GB1597348A - Methods and apparatus for forming and securing a strap loop about a package - Google Patents
Methods and apparatus for forming and securing a strap loop about a package Download PDFInfo
- Publication number
- GB1597348A GB1597348A GB52966/77A GB5296677A GB1597348A GB 1597348 A GB1597348 A GB 1597348A GB 52966/77 A GB52966/77 A GB 52966/77A GB 5296677 A GB5296677 A GB 5296677A GB 1597348 A GB1597348 A GB 1597348A
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- GB
- United Kingdom
- Prior art keywords
- strap
- loop
- free end
- package
- primary
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
- B65B13/00—Bundling articles
- B65B13/18—Details of, or auxiliary devices used in, bundling machines or bundling tools
- B65B13/24—Securing ends of binding material
- B65B13/32—Securing ends of binding material by welding, soldering, or heat-sealing; by applying adhesive
- B65B13/322—Friction welding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
- B65B13/00—Bundling articles
- B65B13/02—Applying and securing binding material around articles or groups of articles, e.g. using strings, wires, strips, bands or tapes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
- B65B13/00—Bundling articles
- B65B13/02—Applying and securing binding material around articles or groups of articles, e.g. using strings, wires, strips, bands or tapes
- B65B13/04—Applying and securing binding material around articles or groups of articles, e.g. using strings, wires, strips, bands or tapes with means for guiding the binding material around the articles prior to severing from supply
- B65B13/06—Stationary ducts or channels
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
- B65B13/00—Bundling articles
- B65B13/18—Details of, or auxiliary devices used in, bundling machines or bundling tools
- B65B13/22—Means for controlling tension of binding means
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Basic Packing Technique (AREA)
- Auxiliary Devices For And Details Of Packaging Control (AREA)
- Package Closures (AREA)
- Making Paper Articles (AREA)
- Package Frames And Binding Bands (AREA)
- Wrappers (AREA)
Abstract
In this method, a primary band loop is formed by introducing a length of band into a circular guide (28). The free band end is guided in a circle on the inner circumference of the guide (28), until the free band end overlaps with part of the loop. Next, the primary band loop is retained and a guide (28) is pressed off vertically downwards. The loop (30) is then widened until it is large enough to span the package (24) to be tied. This is carried out by retaining the free band end while the band is fed out. The package (24) is then guided over the widened loop (30) and the loop (30) is laid round the package (24). The loop (30) can then be tautened and joined together by fusing the overlap region. <IMAGE>
Description
(54) METHODS AND APPARATUS FOR FORMING AND
SECURING A STRAP LOOP ABOUT A PACKAGE
(71) We, SIGNODE COR
PORATION, a Corporation organised under the laws of the State of Delaware,
United States of America, of 3600 West
Lake Avenue, Glenview, Illinois 60025,
United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to methods and apparatus for forming and securing a strap loop about a package.
In the past, we have developed several methods and machines for forming a strap loop about a package, tensioning the loop, and joining the overlapping portions of the tensioned loop by friction-fusion or other means. Such methods and apparatuses are typified by those disclosed and claimed in
U.S. Patents No. 3,442,732, No. 3,442,733,
No. 3,442,734, No. 3,442,735, No. 3,442,203 and No. 3,586,572.
Some strapping machines, such as the machine described in U.S. Patent No.
3,442,203, are of the completely automatic type, i.e. one which automatically feeds a thermoplastic strap around a package from a strap supply source, grips the leading end of the strap, withdraws the standing length of the strap to tension the strap loop, friction-fuses the overlapping portions of the loop, and severs the loop from the standing length of the strap. However, an automatic strapping machine of this construction has a relatively large, ring-like rigid chute into which the package is inserted and in which the strap is fed to form a closed loop around the package. A ring-like chute requires a work space, or operating space. large enough to accommodate the chute and large enough to provide insertion and removal areas for the package.
Automatic strapping machines which use ring-like chutes to form the loop about the package are somewhat inefficient with respect to strapping different size packages.
For example, if a strapping machine is intended to strap large packages, say three feet in diameter, then the strap chute must be at least three feet in diameter. If, subsequently, the machine is used to strap much smaller packages, say one foot in diameter, then the strap loop formed around the smaller package is initially three feet in diameter and the machine must withdraw a substantial amount of trailing strap during the tensioning process to decrease the diameter of the loop and tighten it about the one-foot diameter package.
According to one aspect of the present invention, there is provided a method of forming a strap loop and securing it about a package comprising: feeding a length of strap and guiding a leading end portion thereof in an arcuate path so as to form a primary loop with the leading end of the said strap overlapping a part of the said length of strap, the said leading end portion being guided by strap guide means which act on the straps from only one side of the said arcuate path; restraining the said free end of the strap to prevent further movement of said free end; causing the standing length of strap to advance towards the loop to expand the loop to a predetermined diameter; effecting relative movement between the package and the expanded loop to locate the expanded loop about the said package; and either before or after effecting such relative movement between said package and expanded loop, joining said free end of the strap to an adjacent overlapped portion of the strap.
According to another aspect of the present invention, there is provided apparatus for forming a strap loop and securing it about a package, comprising: strap guide means for guiding a leading end portion of a length of strap in an arcuate path such as to form a primary loop with the leading end portion of the said strap overlapping a part of the said length of strap the strap guide means acting on the strap from only one side of the said arcuate path; means for restraining the said free end of the strap to prevent further movement of the said free end; means for causing the standing length of strap to advance towards the loop to expand the loop to a predetermined diameter; means for effecting relative movement between the package and the expanded loop to locate the expanded loop about the package; and means for joining the said free end of the strap to an adjacent overlapped portion of the strap either before or after effecting such relative movement between the package and the said expanded loop.
The invention thus provides a strapping method and apparatus wherein the strap loop can be formed without the need for a large, ring-like chute into which a package must be inserted. In use the method of the invention requires less space than the known method discussed above, which requires a chute, and can be performed on a work table or desk, and can be used for strapping small packages.
The invention may be carried into practice in various ways but a generalised description of the preferred way will now be given followed by a specific description and a number of alternatives.
In the preferred embodiment of the method of the present invention, the primary strap loop is formed by feeding a length of strap into a substantially circular guide or cup so that the strap free end is guided around in a circle by the inner periphery of the cup to form a loop with the strap free end overlapping a portion of the loop. Next, the formed primary strap loop is held, gripped or guided to maintain the primary strap loop in the plane of its original formation and the circular cup is lowered away from the primary loop in a direction normal to the plane of the loop.
The loop is then expanded to a size large enough to fit around the particular package to be strapped. More specifically, the strap free end is gripped or restrained from further movement while the standing length of strap is continued to be fed to expand the loop to the desired size. The package is then moved near, or over, a portion of the expanded loop and the loop is placed about the package, after which the loop is tensioned to tighten it about the package.
When the loop has been sufficiently tightened, the strap free end is connected or joined to an adjacent overlapping portion of the
loop by appropriate means, such as by friction fusion, application of an independent seal, or by formation of an interlocking slit type joint. The completed loop can then be severed from the trailing length of strap.
In the preferred embodiment of the apparatus of the present invention, a supply of strap is threaded in guideways in a horizontal strap transport zone below a horizontal package support surface. The strap is further threaded between a traction wheel and an idler wheel, the traction wheel being driven by an electric motor to advance the strap forward when feeding the strap to form a loop and to withdraw the strap backwards when tensioning the loop.
A cylindrical cup is provided to receive the free end of the strap as it is fed forward.
The strap enters the cup through an opening or slot in the cylindrical side of the cup and impinges upon the interior surface of the cup where the strap is further guided in a closed arcuate path to form a small primary strap loop with the free end overlapping a portion of the strap loop. The cup is mounted for movement between this first, strap receiving, position and a second position beneath the first position. After the strap loop has been formed, the cup is lowered to the second position and the formed primary strap loop, being supported by the standing length of strap in the strap transport zone guideways, remains suspended at the elevated first position above the lowered cup.
A combination cylindrical gripping/welded member extends through the bottom of the cylindrical cup and up into the inside of the formed primary strap loop. A movable anvil member is provided on the exterior of the formed strap loop and is movable toward and away from the combination gripping/welding member.
When the cup has been moved to the lowered position below the formed primary strap loop, the anvil member is moved toward the gripping/welding member and presses the overlapped portion of the strap loop therebetween. The gripping/welding member has a rough peripheral gripping surface which engages a side of the strap free end while the anvil surface contacting the side of the overlapped portion of the loop is smooth. Thus, as the strap continues to be fed, the strap free end is restrained from movement and the overlapped portion of the loop slides between the strap free end and the smooth surface of the anvil to expand the loop to a larger diameter. When a predetermined larger diameter has been reached, the feeding of the strap is terminated.
A package, having been placed upon the raised package support surface adjacent the overlapped portion of the strap loop, is then moved forward to overhang the horizontally oriented loop. The operator then grasps the strap loop and lifts it around the package by twisting the loop about the restrained overlapping strap area to a vertical orientation about the package.
Reversal of the traction wheel withdraws the standing portion of the length of strap to tighten the loop about the package. When the strap is tensioned to tighten the loop, the gripping/welding member is still engaged with the strap free end to prevent its movement and to allow the loop to be tightened.
As the loop is tightened about the package, the strap free end and the adjacent overlapped loop portion of the strap between the anvil member and the gripping/welding member are oriented with their sides perpendicular to the bottom surface of the package and lying in the plane of the loop about the package. In this configuration, strap loop is next frictionfusion welded in the overlapping area. The gripping/welding member is rotatably oscillated at a high frequency to move the strap free end back and forth relative to the overlapped portion of the strap loop thereby generating sufficient friction heat to fuse the strap free end to the overlapped portion of the loop. A cutter blade is provided to sever the standing length of strap from the loop.Next, as the anvil is retracted away from the gripping/welding member, the twisted, overlapped portion of the loop twists back to assume the normal orientation lying flat against the package.
The package can then be removed from the apparatus.
The invention may be carried into practice in various ways but one form of apparatus and its method of use in accordance with the invention, together with a number of modifications, will now be described by way of example with reference to the accompanying drawings in which like numerals are employed to designate like parts throughout and in which::
Figure 1 is a partial perspective view of a first embodiment of apparatus for strapping a package;
Figure 2 is a partial perspective view similar to Figure 1 and showing a package on the apparatus with the strap cup in raised position;
Figure 3 is a partial perspective view similar to Figure 2 showing the strap cup in the lowered position and the strap being expanded to a predetermined larger diameter;
Figure 4 is a partial perspective view similar to Figure 3 showing the expanded strap loop being located about the package;
Figure 5 is a partial perspective view similar to Figure 4 showing the strap loop tensioned about the package;
Figure 6 is a partial fragmentary perspective view of the apparatus shown in
Figure 1;;
Figure 7 is an enlarged, partial, fragmentary top view of the apparatus shown in Figure 2 with the strap cup in raised position and a length of strap formed into a loop within the cup;
Figure 8 is a sectional view taken generally along the plane 8-8 of Figure 7;
Figure 9 is an enlarged, partial, fragmentary top view similar to Figure 7 but with the strap cup in the lowered position and the strap loop expanded to a larger predetermined diameter;
Fig. 10 is a sectional view taken generally along the plane 10--10 of Figure 9;
Figure 11 is a sectional view similar to
Figure 10 showing the expanded loop located about a package;
Figure 12 is an enlarged, partial top view of the apparatus shown in Figure 6 showing in detail the strap tension sensing mechanism;;
Figure 13 is a schematic diagram of the pneumatic control system for the apparatus shown in Figures 1 to 12;
Figure 14 is a simplified control block diagram for the apparatus shown in Figures 1 to 12;
Figure 15 is a top view similar to Figure 2 of the strap loop forming area of a second embodiment of apparatus for strapping a package;
Figure 16 is a view similar to Figure 15 showing the method of expanding the strap loop to a larger diameter;
Figure 17 is a cross-sectional view taken generally along the plane 17-17 of Figure 15;
Figure 18 is a view similar to Figure 8 illustrating the strap loop forming area of a third embodiment of apparatus for strapping a package;
Figure 19 is a cross-sectional view of the strap loop forming area of a fourth embodiment of apparatus for strapping a package;;
Figure 20 is a reduced cross-sectional view taken generally along the plane 20--20 of Figure 19;
Figure 21 is a top view of the strap loop forming area of a fifth embodiment of apparatus for strapping a package;
Figure 22 is a simplified diagrammatic top view of the strap loop forming area of a sixth embodiment of apparatus for strapping a package;
Figure 23 is a view of the sixth embodiment, similar to Figure 22, illustrating the formation of a primary strap loop;
Figure 24 is a view of the sixth embodiment, similar to Figure 23, illustrating the formation of an expanded strap loop;
Figure 25 is a view of the sixth embodiment, similar to Figure 24 but much reduced in scale, to show an expanded strap loop placed about a package;
Figure 26 is a top view of the strap loop forming area of a seventh embodiment of apparatus for strapping a package;;
Figure 27 is a cross-sectional view taken generally along the plane 27-27 of Figure 26 showing a primary strap loop being lifted from a guide;
Figure 28 is a top view of the seventh embodiment, similar to Figure 26, showing an expanded strap loop;
Figure 29 is a cross-sectional view of the strap loop forming area of an eighth embodiment of apparatus for strapping a package;
Figure 30 is a cross-sectional view taken generally along the plane 30--30 of Figure 29 and
Figure 31 is a simplified, partially schematic diagram illustrating an alternative form of primary strap loop.
For ease of description, the various embodiments of the apparatus that may be used for strapping a package wilf be described in normal operating position, and terms such as upper, lower and horizontal will be used with reference to this normal operating position. It will be understood, however, that the apparatus may be manufactured stored, transported, sold and operated in orientation other than the normal operating position described.
The apparatus illustrated herein which may be used to effect the method of this invention has certain conventional drive mechanisms and control mechanisms which, though not fully illustrated or described, will be apparent to those having skill in the art and an understanding of the necessary functions of such drive mechanisms causing proper operation of the apparatus as will be explained.
A preferred embodiment of the expanding strap loop forming and friction fusion apparatus in accordance with the present invention is designated generally as 20 in Figure 1. Preferably, the apparatus is of a size suitable for being placed on a worktable or desk and is advantageously used to strap rectangular parallelpipedshaped packages having dimensions of between 5 and 40 inches on each side.
However, the apparatus can accommodate much larger or smaller packages and packages of different shapes.
As shown in Figure 2, the apparatus 20 of the present invention has a package support surface 22 for supporting a package 24. The apparatus 20 has a lower surface or shoulder 26 stepped below the elevation of the package support surface 22.
Outline of the Major Steps of the Strapping
Sequence
To aid in understanding the details of construction of the apparatus 20, a brief outline of the process of forming and securing a strap loop about a package will first be given.
As illustrated in Figure 2, a package 24 is first placed upon the package support surface 22 near shoulder 26. A cylindrical cup 28 is raised from a position below the surface of shoulder 26 to an elevated position above the surface of shoulder 26. A length of strap is fed into the cup to form a primary strap loop. The cup 28 is then lowered to a position below the surface of shoulder 26 while the loop is maintained at the higher elevation where it is expanded to a predetermined larger diameter loop 30 as illustrated in Figure 3. Next, the operator slides the package 24 forward to overhang shoulder 26 and then places the expanded loop 30 about the package 24 as illustrated in Figure 4. The strap is tensioned to draw the loop tight about the package (Figure 5).
The entire process is completed when the tension loop is friction fusion welded to form a connection and then severed from the strap supply.
The specific features of the apparatus used to accomplish the above-described package strapping process will next be discussed in detail. The major features or mechanisms of the apparatus are: 1) the strap loop forming mechanism; 2) the strap feed tensioning mechanism; 3) the strap loop friction fusion mechanism; 4) the strap severing mechanism; 5) the pneumatic actuation system, and 6) the electrical control system.
Strap Loop Forming Mechanism
A feature of the apparatus is the mechanism automatically for first forming a primary strap loop that can be subsequently expanded to any larger size. The apparatus for forming the primary strap loop is most clearly shown in Figures 6 to 11.
By a strap feed mechanism described hereinafter, the strap is fed into a guide means. A circular band member, or cup 28, provides a circular guide means for forming the primary strap loop. Cup 28 is a substantially cylindrical member and may or may not have open ends. In the preferred embodiment illustrated, cup 28 has a partially closed bottom and an open top. A portion of the vertical cylindrical wall of the cup 28 is cut away to form a relatively large opening or slot 34 for receiving a length of strap 36 as shown in Figure 7. The cup 28 guides the strap free end 38 in a closed arcuate path whereby the free end 38 is directed back upon the length of strap 36 to form the initial primary strap loop with the free end of the strap overlapping a portion of the formed strap loop.
The cup 28 is movable between an upper, or raised position, and a lowered position.
The mechanism for raising and lowering the cup 28 may be of any appropriate type. As illustrated in Figure 6, the cup 28 is secured to a drive member 64 which is attached to an electric solenoid actuator 66.
The length of strap 36 is oriented with its side surfaces perpendicular to the plane of the package support surface 22 and is guided beneath the package support surface 22 in a strap transport zone 40 which lies between the package support surface 22 and the plane of shoulder 26. The strap transport zone 40 has a thickness substantially equal to the width of the length of strap 36 and is essentially a stratum in which the length of strap 36 is fed, guided, formed into a primary loop, expanded into a larger loop, tensioned, friction welded and severed. In the raised position (as illustrated in Figure 2), the cup 28 lies in the strap transport zone 40. In the lowered position (as illustrated in Figures 1 and 6), the cup 28 lies below the strap transport zone 40. The length of strap 36 is guided within the strap transport zone 40 by appropriate guideways 42 as illustrated in Figure 6.The strap is also fed forward and tensioned backwards through the guideways 42 in zone 40 by appropriate traction drive means as will be described hereinafter.
During loop formation, the strap free end 38 is 1) guided into the cup slot 34, 2) maintained within the cup 28 by upper and lower guides, and 3) restrained above cup 28 during lowering of cup 28 and subsequent expansion of the loop. These guides and strap restraining means will be described with reference to Figure 7. Adjacent slot 34 is an anvil 44 which is mounted on movable slide 46. A portion of anvil 44 adjacent the length of strap 36 has a smooth-surface polyurethane pad 48 secured thereto for guiding and contacting length of strap 36 as will be described hereinafter. Opposite the polyurethane pad 48 is a cylindrical member, or weld head 52, which serves two functions: 1) gripping the strap free end 38 and 2) welding the free end to the overlapped portion of the loop. The welding function will be described later.At this point, just the gripping or restraining feature of the weld head will be discussed.
The weld head 52 is mounted on shaft 53 and is a substantially cylindrical member having a rough, peripheral gripping surface 54 adapted for contacting a side of the strap free end 38. Both the weld head 52 and the anvil 44 lie in the strap transport zone 40 as illustrated in Figure 8. The anvil 44 is movable, by air cylinder actuator means to be described later, within the transport zone 40 in a horizontal plane towards and away from the weld head 52. When the cup 28 is in the raised position as illustrated in
Figures 7 and 8, the anvil 44 can be moved towards the weld head 52 to a position spaced away from the weld head gripping surface 54 where a portion of the anvil 44 contacts the cup 28 at abutment surface 56 and remains biased thereagainst.In this position there is sufficient clearance between the weld head gripping surface 54 and the polyurethane pad 48 to allow the length of strap 36 and the overlapping free end 38 to lie therebetween. When the cup 28 is lowered below the surface of shoulder 26, the anvil 44, being biased towards the weld head 52, moves toward the weld head 52 to bring the polyurethane pad 48 into contact with the length of strap 36 lying therebetween to restrain the overlapping strap free end 38 from movement.
As illustrated in Figure 6, the movement of anvil slide 46 is effected by a pneumatic cylinder actuator 120 which acts through a piston rod 122 connected on one end to the cylinder piston (not shown) and on the other end to the slide 46.
Referring now to Figure 7, the detailed formation of the primary strap loop will now be described. First, the free end 38 of a length of strap 36 is fed forward in the strap transport zone 40 between the strap transport guideways 42 and through aperture 34 of cup 28. The strap free end 38 is guided by polyurethane pad 48 and a portion of anvil 44 as it enters the interior of cup 28. The strap free end 38 is guided by the interior surface of cup 28 in a closed arcuate path to form an initial primary loop with the free end 38 overlapping a portion of the loop between the anvil 44 and the weld head 52. By suitable control means as will hereinafter be described, the feeding of the strap length 36 is terminated when the primary loop has been formed essentially as illustrated in Figure 7.
It is desirable during the primary loop formation stage, as well as during subsequent tensioning and welding stages, to maintain the overlapped portion of the strap length 36 and the free end 38 in the elevation of the strap transport zone 40. To this end, appropriate upper and lower guides are provided. A flange 60 is provided in the lower end of the weld head 52 for keeping the overlapped portion of the strap length 36 and strap free end 38 from running below weld head 52. A slide cover 62 is secured to, and movable with, slide 46 above the strap transport zone 40 to prevent the overlapped portion of the length of strap 36 and the strap free end 38 from riding above the weld head 52 and the polyurethane pad 48.
After the primary strap loop has been formed, the cup 28 must be lowered from its elevated position in the strap transport zone 40 to a second position below the strap transport zone 40. As the cup is lowered, the formed primary strap loop does not ride in the cup 28 to the lowered position, but rather slides out of the cup and remains at the upper position. This is due to the combination of the relatively small diameter of the cup 28, the stiffness of the strap, the low coefficient of friction between the strap and the cup, and the fact that the strap length 36 is supported on its bottom edge in the strap transport zone guides 42.
Consequently, when the cup 28 is lowered, the formed primary strap loop is maintained at the elevation of the strap transport zone 40 above the surface of the shoulder 26.
After the cup 38 is completely lowered away from the primary strap loop, any tendency of the loop to uncoil or unwind is resisted. Owing to the proximity of the weld head 52 and the polyurethane pad 48 on opposite sides of the overlapping strap portions of the loop, the loop is not able to unwind and is thus maintained in a loop.
A combination of mechanism is used to expand the formed primary strap loop to a larger loop of predetermined diameter.
With the cup 28 in the lowered position as illustrated in Figures 9 and 10, slide cover 62, anvil 44 and polyurethane pad 48 move closer toward weld head 52 by slide 46 under the influence of a biasing means described hereinafter. Anvil 44 is moved forward to force polyurethane pad 48 against the strap loop in a region where the strap free end 38 overlaps the overlapped portion of the loop formed by the length of strap 36. The polyurethane pad 48 then contacts a side of the length of strap 36 to force both the length of strap 36 and the overlapping strap free end 38 against weld head 52. By means that will be described later, the polyurethane pad 48 is maintained against the loop with a relatively small amount of force such that the strap free end
38 is restrained from moving by the weld head roughened peripheral gripping surface
54.However, the force is low enough (about
2 pounds) to permit the overlapped length of strap 36 to slide forward between the strap free end 38 and the smooth-surfaced polyurethane pad 48 when the length of
strap 36 is fed to expand the loop.
Preferably, during the expansion of the
primary strap loop, the surface of shoulder
26 provides the support for the bottom of
the strap loop as it expands.
Though the surface 54 of the weld head
52 is preferably roughened (especially on
account of its gripping function during the subsequent friction fusion process to be described below), it need not necessarily be so. Insofar as the head 52 functions during the loop expansion process, the head 52 need only have some sufficiently relatively greater coefficient of sliding friction than the pad 48. Alternatively, the pad 48 could be replaced by a cylindrical roller mechanism which would rotate about an axis parallel to the weld head shaft 53 to allow feeding and tensioning of the strap. The roller could be locked against rotation, if necessary, during the subsequent friction fusion process (to be described below).
After the loop has been expanded to the predetermined larger diameter and placed around the package 24 as shown in Figures 4 and 11, the loop 30 is tensioned and tightened about the package 24. The details of the mechanism for applying tension to the strap will be discussed later. It is first necessary to describe the action of the polyurethane pad 48 and the weld head 52 during the tensioning process. At the beginning of the tensioning phase, the strap loop 30 is disposed about the package 24 as illustrated in Figure 11. At this time, the cup 28 is in the lowered position below the surface of the shoulder 26. The strap loop 30 is tensioned about the package 24 to form a tight loop as illustrated in Figure 5.During tensioning, a tensile force is transmitted along the length of the strap 36 which is considerably higher than the small compressive force which exists in the portion of the strap between the strap feed mechanism and the polyurethane pad 48 as the strap is being fed to form the expanded loop. Consequently, during tensioning the higher force occurring in the strap would tend to pull the strap free end 38 from its restrained engagement against the weld head 52. To overcome this possibility, the polyurethane pad 48 is forced against the strap and weld head 52 during tensioning with a large force to cause strap free end 38 to remain restrained against the weld head 52. In the preferred embodiment of the present invention, it has been found that a force of about 30 to 40 pounds is sufficient to maintain the strap free end 38 between the polyurethane pad 48 and the weld head 52 as the overlapped length of strap 36 is tensioned. Typically, the strap loop is tensioned to about 10 to 15 pounds.
During the tensioning process, as illustrated in Figure 11, the upper edge of the strap, in the region of the strap overlap between the polyurethane pad 48 and the weld head 52, is nearer the bottom surface of the package 24 than is the bottom edge of the strap. Preferably, the strap loop 30 is maintained in the 90" twist orientation illustrated in Figure 11 such that both the upper and lower edges of the strap in the region between the polyurethane pad 48 and the weld head 52 are located in the plane of the loop as the loop is tensioned about the package 24. Although the sliding surface of polyurethane pad 48 and the opposed gripping surface 54 of weld head 52 are shown in Figure 11 as being perpendicular to the slide cover 62 and to the bottom of the package 24, such orientation is not necessarily required.The surfaces on both the polyurethane pad 48 and the weld head 52 could be angled with respect to the plane of the strap loop 30 about the package 24.
During the tensioning process, slide cover 62 lies between the bottom surface of package 24 and the strap loop 30. With some types of soft packages and at certain high tension levels, the slide cover 62 serves to prevent the loop 30 from pulling out of engagement from between the polyurethane pad 48 and the weld head 52. After tensioning, when the slide cover 62 is removed from between the package 24 and the loop 30 as will be described hereinafter, a certain amount of slack is thus present in the tightened loop. However, due to the elasticity of the plastic strap and due to the compressibility of the package 24, a tight loop is nevertheless achieved when the slide cover 62 is removed.Additionally, the slide cover 62 can be made relatively thin (in the vertical direction as viewed in Figure 11) and can be made relatively narrow with respect to the package width (as viewed in the horizontal direction in Figure 2) to reduce the amount of slack formation.
Further, with certain types of packages (such as those having rather rigid and incompressible surfaces), and with low loop tensions, the slide cover 62 can be eliminated altogether. This is because, at low tension levels, the strap loop has less of a tendency to be pulled out of engagement from between the polyurethane pad 48 and the weld head 52. Further, the relative incompressibility of the package 24 would prevent the strap loop 30 from sinking into the package and pulling away from the polyurethane pad 48 and the weld head 52.
Although the tensioning process is illustrated in Figure 11 as occurring with the overlapped portions of the strap loop oriented in a plane parallel to the plane of the strap loop about the package, the loop 30 could be tensioned in other orientations.
With very large packages and with very small weld head diameters, it would be possible to insert the package into the expanded loop when the loop is in the horizontal position as shown in Figure 3.
Then the loop could be tensioned in that horizontal configuration. Though the diameter of the weld head 52 would create some amount of slack in the tensioned loop, with large compressible packages such slack would be negligible and would not affect the integrity of the tightened loop. If the strap loop was to be tensioned about the package in the horizontal direction, then the upper surface of shoulder 26 would advantageously be located at a lower elevation with respect to the weld head 52 and the strap transport zone 40 than is shown in
Figure 6. The increased depth would accommodate placement and insertion of large packages within the horizontally
oriented loop.Of course, if the loop were to be tensioned in the horizontal direction, provisions could also be made for automatically withdrawing the weld head 52 from between the strap and the package after the tensioning process has been completed.
Strap Feed and Tensioning Mechanism
The strap is both fed and tensioned by one traction wheel assembly. A traction wheel 68 and adjacent idler wheel 70 are mounted for horizontal rotation in the strap transport zone 40 as illustrated in Figure 6.
The idler wheel 70 is preferably springbiased against the traction wheel 68. The strap 36 is threaded in the guideways 42 and between the traction and idler wheels 68 and 70, respectively. Traction wheel 68 is mounted on a shaft 72 and is rotatably driveable in either direction by an electric motor 76 which is connected to the shaft by a conventional drive belt 78. The motor can drive the traction wheel 68 first clockwise (as viewed in Figure 6) to feed the strap to form the loop and then counterclockwise (as viewed in Figure 6) to tension the loop.
A bulk supply of strap is preferably wound on a conventional self-supporting spool (not shown) which can be placed near the apparatus 20 and which rotates to deliver strap in response to the feed force of the traction wheel pulling on the strap.
On the end of the shaft 72 opposite the traction wheel is an incremental rotation control unit 74 which signals the cup solenoid actuator 66 to lower cup 28 after the primary strap loop has been formed.
Control unit 74 is of a conventional type which incorporates an electrically actuated clutch. When the clutch is actuated, a cam member rotates with the shaft 72 for one revolution, after which the clutch disengages the cam member from the shaft 72 and locks the cam against further rotation. The cup solenoid actuator 66 is de-energized to lower the cup 28 by a limit switch provided in the control unit 74 and which is actuated by the rotating cam after one rotation of the cam. In order that a single rotation of the traction wheel 68 causes the primary strap loop to be formed within the cup 28 with the strap free end overlapping a portion of the loop, the diameter of the traction wheel 68 is larger than the diameter of the cup 28.
After formation of the primary strap loop in the cup 28, cup 28 is lowered away from the loop allowing the traction wheel 68 to expand the loop to a predetermined size.
Actually, since the cup 28 is lowered quite rapidly by the solenoid actuator 66, it is not necessary to terminate the strap feeding process while the cup 28 is being lowered.
Thus, the strap is continuously fed without interruption until the desired expanded loop diameter is achieved.
The tensioning process is terminated when the desired level of loop tension is sensed. A tension sensing assembly is provided in the strap transport zone 40 and is illustrated in Figures 7, 9 and 12. A tension sensing wheel 83 is rotatably mounted about shaft 84 on arm 86. Arm 86 is pivotally mounted about shaft 88 to frame plate 90. Spring 92 is secured on one end to arm 86 and on the other end to an anchor 94 in the frame. The spring 92 functions to pivot arm 86 counterclockwise about shaft 88 to bias the tension sensing wheel 83 against the side wall region 95 in strap transport zone guideway 42. The tension of spring 92 is adjustable and can be set to permit a given amount of spring extension at a predetermined strap tension level.When the strap is under little or no tension, the strap length 36 is forced by the wheel against the side wall region 95 in guideway 42 as illustrated in Figures 7 and 9. As the tension increases, the strap length 36 forces wheel 83 out from the wall region 95 because the tensioned strap 36 is drawn into a straight line between point 96 and point 97 in guideway 42. The present spring tension is set so that the strap length 36 is prevented from forming a straight line between points 96 and 97 until the strap tension reaches the predetermined level. When the predetermined strap level is reached, the tension sensing wheel 83 is forced by the straight portion of strap length 36 to the position illustrated in Figure 12 where the arm 86 bears against contact arm 98 of a limit switch 100.Actuation of the limit switch 100 in this manner opens the circuit of motor 76 to terminate the tensioning.
Strap Loop Friction Fusion Mechanism
The method and mechanism for connecting the strap free end 38 to the overlapped portion of the length of strap 36 will now be described. If a plastics or plasticscoated metal strap is used, a welded or friction-fused joint can be achieved by heating the overlapped region of the loop.
In the preferred embodiment, fusion heat is generated by rapidly moving the strap free end 38 against the overlapped portion
of the length of strap 36 to generate heat by
friction and effect interface melting there
between. More particularly, this is
accomplished by oscillating the weld
head 52 with a relatively small angular
rotation at a suffici~ently high
frequency. Weld head 52 is rotatably
oscillated about the shaft 53 so that
the peripheral gripping surface 54, being engaged with a side of the strap free end 38, causes the strap free end 38 to be
moved back and forth with respect to the stationary overlapped portion of the length
of strap 36.Typically, the frequency of oscillation is between about 50 and 100 hertz, the total amplitude of circumferential rotation of the gripping surface 54 is about 0.15 inch, and the oscillation period
lasts from between .75 to 1.0 second. In order to ensure an adequate weld, the polyurethane pad 48 is pressed against the
overlapped portion of the length of strap 36 with a higher force than is used during the tensioning process. Typically, a force of about 100 pounds is impressed against the
strap during the friction-fusion process.
The weld head 52 is driven in the oscillatory mode by motor 80 and a connected oscillating drive transmission 82. The motor 80, transmission 82, and control means (not shown) are well known and commercially used in present friction fusion strapping machines. A description of such mechanisms can be found in the U.S. Patent to Ericsson, No. 3,586,572.
The friction fusion joint could be formed with a different type of anvil apparatus than illustrated. For example, pad 48 could be replaced with a cylindrical roller mounted for rotation about an axis parallel to the weld head shaft 53 and having a roughened gripping surface. The rotation of the roller would allow for the feeding and tensioning of the strap. Then after the loop had been tensioned, the roller could be oscillated vertically (along its axis) by a suitable mechanism to vibrate the strap 36 against the free end 38 to create a fused joint.
After the friction-fusion joint has been completed, the cup 28 is still maintained in the lowered position below the surface of shoulder 26 while the weld head 52 and the polyurethane pad 48 are maintained in compressive engagement on the strap loop so that the strap loop can be severed from a standing portion of the strap length 36 as will be next described in detail.
With metal strap, other types of joints could be created through the use of additional, conventional joint forming mechanisms (not illustrated). Such other joints may be, for example, of the independent seal type or of the interlocking slit type. Descriptions of such seals and sealing mechanisms can be found in the
U.S. patents to Crosby, No. 2,710,435; to
Crosby et al., No. 2,801,558; and to Beach,
No. 3,303,541.
Strap Severing Mechanism
After the loop has been connected by friction-fusion weld, the standing portion of the strap is severed from the loop by cutter 102 as best illustrated in Figures 6 and 9.
The cutter blade 102 is fixed in a slide block 104 which is slidably mounted for movement toward and away from strap 37 as best shown in Figure 9. A cutter block 106 is provided to guide strap 36 to prevent the strap from deflecting away from the cutter blade 102 at it is moved forward to sever the strap.
The cutter blade 102 is moved through a linkage by a pneumatic cylinder actuator 109. As illustrated in Figure 6, link 108 is pivotally mounted about shaft 110 and is pivotally connected to arm 111 on one end and to slide block 104 on the other end.
Arm 111 is connected to the cutter air cylinder actuator 109 through a conventional cylinder piston rod (not
shown). Pressurization of the cylinder
actuator 109 forces the cylinder piston
rod and arm 111 toward the cylinder
actuator to pivot link 108 counterclockwise (as viewed in Figure 6) about shaft 110 thereby moving the cutter blade 102 forward to sever the strap. The cylinder actuator is equipped with an internal spring to return the piston rod to the extended position (and hence the cutter blade 102 to the retracted position) upon release of
cylinder air pressure.
After the strap has been severed, the anvil slide 46 is moved away from the weld head 52 to retract the anvil 44 and the slide cover 62.
With the anvil 44 retracted, the fused portion of the strap loop adjacent the weld head 52 is relieved from its 900 twist configuration with respect to the balance of the loop and lies flat along the bottom surface of the package. Since the slide cover 62 is also retracted, the tensioned strap loop tightens further, under influence of its elasticity, to fit tight around a portion of the surface 6f the package that was previously in contact with the slide cover 62. The strapped package can then be removed from the apparatus.
Pneumatic Actuation System
As previously described, the movement
of cutter blade 102 and anvil slide 46 is effected by pneumatic cylinder actuators
109 and 120, respectively. The actuators are controlled by pneumatic actuation system illustrated schematically in Figure 13.
The system is comprised of a supply manifold 124 supplying 90 psi air to three pressure regulating valves 126, 128, and 130 downstream of which are three-way electrically operated solenoid valves 132, 134, and 136, respectively. The solenoid valves admit air to a distribution manifold 137 for supplying the cylinder actuators 109 and 120. A check valve 138 prevents flow from solenoid valves 132 and 134 from pressurizing the cutter cylinder actuator 109. Cylinder actuator 109 can thus be pressurized only from solenoid valve 136 through a flow control valve 139.
Pressure regulating valves 126, 128 and 130 are set to control pressure relative "low", "medium", and "high" pressure levels, respectively, for purposes to be explained hereinafter. The solenoid valves 132, 134, and 136 each have three ports (labeled A, B, and C in Figure 13). Exhaust port C is plugged in valves 134 and 136, but is unplugged to exhaust to atmosphere in valve 132. In the de-energized state, the solenoid valves are set to pass flow through ports B and C (except that port C is plugged on valves 134 and 136) and in the energized state the valves pass flow through ports A and B.
The actuation of the anvil cylinder actuator 120 will now be considered. When the primary strap loop is first formed in cup 28, the anvil 44 is moved forward to contact abutment surface 56 as illustrated in Figure 7. With reference now to Figure 13 also, it can be seen that movement of anvil 44 to this position is accomplished by actuating air solenoid valve 132 to open ports A and B to allow a regulated low air pressure from pressure regulating valve 126 to act upon the piston in cylinder actuator 120 and force anvil 44 against the cup abutment surface 56 with about 2 pounds of force. The 2 pounds of force is a nominal amount that is used to ensure that the anvil 44 is abutting the cup 28 to provide proper alignment and guiding of the strap free end 38 as it is fed forward into aperture 34 and between polyurethane pad 48 and weld head 52.
After the primary strap loop has been formed in cup 28, cup 28 is lowered to below the surface of shoulder 26. As cup 28 is being lowered, cup abutment surface 56 slides vertically downward along the front of anvil 44. As soon as cup 28 has cleared the bottom of anvil 44, anvil 44 is urged forward against the strap and weld head 52 by the 2 pounds of force that is still
maintained by the anvil air cylinder
actuator 120. The loop is expanded to a
larger diameter with the anvil 44
maintaining the 2 pounds of force on the
strap. Next, after the expanded loop has
been located around the package, a higher
pressure must be applied to the overlapped portions to prevent the strap free end 38 from being drawn out of engagement with weld head 52, during the tensioning step.
Thus, at this point, solenoid valve 134 is energized to open port A to provide medium pressure air to anvil air cylinder actuator 120 to cause the anvil 44 to exert about 30 to 40 pounds on the strap against the weld head 52. After the tensioning process has been completed, the solenoid valve 134 is de-energized to close port A.
However, since port C is plugged, the cylinder actuator 120 remains pressurized and the anvil 44 remains pressed against the strap loop.
During the next, joint-forming step, the strap must be held with even more force against the weld head 52 as the weld head 52 is oscillated at high frequency to form the friction-fused joint. To accomplish this, the solenoid valve 136 is energized to open port
A to admit higher pressure air to anvil air cylinder actuator 120 to force anvil 44 against the strap and weld head 52 with about 100 pounds of force.
The cutter air cylinder actuator 109 is supplied with high pressure air from high pressure regulator 130 only through solenoid air valve 136 since check valve 138 prevents air from low and medium pressure regulators 126 and 128 from flowing into the cutter air cylinder actuator 109. Note that solenoid air valve 136 admits air to both the anvil air cylinder actuator 120 and the cutter air cylinder actuator 109 simultaneously. However, the action of the cutter air cylinder actuator 109 is delayed about one-half second while the high pressure air is admitted to the anvil air cylinder actuator 120 to hold the strap until completion of the friction-fusion welding.
After the weld is completed, the cutter air cylinder actuator 109 is permitted to move the cutter blade to sever the strap. This is accomplished by the flow control valve 139 in the air supply line to cutter air cylinder actuator 109. The flow control valve 139 provides a controlled slow rate of pressurization and, acting through the cutter air cylinder actuator 109, moves the cutter blade 102 forward so that it reaches the strap length 36 (Figure 12) just as the weld sequence is terminated. After the cutter blade 102 has severed the strap and reached the full extent of its travel, solenoid valve 136 is deenergized to close port B and solenoid valve 132 is de-energized to close port A and open port C to exhaust air pressure from both the cutter air cylinder actuator 109 and the anvil air cylinder actuator 120.The internal spring return mechanisms in each of the cylinders causes anvil 44 and cutter blade 102 to return to the fully retracted positions.
Electrical Control System
In order that the strap loop be properly formed, expanded, tensioned, frictionfused, and severed, the sequence of operation must be appropriately controlled.
The operation of the apparatus 20 of the present invention can be made to operate automatically and rapidly by means of a suitable electrical control system. A suitable control system is illustrated in the simplified control block diagram of Figure 14. In the diagram, the necessary interlocking latching relays and switches are omitted. It is assumed that apparatus is at the beginning of a strapping cycle in a power-on ready mode with the strap threaded in the guideways 42 up to the cutter block 106.
The cup 28 is in the raised position by the energized solenoid actuator 66. The solenoid valve 132 is energized to pressurize the anvil cylinder actuator 120 to move the anvil 44 against the cup 28 (as shown in
Figure 7) with about 2 pounds of force. The field coils of the traction wheel motor 76 are energized for motor operation in the direction to feed the strap into the cup 28.
A strap feed switch 143 is provided and is preferably a foot-operated momentary contact type. When depressed, the feed switch 143 energizes the armature of the traction wheel motor 76 to turn the motor in the direction to feed the strap. The feed switch 143 also actuates the incremental control unit 74 associated with the traction wheel shaft 72 to lower the cup 28 after the primary strap loop is formed. As the cup 28 is lowered, the motor is still rotating so that the strap continues feeding. As the cup reaches the lower position beneath the surface of the shoulder 26, the anvil 44 is urged against the strap to force the strap against the weld head 52 under the influence of the low pressure air being supplied to anvil cylinder actuator through the solenoid valve 132. The anvil 44 bears against the strap and the weld head 52 with about 2 pounds of force as the loop continues to expand. Release of the feed switch 143 stops the motor 76 and stops the strap feed. Repressing of the feed switch 143 continues the feeding of strap and expansion of the loop.
When the loop is of sufficient size, the operator releases the feed switch 143.
Alternatively, if identically sized packages are being strapped on a production line basis the feeding of the strap and expansion of the loop could be controlled by a timer.
In any case the operator next lifts the loop and places it over the package as illustrated in Figure 4.
A strap tension switch 148 is provided to reverse the motor 76 to tension the loop about the package. The tension switch 148 is preferably a foot-operated momentary contact type. The tension switch 148 is also connected to actuate the solenoid valve 134 to admit medium pressure air to the anvil air cylinder actuator 120 to move the anvil 44 against the strap loop and the weld head 52 with about 40 pounds of force. This holds the strap free end 38 against the weld head 52 while the overlapping portion of the strap loop is allowed to slide against the anvil 44 as the loop is tensioned.
When the predetermined strap loop tension level (about 10 to 15 pounds on small packages) is reached, the tension sensing switch 100 is actuated to stop the motor 76 and reverse the motor field coils for the next cycle operation in the feed direction. The tension sensing switch 100 also deenergizes the medium pressure solenoid valve 134 and energizes the solenoid valve 136 supplying the high pressure to the anvil cylinder actuator 120 and the cutter air cylinder actuator 109.
This causes 1) the anvil actuator 120 to provide the high clamping force (approximately 100 pounds) required to hold the overlapped strap portion of the loop while the friction-fusion joint is made and 2) the cutter actuator 109 to move the cutter blade 102 to sever the strap after conclusion of the joint weld. The tensionsensing switch also actuates the weld motor 80 and the timer 152 which de-energizes the weld motor after the weld has been completed (about 3/4 of a second to 1 second).The timer 152 also de-energizes the solenoid valve 136 thereby blocking the high pressure air supply and de-energizes the solenoid valve 132 to exhaust to atmosphere so that both the cutter air cylinder actuator 109 and the anvil air cylinder actuator 120 are returned by their internal spring mechanisms to the positions wherein the cutter blade 120 and the anvil 44 are in the fully retracted positions.
To set the apparatus for the next cycle, timer 152 also energizes two additional timers, 154 and 156. Upon timing out, timer 154 energizes solenoid actuator 66 to raise cup 28 and timer 156 energizes solenoid valve 132 to move the anvil 44 forward to abut the cup 28. Timer 154 is set to provide a certain time period for removal of the strapped package before raising the cup 28.
Timer 156 is set to provide a period longer than timer 154 to assure that the cup 28 will be in the raised position when the anvil 44 is moved forward.
Alternative Forms of Apparatus
Formation of the strap loop with the apparatus illustrated in Figures 1 to 14 and heretofore described involves the use of a movable, circular guide (cup 28). The strap loop formation step of the method of the present invention can also be performed in a number of other ways.
In each of the embodiments, certain mechanisms, though not always illustrated, will be understood, to exist and function analogously to those mechanisms heretofore described for the embodiment illustrated in Figures 1-14. Examples of such mechanisms are the strap transport zone guides 42, the traction wheel 68, the idler wheel 70, and the cutter blade 71, as well as the necessary drive means, controls, and support structures. In all of the alternative embodiments an anvil and associated slide mechanism are provided (as schematically illustrated and designated 144, and 146, 244 and 246, 344 and 346, 444 and 446, 544 and 546, and 644 and 646 in
Figures 15-17; 1819 and 20; 21; 22-25; and 26-28, respectively).The anvil and slide in these alternative embodiments are understood to perform the same functions as the anvil 44 and slide 46 of the embodiment illustrated in Figures 1 to 14 and as heretofore described.
Figures f5 to 17 schematically illustrate another way of performing the step of forming a primary strap loop and expanding the strap loop to a larger diameter by use of an alternative, or second embodiment of a strap loop forming mechanism. The mechanism illustrated would be used in a strapping apparatus, such as the strapping apparatus 20 illustrated in Figures 1 to 14, and would be located in the strap loop forming area of the apparatus (the strap loop forming area of apparatus 20 is illustrated in Figures 8-9). Specifically, in place of the weld head 52, a wheel 112 is provided.
Surrounding the wheel 112, and spaced from it, are a number of pivotable guide plates 114 which are spring-biased to a vertical position and provide a strap guide on the loop exterior side of the length of strap 36. Figure 17 shows one of the pivotable guide plates 114 biased to the vertical direction by an appropriate spring mechanism 116 and further shows a portion of the strap 36 adjacent one side of the plate 114 as the strap is guided thereagainst. The guide plates can be of varying size and number. In the embodiment illustrated, there are four guide plates forming a roughly polygonal shape, or more specifically, 4/6 of a hexagon. A fifth side of the hexagon is formed by a stationary guide plate 115 and a sixth side of the hexagon is formed by a smooth-surfaced pad or anvil 144 which is movable towards and away from the wheel 112 by an appropriate slide mechanism 146.
During the stage of initial loop formation, the strap free end 38 is fed into the strap loop forming area between the wheel 112 and the anvil 144 and is guided by the guide plates 114 and 115 to form a loop. After the strap has been fed in a circle slightly greater than 2K radians to form the loop with a portion overlapped by the strap free end 38, the anvil 144 is moved closer towards the wheel 112 to apply a predetermined amount of force against the overlapped portions of the strap loop between the anvil and the wheel so that the overlapped portions are lightly held together. The wheel 112 preferably has a rough peripheral surface for contacting a side of the strap free end 38. The strap is continued to be fed against the guide plates 114 and the strap free end 38 is restrained, against the wheel 112, from further movement.With an appropriate choice of the strength of the spring 116 used to bias the guide plates 114 to the vertical position, the plates 114 will be forced to pivot outwardly and down by the force of the expanding strap loop to assume the position shown in dashed lines in
Figure 17. This will permit the strap loop to expand to a larger size 30 as illustrated in
Figure 16.
When the loop has been expanded to the proper predetermined size, the strap feeding process is terminated. Next, a package can be located over a portion of the loop and the loop can be twisted 900 (out of the plane of Figures 15 and 16) to place it around the package for subsequent tensioning in the manner previously described for the embodiment illustrated in
Figure 4. The wheel 112 may be relatively small, say between 1 and 2 inches in diameter, or may be much larger.
Regardless, if plastics, strap or plasticscoated metal strap is used, the wheel 112 can be oscillated with a small angular rotation at a sufficiently high frequency to form a friction-fused joint in the manner analogous to that described for the preferred embodiment of the weld head 52 previously described with reference to
Figures 1 to 14.
Severance of the strap loop from the trailing length of strap can be effected by a suitable strap severing mechanism, not illustrated, such as the cutter blade 71 previously described for the preferred embodiment and illustrated in Figure 7.
A third embodiment of the strap loop forming mechanism of an apparatus for strapping a package according to the method of the present invention is illustrated in Figure 18 and is similar to the strap loop forming mechanism of the first embodiment illustrated in Figures 1 to 14. A cup 228 is provided to receive the length of strap 36 and to guide the strap free end 38 on the inner periphery thereof to form a primary strap loop. A weld head 252 is provided inside the cup 228 and has a lower guide flange 260 to maintain the plane of strap 36 at the proper elevation within the cup 228.. An anvil 244 and movable slide mechanism 246 are illustrated schematically and function in a manner analogous to the anvil 44 and movable slide mechanism 46 of the first embodiment illustrated in Figures 1 to 14.
However, in the case of embodiment illustrated in Figure 18, the cup 228 is hinged, or pivotally mounted, on pin 262 for movement to a tilted position (shown in dashed lines in Figure 18) after the primary strap loop has been formed. This provides clearance around the periphery of the primary strap loop to allow subsequent expansion thereof. The cup 228 is moved to the tilted position by any suitable drive means or actuator means (not illustrated).
With the strap having an appropriate combination of thickness, width and flexibility, any movement or tilting of the cup is not even necessarily required. That is, the cup, with a properly shaped wall, could remain stationary after formation of the primary strap loop. Then continued feeding of the strap into the cup will cause the strap to buckle out of the cup so that it can expand to a larger size.
Figures 19 and 20 illustrate a fourth embodiment of the strap loop forming mechanism of an apparatus for strapping a package according to the method of the present invention. In this embodiment a strap loop is formed in a plane perpendicular to a package support surface 322 on a strapping apparatus. Initially, the package 324 is placed upon the package support surface 322 adjacent the loop forming area. A length of strap 36 is then fed between, and guided by, two axially aligned adjacent guide rings 326 and 328.
The guide rings 326 and 328 are pivotally mounted on pins 330 and 332 respectively, which are mounted in recessed channels 334 and 336, respectively. The guide rings 326 and 328 can thus be rotated 90 degrees to a position below, and parallel to, the package support surface 322. To this end, guide ring cavities 338 and 340 are provided to receive the guide rings 326 and 328, respectively.
The strap 36 can be fed into a slot (not shown) between the guide rings 326 and 328 by an appropriate traction wheel mechanism.
In a manner analogous to that described for the embodiment illustrated in Figures 1 to 14, a plastics strap or plastics coated metal strap can be formed into a primary strap loop and then gripped between a weld head 352 and an anvil 344 for the subsequent loop expansion, loop tensioning, and friction fusion steps. In Figure 19, the anvil 344 is schematically illustrated as being movable towards and away from the strap 36 and weld head 352 by slide mechanism 346 and the weld head 352 is shown mounted on shaft 353 and driven by an appropriate drive means or motor 355.
By appropriate control means, the length of strap 36 is fed between the guide rings 326 and 328 until a primary strap loop is formed with the strap free end 38 overlapping a portion of the loop. At this point, the anvil 344 is urged against the overlapping strap portions and the guide rings are moved, by a suitable means, to the horizontal position below the package support surface 322 to provide clearance around the periphery of the loop. The loop is then expanded by continued feeding of the length of strap until the desired larger diameter is reached. The package is then moved into the loop and the loop is subsequently tightened, tensioned, and severed in a manner similar to that described for the embodiment illustrated in Figures 1 to 14.
However, with the apparatus illustrated in
Figures 19 and 20, the loop does not have to be twisted 90 degrees to be placed around the package since the loop is formed initially in the plane perpendicular to the package support surface 322 and since the package 324 can be placed therein without requiring the loop to be twisted in any manner.
When the loop is tensioned about the package 324, the small weld head 352 is necessarily located between the package and the strap loop which causes the loop to be slightly larger than the periphery of the package. After the loop has been tensioned, friction-fused (or the overlapped ends otherwise suitably joined), and severed from the trailing length of strap, the weld head 352 must be removed from between the package and the strap loop. This can be accomplished by moving the combined assembly of weld head 352, shaft 353 and motor 355 away from the package (in a direction to the right as viewed in Figure 19) by appropriate mechanisms (which are not illustrated). With very large packages and with very small weld head diameters, the creation of a slightly larger diameter loop about the package resulting from the weld head being disposed between the loop and the package is negligible.Further, if the large package was slightly resilient, the package would expand slightly to a larger diameter (and the strap itself would contract to a slightly smaller diameter) to effect a tight loop about the package.
Figure 21 illustrates a fifth way of performing the step of forming a primary strap loop and expanding the strap loop to a larger diameter. The mechanism illustrated in Figure 21 would be used in a strapping apparatus, such as the strapping apparatus 20 illustrated in Figures 1 to 14, and would be located in the strap loop forming area of the apparatus (the strap loop forming area of apparatus 20 is illustrated in Figures 8-10). Specifically, in place of the guide cup 28 and the weld head 52 in apparatus 20, there is provided a flexible guide band 428 and a strap free end stop block 452, respectively. Opposite the stop block 452 is an anvil 444 which is movable toward and away from the stop block 452 by a slide mechanism 446. The length of strap 36 is introduced to the inner periphery of the flexible guide band 428 between the anvil 444 and stop block 452.The strap free end 38 is guided in a circle by the inner periphery of the flexible guide band 428, and after traveling in a circle for slightly greater than 27r radians, impinges upon the stop block 452 thus forming a primary strap loop with a portion of the loop overlapped by the strap free end 38.
The flexible guide band 428 can be of any suitable flexible material such as poly
ethylene or rubber, or even thin metal. In the loop forming position, the band 428 extends from an anchor point 454 in a circular locus with a free end 455 in abutment with the anvil 444. On the free end 455 of the flexible guide band is a guide pin or prong 457 which projects from the bottoin of the flexible guide band 428 and into an arcuate slot or track 458 in the shoulder surface 26 of the apparatus. As illustrated in Figure 21, the shape of the track 458 is an involute of the circle formed by the flexible guide band 428 when the band is in the position illustrated in Figure 21 for forming the primary strap loop. After the primary strap loop has been formed, the free end 455 of the band 428 is moved in the locus of the track 458.To this end, by appropriate drive means not illustrated, the pin 457 on the free end 455 of the band 428 is driven in the track 458 to point B so that the flexible guide band 428 assumes a substantially straight line orientation illustrated by dashed lines and labeled 428'.
In the straight line orientation, the flexible guide band 428' is thus spaced away from the formed primary strap loop to provide
clearance about the periphery of the loop.
Next, the anvil 444 is moved closer towards the loop to apply a relatively small force against the overlapped portions of the strap loop to restrain the strap free end 38 from disengaging from the stop block 452.
Subsequently, by appropriate feed drive means, the length of strap 36 can continue to be fed to expand the loop to the desired larger diameter. A package can then be
placed over a portion of the loop and the loop can be twisted about the package. The
loop can then be tensioned and tightened
about the package in a manner similar to that previously described for the embodiment illustrated in Figures 1 to 14.
The overlapping portions of the strap loop can be joined by appropriate means, such as by a friction-fusion, application of an independent seal, or formation of an interlocking slit joint. Creation of a frictionfusing joint would require the stop block 452 to be oscillated or vibrated sufficiently rapidly to generate heat by friction and effect interface melting therebetween.
Mechanisms for applying an independent seal or for forming an interlocking slit joint to metal strap would be of a conventional nature and associated with anvil 444 and stop block 452 as may be necessary or desired.
Figures 22 to 25 illustrate another way of performing the step for forming a primary strap loop and expanding the strap loop to a larger diameter by use of a sixth embodiment of a strap loop forming mechanism. The mechanism illustrated would be used in a strapping apparatus, such as the strapping apparatus 20 illustrated in Figures 1 to 14 and previously described. The strap loop forming mechanism would be located in the strap loop forming area of the apparatus (the strap loop forming area of apparatus 20 is illustrated in Figures 8-10).
In this sixth embodiment, the strap guide is not in the same form as in the previous embodiments. Instead. the strap guide is formed as a wheel 552 (in place of the weld head 52 of the first embodiment illustrated in Figures 8-10) which has a slot 554 for receiving the strap free end 38 of a length of strap 36. As the strap is fed by appropriate traction wheel feed means (not illustrated), the strap free end 38 enters the slot 554, abuts the end of the slot in the wheel 552 and the wheel is caused by this to rotate (counterclockwise as viewed in Figures 22 to 24). The length of strap 36 is fed until the wheel 552 has rotated slightly greater than 27r radians so that a primary strap loop is formed with a portion of the loop overlapped by the free end 38.After the primary strap loop has been formed, the wheel 552 can be locked against further rotation while the strap length 36 is continued to be fed.
An anvil 544 is provided adjacent the wheel 552 and is movable toward and away from the wheel by a slide mechanism 546 (schematically illustrated in Figures 22 through 25). The anvil 544 is brought into contact with the exterior side of the length of strap 36 in the area of the overlapped portion of the loop to restrain the strap against the movement away from wheel 552 at that point. With the wheel 552 prevented from rotating, the primary strap loop expands from around the periphery of the wheel 552 to form a loop 30 of any desired larger size as illustrated in Figure 24.
With a relatively small wheel 552 and a relatively large package 24, the package 24 can be inserted into the expanded loop as shown in Figure 25. By means previously described for the other embodiments, the loop can then be tensioned about the package. Subsequently, the wheel 552 could also function analogously to the weld head 52, described for the embodiment illustrated in Figures 1 to 14, by producing a friction-fused joint. Following formation of the friction-fused joint, the wheel 552 is withdrawn from between the package and the loop.
Alternatively, instead of inerting the package 24 into the expanded loop as illustrated in Figure 25, the expanded loop could be first twisted 90 degrees (out of the plane of Figure 25) and the package could then be inserted into the loop above the wheel 552 and anvil 544. Such a 90 degree twist orientation of the loop is identical to that effected in the process step performed by the previously described preferred embodiment and illustrated in Figure 11.
Further, with metal strap, the overlapping portions of the strap loop could be joined by conventional independent seals or interlocking slit joints, The mechanisms for effecting such conventional joints are not illustrated in Figure 25 but could be located adjacent the wheel 552 and anvil 544 around the overlapped portion of the strap loop.
A seventh embodiment of a strap loop forming mechanism is illustrated in Figures 26 through 28. The mechanism illustrated therein would be used in a strapping apparatus, such as the strapping apparatus 20 illustrated in Figures 1 to 14, and would be located in the strap loop forming area of the apparatus (the strap loop forming area of apparatus 20 is illustrated in Figures 8-10).
A substantially circular guide 628 is provided in the surface of the apparatus for receiving the length of strap 36. In place of a weld head (such as weld head 52 illustrated in Figures 6 to 10) a stop block 652 is provided near the periphery of the circular guide 628. Opposite the stop block 652 is an anvil 644 which is movable toward and away from the stop block by a slide mechanism 646 which is schematically illustrated in the
Figures 26 and 27.
Initially, when the length of strap 36 is fed into the guide 628, the strap free end 38 passes between the stop block 652 and the anvil 644 which has been spaced away from the stop block 652 to allow passage therebetween. The strap free end 38 is then guided round the periphery of the guide 628 until it has completed a circular motion of a slightly greater than 27r radians so that a strap loop is formed with a portion of the loop being overlapped by strap free end 38 and so that the strap free end 38 has impinged upon stop block 652.
Next, the anvil 644 is moved to press against the overlapped portion of the loop with a relatively small force and the formed primary strap loop is partially lifted out of the guide 628 to allow expansion of the loop. To this end, a lift lever 650 is provided below the formed primary strap loop and the bottom of the guide 628. Lift lever 650 is pivotally mounted on pin 651 below guide 628 and is pivotally connected on one end to rod 657 which is secured to actuator 659.
Actuator 659 moves rod 657 in a vertical reciprocal motion as viewed in Figure 27 to lower and raise, respectively, the lift finger 650.
When the lift finger 650 has been raised to the position shown in Figure 27, the length of strap 36 can continue to be fed so that the loop 30 expands to any desired larger diameter as illustrated in Figure 28. A package to be strapped is then placed over the stop guide block 652 and anvil 644 and the expanded loop is twisted upwardly and around the package in a manner analogous to that for the preferred embodiment illustrated in Figure 11. Subsequently, the loop can be tensioned by a suitable traction wheel mechanism, such as that described for the preferred embodiment of the apparatus 20 illustrated in Figures 1 to 14.
After tensioning, a conventional independent seal or slit joint can be applied to the overlapped portion of the strap loop by mechanisms not illustrated. Alternatively, the stop block 652 could be rapidly oscillated or vibrated to effect a friction fusion joint on a plastics or plastics-coated metal strap. Instead of stop block 652, a weld head similar to the weld head 52 illustrated in Figures 6--10, could be provided. It is not necessary that the strap free end 38 abut a stop block or similar member upon completion of forming the primary strap loop. This is because the strap feeding can be governed by suitable automatic rotation indexing controls to terminate the feeding of the length of strap 36 after the primary strap loop has been created with the desired amount of overlap.
An eighth embodiment of a strap loop forming mechanism is illustrated in Figures 29 and 30. The mechanism illustrated therein would be used in a strapping apparatus, such as the strapping apparatus 20 illustrated in Figures 1 to 14, and would be located in the strap loop forming area of the apparatus (the strap loop forming area of apparatus 20 is illustrated in Figures 8-10). This eighth embodiment is somewhat similar to the fourth embodiment illustrated in Figures 19 and 20 and described above. In this eighth embodiment, strap guide rings 726 and 728 are pivotally mounted for movement into a cavity 738 below the package support surface 722.However, the guide rings 726 and 728 pivot about axes 727 and 729 respectively, which are perpendicular to the plane of the primary loop formation whereas the guide rings 326 and 328 of the fourth embodiment pivot about axes that are parallel to the plane of primary strap loop formation. The guide rings 726 and 728 each have identical cross sections that are substantially H-shaped. As illustrated for guide ring 728 in Figure 21, the H-shaped cross section provides an interior channel comprising sidewalls 731 and 733 and a perpendicular arcuate guide wall 735, all of which function to contain and guide the strap as the primary loop is being formed.
Unlike the fourth embodiment, the eighth embodiment does not have a weld head mounted within the central portion of the guide rings. Rather, an anvil 744 is pivotally mounted about shaft 745 and has 1) a top surface flush with the package support surface 722 and 2) a strap bearing surface opposite, and facing, a combination feed/tension/weld head wheel 752. After completion of the strapping process, the anvil 744 can be pivoted out from between the package and the strap loop by an appropriate actuator and linkage mechanism 747.
The strap 36 is threaded between the anvil 744 and feed/tension/weld head wheel 752 and is fed by rotation of the wheel 752 in a clockwise direction (as viewed in Figure 29) around the inner periphery of the vertically oriented guide rings 726 and 728 until the strap free end 38 overlaps a portion of the loop. In order for the loop to be expanded, the guide rings 726 and 728 must be pivoted about axes 727 and 729 respectively, to the lower position illustrated by dashed lines in Figure 29. This, of course, provides an unobstructed expansion area around the perimeter of the primary loop to allow expansion thereof to a predetermined larger diameter. The pivotal movement of the guide rings 726 and 728 is effected by an appropriate actuator mechanism such as an electric solenoid or air-operated cylinder actuator 765 connected to linkage members 766, 767, and 769.
As illustrated in Figure 30, wheel 752 is mounted on shaft 753 to motor 755. Motor 755 is mounted on carriage 757 which can move the motor, shaft, and wheel in a vertical direction by suitable drive means (not shown). The weld head 752 is generally cylindrical and presents a peripheral strap gripping surface. As the primary loop is being formed, and during subsequent operations, the weld head 752 is aligned with the strap 36 as illustrated in Figure 30.
After the primary loop is formed, the weld head 752 can be impressed upon the strap 36, by appropriate movement of the carriage 757 so that the strap free end 38 is maintained in frictional engagement with the anvil 744. The guide rings 726 and 728 are then pivoted to the lower position illustrated by dashed lines in Figure 29 and the strap length 36 is then continued to be fed forward, sliding against the adjacent strap free end 38, to form the expanded loop.
After the loop has been expanded, the rotation of wheel 752 is reversed to tension the loop about a package that has been inserted therein. If necessary, by appropriate upward movement of the carriage 757, a higher force can be applied to the overlapping strap lengths 36 and 38 by the wheel 752 during the tensioning process to hold the strap free end 38 in place.
After the tensioning is complete, a connection can be formed between the strap free end 38 and the overlapped strap length 36, such as by friction fusion wherein the wheel 752 is rapidly oscillated or vibrated to form a friction fusion joint on plastic or plastic-coated metal strap.
Alternatively, a friction fusion joint could be formed by rapidly vibrating the anvil 744.
In either case, the frequency and amplitude parameters relating to the formation of such a joint would be the same as has been described above under the section entitled "Strap Loop Friction Fusion Mechanism".
It is possible to form a loop that has an overlapping joint area different than those discussed so far. Figure 31 schematically illustrates such a formed primary strap loop.
A length of strap 36 is fed in a closed path to form a primary strap loop with a portion of the strap loop overlapped by the strap free end 38. Note that in this loop, the surface of the strap which is on the "inside" of the loop is maintained in an orientation such that, in the region of the overlap 812, the "inside" surfaces of the strap are in a facing relationship. The loop can be thus formed by hand or mechanically (which can include feeding the strap 36 in a closed path to form this type of loop). Following formation of the primary strap loop, the strap free end 38 is restrained from movement while the standing length of strap is fed to expand the loop to a predetermined size. Then a package can be inserted into the expanded loop, after which the loop is tensioned about the package.The strap free end 38 is then joined, by appropriate means, to the
overlapped portion of the strap length 36 to form a connection and secure the loop about the package.
During expansion of the loop, the strap free end 38 may be restrained from movement by pressing it, with a first member 814, against the overlapped portion to the strap 36 in the region of overlap 812.
A second member 816, opposite the first member and presenting relatively less sliding resistance to strap movement, is pressed against the strap 36.
Specifically, members 814 and 816 could, for example, comprise respectively, a weld head and an anvil, similar to weld head 52 and anvil 44 described for the preferred embodiment previously described and illustrated in Figures 1 to 14. It should be noted that once a loop such as illustrated in
Figure 31 has been expanded, the overlapping portions can be joined by an appropriate means, including friction fusion, formation of interlocking slits, or application of an independent seal. Most importantly, the joint can be formed, as by members 814 and 816 (or other members located adjacent thereto), without requiring that any member, or portion thereof, be placed inside the loop between the strap and the package. This has the advantage of increasing residual tension in the loop since the loop when tensioned, can be drawn tighter around the package.
Further, it should be noted that the strap does not necessarily have to be "twisted" to be placed about the package. The loop can be formed and expanded in one plane and the package then moved perpendicular to that plane and into the loop.
The method of the present invention can be advantageously used with compressible articles, bundles, or bales. In one case, preformed metal or plastics strap segments, (e.g., bale ties) could be stacked and loaded in a magazine of an appropriate apparatus for sequential feeding (one at a time) to 1) form an initial primary strap loop and 2) subsequently form an expanded loop. This could be accomplished, in part, with apparatus similar to those described above for the various illustrated embodiments.
After the loop has been expanded to a larger predetermined size, the overlapping ends of the loop could be joined by any appropriate means. Next, a compressed bale could be inserted into the strap loop and allowed to expand against the strap, thus forming a tied bale. Alternatively, the formed and joined strap loop could be removed from the strap loop forming apparatus and placed around a compressed bale which is then allowed to expand to form a tied bundle.
Instead of using separate preformed strap segments, a compressed bale could be tied with a loop formed from a continuous length of strap. Apparatus similar to that illustrated in Figures 1 to 14 could be used to form an expanded loop. But, instead of tensioning the loop about the bale, just the joint could be formed in the loop. Then the compressed bale could be placed in the loop and allowed to expand to form the tied bale.
Alternatively, the formed and joined loop could be removed from the apparatus and then placed around the bale.
With respect to binding a compressed bale as described above, it is important to note that tension need not necessarily be drawn on the expanded strap loop. With certain types of bales, it can be sufficient to allow the compressed bale to expand into binding engagement with a formed and joined strap loop.
From the foregoing, it will be observed that numerous variations and modifications may be effected to the apparatus described.
Attention is directed to our Patent
Application No. 52965/77 (Serial No.
1597347) which is directed to the formation of the joint in a portion of the loop which is twisted relative to the main part of the loop and which claims, inter alia, a method of tensioning and securing twisted strap loop located about a package, said strap loop formed between a free end of a length of strap and a standing portion of the said length of strap with a portion of the strap loop overlapped by said free end and with a region of the strap free end and adjacent overlapped portion of the loop oriented with one edge of the strap in the region maintained further from a surface of the package than the other edge, the method comprising: restraining one of the said standing portion and the said free end while pulling the other to tension the length of strap and thereby tighten the loop about the package; and joining the free end and an overlapped portion in the said region.
WHAT WE CLAIM IS:- 1. A method of forming a strap loop and securing it about a package comprising: feeding a length of strap and guiding a leading end portion thereof in an arcuate path such as to form a primary loop with the leading end portion of the said strap overlapping a part of the said length of strap, the said leading end portion being guided by strap guide means which act on the strap from only one side of the said arcuate path; restraining the said free end of the strap to prevent further movement of said free end; causing the standing length of strap to advance towards the loop to expand the loop to a predetermined diameter; effecting relative movement between the package and the expanded loop to locate the expanded loop about the said package; and either before or after effecting such relative movement between said package and expanded loop, joining said free end of the strap to an adjacent overlapped portion of the strap.
2. A method as claimed in claim 1, further comprising the step of effecting relative movement between the said primary loop and the said strap guide means to provide clearance around the periphery of the said primary loop.
3. A method as claimed in Claim 1 or
Claim 2 which includes, after effecting relative movement between the package and the expanded loop to locate the expanded loop about the package, tensioning the length of strap to tighten the loop about the package.
4. A method as claimed in Claim 1 or
Claim 2 or Claim 3 in which the step of forming a primary strap loop includes guiding a portion of one edge of the length of strap in a plane parallel to the plane of the formed primary strap loop.
5. A method as claimed in Claim 1 or
Claim 2 or Claim 3 in which the step of forming a primary strap loop includes guiding a portion of each of the two edges of the length of strap in separate planes parallel to the plane of the formed primary strap loop.
6. A method as claimed in any of the preceding claims in which the step of forming a primary strap loop includes providing a generally circular guide on the exterior periphery of the primary strap loop to guide the free end of the strap.
7. A method as claimed in Claim 6 which includes effecting relative movement between the generally circular guide and the primary strap loop to provide clearance around the periphery of the primary strap loop to permit the expansion of the loop.
8. A method as claimed in any of the preceding claims in which the primary strap loop is formed by feeding a length of strap against walls of a guide structure wherein each wall forms a side of a polygon.
9. A method as claimed in Claim 8 which includes pivoting at least one of the said walls about an edge parallel to the plane of the primary strap loop to provide clearance around a portion of the periphery of the loop to permit the expansion of the loop.
10. A method as claimed in any of Claims 1 to 5 in which the step of forming a primary strap loop includes feeding a length of strap between two axially aligned adjacent guide rings.
11. A method as claimed in Claim 10 which includes pivoting each guide ring away from the primary strap loop to provide clearance around the periphery of the loop to permit expansion of the loop to the larger size.
12. A method as claimed in any of Claims 1 to 5 in which the step of forming a primary strap loop includes feeding a length of strap on the inside of a flexible member which is maintained in an arcuate configuration.
13. A method as claimed in Claim 12
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (39)
- **WARNING** start of CLMS field may overlap end of DESC **.compressed bale could be placed in the loop and allowed to expand to form the tied bale.Alternatively, the formed and joined loop could be removed from the apparatus and then placed around the bale.With respect to binding a compressed bale as described above, it is important to note that tension need not necessarily be drawn on the expanded strap loop. With certain types of bales, it can be sufficient to allow the compressed bale to expand into binding engagement with a formed and joined strap loop.From the foregoing, it will be observed that numerous variations and modifications may be effected to the apparatus described.Attention is directed to our Patent Application No. 52965/77 (Serial No.1597347) which is directed to the formation of the joint in a portion of the loop which is twisted relative to the main part of the loop and which claims, inter alia, a method of tensioning and securing twisted strap loop located about a package, said strap loop formed between a free end of a length of strap and a standing portion of the said length of strap with a portion of the strap loop overlapped by said free end and with a region of the strap free end and adjacent overlapped portion of the loop oriented with one edge of the strap in the region maintained further from a surface of the package than the other edge, the method comprising: restraining one of the said standing portion and the said free end while pulling the other to tension the length of strap and thereby tighten the loop about the package; and joining the free end and an overlapped portion in the said region.WHAT WE CLAIM IS:- 1. A method of forming a strap loop and securing it about a package comprising: feeding a length of strap and guiding a leading end portion thereof in an arcuate path such as to form a primary loop with the leading end portion of the said strap overlapping a part of the said length of strap, the said leading end portion being guided by strap guide means which act on the strap from only one side of the said arcuate path; restraining the said free end of the strap to prevent further movement of said free end; causing the standing length of strap to advance towards the loop to expand the loop to a predetermined diameter; effecting relative movement between the package and the expanded loop to locate the expanded loop about the said package; and either before or after effecting such relative movement between said package and expanded loop, joining said free end of the strap to an adjacent overlapped portion of the strap.
- 2. A method as claimed in claim 1, further comprising the step of effecting relative movement between the said primary loop and the said strap guide means to provide clearance around the periphery of the said primary loop.
- 3. A method as claimed in Claim 1 or Claim 2 which includes, after effecting relative movement between the package and the expanded loop to locate the expanded loop about the package, tensioning the length of strap to tighten the loop about the package.
- 4. A method as claimed in Claim 1 or Claim 2 or Claim 3 in which the step of forming a primary strap loop includes guiding a portion of one edge of the length of strap in a plane parallel to the plane of the formed primary strap loop.
- 5. A method as claimed in Claim 1 or Claim 2 or Claim 3 in which the step of forming a primary strap loop includes guiding a portion of each of the two edges of the length of strap in separate planes parallel to the plane of the formed primary strap loop.
- 6. A method as claimed in any of the preceding claims in which the step of forming a primary strap loop includes providing a generally circular guide on the exterior periphery of the primary strap loop to guide the free end of the strap.
- 7. A method as claimed in Claim 6 which includes effecting relative movement between the generally circular guide and the primary strap loop to provide clearance around the periphery of the primary strap loop to permit the expansion of the loop.
- 8. A method as claimed in any of the preceding claims in which the primary strap loop is formed by feeding a length of strap against walls of a guide structure wherein each wall forms a side of a polygon.
- 9. A method as claimed in Claim 8 which includes pivoting at least one of the said walls about an edge parallel to the plane of the primary strap loop to provide clearance around a portion of the periphery of the loop to permit the expansion of the loop.
- 10. A method as claimed in any of Claims 1 to 5 in which the step of forming a primary strap loop includes feeding a length of strap between two axially aligned adjacent guide rings.
- 11. A method as claimed in Claim 10 which includes pivoting each guide ring away from the primary strap loop to provide clearance around the periphery of the loop to permit expansion of the loop to the larger size.
- 12. A method as claimed in any of Claims 1 to 5 in which the step of forming a primary strap loop includes feeding a length of strap on the inside of a flexible member which is maintained in an arcuate configuration.
- 13. A method as claimed in Claim 12which includes pulling one end of the flexible member increasingly away from the centre of the primary strap loop whereby the flexible member is peeled away from the loop to provide clearance around the periphery of the loop to permit expansion of the loop to the larger size.
- 14. A method as claimed in Claim 1 or any of Claims 3, 4, or 5 when dependent thereon, in which the step of forming a primary strap loop includes holding the free end of a length of strap and moving the free end in a closed arcuate path to orient one strap side on the free end adjacent and facing the opposite strap side on an overlapped portion.
- 15. A method as claimed in Claim 14 in which the step of holding the free end of a length of strap includes restraining the free end in a slot on a rotatable holding member.
- 16. A method as claimed in Claim 14 or Claim 15 in which the step of moving the strap end in a closed path includes rotating the holding member greater than 2x radians.
- 17. A method as claimed in any of the preceding claims in which the step of effecting relative movement between the package and the expanded loop includes the steps of first restraining an area of the expanded loop and then twisting the balance of the loop about the said area and out of the plane of loop formation to locate the loop about the package.
- 18. A method as claimed in Claim 17 in which the step of first restraining the loop includes pressing the free end and overlapped portion of the loop between a roughsurfaced member contacting a side of the free end and a smooth-surfaced member contacting a side of the overlapped portion of the strap loop.
- 19. A method of forming a strap loop and securing it about a package comprising: feeding a length of strap and guiding a leading end portion thereof in an arcuate path such as to form a primary loop with the leading end of the said strap overlapping a part of the said length of strap, the said leading end portion being guided by strap guide means which act on the strap from only one side of the said arcuate path; restraining the free end of the strap to prevent further movement of the free end; effecting relative movement between the primary loop and the strap guide to provide clearance around the periphery of the primary loop while continuing to cause the standing portion of strap to advance towards the loop to expand the loop predetermined diameter; inserting a package in the expanded loop; drawing the loop tight around the package; friction welding the free end of the strap to an adjacent over lapped portion of the strap; and severing the standing portion of the strap from the tightened and welded loop.
- 20. Apparatus for forming a strap loop and securing it about a package, comprising; a strap guide means for guiding a leading end portion of a length of strap in an arcuate path such as to form a primary loop with the leading end of said strap overlapping a part of the said length of strap, the strap guide means acting on the strap from only one side of the said arcuate path; means for restraining the said free end of the strap to prevent further movement of the said free end; means for causing the standing length of strap to advance towards the loop to expand the loop to a predetermined diameter; means for effecting relative movement between the package and the expanded loop to locate the expanded loop about the package; and means for joining the said free end of the strap to an adjacent overlapped portion of the strap either before or after effecting such relative movement between the package and the said expanded loop.
- 21. Apparatus as claimed in Claim 20 which includes means for tensioning the strap to tighten the expanded loop about a package.
- 22. Apparatus as claimed in Claim 20 or Claim 21 in which the means for forming a primary loop includes a circular band member having a slot, the band member being positioned to receive the strap through the slot and being designed to guide the strap along the inner surface of the band to form the primary strap loop.
- 23. Apparatus as claimed in Claim 22 in which the slot is open to one edge of the band member, and including means for moving the band member between a first position wherein the primary strap loop is formed and a second position parallel to, and spaced away from, the first position to allow the primary strap loop to be expanded to the larger size out of contact with the band member.
- 24. Apparatus as claimed in any of Claims 20 to 23 in which the means for restraining the free end of the strap comprises a roughsurfaced member adapted for bearing against a side of the free end to engage the free end between the rough-surfaced member and an adjacent overlapped portion of the loop while the standing length of the strap is fed to expand the loop.
- 25. Apparatus as claimed in Claim 20 or Claim 21, or in Claim 24 when dependent thereon, in which the guide means is a hollow, substantially cylindrical member having a slot for passing the length of strap from the exterior of the cylindrical member to the interior of the cylindrical member.
- 26. Apparatus as claimed in Claim 25 in which the slot is open to one end of the cylindrical member, the apparatus including means for moving the cylindrical member between a first position wherein the primary strap loop is formed and a second position spaced away from the first position to allow the primary strap loop to be expanded to the larger size out of contact with the cylindrical member.
- 27. Apparatus as claimed in any of Claims 20 to 26 which is adapted for use with strap which is fusible or has a fusible coating and in which the means for joining includes a rough-surfaced gripping member rotatably mounted on a frame and in which said means for restraining said free end of the strap further includes an anvil, the said apparatus further including means for effecting relative movement between the anvil and the gripping member to compress the strap free end and an adjacent overlapped portion of the loop therebetween and to place the strap free end and the adjacent overlapped portion of the loop in frictional engagement, and means for oscillating the gripping member to produce bodily sliding frictional movement of the strap free end against the adjacent overlapped portion of the loop to effect interface melting therebetween, whereby the strap free end is fused to the adjacent overlapped portion of the loop.
- 28. Apparatus as claimed in any of Claims 20 to 26 in which the means for restraining the free end of the strap comprises a roughsurfaced member and an opposed smoothsurfaced member for pressing the free end of the strap and an adjacent overlapped portion of the loop therebetween.
- 29. Apparatus as claimed in Claim 28 which includes strap edge locator means for guiding at least one of the two edges of a portion of the length of strap as the strap is fed.
- 30. Apparatus as claimed in Claim 29 in which the strap edge locator means comprises a flange on the rough-surfaced member.
- 31. An apparatus for forming, tensioning, and securing a strap loop about a package, said apparatus comprising: a frame having means for supporting a length of strap along one edge of the strap; means for feeding a length of strap; guide means for receiving a free end of said length of strap to urge said strap in a path to form a primary strap loop with a portion of the strap loop overlapped by said free end by guiding only the exterior portions of the strap whereby said strap is unguided on the interior of said loop, means for restraining said free end of the strap from movement means for moving said guide means relative to said primary loop to provide clearance around the periphery of said primary loop while continuing to feed the standing length of the strap to expand the loop to a predetermined size; means for tensioning the strap to tighten the loop about said package; and means for joining said free end of the strap and an adjacent overlapped portion of the loop.
- 32. Apparatus for forming, tensioning and securing a fusible strap or a strap with a fusible coating in a loop about a package, the apparatus comprising a frame having a package support surface; means for supporting a length of strap on edge in a strap transport zone below the package support surface; a motor-driven traction wheel and adjacent idler wheel located in the strap transport zone and adapted for engaging the length of strap therebetween for feeding the length of strap in one direction for forming a loop and for drawing the length of strap in the reverse direction to tension the loop; a cylindrical weld head located in the strap transport zone with the axis parallel to the sides of the strap in the zone and having a peripheral gripping surface adapted for contacting a side of the strap; a smooth-surfaced anvil member located adjacent the weld head in the strap transport zone;means for moving the anvil in the strap transport zone towards the weld head to engage portions of the strap therebetween; a hollow cylindrical guide in the strap transport zone surrounding the weld head and having slot means for accommodating the movement of the anvil member towards the weld head and for accommodating the passage of the length of strap between the anvil and the weld head from the exterior to the interior of the guide when the length of strap is fed into the guide to form a primary strap loop with a portion of the strap loop overlapped by the free end of the strap, the guide being movable between a first position in alignment with the strap transport zone and a second position, below the first position, wherein the primary strap loop can be expanded to a larger loop of predetermined diameter when the free end of the strap is pressed between the weld head gripping surface and an adjacent overlapped portion of the loop by the smooth-surfaced anvil; means connected to the cylindrical weld head for oscillating the head at a frequency sufficiently high to fuse the free end of the strap to an adjacent overlapped portion of the loop; and cutter means for severing the standing portion of the length of strap from the tightened and fused loop.
- 33. Apparatus as claimed in Claim 32 which includes control means responsive to the rotation of the traction wheel for moving the cylindrical guide from the first position to the second position after formation of the primary strap loop in the guide.
- 34. Apparatus as claimed in Claim 33 in which the traction wheel is secured to a shaft and in which the control means includes a clutch member engageable with the shaft.
- 35. Apparatus as claimed in Claim 32 or Claim 33 or Claim 34 in which the means for moving the anvil includes an air operated piston and cylinder actuator and in which the apparatus includes automatically actuated valve means for variable pressurizing the piston and cylinder actuator to bias the anvil member with the variable force against the weld head with portions of strap impressed therebetween.
- 36. A method of forming a strap loop and securing it about a package substantially as described herein with reference to Figures 1 to 14 of the accompanying drawings.
- 37. A method as claimed in Claim 36 modified substantially as described herein with reference to Figures 15 to 17, or to Figure 18, or to Figures 19 and 20, or to Figure 21, or to Figures 22 to 25, or to Figures 26 to 28, or to Figures 29 and 30, or to Figure 31 of the accompanying drawings.
- 38. Apparatus for forming and securing a strap loop about a package substantially as described herein with reference to Figures I to 14 of the accompanying drawings.
- 39. Apparatus as claimed in Claim 38 modified substantially as described herein with reference to Figures 15 to 17, or to Figure 18, or to Figures 19 and 20, or to Figure 21, or to Figures 22 to 25, or to Figures 26 to 28 or to Figures 29 and 30, or to Figure 31 of the accompanying drawings.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US05/752,011 US4062278A (en) | 1976-12-20 | 1976-12-20 | Expanding strap loop forming and friction fusion machine |
US05/752,001 US4079667A (en) | 1976-12-20 | 1976-12-20 | Method of forming and tensioning a strap loop about a package |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1597348A true GB1597348A (en) | 1981-09-03 |
Family
ID=27115515
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB52966/77A Expired GB1597348A (en) | 1976-12-20 | 1977-12-20 | Methods and apparatus for forming and securing a strap loop about a package |
Country Status (12)
Country | Link |
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JP (1) | JPS5379696A (en) |
BR (1) | BR7708421A (en) |
CA (1) | CA1063501A (en) |
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US5078057A (en) * | 1990-01-05 | 1992-01-07 | Illinois Tool Works Inc. | Binding machine, such as strapping machine |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1153318B (en) * | 1959-11-05 | 1963-08-22 | Ver Metaalverpakking Mij Nv | Machine for fastening a metal band or a metal wire around a box, a can, a package or another package |
US3586572A (en) * | 1969-02-20 | 1971-06-22 | Signode Corp | Electrically controlled handtool for friction-fusing nonmetallic strap |
US3554844A (en) * | 1969-04-07 | 1971-01-12 | Charles J Ingram | Tying device |
JPS528095B2 (en) * | 1972-04-24 | 1977-03-07 | ||
DE2403261C3 (en) * | 1974-01-24 | 1978-07-20 | Maryan 5443 Kaisersesch Stankovicc-Gansen | Device for automatic strapping |
-
1977
- 1977-10-14 CA CA288,737A patent/CA1063501A/en not_active Expired
- 1977-11-16 NL NLAANVRAGE7712628,A patent/NL187262C/en not_active IP Right Cessation
- 1977-11-23 DE DE2752360A patent/DE2752360C2/en not_active Expired
- 1977-11-29 CH CH1462477A patent/CH623529A5/en not_active IP Right Cessation
- 1977-11-29 JP JP14324477A patent/JPS5379696A/en active Granted
- 1977-12-19 SE SE7714434A patent/SE7714434L/en not_active Application Discontinuation
- 1977-12-19 FR FR7738348A patent/FR2374215A1/en active Granted
- 1977-12-19 NZ NZ186025A patent/NZ186025A/en unknown
- 1977-12-19 IT IT30890/77A patent/IT1089176B/en active
- 1977-12-19 BR BR7708421A patent/BR7708421A/en unknown
- 1977-12-20 ES ES465712A patent/ES465712A1/en not_active Expired
- 1977-12-20 GB GB52966/77A patent/GB1597348A/en not_active Expired
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1982
- 1982-02-10 SE SE8200781A patent/SE8200781L/en unknown
- 1982-02-10 SE SE8200782A patent/SE449081B/en not_active IP Right Cessation
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DE2752360A1 (en) | 1978-06-29 |
NL7712628A (en) | 1978-06-22 |
DE2752360C2 (en) | 1985-02-14 |
SE7714434L (en) | 1978-06-21 |
IT1089176B (en) | 1985-06-18 |
CA1063501A (en) | 1979-10-02 |
JPS6238208B2 (en) | 1987-08-17 |
ES465712A1 (en) | 1979-01-01 |
BR7708421A (en) | 1978-07-25 |
CH623529A5 (en) | 1981-06-15 |
NL187262C (en) | 1991-08-01 |
SE8200781L (en) | 1982-02-10 |
JPS5379696A (en) | 1978-07-14 |
FR2374215B1 (en) | 1980-06-20 |
SE8200782L (en) | 1982-02-10 |
SE449081B (en) | 1987-04-06 |
NZ186025A (en) | 1981-02-11 |
FR2374215A1 (en) | 1978-07-13 |
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Legal Events
Date | Code | Title | Description |
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PS | Patent sealed [section 19, patents act 1949] | ||
PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19941220 |