Sewing machine for sewing articles

Abstract

A sewing machine for sewing articles, comprising: a turntable (3) constrained to a base (2) carrying a sewing needle (4) facing downward with an associated sewing thread (5); first actuating means arranged in the turntable for movement of the needle; a forming arm (8) supported in an oscillating manner by a unit (10) carried by the base and rotatably supporting a bushing (11) located below and open towards the needle, the axis of the bushing being coaxial with the oscillating axis of the arm; stabilizing means (12) associated with a specified arm (8), the oscillation in one direction of which exerts on the bushing (11) an oscillation in the opposite direction and having an equal amplitude; the rotary hook (13) is positioned in the bushing (11); a second actuation means (14) acting in phase with the first actuation means to pull the swivel hook to rotate so as to form a sewing stitch in cooperation with the needle and the associated sewing thread (5) within the liner; means for connecting the unit (10) to the base (2) so as to enable the unit to oscillate according to a coaxial arc of a circumference, the axis (C) of which intersects the highest point (T) that the end (53) of the swivel hook (13) reaches during its rotation.

Description

Technical Field

[0001] The present invention relates to the technical field of sewing machines for sewing footwear, leather goods, goods of natural and / or synthetic fabrics and the like, in particular sewing machines for making knotted sewing stitches or stitches of the “chain stitch” type. Background Art

[0002] Among the machines of the above-mentioned type, some include a turntable carried in a cantilevered manner by the base of the machine, from the free end of which at least one needle projects vertically downwards, which needle pulls the first sewing thread; this needle cooperates with a rotating hook device (also called a crochet hook), which pulls the second sewing thread from a yarn bobbin connected to the crochet hook.

[0003] The alternating vertical movement of the needle is actuated in phase relation with the rotation of the swivel hook so that a knotted sewing stitch is achieved with the first sewing thread and the second sewing thread as is known per se.

[0004] The swivel hook and the associated yarn spool are located inside the crochet hook unit, essentially in the form of a bushing that opens in an upward direction to allow the needle to enter therein; the bushing is carried by a pin, which is rotatably carried by the end of a forming arm (8) (e.g. "V"-shaped, "C"-shaped, "L"-shaped, "U"-shaped), and the forming arm (8) can oscillate relative to the base of the machine with a predetermined angular amplitude.

[0005] The oscillation axis of the arm is coaxial with the axis of the bushing.

[0006] Document EP 0397617 describes a kinematic mechanism inserted into an arm, connected to the arm on one side of the axis of oscillation of the arm and to a pin supporting a bushing on the other side.

[0007] The kinematic mechanism is such that an oscillation of the arm in one direction causes an oscillation of the bushing in the opposite direction; the amplitude of the oscillations is the same, so that the bushing maintains its spatial positioning regardless of the position assumed by the oscillating arm.

[0008] The oscillating arm carries means for rotating the swivel hook about an axis coaxial with the axis of the bushing.

[0009] During the sewing process, the forming arm is oscillated manually by the operator or by motorized means into a position where it does not interfere with the article during the actual instant of sewing.

[0010] The drive shaft of the machine actuates the alternating vertical movement of the needle and the in-phase rotation of the rotary hook; this phase is in no way altered by the vibrations of the forming arms.

[0011] The above-mentioned machine has two end structures, which are defined by the maximum oscillation of the forming arm in one direction and then by the maximum oscillation of the forming arm in the other direction; between the end positions, multiple positioning of the forming arm is defined, which facilitates the operator to sew.

[0012] This constitutes a limitation for sewing special articles having dimensions interfering with the shaped arms, such as tubular articles extending in a continuous non-coaxial portion and beyond the terminal portion of the arm, ie the portion bearing the bushing.

[0013] Document WO 03 / 052192 considers a machine having a base which may form a column to which is constrained a head which comprises means for actuating a sewing needle facing downwards. The base supports an oscillating arm bent relative to an inclined axis, to the upper end of which a hook unit is constrained, the orientation remaining unchanged regardless of the position of the arm. The hook cooperates with the needle to form a sewing stitch.

[0014] Document US 7,363,869 describes a sewing machine comprising a base carrying a column supporting a head in cantilevered manner, the head comprising means for actuating a needle facing downwards. The base carries a curved arm movable in two directions according to an axis of inclination; the upper end of the arm, coaxial with respect to the axis, carries means cooperating with the needle for forming the sewing stitch.

[0015] Publication EP 0409801 describes a machine comprising a frame whose ends are articulated according to a transverse axis to the frame of the machine. The lower end of a curved arm is articulated according to an axis perpendicular to the frame, and the upper end of the curved arm carries a plate coaxial with the axis of oscillation of the curved arm; this plate is inserted inside the footwear during the sewing process. Summary of the invention

[0016] The object of the present invention is to provide a machine for sewing articles which, in addition to the technical functional aspects of the above-mentioned prior art machines, enables a plurality of further spatial positionings of the forming arms.

[0017] Another object of the invention is to realize a machine which does not present difficulties for the operator when using it.

[0018] Another object of the invention is to provide a machine for producing seams included in articles having complex shapes.

[0019] Still another object of the present invention is to provide a machine for forming seams with a knotted needle or chain stitch for the above purposes.

[0020] The above advantages can be achieved according to the specific contents of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features of the present invention will become apparent from the following description of an embodiment of a sewing machine for sewing articles, with particular reference to the accompanying drawings, in which:

[0022] —— Figure 1 and Figure 2 Two perspective views of the machine in two different end spatial orientations obtained using the technical solution of the present invention are shown;

[0023] —— Figure 2A Shows the relative Figure 1 , 2 another perspective representation of the machine considered from the opposite side of the view;

[0024] —— Figure 3 Some technical functional aspects of the machine are shown in perspective;

[0025] —— Figure 4 In perspective and relative to Figure 1 and Figure 2 Shown on a larger scale Figure 1 Detail A of which some parts are removed to better illustrate others;

[0026] —— Figure 5 shows a side view of the machine in a first spatial end position, sectioned according to a vertical plane;

[0027] —— Figure 6 shows a side view of the machine in a second spatial end position, sectioned according to a vertical plane;

[0028] —— Figure 7 Shown in perspective and on a larger scale Figure 2A Details J to highlight further technical functional aspects related to the actuation of some operating parts of the machine;

[0029] —— Fig. 8A Shown on a larger scale Figure 5 Detail B, with some parts omitted to better demonstrate the functional aspects of the machine;

[0030] —— Figure 8B Shows Fig. 8A A view in the direction of arrow R as shown in FIG.

[0031] —— Figure 8C Shown on a larger scale Figure 6 Detail E of the machine, in which some parts have been omitted in order to better demonstrate the technical functional aspects of the machine;

[0032] —— Fig. 9 is a schematic illustration characterizing one of the functional aspects of the machine;

[0033] —— Fig.10 shows a schematic side view of a machine with a first variant of embodiment with respect to the bushing;

[0034] —— Fig. 10A Shown on a larger scale Fig.10 Details of F1;

[0035] —— Fig. 10B The components defining the first variant are shown in a schematic perspective view;

[0036] —— Fig.11 shows a schematic side view of a machine with a second variant of embodiment with respect to the bushing;

[0037] —— Fig.11A Shown on a larger scale Fig.11 Details of F2;

[0038] —— Fig. 11B The components defining the second variant are shown in a schematic perspective view;

[0039] —— Fig.12 shows a schematic side view of a machine with a third variant of embodiment with respect to the bushing;

[0040] —— Fig. 12A Shown on a larger scale Fig.12 Details of F3;

[0041] —— Fig. 12B The components defining the third variant are shown in a schematic perspective view. DETAILED DESCRIPTION

[0042] With reference to the accompanying drawings, reference number (1) denotes as a whole a machine object according to the invention, the supporting structure of which comprises a base (2) supporting a turntable (3) in a cantilevered manner.

[0043] The free end (3A) of the turntable carries: a downwardly facing needle (4) which (in a known manner) pulls a first sewing thread (5); a leather presser foot (6) which is located on one side of the needle; a feed foot (7) which, as is known, cooperates with the needle for moving the article after a single sewing stitch has been made (see Figure 4 , 8B).

[0044] The movement of the needle (4) is actuated by a first actuating means arranged in a turntable, not shown as known to a person skilled in the art; moreover, the moving components of the feet (6, 7) acting in phase relationship with the movement of the needle are not shown as they are known in the art.

[0045] Reference numeral (8) denotes a shaped arm, the end (9) of which is supported by a unit (10) carried by the base (2), as will be demonstrated hereinafter; the other end of the arm rotatably supports a sleeve (11) which is located below the needle (4) and opens towards it.

[0046] The oscillation axis (X1) of the arm (8) is coaxial with the oscillation axis of the bushing (11).

[0047] This oscillation (direction ( Figure 7 In the illustrated case, Z1, Z2) are actuated by a motor unit (40) which imparts the above-mentioned oscillations via the meshing of a cogwheel (41) and a cogwheel segment (42).

[0048] A stabilizing device (12) is associated with the arm (8) ( Figure 5 , 6 ), which stabilizing device is implemented according to the solution of EP0397617 cited in the preamble; in this way, an oscillation of the arm (8) in one direction causes an oscillation of the bushing (11) with equal amplitude in the opposite direction.

[0049] The swivel hook (13) is located inside the bushing (11) and is actuated by a second actuating device (14) ( Figure 5 and Figure 6 ) is pulled into rotation in a known manner.

[0050] In the embodiment shown in the figure, the rotating hook (13) pulls the second sewing thread (15), which originates from the sleeve ( Figure 4 ) inside the yarn spool (16).

[0051] As is known, if the second actuating means (14) is actuated in phase with the actuation of the first actuating means, the cooperation between the needle (4) and the associated sewing thread (5) and the swivel hook (13) and the associated sewing thread (15) results in the formation of a knotted sewing stitch, as is known.

[0052] It is also possible to achieve a stitch known as a chain stitch; in this case, the second sewing thread is not involved, since only the first sewing thread (5) pulled by the needle (4) is used in cooperation with the swivel hook (13), as is known per se.

[0053] The connection between the unit (10) and the base (2) is through two curved supports (20) ( Figure 1 , 2 )(20A)( Figure 2A ) are realized, both supports are fixed to the base, wherein corresponding grooved tracks (21) ( Figure 1 , 2 )(21A)( Figure 2A , 7 ).

[0054] These tracks extend according to relative arcs of circles (35, 35A) having the same radius ( Fig. 8A , 8B , 8C), the depressions of these relative arcs face the bushing (11).

[0055] The arcs of the circumference extend in opposite planes parallel to each other and to the axis ( X1 ).

[0056] The roller (22) runs in a grooved track and is connected to the relevant sectors (23) ( Figure 1 , 2 )(23A)( Figure 2A , 7 ) is rotatably supported; both parts are firmly constrained on the unit (10).

[0057] One of these sectors, specifically the one indicated by reference numeral (23A) ( Figure 7 ) has a cog (25) which is arranged according to the adjacent track (21A) ( Figure 7 ) is an arc extending from the circumference of a coaxial circle.

[0058] A cogwheel (not visible in the figure) meshes with this cogwheel (not visible in the figure), which is pulled in two directions by the motor unit (27); in this way, it is possible to make the two sectors (23, 23A) (when they are firmly connected to the unit (10)) move in opposite directions (Y1, Y2) ( Figure 7 ) so as to define two spatial end positions (P1) ( Figure 5 )、(P2)( Figure 6 ).

[0059] exist Fig. 9 Schematically shown are arcs of coincident circles (35, 35A), such as: they extend in relative planes parallel to each other and to the axis (X1); they have the same radius and a common axis (C).

[0060] Fig. 9The diameter of the arc of the circumference is also partially indicated, in particular the cog sector (23) ( Figure 2 ) is the diameter of the median (X2); it is also noted that (G1, G2) is the position assumed by the diameter (X2) in the above-mentioned position (P1, P2) of the unit (10).

[0061] The oscillation of these sectors (23, 23A) relative to the axis (C) sets the unit (10) to oscillate relative to the axis; it follows that the components carried by the unit and the unit itself describe an arc of a circle centered on the axis (C), the amplitude of which is a function of its distance from the axis (C).

[0062] With the unit (10) in the first end position (P1), the bushing (11) is Fig. 8A The center is positioned such that the diameter (X2) is at the center position (K1).

[0063] Due to the rotation of the unit (10) relative to the axis (C), the bushing assumes two end orientations, the orientation (K2) corresponding to the position (P2) being Figure 8C : The angular displacement "α" relative to the center position (K1) can be clearly seen.

[0064] With reference to this unit (10), the position situated at the axis C does not undergo any oscillations; moreover, the components which cyclically intersect the axis C maintain their orientation in any intersection.

[0065] It is known that when the end reaches the highest point (T) during the rotation of the rotating hook (13), the sharp operating end (53) of the rotating hook (13) cooperates with the needle (4) to form a sewing stitch ( Figure 8B ).

[0066] In the proposed solution, the unit (10) is adapted in such a way that it is positioned at a level defined by the point T relative to its axis of oscillation (C).

[0067] As a result, after each sewing cycle, the ends (53) of the needle and the swivel hook are in the same position and have an unchanged orientation relative to each other.

[0068] In particular, the means capable of connecting the unit ( 10 ) to the base ( 2 ) must be configured so as to allow the unit ( 10 ) to oscillate relative to the axis (C) defined above.

[0069] It is known that the part of the article subjected to sewing must be supported by a horizontal sewing abutment which must further have an opening for the passage of the needle; this makes possible the function of the needle (4) and the associated leather presser foot (6) and feed foot (7).

[0070] like Figure 6 and 8C As shown, oscillation of the sectors (23, 23A) relative to the axis (C) results in consequent rotation of the bushing.

[0071] In order to achieve a horizontal sewing abutment, the upwardly facing opening (11A) formed in the sleeve ( Figure 4 ), a plate (60) is positioned, rotatably supported by two pins (61) hinged to the edge of the opening and coaxial with each other according to an axis (X3) perpendicular to the oscillation plane of the sectors (23, 23A); the plate has a slot (62) extending parallel to the axis (X3) for the passage of the needle (4) ( Figure 4 ).

[0072] When using the machine, the operator places the item to be sewn on the plate 60 and, if the plate is not level due to the positioning of the unit 10, he makes it level, which is facilitated by the fact that the plate itself can oscillate (axis X3) relative to the relative pins 61.

[0073] After positioning has been carried out, sewing begins with the activation of the leather presser foot (6) which acts to stabilize the horizontal position of the plate by pressing the article with a force downward from above and therefore the plate below.

[0074] When the leather presser foot is raised, the item to be sewn is acted upon by the combination of the needle (4) and the feed foot (7), which together keep the plate (60) horizontal; at the end of the transport of the item (performed by the needle (4)-foot (7) assembly), the leather presser foot (6) re-intervenes to stabilize the horizontal position of the plate: and so on, until sewing is completed, regardless of the position of the unit (10).

[0075] According to a first variant of the configuration of the bushing (110) Fig.10 , Fig. 10A , Fig. 10B ), in its upwardly facing opening (111), a plate (112) is located above a ring (113) (or first ring) which can be removably connected to the side wall of the bushing by a known system; a tab (114) protrudes from the plate and is designed to cover the opening (111) in combination with the plate (112); the plate (112) has a slot (115) through which the needle (4) freely passes.

[0076] When the unit (10) is in the first operating position (D1) (for example, coinciding with the position (P1), Figure 5 ), the plate (112) is positioned horizontally: position (M1) ( Fig.10); This is very advantageous because during the sewing process, the part of the item to be sewn lies on the horizontal working plane defined by the plate.

[0077] Any resulting angular displacement of the position M1, +β1, −β1 (eg ±5 degrees) does not change the functionality of the needle (4) or the sewing parameters, such as the frequency of the sewing stitches performed, the quality of the stitches themselves, etc.

[0078] The cell (10) describes an arc with an axis (C) which is greater than the sum of the angles β1+β2.

[0079] It follows that in order to realize the advantages of the first variant, further variants of the construction of bushings of the type described above must be included.

[0080] For example, Fig.11 , 11A 11B shows a second variant comprising a second ring ( 123 ) which can be detachably coupled to the above-mentioned wall of the bushing ( 110 ) by a known system.

[0081] In this case, the ring also comprises a plate (122) which, together with an associated tab (124), has a slot (125) for the passage of the needle (4).

[0082] When the unit (10) is in the second position (D2) ( Fig.11 , in the case of the position (halfway between the positions (P1, P2)), the plate (122) is positioned horizontally, with the following advantages for sewing: position (M2) (eg +10 degrees relative to position M1).

[0083] In this case, any resulting angular displacement (from position (M2)) of +β2, -β2 (eg ±5 degrees) does not change the function of the needle (4) or the sewing parameters.

[0084] The first and second variants have an overall angular variation of the axis X2 of at least 20 degrees (see Figure 5 and Figure 6 ).

[0085] In order to widen the operating sector, at least a third variant of the bushing (110) is included.

[0086] In fact, including the third ring (133) ( Fig.12 , 12A , 12B), which includes a plate (132), the plate (132) and the associated tabs (134) having grooves (135).

[0087] When the unit (10) is in the 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 (relative to position (M2), and 20 degrees relative to position (M1)).

[0088] In this case, any final angular displacement (from position (M3)) of +β3, -β3 (eg ±5 degrees) will not change the sewing parameters.

[0089] The cited variants, the first variant, the second variant and the third variant, generally exhibit an angular variation of the axis (X2) of at least 30 degrees.

[0090] Specifically, by including three rings (113, 123, 133) such as those adapted above, the operator actually works on a horizontal support (or an almost horizontal support) defined by the plates (112, 122, 132), respectively, with all the advantages that this entails.

[0091] Specifically, in unit (10) ( Figure 5 ) and (P2)( Figure 6 ) is applied to a plurality of spatial positions from among the cited end positions (P1); in each spatial position, the forming arm (8) can be set in another series of positions due to its oscillation relative to the relative axis (X1).

[0092] In each spatial position, the position (axis C) of the end (53) of the rotating hook (13) is defined by its uppermost point (T) in which the first sewing thread cooperates to form a sewing stitch, which will be of the "knot stitch" type if the end of the hook pulls the second sewing thread, or of the "chain stitch" type if the second sewing thread is not included.

[0093] As indicated, the optimal solution is to implement connecting means of the unit (10) at the base and guiding means causing the oscillation of the unit, the connecting means and guiding means being adapted to define the axis (C) of the oscillation at the highest point (T) affected by the end (53) of the rotating hook during its rotation; any displacement from the highest point presented by the end (53) of the rotating hook after rotation relative to the optimal solution to the axis (C) is allowed as long as the end of the rotating hook is inserted in the loop (90) created in the first sewing thread (5) after the needle (4) is raised.

[0094] The circuit defines an operating zone (S) which always occurs in the same position as that which is not affected by the oscillations of the unit (10); an alternative to the case already considered is that the axis (C) can be arranged to pass through the interior of the operating zone.

[0095] As already specified in the different positions applied to the unit (10), a horizontal abutment is defined by the plate (60) for the item to be sewn.

[0096] In one embodiment, the oscillation axis (X3) of the plate (60) coincides with the axis (C).

[0097] In one variant, a sewing machine for sewing articles comprises: a turntable (3) supported by a base (2) in a cantilevered manner, the free end (3a) of the turntable (3) carrying a sewing needle (4), the sewing needle (4) facing downward, the sewing needle (4) pulling a first sewing thread (5), a leather presser foot (6) and a feed foot (7); a first actuator, the first actuator being arranged in the turntable (3) for moving the needle; an arm, one end of the arm being rigidly fixed to the unit (10) supported by the base and the other end of the arm being capable of rotatably supporting a bushing (11).

[0098] Specifically, the arm is fixed relative to the unit (10).

[0099] The sewing machine also includes a rotating hook (13) located in the bushing (11) and a second actuating device acting in phase with the first actuating device to pull the rotating hook to rotate, thereby forming sewing stitches in cooperation with the needle inside the bushing.

[0100] In this case, knotted sewing stitches or chain lock sewing stitches can also be realized.

[0101] In the first case (knot stitch), the swivel hook (13) pulls the second sewing thread (15) from a yarn spool (16) located in the bushing (11); in the second case (chain stitch), only the first sewing thread (5) pulled by the needle (4) is used.

[0102] The connection between the unit (10) and the base (2) is obtained by the technical functional specifications considered above, which make it possible to set the unit (10) and the components carried thereby to oscillate relative to the axis (C).

[0103] Specifically, the variant cited provides a unit (10) which fixedly supports the arm carrying the bushing; a plurality of spatial positions are imposed on the unit (10), oscillating between end positions (P1, P2) relative to the axis (C).

[0104] The proposed variant also comprises a plate (60) so as to define, in any spatial configuration of the unit (10), a horizontal abutment for the items to be sewn.

Claims

1. A sewing machine for sewing articles, comprising: A turntable (3), the turntable (3) being supported by the base (2) in a cantilevered manner, the free end (3a) of the turntable (3) carrying a sewing needle (4), the sewing needle (4) facing downward, the sewing needle (4) pulling a first sewing thread (5); a first actuating device, the first actuating device being arranged in the turntable and used for moving the needle; A forming arm (8), the end of which is rotatably supported by a unit (10) carried by the base in an oscillating manner, and the other end of the forming arm (8) is rotatably supported by a sleeve (11) located below the needle and open toward the needle; the axis of the sleeve is coaxial with the oscillation axis of the arm; a stabilizing device (12), the stabilizing device (12) is associated with a given arm (8), the oscillation of the arm in one direction imposes on the sleeve (11) an oscillation in the opposite direction and with equal amplitude; a rotating hook (13), the rotating hook (13) is located in the sleeve (11) and is used to pull the second seam sewing thread (15), said second sewing thread (15) originating from a yarn spool (16) located in the bushing itself; a second actuating device (14), said second actuating device (14) acting in phase with the first actuating device to pull the rotating hook to rotate, thereby cooperating with the needle (4) and the associated first sewing thread (5) inside the bushing to form a knotted sewing stitch; the sewing machine is characterized in that it includes a device for connecting the unit (10) to the base (2) so that the unit can oscillate according to a coaxial arc of a circle of equal radius centered on a common axis (C), the concave part of the coaxial arc facing the bushing (11).

2. A sewing machine for sewing articles, comprising: A turntable (3) supported by the base (2) in a cantilevered manner, the free end (3a) of the turntable (3) carrying a sewing needle (4), the sewing needle (4) facing downward, the sewing needle (4) pulling a first sewing thread (5); a first actuating device, the first actuating device being arranged in the turntable and used for moving the needle; a shaped arm (8) whose end is rotatably supported in an oscillating manner by a unit (10) carried by the base, and whose other end rotatably supports a bushing (11) located below the needle and open toward the needle; the axis of the bushing being coaxial with the axis of oscillation of the arm; a stabilizing device (12) associated with a given arm (8), the oscillation of the arm in one direction imposing on the bushing (11) an oscillation in the opposite direction and with equal amplitude; a rotating hook (13), the rotating hook being located in the bushing (11); A second actuating device (14) which acts in phase with the first actuating device to pull the rotating hook to rotate, thereby cooperating with the needle (4) and the associated sewing thread (5) inside the bushing to form a chain stitch, the sewing machine being characterized in that it includes a device for connecting the unit (10) to the base (2) so that the unit can oscillate according to a coaxial arc of a circle of equal radius centered on a common axis (C), the concave portion of the coaxial arc facing the bushing (11).

3. A sewing machine for sewing articles, comprising: A turntable (3) supported by the base (2) in a cantilevered manner, the free end (3a) of the turntable (3) carrying a sewing needle (4), the sewing needle (4) facing downward, the sewing needle (4) pulling a first sewing thread (5); a first actuating device, the first actuating device being arranged in the turntable and used for moving the needle; an arm, one end of which is fixed to a unit (10) carried by the base and the other end of which is rotatably supported by a bushing (11) located below the needle and open toward the needle; a swivel hook (13) located in the bushing (11); A second actuating device (14) acts in phase with the first actuating device to pull the rotating hook to rotate, thereby cooperating with the needle (4) and the associated first sewing thread (5) inside the bushing to form a sewing stitch; the sewing machine is characterized in that it includes a device for connecting the unit (10) to the base (2) so that the unit can oscillate according to a coaxial arc of a circle of equal radius centered on a common axis (C), the concave portion of the coaxial arc facing the bushing (11).

4. The sewing machine according to claim 1, 2 or 3, characterized in that: The axis (C) of the arc of the circumference is located inside the bushing (11).

5. The sewing machine according to claim 1, 2 or 3, wherein: After lifting the needle, a loop (90) is formed in the thread (5) carried by the needle (4), characterized in that the axis (C) of the arc of the circumference is located inside the loop (90).

6. The sewing machine according to claim 1, 2 or 3, characterized in that: The axis (C) of the arc of the circle affects the highest point (T) determined by the operating end (53) of the swivel hook during the rotation of the swivel hook.

7. The sewing machine according to claim 1, 2 or 3, wherein: The bushing (11) has an upwardly facing opening (11A), characterized in that a plate (60) is located in the opening, the plate (60) being rotatably supported by the edge of the opening according to an axis (X3) perpendicular to the oscillation plane of the unit (10), the opening having a slot (62) for the needle (4) to pass through.

8. The sewing machine according to claim 7, characterized in that The groove (62) extends parallel to the axis (X3).

9. The sewing machine according to claim 1, 2 or 3, characterized in that: The device for connecting the unit (10) to the base (2) comprises: at least one support (20, 20A) fixed to the base, wherein a grooved track (21, 21A) is made to extend according to an arc (35, 35A) of a circle centered on the axis (C); a series of rollers (22) sliding in the grooved track, rotatably carried by a sector (23, 23A) fixedly constrained to the unit (10).

10. The sewing machine according to claim 9, characterized in that The sectors (23A) comprise cogs (25) extending according to an arc of a circle centered on the axis (C), and the motor units (27) are arranged to oscillate the sectors in opposite directions (Y1, Y2) so as to define two extreme spatial positions (P1, P2) for each unit (10).

11. The sewing machine according to claim 3, characterized in that The rotating hook (13) pulls a second sewing thread (15) from a yarn spool located in the bushing itself, so as to define a knotted sewing stitch in cooperation with the needle (4) and the associated sewing thread (5).

12. The sewing machine according to claim 1, 2 or 3, wherein: The bushing (110) has an opening (111) accessible from above, characterised in that it comprises a ring removably connected to the side wall of the bushing, the ring comprising in the upper part a plate at the opening for receiving and adjoining the material to be sewn, the plate having a slot through which the needle of the sewing machine passes and can thus be oriented horizontally to a predetermined position assumed by the unit (10).

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