FIELD OF THE INVENTION

The invention relates to the technical sector of sewing machines, in particular those which realise knotted sewing stitches, or stitches of the “chained stitch” type, used for sewing footwear, leather articles, articles of natural and/or synthetic fabrics and the like.

DESCRIPTION OF THE PRIOR ART

Among the machines of the above type are those comprising a turret, borne in a cantilever fashion by the base of the machine, from the free end of which at least a needle projects vertically downwards, which draws a first sewing yarn; the needle cooperates with a rotary hook device, also known as a crotchet hook, which draws a second sewing yarn originating from a yarn bobbin associated to the crotchet hook.

The alternating vertical movement of the needle is actuated in phase relation with the rotation of the rotary hook in such a way as to realise, as known, with the first and second sewing yarn, the knotted sewing stitches.

The rotary hook, and associated yarn bobbin, are situated internally of a crotchet hook unit, substantially in the form of a bushing open in an upwards direction to allow entry of the needle therein; the bushing is borne by a pin rotatably supported by the end of a profiled arm (8) (for example “V”, “C”, “L”,“U” shaped) which can oscillate, with a prefixed angular amplitude, with respect to the base of the machine.

The axis of oscillation of the arm is coaxial to the axis of the bushing.

Document EP 0397617 describes a kinematism, inserted in the arm, connected at a side of the axis of oscillation of the arm and at the other side to the pin bearing the bushing.

The kinematism is such that the oscillation of the arm in one direction leads to the oscillation in the opposite direction of the bushing; the amplitudes of the oscillations are identical, so that the bushing maintains its spatial positioning independently of the position assumed by the oscillating arm. The oscillating arm bears the means for the rotation of the rotary hook with respect to a coaxial axis with the axis of the bushing.

During the sewing the profiled arm is made to oscillate by the operator, manually or by motorised means, into positions that do not interfere with the article in the actual sewing situation of the moment.

The drive shaft of the machine activates both the alternating vertical movement of the needle and, in phase, the rotation of the rotary hook; this phase is in no way altered by the oscillation of the profiled arm.

The above-mentioned machine has two end configurations defined by the maximum oscillation in one direction, and then the other, of the profiled arm; between the end positions, a plurality of positionings of the profiled arm are defined, which facilitates the operator when performing the sewing.

This constitutes a limitation for sewing special articles which have dimensions that are such as to interfere with the profiled arm, for example tubular-shaped articles which extend in consecutive non-coaxial parts and are such as to exceed the extension of the terminal portion of the arm, i.e. the portion supporting the bushing.

Document WO 03/052192 considers a machine with a base that can form a column to which a head is constrained comprising the means for activating a sewing needle facing downwards. The base supports a curved oscillating arm with respect to an inclined axis, to the upper end of which a crotchet unit is constrained the orientation of which remains unaltered independently of the position of the arm. The crotchet hook cooperates with the needle for formation of the sewing stitches.

Document US 7,363,869 describes a sewing machine comprising a base that bears a column which supports, in a cantilever fashion, a head comprising means for activating a needle facing downwards. The base supports a curved arm made movable, in both directions, according to an inclined axis; the upper end of the arm, coaxial with respect to the axis, bears the means that cooperate with the needle for the formation of the sewing stitches. Publication EP 0409801 describes a machine comprising a frame, of which an end is hinged to the frame of the machine according to a transversal axis. The lower end of a curved arm is hinged according to an axis perpendicular to the frame, the upper end of which arm bears a plate that is coaxial with the axis of oscillation of the curved arm; the plate is destined to be inserted internally of an article of footwear during the sewing performed on the article.

SUMMARY OF THE INVENTION

The invention has the aim of providing a machine for sewing articles which beyond the technical-functional aspects of the machine of the prior art, described in the foregoing, enables realising a plurality of further spatial positionings of the profiled arm.

A further aim of the invention is to realise a machine which, for the operator, does not present difficulties for use thereof.

A still further aim of the invention is to provide a machine such as to create seams including in articles having complex shapes.

A still further aim of the invention consists in providing a machine, which in respect of the aims listed above, is such as to make seams with a knotted needle or seams of the chained type.

The above-mentioned advantages are obtained according to the specified contents of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics of the invention will emerge from the following description of an embodiment of a sewing machine for sewing articles, with particular reference to the accompanying tables of drawings, in which: figures 1 and 2 illustrate two perspective views of the machine in two different end spatial positionings obtained with the technical solution of the present invention; figure 2A illustrates a further perspective representation of the machine, considered from the opposite side with respect to the views of figures 1, 2; Figure 3 illustrates, in a perspective view, some technical-functional aspects of the machine;

Figure 4 illustrates, in a perspective view, and in larger scale with respect to figures 1 and 2, detail A of figure 1 , with some parts removed to better evidence others;

Figure 5 illustrates a lateral view of the machine, sectioned according to a vertical plane, in a first spatial end position;

Figure 6 illustrates a lateral view of the machine, sectioned according to a vertical plane, in a second spatial end position;

- Figure. 7 illustrates, in a perspective view and in larger scale, detail J of figure 2A, to highlight further technical-functional aspects relative to the activations of some operating parts of the machine;

Figure. 8A illustrates, in larger scale, detail B of figure 5, with some parts omitted to better evidence functional aspects of the machine;

- Figure 8B illustrates the view, in the direction of arrow R, of what is illustrated in figure 8A;

Figure. 8C illustrates, in larger scale, detail E of figure 6, with some parts omitted to better evidence technical-functional aspects of the machine;

- Figure 9 is a graphic schematic representation of one of the functional aspects characterising the machine;

- Figure 10 illustrates a schematic lateral view of the machine with a first variant concerning the embodiment of the bushing;

- Figure. 10A illustrates detail F1 of figure 10 in larger scale;

- Figure 10B illustrates, in a schematic perspective view, the components which define the first variant;

- Figure 11 illustrates a schematic lateral view of the machine with a second variant concerning the embodiment of the bushing;

- Figure. 11 A illustrates detail F2 of figure 11 in larger scale; - Figure 11 B illustrates, in a schematic perspective view, the components which define the second variant;

- Figure 12 illustrates a schematic lateral view of the machine with a third variant concerning the embodiment of the bushing;

- Figure. 12A illustrates detail F3 of figure 12 in larger scale;

- Figure 12B illustrates, in a schematic perspective view, the components which define the third variant.

DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to the figures, reference numeral (1) denotes, in its entirety, the machine object of the invention the supporting structure of which comprises a base (2) which supports, in a cantilever fashion, a turret (3).

The free end (3A) of the turret bears: a needle (4) facing downwards, which draws (in known ways) a first sewing yarn (5); a leather presser foot (6), located by a side of the needle; a feed foot (7) which, as is known, cooperates with the needle for the displacement of the article following the realisation of a single sewing stitch (see figures 4, 8B).

The movement of the needle (4) is actuated by first activating means, arranged in the turret, not illustrated as known to the technical expert in the sector; also the movement members of the feet (6, 7), acting in phase relation with the movement of the needle, are not illustrated, as they are known in the art.

Reference numeral (8) denotes a profiled arm of which an end (9) is supported by a unit (10) borne, as will be evidenced in the following, by the base (2); the other end of the arm rotatably supports a bushing (11), located beneath the needle (4) and open towards the needle.

The axis of oscillation (X1) of the arm (8) is coaxial to the axis of oscillation of the bushing (11).

This oscillation (directions (Zi, Z ₂ figure 7), is actuated in the illustrated case by a motor unit (40) which, via a cogwheel (41) enmeshing with a cogged sector (42), imposes the above-mentioned oscillations.

Stabilising means (12) are associated to the arm (8) (Fig.5, 6), which stabilising means are realised according to the solution of EP0397617 cited in the preamble; in this way the oscillation in one direction of the arm (8) leads to an oscillation in the opposite direction, and of equal amplitude, of the bushing (11).

A rotary hook (13) is located internally of the bushing (11), which is drawn in rotation, in known ways, by second activating means (14) (figures 5 and 6) internal of the arm (8).

In the embodiment illustrated in the figures, the rotary hook (13) draws a second sewing yarn (15), originating from a yarn bobbin (16) internal of the bushing (figure 4).

If follows that, as is known, as the second activating means (14) are activated in phase relation with the activation of the first activating means, the cooperation between the needle (4), with the relative sewing yarn (5), and the rotary hook (13), with the relative sewing yarn (15), leads, as is known, to the formation of knotted sewing stitches.

It is also possible to realise stitches known as chained stitches; in this case the second sewing yarn is not included, as only the first sewing yarn (5), drawn by the needle (4) is used, as is known, in cooperation with the rotary hook (13).

The connection between the unit (10) and the base (2) is obtained by means of two curved supports (20) (figures 1 , 2), (20A) (figure 2A), both fixed to the base, in which corresponding grooved tracks (21) are realised (figures 1 , 2), (21A) (figures 2A, 7).

The tracks extend according to relative arcs of circumference (35, 35A), having a radius that is identical with respect to a common axis (C) (figures 8A, 8B, 8C), the concavities of which are facing towards the bushing (11).

The arcs of circumference extend in relative planes parallel to one another, as well as parallel to the axis (X1). Rollers (22) run in the grooved tracks, rotatably supported by relative sectors (23) (figures 1, 2), (23A) (figures 2A, 7) by screw means (24); both sectors are solidly constrained to the unit (10).

One of the sectors, specifically the one denoted with reference (23A) (figure 7) has a cogging (25) extending according to an arc of circumference coaxial to the adjacent track (21 A) (figure 7).

A cogwheel (not visible in the figure) enmeshes with the cogging (not visible in the figure) which cogwheel is drawn in both directions by a motor unit (27); in this way it is possible to oscillate both sectors (23, 23A) (as they are solidly connected to the unit (10), in opposite directions (Y1, Y2) (figure 7) to define, for the unit, two spatial end positions (P1) (fig. 5), (P2) (fig. 6).

Figure 9 schematically illustrates the arcs of circumference (35, 35A) as coincident, as: they extend in relative planes parallel to one another, as well as parallel to the axis (X1); they have an identical radius and a common axis (C).

Figure 9 also partially indicates a diameter of the arcs of circumference, in particular that of the median (X2) of the cogged sector (23) (figure 2); also indicated, (G1, G2) are the positions assumed by the diameter (X2) in the above-mentioned positions (P1, P2) of the unit (10).

The oscillation of the sectors (23, 23A) with respect to the axis (C) sets the unit (10) in oscillation with respect to the axis; it follows that the components borne by the unit, as well as the unit itself, describe arcs of circumference, centred on the axis (C), the amplitude of which is a function of the distance thereof from the axis (C).

With the unit (10) in the first end position (P1), the bushing (11) is positioned as in figure 8A: the diameter (X2) is in the centred position (K1).

Owing to the rotation of the unit (10) with respect to the axis (C), the bushing assumes two end orientations of which (K2) corresponding to the position (P2) is indicated in figure 8C: the angular displacement “a” with respect to the centred position (K1) can clearly be seen. With reference to the unit (10), what is located at axis C is not subject to any oscillation; further, the means that cyclically intercept the axis C maintain the orientation thereof in any interception.

It is known that the sharp operating end (53) of the rotary hook (13) cooperates with the needle (4) for the formation of the sewing stitch, when the end reaches the topmost point (T) during the rotation of the rotary hook (13) (figure 8B).

In the technical solution provided, the unit (10) is conformed in such a way that the axis (C), with respect to which the unit is oscillating, is positioned at the level defined by point T.

If follows that at each cycle of the sewing, the needle and the end (53) of the rotary hook are in the same position and with mutual unaltered orientations.

Definitively, the conformation of the means that enable connecting the unit (10) to the base (2), must be such as to cause the unit (10) to oscillate with respect to an axis (C) defined as illustrated above.

It is known that the part of the article subject to sewing must be supported by a horizontal sewing abutment which must further have an opening for passage of the needle; this makes possible the functions of the needle (4) and of the associated leather presser feet (6) and feed feet (7).

As illustrated in figures 6 and 8C, the oscillations of the sectors (23, 23A) with respect to the axis (C), lead to a consequent rotation of the bushing.

To realise a horizontal sewing abutment, in the opening (11 A) made in the bushing and facing upwards (figure 4), a plate (60) is located, rotatably supported by two pins (61) hinged to the edges of the opening, coaxial to one another according to an axis (X3) perpendicular to the oscillation plane of sectors (23, 23A); the plate has a slot (62), for the transit of the needle (4), extending parallel to the axis (X3) (figure 4).

When using the machine, the operator places the article to be sewn on the plate (60) and if the plate, owing to the positioning of the unit (10), is not horizontal the operator makes it horizontal thereto, facilitated by the fact that the plate itself can oscillate (axis X3) with respect to the relative pins (61).

Having carried out the positioning, the sewing begins with the activation of the leather presser foot (6) which by pressing the article, and thus the underlying plate, with a force directed from above downwards, combines to stabilise the horizontal position of the plate.

When the leather presser foot lifts, the article to be sewn is subjected to the combined action of the needle (4) and the feed foot (7) which combine to maintain the plate (60) horizontal; on termination of the transport of the article (performed by the needle (4) - foot (7) assembly), the leather presser foot (6) newly intervenes to stabilise the horizontal position of the plate: and so on up to completion of the sewing independently of the position of the unit (10).

According to a first variant of the conformation of the bushing (110) (figures 10, 10A, 10B), in the opening (111) thereof, facing upwards, a plate (112) is located, superiorly in a sort of ring (113) (or first ring), which is removably couplable, by known systems, to a lateral wall of the bushing; a tab (114) protrudes from the plate, designed to cover, in combination with the plate (112), the opening (111); the plate (112) has a slot (115) through which the needle (4) freely transits.

The plate (112), with the unit (10) in a first operating position (D1) (for example coinciding with position (P1), figure 5), is positioned horizontally: position (M1) (figure 10); this is extremely advantageous since during the sewing, the portion of the articles to be sewn is positioned on a horizontal work plane defined by the plate.

Any eventual angled displacements, +pi, - pi of position M1 (for example ±5 degrees) do not alter either the functioning of the needle (4) or the parameters of the sewing, for example the frequency of the sewing stitches carried out, quality of the stitches themselves, etc.

The unit (10) describes an arc, with axis (C), that is greater than the sum of angles pi+ p2.

It follows that to achieve the advantages of the first variant, it is necessary to include further variants of the conformation of the bushing of the type described above.

For example figures 11, 11 A, 11 B illustrate a second variant, comprising a second ring (123) removably couplable, by known systems, to the above- mentioned wall of the bushing (110).

In this case too the ring comprises a plate (122), with a relative tab (124), having a slot (125) for the transit of the needle (4).

With the unit (10) in a second position (D2) (figure 11, intermediate between the positions (P1 , P2)) the plate (122) is positioned horizontally, with the advantages that brings for the sewing: position (M2) (for example +10 degrees with respect to position M1).

In this case too any eventual angular displacements +P2, -p2 (from position (M2)), for example ±5 degrees, do not alter either the functioning of the needle (4) or the parameters of the sewing.

The first and second variant have overall angular variations of the axis X2 of at least 20 degrees (see figures 5 and 6).

To broaden the operational sector, at least a third variant of the bushing (110) is included.

In fact, a third ring (133) is included (figures 12, 12A, 12B) comprising a plate (132), with a relative tab (134), having a slot (135).

With the unit (10) in a first operating position (D3) (for example coinciding with the position (P2), figure 6) the plate (132) is positioned horizontally: position (M3), for example +10 degrees (with respect to position (M2), 20 degrees with respect to position (M1).

In this case too any eventual angular displacements + p3, - p3 (from position (M3)), for example ±5 degrees, do not alter the parameters of the sewing.

The cited variants, first, second and third variants overall display angular variations of at least 30 degrees of the axis (X2).

Definitively, by including, for example, three rings (113, 123, 133), conformed as above, the operator works practically on a horizontal support (or almost horizontal support) defined respectively by the plates (112, 122, 132) with all the advantages that brings.

Definitively, a plurality of spatial positions from among the cited end positions (P1) can be imposed on the unit (10) (figure 5) and (P2) (figure 6); in each of the spatial positions the profiled arm (8), as a consequence of its oscillation with respect to the relativ axis (X1), can be set in another series of positions.

In each of the spatial positions the position of the end (53) of the rotary hook (13) is defined (axis C), by the topmost point (T) thereof in which the first sewing yarn cooperates for the formation of the sewing stitch which will be of the “knotted stitch” type if the end of the hook draws the second sewing yarn, or of the “chained stitch” type in a case where the second sewing yarn is not included.

As specified the optimal solution is to realise the connecting means of the unit (10) at the base and the guide means to the oscillation of the unit which are conformed so as to define the axis (C) of the oscillation at the topmost point (T) affected by the end (53) of the rotary hook during the course of the rotation thereof; any displacements from the axis (C) from the topmost point assumed by the end (53) following the rotation of the rotary hook with respect to the optimal solution, are allowed as long as the end of the rotary hook inserts in the loop (90) which is created in the first sewing yarn (5) following the raising of the needle (4).

The loop defines an operating area (S) which is always created in the same position as it is not influenced by the oscillation of the unit (10); an alternative might exist to what has been considered and that is that the axis (C) can be provided transiting internally of the operating area.

As already specified in the various positions imposed on the unit (10), a horizontal abutment is defined, by means of the plate (60), for the article to be sewn.

In an embodiment, the axis (X3) of oscillation of the plate (60) coincides with the axis (C). In a variant the sewing machine for sewing articles comprises: the turret (3), supported in a cantilever fashion by the base (2), the free end (3a) of which turret (3) bears the sewing needle (4), facing downwards, which draws the first sewing yarn (5), and the leather presser feet (6) and the feed feet (7); the first activating means, arranged in the turret (3), for the movement of the needle; an arm of which an end is fixed rigidly to the unit (10) borne by the base and the other end rotatably supports the bushing (11).

Definitively, the arm is fixed with respect to the unit (10).

The machine further includes the rotary hook (13), located in the bushing (11), and the second activating means acting in phase with the first activating means, to draw the rotary hook in rotation for the formation, internally of the bushing and in cooperation with the needle, of a sewing stitch.

In this case too it is possible to realise a knotted sewing stitch, or a chained sewing stitch.

In the first case (knotted stitch) the rotary hook (13) draws a second sewing yarn (15) originating from a yarn bobbin (16) situated in the bushing (11); in the second case (chained sewing stitch), only the first sewing yarn (5) is used, drawn by the needle (4).

The connection between the unit (10) and the base (2) is obtained with the technical-functional specifications considered in the foregoing, which enable setting the unit (10) in oscillation, as well as the components borne thereby with respect to the axis (C).

Definitively, the cited variant provides a unit (10) which fixedly supports the arm bearing the bushing; a plurality of spatial positions is imposed on the unit (10), oscillating with respect to the axis (C) between the end positions (P1, P2).

The proposed variant further comprises the plate (60), to define, in any spatial configuration of the unit (10), a horizontal abutment for the articles being subjected to the sewing.