US2000254A - Lockstitch sewing machine - Google Patents

Description

May 1935- F. RICKS ETAL 7 2,000,254

LOCI STITCH SEWING MACHINE Filed Jan. 5, 1934 3 Sheets-Sheet 1 Wiiness Inveniors y 1935- F. RlcKs ET AL 2,000,254

LOCKSTITCH SEWING MACHINE E 'iled Jan. 5, 1954 s Sheet-Sheet 2A Fz'yj FL .8 fm/eniors 652.4 M Wiiness M mm v & Fw/M @VM W May 7,1935. F RICKS ET AL 2,000,254

LOCKSTITCH SEWING MACHINE Filed Jail. 5, 1 934 3 Sheets-Sheet A3 -3, v o o flaw Patented May 7, 1935 UNITED STATES L CKSTITCH SEWING MACHINE Fred Ricks and Harold Ernest Elliott, Leicester, England, assignors to United. Shoe Machinery CorporationfPaterson, N, 'J., a corporation of New Jersey Application January 5, 1934, serial N6. 705,408 ;In Great Britain April 12, 1933 This invention is concerned with improvements in or relating to sewing machines, and is particularly but by no means exclusively. con-. cerned with sewing machines for operating on thick stubborn materials such as leather.

as i

1 to allow the machine to operate smoothly andsufiiciently at speeds which are considerably in excess of those customary in curved hooked needle lockstitch sewing machines" such as are in general use at the present time. The machine disclosed in said co-pending application has been found to operate very efficiently on many kinds of work, the thread handling and controlling instrumentalities of the machine being found to manipulate the thread in the desired manner withoutappreciable danger of causing breakage or chafing of the thread.

When operating on certain other kinds of work, however, particularly when operating on work which is to be sewn by either very thick or very thin hot waxed thread (as contrasted with so called gummed thread) some tendency tobreak ing or chafing the thread becomes apparent especially at the highest speeds. y

We have found that this tendency is, at least,

a largely due to the fact that the wax with which the thread is coated tends to adhere to the hook or barb of the needlethrough which the thread passes, thus tending to prevent the thread from being lifted out of the barb by the beak of the rotating shuttle at the correct instant in the machine cycle and causing the thread to reeve around the lip of the needle barb as the shuttle beak tends to lift the thread out of the barb and thus to break orstrand.

One of the several objects of the present invention is to improve the machine disclosed in the said co-pending application by providing means which shall ensure that the needle thread will be lifted out of the needle barb. at the correct time in the machine cycle without danger.

of breaking or stranding irrespective of the adhesive qualities of the Wax with 1 which the thread is coated and irrespective of the thickness of the thread being used This particular one of the several objects of the present invention is sought to be achieved in the illustrative embodiment of the .present invention hereinafter described, by providing on the beak of they shuttle, on that side whichis arranged to engage the rear limb of the needle thread loop, .ai-relatively shortand steep cam member which acts as the shuttle beak engages the loop ofneedle thread, held open for it bythe thread lifter of the machine, to give-to the thread passing through the needle barb a quick considerable moyementrearwardly of the machine towards the open end of the barb of the needle so that continued rotation of the shuttle causes the thread to ride easily out of the barb.

There is also and in accordance with another of. the several features of the invention preferably provided on the shuttle beak just beyond the said cam member'of the illustrative embodiment a shoulder which is so arranged that after the loop of needle thread has been taken out of the needle barb by the aidof this cam action its rearward limb can, during continued lifting action of the shuttle beak, flick into a recess operated by said shoulder andthus be deflected quicklysomewhat to-one side of the plane in which the needle moves, thus assisting in overcoming the danger which would exist if the said limb of the loop were to remain in the plane in which the needle moves after the loop has been taken off the needle, that the said limb might deflect itself so as to be struck and pierced byithepoint-of theneedle which latter moves forwardly and downwardly towards the work during and somewhat afterthetime when the loop is being taken out of the needle barb. Furtherand-in; accordance with yet another of the several features of the inventionin the said illustrative embodiment of the present invention means is preferably provided for pre-, venting the slight possible reeving or chafing of the needle thread through the barb of the needle as the thread lifterexerts its lifting action on the loop' of needle thread to open the loop forthe reception of the shuttle beak. For this purpose the needle guide of the machine, which serves to support the needle against bending during its Work penetrating action, is ar-' ranged to be moved in such a manner that as the thread lifter moves into engagement with the thread loop and thenopens the latter, the limb of thethread loop in the needle barb which extendsdown to the stitch last formed is trapped against the closed end of the barb by the v needle guide in a sufliciently. positive man-' ner to prevent reeving of thethread through the barb, the thread lifter acting on the other limb of the loop to draw up the additional amount of thread required for the opening of the loop from the rising thread take-up device. In this construction the needle guide is arranged to release the thread and be retracted as the thread lifter approaches the top, of its stroke so that the lifting action of the shuttle beak on the thread loop, which commences just about as the thread lifter reaches thetop of its stroke, shall be unimpeded by presence, close to the needle barb of the needle guide.

The nature of the present invention will be come more clear from the description which-follows, with reference to the'accompanying diagrammatic drawings, of the illustrative embodiment aforementioned. W i

In the drawings:

Figure 1 is a. front view showing part of a shuttle of the said illustrative embodiment" Figure 2 is a right hand side elevation of the shuttle seen in Figureil; I

Figure 3 is a rear view of the -shuttle beak; Figure 4 is a-view of theshuttlebeak looking inthe direction of the arrow .se'enin Figure 3 Figures 5 and 6 are respectively front and right hand-views'showing' the relation of certain parts of the illustrative embodiment at one stage in a cycle of the machine when the'shuttle beak is about toenter the loop of needle thread; Figures I and 8 are front andrl'ght hand side views showing the same parts at a slightly later stage in the machine cycle when the shuttle beak is just about to remove the loop from the needle barb;

Figures 9 and 10'are front and right hand side views showing the same parts at a still later stage'in the machine cycle just after the loop has left the needle barb; p v Figure 11 is a view looking in the direction of the arrow seen in Figure 7; a

Figure 12 is a view looking in the direction of the arrow seen in Figure 9; and c Figure 13 is a vertical-sectional view illustrating the construction and relative arrange ment of some of the principal parts of a machine embodying the several features of 'the present invention. F

The machine of the'present illustrative embodiment can be assumed to be generally similar, except in so far as is'hereinafter pointed out, to the machine disclosed in the specification of the co-pendin'g application aforementioned and reference is directed to said specification for a detailed understanding of the construction and operation of parts of *the machine" which are only briefly referred to hereinaften tive embodiment is indicated generally at I, the general construction and driving arrangement of the shuttle being similar to that of the shuttle disclosed in application No. 688,480.

The beak 2 of the shuttle of the presentillustrative embodiment, however, has formed on it an outwardly directed cam member which acts at the time-and in the manner hereinafter indicated to urge thread passing from the needle barb to the thread lifter rearwardly toward the open end of the barb. This cam member is formed on the rear side of the beak, looking at the machine from the front, and extends from the-loop entering end of the beak-rearwardly at-an angle of about 510 to the plane in which the shuttle rotates. The cam memberis about three quarters of an inch long and extends cam member is inclined downwardly towards the rear to form a smooth continuation of the upper thread engaging face of the beak. Near .its .broader end, however, the upper face 6 of the cam is cut away or stepped down at 8 to provide a recessed portion into which the needle loop may snap at the instant that the shuttle beak acts to lift the, thread clear of the needle barb, the sudden snapping of the thread into ,this recessed portion allowing the tension in the thread to relax somewhat in an instantanerl ous manner to allow the thread to whip more easily out of the needle barb. The endofthe cam face which is remote from the loop-entering end of thebeak does not slope gradually to rejoin the shuttle body but ends more or less abruptly as shown for example in Figure -8 to constitute a shoulder and thus create a notch into which the thread may slip, due to the rotation of the shuttle, soon after the loop of thread has been taken off the needle by the shuttle beak. In slipping around this shoulder the limb of the loop of thread which lies on the rear side of the shuttlemoves towards the left of the plane of movement of the needle, this together with the movement of the thread towards the left which is eifected by continued rotation of the shuttle, ensuring that it will not move into the path of and be struck by the needle point which moves downwardly and forwardly towards the work during, and somewhat after, the time when the shuttle beak is acting to lift the loop of needle thread oif the needle.

actually engaged the needle loop held open for it by the thread lifter, the latter retires downwardly toits inoperative position once more,

leaving the loop supported in the shuttle beak.

The needle guide of the machine through which the needle passes and by which it is supported during its work penetrating stroke isv j indicated at 22, see particularly Figures 6, 8' In all the figures the shuttle of the -illustra-' and 10. The needle guide is socontrolled and moved, in the present illustrative embodiment, by cam mechanism of the general character described in application No. 688,480 that, just before the thread lifter engages the needle loop,

it (i. e. the needle guide) is advanced in a forward and downward direction along the needle so far as to grip the thread in the needle barb firmly against the closed end of the barb. The needle guide remains in gripping engagement with the thread, thus preventing movement of the latter through the barb, during the whole of the time that the thread lifter is engaging the right handlimb of the needle loop and to lift it to open the loop for the reception of the shuttle beak and. releases itsgrip on the thread as the thread lifter is reaching the top of its stroke and the shuttle beak has just engaged the loop. The fact that: the thread..;is". held gripped in the needle barb :against'm'ovement as the loop is being opened. by the threadlifter prevents the rising action of 1 the threadlifter from causing any movement of'the threadito take place through the barb and therefore avoids such chafing of the thread 'as-fwould' be likely to occur if the thread were free to'move through the barb as the thread lifterexerts a tension'on the thread in opening the loop. Since the limb of the loop engaged by the thread lifter passes downwardly from the needle to the threadtakeup device of the'machine' (which .latterrises" somewhat to pay out thread as thethread lifter rises to open the loop) thefact that'the thread in the needle barb is gripped against movement as the'thread lifter rises to open the loop does not offer any impedimentto the 'openingpf the loop. After the thread lifter has finished its loop-opening function and the shuttle beak has engaged the thread,"the thread lifter in returning to its thread-engaging end'passes through the needle plane before the needle has descended so far as to foul it in its descent.

The needle continues its descending movement part-way towards the work during the time thatv the shuttle is rotating after having lifted the thread loop off the needle, and remains in a lowered position during the time that the loop is being pulled oil; the shuttle by the take-up.

for the setting of the stitch.

In order to prevent the loop of thread from becoming caught once more in the barb of the needle as it is pulled down on to the work, the needle guide is moved downwardly along the needle to cover the needle barb soon after the loop has been lifted from the needle and remains substantially in this position until the setting of the stitch has been completed.

The manner in which the various instrumentalities cooperate during the opening of the needle loop and the taking off of the loop from the needle barb will now be described with reference to Figures 6 to 12.

In Figures 5 and 6 the parts are shown in the positions they occupy just before the shuttle beak actually engages the needle loop. The point of the needle ll occupies the position above the work indicated which it'will have reached in rising nearly to the top of its stroke and the needle guide 22 is gripping the thread against the closed end of the needle barb, it actually having been moved to grip the thread against the closed'end of the barb before the thread lifter I3 is moved forward from its inoperative position sufficiently far to engage the thread. The thread lifteris nearing the top of its loop-opening stroke drawing off the necessary amount of thread for the opening of the loop entirely from the thread take-up device and the loop has been partly opened for the reception of the shuttle beak which latter will, however,

not yet have engaged the thread. The relative positions of the cam member 4 on the shuttle beak and the limb of the needle thread which passes from the needle directly down to the work at this time are clearly visible, the rear edge of the cam member, as seen in Figure 6, lying rearwardly across the line in which the said limb of thread extends. i

In Figures 7, 8 and 11 the parts are shown in.

the positions which they occupy when the shuttle beak having engaged the thread is just about to remove the thread loop from the needle barb. The needle has already risen to the top of its stroke and is descending somewhat slowly, having reachedaposition similar to that shown-in Figure 6. The thread lifter I3 is at the top of its loop-opening strokeand the needle guide 22 occupies a slightly more'irearward positionvthan is indicated in Figure 6 having just released its grip 'onthe thread to allowthe thread tobe freely. removed fromv the .barb by the. shuttle beak. The latter :has, as ..stated,x*already' en-j gaged the thread and started to lift it out of the needle barb the cam/member 4. acting as shown, to. urge the thread 'positively towards the rig'htof the needle plane somewhat while moving itmarkedly rearwardly towards the open endof the needle barb to allow the continued rising of the beak to: cause the threadto whip out of the barb withoutbeing'caught on thelip of the barb, it being understoodthat thezieedle will continue its 'descending movement as the shuttle beak is acting-itoaliftthe thread outxiof the barb. Just as the shuttle beak is actingto lift the thread clear of the barb, the thread snaps ,into thef"-recessd.portion'8 of Ithefcam member and the slight: but sudden release of tension in the, thread, which takes place as a result of this, assists the thread to whip out of the barb just as the action of the cam member on the thread is concluding.

barb toclose the latter and prevent the loop of thread when it is later drawn off the shuttle by the take-up, from catching in the barb.

The thread lifter hascommenced to descend and willbe moving down sufficiently rapidly to cross the needle path below the point of the latter.

The shuttle beak will have moved upwardly sufiiciently far for the thread to slip around the shoulder into the recess the thread moving, in moving around the shoulder, somewhat towards the left of the needle plane, thereby assisting the continued rotation of the shuttle beak to carry the limb of thread which passes up from the work to the rear side ofthe shuttle beak out of the needle plane and thus ensuring that it will not be struck and pierced by the descend ing needle.

If desired, .the thread lifter actuating mechanism may be modified so that in opening the needle loop, it rises to a somewhat higher position, before the shuttle beak engages the thread, than is really necessary to open the loop sufiiciently for the shuttle beak to enter, thus drawing a little surplus thread into the loop. With 7 and therefore making it easier for the thread 1 to escape from the barb. I

The nature and scope of the invention having been indicated, and mechanism embodying the several features oftheqinvention having been specifically described, what is clairnedis:

1. A lockstitch sewing machine. having, in

combination, stitch forming devices comprising a. curved hooked needle, a loop lifter and a discoidal shuttle provided with a beak to enter the loop held by the needle and loop lifter and with a cam on the shuttle beak projecting beyond the shuttle. body" towards. the needle. to lift the needle loop from the needle barb.

2. A lockstitch sewing; machine having, in

combination, stitch. forming devices comprising intowhich the needle loop may snap when lifted clear of the needle barb. 3. A lockstitch sewing machine having, in combination, stitch forming devices comprising a. curved hooked needle, a loop lifter and a. discoidal shuttle provided with a beak to enter the loop held by the needle and loop lifter and with a cam on the shuttle beak projecting beyond the shuttle body towards the needle to lift the needle loop from the. needle barb, said cam terminating in a shoulder on the side of the shuttle towards the needle, and thereby forming a notch to receive the thread taken from the needle barb and deflect. it away from the plane of, the needle.

4.. Av lockstitch sewing machine having, in combination, stitch forming devices comprising a curved hooked needle, a. needle guide, a, loop lifter, a discoidal shuttle provided with a beak to enter the loop held by the needle and loop lifter, and means for actuating the needle guide to hold the thread gripped inv the needle barb during the thread lifting movement of. the thread liften.

' FRED RICKS.

HAROLD ERNEST ELLIOTT.

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