US3526187A

US3526187A - Toggle controlled strapping apparatus and method

Info

Publication number: US3526187A
Application number: US764456A
Authority: US
Inventors: Allen F Gilliard
Original assignee: Signode Corp
Current assignee: Signode Corp
Priority date: 1968-10-02
Filing date: 1968-10-02
Publication date: 1970-09-01
Anticipated expiration: 1987-09-01

Description

United States Patent [72] Inventor Allen F. Gilliard Western Springs, Illinois [211 App]. No. 764,456 [22] Filed Oct. 2, 1968 [45] Patented Sept.l,l970 [73] Assignee Signode Corporation a corporation oi Delaware [54] TOGGLE CONTROLLED STRAPPING APPARATUS AND METHOD 25 Claims, 22 Drawing Figs.

[52] US. Cl 100/2,

100/4, 100/26, 100/30, 140/934, 226/143 [51] Int. Cl B65b 13/02 [50] Field otSearch 226/143;

[56] References Cited UNITED STATES PATENTS 2,195,043 3/1940 Wright 100/26 2,215,121 9/1940 Harvey et al.. 100/26X 2,730,036 1/1956 Cheesman.... [OD/32X 3,183,824 5/1965 Cook 100/26X Primary Examiner-Billy .l. Wilhite A!t0rney-Dressler, Goldsmith, Clement and Gordon over center to an operative tensioning position in responseto the completion of a strap loop, and to an operative feeding-"- position in response to the drawing ofa preselected amount of tension in the strap. The toggle linkages are controlled by eccentric drive structures for moving the feed wheel into an active strap engaging position when the toggle linkages are at the operative feeding position, and for moving the tension wheel into active strap engaging position when the toggle linkages are in operative tensioning position. The eccentric means also control the toggle linkages to move the feed wheel to an inactive position so that the toggle linkages can move from the tensioning position to the feeding position without the feed wheel engaging the strap, and to move the tension wheel to an inactive position so the toggle linkages can move from the feeding position to the tensioning position without the tension wheel engaging the strap.

The sealing head structure is actuated by a crank controlled reciprocating crosshead, and the crank is rotated in response to the toggle linkages moving over center after tension is drawn in the strap.

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Sheet '5 of 11 Patented Sept. 1, 1970 3,526,187

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Sheet 5 of 11 jive] awn/ JM,W wan 5 9mm Patented Sept. 1, 1979 3,526,187

Sheet 6 of 11 Patented Sept. 1, 1970 3,526,187

Sheet 7 of 11 Patented Sept. 1 1970 Sheet Patented Sept. I, 1976 Sheet jivenior" Patented Sept. 1, 1976 3,526,187

Sheet II of 11 f a l ezz/ 9 gb.

TOGGLE CONTROLLED STRAPPING APPARATUS AND METHOD BACKGROUND OF THE INVENTION In the past, it has been well known to provide strapping apparatus with a reciprocable sealer crosshead for notching and crimping a seal about overlapping strap portions. Such machines have conventionally been either pneumatically or hydraulically powered, and a typical arrangement is disclosed in Crosby et al. Pat. No. 2,8OI,558, the disclosure of which is incorporated herein in its entirety by this reference. While such machines have, in general, functioned satisfactorily, certain problems have arisen, particularly after extended periods of use.

More particularly, in pneumatically or hydraulically powered prior art devices, positive sealing means must be provided in the piston cylinders, and such sealing means have a tendency to deteriorate after prolonged periods. Furthermore, prior art devices have conventionally included somewhat complicated electrical controls to properly time and sequence the various functions of the apparatus. These controls have sometimes proven to be unreliable, and are costly to maintain and replace.

The strap feeding and tensioning mechanisms of prior art automatic strapping machines have also not been entirely satisfactory. In some machines, a single rotatable member is provided to feed strap when the member rotates in one direction and to tension strap when the member rotates in an opposite direction. Such arrangements have necessitated the use of costly and somewhat complex means for reversing the direction of rotation of the strap feed member. In other known automatic strapping machines, separate members have been used to feed and tension the strap, but heretofore these arrangements have been complicated, costly and unreliable.

SUMMARY OF THE INVENTION The apparatus and method of the present invention obviate the problems of the prior art noted above by providing an arrangement which is essentially purely mechanical, thus eliminating problems inherent in pneumatically or hydraulically powered machines, and also eliminating the necessity of costly electrical controls. In the apparatus of the present invention, a simple clutch controlled crank arrangement is employed to reciprocate the sealer crosshead, and the clutch is controlled by a novel latch arrangement that is responsive to the drawing ofa predetermined amount of tension in the strap.

The apparatus of the present invention includes a novel strap feeding and tensioning arrangement, wherein individual continuously rotating strap feeding and tensioning wheels are carried by mechanically coupled toggle linkages, with eccentric means being operative upon the toggle linkages to move the feeding and tensioning wheels between inactive and active strap engaging positions. The toggle linkages are thrown over center in a first direction in response to the completion of a strap loop and the arresting of the strap, and the toggle linkages are thrown over center in an opposite direction in response to the drawing ofa predetermined amount oftension in the strap.

The movement of the strap feed wheel to active strap feeding position takes place automatically in response to the completion of the sealing cycle by a novel cam and linkage arrangement that is operative in response to the movement ofa seal ejecting mechanism from a seal ejecting to a seal dispensing position. The movement ofthe tension wheel to the active strap engaging position is responsive to a manually controllable rotary solenoid.

The apparatus of the present invention also includes a novel gripping jaw mechanism that is released in response to the completion of a strap loop for allowing the gripping jaws to move into engagement with the strap. The actuation of the gripperjaw mechanism controls a strap holding pawl which allows tension to be drawn in the strap, and which retains the tension after it is drawn.

The many objects and features of the invention will hereinafter become apparent from the following description, taken in connection with the annexed drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS trating the gear drive means for continuously rotating the feed wheel and the tension wheel;

FIG. 4 is an enlarged vertical sectional detail of the ejector mechanism in the seal dispensing position;

FIG. 5 is a view similar to FIG. 4, but illustrating the ejector mechanism in the seal ejecting position;

FIG. 6 is a vertical sectional view similar to FIGS. 5 and 6, but in a different plane, and illustrating the structure for controlling the tension wheel and feed wheel eccentrics;

FIG. 7 is a sectional view taken generally along line 77 of FIG. 6, with certain parts broken away for clarity of illustratron;

FIG. 8 is a sectional view taken generally along line 88 of FIG. 6, and also has certain parts broken away for clarity of illustration;

FIG. 9 is a detail view illustrating the sealer crosshead actuating structure, and FIG. 9 is also taken on a vertical plane through the apparatus with certain parts broken away for clarity of illustration;

FIG. 10 is a view similar to FIG. 9, and illustrating certain of the parts in a different position during sealer crosshead actuatron;

FIG. 11 is a front elevational view of the sealing head structure and illustrates the strap re-entering and arresting mechanism in a normal position;

FIG. I2 is a view similar to FIG. 11, and illustrates the structure in a strap arresting position;

FIG. 13 is a sectional view taken generally along line l3- l3 of FIG. I], with certain parts broken away for clarity of illustration;

FIG. 14 is a fragmentary sectional view similar to FIG. 13 il- Iustrating the position of the parts after the strap has been arrested;

FIG. I5 is a fragmentary sectional view similar to FIGS. 13 and 14, and illustrates the position of the parts just prior to return movement of the sealer crosshead;

FIG. I6 is an enlarged sectional view taken generally along line l616 of FIG. 13, and illustrates the gripper jaw mechanism;

FIG. 17 is a sectional view taken generally along line 17- -17 of FIG. 13 and illustrates the mechanism for actuating the gripper jaw structure;

FIG. 18 is an enlarged sectional view taken generally along line18-l8 ofFlG. 13;

FIG. 19 is a side elevational detail view of the toggle linkage structures in the tension position, with the tension wheel in active position and the feed wheel in inactive position;

FIG. 20 is a view similar to FIG. 19, but with the toggle linkage structures in feed position, with the tension wheel in inoperative position and the feed wheel in inactive position;

FIG. 21 is a view similar to FIGS. 19 and 20, with the toggle linkage structures in feed position and with the feed wheel in active position and the tension wheel in inactive position; and

FIG. 22 is a view similar to FIGS. l82l, with the toggle linkage structures in the tension position and with the tension wheel in inactive position and the feed wheel in inoperative position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail one specific embodiment, with the understanding that the present disclosure is to be considered as an exemplification of the principles ofthe invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

GENERAL ORGANIZATION Referring now to the drawings in detail, the structure of the present invention is mounted within a suitable housing 30 (FIG. 1), and strap from a supply source (not shown) enters the housing 30 through a guide chute 31 which guides the strap along a strap path to a back-up wheel 32. Strap feed means 33, adjacent the strap path and the back-up wheel 32, moves the strap past the back-up wheel 32 through a guide chute (not shown) and around a package P at a sealing station 34. Means, responsive to the presence of the free strap end, is provided at the strap sealing station 34 for disengaging the strap feeding means 33 and for bringing strap holding means 35 adjacent the back-up wheel 32 into operative engagement with the strap to positively hold the same.

Once the feeding of the strap is completed, strap tensioning means 36, adjacent the strap path and the back-up wheel 32, moves the strap in a direction opposite to strap feeding movement, to draw the strap around the package P with a predetermined force. After the predetermined amount of tension has been drawn in the strap, sealing means 37 is actuated to apply a seal to the overlapping strap portions at the sealing station 34, and the completed loop is severed from the strap supply so that the sequence can be repeated.

STRAP FEEDING, TENSIONING AND HOLDING STRUCTURE The strap feeding means 33 includes a feed wheel 40 that is carried by a toggle linkage means 42 for movement between operative and inoperative positions. The strap tensioning means 36 includes a tension wheel 41 that is carried by a toggle linkage means 43 for movement between operative and inoperative positions. Feed wheel 40 is continuously rotated in a clockwise direction and tension wheel 41 is continuously rotated in a counterclockwise direction by drive means best illustrated in FIG. 3. Toggle linkage means 42 and 43 are synchronized for movement together between fixed stops, as will hereafter be described.

An electric motor (not shown) is supported upon housing 30 and includes a rotary shaft 44 having a pinion 45 thereon. The motor functions to continuously rotate shaft 44, and illustratively the motor may be a one-half horsepower, 110 volt, single phase motor. Shaft 44 rotates in a counterclockwise direction and a large diameter gear 46 on a shaft 47 meshes with gear 45 to rotate shaft 47 and a further pinion 48 thereon in a clockwise direction. A driven gear 49 is mounted upon tension wheel shaft 50 and meshes with gear 48 to rotate the shaft 50 and the tension wheel 41 in a counterclockwise direction. A gear 51 is mounted on feed wheel shaft 52 and is rotated in a clockwise direction by a gear train including gears 53-55 mounted on respective shafts 56-58.

The drive means illustrated in FIG. 3 also includes a gear 62 mounted on a shaft 63 and meshing with gear 48, so as to rotate shaft 63 in a counterclockwise direction. A further gear 64 is mounted on a clutch shaft 65 and meshes with gear 62 so as to rotate in a clockwise direction. A conventional commercially available clutch 70 is coaxially arranged with shaft 65, and includes an output shaft 650 (FIG. 2) having a gear 66 thereon that meshes with a gear 67 on a crankshaft 68 to rotate the crankshaft 68 in a counterclockwise direction. Sealing means 37 is operatively responsive to rotation of crankshaft 68, as will hereinafter appear. Latching means 72 (FIGS. 2, 9 and 10) to be hereafter described, retains the clutch and the shaft 65a against rotation until after tension has been drawn in the strap.

The feed wheel toggle linkage means 42 and the tension wheel toggle linkage means 43 will be best understood from a consideration of FIGS. 13 and 19-22. A mounting block 74 is fixed to housing 30 by set screws 75 and includes a pair of laterally spaced flanges 76 at the forward or right hand side thereof, as viewed in FIGS. 1 and 2. The lower end ofa tension lever 77 is pivotally mounted between flanges 76 by a transverse pivot pin 78, and the upper end of lever 77 presents an upright abutment surface 79 for transmitting the force of a spring means 80 to tension wheel 41.

In the illustrated embodiment, spring means 80 takes the form of a plurality of belleville washers 81 mounted with a generally cylindrical chamber 82 mounted upon housing 30. The far right hand belleville washer 81 engages a platelike abutment 83 having a stem 84 of reduced diameter that extends outwardly of chamber 82 and bears against abutment surface 79 of lever 77. The far left hand belleville washer 81 bears against an abutment disc 85, and a tension adjusting knob 86 has an externally threaded stem 87 extend into chamber 82 through an internally threaded opening in housing wall 88, with the end of stem 87 bearing against abutment disc 85. The belleville washers 81 are compressed to a predetermined extent by adjustment of knob 86 to bias the lever 77 in a clockwise direction about pivot 78 with a predetermined amount of force.

Tension wheel toggle linkage 43 includes a first link 90 pivotally mounted to an intermediate portion oflever 77 by an eccentric portion 91 ofa transversely extending shaft 92 (FIG. 2). Toggle linkage 43 includes a second link 93 pivotally connected at 94 to the end of link 90 remote from eccentric 91. The forward or right hand end of link 93, as viewed in FIG. 1, is bifurcated to provide upright flanges 95. Tension wheel shaft 50 is rotatably mounted in flanges 95, and tension wheel 41 is positioned therebetween. In the strap tension drawing position illustrated in FIGS. 1 and 19, eccentric 91 is positioned in its forward or closed position to dispose the tension wheel 41 in positive gripping engagement with the strap under the urging of spring means 80. Tension wheel 41 is preferably knurled or serrated to enhance its strap gripping ability. Spring means 80 limits the degree to which the counterclockwise rotating tension wheel 41 moves the strap upwardly around backing wheel 32 and to the left in guide chute 31, in that when the predetermined amount of tension has been drawn in the strap (as determined by the setting of knob 86) pivot 94 will break over center to the position of FIG. 20.

The means for urging the feed wheel 40 against the strap in the strap feeding position of toggle linkage means 42 can be best seen from FIG. 1. As is shown therein, a lever is pivoted at 101 between the flanges 76 of mounting block 74, and lever 100 has an offset lower end 102 that presents an upright abutment surface 103 for transmitting the force of a spring means 104 to feed wheel 40. Spring means 104 includes a helical spring 105 in a cylindrical chamber 106 in housing 30, with the left hand end of spring 105 bearing against an abutment disc 107, and with the right hand end of spring 105 bearing against an abutment disc 109. Disc 109 includes a stem 110 of reduced diameter that projects outwardly of chamber 106, with the end of stem 110 bearing against upright surface 103 on lever portion 102. A set screw 111 is threaded through an opening in a wall 112 of housing 30, and the end of set screw 111 bears against abutment disc 107 to compress spring 105 and bias stem 110 outwardly into engagement with lever surface 103.

Feed wheel toggle linkage means 42 includes a first link 115 pivoted to the midportion oflever 100 by an eccentric portion 116 of a shaft 117 (FIG. 2). Toggle linkage means 42 includes a second link 118 pivotally connected at 119 to the end of link 115 remote from eccentric 116. The forward or right hand end of link 118, as viewed in FIG. 1, is bifurcated to provide a pair of upstanding flanges 120 in which feed wheel shaft 52 is rotatably mounted. Feed wheel 40 is positioned between flanges 120, and in the tension position of the toggle linkages illustrated in FIG. 1, the feed wheel 40 is spaced from the strap passing around the back-up wheel 32. In the tension position, the feed eccentric 116 is in the open or left hand position, so that when the toggle linkage means 42 breaks over center, i.e., when pivot 119 moves over a line between

shafts

117 and 52, the feed wheel 40 will remain out of engagement with the strap.

Stops

130 and 132 are located such that the included angle in the operative position between links 90 and 93 (FIGS. 1, 19 and 22) and between links 115 and 118 (FIGS. 20 and 21) is 168, while in the inoperative position the included angle between links 90 and 93 (FIGS. 20 and 21) and between links 115 and 118 (FIGS. 1, 19 and 22) is 165. The decreased angular relationship insures that the feed wheel 40 and tension wheel 41 will be spaced from the strap while in the inoperative position.

Toggle linkage means 42 and 43 are synchronized for movement together by links 122 that are connected between

pivots

94 and 119 at opposite sides of

links

93 and 118. Restraining means in the form of

rollers

124 and 125 are provided on

links

93 and 118, respectively, and

rollers

124 and 125 are received in generally rearwardly

open slots

126 and 127, respectively, in a mounting plate 128 fixed relative to housing 30. A spring 129 biases link 93 toward a fixed stop 130 to properly locate the toggle linkage 43 in the operative tension position, and a spring 131 biases link 118 toward a fixed stop 132 to properly locate the toggle linkage 42 in the operative feed position.

The means for controlling the actuation of the tension eccentric 91 and the feed eccentric 116 will be best understood from a consideration of FIG. 2. As is shown therein, a single revolution clutch 140 of conventional commercially available design, is mounted coaxially with shaft 63, and clutch 140 has an output shaft 630 with a sprocket 141 fixed thereon. A chain 142 is trained over sprocket 141 and over a further sprocket 143 that is fixed to the tension wheel eccentric shaft 92. A further chain 144 is trained over a small diameter sprocket 145 on shaft 92, and over a further sprocket 146 on feed wheel eccentric shaft 117. Idler sprockets 147 and 148 are carried on respective pivotally mounted arms 149 and 150, with the idler sprockets 147 and 148 being urged into engagement with chains 142 and 144 by spring means (not shown) connected between arms 149 and 150 to take up any slack in the chains. The size relationship between

sprockets

141, 143. 145 and 146 is such that when the clutch 140 is actuated to make a complete revolution, tension wheel eccentric shaft 92 and feed wheel eccentric shaft 117 are rotated through 180. As is evident from FIGS. 2 and l9-22, the tension eccentric 91 and the feed eccentric 116 are 180 out of phase with one another, so that when one eccentric is open the other will be closed, and vice versa.

As has been previously explained, the tension toggle linkage means 43 breaks over center when a predetermined amount of tension is drawn in the strap, and the feed toggle linkage means 42 is moved over center with the tension toggle linkage means 43 by the connecting links 122. The toggle linkage means 42 and 43 are thrown over center in an opposite direction after the strap has been completely fed around a package P and arrested to actuate the strap holding means 35.

The strap holding means 35 (FIGS. 1 and 13) includes a rotary pawl 160 that is supported on a link 161, with one way clutch means being associated with the pawl 160 for allowing the pawl to rotate or free wheel in a counterclockwise direction but preventing rotation of the pawl in a clockwise direction. As is evident from FIG. 1, a pair of strap guides 162 and 163 are provided adjacent back-up wheel 32, and the strap guides I62 and 163 have arcuate strap guiding surfaces spaced slightly outwardly of the back-up wheel for guiding strap around the back-up wheel and toward the sealing station 34. The rotary pawl 160 is movable in the space between

guides

162 and 163 from an active position illustrated in FIG.

1 in engagement with a strap, to an inactive position illustrated in FIG. 13 spaced from the strap. To this end, the midportion of link 161 is pivoted at 164 to an arm 165 that extends downwardly from strap guide 163. The end of link 161 remote from pawl 160 is connected at pivot 166 to a generally vertically disposed actuating link 167 that is biased downwardly by a spring 168 (FIG. 13), to bias the pawl 160 toward engagement with the strap.

Actuating link 167 is controlled by a generally L-shaped lever 169 having its midportion pivotally connected at 170 to housing 30. One arm 171 of lever 169 is pivotally connected at 172 to the upper end oflink 167 and a spring 173 is connected between arm 171 and housing 30 to bias the lever 169 in a clockwise direction and urge the link 167 downwardly. A second arm 174 of lever 169 extends generally upwardly into a position where it is engaged by a pin 175 associated with a gripping jaw cross head as will be later explained in connection with the structure at the sealing station 34. In the position illustrated in FIG. 13, pin 175 has pivoted lever 169 in a counterclockwise direction to lift the link 171 upwardly against the bias of spring 168 to pivot link 161 and thus move pawl 160 to the inactive position spaced from the back-up wheel 32. The pawl 160 remains in the inactive position during the strap feeding cycle, as will hereinafter be explained, and once the strap has completed its travel around the package, pin 175 moves to the right out of engagement with lever arm 174 to allow the spring 168 to move the actuating link 167 and bring the pawl 160 into engagement with the strap. Once the pawl 160 moves into engagement with the strap, it is positively stopped and the toggle linkage means 42 and 43 break over center from the strap feeding position of FIG. 21 to the feed completion position of FIG. 22. Pawl 160 remains in the active strap holding position through the strap tensioning operation and through a major portion of the strap sealing cycle, as will be hereinafter explained.

SEALING HEAD STRUCTURE The apparatus for feeding and crimping a seal around the overlapping strap portions at the sealing station 34 is essentially conventional, and reference may be made to Crosby et al. Pat. No. 2,801,558 and Ericsson Pat. No. 3,198,218 for details of the structure not specifically disclosed herein. With reference to FIG. 1, the structure at the sealing head includes, starting from bottom to top, a guiding plate 180, gripper jaw means 181, sealing jaw means 182, gathering jaw means 183 and seal ejector means 184.

The means 37 for actuating the strap sealing structure includes a sealer crosshead 185 that is slidably and reciprocably mounted in an opening 186 in a cross wall 187 of the housing 30. The rear, or left hand end as viewed in FIG. 1, of sealer crosshead 185 is slotted as at 188 to receive a transversely extending pin 189. The forward or right hand end ofa connecting rod 190 is pivotally mounted on pin 189, and the left hand I end of connecting rod 190 is pivotally connected to a crank portion 191 of shaft 68. As has been previously mentioned, latch means 72 (FIGS. 2, 9 and 10) normally retains clutch 70 against rotation, so that during strap feeding and tensioning the crosshead 185 is in the position illustrated in FIG. 1. When the final tension has been drawn in the strap to break the toggle linkage means 42 and 43 over center, the latch means 72 is released and the crankshaft 68 is rotated by gears 66 and 67 As is evident from FIG. 2, the step down relationship between gears 67 and 66 is such that shaft 68 will rotate at one half the speed of the output shaft 65a of the clutch 70.

The latch means 72 will be best understood from FIGS. 9 and 10, and as illustrated therein, the latch means 72 includes a link 194 pivotally connected at one end at 195 to the housing 30, and having an upright detent surface 196 at the opposite end for normally retaining the clutch 70 against rotation. An extension link 197 is secured to link 194 by bolts 198, and link 197 is biased in a counterclockwise direction about pivot 195 by a spring 199 connected between link 197 and the housing 30. It will be appreciated that spring 199 positively biases the detent surface 196 on link 194 into engagement with a corresponding abutment on the clutch 70.

A generally vertically disposed latch release link 200 has its lower end pivotally connected to the second link 93 of the tension wheel toggle linkage means 43, and illustratively, the link 200 may be pivotally connected to an extension of the tension wheel shaft 50. The end of link 197 remote from pivot 195 includes a transverse abutment pin 202, and a perpendicularly disposed surface 203 on link 200 bears against the upper surface of pin 202 for pivoting the link 197 in a clockwise direction as the toggle linkage means 42 and 43 break over center when final tension is drawn in the strap. A spring 204 is connected between housing 30 and the upper end of link 200 to bias the link 200 in a counterclockwise direction about tension wheel shaft 50 to positively retain the link abutment 203 in engagement with the pin 202.

A disc 205 is mounted for rotation with crankshaft 68, and a pin 206 extends outwardly from disc 205 into a position for engaging link 200 to pivot the link 200 against the bias of spring 204 when the disc 205 is rotated in a counterclockwise direction to bring the pin 206 into engagement with the link 200. As is evident from comparing FIGS. 9 and 10, pin 206 does not move into engagement with link 200 until after shaft 68 has rotated more than 180. Thus, when the link 200 is moved downwardly as the toggle linkage means 42 and 43 break over center to free the detent surface 196 from the clutch 70, pin 206 does not engage link 200 to pivot the link surface 203 out of retentive engagement with pin 202 until after the clutch 70 has completed 360 of rotation. In this manner, the clutch 70 will make two complete revolutions before its rotation is arrested by detent 196. Accordingly, crankshaft 68 will be rotated through a full 360.

When the disc 205 has rotated through 210, the link 200 will be pivoted in a clockwise direction about tension wheel shaft 50 to free pin 202 from surface 203, so that the spring 199 will pivot link 194 in a counterclockwise direction about pivot 195 to reposition the detent surface 196 on the clutch 70. The link 200 will remain in the down position until the toggle linkage means 42 and 43 are again thrown over center when the strap feeding cycle is completed, and the resulting upward movement of the link 200 will reposition the pin 202 in the notch adjacent surface 203, to ready the latch means 72 for further actuation.

From the foregoing, it will be appreciated that when the latch means 72 is released. crankshaft 68 will be rotated in a counterclockwise direction to reciprocate sealer crosshead 185 back and forth by an amount equal to the throw of the crank portion 191 of shaft 68. Movement of the sealer crosshead 185 to the right in FIG. 1 will hereinafter be referred to as the downstroke while return movement of the crosshead 185 to the left will hereinafter be referred to as the upstroke.

The seal ejector mechanism 184 is actuated by reciprocation of the sealer crosshead 185, and will be best understood from a consideration of FIGS. 1, 4-8 and 18. A downwardly inclined, generally U-shaped in' crosssection, seal storage magazine 210 is provided at the upper end of the housing 30, and terminates adjacent the seal ejector mechanism 184. The seal ejector mechanism 184 includes a pair of genrally indentically shaped

ejector arms

211 and 212 that are connected by a pivot 213 to an arm 214 that extends upwardly from a housing 30. The ejector arms 21] and 212 are generally L-shaped, and include a generally forwardly extending portion 215 and a generally downwardly extending portion 216. The end of each ejector arm portion 215 remote from pivot 213 includes a forwardly opening notch 217, and a transversely extending pin 218 at the upper end of a seal ejector member 219 is positioned in the aligned notches 217 in the

ejector arms

211 and 212.

The lower end of ejector arm portions 216 have a cam follower roller 220 mounted thereon, and rollers 220 engage cam surfaces 221 at opposite sides ofa block 222 that is secured to the sealer crosshead 185. As can be seen in FIG. 1, the block 222 is fixedly secured to crosshead 185 by a screw 223. Spring means, not shown, bias the

ejector arms

211 and 212 in a clockwise direction about 213 toward the seal depositing position illustrated in FIG. 4. As the crosshead 185 begins its downstroke, followers 220 ride up cam surfaces 221 to pivot the

ejector arms

211 and 212 in a counterclockwise direction to the position of FIG. 5 to cock the ejector member 219 in a position for ejecting a seal from magazine 210.

Means is provided for latching the

ejector arms

211 and 212 in the cocked position of FIG. 5, and the latch means includes a latch member 230 pivotally mounted at 231 to housing 30. A spring 232 biases latch member 230 in counterclockwise direction about pivot 231, and latch member 230 includes a forwardly extending finger 233 that is moved into engagment with ejector arm 211 (FIG. 18) under the urging of spring 232 when the crosshead 185 moves to the position of FIG. 5. Latch member 230 includes an upwardly extending finger 234 that engages the cross wall 187 to limit the movement of the latch member 230, and a downwardly extending finger 235 on latch 230 is positioned in the path of a pin 236 that extends outwardly from crosshead block 222 to release the latch member 230 when the crosshead 185 moves in its upstroke, i.e., from the position of FIG. 5 to the position of FIG. 4. As the sealer crosshead 185 completes its return movement from the position of FIG. 5 to the position of FIG. 4,

ejector arms

211 and 212 are pivoted in a clockwise direction about pivot 213 by the spring means, not shown, to move the ejector member 219 downwardly to eject a seal from the magazine 210, and position the seal in the sealingjaws.

Clutch actuating means is associated with the seal ejecting mechanism 184 for controlling the movement of the feed wheel and tension wheel eccentrics, and to this end, a cam 240 (FIG. 6) is mounted by pivot 241 to the lower end of portion 216 of ejector arm 212. A clutch actuating pin 242 is slidably mounted in an opening 243 in the housing cross wall 187, and the forward end of pin 242 projects outwardly of opening 243 into a position to be engaged by the end of cam 240 as the

ejector arms

211 and 212 move from the position of FIG. 5 to the position of FIG. 4, i.e., from the full line to the broken line position of FIG. 6. The outwardly projecting end of pin 242 is rounded, so that as cam 240 engages the pin it will move pin 242 to the left and then assume the broken line position of FIG. 6, so that the pin 242 is free to move to the right once the sealer crosshead upstroke has been completed.

The clutch actuating means responsive to the depression of pin 242 will be best understood from FIG. 6. As is shown therein, a generally L-shaped lever 250 is pivotally mounted to the housing 30 at 251, and lever 250 includes a downwardly extending arm 252 that is pivotally connected at 253 to the rearward, or left hand end, of pin 242. Lever 250 includes a rearwardly extending, generally horizontally disposed arm 253 that is pivotally connected at 255 to the upper arm of a generally vertically disposed link 254. The left hand end of a generally horizontally disposed clutch latch member 256 is pivoted to housing 30 at 257, and the midportion of member 256 is pivotally connected at 258 to the lower end of link 254. A detent 259 is provided on the bottom of member 256 and normally holds the one revolution clutch against rotation in a counterclockwise direction. Spring mounts 260 and 261 are connected, respectively, to

pivots

253 and 258, and a spring 262 extends between

mounts

260 and 261 to bias the detent 259 on member 256 toward positive engagement with the corresponding abutment on one revolution clutch 140.

Thus, during return movement of the sealer crosshead 185, when pin 242 is depressed, lever 250 is pivoted in a clockwise direction about pivot 251 to pivot member 256 in a counterclockwise direction about pivot 257 and free detent 259 from the one revolution clutch 140. After the cam 240 sweeps past pin 242, spring 262 forces pin 242 to the position of FIG. 6, and returns the detent 259 to a position against the one revolution clutch 140 to stop the clutch after one revolution is completed. As has been previously described, as the one revolution clutch 140 completes a single revolution, the tension wheel eccentric 91 and feed wheel eccentric 116 are rotated 180 by the chain drive means 60 defined by chains 142 and 144. As will be more fully understood from the ensuing description of the operation of the machine, this latter rotation of the tension and feed eccentrics brings the feed wheel 40 into active feeding engagement with the strap. Thus, as long as cam 240 is in the position illustrated in FIG. 6, the machine will continuously sequentially operate to feed strap around packages when the sealer crosshead 185 completes its return movement to pivot

ejector arms

211 and 212.

A rotary solenoid 270 (FIGS. 6-8) is utilized to release latch member 256 and initiate a strap tensioning function. An arm 271 extends laterally outwardly from the shaft 272 of the rotary solenoid 270, and a detent 273 projects outwardly from the end of arm 271. Solenoid 270 is connected in a suitable electrical circuit, and when the solenoid is energized, as for example by the depression of a push button, shaft 272 rotates in a clockwise direction, as viewed in FIG. 8, so that detent 273 lifts the latch member 256 against the bias of spring 262 to free the detent 259 from the one revolution clutch 140. A spring 274a is connected between a pin 274 and arm 271, to assist in returning the arm 271 to the position illustrated in FIG. 8. Detent pin 273 is spring loaded, so as to be capable of axial movement relative to arm 271 upon return movement to the position of FIG. 8.

Disabling means is provided for preventing the automatic actuating ofthe feed wheel and tension wheel eccentrics at the end of the sealer crosshead upstroke, and to this end, an eccentric pin 275 (FIGS. 68) is engageable with a side of the cam 240 to pivot the cam 240 relative to the ejector arm portion 216 to a position where the end of the cam 240 does not engage pin 242 as the

ejector arms

211 and 212 move to the broken line position of FIG. 6. A manually accessible actuating knob 276 is provided outwardly of housing 30, and the shaft 277 of knob 276 is offset with respect to the axis of pin 275, so that movement of the cam 240 will be accomplished by rotating the knob 276. It will be appreciated that if the cam 240 has been disabled by pin 275, it will be necessary to energize solenoid 270 to initiate a strap feed cycle.

When a strap feed cycle is completed, either after manual initiation by energizing solenoid 270 or by automatic operation in depressing pin 242. the end of the strap will be arrested by structure best seen in FIGS. 11 and 12. In FIG. 11, the end of the strap E is shown prior to its entrance into the arresting mechanism and it will be understood that the strap is being fed at a constant speed by the continuously rotating feed wheel 40. The strap arresting mechanism includes a strap sensing finger 280 that is mounted for movement about a pivot pin 281 on support structure 282. A lever 283 is fixed to pivot pin 281 and bears against the upper surface ofa latch release lever 284 (FIGS. 13 and 14) that is mounted at 285 for pivotal movement relative to the housing 30. Thus, when the end E of the strap moves from the position of FIG. 11 to the position of FIG. 12. the strap sensing finger 280 is pivoted in a clockwise direction about pivot 280 to move the lever 283 downwardly as can be seen in FIG. 12. Referring to FIG. 13, the downward movement of lever 283 pivots the latch release lever 284 in a clockwise direction about pivot 285, to move the upper end of lever 284 generally to the right. This latter movement releases latch 288 for allowing a gripper crosshead 289 to move to the right from the position of FIG. 13 to the position of FIG. 14.

As can be best seen in FIG. 17, the gripper crosshead 289 is mounted for sliding movement on guide plate 180, and crosshead 289 is moved to the right as viewed in FIG. 17 by a spring 290 that is connected between the frame of pin 320 that extends vertically through the left hand end of the crosshead. Thus, as latch 288 is released, spring moves crosshead 289 to actuate the gathering jaws 183. An abutment pin 291 extends upwardly from gripper crosshead 289 and moves out of engagement with the end of a pivotally mounted lever 292 to allow the gripping jaw means to be actuated. The midportion of the lever 292 is pivotally mounted on guide plate 180 at 293, and a spring 294 is connected to the end of lever 292 remote from pin 291 to bias the lever in a clockwise direction about pivot 293.

As can be best seen in FIG. 16, gripper crosshead latch 288 is pivotally mounted at 296 to the housing 30, and with reference to FIG. 14, it will be noted that the latch 288 has an enlarged hook-like end 299. A latch pin 297 extends transversely outwardly from both sides of the rearward end of gripper crosshead 289, and the hooked end 299 of latch 288 normally embraces the pin 297 to retain the crosshead 289 against movement by spring 294. An abutment 298 (FIG. 14) extends downwardly from latch 288, and is engaged by the latch release lever 284. Thus, when finger 280 is pivoted by the end of the strap entering the strap arresting mechanism, latch release lever 284 is pivoted in a clockwise direction and latch 288 in a counterclockwise direction about pivot 296 to free the hook-like end 299 of the latch from the latch pin 297 on the gripper crosshead.

As the gripper crosshead 289 moves to the right from the position of FIG. 13 to the position of FIG. 14, the gripper jaw means 181 is actuated by structure best illustrated in FIGS. 16 and 17. With reference to FIG. 17, it will be noted that a connecting link 302 is connected at one end by pivot 303 to a lateral extension 304 of lever 292. The opposite end of link 302 is pivotally mounted to a vertical drive pin 305 on a slide 306. As lever 292 is pivoted in a clockwise direction about pivot 293 by spring 294, slide 306 is moved to the left by link 302, with pin 305 sliding in a slot 307.

The gripper jaw means 181 includes a pair of laterally opposed jaw members 308 and 309 (FIG. 16) pivotally mounted at 310 and 311, respectively, to a mounting plate 312 spaced vertically above guide plate 180. A pair of

actuating links

313 and 314 are pivotally connected at one end at 315 and 316 to gripperjaws 308 and 309, respectively, with the opposite ends of

links

313 and 314 being pivotally connected to a vertical pin 317 extending upwardly from slide 306. Thus, as slide 306 is moved to the left by link 302, gripper jaw 308 is pivoted in a clockwise direction about pivot 310 by link 313, while gripper jaw 309 is pivoted in a counterclockwise direction about pivot 311 by link 314 to bring the hook-

like ends

318 and 319 of the gripping jaws into positive engagement with the strap.

As the leading end E of the strap enters the strap arresting mechanism to pivot the strap sensing linger 180, a time delay means is provided by the gripper jaw actuating mechanism which will allow the strap end to move to the position of FIG. 12 before the strap is positively stopped by the holding pawl 160. The amount of strap travel past the sensing finger 280 is accurately controllable, in that the strap is fed at a constant speed by the feed wheel 40, while the movement of the pin on the gripper jaw crosshead 289 allows the strap holding pawl 160 to move into engagement with the strap after a fixed increment oftime has expired.

After the strap has been arrested and gripped, the toggle linkage means 42 and 43 are thrown over center and a tension cycle is initiated by actuation of the rotary solenoid 270. When the final tension is drawn by tension wheel 41, the toggle linkage means 42 and 43 again break over center and the sealer crosshead 185 begins its downstroke movement. Reference can be made to the above-mentioned Crosby et al. patent for details of the seal crimping and notching structure actuated by the sealer crosshead 185.

Means is provided for returning the gripper crosshead 289 in response to upstroke movement of the sealer crosshead 185 after the strap sealing operation is completed, and as can be best seen in FIG. 16, a pulling latch 321 is pivotally connected at 322 to the sealer crosshead block 222. Latch 321 includes an enlarged hook-like forward end 323 for pulling the gripping crosshead 289 rearwardly or to the left as viewed in FIGS. 13- 15, upon upstroke movement of the sealer crosshead 185. The rear surface 324 of latch 321 is slightly inclined so as to hold the hook-like end portion 323 of the latch above pin 297. so that the gripper crosshead 289 is free to move once latch 288 is released. A stop 325 (FIG. 18) extends laterally outwardly from the lower end of the sealer crosshead block 222 and is engageable with an abutment surface 326 on the bottom of latch 321 to support the latch 321 in the position of FIG. during the downstroke of the sealer crosshead. The front surface of the hook-like portion 323 of latch 321 is inclined, so that the latch 321 will pivot in a counterclockwise direction about pivot 322 as the leading end of the latch 321 engages the pin 297 on the gripper crosshead during downstroke movement of the sealer crosshead. After the strap sealing and cut-off functions have been accomplished, and sealer crosshead 185 begins its upstroke movement, the hook-like end 323 of the latch 321 will engage the pin 297 (as can be seen in FIG. 15) to move the gripper crosshead 289 to the left and open the gathering jaws 183 and the gripperjaws 308 and 309.

When the strap package P is removed from the strapping station 34, strap sensing finger 280 pivots from the position of FIG. 12 to the position of FIG. 11, so that latch release lever 284 pivots from the position of FIG. 14 to the position of FIG. 13. A stop pin 331 (FIGS. 14 and 18) extends outwardly from the side wall of housing 30, and engages the lower portion of latch 288 after the roller 286 on lever 284 moves out of engagement with latch 288. The leading end of the hook portion 289 oflatch 288 includes an inclined cam surface 332, so that as the pin 297 on the gripper crosshead moves to the position of FIG. 13, the latch 288 will be pivoted in a counterclockwise direction about pivot 296 to allow the pin 297 to pass under the latch 288.

SUMMARY OF OPERATION Assuming that the strap has been fed around the package P at the strapping station 34, and that the tab end of the strap is held between gripper jaws 308 and 309, the toggle linkage means 42 and 43 will be disposed in the tensioning position illustrated in FIGS. 1 and 19. When solenoid 270 (FIGS. 68) is energized by actuating a suitable electric circuit, not shown, shaft 272 is rotated in a clockwise direction as viewed in FIG. 8 and detent 273 pivots latch member 256 in a counterclockwise direction about pivot 257 to move the detent surface 259 on the latch member out ofengagement with the stop surface on the one revolution clutch 140. Once the one revolution clutch 140 is unlatched, chains 142 and 144 rotate the tension eccentric 91 and the feed eccentric 116 through 180 to move the tension wheel 41 inwardly into active strap engaging position and to move the feed wheel 40 outwardly to inactive position. When the continuously rotating tension wheel 41 draws the predetermined tension in the strap, as determined by the setting of spring means 80, the

toggle linkages

42 and 43 are broken over center to the position of FIG. by the reaction force of the strap against the tension wheel 41. Since feed wheel 40 has been previously rotated to the inactive position, it does not engage the strap as the toggle linkage 42 moves over center. The tension which is drawn in the strap is retained by the holding pawl 160 (FIG. 1) which is free to rotate in a counterclockwise direction as tension is being drawn, but which is incapable of rotation in a clockwise direction, so that the strap tension will not be released. I

As the toggle linkage means 42 and 43 move from the position of FIGS. 1 and 19 to the position of FIG. 20. link 200 (FIGS. 9 and 10) is moved generally downwardly, and the abutment surface 203 on link 200 bears against the pin 202 on latch arm 197 to pivot the latch arm in a clockwise direction about pivot 195. The clockwise pivotal movement of latch arm 197 frees the detent 196 from engagement with the clutch 70, so that the clutch is free to rotate crankshaft 68 via the engagement of gears 66 and 67. Because of the size relationship between gears 66 and 67, link 200 is not freed from latching engagement with arm 197 by pin 206 until well after the clutch 70 has completed a revolution. In this manner, the complete 360 rotation ofthe crankshaft 68 is insured.

As the crankshaft 68 begins to rotate, the sealing cycle is initiated by movement of the sealer crosshead 185 from left to right, as viewed in FIG. 1. During the initial movement of the sealer crosshead, the

seal ejector arms

211 and 212 are pivoted from the seal dispensing position of FIG. 4 to the seal ejecting position of FIG. 5 by the engagement of cam 221 on the crosshead block 222 with the cam follower rollers 220 on the

seal ejector arms

211 and 212. The seal ejector arms are retained in the seal ejecting position of FIG. 5 during the sealing cycle by the spring urged latch member 233. As the sealer crosshead 185 completes its downstroke movement from left to right, the seal is notched and the strap is sheared from the strap feed supply by conventional structure, not shown, such as that disclosed in the above-mentioned Crosby et al. patent.

As the sealer crosshead 185 completes its upstroke movement from right to left towards the rest or dwell position adjacent housing wall portion 187, the sealing jaws are open and retracted. Toward the latter part of the sealer crosshead stroke, latch 321 moves into engagement with the transverse pin 297 on the gripper crosshead 289 and the gripper crosshead is returned to the rest position adjacent wall 187 by the latch 321. This latter movement also re-engages the holding latch 288 with the pin 297, as the latch 321 pivots to the position of FIG. 13. Thus, the gripping jaw means 181 and gathering jaw means 183 are latched open releasing the completed strap. The return movement of the gripper crosshead 289 also moves the pin 175 into engagement with the lever 169 (FIG. 13) to move the holding pawl 160 away from the back-up wheel 32 to prepare the apparatus for a subsequent feed cycle.

As the sealer crosshead 185 reaches the station adjacent wall 187, the seal ejector latch 233 (FIGS. 4 and 5) is released by pin 236 and the seal ejector 219 strips a seal from the stack in magazine 210 and inserts it in the open sealing jaws. As the

seal ejector arms

211 and 212 move to the position of FIG. 4, the cam 240 (FIG. 6) on seal ejector arm 212 depresses pin 242 to pivot the clutch release arm 256 in a counterclockwise direction about pivot 257 through lever 250 and link 254.

The pivotal movement of latch arm 256 moves the detent 259 thereon out of engagement with the abutment on clutch so that the tension eccentric 91 and feed eccentric 116 are rotated through 180 by chains 142 and 144. This latter movement advances the feed wheel 40 to active strap engaging position, while the tension wheel 41 is retracted to inactive position. The engagement of the continuously rotating feed wheel 40 with the strap pulls strap from the strap supply along the strap path through guide chute 31, past guides 162 and 163, around the back-up wheel 32, through the strap chute (not shown) and around the package P at the sealing station 34.

When the leading end E of the strap enters the strapping head, strap sensing finger 280 (FIGS. 11 and 12) is pivoted in a clockwise direction and lever 284 (FIGS. 13 and 14) is also pivoted in a clockwise direction by the engagement of arm 283. The movement of lever 284 releases the gripper crosshead latch 288 allowing the spring 290 (FIG. 17) to move the gripper crosshead 289 from left to right and close the gathering jaws 183. The gripping jaws 318 and 319 (FIG. 16) are subsequently closed by the action of spring 194. The movement of the gripper crosshead 289 also moves pin 175 away from lever 169, so that the holding pawl is moved into positive retentive engagement with the strap by spring biased lever 169 and link 167. The arresting of the strap by pawl 160 causes the

toggle linkages

42 and 43 to break over center from the position of FIG. 21 to the position of FIG. 22, removing both the feed wheel 40 and the tension wheel 41 from engagement with the strap.

It will be appreciated that as soon as a further package P is positioned at the sealing station 34, a further sealing cycle can be initiated by energizing solenoid 270 to repeat the above described sequence.

From the foregoing description and from a comparison of FIGS. 1922, it will be understood that while the

toggle linkages

42 and 43 are movable only between two positions, the feed wheel 40 and tension wheel 41 each occupy four positions, in the illustrated embodiment of the invention, by virtue of the above described

eccentrics

116 and 91, which respectively move the feed wheel 40 and the tension wheel 41 between two positions in the operative and the inoperative positions. In the following claims, the tensioning position (FIGS. 19 and 22) of the toggle linkages will be referred to as a position wherein the tension wheel 41 is operative and the feed wheel 40 is inoperative. In a like manner, the feeding position (FIGS. 20 and 21) of the toggle linkages will be referred to as a position wherein the feed wheel is operative and the tension wheel is inoperative. The claims also define the positions wherein the feed wheel 40 engages the strap while in the operative position (FIG. 21) and wherein the tension wheel 41 engages the strap while in the operative position (FIG. 19) as active positions. The positions wherein the feed wheel 40 (FIG. 20) and tension wheel 41 (FIG. 22) are spaced from the strap while in the operative positions are defined in the claims as inactive positions. This language has been chosen so that claims referring only to operative and inoperative positions could be construed broadly to cover a two position arrangement, as well as the four position arrangement disclosed herein. Thus, claims referring to operative and inoperative" positions, but not to active" and inactive positions, could be construed to cover an arrangement Where the feed and tension wheels are automatically brought into engagement with the strap upon movement between the operative and inoperative positions, as well as to cover an arrangement wherein an additional movement must be imparted to the feed and tension wheels after they are in the operative position to bring the wheel in the operative position into engagement with the strap.

lclaim:

l. Strapping apparatus comprising: means defining a strap path; means for feeding strap in a first direction along said path toward a sealing station for forming a loop about an object at said sealing station; means for drawing tension in said strap by moving said strap along said path in a direction opposite to said first direction; toggle means supporting said feeding means and said tensioning means for movement between an operative position on one side ofa center line and an inoperative position on the opposite side of the center line; means responsive to completion of a loop for actuating said toggle means to shift said feeding means from operative to inoperative position and to shift said tensioning means from inoperative to operative position; and means responsive to the drawing ofa predetermined tension in said strap for actuating said toggle means to shift said feeding means from inoperative to operative position and to shift said tensioning means from operative to inoperative position.

2. Strap feeding apparatus as set forth in claim I wherein means are provided for moving said feeding means and said tensioning means between an active strap engaging position and an inactive position spaced from the strap.

3. Strap feeding apparatus as set forth in claim 2 wherein the means for moving the feeding means and tensioning means between said active and inactive positions include eccentric means engageable with said toggle linkage means for shifting said toggle linkage means toward and away from said strap.

4. Strap feeding apparatus as set forth in claim 2 including adjustable means for urging said feeding means and said tensioning means against said strap with a predetermined force.

5. Strap feeding apparatus as set forth in claim 4 wherein said toggle means includes a first toggle linkage supporting said feeding means and a second toggle linkage supporting said tensioning means, said toggle linkages being coupled together for simultaneous movement.

6. Strap feeding apparatus as set forth in claim including a pair of pivotally mounted levers, said first and second toggle linkages including a pair of pivotally connected links, one link of each toggle linkage being pivotally connected to one of said levers, and wherein said adjustable urging means includes spring means bearing against each of said levers.

7. Strap feeding apparatus as set forth in claim 6 wherein the means for moving the feeding means and the tensioning means between said active and inactive positions includes first and second shafts, each having an eccentric portion engageable with one of said levers for moving said first and second toggle linkages.

8. Strap feeding apparatus as set forth in claim 7 including means coupling said first and second shafts for rotation together, the eccentric portions of said shafts being l out of phase with one another, whereby said feeding means is in active position when said tensioning means is in inactive position and said feeding means is in inactive position when said tensioning means is in active position.

9. Strap feeding apparatus as set forth in claim 8 including manually selectable means for actuating said shaft coupling means after strap feeding is completed to move said tension means to active position.

10. Strap feeding apparatus as set forth in claim 8 including means for automatically actuating said shaft coupling means at the end ofa sealing cycle to move said feeding means to active position.

11. Strap feeding apparatus as set forth in claim 10 wherein said means for automatically actuating said shaft coupling means includes a continuously rotating shaft, clutch means for transmitting rotary motion of said continuously moving shaft to said coupling means, latch means releasably retaining said clutch means against rotation, and means responsive to the completion of a sealing cycle for releasing said latch means to permit said clutch to rotate.

l2. Strap feeding apparatus as set forth in claim 11 including manually selectable disabling means for preventing said latch releasing means for releasing said latch means at completion of a sealing cycle.

13. Strap feeding apparatus as set forth in claim 11 including manually selectable means for actuating said shaft coupling means after strap feeding is completed to move said tension means to active position.

14. Strap feeding apparatus as set forth in claim 13 wherein said manually selectable means includes solenoid means for releasing said latch means.

15. Strap feeding apparatus as set forth in claim 10 including a seal ejector mechanism movable from a seal ejecting to a seal dispensing position at the completion of a sealing cycle, said latch releasing means being operatively responsive to movement of said ejector mechanism from seal ejecting to seal dispensing position.

16. Strap feeding apparatus as set forth in claim 1 wherein said first mentioned means for actuating said toggle means includes means at said sealing station for sensing a strap end when a strap loop is completed, linkage means movable in response to the sensing of said strap end by said sensing means, and strap stopping means movable for an inactive position spaced from said strap path to an active strap engaging and stopping position responsive to movement of said linkage means, whereby the reaction force of said feeding means against said strap causes said toggle means to move said feeding means from operative to inoperative position and said tension means from inoperative to operative position.

17. Strap feeding apparatus as set forth in claim 16 including means at said sealing station for gripping overlapping strap portions after strap feeding has been completed, said gripping means being engaged in response to movement of said linkage means, and means responsive to the disengagement of said gripping means for moving said strap stopping means from active to inactive position.

18. Strap feeding apparatus as set forth in claim 1 including a reciprocal sealing head movable between a rest position and a sealing position, crank means for reciprocating said sealing head, and means responsive to the last named toggle actuating means for actuating said crank means.

19. Strap feeding apparatus as set forth in claim 18 wherein said means for actuating said crank means includes a continuously rotating member, clutch means for transmitting rotary motion of said continuously rotating member to said crank means, latch means releasably retaining said clutch means against rotation, and means movable by said toggle means after said predetermined tension has been drawn for releasing said latch means.

20. A package strapping method comprising: continuously rotating a strap feeding means on a first toggle linkage, continuously rotating a strap tensioning means on a second toggle linkage, moving said feeding means into engagement with the strap to feed the strap in a first direction along a strap path around an object at a strapping station, moving said first and second toggle linkages over center when said strap feeding step is completed to move said feeding means out of engagement with said strap, gripping said strap, moving said tensioning means into engagement with said strap to move said strap along said strap path in a direction opposite to said first direction to draw a predetermined tension in said strap, and moving said first and second toggle linkages over center when said tension drawing step is completed to move said tensioning means out ofengagement with said strap.

21. A package strapping method as set forth in claim including the further steps of initiating a sealing cycle after said tension drawing step is completed, and moving said feeding means into engagement with the strap at the completion of said sealing cycle.

22. A package strapping method as set forth in claim 21 including the further step of moving a seal ejector mechanism from a seal dispensing position to a seal ejecting position and back to a seal dispensing position during a sealing cycle, and wherein the feeding means moving step of claim 21 is performed in response to movement of said seal ejector mechanism back to seal dispensing position. 23. A package strapping method as set forth in claim 20 wherein the first mentioned toggle linkage moving step is performed by holding said strap against movement in a strap feeding direction in response to completion of a strap loop around said object and positively confining said strap between the feeding means and the holding means, whereby the reaction force of said strap will move said toggle linkages over center.

24. A package strapping method as set forth in claim 23 wherein said strap holding step and said strap gripping step are performed in response to completion of a strap loop about said object.

25. A package strapping method as set forth in claim 20 wherein the second mentioned toggle linkage moving step is performed automatically in response to the drawing of said predetermined tension in said strap.