| JP03149076 | BEDDING DEMOUNTING DEVICE FOR BEDDING SEWING DEVICE |
| JP2749785 | HEM PROCESSING DEVICE FOR FABRIC PRODUCT |
| WO/1992/012282 | METHOD FOR SEWING UPHOLSTERY ASSEMBLIES |
Landoni, Giannino (Strada Provinciale Busto/Cassano 3, Fagnano Olona, I-21054, IT)
| 1. | Method for the simultaneous tensioning on four sides of a textile material (11) fed continuously to a sewing machine (10), said sewing machine (10) including sewing members (12, 15) and drawing means (13) able to unwind said textile material (11) from feed means (14), characterized in that it provides that pre. tensioning means (19) and tensioning/ drawing means (20. 20a), mounted substantially at inlet to said sewing machine (10), act on the sides of said textile material (11) to provide a constant tensioning of said textile material (11), which unwinds continuously from said feed means (14) to be sent to said sewing members (12,15). |
| 2. | Method as in claim 1, characterized in that it provides that the lateral tension of the textile material (11) is kept constant both during forward stitching, when the drawing means (13) rotate forwards, and also during backstitching, when the drawing means (13) rotate backwards. |
| 3. | Method as in claim 2, characterized in that it provides that a compensation element (17) to recover the material is automatically activated when said drawing means (13) rotate backwards to keep the longitudinal tensioning of the textile material (11) constant. |
| 4. | Method as in claim 3, characterized in that said textile material (11), drawn by said drawing means (13), unwinds from said feed means (14) braked by braking means (18), cooperates with an idle guide roller (16), cooperates with said movable compensation element (17), enters into contact with said pre. tensioning means (19) to be laterally widened and is then introduced between said tensioning/drawing means (20. 20a) and relative sliding surfaces (56,56a) so that its lateral tensioning remains substantially constant during its passage through the sewing members (12,15). |
| 5. | Method as in claim 4, characterized in that during contact with said pre. tensioning means (19) the lateral edges of the textile material (11) are gripped by gripping elements (36) arranged at the ends of said means (19) and mounted on bushing elements (35), said bushing elements (35) being solid with support elements (31) having shaped ends (32) held elastically pressed against the profiles (34) of cam means (33. 33a), said lateral edges of the textile material (11) being induced to follow an outward displacement, putting the textile material (11) under lateral tension before introducing it between the tensioning/drawing means (20. 20a) and the relative sliding surfaces (56. 56a). |
| 6. | Method as in claim 5, characterized in that said tensioning/drawing means (20. 20a) keep the lateral tension of the textile material (11) constant throughout its passage through the sewing members (12,15) as far as inlet to the drawing means (13) and discharge towards the outlet assembly (lOc). |
| 7. | Method as in any claim hereinbefore, characterized in that, when the drawing means (13) rotate backwards in order to do backstitches, the tensioning/drawing means (20. 20a) also rotate backwards, drawing the textile material (11) backwards and keeping the lateral tensioning constant. |
| 8. | Method as in claim 7, characterized in that during the backward rotation of said drawing means (13), tensioning elements (27. 27a) arranged at the ends of said pre. tensioning elements (19) are braked by the friction of said semi. spherical ends (32) of the rods (31) against the profiles (34) of the cam means (33. 33a), and do not rotate backwards due to the presence of free. wheel means (53) mounted in cooperation with said shaft (23), whereas said bushings (35), with said gripping elements (36) gripping the edges of the textile material (11), rotate backwards in order to keep the lateral tension of the textile material (11) constant also during the backward movements. |
| 9. | Device for the simultaneous tensioning on four sides of a textile material (11) fed continuously to a sewing machine (10), said sewing machine (10) including sewing members (12, 15) and drawing means (13) able to unwind said textile material (11) from feed means (14), characterized in that it comprises pre. tensioning means (19) and tensioning/drawing means (20. 20a) arranged substantially at inlet to said sewing machine (10) and able to provide a constant tensioning on the sides of said textile material (11), which unwinds continuously from said feed means (14) to be sent to said sewing members (12,15). |
| 10. | Device as in claim 9, characterized in that said pre. tensioning means (19) and said tensioning/drawing means (20. 20a) are mounted in an intermediate position between said drawing means (13) and said feed means (14). |
| 11. | Device as in claim 9, characterized in that said sewing machine (10) is a multi. needle quilting/embroidering machine. |
| 12. | Device as in any claim from 9 to 11 inclusive, characterized in that said pre. tensioning means (19) and said tensioning/drawing means (20. 20a) are laterally supported by supporting walls (22. 22a) mounted on an inlet assembly (10a) of the sewing machine (10) in an intermediate position between the feed means (14) and the drawing means (13). |
| 13. | Device as in claim 12, characterized in that at least one supporting wall (22a) is translatable laterally and can be blocked on each occasion in the position most suitable for the width of the textile material (11) which has to be worked. |
| 14. | Device as in any claim from 9 to 13 inclusive, characterized in that said pre. tensioning means comprise a roller (19) composed of an idle central part (26) rotating on a shaft (23) and two lateral parts (27. 27a) having means able to grip the lateral edges of the textile material (11) and to widen them to laterally tension the textile material (11). |
| 15. | Device as in claim 14, characterized in that said idle roller (26) can be extended longitudinally. |
| 16. | Device as in claim 14, characterized in that each of said means to grip and widen the textile material (11) comprises at least two disk elements solid with each other, respectively an inner disk (29) and an outer disk (30), in the peripheral part of said disks (29,30) coaxial holes being present, aligned and parallel to the axis of the shaft (23), wherein mating rods (31) are able to slide in a direction parallel to the axis of the shaft (23), the ends of said rods (31) facing said supporting walls (22. 22a) being shaped like a semi. sphere (32). |
| 17. | Device as in claim 16, characterized in that said semi. spherical ends (32) of said rods (31) are able to cooperate with a profile (34) of two circular front cams (33. 33a) fixed to the supporting walls (22. 22a) in a position concentric to said shaft (23). |
| 18. | Device as in claim 17, characterized in that the profiles (34) of said circular front cams (33. 33a) have their lower parts in correspondence with the upper part of said supporting walls (22. 22a) and the higher parts in correspondence with the lower part of said walls (22. 22a). |
| 19. | Device as in any claim from 9 to 18 inclusive, characterized in that in the intermediate part of every rod (31), between the disks (29,30) a bushing element (35) is mounted, having on its periphery a plurality of gripping elements (36) protruding from its outer surface, said gripping elements (36) being able to grip the lateral edges of the textile material (11). |
| 20. | Device as in claim 19, characterized in that said bushing elements (35) are able to rotate on said rods (31) and are held in position by two wall washers, an outer (37) and an inner (38), fixed to the rods (31). |
| 21. | Device as in claim 20, characterized in that the distance between the outer diameters of two diametrically opposite bushing elements (35) is substantially equal to the outer diameter of the idle roller (26). |
| 22. | Device as in any claim from 9 to 21 inclusive, characterized in that on each of said rods (31), between the inner wall washer (38) and the inner support disk (29), elastic means (39) are mounted able to keep the semi. spherical end (32) of said rods (31) in constant contact with the profile (34) of said cams (33. 33a). |
| 23. | Device as in claim 22, characterized in that said spring means (39) are associated with means to regulate the pressure, comprising at least a thrust element (59) and a positioning element (61) able to slide on said shaft (23) and to be selectively fixed thereto by means of attachment means (62) in a position wherein the pressure on the springs (39) is the most suitable for the textile material (11) which has to be worked. |
| 24. | Device as in any claim from 9 to 23 inclusive, characterized in that said tensioning/drawing means comprise chains (20. 20a) mounted one on either side on the inner part of said two supporting walls (22. 22a). |
| 25. | Device as in claim 24, characterized in that said chains (20. 20a) have the outer part of the links lined with gripping blocks (41) made of anti. slip material, for example rubber, said gripping blocks (41) being able to cooperate with relative sliding surfaces (56,56a) to grip and draw the laterally tensioned material. |
| 26. | Device as in claim 24, characterized in that said chains (20. 20a) are able to slide on four pinions of equal diameter (42. 42a; 43. 43a) rotating on bearings mounted on the supporting walls (22. 22a). |
| 27. | Device as in claim 25 or 26, characterized in that it comprises a pair of pressure elements (21. 21a) able to act on the inner part of the links of the drawing chains (20. 20a) and cooperating with relative actuators (55) to regulate the pressure between the gripping blocks (41) and the relative sliding surfaces (56. 56a). |
| 28. | Device as in claim 26, characterized in that the two pinions (42. 42a) facing the drawing rollers (13) are solidly mounted on a shaft (44) at one end of which a pinion (47) is solidly mounted, said pinion (47) being associated, by means of a chain (46), to a pinion (45) solid with the drawing means (13) in order to synchronize the movement of said drawing means (13) and said chains (20. 20a). |
| 29. | Device as in claims 14 and 26, characterized in that at one end of the shaft (23) of the pre. tensioning means (19), an electromagnetic clutch (52) is mounted by means of a free. wheel (53), on the anchor (51) of which a pinion (50) is solidly mounted, connected by means of a chain (49) to a pinion (48) solid with one of said pinions (43) of said chains (20. 20a) in order to synchronize the movement of said drawing means (13), said tensioning/drawing chains (20. 20a) and said pre. tensioning means (19). |
| 30. | Device as in any claim from 9 to 29 inclusive, characterized in that when the drawing rollers (13) rotate forwards, drawing the textile material (11), the drawing chains (20. 20a) and the pre. tensioning means (19) move in the same direction and at the same peripheral speed with a movement derived from said drawing rollers (13) by means of said pinions (45,47, 42,43, 48 and 50) and said chains (46,49). |
| 31. | Device as in any claim from 9 to 30 inclusive, characterized in that when the drawing rollers (13) rotate backwards, releasing the textile material (11), said chains (20. 20a) also rotate backwards, drawing the edges of the textile material (11) backwards, but only the idle central part (26) of the pre. tensioning roller (19) rotates backwards due to friction with the textile material (11), while the two lateral tensioning elements (27. 27a), solid with the shaft (23), remain still, due to the pressure exerted by the semi. spherical ends of the rods (31), subjected to the thrust of the springs (39) against the profiles (34) of the cams (33. 33a). |
| 32. | Device as in claims 29 and 31, characterized in that said pinion (50) is made solid with the anchor (51) of said clutch (52) by means of a free. wheel (53) so that said pinion (50), when it rotates backwards, does not transmit said movement to said shaft (23). |
| 33. | Device as in claim 29, characterized in that said clutch (53) can be selectively dis. engaged so as to make the shaft (23) and the two lateral elements (27. 27a) of the pre. tensioning roller (19) idle, for example during operations to lead the textile material (11) manually into the machine. |
| 34. | Multi. needle sewing machine, advantageously a quilting/embroidering machine, comprising sewing members (12,15) and drawing means (13) able to unwind said textile material (11) from feed means (14), characterized in that it comprises pre. tensioning means (19) and tensioning/drawing means (20. 20a), mounted substantially at inlet to said sewing machine (10), able to act on the sides of said textile material (11) both during forward stitching and also during backstitching, to provide a constant tensioning of said textile material (11) which unwinds continuously from said feed means (14) to be sent to said sewing members (12, 15). |
| 35. | Sewing machine as in claim 34, characterized in that it comprises at least a compensation element (17) able to keep the longitudinal tension of the textile material (11) constant during the backward rotation of the drawing means (13). |
The invention also concerns a sewing machine, advantageously but not exclusively an automatic multi-needle quilting/embroidering machine, equipped with said tensioning device.
The invention also concerns a method to continuously perform quilting, embroidery, the application of cords, ribbons or trimmings, on simple or padded fabrics, simultaneously tensioned on four sides.
The invention is applied in the textile field and refers to quilting, embroidery, the application of cords, ribbons or trimmings etc. , performed on continuously fed, simple, multi-layer or padded textiles, with the simultaneous tensioning of said materials on four sides.
The invention is characterized by the presence of at least one inlet pre-tensioning element, at least one pair of drawing and lateral tensioning chains, two or more drawing and front tensioning rollers, and an adjustable braking system for the rolls which feed the material; these components allow to guarantee optimum tensioning on all four sides, for every type of textile material, in its passage through the sewing members.
The invention is also characterized by the presence of a compensation system to recover the material during
backstitching, in order to keep the front tensioning constant even when the drawing rollers rotate backwards with respect to the direction of unwinding of the feed roll.
BACKGROUND OF THE INVENTION Multi-needle quilting machines are characterized in that they work"continuously", that is they continuously quilt the materials which are drawn by suitable drawing rollers and unwind from rolls, which are subject to controlled braking to ensure a constant and suitable tensioning in a longitudinal direction.
In multi-needle quilting machines the quilting pattern is achieved by moving the materials to be quilted in two main directions: front (backwards/forwards) and sideways (left/right); the materials are moved under the needles with an infinite combination of these two main movements in order to obtain the desired pattern.
Modern automatic multi-needle quilting machines, with electronic command and computerized management, have very limited tolerances of the sideways/front movements and can, in theory, make every type of ornamental pattern, even the most sophisticated and similar to embroidery.
In practice, however, their precision in making the ornamental pattern is limited by the fact that the materials to be quilted are held in tension only on the two front sides, at the front by the drawing action of the drawing rollers and at the rear by the braking action of the rolls, while the two lateral sides are free and are therefore subject to deformations; the more elastic the materials, the more accentuated these deformations.
In embroidering machines too, both of the"schiffli"type and the multi-head type, the formation of the ornamental pattern is made by moving the materials to be embroidered under the needles in two main directions: front
(backwards/forwards) and sideways (left/right).
In embroidering machines, however, to guarantee maximum precision in the ornamental pattern, the materials to be embroidered are fixed at the four sides on suitable frames which are displaced in every direction with movements controlled by a computer; this operation of attaching the materials to the frames must be repeated manually with every new job, and takes a considerable period of time.
Productivity. is greatly penalized by this, since it is not possible to work the textile material continuously, and until now, no-one has ever proposed a simultaneous tensioning system of the materials on the four sides for continuous production which would give sufficient guarantees of reliability and good functioning.
The present invention intends to fill this vacuum and propose, both to improve precision in quilting machines and to increase the productivity of embroidering machines, a practical and efficient solution which will guarantee an efficient simultaneous tensioning on the four sides of materials which move in all directions during continuous processes.
The present Applicant has devised, tested and embodied this invention to achieve these purposes.
SUMMARY OF THE INVENTION The invention is set forth and characterized in the respective main claims, while the dependent claims describe other characteristics of the main embodiment.
The purpose of the invention is to provide a device, and the relative method, for the simultaneous tensioning on four sides of textile material to be quilted or embroidered.
The invention is suitable to be applied on a sewing machine, particularly a multi-needle quilting machine/ embroidering machine, in order to continuously work textile
materials fed continuously from rolls, making ornamental quilting/embroidery patterns of very high precision.
Another purpose is to make a sewing machine with the device mentioned above and suitable to continuously work simple or padded fabrics, with simultaneous tensioning on the four sides, obtaining any ornamental pattern, quilted or embroidered, also with the application of cords, ribbons or trimmings, with very high precision designs.
A sewing machine on which the tensioning device according to the invention is applied comprises at least a trolley, which can be translated laterally, on which are mounted: the rollers for drawing the materials, the supports of the rolls of textile material to be quilted/embroidered, equipped with suitable tensioning brakes, and at least a compensation roller to recover the material during backstitching, that is, when the drawing rollers rotate backwards in the opposite direction to that in which the roll is unwinding.
This trolley is equipped with alternative lateral left/ right movements, managed directly by a command computer of the sewing machine following the ornamental pattern to be quilted/embroidered.
The drive of the drawing rollers which draw the materials is also managed directly by the command computer, and the rollers can rotate backwards or forwards in order to make the ornamental pattern to be quilted/embroidered; the compensation roller (s) is/are made to function automatically when the drawing rollers rotate backwards to keep the tensioning of the materials constant.
Thanks to the infinite combination of these two main movements, sideways (left/right) and front (backwards/ forwards), the materials to be quilted/embroidered are moved in all directions under the needles to make the required ornamental pattern to be quilted/embroidered.
The device according to the invention is mounted on the translatable trolley, in an intermediate position between the compensation rollers and the drawing rollers. This device consists of a supporting structure comprising two lateral walls on which a pre-tensioning element, two tensioning and drawing chains, two pressure bars and two sliding surfaces are mounted.
The pre-tensioning element is positioned at inlet to the machine and its purpose is to widen the material and to tension it before it inserts the lateral edges of the material between the drawing chains and the sliding surfaces.
The pair of drawing chains (one on each side) has the outer part of the links lined with gripping blocks made of anti-slip material, for example rubber. The task of these blocks is to hold firmly the lateral edges of the material, already under tension from the pre-tensioning element, and to draw them along the sliding surfaces, keeping the lateral tension substantially constant as the material transits under the sewing needles.
In cooperation with these drawing chains there are pressure bars commanded by pneumatic cylinders; these bars act downwards on the inner part of the two drawing chains and their job is to increase the force which retains the edges of material between the blocks of the chains and the sliding surfaces on which the material passes.
In a preferential embodiment of the invention, the material unwinds from the feed roll, passes on an idle guide roller, under the compensation roller and then passes over the pre-tensioning inlet element which puts it under tension, widening the edges and inserting them between the blocks of the drawing chains and the sliding surfaces. Then, the material is drawn, under tension, under the sewing
members, and finally passes, already quilted or embroidered, between the two drawing rollers.
In a preferential embodiment, the rotary movements of these components are synchronized and are derived, by means of appropriate transmission members, from the drawing rollers, which in turn receive the impulses to move backwards/forwards from a suitable DC motor, managed directly by the command computer by means of a drive interface, following the ornamental pattern to be made.
According to one characteristic of the invention, the rotatory movement of the pre-tensioning element is synchronized with that of the drawing rollers and the drawing chains only when the latter are drawing the material forwards, but stops when the drawing rollers and the chains rotate backwards, that is, during the backstitching steps.
According to another characteristic of the invention, the pre-tensioning element consists of a roller made in three parts: a central part formed by a tube rotating idle on bearings mounted on the shaft of the pre-tensioning element, free to rotate backwards or forwards irrespectively, due to the effect of the friction of the material, and two lateral parts mounted at the ends and including devices able to grip the lateral edges of the material and to widen them to tension the material laterally.
In one embodiment of the invention, each of said devices consists of two disks, an inner disk facing the central part of the roller and an outer disk facing the supporting wall, made solid with each other by means of a spacer of the appropriate length and fixed to the shaft of the pre- tensioning roller by means of keys.
On the peripheral part of the disks there are axial holes, equidistant and aligned with each other; an equal number of rods, whose ends facing the supporting walls are shaped like
a semi-sphere, slide freely therein, in a direction parallel to the axis of the roller.
On the lateral walls of the supporting structure two front circular cams are mounted, with tempered profiles, and are fixed to said walls in a position concentric to the shaft of the pre-tensioning roller. The circular cams have their shaped profile facing the semi-spherical ends of the steel rods, with the lower part of the profile being positioned in correspondence with the upper part of said walls and the higher part of the profile being positioned in correspondence with the lower part of the walls.
In the intermediate part of each steel rod, between the inner and outer disks, a bushing element is mounted with a plurality of pointed pins protruding from its outer surface.
The bushing elements are able to rotate freely on the rods and are kept in position by two wall washers, one on the right and one on the left, fixed to the rods.
On each of the rods, between the inner wall washer and the inner supporting disk, there are elastic means, for example a compression spring, of the appropriate length. The elastic means, thanks to their action between the inner wall washer and the inner supporting disk, keep the semi-spherical end of the rods always in contact with the profile of the cam.
According to the invention, while the machine is functioning, the fabric, drawn by the drawing rollers, unwinds continuously from the relative roll, subject to appropriate braking, passes over the idle guide roller, under the compensation roller and then over the pre- tensioning element which receives movement from the drawing rollers and therefore rotates at the same peripheral speed as them.
While in contact with the pre-tensioning element, which occurs for an angle of about 90°, the edges of the material
are gripped by the pins present in the outer shell of the bushings. Since the rods on which the bushings are mounted are subject to the thrust from the springs, their semi- spherical ends follow the profile of the cams; while in contact with the material, they pass therefore from an inner position to an outer position, following the thickness of the profile of the cams, which is at its maximum at the moment when the edges of the material are caught, and at its minimum when they are released.
As a consequence, under the thrust of the springs, the bushings, solid with the rods, also move from inside towards the outside following the profile of the cams, consequently widening the edges of the material gripped by the pins present in the shell of the bushings.
Before the material is released by the pins of the bushings when, continuing its travel towards the drawing rollers, it starts to move horizontally, losing contact with the pins of the pre-tensioning element, the edges of the material, under tension, are inserted and gripped between the blocks of the drawing chains, which advance at the same peripheral speed, and the sliding surfaces.
In this way, the tension supplied to the material by the pre-tensioning roller is kept constant for the whole period wherein the material is under the sewing needles, before entering between the drawing rollers.
As soon as the drawing rollers begin to rotate backwards, for example to make backstitches following the commands of the computer according to the ornamental pattern to be made, the drawing chains also begin to rotate backwards and the compensation element begins to lower, to keep the front tension constant on the material released by the drawing rollers.
According to the invention, the idle central part of the
pre-tensioning element rotates backwards due to friction with the material, but the two lateral parts, solid with the shaft by means of keys, do not rotate backwards. This happens because the command pinion of the shaft of the pre- tensioning element is mounted on means which allow it to rotate idly backwards; on the contrary, the two outer devices of the pre-tensioning element and the shaft on which they are mounted remain still, since they are blocked by the friction of the semi-spherical ends of the rods against the profiles of the cams due to the action of the springs.
The bushings, however, since they can rotate freely on the rods, under the action of their pins engaged in the edges of the material, rotate backwards following the movement thereof, but, held in their position by the wall washers, they do not release the tension previously imposed on the edges of the material during the inlet step.
This characteristic is particularly significant in that, unlike conventional tensioning devices which allow tensioning only with forward movements, the device according to the invention does not release the tensioning if the fabric is made to move backwards.
According to another characteristic of the invention, the tensioning imparted to the edges of material can be regulated to adapt it to the greater or lesser elasticity of said material.
In a preferential embodiment, this is obtained by means of a mobile disk located between the springs mounted on the rods and the inner supporting disk. The mobile disk is fixed, by means of a series of stays passing through equidistant radial holes made in the inner supporting disk, to another disk provided with a hub which slides on the command shaft and can be blocked on the latter by means of an attachment screw.
By suitably approaching or distancing the disk provided with the hub to/from the support disk and blocking it in position by means of the attachment screw, it is thus possible to increase or decrease the pressure of the springs mounted on the rods to adapt it to the type of material being worked.
According to another characteristic of the invention, the command pinion of the shaft of the inlet pre-tensioning roller is not mounted directly on the shaft, but on the anchor of a clutch which can be engaged or disengaged as desired.
During normal working, the clutch is engaged and renders the command pinion solid with the shaft, whereas when the materials are set up manually, in order to facilitate this operation, the clutch can be disengaged and thus leave the pre-tensioning roller free to rotate.
According to the solution proposed, there is a free-wheel able to permit the pre-tensioning roller to stop when the drawing rollers rotate backwards; in the preferential embodiment, the free-wheel is not mounted directly between the shaft and the command pinion, but between the shaft and the clutch manifold.
According to another characteristic of the invention, one of the device's supporting walls is fixed, whereas the other wall is translatable laterally in order to adapt the distance between the drawing chains and between the terminals of the pre-tensioning roller to the width of the material which has to be worked.
In a further solution of the invention, at least the central part of the pre-tensioning roller can be extended in the direction of the axis of rotation during the tensioning step of the textile material winding onto part of it.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other characteristics of the invention will be apparent from the following description, given as a non- restrictive example, of a preferential form of the invention with reference to the attached drawings: Fig. 1 is a schematic view of a multi-needle quilting/ embroidering machine of the type able to comprise a tensioning device for textile material on the four sides during continuous quilting/embroidery operations according to the invention; Fig. 2 is a schematic view of a preferential embodiment of the device according to the invention; Fig. 3 is a longitudinal section of a detail of the pre- tensioning element.
DETAILED DESCRIPTION OF PREFERENTIAL EMBODIMENT Fig. 1 shows an electronically commanded multi-needle quilting/embroidering machine 10, the general type of which is substantially known. The quilting machine 10 comprises, in its essential parts, an inlet assembly 10a, a sewing assembly 10b and an outlet assembly 10c.
The inlet assembly 10a is used to feed the textile material 11 which has to be worked. The inlet assembly 10a, commonly called the trolley, is managed and controlled by a command software and is therefore able to move the textile material 11 in any direction, backwards/forwards or left/right, in order to make any type of ornamental pattern, even very complex ones.
The sewing assembly 10b comprises upper sewing members 12 and lower sewing members 15 of a conventional type which cooperate with each other with their respective threads and make stitches on the textile material 11, making more or less complex ornamental patterns of quilting or embroidery.
The machine 10 comprises drawing rollers 13 which draw the textile material 11 unwinding it from the roll 14 on which
it is wound, an idle guide roller 16, a movable compensation roller 17 and supports for the roll 14 equipped with braking members 18.
With reference to Fig. 2, between the movable compensation roller 17 and the drawing rollers 13 a lateral tensioning device according to the invention is inserted; the device consists, in the embodiment shown here, of an inlet pre- tensioning roller 19, two lateral tensioning and drawing chains 20-20a, two pressure elements 21-21a, two supporting walls 22-22a and transmission means.
With reference to Fig. 3, the pre-tensioning roller 19 consists of a shaft 23 rotating on first bearings 24-24a fixed to the respective supporting walls 22-22a. In the central part of said shaft 23 an idle roller 26 is mounted, on second bearings 25-25a, which in this case can also be extended longitudinally due to the presence of coupling eyelets 58 between two mating roller elements.
At the two ends of the shaft 23 two tensioning elements 27-27a are mounted, fixed to the shaft 23 by means of keys 28.
Each of the tensioning elements 27-27a consists of two disks, an inner disk 29 facing the idle central part 26 of the pre-tensioning roller, and an outer disk 30 facing the supporting wall 22, the disks being solid with each other by means of a spacer of the appropriate length and fixed to the shaft 23 by means of the keys 28.
On the peripheral part of the disks 29 and 30 coaxial holes are made, equidistant and with the axes parallel to the axes of the shaft 23; an equal number of steel rods 31, with their ends facing the supporting walls 22 shaped like semi-spheres 32, are able to slide freely, in a direction parallel to the axis of the shaft 23, in said holes.
Two steel circular front cams 33-33a, with tempered
profiles 34, are mounted on the supporting walls 22; they are fixed to said walls in a position concentric to the shaft 23 with the tempered profile 34 facing the semi- spherical ends 32 of the steel rods 31.
The lower part of the profile 34 is located in correspondence with the upper part of the supporting walls 22, while the higher part of the profile 34 is located in correspondence with the lower part of the supporting walls 22.
In the intermediate part of each steel rod 31, between the disks 29 and 30, a bronze bushing 35 is mounted equipped with a plurality of pointed pins 36 protruding from its outer surface. Said bushings 35 are mounted in such a fashion that the distance between the outer diameters of two diametrically opposite bushings is substantially equal to the outer diameter of the idle roller 26. Said bushings 35 can also rotate freely on the steel rods 31 and are kept in position by two wall washers, an outer washer 37 and an inner washer 38, fixed to the steel rods 31.
Between the washers 38 and the relative bushings 35 thrust bearing bearings are advantageously mounted.
On each of the steel rods 31, between the inner wall washer 38 and the inner supporting disk 29, a compression spring 39 is mounted, of the appropriate length, which with its action keeps the semi-spherical end 32 of the rods 31 in constant contact with the tempered profile 34 of the cams 33-33a.
Two drawing and tensioning chains 20-20a are mounted, one on each side, on the supporting walls 22-22a. Said chains 20-20a have the outer part of the links covered with gripping blocks 41, advantageously made of rubber, and are able to slide on four pinions of equal diameter 42-42a and 43-43a, rotating on bearings mounted on the supporting walls
22-22a.
The two pinions 42-42a, facing the drawing rollers 13, are solidly mounted on a transmission shaft 44 which rotates on bearings 54 fixed to the supporting walls 22-22a. With reference to Fig. 2, a pinion 45 is fixed to the left end of the lower drawing rollers 13; by means of an auxiliary chain 46, the pinion 45 transmits movement to a pinion 47 solidly mounted at the left end of the shaft 44. The number of teeth of the pinions 42,43, 45 and 47 is suitably calculated so that the peripheral speed of the rubber blocks 41 of the chains 20-20a is equal to that of the drawing rollers 13.
The two pinions 43-43a, facing the pre-tensioning roller 19, rotate idle on bearings 40 mounted on the walls 22-22a.
With reference to Fig. 2, on the outer side of the hub of the left pinion 43 a pinion 48 is solidly mounted which, by means of a chain 49 commands a pinion 50 mounted on the anchor of an electromagnetic clutch 51, the manifold 52 of which is mounted on the shaft 23 by means of a free-wheel 53.
The number of teeth on the pinions 48 and 50 is also suitably calculated so that the peripheral speed of the pre- tensioning roller 19 is equal to that of the drawing rollers 13 and the drawing chains 20-20a.
Two pressure devices are also mounted on the walls 22-22a, consisting of two pressure elements 21-21a made of anti- friction material, which press downwards on the inner part of the drawing chains 20-20a.
The pressure devices also comprise a plurality of pneumatic cylinders 55, or other adjustable actuators which, acting on the pressure elements 21-21a, increase the pressure between the rubber blocks 41, mounted on the outer links of the chains 20-20a, and two metallic sliding surfaces 56-56a solid with the supporting walls 22-22a. The
pressure can be adjusted by varying the value of the pressure of the air compressed in the pneumatic cylinders 55.
The left supporting wall 22 is solidly fixed to the translatable trolley 10a, while the right supporting wall 22a is translatable laterally and can be clamped in the working position most suitable for the width of the material to be worked.
The device as described heretofore functions as follows.
The textile material 11 is drawn by the drawing rollers 13 and unwinds continuously from the roll 14, subject to braking by appropriate braking members 18. This braking action guarantees a constant front tensioning of the textile material 11 for as long as the drawing rollers 13 rotate forwards.
Unwinding from the roll 14, the textile material 11 passes over the idle guide roller 16, under the movable compensation roller 17 and over the inlet pre-tensioning roller 19. At the start of contact with the pre-tensioning roller 19, which occurs for an arc of about 90°, the lateral edges of the textile material 11 are penetrated by the pins 36 protruding from the bronze bushings 35 mounted on the steel rods 31. Appropriate contrasting rollers, not shown here, ensure that the edges of the textile material 11 adhere to the pre-tensioning roller 19.
The semi-spherical ends 32 of the steel rods 31, under thrust from the compression springs 39, slide on the tempered profile 34 of the front cams 33-33a, the thickness of which is greatest at the point of first contact between the textile material 11 and the pre-tensioning roller 19, and smallest at the point of release. As a consequence, the bronze bushings 35, solid with the rods 31, follow the outward movement of said steel rods 31 subjected to the
action of the springs 39, and their pins 36, engaged in the edges of the textile material 11, put it under tension.
Before it is released however, which happens when the pins 36, following the rotation of the pre-tensioning roller 19, begin to abandon the textile material 11, the edges of the textile material 11, still under tension, are taken in between the sliding surfaces 56-56a and the rubber blocks 41 mounted on the outer part of the links of the chains 20-20a which rotate at the same peripheral speed as the drawing rollers 13.
Due to the effect of the pressure supplied by the pressure elements 21-21a, the textile material 11 is drawn by the rubber blocks 41 and made to slide over the sliding surfaces 54-56a, keeping its lateral tension constant during the time it transits under the needles, until the textile material 11 is released by the rubber blocks 41 and enters between the drawing rollers 13 to finally arrive at the collection assembly 10c.
The above applies in the case that the drawing rollers 13 always draw the textile material 11 forwards.
When, due to the requirements of the pattern, the drawing rollers 13 begin to rotate backwards to make backstitches, the front tension of the textile material 11, which would otherwise slacken, is kept constant by the movable compensation roller 17 starting to function, which, commanded in a conventional manner, begins to lower with a movement corresponding to the backward movement of the drawing rollers 13.
During this step, the drawing chains 20-20a, commanded by the pinions 45,42-42a, 43-43a and 47 and by the chain 46, also rotate backwards, keeping the lateral tension of the textile material 11 constant. The pinion 50, commanded by the chain 49, also rotates backwards, but does not transmit
this movement to the shaft 23 due to the effect of the free- wheel 53, which is located in-between.
Therefore, while the idle central part 26 of the pre- tensioning roller 19 rotates backwards following the movement of the textile material 11 due to friction, the two tensioning assemblies 27-27a remain still due to the effect of the friction of the semi-spherical ends 32 of the steel rods 31 on the tempered profiles 34 of the front cams 33- 33a, under the action of the springs 39.
On the contrary, the bronze bushings 35 rotate backwards, the pins 36 of which are engaged in the edges of the textile material 11. The bronze bushings 35 rotate idle on the steel rods 31, following the backward movement of the textile material 11 but, being retained by the wall washers, they cannot move laterally, thus keeping the tension of the textile material 11 constant.
It is therefore clear that, since the bronze bushings 35 are kept in position by the action of the springs 39, during the backward movement of the textile material 11, its lateral tensioning is kept constant and is not released, which is the main purpose of the present invention.
At the moment when the drawing rollers 13 start to rotate forwards again, the shaft 23 under the action of the free- wheel 53 also begins to rotate forwards, causing the tensioning assemblies 27-27a to start to move, and restoring the conditions described at the beginning.
During the steps of preparing the quilting/embroidering machine, and especially during the step when the fabrics are led in, it is useful to be able to make the pre-tensioning roller 19 independent from the drawing system. To this purpose, the pinion 50 which commands the shaft 23 is mounted on the anchor 51 of an electromagnetic clutch 52 which can be inserted to make the shaft 23 solid with the
drawing system or dis-engaged to make it idle.
In order to adapt the tensioning force to the various types of materials 11, between the inner support disk 29 and the bronze bushings 35 a thrust disk 59 is inserted, wherein a series of holes are made, corresponding to those of the inner support disk 29, through which the steel rods 31 pass.
Said thrust disk 59 is fixed, by means of rods 60 passing through an equal number of corresponding holes on the inner support disk 29, to a positioning disk 61 which slides on the shaft 23 and can be fixed to said shaft 23 by means of a screw 62 housed in its hub.
It is clear that, by moving the positioning disk 61 towards the inner support disk 29, the thrust disk 59 is displaced in the same direction, increasing the pressure on the springs 39, while by moving the positioning disk 61 away from the inner support disk 29, the pressure on the springs 39 decreases. This allows to adapt the entity of tensioning to the various types of materials 11 which have to be worked.
Modifications and/or additions can be made to the device and method for simultaneously tensioning textile material on four sides as described heretofore, without departing from the field and scope of the present invention.