EP0638682B1 - Embroidering machine with shuttles and yarn cutting device - Google Patents

Abstract

A shuttle-type embroidering machine possesses a yarn-cutting device (17) with knives (21) which are each guided by a guide element (25). A plurality of knives (21) and the associated guide elements are in each case formed on a knife rail (31) or combined to form a guide plate (25). The knife rails (31) and guide plates (25) are arranged on rails (33, 35) which are connected to one another in an articulated manner by means of the levers (39, 41) and which are displaceable relative to one another. For pivoting the levers (39, 41), a shaft (43) connected fixedly in terms of rotation to a lever (37) is provided. The lever (37) is articulated on the angle lever (39). As a result of the rotation of the shaft (43), the rails (33, 35), guided perpendicularly to their longitudinal extension, are displaced upwards and apart from one another. Furthermore, a slotted link (45) having a cam (49) cooperating with a fixed part (not shown) is provided on the shaft (43). As a result, during the rotation of the shaft (43), an advancing movement of the latter is simultaneously brought about. The yarn-cutting device makes it possible to cut the rear yarn without any additional clamping device.

Description

The present invention relates to a shuttle embroidery machine with shuttle tracks arranged on a profile, which are delimited on the fabric side by a stitch plate, and a thread cutting device for the rear thread with a knife, which can be positioned by a mechanism in front of the stitch plate for a cutting process.

When embroidering, the threads must be cut when changing color or repeat. For a long time, especially with shuttle embroidery machines, this was done manually, which of course is very labor intensive and expensive. In recent years, embroidery machines have become known that can automatically cut the back or bobbin thread. When implementing an automatic thread cutting device, the problem arises first of all that the space available for a thread cutting device in embroidery machines, in particular in large shuttle embroidery machines, is extremely scarce. In addition, when cutting a thread with a simple blade movement, the thread must first be clamped so that it cannot be pulled out of the shuttle. In addition, it is a requirement that the thread cutting device cuts the threads as close as possible to the embroidery site. Otherwise the embroidery pattern on the back of the textile would be impaired. In practice, a thread cutting device should also be as easy to maintain and robust as possible, not least because the embroidery machines are used today mainly in less industrialized countries. Maintenance should be effortlessly carried out by the machine operators there themselves.

The Swiss patent specification CH 660 608 discloses an embroidery machine in which a coupling is provided at each individual embroidery point in the drive train for the driver rod for the switching on and off of the respective embroidery point which can be influenced independently. When the respective embroidery site is stopped, the thread is behind the needle plate automatically cut by a thread cutter. This device has the disadvantage that a separate drive is assigned to each individual thread clamping and cutting device and this requires a large amount of space. For this reason, this device cannot be used on every shuttle embroidery machine. In addition, the thread previously clamped for cutting can be released again after cutting, so that damage to the latter can occur during further operation.

Another approach is presented in EP 0 541 923. There, a thread clamping and cutting device for the back or under thread of an embroidery machine is disclosed, which is arranged in the area of the stitch hole and also cuts the thread behind the stitch plate. The clamping gap of the thread clamping device is arranged in alignment with the cutting device. This device is characterized in that an intermediate plate with slot-shaped recesses is mounted on the throat plate, into which a guide part can be inserted. The guide part has an inner recess in which an actuating slide is slidably guided. The actuating slide itself has a U-shaped profile, in which the guide part engages with a projection, so that the actuating slide is guided. The actuating slide is screwed to an actuating rod which can be moved back and forth by a sliding drive. Two keyhole-shaped recesses are aligned in the U-profile, which are at the height of the stitch hole when embroidering. The lower boundary of the front keyhole-shaped recess is designed as a cutting edge. The counter knife is clipped in place in the guide part above the tap hole. The clamping gap is formed by a resiliently mounted clamping finger in the guide part and a counter-clamping piece inserted in the guide part. Due to the construction described, the thread is first clamped in the clamping gap during the cutting process and then cut. Another advantage is that the thread remains clamped in the clamping gap even after the actuating slide has been retracted, and only then is relieved by sufficient tension from the nip when re-stitching. The cutting and clamping device described also clamps the thread after the cutting process and is extremely space-saving. However, it is disadvantageous that the cutting and clamping device is relatively complex, complicated and therefore expensive. There is also the risk that the sliding mechanism is contaminated by external influences or by abrasion and this can lead to longer downtimes.

GB-A-12 185 (AD 1910) discloses a thread clamping and cutting device for the rear thread of a shuttle embroidery machine which is arranged during embroidery below the carrier rail which carries the shuttle and the associated drive. This device has a shaft which is rotatable and displaceable in the longitudinal direction. A crank is arranged on the shaft, which carries a rail which can extend along the entire embroidery machine. A plate is also attached to the rail, which has cutting surfaces on the upper edge. To cut the rear thread, the carrier rail with the shuttle is pulled back a little to create a space between the embroidered fabric and the needle plate. Then the shaft of the thread clamping and cutting device is shifted and rotated in the longitudinal direction, whereby the plate is pivoted in front of the needle plate and strikes it. During the upward movement, the plate hits the rear thread, clamps it onto the needle plate and cuts it off. What is special about this device is that the thread is clamped during the cutting process and remains clamped even after cutting so that it can be sewn on again. However, the device described has the disadvantage that it is not possible to cut the rear thread without prior clamping, since otherwise the thread would be pulled out of the shuttle by the simple knife movement. The needle hole cannot act as a counter knife, since the edges of the needle hole must be rounded in order to avoid inadvertent chafing or cutting off of the rear thread during embroidery.

It is an object of the present invention to provide an embroidery machine, in particular a shuttle embroidery machine, in which the disadvantages mentioned at the outset can be largely avoided and the thread can be cut off as directly as possible at the embroidery site. The cutting device should be robust, easily accessible, easy to service and insensitive to dirt. It would also be an advantage if embroidery or sewing machines already in use could also be inexpensively retrofitted with the cutting device.

According to the invention, this is achieved in that the knife has a guide element and that the mechanism ensures a relative movement of the knife and guide element for cutting the thread. The knife and the guide element virtually perform a scissor movement when cutting, i.e. the cutting surface of the knife crosses or intersects with an edge of the guide element. This type of cutting movement of the knife and guide element means that the thread is not stressed during cutting and there is no danger that it would be pulled out of the shuttle. For this reason, thread clamping can be dispensed with, e.g. is necessary if the thread is to be cut off at the tap hole (see GB-A-12 185). In contrast to DE-OS-2 065 264, no gripper is needed to grasp the thread to be cut. The solution according to the invention is therefore simple, robust and inexpensive. Another advantage is that the thread cutting device works independently, i.e. that these e.g. is not coupled with the decommissioning of boats as described in CH 660 608. As a result, the rear thread can be cut off without the associated shuttle being shut down for further operation at the same time. Moving the knife enables the thread to be cut in front of the stitch plate and close to the embroidery site.

An edge of the guide element is expediently designed as a cutting edge, which can interact with the cutting edge of the knife. Because the thread is cut by two intersecting cutting surfaces, thin ones can also be cut Threads of whatever material are reliably cut. The knives and the guide elements are advantageously detachably attached to rails. This is particularly advantageous because the actuating mechanism then only has to ensure a relative movement of the rails. As a result, a large number of knives can be actuated with just one drive, which considerably simplifies the construction. It is also advantageous if the knives and the guide elements are formed in blocks on a knife rail or. are combined into a guide plate. These can be changed quickly if necessary, for example to sharpen the cutting edges.

The knives are expediently connected to the mechanism in such a way that when the same is actuated, both a displacement of the knives along at least one axis and a relative movement of the same results. This can e.g. by means of a suitable eccentric device or a lever arrangement which positions the knives in front of the throat plate and at the same time ensures a scissor movement of the knives. The cutting device can be arranged below the angle profile or at another location on the embroidery machine.

The mechanism advantageously has at least one pivotable lever which connects the rails in an articulated manner. The two rails can be moved apart like scissors by the lever. Another advantageous construction provides that the rails are connected to one another by means of two levers arranged one behind the other, a lever which is articulated on one rail and an angle lever which is articulated at its angle on the other rail. The angle lever can have two arms of different lengths, so that a large lever effect can be generated. The actuating mechanism advantageously has a drive shaft which is connected in a rotationally fixed manner to a further lever. The free end of this lever is articulated to a lever already described above, which is required for the relative movement of the two rails. The rotation of the drive shaft can a vertical displacement of the rails can be effected at the same time.

In a preferred embodiment, in order to generate a feed movement, the drive shaft is connected in a rotationally fixed manner to a link having a curve, the link interacting with a stationary part. As a result, a translatory movement of the shaft can be generated simultaneously by a rotary movement. The knife can thus be moved when cutting onto the fabric stretched on the creel, and the thread can be cut off directly at the embroidery site. The backdrop is advantageously cylindrical and has a curved channel milled into the lateral surface. A stationary bolt can protrude into this channel, so that when the link is rotated it is moved in the longitudinal direction.

The knife expediently has a hook-shaped cutting edge which cooperates with the upper edge of the guide plate designed as a counter knife during thread cutting. Thanks to the two cutting edges, the thread can be cut cleanly. In another preferred embodiment, the knife has a straight cutting edge which is at an angle to the upper edge of the guide part. The angle between the cutting edge and the upper edge of the guide plate can be between approximately 4 and 45 °, preferably approximately 5 to 25 °. When using such an arrangement, the thread to be cut can be easily positioned under the cutting edge and the result is a scissor movement that promotes cutting. Another advantage is that the deflection of the knife needs to be less than e.g. when using hook-shaped cutting edges.

Guides are preferably provided on the guide plate, which connect the knife bar and the guide plate. This ensures tight guidance of the knives on the guide plates. In addition, the knives and the guide plates can be pretensioned, ie slightly curved. This feature ensures that the cutting edge of the knife the upper edge of the guide plate, which is designed as a counter knife, can interact optimally.

Fig.1

eine perspektivische Teilansicht der Schiffchenbahnen einer Stickmaschine mit einer Fadenschneideinrichtung, wobei letztere in zwei verschiedenen Positionen dargestellt ist,

Fig.2

einen Querschnitt durch die Schiffchenbahnen, die Fadenschneideinrichtung und den Schwingbalken der Stickmaschine, wobei die gestrichelten Linien die Fadenschneideinrichtung in der Schneidposition zeigen,

Fig.3

• a) und b) schematische Darstellung eines Betätigungsmechanismus zur Erzeugung einer Verschiebung und einer Scherenbewegung der Schienen,
• c) eine modifiziertes Ausführungsbeispiel,

Fig.4

• a) die Fadenschneideinrichtung der Fig.1 jedoch mit Messern mit einer ungefähr waagrechten Schneide,
• b) ein einzelnes Messer in vergrössertem Massstab.

Exemplary embodiments of the present invention will be described below with reference to the figures. It shows:

Fig. 1

2 shows a perspective partial view of the shuttle tracks of an embroidery machine with a thread cutting device, the latter being shown in two different positions,

Fig. 2

3 shows a cross section through the shuttle tracks, the thread cutting device and the oscillating beam of the embroidery machine, the dashed lines showing the thread cutting device in the cutting position,

Fig. 3

• a) and b) schematic representation of an actuating mechanism for generating a displacement and a scissor movement of the rails,
• c) a modified embodiment,

Fig. 4

• a) the thread cutting device of FIG. 1, however, with knives with an approximately horizontal cutting edge,
• b) a single knife on an enlarged scale.

Figures 1 and 2 show a thread cutting device 17 and upwardly projecting shuttle webs 13 of a shuttle embroidery machine. The shuttle tracks 13 are screwed to an angular profile 15, the so-called Stöcklilineal. At the front, the shuttle lanes 13 are each delimited by the throat plate 12. In the shuttle tracks 13, the shuttle 11 move up and down during the embroidery process. The boats 11 are held or driven by the driver nails 14, 16, which are arranged on the movable oscillating beam 18. During the embroidery process, the shuttle 11 are looped through the upper or front thread carried out, which is brought by means of the embroidery needle through the tap hole 20 in the shuttle 13.

Below the angle profile 15 is the thread cutting device 17 already mentioned, which is shown in FIG. 1 in two different positions. The representation at the edge of the drawing shows the thread cutting device 17 in the rest position; the other illustration shows the thread cutting device 17 in the cutting position. The cutting position is shown in dashed lines in FIG. As can be seen from FIGS. 1, 2, the cutting device can be displaced along two axes (arrows 58, 60). During embroidery, the thread cutting device 17 is in the rest position approximately in the plane of the needle plate 12. For thread cutting, the device in front of the needle plate 12 or. positioned on the embroidered fabric so that the thread can be cut as close as possible to the embroidery site.

The thread cutting device 17 comprises an actuating mechanism 19 and a plurality of knives 21 arranged at a distance from the stitch holes 20. As shown in FIG. 1, a plurality of knives 21 can be formed on a single sheet and form a knife rail 31 (FIG. 1). The knives 21 are guided by a guide plate 25. The guide plate 25 has punched-out ears 27 projecting from the surface, by means of which the shank of the knives 21 is guided in each case. A large number of knife rails 31 and guide plates 25 each work in pairs and are detachably fastened to rails 33, 35. The rails 33, 35 can be moved relative to one another by the mechanism 19 and can be positioned in front of the throat plate 12.

The knife rails 31 and guide plates 25 shown can be produced simply, for example by punching them out of a metal sheet. They advantageously consist of a thin spring steel sheet. The knives 21 run parallel to the shuttle tracks 13 and have a hook-shaped cutting edge 23. The upper edge 29 of the guide element 25 is also designed as a cutting edge, which is each provided with a knife 21 cooperates. The knife rails 31 and / or the guide plates 25 are expediently prestressed against one another, ie are slightly concave. This ensures that the cutting edges 23, 29 run closely together.

In contrast to the cutting device shown in FIG. 1, the knives 21 ′ according to FIG. 4 have approximately straight cutting edges 24 instead of the hook-shaped cutting edges 23, which are at a certain angle to the upper edges of the guide plates 25. This design of the cutting edges 24 has the advantage that the thread to be cut can be positioned particularly easily under the cutting edge 24. It has proven to be advantageous if the cutting edges 24 are at an angle between approximately 5 and 25 ° to the upper edge 29 of the guide plate 25.

As already mentioned above, the knives 21, 21 'can be positioned in front of the throat plate 12 for cutting. The structural details of a preferred embodiment, which can cause the displacement and the actual cutting movement of the knives, are discussed in more detail below.

To produce the cutting movement, the rails 33, 35 carrying the knife rails 31 and the guide plates 25 must be moved relative to one another in such a way that the cutting edges of the knives 21 and the upper edge 29 of the guide plate 25 can overlap. As can be seen from Figure 1, the knife rail 31 is releasably attached to the rail 35. The guide plate 25, however, is releasably attached to the rail 33. Furthermore, the rails 33, 35 are articulated to one another with two levers 39, 41. The lever 41 is articulated at one end to a pin 42 arranged on the rail 35. The lever 39 is designed as an angle lever and is articulated at an angle on a pin 40 of the rail 33. A pivoting of the angle lever 39 has the effect that the two rails 33, 35, which are perpendicular to their longitudinal extension (not shown), are deflected relative to one another (FIG. 1).

To actuate the lever 39, a drive shaft 43 is provided, which is connected in a rotationally fixed manner to a lever 37. The lever 37 is articulated on the angle lever 39 at the other end. By rotating the drive shaft 43, the guided rails 33, 35 are moved upward, as shown in FIG. This arrangement therefore has the advantage that not only is a relative movement of the rails 33, 35 produced by rotating the drive shaft 43, but they are simultaneously displaced a certain distance. As a result, the rails 33, 35 can be raised to approximately the height of the tap hole 20 (FIG. 1).

In order to move the cutting device 17, which in a preferred embodiment is in the plane of the throat plate 12 (FIG. 2) or behind it, in front of the throat plate 12, a cylindrical link 45 is provided. This is firmly connected to the drive shaft 43. A curved channel 49 is milled out in the lateral surface 47 of the backdrop 45. A fixed pin (not shown), which can be arranged on the profile 15, engages in this channel 49. When the drive shaft 43 rotates, a feed movement in the direction of arrow 44 (FIG. 1) is generated.

Further possible designs for generating the deflection of the rails 33, 35 and the relative movement thereof are shown schematically in FIG. 3. In a first example (FIGS. 3a and b), a straight lever 55 is articulated on the rail 33 approximately in the middle. One end of the lever 55 is guided in a slot 59 in the rail 35, the other end of the lever 55 is articulated on a lever 57. By pivoting the lever 57 about the lower, fixed pivot point, the rails 33, 35 are inevitably shifted upward. At the same time, the rails 33, 35 perform a scissor movement (FIG. 3b). The rails 33, 35 are guided by suitable means in such a way that they can only be displaced perpendicularly to their longitudinal extent.

3 c shows a further exemplary embodiment for generating the deflection of the rails 33, 35 and the cutting movement. In In this example, the lever 55 has a pin approximately in the middle, which is slidably guided in a slot 59 'in the rail 33. Furthermore, one end of the lever 55 is articulated on the rail 35, the other end on the lever 57. Analogously to the example of FIGS. 3 a, b, the rails 33, 35 can be deflected by pivoting the lever 57 and moved relative to one another.

The thread cutting works as follows: When the shaft 43 is rotated by drive means (not shown in more detail), the entire drive shaft 43 moves with the rails 33, 35 as a function of the curve 49 of the link 45 along its longitudinal axis (FIG. 1: arrow 44). At the same time, the rails 33, 35 are moved up and apart due to the lever arrangement 37, 39, 41. The movement of the rails 33, 35 takes place along the arrows 58, 60 (FIG. 2). The last part of the movement is only in one direction (vertical). During this last part of the movement, the rails 33, 35 move apart, so that the cutting edges 23 of the knives 21 are moved beyond the upper edge 29 of the guide plate 25, i.e. the scissors open (Figure 2: position shown in dashed lines). In this position, the knife 21 is located in front of the stitch plate 12 in the area of the stitch hole 20. To cut the thread, the gate with the stretched fabric is then moved so that the thread, which extends from the last embroidery point through the stitch hole 20 to the boat, comes to rest under the cutting edge 23. Then the link 45 is turned back until the cutting edges 23 and the edge 29 intersect and cut the thread (Fig. 2: movement of the rails against arrow 60). This cutting movement can be repeated by rotating the shaft 43 back and forth two or three times. This can ensure that all threads are cut.

By appropriately positioning the gate, the length of the thread to be cut can be selected so that it can just be re-stitched on, but after the stitching there is no annoying thread at the new embroidery site. This has the advantage of being an additional one Device for clamping the thread, as mentioned, for example, in the writings cited at the beginning, can be dispensed with.

Claims (15)

1. Shuttle embroidering machine comprising shuttle guideways located on a profile (15), said shuttle guideways bordering a stitch plate on the side facing the fabric, and thread cutter (17) for the back thread, said thread cutter comprising a knife (21) which for a cutting operation can be positioned by a mechanism (19) in front of the stitch plate, characterised in that the knife (21) comprises a guide element (25), and in that for cutting of the thread the mechanism (19) provides a relative motion between knife (21) and guide element (25).
2. Embroidering machine as in claim 1, characterised in that an edge (29) of the guide element (25) is formed as a cutting edge which cooperates whith the cutting edge (23) of the knife (21).
3. Embroidering machine as in claim 1 or 2, characterised in that the knife (21) and the guide elements (25) are removably fastened to rails (35, 33).
4. Embroidering machine as in one of the claims 1 to 3, characterised in that a plurality of knives (21) and guide elements are in form of a block on a knife bar (31) and combined to a guide plate (25), respectively.
5. Embroidering machine as in one of the claims 1 to 4, characterised in that the knives (21) are in such an operative relationship with the mechanism (19) that, on actuation of the mechanism, a movement of the knives (21) at least one along one axis (60) and a relative motion of said axis takes place.
6. Embroidering machine as in claim 5, characterised in that the mechanism comprises a tiltable lever (55) pivotally connecting the rails (33, 35).
7. Embroidering machine as in one of the claims 5 or 6, characterised in that the rails (33, 35) are connected by two levers (41, 39) connected in series, one lever (41) being pivotally connected to one rail (35), and a bell crank (39) being pivotally connected at its bend to the other rail (33).
8. Embroidering machine as in one of the claims 5 to 7, characterised in that the actuating mechanism (19) comprises a drive shaft (43) rigidly connected to a lever (57) which with its other end is pivotally connected to the lever (39, 55).
9. Embroidering machine as in one of the claims 5 to 8, characterised in that for generating a feed motion the drive shaft (43) is rigidly connected to a cam (45) comprising a curve (49), and in that the cam (45) cooperates with a stationary part.
10. Embroidering machine as in claim 9, characterised in that the cam (45) is cylindrical and comprises in its mantle a curved channel (49) into which a stationary stud (51) protrudes.
11. Embroidering machine as in one of the claims 1 to 10, characterised in that the knive (21) has a hook-like cutting edge (23).
12. Embroidering machine as in one of the claims 1 to 11, characterised in that the knife (21) has a straight cutting edge (24) which is arranged at an angle to the upper edge (29).
13. Embroidering machine as in one of the claims 4 to 12, characterised in that guide members (27) are provided at the guide plate (25), said guide members (27) slidably connecting the knive bar (31) with the guide plate (25).
14. Embroidering machine as in one of the claims 4 to 13, characterised in that the knive bar (31) and the guide plate (25) are biased together.
15. Embroidering machine as in one of the claims 1 to 14, characterised in that the thread cutter (17) is mounted on the profile (15).

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