US3827381A

US3827381A - Automatic sewing machine control having a manually controlled operating sequence

Info

Publication number: US3827381A
Application number: US00224676A
Authority: US
Inventors: T Baanstra; Hagen W Von; W Niem
Original assignee: Union Special GmbH
Current assignee: Union Special GmbH
Priority date: 1971-02-16
Filing date: 1972-02-09
Publication date: 1974-08-06
Anticipated expiration: 1991-08-06
Also published as: FR2125935A5; DE2107351A1; NL7200943A; IT949736B; GB1384273A; CH541651A

Abstract

This disclosure relates to an automatic control for a sewing machine which will effect the automatic controlling of the operation of the sewing machine at both the leading and trailing edge of a workpiece while at the same time permitting a manually controlled operating sequence during other portions of the sewing cycle which will in no way affect the automatically controlled operations.

Description

United States Patent [191 Baanstra et al.

[ AUTOMATIC SEWING MACHINE CONTROL HAVING A MANUALLY CONTROLLED OPERATING SEQUENCE [75] lnventors: Theo Meindert Baanstra,

Warmbronn; Wolf-Riidiger Von Hagen, Grotzingen; Wolfgang Niem, Leonberg, all of Germany [73] Assignees Union Special Maschinenfabrik G.m.b.II., Stuttgart, Germany [22] Filed: Feb. 9, 1972 [21] Appl. No.1 224,676

[30] Foreign Application Priority Data Feb. 16, 1971 Germany 2107351 [52] U.S. Cl ll2/l2l.ll, 112/210, 112/262 [51] Int. Cl D05b 19/00 [58] Field ofSearch ll2/121.11,l2l.15,219A, 112/220, 210, 262; 318/284; 192/146, 84 P,

[ Aug. 6, 1974 2,483,138 9/1949 Helmer 112/219 A 3,174,450 3/1965 Becker et a1 112/219 A 3,363.594 1/1968 Kosrow 112/210 3,367,296 2/1968 Harruff. 112/219 A 3,468,273 9/1969 Lester... 112/262 3,654,882 4/1972 Kamena 112/121.ll

Primary Examiner-James R. Boler Assistant Examiner-Peter Nerbun Attorney, Agent, or Firm-Diller, Brown, Ramik & Wight [5 7] ABSTRACT This disclosure relates to an automatic control for a sewing machine which will effect the automatic controlling of the operation of the sewing machine at both the leading and trailing edge of a workpiece while at the same time permitting a manually controlled operating sequence during other portions of the sewing cycle which will in no way affect the automatically controlled operations.

14 Claims, 2 Drawing Figures I 26 We 07o o-Z o-4 AUTOMATIC SEWING MACHINE CONTROL HAVING A MANUALLY CONTROLLED OPERATING SEQUENCE The invention relates to a control mechanism for controlling the operation of a sewing machine and includes means for scanning the seam being sewn and automatically release a control impulse that deliberately switches on a control arrangement for an automatic sewing operation while permitting a manually controlled operating sequence during other portions of the sewing cycle.

BACKGROUND OF THE INVENTION fore these arrangements have not proven to be fully sat- 2 isfactory.

For example, in the past there has been provided arrangements for the automatic locking of a seam by producing a locking stitch at the beginning of the seam upon switching on of the sewing machine by means of a servo-arrangement and to permit a repetition of the initial locking stitch only after operation of a control switch at the end of the seam. According to another proposal, the production of the final locking stitch is followed still by cutting off the threads and by lifting the presser foot, whereby the final locking stitch is made and the succeeding controls take place after the machine is stopped. In the case of manual control of these arrangements, it is still relatively simple for the seamstress to make the locking stitch deliberately at the beginning of the seam, since the seamstress can place the edge of the material while the machine is at rest, after which she can initiate the operation of the machine.

It is, however, difficult to place the locking stitch at the end of the seam precisely at the trailing edge of the material. The seamstress must feel her way up to this edge and must operate the release switch at the correct distance, whereby she must synchronize precisely the inertia of the switching elements with the then prevailing number of stitches and length of the stitches in order to achieve a reversal of the feed mechanism after reaching the edge of the material. The same is true also for cutting mechanisms for trimmings being sewn to the fabric. In the case of cutting mechanisms, the trimming as a rule is cut with an excess beyond the edge in order to prevent the fabric being out should the cutting process be initiated too early.

Proposals have been made for switching on such mechanisms by means of automatic switching arrangements, for example, photoelectric cells, which will scan the seam. Such switching mechanisms are just as much dependent on time. With these arrangements it is also left to the skill of the seamstress to select the sewing speed in coordination with the length of the stitch in such a way that at a predetermined distance of the scanning device from the end of the seam, the inertia of the switching elements is compensated for in such a manner that the shifting of the elements that are to be switched on will take place precisely at the end of the seam. The difficulty arising here becomes quite evident when it is considered that in the case of a fairly customary speed of 6,000 stitches per minute, one stitch is produced in one one-hundreth of a second.

SUMMARY OF THE INVENTION The primary object of this invention is to provide a mechanism for the scanning of the seam and for the automatic release of a control impulse for the deliberate switching on of a control device in the case of a sewing machine having a manually controlled operating sequence, which releases the seamstress of the heretofore required concentration of a precise switching on of the control device.

Essentially this object is achieved through the provisions of a second switching element for switching on a predetermined speed of the sewing machine in conjunction with a mechanism for scanning of the seam and for triggering a switching device, which second switching element will allow the control impulse of the scanning arrangement to become effective only in the 5 switched on state. A preferred embodiment is characterized in that the second switching element is a switching element that is to be operated arbitrarily by the seamstress.

By means of this additional switching element, according to the present invention, the speed of the driving motor of the sewing machine is adjusted just before the end of the seam to a predetermined constant low level, after which the scanning device will assure a perfect sewing of the seam up to the trailing edge of the material. As a result of such an arrangement, it will be possible, for example, to cut a trimming even with the edge of the material, or a locking stitching process will be performed which will place the locking stitch precisely on the edge of the material without any need for special concentration on the part of the seamstress. At the same time", the additional switching element can be a switch that may be operated arbitrarily by the seamstress or may be in the form of an automatic detector, such as a light or air barrier type.

Preferably, a switch that is to be controlled by a second switching element is located in a circuit arranged parallel to a switch controlled by the scanning device. These parallel circuits are part of a holding circuit of a relay which is energized at the beginning of the sewing process through the switching on of the control mechanism. The relay has alternating contacts for the alternate switching on of control devices at the beginning of the seam and/or the end of the seam.

The mechanism according to the invention not only permits the triggering of the control process precisely at the edge of the material without special concentration by the seamstress, but, in addition, it prevents the triggering of the switching process in the case of an unintentional release of the switching impulse by the scanning device or an unintentional operation of the switch that is to be switched manually.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings:

In the Drawings:

FIG. 1 is a schematic view of the control mechanism wherein the seamstress manually sets the machine to operate at a predetermined speed along a trailing portion of the material.

FIG. 2 is a fragmentary schematic view similar to FIG. 1 and shows a detector for setting the speed mechanism at a predetermined rate along a terminal portion of the sewing cycle.

Although the control mechanism of the invention may be utilized in conjunction with different machines and in different manners in conjunction with a sewing machine, only the specific application of the control mechanism in conjunction with a sewing cycle and the locking of the seam at the beginning and end of the seam have been illustrated in the drawing and will be described in detail here.

With reference to FIG. 1, it will be seen that there has been schematically illustrated a conventional sewing machine 1 which is driven in the customary manner by means of a drive belt 2, which may be a V-belt, which connects a belt pulley 3 of the sewing machine with a belt pulley 4 carried by a shaft 5 of a motor 6. The motor 6, which is shown only by way of example, is a motor that can be regulated as to speed. The motor 6 has been connected with a control pedal 9 through a connecting rod 8 in order to regulate the speed thereof.

The sewing machine 1 carries, in a conventional manner, a rotary solenoid or magnet 11 on a shaft 12, which when energized, will change the direction of operation of the customary feed mechanism of the sewing machine 1. At this time it is pointed out that in lieu of the rotary solenoid or magnet 11, a solenoid or magnet of the direct pull type or other servo devices can be utilized.

The electrical circuitry of the control mechanism includes two

switches

13 and 14 which alternately open or close depending upon the operating position of the pedal 9. The switch 13 is normally open while the switch 14 is normally closed and forms part of an automatic holding circuit of a relay 15. In this automatic holding circuit there is also a switch contact 16 the position of which is controlled by the relay 15. Relay also controls the position of a switch contact 17 which forms part of a circuit for a switch counter 18 which is connected to the rotary solenoid or magnet 11. Another switching contact 19 controlled by the relay 15 forms part of a circuit for a stitch counter 21 which is also connected to the magnet 11.

Parallel with the circuit containing the switch 14 there is another circuit which includes a switch contact 22 controlled by a relay 23. The relay 23 is in turn controlled by a scanning device in the form of a photoelectric cell 24 mounted at the head of the sewing machine 1. The electrical circuitry also includes

switches

25,26 and 27 which serve to open the respective circuit of which each is a part and each may be separately manually controlled.

In the starting position of the sewing machine controls, the relay 15 is not energized and the

switching contacts

16 and 19 are open while the switching contact 17 is closed. When the seamstress depresses the pedal 9 to rotate in a counterclockwise direction at the beginning of a sewing cycle, switch 13 is moved to a closed position and as a result the circuit to the relay 15 is completed with relay 15 being energized and In accordance with the foregoing, the stitch counter is switched on with the switching on of the sewing process. It is to be understood that the material to be sewn is first positioned by the seamstress relative to the customary needle and presser foot of the sewing machine and that the stitch counter 21 is programmed so that after a predetermined number of stitches have been formed, it will energize the rotary magnet or solenoid 11 to effect a reverse feeding of the material. The stitch counter 21 is programmed so as to form the same number of stitches in a reverse direction as previously formed in a forward direction, after which the rotary magnet 11 will be de-energized and the sewing operation on the material will proceed in a customary manner. Thus, the stitch counter 21 will effect the forming of the desired locking stitch at the leading edge of the fabric.

When switch 13 closes and energizes relay 15, the contact 16 also closes, as described above, completing two holding circuits through which relay 15 remains energized independently of whether the switch 13 is closed or open. One holding circuit is through the switch 14 and the switch contact 16 while the other holding circuit is through the switch 25 and

switch contacts

22 and 16. Thus, it is possible to stop the sewing operation any time during the sewing cycle and to start again without triggering any kind of automatic sewing process such as a locking stitch sewing process.

As the trailing edge of the fabric approaches the needle, the seamstress will open switch 14 by pushing back on pedal 9 to pivot the same in a clockwise direction. As a result of such movement, a predetermined motor speed is set through the movement of the rod 8. While the sewing machine 1 operates at this preselected speed, the edge of the fabric passes by the photoelectric cell 24 with the result that the energization of the relay 23 will be changed so as to move the switch contact 22 to an open position. Thus, the second of the holding circuits for the relay 15 opens and the relay 15 is de-energized.

When the relay 15 is de-energized, switch contact 17 again closes while switch

contacts

16 and 19 open. The closing of switch contact 17 completes the circuit through stitch counter 18 causing energization of the rotary magnet or solenoid 11. The timing is such that as the needle of the sewing machine 1 makes the last stitch in the material, the feed direction of the material is reversed and the stitching is in a reverse direction for a predetermined number of stitches as determined by the stitch counter 18.

It is also to be understood at this time that the switch counter 18, which is of a conventional construction, may also stop the operation of the sewing machine 1 after the predetermined number of locking stitches have been formed, and thereafter actuate a thread cutter (not shown) and the presser foot lifter (not shown) of the sewing machine in the customary manner. It is further to be understood that if the operation of the sewing machine 1 is such that trimming is being sewn to the workpiece, the stitch counter 18, at the time it energizes the magnet 11, could also actuate a trimming cutter (not shown) to accurately sever the trimming even with the edge of the material.

It is to be understood that with the switching arrangement illustrated and described, a time constant from triggering of the switching impulse in the photoelectric cell to the reaching of the needle path by the edge of the fabric, has been predetermined on the basis of the preselected speed of the motor 6 and the sewing machine 1 is driven thereby, which time constant also makes possible the accomplishment of the actuation of control elements, including the magnet 11 by RC elements instead of by means of the stitch counters. It is to be understood that for this purpose it naturally is necessary that the speed of the motor 6 up to the dropping off of the RC element must also be predetermined at the beginning of the seam.

It is further to be understood that instead of electric switches, pneumatic switches with the same function could be utilized.

At this time it is particularly pointed out that the stitch counters 18 and 21 are conventional and therefore, the specific details thereof have not been illustrated nor described herein. It is to be understood that if the stitch counters l8 and 21 do work on a time cycle, as set forth above, then they do not need to be directly connected to the sewing machine 1. On the other hand, if the stitch counters 18,21 actually do count the actuation of the sewing machine in the formation of stitches, it will be necessary that the stitch counters 18,21 be mechanically or electronically associated with the sewing machine 1 in a positive manner, which manner is conventional in the art.

Reference is now made to FIG. 2 wherein it is shown that the switch 14 can be controlled by a detector 31 which may be of any conventional type, including a photoelectric cell, air detector, etc. The detector 31 may be operatively associated with the switch 14 for actuating the same in any desired manner. At the same time, it may be operatively associated with the speed control for the motor 6 so as to automatically change the speed of the motor 6 to the predetermined speed. For simplicity of illustration, a solenoid 33 has been shown operatively associated with the pedal 9 to automatically pivot the pedal 9 in a clockwise direction so as to automatically accomplish that which is normally manually accomplished by the seamstress as the trailing edge of the material approaches the needle of the sewing machine.

It is to be understood that the detector 31 must be positioned sufficiently in advance of the scanner 24 so that adjustment of the sewing machine to the predetermined constant speed will be permitted before the scanner 24 turns on the thread counter 18 or other mechanisms controlled thereby.

Although the invention has been specifically illustrated and described in conjunction with a sewing machine, it is to be understood that the control mechanism may be utilized in other environments and minor variations may be made therein without departing from the spirit and scope of the invention, as defined in the appended claims.

We claim:

1. A control mechanism for controlling operations on a terminal edge portion of a moving workpiece by a machine, said control mechanism including an operator actuated speed control mechanism for controlling the speed of operation of the machine with said speed control mechanism having an operator controlled position for the operation of said machine at a predetermined speed, a control device for automatically controlling the operation of said machine during a terminal portion of an operating cycle thereof, detector means for detecting the arrival of a trailing edge of a workpiece at a predetermined position, and control means for actuating said control device only when an operator has placed said speed control mechanism in said predetermined speed position and the trailing edge is detected as reaching said predetermined position.

2. The control mechanism of claim 1 wherein said control means includes an electrical circuit having a switching element controlled by said detector means.

3. A control mechanism for controlling operations on a terminal edge portion of a moving workpiece by a machine, said control mechanism including a speed control mechanism for controlling the speed of operation of the machine with said speed control mechanism having a position for the operation of said machine at a predetermined speed, a control device for automatically controlling the operation of said machine during a terminal portion of an operating cycle thereof, detector means for detecting the arrival of a trailing edge of a workpiece at a predetermined position, and control means for actuating said control device only when said speed control mechanism is in said predetermined speed position and the trailing edge is detected as reaching said predetermined position, said control means including an electrical circuit having a first switching element controlled by said detector means and a second switching element positioned in accordance with the setting of said speed control mechanism in said predetermined speed position.

4. The control mechanism of claim 3 wherein said first and second switching elements are disposed in parallel circuits.

5. The control mechanism of claim 4 wherein actuation of said control device is controlled by a switching element actuated by a relay, and said parallel circuits are holding circuits for said relay.

6. The control mechanism of claim 5 wherein said speed control mechanism has a manually operable position, and said relay has an energizing circuit under the control of said speed control mechanism in the manually operable position thereof.

7. The control mechanism of claim 6 wherein said relay controls the position of another switching element in said holding circuits.

8. The control mechanism of claim 5 wherein there is another control device for controlling the operation of said machine at a leading edge of a workpiece, said relay controlling the position of a further switching element in a control circuit for said another control device.

9. The control mechanism of claim 8 wherein said machine is a sewing machine and has a reverse feed control device, and said another control device is operatively connected to said reverse feed control device and is operable upon the initiation of a sewing cycle to permit a workpiece to advance a predetermined number of stitches, then to operate said reverse feed control device for a predetermined number of stitches, and then to permit the sewing operation to proceed normally under the manual control of an operator.

10. The control mechanism of claim 9 wherein the first mentioned control device is also operatively connected to said reverse feed control device and is operable when energized to effect a reverse workpiece feeding'for a predetermined number of stitches.

11. The control mechanism of claim 8 wherein said speed control mechanism has a manually controllable position wherein said machine may be operated at varying speeds under the control of an operator, said relay has an energizing circuit including a switch element closable when said speed control mechanism is in said manually controllable position, and said holding circuits permitting said speed control mechanism to be selectively actuated in a normal manner during a sewing cycle without effecting the energization of said relay or the operation of said control devices after the initiation of a sewing cycle.

12. The control mechanism of claim 1 wherein said trol mechanism to said predetermined speed position. i

Claims

10. The control mechanism of claim 9 wherein the first mentioned control device is also operatively connected to said reverse feed control device and is operable when energized to effect a reverse workpiece feeding for a predetermined number of stitches.

12. The control mechanism of claim 1 wherein said speed control mechanism has a manually controllable position wherein said machine may be operated under normal conditions at varying speeds.

13. The control mechanism of claim 1 wherein said detector means includes a scanning device.

14. The control mechanism of claim 1 wherein said control means includes an electrical circuit having a first switching element controlled by said detector means and a second switching element, and a second detector means operable in accordance with the position of a workpiece trailing edge for positioning said second switching element and moving said speed control mechanism to said predetermined speed position.