[0001] The present invention refers to an improved type of machine for forming metal wire,
adapted to allow for a greater productivity and throughput through an increase of
the travelling speed of the wire in the appropriate wire forward-feeding and coiling
units.
[0002] Wire-forming machines, in which metal wire is processed in special forming units
in view of being converted into corresponding finished parts or items, in particular
wire springs and the like, are variously known in the art.
[0003] In view of appropriately reaching said forming units, the wire must in the first
place be unwound from the related coil-stock in which it has been wound for storage
after wire-making; it must then be properly straightened and pushed, with the aid
of such gripping and pushing means as largely known in the art, into said forming
units; in particular, said wire gripping and pushing means are formed by the so-called
and well-known "gear-cases ". As illustrated in the prior patent EP 0 682 997, these
gear-cases are constituted by assemblies comprising a plurality of pairs of synchronously
rotating rollers, these pairs being arranged in a sequence and in a proper alignment,
in such a manner as to enable the wire to be successively gripped by successive pairs
of rollers provided so as to be matching with each other along a generatrix thereof,
and pushed in an orderly manner, and with an adequate force, towards said forming
units.
[0004] Also largely known in the art is the fact that there are a number of applications
in which the wire, before being formed in said forming units, must also undergo a
twisting or coiling operation. For example, this occurs when forming special springs,
or similar items, which have substantially a three-dimensional expansion.
[0005] In this case, it is a largely known fact that said gear-case does not remain spatially
stable with respect to the coil-stock from which the wire is being unwound, and therefore
with respect to the environment, but rather is caused to rotate in a continuous manner,
as the wire is unwound and fed forward, about an axis coinciding with the feeding
axis of the wire.
[0006] With reference to the accompanying Figure 1, which is a perspective schematic view
of a wire forming machine provided with such a gear-case as described above, it can
be noticed that said gear-case 1 is firmly and rotatably joined to a rotating plate
21, which is appropriately engaging rotatably driving means that are adapted to substantially
impart the desired rotary motion to said gear-case 1, and the related rollers 3, in
which said rotary motion can be easily graduated, i.e. adjusted and synchronized with
the forward-feeding motion and speed of the metal wire 4.
[0007] This solution is largely used in the art without encountering any particular problem,
except for the fact that the productivity of the machine may undergo considerable
limitations.
[0008] As a matter of fact, owing to the gear-case being an inherently heavy member and,
above all, featuring a considerable inertia with respect to the afore-cited axis of
rotation, if abrupt speed variations or reversals in the direction of rotation are
to be brought about, it is quite clear and obvious that the highest possible angular
acceleration will in these cases be the one produced by said driving motor, and imparted
to said rotating plate 21, compatibly with the resisting inertia of said gear-case.
[0009] It practically ensues that, if the wire is to be twisted or coiled according to a
very close pattern, so that said rotating plate must therefore rotate at a correspondingly
high speed, owing to the latter being actually limited - as explained above - by the
inertia of the gear-case, the need arises for also the feed-forward speed of the metal
wire to be reduced accordingly, in order to obtain the desired twisting or coiling
pattern.
[0010] Considering that it is actually the feed-forward speed of the wire through the machine
that contributes in a decisive manner to the overall productivity of the machine,
it can be most readily appreciated that the inertia of said gear-case ultimately plays
a key-role in determining the productivity of the machine and, as a result, the economic
import thereof.
[0011] It would therefore be desirable, and it is actually an object of the present invention
to provide a wire forming machine with a gear-case rotating in a controlled and variable
manner about the axis of the wire, in which said gear-case has an inertia that is
sensibly lower than the inertia typically featured by prior-art gear-cases.
[0012] Such a machine shall further be easy to manufacture using existing, readily available
techniques, tools and materials, and shall be competitive in its construction and
easy to use; preferably, its implementation shall be such as to basically involve
such modifications as are compatible with currently available and produced machines,
while the newly introduced features shall by no means affect the overall reliability
of the machine itself.
[0013] According to the present invention, these aims, along with further ones that will
be apparent in the following description, are reached in a particular kind of wire
forming machine that is provided with such operation and control means as described
below by way of non-limiting example with reference to the accompanying drawings,
in which:
- Figure 2 is a vertical and cross-sectional plan view of a first arrangement according
to the present invention;
- Figure 3 is a longitudinal cross-sectional plan view showing symbolically the arrangement
illustrated in Figure 2;
- Figure 4 is a symbolical front view of the geometry of a second embodiment of the
arrangement according to the present invention;
- Figures 4A and 4B are a side view and a perspective view, respectively, of an arrangement
according to the present invention, the geometry of which is illustrated in Figure
4 above;
- Figure 5 is a symbolic perspective view of an improved embodiment of a machine according
to the present invention;
- Figure 6 is a plan view of the arrangements illustrated in Figure 5, as seen from
a distant position along the axis of the metal wire;
- Figure 7 is a view of a symbolically illustrated variant in the number and the related
arrangement of the gear-cases of a machine according to the present invention;
- Figure 8 is a perspective view of a further arrangement of a machine according to
the present invention;
- Figure 9 is a top plan view of the arrangement illustrated in Figure 8;
- Figure 10 and Figure 11 are views of two different operating set-ups of the machine
illustrated in Figures 8 and 9;
- Figure 12 is a perspective view of a different embodiment of the arrangement illustrated
in Figure 8;
- Figure 13 is a front elevational plan view of the arrangement illustrated in Figure
12.
[0014] With reference to the above-cited Figures 2 and 3, the gear-case, which shall be
referred to as the wire forward-feeding and coiling unit 2 from now on in this description,
is comprised by an outer casing 10, preferably of the load-bearing or structural kind,
at least a pair of mutually opposing pull-in, i.e. feed-forward rollers 3, 3A, in
which there is provided a symmetrical groove 5 adapted to receive the wire 4 and tightly
grip it with a combined pincers-like effect, so that the synchronous rotation of said
rollers causes the wire to move forwards at the desired rate or speed.
[0015] Said two rollers 3 and 3A are shrink-fitted on or similarly attached to respective
driving axles 11, 12 jutting into said outer casing 10, inside which they are rotatably
supported and held in position in a stable manner with the aid of means that are commonly
known in the art.
[0016] On each one of said axles 11, 12, inside said outer casing 10, there are shrink-fitted,
or anyway press-fitted, respective motion transmission members 13, 14, which are adapted
to transmit the rotary motion of a driving shaft 15, which is also provided inside
said outer casing 10, to said driving axles 11, 12.
[0017] According to the present invention, in view of reducing as much as possible the moment
of inertia of said driving shaft 15 with respect to the wire 4, said driving shaft
15 is oriented in the manner shown in the two Figures being considered here as a reference,
where it can be noticed that the axis "O" of said shaft is substantially orthogonal
(in the sense that it lies on an orthogonal plane) to said two driving axles 11 and
12 and, in particular, it is parallel to the feed-forward direction of the metal wire
4.
[0018] In view of ensuring a most perfect functionality, i.e. ability to perform its duty,
of the rotary coupling of said motion transmission members 13, 14 with said driving
shaft 15, all of which having axes of rotation that are orthogonal with respect to
each other, said rotary coupling may be advantageously implemented by means of inclined-teeth
gears, in particular by means of cylindrical helical gears. Since such devices are
well-known in the art, they shall not be described here any further for the sake of
brevity.
[0019] As compared with the usual prior-art configuration, according to which said driving
shaft 15 was held parallel to said two driving axles 11 and 12, it can be readily
appreciated that the configuration according to the present invention - all other
conditions being equal - enables a wire forward-feeding and coiling unit 1 to be provided,
which has a remarkably lower moment of inertia with respect to the axis of rotation
(axis of the wire 4), owing to said drive shaft 15 not being oriented orthogonally
to the wire, but rather parallel to the latter.
[0020] The above described solution, anyway, still allows for a number of advantageous improvements.
A first one of such improvements, which is illustrated symbolically in Figure 3 itself,
provides for both driving axles 11, 12 of a same pair of rollers to be coupled to
a same drive shaft, in which an additional gear is used to transmit motion in a synchronous
manner.
[0021] As a further improvement, said motion transmission members 13, 14 may also feature
following characteristics, i.e.:
- they are mutually aligned, in the sense that they are at the same distance from the
wire 4, and further
- they are spaced from each other by an appropriate separating gap adapted to accommodate
said shaft 15.
[0022] It can actually be readily appreciated that, in this manner, such a further improvement
enables both the size, and the resulting space requirements, and the weight of the
shaft itself to be further reduced, with the result that the advantageous effects
that can be attained with the invention can be additionally boosted.
[0023] A further improvement that stands as matter of course lies in the fact that, if there
are provided various pairs 18, 19, ... of feed-forward rollers, all of them having
their respective driving axles 18A, 18B, 19A, 19B, ..., as well as their respective
motion transmission members, all such devices and members will then be sized and arranged
in such a manner as to be able to be rotatably driven by a single drive shaft 15,
as this is clearly illustrated in the same Figure 3 in a manner that anyone skilled
in the art is fully capable of readily understanding and implementing.
[0024] As far as the transmission of the motion to such a drive shaft 15 is concerned, a
fact that should be taken into due consideration in the first place is that this shaft
must of course rotate about its own axis, along an axis extending parallel to the
feed-forward direction of the wire. However, owing to the same shaft being an integral
part of the rotary wire forward-feeding and coiling unit, it must at the same time
rotate about the wire itself, and shall of course do this jointly with the rotary
motion of said wire forward-feeding and coiling unit 2.
[0025] To this purpose, and with reference to Figures 3 and 4, the unit itself is provided
with a rotating plate 21, on a face of which said wire forward-feeding and coiling
unit is fitted rotatably, and in which there is provided a suitable through-hole 22;
said drive shaft 15, upon jutting out of said wire forward-feeding and coiling unit,
is inserted rotatably in said through-hole 22 so as to come out on the other side
of it.
[0026] On to the portion of said shaft protruding from said plate on said other side thereof
there is attached, by shrink-fitting or other similar technique, a driving gearwheel
23, which is coupled peripherally with an appropriate centering gearwheel 24, the
axis of which is coincident with the axis of rotation "R" of said rotating plate 21;
said two wheels, i.e. the driving wheel and the centering one, may be co-planar and
have parallel axes, so that the mutual coupling thereof can be brought about with
the aid of simple straight-toothed gears.
[0027] Said centering gearwheel is firmly joined to and coaxial with a pulley 25, on which
there is fitted a driving belt 26 that is driven by other members of the machine with
the aid of means that are commonly known in the art.
[0028] Furthermore, this centering gearwheel, jointly with the pulley, is able to rotate
freely relative to said rotating plate 21, although they are co-axial.
[0029] Those skilled in the art should at this point be fully capable of understanding the
way in which the above-mentioned arrangements actually work: in fact, said drive shaft
15, which carries said wire forward-feeding and coiling unit 2, is caused to rotate
owing to the effect of its eccentric position in relation to said rotating plate 21,
whereby the rotation of the wire forward-feeding and coiling unit 2 about the wire
4 is ensured. At the same time, however, the rotation of this shaft 15, and therefore
the rotation of said rollers 3 and 3A, is ensured regardless of the position in which
the shaft may also be (and, therefore, even during motion), owing to the fact that
the driving gearwheel 23 connected thereto is constantly engaged with the corresponding
centering gearwheel 24, which in turn is driven by the pulley and the associated driving
belt; and, since these mechanical relations are constantly established, the desired
effect of a double continuous motion of the pairs of feed-forward rollers is attained.
[0030] Moreover, this solution has a quite important advantage in that the two motions can
be imparted at rotating speeds that are fully independent of, i.e. fully unrelated
with each other, thereby dramatically improving the application scope and the flexibility
of the above described machine.
[0031] However, a machine that is made as illustrated above may still have a drawback in
that, owing to said wire forward-feeding and coiling unit 2 being arranged in a half-space
lying on a single side with respect to the plane that passes through the metal wire
and extends orthogonally to said pairs of rollers, as this is best illustrated both
in Figure 1 and in Figure 2, it ensues a condition of total unbalance with respect
to the wire itself due to the effect of the rotation of said rotating plate 21, thereby
giving rise to continuous vibrations being generated, with a resulting greater extent
of weardown of the related support members and, in general, an easily understandable
higher degree of criticalness not only in the design, but also in the construction
and the use of the machine.
[0032] In view of doing away with or at least minimizing such a drawback, following improvement
is advantageously implemented: with reference to Figures 5 and 6, the plurality of
pairs of feed-forward rollers 3, 3A, ... etc. is subdivided into two distinct assemblies
and the pairs of rollers of a same assembly are associated to a same wire forward-feeding
and coiling unit 30 having the characteristics as described above: Similarly, the
same occurs with the pairs of rollers of the other assembly, forming the wire forward-feeding
and coiling unit 31.
[0033] Two distinct wire forward-feeding and coiling units are in this way provided, which
are arranged and applied in a sequence, but preferably contiguously, so that a general
point of the wire will first pass through one of said units and then through the second
one.
[0034] In addition, said units are mutually oriented so as to be arranged exactly in opposition
with respect to the wire, as this can be clearly inferred from the illustration appearing
in Figure 6, in which said units are sighted from a distance along the axis of the
wire 4. In this manner, the centre of gravity of the totality of said wire forward-feeding
and coiling units is shifted sensibly towards the wire itself, thereby markedly reducing
the unbalance and the vibrations induced by it, under beneficial effects on the operation
of the entire machine, although the moment of inertia is not modified to any sensible
extent.
[0035] This improvement may be embodied in various, differently organized and more articulate
manners. For instance, the pairs of feed-forward rollers may be subdivided in more
than simply two sub-assemblies 33, 34, 35, each one of which then constitutes a distinct
wire forward-feeding and coiling unit.
[0036] In an advantageous manner, these distinct wire forward-feeding and coiling units
may be provided in a radial arrangement, as spaced from each other by an equal angle
"s", as this is illustrated symbolically in Figure 7 representing the same view as
the one of Figure 6, however with reference to the case in which there are three of
said distinct and successive wire forward-feeding and coiling units.
[0037] As a matter of fact, the subdivision of the pairs of feed-forward rollers into a
larger number of wire forward-feeding and coiling units allows for their unbalance,
as taken individually, to be more effectively brought into equipoise; it further makes
it possible for the overall moment of inertia to be reduced.
[0038] The drive and rotation devices and parts of each one of said several wire forward-feeding
and coiling units so provided are the same as the ones used in the afore-described
case in which use is made of just a single one of such units. Therefore, their implementation
and adaptation may well be considered as being fully within the capabilities of those
skilled in the art, so that they shall not be described here any further.
[0039] Anyway, a machine that is made as illustrated above offers the possibility for further
advantageous improvements to be implemented. In fact, and again with reference to
Figure 1, it should be noticed that wire forming is performed by a plurality of forming
heads that are arranged in a various manner, but preferably according to a radial
pattern, on respective variously combinable plates 40 that are provided downstream
of said wire forward-feeding and coiling units.
[0040] Each such forming head is largely known to be designed in view of performing a specific
task, so that, when complex forming operations are to be carried out, the need generally
arises for several forming heads to be used.
[0041] Now, such a need involves an undesired increase in the number of forming heads to
be used, and this in turn leads to an increased complexity from a construction point
of view, as well as a resulting increase in overall costs.
[0042] In view of doing away with, or at least reducing the extent of such a drawback, a
kind of multipurpose forming head is disclosed and proposed here, which is able to
perform at least two types of forming operations having different characteristics.
[0043] It is a largely known fact that a forming process generally requires the use of a
tool that is capable of deforming the metal wire at a predetermined angle under utilization
of opposition or contrasting means having definite characteristics; a process involving
several forming operations will therefore require the use of tools with contrasting
means that are suitable to ensure deformation of the wire at respectively different
angles.
[0044] With reference to Figures 8 and 9, a forming unit is therefore illustrated, which
comprises a bending head 100 that is provided with contrasting means on a side thereof,
and with a moving bending tool 103 provided with a respective working stud 104 on
the other side thereof, in which said tool is capable of moving relative to said bending
head 100. Said contrasting or opposition means are comprised of a first opposition
stud 105 that is applied in a firmly joined manner on to said bending head, and a
second opposition stud 106 that is applied in a firmly joined manner on to said first
stud 105, as this is best illustrated in the above-cited Figures.
[0045] The outer surfaces of said first and second studs have different radiuses of curvature,
so as to be able to bring about differing bending extents.
[0046] The selection of the stud to be used for bending is determined by the positioning
of the wire 4 relative to such studs and, namely, by the height or distance of said
wire in relation to the head 100, in such a manner that the rotary motion of the working
stud 104 will push the wire 4 exactly against that contrasting or opposition stud,
the radius of curvature of which is to be used to the actually intended purpose, while
at the same time preventing said wire 4 from possibly engaging against studs that
are not desired or required.
[0047] The actual operation of the above-illustrated arrangement is as follows: according
to the kind or extent of deformation to be imparted to the wire, and therefore the
tool to be used, the wire is lifted, using generally known means (not shown), from
the shown side of the bending head in such a manner as to enable it to be set either
aligned with said first contrasting stud 105, as this is illustrated symbolically
in Figure 10, or aligned with said second contrasting stud 106, as this is illustrated
symbolically in Figure 11, these Figures being both an elevational plan view of the
bending head as seen from a distance along the axis of the wire.
[0048] Depending on the selected set-up, i.e. alignment of the wire, the latter is intercepted
by the working stud 104 and then bent by the motion performed by the latter in relation
to one of the two contrasting or opposition studs 105 and 106; depending on which
one of said contrasting or opposition studs is engaged, the wire itself is deformed
according to the related outer geometrical characteristics thereof. As a result, the
need only arises for the characteristics of said contrasting or opposition studs to
be defined and the suitable alignment to be selected accordingly in order to ultimately
obtain the desired bending or deformation curvature of the wire.
[0049] A further improvement of the above-described machine can be obtained, as best illustrated
in Figures 12 and 13, if said bending head is provided on said side thereof with an
open groove 107 for the wire 4 to be able to slide therethrough before eventually
coming out of the body of said bending head through an appropriate aperture 112. In
a corresponding manner, said moving bending tool 103 is provided along its side border
109 with a cutting edge 110. The configuration of the above-described devices and
arrangements is such that, owing to the motion of said moving tool 103, said cutting
edge 110 moves along to pass by said aperture 112 from which said metal wire is coming
out, so that the wire itself, being in this manner subject to a shearing stress between
said cutting edge 110 and the opposite resisting wall of said aperture 112, is of
course severed.
1. Machine for forming metal wire comprising:
- a wire forward-feeding and coiling unit (2),
- a rotating plate (21) adapted to rotatably drive said wire forward-feeding and coiling
unit (2),
- a plurality of forming plates (40) arranged downstream of said wire forward-feeding
and coiling unit (2) and adapted to support a respective plurality of forming heads
(100),
in which said wire forward-feeding and coiling unit is provided with a plurality
of pairs of mutually opposing feed-forward rollers (3, 3A, 18, 19) revolving about
respective parallel driving axles (11, 12; 18A, 18B; 19A, 19B), as driven by an assembly
of kinematical mechanisms,
characterized in that:
- said assembly of kinematical mechanisms comprises rotary motion-transmission means
(13, 14), each one of which is associated to a respective one of said parallel driving
axles (11, 12),
- there is provided a rotary drive shaft (15) adapted to transmit the rotary motion
thereof to said rotary motion-transmission means (13, 14) via appropriate couplings,
- and said drive shaft revolves about its own axis of rotation, which is orthogonal
to the plane defined by the axes of rotation of said parallel driving axles (11, 12).
2. Wire forming machine according to claim 1, characterized in that a plurality of pairs of feed-forward rollers have respective axes that are parallel
to each other so as to define respective planes; in that said planes are parallel to each other; and in that said drive shaft (15) is orthogonal to said parallel planes and coupled to the parallel
driving axles (11, 12; 18A, 18B; 19A, 19B) of respective feed-forward rollers (3,
3A, 18, 19).
3. Wire forming machine according to claim 1 or 2, characterized in that said parallel driving axles ( 11, 12; 18A, 18B; 19A, 19B) of a same pair of rollers
are spaced from each other by a separation gap within which there is arranged said
drive shaft.
4. Wire forming machine according to any of the preceding claims, characterized in that said couplings between said rotary motion-transmission means ( 13, 14) and said drive
shaft ( 15) are of the inclined-teeth gear type, preferably cylindrical helical gears.
5. Wire forming machine according to any of the preceding claims,
characterized in that:
- in said rotating plate (21) there is provided a suitable boring, preferably a through-hole
(22),
- said drive shaft ( 15) juts out of said wire forward-feeding and coiling unit and
is inserted rotatably in said through-hole (22) provided in said rotating plate (21),
- on to the portion of said shaft protruding from said plate there is attached, by
shrink-fitting or other similar technique, a driving gearwheel (23), which is coupled
peripherally with an appropriate centering gearwheel (24), the axis of which is coincident
with the axis of rotation "R" of said rotating plate,
- said centering gearwheel is firmly joined to a co-axial circular member for the
transmission of motion.
6. Wire forming machine according to claim 5, characterized in that said circular motion-transmission member is a pulley (25) adapted to engage an appropriate
drive belt (26).
7. Wire forming machine according to any of the preceding claims,
characterized in that:
- there is provided a plurality of pairs of said wire feed-forward rollers,
- said plurality of said pairs of rollers is subdivided into two distinct sub-assemblies
(30, 31) arranged in successive positions with respect to the feed-forward motion
of the wire, so that a general point of the wire will first pass through one of said
sub-assemblies and then through the second one,
- and said two sub-assemblies are oriented in a mutually opposing manner.
8. Wire forming machine according to any of the preceding claims 1 to 6,
characterized in that:
- there is provided a plurality of pairs of said wire feed-forward rollers,
- said plurality of said pairs of rollers is subdivided into at least three distinct
sub-assemblies (33, 34, 35) arranged in successive positions with respect to the feed-forward
motion of the wire, so that a general point of the wire will first pass through one
of said sub-assemblies and then successively through the other ones,
- and said at least three distinct sub-assemblies are arranged in a radial arrangement
in relation to each other and are preferably so distributed as to feature an equal
angular distance between successive sub-assemblies.
9. Wire forming machine according to the preamble of claim 1,
characterized in that said wire end-product forming unit comprises:
- a bending head (100) provided with at least a contrasting or opposition means on
a side (101) thereof,
- a moving bending tool (103) provided with a respective working stud (104), said
tool being capable of moving relative to said bending head (100),
in which said contrasting or opposition means is comprised of a first opposing stud
(105) that is applied in a firmly joined manner on to said bending head, and a second
opposing stud (106) that is applied in a firmly joined manner on to said first stud
(105).
10. Wire forming machine according to claim 9, characterized in that said first opposing stud (105) and said second opposing stud (106) have outer surfaces
featuring different radiuses of curvature at least in the zone at which they come
into contact with said metal wire (4).
11. Wire forming machine according to the preamble of claim 8,
characterized in that said wire end-product forming unit comprises:
- a bending head (100) provided on a side thereof with at least a contrasting or opposition
means,
- a moving bending tool (103) provided with a respective working stud (104), said
tool being capable of moving relative to said bending head (100),
in which said bending head is provided on said side thereof with at least an open
groove (107) which is adapted to accommodate said metal wire sliding therethrough,
and which debouches on the other side of said bending head through an appropriate
aperture ( 112),
and in which said moving bending tool (103) is provided on a side border (109) thereof
with a cutting edge (110) adapted to be caused to pass by said aperture (112).