US3752058A

US3752058A - Feed mechanism

Info

Publication number: US3752058A
Application number: US00152266A
Authority: US
Inventors: P Lems
Original assignee: Signode Corp
Current assignee: Signode Corp
Priority date: 1971-06-11
Filing date: 1971-06-11
Publication date: 1973-08-14
Anticipated expiration: 1990-08-14
Also published as: DE2224673B2; GB1357480A; ES402784A1; FR2141357A5; ZA723519B; IT955759B; CA987581A; DE2224673A1; JPS5435557B1

Abstract

A strap-feeding and tensioning mechanism for applying strap material about an article and tensioning the strap prior to interconnection of the strap loop about the article. The tensioning mechanism consists of a driven wheel that has a friction producing member cooperating therewith to produce frictional engagement between the strap and the peripheral surface of the wheel. The friction producing member is in the form of an arcuate segment that encompasses a substantial circumferential portion of the wheel and is movable between first and second positions to (1) allow unrestricted relative movement between the strap and the wheel and (2) frictionally engage the strap with the periphery of the wheel to cause movement of the strap in response to rotation of the wheel.

Description

United States Patent [191 Lems Aug. 14, 1973 [54] FEED MECHANISM Primary Examiner-John Petrakes 5 I t Pete Lems w- L Assistant Examiner-C. K. Moore 1 men or r 1 I Attorney-Dressler, Goldsmith, Clement & Gordon [73] Assignee: Signode Corporation, Glenview, Ill.

[22] Filed: June 11, 1971 [57] ABSTRACT [21 Appl. No.: 152,266 A strapfeeding and tensioning mechanism for applying strap material about an article and tensioning the strap 52] U 8 Cl 100 /32 100/26 prior to interconnection of the strap loop about the ar- [51] g 13/22 ticle. The tensioning mechanism consists of a driven 58] Fieid /25 26 32 wheel that has a friction producing member cooperat- 226/1 83 ing therewith to produce frictional engagement between the strap and the peripheral surface of the wheel. [5 6] Re'ennces Cited The friction producing member is in the form of an arcuate segment that encompasses a substantial circurn- UNITED STATES PATENTS ferential portion of the wheel and is movable between 9 2 V196l 1! e! 100/26 first and second positions to 1) allow unrestricted rela- 23764505 V1957 226/133 Ux tive movement between the strap and the wheel and gags 5 (2) frictionally engage the strap with the periphery of the wheel to cause movement of the strap in response to rotation of the wheel.

11 Claims, 5 Drawing Figures Patented Aug. 14, 1973 2 SheetsSheet 1 fwenfofl' P6596 01 m 29% Patented Aug. 14, 1973 3,752,058

2 Sheets-Sheet 2 M1 z J1 ZZZ FEED MECHANISM BACKGROUND OF THE INVENTION The present invention relates generally to a mechanism for feeding strap about an article to produce a loop and tensioning the strap about the article after the leading end of the strap has been gripped. The present invention has particular utility in the feeding and tensioning of various types of plastic strapping materials.

When articles or packages are secured by ligatures, it has been a practice to automatically feed the material about the package to form a loop, grip the leading end of the strap, and apply a tension to the strap to remove slack in the loop in order to obtain a package surrounded by a ligature under tension. When articles are to be secured with such ligatures, it is desirable to be able to dispose the strap about the article in a minimum amount of time. Thus, it has been customary to feed the strap about the article at a rather high rate of speed and also to remove the slack from the strap loop at substantially the same rate of speed. After the slack has been removed and the strap is substantially in final location relative to the article, a high tension should be placed on the strap to obtain a suitably type package.

One apparatus for performing the feeding and tensioning function is disclosed in US. Pat. No. 3,420,158, issued Jan. 7, 1969, and an improved mechanism is disclosed in US. Pat. No. 3,566,778 issued Mar. 7, I971,

both patents being assigned to the as'signee of the present invention. In the feeding and tensioning apparatus disclosed in these patents, the feeding and initial removal of slack from the strap loop is accomplished by a first wheel that is driven at a high rate of speed in opposite directions, while the final tensioning wheel has a fixed guide spaced therefrom for guiding the strap adjacent the wheel. The drive mechanism incorporates a clutch that automatically slips when a predetermined amount of tension has been developed in the strap. The final tensioning of the strap loop is then accomplished by a second wheel that has the strap encompassing a portion thereof.

In the apparatus disclosed in the above two patents, the final tensioning wheel has a urethane rubber-like material on the outer periphery thereof, and the tension produced by the initial feed wheel draws the strap away from the guide into engagement with the tension wheel and produces frictional driving engagement between the urethane portion and the strap to produce the final tensioning of the strap loop. While the above type of apparatus has found a remarkable degree'of commercial success, there are certain instances in which it may be desirable to consistantly obtain tension loads greater than that capable of being developed in the patented apparatus.

SUMMARY OF THE INVENTION The present invention contemplates an improved guiding and friction gripping mechanism that cooperates with the final tensioning wheel of a strap feeding and tensioning apparatus that insures positive gripping between the wheel and the strap during the tensioning operation and at the same time provides for a movable guide that cooperates with the strap during the rapid feeding phase of the operation to minimize abrasion between the guide and the strap. The mechanism consists of a member that has a concave surface in juxtaposed relation to at least a peripheral portion of the wheel and moving means cooperating with the member to move the member between a guiding position and a gripping position.

In the illustrated embodiment, the concave or arcuate surface is collectively defined by a plurality of circumferentially spaced freely rotatable rollers that are interconnected by links and the moving means consists of a fixed pivot axis for one end of the member, and an arm pivoted on a second pivot axis with the opposite end of the member secured to the arm eccentrically of the fixed pivot. The arm is then moved between two po sitioris to respectively define the guiding and the friction gripping positions for the arcuate surface. The roll- 'ers are sufficiently close to one another that their diametric portions adjacent the tension wheel cooperate to define an arcuate strap compressing surface, even though the rollers are spaced. The rollers extend over a substantial circumferential extent of the tension wheel to provide a distributed area of contact which BRIEF DESCRIPTION OF SEVERAL VIEWS OF DRAWINGS FIG. 1 is a schematic front elevational view of a strapping machine and associated strap guide chute;

FIG. 2 is an enlarged fragmentary side elevational view illustrating the feeding and tensioning mechanism of the strapping machine;

FIG. 3 is a view taken generally along line 3-of FIG.

FIG. 4 is a section viewtaken generally along line 4-4 of FIG. 3; and

FIG. 5 is an enlarged fragmentary view taken generally along line 55 of FIG. 4.

DETAILED DESCRIPTION While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail one specific embodirnent, with the understanding that the present disclosure is to be considered an an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated.

Referring to FIG. 1, a strap 10 extends from a supply roll 12 through a suitable guide chute 14 to be located around a package or the like 16 in the form of a strap loop. The strap is directed through a feeding and tensioning mechanism 18 which forms the subject matter of the present invention. After the strap is looped about the container, it is gripped, tensioned and severed from the supply source 12 and a suitable sealing mechanism 19 is actuated to secure the over-lapped strap portions in place about the container.

The various components of the feeding and tensionnism for the tensioning and feeding mechanism forms no part of the present invention, a detailed description thereof is unnecessary. However, for purposes of completeness, the feed wheel 22 of the feeding and tensioning mechanism is operated at a high rate of speed while the tensioning wheel 24 is operated at a lower rate to allow for the development of higher torque forces for the final tensioning of the strap.

During the feeding and initial removal of the slack from the loop of strap, the strap is frictionally gripped between the feed wheel 22 and a pair of circumferentially spaced pinch rollers 28 that are biased or otherwise held in engagement with the strap to frictionally grip the strap between the wheel and the pinch rolls. The pinch rolls may either be continuously held in engagement with the strap, as is disclosed in U.S. Pat. No. 3,420,158 or alternatively may be movable relative to the feed wheel as is disclosed in U.S. Pat. No.

As is more fully explained in the above mentioned patents, the wheel 22 is initially rotated in a clockwise direction to feed strap from the supply 12 in sufficient quantity to encompass the article and create a loose loop. During this feeding phase of the operation, the strap is guided along a fixed guide adjacent the periphery of the second wheel 24 in a manner to prevent direct contact with the second wheel. After the loop has been completed, the leading end of the strap is gripped, as by structure described in detail in U.S. Pat. No. 3,442,203. Thereafter, the wheel 22 is rotated in the opposite direction, counterclockwise as viewed in FIG. 2, to initially take-up slack in the strap loop prior to final tensioning of the strap loop. Following shrinking of the strap loop, the strap is pulled into engagement with the periphery of the second wheel 24 and, when the tension on the strap reaches a predetermined level, a slip clutch (not shown in this application)-between the drive motor and feed wheel 22 causes a slipping, which allows the feed wheel to be rotated at a slower rate of speed. At this time, it is desirable to have the gripping force between the second or tension wheel 24 of sufficient magnitude to insure that the desired final tension may be applied to the loop prior to a sealing operation. The present invention contemplates a heavy duty type of apparatus that is capable of developing a desired tension on the strap loop.

The gripping force between the encompassing portion of the strap 10 and the wheel 24 is substantially increased by gripping means constructed in accordance with the teachings of the present invention. The gripping means is in the form of an elongated member defining a concave or arcuate surface in juxtaposed relation to the encompassing portion of the strap, with the arcuate surface having a first position for guiding the strap in spaced relation to the periphery of the wheel and a second position for forcing the strap into engagement with the periphery of the wheel.

The means for selectively causing gripping engagement between the tension wheel and the strap is illustrated in FIGS. 2 through 5 and consists of a member or belt 30 having one end pivoted about a fixed pivot pin 32 that is secured to the housing 34 (FIG. 2). The opposite end of the belt is secured to the hub portion 36 of an arm 38 that is pivoted on a second fixed pivot pin 40 carried by the support 34.

The belt 30 consists of a plurality of rollers 42a and 42b freely rotatable on pins 46 that are interconnected by links 44. The arm 38 is normally maintained in the solid position shown in FIG. 2 wherein the arcuate surface defined by the collective peripheries of the plurality of rollers 42a and 42b is spaced a sufficient distance from the periphery of the wheel 24 to allow the strap 10 to move freely along the arcuate surface without engaging the peripheral surface of the wheel.

When the wheel 22 completes the constriction of the strap loop and the application of an initial tension, the arm 38 is moved to the second dotted line position, shown in FIG. 2, by means to be hereinafter described, to cause the arcuate surface to be moved sufficiently to produce a gripping pressure between the periphery of the wheel and the adjacent surface of the strap. In order to have the desired gripping engagement between the wheel and strap, it is preferable that the periphery of the wheel be serrated or have teeth formed thereon and to form the wheel of a steel material.

According to another aspect of the invention, the gripping means further includes mechanism for maintaining a predetermined minimum spacing between the peripheral surface of the wheel and the arcuate or concave surface collectively defined by the rollers 42a and 42b. This is desirable to insure that the rollers do not directly engage the roughened surface of the wheel when no strap is located between the two surfaces. It will be appreciated that direct contact could damage either or both of the surfaces.

The mechanism for maintaining the predetermined minimum spacing between the two surfaces is in the form of radial flanges 50 located on opposite ends of the rollers 42b, which may be termed spools. The

flanges 50 extend beyond the outer periphery of the wheel 24 toward the center and engage a pair of circumferentially extending ledges 52 located on opposite sides of the peripheral surface of the wheel. The ledges are formed by reduced diameter portions adjacent the opposite ends of the wheel. An inspection of FIG. 5 shows that the peripheral surfaces of the wheel and rollers are spaced from each other by a small dimension when no strap is located between the two surfaces. The flanges also insure that the strap is maintained adjacent the periphery of the wheel 24 at all times.

The mechanism for moving the member or belt 30 into frictional engagement with the strap to produce a substantially uniform gripping pressure between the encompassing portion of the strap and the periphery of the tension wheel 24 may take various forms. One mechanism that has been found satisfactory is a power means including a solenoid 58 having its plunger 60 connected to the outer end of the arm 38 through a link 62. The solenoid may periodically be energized by any suitable means, such as a timer that may periodically be actuated for a predetermined amount of time to move the arm from the solid line to the dotted line position of FIG. 2 and maintain the arm in the dotted line position for the selected time period. Alternatively, the solenoid could be energized by a suitable govenor or cam that could be controlled by the speed of rotation of the feed wheel 22. As was explained above, when the slack on the strap loop has been removed, a slip clutch in the drive mechanism for the feed wheel 22 allows the drive mechanism to continue to move at a rapid rate while the feed wheel 22 is rotated at a slower rate. At this time, the solenoid 58 could be actuated to move the arm 38.

While the operation of the feeding and tensioning mechanism has been described, a brief summary appears to be in order. The lead end of the strap is initially fed between the peripheral surface of the wheel 22 and the pinch rollers 28 as well as between the arcuate surface on the member 30 and the peripheral surface of the second wheel 24. The lead end of the strap is then located in a suitable guide mechanism (not shown) to be fed into the guide 14 extending around the container 16. Clockwise rotational movement of the first wheel 22 by drive motor rapidly feeds the strap in sufficient quantity around the container to form a strap loop.

After the strap loop has been formed about the package, the free end is gripped and the drive motor is reversed so that the first wheel 22 is rotated counterclockwise while the second wheel is rotated clockwise. During initial reverse movement, the first wheel 22 will remove all of the slack from the strap loop and, when sufficient tension has been achieved on the strap loop, a slip clutch will become operative with a resultant reduction in speed of the first wheel 22 until such time as the speed of the two wheels coincide. At this time, the solenoid 58 may be energized to move the arm 38 to its dotted line position and consequently move the member 30 to its gripping position, forcing the encompassing portion of the strap into frictional engagement with approximately one-half or 180 of the periphery of the second wheel 24 producing a substantially uniform pressure of the entire encompassing portion of the strap. After a predetermined amount of tension has been applied to the strap loop, the overlapping portions of the strap are interconnected by any suitable means, and the loop is severed from the remainder of the strap supply 12. Preferably, the strap and gripping member 30 encompass at least a 90 segment of the wheel to insure sufficient gripping force and achieve the desired tension on the strap loop.

It will be appreciated that the present invention provides a simple and inexpensive expedient for positively gripping the strap during a tensioning phase of article packaging while readily allowing unobstructed relative movement between the tension wheel and the strap during the remaining phases of the article packaging. The rollers provide a movable guide for the strap during the feeding operation while also providing a movable gripping member during the tensioning phase of the operation.

If desired, the mechanism 30 could also be used in place of the pinch rolls 28.

What is claimed is:

1. Apparatus for moving strap to be directed about an article comprising a wheel having at least a portion thereof encompassed by said strap, said wheel having.

a serrated periphery to increase the frictional engagement between said strap and said wheel; a drive mecha-- nism for rotating said wheel; and means, extending substantially 180 around said wheel, for selectively causing gripping engagement between said wheel and strap, said means including a member having a concave surface in juxtaposed relationship with the encompassing portion of said strap, said concave surface being comprised of a plurality of equally and closely spaced freely rotatable rollers, and moving means cooperating with said memberto move said rollers into engagement with said strap and said strap into engagement with the serrated periphery of said wheel to produce a gripping pressure between the encompassing portion of said strap and the serrated periphery of said wheel.

2. Apparatus as defined in claim 1, in which said moving means includes means defining a fixed pivot ad- 5 jacent said wheel for one end of said member; and

power means for an opposite end of said member.

3. Apparatus as defined in claim 2, in which said power means includes means defining a second fixed pivot adjacent said wheel, an arm rotatable on said second fixed pivot between firat and second positions, said opposite end of said member being connected to said arm at a location spaced from the second fixed pivot; and means for moving said arm between said positions.

4. Apparatus as defined in claim I in which said rollers are interconnected by links.

5. Apparatus for moving strap to be directed about an article comprising a wheel having at least a portion thereof encompassed by said strap; a drive mechanism for rotating said wheel; and means for selectively causing gripping engagement between said wheel and strap, the improvement of said means including a member having a concave surface in juxtaposed relationship with the encompassing portion of of said strap and moving means cooperating with said member to engage said strap with said surface to produce a gripping pressure between the encompassing portion of said strap and the periphery of said wheel, said moving means including means defining a fixed pivot adjacent said wheel for one end of said member, power means connected to an opposite end of said member, said power means including mpans defining a second fixed pivot adjacent said wheel, an arm rotatable on said second fixed pivot between first and second positions, said opposite end of said member being connected to said arm at a location spaced from the second fixed pivot, and means for moving said arm between said positions.

6. Apparatus as defined in claim 5 in which said member includes a plurality of freely rotatable rollers interconnected by links, the peripheries of said rollers cooperating to define said concave surface.

7. Apparatus as defined in claim 5, in which said member is a belt.

8. Apparatus for moving strap to be directed about an article comprising a wheel having at least a portion thereof encompassed by said strap; a drive mechanism for rotating said wheel; and means for selectively causing gripping engagement between said wheel and strap, the improvement of said means including a member having a concave surface in juxtaposed relationship with the encompassing portion of said strap, moving means cooperating with said member to engage said strap with said surface to produce a gripping pressure between the encompassing portion of said strap and the periphery of said wheel, and spacer means, between said wheel and concave surface to maintain a predetermined spacing between the periphery of said wheel and said surface when no strap is encompassing said wheel.

9. A strap feed and tension mechanism for strapping to be directed about an article and securing the same including a wheel about which a strap is disposed; means for driving said wheel; cooperating means adjacent the peripheral surface of said wheel, said cooper-' ating means defining an arcuate surface encompassing a substantial portion of said wheel and producing a substantially uniform gripping pressure between said strap and said portion of said wheel; and means for moving said arcuate surface away from the position adjacent 11. A strap feeding and tensioning mechanism as defined in claim 9, in which said wheel has ledges adjacent opposite ends of said surface and at least some of said rollers have flanges extending beyond the peripheral surfaces engaging said ledges to define a minimum spacing between the peripheral surface of said wheel and said rollers.

a t a a

Claims

1. Apparatus for moving strap to be directed about an article comprising a wheel having at least a portion thereof encompassed by said strap, said wheel having a serrated periphery to increase the frictional engagement between said strap and said wheel; a drive mechanism for rotating said wheel; and means, extending substantially 180* around said wheel, for selectively causing gripping engagement between said wheel and strap, said means including a member having a concave surface in juxtaposed relationship with the encompassing portion of said strap, said concave surface being comprised of a plurality of equally and closely spaced freely rotatable rollers, and moving means cooperating with said member to move said rollers into engagement with said strap and said strap into engagement with the serrated periphery of said wheel to produce a gripping pressure between the encompassing portion of said strap and the serrated periphery of said wheel.

2. Apparatus as defined in claim 1, in which said moving means includes means defining a fixed pivot adjacent said wheel for one end of said member; and power means for an opposite end of said member.

4. Apparatus as defined in claim 1 in which said rollers are interconnected by links.

5. Apparatus for moving strap to be directed about an article comprising a wheel having at least a portion thereof encompassed by said strap; a drive mechanism for rotating said wheel; and means for selectively causing gripping engagement between said wheel and strap, the improvement of said means including a member having a concave surface in juxtaposed relationship with the encompassing portion of of said strap and moving means cooperating with said member to engage said strap with said surface to produce a gripping pressure between the encompassing portion of said strap and the periphery of said wheel, said moving means including means defining a fixed pivot adjacent said wheel for one end of said member, power means connected to an opposite end of said member, said power means including means defining a second fixed pivot adjacent saId wheel, an arm rotatable on said second fixed pivot between first and second positions, said opposite end of said member being connected to said arm at a location spaced from the second fixed pivot, and means for moving said arm between said positions.

7. Apparatus as defined in claim 5, in which said member is a belt.

8. Apparatus for moving strap to be directed about an article comprising a wheel having at least a portion thereof encompassed by said strap; a drive mechanism for rotating said wheel; and means for selectively causing gripping engagement between said wheel and strap, the improvement of said means including a member having a concave surface in juxtaposed relationship with the encompassing portion of said strap, moving means cooperating with said member to engage said strap with said surface to produce a gripping pressure between the encompassing portion of said strap and the periphery of said wheel, and spacer means between said wheel and concave surface to maintain a predetermined spacing between the periphery of said wheel and said surface when no strap is encompassing said wheel.

9. A strap feed and tension mechanism for strapping to be directed about an article and securing the same including a wheel about which a strap is disposed; means for driving said wheel; cooperating means adjacent the peripheral surface of said wheel, said cooperating means defining an arcuate surface encompassing a substantial portion of said wheel and producing a substantially uniform gripping pressure between said strap and said portion of said wheel; and means for moving said arcuate surface away from the position adjacent the peripheral surface of said wheel to a second position where said surface acts as a guide for said strap and accommodates substantially unrestricted relative movement between said strap and said wheel.

10. A strap feeding and tensioning mechanism as defined in claim 9, in which said cooperating means includes a plurality of circumferentially spaced rollers, the peripheral surfaces of which cooperate to define said arcuate surface.

11. A strap feeding and tensioning mechanism as defined in claim 9, in which said wheel has ledges adjacent opposite ends of said surface and at least some of said rollers have flanges extending beyond the peripheral surfaces engaging said ledges to define a minimum spacing between the peripheral surface of said wheel and said rollers.