Patent Publication Number: US-3877405-A

Title: Automatically adjustable apparatus for embroidery stitching

Description:
1451 Apr. 15, 1975 United States Patent 1191 Dorosz et al.  
 [ AUTOMATICALLY ADJUSTABLE APPARATUS FOR EMBROIDERY STITCHING [75] Inventors: Adolph S. Dorosz, Beverly; Reade Williams, Hamilton, both of Mass.  
  Primary Examiner-George H Krizmanich [73] Asslgnee&#39; USM Corporatmn Flemmgton Attorney, Agent, or Firm-Gelling, Ralph D.; Vincent Filed: Feb. 22, 1974 A. White; Richard B. Megley [21] Appl. No.: 444,869  
 [57] ABSTRACT In a machine for intermittently sewing normal stitches and embroidery stitches, means are provided to automatically adjust the thread tension to a lower level and to simultaneously raise the clearance between the 508 5 3 mw 5 1 b5 52 0 m S &#34;2 &#34;n WW in &#34;r ha S L cm l s Umm unc e 555 [56] References Cited lower reach of the presser foot stroke and the work- UNITED STATES PATENTS piece when an embroidery stitch is to be made.  
 2,008,621 7/1935 Mattingly............................ 112/238 8 Claims, 6 Drawing Figures PATENTED APR 1 5197s SHEEThUfQ AUTOMATICALLY ADJUSTABLE APPARATUS IFOR EMBROIDERY STITCHING BACKGROUND OF THE INVENTION Automatically controlled sewing machines generally have a workpiece support table which is mounted for movement along several axes relative to the sewing instruments. The support table is driven by numerically controlled motors which are responsive to signals from a digital control system which generates signals according to a digitized pattern. The workpiece is then moved under the sewing instruments through the desired path. The sewing machine is more or less standard and is operated in coordination with the workpiece support table. This system has proven to provide high speed and accurate stitching in a wide variety of applications.  
  More recently, it has been attempted to provide a dual stitching capability, namely, a machine which can proceed through a pattern which calls for both regular and embroidery stitches interspersed throughout the design. It was found that several problems arose which called for machine adjustment before and after each mode of stitching.  
  Since the embroidery stitch is necessarily of greater bulk, the presser foot, which normally reciprocates be tween two positions in coordination with the needle, binds on the thread at its lower point. In addition, because of the greater length of the embroidery stitch and the loose nature thereof, the standard thread tensions used in normal stitching becomes excessive and cause puckering or tearing of the workpiece.  
 BRIEF DESCRIPTION OF THE INVENTION In order to overcome the problems mentioned above, the apparatus provides adjustable limits in the presser foot stroke so that additional clearance may be created to accommodate the bulkier embroidery stitch. Also, a device is constructed which provides for a multilevel thread tension, thereby allowing for a reduced tension when an embroidery stitch is to be formed. A control system connects these devices for simultaneous actuation when the pattern calls for a change from normal stitching to embroidery stitching or the reverse.  
 BRIEF DESCRIPTION OF THE DRAWINGS The instant invention is more fully described below in conjunction with the attached drawing which shows a preferred embodiment of the invention and in said drawing:  
  FIG. 1 is a perspective overall view of the automatic sewing machine;  
  FIG. 2 is a perspective view of the tension varying apparatus;  
  FIG. 3 is a partial plan view of the tension varying apparatus showing one tension level;  
  FIG. 4 is a partial plan view of the tension varying apparatus showing the second tension level; and  
  FIG. 5 is a perspective view, partially in section, of the presser foot actuating mechanism.  
  FIG. 6 is a block diagram showing the relationship of the control means.  
 THE PREFERRED EMBODIMENT OF THE INVENTION The preferred embodiment of this invention is used in an automatically controlled sewing machine as best shown in FIG. 1. This system consists of sewing machine 1 mounted on platform 2 in operative association with the movable workpiece support table 3. The table 3 is moved under the stitching instruments 4 along tracks 5 and 6 by numerically controlled motors 7 and 8. Control console 9 generates signals to activate motors 7 and 8 to move table 3 through a path determined by a digitized pattern which is supplied to control 9.  
  The sewing instruments 4 generally consist of needle 10, presser foot 11, thread feed 14, and a bobbin assembly (not shown) located underneath the workpiece support table 3.  
  Presser foot 11 is reciprocated by a cam in timed relation with needle 10 and may be retracted at the end of the sewing operation by air cylinder 12. Generally, presser foot 11 has an opening 13 through which needle 10 passes during the stitching operation.  
  Thread feed 14 consists of a variety of eyes and pulleys and generally guides thread 15 from a supply spool (not shown) through a variable tension device 16 to the needle 10.  
  The presser foot 11 (FIG. 5) reciprocates through a stroke indicated by dotted lines 17 and 18, the line 18 indicating the lowermost reach of the presser foot. When the presser foot is in its lowermost position, there is only a slight clearance between it and the workpiece. This enables the foot to engage the workpiece, thereby facilitating the withdrawal of the needle therefrom. In some applications the presser foot 11 may not reciprocate but only be lowered into engagement with the workpiece and retracted atthe end of the operation. As part of this invention, it is desirable, when embroidery stitches are to be formed, to raise the lowermost position 18 of the presser foot to provide a greater clearance with the workpiece. In order to accomplish this, a mechanical stop 19 is provided to limit the downward stroke of the presser foot. This stop is engaged by a lug 20 on support bar 21 when the desired lowermost point is reached. The stop 19 is mounted for sliding motion between two positions by air cylinder 22. Each of the positions provides a different limit to the stoke of the presser foot, thereby varying the clearance between the lower reach of the presser foot and the workpiece. As indicated above, it is desirable to raise this clearance when embroidery is to be performed. Adjustment knob 23 may be provided to allow the operator to vary the movement of the stop.  
  The variable tension device 16 (see also FIG. 2) is comprised of the well-known rotary type tension source in which the thread 15 runs about a pulley 35 which is frictionally engaged by a brake operated through plunger 24 to create tension on thread 15 as it is supplied to the needle 11. The tension created by the device 16 may be varied by pressing on plunger 24 to exert greater force on pulley 35. The plunger 24 is actuated by a lever 25 which is pivotally mounted at 26 on mounting bracket 27. Air cylinders 28 and 29 are mounted on bracket 27 with their piston shafts and 31, respectively, extending outward to operatively engage lever 25. It is observed that the operation of air cylinder 28 will cause a specific amount of pivotal movement of the lever which, in turn, will apply a specific force to plunger 24, thereby creating a specific tension level on the thread. This is also true of the operation of air cylinder 29 which will, in turn, create a second tension level on the thread by pivoting lever 25. Of course. lever 25 may be disengaged from plunger 24,  
 thereby creating a third tension level. A plurality of tensions can be conveniently supplied in this manner.  
  In the preferred embodiment, an adjustable mechanical stop 32 is provided to limit the movement of lever 25. Operation therefore of air cylinder 28 will pivot lever 25 until U-bracket 33 abuts stop 32. Since lever 25 extends into the channel 34 of the U-bracket 33, it is free to pivot further, upon operation of air cylinder 29, until it abuts stop 32. It is, therefore, possible to vary the tension levels provided by adjusting stop 32.  
  This apparatus may be also applied to a standard disk type tension device (not shown) wherein the thread is frictionally engaged between two disks. The force exerted by the disks may be varied by a plunger similar to the plunger 24 described herein.  
  Air cylinders 12, 22, 28 and 29 are connected to a source of air, as shown in the block diagram of FIG. 6, by standard electrically controlled valves which control the flow of air to the cylinders. These valves may be made responsive to a control signal which may be generated by the automatic control system when a change in stitching mode is to be inserted in the pattern. The air cyliinders 12, 22, 28 and 29 may also be any suitably controlled devices, for example, fluid, hydraulic or solenoid operated cylinders.  
  In operation, the control input to the console 9 includes information which triggers a signal when a change in stitching style is directed. These signals are applied to the air cylinders 22 and 29 to simultaneously adjust the presser foot clearance and the thread tension to accommodate the bulkier and looser embroidery stitches. These actuators revert back to normal when the control signal so indicates.  
  It can readily be observed that a great many combinations of clearances and tensions may be accomplished by the use of this apparatus.  
 We claim:  
  1. In an automatically controlled sewing machine having apparatus to intermittently form different types of stitches in a workpiece, means are provided to automatically adjust the sewing machine to accommodate the different characteristics of the stitching modes, said adjusting means comprising:  
 A. Control means for generating a signal when the stitching mode is to change;  
 B. A presser foot mounted on the sewing machine for movement toward the workpiece;  
 C. A stop element operatively connected to the presser foot to limit its movement;  
 D. Means connected to the stop element to vary the position thereof in response to the signal from the control means;  
 E. A variable tension device engaging the thread; and  
 F. Actuating means to adjust the tension device in response to the signal from the control means.  
  2. In an automatically controlled sewing machine having apparatus to intermittently form different types of stitches in a workpiece, means are provided to automatically adjust the sewing machine to accommodate the different characteristics of the stitching modes, as described in claim 1, wherein the means for varying the position of the stop element comprises:  
 A. A fluid actuated piston operatively connected to the stop element to move said element between two positions; and  
 B. valve means connected to control the flow of fluid to the piston to actuate the change of stop element position in response to the signal from the control means.  
  3. In an automatically controlled sewing machine having apparatus to intermittently form different types of stitches in a workpiece, means are provided to automatically adjust the sewing machine to accommodate the different characteristics of the stitching modes, as described in claim 2, wherein the two positions are such that more clearance is provided between the stitches and the presser foot when the machine is forming embroidery stitches.  
  4. In an automatically controlled sewing machine having apparatus to intermittently form different types of stitches in a workpiece, means are provided to automatically adjust the sewing machine to accommodate the different characteristics of the stitching modes, as described in claim 1, wherein the variable tension device and the associated actuating means comprise:  
 A. A variable tension device engaging the thread as it is supplied to the needle, said tension device having a plunger for changing the tension on the thread when pressure is applied to said plunger;  
 B. A lever pivotally mounted on the sewing machine for engagement with the tension varying plunger at one end of the lever;  
 C. Fluid piston actuating means operatively connected to pivot the lever in order to apply pressure to the plunger; and  
 D. Valve means connected to control the flow of fluid to the piston to actuate the change in thread tension in response to the signal from the control means.  
  5. In an automatically controlled sewing machine having apparatus to intermittently form different types of stitches in a workpiece, means are provided to automatically adjust the sewing machine to accommodate the different characteristics of the stitching modes, as described in claim 4, wherein the fluid piston actuating means comprises two pistons operatively connected at different positions along the length of the lever to pivot the lever against the plunger, said pistons being positioned to provide at least two levels of tension, one of which providing a relatively low level when the machine is forming embroidery stitches.  
  6. In an automatically controlled sewing machine having apparatus to intermittently form different types of stitches in a workpiece, means are provided to automatically adjust the sewing machine to accommodate the different characteristics of the stitching modes, said adjusting means comprising:  
 A. Control means for generating a signal when the stitching mode is to change;  
 B. A presser foot mounted on the sewing machine for movement toward the workpiece;  
 C. A stop element operatively connected to the presser foot to limit its movement;  
 D. A fluid actuated piston operatively connected to the stop element to move said element between two positions, one position providing a greater clearance between the presser foot and the stitches; and  
 E. Valve means connected to control the flow of fluid to the piston to change the position of the presser foot in response to the signal from the control means.  
 7. In an automatically controlled sewing machine having apparatus to intermittently form different types of stitches in a workpiece, means are provided to automatically adjust the sewing machine to accommodate the different characteristics of the stitching modes, said adjusting means comprising:  
 A. Control means for generating a signal when the stitching mode is to change;  
 B. A variable tension device engaging the thread as it is supplied to the needle, said tension device having a plunger for changing the tension on the thread when pressure is applied thereto;  
 C. A lever pivotally mounted on the sewing machine for engagement with the tension varying plunger at one end of the lever;  
 D. Fluid piston actuating means operatively connected to pivot the lever in order to apply pressure to the plunger; and  
 E. Valve means connected to control the flow of fluid to the piston to actuate the change in thread tension in response to the signal from the control means.  
  8. In an automatically controlled sewing machine having apparatus to intermittently form normal and embroidery stitches in a workpiece, means are provided to automatically adjust the sewing machine to accommodate the different characteristics of the stitching modes, said adjusting means comprising:  
 A. Control means for generating a signal when the stitching mode is to change;  
 B. A presser foot mounted on the sewing machine for movement toward the workpiece;  
 C, A stop element operatively connected to the presser foot to limit its movement;  
 D. First fluid actuated piston means operatively connected to the stop element to move said element between two positions, one position providing a greater clearance between the presser foot and the stitches;  
 E. First valve means connected to control the flow of fluid to the first piston means to change the position of the presser foot in response to the signal from the control means;  
 F. A variable tension device engaging the thread as it is supplied to the needle, said tension device having a plunger for changing the tension on the thread when pressure is applied thereto;  
 G. A lever ppivotally mounted on the sewing machine for engagement with the tension varying plunger at one end of the lever;  
 H. Second fluid actuated piston means operatively Second valve means connected to control the flow of fluid to the second piston means to cause a change in thread tension in response to the signal from the control means.