DEVICE AND METHOD FOR PRODUCING A SPRING WIRE, DEVICE AND METHOD FOR MAKING A SPRING WIRE, DEVICE AND METHOD FOR PRODUCING SPRINGS FROM A SPRING WIRE, AND SPRING WIRE

Abstract

A device for producing a spring wire includes a wire production apparatus which is designed such that a spring wire can be produced from a raw material, in particular by drawing; a checking unit which is designed such that the spring wire can be checked for flaws, in particular material flaws and surface flaws; and a laser marking unit which is designed such that defective regions of the spring wire, in particular regions of the spring wire having material and surface flaws, can be marked with a laser marking such that part of the surface of the spring wire can be removed or part of the surface of the spring wire can be tempered in such a manner that the color of the surface of the spring wire is changed in this part. The wire production apparatus is designed such that the spring wire can be guided past the checking unit and past the laser marking unit.

Claims

1. A device for producing a spring wire (2), comprising: a wire production apparatus (8) which is designed such that a spring wire (10) can be produced from a raw material, in particular by drawing; a checking unit (14) which is designed such that the spring wire (10) can be checked for flaws, in particular material flaws and surface flaws; and a laser marking unit (18) which is designed such that defective regions of the spring wire (10), in particular regions of the spring wire (10) having material and surface flaws, can be marked with a laser marking (44) such that part of the surface of the spring wire (10) can be removed or part of the surface of the spring wire (10) can be tempered in such a manner that the color of the surface of the spring wire (10) is changed in this part; with the wire production apparatus (8) being designed such that the spring wire (10) can be guided past the checking unit (14) and past the laser marking unit (18).

2. A device for marking a spring wire (21), comprising: a supply unit, in particular a supply roller (22) for supplying a spring wire (10); a checking unit (14) which is designed such that the spring wire (10) can be checked for flaws, in particular for material and surface flaws; and a laser marking unit (18) which is designed such that defective regions of the spring wire (10), in particular regions of the spring wire (10) having material and surface flaws, can be marked with a laser marking (44) such that a part of the surface of the spring wire (10) can be removed or that a part of the surface of the spring wire (10) can be tempered in such a way that the color of the spring wire (10) is changed in this part; with the supply unit (22) being designed such that the spring wire (10) can be guided past the checking unit (14) and past the laser marking unit (18).

3. The device (2) according to claim 1 or 2, wherein the laser marking unit (18) is designed such that, for removing part of the surface of the spring wire (10) in the defective regions of the spring wire (10), it directs a laser beam with a temperature above the melting temperature of the basic material of the spring wire (10) onto the spring wire (10).

4. The device (2) according to claim 1 or 2, wherein the laser marking unit (18) is designed such that, for tempering a part of the surface of the spring wire (10) in the defective regions of the spring wire (10) such that the color of the surface of the spring wire (10) is changed in this part, it directs a laser beam with a temperature of approx. 200° C. to 600° C. onto the spring wire (10).

5. The device (2) according to any of the preceding claims, further comprising a control unit (16) connected to the checking unit (14) and the laser marking unit (18) and designed such that, during operation of the device (2), it receives signals on defective regions of the spring wire (10) from the checking unit (14) and controls the laser marking unit (18) such that the latter introduces at least one laser marking (44) into these defective regions of the spring wire (10).

6. The device (2) according to any of the preceding claims, wherein the laser marking unit (18) comprises a radiation source (38) and/or a scanner optical system (40) or a projection mask and/or a focusing means (42) which is/are arranged such that they are directed towards the moving spring wire (10).

7. The device (2) according to any of the preceding claims, wherein the laser marking unit (18) is designed such that the defective regions of the spring wire (10) are marked such that the laser marking (44) forms a machine-readable code, in particular a line code (54), a barcode (56) or a data matrix code (58), or a machine-readable text, and/or wherein the laser marking unit (18) is designed such that each defective region is respectively provided with the same laser marking (44), or that each defective region is respectively provided with an unambiguously distinguishable laser marking (44), and/or wherein the laser marking (44) contains additional information on the respectively marked defective region.

8. The device (2) according to any of the preceding claims, wherein the laser marking unit (18) is arranged or designed such that the laser marking (44) is applied to the defective region or regions of the spring wire (10) such that it extends at least across large part of the circumference of the spring wire (10), in particular across the entire circumference of the same, or wherein the laser marking (44) is applied to the defective region or regions of the spring wire (10) such that it extends only across a partial region of the circumference of the spring wire (10).

9. The device (2) according to any of the preceding claims, wherein the checking unit (14) for checking the spring wire (10) for flaws is designed as optical checking unit, as eddy current checking unit or as flux leakage measuring unit.

10. The device (2) according to any of the preceding claims, wherein the checking unit (14) and the laser marking unit (18) are arranged beside each other, and wherein in particular the checking unit (14), as seen in the direction of movement of the spring wire (10), is arranged in front of or subsequent to the laser marking unit (18).

11. The device (2) according to any of the preceding claims, further comprising a winding unit (20), in particular a roller, onto which the spring wire (10) including the defective region/regions provided with one or more laser markings (44) can be wound.

12. The device (2) according to any of the preceding claims, further comprising at least one wire guide (12), in particular a first wire guide (12) arranged upstream of the checking unit (14) and the laser marking unit (18), and a second wire guide (12) arranged downstream of the checking unit (14) and the laser marking unit (18) and upstream of the winding roller (20).

13. A method for producing a spring wire (10), comprising the following steps: producing, in particular drawing, a spring wire (10) from a raw material; checking the spring wire (10) for flaws, in particular for material and surface flaws; and marking the defective regions of the spring wire by means of a laser marking unit (18), with the laser marking unit (18) removing part of the surface of the spring wire (10) or with the laser marking unit (18) tempering part of the surface of the spring wire (10) such that the color of said part is changed.

14. A method for marking a spring wire (10), comprising the following steps: supplying a spring wire (10) by means of a supply unit, in particular a supply roller (22); checking the spring wire (10) for flaws, in particular for material and surface flaws; and marking the defective regions of the spring wire by means of a laser marking unit (18), with the laser marking unit (18) removing part of the surface of the spring wire (10) or with the laser marking unit (18) tempering part of the surface of the spring wire (10) such that the color of said part is changed.

15. The method according to claim 13 or 14, wherein the laser marking unit (18) directs a laser beam with a temperature above the melting temperature of the basic material of the spring wire (10) onto the spring wire (10) in order to remove part of the surface of the spring wire (10) in the defective regions of the spring wire (10).

16. The method according to claim 13 or 14, wherein the laser marking unit (18) directs a laser beam with a temperature of approx. 200° C. to 660° C. onto the spring wire (10) in order to temper part of the surface of the spring wire (10) in the defective regions of the spring wire (10) such that the color of the surface of the spring wire (10) is changed in this part.

17. The method according to any of claims 13 to 16, therein the defective regions of the spring wire (10) are marked by means of a laser marking unit (18) such that the laser marking (44) forms a machine-readable code, in particular a line code, a barcode (56) or a data matrix code (58), or a machine-readable text.

18. The method according to any of claims 13 to 17, wherein the defective regions of the spring wire (10) are marked by means of a laser marking unit (18) such that each defective region is respectively provided with the same laser marking (44).

19. The method according to any of claims 13 to 18, wherein the defective regions of the spring wire (10) are marked by means of a laser marking unit (18) such that each defective region is respectively provided with an unambiguously distinguishable laser marking (44), and/or wherein the laser marking (44) contains additional information on the respectively marked defective region.

20. The method according to any of the claims 13 to 19, wherein the laser marking (44) is applied to the defective region or regions of the spring wire (10) such that it extends at least across large part of the circumference of the spring wire (10), in particular across the entire circumference of the same, or wherein the laser marking (44) is applied to the defective region or regions of the spring wire (10) such that it extends only across a partial region of the circumference of the spring wire (10).

21. The method according to any of claims 13 to 20, wherein the method steps of checking the spring wire (10) for flaws and of marking the defective regions of the spring wire (10) are carried out during continuous movement of the drawn wire.

22. The method according to any of claims 13 to 21, wherein the laser marking unit (18) comprises a radiation source (38) and/or a scanner optical system (40) or a projection mask and/or a focusing means (42) which is/are designed such that they are directed towards the moving spring wire (10).

23. The method according to any of claims 13 to 22, wherein checking of the spring wire (10) for flaws is effected by means of an optical checking method or by means of an eddy current checking method.

24. A device for producing springs from a spring wire (60), comprising: a spring wire supply unit (28), in particular a supply roller (22), for supplying spring wire (10) in which defective regions, in particular regions having material and surface flaws, are marked with a laser marking (44); a recognition unit (24) which is designed such that it recognizes laser markings (44) on the spring wire (10); a spring production unit (30), in particular a coiling machine, which is designed such that springs can be produced from the spring wire (10) continuously and without interruption, and in particular can be coiled and cut to length; a discharge unit (32), in particular a discharge duct having a switch, which is designed such that springs produced from spring wire (10) without laser marking are discharged into a first area, in particular a container with non-defective springs (36), and springs produced from spring wire (10) with laser marking (44) are discharged into a second area, in particular a container with defective springs (34).

25. The device (60) according to claim 24, further comprising a control unit (26) connected to the recognition unit (24) and the discharge unit (32) and designed such that, during operation of the device (60), it receives signals on defective regions of the spring wire (10) from the recognition unit (24) and controls the discharge unit (32) such that springs produced from the defective region of the spring wire (10) are passed to the second area, in particular the container with defective springs (34).

26. The device according to claim 24 or 25, wherein the recognition unit (24) is designed as optical recognition unit, as eddy current recognition unit or as a flux leakage recognition unit.

27. A method for producing springs from a spring wire, comprising the following steps: supplying spring wire (10), in which defective regions, in particular regions having material and surface flaws, are marked with a laser marking (44), by means of a spring wire supply unit (28); recognizing laser markings (44) on the spring wire (10) by means of a recognition unit (24); continuous and uninterrupted production, in particular coiling and cutting to length of springs from the spring wire (10) by means of a spring production unit (30); discharging those springs that were produced from spring wire (10) without laser marking into a first area, in particular a container with non-defective springs (36) and discharging those springs that were produced from spring wire (10) with laser marking (44) into a second area, in particular a container with defective springs (34), by means of a discharge unit (32), in particular a discharge duct having a switch.

28. A spring wire (10), comprising: a raw material, in particular of spring steel, having a substantially constant elongated outline; wherein defective regions of the spring wire (10), in particular regions of the spring wire (10) having material and surface flaws, are marked with a laser marking (44) in which the surface of the spring wire (10) is recessed in relation to the surface of adjacent regions and with respect to the longitudinal central axis, or in which the surface of the spring wire (10) is changed in color with respect to the surface of adjacent regions.

29. The spring wire (10) according to claim 28, wherein in case the laser marking (44) is provided in the form of a recessed surface region of the spring wire (10), the recess has a depth from 10 μm to 1 mm as measured from the non-recessed surface to the longitudinal central axis.

30. The spring wire (10) according to claim 28, wherein in case the laser marking (44) is provided in the form of a surface region of the spring wire (10) that is changed in color, the color of the surface region of the spring wire (10) that is changed in color comprises white-yellow, straw-yellow, golden yellow, yellow-brown, brown-red, red, purple, violet, dark blue, cornflower blue, light blue, blue-gray or gray, with the color of the remaining surface regions of the spring wire (10) that are not changed in color being silvery-gray.

31. The spring wire (10) according to any of claims 28 to 30, therein the laser marking (44) forms a machine-readable code, in particular a line code, a barcode (56) or a data matrix code (58), or a machine-readable text, and/or wherein each defective region is respectively provided with the same laser marking (44), or wherein each defective region is respectively provided with an unambiguously distinguishable laser marking (44) and/or wherein the laser marking (44) contains additional information on the respectively marked defective region.

32. The spring wire (10) according to any of claims 28 to 31, wherein the laser marking (44) extends at least across large part of the circumference of the spring wire (44), in particular across the entire circumference of the same, or wherein the laser marking (44) extends only across a partial region of the circumference of the spring wire (10).

33. A device according to any of claims 1 to 12 or 24 to 26, a method according to any of claim 13 to 23 or 27 or a spring wire according to any of claims 28 to 33, wherein the inventive spring wire comprises as material spring steel, in particular SiCr-alloyed spring steel, SiCrV-alloyed spring steel or SiCrNiV-alloyed spring steel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0102] The invention will be explained in more detail in the following on the basis of embodiments with reference to the accompanying drawings in which:

[0103] FIG. 1 shows a schematic view of a spring wire production device according to a first embodiment of the present invention;

[0104] FIG. 2 shows a schematic view of a spring wire marking device according to a second embodiment of the present invention;

[0105] FIG. 3 shows a schematic view of the laser marking unit of the spring wire production device of FIG. 1 or the spring wire marking device of FIG. 2 and the spring wire guided past the same, with the defective regions thereof being marked by the laser marking unit;

[0106] FIGS. 4A-4D show longitudinal and transverse cross-sectional views of exemplary regions of a spring wire;

[0107] FIGS. 5A and 5B show respective schematic views of a spring wire in which four defective regions along the longitudinal extension of the spring wire have been provided with laser markings;

[0108] FIGS. 6A-6C show exemplary illustrations of defective spring wire regions with different laser markings; and

[0109] FIG. 7 shows a schematic illustration of a device for producing springs from a spring wire according to a further embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0110] FIG. 1 shows a schematic illustration of a spring wire production device 2.

[0111] The spring wire production device 2 comprises a wire production apparatus 8, a first wire guide 12, a checking unit 14, a laser marking unit 18, a control unit 16, an additional wire guide 12 and a winding roller 20.

[0112] The wire production apparatus 8 is designed such that a spring wire 10 can be produced from a raw material, in particular by drawing. This is known to the skilled person and need not be explained in more detail here.

[0113] The spring wire 10 is produced continuously by the wire production apparatus 8 and leaves the same towards the right in FIG. 1 and successively passes the first wire guide 12, the checking unit 14, the laser marking unit 18 and the additional wire guide 12, and is finally wound onto winding roller 20. The movement direction of the spring wire 10, which is from left to right in FIG. 1, is indicated by an arrow bearing reference numeral 4.

[0114] By means of the wire guide 12 arranged upstream of the checking unit 14 as well as the wire guide 12 arranged downstream of the laser marking unit 18, the spring wire 10 is guided so exactly that the checking unit 14, which in particular is arranged in stationary manner, is capable of accurately checking the spring wire 10, and the laser marking unit 18, which in particular is arranged in stationary manner, is capable of accurately marking defective regions of the spring wire 10.

[0115] The wire guides 12 thus can be formed in particular as a pair of guide rollers rotating in opposite directions and having the spring wire 10 extending between the same.

[0116] The checking unit 14 is designed such that it checks the spring wire 10 for flaws, in particular for material and surface flaws. The checking unit 14 may be in the form of an optical checking unit or an eddy current checking unit.

[0117] During operation of the spring wire production device 2, the spring wire 10 is continuously moved past the checking unit 14 and the laser marking unit 18, which check the spring wire during movement of the same for material and surface flaws and, in case such flaws are detected, provide the corresponding regions of the spring wire 10 with a laser marking 18.

[0118] When the checking unit 14 recognizes material or surface flaws of the spring wire 10, it issues a corresponding signal to the control unit 16 which then controls the laser marking unit 18, which is arranged subsequent to the checking unit 14 in the direction of movement of the spring wire 10, so as to apply a suitable laser marking to these defective regions of the spring wire 10. Exemplary laser markings are illustrated and described in FIGS. 4 to 6 below.

[0119] The laser marking unit 18 is designed such that the defective regions of the spring wire 10 are identified by a laser marking such that part of the surface of the spring wire 10 is removed, so that the spring wire 10, in the defective regions determined, has one or more recesses in its surface.

[0120] To this end the laser marking unit 18 directs a laser beam, having a temperature above the evaporation temperature of the basic material of the spring wire 10, to the regions of the surface of the spring wire 10 to be marked, so that part of the material of the spring wire evaporates and a corresponding, defined recess is created in the spring wire 10.

[0121] As an alternative, the laser marking unit 18 is designed such that the defective regions of the spring wire 10 are marked with a laser marking such that part of the surface of the spring wire 10 is changed in color as compared to the adjacent regions of the surface of the spring wire 10. To this end, the laser marking unit 18 directs a laser beam onto the corresponding regions of the surface of the spring wire 10, effecting a tempering temperature between 200 and 660° C. in the surface of the spring wire 10, so that an oxide layer is created the color of which is dependent on the respective tempering temperature, as will be described in a different location of this patent application.

[0122] The laser marking unit 18 to this end is directed onto the moving spring wire 10 and, when correspondingly driven by the control unit 16 removes part of the surface of the spring wire 10 or, respectively, changes the color in'said part of the surface of the spring wire 10 by means of a laser beam directed to the spring wire 10.

[0123] The laser marking unit 18 to this end comprises a radiation source and in addition may also comprise a scanner optical system or a projection mask and a focusing means which in the following are illustrated in exemplary manner with reference to FIG. 3.

[0124] When the checking unit 14 detects no material or surface flaws of the spring wire 10, the laser marking unit 18 is controlled by the control unit 16 so as to apply no laser markings to the spring wire 10.

[0125] Finally, the finished spring wire 10, the defective regions of which have been provided with laser markings, is wound onto the winding roller 20.

[0126] At the end of the production process, there is either no further raw material replenished in the wire production apparatus 8, so that the production process ends by itself As an alternative, the spring wire 10, possibly after stopping of the production process, may also be cut off or cut to length. The winding roller 20 having the spring wire 10 wound onto the same then may be removed completely and transported to a spring production device. Thereafter, a new empty winding roller instead of the removed winding roller can be provided for the next production process.

[0127] It is emphasized once more at this location that the checking of the spring wire 10 and the marking of defective regions of the spring wire 10 by the checking unit 14 and the laser marking unit 18 takes place in-line, i.e. during the production process, without the same having to be slowed down or even stopped. This constitutes a particularly efficient, rapid and inexpensive manner of producing spring wire 10, in which at the same time the defective regions can be recognized easily and directly for the subsequent spring production process.

[0128] It is to be understood that the control unit 16 can be connected in addition to the wire production apparatus 8 or the supply roller 22 as well as to the winding roller 20 or can be connected to a control unit of the wire production apparatus 8, the supply roller 22 and the winding roller 20 or can be formed in integrated manner with the same, so that the wire production proper, the feeding speed of the spring wire 10 and winding of the spring wire 10 onto the winding roller 20 can be controlled.

[0129] FIG. 2 shows a schematic illustration of a spring wire marking device 21.

[0130] This spring wire marking device 21 in essence corresponds to the spring wire production device 2, with a supply roller 22 being provided instead of the wire production apparatus 8.

[0131] Like elements are provided with the same reference numerals. For avoiding repetitions, these elements as well as the manner of operation of the same will not be explained again.

[0132] The supply roller 22 supplies the spring wire produced in a previous production step and, in particular, drawn from a raw material, via the wire guide 12 to the checking unit 14 and the laser marking unit 18, where the spring wire 10 is checked and defective regions of the same are marked, before the spring wire 10 is passed through the second wire guide 12 to the winding roller 20 and is wound onto the same.

[0133] The main difference between the spring wire production device 2 of FIG. 1 and the spring wire marking device 21 of FIG. 2 consists in that in the spring wire production device 2 the wire production apparatus 8 constitutes the first part, so that the spring wire 10 is produced and defective regions of the same are detected and marked in one and the same device. In contrast thereto, in case of the spring wire marking device 21, an already produced spring wire 10 is provided which usually is wound onto a roller 22, and this spring wire 10 is supplied via the wire guide 12 to the checking unit 14 and the laser marking unit 18. The production of the spring wire as well as the detection of the defective regions thus is effected at two different locations in case of the spring wire marking device 21.

[0134] FIG. 3 shows a schematic illustration of the laser marking unit 18 and the spring wire 10 guided past the same, with the defective regions of the spring wire 10 being marked by means of the laser marking unit 18.

[0135] The laser marking unit 18 comprises a radiation source 38 for generating a laser beam, a scanner optical system 40 or a projection mask, as well as a focusing means 42. The laser marking unit 18 is arranged such that it is directed onto the moving spring wire 10 and is designed such that the laser beam, when directed onto the moving spring wire 10, is capable of removing regions of the surface of the same in order to apply a laser marking forming a recess in the surface of the spring wire 10, or is designed such that the laser beam, when directed onto the moving spring wire 10, can change the color of this surface region by way of the tempering effect caused by a structural changes in the marginal layer, in order to apply a laser marking to the spring wire 10. The manner in which the radiation source 38, the scanner optical system 40 or the projection mask and the focusing means 42 need to be designed in detail for causing this effect, is known to the skilled person and need not be elucidated in more detail here.

[0136] FIG. 4, by way of its four partial FIGS. 4A, 4B, 4C and 4D, illustrates respective longitudinal and transverse sectional views of exemplary portions of a spring wire 10.

[0137] In the partial FIGS. 4A, 4B, 4C and 4D, a respective longitudinal sectional view illustrates a sectional line A-A, and the transverse sectional view is cut along this sectional line A-A.

[0138] In accordance with partial FIG. 4A, the illustrated portion of the spring wire 10 has a constant elongated outline and has no material or surface flaws, so that this portion of the spring wire 10 has no laser marking.

[0139] In accordance with partial FIGS. 4B, 4C and 4D, the portions illustrated of the spring wire 10 have material or surface flaws not shown here and therefore have each been provided with a laser marking 44 by the laser marking unit 18.

[0140] It can be seen in the longitudinal sectional view of partial FIG. 4B that the laser marking 4 has mutually spaced apart recesses which each have been introduced into an upper region of the spring wire 10 only. Such a laser marking with several recesses introduced may be an introduced machine-readable code as will be explained in more detail in the following with reference to FIG. 6.

[0141] In accordance with partial FIG. 4C, the laser marking 44 applied is a continuous elongated recess introduced on the top side of the upper region of the spring wire 10. This is an elongated marking on the top side of the spring wire 10 that is recognized by an optical recognition unit or a viewer as an elongated line or an elongated bar.

[0142] In accordance with partial FIG. 4D, the laser marking 45 applied is a surface region that has been changed in color by tempering by means of a laser beam and has been introduced on the top side of the upper region of the spring wire 10.

[0143] This is an elongated marking at the top side of the spring wire 10 which, as in case of partial FIG. 4C, is perceived by an optical recognition unit or by a viewer as an elongated line or an elongated bar.

[0144] For example, the surface of the spring wire 10 may be bare and may have a silver-gray color, whereas the laser marking 45 has a brown-red color that has been introduced into the surface of the spring wire 10 by means of a laser beam having a tempering temperature of approx. 250° C. This yields an optically very well perceivable/detectable contrast. It is of course also possible that the basic color of the surface of the spring wire 10 has a color different from silver-gray, and of course, the color of the laser marking 45 may be different as well, for example white-yellow, straw-yellow, golden yellow, yellow-brown, red, purple, violet, dark blue, cornflower blue, light blue or blue-gray. The tempering temperatures necessary therefor are indicated at another location of this patent application.

[0145] It is emphasized here once more that the laser markings introduced do not have the purpose of identifying the spring wire 10 as such, but rather are intended to mark merely the defective regions which are to be recognized automatically in a subsequent spring production process, so that the springs produced from such regions can be automatically singled out.

[0146] FIG. 5 by way of its two partial FIGS. 5A and 5B illustrates schematic views of a spring wire 10 in which four defective regions have been provided with laser markings 46, 48, 50 and 52 as well as 47, 49, 51 and 53, respectively, along the longitudinal extension of the spring wire 10.

[0147] In partial FIG. 5A the laser markings 46, 48, 50 and 52 are provided in the form of recesses in the surface of the spring wire 10, which have been created e.g. by means of a laser beam having a temperature above the evaporation temperature of the basic material of the spring wire 10.

[0148] In partial FIG. 5B the laser markings 47, 49, 51 and 53 are provided in the form of ablation-free surface regions of changed color which for example have been introduced in the surface of the spring wire 10 by means of a laser beam having a defined temperature. The colors of the surface regions brought about by various tempering temperatures are explained elsewhere in this patent application. In practical application it is important that an optically well perceivable/detectable contrast between the color of the surface of the spring wire 10 in the laser markings 47, 49, 51 and 53 and the adjacent regions of the surface of the spring wire 10 results.

[0149] The laser markings 46 and 47, respectively, shown in the frontmost position, i.e. to the very right in FIG. 5A and FIG. 5B, each comprise a transversely extending laser marking on the top side of the spring wire 10 which is perceived by a recognition means or a viewer as a transverse line.

[0150] The second laser markings 48 and 49, respectively, from the front each comprise two spaced apart transversely extending laser markings on the top side of the spring wire 10, which are perceived by a recognition means or a viewer as two parallel transverse lines.

[0151] The third laser markings 50 and 51, respectively, from the front each comprise three spaced apart transversely extending laser markings on the top side of the spring wire 10, which are perceived by a recognition means or a viewer as three transverse lines.

[0152] The rearmost laser markings 52 and 53, respectively, each comprise four spaced apart transversely extending laser markings on the top side of the spring wire, which are perceived by a recognition means or a viewer as four transverse lines.

[0153] Accordingly, each defective region of the spring wire 10 is provided with an unambiguously distinguishable laser marking 46-52, which in the present embodiment are of exemplary nature only. For example, it is possible to associate with the first marking 46 and 47, respectively, the meaning “first defective region in the entire spring wire”, with the second laser marking 48 and 49, respectively, the meaning “second defective region in the entire spring wire”, and so on.

[0154] FIG. 6 by way of its partial FIGS. 6A, 6B and 6C shows exemplary illustrations of defective spring wire regions with different laser markings.

[0155] All of these laser markings have in common that the markings introduced constitute recesses in the surface of the spring wire 10 or regions of the surface of the spring wire 10 with changed color.

[0156] The laser marking 54 constitutes a pattern introduced into the surface of the spring wire 10, which is perceived by a recognition means or a viewer as “TEST, three transverse lines, TEST”, and thus as a third test laser marking applied identifying a defective region of the spring wire 10.

[0157] The laser marking 56 constitutes a barcode which, in contrast to the laser markings described hereinbefore, does not only extend over the top side of the spring wire 10, but around the entire circumference of the spring wire 10. Laser marking 56 constitutes a pattern of circumferential recesses or regions with changed color of different width, with respective spring wire regions located therebetween having the original, non-recessed circumference or the non-recessed height, or having the respective spring wire regions of unchanged color located therebetween, respectively.

[0158] The laser marking 56 formed as such a barcode can be recognized in particular by a recognition means. In addition to the information, that the respective region of the spring wire 10 is defective, such a barcode laser marking 56 is capable of introducing into the spring wire 10 numerous other items of additional information on the kind of the flaw and make the same available for a subsequent spring production machine, e.g. the information on the number of the current flaw on the spring wire 10, the information on the kind of the flaw, e.g. material or surface flaw, additional information on the kind of the material or surface flaw or spring wire dimensions in the defective region.

[0159] The laser marking 58 constitutes a so-called data matrix code which extends only across part of the circumference of the spring wire 10 and forms a pattern of recesses or regions of changed color, which have been introduced into the surface of the spring wire 10.

[0160] Such a laser marking in the form of a data matrix code can be recognized in particular by a recognition unit. Similar to the laser marking 56 provided in the form of a barcode, such a laser marking 58 is capable of introducing into the spring wire 10 a multiplicity of items of information on the defective region and making the same available for a subsequent spring production machine.

[0161] It is to be understood that the laser marking unit 18 has to be designed such that it is capable of introducing laser markings into the circumferential region of the spring wire 10 in which the laser marking is to be produced.

[0162] When a circumferentially broad region and in particular a region of the spring wire extending about the entire circumference of the spring wire 10 is to be marked, it is necessary to provide one or more laser marking units 18 having a laser beam that can be projected in correspondingly broad manner.

[0163] In case of a very simple embodiment that is not illustrated here in a separate figure, the laser marking unit 18 is designed such that it provides any defective region with a simple, identical laser marking.

[0164] FIG. 7 shows a schematic illustration of a device 60 for producing springs from a spring wire, according to a further embodiment of the invention.

[0165] This spring production device 60 comprises a supply roller 22, a recognition unit 24, a spring wire supply unit 28, a spring production unit 30, a discharge unit comprising a container for defective springs 42 and a container for intact or non-defective springs 36, as well as a control unit 26.

[0166] The supply roller 22 may be the winding roller 20 onto which the spring wire 10 produced has been wound and the defective regions of which have been provided with corresponding laser markings.

[0167] This spring wire 10 is passed through a recognition unit 24 and via the spring wire supply unit 28 to the spring production unit 30 proper, where the spring wire is reshaped, in particular coiled and cut to length into separate springs which then are passed to the discharge unit 32 via a discharge duct not shown here.

[0168] The recognition unit 24 is designed such that it recognizes laser markings on the spring wire 10 while the latter is continuously guided through the same. The recognition unit may be in the form of an optical recognition unit, an eddy current recognition unit or a flux leakage recognition unit. In the event that the laser markings are formed as recesses in the surface of the spring wire, as illustrated in FIGS. 4B, 4C and 5A, all three options permit a reliable and non-contacting recognition of defective spring wire regions provided with laser markings. In the event that the laser markings are formed as regions of the surface of the spring wire that are changed in color, as illustrated in FIGS. 4D and 5B, only a recognition unit in the form of an optical recognition unit is capable of reliably detecting the defective spring wire regions provided with laser markings.

[0169] The discharge unit 32 comprises a switch illustrated schematically in FIG. 7, which can be moved such that springs moving in particular by force of gravity through the discharge duct selectively reach the container for defective springs 34 or the container for intact springs 36.

[0170] When the recognition unit 24 recognizes a laser marking on the spring wire 10, it issues a corresponding signal to the control unit 26 which in turn sets the switch of the discharge unit 32 such that springs produced from the spring wire 10 with laser marking enter the container for defective springs 34. When the recognition unit 24 recognizes no laser marking on the spring wire 10, the switch of the discharge unit 32 remains in the position in which the springs produced automatically reach the container for intact springs 36, or is moved into this position in case the recognition unit 24 had recognized a laser marking before.

[0171] The spring production device 60 according to the invention permits a continuous and uninterrupted production of springs from a spring wire 10. Defective regions of the spring wire are recognized automatically, the spring production device 60 however need not be stopped, which would lead to machine downtimes, reduced efficiency as well as higher costs. Rather, the springs produced from such defective regions of the spring wire 10 are fed automatically to a different container, namely the container for defective springs 34.

[0172] While the invention has been described with reference to exemplary embodiments and applications scenarios, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the claims Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims and can be applied to various application in the industrial as well as commercial field.