US3705561A - Cyclic sewing machine - Google Patents

Abstract

A cyclic sewing machine comprising a first cam disk for actuating a motion control mechanism to control the start and stop of a sewing machine and a thread cutting mechanism at the end of a cycle corresponding to a prescribed number of stitches; and a second cam disk for imparting the feed movement to the work clamp mechanism with a number of stitches equal to an integral multiple of said prescribed number of stitches, wherein the motion control mechanism and thread cutting mechanism are brought to an inoperative state until just before the second pattern cam disk imparts a one cycle feed movement to the work clamp mechanism, thereby permitting the very easy change of a number of stitches used in one cycle.

Description

United States Patent Sakawa et al.

[451 Dec. 12,1972

1541 CYC LIC SEWING MACHINE [72] Inventors: Katuaki Sakawa, Chiryu; Tetuo Kozawa, Aichi-ken, both of Japan [73] Assignee: Brother Kogyo Kabushiki Kaish, Nagoya-shi, Japan [22] Filed: July 6, 1971 [21] App1.No.: 160,195

[30] Foreign Application Priority Data July 6, 1970 Japan ..45/58857 [52] US. Cl ..1l2/67, 112/70 [51] Int. Cl. ..D05b 3/04 [58] Field of Search ..l12/67, 70, 73, 65

[56] References Cited UNITED STATES PATENTS 1,033,721 7/1912 Miller ..112/65 1,492,084 4/1924 Ray ..112/65 l/l932 Allen ..ll2/65 1/1961 Reece ..112/70X Primary Examiner-H. Hampton Hunter Attorney-Kemon, Palmer & Estabrook [5 7 ABSTRACT A cyclic sewing machine comprising a first cam disk for actuating a motion control mechanism to control the start and stop of a sewing machine and a thread cutting mechanism at the end of a cycle corresponding to a prescribed number of stitches; and a second cam disk for imparting the feed movement to the work clamp mechanism with a number of stitches equal to an integral multiple of said prescribed number of stitches, wherein the motion control mechanism and thread cutting mechanism are brought to an inoperative state until just before the second pattern cam disk imparts a one cycle feed movement to the work clamp mechanism, thereby permitting the very easy change of a number of stitches used in one cycle.

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PATENTED um 12 m2 SHEET llUF 12 PATENTED DEC 12 I972 SHEET 12 0F 12 wmv do? m CYCLIC SEWING MACHINE This invention relates to a cyclic sewing machine, and more particularly to a cyclic sewing machine capable of sewing bar tacks, patterns and other forms on a work fabric with a certain number of stitches prescribed for each case.

The prior art cyclic sewing machine is generally so designed that a first cam disk jointly rotating with a main shaft controls a motion control mechanism for stopping a sewing machine upon completion of sewing and a second cam jointly rotating with said main shaft controls the feed movement of a work clamp mechanism.

This type of sewing machine has the drawbacks that where there was to be performed cyclic sewing requiring a different number of stitches from those used in the preceding form of sewing, there should be changed the tooth number ratio of the worms and worm wheels coupling the cam disks with the main shaft, a second cam disk had to be replaced with one corresponding to the resulting changed number of stitches and also a first cam disk had to be exchanged for one capable of imparting proper operation timing to the motion control mechanism and thread cutting mechanism to match the varied number of stitches to be performed by said replaced second cam disk.

Replacement of the first and second cam disks and worms and worm gears to drive them for each such change of the number of stitches not only consumed a great deal of time and work, but also there were presented considerable difficulties in exchanging the worms and worm gears by taking out the main shaft which was designed to control the movement of all movable parts of a sewing machine. This operation was impossible with general nonexpert users of a sewing machine.

There has been developed another type of cyclic sewing machine wherein, instead of replacing the first cam disk, there is adjustably fitted to said cam disk a cam strip for actuating the motion control mechanism and thread cutting mechanism and the operation timing of both mechanisms is adjusted, each time the number of stitches is changed. Either case, however, is accompanied with time-consuming work which is impossible with general users of a sewing machine. Where, therefore, the user desired to perform various types of cyclic sewing, he has to purchase a number of sewing machines with the resulting economic disadvantage. Also where a sewing machine maker manufactures sewing machines performing various numbers of stitches, he is obstructed in mass production due to the necessity of fitting each time different types of first cam disk, worm and worm gear.

It is accordingly an object of this invention to provide a cyclic sewing machine permitting the easy change of a number of stitches.

Another object of the invention is to provide a cyclic sewing machine, which, in changing a number of stitches, eliminates the necessity of replacing a first cam disk for actuating the motion control mechanism and thread cutting mechanism and controlling the operation timing of both mechanisms.

Another object of the invention is to provide a cyclic sewing machine permitting another form of cyclic sewing using a different number of stitches simply by replacing gear means disposed between the second cam disk and the main shaft.

Still another object of the invention is to provide a cyclic sewing machine permitting another form of cyclic sewing using a different number of stitches simply by machining a second cam disk and replacing it for the previously used one.

A further object of the invention is to provide an inexpensive cyclic sewing machine of extremely simple construction due to a design easily to change a number of stitches.

A still further object of the invention is to provide a cyclic sewing machine which permits mass production for manufacturers and offers handling convenience and saves cost for manufacturers as well as for users.

According to the invention there is provided a cyclic sewing machine comprising a frame including a work supporting bed, drive means, amain shaft journaled in said frame, a reciprocable needle supported on said frame and movably connected to said main shaft, motion control mechanism disposed between said main shaft and said drive means for controlling the start and stop of said main shaft, a thread cutting mechanism mounted on said frame for cutting threads, a work clamp mechanism movably supported on said work supporting bed to move across the reciprocating path of said needle, first cam disk means mounted on said frame and movably connected to said main shaft for controlling the operation of said motion control mechanism and said thread cutting mechanism at the end of each sewing cycle corresponding to a predetermined number of stitches, first cam follower means operatively connecting said first cam disk means with said motion control mechanism, second cam follower means operatively connecting said first cam disk means with said thread cutting mechanism, second cam disk means for imparting feed movement to said work clamp mechanism with a number of stitches equal to an integral multiple of those corresponding to one cycle of said first cam disk means, driving connections provided between said second cam disk means and said main shaft for rotating the second cam disk means to such extent that the ratio of the angular velocity of said second cam disk means to that of said first cam disk means takes a value arrived at by dividing the number of stitches corresponding to said first cam disk means by the number of stitches corresponding to said second cam disk means, third cam follower means operatively connecting said second cam disk means with said work clamp mechanism, and means for rendering said motion control mechanism and thread cutting mechanism inoperable, notwithstanding the rotation of said first cam disk means until just before the rotation for imparting a one cycle feed movement to said work clamp mechanism is completed.

The present invention can be more fully understood from the following detailed description when taken in conjunction with reference to the appended drawings, in which:

FIGS. 1 to 10 show a cyclic sewing machine according to one embodiment of the invention, wherein FIG. 1 is a schematically perspective view of the machine,

FIGS. 2 and 3 are respectively right and left side views of a machine body,

FIG. 4 is an enlarged perspective view of a jaw portion of the machine, I

FIG. 5 is a cross sectional view on line VV of FIG.

FIG. 6 is a perspective view showing a cam unit and operable levers,

FIGS. 7 to 9 are respectively perspective views of a thread cutting mechanism, stop cam mechanism and thread tightening cam mechanism, and

FIG. 10 illustrates a deceleration mechanism;

FIGS. 11 to 13 show a cyclic sewing machine according to another embodiment of the invention, wherein FIG. 11 is a left side view, partially cut off, of the cyclic sewing machine, FIG. 12 is a cross section on line XII XII of FIG. 11 and FIG. 13 is a cross sectional view of a deceleration mechanism;

FIG. 14 shows perspectively a modification of a feed cam and cam unit; and

FIGS. 15A and 15B are respectively front views of another modification of a feed cam.

There will now be described a cyclic lock stitch sewing machine according to one embodiment of the invention with reference to FIGS. 1 to 10.

Referring to FIG. 1, on the table 1 there is mounted a machine body or frame 2 while under the table there is provided a motor 4 driving a machine through a belt 3, a starting pedal 6 connected to a chain member 5 and a foot lifting pedal 7.

In FIGS. 2 to 4 a reference numeral 11 indicates a bracket arm portion extended from a standard or leg member 13 having an arm bed 12, and a main shaft 14 is provided in the arm portion 11 and member 13. Said main shaft 14 is adapted to control vertical movements of members such as a thread take up lever 16 extending from an elongated slit 15 formed in the jaw 11a of the arm portion 11 and a needle bar 18 provided with a needle 17 on the lower end thereof. 19 denotes a feed cam rotatably mounted on the standard 13 by a rotary shaft 20, which has transverse feed grooves 19a in the front surface thereof and forward and backward feed grooves 190 in the back surface thereof. There is rotatably contacted with the surfaces of said transverse feed grooves 19a a roller 22 mounted on the top end portion of a transverse feed lever 21 of which the base end portion is pivoted by a shaft 24 on a feed bracket 23 erected on said arm bed 12. There is integrally provided a guide member 25 having an elongated guide slit 25a for the base end portion of said lever 21. In the elongated guide slit 25a of the guide member 25 there is slidably inserted a spherical shaft 27 mounted on the top end of a transverse feed rod 26. The base end portion of said transverse feed rod 26 is connected to a transverse feed lower shaft 28 supported in said arm bed 12. A feeding link guide 29 is fixed to the lower shaft 28 and connected to a feed bed 30 disposed on the surface of said arm bed 12. A feed plate 31 is connected to the top end of the feed bed 30 so as to be positioned downwardly of said jaw 11a.

There is rotatably contacted a roller (not shown) mounted on a forward and backward feed lever 32 supported by said feed bracket 23 in said forward and backward feed grooves 19b of said feed cam 19. A forward and backward feed controlling guide shaft 33 is attached to said forward and backward feed lever 32 and is connected to said feed bed 30. 34 shows a pressure arm standed on said feed bed 30, to the top end of which there is vertical-movably attached by a pressure foot guiding plate 35, a pressure foot 36 having a protrusion 36a. Normally, biasing force is downwardly applied to said foot 36 by a pressure spring 37, so that the work fabric (not shown) on the surface of said feed plate 31 is held by the pressure foot 36 thereby to constitute a work fabric clamping mechanism. A numeral reference 38 shows a pressure rod mounted on said jaw 11a to the lower portion of which there is connected a lever 39 to face from below the protrusion 36a of said pressure foot 36, and to the center portion of which there is attached a pressure plate 40 having a protrusion 40a. With lower side of the protrusion, there is contacted a top end portion of a pressure arm member 42, the center of which is pivoted on the machine arm portion 11 by a shaft 41. Accordingly, as later described, when the pressure member 42 is, in FIG. 3, swung in a counter-clockwise direction, the pressure rod 38 is moved upwardly and the lever 39 pushes up said pressure foot 36 via said protrusion 36a, whereby the foot 36 is upwardly urged against the pressure spring 37.

Referring to FIG. 3, a numeral reference 43 shows a cam unit rotatably supported on the left side frame of said leg member 13 by a rotary shaft 44 which is, as later described in FIG. 6, constituted by a rest cam 45, stop cam 46, a thread cutting cam 47 and a thread tightening cam 48 which are respectively formed with the same diameter. Said rest cam 45 is freely rotatable about the shaft 44 and the remaining cams 46 to 48 are adapted to rotate integrally with the shaft 44. On the side wall of the rest cam 45 there is extended a pin 49 engaged with the forked portion of an operable lever 50. The base portion of said operable lever 50 is attached to one end of a shaft 51 vertically penetrating through said arm bed 12. On the other end of the shaft 51 is fixed a lever 52 having a roller 52a rotatably contacting the outer peripheral surface of said feed cam 19. In this case, biasing force is so in advance applied to said lever 52 by, for example, a spring (not shown) as to permit the roller 52a to always contact the outer peripheral surface of the feed cam 19. A depression is formed in the periphery of the feed cam 19 to have a prescribed area corresponding to four stitches ahead and backward of the stop point of the machine. When said feed cam 19 is, for example, in FIG. 2, rotated in a clockwise direction and then said roller 52a is brought down into said depression 19c whereby said lever 52 is swung, also in FIG. 2, in a clockwise direction, such rotation is transmitted through the shaft 51 to the operable lever 50, so that said operable lever 50 is adapted to swing the rest cam 45, in FIG. 3, in a counter-clockwise direction through said pin 49.

53 shows a clutch lever rotatably supported by a shaft 55 to a clutch lever bracket 54 extended from said leg member 13, the upper end portion of which is disposed a clutch stopper 56. Said clutch stopper 56 is so arranged as to oppose a movable wheel 57 which is fixed to said main shaft 14 so as to rotate integrally therewith. There is formed on that surface of the movable wheel 57 which faces said clutch stopper 56 a stopper groove (not shown) to be engaged with said stopper 56. 58 shows an idle wheel idly fitted to said machine shaft. Said clutch lever 53 is normally biased in a counter-clockwise direction in FIG. 2 (in a clockwise direction in FIG. 3) by a clutch lever spring 59 stretched between the lever 53 and said leg member 13. When said lever 53 is swung in a clockwise direction (in FIG. 2) against said spring 59 by manual operation to be brought to an operable position or condition, a clutch lever pawl 60 mounted on the lower end portion of said lever 53 is engaged with a clutch stopping pawl 62 mounted on the top end of a clutch stopping lever 61 whereby said operable condition is maintained. The base end portion 0 of said clutch lever 61 isfixed to the one end of a shaft 63 transversely penetrating through said standard 13 and biasing force is normally applied thereto in a clockwise direction in FIG. 2 by a spring 64 strected between said lever 61 and the member 13. To the other end of said shaft 63 is fixed a stop lever 65 as shown in FIG. 3. As shown in FIG. 6, to the top end portion of said stop lever 65 there are attached rollers 66 and 67 which slidably move on the peripheral surfaces of said rest cam 45 and stop cam 46, respectively. There is formed in that point of the outer periphery of said stop cam 46 at which the machine operation stops a stop cam groove 46a as shown in FIG. 8. When the roller 67 is brought down into said cam groove 46a whereby said lever 65 is swung in a clockwise direction in FIG. 3, the clutch stopping lever 61 is swung in a counter-clockwise direction in FIG. 2 through the shaft 63 against the spring 64 and then the clutch stopping pawl 62 is disengaged from the clutch lever pawl 60, so that the clutch lever 53 is swung in a counter-clockwise direction in FIG. 2, i.e. toward the stopping position by the clutch lever spring 59 and then the clutch stopper 56 is engaged with the clutch groove of the movable wheel 57 thereby to stop rotation of the machine shaft 14. 68 is a belt guide attached to said clutch lever 53, which shfts a belt transmitting the rotary force of a motor 4 from either of the movable wheel 57 to the idle wheel 58 to the other in response to the motions of the clutch lever 53, that is, when the clutch lever 53 is moved to the operational position, said belt is shfted from the idle wheel 58 to the movable wheel 57 thereby to rotate the main shaft 14, while when the clutch lever 53 is moved to the stopping position, then the belt is shfted from the movable wheel 57 to the idle wheel 58 to rotate the idle wheel 58, thus preventing drive power from being transmitted to the machine shaft 14, thereby constituting a catch controlling operation stop mechanism.

In FIG. 3, 69 is a pressure stopping lever which is pivoted to said leg member at the intermediate portion. To the upper end of the lever 69 is attached a stopping lever pawl 70 and to the lower end thereof is connected said clutch lever 53 via a connection rod 71. When the clutch lever 53 is placed in the operational position, said lever pawl 70 is opposed from below to the pressure stopping pawl 72 mounted on the end of said member 42 thereby to stop the swing thereof, so that the pressure rod 38 and thus pressure foot 36 are prevented from being raised during operation of the machine. Alternatively, when the clutch lever 53 is moved to the stopping position, the pressure controlling lever 69 is swung in a counter-clockwise direction in FIG. 2 via the connection rod 71, so that the stopping lever pawl 70 becomes unable to oppose the pressure stopping pawl 72, permitting swing of the pressure member 42.

There will now be described a thread cutting mechanism. In FIG. 3, 73 is a thread cutting lever which is pivoted to said leg member 13 at the central portion, the upper portion of which is formed in a forked shape as shown in FIG. 6, the top end of one arm of said forked form being provided with a roller 74 movably contactedwith periphery of said rest cam 45 and that of the other arm a roller 75 and pointed body 76. There is, as shown in FIG. 7, fixed to the outer peripheral surface of said thread cutting cam 47 a stepped member which comprises a lower thread catching stepped portion 77, upper thread catching stepped portion 78 and upper and! lower thread cutting stepped portion 79. Further, there is formed a depression 47a spacingly apart from said stepped member 80 along the rotary shaft of the thread cutting cam 47 and there are formed adjacent said depression 47a a first cam face 47b for preparing to catch a thread, a second cam face so acting as to permit a "thread cutting means hereinafter described to hold a cut upper thread and a third cam face 47d for returning the thread cutting means actuated to cut off a thread to the original condition. Said pointed body 76 may be brought down into the lower and upper thread catching stepped portions 77 and 78 of said stepped member 80 just before the machine automatically stops and down into the thread cutting stepped portion 79, when the machine automatically stops, by the action of a spring as later described. Said roller 75 is associated with the thread cutting cam 47 so that the pointed body 76 is not contacted with the periphery of the cam 47 in the normal condition, and at the same time slides in contact therewith, and when the roller 75 is brought down into said depression 47a, said pointed body 76 contacts the upper surface of said stepped member 80 in a manner to be brought down into said three stepped portions 77 78 and 79, whereby provision is so made as to permit the pointed body to be disengaged from the thread cutting cam 47 except when facing the three cam surfaces 47b, 47c and 47d of said depression 47a. 81 is a connecting member to beinterlockingly operated upon receipt of the swing motion of said thread cutting lever 73 caused by the depression of the pointed body thereof and which is interposed between said lever 73 to actuate the thread cutting means. One end of the connecting member extends to the proximity of the end of said lever 73 and the other end to near the thread cutting means. There is stretched between the leg member 13 and lever 73 a spring (not shown) so acting as to perform the depression of said lever 73. 82 is a connecting piece for the purpose of contacting that end portion of the connecting member 81 which faces said lever 73 with the lever 73 so that the displacement amount of said connecting member 81 may be adjusted in order to secure accurate operation of the thread cutting means, the lower end portion of said lever 73 being associated with a tongue piece 82a provided on the connecting piece 82 and the piece 82 being adjustably associated to the connecting member 81 by means of a screw 83 attached to the connecting member 81, penetrating through an elongated groove 82b formed in the connecting piece 82. 84 is a needle plate fitted to the underside of said feed plate 31, which has needle holes 85 through which there is passed the needle 17 vertically reciprocated by said needle bar 18. There is fitted to the undersurface of the needle plate a thread cut-ting means 86 which catches and cuts off upper and lower threads and then holds the cut upper thread by interlocking with said lever 73. The thread cutting means 86 comprises, as shown in FIG. 5, a pivotal shaft 87 fixed to said needle plate 84, a pinion 88 which is pivoted to the shaft 87 and intermeshed with a rack 81a formed in the end portion of said connecting member 81 so as to rotate by desired angles, and a plate member 91 having thread catching pawl 91a screwed by a screw 90 to a projective arm 89 formed integrally with said pinion 88 so as to catch the lower thread by passing below said needle holes 85 as the rotation of the pinion 88 and a lower thread cutting blade 91b which is disposed backwardly of said pawl 91a and fittingly to an angular groove 92 formed coaxially with the rotary center of said pinion 88 on the undersurface of the needle plate 84. The cutting means further includes an upper thread cutting pawl 93a and blade 93b disposed therebehind, which are screwed by said screw 90 similarly to said plate 91 and disposed backwardly of the lower thread catching pawl 91a of said plate 91 and spaced apart from said pawl 91a so as to catch the upper thread by passing below the needle holes 85 as the rotation of said pinion 88, an 'upper thread holding member 94 which is screwed by the screw 90 in the same manner as in said both plates 91 and 93 to pass below the needle holes 85 and holds the upper thread by catching that end portion of the cut upper thread which faces the needle 17 and pinching said portion between said holding member and needle plate 84, and an upper thread cutting stationary blade 95 screwed on the undersurface of said needle plate 84 so as to engage the upper thread cutting blade 93b for the purpose of cutting the upper thread by cooperating therewith. Referring to FIG. 7, 96 is a stopper contacting a projection 820 formed in said connecting piece 82 so as to prevent the pointed body 76 of the thread cutting lever 73 from being fallen into the stepped portion 79 against the spring action when said pointed body 76 brought, by the action of the spring, down into said thread catching stepped portions 77 and 78 and then has abutted on the next thread cuttingstepped portion 79 by the rotation of the cam 47. The stopper is disposed in a manner to face the side of the projection 82c of said connecting piece 82 and fixed, by, for example, a screw, to a rotary arm 98 rotatably supported at the base end to an auxiliary machine frame 97 screwed to said leg member 13. 99 is a spring stretched between said auxiliary machine frame 97 and rotary arm 98 to permit the free end of the rotary arm 98 to be upwardly urged.

100 is a connecting rod connected to the foot pedal 7 at the lower end for lifting said pressure foot 36. The enlarged diameter portion 100a of the rod 100 is inserted through a hole 98b formed in a bearing arm horizontally extended from the free end of said rotary arm 98 and provided with a pin 101 penetrated through the rod in a manner to swing the arm 98 before the liftup of the pressure foot so that when the rod is downwardly shifted by the operation of pressure foot the stopper 96 is disengaged from the contacting position with the connecting piece 82 to cause said lever 73 to be brought down into the thread cutting stepped portion 79. The upper end of said connecting rod 100 is connected to that end portion of said pressure member 42 which faces the side at which is disposed the pressure stopping pawl 72.

To give further description of a thread tightening mechanism, 102 is a thread tightening lever, which is, as shown in FIG. 6, constructed by a pair of linearly connected lever to the top end of one of which is attached'a roller 103 slidably contacting said rest cam 45 and to that of the other of which is provided a roller 104 slidably contacting said thread tightening cam 48. There is fixed, as shown in FIG. 9, to a shaft 105 secured to the thread tightening lever 102 a thread tightening connected lever 106 to which is attached a thread tightening connecting rod 109 connected to a clamping plate 108 which is forwardly guided within said machine arm portion 11 and pivoted to said needle bar 18 by a shaft 107. There is integrally attached to the middle portion of the thread tightening connecting rod 109 a cam body 110 having the cam surface 110a with which is contacted the extended end of the thread loosing guide shaft 111a of a main adjuster 111 mounted on the right side of said jaw 11a through an auxiliary guide member 112 disposed inside the jaw 11a. Further, connected to the thread tightening lever 102 is another shaft 113 fixed to a thread tension adjusting member 114 which is disposed in a manner to be engaged with a stop member 115 so fixed to the side of said pressure member 42 as to swing integrally therewith. There is formed in the outer periphery of said thread tightening cam 48 a cam groove 48a corresponding to forward two stitches and backward three or four stitches, so that when said roller 104 slidably moves on the outer peripheral surface of the thread tightening cam 48 to be brought down into the cam groove 48a, the thread tightening lever 102 is swung, in FIGS. 3 and 9, in a counter-clockwise direction, said rotation being transmitted as a forward drive force to the thread tightening connecting rod 109 via the thread tightening connecting lever 106. In this case, when the roller 104 is brought down into the cam groove 480 by substantially one half of the depth thereof, the thread tension adjusting member 114 connected to the shaft 113 is engaged with the stop member 115 fixed to the pressure member 42 thereby to prevent the roller 104 from being any further brought down into said cam groove 48a. If the thread tightening connecting rod 109 is forwardly moved by the swing movement of the thread tightening lever 102 resulting from the fall of the roller 104 to half the depth of the cam groove 48a, the thread loosing guide shaft 111a slidably contacting the cam surface 110a of the cam body 110 is moved in its axial direction in FIG. 9 thereby to loose the upper thread pinched by the adjuster disks 111b of the main adjuster 111. Further, when the pressure member 42 is swung (in a counter-clockwise direction in FIG. 9) via the connecting rod 100 by the operation of the foot pedal for lifting said pressure foot 36, the thread tension adjusting member 114 is disengaged from the stop member 115 so that the roller 104 is fallen into the deepest portion of the cam groove 48a. The thread tightening connecting rod 109 is further forwardly moved by the swing movement of the thread tightening lever 102 resulting from said fall to further loose the thread holded by the main adjuster 111 and by the top end portion thereof the clamping plate 108 is urged to be rotated in a clockwise direction in FIG. 9 and then a needle thread guide 18a mounted on the needle bar 18 is urged to loose the upper thread guided into the needle 17 through said needle thread guide 18a. Then, the machine is once again driven and, after three or four stitches are performed, the roller 104 gets out of the cam groove 48a, and tightening by the clamping plate 108 of the upper thread is released in reverse motions to those described above and further loosing by the main adjuster 111 of the upper thread is also released.

There will now be described an operation connecting mechanism for driving in a manner to rotate said feed cam 19 and cam unit 43 with referenceto FIG. 10. The rotary shaft 44 of said cam unit 43 transversely penetrates through the leg member 13, one end of which is supported by the journal bearing 13a mounted on the right side wall of the leg member 13 and to the middle portion of which is fixed a worm wheel 117 intermeshed with the worm 116 fixed to said main shaft 14. To the end portion of said rotary shaft 44 is at: tached a small gear 118 by intermeshing a key way 118a with a key 44a formed in the rotary shaft 44, said small gear being so secured thereto as to integradally rotate with said rotary shaft 44 by means of a stop ring 119. The rotary shaft 20 of the feed cam 19 is supported by a journal bearing 13b formed in the right side wall of the leg member 13 and is attached to a large gear 120 intenneshed with said small gear 118 by engaging a key way 120a with a key 20a formed in said rotary shaft. The key way 121a of a cylindrical'shaft 121 penetrating through the shaft hole 19d of said feed cam 19 is engaged with the key 20b of the rotary shaft 20, and by screws 122 the feed cam 19 is screwed to the cylindrical shaft 121 and simultaneously a nut 123 is screwed into the top end portion of the rotary shaft 20 whereby the large gear 120 and feed cam 19 are so set as to rotate integrally with the rotary shaft 20. With the above-mentioned construction, if the stop ring 119 is dismounted, the small gear 118 becomes detachable from the rotary shaft 44 and if the nut 123 and screws 122 are dismounted, the large gear 120 and feed cam 19 also become detachable from the rotary shaft 20. Accordingly, the small and large gears 118 and 120 may consist of a combination of those having arbitrary numbers of teeth, and the feed cam 19 may also be replaced by a cam realizing any desired sewn pattern and stitch numbers.

In the sewing machine, one rotation of the main shaft 14 corresponds to one vertical reciprocating movement of the needle 17, i.e. one stitch thereof, and accordingly, the number of rotations of the rotary shaft 44 with respect to the main shaft 14, namely, number of stitches required for one rotation of the cam unit 43 is determined by the ratio of the teeth of the worm 116 to those of the worm wheel 117. The ratio of the teeth of the worm 116 to those of the worm wheel 117 is so determined as to permit the number of rotations of the main shaft 14 with respect to one rotation of the cam unit 43, i.e. the number of stitches to become m, and the ratio of the teeth of the small gear 118 to those of the large gear 120 is so selected as to permit the rotary shaft 44, i.e. cam unit 43 to rotate n times with respect to one rotation of the rotary shaft 20, i.e. feed cam 19. Here, it is assumed that said n is an integral multiple of m. Accordingly, the number of stitches corresponding to one rotation of the feed cam 19 is expressed by m X n. There are formed in the outer peripheral surface of the rest cam 45 of. said cam unit 43 depressions 45a, 45b and 45c into which, when the rest cam 45 is rotated in FIG. 3 in a clockwise direction via the lever 52, shaft 51, operable lever 50 and pin 49 by the fall of the roller 52a of the lever 52 slidably contacting the outer peripheral surface of said feed cam 19 into the cam groove 19c, there can be brought down the rollers 67, 74 and 103 of said stop lever 65, the thread cutting lever 73 and the thread tightening lever 102.

There will now be described an operation of the apparatus according to the embodiment of the invention constructed as mentioned above.

When the drive motor 4 is rotated and the clutch lever 53 is shifted to the operable position by the manually operable apparatus 6, said clutch lever 53 is retained in an operable position shown in FIG. 2, so that the belt travelling from the drive motor is shifted to the movable wheel 57 by the belt guide 58 to rotate the main shaft 14, thus commencing operation. The feed cam 19 and cam unit 43 are rotatedin a direction, for example, indicated by A in response to the rotation of the main shaft 14. In this case, the rest cam 45 of the cam unit 43 is not rotated and remains in a non-operable condition. When the feed cam 19 is rotated, lateral feed signals supplied by the transverse feed groove 19a cause the feed bed 30 to conduct lateral feed movements via the feed lever 21, guide member 25, lateral feed rod 26, lateral feed lower shaft 28 and feed link guide 29. Simultaneously, by the rotation of the cam the forward and backward feed signals supplied from the forward and backward feed groove 19b cause the feed bed 30 to conduct forward and backward feed movements through forward and backward feed lever 32 and guide shaft 33, whereby desired patterns are sewn in the work fabric supported between the feed plate 31 and pressure foot 36 by the cooperation with the needle vertical movement by the rotation of the main shaft 14 when sewing operation is made in this way and accordingly the feed cam 19 makes an approximately l/n rotation, the cam unit 43 makes an approximately one rotation, the roller 67 of the stop lever 65 is brought into a condition that the stop cam 46 is fallen into the cam groove 46a, the roller and pointed body 76 of the thread cutting lever 73 respectively fallen into the cam surface 47b of the thread cutting cam 47 and the lower thread catching stepped portion 77 of the stepped portion constituting body 80, and the roller 104 of the thread tightening lever 102 fallen into the cam groove 48a of the thread tightening cam 48, so that the operation stopping mechanism, thread cutting mechanism and thread tightening mechanism are respectively brought into a condition capable of being operated. However, as above described, at this time, the feed cam 19 makes only a l/n rotation, i.e. only l/n stitches of the total stitches or one sewing cycle, and accordingly if said respective mechanisms should be operated at such time, smooth sewing operation could not be conducted. However, in the embodiment, the rollers 66, 74 and 103 of the respective levers 65, 73 and 102 contact the outer peripheral surface of the rest cam 45 having the same diameter as the respective cams 46, 47 and 48 and even if, accordingly, said roller 67, roller 75, pointed body 76 and roller 104 are brought into a condition capable of being fallen into IMO!" (11 A4 the cam groove 46a, cam surface 47b, lower thread catching stepped portion 77 and cam groove 48a, they are prevented from being fallen thereinto by the operation of the rollers 66, 74 and 103 and rest cam 45. Accordingly, said movement stopping mechanism, thread cutting mechanism and thread tightening mechanism are not operated, whereby sewing operation is continued. Every time the feed cam 19 rotates 2/n, 3/n times, the cam unit 43 rotates 2, 3 times with the result that the respective mechanisms are, as above described, brought into a condition capable of being operated, but said mechanisms are not operated by the operation of the stop cam 45, causing the sewing operation to be continued. When in this way, the feed cam 19 enters the stage of (n-l) n rotations, i.e. the final stage after the (n l rotations and the feed cam 19 is rotated close to the automatic rest position, the roller 52a of the lever 52 abuts on the cam groove 19c of the feed cam 19 at fourth stitch from the automatic rest position to be brought down thereinto, so that the lever 52 is rotated in FIG. 2 in a clockwise direction. Thus, the operable lever 50 is swung in FIG. 3 in a counterclockwise direction via the shaft 51, so that the stop cam 45 of the cam unit 43 is rotated in the same direction via the pin 49 and the rollers 66, 74 and 103 of the stop lever 63, thread cutting lever 73 and thread tightening lever 102 are allowed to abut on the depressions 45a, 45b and 450 of the stop cam 45, whereby the respective levers 65, 73 and 102 are brought to an operable state capable of being actuated.

The levers 65, 73 and 102 corresponding to the respective cams 46, 47 and 48 approximately finishing a group of stitches including one bar tack are in positions shown in FIGS. 7 to 9, respectively, and as the sewing operation proceeds, the respective cams 46, 47 and 48 are rotated in a direction indicated by an arrow A to cause the roller 75 of the thread cutting lever 73 to be brought down into the depression 470 by sliding along the first cam surface 47b and swung and at the same time the pointed body 76 to be contacted with the upper surface of the stepped portion constituting member 80, ,so that the connecting member 81 as well as the connecting piece 82 is moved in a direction indicated 'by an arrow B by the other end of the thread cutting lever 73 thereby to rotate the pinion 88 of the thread cutting means 86 intermeshed with the rack 81a of the connecting member 81 and further dispose the lower thread catching pawl 91a of the thread cutting means 86 in a position near the needle hole 85 so as to be ready to catch the lower thread. When the respective cams 46 to 48 are further rotated immediately before the machine automatically stops, the pointed body 76 of the thread cutting lever 73 abuts on the lower thread catching stepped portion 77 and is fallen thereinto to cause the thread cutting lever 73 to be swung. Said swing movement is, as above described, transmitted to the thread cutting means 86 so as to cause the lower thread catching pawl 91a to be rotated together with the pinion 88 and pass below the needle holes 85 to catch the lower thread. Further, when the respective cams 46 to 48 are rotated, the pointed body 76 of the thread cutting lever 73 abuts on the upper thread catching stepped portion 78 and is fallen thereinto, thereby, the projection 820 of the connecting piece 82 being brought into contact with the stopper 96 and at the same time the upper thread being caught by the upper thread catching pawl 93a of the thread cutting means 86. At this time, the roller 104 of the thread tightening lever 102 abuts on and is brought down into the cam groove 48a of the thread tightening cam 48, so that when said roller 104 is brought to half the depth of the cam groove 48a, the thread tension adjusting member 114 is allowed to contact the stop member 115. The thread tightening connecting rod 109 is moved, in FIG. 9, in a direction (ahead the machine) indicated by an arrow C by the swing of the thread tightening lever 102 resulting from the fall of the roller 104 into half the depth of the cam groove 48a thereby causing the main adjuster 111 to loose the upper thread via the cam body and thread loosing guide shaft 111a, thus permitting the upper thread catching pawl 93a to catch the upper thread smoothly.

As described above, when the respective cams 46 to 48 have been rotated, until they finish a bar tack consisting of a group of stitches, the roller 67 of the stop lever 65 abuts on the cam groove 46a of the stop cam 46 to be fallen thereinto thereby to cause the stop lever 65 to be swung, in FIG. 3, in a clockwise direction, so that the clutch stopping lever 61 is swung, in FIG. 2, in a counter-clockwise direction via the shaft 63. Accordingly, the clutch stopping pawl 62 is disengaged from the clutch lever pawl 60, whereby the clutch lever 53 is swung in a direction where it stops by the clutch lever spring 59, and consequentially the belt is shifted from the movable wheel 57 to the idle wheel 58 by the belt guide 68 to prevent electric power from being transmitted to the main shaft 14 and simultaneously the clutch stopper 56 is engaged with the clutch groove formed in the surface of the movable wheel 57 to stop rotation of the main shaft. Of course, when the rotation of said main shaft 14 is stopped, the needle bar 18, i.e. needle 17 is adapted to be placed in elevated position.

Under a condition where the above machine automatically stops, the thread cutting cam 47 stops so that the pointed body 76 of the thread cutting lever 73 may be allowed to abut on the thread cutting stepped portion 79 and said stopper 96 contacts the projection 82a of the connecting piece 82 of the connecting member 81 so as to prevent said pointed body 76 from being fallen into said stepped portion 79. Further, the thread tightening cam 48 is also stopped under a condition where the roller 104 of the thread tightening lever 102 abuts on the cam groove 48a and is fallen into approximately half the depth thereof, and said roller is prevented from being further fallen into the cam groove by contact of the stop member with the thread tension adjusting member 114. Under such condition, the loops of the upper and lower threads caught by both catching pawls 91a and 93a of said thread cutting means 86 are securely enlarged by the enlarging portion of the plate members 91 and 93 following said pawls 91a and 93a. Further, the stop cam 64 is stopped under a condition where the roller 67 of the stop lever 65 is disengaged from the cam groove 46a.

When the connecting rod 100 is downwardly urged by operation of the foot pedal 7 so as to raise the pressure foot 36 to be operated in order to form the succeeding bar tack on the work fabric clamped between the pressure foot 36 and feed plate 84, since, at this time, the stopping lever pawl 70 is already shifted to a position where it does not face the pressure adjusting pawl 72 by the shift of the clutch lever 53 to the stop position, so that the connection rod 100 is ready to be downwardly urged and the pressure member 42 to be rotated, the rotatable arm 98 is rotated in a direction indicated by an arrow D in FIGS. 3 and 7 via the pin 101 so that the stopper 96 is disengaged from its contact with the projection 82a of the connecting piece 82 of said connecting member 81, whereby the thread cutting lever 73 is permitted to swing to cause the pointed body 76 to be fallen into the thread cutting stepped portion 79 and then the pinion 88 of the thread cutting means 86 is further rotated by the thread cutting lever 73, thus cutting the upper and lower threads. Then, the pressure member 42 is further swung in a counterclockwise direction in FIG. 3 to raise the pressure rod 38 and lift the pressure foot 36 via the lever 39 and the protrusion 36a of the foot 36. However, the stop member 115 mounted on the pressure member 42 is disengaged from its contact with the thread tension adjusting member 114 by rotation of the member 42 before the pressure foot 36 is lifted. Accordingly, the roller 104 of the thread tightening lever 102 is brought down into the deepest portion of the cam groove 48a of the thread tightening cam 48 to swing the lever 102 whereby the thread tightening connecting rod 109 is moved in a direction indicated by an arrow C in FIG. 9 to cause the main adjuster 111 to loose the upper thread and the clamping plate 108 to be rotated so as to urge the needle thread guide 18a, to tighten the cut upper thread and thus the upper thread is prevented from escaping from the needle hole of the needle 17.

When the pressure foot 36 is downwardly urged by releasing operation of the foot pedal 7 and the clutch lever 53 is brought to its operable position by manually operating in order to start a group of the succeeding bar tacks, the main shaft 14 is rotated in a manner mentioned above, so that the feed cam 19 and cam unit 43 are also rotated. When, in this way, the cam unit 43 is rotated, the roller 75 of the thread cutting lever 73 which is fitted into the depression 47a of the thread cutting cam 47 abuts on the second cam surface of said depression 47a and slides along the same. Consequentially, the thread cutting lever 73 is swung in a reverse direction to that caused by the above mentioned fall to allow the upper thread holding member 94 of the thread cutting means 86 to hold the needle side of the upper thread cut together with the needle plate 84. When the sewing operation advances to provide several stitches, the roller 75 becomes to abut on the third cam surface 47d of the depression 47a and slides thereon to cause the thread cutting lever 73 to be further swung in a reverse direction to that described above and then the thread cutting lever 73 and thread cutting means 86 to be returned to their original positions. Substantially at the same time as above, the roller 104 of the thread tightening lever 102 is disengaged from the cam groove 48a of the thread tightening cam 48 to cause the thread tightening lever 102 tobe swung in a reverse direction to that described above and thus the thread tightening connecting rod 109 to be moved in a direction indicated by an arrow C in FIG. 9 thereby to release the tension of the upper thread by the tightening plate 108 and simultaneously the loosening of the upper thread by the mainadjuster 111. When the feedcam 19 is further rotated, for example, corresponding to about four stitches after the stop point as above described, the roller 52a of the lever 52 is disengaged from the cam groove 19c of the feed cam 19 to swing said lever 52 in a reverse direction to that described above. Accordingly, the operable lever is swung in a counterclockwise direction in FIG. 3 to cause the rest cam 45 of the cam unit 43 to be rotated via the pin 49 in the samedirection so that the rollers 66, 74 and 103 of the stop lever 65, thread cutting lever 73 and thread tightening lever 102 are allowed to contact the outer peripheral surface of the stop cam 45 without being falleninto the depressions 45a, 45b and 450, whereby the respective levers 65, 73 and 102 are retained in the non-operable position. Resultantly, the stop mechanism, thread cutting mechanism and thread tightening mechanism are not operated freely from the rotation of the cam unit 43 until the feed cam 19 is rotated to come near the automatic stop position.

As abovedescribed, according to the embodiment of the invention, the stop mechanism, thread cutting mechanism and thread tightening mechanism may be retained in a non-operable position by the rest cam 45 of the cam unit 43 freely from therotation thereof until the feed cam 19 is rotated to come near the automatic stop position, and said respective apparatuses are brought, when the cam unit 43 makes final rotation, into a condition capable of being operated by the operational signals produced by the feed cam 19 (by the cam groove 19c of the feed cam 19). Accordingly, if the ratio n of the rotation of the cam unit 43 to that of the feed cam 19 is set to an arbitrary number of integral multiples of the number m of stitches (the number of rotation of the main shaft 14) corresponding to one rotation of the cam unit 43, there can be made optional sewing operation having the number m X n of stitches. There can be changed over the number of stitches without performing the timing of the operation and the adjustment of the position of the stop mechanism, thread cutting mechanism and thread tightening mechanism only by replacing the small gear 118 and large gear 120 providing said ratio n and the feed cam 19 providing the number m X n of stitches and desired patterns of stitches corresponding thereto.

Referring to FIGS. 11 to 13, there will now be described another embodiment wherein the same members and parts as those of the preceding embodiment are denoted by the same reference numerals and the detailed description thereof is omitted.

The second cam or feed cam 19 is horizontally disposed in the lower part of the leg member 13 and arm bed 12 and the rotary shaft 20 is supported by a journal bearing 12a formed in the arm bed 12 in a manner to extend upwardly. A lateral feed lever 124 and forward and backward feed lever 125 having rollers 124a and 125a respectively fitted into the transverse feed groove 19a and forward and backward feed groove 1% of said feed cam 19 are allowed to move said feed bed 30 transversely, in a forward or backward direction in response to lateral feed signals and forward and backward feed signals produced by the respective grooves 19a and 19b to form the desired patterns of stitches, which is as in the preceding embodiment. The stop lever 65 only has the roller 67, and the thread

Claims (8)

1. Cyclic sewing machine comprising a frame including a work supporting bed, drive means, a main shaft journaled in said frame, a reciprocable needle supported on said frame and movably connected to said main shaft, motion control mechanism disposed between said main shaft and said drive means for controlling the start and stop of said main shaft, a thread cutting mechanism mounted on said frame for cutting threads, a work clamp mechanism movably supported on said work supporting bed to move across the reciprocating path of said needle, first cam disk means mounted on said frame and movably connected to said main shaft for controlling the operation of said motion control mechanism and said thread cutting mechanism at the end of each sewing cycle corresponding to a predetermined number of stitches, first cam follower means operatively connecting said first cam disk means with said motion control mechanism, second cam follower means operatively connecting said first cam disk means with said thread cutting mechanism, second cam disk means for imparting feed movement to said work clamp mechanism with a number of stitches equal to an integral multiple of those corresponding to one cycle of said first cam disk means, driving connections provided between said second cam disk means and said main shaft for rotating the second cam disk means to such extent that the ratio of the angular velocity of said second can disk means to that of said first cam disk means takes a value arrived at by dividing the number of stitches corresponding to said first cam disk means by the number of stitches corresponding to said second cam disk means, third cam follower means operatively connecting said second cam disk means with said work clamp mechanism, and means for rendering said motion control mechanism and thread cutting mechanism inoperable, notwithstanding the rotation of said first cam disk means until just before the rotation for imparting a one cycle feed movement to said work clamp mechanism is completed.

2. A cyclic sewing machine according to claim 1, wherein said second cam disk means is adapted to be exchanged for another cam disk means for imparting different feed movement to said work clamp mechanism, and said driving connections include selectively exchangeable gear means.

3. A cyclic sewing machine according to claim 1, wherein the means for rendering the motion control and thread cutting mechanisms includes at least two cam portions formed on the circumference of said second cam disk means to permit the operation of said motion control mechanism and said thread cutting mechanism by the rotation of said second cam disk means and said cam portions are formed at an equal interval and along the periphery of said second cam disk means at an equal interval corresponding to a number of stitches equal to an integral multiple of a number of stitches corresponding to one cycle of said first cam disk means.

4. A cyclic sewing machine according to claim 1, wherein said motion control mechanism and thread cutting mechanism are rendered inoperative by releasing engagement between said first cam disk means and both cam follower means.

5. A cyclic sewing machine according to claim 4, wherein the last mentioned means further includes a cam surface formed on said second cam disk means, and a cam following mechanism operatively connecting said cam surface with said both follower means or said first cam disk means.

6. A cyclic sewing machine according to claim 1, wherein the last mentioned means includes a control disK arranged adjacent to said first cam disk means for releasing said first and second cam follower means from the first cam disk means.

7. A cyclic sewing machine according to claim 6, wherein said first cam disk means includes a pair of cam elements for controlling said first and second cam follower means respectively and said control disk includes a pair of control elements, each of said cam elements and said control elements being arranged alternately on an axis, and said first cam disk being moved along said axis for releasing said first and second cam follower means from the related cam element.

8. A cyclic sewing machine according to claim 1, wherein the last mentioned means includes a cam surface formed on said second cam disk means, and a cam following mechanism operatively engaged with said cam face and control disk operatively connected with said cam following mechanism.

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