US2959118A

US2959118A - Box strapping machine

Info

Publication number: US2959118A
Application number: US577097A
Authority: US
Inventors: Robert E Hager
Original assignee: Acme Steel Co
Current assignee: Acme Steel Co
Priority date: 1956-04-09
Filing date: 1956-04-09
Publication date: 1960-11-08
Anticipated expiration: 1977-11-08

Description

' F dApri l 9,. 1956 v H R'. E. HA'GER Nov. 8, 1960' i I BOX sTRAPPINc MACHINE 5 Sheets-Sheet 1 IN VEN TOR.

BY I

BObZTiE Nov. 8, 1960 R. E. HAGYER 2,959,118 BOX STRAPPING MACHINE Filed April 9, 1956 5 Sheets-Sheet 2 IN V EN TOR.

Nov. 8, 1960 R. E. HAGER 18 BOX STRAPPING MACHINE Filed April 9, 1956 5 Sheets-Sheet 3 INVE OR- Nov. 8, 1960 7 E. HAGER BOX,ST.RAFPING MACHINE q Filed April 9, 1956 v 5 SheetS-SheetEA" IN V EN TOR.

Nov. 8, 1960 R. E. HAGER 2,959,118

BOX STRAPPING MACHINE Filed April 9. 1956 v s Sheets-Sheet s 102 J00 J03 J T l .12.

15 2 LQQ J95 10 Q Q m v v on IN VEN TOR.

22 /24 W F *M cgg nite BOX STRAPPING MACHINE Filed Apr. 9, 1956, Ser. No. 577,097

12 Claims. (Cl. 100-26) This invention relates to box strapping machines and its purpose is to provide an improved machine for applying a flexible binder, such as a flat metal strap, about a box or package, drawing the strap taut, cutting it off from the source of supply and then uniting its overlapping ends. Machines of this type are described and claimed in the copending application of Alvin L. Winkler Robert E. Hager, and Kjell A. Falck-Pedersen, Serial No. 284,634, filed April 26, 1952, now Patent No. 2,882,814 issued April 21, 1959; in the copending application of Alvin L. Winkler and James N. Wognum, Serial No. 356,056, filed May 19, 1953, now Patent No. 2,846,218 issued August 5, 1958, and in the copending application of Marchand B. Hall and Alvin L. Winkler, Serial No. 517,768, filed June 24, 1955, now Patent No. 2,853,938 issued September 30, 1958.

The principal object of the invention is to provide a box strapping machine with an adjustable size strap guide adapted to minimize the strap feed and the strap take-up time when strapping various sizes of packages or other objects. Another object of this invention is to provide a box strapping machine having an adjustable size strap guide and an adjustable length strap feed having adjusting means for providing a strap feed length corresponding to a particular strap guide size when the size of the strap guide is adjusted to accommodate a different size package or object to be strapped. A further object of the'invention is to provide a box strapping machine having an adjustable strap guide for directing the strap around the object to be bound, in combination with automatic strap feeding means regulated by an electric control circuit whereby a predetermined length of strapping is fed during each operation. Other objects relate to various features of construction and arrangement which will appear more fully hereinafter.

The nature of the invention will be understood from the following specification taken with the accompanying drawings in which one embodiment is illustrated. In the drawings,

Figure 1 shows a front elevation of the upper portion of the improved box strapping machine, illustrating a part of the strap feeding mechanism and the adjustable guiding means for directing the strap around the box or package;

Fig. 2 shows a top plan view of a portion of the box strapping machine shown in Fig. 1;

Fig. 3 shows a perspective view of a box which has been bound by a metal strap having its overlapping ends secured together by welding or other means;

Fig. 4 shows an enlarged view of a welded joint of strap ends which may be the joint shown in Fig. 3;

Fig. 5 is a somewhat diagrammatic side elevation of the apparatus shown in Fig. 1, illustrating the relative positions of the parts when a predetermined length of strap has been fed completely around the guide which extends around the position occupied by the box or package to be bound;

Fig. 6 is a view similar to that of Fig. 5 showing the Patent 0 ice 2 relative positions of the parts at a later stage when the strap has been drawn taut around the box and it is about to be severed from the supply portion;

Fig. 7 is a view similar to those of Figs. 5 and 6, show ing the relative positions of the parts at a still later stage when the strap has been cut and a joint has been formed;

Fig. 11 shows a sectional view taken on the line 11-11.

of Fig. 10; and

Fig. 12 is a circuit diagram showing somewhat diagrammatically the electrical system by which the box strapping machine shown in Figs. 1 to 11, inclusive, is operated.

As illustrated in the drawings, the invention is embodied in a box strapping machine comprising a table top 15 which is carried by a cabinet adapted to rest upon the floor and to contain most of the movable part of the operating mechanism by which the strap is drawn taut.

around the box, package or other object to be bound. The table top 15 is provided with a central opening 15a in which are mounted certain parts 16 on which the object 17 to be bound is adapted to rest. The table top 15 has secured to the upper side thereof a stationary strap guide 18 which is secured to the table by studs 19 and it also has slidably mounted thereon a movable strap guide 20 which is adapted to move endwise at the tab-1e with respect to the stationary guide 18 so that boxes or packages of different sizes may be accommodated in the opening between them. The strap guide 18 comprises a bar 18ahaving secured to the opposite sides thereof fiat metal plates 18b which are shaped so that they project inwardly from the end portion of the bar 18 and terminate in vertical edges 18c adapted to be located in proximity to the vertical edges of the object being bound. The top edges of the plates 18b project downwardly below the inner face of the bar 18a as shown at 18d and these parts 18d are extended horizontally toward the left, as shown in Figs. 1 and 2, terminating in proximity to the upright standards or pedestals 21 which are secured by brackets 22 and studs 23 to a base plate 24 which may be the floor upon which the machine rests. The guide flanges 18d are bent outwardly at their ends, as shown at 18a, and these flanges are secured to the standards 21 by studs 25.

The movable guide 20 comprises a curved bar 20a located in a vertical plane and having secured to the opposite edges thereof two guide plates 20]), the body portions of which extend inwardly to a substantial distance beyond the bar, terminating in the vertical edges 200 which are parallel to the edges of the stationary guide. The side plates 20b have upwardly and inwardly directed parts 20d which terminate in proximity to the flanges 18d of the plates 1812. There is thus formed a guide for the metal strap which has a generally elliptical shape so that the strap being fed thereto passes around the inner faces of the

bar

18a and 20a and between the side plates 18b and 20b until it has extended completely around the box or package 17. The lower extremity of the bar 18 extends below the side plates 1812 as shown at 18a, so that the strap is properly guided to the strap gripping devices and other mechanism hereinafter described which are located below the top surface of the table 15. Similarly, the lower end of the bar 2011 terminates below the level of the table 15 as shown at 20e, so that it receives and guide the metal strap as this strap is fed thereto,

The movable guide 20 has secured to the middle POI:

tion thereof a bracket 26 in which there is secured a piston rod 27 which threadedly engages the bracket and which is held in position by a locknut 28. The piston rod 27 extends into a cylinder 29 which is secured to a plate 30 spaced from the standards 21 by a block 31. The plate 30 and the block 31 are secured to the standards 21 by studs 32. A piston connected to the piston rod 27 is actuated by compressed air or other fluid which is admitted to the opposite ends of the cylinder 29 through

pipes

33 and 34 connected in the operating system hereinafter described.

Referring to Figs. 1, 5, 6 and 7 of the drawings, the metal strap 35 is shown as being drawn from a source of supply (not shown) by a feed wheel 36 which is mounted on a shaft 37 and rotates in the direction of the arrow 38. The strap 35 is held in engagement with the feed wheel 36 by an idler 39 mounted on a shaft 40. These parts are located beneath the top of the table 15, and, after passing from the feed Wheel 36, the strap 35 passes through a slot 41a formed in a movable gripping dog 41 which is pivoted at 42 on the frame and which is provided on its upper side with a serrated gripping surface 41b adapted to engage the free end 35a of the strap after it has been passed around the box or package and beneath a stationary gripping plate 44.

After passing through the slot 4112, the strap 35 passes through a guide channel 45a formed in a guide member 45 which is adapted to be moved horizontally to and from the operating position illustrated in Fig. 5. After passing through the guideway 45a, the strap 35 passes beneath a second stationary gripping plate 46 and above a second movable gripping dog 47 which is pivoted at 48 on the frame. This gripping dog has a serrated upper surface 47b adapted to engage the under side of the strap to cause it to be gripped against the stationary gripping plate 46 at the proper time in the cycle of operations. During the initial feeding movement of the strap 35, the

members

46 and 47 are separated, as shown in Fig. 5, and the strap is then forced into the guide 26 where it rides around on the inner surface of the bar a between the side plates 2012. It then passes into engagement with the upper part of the guide 18 between the portions 18d of the side plates 18a and is thence directed downwardly around the curved portion of the bar 18a until it passes from the part 18:: and above the movable gripping member 41 into engagement with a socket 45b formed in the guide 45. After the strap has been fed to place the end thereof in engagement with the end of the socket whereby to provide the proper length of strapping to be fed (the mechanism to control the strap feed being explained more fully hereafter) and when that condition is reached, the end portion 35a of the strap is gripped by the gripping member 41 and the gripping plate 44 so that the end of the strap is then held in a stationary position with the extremity thereof in the socket 4515.

When the above condition has been reached, the direction of rotation of the feed wheel 36 is reversed so that the loop of the strap extending around the box 17 is contracted as the strap is withdrawn by the feed wheel until a condition is reached where the strap is in close engagement with the box 17, as shown in Fig. 6. If further tightening of the strap around the box or package is desired, the strap may then be automatically gripped by the gripping dogs 49 and 50 which are located below the feed wheel 36 and which are adapted to be moved into engagement with the strap whereupon they are moved downwardly by means not shown in order to draw the strap taut. Below the gripping dogs 49 and 50, the strap 35 may pass around a roller 52 as it comes from the source of supply.

After the strap 35 has been drawn taut around the box or package 17, as shown in Fig. 6, the movable gripping dog 47 is moved upwardly to hold the supply portion of the strap against the stationary gripping plate 46. The supply portion of the strap is then cut off by shearing blades 53 which are located above and below the strap at a point beneath the stationary gripping plate 44. These shearing blades are then automatically actuated by means not shown to cut off the strap and create a condition which is shown diagrammatically in Fig. 7 Where the end portions of the strap are held against the gripping

plates

44 and 46 and the extreme end portions overlap each other beneath the welding points 55 and 56 which are mounted on

stationary members

57 and 58, respectively, carried by the frame. The overlapping ends of the metal strap are then pressed against the welding points by a movable welding head 60 which is carried by a plunger 61 and which is adapted to be moved vertically by means not shown from the position shown by the dotted lines in Fig. 7 to a position where it presses the overlapping strap ends against the welding points 55 and 56. The passage of an electric current through the overlapping strap ends at points opposite the welding points results in the formation of spot welds 62 in the overlapping portions of the strap 35, as shown in Fig. 4. The predetermined length of the strap 35 is then securely bound around the box or package f7, as shown in Fig. 3. When the joint has been formed, the movable

gripping dogs

41 and 47 are retracted and the box or package 17 may then be moved on the table to remove the strap 35 from engagement with the welding points 55 and 56 and with the stationary

gripping plates

44 and 46.

The actuation of the gripping

dogs

41 and 47 may be effected in various ways but it is illustrated as being brought about by means of suitable lever connections located beneath the level of the table and on opposite sides of the frame member 63 in which the plunger 61 is slidab-ly mounted. A lever 64 is pivoted at 65 on the frame and has a resilient connection through a link 66 with the underside of the gripping dog 41. Similarly, a bell crank lever 67 is pivoted at 68 on the frame and has a resilient connection 68 with the underside of the gripping dog 47. A pair of coil springs 69 and 7d are adapted normally to move the gripping

dogs

41 and 47, respectively, to their gripping positions.

A form of mechanism for actuating the shaft 37 to rotate the feed wheel 36, in order to cause equal increments of the strap to be fed on each operation, is shown particularly in Figs. 8, 9, l0 and 11, where the drive shaft 37 is illustrated as being connected by a gear 71 to a pinion 72 mounted upon the shaft 73 of a rotary switch 74, which features in themselves do not constitute a part of the present invention. At the end of a feeding operation brought about by the rotation of the feed wheel 36, the free end of the strap is gripped by the

gripping devices

41 and 44 and the feed shaft 37 is then reversed to draw the strap taut. This feed shaft has mounted thereon a sprocket pinion 75 connected by an endless sprocket chain 76 to a sprocket gear 77 mounted on a timer shaft 78. This timer shaft 78 is journalled in two ball-bearing units 79 which are mounted in a bearing bracket 80 carried by a horizontal plate 80a which is secured by studs 81 to the horizontal frame member 82 which may form a part of the frame structure which supports the table 15.

At the end of the bearing sleeve 80 opposite to the sprocket gear 77, the shaft 78 is provided with an integrally formed radial flange 78a and, on the outer side of this flange, there is provided a cylindrical portion 78b which is formed integrally with the reduced extremity 780 of the shaft. A non-metallic clutch ring 83 fits over the part 7812 of the shaft and seats against the radial flange 78a. A latch cam 84 is rotatably mounted on the part 7811 of the shaft adjacent to the clutch ring 83 and a timing cam 85 fits over the extremity of the shaft portion 78b against the outer face of the latch cam 84. The two

cams

84 and 85 are secured against relative rotation by two studs 86 which engage arcuate slots 85a in the timing cam and which threadedly engage the circular aperture formed in the cam 84. By releasing the studs 86, a relative angular adjustment of the two cams may be made in order to regulate the timing operations hereinafter referred to.

The clutch ring 83 and the two

cams

84 and 85 are retained in position on the portion 78b of the shaft by a disk 88 which is centrally apertured to fit over the reduced extremity 78c of the shaft and which bears against the inner portion of the outer face of the cam 85. A pin 89 has a drive fit in an aperture formed in the enlarged portion 78b of the shaft and the extremity of this pin engages an aperture 88a in the disk 88 so that the disk revolves with the shaft but is capable of endwise movement thereon. This disk 88 is mounted in contact with the outer face of the cam 85 by means of a helical spring 90 which is mounted upon the portion 780 of the shaft between the disk 88 and a collar 91 mounted on the outer end of the shaft and secured in position by a pin 92 arranged to extend with a drive fit through a transverse aperture formed in the shaft. With the foregoing arrangement the clutch ring 83 and the

cams

84 and 85 are free to rotate on the portion 78b of the shaft, being restrained only by frictional contact with the radial flange 78a of the shaft and with the spring pressed disk 88.

An electric switch 95 is secured to one side of the bearing bracket 80 and has a reciprocating plunger 95a provided with a roller 95b arranged to contact with the peripheral surface of the cam 85. This surface includes an arcuate portion 85b of smaller radius which is connected by two inclined portions 850 and 85d with a portion 852 of larger radius. As the pinion 75 is rotated in the direction of the arrow 96, as shown in Fig. 8, the cam 85 rotates in the same direction and the roller 95b rides over the peripheral surfaces of the cam 85, thus controlling the operation of the switch 95 which is connected in the electric control circuit hereinafter described.

There is also mounted upon the bearing bracket 80 a stud 97 which extends laterally therefrom and has pivotally mounted on its outer end a latch or detent 98 adapted to engage a shoulder 84b formed on the latch cam 84. The outer surface 84a of this cam is of spiral formation and the extremities of this surface terminate at the radial shoulder 84b. The latch or detent 98 is pressed against the cam 84 by a coil spring 99 which is mounted upon the stud 97 with one extremity thereof engaging the bracket 80 and with the other extremity thereof engaging the latch 98, so that the latch is maintained in contact with the peripheral surface of the cam.

In the operation of the apparatus just described the cams and the parts which coact therewith are in the relative positions shown in Figs. 8 and 11 at the beginning of each cycle, with the latch 98 abutting against the shoulder 84b and with the roller 95b riding on the surface 85b of the cam 85 at a point adjacent to the incline 850, with the switch 95 in one of its two closed positions. When the feeding of the strap begins, in response to an operation hereinafter described, the shaft 78 and the

cams

84 and 85 rotate in counterclockwise directions. As the cam 85 rotates, the roller 95b rides on the surface 85b of lesser radius and then rides up the incline 85d, thereby depressing the plunger 95a and moving the switch 95 to the other of its two closed positions. This condition continues as the surface 85e of larger radius travels past the roller 95b and the feed wheel 36 is thereby rotated to feed the strap. The roller 95b then rides down the incline 850 to the position shown in Fig. 8, thereby stopping the feeding operation. At the same time, the latch 98 moves into a position in contact with or adjacent to the shoulder 84b. If there is a space between the shoulder 84b and the latch, due to the overrunning of the cam, this is corrected when the feed mechanism is reversed to draw the strap taut around the package, since the shaft 78 then rotates in the opposite direction and moves the shoulder 84b into contact with the latch 98.

During this reverse rotation, the latch 98 holds the

cams

84 and 85 stationary while the shaft 78, clutch ring 83 and disk 88 rotate with respect to these cams, as per- 6 mitted by the spring 90. This spring is of such strength that it permits this slipping action during the reverse feeding, although causing the

cams

84 and 85 to move with the shaft during the feeding operation. The parts remain in the relative position shown in Fig. 8 at the end of the reverse feeding operation so that they will be in readiness for the next feeding cycle.

Having described the mechanical feeding mechanism and the means for actuating the control switch 95, reference will now be made to Fig. 12 in which an electric circuit, including the switch 95, is diagrammatically illustrated. This circuit comprises a double pole master switch which connects the supply conductors 101, leading from an alternating current supply source, with the

line conductors

102 and 103 by which current is supplied to the operating parts of the electrical apparatus. Two conductors 104 and 105 lead from the

conductors

102 and 103, respectively, to the electronic timer 106. This timer includes a solenoid operated switch 106s, switch contacts 106a controlled by the triode vacuum tube 106t, a potentiometer 106p, a potentiometer 106y, and a switch 106w by which either potentiometer 106p or 106y may be connected in series with the condenser 1060 by shifting the movable blade of the switch.

The contacts 106a are connected in a line 107 leading from the line conductor 102 to one terminal of a strap feed relay 108 which has its other terminal connected by a conductor 109 to the other line conductor 103. The solenoid 108 has a plunger 108a which operates a contact member 108b adapted to connect the terminals of two spaced pairs of

contacts

110 and 111, thus forming a double pole double throw switch.

The

line conductors

102 and 103 lead to the input terminals of a current rectifier 113 from which direct current flows through the conductors 114 and 115. The conductor 114 leads to one contact of each pair of

contacts

110 and 111. The conductor 115 leads to the terminals of the feed drive brake 116 and the feed drive clutch 117 which include condensers 116a and 117a and solenoids 11Gb and 117b, respectively. The feed drive brake 116 is connected through a resistor 118 to one terminal 95c of the switch 95. The other terminal 95d of this switch is connected by a conductor 119 to a conductor 120 leading through a resistor 121 from the feed drive clutch 117 to the other contact terminal 110. The movable contact 95e of the switch 95 is connected through a line 122 and a switch 123 to the other contact 111.

The starting of each strapping cycle is controlled from the electronic timer through connections made by conductors 124 to the contacts of a master switch 125 operated by a rotary earn 127. This cam is mounted on a shaft driven intermittently from one of the power driven shafts of the strapping machine and makes one revolution for each strapping cycle. The contacts of this switch 125 are closed to initiate a cycle by the portions of the cam 127 of larger radius and when they are opened by the part of the cam of smaller radius, the condenser 1060 is recharged in preparation for the next cycle. The closing of the switch 125 is initiated manually by means (not shown) whereby the rotation of the cam 127 is controlled by the operator.

When the switch 125 is closed by the cam 127, the solenoid 106s of the electronic timer closes the contacts 106a and thereby energizes the solenoid 108 to close the contacts 110 and thereby close the circuit of the feed drive clutch 117, thereby causing the rotation of the feed wheel 36 and the feeding of the strap. After the cycle has been thus started, the timer cam 85 rotates and the roller 95b of the switch 95 moves onto the surface 85e I of the cam and the timing of the cycle is then taken over by the cam 85. The end of the cycle is reached when the roller 95b passes down the incline 850 to rest upon the surface 85b of the timer cam as this cam completes its revolution and is stopped by the latch 98 engaging the shoulder 84b of the cam 84. The potentiometers 106p 7 and 10632 of the timer 106 should be regulated so that the action of this timer terminates before the roller 95b rolls down the incline 850 of the cam 85, so that the end of the cycle will be determined by the switch rather than by the electronic timer.

The circuit shown in Fig. 12 also comprises means for controlling the admission of compressed air or the like to the cylinder 29 through the

conduits

33 and 34 to regulate the position of the movable strap guide 20 in accordance with the size of the box or package to be bound. For this purpose, the movable switch blade of the switch 106w is connected by a mechanical connection 129 to the movable switch blade of a switch 130 connected on one of two conductors 131 leading from a source of current supply to the solenoid 132a of a spring return solenoid operated valve 132 which controls the flow of compressed air to the

pipes

33 and 34 from a supply line 133 leading, from an air pump 134 driven by an electric motor 135. The air supply line. 133 has an accumulator 136 connected therein.

The switches 166w and 130 are operated by a single handle or button (not shown) which may be conveniently located at the front of the machine. The operation of these switches determines which potentiometer 106p or 1063 is active in the circuit whereby the length of strap fed during a cycle corresponds to the size of the strap guide as fixed by the position of the movable strap guide 20.. The positions of the

switch contacts

106w and 130, as. shown in Fig. 12, correspond to the smaller guide size and the lesser strap feed and when these positions are reversed a larger size guide is brought about accompanied by a greater strap feed.

It might appear that the electronic timer 1% alone could be used both to initiate and terminate the strap feed cycle, rather than to use it only to initiate the strap feed cycle. The reason that this is not true is that the electronic timer does not provide the degree of accuracy required for the precise strap feed length required. in this case, the electronic timer 106 is used to initiate the strap feed cycle and to keep the strap feeding until the roller 95b of the switch 95 rolls up the incline 85d of the cam 85 and changes the position of the switch contacts. This enables the cam 85 to take over control of strap feed after it is initiated by the timer and the timer need only be stopped after the cam 85 takes control and before its roller 95]) rolls down the cam incline 850 to terminate strap feed. It is apparent that if the electronic timer does not stop its timing before the roller 95b rolls down the cam incline 850, it retains control of the strap feed. This control can be carried over into a second or third or any other rotation cycle of the cam 85 in order to prolong the strap feed during multiple rotations of the cam 85. Consequently, the strap feed length obtained by using

therheostats

106p and 106 must necessarily correspond to different cycles of rotation of the cam 85. The adjustability of the potentiometers 166p and 1% is provided in order to assure that they stop the strap feed control of the electronic timer during that part of the rotation of the cam 85 when the roller 95b rides on the surface 85e of the cam 85.

By adjusting the speed of the cycles of the cam 85 by interchange of different sizes of sprockets 71 and 77, and by slight relocation of the timing cam 85 relative to the latch cam 84 as provided, an infinite range of strap feed lengths can be provided in order to have a strap feed length corresponding to any strap guide size used.

One form of the invention has been shown and described by way of illustration but it will be understood that it. may have various other embodiments which come within the scope of the appended claims.

I claim:

1. The combination in a box strapping machine, of an. adjustable strap guide extending entirely around the position occupied by the box, automatic means for feeding, a length, of strap. through said guide and entirely around the box with the free end of the strap in over-v lapping relation with another portion of the strap, means,

for varying the length of said guide, and means for automatically adjusting said automatic feeding means upon varying the length of said guide to cause saidfeeding means to feed a predetermined length of strap in ac-- cordance with the length of the strap guide;

2. The combination in a box strapping machine, of. an adjustable strap guide extending entirely around the position occupied by the box, automatic means for feeding a length of strap through said guide and entirely around the box with the free end of the strap in overlapping relation with another portion of the strap, a stop for engaging the end of said strap after it has passed through said guide and into said overlapping position, means for varying the length of said guide, and means for automatically adjusting said automatic feeding means upon varying the length of said guide to cause said automatic feeding means to feed a predetermined length of strap which engages said stop with change in length of said strap guide.

3. The combination in a box strapping machine, of an adjustable strap guide extending entirely around the position occupied by the box, automatic means for feeding a length of strap through said guide and entirely around the box with the free end of. the strap in overlapping relation with another portion of the strap, means for varying the length of said guide, means including an electronic device for starting the operation of said automatic feeding means, and means including control devices connected in a direct current circuit for changing the duration of the operation of said automatic feeding means upon varying of the length of said guide.

4. The combination in a box strapping machine, of an adjustable strap guide extending entirely around the position occupied by the box, automatic means for feeding a length of strap through said guide and entirely around the box with the free end ofthe strap in overlapping relation with another portion of the strap, fluid pressure operated means for varying the length of said strap guide, means including an electronic device for starting and stopping said automatic feeding means and actuating said fluid pressure operated means, said means including means for changing the duration of the operation of said automatic feeding means upon varying of the 'length'of said guide.

5. The combination in a box strapping machine, of an adjustable strap guide extending entirely around the position occupied by the box, automatic means for feeding a length of strap through said guide and entirely around the box with the free end of the strap in overlapping relation with another portion of the strap, manually controlled means for varying the length of said guide, and an electric circuit comprising means for. automatically changing the duration of the feed of said strap with the change in the length of said guide.

6. The combination in a box strapping machine, of a substantially elliptical strap guide extending entirely around the position occupied by the box, said guide comprising a stationary part and a horizontally movable part, the effective length of said guide aroundsaid position being adjustable to receive different sizes of boxes, means controlled by the operator for adjusting said horizontally movable part, automatic means for feeding a predetermined length of strap through said guide and entirely around the box with the free end of the strap in overlapping relation with another portion of the strap, and means for adjusting said automatic feeding means to change said length automatically when said horizontally movable part is adjusted.

7. The combination in a box strapping machine, of a strap guide extending entirely around the position occupied by the box, said strap guide having a first operative position extending entirely around said box posi tion and a second operative position extending entirely around said box position, automatic means for feeding a length of strap through said guide and entirely around the box with the free end of the strap in overlapping relation with another portion of the strap, first control means for said automatic feeding means to cause said automatic feeding means to feed a length of strap corresponding to said first guide position, second control means to control said automatic feed means to cause said automatic feed means to feed a length of strap corresponding to said second guide position, and third control means automatically operative in one position to place said guide means in said first position and simultaneously to render said first control means operative and automatically operative in another position to place said guide means in said second position and simultaneously to render said second control means operative.

8. The combination in a box strapping machine as set forth in claim 7, wherein the two operative strap guide positions are each adjustable and the first control means and the second control means are both adjustable to accommodate the adjustments in the strap guide positions.

9. The combination in a box strapping machine, of a strap guide extending entirely around the position occupied by the box, said strap guide having a first operative position extending entirely around said box position and a second operative position extending entirely around said box position, automatic means for feeding a length of strap through said guide and entirely around the box with the free end of the strap in overlapping relation with another portion of the strap, a timing device to start and to control said feeding means during the first portion of the operation thereof, cam operated switch means to control the operation of said feeding means during the final portion of the operation thereof to cause said feeding means to feed a predetermined length of strap, control means to move said strap guide between the first and second operative positions thereof and simultaneously to change the operation of said timing device to feed a different predetermined length of strap according to the position of said strap guide, and switch mechanism to change the control of said feed means from said timing device to said switch means just prior to termination of the operation of said strap feeding means, whereby accurately to control the length of strap fed through said guide in accordance with the adjusted position of Said guide.

10. The combination in a box strapping machine, of a strap guide txtending entirely around the position occupied by the box, said strap guide having a first opera- 10 tive position extending entirely around said box position and a second operative position extending entirely around said box position, automatic means for feeding a length of strap through said guide and entirely around the box with the free end of the strap in overlapping relation with another portion of the strap, a timing device to start and to control said feeding means during the first portion of the operation thereof and including first control means to cause said feeding means to feed a length of strap corresponding to said first guide position and second control means to cause said feeding means to feed a length of strap corresponding to said second guide position, cam operated switch means to control the operation of said feeding means during the final portion of the operation thereof to cause said feeding means to feed a predetermined length of strap, switch mechanism to change the control of said feed means from said timing device to said switch means just prior to termination of the operation of said strap feeding means, whereby accurately to control the length of strap fed through said guide in accordance with the adjusted position of said guide, and third control means operative in one position automatically to place said guide means in said first position and simultaneously to render said first control means operative and automatically operative in another position to place said guide means in said second position and simultaneously to render said second control means operative.

11. The combination in a box strapping machine as set forth in claim 10, wherein the two operative strap guide positions are each adjustable and the first control means and the second control means are both adjustable to accommodate the adjustments in the strap guide positions.

12. The combination in a box strapping machine as set forth in claim 10, wherein means is provided always to place the cam operated switch means in the proper position at the beginning of an operation of the feeding means to ensure that an accurate and predetermined length of strap is fed upon operation thereof in combination with the timing device.

References Cited in the file of this patent UNITED STATES PATENTS 1,462,960 Guenther July 24, 1923 2,195,043 Wright Mar. 26, 1940 2,420,498 Pojman May 13, 1947 2,597,675 Sackett May 20, 1952 2,632,381 Buckland Mar. 24, 1953 2,707,429 Leslie et al. May 3. 1955 2,732,792 White Jan. 31, 1956 2,831,422 Black et al. Apr. 22, 1958