CA1109237A - Strap segment - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A flat strap segment is formed into a loop and ten-sioned about an article with the strap having outer and inner overlapping portions retained in a fixed position solely by a crimped seal. The outer overlapping portion of the strap has a distal end segment protruding from the crimped seal and terminating in a terminal portion. A bend is provided in the distal end segment inwardly of the terminal portion and spaced axially from the adjacent end of the crimped seal for directing the terminal portion toward a flat underlying region of the inner overlapping portion of the strap to minimize exposure of the sharp cut edge of the strap.

Description

This is a division of our copending Canadian Patent Application No. 239,407 filed November 12th, 1975.
Background of the Invention When a package is secured by a strap, the package is circumscribed by the strap so that the strap has overlapping portions. These overlapping portions are enclosed in a seal structure, the strap is tensioned to a pre-selected tautness about the package, the seal is crimped about the overlapping strap portions to secure the overlapping strap portions together, and the excess strap situated externally of the seal is cut off or sheared. In this manner continuous strap which may be supplied from a reel can be used.
Illustrative prior art tensioning and shearing tools include those shown in United States Patent No. 3,150,694 to Meier wherein the shearing mechanism includes a driving cylinder-piston assembly which is energized by opening a valve so that air is supplied to the cylinder to move the piston and the piston rod. The strap is sheared along the edge of the seal without using a cutting block.
Another prior art tensioning and shearing tool is disclosed in United States Patent No. 3,028,885 to Leslie et al., wherein a first handle is moved to actuate the tensioning mechanism, and a second handle is provided to operate the shearing mechanism. Shearing is effected by rotating the second handle, to which a cutter is pivotally connected, thereby severing the strap between the cutter blade and the straight cutting edge of a cutting block. The second handle is biased toward the off-position by a handle spring, but the second handle can be operated any number of times before a subsequent tensioning operation is initiated.
Summary of the Invention The present invention provides in a flat strap segment formed into r a loop tensioned about an article and having outer and inner overlapping portions retained in fixed position solely by a crimped seal, said seal -~ 30 surrounding part of said overlapping portions and deformed along with said outer and inner overlapping portions, said outer overlapping portion having a distal end segment protruding from said seal and terminating in a terminal -1- ~

portion, the improvement which comprises a bend in said distal end segment inwardly of said terminal portion, said bend being axially spaced from t'ne adjacent end of said seal and directing the terminal po-rtion toward a flat underlying region of the inner overlapping portion of strap, any springing action, if existing, of said outer overlapping portion against said crimped seal being insufficient to weaken said crimped seal.
This reduces the exposure of the sharp cut edge of the strap. Pre-ferably the bend has an included angle of less than about 150 degrees, and preferably the terminal portion abuts the inner overlapping portion of the strap.
rief Description of the Drawings Figure 1 is a side elevational view of a strap tensioning and cut-ting tool for for~ing the strap segment of the present invention;
Figure 2 is a frontal elevational view of the tool of Figure 1 taken from the left side of the tool as shown in Figure l;
Figures 3A through 3D are fragmentary cross-sectional views of the tool of Figure 1 taken along plane 3-3 in Figure 2 and show in sequence the operation of the tool during the strap cut-off; and Figure 4 is a side elevational view of the strap and seal after cut-off-Description of the Preferred Embodiments Referring to the Figures, there is illustrated an integrated strap tensioning and shearing tool. While the tool is intended primarily for use with steel strap, the tool can also be utilized with plastic strap and the like.
Tool 10 has a main frame 11 having upright portion 12 and base por-tion 13 Pivot shaft 14 is mounted on upright portion 12 of frame 11 and carries tensioning assembly 16 pivotally mounted thereon.
Tensioning assembly 16 includes a pneumatic motor means 18 con-trolled by valve operator 19 which receives air from any convenient source.

~lotor means 18 may be a reversible air motor, although the tool can also be utilized with other types of motors. The output shaft of air motor 18 drives knurled tensioning wheel 26 through a suitable transmission situated within a gear housing 20. Air motor 18 and tensioning wheel 26 are operably connected by means of drive shaft 27 and are mounted on gear housing 20 which, in turn, is mounted for pivotal movement on pivot shaft 14. Supporting link 28 is also pivotally mounted on pivot shaft 14, and common drive shaft 27 for tensioning wheel 26 and ratchet wheel means 40 is journaled therein.
As shown in Figure 2, torsion spring 31 provides an additional downward force urging tensioning wheel 26 against the strap. Torsion spring 31 is carried on pivot shaft 14 and is connected to gear housing 20 and frame 11 by means of pin 25 and generally L-shaped member 33, respectively. General-ly L-shaped member 33, pivotally mounted on upright portion 12 of frame 11 by pin 32 can also be made integral with upright portion 12, if desired, and provides an abutment for torsion spring 31. The additional downward force provided by the torsion spring 31 urges tensioning wheel 26 against the strap and helps to start the tensioning. Additionally, after the cut-off cycle is completed, torsion spring 31 helps to hold the cut-off portion of strapin the tool.
As shown in Figures 3A through 3D, tensioning, wheel 26 grips strap positioned within the tensioner and pulls the upper, outer, overlapping strap portion 34 through s0al 38 when the motor 18 is energized to rotate tensioning wheel 26 in the direction indicated by arrow A. Excess strap 29 is pulled through seal 38 until strap segment 30 which circumscribes a package is tensioned to a predetermined tautness. Strap 30 and seal 38 can then be crimped to fix the produced joint in a conventional manner. As the tensioning wheel 26 bears down on strap 30, the lower overlapping strap portion 36 is held and gripped during the tensioning operation against ' - ~ . :- .

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serrated surface 39a on gripping block 39 which is mounted in base portion 13 of frame 11.
When strap is tensioned and sealed, shearing mechanism 74 is brought into operation. The shearing mechanism 74 includes a movable cu~-ting block 76 which preferably is slidably mounted on frame 11 and floats on carrier spring 92, cutter housing 78, cutter blade 80, and a cutter link 82 connected at one end to a crank 62 by cutter link pin 84, and connected at the opposite end to cutter blade ~80 by cutter pin 86, Cutting block 76 may also be cantilevered from cutter housing 78 or pivotally mo~l~ed on cut-ter housing 78, as desired. Cutter blade 80 preferably is slidably mounted,as will be discussed hereinbelow. Alternatively, cutter blade 80 could be pivotally mounted or can be a rolling blade which traverses the strap segment to be cut. Crank 62 also carries pawl 42 pivotally mounted thereon by means of ra~che~ link pin 44.
Shearing mechanism 74 is driven by ratchet wheel 40 which is mounted on drive shaft 27 and is driven simultaneously with tensioning wheel 26. In the preferred embodiment ratchet wheel 40 is positioned and arranged with respect to tensioning wheel 26 such that pawl 42 cannot engage the teeth : of ratchet wheel 40 when the wheel rotates in the tensioning direction which is illustrated by arrow A. However, when the wheel rotates in the opposite (cut-off) direction, illustrated by arrow B, pawl 42 can engage the teeth of ratchet wheel 40 and actuate cutter blade 80.
Pawl 42 has one end adapted to engage the teeth of ratchet wheel ; 40. The opposite end of pawl 42 has one end 52 of elastic pawl positioning means 50 attached thereto. Gpposite end 54 of pawl positioning means 50 is attached to a latch means including lobe means 56 which is also provided with shifting lever 58 fixedly secured thereto. Preferably elastic pawl positioning means 50 is connected to pawl 42 and lobe 56 in an overcenter " . ~, . . .
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arrangement so that lobe 56 locks by means of snap action over dead center in either the on-position or in the off-position.
Pawl positioning means 50 may be a spring means such as a tension spring. '~hen shearing mechanism 74 is in the off-position and tensioning wheel 26 rotates in the tensioning direction, tension spring 50 holds pawl 42 out of engagement with ratchet wheel 40 and also holds lobe 56 against stop surface 57.
To bring shearing mechanism 74 into opera~ion, lobe 56 is manually moved counterclockwise, in the direction of arrow C (Figure 3A)~ to the on-position illustrated in Figure 3B so that lobe 56 -abu~s-circular boss 59 ; which provides stop surface 59a for lobe 56. Due to the overcenter arrange-ment, tension spring 50 holds lobe 56 against stop surface 59a on the gener-ally circular boss 59. Tension spring 50 thereby biases pawl 42 into engage-ment with ratchet wheel 40, whereby ~he pawl is in a position to actuate cutter blade 80 when ratchet wheel 40 is rotated in direction B. Reversible air motor 18 is manually reversed, and the cut-off stroke is *hus initiated.
Crank pin 66 pivotally mounts crank 62 on frame 11. As illustrated in Figures 1 and 3A-3D, crank 62 is generally L-shaped and is pivotally ~ connected at the end of one leg to cutter link 82 by cutter link pin 84.
i~ 20 The end of the other leg of crank 62 has a projection 68.
As ratchet wheel 40 raises pawl 42, crank 62 is rotated counter-clockwise, in the direction of arrow D in Figure 3C, thereby permitting cut-off to occur. Midway through the cut-off cycle, cam surface 69 on lobe 56 is engaged by projection 68 on crank 62 and lobe 56 is rotated clockwise in the direction of arrow E ~Figure 3C). Lobe 56 is thus pivoted from the on-position until end 52 of the tension spring, which is attached to the lobe 56, reaches an overcenter position relative to end 54 of the tension spring, which is attached to pawl 42, whereby tension spring 50 continues to rotate lobe 56 to the off-position until lobe 56 abuts stop surface 57, as illustr-ated in Figure 3D. This insures that only a single cut-off stroke occurs each time lobe 56 is shifted to the on-position and a cut-of stroke is initiated.
At the end of the cut-off stroke, surface 70 of pawl 42 contacts roller 72 which is attached to upright portion 12 of frame 11. Roller 72 serves as a stop, and as is shown in Figure 3D, pawl 42 is thereby rotated clockwise in the direction of arrow F ~Figure 3D) until it contacts roll pin 73 which stops its clockwise movement. Pawl 42 thereby disengages ratchet wheel 40 and returns to the position of Figure 3A. This further insures that only a single cut-off stroke will occur, and automatically resets pawl 42 to the off-position.
As depicted in Figures 3C and 3D, as pawl 42 is raised by ratchet wheel 40, crank 62 is rotated counterclockwise in the direction of arrow D, thereby causing cutter link 82 and cutter blade 80 to move downwardly and shear the excess portion 29 of the strap. Cutter spring means 85 is thereby compressed, and causes strap cut~er means 74 to return to the off-position.
Stop surface 93 limits the clockwise movement of crank 62 after a cut-off stroke.
Cutter blade 80 moves vertically and substantially perpendicular relative to uppèr overlapping strap 34 which is to be sheared. Since it is the rotation of crank 62 that causes cutter blade 80 to ~ove vertically cutter link 82 provides a lost-motion~connection between crank 62 and cutter blade 80, both of which are pivotally connected by pin 86.
, A feature of this toollOisthe saf~*y with which it is operated.
, ~; Tension spring 50 prevents pawl 42 from engaging ratchet wheel 40 unless the ; operator of tool 10 intentionally decides to cut the strap by moving lobe 56 ; from the off-position to the on-position. By doing so, only a single cut-off stroke occurs, and pawl 42 and lobe 56 are automatically returned to the ' , ' off-position. If an additional cut-of stroke is desired, cut-off le~er 5 must be manually moved to the cut-off position.
A further feature is the configuration of cutting block 76. Cut-ting block 76 has a cutting edge 87 positioned transverse to the tensioning direction of the strap, and preferably facing toward tensioning wheel 26.
Cutting block 76 is provided with a chamfer 88 at one end of upper face 89 and along cutting edge 87. Since the overlapping strap portions 34 and 36 are fed into tool 10 so that floating cutting block 76 slidably mounted on frame 11 and supported by carrier spring 92 is positioned therebetween as illustrated in Figure 3D, chamfer 88 has the advantage of causing cut edge 90 of stra? 34 to bend downwardly upon being cut. This is a safety feature minimizing the exposure of the sharp cut edge 90 of the straR. During strap cut-off lower inner strap portion 36 is held against base portion 13 of frame 11 by floating cutting block 76 which functions as a clamping means for pre-venting sideways movement of sealed strap portions 34 and 36 as the cutting blade engages strap portion 34.
Referring to Figure 4, outer and inner overlapping strap portions - 34 and 36 are retained in fixed position by seal 38 surrounding the overlap-- ping strap portions. The outer strap 34 has distal end 35 protruding out-- 20 wardly from seal 38 and the terminal portion 37 of outer strap 34 has a bend directing terminal portion 37 toward inner overlapping strap portion 36.
Preferably, the included angle 0 be~ween distal end 35 and terminal portion 37 is less than about 180. More preferably, the included angle 0 is less than about 150. It is particularly preferred to have a bend in outer strap portion 34 which causes the terminal portion 37 to abut the inner overlapping strap portion 36.
Another feature of chamfer 88 is the protection afforded to cutting edge 87 of cutting blcck76 du~ng the tensioning operation, becauses~ap portion ~4ishe~

%37 away from cutting edge 87 until, such time when a strap segment 30 is to be cut off, thereby minimizing wear of cutting edge 87 as the strap is tensioned.
Yet another feature is thak the time between engagement of pawl 42 by ratchet wheel 40 and tension release on the strap can be convenientiy controlled by selecting the number of serrations (teeth) on the ratchet wheel.
The lower the number of serrations, the greater the time period between ratchet engagement of the pawl and tension release. Tension release before cut-off is particularly important when plastic strap is being used in order to avoid shattering of the strap.
In operation, tool 10 is initially in the position illustrated in Figure 3A wherein tension spring 50 holds pawl 42 ou~ of engagement with ratchet wheel 40. Strap 30 circumscribes a package and has upper and lower overlapping portions 34 and 36 on opposite sides of cutter block 76 and through a seal 38 which is initially uncrimped. Reversible motor means 18 is actuated and tensioning wheel 26 grips the strap and rotates in the dir-ection of arrow A, pulling upper strap portion 34 through seal 38. At the ;- same time lower strap portion 36 is held in place by the coaction of the grip-ping block 39 and the ~ensioning wheel 26. The strap is tensioned to a predetermined tautness and seal 38 is crimped.
As shown in Figure 2, lobe 56 is manually moved in the direction of arrow C to the on-position. Tension spring 50 thereby biases pawl 42 iffto engagement with ratchet wheel 40, which enables pawl 42 to actuate cutter blade 80. Cut-of~ is initiaked by manually reversing reversible air motor 18, so that ratchet wheel 40 rotates in the direction of arrow B.
During the cut-off cycle, pawl 42 is raised by the ratchet wheel 40, as can be seen in Figure 3C, and crank 62 is rotated in the direction of arrow D. Cam surface 69 on lobe 56 is engaged by projection 68 on crank 62 and lobe 56 is rotated in the direction of arrow E from the on-position until 23~

it reaches anovercenterposition relative to pawl 42, whereby tension spring 50 continues to rotate lobe 56 to the off-position ~Figure 3D).
The rotational movement of the crank as the pawl 42 is raised by ratchet wheel 40 causes cutter link 82 and cutter blade 80 to move downwardly and shear the excess portion 29 of the upper strap 34. The cutter spring means 85 is compressed by the downward movement of cutter link 82 and urges strap cutter means 74 to the off-position. The rotational movement of crank 62 after ~ cut-off stroke is limited by stop surface 93.
~ hen the cut-off stroke is completed, Figure 3D, surface 70 of 10 pawl 42 contacts roller 72 which serves as a stop. Pawl 42 is thereby rotated in the direction of arrow F until it con~acts roll pin 73 which stops i~s clockwise movement. P~wl 42 thereby disengages ratchet wheel 40. The cut-off cycle is completed, and tool 10 is automatically returned to the off-posi-tion, whereupon another cycle of tensioning, crimping and cutting-off may be commsnced.
While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and described herein in detail preferred embodimcnts of the invention, 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.

Claims (4)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a flat strap segment formed into a loop tensioned about an article and having outer and inner overlapping portions retained in fixed position solely by a crimped seal, said seal surrounding part of said overlapping portions and deformed along with said outer and inner overlapping portions, said outer overlapping portion having a distal end segment protruding from said seal and terminating in a terminal portion, the improvement which comprises a bend in said distal end segment inwardly of said terminal portion, said bend being axially spaced from the adjacent end of said seal and directing the terminal portion toward a flat underlying region of the inner overlapping portion of strap, any springing action, if existing, of said outer overlapping portion against said crimped seal being insufficient to weaken said crimped seal.

2. The improvement as defined in claim 1 wherein the angle of said bend in said distal end segment is less than about 180° as measured along the surface of said outer overlapping portion that faces toward said inner overlapping portion.

3. The improvement as defined in claim 1 wherein the angle of said bend in said distal end segment is less than about 150° as measured along the surface of said outer overlapping portion that faces toward said inner overlapping portion.

4. The improvement as defined in claim 1 wherein said terminal portion abuts said inner overlapping portion of strap.