DE2526694A1 - THREAD RETRACTION MECHANISM - Google Patents

Description

BOEHMERT & BOEHMERT

LEGAL FIRM

Boehmert & Boehmert. D-2800 Bremen 1st post office box

To the

German Patent Office

8 Munich PATENT ADVOCATE DR.-ING.KARL BOEHMERT (1933-1973) PATENT Attorney DIPL.-ING. ALBERT BOEHMERT. BREMEN PATENT ADVOCATE DR.-ING. WALTER HOORMANN. BREMEN PATENT Attorney DIPL.-PHYS.DR. HEINZ GODDAR.BREMEN PATENT Attorney DIPL.-ING.EDMUND F.EITNER.MUNICH

LAWYER WILHELM J. H. STAHLBERG. BREMEN

Your sign
Your ret

New registration

Your letter from Your letter

Our mark Ourref.

C Bremen.
Feldstrasse 24

June 14, 1975

CLINTON INDUSTRIES, INC., 55 S. Newman Street, Hackensack, N.J., u. S.A. 07601 (V.St.A.)

Thread withdrawal mechanism

The invention relates generally to an improvement Sewing machines and in particular a thread retraction mechanism for a sewing machine with a needle that moves on a path between a raised and a lowered

Office Bremen: D-2800 Bremen 1 Postfach 786, Feidstrasse Telephone: (0421) * 74044 Telex: 244958 bopatd Telegr.: Diagram, Bremen

609809/0658

Bremen accounts: Bremer Bank, Bremen (BLZ 29080010) 1001449

PSchA Hamburg

(BLZ 20010020) 126083-202 Munich office: D-8000 Munich 90 Schlotthauer Straße 3

Telephone: (089) 652321 Teiegr. : Telepatent, Munich

BOEHMERT & BOEHMERT

lowered position can be moved back and forth. The thread retraction mechanism is used to follow the To create a row of stitches or a seam to pull the cut thread away from the path of the sewing material.

For industrial sewing work it is for reasons of the greatest possible cost-effectiveness and the highest degree of efficiency necessary to reduce the number of time-consuming, manual operations to a minimum. To this One of the normally hand-performed and highly time-consuming operations is the removal of the clipped Thread from the path of a sewing material following the completion of a sewing process to the unhindered To facilitate the execution of the following sewing process.

Numerous thread pull-back mechanisms to carry out this thread pull-away process has already been proposed and is available; however, these have numerous Disadvantages and shortcomings. These are complex and unreliable devices that difficult to attach to a conventional sewing machine without disturbing its work, and little are adaptable and versatile and also leave many requirements unfulfilled.

The invention has for its object to provide an improved mechanism for a sewing machine and in particular one to create an improved thread retraction mechanism for a sewing machine.

Another object of the invention is to provide an improved thread retracting mechanism for a sewing machine, which at the end of a sewing process can pull the severed thread away from the path of the sewing material.

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Another object of the invention is to provide a mechanism of the type mentioned, which is characterized by reliability, Robustness, simplicity, ease of use and high versatility and adaptability excels.

This task is performed with a pad retraction mechanism of the type mentioned solved by a picker element with a hook, which has a rearwardly directed opening, and a drive device which is arranged behind and above the needle path and the picker element carries so that they can lower this one after the other to the needle path, can pivot back and forth so that the Hook the lladelbahn is crossed back and forth, and then pull it back and lift over the path of the tip of the needle.

In a preferred embodiment of the pad retraction mechanism according to the invention, the drive device comprises the drive device a pair of parallel, vertically extending, laterally spaced side arms in which a first guide slot and a second guide slot are formed which have parallel, upper sections, wherein the first guide slot has a control path forming, lower portion, the one Forms an angle with the top section, a slider between the side arms, a transverse axis, which is mounted in the slider, a crank arm mounted on the axis, which carries a first pole roller, the is in engagement with the first Pührungsschlitz, a second pole roller, which is arranged on the slider and engaging the second guide slot and means for reciprocating the slide along it the side arms, the picker element having an arm which extends radially from the axis and in the

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2576694

Hook ends. *

The thread retracting mechanism of the invention is extremely reliable, simple, robust, easy to attach and to use as well as extremely versatile and adaptable .

The invention is thus a thread retraction mechanism for a sewing machine with a pair of perpendicular, parallel guide arms, the positioned behind and above the path of the tip of a reciprocating needle, one the guide arm has a straight, first slot and the other guide arm has a slot which has an upper section parallel to the first slot and an angled lower section. A The slide, which can be reciprocated by a pneumatic cylinder, is arranged between the guide arms and carries a first follower roller, which is in engagement with the first slot, and a transverse, reciprocating axis, which is provided with a crank arm that carries a second follower roller, which with engages the second slot. A picker arm extends radially from the axis and ends in a hook, when lowering and lifting the slider downwards, crossing the needle track forwards and backwards and then moved back up.

Further objects, advantages and features of the invention emerge from the following description of an exemplary embodiment of the invention in conjunction with the drawings. Show it:

Fig. 1 is a perspective front view of a head of a sewing machine, which is equipped with an inventive

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proper thread retraction mechanism is provided;

Pig. 2 is a fragmentary end view showing the thread retraction mechanism in retracted Position shows;

3 is a view similar to FIG. 2 showing the

Shows thread retraction mechanism in the extended position;

4 is a perspective view of the thread retraction mechanism in a disassembled state; and

Figure 5 is a partially rear view of the assembled suture retraction mechanism on average.

Reference will now be made to the drawings which show a preferred embodiment of the invention. In the drawings, the reference numeral 10 denotes as a whole the new thread retraction mechanism, which is attached to a conventionally constructed head 11 is attached to a sewing machine. The head 11 comprises at its outer end a needle that can be reciprocated in a vertical direction. Immediately behind the needle 13 is a tiltable sewing foot 15 mounted on a rod 14. The presser foot is together with the rod 14 in a known manner between a raised and a lowered position movable in the vertical direction. The head 11 has conventional Thread tensioning and guiding devices, drive mechanisms, Thread dispenser and the like. The rod 14 is seated in another sleeve 16 such that it can slide in the axial direction.

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BOEHMERT & BOEHMERT

The suture retraction mechanism 10 includes a mounting block 17 in the form of a slotted flange with a longitudinal bore in which the sleeve 16 sits. The mounting block is firmly attached to the sleeve by means of a clamping screw 17 'tensioned, which goes through axially aligned, transverse bores in the arms of the mounting block 17 in the form of a slotted flange. One one of the holes is threaded and the other hole is drilled out smooth. Two parallel, laterally spaced, rearwardly and upwardly inclined side arms 18 and 19 point at their lower ones Ends facing forward fingers 20, which are screwed to the side surfaces of the mounting block 17 by means of screws 21. A cross piece 22, the one has central, vertically extending threaded hole 23, runs between the upper ends of the side arms 18 and 19 and is by means of a screwdriver! 24 attached to this. In the side arm 19, a central, longitudinally extending, straight guide slot 26 is formed, and a longitudinal control slot 27 is formed in the side arm 18, which has a straight central one Section 28 comprises, which at its lower end in a short, downwardly and rearwardly inclined section 29 transforms.

A linear drive 231 in the form of a compressed air cylinder is shown with a return spring, although other types of drives may be used, includes one Cylinder 33 which is provided at its inner end with an axial threaded bushing 34 which is firmly inserted into the threaded bore 23 of the crosspiece is screwed in. The linear drive 32 has a resettable by a spring Piston with an axial piston rod 36 which is slidably extendable through the threaded bushing 34. The top The end of the cylinder 33 is via an if necessary or

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automatically operated valve system of known type either connected to a source of compressed air or to an outlet.

A slider is arranged between the side arms 18 and 19, one of which runs in the longitudinal direction Has threaded bore which is screwed to the threaded end of the piston rod 36. This connection will secured by a nut 38 which sits on the threaded end of the piston rod and against the top of the slider 37 pushes. From the upper part of the slider 37, an arm 39 protrudes to the side arm 19 in which a transverse threaded hole is formed into which a screw 40 is screwed through the Slot 26 passes through and carries an axial roller 41 which is in engagement with the guide slot 26 and is displaceable in the longitudinal direction.

A transverse bore 42 is formed in the lower part of the slider 37 and runs through this transverse bore 42 an axle 43 supported therein. One end of the axis 43 lies under the arm 39 and is provided with a thickened, cylindrical head 44 provided, which has a transverse bore 46 and a central slot, the opposite Clamping arms limited on opposite sides of the transverse bore 46. The clamping arms are aligned Bores 47 provided which extend outside the transverse bore 46 at right angles to this, with a the bores 47 is threaded. In the bores 47 a screw is used, which a Tightening the clamp arms allows.

A radially extending crank arm 48 is rigidly located at the end of the axle 43 opposite the thickened head 44 attached, which at its lower end 49 a

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has slotted, enlarged flange which is clamped on the axis 43. The crank arm 48 extends from the axis 43 upwards and has near its free end a threaded hole 50 into which one Screw 51 is screwed, which carries a freely rotatable, working as a follower roller roller 52, which in sliding engagement with the control slot 27 is.

The head 44 of the axle carries a so-called picker arm 53 or retraction arm, which moves together with the head 44 and is made of stiff wire or rod material. The picker arm is except for his Surrounded at the free end by a plastic sleeve 54. The picker arm 53 comprises a substantially straight, upper leg 56, the upper end of which sits in the transverse bore 46 of the head 44 and is clamped there and the goes down from head 44 and sideways to the right of the path of needle 13 (as viewed in Fig. 1) is offset. From the lower end of the leg 56, an intermediate leg 57 protrudes forward, which at his front end merges into a downward-facing leg, which is inclined slightly to the left. The thigh 58 ends in an integrally formed hook 59 which is open to the rear and comprises an end limb 60, which runs in the longitudinal direction transversely to the path of movement of the needle and inwards and backwards from its base is inclined, so that the hanging thread from the raised needle 13 in a forward movement of the Hook 59 is detected by the end leg 60 of the hook and shifted sideways until the hook 59 is in front of the Has moved the needle track.

The operation of the described thread retraction mechanism is explained below. During normal Sewing the linear drive 32 is vented so that the

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Piston rod 36 is retracted to its raised position as it does in the Pig. 1 and 2 is shown. In this state the rollers 41 and 52 lie at the upper ends of the guide slot 26 and the control slot, respectively 27, so that the picker arm 53 is pivoted backwards and the hook is in the raised position is located behind the needle 13 and completely outside the sewing or working area of the sewing machine.

At the end of the sewing process, the picker arm is in its retracted position and the needle 13 is stopped in its fully raised position. Then the needle thread T hanging from the needle 13 is cut either by hand or automatically. Thereafter, the linear drive 32 is successively connected either automatically or manually to compressed air and then to an outlet, whereby the piston rod 36 and the slider 37 are successively lowered and raised. When the slider is lowered, the picker arm 53, which is carried by the axle 43, is also lowered. The picker arm is not pivoted during the initial, largest rope of its downward movement, since the guide slot 26 and the control slot 27 in which the rollers run are parallel to one another. When the Pickerarm reaches 53 in a downward movement to a position in which the roller into the lower portion 29 of the control slit occurs 27, there is the hook 59 at a height between the lower end of the raised needle 13 and the presser foot 15, Venn, then the Slide 37 is moved further down by the piston rod 36, the roller 52 runs through the section 29 of the slot, so that the axis 43 is pivoted counterclockwise by the crank arm 48 (in Fig. 3) and thereby the picker arm 53 and the hook 59 pivots forward across the path of the needle 13.

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During the forward movement of the hook 59, the needle thread T hanging down from the needle 13 is briefly removed from the end limb of the hook shifted sideways, after which it was in a position at the end of the forward stroke of the mechanism in which it is aligned with the opening of the hook 59.

Then the linear drive 32 is connected to an outlet, so that the piston rod 36 by a spring in their raised position is returned and the picker arm 53 and the hook 59 perform a movement, which runs in the opposite direction to the movement carried out on the forward stroke of the piston rod 36. During the Backward movement of the hook 59, the cut needle thread T is gripped and moved backward and then moves upward during the upward movement of the picker arm 53, thereby cycling and retracting of the thread from the sewing area.

Although only a preferred embodiment of the invention has been shown and described; however it lies It is obvious that numerous modifications, additions and omissions can be made without the scope of the Invention to leave.

Patent claims:

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Claims (6)

BOEHMERT & BOEHMERT Claims n ^) Pade retraction mechanism for a sewing machine with a Needles that are moved back and forth on a path between a raised and a lowered position can, characterized by a picker element (53) with a hook (59) having a rearward-facing Has opening, and a drive device (18, 19, 32, 37, 43, 48) behind and above the needle path is arranged and carries the picker element so that it can successively lower it to the needle path, back and can pivot so that the hook is moved back and forth crossing the needle path, and then retract and can lift above the trajectory of the tip of the needle. 2. Pade retraction mechanism according to claim 1, characterized in that the drive device a slide (37) which reciprocates between a raised and a lowered position can, wherein the picker element (53) is pivotally supported by the slider, a stationary element (28) and a scanner (52) coupled to the picker element and to the stationary element engages in the lower track section of the slider so that the picker element is engaged when it is lowered and raised of the slider is pivoted back and forth near the end of its path. 3. Pade retraction mechanism according to claim 2, characterized in that the picker element has a comprises elongated arm (53) which extends downwards from the slide (37) and terminates in the hook (59). -11- 609809/0858 BOEHMERT & BOEHMERT 4. thread retraction mechanism according to claim 3, characterized in that the drive device a transverse axis (43) which is mounted in the slider (37) and carries the picker element (53), and a crank arm (48) attached to the axle and the scanner (52) eccentric with respect to the Axis carries. 5. Pade retraction mechanism according to claim 1, characterized in that the drive device a pair of parallel, vertically extending, laterally spaced side arms (18, 19) which located behind and above the needle track and in which a first guide slot (27) and a second guide slot (26) are formed, the parallel, straight, have upper section (28), wherein the first guide slot has a control path forming a lower section (29) which forms an angle with the upper section, a slide (37) which between the Side arms arranged and is slidably displaceable along these, a transverse axis (43), which in the Slider is mounted, a crank arm mounted on the axle (48), a first follower roller (52) on the crank arm is arranged and is in engagement with the first guide slot, a second follower roller (41), which on Slider is arranged and in engagement with the .second · guide slot, and means (32) for reciprocating of the slider, the picker element having an arm (53) extending from the axis and ends in the hook (59). 6. thread retraction mechanism according to claim 5, characterized in that the means for reciprocating Introducing the slider comprise a pneumatic cylinder (33) with a piston rod (36) which is connected to the Slider is connected. -12-609809 / 0658