DE479945C - Buttonhole sewing machine with a device for opening the fabric clamp and a device located underneath the fabric for severing the needle thread - Google Patents

Description

Buttonhole sewing machine with a device for opening the fabric clamp and a device located beneath the fabric for severing the needle thread The invention relates to 1 # sewing machines and in particular to buttonhole sewing machines, which are provided with a device by means of which the threads and the gimp between the buttonhole sewing periods can be separated and controlled.

According to the invention, the upper and lower threads as well as the Gimp underneath the fabric severed and any obstructions on the fabric clamping plates and upper clamp feet eliminated, so that the fabric clamp itself is simple in shape can be made, which is a blockage of the free plan view of the fabric at precludes its attachment to the fabric clamp before starting the machine.

According to the invention devices for handling the thread are provided, to avoid and guarantee the formation of skipped stitches at the beginning of the sewing work, that the sewing process can be started in the required manner.

It is for the stated purpose with the automatic buttonhole sewing machine according to the invention only necessary to lead the fabric into the open fabric clamp and depress the start button; the machine then works automatically to close the cloth clamp, cut and sew the buttonhole and all Separate the threads and the gimp underneath the fabric close to the last stitch, whereupon the fabric clamp is opened so that the fabric is removed from the machine the buttonhole completely finished and no subsequent one it is necessary to trim the ends of the sewing threads and the gimp again.

For the stated purpose is in conjunction with the below the cloth clamp located device for cutting all threads and the gimp close to that last stitch a puller is provided that on the needle thread between the needle and the fabric acts independently of the fabric clamp, and during the Fabric is clamped and under control, a needle thread end of measured and of sufficient length below the eye of the needle to enable proper start-up the next sewing process is guaranteed without the needle being able to unthread or skipped stitches occur and, without it being necessary to provide a device, by means of which the beginning end of the sewing thread is clamped, while the first Stitches are sewn, or around the beginning thread end or thread ends again having to prune.

To make it easier for the puller in some cases, pulling the needle thread down through the eye of the needle can be done with this Pulling device a device for loosening the needle thread are combined, which at the end of the Stitch formation circuit between the tensioning device and the supply spool acts to draw loose thread from the spool and thereby to avoid an unfavorable stress on the thread when it is pulled through the eye of the needle. A device for releasing the needle thread tension is also preferably used.

In some cases it may be desirable to retract the device of the needle thread to be provided between the tensioning device and the needle, so that at times the needle thread end is shortened sufficiently to avoid this The thread end is accidentally clamped by the upper clamp feet when the fabric clamp is closed. It should be noted, however, that this device can be retracted of the thread is not essential and is only provided in those cases where the end of the needle thread can possibly be caught by the fabric clamp.

Furthermore, a device is used to adjust the lower thread tension between sewing periods and before the thread and gimp are severed, so that the bobbin thread is relieved of stresses when it is cut, whereby a recoil of the lower thread due to its elasticity and therefore a possible Avoid unthreading the bobbin thread.

In the drawings, one embodiment of the invention is for example shown, namely Fig. i is a right side view of a buttonhole sewing machine according to the invention. Fig. A is a left side view of the machine, and Fig. 3 is a detailed view of the tension release device shown in FIG. Fig. 4 is a front end view of the lower part of the machine, Fig. 5 is a Top view of the machine from below, Figure 6 is a section along line 6-6 of Fig. 5.

FIG. 7 is a rear elevational view of that shown in FIG Parts, and fig ,. 8 is a section on line 8-8 of FIG. 6.

Figure 9 is a top plan view of the washer and device to cut the thread in the thread trimming position.

Figure 10 is a top plan view of the rear left corner of the fabric clamp.

Fig. I i is a bottom plan view of a portion of the fabric clamp.

Fig. 12 is a front elevational view of the needle thread puller and the thread cutting knife in the position that these parts during the sewing process take in.

Figure 13 is a similar view at the end of a sewing operation and illustrates the movement of the puller to grasp the loading thread.

Fig. 1q. is a similar view and illustrates how the needle thread is withdrawn by the retraction of the puller before the line cutting knife from the position shown by the full lines to that shown by the dashed lines Lines indicated position advances.

FIG. 15 is a rear elevational view of that shown in FIG Parts.

Figs. 16 and 17 are individual views of the puller, and Fig. Fig. 18 is a top plan view of the puller and its moving device from underneath.

In the illustrated embodiment, i denotes the hollow foot a buttonhole sewing machine, from which the stand a of the overhanging machine arm 3 extends upwards, which in the head q. expires.

The stitch-forming device is of the usual type and has an upper one straight needle 5 piercing the fabric and a lower curved needle 6 passing through goes through the buttonhole. The needle 5 is going up and down from the Needle bar 7 carried, while the bow needle 6 from the usual attachment disk 8 is carried, with the needle bar and the attachment disk the usual rotary movements transmitted through the interconnected upper and lower sector drives 9, 1o that together by the usual connections with the in the feed disc 12 existing cam groove i z (Fig. 5) can be moved. This device works to the stitch-forming devices while sewing one or both ends of the buttonhole in one direction and the stitch-forming devices turn back between sewing periods to return them to the starting position. The stitch-forming device is driven by the machine drive shaft 13, which also the feed disk 12 during the sewing process through mediation the usual pin and star wheel drive 1q. (Fig. 5) and the usual wheels 15 gradually propels.

The cloth clamp can be moved and is first quickly over the Foot i moved away to move the fabric from the buttonhole position to the sewing position to demonstrate; then the cloth clamp is moved a little more slowly and gradually, to attach the stitches around the buttonhole, whereupon they quickly in the buttonhole cutting position is returned. The cloth clamp has the lower one Stoffklemmpdatten-r6 and the upper clamping feet 17, which are in clamping position with reference on the fabric by an oscillating motion of the interconnected oscillating shaft parts 18 are depressed, to one of which an arm i9 (Fig. I) is connected, the can be depressed by the usual lever 2o that closes the clamp, which at the beginning of a buttonhole production cycle by = a cam groove 2i is moved in the constantly rotating disc 22, which in turn is coaxial to the buttonhole cutting shaft 23 lies. A sliding pin 24 that protrudes from the rearward Arm 25 of the clamp closing lever 2o is carried for one rotation the disc 22 enter the cam groove 21, whereupon it is ejected and in the ejected Position is locked.

The cloth clamping plates 16 are supported by the transverse slide plate 26 carried, which in turn is carried by the longitudinal sliding frame 27, the movement through a handlebar connection 28 with the longitudinal feed lever 29 be granted, which has a driven member 3ö, which is in the feed cam groove 31 of the feed disk 12 is working. When the machine is used to sew a straight buttonhole to differ from a buttonhole provided with an eye, so it is not necessary to move the sliding plate 26 with respect to the sliding frame 27, so that the mentioned plate and the frame are always stationary with respect to one another can be held.

The rapid advance of the fabric clamp from the buttonhole cutting position into the sewing position and its return movement are carried out by the usual continuously running, fast feed drive shaft 32 (Fig. 5), which by means of a screw and a worm gear train 33, the driving part 34 of a Clutch drives the driven member 35 of which is fixed on the transverse shaft 36 sits, which in turn by a bevel gear 37 with the gear ratio i : i drives the feed disk 12. By withdrawing the cone -38 from that driven coupling members 35 is the engagement of the driving and driven coupling members while caused by the advancement of the cone 38 on the = driven coupling member 35 to uncouple the parts 35 and 34 is brought about. The cone 38 is through the usual coupling arm 39 on the longitudinal slidable rod 40 (Fig. 6) moves the side pin 41 and after arm protruding below .4 = carries.

In the foot i on the bearing block 43 (Fig.5) there is a constantly swinging out Angle lever 44 45 (Fig. 5 and 6), whose forked arm 45 the crank 146 includes on the fast feed shaft 32. There is a single back and forth on arm 44 Articulated forward rod 4.7, at the free end of which a spring 48 engages (Fig. 6 and 7) which push the rod 47 upwards against a seat 49 of a pawl 5o (Fig. 8) pulls, which is pivotably mounted at 51 on the foot i. The rod 47 is ineffective back and forth when it is held down by the latch 5o. If but the pawl 5o is withdrawn to release the rod 47, the latter becomes pulled up by spring 48 and shoulder 52 now engages with the pin 41 and pushes the slide rod 4o to the right (Fig. 6), around the cone 38 to withdraw from the coupling members 34, 35 and the coupling of the fast To bring about feed shaft 32 with the transverse shaft 36, so that the feed disk 12 is driven quickly. When the rod 40 is pushed into the coupling position, it becomes due to the engagement of the shoulder 53 of the lever 54 with the lower one End of arm 42 held on rod 40 in this position. The arm 54 is on the Screw 55 (Fig. 7) mounted so that it can swing, which is coaxial with the screw pin 56 for the angle lever 44, 45 runs, and on the. Arm 54 grips one end a spring 57, the other end of which is attached at 58 to the hub of the arm 39. The lever 54 and shoulder 53 thus act as a spring pawl around the slide bar 40 to keep the clutch engaging position. During the return movement of the Rod 47 comes the inclined shoulder 59 (Fig. 6) with the pin 41 and engages causes the rod 47 is depressed enough to be in the ineffective Position to be detected again by the pawl 5o.

The usual removable sample disk 6o sits on the transverse shaft 36, which controls the starting and stopping device by means of the lever 61 and the handlebar 62, to regulate the duration of the effect of the stitch-forming device. The disk 6o carries the usual trigger tips 63, which swing out the lever 64 (Fig. 2) and that Control the disengagement of the fast drive for the feed disk 12. The lever 64 is forked at its rear end (Fig. 2) and encompasses end 65 of the lever 54. Therefore, when the lever 64 is swung out by one of the trigger tips 63, so the lever 54 is depressed and the arm 42 and the sliding pole 40 released, whereupon the spring 66 (Fig. 5) acts directly on the rod 40 to move into their clutch-releasing position. The control device for the start of the fast feed before and after the sewing process includes the Rocker shaft 67 which has an arm 68 (Fig. 2) which engages with the pawl 5o stands; another arm 69 can through a control tip 7o on the clutch disc 71 are depressed while a third arm 72 is raised by the lever 73 can be, which in turn is moved by the storage device S.

The machine of the invention is of the type that cuts the buttonhole slot prior to sewing. The buttonhole cutting device has the displaceable knife lever 74, 75, which the usual forward movements as well as the vibration and. Opening movements. Control disks are given on the knife shaft 23, which in turn is given a single rotation before sewing by the continuously rotating disk 22, which comes into effect through a coupling that allows a single rotation. A control cam 76 (Fig. I) seated on the knife shaft 23 acts on a T-shaped lever 77 after the buttonhole has been cut in order to bring the nose 78 of this lever into operative engagement with the usual clamp-spreading device 79 . The fabric clamp is opened by the action of a tooth 8o on the sample disk 6o and the clamping jaws are laterally fed to one another; the tooth 8o lifts the roller 8 1 on the lever 82 which is pivotably mounted at 83 on the foot i. The lever 82 is connected by the link 82 'to the lever 84 (FIG. 2), which is pivotably mounted at 85 on the stand 2. When the lever 84 is swung out by the lever 82, it strikes the front end of the rod 85 'which is attached to it. 86 is articulated, on the usual and the clamp-opening arm 87. The rod 85 'carries the usual projecting arm 88 (Fig. 2), which abuts on the lever 89 canceling the spreading action of the clamp.

The machine is equipped with a device to cut all threads and the gimp underneath the fabric close to the last stitch; this device comprises a scissors-like cutting knife 9i (Fig. 4) carried by the lever 92, which is pivotably mounted at 93 and moved by the link 94 with the lever 95, which in turn is mounted at 96 (Dep. i) and is controlled by the cam groove 97 of the wheel 37. The cam groove 97 has a hump -98 at one point of its working cycle, and this hump is timed so that it advances and retracts the scissors 9 i after the sewing of the buttonhole has been completed and the fabric clamp has been returned to the buttonhole cutting position, but before the cloth clamp has been opened. The scissors gi carry a clamp 99, ioo for the superfluous needle thread loop; of this clamp, the jaw ioo has an oblique outer edge ioi (Fig. 9) which comes into engagement with the post io2 of the attachment disk 8 when the scissors gi are advanced into the position cutting the thread. When the scissors gi and the clamp 99, ioo are withdrawn, the inclined surface 103 (_, # ibb. 9) on the tail of the jaw ioo comes into engagement with the stationary bearing block 104 (Figs. 2 and 4), whereby the clamp opened and the unnecessary needle thread loop is released. The tail of the clamp ioo carries a leaf spring io5 (Fig. G) which presses with friction on the tail of the jaw 99; the spring io5 has a transverse rib io6 which engages over the opposing edges 107 of the tail of the jaw 99 to hold the jaw ioo in either the fully open or closed position. The movable scissor blade is moved by the pin io8, which sits on the clamp and cooperates with a cam groove iog in the stationary plate iio.

The machine of the invention has no device on the upper clamp feet to separate and hold the needle thread. To ensure that the The end of the needle thread hanging from the needle at the beginning of a sewing job is sufficient is long to ensure the correct formation of the first stitches is a new shape a needle thread puller provided. This puller is complete formed independently of the cloth clamp and arbefet to a measured amount thread through the eye of the needle before pulling the fabric through the fabric clamp is released so that the amount of needle thread is under control, and before the The threads and the gimp underneath the fabric are severed.

The thread pulling device preferably has the shape of an angle lever i i i, i i i 'on, .der at i i2 on the bearing block i i3 (Fig.2) mounted to swing is, which in turn is attached to the stationary bearing pin 114 for the sector drive 9 is; the bearing pin 114 is carried by the overhanging machine arm 3. The arm i i i has at its lower end one with the Thread in Engagement occurring hook i 15, the tip i 16 of which is bent forward, so that it is at an angle to the plane of action of the actual hook. .

On the arm. iii 'of the pulling device, a short upright arm 118 is articulated at 117, to which one end of a spring i 19 is connected, the other end of which engages on the arm iii. The spring ii 9 resiliently holds the arm on a stop pin i2o (Fig. 14). The arm 118 lies in the movement path of the control block 121 on the underside of the sector drive 9. The block 121 has an inclined surface 122, which is followed by a sharp shoulder 123. During the oscillation of the sector drive 9 in one direction (FIG. 2), the block i2i only tilts the arm i i8 away from the stop pin 12o, the spring i i9 being tensioned at the same time. After the control block i2i has passed the arm i 18, the spring i 19 returns the arm 118 to its upright position, which is shown in Fig. R 3 by the solid lines. During the oscillation of the sector drive 9 in the opposite direction, the inclined surface 122 of the control block 121 presses the arms 118 and i ii 'downwards, whereby the arm iii is displaced into the position indicated by the dashed lines in Figure 13, in which it transversely to the course of the needle thread t - which at this time extends downwards and backwards from the eye of the needle towards the last stitch (Fig. 17), the fabric moving from the sewing position to the buttonhole cutting position due to the rapid advance of the fabric clamp has been led behind. As soon as the sharp shoulder 123 passes the arm 118, the spring 12 on the bearing pin i 12 of the extraction lever iii, iii 'moves the latter from the position shown in Fig. 13 by the dashed lines to that shown in Fig. 14 by the solid lines indicated position during which movement the hook i 15 grasps the needle thread t and pulls a measured amount of the thread through the eye of the needle. The scissors 9i are then pushed forward into the dashed position (Fig. 14) in order to separate the upper and lower threads as well as the gimp, whereupon the fabric clamp is opened to release the fabric.

In order to avoid stressing the needle and the thread, it is preferable to provide a device for releasing the usual needle thread tensioning device and a device on the feed side of the tensioning device by means of which the needle thread coming from the supply bobbin is loosened. The device for loosening the thread comprises an angle lever 12.5 (Fig. 2), the short arm of which is connected to the upper end of a lever 127 by a link 126. which is mounted at 128 on the machine arm 3 such that it can oscillate. A downwardly extending arm 130 is supported at 129 at the lower end of the lever 127 and is usually held in engagement with the stop pin 131 by the spring 132. A drive block 133 is mounted on the sliding frame 27 of the fabric clamp and can easily go under the arm 130 when the fabric clamp is moved forwards. The block 133 is arranged, however, so that its rear end engages the arm 130 when the fabric clamp is moved back when the last stitches are sewn and the lower end of the lever 127 pushes backwards, so that the long arm of the angle lever 125 into the by the dashed lines (Fig. 2) indicated position is moved down, whereupon the block 133 releases the arm 130 at the beginning of the rapid advance of the fabric clamp in the initial or buttonhole cutting position, whereupon finally the spring 134, which with one end engages the lever 12.7 and is connected with its other end 135 to the machine frame, the lever 125 producing the thread loosening returns to its initial position, which is shown by the solid lines. A thread loosening is thus produced directly next to the tensioning device 136 at the end of a sewing process.

The release of the tensioning device 136 occurs during the rapid Feed movement of the fabric clamp from the sewing position to the buttonhole cutting position. There is one at the rear left corner of the slide frame 27 of the cloth clamp longitudinally adjustable plate 137 with its outer rear corner at 138 is beveled. The return movement of the cloth clamp from that shown in Fig. Fo through the The position indicated by the broken lines in the position shown by the solid lines Position leads the inclined surface 138 against the lower end of the tension release lever 139 and pushes this end outwards. The lever 139 (Fig.3) is between his Ends at 14o on the bearing block 141 which is attached to the machine arm 3 is. An outward movement of the lower end of this lever has the consequence that the adjustable knob 142 attached to the upper end of the lever the usual release pin 143 of the tensioning device 136 is pressed. the Spring 144 resiliently urges lever 139 into its tension-restoring position Location; this effect takes place, when the cloth clamp quickly goes from the buttonhole cutting position to the sewing position at the beginning of a buttonhole production cycle is moved.

In the illustrated embodiment, a measured one is preferably used Amount of needle thread pulled back through the eye of the needle, so that the needle thread end there is no danger of being jammed under the clamping feet if the latter is conclude. For the stated purpose is at the front end of the clamp closing Lever 2o a two-part rod 145 of adjustable length rotatably attached, which works in a guide 146 which is attached to the machine arm 3. the Both parts of the rod 145 are held together by the clamp 147. The top The end of the rod 45 has a lateral extension 1 ¢ 8 (Fig.2), which the needle thread overlaps which of the stationary guide pin 149 to the upper end of the hollow needle bar 7 goes. When the lever 2o closing the clamp is moved, so he pulls the rod 145 down and causes its upper end 148 comes into engagement with the needle thread and the thread end located under the eye of the needle shortened. To ensure that the needle thread is retained in the hook 115 so that the shortened 'thread end on one side and outside the area the clamp feet is held, is a light leaf spring 151 by means of the screw 152 '(Fig. 17) attached to the pull-off lever I i i. This spring 151 pushes lightly on the thread located in the hook 115 and holds the thread end in the hook back while it is shortened. The spring 151 is intentionally made light, in order to be able to hold the thread end after the stitch-forming device has started has been set so that the thread end during the first descent of the needle is pulled out of the hook, but after that created by the puller Loosening produced below the eye of the needle as a result of the decline of the needle 6 has been. The length of the thread end is here such that the latter depends on the starting stitches is recorded.

The tensioning device for the bobbin thread 152 (fig. I and q.) Is of conventional design and has a pair of spring-loaded washers, between which the bobbin thread passes away on its way to the lower needle 6. While During the sewing process, these discs exert tension on the bobbin thread. After this the sewing process is finished, and when the fast feed movement of the fabric clamp takes place in the buttonhole cutting position, the inclined edge 153 (Fig. ii) the control plate 15 ¢ when moving from that indicated by the dashed lines Position engaged in the position illustrated by the solid lines with the tail 155 of the tension release lever 156 and shifts the latter off the dashed position to the extended position (Fig. i i), whereby the lower End 157 of lever 156 between the discs of tensioning device 152 (Fig. i) brought and tension on the bobbin thread before cutting the thread and the gimp is lifted.

Claims (7)

PATENT CLAIMS: i. Knapflochstähmaschine with a device for opening the fabric clamp and a device located below the fabric for severing the needle thread, characterized in that a thread pulling device located above the fabric, which comes into effect before opening the fabric clamp, is used. pull the needle thread down through the eye of the needle. 2. Sewing machine according to claim i, characterized in that one of the machine arm = carried pull lever is moved so that it pulls the needle thread down through the Pulls the eye of the needle through it before the needle thread is severed. 3. Sewing machine after Claim i, in which the stitch-forming device rotates and during the sewing process is rotated back between the sewing periods, characterized in that the puller is moved by the device which rotates the stitch forming device. ¢. sewing machine according to claim i with a needle thread tensioning device, characterized in that that a second puller on the feed side of the tensioning device is provided and is used to produce a loose needle thread, the Tensioning device is released before the action of the first puller. 5. Sewing machine according to claim i, characterized in that a device is provided is in order to shorten the needle thread end a measured amount of needle thread to be withdrawn so that it cannot be grasped by the fabric clamp when the latter is closed at the beginning of the next buttonhole production cycle. 6. Sewing machine according to claim q., thereby marked that the between the Needle thread supply source and the tensioning device arranged, the thread loosening producing lever (r25) when moving the fabric clamp through a block (i33) is swung out, which acts on an arm (13o), which on a lever (r27) is mounted, which in turn is connected to the lever (i25) that produces the thread loosening. is articulated so that the latter pulls off the thread, and that the arm (13o) through it a spring (r34) returned to its initial position and the thread loosening producing lever is also returned to the initial position. 7. Sewing machine according to claim i, wherein the cloth clamp from the buttonhole cutting position to the Sewing position is moved and returned to said cutting position, thereby indicates that the needle thread puller is independent above the fabric is mounted by the cloth clamp so that it has a fixed trajectory next to it of the needle, such that the distance between the needle and the fabric of the needle thread is brought into the range of action of the puller when the fabric clamp is returned from the sewing position to the buttonhole cutting position will.