US3400675A - Single cycle starting control system for sewing machines - Google Patents

Description

Se t. 10, 1968 J. A.-RAUDONIS, JR 3,400,675

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1Q.. d/nbo' Jglleefl AT RNEY United States Patent O 3,400,675 SINGLE CYCLE STARTING CONTROL SYSTEM FOR SEWING MACHINES John A. Raudonis, Jr., Elizabeth, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed June 8, 1967, Ser. No. 644,510 2 Claims. (Cl. 112--67) ABSTRACT OF THE DISCLOSURE A fluid operated control system for initiating the cycle starting and lifting of the work clamp of a cyclic sewing machine is disclosed in which an operators control initiates starting of the machine by way of a normally open time-delayed closing interlock fluid valve which automatically closes after each sewing machine start and remains closed until the operators control is deactivated in order to prevent machine operation for more than a single cycle for each actuation of the operators control.

SUMMARY OF THE INVENTION This invention relates to operator assist devices for controlling the cycle starting of sewing machines as well as the operation of devices ancillary to the sewing instrumentalities such as the lifting and lowering of a work holding clamp.

A problem which arises with such control devices when used with a cyclic sewing machine having a short cycle, such as a button sewing machine or certain tacking machines, is that the cycle of sewing machine operation is of such short duration that it is diflicult for an operator to discontinue the starting signal before the machine has operated through a cycle and as a result, a plurality of cycles rather than the desired single cycle is frequently obtained.

The present invention provides an operator influenced fluid operated control system for initiating cycle starting of a sewing machine which can also serve to actuate an ancillary device such "as lifting of a work clamp between cycles, and which includes in the sewing machine cycle starting control an automatically effective fluid interlock serving to prevent operation of the sewing machine beyond a single cycle of operation until the operator has released and again signaled for a subsequent cycle of operation.

In the preferred embodiment illustrated in the drawings, the fluid interlock is provided by a normally open time delayed closing fluid valve arranged in the fluid supply line leading to the fluid operated device for initiating sewing machine cycle starting. By preselecting a time delay of the fluid valve shorter than the cycle of operation of the sewing machine, a single cycle of machine operation for each operator influenced starting signal is insured.

DESCRIPTION OF THE DRAWINGS With the above and additional objects and advantages in view as will hereinafter appear, this invention will be described below with reference to the accompanying drawing of a preferred embodiment in which:

FIG. 1 is a diagrammatic view of a sewing machine control system embodying this invention with the elements of the system illustrated in a condition in which the sewing machine is stopped and the sewing machine work clamp is being held open by the control system,

FIG. 2 is a view like FIG. 1 but with the elements of the system illustrated in a condition in which the sewing machine is stopped and the work clamp is closed,

FIG. 3 is a view like FIG. 1 but with the elements of the system illustrated in a condition in which cycle starting of the sewing machine is initiated by the control system, and

FIG. 4 is a view like FIG. 3 but showing the time delayed closing of the normally open interlock valve during the cyclic operation of the sewing machine.

DETAILED DESCRIPTION The control system of this invention is illustrated in the accompanying drawing as applied to a conventional cyclic sewing machine which includes a needle 11 which is adapted to be reciprocated relatively to a work support 12 by a drive shaft 13. Indicated generally at 14 are stitch forming instrumentalities also adapted to be actuated by the drive shaft 13 in timed relation with the needle. A work clamp 15 is shiftably supported on the sewing machine for movement into and out of a Work clamping position contiguous to the sewing machine work support 12 and biased into work clamping position by a. spring 16. A work clamp lifting linkage is represented by a lever 17 fulcrumed on the sewing machine.

The driving mechanism of the sewing machine includes a driven clutch element 20 on the drive shaft 13, and a driving clutch element 21 operatively connected to a drive motor 22 and shiftable into and out of engagement with the driven clutch element 20 in response to movement of a control lever 23 fulcrumed on the sewing machine. A latch lug 24 on the control lever 23 is engageable by a latch element 25 for detaining the control lever 23 in the engaged condition of the clutch elements 20 and 21 until the latch element is released by conventional stop motion mechanism of the sewing machine after a stitching cycle of predetermined number of stitches has been completed. A spring 26 biases the control lever 23 toward the declutch position of elements 20 and 21.

The control system of this invention utilizes a fluid pressure operated motor comprising a piston 30 movable in a cylinder 31 to raise and lower the work clamp. A connecting rod 32 affixed to the piston is pivoted to the clamp operating lever 17 and a spring 33 acting upon the piston 30 biases the piston toward the lowered position of the work clamp. Another fluid pressure operated motor comprising a piston 35 movable in a cylinder 36 is utilized to initiate starting of a sewing cycle. A connecting rod 37 aflixed to the piston 35 is pivoted to the control lever 23 and a spring 38 acting upon the piston 35 biases the piston toward the declutched position of the elements 20 and 21.

While any fluid medium may be used to operate the control system of this invention the preferred form as illustrated in the drawing utilizes compressed air. From a source (not shown) compressed air admitted through a pressure regulating valve 39 to a conduit 40 leading to an operator influenced normally open valve 41 operated by a plunger 42, and to a conduit 43 leading to a normally closed interlock valve 44 operated by a plunger 45 which is disposed in the path of a cam 46 fast on the clamp opening piston rod 32. A conduit 47 leads from the interlock valve 44 to a normally closed operator influenced valve 48 operated by a plunger 49. Under the influence of a sewing machine operator, as by way of a treadle 50, or the like, is a valve control cam 51 adapted to engage the valve plungers 42 and 49. A spring 52 biases the treadle into a first position illustrated in FIG. 1 in which the cam 51 is out of engagement with both valve plungers 42 and 49.

From the normally open valve 41, a conduit is directed to a normally open valve 61 operated by a plunger 62 which is arranged in the path of a control cam 63 carried on the connecting rod 37 of the piston 35 which influences the initiation of sewing cycles. As illustrated I 3 in FIG. 1 when clutch elements and 21 of the sewing machine are disengaged and the piston 35 is biased into the returned position by the spring 38, the control cam 63 will be out of engagement with the plunger of the normally open valve 61 and a conduit 64 from the valve 61 to the cylinder 31 will direct compressed air from the source to the piston opening the work clamp 15.

FIG. 2 illustrate-s a second or intermediate position of the treadle 50 in which the control cam 51 associated therewith has been shifted into engagement with the plunger 42 to close the valve 41. No compressed air will be supplied to the cylinder 31 and the piston 30 will be returned by the spring 33 allowing the work clamp 15 to close. If the operator should then release the treadle 46 for return to the first position, the valve 41 will be reopened and the work clamp will be raised by the piston 30 as illustrated in FIG. 1. The transition as between the conditions illustrated in FIGS. 1 and 2 is reversible and the operator may open and close the work clamp as many times as is necessary until she is satisfied that work is properly orientated therein.

FIG. 3 illustrates the position of the parts after the operator has fully depressed the treadle 50 into the third position. The control cam 51 will then shift to a position engaging both plungers 42 and 49 thus holding closed the valve 41 to cut off compressed air from the work clamp opening cylinder 31 and opening the valve 48.

When the piston 30 in the work clamp opening cylinder 31 is returned by the spring 33, the cam 46 will engage the plunger 45 and hold open the normally closed valve 44 admitting compressed air from the supply to the conduit 47 and to the operator influenced valve 48. A conduit 70 leads from the operator influenced valve 48 to a normally open time delay closing three port, two position air valve indicated generally at 71. From the valve 71, a conduit 72 leads to the sewing cycle starting cylinder 36.

As illustrated diagrammatically in the drawing, the valve 71 is shiftable between two positions relatively to the conduits 70 and 72. A spring 73 normally biases the valve into a position illustrated in FIGS. 1, 2 and 3 in which a chamber 74 occupies an effective position establishing communication between the conduits 70 and 72. A second position, as illustrated in FIG. 4 is effected by an air cylinder 75 supplied from the conduit 70 by a conduit 76 having a throttle valve 77. The air cylinder 75 serves to shift a chamber 78 into an effective position in which the passage between the conduits 70 and 72 is blocked and the conduit 72 is exhausted to the atmosphere. The shiftable chamber 78 in conjunction with the air cylinder 75 constitutes an auxiliary fluid pressure operated motor for operating the valv 71 after a time delay. The shift into the second position, however, is only effective after a time delay occasioned by filling of the air cylinder 75. An adjustable plunger 79 is provided in the air cylinder 75 to vary the size of the reservoir represented by the air cylinder 75 thus to vary the time delay prior to closing of the conduits 70 and 72 after admission of pressure to the conduit 70.

When air under pressure is admitted to th cylinder 36 by way of the normally open position of the valve 71, the piston will be depressed shifting the sewing machine starting lever 23 into the running position illustrated in FIG. 3 in which position the latch 24, 25 will retain the parts until the sewing machine signals completion of a sewing cycle by releasing the latch. While the sewing machine is running the latch 24, 25 will also hold the piston 35 depressed and the control cam 63 will be in engagement with the plunger 62 of the valve 61 holding the valve 61 closed. If the operator should release the treadle 50 before the termination of a sewing cycle, the the latch 24, 25 will maintain operation of the sewing machine and the control cam 63 will maintain the interlock valve 61 closed to prevent opening of the work clamp despite the return of the operator influenced valve 41 to the normally open position. If the treadle 50 is re- 4 leased before the conclusion of a sewing-cycle, the operator influenced valve 48 will also return to the normally closed position and the time delay valve 71 will revert to the normally ope-n position illustrated in FIG. 1.

When a sewing machine is employed such as button sewing machine or tacker having only a few stitches in each cycle of operation, the cycle can be completed in such a short time that the operator cannot always release the treadle 50 prior to completion of one sewing cycle and as a result two or more successive cycles may be formed producing a noticeable defect in the stitched article.

The plunger 79 of the valve 71 in this invention is preferably adjusted so as to provide a time delay in the operation of thevalve 71 which is shorter in duration than the cycle time of the sewing machine. If the operator maintains the treadle 50 depressed for a period of time longer than the cycle time of the sewing machine the valve 71 will automatically close as illustrated in FIG. 4, before the conclusion of the first sewing cycle thus preventing the sewing machine from partaking of more than one cycle until the treadle 50 is released from the fully depressed position illustrated in FIGS. 3 and 4 to restore the valve 71 to normally opened position. If the treadle position of FIG. 4 is maintained, therefore, the sewing machine will stop when the latch 24, 25 is released by the machine, and since the valve 71 is closed the piston 35 will be returned by the sewing machine stop motion mechanism and the spring 38. The cam 63 will release the plunger 62 allowing the interlock valve 61 to return to normally opened position so that only the manually influenced valve 41 prevents the work clamp from being opened. The machine will thus stop with the work clamp in operative work holding position and this condition will continue until the opxerator releases the treadle 50.

If the operator wishes to recycl the sewing machine for one additional cycle she need only release the treadle to the intermediate position shown in FIG. 2 and then depress the treadle to the position illustrated in FIG. 3. The work clamp will not be raised and the momentary release of pressure from the line occasioned by the closing of the operator influenced valve 48 will restore the time delay valve to normally open position in readiness for a succeeding cycle of operation. If the operator completely releases the treadle, the conditions illustrated in FIG. 1 will exist and not only will the time delay valve 71 be restored to normally open condition but the work clamp will be raised.

Having thus set forth the nature of this invention, what I claim herein is: i

' 1. In a cyclically operating sewing machine having a drive means including control mechanism shiftable from a non-operating position of said drive means to an operating position thereof, and latch means maintaining said control mechanism in said operating position for a predetermined cycle of sewing machine operation, an operators control movable from a normal position into a machine operating position, a fluid means connected to said operators control and to said control mechanism for said drive means for shifting said control mechanism into said machine operating position of said drive means in response to movement of said operators control into said machine operating position and for maintaining said control mechanism shifted into said machine operating position while said operators control remains in said machine operating position, a normally open fluid valve means including time delay closing valve means separate from said fluid means and connected to said fluid means, said time delay valve means being arranged to render said fluid valve means ineffective upon time delay closing, means effective upon movement of said operators control out of said machine operating position for restoring said fluid valve means to normally open condition, and means associated with said time delay closing valve means for preselecting the duration of said time delay shorter than the duration of one predetermined cycle of sewing machine operation.

2. A device as set forth in claim 1 in which said time delay closing valve means includes an auxiliary fluid pressure operated motor and said fluid means comprises a normally closed valve means shiftable into an opened position in response to movement of said operators control into said machine operating position, means for supplying fluid under pressure to said normally closed valve means, a fluid pressure operated motor means connected to said control mechanism for said drive means, and a conduit leading from said normally closed valve means to said fluid pressure operated motor means, in which said normally open fluid valve means including said time delay which the time delay closing is effected by operation of said auxiliary fluid pressure operated motor in response to fluid pressure in said conduit between said normally open fluid valve means and said normally closed fluid valve means.

References Cited UNITED STATES PATENTS 2,722,184 11/1955 Sweet 11267 2,740,859 4/1956 Beatty et a1 91-355 XR 2,764,112 9/1956 Happe 1l267 3,298,341 1/1967 Bonis 112219 PATRICK D. LAWSON, Primary Examiner.

closing valve means is arranged in said conduit and in 15 H. H. HUNTER, Assistant Examiner.

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