US3008437A

US3008437A - Thread-chain cutter for sewing machines

Info

Publication number: US3008437A
Application number: US737607A
Authority: US
Inventors: John A Herr
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1958-05-26
Filing date: 1958-05-26
Publication date: 1961-11-14
Anticipated expiration: 1978-11-14
Also published as: GB862946A

Description

Nov. 14, 1961 J. A. HERR 0 THREAD-CHAIN CUTTER FOR SEWING MACHINES Filed May 26, 1958 4 Sheets-Sheet 1 NOV. 14, 1961 HERR 3,008,437

THREAD-CHAIN CUTTER FOR SEWING MACHINES Filed May 26, 1958 4 Sheets-Sheet 2 Nov. 14, 1961 J. A. HERR -CHAIN CUTTER FOR SEWING MACHINES THREAD 4 Sheets-Sheet 5 Filed May 26, 1958 Fig.4.

Nov. 14, 1961 J. A. HERR 3,008,437

THREAD-CHAIN CUTTER FOR SEWING MACHINES Filed May 26, 1958 4 Sheets-Sheet 4 United States The present invention relates to a thread-chain cutter for sewing machines.

In a cyclically-operated sewing machine having a traversing mechanism for feeding the work relatively to the stitching mechanism of the machine, the traversing mechanism includes a work carrying portion thatis moved about on the work supporting surface of the machine relatively to the stitch forming mechanism to define a sewing pattern of a desired configuration. To avoid subsequent trimming the thread-chain cutter should be located relatively close to the point of stitch formation so that the thread chain from the Work is cut relatively short and so that the thread ends at the beginning of the seam on the succeeding Work piece are also relatively short. In accordance with the above, it is an object of this invention to provide a thread-chain cutter which will sever the thread-chain sufliciently close to the point of stitch formation to avoid undesirably long thread ends and which will also not interfere with the manipulation of the work on the work supporting surface of the machine. It is a further object of this invention to provide such a thread-chain cutter which is adapted to be automatically actuated at the completion of the sewing cycle as the work is being removed from the machine, and particularly one that is adapted to be actuated by a traversing mechanism for loading and unloading the machine.

Further objects of this invention are to provide a thread-chain cutter for a sewing machine which is economical, dependable, durable, and trouble-free in operation.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

FIG. 1 is a fragmentary top plan view of a machine embodying the present invention.

FIG. 2 is a fragmentary sectional view taken substantially on the line 2-2 of FIG. 1.

FIG. 3 is a fragmentary detail vertical sectional view of the head portion of the sewing machine of FIG. 1 illustrating the thread-chain cutter.

FIG. 4 is a fragmentary top plan view of the bed of the sewing machine of FIG. 1 adjacent to the point of stitch formation.

FIG. 5 is a vertical sectional view of the thread-chain cutter per se.

FIG. 6 is a schematic circuit diagram of the machine illustrated in FIG. 1.

The present invention is herein illustrated as embodied in the machine forming the subject matter of the copending application of Reid et al., Serial No. 737,775, filed May 26, 1958, to which reference may be had for a more complete understanding of the machine. Briefly, this machine includes a sewing machine supporting table 1 upon which is mounted a sewing machine 2, and a table 3 for supporting the traversing mechanism for moving the work relatively to the point of stitch formation of ice the sewing machine 2 to define a path of motion corresponding to the desired seam configuration. The tables 1 and 3 are mounted upon supporting structures which are only incidentally disclosed in the drawings.

The sewing machine 2 is a Singer class 251 machine which is a single needle, high speed, lock stitch industrial sewing machine substantially as disclosed in the United States patent of Graesser, No. 2,680,417, but modified in that the feeding mechanism has been completely removed. The machine 2 comprises a bed 4, FIG. 3, including a bed plate 5, a standard 6 and a bracket arm 7 overhanging the bed 4 and terminating in a head 8. The sewing machine 2 is driven by a belt 9 from a double solenoid controlled electric power transmitter 10 which is substantially as disclosed in the United States patent application of Turner et al., Serial No. 536,414, filed September 26, 1955, now Patent No. 2,860,748, granted November 18, 1958. The transmitter 10 includes an electric motor 11 and a double acting solenoid 12 that actuates the clutch and brake mechanisms thereof and having a brake solenoid 13 and a clutch solenoid 14, FIG. 6. The stitching mechanism of the sewing machine 2 comprises an endwise movable needle bar 15 mounted in the head 8 and carrying a needle 16 at its lower end that cooperates in the formation of stitches with a rotary hook 17 journaled in the bed 4 beneath the bed plate 5. In the usual manner, at the point where the needle penetrates the bed plate 5, which is the point of stitch formation, there is provided a throat plate 18 having a needle aperture 19, FIG. 3. The sewing machine 2 is provided with a needle positioner 20 that stops the machine with the needle 16 in the raised position. The presser mechanism of the sewing machine 2 comprises a presser foot 21 mounted upon the lower end of a presser bar 22 that is mounted in the head 8. The presser foot is raised from and lowered onto the throat plate 18 by a presser lifter mechanism including a presser lifter lever 23 that is pivotally mounted intermediate its ends on the bracket arm 7 and connected through appropriate elements to a solenoid 24, FIG. 2, mounted on the supporting structure of the tabie 1.

For moving the work relatively to the point of stitch formation of the sewing machine 2 for sewing the seam designated S in FIG. 4, there is provided a traversing mechanism comprising a traversing table 25 mounted for universal movement in a horizontal plane on the table 3 by means of a first pair of tracks 26 on table 3 and on which rides a wheeled frame 27 that carries a second pair of tracks 28 arranged at a right angle to the tracks 26 and on which the traversing table 25 rides. A motor 29 is mounted on the table 25 which, through a belt 30 and variable speed ratio control mechanism 31, drives a vertical axis shaft 32 journaled on the table 25. At its lower end, the shaft 32 carries a pinion 33 that rides in a toothed track in a template 35 that is mounted upon the table 3. Thus, upon operation of the motor 29, the traversing table 25 will be moved through a path defined by the track 34.

The traversing table 25 carries an arm 36 upon which the work is adapted to be deposited and carried during the traversing cycle. The work is clamped on the arm 36 by a clamping bar 37 pivotally mounted on the arm 36 and biased downwardly against the arm 36 by a tension spring 38. The clamping bar 37 is automatically raised against the action of the spring 38 by a lever 39 which at its free end is connected by a cord 40 to one arm 41 of a bell crank lever 42, FIG. 3, pivotally mounted on the underside of the traversing table 25. The other arm 43 of the bell crank lever 42 cooperates with a rod 44 mounted on the supporting structure of the table 1. When the traversing table 25 is advanced toward the table 1, the arm 43 engages the rod 44 and is raised, thus depressing the arm 41 which pulls on the cord and through the lever 39 raises the clamping bar 37. When the traversing table 25 moves laterally in its forward position, the arm 43 slides along the rod 44 to hold the clamping bar 37 raised. When the traversing table 25 moves away from the table 1, the arm 41 is raised by the rod 44, thus permitting the spring 38 to lower the clamping bar 37 onto the traversing arm 36 to clamp the work.

The work is loaded onto and unloaded form the traversing arm 36 by a feeding or loading mechanism comprising a sleeve 45 mounted for endwise sliding on a rod 46 arranged across the bed plate 5 of the sewing machine 2 in back of the point of stitch formation. The sleeve 45 is moved by a reversible induction type motor 47 having a pulley 48 about which is wrapped a cord 49 that is entrained about pulleys 5t] and 51 and is connected at its opposite ends to a driving arm 52 on the sleeve 45. The work is deposited, for example, after the completion of a prior stitching operation as in the machine disclosed in the above noted application Serial No. 737,775, in a position to be engaged by a driving arm 52 on the sleeve 45. To remove the previously completed work from the arm 36, there is provided a work pick-up element on the sleeve 45 which, in the illustrated embodiment of the invention designed to be used in the machine forming the subject matter of the above noted application Serial No. 737,775, comprises an electromagnet 53 that is adapted to attract a metallic insert (not herein shown) embedded in a work holding element 54, FIG. 5, having an upper and a lower plate between which the work is sandwiched. When the motor 47 is operated forward, the driving arm 52 engages a work piece and advances it onto the traversing arm 36, and simultaneously, the electromagnet 53 is energized to pick up the previously completed work piece in the traversing arm 36 and carry it away from the machine. Reverse operation of the motor 47 returns the sleeve 45 to its original position.

The thread-chain cutter of the sewing machine 2 includes a rod 55 (FIGS. 3 and S) which, to facilitate assembly and to provide for adjustment, is made in two parts comprising an upper rod 56 and a lower rod 57 connected together -by a coupler 58. The upper rod 56 carries a wire 59 which is heated to incandescence for burning the thread chain. The wire 59 is mounted on the top of and is arranged generally parallel to the rod 56. The upper end 60 of the wire 59 is mechanically and electrically secured to the top of the rod 56, as by soldering, while the lower end 61 of the wire 59 is secured in a similar manner to the top of a sleeve 62 that surrounds the rod 56 in spaced relation thereto. sleeve 62 is insulated from the rod 56 by a sleeve 63 of insulating material, such as Bakelite, moulded on the rod 56. The insulating sleeve 63 is thus secured to the rod 56 and, while not shown, the adhesion between them may be enhanced by forming grooves or ridges or knurling on the periphery of the rod. The sleeve 62 is secured to the sleeve 63 and and thus to the rod 56 by a collar 64 surrounding the bottom of the sleeve 62 and having a set screw 65 for collapsing the sleeve 62 on the sleeve 63. A wire 66 has the end thereof disposed in a bore in the collar 64 adjacent to the sleeve 62 and intersecting thebore for the set screw 65. The end of the wire 66 is thus mechanically and electrically secured to the sleeve 62 when the set screw 65 is turned down. Spaced from the end of the sleeve 62, there is mounted on the rod 56 another collar 67 having a set screw 68 for securing the collar to the rod 56 and at the same time, mechanically and electrically securing the end of a wire 69 to the rod. The cutter wire 59 is thus mounted on the rod 56 and is adapted to be heated to incandescence by power supplied through the

wires

66 and 69.

The rod 55 is carried by the armature of a solenoid 70 mounted on the supporting structure of the table 1, and is disposed on a vertical axis beneath the bed plate 5 of the sewing machine 2 with the sleeve 62 extending The through a bearing bore 71 in the bed of the machine to guide the rod in endwise sliding movement. Upon energization of the solenoid 70, the rod 55 is raised and the upper end thereof with the cutter wire 59 is projected upwardly through an opening 72 in the bed plate 5. The sleeve 62 is elongated so that the collar 64 will not contact the under side of the bed 4 at the upper limit of movement of the rod 55. With reference to FIG. 4, the cutter is disposed beyond the point of stitch formation laterally 0f the bed of the sewing machine 2 and between the point of stitch formation and the point on the work to which the thread chain, designated C in FIG. 4, is connected at the end of the sewing cycle. Thus, when the cutter wire 59 is projected through the bed plate 5 by the solenoid 7t) and the work is moved away from the sewing position, as illustrated in phantom lines in FIG. 4, the thread chain C is wiped over the wire 59 and thereby severed. The cutter wire 59 is disposed adjacent to the point of stitch formation but spaced therefrom a distance adequate to provide a sufficiently long thread end for starting the next sewing operation without unthreading the needle. At the same time, the wire 59 can be located to provide an optimum thread end on the work.

Automatic operation of the sewing machine 2 and the traversing table 25 and the traversing sleeve 46, together with the thread-chain cutter, is provided by means of a plurality of switches responsive to the movement of the table 25. The operation of the mechanism and the description of the control switches can best be understood by reference to FIG. 6.

The operation of the machine is more fully disclosed in the above noted application Serial No. 737,775, to which reference may be had for a more complete understanding. The machine controls are herein explained only insofar as is necessary to describe the present invention. As seen in FIG. 6, power is supplied to the machine by leads 73 and 74 from a 110 v. source and by leads 75 from a 220 v. source. The leads 75 energize the motor 11 of the transmitter 10 which operates continuously.

Operation of the machine is controlled by a previous sewing operation which closes a solenoid actuated starting switch 76 by power supplied through a lead 77. Closing of the switch 76 closes a solenoid controlled holding circuit 78 through a normally closed stop switch 79 carried by the traversing table 25 and adapted to be opened by a cam plate on the table 3. The holding circuit 73 energizes the motor 29. The switch 76 can be opened and the motor 2'9 will continue to run until the stop switch 79 is opened at the end of the traversing cycle when it passes over the cam plate 80.

The traversing table 25 also carries a double acting sewing switch 81 that cooperates with a cam plate 82 on the table 3 for controlling the solenoid 12 of the transmitter 10, a switch 83 that cooperates with a cam plate 84 on the table 3 for initiating operation of the motor 47 and a cam 85 that cooperates with a switch 86 on the supporting structure of the table 1 for energizing the solenoid 24 to raise and lower the presser foot 21 of the sewing machine 2.

When the sewing switch 81 is riding on the cam plate 82 the brake solenoid I13 of the transmitter 10 is energized and the sewing machine is out of operation. This is the idle stroke of the traversing mechanism during which the work carrying arm 36 passes under the presser foot 21, the switch 86 being closed at this time by the cam 85 to energize the solenoid 24 and thus hold the presser foot raised. When the switch 81 passes off the cam plate 82, the clutch solenoid 14 of the transmitter 10 is energized to bring the sewing machine 2 into operation. Near the end of the traversing cycle, the stop switch 79 passes over the cam plate and is thereby opened, thus deenergizing the holding circuit 78 and in turn the traversing motor 29; There is a certain amount of coasting which carries the switch 79 over the cam plate 80 to reset the same for the next sewing cycle.

Near the end of the sewing cycle, the switch 83 is closed by the cam plate '84 to initiate operation of the motor 47. A solenoid controlled multiple contact switch 87 including two pairs of normally open contacts and a pair of normally closed contacts is connected together with normally closed limit switches 88 and 89 in the circuit of the forward rotation coil 90 and reverse rotation coil 91 of the motor 47. The limit switches 88 and 89 are arranged at the opposite ends of the rod 46 and are adapted to be opened by the arm 52 and an arm 92' on the electromagnet 53. In the rest position, the limit switch 88 is held open by the arm 52. When the switch 83 closes, the solenoid of the switch 87 is energized through the limit switch 89 and the starting switch 83 to close the normally open contacts. The forward rotation coil 90 of the motor 47 is then energized through the normally open contacts of the switch 87 and the starting switch 83. The motor 47 starts forward moving the sleeve 45 and thus moving the arm 52 away from the limit switch 88, permitting it to close. The switch 83 can now be opened to reset it for the next cycle, which is accomplished as the switch 83 is carried over the cam plate 84 while the motor 29 coasts after it is deenergized. The coil 90 is then energized through the normally open contacts of the switch 87 and the limit switch 88. The solenoid of the switch 87 is then energized through the limit switch 89, the normally open contacts of the switch 87, and the limit switch 88.

When the sleeve 45 reaches the end of its forward stroke, the arm 92 contacts the limit switch 89, opening it and deenergizing the solenoid of the switch 87, thus breaking the normally open contacts. The reverse rotation coil 91 of the motor 47 is then energized through the normally closed contacts of the switch 87 and the limit switch 88, and the return motion is imparted to the sleeve 45. At the end of the return stroke, the arm 52 opens the limit switch 88 to stop the motor 47.

Simultaneously with energization of the solenoid of the switch 87 when the starting switch 83 is closed, a solenoid actuated switch 93 is closed to energize the electromagnet '53. Thus, the work is magnetically secured to the sleeve 45 during the forward stroke. The solenoids of the switches 87 and 93-, being in parallel, are simultaneously deenergized upon opening of the limit switch 89 at the end of the forward stroke of the sleeve 45.

The sleeve 45 also carries an arm 94 that cooperates with a switch 95 upon the initial forward movement of the sleeve 45 for energizing the solenoid 70 of the threadchain cutter thus projecting the cutter upwardly into the path of the thread chain for severing it as it is wiped across the wire 59.

For heating the wire 59, the

leads

66 and 69 are connected to the opposite sides of the secondary coil of a step-down transformer 96, the primary coil of which is connected across the power leads 73 and 74 through a pair of contacts 97. The contacts 97 are a part of a time delay control unit 98 commercially known as an Agustat that controls the heating of the wire 59. The control unit 98, when energized, initiates heating of the wire 59 after a variable time delay and, when deenergized, will shut off the heating of the wire 59 after another variable time delay. The contacts 97 are normally open and are adapted to be closed by a solenoid 99. A dashpot 100 is connected to the armature of the solenoid 99 to impose a time delay in the opening of the contacts 97 when the solenoid 99 is deenergized. The control unit 98 also includes a second pair of normally open contacts 101 for energizing the solenoid 99. The contacts -1 are adapted to be closed by a solenoid 102, a dashpot 103 being connected to the armature of the solenoid 102 to impose a time delay in the closing of the contacts 101 after the solenoid 102 is energized. The solenoid 102 is connected in parallel 6 with the clutch solenoid 14 of the transmitter so that when the solenoid 14 is energized by the switch 81 to start the sewing cycle of the sewing machine 2, the solenoid 102 is simultaneously energized.

When the solenoid 102 is energized, the contacts 101 will be closed after a predetermined time delay imposed by the dashpot 103. When the contacts 102 close, the solenoid 99 is energized and the contacts 97 are closed immediately to energize the transformer 96 and thus begin heating the wire 59. Since the solenoid 102 is in parallel with the solenoid 14, it will be energized during the entire sewing cycle, thus maintaining energization of the solenoid 99 to hold the contacts 97 closed and to continue heating of the wire 59. The dashpot 103 is adjusted relative to the length of time required for the sewing cycle and to the length of time required to heat the wire 59 to incandescence, so that wire will be heated at the termination of the sewing cycle.

As noted above, substantially simultaneously with termination of the sewing cycle, the forward rotation of the motor 47 is initiated to impart forward movement to the sleeve 45 to remove the completed work from the arm 36 and to deliver unsewed work to the arm. The initial movement of the sleeve 45 causes the arm 94 to close the switch 95, thus energizing the solenoid 70 to project the wire 59 into the path of the thread chain C so that the chain will be wiped over the wire as it is moved along by the sleeve 45 and thereby severed. Simultaneously with deenergization of the clutch solenoid 14 at the end of the sewing cycle, the solenoid 102 is deenergized and the contacts 101 open immediately to deenergize the sole noid 99. The contacts 97, however, remain closed for a predetermined period of time as imposed by the dashpot 100. Thus, heating of the wire 59 will be continued to keep it hot for a short time after termination of the sewing cycle, and until the thread chain has been severed.

Numerious alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

Having thus described the nature of the invention, what I claim herein is:

1. In combination, a sewing machine having a bed including a bed plate and stitching mechanism defining a point of stitch formation on said bed plate, a thread-chain cutter comprising a hot wire for severing the thread chain by burning, means for supplying electrical power to said Wire for heating the same to a cutting temperature, means beneath said bed plate for mounting said wire for movement from a normal inoperative position beneath said bed plate to a stationary thread severing position in which said wire projects above said bed plate adjacent to the point of stitch formation for severing a thread chain at a point above said bed plate upon engagement of said thread chain against said wire as the work is removed, and means for moving said wire between the inoperative position and the thread severing position.

2,. In combination, a sewing machine having a bed including a bed plate and stitch-ing mechanism defining a point of stitch formation on said bed plate, said bed plate having an aperture, a thread-chain cutter comprising a rod mounted in said bed beneath said aperture for endwise movement from a normal inoperative position beneath said bed plate to a thread severing position in which the upper end thereof extends through said aperture, controlled means for imparting endwise movement to said rod between the inoperative position and the thread severing position, a wire mounted upon the upper end of said rod for severing the thread chain by burning, and means for supplying electrical power to said wire for heating the same to a cutting temperature.

3. In combination, a sewing machine having a bed including a bed plate and stitching mechanism defining a point of stitch formation on said bed plate, said bed plate having an aperture adjacent to the point of stitch formation, a thread-chain cutter comprising a rod mounted in said bed beneath said aperture for endwise movement from a normal position beneath said bed plate to a thread severing position in which the upper end thereof extends through said aperture, a sleeve surrounding an intermediate portion of said rod and electrically insulated therefrom, a wire for severing the thread chain by burning, said wire being mounted upon and electrically connected at its opposite ends to the upper end of said rod and to said sleeve, a source of electrical power operatively connected beneath said bed plate to said rod and to said sleeve, means for controlling the application of electrical power to said wire for heating the wire to a cutting temperature, a solenoid disposed beneath said bed plate and operatively connected to said rod for moving said rod to thread severing position when energized, and means for controlling the energization of said sol noid.

4. In a cyclically operated sewing machine having stitch forming mechanism defining a point of stitch formation, a thread-chain cutter comprising a hot wire for severing the thread chain by burning, said wire being arranged to be engaged by a thread chain extending between the point of stitch formation and a sewed work piece, means for supplying electrical power to said wire for heating the same to a cutting temperature, and means for automatically controlling the electrical power to said wire to apply the power a predetermined period of time before the completion of the sewing cycle to obtain cutting temperature at the completion of the sewing cycle and thereafter to terminate the heating of the wire.

5. -In a cyclically operated sewing mach-inc having stitch forming mechanism defining a point of stitch formation, a thread-chain cutter comprising a hot wire for severing the thread chain by burning, means for mounting said wire on said sewing machine for movement from a normal inoperative position to provide for manipulation of the work relative to said point of stitch formation to a thread severing position adjacent to the point of stitch formation means for supplying electrical power to said Wire for heating the same to a cutting temperature, and means for automatically controlling the electrical power to said wire to apply the power a predetermined period of time before the completion of the sewing cycle to obtain cutting temperature at the completion of the sewing cycle and thereafter to terminate heating of the wire, and means for moving said wire into thread severing position at the completion of the sewing cycle.

6. In a cyclically operated sewing machine having a bed including a bed plate and stitching mechanism defining a point of stitch formation on said bed plate, a threadehain cutter comprising a hot wire for severing the thread chain by burning, means for mounting said wire in said bed for movement between a normal inoperative position beneath said bed plate to provide for manipulation of the work on said bed plate relatively to the point of stitch formation and a thread severing position in which said wire projects above said bed plate to be engaged by a thread chain extending between said point of stitch formation and a sewed work piece, means for supplying electrical power to said wire for heating the same to a cutting temperature, and means for automatically controlling the electrioal power to said wire to apply the power a predetermined period of time before the completion of the sewing cycle to obtain cutting temperature at the completion of the sewing cycle and thereafter to terminate heating of the wire, and means for moving said wire into thread severing position at the completion of the sewing cycle.

7. In a cyclically operated sewing machine having a bed including a bed plate and stitching mechanism defining a point of stitch formation on said bed plate, loading mechanism for presenting work to said sewing machine and removing sewed work therefrom, a threadchain cutter comprising a hot wire for severing the thread chain by burning, means for mounting said wire in said bed for movement between a normal inoperative position beneath said bed plate to provide for manipulation of the work on said bed plate relative to the point of stitch formation and a thread severing position in which said wire projects above said bed plate to be engaged by a thread chain extending between said point of stitch formation and a sewed work piece, means for supplying electrical power to said wire for heating the same to a cutting temperature, and means for automatically controlling the electrical power to said wire to apply the power a predetermined period of time before the completion of the sewing cycle to obtain cutting temperature at the completion of the sewing cycle and thereafter to terminate the heating of the wire, means for actuating said loading mechanism at the completion of the sewing cycle, and means for moving said wire into thread severing position at the completion of the sewing cycle upon the initial actuation of said loading mechanism.

8. In a cyclically operated sewing machine having a bed including a bed plate and stitching mechanism defining a point of stitch formation on said bed plate, traversing mechanism for receiving work and for moving the same on said bed plate relative to said point of stitch formation to produce a seam of a predetermined eonfiguration, control means for initiating the operation of said traversing mechanism and said sewing machine and for stopping the same at the completion of the cycle of actuation, loading mechanism for presenting work to said traversing mechanism and for removing completed work from the same, actuating means for said loading mechanism for imparting a cycle of actuation thereto, means for initiating actuation of said loading mechanism at the completion of the sewing cycle and for automatically stopping the same at the completion of its cycle of actuation, and a thread-chain cutter comprising a hot wire for severing the thread chain by burning, means for supporting said wire beneath said bed, means for supplying electrical power to said wire for heating the same to cutting temperature, means for automatically controlling the heating of the wire to obtain cutting temperature at the completion of the sewing cycle and thereafter terminate heating of the wire, and means responsive to the actuation of said loading mechanism for projecting said wire into a position traversed by the thread chain as the work is moved away from sewing position, whereby the thread chain will engage said wire and will thereby be severed.

9 In a cyclically operated sewing machine having a bed including a bed plate and stitching mechanism defining a point of stitch formation on said bed plate, actuating means for said sewing machine, traversing mechanism for receiving work and for moving the same on said bed plate relative to said point of stitch formation to produce a seam of a predetermined configuration, actuating means for said traversing mechanism, control means for initiating operation of said traversing mechanism and for automatically stopping the same at the completion of the traversing cycle, means controlled by the actuation of said traversing mechanism for initiating operation of said sewing machine, and stopping the same at the completion of the sewing cycle, loading mechanism for presenting work to said traversing mechanism and for removing completed work therefrom, actuating means for said loading mechanism, control means actuated by said traversing mechanism at the completion of the traversing cycle for initiating operation of said loading mechanism and for automatically stopping the same at the end of the loading cycle, and a thread-chain cutter comprising a hot wire for severing the thread chain by burning, means for mounting said wire in said bed for movement between a normal inoperative position beneath said bed plate and a thread severing position in which said wire projects above said bed plate to be engaged by a thread chain extending between said point of stitch formation and a sewed work piece, means for supplying electrical power to said wire for heating the same to a cutting temperature, and means for automatically controlling the electrical power to said wire to apply the power a predetermined period of time before the end of the traversing cycle to obtain cutting temperature at the completion of the traversing cycle, and thereafter to terminate heating of the Wire, means for moving said wire into thread severing position upon the initial actuation of the loading mechanism.

10. A cyclically operated sewing machine in accordance with claim 9 in which the control means for initiating the heating of the wire is actuated by said traversing mechanism simultaneously with initiation of the actuation of the sewing machine and includes means for imposing a variable time delay between the time of actuation and the time electrical power is supplied to said wire for initiating heating thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,173,769 Carman Feb. 29, 1916 1,342,008 Weis June 1, 1920 2,226,401 Haas Dec. 24, 1940 2,592,463 Phillips Apr. 8, 1952 FOREIGN PATENTS 310,510 Germany Jan. 27, 1919 311,048 Germany Feb. 21, 1919