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Title:
APPARATUS FOR PRODUCING WIRE SPRINGS OF WIRE OF POLYGONAL CROSS SECTION, AND RELATIVE METHOD
Document Type and Number:
WIPO Patent Application WO/2020/201912
Kind Code:
A1
Abstract:
Apparatus for producing wire springs comprising: a first workstation (1) with a wire support (2), and cutting means (3) adapted to cut the wire against said support, a second workstation (5) with a wire winding rod (6), and means for clamping (7) the wire against an end of said rod, a wire carriage (9) adapted to be displaced in a controlled manner in a direction parallel to the axis (X) of the winding rod, and provided with means adapted to avoid the twisting or kinking of the wire between said wire carriage and said rod. Said means comprise a wire outfeed quill (U) having a cross section that is not circular in shape, typically polygonal and in particular rectangular for feeding said wire from said wire carriage, and are adapted to rotate said wire carriage around an axis (A) orthogonal to the wire winding axis so that said outfeed quill is oriented in a selectively controlled manner so as to eliminate the edge with which said wire touches and winds around said winding rod at the point of reciprocal contact. Said angle in particular can be controlled during the central wire winding step. The invention also relates to a corresponding method for producing a wound wire spring.

Inventors:
BORDIGNON ROMEO (IT)
Application Number:
PCT/IB2020/052754
Publication Date:
October 08, 2020
Filing Date:
March 24, 2020
Export Citation:
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Assignee:
BORDIGNON ROMEO (IT)
International Classes:
B21F3/04
Foreign References:
EP1755806A12007-02-28
US1063505A1913-06-03
US5927123A1999-07-27
EP2416031A12012-02-08
Attorney, Agent or Firm:
GIUGNI, Diego et al. (IT)
Download PDF:
Claims:
CLAIMS

1) Apparatus for producing wound wire springs whose wire shows a polygonal section, particularly rectangular, comprising:

- a first working station (1 ) provided with a support member (2) of the wire, preferably cylindrical and adapted to be partially wound by a length of wire (4), and cutting means (3) provided at said working station and adapted to cut said length of wire against said support acting as an anvil,

- a second working station (5) provide with a wire supporting and winding rod (6) and wire engagement and clamping means (7) for securing a portion of said wire at an end portion of said rod (6),

- a wire carriage (9) adapted to transfer a length of wire (4) from said first working station to said second working station with a displacement in a direction that is rectilinear and parallel to the axis (X) of said rod, and provided with a non circular quill (“U”) which quill is a projection on a plane“N” orthogonal to the exit direction (“M”) of said wire from the driving means (26, 27, 28, 29) determining the opening (30) towards the outside of said wire, characterized in that it is able of imparting a rotation to said wire carriage (9) and therefore the relevant quill (“U”) around a line (A) which line is parallel to the orthogonal direction (M) of said quill (“U”).

2) Apparatus according to claim 1 , characterized in that said rotation is defined by an angle“h” formed:

- by said“X” axis, and

- by a straight line“r” formed by the intersection, on a second plane (P2) passing trough said axis (X) and parallel to said quill (“U”), of a first plane which

• before of the rotation (P1 ) passes trough said axis (X), is parallel to said direction (M), and is integral with said wire carriage (9), and

• after the rotation (P3) of the wire carriage interferes to said second plane (P2) and crosses said axis (“X”) determining in it the vertex (K) of said angle (“h”).

3) Apparatus according to claim 1 or 2, characterized in that it is able of rotating said wire carriage (9) so that said angle (h) results a not zero value.

4) Apparatus according to anyone of claims 1 to 3, characterized in that it comprises rotating means commanded and controlled by control means so that said rotation is automatically carried out any time and in any position along the path of said rod (6), both along one direction and along the opposite direction without interruptions. 5) Apparatus according to any of the previous claims, characterized in that it is able of rotating said wire carriage (9), during the final step (F3) of said wire winding around said rod (6), so that said angle (h) will assume a value which is different than the value showed during the central step (F2) of the wire winding.

6) Apparatus according to any of the previous claims, characterized in that it is able of imparting said rotation to said wire carriage (9) in a selectively pre-determined way so that said rotation takes place in successive steps, wherein during a first step said rotation is actuated with a pre-determined rotation sense around a line (A) parallel to a direction (M) orthogonal to said quill (“U”), and during a second step said rotation is actuated in a rotation sense opposed to the rotation sense in said first rotation step.

7) Method for producing a wound wire spring, comprising the steps of:

- cutting a first end of the spring wound at less than a turn,

- displacing said first end of the spring onto a wire-winding rod,

- clamping of said first end of the spring against said rod,

- rotating said rod while at the same time displacing said wire so as to produce a wire spring,

- unclamping said first end of the spring from said rod,

- returning said spring to a cutting station,

wherein said wire is extracted from a wire carriage which determines an exit quill (“U”) of said wire having a non-circular shape, characterized in that during the rotation step of said rod and simultaneous displacing of said wire carriage, the same wire carriage is rotated around an axis (A) parallel to the exit direction (M) of the wire from said wire carriage, and arranged on a plane (Q1 ; - Q2) orthogonal to the axis (x) of said rotation rod (6).

8) Method according to claim 7, characterized in that, said rotation is carried out automatically at any time and in any position along said winding rod, both in a direction and in the opposite direction without interruptions.

9) Method according to claim 8, characterized in that during the end step (F3) of the wire winding around said rod (6), said wire carriage is submitted to a rotation which takes a value different from the value taken during the central step (F2) of said wire winding. 10) Method according to claim 7-9, characterized in that, during the winding step of the wire around said rod (6), said rotation of the wire carriage is implemented in successive times, in which:

- during a first time, said rotation is made with a pre-determined direction of winding rotation around an axis (A) parallel to the exit direction (M) of the wire from said wire carriage, and arranged on a plane (Q1 ; Q2) orthogonal to the axis (x) to said rotation rod (6),

- and during a second time, said rotation is made with a direction of rotation opposed to the direction of rotation of said first time.

Description:
APPARATUS FOR PRODUCING WIRE SPRINGS OF WIRE OF POLYGONAL

CROSS SECTION, AND RELATIVE METHOD

DESCRIPTION

TECHNICAL FIELD

[0001] The present invention refers to an apparatus and a method for producing coiled wire springs, according to the preamble of claims 1 and 6, as generally disclosed in Patent US-A-5,927,123 and Patent EP 1 755 806 B1 .

[0002] In the following description, springs of this type will be identified simply with the term“wire springs”, which however are formed with a wire having a cross section that is not circular, that is, a broken-line polygonal cross section.

PRIOR ART

[0003] It is well known that coiled wire springs are generally made by winding on a relevant rod, called“core” in the technical jargon, a continuous length of wire, which is appropriately cut to create the spring. The cross section of a just produced spring is also the initial cross section of the spring being formed.

[0004] It is also known to the skilled person in the art, and this is only briefly mentioned here, that an automatic apparatus for the production of these springs comprises in particular (with reference to fig. 8):

- a first workstation 1 provided with a thick support element provide with a plane surface and adapted to be partially wound by a length of wire 4, and a cutting means 3 arranged at said first workstation and adapted to cut said length of wire against said plane surface acting as an anvil;

- a second workstation 5 provided with a supporting and winding rod 6 for said wire, and adapted to be rotated around its axis, and engaging and clamping means 7 for securing a portion of said wire at an end portion of said rod 6;

- a wire carriage 9, adapted to transfer a length of wire from said first workstation to the second workstation in a rectilinear direction that is parallel to the direction of the axis“X” of said rod.

[0005] It should be stated that the cross section of the wire can ideally be represented by any polygonal, but typically and preferably the invention applies to a wire having a rectangular cross section, and therefore the figures which follow refer to such a shape of the wire, without thereby limiting the scope of application of the invention to wires having other shapes/cross sections that are however not circular. [0006] The production of wire springs with said apparatus allows a high productive flexibility and a considerable output; however, said apparatus, and the relative method of processing the wire in mass production, are often subject to a particular effect that seriously limits the performance of the same.

[0007] This effect is caused by the circumstance that, when attempting to wind a wire having a polygonal cross section on a supporting rod so as to create an elongated spiral, the wire carriage must be placed on a more“frontward” position with respect to the point of contact of the wire with the rod, and therefore, as the wire is to be wound starting from said “more frontward” position, said wire arranges itself necessarily in an “oblique” position with respect to the axis of the relative rod, as symbolically illustrated in Fig. 1 .

[0008] In Fig. 2 is illustrated symbolically a simplified and perspective view of the extension of a generic coil delivered by the wire carriage during a process of winding the extended spiral of a wire spring, in which the extension is correctly carried out, that is, with one side of the wire (in this case the side“L2”, also identified by the surface portion A - B - B1 - A1 of Fig. 2), which lies completely flat on the surface of the winding rod 6.

[0009] Flowever, and with reference to Fig. 3, there is often the condition that, if a wire 4 with, for example, a square cross section is to be wound on the rod 6, and particularly if said wire 4 is markedly elongated along its side“B - C” which is set in the direction orthogonal to the surface of the rod, compared to the side“A - C” which instead lies on the external surface of said rod, then there is the effect that all the wire is pushed to rotate around it.

[0010] Thus there is the situation, illustrated symbolically in Fig. 3, that the wire is pushed to rotate around said zone of first contact, and therefore it is subjected to a“twisting” (or “kinking”) action of the sides of the wire.

[0011] This situation causes a series of problems described below with reference to Figs. 4, 5 and 5A:

a) the first problem results from the fact that when a metal wire of rectangular cross section is wound around a rod, with reference to Figs. 4, 5 and 5A, it can be seen that, in the absence of particular devices, there is generally the situation that the resulting spring displays certain irregularities due to said“twisting” around its longitudinal median axis; in the most serious cases, the spring cannot be used because its basic characteristics are no longer satisfied;

b) the second problem concerns the pitch of said spring; it is well known that the pitch of a wound wire spring, in general use, must be absolutely constant to guarantee the uniformity of its characteristics and performance in any condition of use/compression; looking at Fig. 4 it can be seen, however, that the pitch“P1” between two turns is completely different, that is, it is smaller than the pitch“P2” between two other coils adjacent to each other; as already mentioned, this problem causes a reduced performance of the spring;

c) the third problem is caused by the circumstance that, at a certain point in the spring, the wire twists upon itself to the point at which it displays outwardly a side that normally is not the one facing outwards; Fig. 5 shows a drawing of a wire spring that displays this problem due to the presence of an external zone“A” placed“crosswise”, and visibly different from zone“B”, that is more normal and correct, that can be seen at another point of the same spring. An even more serious situation can be seen in Fig. 5A, which shows how the wire, which ideally must be arranged with the smaller side inside and outside the spring, instead is arranged with the larger side facing inwardly and therefore also outwardly, due to the effect of the rotation or winding of the wire on itself during the winding of the spring. Evidently, this circumstance makes the spring almost always unusable; d) the fourth problem is caused by the fact that, when said state of “twisting” occurs, the wire is no longer stretched out on one of its sides on the external surface of the rod on which it is wound, as is shown symbolically in Fig. 6, but it is engaged on said rod with only an edge“g”, as is shown symbolically in Fig. 7. In addition to being a functional problem in itself, this circumstance also causes an evident increase in the outer dimensions“D2” of the spring itself, with respect to the nominal dimension“D1” (Fig. 7), since the coils of the spring are arranged “diagonally” and not“flat-wise”, as they should be and as shown in Fig. 6, which impairs its use in all the very frequent cases in which the outer dimensions of the spring are a binding requirement;

e) a further problem stems from the fact that, if the problems just described are to be eliminated or at least limited, it is necessary to“adjust” the variables on the apparatus and on the manufacturing process that cause the foregoing problems, so as to determine the best combination of the variables involved which, as desired, would eliminate or limit said problems. These variables are, mainly, the pitch of the spring, its dimensions, the geometry of the wire, its tension before it is wound, the distance of the wire from its feeding quill to the surface of the winding rod, and naturally the nature and characteristics of the material from which the wire is made. This problem is particularly substantial the more the wire is elongated, in the sense that its side in contact with the external surface of the rod is sensibly smaller than the side that must, instead, be orthogonal to said surface.

OBJECTIVES OF THE INVENTION

[0012] It would therefore be desirable, and it is the main purpose of the present invention, to propose a solution for the production of coil wire springs formed with a wire having other than a circular cross section that makes it possible to completely eliminate the risk of producing wire springs with the wire“twisted” around the winding rod - and therefore unusable due to the problems described above - by means of a simple adjustment of the arrangement and orientation of the wire carriage with respect to the winding rod.

[0013] A further important purpose of the invention is offered by the possibility of manufacturing wound coil wire springs adapted to present a differentiated operating characteristic and that can be made in a single wire winding step, by simply rotating the wire carriage at the right moment, or after having wound a predetermined number of coils.

[0014] A further purpose of the invention is to be able to adopt the present invention on previously utilized automatic apparatuses, by means of few and simple modifications on both the apparatus and the processing method.

[0015] To achieve the above objectives, an apparatus and a method for producing wound wire springs are proposed according to the accompanying claims.

LIST OF FIGURES

[0016] Characteristics and advantages of the invention will be better appreciated from the following description, given solely by way of example and without limitations, and with reference to the enclosed drawings, wherein:

- Fig. 1 illustrates a simplified external view of the wire supporting and winding rod 6, of the wire carriage 9, and of the direction“d” of movement of said carriage parallel to the axis“X” of said rod 6;

- Fig. 2 illustrates a simplified external and enlarged perspective view, of the zone of engagement between the wire 4 and the rod 6, in a correct wire winding condition;

- Fig. 3 illustrates a see-through and conventionally represented view of the view of Fig. 2, but with the wire carriage 9 seen from“underneath” the rod 6, and with the wire twisted upon itself before being wound on the rod, and therefore showing that its contact with said rod becomes in fact an edge“S”;

- Figs. 4, 5 and 5A illustrate respectively side views of two spirally wound coiled wire springs showing respective winding defects; - Fig. 6 illustrates an enlarged cross section, according to a sectional plane passing through the axis“X” of the rod 6, of a portion of the wire winding zone in a correct winding condition;

- Fig. 7 illustrates the same view of Fig. 6, but in an anomalous and flawed condition of the wound wire on the relative rod;

- Fig. 8 is a perspective view from outside of the two workstations and of the wire carriage in an apparatus according to the invention;

- Fig. 9 is a simplified view in plane cross section of a plane intersecting the median axis“A” of the feeding quill“U” of the wire carriage 9, and orthogonal to the axis“X” of the winding rod 6, in which said quill“U” is aligned with said rod;

- Fig. 9A is a view similar to Fig. 9, but in which said quill“U” is not aligned with said rod, and the wire 4 is noticeably far from the same;

- Fig. 10 illustrates in an absolutely symbolic and simplified manner a perspective view of the feeding quill in a wire carriage, seen from a quasi-frontal point of view;

- Fig. 10A shows a schematic and plane view of the feeding quill of the wire carriage of Fig. 10 according to the sectional plane“S” of Fig. 10;

- Fig. 1 1 and Fig. 12 illustrate two partial views and in simplified perspective of a machine according to the invention, in two respective moments of operation according to the invention;

- Fig. 13 illustrates a view similar to Fig. 3, in which the wire exits the wire carriage which carriage was previously rotated according to the invention;

- Fig. 14 illustrates a lateral view of the wire winding rod and of the wire wound on it, with the indication of certain portions of the same wire;

- Fig. 15A and 15B illustrate respective cross sections according to sectional planes intersecting the axis of rotation of a given wire, in two respective different winding manners;

- Fig. 16 illustrates two examples of the graphic representation of Flooke’s Law relative to the respective Figs. 15A and 15B;

- Fig. 17A illustrates a symbolic representation of a combination of the two different manners of winding the same wire on the same rod;

- Fig. 17B is perspective and symbolical representation of a wound spring according to Fig. 17A;

- Fig. 18 is a symbolic and simplified representation of the graph of “Flooke’s Law” relative to the wire spring shown in Fig. 17; - Figs. 19, 20 and 21 illustrate respective symbolic lateral views of a winding rod and of the relative wire carriage in three different orientations of the latter with respect to said rod;

- Fig. 19A is a general and perspective representation of a wire exiting from the relative wire carriage before starting to be wound on the relative winding rod;

- Figs. 20A and 21 A illustrate representations, respectively, of the perspective and symbolic views of Figs 20 and 21 .

DESCRIPTION OF THE INVENTION

[0017] With reference to the figures, an apparatus for the production of a wire spring according to the invention is made up of the following means and devices which refer to a prior-art apparatus, to which will be added the characteristics described and illustrated below.

[0018] With reference to Fig. 8, a typical basic configuration is to be considered: an apparatus according to the prior art comprises:

- a first workstation 1 equipped with a wire support element 2, often of cylindrical shape but segmented by a sectional plane parallel to the axis of the cylinder and adapted to be partially wound by a length of wire 4, and a cutting means 3 arranged at said first workstation and adapted to shear said length of wire against said support used as an anvil;

- a second workstation 5 provided with a wire supporting and winding rod 6, and with engaging and clamping means 7 for a portion of said wire at the end of said rod 6 mounted on said workstation 5;

- a wire carriage 9, adapted to transfer a length of wire 4 from said first workstation to the second workstation with a rectilinear motion and parallel to the direction of the axis X of said rod; in addition, as shown in Figures 9, 9A, 10A, said wire carriage 9 is provided with a wire feeding quill“U”, which, as will be specified later, is not a physical opening but only a geometrical shape, said opening having a polygonal, i.e., not circular, cross section, preferably rectangular, as shown in the same figure; in Fig. 10, said feeding quill is shown in the hatched area and identified with numeral“30”.

[0019] The characteristics of said wire feeding quill“U” will be better detailed hereunder, because the invention is based essentially on the possibility of modifying the orientation of said quill“U”.

[0020] See also Fig. 19A, which provides a general view of the part of the apparatus that is interested by the invention.

[0021] The present invention has been generated by the observation that, as shown symbolically in Fig. 3, the body of the wire 4 can often be twisted upon itself with an undesired rotation with respect to the original position of the same wire at the exit of the wire carriage, and this undesired rotation continues for the remaining part of the winding of the wire, and therefore of the finished spring.

[0022] In fact, when the wire exits from the quill“U”, its initial portion exhibits a particular orientation, or rather one that is physically imposed by the shape and orientation of the outline of the quill“U”, or simply by the fact that it maintains the orientation of the final driving means of said wire before it exits from said wire carriage 9.

[0023] However, as the wire becomes elongated toward the winding rod 6, it tends to become twisted upon itself, with a rotation as illustrated and under the effect described above, to the point of assuming the configuration illustrated symbolically in Fig. 3.

[0024] Only by way of example, and with reference to Fig. 3, it can in fact be seen that the output side“A-B” of the wire from the relative quill when it arrives above the rod 6, after having made half a turn around the rod, is rotated counterclockwise by an angle“S- A”, becoming the side“A2-B2” which corresponds exactly to the original side“A-B”.

[0025] The same thing would happen even if the elements described above were arranged in a“specular” manner compared to the manner that is illustrated in figures from 1 to 3, and thus with the engaging means 7 shown to be to the right of the observer compared to what is illustrated in Fig. 1 ; the difference observed is that in this case the wire would be twisted naturally in a direction opposite to the way it is shown, and thus the same wire would be twisted clockwise.

[0026] The invention consists in countering said twisting that occurs between the wire carriage 9 and the rod 6 with an equal but opposite effect, that is in imposing on said twisting a“preventive counter-twisting” that opposes the spontaneous twisting described above, and that offsets the final effect.

[0027] In order to produce said preventive counter-twisting, it would thus be necessary that, according to the invention, the wire be rotated in a particular direction before arriving where it could touch and wind itself on the rod 6.

[0028] To identify said preventive counter-twisting, the following is to be done: since the invention is based essentially on the orientation of said quill“U”, it is necessary that this be defined very precisely, according to the construction which follows.

[0029] In the final exit path from the wire carriage, the wire is naturally guided by the mechanical driving means, which determine its exact position.

[0030] These driving means can be of various types: for example, they can be a simple opening or passage between mechanical parts that face each other, or they can consist of a simple roll or pairs of rolls of different types, etc.

[0031] Figs. 10 and 10A show an example of such driving means. Fig. 10 illustrates a perspective view of an opening of a generic wire carriage 9, determined by two opposing and parallel walls 26, 27, which delineate an internal jacket; wherein are arranged two other separate and parallel opposing walls 28, 29.

[0032] Between said two pairs of opposing walls 26, 27 28, 29 is thus formed the physical opening 30.

[0033] The winding wire is made to pass through said physical opening 30.

[0034] This wire, at the more external end part of said walls 26, 27, 28, 29 assumes, during the extraction of the same wire, a definite direction“M”, as shown symbolically in Fig. 10, obviously determined by the reciprocal size and geometry of the same walls 26, 27, 28, 29.

[0035] Considering now Fig. 10A, the plane “N” is shown therein as being a plane orthogonal to said direction“M” and containing the material portion, that is, the physical and final portion, of said opening 30.

[0036] The geometrical projection of said physical opening 30 on said plane“N” to which these figures refer (hence it is a plane figure) is defined as quill“U”.

[0037] It will be easily seen now that, with the construction just illustrated, said opening 30 and said quill“U” coincide; however, in the general case, the final mechanical wire output portion from said carriage 9, is not regular or arranged on a plane, but could be for example“stepped”, and therefore it could be very possible to have the condition in which said elements, the opening 30 and the quill“U”, do not coincide.

[0038] More generally, to define the output quill“U” from a generic wire carriage 9, the mechanical means that determine in their final part the instant outfeed direction of the wire are considered, whichever form they are made.

[0039] Considering now a plane orthogonal to said instant outfeed direction; said plane is assumed to be arranged exactly at the end portion, that is, the external one, of said wire driving means.

[0040] And assuming now that the projection of said opening, or the passage in the external end part of said wire driving means, is defined and delimited on said orthogonal plane.

[0041] The generally valid definition given is that said opening“U” is determined by the projection of said passage/opening on said orthogonal plane in said instantaneous outfeed direction.

[0042] It will then be evident that said quill“U”, as defined above, will be understood below not like a specific mechanical part, (in fact, it is not a mechanical part), but as being only that geometrical place and plane determined as just explained above.

[0043] In summary, said quill“U” is formed by the projection on a plane“N” orthogonal to the outfeed direction“M” of said wire from the driving means 26, 27, 28, 29, which determine the physical opening 30 exiting of the wire carriage 9.

[0044] It will also be evident that the wire to be wound does not necessarily have a rectangular cross section, which however is within the invention, but it can also have any other shape, as long as it is polygonal.

[0045] Assuming now a plurality of straight lines M1 , M2, M3, M4..., all parallel to each other and having the same direction as said direction“M”; each of said straight lines M1 , M2, M3, M4... thus differs from another one of said lines only insofar as their spatial position is concerned, but not on account of their orientation, as they are all parallel in construction.

[0046] The invention consists in making said wire carriage 9, and therefore the relative quill“U”, rotate around an axis“A” or“A-1”, (hereafter, the straight line“A-1” will be mentioned again as that line, external to said quill“U” and that can also be external to the materiality of the same wire carriage 9, and that is the possible line of rotation of said quill; however, for simplicity of depiction, this line“A-1” will not be explicitly illustrated), parallel to the orthogonal direction to said quill“U”, and thus said wire carriage is adapted to rotate around any of said parallel straight lines M1 , M2, M3, M4..., all of them being parallel to the single direction“M”.

[0047] With reference to Figs. 9, 9A, assuming that the wire 4 exits from the wire carriage 9 where the wire 4 passes through a quill“U”, in which said quill“U” is oriented so that, if said quill is sectioned on a plane that is orthogonal to the axis“X” of the rod 6 and passes through said quill“U”, two different configurations will be possible; as are schematically illustrated in Figures 9 and 9A.

- 1 st configuration: in Fig. 9 it can be seen that the projection of said quill is“aligned” directly with the center of the axis“X” and therefore it directly intersects said rod 6;

- 2nd configuration: in Fig. 9A it can be seen that the relative quill“U” is spatially arranged so that its projection on a plane passing through said axis“X” and parallel to said quill does not intersect the rod 6 but passes far from said rod at a distance “d”.

[0048] To improve this information, it is assumed that this latter case is shown in actuality in figures 20A, 21 A and 19A.

[0049] Flereinbelow, this last condition will be considered, because this is the general case, to which can naturally be referred the case shown in Fig. 9A.

[0050] Considering now Fig. 1 1 ; in this figure, the plane“P1” is defined as that plane that passes through said axis“X” of the rod 6 and is parallel to one of said lines M1 , M2, M3, M4..., relative to a quill“U” of a wire carriage 9; as was previously seen, said plane“P1” could cross a portion of said quill “U” or not, but this difference will not modify the discussion which follows, which can be applied identically to both possibilities.

[0051] With letter“A” is indicated the specific line among all said straight lines M1 , M2, M3, M4..., around which said wire carriage 9 is to be rotated; as previously mentioned, said line“A” can intersect said quill“U” or not; for the sake of simplicity in Fig. 1 1 said line “A” is shown as intersecting said quill“U” at point A-A, and Figures 19, 20 and 21 illustrate in a simplified manner some possibilities of rotation, and therefore the relative positions, of the wire carriage if said carriage rotates around an axis“A” passing through said quill “U”.

[0052] According to the invention, the wire carriage rotates around an axis parallel to the direction orthogonal to said quill“U”, and therefore the same wire carriage can be adapted to rotate around any of said parallel lines M1 , M2, M3, M4...., as all of them are parallel to the single direction“M”, and, as the case may be, they are identified as the line“A” (if it passes through the quill“U”), or otherwise as another line (not explicitly shown).

[0053] In Fig. 1 1 is also defined a second plane“P2” that passes through the same axis “X” and that is also orthogonal to said plane“P1”.

[0054] Evidently, by interpretation, said axis“X” is also the projection of said plane“P1” on said plane“P2”.

[0055] Now, it is assumed that said plane“P1” is“integrated” with said wire carriage 9, and finally, assumed that said wire carriage 9 and thus said plane“P1” is rotated around said line“A”, that is, the line chosen by the manufacturer on the basis of constraints or other choices that are not evinced here.

[0056] Whichever is the line around which said wire carriage 9 rotates, be it one passing through said quill“U”, be it one that is external to this but that passes through the same carriage 9, be it in the more general case that said line passes externally to the same carriage 9, said plane“P1”, now integrated with the carriage 9, naturally rotates with the carriage itself.

[0057] In the present example, illustrated in Figures 1 1 and 12, it is assumed that said rotation takes place around the line“A” that passes through said quill“U”.

[0058] Fig. 12 shows that the new position of the original plane“P1”, by effect of the rotation of the wire carriage 9, is revealed now in a new position, that is, one represented by the new plane“P3”.

[0059] Since the plane“P2” maintains its original position, the new intersection between said new rotated plane“P3” and the original plane“P1” becomes a line“r” that passes through a specific point“K” located on said axis“X”.

[0060] Still with reference to Fig. 12, it can be seen that said line“r” crosses said axis “X” with an angle“h”, wherein said specific point“K” is the vertex; evidently, if said carriage 9 is rotated again until it returns to the original position, it can be seen that said angle“h” decreases progressively until it is canceled out, when the carriage 9 returns exactly to the original position.

[0061] In short, said rotation is defined by the angle“h” formed:

- by said axis“X”, and

- by a line“r” formed:

• by the intersection on a second plane P2; passing through said axis“X” and parallel to said quill“U”,

• of a first plane P3 which

- before the rotation passes through said axis“X”, is parallel to said exit direction (M), and is integral with said wire carriage, and is identified as plane“P1”, and

- after said rotation it assumes the final position P3, which interferes with said second plane P2 and crosses said axis“X”, determining in it the vertex“K”.

[0062] Thus it must be concluded that if a measurement parameter of the rotation of the carriage around an axis that is orthogonal to the respective quill“U” is to be assumed, after the rotation, said angle“h” must not be a null angle.

[0063] All the foregoing discussion has been presented to express the circumstance that is at the basis of the invention; this circumstance consists of the fact that it has been noticed and thus discovered that:

- if in an apparatus that performs a process of winding a wire spring, there is the unwanted occurrence of the wire twisting upon itself and therefore around the axis of the rod, the quill“U” is rotated and therefore, if necessary, this is also done with the wire carriage 9 (depending on the possible mechanical links between the wire carriage and the relative quill),

- in such a manner that said angle“h” does not become null, so that it is possible to detect, preferably experimentally, a specific value for said angle“h” such that said twisting is canceled out, and the wire lies as in figures 2 and 13.

[0064] Particularly in the comparison of Figures 3 and 13 it is possible to appreciate the different angling, with respect to the rod 6, between the quills“U1” and“U2” in the two cases illustrated.

[0065] In fact, it can be seen that in Fig. 3 the segment“A-A1” crosses the segment“B- B1” at point“E”, and the segment“C-C1” crosses the segment“D-D1” at point“F”, which visually demonstrates the phenomenon of twisting.

[0066] Unlike this situation, Fig. 13 shows that the relative quill“U2” is oriented in a manner dissimilar from the orientation of quill “U1” which is the case in Fig. 3, and therefore this circumstance is the reason for which, in Fig. 13, the relative segment“A- A1” does not cross the segment“B-B1” again, and the relative segment“C-C1” does not cross again the segment“D-D1”.

[0067] The complexity of the foregoing description is due to the fact that it will not always be possible to rotate the wire carriage around an axis passing exactly through the quill “U”; in fact, there could be mechanical and functional constraints in the same apparatus that prevent or make it difficult to rotate the carriage around an axis passing exactly through said quill; a factor that further complicates the functioning of the invention.

[0068] The operation just described of rotation of the wire carriage and therefore of the wire outfeed quill, causes the desired effect of rotating, in a definite direction, said wire before it begins to wind around the rod 6, and therefore, if during the winding operation said wire tends to twist spontaneously in a counterclockwise rotation (as in Fig. 3), then said twists in the counterclockwise direction and in the clockwise direction sum up and therefore cancel each other out, as symbolically illustrated; ultimately, the consequence is the final desired effect that the wire is applied to the external surface of the rod evenly and without twisting.

[0069] The present invention offers the possibility of having some advantageous improvements.

[0070] The first improvement is achieved easily by the provision of means of rotating the wire carriage 9 that can impart to said wire carriage 9 a selectively determined rotation. This feature makes it possible in fact to effectively“correct” the rotation of the wire and to compensate it with a counter-rotation that is appropriate to the final purpose, on the basis of the different variables involved, and in particular the dimensions of the wire, its proportions and the winding pitch.

[0071 ] In other words, it should be noted that for what concerns the above considerations the correction consists of a rotation of the wire carriage thanks to said controlled driving means of rotation so as to carry out automatic rotations at any moment and in any position along the length of the rod 6, also uninterruptedly, in both directions of rotation, with angles of rotation predetermined on the basis of said variables resulting from the characteristics of the wire used and from the demands of the finished product (spring), like pitch and load.

[0072] It is evident, therefore, that with the apparatus and the method of production of a spirally wound coiled wire spring of the present invention, advantageously the production of a spring having different characteristics in different portions can be achieved without interruptions that could slow down the pace of production.

[0073] With reference to Fig. 14, a further improvement consists of the fact that said counter-rotation means are adapted to give the wire:

- no specific value of counter-rotation angle during the initial wire winding step“F1”, when the first coil is being formed, which generally must be wound on a plane orthogonal to the axis “X” of the rod 6 and thus, while not undergoing any spontaneous rotation/twisting, must also not be subjected to any“counter-rotation” step;

- a preset value of counter-rotation angle during the central step“F2” of winding the coil, when there is the necessity of a“counter-rotation” effect as explained above, so as to avoid the“twisting” or kinking effect;

- and again no specific value of counter-rotation angle during the final spring coiling step“F3”, in which said final step creates the final coil of the spring being wound, which becomes the initial coil of the next spring, and which therefore must be a flat coil.

[0074] One advantageous improvement consists of the fact that said rotation or counter rotation means are selectively programmable in such a manner that, during an automatic process for the production of a successive series of wire springs, said angle of rotation (h) is actuated in an automatic mode based on said steps F1 , F2, F3.

[0075] Said improvement, of a predefined rotation or counter-rotation drive, on the basis of the processing step, and of other variables, like the dimension of the wire, its proportions and its winding pitch, are all within the comprehension of a person skilled in the field, and therefore their detailed description will be omitted.

[0076] With reference to Figures 15A to 18, a further advantageous variant of the invention consists of the following: since the possibility identified of modifying the orientation of the wire carriage offers the advantage of determining, and therefore possibly correcting, the type of support of the wire on the rod, this possibility can also be used to wind the wire on the rod in a not uniform manner, but with completely innovative and particularly advantageous characteristics; in fact, it should be remembered that, according to Flooke’s Law, the force“F” applied to a spring determines its deformation, or elongation Έ”, according to the formula:

F = k E in which “k” is the elastic constant of the spring.

[0077] It is assumed that the operation of two different springs is shown according to Hooke’s Law, in which the wire is the same and has a markedly elongated rectangular cross section, that is, with a“short” side and a“long” side.

[0078] Assuming also that said two springs are wound on identical winding rods with the same manners of winding, and the same length, and in particular that the same pitch is used, with the only difference being that one of said springs, the spring M1 , is wound with the short side adhering to the surface of the rod, while the spring M2 is wound with the long side adhering to the rod.

[0079] The cross section of a plane passing through the axis of the respective identical rods 6 is respectively illustrated in Figures 15A and 15B, which represents the circumstance that the spring M1 is significantly“weaker” than the spring M2.

[0080] The behavior of said two different springs M1 and M2 will naturally be different, and Hooke’s Law for said two springs is illustrated in a schematic and simplified form in the graphs of Fig. 16.

[0081 ] These behaviors are universally recognized and are at the basis of the calculation of the wire springs, but they are however called to mind to introduce the following improvement and to justify their operation.

[0082] In practice, to obtain a given resistant elastic strength“Fk” with the spring“M1” it will be necessary to impress on it an elongation“E-1”, while to obtain the same resistant strength“FK” with the spring M2 it will be sufficient to impress on it an elongation“E-2” that is significantly smaller, as can be observed in Fig. 16.

[0083] If said two springs are now joined at rest at one respective end, a final spring will be obtained having a cross section according to the plane passing through the common axis“X” as symbolically illustrated in Fig. 17.

[0084] In practice, as said graph suggests, said final spring will behave as follows: if a force“Fk” is applied to said spring resulting from the joining of the two springs M1 and M2, to which naturally both springs will be subjected to the same extent because they are connected to each other along their common axis, the elongation of the spring M1 will naturally be equal to the value of “E-1”, while the elongation of the spring M2 is determined by the value of“E-2”.

[0085] Thus the spring formed in this manner will have, if subjected to the same force “Fk”, the overall value of elongation equal to:“E-1” +“E-2”, represented by point“T” in Figure 18. [0086] If said spring is compressed further, at a certain point the elongation of the “weaker” spring, that is, M1 , ends (that is, in technical terms, it“bottoms out”), and therefore only the function of the spring M2 remains, which naturally will have a well- known behavior, the same as said spring M2 will have by itself alone, as can be seen in Fig. 16.

[0087] In practice, therefore, the final overall behavior of the association of said two springs will be represented by the graph of Fig. 18, in which the section upwards from point“T” is obviously aligned with the section relative to the spring M2 by itself, because in fact upwards from said point“T” the combined spring behaves exactly as if it were the spring M2 alone.

[0088] Thus is obtained a spring with a differentiated behavior based on the range of motion of the spring, or, in other terms, based on the force already applied.

[0089] To achieve springs of this type with differentiated characteristics while using the same wire, according to the present invention, the possibility of appropriately rotating the wire carriage during the production of a single wire spring formed with wire with a suitable elongate cross section is utilized; now, bearing in mind that the teachings of present invention are to rotate in an appropriate manner said wire carriage to avoid the twisting of the wire on the rod, and thus to enable it to wind correctly, in the sense that one side of the wire lies flat to the cylindrical surface of the rod, the present invention teaches instead to “aggravate” the spontaneous winding of the wire so that said twisting is worsened to a point where it is not the correct side of the wire that is wound, but instead the side orthogonal to the same is wound, which in normal conditions would be the “wrong” side.

[0090] This entails that, if for a certain wire winding portion the wire carriage is rotated in a certain direction, the wire is wound in an initial segment with a winding that will be defined as correct; if after this initial segment the wire carriage is rotated in the direction opposite to the previous rotation, and said second and opposite rotation is maintained for an appropriate angle of rotation and for a desired length of a further final segment of the resulting portion of spring, in the end a type of spring will be obtained whose flat section passing through the axis of the relative rod is illustrated schematically in Fig. 17A. Fig. 17B illustrates a simplified representation of the new configuration of the spring of Fig. 17A.

[0091] Therefore, to obtain the above results, the apparatus will be equipped with a wire carriage provided with control means adapted to actuate the rotation in one direction or in the other direction so as to achieve, selectively, for example: - a first type of winding the wire without any need of correcting the orientation of the wire carriage 9, as schematically illustrated in Fig. 19;

- or a second type of winding the wire by applying a clockwise rotation“R-A” of the wire carriage 9 in a counter-clockwise rotation of the wire according to an axis“A” arranged on a plane “Q1” orthogonal to the axis “X” of the relative rod 6, as schematically illustrated in Figures 20 and 20A: in particular, Fig. 20A illustrates a perspective view corresponding to Fig. 20, in which said wire carriage 9 is seen frontally. Considering an arbitrary plane“Q1” orthogonal to the axis“X” of the rod 6, and the plane“G1” as representing a reference orientation of the wire carriage 9; in this solely representative figure, said counter-clockwise rotation“R-A” is observed between said planes“Q1” and“G1”;

- or a third type of winding the wire achieving a clockwise rotation“R-O” of the wire on a relative axis“A” arranged on a plane“Q2” orthogonal to the axis“X” of the relative rod 6, as illustrated schematically in Fig. 21 .

[0092] Similarly to the case of Figs. 20 and 20A, Fig. 21 A is seen in particular as showing a perspective view corresponding to Fig. 21 , in which said wire carriage 9 is seen frontally. In said Fig. 21 A is considered the arbitrary plane“Q2” (parallel to the previous plane“Q1” and possibly coincident with this) orthogonal to the axis“X” of the rod 6, and the plane “G1” as representing the same reference orientation of the wire carriage 9, defined in Fig. 20A. In this solely representative figure, said rotation“R-O” is observed between said planes“Q2” and“G1”, which however in these figures is achieved in a clockwise rotation and no longer a counter-clockwise rotation.

[0093] This peculiarity presented as a matter of principle, therefore makes it possible to build a spring that is adapted to present a differentiated characteristic of operation, and that can also be manufactured in a single wire winding step, by simply rotating the wire carriage at the appropriate moment, or after having wound a preset number of coils.

[0094] The possibility of obtaining the spring having an appropriately differentiated behavior in a single processing step, is naturally advantageous in a large number of applications, as it makes it possible to simplify and thus economize on both the construction and the use of springs having different characteristics in any portion of their extension.