and a pulling unit arranged downstream of the straightening unit, configured to apply a constant pulling force to the metal wire along the direction of travel of the metal wire.

[0004] Straightening is an operation necessary to straighten the wire by relieving residual tensions that may be present in the metal wire due to various causes, for example, generated as a result of uneven cooling during the hot manufacturing process, caused by the unwinding of the metal wire from a coil, or generated during the rolling process.

[0005] In addition to residual tension, metal wires may also have irregular cross-sectional shapes that often prevent current straightening devices from operating effectively continuously over extended periods of time without any apparent performance degradation. Irregular cross-sectional shapes of metal wires can also cause reading errors in conventional contact-type wire length measurement devices such as encoders.

[0006] These problems are particularly true in the case of metal wire for rebar, which has both discontinuous surfaces, such as ribs, and shapes that are not always perfect.

[0007] Simple operations on metal wires are in fact conditioned by the tensions present in the metal wires, so that the geometric shapes created with them tend to lose and not maintain the desired spatial arrangement, so that if the spatial arrangement must be flat when installed, such as in reinforcing brackets, you end up with a three-dimensional spatial shape bracket that is unusable or of poor quality and unreliable after installation, or in the case of machines that manufacture electric welded mesh, the bar must be straightened enough to be loaded automatically by the machine.

[0008] Even when the mesh is produced directly from a wound roll, a proper in-line straightening operation is required to create regular panels made up of straight wires.

[0009] Examples of mechanical wire straightening devices are described in Chinese Utility Model No. 213002131, Chinese Utility Model No. 210547659, European Patent Application Publication No. 0362055, and Swiss Patent No. 669128.

[0010] There is therefore a need to develop an apparatus and related method for straightening metal wires that overcomes at least one of the shortcomings of the state of the art.

[0011] To achieve this, the technical problem of achieving uniform tensioning and straightening over the entire length of the metal wire without discontinuities in performance must be overcome.

[0012] In particular, it is an object of the present invention to realize a machine and develop a method for uniformly, continuously, and efficiently straightening metal wire.

[0013] Applicant has made, tested and embodied the present invention to overcome the shortcomings of the prior art and to attain these and other objectives and advantages. Summary of the Invention

[0014] The invention is set forth and characterized in the independent claims. The dependent claims describe further features of the invention or variants of the main inventive idea.

[0015] In accordance with the above objectives, in order to solve the above disclosed technical problem in a new and original way and also achieve considerable advantages compared to the prior art, the inventive device for straightening a metal wire comprises a support structure to which are attached, in order, at least a straightening unit configured to reduce tension in the metal wire, a main tensioning unit configured to apply a constant pulling force to advance the metal wire, and an exit unit configured to guide the metal wire along an exit axis.

[0016] According to one aspect of the invention, the apparatus further comprises at least one calibration unit arranged upstream of the straightening unit, the calibration unit comprising at least two rollers configured to receive the metal wire therebetween along an inlet axis and exerting a longitudinal flattening action on the sides of the metal wire to shape the cross section of the metal wire.

[0017] As a result, the metal wire is continuously and uniformly processed in the straightening unit and the pulling unit, and the cross section of the metal wire is made uniform, which reduces and eliminates problems in reading the length of the metal wire using a contact-type wire length measuring device such as an encoder.

[0018] According to another aspect of the invention, the calibration unit comprises at least one other roller, the at least two rollers and the other roller defining a first group of rollers and being arranged angularly offset from each other by the same offset angle.

[0019] According to another aspect of the invention, the calibration unit may include a second group of rollers disposed downstream of the first group of rollers and including other rollers disposed angularly offset from each other by the same offset angle, the second group of rollers may be disposed in a rotated configuration relative to the first group of rollers.

[0020] According to another aspect of the invention, the roller has a cylindrical peripheral forming surface.

[0021] In accordance with another aspect of the invention, according to a further embodiment, the roller may have a peripheral defining surface that is recessed circumferentially towards the center of the roller.

[0022] According to another aspect of the invention, the circumferentially recessed peripheral defining surface has a radius of curvature that is greater than a nominal radius of the metal wire.

[0023] According to another aspect of the invention, the tensioning unit comprises two rollers arranged at different heights and defining between them an S-shaped path for the metal wire.

[0024] According to another aspect of the invention, the exit axis is parallel to the entrance axis and vertically offset by an amount equal to the sum of the distance between the centers of the tensioning rollers and the radius of the tensioning rollers.

[0025] According to another aspect of the invention, each of the tensioning rollers has a "V" shaped circumferential seat for the metal wire.

[0026] According to another aspect of the invention, the seat has a seat angle of 50° to 100°, preferably 60° to 90°.

[0027] According to another aspect of the invention, the sheet is provided with recesses or ribs.

[0028] According to another aspect of the invention, the tensioning unit comprises one or more pressure rollers arranged around the tensioning roller for pressing a metal wire into the sheet of the tensioning roller.

[0029] According to another aspect of the present invention, the outer circumferential surface of the pressure roller faces the sheet provided on the tension roller, so that the metal wire is sandwiched between the tension roller and the pressure roller, which enhances the stability of tensioning, prevents the wire from slipping or coming off, and improves the reliability of the entire tensioning unit.

[0030] According to another aspect of the invention, the exit unit comprises two different groups of rollers.

[0031] According to another aspect of the invention, the exit unit comprises a first row of exit rollers having a horizontal axis and a second row of exit rollers perpendicular thereto.

[0032] The inventive method for straightening a metal wire includes at least one step of straightening the metal wire, performed by a straightening unit, a step of pulling the metal wire, performed by a tensioning unit, and a step of guiding the metal wire, performed by an exit unit along an exit axis.

[0033] According to one aspect of the present invention, the method further includes a calibration step performed by the above-mentioned calibration unit prior to the straightening step, in which the at least two rollers receive the metal wire between them along an inlet axis and exert a longitudinal flattening action on the sides of the metal wire to shape the cross section of the metal wire.

[0034] According to another aspect of the invention, the calibration step occurs with at least a first roller group including three rollers positioned around the metal wire angularly offset from one another by the same offset angle.

[0035] According to another aspect of the invention, after the calibration step, the cross section of the metal wire has a uniform profile with at least three calibrated sides between which there is an equal number of non-flattened sides. The number of calibrated sides depends on the number of rollers acting on the metal wire. For example, in the case of two groups each containing three rollers, the profile of the cross section of the metal wire will rock six calibrated sides and six non-flattened sides.

[0036] Advantageously, a slight horizontal adjustment on 4, 6 or 8 symmetrical sides of the metal wire, depending on the configuration of the calibration unit, can prevent the metal wire from rotating about its axis in all subsequent movements determined by the rollers (whether pulling, guiding or straightening). This rotational stability also benefits machines downstream of the device of the invention, since it can greatly simplify the adjustment of all subsequent equipment and also improves the consistency of the pulling, measuring, straightening, stirrup bending and forming operations.

[0037] According to another aspect of the invention, after the calibration step, the final cross-sectional area of ​​the metal wire is smaller than the initial cross-sectional area of ​​the metal wire by a value in the range of 0.5% to 1.5%, preferably about 1%. The calibration performed is therefore very limited, not significantly changing the height of the ribs previously created to improve the adhesion of the metal wire in place. Thus, even after calibration, the metal wire continues to meet the characteristic adhesion parameters of metal wire for reinforced concrete applications established by national regulations.

[0038] These and other aspects, features and advantages of the present invention will become apparent from the following description of some embodiments thereof, given by way of non-limiting example with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0039] [Figure 1]FIG. 1 is a schematic side view of an apparatus for straightening metal wires according to the present invention. [Figure 2A] FIG. 2A is a view taken along section IIA of FIG. [Figure 2B] FIG. 2B is a view taken along section IIB of FIG. [Diagram 3] FIG. 3 is a view along section III of FIG. [Figure 4] FIG. 4 is a side view of FIG. [Diagram 5] FIG. 5 shows a modification of the embodiment of FIGS. [Figure 6] FIG. 6 shows a modification of the embodiment of FIGS. [Figure 7] FIG. 7 is a side view of a roller of a calibration unit having a cylindrical peripheral forming surface. [Figure 8] FIG. 8 shows a modification of the embodiment of FIG. 7, in which the peripheral surface is concave. [Figure 9] FIG. 9 is a schematic side view showing a tension roller coupled to a pressure roller for tensioning a metal wire. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] It must be made clear that the phraseology and terms used in this specification, as well as the figures of the accompanying drawings, have the sole function of better illustrating and explaining the invention, the scope of protection of which is defined by the claims, and that their function is to provide a non-limiting example of the invention itself.

[0041] To facilitate understanding, the same reference numbers have been used wherever possible to identify identical common elements in the drawings, it being understood that elements and features of one embodiment may be conveniently combined or incorporated in other embodiments without further description.

[0042] Description of Some Embodiments of the Invention With reference to FIG. 1, an apparatus 10 for straightening a metal wire W according to the invention is suitable for preparing a product for feeding into a work machine, such as a bending / forming machine, a machine for manufacturing metal mesh for construction, or other machines that are known and therefore not shown in the drawings.

[0043] The metal wire W has an average diameter between about 3 mm and about 20 mm, more typically between about 3.5 mm and about 16 mm. The metal wire W may, for example, be ribbed, i.e., the metal wire W may have raised surface ribs extending in the longitudinal direction, and may optionally be deployed in a helical fashion.

[0044] The apparatus 10 comprises a support structure 11 to which at least are attached, in sequence relative to the direction of travel of the metal wire W, a straightening unit 12 configured to reduce the tension present in the metal wire W, a tensioning unit 13 configured to apply a constant attractive force to the metal wire W, and an exit unit 14 configured to guide the metal wire W along an exit axis X.

[0045] The apparatus 10 further comprises a calibration unit 15 arranged upstream of the straightening unit 12 and equipped with at least two rollers 16, 17 configured to receive the metal wire W between them along an entrance axis Y, which in the configuration described herein is parallel to the exit axis X, and to exert a longitudinal flattening action on the sides of the metal wire W in order to shape the cross-section of the metal wire W. With reference to Fig. 2A, the cross-section of the metal wire W at the entrance may have an irregular shape, whereas the cross-section at the exit shown in Fig. 2B has a regular and uniform shape.

[0046] At least two rollers 16, 17 are operatively disposed around the metal wire W to press the same segment of the metal wire W simultaneously but in different directions, e.g., opposite directions.

[0047] The calibration operation on the metal wire W is a preparatory operation to enable both the straightening unit 12 and the tensioning unit 13 to perform their functions on the metal wire W effectively and continuously.

[0048] 3 and 4, the calibration unit 15 includes a first group of rollers 16, 17, 18, and a second group of rollers 16', 17', 18' arranged downstream of the first group of rollers 16, 17, 18 along the inlet axis Y in the traveling direction of the metal wire W.

[0049] The number of rollers 16', 17', 18' of the second roller group is preferably equal to the number of rollers 16, 17, 18 of the first roller group, although a solution in which the number of rollers in the first and second roller groups is different, i.e. does not correspond in number, is not excluded.

[0050] The first and second roller groups consist of three rollers 16, 17, 18 and 16', 17', 18', respectively, preferably arranged symmetrically with respect to a centre point defined by the inlet axis Y or, equivalently, by the longitudinal extension axis of the metal wire W, as shown in FIG. 3.

[0051] The rollers 16, 17, 18 and 16', 17', 18' rotate in the same advancing direction as the metal wire W and are distinct from one another but identical to one another, for example having the same diameter and the same peripheral shape.

[0052] The rollers 16, 17, 18 and 16', 17', 18' are arranged to define between them a passage channel for the metal wire W. The cross section of the passage channel is smaller than the cross section of the metal wire W, so that it is subjected to a flattening action.

[0053] The rollers 16, 17, 18 and 16', 17', 18' are arranged angularly offset from one another by the same offset angle α, which may be preferably equal to about 120° for three rollers, so that the rotation axes of the rollers 16, 17, 18 intersect between them at an angle equal to the offset angle α.

[0054] If the number of rollers 16', 17', 18' in the second roller set is different from the number of rollers 16, 17, 18 in the first roller set, the offset angle α may be different.

[0055] 3, the second set of rollers 16', 17', 18' is arranged in a rotated configuration with respect to the first set of rollers 16, 17, 18, for example with a rotation angle β equal to 60°. For purposes of explanation only, the rotated configuration is understood considering the inlet axis Y as the center of rotation, or equivalently, considering the longitudinal extension axis of the metal wire W as the center of rotation.

[0056] Thus, the rollers 16, 17, 18 and 16', 17', 18' flatten the metal wire W along six different directions, which are pairwise opposed.

[0057] Thus, the cross section of the metal wire W after passing through the calibration unit 15 has six calibrated sides with an equal number of non-flattened sides between them (FIG. 2B). Overall, the cross section of the metal wire W becomes more uniform and the nominal cross section of the metal wire W is reduced by about 1%. However, this value ensures that the minimum height of the ribs on the surface of the metal wire W is maintained within the parameters defined by the standard.

[0058] In this way, the initial shape of the cross section of the metal wire W becomes generally symmetrical, and the metal wire W is ready to be uniformly and continuously processed by the straightening unit 12 and the tensioning unit 13 .

[0059] According to an embodiment, the rollers 16, 17, 18 and 16', 17', 18' have cylindrical peripheral forming surfaces 16a, 17a, 18a and 16a', 17a', 18a', respectively (Figure 7), adapted to define six spaced apart planes having an angular pitch equal to the offset angle α.

[0060] According to a further embodiment, the peripheral forming surfaces 16a, 17a, 18a and 16a', 17a', 18a' of the rollers 16, 17, 18 and 16', 17', 18' may be circumferentially concave towards the center of the roller (FIG. 8). The concave radius of curvature of the peripheral forming surfaces 16a, 17a, 18a and 16a', 17a', 18a' is preferably greater than the average radius of the metal wire W.

[0061] According to a possible embodiment, the first set of rollers 16, 17, 18 may be different from the second set of rollers 16', 17', 18'. For example, the first set of rollers 16, 17, 18 may have cylindrical peripheral forming surfaces 16a, 17a, 18a and the second set of rollers 16', 17', 18' may have concave peripheral forming surfaces 16a', 17a', 18a' or vice versa.

[0062] According to possible embodiment variants, the calibration unit 15 may comprise a single roller group consisting of more than three rollers, for example four or more rollers, or several separate groups consisting of two or more rollers. For example, in Figures 5-6, the calibration unit 15 comprises two roller groups consisting of two rollers 16, 17 and 16', 17', the two rollers in each roller group being offset from each other by an offset angle α equal to 180° and the rotation angle β between the two roller groups being equal to 90°.

[0063] Referring to FIG. 1, the tensioning unit 13 comprises two coplanar tensioning rollers 13a, 13b.

[0064] The tensioning rollers consist of an upper tensioning roller 13a and a lower tensioning roller 13b, which are arranged at different heights and define between them an S-shaped path for the metal wire W. This path runs vertically. Thus, the exit axis X is offset vertically with respect to the entry axis Y. The vertical offset is equal to the sum of the distance between the centers of the tensioning rollers 13a, 13b and the radii of the tensioning rollers 13a, 13b themselves.

[0065] The tension rollers 13a, 13b each have a horizontal axis of rotation.

[0066] According to a possible embodiment, the tensioning rollers 13a, 13b of the tensioning unit 13 may each have a vertical axis of rotation, in which case the S-shaped path of the metal wire W develops horizontally and the inlet axis Y and the outlet axis X are always parallel but horizontally offset.

[0067] Such a configuration of the tensioning unit 13 serves to increase the tensioning force of the metal wire W, since the metal wire W must also pass through the calibration unit 15.

[0068] According to an embodiment, the tension rollers 13a, 13b have a "V" shaped sheet 19 around their periphery, which is configured to receive the metal wire W to achieve its interlocking effect and drag it more effectively.

[0069] The "V" shape of the seat 19 is characterized by a seat angle γ that varies from a minimum of about 50° to a maximum of about 100°, and preferably varies from about 60° to about 90°.

[0070] According to a variant, the sheet 19 may have recesses or ribs in order to improve the adhesion effect on the metal wires W.

[0071] The tensioning unit 13 may also include one or more pressing rollers 13c arranged to cooperate with the tensioning rollers 13a, 13b to press the metal wire W into the sheet 19 of the two tensioning rollers 13a, 13b, thereby improving the tensioning effect exerted by each tensioning roller 13a, 13b.

[0072] The pressure roller 13c has a rotation axis parallel to the rotation axes of the tension rollers 13a and 13b.

[0073] The pressing roller 13c is movable toward / away from the tension rollers 13a, 13b. In other words, the position of the pressing roller 13c is adjustable relative to the positions of the tension rollers 13a, 13b. Thus, the pressing roller 13c can apply an adjustable pressure to the metal wire W, which is advantageous in that metal wires W having different diameters can be flattened.

[0074] However, further configurations of the tensioning unit 13 are possible and may, by way of example, include a single tensioning roller (eg, an upper roller) preceded by a return roller or pulley.

[0075] In any case, all these configurations must be suitable to ensure the correct pulling force on the metal wire W. In a further embodiment solution, for example, the pulling unit 13 comprises a winch, i.e. one or more pairs of rollers that are appropriately grooved, shaped, partially motorized and in contact and coupled, allowing the metal wire W to be advanced in the desired way.

[0076] The straightening unit 12 comprises a number of straightening wheels, seven in the example described herein, some of which are fixed straightening wheels 12a integral with the support structure 11 and others of which are movable straightening wheels 12b fixed to a carriage that is vertically movable in order to vary the passing gap and thus the pressure exerted on the metal wire W.

[0077] The fixed straightening wheel 12a and the movable straightening wheel 12b define a straightening axis between them, which in the illustrated case coincides with the inlet axis Y.

[0078] In the example of FIG. 1, the straightening wheels 12a, 12b have horizontal axes of rotation.

[0079] According to a possible embodiment, a similar further straightening unit can be arranged before the straightening unit 12, but with a straightening wheel with an axis arranged at 90 degrees, i.e. a vertical axis of rotation. This further straightening unit is arranged between the calibration unit 15 and the straightening unit 12.

[0080] The outlet unit 14 or guiding unit makes it possible to guide and further straighten the metal wire W which leaves the tensioning unit 13 and travels towards an operating station (not shown) of a work machine arranged downstream.

[0081] The exit unit 14 comprises a first row of exit rollers 14a having a horizontal axis and a second row of exit rollers 14b perpendicular thereto.

[0082] The operation of the device 10 described so far, which corresponds to the method of the present invention, comprises at least the following steps: a step of straightening the metal wire W, performed by a straightening unit 12, a step of pulling the metal wire W, performed by a tensioning unit 13, and a step of guiding the metal wire W, performed by an outlet unit 14 along an outlet axis X.

[0083] The method further includes a calibration step performed by a calibration unit 15 prior to the straightening step, in which at least two rollers 16, 17 receive the metal wire W between them along an inlet axis Y and exert a longitudinal flattening action on the sides of the metal wire W to shape the cross section of the metal wire W.

[0084] It will be apparent that modifications and / or additions to components may be made to the apparatus 10 and method described above without departing from the field and scope of the present invention as defined in the claims.

[0085] Although the present invention has been described with reference to some specific examples, it is clear to a person skilled in the art that other equivalent configurations of the device and method for straightening metal wires can certainly be realised, which have the characteristics as described in the claims, and thus are all included in the field of protection defined by the claims. In the following claims, the only purpose of the references in parentheses is to improve their readability, and they must not be considered as a limiting factor with regard to the field of protection defined by the claims.

Claims

1. A device (10) for straightening a metal wire (W), comprising: A support structure (11), said support structure (11) is fitted with at least, in order, a straightening unit (12), a main tensioning unit (13) and an outlet unit (14) configured to guide the metal wire (W) along an outlet axis (X); The device (10) further comprises: at least one calibration unit (15) arranged upstream of said straightening unit (12), said calibration unit (15) comprising at least two rollers (16, 17) configured to receive said metal wire (W) therebetween along an inlet axis (Y); An apparatus (10) comprising:

2. The calibration unit (15) comprises at least one other roller (18), The rollers (16, 17, 18) define a first group of rollers and are angularly offset from one another by the same offset angle (α).

2. The device (10) according to claim 1 .

3. the calibration unit (15) comprises a second roller group arranged downstream of the first roller group and comprising other rollers (16', 17', 18') arranged angularly offset from each other by the same offset angle (α); The second group of rollers is arranged in a rotated configuration relative to the first group of rollers (16, 17, 18).

3. The device (10) according to claim 2.

4. The rollers (16, 17, 18; 16', 17', 18') have cylindrical peripheral forming surfaces (16a, 17a, 18a; 16a', 17a', 18a').

4. Device (10) according to claims 2 and 3.

5. The rollers (16, 17, 18; 16', 17', 18') have peripheral forming surfaces (16a, 17a, 18a; 16a', 17a', 18a') that are recessed in the circumferential direction toward the center of the roller.

4. Device (10) according to claims 2 and 3.

6. The circumferentially recessed peripheral forming surfaces (16a, 17a, 18a; 16a', 17a', 18a') have a radius of curvature greater than the nominal radius of the metal wire (W).

6. The device (10) according to claim 5.

7. The tensioning unit (13) comprises two rollers (13a, 13b) arranged at different heights and defining an S-shaped path for the metal wire (W) between them.

2. The device (10) according to claim 1 .

8. The exit axis (X) is parallel to the entrance axis (Y) and is vertically offset by an amount equal to the sum of the distance between the centers of the tensioning rollers (13a, 13b) and the radius of the tensioning rollers (13a, 13b).

8. The device (10) according to claim 7.

9. Each of the tensioning rollers (13a, 13b) has a "V" shaped circumferential seat (19) for the metal wire (W).

8. The device (10) according to claim 7.

10. Said seat (19) has a seat angle (γ) between 50° and 100°, preferably between 60° and 90°.

10. The device (10) according to claim 9.

11. The sheet (19) is provided with recesses or ribs.

10. The device (10) according to claim 9.

12. The tensioning unit (13) comprises one or more pressure rollers (13c) arranged around the tensioning rollers (13a, 13b).

8. The device (10) according to claim 7.

13. The outlet unit (14) comprises two different series of rollers (14a, 14b) 2. The device (10) according to claim 1 .

14. The exit unit (14) comprises a first row of exit rollers (14a) having a horizontal axis and a second row of exit rollers (14b) perpendicular thereto.

2. The device (10) according to claim 1 .

15. A method for straightening a metal wire (W), comprising at least: one step of straightening said metal wire (W), carried out by a straightening unit (12); a step of tensioning said metal wire (W), carried out by a tensioning unit (13); a step of guiding said metal wire (W) performed by an outlet unit (14) along an outlet axis (X); Including, The method further comprises: a calibration step carried out by a calibration unit (15) before the straightening step, in which at least two rollers (16, 17) receive the metal wire (W) between them along an inlet axis (Y) and apply a longitudinal flattening action to the side surfaces of the metal wire (W) to adjust the cross-sectional shape of the metal wire (W); A method comprising:

16. The calibration step occurs by means of at least a first group of rollers comprising three rollers (16, 17, 18) angularly offset from one another by the same offset angle (α) and arranged around the metal wire (W).

16. The method of claim 15.

17. After the calibration step, the cross section of the metal wire (W) has a uniform profile with at least three calibrated sides between which there are an equal number of non-flattened sides.

16. The method of claim 15.

18. After the calibration step, the final cross-sectional area of ​​the metal wire (W) is smaller than the initial cross-sectional area of ​​the metal wire (W) by a value in the range of 0.5% to 1.5%.

16. The method of claim 15.

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