US 3396889 A
Description (OCR text may contain errors)
Aug. 13, 1968 J. R. ANNIS, JR 3,396,889
REVERSIBLE FEED WHEEL MECHANISM FOR POWER STRAPPING MACHINES v Filed May 23, 1966 2 Sheets-Sheet 1 INVENTOR= 7-, K M JAMES R. A/VN/S',JR. I00 A :0
By dwand. am
REVERSIBLE FEED WHEEL MECHANISM FOR POWER STRAPPING MACH INES Filed May 23, 1966 Aug. 13, 1968 J. R. ANNIS, JR
2 Sheets-Sheet 2 m m mm mm w mm By: 5M (R United States Patent 3 396,889 REVERSIBLE FEED WHEEL MECHANISM FOR POWER STRAPPING MACHINES James R. Annis, Jr., Northbrook, Ill., assignor to Signode Corporation, Chicago, 11]., a corporation of Delaware Filed May 23, 1966, Ser. No. 551,975 9 Claims. (Cl. 226143) The improved reversible feed wheel mechanism comprising the present invention has been designed primarily for use in connection with stationary power strapping machines of the fully automatic type wherein plastic or steel strapping is fed or payed out in one direction through a chute which encircles the package or bundle undergoing strapping and then, after the strapping has been caused to completely encircle the package, its direction of feed is reversed to tension the strapping about the package. The invention is however not limited to such use and feed wheel mechanisms embodying the principles of the invention may, if desired, with or without modification as required, be employed in connection with any power strapping machine, whether fully automatic or semiautomatic, where the requirements are that a feed wheel, at the commencement of the machine cycle, impel the strapping in one direction for strap-feeding purposes and then, at a subsequent point in the machine cycle, reverse its direction of rotation to tension the previously fed strapping. Irrespective however of the particular use to which the invention may be put, the essential features thereof remain substantially the same.
It has long been the practice, in connection with strapping tools, both portable and stationary alike, to support the strap-tensioning feed or traction wheel at the distal end of a swinging support which is so pivoted to the tool framework that the feed wheel approaches the reaction anvil or back-up wheel at a relatively small approach angle, thus causing a binding or wedging action on the strapping which is a function of the cotangent of the angle involved. Thus, the greater the tension in the strapping, the greater will be the binding action on the strapping, this phenomenon being commonly referred to as a self-energizing action.
Where a feed wheel is obliged to impel the. strapping in a direction counter to the direction of tensioning for the purpose of feeding the strapping into a chute toward or around the work, for example into a chute which encircles the strapping area, reaction forces on the feed wheel are such that a rapid self-deenergization of the feed wheel takes place as the approach angle becomes greater and, as a result of the consequent loss of pressure upon the strapping, there is a tendency for slippage of the feed wheel upon the strapping with consequent abrasion of the latter due to a milling action so that the interstices between the driving teeth or protuberances on the feed wheel become filled with particles. Thereafter, where resistance to strapping feed is encountered in advance of the feed wheel, as for example where the strapping is being forced forwardly through a strap chute, the tractional efficiency of the feed wheel is impaired.
With the advent of relatively high speed strap feeding operations, amounting in some cases to as much as six feet per second, such abrasion of the strapping is augmented by the tendency of the shock load which is applied to the strapping when the slack in the strapping is initially taken up and the inertia load of the rotary strapping reel in the strapping dispenser is encountered. At this moment, and until the dispenser gets up to normal feeding speed, deep mill cuts and other impressions are imparted to the strapping by the feed wheel, thereby weakening the strapping.
'These problems of strapping feed have long plagued 3,396,889 Patented Aug. 13, 1968 the designers of feed wheel mechanisms and various means have been devised in an etiort to minimize the amount of self-deenergization which takes place when a strap-tensioning feed wheel is rotated counter to the direction of strap tensioning for strap feeding purposes. The most obvious of these means has been to increase the spring pressure normally applied to the swinging feed wheel support, but this has resulted in a more pronounced feed wheel marking upon the strapping and other damage to the strapping finish, as well as causing increased strapping curl and feed wheel camber due to offset lateral support for the feed wheel shaft. Such considerations are particularly pronounced where plastic or other nonmetallic strapping is concerned.
The present invention is designed to overcome the above-noted limitations that are attendant upon the construction and operation of reversible feed wheel mechanisms which operate upon the strapping in one direction for strapping feed purposes and in the other direction for strap tensioning purposes and, toward this end, the invention contemplates the provision of a novel feed wheel mechanism in which a self-energizing action takes place in both directions of rotation of the feed wheel.
The provision of such a feed wheel mechanism constitutes the principal object of the invention and in the accompanying two sheets of drawings forming a part of this specification, several embodiments of the invention by means of which such dual feed wheel energization may be accomplished have been illustrated. Other ancillary objects and advantages of the invention, will readily suggest themselves as the nature of the invention is better understood.
In these drawings:
FIG. 1 is a sectional view taken substantially vertical- 1y, centrally and longitudinally through a reversible feed wheel mechanism embodying the principles of the present invention the mechanism embodying a novel feed wheel anvil and gripper member and being shown as operatively associated with the related parts of a power strapping machine;
FIG. 2 is a sectional view taken substantially on the line 2-2 of FIG. 1 in the direction of the arrows;
FIG. 3 is a sectional view taken substantially on the line 3-3 of FIG. 1 in the direction of the arrows;
FIG. 4 is a side elevational view, partly in section and entirely schematic in its representation, illustrating the mode of operation of the structure shown in FIG. 1;
FIG. 5 is a schematic view, similar to FIG. 4 illustrating the structure and mode of operation of a modified form of reversible feed wheel mechanism embodying the present invention;
FIG. 6 is a schematic view similar to FIGS. 4 and 5 showing another modified form of feed wheel mechanism embodying the present invention; and
FIG. 7 is a schematic view similar to FIGS. 4, 5 and 6, showing the anvil member of FIG. 4 devoid of its gripper function.
Referring now to the drawings in detail and in particular to FIGS. 1 to 3 inclusive, one form of reversible feed wheel mechanism incorporating the principles of the present invention has been designated in its entirety at 10 and it is shown for exemplary purposes as being embodied in a fully automatic power strapping machine of the type which operates to feed a length of strapping material in one direction about a bundle so that its free end is positioned in overlapping relationship with respect to the standing portion thereof which leads to a source of strapping such as a coil of strapping, after which the free end of the strapping is fixedly clamped and the direction of movement of the strapping is reversed to tension the strapping and shrink the same on the bundle. When the required degree of tension has been attained, the machine operates to position and crimp'a seal about the overlapping portion of the strapping or otherwise unite these overlapping portions and, finally. it operates to sever the standing portion of the strapping to free the strapped bundle.
The feed wheel mechanism is, with suitable modification as required, applicable to a wide variety of automatic power strapping machines but for exemplary, purposes it has been shown as being incorporated in a strapping machine of the general type, shown and described in United States patent to Crosby et al., No. 2,915,003,
granted on Dec. 1, 1959, and entitled Power Strapping Machine, only such parts of the machine as have ;a direct work and which is comprised of parallel longitudinally extending side walls 14 and 16 and a-rear wall 18, the front end of the housing being open. The machine is so designed that the area or region immediately below the housing 12 constitutes a strapping station ST where'an article such as the article shown at A is moved into position beneath the housing for strappingjpurposes. The
strapping station ST is defined by a strap guiding chute 20 which encircles the article A and provides a substan-' tially closed path for the strapping. Strapping S is drawn from a suitable strapping dispenser (not shownland is fed by the mechanism 10 through the housing 12 forwardly into the receivingend 22 of the chute 20, from whence it is projected in a closed path substantially completely around the article A so that it emerges from the discharge end 24 of the chute and then traverses a short distance beneath the housing 12 through a guide channel 26 until the leading end region 28 thereof overlaps and underlies the standing portion 30 of the strapping which exists at a sealing station SS. At this time, the mechanism 10 becomes effective to clamp the free end region of the strapping and reverse the direction of movement of the standing portion of the strapping through the housing 12 whereupon the article-encircling portion of the strapping S will be drawn in centripetal fashion from the chute 20 to shrink the same about the article, after which continued reverse movement of the strapping will tension the thus shrunk strapping. When the required or predetermined degree of tension has ben attained in the encircling loop of strapping, a previously applied seal 32 is crimped in position about the overlapping portions .of the strapping at the sealing station SS and the free end region of the strapping is severed from the encircling loop to release the entrapped article from the source of strapping, suitable crimping jaw instrumentalities 34 and shearing instrumentalities 36 being provided at the sealing station for this purpose.
The general arrangement of parts thus far described, with the exception of the specific construction of the feed wheel mechanism 10, is conventional since reversible feed wheel mechanisms are currently in use for initially feeding strapping material in one direction to force the same through an article-encircling chute and for thereafter feeding the strapping in the opposite direction to shrink and tension the strapping about an article. Thus, no claim is made herein to any novelty in connection with the strapping machine operations thus far described, the novelty of the present invention residing rather in the details of the feed wheel mechanism per se by means of which a firm gripping action is attained upon the strapping by the feed wheel proper which is associated with the mechanism, regardless of whether the strapping is undergoing forward strapping feed into the chute 20 or reverse strapping feed for strap tensioning purposes.
Considering nowthe feed wheel mechanism 10 in greater detail, this mechanism involvesin its general organization a toothed or serrated feed wheel proper which is carried at the lower end of a bifurcated link 52, the upper end of which is pivoted to a cross pin 54 which extends across the housing 12 between the two walls 14 and 16. The feed wheel 50 is secured to the drive shaft 55 of a reversible motor M and is straddled by the furcations of the link 52 as best seen in FIG. 2. The motor M is provided with a housing 56 having a hub portion 57 secured in an opening 58 formed in one of the furcations of the link 52, the hub portion passing through a clearance opening 60 formed in the side wall 16 of the housing12. The motor is thus supported by the link 52 near the distal or lower end thereof so that it moves bodily with the link throughout the limited swinging movements of the latter about the axis of the pivot pin 54. i
, The feed wheel 50 cooperates with a combined gripper and anvil member 62 in the form of a rocker element to feed the strapping S which is interposed between these two elements either in a forward direction to project the strapping into and through the chute 20 for article encircling purposes, or in a. reverse or rearward direction to shrink the strapping loop and tension the same about the article as previously described. This rocker element 62 is generally in the form of a pentahedron which is substantially of triangular configuration in longitudinal elevation as shown in FIG. 1. Stated otherwise the rocker element 62 is wedge-shape in its design. The element 62 is possesssed of three functional sides including a base side 64, a. rear side 66 which extends at a right angle to the baseside, and a working side 68 which constitutes the hypotenuse ofthe triangle. The rocker element 62 is pivoted for limited swinging movement about a horizontal axis by means of a pin 70 which projects between the side wallsj14 and 16 and serves to pivotally support the rocker element in the vicinity of the juncture between the sides 64 and 66 for free swinging movement in either direction.
The working side 68 of the rocker element 62 is formed with a shallow 'semicylindrical depression or well 72 therein having a radius of curvature which is preferably slightly greater than the radius of the feed wheel 50 and into which depression the periphery of the feed Wheel projects. When the feed wheel is centered within the depressi0n'72 as shown in FIG. 1, i.e., when the axis of the link 52 is such that it intersects the transverse axisof the pivot pin 70, the periphery of the feed Wheel lies close to the bottom of the depression 72 but is separated therefrom by'a distance slightly less than the thickness of the strapping S. Such a position has been illustrated in FIG. 1 but it is an unnatural one and represents a mid-position of the link 52 and feed wheel 50 and only occurs during the machine cycle when the direction of rotation of the feed wheel is undergoing reversal. In the normal position of the parts, as well as during strap tensioning operations, the feed wheel effectively bears against the forward region 72a of the depression, either under the influence of gravitational forces acting on the motor M, or a self-energizing action in one direction as will be described presently, or both. During strap feeding operations into the chute 20, the feed Wheel effectively bears against the rear regions 72b of the depression due to a similar self-energizing action in the opposite direction.
The strapping is initially passed through the housing by projecting the free end thereof forwardly through an opening provided in the rear Wall 12 and across the upper surface of the side 68 and from thence into the receiving end 22 of the chute 20, the strapping being guided by the feed wheel 50 which at the time is caused to rotate in a clockwise direction, so that it follows the contour of the depression 72. The strapping after being initially thus introduced through the housing, remains in the housing until the supply of strapping leading from the dispenser is exhausted. In order to guide the strapping through the housing and prevent it from clinging to the feed wheel 50, a pair of substantially identical guide blocks 82 are nested within channel-like depressions. 84 (FIG. 3) which are established by reason of pairs of upstanding flanges 86 on the upper side 68 of the rocker element 62 and are secured in position between the respective pairs of flanges by anchoring pins 88. The underneath faces of the blocks 82 are spaced slightly above the upper side 68 to afford a clearance for the strapping.
The width of the blocks 82 is substantially equal to the width of the strapping S and the width of the feed wheel 50 is less than the width of the strapping. A pair of spaced apart flanges 90 on each of the guide blocks 82 straddle the peripheral region of the feed wheel but lie within the marginal confines of the strapping so that these latter flanges act as stripper elements to constrain the strapping to follow the contour of the upper working surface 68 of the rocker element 62 rather than cling to the feed wheel and thus cause jamming of the mechanism.
The previously mentioned crimping jaw instrumentalities 34 and shearing instrumentalities 36 at the sealing station SS my be of any conventional construction but, for examplary purposes herein they are illustrated as being of the type shown and described in United States patent to Meier, No. 3,150,694, granted on Sept. 29, 1964, and entitled Strapping Tool. Reference may be had to such patent for a full understanding of these instrumentalities 34 and 36 but, for descriptive purposes herein it is deemed sufficient to state that the crimping jaw instru-mentalities include a pair of cooperating crimping jaws 92 which operate at an appropriate point in the machine cycle to loosely maintain a seal such as the seal 32 around the overlapping portions 28 and 30 of the strapping S and hold the same thus loosely positioned during the strap tensioning operation and then, after such tensioning operation has been completed, to crimp the seal. The shearing instr-umentalities 36 include a depressible plunger 94 which, upon depression thereof, engages the seal 32 and forces the same downwardly so as to shear the standing portion of the strapping against a fixed shear block 96.
As previously stated, when the free end region of the strapping S emerges from the discharge end 24 of the chute 20 it traverses the guide channel 26 and is thereby conducted to the shearing station SS where it assumes its underlying position with respect to the standing portion 30. This guide channel 26 is established by means of a swinging gate member 100 which is pivoted by a pin 102 to one side of the rocker element 62 and has a foot portion 104 which normally underlies the latter element. The gate member 100 is biased to its normal position by a torsion spring 106 surrounding the pivot pin 102. During the shrinking of the loop of strapping S about the article undergoing strapping, this gate member 100 is deflected by the inward centripetal movement of the strapping so that the gate member offers no resistance to removal of the strapped article from the strapping zone.
An anvil foot 110 also normally underlies the forward end region of the rocker element 62 'and constitutes a part of a second swinging gate member 112 of C-shape design. The gate member 112 is pivoted by a pin 114 (FIG. 2) to an overhead support 115 constituting a part of the machine framework and which is disposed well above the level of the link 52. The anvil foot 110 may be formed with serrations on its upper side thus establishing a movable gripper jaw 116 which is designed for cooperation with similar serrations which establish a fixed gripper jaw 118 on the underneath side of the extreme forward region of the rocker element 62 in clamping the strapping therebetween immediately prior to the strap tensioning operation. The gate member 112 is capable of being laterally displaced as shown in dotted lines in FIG. 2 after the strap severing operation so as to release the tensioned loop of strapping which surrounds the article and thus release the article so that it may be withdrawn from the strapping zone.
The operation of the feed wheel mechanism may readily be described by reference to the schematic illustration of FIG. 4 wherein the principal components thereof have been, to a large extent isolated from the immediate strapping machine environment and wherein the guide' blocks 82 have been removed in the interests of clarity. Reference to FIG. 4 will reveal the fact that during that portion of the machine cycle when the strapping S is undergoing feeding in a forward direction, i.e., to the left as seen in this view, the feed wheel will rotate in a clockwise direction to thus impel the strapping which overlies the depression 72. Since the combined effective length of the swinging link 52 and the diameter of its supported feed wheel is such that in the mid-position of the link 52 the strapping will be lightly confined between the feed wheel 50 and the bottom of the depression 72, the tendency for the feed wheel during such clockwise rotation will be to tractionally engage the strapping and, by a locomotive action, travel generally rearwardly so as to cause the link 52 to swing in a counterclockwise direction. The pressureexerted upon the portion 72b of the depression 72 will cause the rocker element 62 to swing in a clockwise direction, thus elevating the serrated gripper jaw 116 from the fixed gripper jaw 118 to allow the forward end region of the strapping to pass between these two jaws after the strapping has traversed the arcuate extent of the chute 20 and passed forwardly through the guide channel 26. At the same time the upper edge. region of the rear side 66 of the rocker element 62 will engage the wall 18 of the housing 12 to limit the extent of clockwise swinging movement of the rocker element 62 and, thereafter, a wedging action of the link 52 and feed wheel 50 will take place wherein the link 52 is placed under relatively high compression between the fixed pivot pin 54 and the portion 72b of the depression 72, this wedging action being commonly referred to in the art of feed wheel suspension devices as a self-energizing action. In the present instance, the magnitude of the self-energizing action is a function of the cotangent of the angle involved between the axis of the link 52 and a plane which is tangent to the increment of linear contact between the feed wheel 50 and surface portion 72b at any given instant during the strap feeding operation.
During such portion of the machine cycle when the feed wheel is rotating in a counterclockwise direction so as to initially pull the strapping in centripetal fashion from the chute 20 and shrink the loop about the article A, and to thereafter tension the strapping about the article as previously described, a similar self-energizing action of the feed wheel and its supporting link will take place by reason of the locomotive action of the feed wheel on the strapping S tending to rock the supporting link 52 in a clockwise direction. The pressure of the feed wheel upon the surface portion 72a of the depression 72 will rock the gripper element 62 in a counterclockwise direction, thus forcing the movable gripper jaw 116 into effective clamping cooperation with the fixed gripper jaw 118 to clamp the free end portion of the strapping therebetween.
From the above description it will be apparent that the present feed wheel mechanism 10 is effective to establish a self-energizing operation of the feed wheel against the strapping S during impelling of the latter in either direction. The energizing angles involved during rotation of the feed wheel in either direction may be regulated to accommodate the desired degree of pressure upon the strapping by proper selection of the pivotal axis of the pin to vary the normal clearances between the rocker element 62 and the two abutment surfaces which limit the swinging movements of this element. In the illustrated form of the invention, during feeding of the strapping S in a direction to project the same forwardly into the entrance end 22 of the chute 20, the energizing angle involved need not be steep since the frictional resistance offered to the strapping passing through the chute is not great, even when a full complement of strapping is disposed within the chute near the end of the strap feeding portion of the machine cycle. During initial strap feeding operations and before all of the slack existing in the portion of the strapping leading from the feed wheel mechanism to the rotary reel type dispenser has been taken up, relatively light pressure upon the strapping by the feed wheel will suffice to impel the strap forwardly. At such time as this slack has been fully taken up and the shock load incident to the inertia of the strapping reel is encountered, the consequent drag upon the power driven feed wheel will increase the energizing angle and maintain such an increase until such time as the strapping reel gathers full dispensing speed of rotation. Thereafter the frictional drag upon the feed wheel will decrease and normal feeding operations under light strapping pressure will obtain. In this manner long stretches of feed wheel impression or other markings on the surface of the strapping will the avoided.
During reverse rotation of the feed wheel 50 for strap tensioning purposes, adequate pressure upon the strapping will at all times be effective to perform the tensioning operation. As the tension in the strapping increases progressively, the binding action of the feed wheel on the strapping will increase commensurately because of the increase in the steepness of the energizing angle. The resultant increase of pressure on the strapping will be translated to the movable gripper jaw 116 through the rocker element 62 so that there will be no danger of slippage of the free end region of the strapping from between these jaws.
In FIG. a modified form of reversible feed wheel mechanism has been illustrated schematically and designated in its entirety at 210. In this form of the invention, the same general principle of dual-energization of the feed wheel 250 and its supporting links 252a and 252b obtains as in the case of the feed wheel 50 and its single supporting link 52. Due to the similarity of parts involved, and in order to avoid needless repetition of description, similar characters of reference but of a higher order have been applied to the corresponding parts as between the disclosures of FIGS. 4 and 5.
In the feed wheel mechanism 210, the motor shaft 256 which supports the feed wheel 250 is suspended from the lower ends of the two supporting links 252a and 252b. These links are of equal length and they in turn, are loosely and pivotally supported adjacent their upper ends on fixed pins 254 which are spaced from each other and lie in the same horizontal plane. The spacing of the pins 254 and the length of the links 252a and 25212 are such that the links are disposed substantially at a right angle to each other with the inclination thereof being on the order of 45. The pivotal support for the links 252a and 252b is established by means of longitudinally extending slots 253 through which the pins 254 extend.
The feed wheel 250 cooperates with a fixed back-up anvil block 310 against which it effectively bears to impel the strapping S either in a forward direction or in a reverse direction, depending upon the direction in which the feed wheel supporting motor shaft 256 is rotated. It will be understood that the gravitational force .of the motor M2 as applied to the feed wheel through the shaft 256 may be relied upon to establish the necessary initial pressure be tween the feed wheel and the strapping S for strap-impelling purposes. However, if desired, each of the links 252:: and 252b may be yieldingly biased in opposite directions respectively by springs 257 to attain this initial feed wheel pressure on the strapping. This spring biasing of the links 252a and 252b may be employed in an installation where the overlapping portions of the strapping extend vertically along a vertical side of the article undergoing strapping so that the gravitational force of the motor is not available for pressure application.
It is to be noted that when the feed wheel is rotating in a clockwise strapfeeding direction, self-energization of the feed wheel against the strapping will take place by reason of the tendency for the link 2521; to swing in a counterclockwise direction and thus cause the lower end region of the associated slot 253 to engage the adjacent pin 254 and place the link 2521) under compression. At the same time the link 252a will follow the locomotive or tractional movement of the feed wheel 250 and the link 252a will ride free on the associated pin 254. Conversely, when the feed wheel is rotating in a counterclockwise strap tensioning direction, self-energization of the feed wheel on the strapping will take place by reason of the tendency for the link 252a to swing in a clockwise direction and effect engagernent of the lower end region of the associated slot with the adjacent pin 254 and thus place the link 252a under compression in a manner similar to that previously described in connection with the link 252b during strap feeding operations.
In FIG. 6 a further modified form of reversible feed wheel mechanism has been schematically illustrated and designated at 410. Again, due to the similarity of the mechanism 410 with the mechanisms 10 and 210', and in order to avoid needless repetition of description, similar reference characters of a still higher order have been applied to the corresponding parts as between the structures of FIGS. 5 and 6.
In the form of the invention shown in FIG. 6, the two links 252a and 252b have been replaced by a single generally triangular supporting plate 452 which, in effect, constitutes a supporting link for the feed wheel 450. The feed wheel supporting motor shaft 456 is pivotally supported near the lower corner of the triangular plate 452 while the plate itself is fioatingly supported on pins 454 which project through arcuate slots 453 adjacent the two upper corners of the triangle. The feed wheel 450 cooperates with a freely rotatable back-up wheel 510 for strap gripping purposes. The effect is similar to that which would be attained if the two links 252a and 252b were to be fixedly secured to each other so as to constitute in effect a bell crank arrangement. Self-energization of the feed wheel 450 against the back-up wheel 510 is attained regardless of the direction of rotation of the feed wheel inasmuch as the shortest distance between the axis of the feed wheel drive shaft 456 and the axis of either of the two pivot pins 454, as well as the radius of the feed wheel 450, are such that at no time may the feed wheel swing free of the backup wheel 510, regardless of the direction of tilting movement of the triangular supporting link or plate 452. If desired, the plate' 452 may be biased by a single compression spring 457 similar in function to the springs 257 associated with the links 252a and 252b of FIG. 5.
In the form of feed wheel mechanism 610 shown in FIG. 7, the feed wheel mounting including the feed wheel 650, its supporting link 652, and the pivot pin 654 for the link, remains substantially the same as the feed wheel mounting of the feed wheel mechanism 10 of FIG. 4. The anvil member 610 is similar in its construction to the anvil member or rocker element 62 but, instead of being movable, it is fixed relative to the strapping machine framework and thus is devoid of any associated gripper means for the free end region .of the strapping S. Utilizing similar reference numerals of a still higher order to designate the corresponding parts as between the disclosures of FIGS. 4 and 7, the anvil member 610 is formed with a semi-cylindrical depression 672 having reaction surfaces 672a and 672b which cooperate with the strapping S and feed wheel 650 during strap feeding and strap tensioning operations respectively in precisely the same manner as described in connection with the feed wheel mechanism 10.
It will be understood that in the forms of the invention shown in FIGS. 4, 5, 6 and 7, the various pivot pins 54, 254, 454 and 654 constitute fixed elements on the strapping machine framework and that the feed wheel reaction members, i.e., the rocker element 62, the anvil blocks 510, 610 and the back-up wheel 510 have fixed supports therefor on the framework, although the members may, if desired, be capable of displacement for strap clearance purposes after the strapping operation has been completed as is the case in connection with the anvil member or foot 210 of FIGS. 1 and 3. Unlike the movable reaction rocker element of FIG. 4, these latter reaction elements are devoid of any gripper function, it being understood that separate gripper means for the strapping will be provided in the vicinity of the strapping station.
The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit of the invention. Therefore, only insofar as the invention has particularly been pointed out in the accompanying claims is the same to be limited.
Having thus described the invention, what I claim and desire to secure by Letters Patent is:
1. In a strapping machine having a framework, a reversible feed wheel mechanism for feeding a length of strapping in one direction for article-encircling purposes and in a reverse direction for strap-tensioning purposes, said mechanism comprising: a reaction member supported by the framework, a rotatable feed wheel designed for cooperation with said reaction member for tractionally feeding strapping thereacross in opposite direction, and a suspension linkage movably supporting said feed wheel on the framework and including a link portion which is effective under compression and through the strapping to cause progressive binding of the feed wheel against the reaction member under the influence of the locomotive action of the feed wheel on the strapping during rotation of the feed wheel in either direction, and means for selectively rotating the feed wheel in opposite directions.
2. In a strapping machine, a reversible feed wheel mechanism as set forth in claim 1, wherein the link portion which is effective under compression during rotation of the feed wheel in one direction, and the link portion which is effective under compression during rotation of the feed wheel in the other direction, are embodied in a single link the upper end of which is pivoted to the framework and the lower end of which rotatably supports the feed wheel.
3. In a strapping machine, a reversible feed wheel mechanism as set forth in claim 1, wherein said link portion of the suspension linkage has its proximate end pivoted to the framework, said feed wheel being pivotally mounted on the distal end of said link portion.
4. In a strapping machine, a reversible feed wheel mechanism as set forth in claim 1, wherein the link portion which is effective under compression and through the strapping during rotation of the feed wheel in one direction has its proximate end loosely pivoted to the framework, and wherein the link portion which is effective under compression and through the strapping during rotation of the feed wheel in the other direction likewise has its proximate end loosely pivoted to the framework, the regions of pivotal connection for said link portions being spaced from each other.
5. In a strapping machine, a reversible feed wheel mechanism as set forth in claim 4, wherein said link portions are embodied in a common rigid link member.
6. In a strapping machine having a framework, a reversible feed wheel mechanism for feeding a length of strapping in one direction for article-encircling .purposes and in a reverse direction for strap-tensioning purposes, said mechanism comprising: a feed wheel supporting link having its proximate end pivoted to the framework for swinging movement of the link in opposite directions, a strap-impelling feed wheel rotatably mounted on the distal end of said link, reaction means supported by the framework and between which means and the feed wheel the strapping passes during impelling thereof in either direction, said reaction means presenting a pair of reaction surfaces against which the feed wheel is adapted to effectively bear through the strapping and which are so disposed with respect to the arcuate path of swinging movement of the feed wheel that the locomotive action of the feed wheel on the strapping urges the feed wheel bodily toward one of said surfaces to increase the pressure of the feed wheel on the strapping when the feed wheel is rotated in one direction, and urges the feed wheel bodily toward the other surface to increase the pressure of the feed wheel on the strapping when the feed wheel is rotated in the other direction, and means for selectively rotating said feed wheel in opposite directions.
7. In a strapping machine, a reversible feed wheel mechanism as set forth in claim 6, wherein said reaction means comprises a reaction block having a shallow depression therein into which the peripheral region of the feed wheel projects, the opposite side surfaces of said depression establishing said pair of reaction surfaces.
8. In a strapping machine, a reversible feed wheel mechanism as set forth in claim 7, wherein said depression is of arcuate configuration and on a radius of curvature greater than the combined effective radial extent of the link and its supported feed wheel.
9. In a. strapping machine, a reversible feed wheel mechanism as set forth in claim 7, wherein said reaction block is in the form of a rocker element pivoted to the framework for limited rocking movement in opposite directions and about an axis which is intersected by the longitudinal axis of the link when the feed wheel is in an intermediate position out of effective engagement with either reaction surface, and an abutment positioned in the path of rocking movement of the rocker element in each direction for limiting the extent of such rocking movement, one of said abutments, in combination with the adjacent opposing portion of the gripper element, constituting a gripper foot for the free end of the length of strapping.
References Cited UNITED STATES PATENTS 3,118,584 1/1964 Brouse 226143 ALLEN N. KNOWLES, Primary Examiner.
J. P. MULLINS, Assistant Examiner.