Sewing method and machine

Description

[0001] The present invention relates to the sewing art and, more particularly, to improvements in a sewing method and apparatus wherein a needle carrying a thread is axially reciprocated into and through a sewable material, e.g. cloth, leather or paper, which is moving relative to axis of needle, to stitch the material.

[0002] Sewing machines are known which use ultrasonic energy to aid the sewing operation. In particular British Patent Specification No. 1 115 170 discloses a sewing machine using an ultrasonically-vibrated rod to apply ultrasonic energy to a stitch after it has been formed by the needle. This action is to soften the area around the thread so as to reinforce the stitch.

[0003] This operation while reinforcing the seam does not improve the actual stitching operation, that is the action of the needle passing through the sewable material.

[0004] It is an object of the present invention to provide an improved sewing method of the type described, which method enables practically any sewable material, even thick and/or hard, to be stitched with greater smoothness and ease and at a greater rate than heretofore.

[0005] Another important object of the present invention is to provide a relatively simple and compact sewing machine for carrying out the improved method described.

[0006] A further important object of the present invention is to provide a sewing machine as described which has one or more additional functions of cutting, welding and marking sewable or sewed materials.

[0007] In accordance with the present invention there is provided, a sewing method using high frequency oscillation wherein a needle carrying a thread is axially reciprocated into and through a sewable material moving relative to the axis of the needle to stitch the material, characterized by the step of imparting the high-frequency mechanical oscillations to the reciprocating needle (1) and substantially in a direction of the needle reciprocation.

[0008] Preferably, the mechanical oscillations imparted to said reciprocating needle are produced or intensified selectively during the advanced stroke of each cycle of the needle reciprocation. To this end, a load of the needle experienced from the material during each cycle of the needle reciprocation is sensed and, when a predetermined change in the load is sensed, the amplitude of the mechanical oscillations is increased from nil or a predetermined minimum level.

[0009] The invention also provides, in a second aspect thereof, a sewing machine wherein a needle carrying a thread is axially reciprocated into and through a sewable material moving relative to the axis of the needle to stitch the material, the machine including means for imparting high-frequency mechanical oscillations characterized in that said high-frequency mechanical oscillations are applied to the reciprocating needle (1) and substantially in a direction of the reciprocation. Preferably, the machine further comprises means associated with the said means for producing or intensifying the mechanical oscillations imparted to the reciprocating needle selectively during at least a time period in which the needle is advanced into and through the material in each cycle of the needle reciprocation. The oscillation means may comprise an electromechanical transducer connectable in an oscillation transmitting relationship with said needle and a power supply for energizing the electromechanical transducer to impart said mechanical vibrations to said reciprocating needle. The machine may further comprise sensing means responsive to a load experienced by the needle from the material during each cycle of the needle reciprocation and control means responsive to an increase in the load for controlling the power supply to produce or intensify the mechanical oscillations imparted to the needle selectively during at least a time period in which the needle is advanced into and through the material in each cycle of the needle reciprocation.

[0010] These and other features of the present invention as well as advantages thereof will become more readily apparent from a reading of the following description of certain embodiments thereof when made with reference to the accompanying drawing in which:

FIG. 1 is an elevational view partly in section diagrammatically illustrating essential portions of a sewing machine incorporating a mechanical vibrator according to the present invention.

FIG. 2 is a circuit diagram in a block form illustrating a preferred mode of a sewing method embodying the present invention;

FIGS. 3(A) and 3(B) are graphical representations illustrating (a) changes in the sewing load which are experienced in sewing machines and (b) a controlled amplitude of mechanical oscillations according to a preferred form of the method according to the invention;

FIG. 4 is a cross-sectional view diagrammatically illustrating a portion of the structure shown in FIG. 1 and a portion of the machine not shown in FIG. 1;

FIGS. 5 and 6 are side-elevational views diagrammatically illustrating cutting and welding/ marking tools, respectively, which may be additionally mounted on the machine according to the present invention.

[0011] Referring now to FIG. 1, a sewing machine according to the present invention may have a conventional basic structure and makes use of a needle 1 which is formed at a free end portion thereof with an aperture 1a having a thread (not shown) passed therethrough. The needle 1 is securely held by means of a chuck 2 to an end (lower) portion of a rod 3. The needle 1 is here supported coaxially with the rod 3 and may extend vertically, perpendicularly to a material 4, e.g. cloth, leather or paper, to be stitched. The rod 3 is supported by a pair of bearing assemblies 5 so as to be vertically movable up and down or capable of vertical reciprocation, and is held thereby against lateral movement and rotation. The rod 3 is vertically or axially reciprocated by a motor 6 via a crank 7 including a crankshaft 7a to which the output shaft of the motor 6 is drivingly coupled via a gear transmission (not shown) and a crank pin 7b secured to the rod 3. The needle 1 is thus axially reciprocated into and through the material 4 moving manually or otherwise relative to the axis of the needle 1 to stitch the material 4.

[0012] Shown secured to the upper end of the rod 3 is an electromechanical transducer 8 which is energized by a power supply unit 9 to impart high-frequency mechanical oscillations to the reciprocating needle 1 in its axial or longitudinal direction. The transducer 8 and the power supply unit 9 themselves are conventional in design and are commercially available. The power supply unit 9 is here mounted on a casing 10 secured to a frame 11 of the machine which has also the bearing assemblies 5 secured thereto. The transducer 8 is secured to the rod 3 by means of a bolt 12. The rod 3 is configured to serve as a horn for propagating and amplifying sonic or ultrasonic oscillatory signals produced in the transducer 8 to the needle 1. The motor 6 is accommodated on a suitable support within the casing 10.

[0013] It has been found that when high-frequency mechanical oscillations are imparted axially to the reciprocating needle 1, the needle 1 can penetrate into and through the material 4 with greater ease and smoothness in each cycle or reciprocation or each advancing stroke. Thus, stitching of any thick and/or hard sewable material 4 is facilitated.

[0014] The reciprocating needle 1, according to the present invention, is axially oscillated with an amplitude of the oscillations, for example, of 20um. This results in an oscillatory advancement of the needle 1 in each cycle of reciprocation in which an oscillation occurs each time the needle advances by a distance of 20 to 30 pm. During the advance stroke of each cycle of reciprocation, a plurality of oscillations should be experienced by the needle 1.

[0015] In this manner, the penetration of the needle 1 into and through the material 4 is greatly facilitated because of a significant reduction in the resistive friction of the material 4 against the penetrating needle 1. The rate of stitching can thus be increased and the possibility of accidental breakage of the needle 1 is also reduced.

[0016] In accordance with a further feature of the present invention, the mechanical oscillations imparted to the reciprocating needle 1 are imparted selectively during the advanced stroke of each cycle of needle reciprocation. Alternatively, the mechanical oscillations may be damped selectively during the retraction stroke of each cycle of needle reciprocation.

[0017] In FIG. 2 there is shown a circuit arrangement which enables such a modified mode of imparting mechanical oscillations to the reciprocating needle 1 to be executed. A sensor 12 is associated with the motor 6 to measure changes in the load of the crank 7 connected to the output of the motor 6. FIG. 3 shows in graph (A) how the load changes over the advance strokes (Ta) and retraction strokes (Tr) in the reciprocation of the needle through the material 4. The sensor 12 responsive to the changes in the load provides switching or control signals which act on the power supply 9 to actuate or increase the vibrational amplitude of the transducer 8 selectively during the advance stroke of each cycle of needle reciprocation. FIG. 3 (B) shows a resulting controlled mode of mechanical oscillations in which the reciprocating needle 1 is mechanically oscillated selectively during the advance stroke. Such a controlled mode is advantageous in that it achieves results substantially same as where the reciprocating needle 1 is oscillated over the entire cycles of reciprocation and at the same time significantly reduces noises produced by the needle oscillations. In FIG. 3 it is shown that the amplitude of mechanical vibrations is maximized when the needle 1 experiences the highest magnitude of load.

[0018] Alternative manners of sensing the changes in the load include provision of a strain gauge on an element in the crank 7 such as the crankshaft 7a to measure strains thereof.

[0019] According to still a further feature of the present invention, a sewing machine as described may have one or more additional functions of cutting, welding and marking sewable materials 4. To this end, referring back to FIG. 1 and also to FIG. 4, the casing 10 is securely carried by a collar 13 which is rotatably fitted onto a column 14. As shown in FIG. 4, the collar 14 is designed to carry further frames 15 and 16 by means of arms 17 and 18, respectively, which are both secured to the collar 13. The frames 15 and 16 are provided to carry sonic or ultrasonic cutting and welding/marking tools 19 and 20 as shown in FIGS. 5 and 6, respectively.

[0020] The cutting tool 19 shown in FIG. 5 comprises a cutter 21 having a cutting edge 21a and secured by means of of a bolt to holder 22 in the form of a horn at one end thereof which is of smaller cross- section.

[0021] The other (upper) end of the horn holder 22 has an electrochemical transducer 23 secured thereto by means of a bolt. The cutting tool 19 is supported in the frame 15 so as to be movable up and down and vertically positionable to locate the edge 21a in cutting relationship with the sewable or sewed material 4. The transducer 23 is energized by a power supply 24 (FIG. 4) to impart high-frequency mechanical oscillations to the edge 21a via the amplifier horn holder 22 to cut the material 4 which is moved along a desired cutting path.

[0022] The welding tool 20 in FIG. 6 may be used to weld pieces of thermoplastic resinous, sewable or sewed material(s) at its free end (lower) portion and is secured by means of a bolt to a horn holder 26 at one end thereof which has a smaller cross- section. The other (upper) end of the horn holder 26 here again has an electromechanical transducer 27 secured thereto by means of a bolt. The welding tool 20 is supported in the frame 16 so as to be movable up and down and vertically positionable to locate the shoe 25a in a welding relationship with two or more overlapped pieces of the sewed or sewable material(s) 4. The transducer 27 is energized by a power supply 28 (FIG. 4) to impart high-frequency mechanical oscillations to the shoe 25a via the amplifier horn 26 to weld the overlapped pieces together which may be moved along a desired welding path. A desired mark may be marked as well in this manner.

Claims

1. A sewing method using high-frequency oscillation wherein a needle carrying a thread is axially reciprocated into and through a sewable material moving relative to the axis of the needle to stitch the material, characterized by the step of imparting the high-frequency mechanical oscillations to the reciprocating needle (1) and substantially in a direction of the needle reciprocation.

2. The method defined in Claim 1 characterized in that said mechanical oscillations imparted to said reciprocating needle (1) are produced selectively during the advance stroke of each cycle of the needle reciprocation.

3. The method defined in Claim 1 characterized in that said mechanical oscillations imparted to said reciprocating needle (1) are intensified selectively during the advance stroke of each cycle of the needle reciprocation.

4. The method defined in any preceding claim, characterized by the step of sensing a load of said needle (1) experienced from said material during each cycle of the needle reciprocation and, in response to a change in the sensed load, automatically increasing the amplitude of said mechanical oscillations.

5. The method defined in Claim 4 characterized in that said amplitude of the mechanical oscillations is increased from a substantially nil value.

6. A sewing machine wherein a needle carrying a thread is axially reciprocated into and through a sewable material moving relative to the axis of the needle to stitch the material, the machine including means for imparting high-frequency mechanical oscillations characterized in that said high-frequency mechanical oscillations are applied to the reciprocating needle (1) substantially in a direction of the needle reciprocation.

7. The machine defined in Claim 6, characterized by means (12) associated with said means (6) for effecting said mechanical oscillations imparted to said reciprocating needle selectively during at least a time period in which said needle is advanced into and through said material (4) in each cycle of the needle reciprocation.

8. The machine defined in Claim 6, characterized by means associated with said means (12) for intensifying said mechanical oscillations imparted to said reciprocating needle selectively during at least a time period in which said needle (1) is advanced into and through said material in each cycle of the needle reciprocation.

9. The machine defined in Claim 6, characterized in that said means (8) comprises an' electromechanical transducer connectable in an oscillation transmitting relationship with said needle (1) and a power supply for energizing said electromechanical transducer (8) to impart said mechanical oscillations to said reciprocating needle (1).

10. The machine defined in Claim 9, characterized by sensing means (12) responsive to a load experienced by said needle (1) from said material (4) during each cycle of the needle reciprocation and control means responsive to an increase in said load for controlling said power supply to selectively produce or intensify said mechanical oscillations imparted to said needle selectively during at least a time period in which said needle is advanced into and through said material in each cycle of the needle reciprocation.

Ansprüche

1. Nähverfahren unter Verwendung von Hochfrequenzschwingungen, bei dem eine einen Faden haltende Nadel axial hin und her und dabei in einen sich relativ zur Nadelachse fortbewegenden nähbaren Werkstoff hinein- und durch ihn hindurchgeht, um ihn zu nähen, dadurch gekennzeichnet, daß die hin- und hergehende Nadel (1) im wesentlichen in Richtung ihrer Hin- und Herbewegung in hochfrequente mechanische Schwingungen versetzt wird.

2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die der hin- und hergehenden Nadel (1) aufgegebenen mechanischen Schwingungen in jedem Zyklus der Nadelbewegung während des Vorwärtshubs bzw. Einstichhubs erzeugt werden.

3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die der hin- und hergehenden Nadel (1) aufgegebenen mechanischen Schwingungen in jedem Zyklus der Nadelbewegung während des Vorwärtshubs bzw. Einstichhubs verstärkt werden.

4. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die vom Werkstoff herrührende Belastung der Nadel (1) während jedes Nadelzyklus gemessen wird und daß auf einer Änderung der gemessenen Belastung hin die Amplitude der mechanischen Schwingungen automatisch vergrößert wird.

5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß die Amplitude der mechanischen Schwingungen von fast Null an gesteigert wird.

6. Nähmaschine, bei der eine einen Faben haltende Nadel axial hin- und hergeht und dabei in einem sich relativ zur Nadelachse bewegenden nähbaren Werkstoff hinein- und durch ihn hindurchgeht, um ihn zu nähen, und die Einrichtungen zur Erzeugung von hochfrequenten mechanischen Schwingungen enthält, dadurch gekennzeichnet, daß die hochfrequenten mechanischen Schwingungen auf die hin- und hergehende Nadel (1) im wesentlichen in Richtung der Nadelbewegung aufgebracht sind.

7. Maschine nach Anspruch 6; gekennzeichnet durch eine Einrichtung (12'), die mit der Vorrichtung (8) zur Aufgabe der mechanischen Schwingungen auf die hin- und hergehende Nadel zusammenwirkt und die Schwingungen in jedem einzelnen Zyklus der Nadelbewegung während wenigstens des Zeitraums, in welchem die Nadel in den Werkstoff hinein- und durch ihn hindurchgestochen wird, erzeugt.

8. Maschine nach Anspruch 6, gekennzeichnet durch eine Einrichtung, die mit die Einrichtung (12'), welche die mechanischen Schwingungen in jedem einzelnen Zyklus der Nadelbewegung während wenigstens des Zeitraums, im welchem die Nadel (1) in den Werkstoff hinein- und durch ihn hindurchgestochen wird, auf die hin- und hergehende Nadel aufgibt, zusammenwirkt und diese Schwingungen verstärkt.

9. Maschine nach Anspruch 6, gekennzeichnet durch eine Einrichtung (8) zur Aufgabe mechanischer Schwingungen auf die hin- und hergehende Nadel (1), mit einem elektromagnetischen, schwingungsübertragend mit der Nadel (1) verbindbaren Wandler und mit einer Kraftquelle zum Antrieb des elektromagnetischen Wandlers (8).

10. Maschine nach Anspruch 9, gekennzeichnet durch einen Fühler (12'), der in jedem Zyklus der Nadelbewegung auf die vom Werkstoff (4) auf die Nadel (1) ausgeübte Belastung anspricht, und durch eine Steuervorrichtung, die während wenigstens des Zeitraums, in den die Nadel in jedem Zyklus der Nadelbewegung in den Werkstoff hinein- und durch ihn hindurchgestochen wird, auf einen Anstieg dieser Belastung anspricht und die Kraftquelle zwecks Erzeugung einer Verstärkung der der Nadel aufgegebenen mechanischen Schwingungen ansteuert.

Revendications

1. Procédé de couture utilisant des oscillations à haute fréquence selon lequel une aiguille tirant un fil est déplacée en sens axial de manière alternative dans et à travers une matière à coudre se déplaçant par rapport à l'axe de l'aiguille, pour coudre cette matière, caractérisé par l'opération consistant à imposer des oscillations mécaniques à haute fréquence à l'aiguille à mouvements alternés (1), substantiellement dans une direction des mouvements alternes de l'aiguille.

2. Procédé selon la revendication 1, caractérisé en ce que lesdites oscillations mécaniques imposées à ladite aiguille à mouvements alternés (1) sont produites sélectivement pendant la course d'avance de chaque cycle de l'aiguille à mouvements alternés.

3. Procédé selon la revendication 1, caractérisé en ce que lesdites oscillations mécaniques imposées à ladite aiguille à mouvements alternés (1) sont intensifiées sélectivement pendant la course d'avance de chaque cycle de l'aiguille à mouvements alternés.

4. Procédé selon l'une quelconque des revendications précédentes caractérisé par l'opération consistant à détecter une charge recontrée par l'aiguille (1) et due à ladite matière pendant chaque cycle des mouvements alternés de cette aiguille et à augmenter automatiquement l'amplitude desdits oscillations mécaniques en réponse à un changement de la charge détectée.

5. Procédé selon la revendication 4, caractérisé en ce que l'amplitude des oscillations mécaniques est augmentée à partir d'une valeur substantiellement nulle.

6. Machine à coudre dans laquelle une aiguille tirant un fil est déplacée en sens axial de manière alternative dans et à travers une matière à coudre se déplaçant par rapport à l'axe de l'aiguille, pour coudre cette matière, cette machine comprenant un moyen pour créer des oscillations mécaniques à haute fréquence, caractérisée en ce que lesdites oscillations mécaniques à haute fréquence sont appliquées à l'aiguille à mouvements alternés (1) substantiellement dans une direction des mouvements alternés de cette aiguille.

7. Machine selon la revendication 6, caractérisée par un moyen (12) associé audit moyen (6) pour appliquer sélectivement lesdites oscillations mécaniques imposées à ladite aiguille à mouvements alternes pendant au moins une période de temps au cours de laquelle ladite aiguille avance dans et à travers ladite matière (4) à chaque cycle des mouvements alternés de l'aiguille.

8. Machine selon la revendication 6, caractérisée par un moyen associé audit moyen (12) pour intensifier lesdites oscillations mécaniques imposées à ladite aiguille à mouvements alternés sélectivement pendant au moins une période de temps au cours de laquelle ladite aiguille (1) avance dans et à travers ladite matière à chaque cycle des mouvements alternés de l'aiguille.

9. Machine selon la revendication 6, caractérisée en ce que le moyen (8) comprend un transducteur électromécanique pouvant être accouplé à ladite aiguille (1) dans une relation de transmission d'oscillations et une source de puissance pour exciter ledit transducteur électromécanique (8) afin d'imposer lesdites oscillations mécaniques à ladite aiguille (1) à mouvements alternés.

10. Machine selon la revendication 9, caractérisée par un moyen de détection (12) sensible à une charge rencontrée par ladite aiguille (1) et due à ladite matière (4) pendant chaque cycle des mouvements alternés de l'aiguille et un moyen de contrôle sensible à une augmentation de ladite charge pour contrôler ladite source se puissance afin de produire sélectivement ou d'intensifier lesdites oscillations mécaniques imposées à ladite aiguille sélectivement pendant au moins une période de temps au corps de laquelle ladite aiguille avance et à travers ladite matière à chaque cycle des mouvements alternés de l'aiguille.

Drawing