US3586572A

US3586572A - Electrically controlled handtool for friction-fusing nonmetallic strap

Info

Publication number: US3586572A
Authority: US
Inventors: Arvid I Ericsson
Original assignee: Signode Corp
Current assignee: Signode Corp
Priority date: 1969-02-20
Filing date: 1969-02-20
Publication date: 1971-06-22
Anticipated expiration: 1988-06-22
Also published as: DE2065080B2; DE2065080C3; CH512357A; NL143464B; ES376917A1; GB1280271A; DE2002593B2; SE399398B; FR2031565A1; JPS4836680B1; DE2065080A1; SE365999B; CA941728A; DE2002593A1; BE744440A; NL7002349A; DE7001959U

Abstract

A COMPACT, PORTABLE TOOL FOR FRICTION-FUSING OVERLAPPING PORTIONS OF A TENSIONED ARTICLE BINDING LOOP, WHICH INCLUDES A ROTATABLY MOUNTED STRAP GRIPPING MEMBER FOR COMPRESSING INTERFACE REGIONS OF THE OVERLAPPING STRAP PORTIONS INTO FRICTIONAL ENGAGEMENT WITH ONE ANOTHER, WITH DRIVE MEANS BEING PROVIDED FOR FIRST INTERMITTENTLY ROTATING THE STRAP GRIPPING MEMBER IN A FIRST DIRECTION TO WITHDRAW ONE OF THE STRAP END PORTIONS TO CONSTRICT THE LOOP ABOUT THE ARTICLE, AND WITH THE DRIVE MEANS THEN BEING OPERATIVE TO OSCILLATE THE GRIPPING MEMBER TO CAUSE INTERFACE MELTING BETWEEN THE OVERLAPPING STRAP PORTIONS, WHEREBY THE MELTED SURFACE REGIONS MAY FUSE TO ACHIEVE INTERFACE SOLIDIFICATION. THE DRIVE MEANS INCLUDES AN ELECTRIC MOTOR HAVING A ROTARY OUTPUT SHAFT, WITH THE ROTARY MOTION OF THE SHAFT BEING CONVERTED INTO ROCKING MOVEMENT, AND WITH THE ROCKING MOVEMENT BEING CONVERTED INTO INTERMITTENT ROTARY MOVEMENT OF THE STRAP GRIPPING MEMBER. WHEN A PREDETERMINED AMOUNT OF TENSION IS DRAWN WITHIN THE STRAP LOOP, THE INTERMITTEN ROTARY MOION OF THE STRAP GRIPPING MEMBER IS CONVERTED TO OSCILLATING MOVEMENT TO EFFECT THE FRICTION-FUSION JOINDER OF THE OVERLAPPING STRAP PORTIONS.

Description

EE RICSSON June 22-, 1971 'j ELECTRICALLY CONTROLLED HANDTOOL FOR FRICTION-FUSING NONMETALLIC STRAP 7 Sheets-Sheet 1 Filed Feb. 20, 1969 A. I. ERICSSON 3,586,572 ELECTRICALLY CONTROLLED HANDTOOL FOR FRICTION-FUSING June 22, 1971 NONME'I'ALLIC STRAP 7 Sheets-Sheet Filed Feb. 1969 20 w m 58 V w ..m 2 ms n W cm 0 M. 29 L1: W m 6 w? 3 m 1 u a Q, j 6 0 L 8 5 EV 8 41M 6 m. J 3 w I m 2 i r 3 0 m r/ 2 0 04 A. I. ERICSSON NONMETALLIC STRAP v 7 Sheets-Sheet 4 June 22, 1971 ELECTRICALLY CONTROLLED HANDTOOL FOR FRICTION-FUSING Filed Feb. 20, 1969 J g Wu J g Q 4 2 Q a 2 6 r 7 3 2 June 22, 1971 A. l. ERICSSON 3,586,572

' ELECTRICALLY CONTROLLED HANDTOOL FOR FR1UTIONFUS1NG NO'NMETALLIG STRAP 7 Sheets-Sheet 7 Filed Feb. 20, 1969 United States Patent US. Cl. 156-359 30 Claims ABSTRACT OF THE DISCLOSURE A compact, portable tool for friction-fusing overlapping portions of a tensioned article binding loop, which includes a rotatably mounted strap gripping member for compressing interface regions of the overlapping strap portions into frictional engagement with one another, with drive means being provided for first intermittently rotating the strap gripping member in a first direction to withdraw one of the strap end portions to constrict the loop about the article, and with the drive means then being operative to oscillate the gripping member to cause interface melting between the overlapping strap portions, whereby the melted surface regions may fuse to achieve interface solidification. The drive means includes an electric motor having a rotary output shaft, with the rotary motion of the shaft being converted into rocking movement, and with the rocking movement being converted into intermittent rotary movement of the strap gripping member. When a predetermined amount of tension is drawn within the strap loop, the intermittent rotary moion of the strap gripping member is converted to oscillating movement to eflFect the friction-fusion joinder of the overlapping strap portions.

BACKGROUND OF THE INVENTION In the recent past, Signode Corporation, the assignee of the entire interest of the present application, has developed several processes and tools for joining the overlapping end portions of a tensioned thermoplastic loop by friction-fusion techniques, and these methods and apparatuses are typified by those disclosed and claimed in Stensaker et al. application Ser. No. 479,446, filed Aug. 13, 1965, and now Pat. No. 3,442,732, Vilcins ap plication Ser. No. 524,429, filed Feb. 2, 1966 and now Pat. No. 3,442,733, Ericsson application Ser. No. 524,431, filed Feb. 2, 1966 and now Pat. No. 3,442,734, Stensaker application Ser. No. 524,432, filed Feb. 2, 166 (Ser. No. 524,432 is a continuation-in-part of a Stensaker application Ser. No. 472,587, filed July 16, 1965) and now Pat. No. 3,442,735, and Kobiella application Ser. No. 629,799, filed Apr. 10, 1967 and now Pat. No. 3,442,203. One of the drawbacks of certain of the tools disclosed in some of the above applications, is that they are pneumatically operated, and oftentimes a suitable source of air is not present at a strapping location. Furthermore, while those working in this area have recognized the desirability of providing a tool which could be operated by a more commonly available power source, such as a conventionally available 110 volt source of electrical current, heretofore a suitable electrically operated friction-fusion tool has not been developed.

While the apparatus in the above-mentioned Kobiella application is of the completely automatic type, i.e., one which automatically feeds strap around a package from a strap supply source, grips the leading end of the strap, withdraws the trailing end of the strap to tension the strap loop, and friction-fuses overlapping portions of the loop, a majority of the tools disclosed in the above-mentioned applications are of the hand operated variety, wherein strap is manually fed around a package to bring overlap- 'ice ping strap portions into registry, whereupon the tool is actuated to tension the strap loop and effect the frictionfusion operation. Although the hand tools described above have functioned satisfactorily, and have met with wide commercial acceptance, it has been desired to provide a tool which is extremely light in weight and compact, so as to allow the user of the tool to easily manipulate the tool for long periods of time without tiring and to allow the user to transport the tool from place to place without difficulty.

Furthermore, in known types of friction-fusion strap sealing tools, the drive mechanisms for effecting compression of the overlapping strap portions, and movement of the strap portions relative to one another to cause the interface melting have been somewhat complicated and costly. In most friction-fusion strap sealing tools, separate means have been provided for compressing the overlapping strap portions, and for effecting either multidirectional or unidirectional movement of one of the overlapping strap portions relative to the other.

SUMMARY OF THE INVENTION The friction-fusion strap joining tool of the present invention is extremely light in weight and compact, so that the tool can be readily manipulated and used for extended periods of time without tiring the user. The tool is electrically operated, and includes a single operative member for compressing the overlapping strap portions, withdrawing one of the overlapping strap portions to constrict the loop about the article and to place the loop in tension, and for effecting interface melting at the interface regions of th overlapping strap portions by oscillating one of the overlapping strap portions.

The present invention provides a novel drive means for a strap gripping member of the type mentioned above, which includes an electric motor having eccentric means coupled to the output shaft thereof to oscillate a rocker arm member. The rocker arm is coupled to the shaft of the gripping member through a one way clutch, so that the gripping member is initially rotated in a first direction to draw a predetermined amount of tension in the strap loop. The one way clutch transmits intermittent rotary motion to the gripping member,'but the intermittent rotary motion is at such a fast rate as to appear continuous. When the preselected amount of tension is drawn in the loop, a ratchet and pawl mechanism is engaged to block rotation of the gripping member, so that the rocker arm oscillates the gripping member at a frequency and amplitude sufficient to cause interface melting between the frictionally engaged interface regions of the overlapping strap portions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top perspective view of a first embodiment of the sealing apparatus of the present invention, with the apparatus being illustrated in a tension drawing and sealing position upon an article;

FIG. 2 is an enlarged front elevational view of the apparatus illustrated in FIG. 1, with the strap gripping wheel and anvil of the tool being illustrated spaced from one another for placement of overlapping strap portions therebetween;

FIG. 3 is a top plan view of the tool illustrated in FIG. 2;

FIG. 4 is a fragmentary front elevational view, similar to FIG. 2, and showing the strap gripping wheel and anvil in strap compressing relationship;

FIG. 5 is a fragmentary detail view illustrating the cooperative action between the strap loop and tension sensing means;

FIG. 6 is a sectional view taken generally along line 66 of FIG. 3;

FIG. 7 is a sectional view similar to FIG. 6, but showing the position of the elements at the completion of a tensioning cycle;

FIG. 8 is a sectional view taken generally along hne 8-8 of FIG. 3;

FIG. 9 is an enlarged sectional view taken generally along line 9-9 of FIG. 8;

FIG. 10 is an enlarged sectional view taken generally along line 10--10 of FIG. 8;

FIG. 11 is an enlarged sectional view taken generally along line 11-11 of FIG. 8;

FIG. 12 is a sectional view taken generally along line 1212 of FIG. 10;

FIG. 13 is a sectional view similar to FIG. 11, and showing the position of the parts during tensioning movement of the gripping Wheel;

FIG. 14 is a sectional view similar to FIGS. 12 and 13, and showing the position of the parts during oscillation of the strap gripping member;

FIG. 15 is a fragmentary front elevational view of a second embodiment of the apparatus;

FIG. 16 is a sectional view illustrating the drive arrangement of the embodiment of 'FIG. 15; and

FIG. 17 is an enlarged sectional view taken generally along line 1717 of FIG. 15.

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

Referring now to the drawings in detail, the embodiment of FIGS. l-l4 is illustrated generally at 20 in the drawings, and apparatus 20 includes a frame in the form of a housing defined by

mating housing members

21 and 22 secured together by screws 23. A handle 24 is provided at the upper end of tool 20 and handle 24 is formed of inverted U-shaped handle portions 25 and 26 formed integrally with

housing members

21 and 22, respectively.

Housing members

21 and 22 are generally thin walled shell-like structures, which collectively define a hollow interior or chamber 27 therebetween.

The tool 20 is shown in position on a package P in FIG. 1, with the trailing end portion 28 of a loop L of thermoplastic strap overlapping a leading end portion 29 of the strap, and with the overlapping strap portions being positioned between a strap gripping wheel 30 and a strap supporting anvil 31. The trailing strap end portion 28 may extend to a suitable supply of strap, not shown. Drive means, to be hereafter described in detail, is provided within the chamber 27 of tool 20 for shifting anvil 31 upwardly into strap compressing relationship with respect to wheel 30, for intermittently rotating wheel 30 to withdraw the upper strap portion 28 to the left, as viewed in FIG. 1, to constrict the loop L about the article and place the loop in tension, and for oscillating wheel 30 relative to anvil 31 to produce bodily sliding frictional movement between the opposing surface regions of the overlapping

strap portions

28 and 29 to effect interface melting therebetween.

The drive means within chamber 27 includes an electric motor M (FIG. 8), and motor M includes a rotary output shaft 33, the left hand end of which is supported in a bearing 34 in the rear wall of the housing, and the forward end of which is supported in a bearing 35 that is provided in an intermediate housing wall 36. A sleeve 37 is mounted on the right hand end of shaft 33, preferably by a splined connection, and sleeve 37 is positioned within bearing 35 (FIG. 9), with sleeve 37 including a portion 38 of enlarged diameter that bears against the right hand side of bearing 35. A suitable bearing retainer, such as a C-ring 39, is provided in an annular groove in sleeve 37, and bears against the left hand side of bearing 35, as is viewed in FIG. 9. A pin 40 extends outwardly from sleeve 37 in eccentric relationship with respect to the motor shaft 33, as can be best seen in FIGS. 13 and 14. Pin 40 extends through a bore 41 in a block 42, and block 42 is mounted for sliding movement along a pin 43 that is disposed at right angles with respect to pin 40 (FIG. 12). To this end, block 42 is provided with a transverse opening 44 below bore 41, and a bushing 45 (FIG. 10) is preferably provided in opening 44 to support pin 43- Thus, when motor M is energized, eccentric pin 40 moves along a circular path concentrically with the axis of motor shaft 33, and block 42 is moved up and down, and from side to side along pin 43. As will hereinafter appear, because of the fixed location of the shaft of gripping wheel 30, block 42 also moves axially along eccentric pin 40. t

A rocket arm is driven by pin 43, and to this end, rocker arm 50 includes a pair of laterally spaced parallel arms 51 and 52 (FIG. 10) having aligned

openings

53 and 54, respectively, impaled by the ends of pin 43. Rocker arm 50 is mounted for rocking movement relative to the frame aboutan axis defined by the shaft 55 of gripping Wheel 30. As can be best seen in FIG. 10, the rearward end 56 of shaft 55 is rotatably supported in a boss 57 that extends outwardly from housing member 21. A retainer member 58 is fixed on the outer end of shaft portion 56 by a pin 59 to prevent the shaft 55 from moving forwardly of the frame. Movement of shaft 55 rearwardly of the frame is prevented by the enlarged gripping wheel 30, as will hereinafter appear. Thus, as block 42 and pin 43 are moved up and down by eccentric pin 40, rocker arm 50 oscillates about the axis of shaft 55, and the slidable engagement of block 42 on pin 40 allows the block 42 to shift axially during this movement.

Shaft 55 includes an enlarged hexagonally shaped portion 60 inwardly of shaft portion 56, and shaft portion 60 seats against a planar, forwardly facing surface 61 on rocker arm 50(FIG. 10). Rocker arm 50 includes a generally annularly shaped wall 62 that extends forwardly from surface 61, and rocker arm wall 62 cooperates with surface 61 and with the rearwardly facing surface of housing member 22 to collectively define a chamber 63 therebet-ween. A ratchet wheel 64 is provided within chamber 63 in face abutting engagement with surface 61, and ratchet wheel 64 is provided with a central hexagonally shaped opening 65 that is slidably positioned over shaft portion 60. The ratchet teeth 66 around the periphery of wheel 64 cooperate with a pawl mechanism (FIGS. 12- 14) to be hereafter described for converting intermittent rotary motion of shaft 55 to oscillating motion.

Shaft 55 further includes a portion 68 of enlarged diameter forwardly of shaft portion 60, and the transition between

shaft portions

60 and 68 defines a rearwardly facing shoulder that confines the ratchet wheel 64 against rocker arm surface 61. Shaft portion 68 is rotatably supported in housing member 22 by a suitable bearing 69 Within a pass through opening therein, and the strap gripping wheel 30 is provided at the outer end of shaft portion 68. Shaft portion 68 includes an axially extending bore 70 throughout substantially the entire length thereof, and strap gripping wheel 30 is counterbored at 71, so as to provide an extremely light-weight structure.

A one Way clutch mechanism is provided in chamber 63 for converting the oscillating movement of rocker arm 50 into intermittent rotary motion of shaft 55, and in the illustrated embodiment, the one way clutch mechanism takes the form of a plurality of inwardly facing clutch teeth 76 which trap cylindrically shaped rollers 77 therebetween. Teeth 76 are shaped so as to allow the rocker arm 50 to rotate freely in a clockwise direction (FIG.1;2) relative to the shaft portion 68, but when the rocker arm 50 is rotated in a counterclockwise direction (FIG. 13), the rollers 77 bind the teeth 76 and the shaft portion 68 to rotate the shaft 55 and gripping wheel 30 in a tension drawing direction.

Means is provided for sensing when a predetermined amount of tension has been drawn in strap loop L, and the tension sensing means includes a flat plate-like lever 80 (FIG. 11) having outwardly extending tabs 81 and -82 at opposite sides thereof received in clearance openings 83 and

84in housing members

21 and 22, respectively. Lever 80 includes a tension sensing finger 85 that extends outwardly of housing member 22 through a further opening 86 therein, and finger 85 overlies anvil 31 with the lowermost strap portion 29 being disposed below finger 85, and with the uppermost strap portion 28 being positioned above the finger 85 (FIG. 4). Anvil 31 includes an upraised transverse rib 87 outwardly of the curved, knurled portion 89 that cooperates with strap gripping wheel 30 to compress the overlapping

strap portions

28 and 29 therebetween. When the strap loop L is initially formed around the package P, the lower strap portion 29 sags into the area 88 between rib 87 and anvil portion 89, and after a predetermined amount of tension has been drawn in the loop L, the lower portion 29 of the strap snaps upwardly from the position of FIG. 4 to the position of FIG. to pivot the lever 80 upwardly to the position of FIG. 14, it being understood that sufiicient clearance is provided between

fingers

81 and 82 and

openings

83 and 84 to allow the lever 80 to move freely.

The pivotal movement of lever 80 is resisted by a spring 91 (FIG. 2) that is positioned in a vertical bore 92 in housing member 22, and the force that spring 91 applies to lever 80 may be adjusted by a set screw 93 that is received in the internally threaded upper end of bore 92. In this manner, the amount of tension in the loop L that is sufficient to pivot the lever 80 can be preselected, so that the tautness of the loop L around the package P can be varied, as desired.

Before proceeding with a detailed description of the means for converting the intermittent rotary motion of shaft 55 to oscillating movement, the means for effecting relative movement between strap gripping wheel 30 and anvil 31 to compress the overlapping

strap portions

28 and 29 will be described. In the present embodiment of the invention, the anvil 31 is movable upwardly toward the strap gripping wheel 30, and to this end, the anvil 31 is formed as an outwardly extending shelf at the lower end of a vertically disposed base member 95. As is evident from FIG. 2, base member 95 includes an enlarged noncircular opening 96 that is positioned over shaft portion 68 to enable the base member 95 to move relative to the shaft 55. The means for shifting plate 95 from the position of FIG. 2 to the position of FIG. 4 includes a shaft 98 (FIGS. 6 and 7) that is rotatably journaled in

frame members

21 and 22 above shaft 55. A torsion spring 99 surrounds shaft 98, and one end 100 of spring 99 bears against the top surface of housing member 22, while the opposite end 101 of spring 99 extends through shaft 98 (FIG. 8) to bias the shaft 98 in a counterclockwise direction as viewed in FIGS. 6 and 7. An eccentric pin 102 extends through shaft 98, and one end of pin 102 extends outwardly of frame member 22 where it is rotatably journaled in an opening 102a at the upper end of plate 95. Plate 95 includes an inwardly bent arm 103 that extends inwardly of housing member 22 through an opening 104, and the lower end of arm 103 is provided with an inclined cam surface 105 (FIGS. 6-8) for a purpose to hereafter appear. Arm portion 103 functions as a blocking element preventing oscillation of the gripping wheel 30 until the anvil 31 has moved into strap compressing relationship with respect to the gripping wheel 30, and tension has been drawn in the strap loop L, as will also hereinafter appear.

A return lever 110 has a hub 111 fixed to shaft 98 between plate and housing member 22, and lever has a detent surface 112 .(FIG. 4) that is adapted to be retentively engaged by a hook 113 on a latch lever 114. Latch lever 114 is pivotally mounted upon housing 22 at 116, and a spring 117 is connected between latch lever 114 and housing 22 for retaining the hook 113 in engagement with detent 112 (FIG. 2). When lever 114 is pivoted from the position of FIG. 2 to the position of FIG. 4 to disengage the hook 113 from detent 112, torsion spring 99 rotates shaft 98 to swing the lever 110 from the position of FIG. 2 to the position of FIG. 4 and the action of eccentric pin .102 lifts plate 95 to bring the anvil 31 into strap compressing relationship with respect to gripping wheel 30. The upward movement of plate 95 is limited by the engagement of the lower portion 96a of opening 96 in plate 95 with the bottom of a guide 68a on shaft portion 68. The spacing between surface 96a and anvil 31 is such that a clearance will be maintained between wheel 30 and anvil 31 if lever 114 is released when no strap is present in the tool. After the strap sealing operation is completed, lever 110 is pivoted from the position of FIG. 4 to the position of FIG. 2. to reengage the detent 112 and hook 113 to latch the anvil 31 in a position spaced from wheel 30, so that the strap portion 2 8 can be severed from the strap supply and the tool removed from the package P, as will hereafter appear.

After the anvil 31 has been moved into strap compressing relationship with gripping wheel 30, and the preselected amount of tension has been drawn in the strap loop L through the intermittent rotation of gripping wheel 30, the aforedescribed lever 80 pivots upwardly from the position of FIG. 6 to the position of FIG. 7 to actuate a pawl release member 120. Pawl release member 120 is mounted for pivotal movement above a transverse pin 121 at the lower end of housing member 22. below shaft 55, and a coil spring 122 acts between the lower right hand end of pawl release member 120 and the bottom of housing member 122 to bias the pawl release member in a counterclockwise direction, as viewed in FIGS. 6 and 7. Release member 120 further includes an abutment 123 adjacent the left hand end thereof that is biased into engagement with the upper surface of finger 85 by spring 122, and a downwardly facing hook 124 outwardly of abutment 123 that is biased by spring 122 into retentive engagement with an inwardly curved detent 125 on a pawl reset lever 126.

As can be best seen in FIGS. 11 and 12, pawl reset lever 126 includes outwardly extending fingers 127 and 128 at opposite ends thereof that are received in

openings

129 and 130 in

housing members

21 and 22, respectively, with

openings

129 and 130 being oversized (FIG. 12) to accommodate rocking movement of the latch reset member 126 from the position of FIGS. 12 and 13 to the position of FIG. 14. Lever 126 includes an upwardly extending portion 132 positioned to engage the pawl for resetting the same, and lever 126 further includes an inclined cam surface 133 that is adapted to be engaged by cam surface 105 on plate 95 when reset lever 110 is moved from the position of FIG. 4 to the position of FIG. 2 for repositioning the pawl 140, as will hereinafter appear.

Pawl 140 is pivotally mounted on a transversely extending pin 141, and the pawl includes a first arm 142 having a toothed end portion positioned to engage the ratchet teeth 66 on ratchet wheel 64, and a second end portion 143 positioned to engage the upstanding portion 132 of lever 126. A spring 144 acts between a recess in pawl arm 143 and a recess 145 in the side wall of rocker arm 50 for biasing the pawl 140 in a clockwise direction as viewed in FIG. 12. Thus, after the anvil 31 has been raised, finger 103 on plate 95 is moved to the position of FIG. 7, and the cam surface 105 on finger 103 is spaced above cam surface 133 on lever 126 to condition the pawl 140 for movement into engagement with the ratchet wheel 64. After tension has been drawn in the strap loop L, lever 80 is pivoted to the position of FIG. 7 to free hook 124 from.finger 125 on lever 126, and spring 144 biases lever 126 to the position of FIG. 7, with cam surface 133 positioned below cam surface 105. Concurrently with the movement of lever 126', spring 144 pivots pawl 140 to bring the toothed end 142 of the pawl into engagement with the teeth 66 on ratchet wheel 64 (FIG. 14), and this engagement prevents the ratchet wheel 64 and shaft 55 from rotating in a counterclockwise direction, as viewed in FIGS. 12-l4.

Thus, when the appropriate tension hasbeen attained in the strap loop L, one way clutch means 75 cooperates to prevent shaft 55 from rotating in a clockwise direction, while pawl 140 prevents shaft 55 from rotating in a counterclockwise direction. Accordingly, as rocker arm 50 continues to oscillate, shaft 55 is effectively locked to the rocker arm, and strap gripping wheel 30 is oscillated in a high frequency-low amplitude mode to move the upper strap portion 28 multi-directionally relative to lower strap portion 29.

Motor M is retained energized for a sufficient time such that the movement of the upper strap portion 28 relative to the lower strap portion 29 will generate enough heat at the interface regions between the overlapping strap portions to achieve interface melting. During oscillation of the strap gripping wheel 30, tension in the strap loop L acts upon the overlapping strap portions, and it is thought that this improves the characteristics of the joint that is ultimately produced. Motor M is connected to a commonly available 110 volt source of alternating current through a cord 150 that extends outwardly through the rearward end of the housing of the tool through an opening 151. Motor M may be energized and de-energized through a switch 152 within the housing cavity 27, and switch 152 is actuated by a push button 153 that extends upwardly through the top surface of the housing. Switch 152 is preferably arranged such that whenever push button 153 is depressed, the motor M is energized to rotate the motor shaft 33.

After the friction-fusion joint has been completed, lever 110 is pivoted and reengaged with latch lever 114 to establish a clearance between wheel 30 and anvil 31. As lever 110 is pivoted, cam surface 105 on arm portion 103 moves into engagement with cam surface 133 on reset lever 126 to pivot the reset lever and move the pawl 140 out of engagement with ratchet 64. Arm 103 and lever 126 then cooperate to block pawl 140' and prevent oscillation of gripping wheel 30 until the next joint forming operation.

The tool 20 also includes cutting means that enable the upper strap portion 28 to be easily and conveniently severed from the strap supply source after the frictionfusion joint has been completed. To this end, a knife element 160 is secured to the outer end of the arm 85 of lever 80, and knife member 160 includes a knife-edge 161 that is located outwardly of the overlapping strap of

portions

28 and 29 when they are positioned between the gripping wheel 30 and the anvil 31, with knife edge 161 being positioned generally parallel with the outer edge of upper strap portion 28. When lever 80 is lifted by tension in the strap loop L, the uppermost strap portion 28 leading to the strap supply is positioned at an angle with respect to the length of knife edge 161. Thus, after the latch lever 114 is engaged with the anvil shifting lever 110 to establish a clearance between the gripping wheel 30 and the anvil 31, the tool 20 is merely slid rearwardly, as viewed in FIG. 1, and because of the inclination of upper strap portion 28 relative to knife edge 161, the movement of the tool relative to the strap loop allows the knife edge 161 to easily sever the upper strap portion 28 from the strap supply.

The above described tool is extremely compact and light in weight. FIGS. 2 and 3 are essentially full scale representations of the tool, and the overall weight of the tool is less than four pounds. It will be appreciated that the light weight and compact size of the tool enables a user of the tool to easily manipulate tended periods of time without tiring. Furthermore, the tool 20 may be used in any location where a -volt supply of alternating current is available. In an exemplary embodiment of the invention, motor M rotates at ap proximately 18,000 r.p.m., and because of the direct driving relationship between motor M and gripping wheel 30, when the pawl 142 is engaged with the ratchet wheel 64, the gripping wheel 30 oscillates at a frequency of approximately 36,000 cycles per minute. The total amplitude of the oscillating movement of gripping wheel 30 is approximately .150 to .160 inch. Because of the short length of time that is required to effect the friction-fused joint, a timer T (FIG. 8) may be provided within chamber '27 and connected in circuit with switch 152 for controlling the overall length of the tension drawing and friction-fusing operations.

A modified embodiment of the tool is illustrated in FIGS. 15-17, and because the embodiment of FIGS. 15- 17 is in many respects similar to, or the same as, the previously described embodiment, similar reference numerals have been used in FIGS. l5l7 to designate elements which correspond to those of the previously described embodiments, with the reference numerals in FIGS. 15-17 having been increased by the sum 200.

In certain instances, it is desirable to have the strap from the strap supply extend toward the user of the tool, since this somewhat facilitates manipulation of the tool and formation of the joint. Accordingly, in the embodiment of FIGS. 15-17, certain elements of the drive structure within the housing of the tool 220 are mirror images of the structure illustrated in the previously described embodiment, so that the strap gripping wheel 230 will be rotated in a counterclockwise direction as viewed in FIG. 15 to withdraw the upper end portion 228 of the strap toward the user of the tool and constrict the strap loop into snug article binding engagement with the package being strapped.

As with the previously described embodiment, a block 242 (FIG. 16) is slidably mounted on the eccentric pin 241 of a motor driven sleeve 237. Block 242 is also slidable along a transversely extending pin 243 that impales an opening 244 in the block 242, and rocker arm 250 is connected to pin 243 by arms, such as arm 251, so that the rocker arm 250 is oscillated as the sleeve 237 rotates.

Strap gripping wheel 230 is intermittently rotated in a loop tensioning direction by a one way clutch means 275, that may be defined by teeth 276 on rocker arm 250 and rollers 277 captured between teeth 276. The overlapping

strap portions

228 and 229 are both positioned below the tension sensing finger 285 of a lever 280, and when a preselected amount of tension is drawn in the strap loop, lever 280 is pivoted upwardly to pivot a release lever 320 about pivot 321 against the bias of spring 322 to free hook 324 on lever 320 from catch 325 on a reset lever 326.

Pawl 340 is positioned above rocker arm 250 and to one side thereof, as can be seen in FIG. 16, and when lever 326 pivots, spring 344 biases the toothed portion 342 of the pawl 340 into engagement with the teeth 266 on ratchet wheel 264. When the pawl 340 is engaged with the ratchet wheel 264, rotation of the strap gripping wheel 230 in the tension drawing direction is prevented, and the ratchet and pawl mechanism cooperates with the one way clutch 275 to hold shaft 255 against rotation, so that as rocker arm 250' oscillates, a high frequency, low amplitude oscillation is imparted to strap gripping wheel 230. This latter movement causes the upper strap portion 228 to move relative to the lower strap portion 229 while the overlapping strap portions are retained compressed and, the innerface regions of the overlapping strap portions are heated by the friction that is generated until melting occurs. After the melted interface regions have solidified to unify the overlapping strap portions, the upper strap portion 228 is severed from the the same for exstrap supply by a cutting mechanism best seen in FIGS. 15 and 17.

The cutting mechanism of the embodiment of FIGS. 15-17 differs essentially from the cutting mechanism of the previously described embodiment in that the upper strap 228 is severed from the strap supply in response to movement of the latching lever 314 to the broken line cut position of FIG. 15. Lever 314 includes an arcuate caming surface 370 that is engageable with an abutment 371 on a cutter element 372 that is pivotally mounted upon base plate 295 at 373. Plate 295 includes a reversely bent flange portion 374 that is generally parallel with the main body portion of the plate 295, and pivot pin 373 impales an opening in flange 374 and an aligned opening in the main body portion of plate 295.

Anvil 231 includes an upraised portion 375 which cooperates with plate 395 to define a strap receiving guideway 377 therebetween. The upper surface of upraised portion 375 defines a gauge face that is engaged by a land area on the cutter element 372, as will hereinafter appear. The upper surface of upraised portion 375 is positioned above anvil surface 377 by a distance corresponding to the thickness of the strap. A knife edge 382 is provided at the lower end of cutter element 372, and a fiat land area 383 is spaced from knife edge 382. Land area 383 is movable into engagement with the gauge face on the upper end of anvil portion 375 when the cutter member 372 is moved into strap severing relationship with anvil 231 by lever 314. The lower edge of knife edge 382 is disposed in the same plane as land area 383, so that when the land area 383 engages the gauge face on anvil 231, the edge 382 severs the upper strap portion 228. An extension 379 extends laterally outwardly from cutting edge 383 and rides in a recess 380 in the sidewall of base plate 295, with extension 379 insuring that the cutting edge 383 cuts clear through the strap. The cutter member 372 is preferably gravity biased through the clearance position illustrated in FIG. 15, although spring means may be provided to return the cutter member to this position. Anvil surface 375 protects knife edge 382 from damage if the cutter member 372 is actuated when there is no strap in the tool, thereby preventing damage to the knife edge.

What is claimed is:

1. A drive mechanism for use in a tool for shrinking a loop of strap about an article and for friction-fusion sealing of overlapping portions of the loop comprising: an input member; means for rotating said input member; an output member; means, driven by said input member, for intermittently rotating said output member in one direction for shrinking the loop about an article; and means for converting the intermittent rotating movement of said output member to oscillating movement for effecting relative motion between overlapping portions of the loop.

2. A drive mechanism as set forth in claim 1 wherein said means for rotating said input member includes an electric motor.

3. A drive mechanism for use in a friction-fusion strap sealing tool comprising: an input member; means for rotating said input member; an output member; means, driven by said input member, for intermittently rotating said output member in one direction, said means for intermittently rotating said output member including a rocker arm, means connected between said rocker arm and said input member for oscillating said rocker arm, and clutch means connected between said rocker arm and said output member, said clutch means permitting said output member to rotate in one direction only; and means for converting the intermittent rotating movement of said output member to oscillating movement.

4. A drive mechanism as set forth in claim 3 wherein said movement converting means includes a ratchet and pawl mechanism for preventing rotation of said output member in said one direction, whereby oscillating movement of said rocker arm is transmitted to said output member.

5. A drive mechanism as set forth in claim 4 wherein said means for rotating said input member includes an electric motor.

6. A drive mechanism as set forth in claim 2 including timer means connected to said electric motor for controlling the duration of the oscillating ,movement.

7. A drive mechanism as set forth in claim 5 including timer means connected to said electric motor for c0ntrolling the duration of the osicllating movement.

8. In a friction-fusion tool having a strap gripping wheel for compressing together overlapping portions of a loop of thermoplastic strap, for tensioning the strap loop into snug binding engagement with an article, and for oscillating one of the overlapping strap portions relative to the other strap portion to generate frictional heat and effect interface melting between the interface regions of the overlapping strap portions, the improvement comprising: means for sensing tension in said loop, said sensing means being movable in response to the attainment of a preselected amount of tension in the loop; ratchet and pawl means for enabling said strap gripping wheel to oscillate when said ratchet and pawl means is engaged; latch means for retaining the pawl of said ratchet and pawl means out of engagement with the ratchet thereof; and means for releasing said latch means in response to movement of said tension sensing means.

9. The invention set forth in claim 8 in which said tension sensing means includes a lever positioned to be moved by said loop, and wherein said releasing means includes a pivotally mounted abutment engaging said lever.

10. The invention set forth in claim 9 including a shaft having said strap gripping wheel thereon, said shaft carrying said ratchet and said pawl being mounted for pivotal movement into and out of engagement with said ratchet, spring means urging said pawl toward engagement with said ratchet, and a shifting element engaging said pawl, said shifting element and said abutment having cooperating means defining said latch means, whereby upon actuation of said releasing means said spring means moves said pawl into engagement with said ratchet.

11. The invention set forth in claim 10 including means for moving said pawl out of engagement with said ratchet, said last named means including a movably mounted anvil normally supporting said overlapping strap portions and cooperating cam surfaces on said anvil and said shifting element.

12. In a friction-fusion tool having a strap gripping wheel for compressing together overlapping portions of a loop of thermoplastic strap, for tensioning the strap loop into snug binding engagement with an article, and for oscillating one of the overlapping strap portions relative to the other strap portion to generate frictional heat and effect interface melting between the interface regions of the overlapping strap portions, the improvement comprising: an anvil adapted to support the overlapping strap portions adjacent the strap gripping wheel; means for shifting said anvil into and out of strap compressing relationship with respect to said strap gripping wheel; and means, responsive to movement of said anvil into strap compressing relationship with respect to said strap gripping wheel, for conditioning said strap gripping wheel for oscillating movement.

13. The invention set forth in claim '12 in which the anvil shifting means includes a shaft having eccentric means thereon engaging said anvil, and torsion spring means engaging said shaft and biasing said anvil toward said strap gripping wheel; and wherein latch means releasably retains said anvil out of engagement with said strap compressing wheel.

14. The invention set forth in claim 13 in which the anvil shifting means includes a lever connected to said shaft for moving said anvil out of engagement with said strap gripping wheel against the bias of said torsion spring, and wherein said lever includes a detent engageable with said latch means.

15. The invention set forth in claim 12 wherein said conditioning means includes a blocking element formed integrally with said anvil, said blocking element being movable from a position preventing oscillating movement of said strap gripping wheel to a position permitting oscillation of said strap gripping wheel in response to movement of said anvil into strap gripping relationship with respect to said strap gripping wheel.

16. The invention set forth in claim 15 including means, responsive to movement of said anvil out of strap compressing relationship with respect to said strap gripping wheel, for terminating oscillation of said strap gripping wheel.

17. The invention set forth in claim 16 in which said blocking element has a cam surface thereon, and wherein said terminating means includes a lever having a cam surface thereon that is engaged by the cam surface on said blocking element when said anvil moves out of strap gripping relationship with respect to said gripping wheel.

18. Strapping apparatus for securing a ligature about an article, which ligature is made of a length of thermoplastic strap formed into a loop having overlapping end portions, comprising: a frame having a strap support anvil thereon; a strap gripping member rotatably mounted on said frame; means for effecting relative movement between said anvil and said strap gripping member to compress said overlapping strap portions therebetween and to place opposing surface regions of said overlapping strap portions in frictional engagement; means for intermittently rotating said strap gripping member in a first direction to withdraw one of the end portions to constrict the loop about the article and to place the loop in tension; and means responsive to a predetermined amount of tension in said loop for converting the intermittent rotary motion of said strap gripping member into oscillating movement to produce bodily sliding frictional movement between said opposing surface regions to effect interface melting therebetween, whereby said melted surface regions fuse to achieve interface solidification between the overlapping surface regions.

19. Strapping apparatus as set forth in claim 18 wherein said means for rotating said strap gripping member includes an electric motor having a rotary shaft, and and means connecting said motor shaft to said gripping member.

20. Strapping apparatus as set forth in claim 19 wherein the means connecting said motor shaft and said gripping member includes a rocker arm, eccentric means connected between said rocker arm and said motor shaft for oscillating said rocker arm, and one way clutch means connected between said rocker arm and said gripping member.

21. Strapping apparatus as set forth in claim 20 wherein said movement converting means includes a ratchet and pawl mechanism for preventing rotation of said gripping member in said first direction, whereby oscillating movement of said rocker arm is transmitted to said gripping member.

22. Strapping apparatus as set forth in claim 18 wherein said movement effecting means is defined by means for shifting said anvil toward and away from said strap gripping wheel.

23. Strapping apparatus as set forth in claim 18 including means for adjusting said tension responsive means.

24. Strapping apparatus as set forth in claim 18 including timer means connected to said electric motor for controlling the overall duration of the withdrawing of one of the end portions and of the oscillating movement.

25. A compact, light-weight portable tool for frictionfusing overlapping portions of a loop of thermoplastic strap, said tool comprising: a housing; an anvil outwardly of the housing for supporting the overlapping strap portions; an electric motor within said housing, said electric motor having a rotary shaft; a strap gripping member, said strap gripping member including a shaft portion within said housing and a wheel portion outside of said housing, said wheel portion cooperating with said anvil to compress said overlapping strap portions together, a rocker arm within said housing; eccentric means within said housing connecting said rotary shaft and said rocker arm for oscillating said rocker arm; clutch means within said housing connected between said rocker arm and the shaft portion of said strap gripping member for intermittently rotating said strap gripping member in one direction to tension said loop; and means within said housing responsive to tension in said loop for converting the in termittent rotary movement of said strap gripping member into oscillating movement, whereby the strap portion in engagement with said wheel portion is oscillated relative to the other strap portion to generate heat and to effect melting at the interface therebetween.

26. A tool as set forth in claim 25 including cutter means associated with said housing for severing one of said overlapping strap portions from a supply of strap.

27. A tool as set forth in claim 26 including lever means for actuating said cutter means.

28. A tool as set forth in claim 25 including a handle on said housing, said strap gripping member being arranged to feed said strap toward said handle during tensioning of said loop.

29. A tool as set forth in claim 25 including a handle on said housing, said strap gripping member being arranged to feed said strap away from said handle during tensioning of said loop.

30. A tool as set forth in claim 25 including switch means connected in a circuit with said motor for controlling energization thereof, and timer means connected in said circuit with said switch means for controlling the overall duration of the rotation of the strap gripping member in one direction and of the oscillating movement.

References Cited UNITED STATES PATENTS 2,459,260 1/1949 Brown 156380 2,517,672 8/1950 Jenkins 156380 2,727,560 2/1955 Bradley et al. 156380 3,052,281 9/1962 Hilton 156380 3,419,447 12/1968 Hewitt 1565l5 SAMUEL FEINBERG, Primary Examiner R. E. HART, Assistant Examiner U.S. Cl. X.R.