Having set forth the nature of this invention,
what is claimed herein is
1. In a sewing machine having a pattern cam exchangeable on a cam accommodating seat and tracked by a pattern cam follower biased toward tracking relation with said pattern cam, a pattern cam ejecting mechanism comprising an operator influenced control cam carried on said sewing machine and shiftable into and out of cam ejecting position, said control cam being formed with a pattern cam ejecting cam track and a pattern cam follower retracting cam track, a cam ejecting lever on said sewing machine traversing said pattern cam accommodating seat and including a follower finger engaging said pattern cam ejecting cam track of said control cam, pattern cam follower retracting linkage carried on said sewing machine and including a follower finger engaging said pattern cam follower retracting cam track on said control cam, said follower finger on said pattern cam follower retracting linkage being so arranged as to engage said cam follower retracting cam track at a varying angle as said control cam is shifted out of cam ejecting position as to impart to said control cam a restoring force urging said control cam out of cam ejected position which restoring force increases in magnitude directly in proportion to the shift of said control cam out of cam ejected position, said follower finger on said cam ejecting lever being so arranged as to engage said pattern cam ejecting track at a varying angle as said control cam is shifted out of cam ejecting position, as to impart upon insertion of a fresh pattern cam on said cam accommodating seat a restoring force urging said control cam out of cam ejected position which restoring force decreases in magnitude directly in proportion to the shift of the control cam out of cam ejected position.
2. A pattern cam ejecting mechanism as set forth in claim 1 in which said follower finger on said pattern cam follower retracting linkage is so arranged relatively to said cam follower retracting cam track such that no restorative force is applied to said control cam in the full cam ejected position and said restorative force arises only after a discrete increment of movement of said control cam out of full cam ejected position.
3. A pattern cam ejecting mechanism as set forth in claim 2, in which said restorative force applied to said control cam by the follower finger on said cam ejecting lever is effective to impart to said control cam said discrete increment of movement out of full cam ejected position.
4. A pattern cam ejecting cam mechanism as set forth in claim 1, in which said operator influenced control cam comprises a dial supported for turning movement in said sewing machine, in which said follower finger on said pattern cam follower retracting linkage tracks a cam follower retracting cam slot formed in said dial, and in which in the full cam ejected position of said dial, said follower finger occupies a position in said cam follower retracting cam slot which extends substantially tangentially to the pivot axis of said control dial.
BACKGROUND OF THE INVENTION
Pattern cam ejection mechanisms are known in the art which are not associated with follower retracting devices. My prior U.S. Pat. No. 3,457,887, July 29, 1969 discloses such an ejection mechanism. Where a single cam follower is involved, the problem of cam follower interference with cam exchange is not a serious one, and usually the follower may be deflected easily by a movement of the cam during cam exchange.
Where two or more cam tracks and a corresponding plurality of followers are employed, however, retraction of the followers becomes essential in order to facilitate cam exchange. A separate operator influenced control may be used to effect such follower retraction, but then cam exchange becomes unduly complicated. Moreover, where one hand of the operator must be occupied to hold the control instrumentality for maintaining the followers retracted, manipulation of pattern cams between the sewing machine and a storage container must be managed with only one hand, which manipulation can become extremely inconvenient.
BRIEF SUMMARY OF THE INVENTION
It is an object of this invention to provide a pattern cam ejecting mechanism with an associated cam follower retracting device worked by a single operator influenced control which assumes a stable condition in the cam ejected position maintaining the followers retracted without further operator manipulation. The mechanism is automatically shifted so as to restore the followers into cam tracking relation when a fresh pattern cam is inserted into operative position in the sewing machine.
This object is obtained by the provision of a single control dial with not only a cam surface for working the pattern cam ejector, but also with a connection to a spring loaded cam follower retracting linkage. The spring loaded cam follower retracting linkage is so connected to the control dial as to apply a retrograde turning movement to the control dial tending to return the control dial to a position to which the cam followers are fully effective. As the control dial is shifted into pattern cam ejected position, however, the connection of the follower retracting linkage with the control dial shifts so as remove the turning moment or to apply a turning moment in the opposite direction to the control dial urging control dial into a stable follower throw-out position against a fixed stop. Pressure exerted by insertion of a newly slected pattern cam causes the cam ejector to react with its co-operating cam surface on a control dial to impart retrograde turning movement to the dial sufficient to return the connection of the follower retracing linkage back into position in which it will apply retrograde turning movement to the control dial so as to return the cam followers into cam tracking relationship.
DESCRIPTION OF THE DRAWINGS
A preferred form of this invention is illustrated in the accompanying drawings in which;
FIG. 1 represents a top plan view of an exchangable pattern cam mechanism for both needle jogging and work feeding mechanisms of a sewing machine with my invention applied thereto shown with the parts in position during sewing,
FIG. 2 is a front elevational view of the mechanism of FIG. 1,
FIG. 3 is a top plan view of portions of the mechanism of FIG. 1 but showing the parts in the cam eject position,
FIG. 4 is a front elevational view of the control dial and cam ejecting lever of FIG. 3,
FIG. 5 is a front elevational view of the control dial and cam follower retracting linkage of FIG. 3,
FIG. 6 is a front perspective view of the pattern cam ejecting lever and control dial showing the position of parts as a fresh pattern cam is about to be inserted, and
FIG. 7 is a disassembled perspective view of the control dial together with its pivot stud and a detent means to assist in maintaining the mechanism in cam ejected position.
Referring particularly to FIGS. 1 and 2 of the drawings a portion of the frame 11 of a sewing machine is illustrated in which is journaled a main drive shaft 12 of the sewing machine. By means of a crank 13 on the main drive shaft, operative movements are imparted to a needle thread take up device 14 and endwise reciprocation is imparted to a needle carrying bar 15. The needle bar is reciprocated in a gate 16 which is fulcrummed in the machine frame so that the needle bar may be jogged laterally to produce zigzag stitches. A drive link 17 pivoted at 18 to the needle bar gate serves to impart jogging motion to the needle bar from a zigzag actuating mechanism indicated generally at 20 in the drawings.
The zigzag actuating mechanism 20 includes an ocillating bracket 30 pivoted to swing about a pivot pin 31 carried by a lever 32 having a fulcrum 33 in the machine frame. A cam follower pin 34 on the ocillating bracket 30 tracks a zigzag pattern cam 35 which is maintained by a spring clip 36 in engagement with an off-center drive pin 37 on a cam seat 38 formed on a vertical cam shaft 39 journaled in the machine frame 11. The cam shaft 39 carries a worm wheel 40 meshing with a worm 41 on the main drive shaft.
The needle bar drive link 17, which is biased towards the left as viewed in FIG. 2 by a spring 42 stretched between the drive link 17 and the machine frame 11, carries a slide block 43 which engages the right hand side of the oscillating bracket 30 as viewed in FIG. 2. A crank pin 44 carried by a bight adjusting dial 45 in the machine frame is embraced by a slot 46 in the needle bar drive link 17 and serves to shift the slide block 43 along the oscillating bracket relatively to the pivot pin 31 thereof in order to regulate the bight of zigzag stitches. A linkage 47,48 connects the lever 32 with a needle position adjusting dial 49 in the machine frame by which the needle position to the right, center, or left of the field of zigzag stitches may be regulated.
As shown in FIGS. 1, 2, and 6, the zigzag pattern cam 35 is formed as the lower most one of a paired set of cams indicated generally at 60 which is permanently fastened together and of which the upper cam is a work feed pattern cam 61.
The follower mechanism for the work feed pattern cam 61 may be carried by a support bracket 62 secured by screws 63 in the machine frame 11. Pivoted on a fulcrum pin 64 in the support bracket 62 is a feed follower lever 65 to which a cam follower member 66 is adjustably secured by a clamp screw 67. A stop member 68 may be similarly secured by a clamp screw 69 to the feed follower lever to abut the machine frame and thus limit movement of the feed follower lever in a direction away from the work feed pattern cam 61.
The feed follower lever 65 carries a roller 70 embraced by a bifurcated extremity 71 of a lever 72 fulcrummed on a pin 73 carried in a regulating slide 74. A spring 75 stretched between the lever 72 and the machine frame 11 biases the feed follower lever 65 toward the work feed pattern cam 61.
The lever 72 may be connected with the regulator of any known type of sewing machine work feed mechanism so that the work feed pattern cam 61 can automatically influence the direction and magnitude of work feed between successive stitches. This mechanism is particularly adapted to regulate the work feeding movement of a four motion drop feed mechanism of a sewing machine but it is also suitable for use with any other known type of sewing machine work feeding mechanism.
A dial 80 journaled on a pin 81 in the machine frame 11 carries an eccentric 82 which is embraced by the regulating slide 74 on which the fulcrum pin 73 for the lever 72 is carried. The regulating slide 74 is formed with a notch 83 which slidably embraces an anchor pin 84 on the support bracket 62. By turning the dial 80 the balance between forward as compared with reverse direction of feed when in cam control feed mode may be regulated and in an extreme position of the dial 80 the cam control of the feed regulation may be completely disabled.
With the zigzag and work feed pattern controlled by paired sets of pattern cams 60, it will be appreciated that the stitch pattern will be produced by the sewing machine will depend on the particular cam set 60 which is inserted in place on the cam shaft seat 38. This invention provides a mechanism which by the application of one operator influenced motion serves to retract both cam followers 66 and 34 out of tracking relation with the respective pattern cams 61 and 35 and simultaneously eject the pattern cam set 60 from the influence of the spring clip 36 on the cam seat. This mechanism then without further operator influence, will maintain the followers in retracted position in readiness for insertion of a different selected cam unit 60.
As shown in FIGS. 1, 2 and 7, a control dial 90 is provided for manually influencing ejection of a cam unit 60 from the cam seat 38. The control dial 90 is rotatable on a bearing sleeve 91 which is clamped to the machine frame by a shoulder screw 92 as shown in FIG. 2. Also clamped in fixed position relatively to the machine frame by the shoulder screw is a washer 93 formed with a radial detent flange 94 and a second washer 95 having an anchor hole 96 formed therein for one extremity of a coil spring 97. The other extremity of the coil spring 97 is accomodated in a similar anchor hole 98 formed in a hub 99 on the control dial 90. The coil spring 97 biases the dial 90 in a clockwise direction as viewed in FIG. 1 and the detent finger 94 co-operates with a detent notch 100 formed atop a cam block 101 on the control dial 90. The detent finger and co-operating detent notch serve releasably to maintain the control dial in the fully ejected position of the pattern cam unit as shown as FIGS. 3 and 4.
The cam block 101 is formed with a sloping control cam track 102 arranged for co-operation with a follower finger 103 which depends from a pattern cam ejecting lever 104. The cam ejecting lever 104 is pivotably supported on a fulcrum pin 105 secured on a bracket 106 held by a fastening screw 107 on the machine frame. A free end of the pattern cam ejector lever 104 is formed with bifurcate arms 108 which straddle the cam seat 38 on cam shaft 39 and underlie the pattern cam unit 60 placed thereon. As the control dial is turned in a counterclockwise direction as viewed in FIG. 1 into the position shown in FIGS. 3 and 4 the control cam track 102 will cause the cam ejector lever to be elevated thus to force the pattern cam upwardly out of influence of the spring clip 36 and off the cam seat 38.
The control dial 90 is also formed with a control cam slot 120 which, as shown in FIGS. 1 and 7, is preferably straight but inclined at a slight angle radially outward from the center of the control dial 90. A block 121 may be added on the dial 90 to increase the thickness of the outer wall slot 120.
The control cam slot 120 is tracked by a follower pin 122 depending from a lever arm 123 which is adjustably secured to a lever body 124 fulcrummed on a pivot pin 125 carried in the support bracket 62. The adjustable connection between the lever arm 123 and the lever body 124 may include a pivot pin 126 and spaced from the pivot pin a clamp screw 127 which is threaded into the lever arm 123 and passes through an elongated slot 128 in the lever body 124. The lever body 124 carries a finger 129 which abuts the feed follower lever 65, and the lever body 124 also carries a finger 130 which abuts the oscillating lever 30 of the zigzag actuating mechanism 20. The finger 130 is preferrably secured to the lever body with capacity for limited adjustment thereon as by a locating pin 131 carried by the lever body and engaging an elongated slot 132 in the finger 130 together with a clamp screw 133 which passes through the slot 131 and is threaded into the lever body 124. The adjustments provided by the fastenings for the lever arm 123 and the finger 130 provide for a nicety of co-operation and co-ordination of the cam follower retracting mechanism with both the feed and zigzag cam followers.
When the cam follower retracting linkage 123 - 124 becomes effective, the return springs 75 and 42 will exert a force by way of the lever arm 123 and the follower pin 122 and the cam slot 120 on the control dial 90. When the control dial 90 occupies its position as shown in FIG. 1 the force exerted by the springs 75 and 42 on a control dial will be exerted in the direction of the arrow placed on FIG. 1 and will act to urge the control dial in a clockwise direction as viewed in FIG. 1. In other words, the result of the spring force will urge the control dial into the position shown in FIG. 1 in its extreme clockwise position. When the control dial 90 has been turned in a counterclockwise direction to the fully ejected position of a pattern cam unit 60 as shown in FIG. 3 the relationship between the follower pin 122 and the slot 120 in the control dial are changed so that the direction of the application of the force of the springs 75 and 42 will assume that of a substantially radial direction on the control dial 90 as shown by the arrow in FIG. 3 thus exerting little or no influence on turning movement of a control dial. Because of this relationship, the mechanism in the fully ejected position of the cam as shown in FIGS. 3 and 4 will be a stable position of the parts, and the mechanism will retain this position without additional operator influence.
As illustrated in FIG. 6 when a fresh cam unit 60 is placed over the bifurcated extremity of the cam ejecting lever 104 and a downward pressure is applied to seat the cam on the cam seat 38, the follower finger 103 will exert a clockwise direction of turning movement to the control dial 90 because it rests on the steep slope 102 of the cam track. The turning movement applied to the control dial 90 by the exertion of the fresh cam onto the stack shifts the follower pin 122 of the follower retracting linkage along the slot 120 sufficiently to cause the application of the force of the springs 75 and 42 to take a direction increasingly at an inclination to the radial as illustrated in FIG. 3. The springs 75 and 42 therefore will apply an increasing magnitude of restoring force to the control dial 90 urging continued clockwise movement of the control dial into the position illustrated in FIG. 1. Insertion of a fresh cam unto the seat 38 of the cam shaft, therefore, will automatically bring into play the return of the cam followers into tracking relation with the pattern cams of the cam unit without the requirement of additional operator attention.