US3509840A - Lockstitch sewing method and system providing bobbinless feed of the bottom thread from a bulk source - Google Patents

Description

May 5, 1970 3,509,840 LOCKSTITCH SEWING METHOD AND SYSTEM PROVIDING 4 Sheets-Sheet l I If/R SUPPLY INVENTOB. Herman R074)! 7 0 w J m w S i R K I m J i L H B A BOBBINLESS FEED OF THE BOTTOM THREAD FROM Il/Rf/YD WISH-RING DV/CE Filed June 12, 1967 I MZ ANEW.

May 5, 1970 ROVIN 3,509,840

LOCKSTITCH SEWING METHOD AND SYSTEM PROVIDING BOBBINLESS FEED OF THE BOTTOM THREAD FROM A BULK SOURCE 4 Sheets-Sheet 2 Filed June 12, 1967 :j INVENTOR.

1549911012 Havuz 7 flIFWRA J'YS;

May 5, 1970 H. ROVIN 3,509,840

LOCKSTITCH SEWING METHOD AND SYSTEM PROVIDING BOBBINLESS FEED OF THE BOTTOM THREAD FROM A BULK SOURCE Filed June 12, 1967 4 Sheets-Sheet s 47 s INVENTOR.

Herman Rowln May 5, 1970 H. ROVIN 3,

LOCKSTITCH SEWING METHOD AND SYSTEM PROVIDING BOBBINLESS FEED OF THE BOTTOM THREAD FROM A BULK SOURCE Filed June 12, 1967 4 Sheets-Sheet 4- INVENTOR. 7 fferman R0701 United States Patent 3,509,840 LOCKSTITCH SEWING METHOD AND SYSTEM PROVIDING BOBBINLESS FEED OF THE BOT- TOM THREAD FROM A BULK SOURCE Herman Rovin, Norwalk, Conn., assignor to Ivanhoe Research Corporation, New York, N.Y., a corporation of Delaware Filed June 12, 1967, Ser. No. 645,183 Int. Cl. D05b 9/00 U.S. Cl. 112-181 34 Claims ABSTRACT OF THE DISCLOSURE The bottom thread is supplied directly from a bulk source, such as a large cone shaped winding, being metered out from the source, and it is then injected into the basket cavity of a lockstitch sewing machine (where the bobbin would normally be placed) to cooperate with a conventional reciprocating needle carrying a top thread to form lockstitches between the top thread and the bottom thread. The invention makes possible the supplying of the bottom thread by high-speed injection in a fraction of a second from a continuous supply, rather than using a limited bobbin supply. In the method as shown a predetermined length of bottom thread is metered out which is just suflicient in each instance for producing the desired stitching path in the respective workpiece to be stitched, and this length is injected into the basket cavity. Thus, when the stitching path is completed, the predetermined length of bottom thread is spent, and it is not necessary to cut the bottom thread upon completion of the stitching path. Also, the bottom thread never runs out during stitching. A freely rotatable turbine spool in the basket cavity is accelerated to high velocity by an air blast impinging upon turbine vanes, and this high-speed turbine spool seizes the injected thread and serves to hold temporarily the predetermined metered length which has been loaded in readiness for stitching. The invention is applicable to any existing Type 301, lockstitch sewing machine, be it single or double needle.

Background of the invention In using a sewing machine today, it is conventional to store a limited supply of the bottom thread upon a bobbin which is suitably housed in a basket cavity of the sewing machine to be in cooperative relationship with the reciprocating needle of the sewing machine. In forming the individual stitches the top thread, which is carried by the needle, is caused to pass around the basket so as to loop around the extending part of the bottom thread to form an interlocking stitch between the top and bottom threads. The bobbin is wound substantially full of thread before being placed in its case which is placed in the basket. In using a sewing machine, the conventional practice is for the operator to remove the bobbin and case from the hasket and then to remove the bobbin from its case whenever the bottom thread has become exhausted. This empty bobbin reel is placed in a rewinding jig on the sewing machine, and the sewing machine is operated in such a way as to rotate the bobbin to wind up a limited supply of bottom thread thereon. Then the operator reinserts the bobbin into its case and loads the full case back into the basket of the sewing machine. The operator can then carry on with the stitching operation. This involves retracing a portion of the stitching Where the bottom thread had run out, if it occurred in an intermediate portion of a stitch path.

In many commercial garment manufacturing operations, the bottom thread is supplied from commercially available pre-wound bobbins wherein the reel is formed of inexpensive materials such that the operator removes the 3,509,840 Patented May 5, 1970 bobbin and case and discards the spent bobbin reel and inserts a new pre-wound one into bobbin case and reloads the case into the machine so as to carry on with the production operation 'without the delay of rewinding the bobbin itself. Among the difficulties of this type of operation is the fact that the bottom thread supplied by the bobbin runs out at an indeterminate time and place; so that the operator must remain alert for the contingency. In addition, a substantial period of time is involved in removing the case, removing the spent bobbin therefrom and in replacing it with a full bobbin and then reloading the full case into the basket of the machine.

Whenever the thread runs out at a random location in an intermediate portion of a stitching path, it is necessary for the operator to restitch a sufficient length of this path so as to be assured of a seam with no gap. This overlapping stitching produces an un-neat appearance in the finished product and is a potential source of problems with the stitching because the end of the spent bottom thread and the end of the new bottom thread are both available along the re-stitched portion of the seam. To a degree it is wasteful of materials as well as the operators time.

Description Among the many advantages of the method and sewing system of the present invention for industrial applications are those resulting from the fact that a predetermined desired length of thread for forming a given stitching path can be metered out and is injection loaded into the basket cavity of the machine ready for usage so that the operator knows that just the right amount of bottom thread is available for forming each stitching path in each workpiece. At the time when the bottom thread runs out, the stitching path will have been completed. Each workpiece has the same neat appearance and all of the seams are complete without restitched portions and loose ends at an intermediate point along the length of the seam.

Another advantage results from the fact that the desired length of the thread is injection loaded into the basket cavity to be received on a freely rotatable turbine spool having associated turbine blades, and an air jet impeller is arranged for rotating this turbine spool at high velocity. The desired predetermined length of the bottom thread is injected into the basket cavity near the high-velocity turbine spool which effectively catches the end of the metered thread and winds up this desired length of thread almost instantaneously. Thus, this length of bottom thread is placed in the basket cavity in a fraction of a second. The injection into the basket cavity is accomplished in less than the time which is required for the operator to remove the finished workpiece and to locate the next workpiece in the sewing station near the needle of the machine.

In some industrial sewing operations the operator tails up one piece right after another and keeps the sewing machine running. In such an operation the metered length of bottom thread which is injected into the basket cavity is suflicient to complete the desired stitching path extending through a predetermined number of pieces.

This invention greatly simplifies the supplying of the bottom thread and enables the entire operation to be car ried out completely automatically without removal or replacement of any bobbin. 'In addition, upon the comany existing lockstitch machine of Type 301, regardless of whether the machine is a single needle or a double needle machine. Equipment embodying this invention can be sold as an attachment for existing Type 301 sewing machines. The equipment does not require any mechanical'lin'kage to the existing machine drives and thus is very well suited to comprise an attachment.

' Another advantage of the present invention is its utility in, automated sewing systems wherein the only scheduled demand upon the operator is to change the bobbin. Accordingly, there is .much down time when the bobbin runs out and the machine sits idle waiting for the operator to get tothe machine- This invention solves that problem of down time and relieves the operator of the task of changingbobbins. The bottom thread is enabled to be supplied directly from a bulk source, such as a continuous coneshaped spool of thread, similar to that now used to supply the top thread. Thus, the sewing machine can run automatically to form each stitching path, without the interruptions and delays occasioned by running out of the bottom thread.

In-this specification and in the accompanying drawings are described and shown a method of automatically sewing and a system embodying the invention, and it is to be understood that this disclosure is not intended to be exhaustive or limiting of the invention. This disclosure is set forth for purposes of illustration in order that others skilled in the art may fully understand the invention and the manner of applying this invention in practical use in lockstitch sewing machines for various production conditions and installations.

The various objects, aspects and advantages of the present invention will be in part more fully pointed out and in part will become understood from the following description of an illustrative embodiment of the invention when considered in conjunction with the accompanying drawings, in which:

' FIG. 1 is a perspective view of a sewing method and system for a lockstitch sewing machine wherein predetermined lengths of bottom thread are metered out from a bulk source and are automatically injected into the basket cavity of the machine;

FIG. 2 is a perspective view of the high-speed rotatable turbine spool including turbine blade elements thereon and a novel case for housing this turbine spool which is adaptedfor having thread injected therein;

FIG. 3 is a' front elevational view, shown on enlarged scale, of the high-speed turbine spool and its case latched in place in a basket within a conventional revolvable hook member. This hook member, when it revolves during stitching, loops the top thread around the basket and case for interengaging the top and bottom threads. The bottom thread injection needle is shown inserted into the case;

FIG. 4-is'a sectional view shown on the same enlarged scale as FIG. 3, illustrating the bottom thread being injected into-the high-speed rotating turbine spool which has been accelerated by an air jetfrom a nozzle;

@FIG. 5 is a top plan view of the thread transporting and injection mechanism, including a cut-off device for providing a predetermined length of the bottom thread as previously metered out;

FIGQ'6 is a front-elevational view of this thread trans- :port'and injection mechanism as seen in the direction 66 inFIG-URE 5;

" 7 is aside-elevational view of the thread transport and injection mechanism of FIG. 6 as seen in the direction 7 7 in FIG. 6;

FIGURE 8 is a partial sectional view taken along the line 88 in FIG. 7; and.

FIGS. 9,10 and 11, are front elevational views similar to FIG. 6 and showing the parts in different operating positions during a cycle of operation.

' As shown in FIG. 1 a workpiece W is positioned in the sewing station 10 of a sewing machine and is being 4. T stitched by the reciprocating needle N forming a desired path of stitches S in the workpiece W. A to thread 12 is carried by the eye of a reciprocatable needle N. This needle N is driven up and down by conventional mechanism of the lockstitch sewing machine, and the top thread 12 is handled in a conventional manner. To simplify the drawings to illustrate the'invention as clearly as possible all of this conventional sewing machine equipment has been omitted.

In forming a stitch the top thread 12 is engaged with a bottom thread 14 to form a path of lockstitches S. This type of lockstitch is identified as Stitch Type 301 in the Federal Standard No. 751, dated Aug. 14, 1959, and entitled Federal StandardStitches, Scams, and Stitchings, published by the General Services Administration.

In the sewing station 10 there is the conventional support surface (not shown) upon which the workpiece W is handled, including a so-called throat plate. As the needle N is reciprocated, its point penetrates down through the workpiece and passes down through an opening in the throat plate so as to bring the eye of the needle near a conventional revolvable hook member 16, which is located in the conventional position beneath the throat plate near the needle. This hook member 16 is secured to and is revolved by a conventional hook shaft 18 which is driven !by the sewing machine in synchronized relationship with the movement of needle N. The hook member 16 has a generally annular configuration with a hub 20 secured to the shaft 18. This hook 16 is in effect an annular revolvable ring-like member and it has a hook point 22 mounted on it. There is also a conventional needle guard on the hook member 16 located almost diametrical- 1y opposite to the hook point 22. In FIG. 1 the hook shaft 18 and hook member 16 revolve in a counter-clockwise manner when the sewing machine is running.

During stitching the hook member 16 revolves synchronously with, the stroke of the needle N in phased relation ship with the needle-so that the hook point 22 on the hook member 16 is in position to engage the top thread 12 upon each stroke to draw the top thread around a basket 24 (FIG. 3) mounted within the annular hook member 16. Although the hook member 16 revolves during stitching, the basket 24 is held stationary at all times by a stationary finger (not shown) in the machine which engages in a notch 26 in the basket 24. A case 28 is located in a cavity 27 within the basket 24, and a detent 29 on the case engages in a notch in the basket for holding the case in a fixed position in the stationary basket. This relationship between the annular, revolva'ble hook member 16 and the stationary basket and case held therein as de scribed above is conventional. It is among the many ad vantages of this invention that it enables so many conventional relationships and components of a lockstitch sewing machine to be utilized.

-Within the basket cavity 27 is latched the case 28 (as seen also in FIG. 2) having a novel injection open ing 30 and novel thread tensioner spring 32. Supported within case 28 is a freely rotatable high-speed turbine spool 34 having turbine vanes 36 formed on the outer radially extending surface of one flange 37 of the turbine spool for accelerating it to high velocity prior to injection of the desired predetermined length of thread into the basket cavity.

As seen in FIG. 2 the turbine flange 37 is relatively thicker than the other flange of the turbine spool 34. The vanes 36 are under cut, as illustrated in FIG. 2, and they are curved aft (as seen in FIG. 4). That is, if the reader traces one of the vanes .36 as illustrated in FIG. 4, beginning at the perimeter of the flange 37 and tracing radially inwardly therealong, the reader will see that each under cut vane 36 curves aft, or backward, relative to the intendeddirection of rotation of the turbine spool. Thus, when an air jet strikes these vanes, this jet being a i med radially inwardly and forwardly in the desired direction of rotation by a nozzle 66 as described further below, the air jet applies a torque to the turbine spool to accelerate it almost instantaneously to a high rotational speed of many thousands of revolutions per minute. The air jet maintains the turbine spool spinning at this high speed until the injected and wound up taut bottom thread arrests the turbine spool.

Being of low angular inertia the turbine spool 34 is readily accelerated and stopped. The case 28 and turbine spool 34 will be described in greater detail further below, following a description to be presented of the sewing method performed in accordance with one aspect of the invention.

Referring again to FIG. 1, it is illustrated by a flow arrow that the bottom thread 14 is fed directly from a bulk supply 38 on a support 39. The bulk supply 38 is shown as a commercially available cone shaped winding containing a continuous strand of thread many thousands of yards long. This invention is adapted to utilize any bulk supply containing a continuous strand of thread.

During the time interval while the stitching path S is being formed in the first workpiece W, a predetermined length of thread is metered by a thread metering device 40. This length of thread which is metered out is just suflicient to accomplish the stitching path in the second workpiece W-2, that is shown in the distance in FIG. 1. The thread metering device 40 may include any suitable measuring elements such as a friction snubber, a pair of rubber-coated rollers engaging the thread 14 and driven by a gear train so as to pull a measured length of the thread through the friction snubber, and a receptacle such as a moving conveyor belt for receiving the measured length of thread so as to support the thread free of snarls available to be pulled off from the receptacle almost instantaneously.

As discussed in the introductory portion of the specification above, in some cases the desired stitching path may extend through more than one workpiece. In this case the stitching path continues through several individual pieces which may collectively be considered as constituting one workpiece, and the metered length of bottom thread is suflicient to accomplish the desired stitching path without interruption.

A thread transport and injection mechanism, generally indicated at 42 in FIG. 1, serves to remove the available metered length of thread from the device 40 and injects it into the basket cavity 27. This injection of the bottom thread 14 into the basket cavity occurs during the brief time period while the first workpiece W is being removed from the sewing station and the second workpiece W-2 is being moved into the station 10. Thus, no delay in production occurs. During this positioning of the second workpiece in the station 10, the sewing machine is temporarily stopped in a predetermined position and so the hook member 16 is stationary, and its position is known at this time. The invention is equally applicable whether the workpieces W and W-2 and so forth are manually handled or automatically handled.

By virtue of the fact that the length of bottom thread was predetermined to be just sutficient to complete and tail off the stitch path S in the workpiece W, there is no necessity to cut the bottom thread before moving the workpiece W away from the sewing station 10. The top thread 12 is cut by any suitable automatic cutting mechanism, such as are commercially available or manually by a pair of scissors.

The thread transport and injection mechanism 42 will be described by reference to FIGS. 1 and 511. This mechanism 42 includes a hollow injection needle 44 mounted upon a movable support 46 which is raised and lowered by a piston rod 47 (FIGS. 1 and 7) extending from a fluid actuated cylinder 48. As shown in FIG. 8, a thread feed passage 50 extends upwardly through the movable support 46 and extends past a clamping zone 52 defined by an exposed region of the passage 50, and then this thread feed passage enters the bore. of the needle 44.

A clamping element 54 is formed by a bent spring and normally clamps the bottom thread 14 against a side wall of the passage 50. This spring 54 is held in its clamping position as shown in FIG. 8, by engagement against a track member 56 which extends parallel to the line of movement of the support 46. The track member 56 is secured by a bracket 58 which is fastened, as shown in FIG. 7, to a main frame member 59 of the injector mechanism 42. As seen most clearly in FIG. 1, the cylinder 48 is rigidly mounted upon this same frame member 59'. The track member 56 not only controls the clamping spring 54 but also serves as guide means for the movable support 46. This support 46 has a pair of projecting guides 60 which straddle the track 56.

When the time comes for injecting the metered length of the bottom thread 14 into the basket cavity, the cylinder 48 is actuated, raising the support 46 so as to insert the injection needle 44 through aligned openings 61 and 62 in the hook member 16 and in the basket 24 and through the injection opening 30 (FIGS. 2 and 4) into the interior of the case 28. At this time of thread injection loading, the sewing machine is stationary with the needle N in a raised position which is predetermined so that the hook member 16 is in a known position with its injection loading opening 61 aligned with the basket opening 62. Both of these openings are aligned with the path of the tubular injection needle 44 into the opening 30 in the case.

There are known mechanisms available for automatically positioning a sewing machine needle N and the hook 16 in a predetermined position upon stopping of the machine, and so this automatic needle positioning mechanism is not shown here.

The cylinder 48 may be actuated by any suitable control means such as an automatically or manually operated switch serving to energize a normally closed solenoid valve 67. Thus the valve 67 becomes opened to feed compressed air from an air supply source 64 through the valve 67 and through a pressure regulator 73 to the cylinder 48, causing its piston rod 47 to move upwardly.

The supply 64 may have any suitable pressure, and in this example has a nominal pressure of pounds per square inch. The fluid actuated cylinder 48 is shown as being of the spring return type. However, it will be understood that this cylinder 48 may be of the double-acting type which is returned by air.

At the same time as the cylinder 48 is actuated to raise the support 46, a solenoid 63 is energized to open its valve so that compressed air from a supply 64 is fed through a tube 65 to a nozzle 66 (FIGS. 3 and 4). This nozzle is aimed through an opening in the hook member 16 and through an opening of the basket 24 so as to direct an air jet against the turbine vanes 36 described hereinabove. The air from the supply 64 is fed to the nozzle 66 at full line pressure, for example approximately 100 p.s.i. This nozzle aims a high pressure air jet inwardly with a com ponent forwardly, as will be understood from FIGS. 3 and 4, to impinge upon the curved vanes 36. The turbine 34 is almost instantaneously accelerated to a high speed of many thousand r.p.m.s.

The air from the source 64 also feeds through the now open valve 63 and through a pressure regulator 70 and then through a flexible plastic tube 68 and through a small duct 69 converging upwardly with the bore of the injection needle 44. Thus there is an upward flow of air through needle 44. The regulator 70 is set to supply low pressure air, for example about 2 or 3 p.s.i. to the bore of needle 44.

Near the upper limit of travel of the movable support 46, as seen in FIGURE 9, the clamp spring 54 rides off of the upper end of the track member 56 thus releasing this clamp 54. The continuous upward flow of air through the needle 44 quickly propels the bottom thread 14 into the region between the flange 37 and another flange 71 of the high-speed rotating turbine spool 34.

As shown in FIGS. 2 and 4, the turbine spool 34 includes a hub 72 and high friction gripping means 74 formed by a plurality of elements 74 capable of catching the leading end portion of the injected thread with a high frictional grip. In this embodiment these elements 74 comprise a plurality of small diameter wires extending parallel to the axis of the turbine spool 34 and spaced outwardly a small distance from the hub 72. The leading end portion of the injected bottom thread becomes detachably caught (FIG. 4) upon one of these gripping elements 74 and the metered thread length is almost instantaneously wound up by this spinning spool. The spool 34 is rotating at very high speed at this moment, for example about 6,000 r.p.m.

In order to grip the leading end of the thread 14 and to wind it up properly upon the spool 34, this spool should be turning sufficiently fast relative to the velocity of the air flowing up the bore of the injection needle 44, that the gripping elements 74 are travelling faster than the thread 14 when its leading end is injected. The end of the injection needle 44 is cut off on an angle facing inwardly toward the axis of the spool 34 and is shaped to direct the thread inwardly around the hub of the spool as shown in FIG. 4.

As soon as this length of thread has become wound up, the thread becomes taut extending from the snubber in the device 40. The taut thread immediately stops the turbine spool 34. This spool is very light and is small being formed of rigid plastic, thus it has low inertia so that the taut thread readily checks its fast rotation without breaking.

The air jet from nozzle 66 continues to apply torque to the turbine 34 so as to hold the thread taut and to prevent backlash of the rotatable turbine 34.

After the brief moment required to inject the metered length of bottom thread onto the spool 34, the taut thread 14 trips a control switch 75 (FIG. 1) which deactuates the cylinder 48, and a spring therein causes the piston rod 47 to retract so as to lower the movable support 46, as shown by the movement arrow in FIG. 10. The thread 14 remains held taut by the air jet from the nozzle 66 applying torque to the turbine spool 34 as the support 46 is lowered to retract the injection needle 44.

As soon as the retraction has begun, the clamp means 54 is caused to clamp the thread 14 at 52 (FIG. by re-engagement of the clamp element 54 against the side of the control track member 56.

For purposes of positioning the available end of the bottom thread 14 beneath the novel thread end tension spring 32 (FIG. 2) on the case 28, the following steps occur. Upon further retraction of the support 46, a hook arm 76 seen in perspective in FIG. 1 which extends from the support 46, catches over a projecting lever arm 78, pivoted at 80 (FIGS. 6, 9 and 11) to the main frame 59. This hook 76 pulls down upon the lever arm 78, as seen in sequence in FIGS. 9, 10 and 11, thus causing the other end 81 of this lever to rise up. A thread end control rod 82 is pivotally connected to the lever end 81 and is slidingly held by a pivot bearing 84 on the upper end of the main frame 59. The upper end of this rod 82 has a transverse portion 85 with a U-bend 86 (FIG. 1).

The rising lever end 81 moves the control rod 82 upwardly, sliding it through the bearing 84 and pivoting it about this bearing so that the U-bend 86 describes an arcuate path 88 (FIG. 11) as indicated by a dash-anddotted line about the case 28. Meanwhile, the thread is held taut by the torque on the spool 34 caused by the air jet from nozzle 66, as described previously. Thus, the thread end portion is positioned beneath the bight 89 of the tension spring 32 with the thread itself passing through an eyelet end region 90 of the elongated injection opening 30. The bight 89 is adjacent to the eyelet end 90. The spring 32 is secured to the case 28 by mounting means 92.

A return spring 93 (FIGS. 6 and 9) stretches from the end 81 of the lever arm 78 to a connection bracket 94 (FIG. 9) on the main frame 59. This spring 93 returns the control rod 82 and lever arm 78 to their initial positions when the hook 76 slips off of the end of the arm 78 (FIG. 11) near the completion of the retraction of the support 46.

In order to cut off the predetermined metered length of the bottom thread, a pivoted knife blade 95 (FIGS. 1 and 5) is swung between a pair of closely spaced shear plates 96. The taut thread 14 passes through aligned holes 98 in the plates 96. A twisted strip actuator 100 is slidingly engaged by a slot in a tab 102 (FIG. 7) projecting from the movable support 46. As the support 46 nears the lower limit of its retraction stroke an abruptly twisted region 104 (FIG. 7) of the strip 100 is passed by the slotted tab 102 causing the knife blade 95 to swing to cut 01f the thread. At the moment of cutting the point of the injection needle 44 is withdrawn to a level just below the plates 96 so that the needle does not interfere with the moving blade. Moreover, the thread is cut oif just above the end of the injection needle 44 in readiness for the next injection.

The location of the thread transport and injection mechanism 42 and the position of the knife cut-off components 95, 96, 98 together with the action of the thread end positioner 82, 85, 86 in traversing the path 88 assures that a sufficient length of bottom thread 14 is left hanging outside of the case 28 and is in the right attitude so that this bottom thread will definitely be picked up at once by the top thread 12 when the stitching motion of the needle N begins again. The tension spring 32 includes an upwardly and outwardly sloping portion 97 facing toward the main region of the injection opening 30 so that the thread 14 can readily be slid around beneath the spring 32 by the positioner 82, 85, 86 so as to become positioned beneath the bight 89.

Upon completion of the retraction stroke, a lower extension of the piston rod 47 (FIG. 1) engages a control switch 107 (FIG. 1) to open this switch, which deenergizes the solenoid valve 63 to allow this valve to close. Thus, the torque is removed from the turbine spool 34 after the thread has been cut to its desired metered length. The clamp 54 holds the end of the thread in the bore of the tubular needle 44 in readiness for the next injection loading cycle.

The end 106 (FIG. 4) of the needle 44 is out off at an angle tending to direct the propelling air stream and the thread in the direction of the arrow 108 (FIG. 4) about the axis of the spinning spool. The hub 72 of the spool is formed of low friction material, for example slippery plastic and has an axial opening 109 therein freely journaled upon a conventional bearing post 110 mounted within the basket 24. A conventional latch mechanism 111 engages a recess in the post 110 to hold the case 28 in position in the basket cavity.

Summary of one pre-metering and injection loading cycle (1) During stitching of one workpiece W a predetermined length of bottom thread 14 is metered out by the device 40 in readiness for accomplishing the sewing path in the next workpiece W- 2.

(2) The sewing machine is stopped after accomplishing the sewing path S in the first workpiece, and the sewing needle N and hook member 16 are automatically positioned in a desired predetermined inactive position wherein the hook member 16 will not interfere with the bottom thread injection loading mechanism and the needle N is elevated so as to clear the sewing station 10.

(3) Upon inactive positioning of the needle N and of hook member 16-, the completed workpiece W is moved out of the sewing station 10. Any remaining tail end of the bottom thread thereby becomes pulled oif from the turbine spool 34 to assure that spool 34 is completely empty. The top thread 12 may then be cut by conventional mechanism.

(4) Control means, automatic or manual, initiates the injection loading of the bottom thread 14. This control means is responsive to the completion of the automatic positioning of the sewing machine (Step 2) and in this example is a normally open switch which becomes closed upon inactive positioning of the sewing machine. This control means energizes the solenoid valves 63 and 67 so as to open these values to:

(5) Bottom thread clamp means 52, 54 (FIG. 8) is released (FIG. 9) when the injection needle 44 nears the limit of its upward stroke; so that loading of the bottom thread 14 immediately commences.

(6) The leading end of the thread 14 is releasably caught by the friction gripping means 74 of the spinning turbine spool, and the previously metered length of the bottom thread is almost instantaneously wound onto the turbine spool 34.

(7) The taut thread 14 now actuates the control switch 75 which actuates the solenoid valve 67 and controls the injection drive cylinder means 48 to cause the injection needle 44 to begin retracting. The air jet continues to flow from the nozzle 66 to maintain torque on the turbine spool 34 to maintain the bottom thread 14 taut.

(8) After the injection needle 44 begins its retraction stroke, the clamp means 52, 54 is caused to reclamp the bottom thread 1-4. In FIG. this clamp means has already clamped the bottom thread.

(9) .As the injection needle 44 is retracting, the bottom thread end positioner 82, 85, 86 is caused to move as shown in FIGS. 10 and 11 (motion path 88) to position the bottom thread beneath the bight 89 of the tension spring 32. The bottom thread is held taut by the torque being applied to the turbine spool 34. The bottom thread now extends out from the case 28 through the eyelet opening 90, and a suflicient amount of the bottom thread extends out of the case 28 in the proper attitude to assure its being picked up by the top thread 12 upon the first stroke of the sewing needle N when stitching again begins.

(10) As the injection needle 44 nears the end of its retraction stroke the needle tip 106 is just below the thread cut- off mechanism 95, 96, 98, and this cut-off mechanism is actuated to cut off the previously metered length of the bottom thread 14.

(11) At the completion of the retraction stroke, a control switch 107 is actuated to cause the valve 63 to close, thus shutting off the air jet to remove torque from the turbine spool 34 and also stopping flow of air up the bore of the needle 44. The bottom thread remains held in the needle 44 by the clamp means 52, 54. The control switch 107 serves to permit the sewing machine to begin operation as soon as the next workpiece W-2 is properly positioned in the sewing station 10. In effect, the control switch 107 serves to signal that the injection loading cycle of the bottom thread is completed and that the sewing machine may resume operation as soon as the next workpiece W-2 is ready.

It is important for the reader to note that although a complete description of the cycle requires a substantial amount of text, the actual thread injection loading is accomplished in significantly less time than one second. That is, steps numbered 4 through 11, inclusive are accomplished in less than one second of time. Moreover, this injection loading can be accomplished while one workpiece is being removed from the sewing station and while the next is being positioned therein, either manually or automatically. Thus, the injection loading, which occurs so rapidly, does not consume productive time. In fact, this invention greatly extends productive time because the bottom thread never runs out in an intermediate portion of a stitching path. There is never any down time of the sewing machine awaiting replenishment of a bobbin reel.

The pre-metering of the thread 14 occurs during the previous sewing operation, and so it occasions no utilization of non-productive time.

It will be understood that the mechanism shown in FIG. 3 comprises thread carrying means for carrying the bottom thread 14. In this illustrative example the thread carrying means includes the revolvable hook member 16 which carries a basket 24 having a cavity 27 therein for carrying the bottom thread. However, other equivalent arrangements are used in lockstitch sewing machines wherein a top thread carried by a reciprocatable needle is engaged with a bottom thread carried by equivalent bottom thread carrying means. The hook member 16 serves to engage the top thread 12 with the bottom thread 14 by looping the top thread around the bottom thread. Other equivalent hook members may be used for accomplishing this interengagement looping of the two threads, for example the hook member 16 may oscillate or shuttle so as to accomplish the interengagement of the two threads and in each arrangement there is means for carrying the bottom thread to which this invention is applicable, as will be understood from my detailed specification herein given.

The terms and expressions which I have employed are used in a descriptive and not a limiting sense, and I have no intention of excluding equivalents of the invention de scribed and claimed.

I claim:

1. For use with a sewing machine of the lockstitch type wherein a top thread carried b a reciprocatable needle is engageable with a bottom thread leading from bottom thread carrying means to form lockstitches be tween the top and bottom threads, the method of injection loading the bottom thread into the thread carrying means comprising the steps of providing a bulk source of the bottom thread positioned outside of the thread carrying means, feeding the bottom thread into a passage, directing the passage into the thread carrying means, and flowing air along the passage moving the bottom thread into the thread carrying means.

2. For use with a sewing machine of the lockstitch type, the method of injection loading the bottom thread into the thread carrying means as claimed in claim 1, including the steps of feeding out from the bulk source a predetermined length of the bottom thread to be available for feeding almost instantaneously, snubbing the bottom thread upstream of said predetermined length, and moving the predetermined length of bottom thread by flowing air through said passage into the thread carrying means until the bottom thread becomes taut therealong back to the point of snubbing, then clamping the bottom thread between the point of snubbing and the thread carrying means, and thereafter cutting the bottom thread at a distance from the thread carrying means to leave an end portion of the bottom thread extending therefrom in readiness to be engaged by the top thread upon reciprocation of the needle.

3. For use with a sewing machine of the lockstitch type, the method of injection loading the bottom thread into thread carrying means as claimed in claim 1, including the steps of accelerating a turbine spool to a high rotational velocity by applying an air jet to the turbine spool applying torque thereto, and moving the bottom thread into the thread carrying means after the turbine spool has been accelerated to a high rotational velocity for winding the thread in said carrying means.

4. A turbine spool for use in the thread carrying cavity of lockstitch type sewing machines for loading a thread in the cavity by winding thereon comprising turbine vanes for rotating the turbine spool upon the application of an 1 1 air jet thereto, and high friction gripping means enabling the rotating turbine spool to releasably engage the leading portion of a thread loaded into the basket cavity for winding the thread upon the rotating turbine spool.

5. A turbine spool for use in the thread carrying cavity of lockstitch type sewing machines as claimed in claim 4 in which said turbine spool includes a hub formed of slippery plastic material, said hub having an axial opening, said hub being adapted to be freely journaled upon a bearing post mounted within the basket cavity.

6. A turbine spool for use in the thread carrying cavity of lockstitch type sewing machines as claimed in claim 4 wherein said high friction gripping means includes a plurality of small diameter wires extending generally parallel with the axis of rotation and spaced about said axis.

7. A turbine spool for use in the basket cavity of lockstitch type sewing machines for loading the bottom thread of the sewing machine into the basket cavity by winding the bottom thread by means of the turbine spool, said turbine spool comprising a hub, a flange extending outwardly from the hub, a plurality of turbine vanes on said flange on the opposite side thereof from said hub for rotating said flange and hub upon the application of air jet to said vanes, and means for engaging the thread to be wound on said turbine spool.

8. A turbine spool for use in the basket cavity of a lockstitch type of sewing machine as claimed in claim 7, in which said turbine vanes are under cut into said flange and said turbine vanes curve aft with respect to the desired direction of rotation when the viewer traces along the turbine vanes from a point thereon of greater radius from the axis of rotation to a point thereon of lesser radius.

9. A turbine spool for use in the basket cavity of lockstitch type sewing machines for loading the bottom thread of the sewing machine into the basket cavity by winding the bottom thread by means of the turbine spool as claimed in claim 7, in which said turbine spool includes a second flange spaced from the first flange and extending outwardly from said hub, and high friction gripping means in the region between said flanges enabling the rotating turbine spool to releasably engage the leading end portion of the bottom thread loaded into the basket cavity for winding the bottom thread upon the turbine spool in the region between said flanges.

10. A system for loading the bottom thread into the basket cavity of a lockstitch sewing machine of the type having a reciprocatable needle carrying a top thread engageable with the bottom thread extending from the basket cavity to form lockstitches, said system comprising means for supplying a continuous strand of the bottom thread, said supplying means being separate from the top thread, a hollow injection needle having an enclosed bore extending longitudinally within said needle to a free end thereof, movable support means for moving said free end of the injection needle to place said bore into communication with the basket cavity and for retracting said free end therefrom, and means for feeding the bottom thread through said bore into the basket cavity when said free end has been moved to place said bore in communication therewith.

11. A system for loading the bottom thread into the bottom thread carrying means of a sewing machine of the type having a reciprocable sewing needle carrying a top thread engageable with the bottom thread provided by the carrying means to form stitches, comprising means for supplying a continuousstrand of bottom thread, a hollow injection needle having a .thread passage therein terminating at a free end of the injection needle, movable support means for moving the free end of the injection needle into communication with the thread carrying means and for retracting the free end of the needle therefrom, a source of air, and air conducting means flowing air along the thread passage toward the free end of the injection needle 12 for feeding the bottom thread along said passage in the injection needle into the thread carrying means when the free end of the needle is in communication therewith.

12. A system for loading the bottom thread into the bottom thread carrying means of a sewing machine as claimed in claim 11 in which said bottom thread carrying means comprises a freely rotatable turbine spool and turbine vanes for applying torque to said turbine spool, an air jet nozzle directed toward said turbine vanes for rotating said turbine spool at high velocity, and control means for turning on a flow of air to said nozzle for rotating said turbine spool at high velocity to receive the bottom thread from said injection nozzle.

13. A system for loading the bottom thread into the bottom thread carrying means of a sewing machine as claimed in claim 12 in Which the free end of said injection needle is shaped to direct the flowing air from the end of said passage in a direction about the axis of the rotating turbine spool.

14. A system for loading the bottom thread into the bottom thread carrying means of a sewing machine as claimed in claim 11 including clamp means for clamping the bottom thread to hold it in said injection needle passage and for releasing the bottom thread for allowing it to feed through said injection needle.

15. A system for loading the bottom thread into the bottom thread carrying means of a sewing machine as claimed in claim 14 in which said clamp means is controlled in its clamping and releasing conditions by engagement with a member extending near the path of movement of the injection needle, said clamp means being released when the free end of the injection needle is advanced into communication with the thread carrying means, and said clamp means clamping the bottom thread for holding it in the passage upon retraction of the injection needle.

16. A system for loading the bottom thread into the bottom thread carrying means of a sewing machine as claimed in claim 14 in which said system includes a thread cut olf mechanism engageable with the bottom thread extending between the injection needle and the thread carrying means, and actuating mechanism for operating said thread cut off mechanism after the bottom thread has been loaded into the thread carrying means and after said clamp means has clamped the bottom thread to hold it in said injection needle passage following cutting of the thread.

17. A system for loading the bottom thread into the bottom thread carrying means of a sewing machine as claimed in claim 17, in which said thread control mechaing means includes a thread tensioner element, a thread control mechanism engageable with the bottom thread extending between the injection needle and the thread carrying means for positioning the thread adjacent to said tensioner element, and actuating mechanism for operating said thread control mechanism after the bottom thread has been loaded into said thread carrying means.

18. A system for loading the bottom thread into the bottom thread carrying means of a sewing machine as claimed in claim 17, in which said thread control mechanism includes a movable rod, a pivoted lever arm, and a hook arm carried by said movable support means engageable with said lever arm during retraction of said injection needle for positioning the bottom thread near said tensioner element.

19. For use with a sewing machine wherein a thread is carried by a spool in operating position in the sewing machine, the method of loading thread onto the spool while the spool remains in its operating position in the sewing machine comprising the steps of mounting the spool to be freely rotatable, directing a jet of air to apply torque for accelerating the spool into rotation, introducing an end of the thread into the vicinity of the rotating spool for engagement with the rotating spool, and allowing the rotating spool to wind the thread upon itself.

20. For use with a sewing machine wherein a thread is carried by a spool in operating position in the sewing machine, the method of loading thread onto the spool as claimed in claim 19 in which the end of the thread is engaged with the rotating spool by flowing air along a passage toward the rotating spool, and using the flowing air to propel the thread end into position to become engaged by the rotating spool.

21. For use with a sewing machine wherein a bottom thread is carried by a spool located near a stitching needle carrying a top thread which is engaged with the bottom thread to form stitches, the method of replenishing the bottom thread onto the spool while the spool remains in its operating position near the stitching needle in the sewing machine comprising the steps of mounting the spool to be freely rotatable, directing a flow of air accelerating the spool into rotation at high speed, introducing an end of the thread into the vicinity of the spool while it is rotating at high speed, frictionally engaging the bottom thread with the rotating spool, and winding 20 the bottom thread upon the rotating spool by rotation of the spool.

22. In a sewing machine apparatus for replenishing the bottom thread onto a spool located near the stitching needle of the sewing machine comprising a spool adapted to detachably engage the end portion of a thread, means rotatably mounting said spool near the stitching needle, source of bottom thread located remote from said spool, means defining a thread passage directed toward said spool, means for rotating the spool when the sewing ma- 0 chine is inactive and with the spool remaining near the stitching needle, air supply means connected to said thread passage for flowing air along said thread passage toward said spool for moving the thread along said thread passage toward the rotating spool to bring the end portion of the 3 thread into a position to he detachably engaged by the rotating spool and thereafter winding the thread upon the rotating spool, and means for cutting the thread between said spool and said source.

23. In a sewing machine apparatus for replenishing the bottom thread onto a spool located near the stitching needle of the sewing machine as claimed in claim 22 in which said means rotatably mounting said spool includes a basket positioned about the spool and having an opening therein providing access to the spool, said means defining the thread passage being movable, and drive means for moving said passage defining means into alignment with said opening in the basket when the sewing machine is inactive.

24. In a sewing machine apparatus for replenishing the bottom thread onto a spool located near the stitching needle of the sewing machine as claimed in claim 22 including thread tensioning means located near the spool for controlling the bottom thread coming from the spool during stitching, means for clamping the thread for holding the thread taut extending from said thread passage to the spool after thread has been wound thereon, a movable member, and means for moving said member to engage the taut thread between the end of said thread passage and said spool for moving the taut thread along an arcuate path for positioning the thread extending from the spool into operating relationship with said thread tensioning means.

25. In a sewing machine having bottom thread carrying means positioned near the stitching needle, apparatus for loading the bottom thread into the thread carrying means and bringing it into operating position comprising means defining a thread passage directed to said thread carrying means, clamping means for releasably clamping the thread for holding the thread in said thread passage, means for flowing air along said thread passage toward said thread carrying means, means for releasing said clamping means to allow the air flowing along said thread passage to move the thread along said passage into said thread carrying means, thread tensioner means associated with the thread 14 carrying means for tensioning the bottom thread running from the thread carrying means during stitching, means positioning the thread in operating relationship with said thread tensioner means to place the bottom thread in operating position, and means for cutting oif the thread after it has been loaded into said thread carrying means.

26. In a sewing machine having bottom thread carrying means positioned near the stitching needle, apparatus for loading the bottom thread into the thread carrying means as claimed in claim 25, in which said thread passage defining means is movable, said thread passage defining means being retracted from said thread carrying means during stitching operation of the sewing machine, drive means for extending said thread passage defining means to said thread carrying means when the sewing machine is inactive, and said releasing means acting to release the clamping means when said thread passage defining means is extended to said thread carrying means.

27. A method of sewing stitching paths in a multiplicity of workpieces in sequence utilizing a sewing machine having a sewing station including a reciprocatable needle carrying a top thread and having a bottom thread which is engaged with the top thread to form the respective lockstitches of the stitching paths, and wherein the sewing machine has a basket cavity for carrying the bottom thread, said method comprising the steps of metering out from a bulk source a predetermined first length of bottom thread which is just sufiicient to stitch the desired lockstitch path in a first workpiece, injection loading said first length of bottom thread into the basket cavity by feeding said first length of bottom thread into a passage, placing an end of the passage in communication with the basket cavity, and flowing air along the passage to propel said length of bottom thread along the passage into the basket cavity, cutting offsaid predetermined first length from the bulk source after said predetermined length has been injection loaded into the basket cavity, moving the first of said workpieces into the sewing station, operating the sewing machine to stitch said first path, moving the first of said workpieces out of the sewing station, metering out from a bulk source a predetermined second length of the bottom thread which is just sufficient to stitch the desired lockstitch path in a second workpiece, injection loading said second length of bottom thread into the basket cavity 'by feeding said second length of bottom thread into a passage, placing an end of the passage in communication with the basket cavity, and flowing air along said passage to propel said length of bottom thread along the passage into the basket cavity, moving the second of said workpieces into the sewing station, operating the sewing machine to stitch said second path, moving the second of said workpieces out of the sewing station, and so forth to accomplish the stitching paths in the workpieces of the sequence.

28. The method of sewing stitching paths in a multiplicity of workpieces in sequence as claimed in claim 27 including the steps of clamping the metered length of bottom thread to prevent its motion along the passage, and thereafter releasing the metered length of bottom thread to allow the flowing air to propel the released length of bottom thread into the basket cavity.

29. The method of sewing stitching paths in a multiplicity of workpieces in sequence as claimed in claim 27 including the steps of directing an air jet into the basket cavity for accelerating a turbine spool therein to a high rotational velocity before the flowing air propels the metered length of bottom thread into the basket cavity.

30. A method of sewing stitching paths in a multiplicity of workpieces in sequence utilizing a sewing machine having a sewing station including a reciprocatable needle carrying a top thread and having a bottom thread which is engaged with the top thread to form the respective lockstitches of the stitching paths and wherein the sewing machine has a basket cavity for carrying the bottom thread, said method comprising the steps of supplying the bottom thread from a bulk source which is entirely separate from the top thread; operating the sewing machine to reciprocate said needle for stitching the desired lockstitch path in a first workpiece; while said first workpiece is being stitched metering out from said bulk source a predetermined length of said bottom thread and temporarily storing said metered length at a location remote from said basket cavity, said metered length being just sufiicient to stitch the desired lockstitch path in the second workpiece; completing the stitching of said first workpiece; replacing the first workpiece in the sewing station by the second workpiece; while replacing said first workpiece injecting said metered length of bottom thread into the basket cavity and cutting it off from said bulk source; operating the sewing machine to reciprocate said needle for stitching the desired lockstitch path in said second workpiece; While said second workpiece is being stitched metering out from said bulk source a predetermined length of said bottom thread and temporarily storing said metered length at a location remote from said basket cavity, said metered length being just sufiicient to stitch the desired lockstitch path in the third workpiece; completing the stitching of said second workpiece; replacing the second workpiece in the sewing station by the third workpiece; while replacing said second workpiece injecting said metering length of bottom thread into the basket cavity and cutting it off from said bulk source; and so forth to accomplish the stitching paths in the workpieces of the sequence.

31. A method of sewing stitching paths in a multiplicity of workpieces in a sequence as claimed in claim 30 in which said metered length of bottom thread is injected into the basket cavity by feeding it through an elongated passage, placing an end of the passage in communication with the basket cavity, and propelling the metered length of thread along the passage into the cavity.

32. A method of sewing stitching paths in a multiplicity of workpieces in sequence utilizing a sewing machine having a sewing station with a reciprocatable needle carrying a top thread and having means for carrying a bottom thread which is engaged by the top thread to form the respective stitches of the stitching path, said method comprising the steps of feeding the bottom thread from a bulk source entirely separate from said top thread and positioned remote from said bottom thread carrying means and metering out a first length of said bottom thread at a position remote from said bottom thread carrying means, said metered length being suflicient for forming the first stitching path in a first workpiece of the sequence, transporting said first length of bottom thread into said bottom thread carrying means, stitching said first path of lockstitches in said first workpiece using said first length of bottom thread, while stitching said first workpiece metering out a second length of said bottom thread from said bulk source at a position remote from said bottom thread carrying means, said second metered length being sufiicient for forming a second stitching path in a second workpiece of the sequence, transporting said second length of bottom thread into said bottom thread carrying means, stitching said second path of lockstitches in said second workpiece using said second length of bottom thread, and repeating said steps for each of said multiplicity of workpieces for stitching the stitching path in each workpiece.

33. For use with a sewing machine wherein a thread is carried by a spool located in its normal operating position at the lower point of travel of a stitching needle, the method of replenishing the thread onto the spool comprising the steps of mounting the spool to be freely rotatable, directing a flow of air accelerating the spool into rotation at high speed, engaging the thread with the spool, winding the thread upon the rotating spool by rotation of the spool, and maintaining the spool in said normal operating position at the lower point of travel of the stitching needle during said replenishing.

34. The method of replenishing the bottom thread onto a spool in the bottom thread carrying means near the stitching needle of a sewing machine comprising the steps of providing a spool in the bottom thread carrying means which is adapted to be frictionally engaged with the end portion of a thread, providing a bulk source of thread at a location remote from said spool, applying torque to the spool While the spool remains in said thread carrying means near the stitching needle to rotate the spool, moving the end portion by feeding the thread through a pas sage directed toward the rotating spool and flowing air along said passage toward the rotating spool to move the thread, frictionally engaging the end portion of the thread with the rotating spool, winding the thread upon the spool by rotation of the spool as the thread is wound thereon, and cutting the thread to separate the thread which has been wound on said spool from the bulk source.

References Cited UNITED STATES PATENTS 1,978,474 10/1934 Nye.

2,283,393 5/1942 Simons 24226 X 2,836,136 5/1958 Ayres 112-229 2,965,057 12/1960 Lakin 112-231 3,012,530 12/1961 Ketterer 112 186 X 3,075,714- 1/1963 Perraut.

3,331,343 7/1967 Goebel 112-486 3,332,381 7/1967 Dobner 112186 FOREIGN PATENTS 180,873 1/ 1955 Austria.

HERBERT F. ROSS, Primary Examiner US. Cl. X.R.

Images