Bag tying apparatus having over-travel compensation assembly for holder-shear drive assembly

A bag tying apparatus for tying a ribbon about a gathered neck is provided. A holder-shear drive assembly moves a holder-shear assembly from side to side to grip and cut the ribbon. An over-travel compensation assembly compensates for over-travel of the holder-shear drive assembly relative to the travel of the holder-shear assembly.

CROSS REFERENCE TO RELATED APPLICATIONS

Not Applicable

Not Applicable

REFERENCE TO MICROFICHE APPENDIX

Not Applicable

Technical Field

This invention relates to a type of apparatus for gathering a neck of a flexible bag, wrapping a ribbon around the gathered neck of the bag, and twisting the ribbon for closing and sealing the neck of the bag.

BACKGROUND OF THE INVENTION

The following patents disclose apparatus used for closing a flexible bag by attaching and twisting a wire-like ribbon about the neck of a flexible bag: U.S. Pat. No. 3,138,904 issued Jun. 30, 1964 to Earl E. Burford entitled “METHOD AND APPARATUS FOR TYING PACKAGES AND WRAPPING MATERIALS; U.S. Pat. No. 3,059,670 issued Oct. 23, 1962 to Charles E. Burford and Leonard W. Burford entitled “WIRE TWISTING TOOL; U.S. Pat. No. 3,919,829 issued Nov. 18, 1975 to Leonard W. Burford and Charles C. Burford entitled “APPARATUS FOR TYING PACKAGES AND WRAPPING MATERIALS;” U.S. Pat. No. 4,856,258 issued Aug. 15, 1989 to Charles E. Burford and Jimmy R. Frazier entitled “WIRE TYING DEVICE;” U.S. Pat. No. 5,483,134 issued Jan. 9, 1996 to Jimmy R. Frazier, John D. Richardson, and Greg P. Coxsey entitled “RIBBON SENSING DEVICE FOR BAG TYER”; U.S. Pat. No. 5,692,358 issued Dec. 2, 1997 to Jimmy R. Frazier, John D. Richardson, and Greg P. Coxsey entitled “BAG NECK TYING DEVICE;” U.S. Pat. No. 5,826,629 issued Oct. 27, 1998 to Joe E. West entitled “WIRE TYING APPARATUS;” and U.S. Pat. No. 5,708,339 issued Jan. 13, 1998 to Jimmy R. Frazier, John D. Richardson, and Greg P. Coxsey entitled “BAG NECK GATHERING STOP.” These U.S. patents are incorporated herein by reference in their entirety for all purposes. If there is any conflict between a reference incorporated by reference and the present disclosure, the present disclosure will control.

Bag tying apparatuses of the type disclosed in the aforementioned patents are commercially available from Burford Corporation of Maysville, Okla. They are constructed to receive packages of product, such as loaves of bread, at speeds of, for example, 100 packages per minute. The design of such bag tying apparatus requires careful consideration of the mass, acceleration, deceleration, and momentum of the moving parts. Further, precise synchronization of parts in assemblies of the apparatus must be maintained throughout repeated tying cycles for the apparatus to operate effectively.

The apparatus hereinafter described offers improvements over the apparatuses described in the above-mentioned patents, for example, to increase the tying rate or to provide apparatuses that require less maintenance.

SUMMARY OF THE INVENTION

A new type of bag tying apparatus is provided for gathering the open end of a bag into a neck and tying the bag neck closed using a ribbon. According to the invention, the apparatus includes: a frame; a gathering means for gathering the open end of a bag into a neck; a holder-shear means for holding a free end of the ribbon adjacent to the gathered neck of the bag and, after the neck of the bag is tied, for cutting the ribbon; a needle means adjacent the holder-shear means, the needle means for engaging the ribbon a distance from the free end and operable to loop a strand of the ribbon about the gathered neck of the bag; a twister means having a hook adjacent the holder-shear means, the twister means for twisting the strand of the ribbon around the gathered neck of the bag; a holder-shear drive means for actuating the holder-shear means; and an over-travel compensation means operatively connected between the holder-shear drive means and the holder-shear means, the over-travel compensation means for compensating for over travel of the holder-shear drive means relative to the travel of the holder-shear means.

The gathering means, the holder-shear means, the needle means, the twister means, the holder-shear drive means, and the over-travel compensation means are operatively supported by the frame.

According to the invention, the holder-shear drive means preferably has the structure of a holder-shear drive assembly. More preferably, the holder-shear drive assembly has the structures of: (a) an eccentric element mounted fixedly on a drive shaft, the eccentric element rotated by the drive shaft; (b) a housing slidingly mounted on the eccentric element, the housing reciprocated along a housing path by the rotating eccentric element; (c) a reciprocating member operatively connected to the housing to be reciprocated by the housing, the reciprocating member operatively connected to the holder-shear means to actuate the holder-shear means, the reciprocating member operable to travel along a reciprocating member path, the reciprocating member limited in its travel at both ends of the reciprocating member path by the holder-shear means, wherein the housing path is greater than the reciprocating member path, and wherein the housing over-travels the reciprocating member.

According to the invention, the over-travel compensation means preferably has the structure of an over-travel compensation assembly. More preferably, the over-travel compensation assembly is operatively connected between the housing and the reciprocating member, wherein the over-travel compensation assembly is operable to allow the housing to move in relation to the reciprocating member when the reciprocating member is at either of the ends of the reciprocating member path, whereby the housing is allowed to travel along the housing path that is greater than the reciprocating member path.

These and further aspects and embodiments of the inventions and various advantages of the aspects and embodiments of the inventions are in the detailed description.

DESCRIPTION OF A PRESENTLY PREFERRED EMBODIMENT

As used herein, like reference characters will refer to like parts throughout the figures of the drawing.

As used herein, the words such as “needle” in the compound terms such as “needle means” are solely for the purpose of naming and distinguishing the particular means for accomplishing a function from another means for accomplishing a different purpose. For example, the term “needle means” is not to be construed as requiring any structure of a needle, but solely as the “means for engaging the ribbon a distance from the free end and operable to loop the ribbon about the gathered neck of the bag.”

As used herein, terms such as “left,” “right,” “clockwise,” “counter-clockwise,” “horizontal,” “vertical,” “up,” and “down” when used in reference to the drawings generally refer to orientation of the parts as oriented in the illustration of the embodiment and not necessarily during use of the illustrated apparatus. These terms used herein are meant only to refer to relative positions or orientations, for convenience, and are not to be understood to be in any manner otherwise limiting.

Referring first toFIGS. 1,2, and3of the drawing, a bag tying apparatus according to a presently preferred embodiment of the invention is generally designated by the numeral10. As will hereinafter be described in more detail, the bag tying apparatus10includes: a frame; a gathering means for gathering the open end of a bag into a neck; a holder-shear means for holding a free end of the ribbon adjacent to the gathered neck of the bag and, after the neck of the bag is tied, for cutting the ribbon; a needle means adjacent the holder-shear means, the needle means for engaging the ribbon a distance from the free end and operable to loop a strand of the ribbon about the gathered neck of the bag; a twister means having a hook adjacent the holder-shear means, the twister means for twisting the strand of the ribbon around the gathered neck of the bag; a holder-shear drive means for actuating the holder-shear means; and an over-travel compensation means operatively connected between the holder-shear drive means and the holder-shear means, the over-travel compensation means for compensating for over travel of the holder-shear drive means relative to the travel of the holder-shear means. The gathering means, the holder-shear means, the needle means, the twister means, the holder-shear drive means, and the over-travel compensation means are operatively supported by the frame.

A bag tying apparatus according to the invention has a frame for providing a rigid structure onto which the other elements of the bag tying apparatus can be mounted. As illustrated inFIGS. 1,2, and3, according to the presently preferred embodiment, for example, the bag tying apparatus10has a frame F.

A bag tying apparatus according to the invention has a gathering means for gathering the open end of a bag into a neck. As illustrated inFIGS. 1 and 2, according to the presently preferred embodiment, for example, the bag tying apparatus10has a gathering means having the structure of a gathering assembly20.

A bag tying apparatus according to the invention has a holder-shear means for holding a free end of the ribbon adjacent to the gathered neck of the bag and, after the neck of the bag is tied, for cutting the ribbon. According to the presently preferred embodiment, for example, the bag tying apparatus10has a holder-shear means having the structure of holder-shear assembly60as illustrated in the prior art bag tying apparatus10A ofFIG. 1A. A person of skill in the art will appreciate that the holder-shear assembly60illustrated inFIG. 1Acan be incorporated into the bag tying apparatus10illustrated inFIG. 1. In addition, the holder-shear assembly60will be hereinafter described in detail with reference toFIG. 4.

A bag tying apparatus according to the invention has a needle means adjacent the holder-shear means, the needle means for engaging the ribbon a distance from the free end and operable to loop a strand of the ribbon about the gathered neck of the bag. As illustrated inFIGS. 1 and 2, according to the presently preferred embodiment, for example, the bag tying apparatus10has a needle means having the structure of needle assembly40.

A bag tying apparatus according to the invention has a twister means adjacent the holder-shear means, the twister means for twisting the strand of the ribbon around the gathered neck of the bag. According to the presently preferred embodiment, for example, the bag tying apparatus10has a twister means having the structure of a twister assembly50as illustrated in the prior art bag tying apparatus10A ofFIG. 1A. A person of skill in the art will appreciate that the twister assembly50illustrated inFIG. 1Acan be incorporated into the bag tying apparatus10illustrated inFIG. 1.

A bag tying apparatus according to the invention has a holder-shear drive means for actuating the holder-shear means. According to the presently preferred embodiment, for example, the bag tying apparatus10has a holder-shear drive means having the structure of holder-shear drive assembly100. The holder-shear drive assembly100is operatively connected to the holder-shear assembly60. The holder-shear drive assembly100will be hereinafter described in detail with reference toFIGS. 5,6, and8-11.

A bag tying apparatus according to the invention has an over-travel compensation means operatively connected between the holder-shear drive means and the holder shear, the over-travel compensation means for compensating for over travel of the holder-shear drive means relative to the travel of the holder-shear means. According to the presently most preferred embodiment of the invention, the over-travel compensation means is operatively positioned within the holder-shear drive means. According to the presently preferred embodiment for example, the bag tying apparatus10has an over-travel compensation means having the structure of over-travel compensation assembly134. The over-travel compensation assembly134will be hereinafter described in detail with reference toFIGS. 5,6, and8-11.

In the bag tying apparatus10, the gathering assembly20, the holder-shear assembly60, the needle assembly40, the twister assembly50, the holder-shear drive assembly100, and the over-travel compensation assembly134are operatively supported by the frame F.

The details and cooperation of the gathering assembly20, the holder-shear assembly60, the needle assembly40, the twister assembly50, the holder-shear drive assembly100, and the over-travel compensation assembly134will be hereinafter described.

Bag Tying Apparatus10Connected to or Adjacent a Conveyor

The bag tying apparatus10is adapted to be mounted to or otherwise secured adjacent the side of a conveyor (not shown). The conveyor is for conveying a plurality of bags, each bag having a product, such as a loaf of bread, positioned therein. An example of such a relationship between a bag tying apparatus and a conveyor is illustrated in U.S. Pat. No. 5,483,134,FIG. 2, the disclosure of which is incorporated herein by reference in its entirety for all purposes. The conveyor carries a bagged product in rapid succession adjacent to the bag tying apparatus10such that the bag tying apparatus can gather and tie the neck of the bags.

In the prior art bag tying apparatus10A, a front discharge cover was difficult to open if it were blocked by a bag. In the presently most preferred embodiment of the bag tying apparatus10, a front discharge cover (not shown) opens to the conveyor side of the bag tying apparatus. The new cover swings up and out of the way on an arc, eliminating this problem while providing better access to the internals of the bag tying apparatus.

Bag Tying Apparatus10Having or Connected to a Ribbon Dispenser

As shown inFIGS. 1 and 2, the bag tying apparatus10uses a ribbon15to tie the neck of a bag. The ribbon15can be constructed of wire enclosed in paper or plastic or it can comprise a ribbon of plastic or any other suitable material for tying the neck of a bag.

The bag tying apparatus10preferably has a ribbon dispenser for dispensing a length of ribbon having a free end, in which case the ribbon dispenser is also attached to the frame F. According to the presently preferred embodiment, for example, the bag tying apparatus10has a ribbon dispenser39. As best illustrated inFIG. 1, the ribbon dispenser39includes ribbon pulleys41,41a, and41band at a spool41cmounted on spool shaft41A. The ribbon15extends from the spool41caround the pulleys41,41a, and41b, through the needle assembly40, and to the holder-shear assembly60. The ribbon dispenser39is operatively connected to the frame F. It is also contemplated that the bag tying apparatus can be selectively and operatively connected to a ribbon dispenser that is independently supported adjacent the conveyor.

Bag Tying Apparatus10Having or Connected to a Motor

The bag tying apparatus10preferably includes a motor160for driving the drive shaft162of the holder-shear drive assembly100, in which case the motor160is attached to the frame F. It is also contemplated that a motor for the holder-shear drive assembly100of the bag tying apparatus10can be selectively and operatively connected to a motor independently supported adjacent the conveyor. The bag tying apparatus10also preferably includes a motor, which can be the same or different than motor160, operatively connected for driving the needle assembly40and the twister assembly50. Most preferably, the motor160is a brushless motor.

Head of Bag Tying Apparatus10is Preferably Removable from Frame

Referring toFIGS. 1,2, and3, the bag tying apparatus10preferably has a head H that is removable from the frame F. The head H preferably includes at least the gathering assembly20, the holder-shear assembly60, the needle assembly40, the twister assembly50, the holder-shear drive assembly100, and the over-travel compensation assembly134mounted on upper and lower face plates16and17. The head H of the bag tying apparatus10is adapted to be removably secured in the bag tying apparatus10. For example, the head H can be removably attached to frame F by suitable quick connect devices, such as clamps (not shown), at20aon the frame F. Thus, the head H of the bag tying apparatus10is preferably separable from the rest of the bag tying apparatus10. With this approach, the “guts” of the bag tying apparatus10, that is, at least the gathering assembly20, the holder-shear assembly60, the needle assembly40, the twister assembly50, the holder-shear driver assembly100, and the over-travel compensation assembly134mounted on the upper and lower face plates16and17, can be removed from the frame F, which can remain attached to or adjacent to a conveyor. A replacement head H can be quickly substituted in the bag tying apparatus10so that bag tying can continue with minimal interruption.

Preferably, various sensors and controls of the bag tying apparatus10are also included on the head H instead of being located remotely. More preferably, the various sensors and controls are located on an exposed surface of the head H for easy access or repair.

Preferably, the ribbon dispenser39is not part of the head H, which makes the head lighter and easier to replace.

Operation of Bag Tying Apparatus10

Referring toFIG. 1of the bag tying apparatus10, as will be hereinafter explained in detail, the gathering assembly20gathers the neck of a bag along a path12to a position adjacent the needle assembly40, the twister assembly50, and the holder-shear assembly60. When the neck of a bag is gathered, the free end of a ribbon15of a wire-like material is gripped in holder-shear assembly60. The neck of the bag moves through a neck path12between the upper faceplate16and the lower faceplate17for drawing the bag to a controlled tension about the contents thereof Needle assembly40wraps the ribbon15about the gathered neck of the bag and twister assembly50twists a portion of the ribbon15about the neck of the bag.

Referring toFIGS. 1 and 2of the drawing, gathering assembly20comprises, in a preferred embodiment of the invention, an upper gathering belt22routed around a driven pulley24and idler pulleys26,27,28, and29. The gathering assembly20further comprises a lower gathering belt32routed around a driven pulley34and idler pulleys36,37, and38. As best illustrated inFIG. 1of the drawing, the portion of the upper gathering belt22that extends between idler pulleys28and29is parallel and closely spaced relative to the portion of the lower gathering belt32that extends between driven pulley34and idler pulley36. In the illustrated embodiment, gathering belts22and32move a bag neck along the neck path12in a plane.

It should be appreciated that the path of the upper gathering belt22from roller26around roller27and roller28and the path of the lower gathering belt32from roller38around roller37and roller36are symmetrical paths on the in-feed adjacent rollers28and36. This symmetrical arrangement assures that the portion of the upper gathering belt22that extends between idler pulleys28and29moves at an equal speed to the portion of the lower gathering belt32that extends between driven pulley34and idler pulley36. Routing the upper and lower gathering belts22and32along symmetrical paths at the in-feed adjacent rollers28and36reduces belt wear caused by the belts rubbing against each other at different linear velocities.

The path of the upper gathering belt22from roller26around roller27and roller28and the path of the lower gathering belt32from roller38around roller37and roller36are substantially mirror images of the other. However, roller36is mounted to lower faceplate17to permit separation of rollers28and36if a heel on a loaf of bread in a bag falls down into the nip between rollers28and36. Lower roller36is urged by a spring upwardly toward roller28, but the lower roller36can pivot downwardly if necessary to allow a heel or other obstruction to pass through the nip between rollers28and36, which otherwise could cause the heel to jam the rollers or tear the bag.

A continuously supported upper belt guide179urges upper gathering belt22downwardly to tightly hold the bag between the upper and lower gathering belts22and32to prevent the bag from being pulled down into a twister hook54of the twister assembly50during the tie cycle. The upper belt guide179also reduces wear on the lower gathering belt32by spreading the contact area over a larger area, reducing the pressure. A pressure pad is resiliently urged upwardly by springs acting through bell cranks (not shown), which maintain belts22and32in frictional engagement with the neck of a bag to be tied.

As the trailing edge of the neck of a bag passes over the end of switch arm88, switch arm88will move back to the position illustrated inFIG. 1to send a signal to a microcontroller for starting a new tying cycle. Other and further switching devices may be employed to initiate a tying cycle, such as use an ultrasonic sensor to detect the bag rather than the trigger arm/switch combination, which can eliminate mechanical wear and problems of getting the switch to actuate at the proper position.

The upper and lower gathering belts22and32on the bag tying apparatus10are mounted close to the upper and lower faceplates16and17to provide a straight ribbon path between the needle assembly40, holder-shear assembly60, and twister assembly50. This assures that the twister assembly50is not under the belts22and32, which could cause the tie material15to be drawn against the side of the lower belt32as it is being tied. This also allows the holder-shear assembly60to be raised ¼″ and the twister assembly50to be raised 3/16″ relative to the spacing in the prior art bag tying apparatus10A illustrated inFIG. 1A. This uses approximately ½″ less of ribbon and provides a tighter bag neck closure. The use of less ribbon can mean a significant saving in consumables for the end user.

Continuing to refer toFIGS. 1 and 2, the gathering assembly20also includes a bag stop lever80mounted on a shaft for rotary movement about a horizontal axis, which holds the bag during the tie cycle. The stop is operated by the needle assembly40, which has a slightly modified motion relative to the prior art bag tying apparatus10A illustrated inFIG. 1A. In the “home” position, the needle42of the needle assembly40(as will be hereinafter described in detail) is rotated approximately 20 degrees further toward the downstream side of the bag tying apparatus10. In this position, the bag stop lever80is held out of the bag neck path12by a lever contacting the needle42. Once a bag passes the bag switch88the needle42is moved forward such that the bag stop lever80is no longer in contact with the needle, allowing the bag stop lever to drop and hold the bag neck. Once the tie cycle is complete, the needle42rotates back, lifting the bag stop lever80out of the way. This design provides more holding force on the neck of the bag.

A needle assembly40, best illustrated inFIGS. 1 and 2, is positioned for wrapping a strand of ribbon material15around a gathered neck of a bag. The needle assembly40comprises a needle42carrying idler rollers44,44a, and44b. Referring briefly toFIG. 1A, the needle42is mounted on the output shaft45of a gearbox driven by a motor. Referring back toFIGS. 1 and 2, needle42is shown in a home position. The motor moves needle42from the home position shown to a lowered position, rotated clockwise from the home position with the eye43(or similar) rotated adjacent holder-shear assembly60. The motor then reverses and moves the needle42back to the home position illustrated inFIGS. 1 and 2. For a fuller explanation of the needle assembly, see U.S. Pat. No. 5,483,134 issued Jan. 9, 1996 to Jimmy R. Frazier, John D. Richardson, and Greg P. Coxsey entitled “RIBBON SENSING DEVICE FOR BAG TYER,” which is incorporated herein by reference in its entirety.

Referring toFIGS. 1Aof the drawing, a twister assembly50comprises a twister shaft52rotatably mounted in a bearing53having a hook54on one end thereof and a pulley55on the other end. A drive pulley56is mounted on the drive shaft of a motor and drives pulley55through a belt58. For a fuller explanation of the needle assembly, see U.S. Pat. No. 5,483,134 issued Jan. 9, 1996 to Jimmy R. Frazier, John D. Richardson, and Greg P. Coxsey entitled “RIBBON SENSING DEVICE FOR BAG TYER,” which is incorporated herein by reference in its entirety. A person of skill in the art will appreciate that the twister assembly50illustrated inFIG. 1Acan be incorporated into the bag tying apparatus10illustrated inFIG. 1.

Referring toFIG. 4of the drawing, a holder-shear assembly, generally designated by the numeral60, comprises a holder-shear assembly of the type disclosed in U.S. Pat. No. 4,856,258 entitled WIRE TYING DEVICE, which issued Aug. 15, 1989, to Charles E. Burford and Jimmy R. Frazier, which is hereby incorporated by reference in its entirety. The holder-shear assembly60comprises a gripper arm62having a gripper finger64on one end thereof rotatably secured to a mounting plate66by bolt65. A pair of anvils68and69is formed on the end of mounting plate66, each being associated with shear surfaces68aand69ato grip and cut a strand of ribbon (not shown inFIG. 4). The free end of a ribbon is gripped between the end of gripper finger64and anvil68or69, depending on which direction the gripper finger64is shifted. When the needle assembly40wraps an intermediate section of the ribbon15around the gathered neck of a bag, the ribbon will be positioned between gripper finger64and the other anvil68or69. When gripper finger64is shifted to its opposite position, the ribbon will be cut and the free end of the strand of ribbon will be gripped between gripper finger64and anvil68or69.

Holder-Shear Drive Assembly and Over-Travel Compensation Assembly

According to the invention, a holder-shear drive means is provided for actuating the holder-shear assembly and an over-travel compensation means operatively connected between the holder-shear drive means and the holder-shear means, the over-travel compensation means for compensating for over travel of the holder-shear drive means relative to the travel of the holder-shear means. According to the presently preferred embodiment, for example, the bag tying apparatus10has a holder-shear drive means having the structure of holder-shear drive assembly100and an over-travel compensation means having the structure of over-travel compensation assembly134.

Referring toFIG. 5of the drawing, a holder-shear drive assembly100according to the invention has an eccentric element149mounted fixedly on a drive shaft162, the eccentric element rotated by the drive shaft. A housing122is slidingly mounted on the eccentric element149, the housing reciprocated along a housing path by the rotating eccentric element. A reciprocating member180is operatively connected to the housing to be reciprocated by the housing, the reciprocating member operatively connected to the holder-shear assembly60to actuate the holder-shear assembly. The reciprocating member180operable to travel along a reciprocating member path, the reciprocating member limited in its travel at both ends of the reciprocating member path by the holder-shear assembly, wherein the housing path is greater than the reciprocating member path, and wherein the housing over-travels the reciprocating member.

According to the invention, the bag tying apparatus10includes an over-travel compensation assembly134. The over-travel compensation assembly134connects the housing122to the reciprocating member180, wherein the over-travel compensation assembly134is operable to allow the housing122to move in relation to the reciprocating member180when the reciprocating member is at either of the ends of the reciprocating member path, whereby the housing is allowed to travel along the housing path that is greater than the reciprocating member path.

FIG. 5is a perspective view of the holder-shear drive assembly100and the over-travel compensation assembly134(not showing spring145, washer144, and tensioning nut143, which are illustrated inFIGS. 8-11).FIG. 6is an exploded perspective view of the holder-shear drive assembly100and the over-travel compensation assembly134(not showing spring145, washer144, and tensioning nut143, which are illustrated inFIGS. 8-11.FIG. 7is an exploded view of a cam assembly120including the housing122of the holder-shear drive assembly100and an actuating arm135, bolt140, and pivot spacer168of the over-travel compensation assembly134.FIGS. 8-11show the holder-shear drive assembly100and the over-travel compensation assembly134at various points in the rotation of the drive shaft162, orbit of housing122, and translation of reciprocating member180and lever arm135.

Holder-Shear Drive Assembly

Referring toFIG. 5, the holder-shear drive assembly100includes a cam assembly120and a reciprocating member180.

The cam assembly120and the reciprocating member180are operatively mounted on mounting plate110. A side plate115provides additional structural stability for this mounting. Plate110has a central opening111and a plurality of threaded apertures114for receiving set screws for connecting an upper end of the motor160to the mounting plate110. Referring toFIG. 6, mounting plate110has internally threaded apertures114, which are adapted to receive bolts for attaching the mounting plate110to the upper faceplate16of bag tying apparatus10. The side plate115is bolted to or otherwise secured to an edge of the mounting plate110. Side plate115has internally threaded apertures116formed in an edge thereon, which receives bolts for attaching side plate115to an upper faceplate16of a bag tying apparatus10.

As best shown inFIGS. 6 and 7, the cam assembly120includes an eccentric element149, a bearing170, and the housing122.

The eccentric element149includes a lower eccentric base155and an upper eccentric cap150. The lower eccentric base155is mounted on the drive shaft162of motor160(where the motor160is not shown inFIG. 7). Lower eccentric base155has a passage158for receiving motor drive shaft162and internally threaded passages159for receiving setscrews152for securing the eccentric cap150to eccentric base155, which are secured to the shaft162of motor160by a setscrew161. A shoulder157extends outwardly from the generally cylindrical outer surface156of base155and engages the lower surface172of bearing170when eccentric base155is positioned in the central opening173of the bearing170.

Upper eccentric cap150of the eccentric element149has a passage151for receiving motor drive shaft162and counter sunk passages153for receiving setscrews152, which are received in internally threaded passages159in lower eccentric base155. Upper eccentric cap150also is provided with a socket formed in the lower surface for receiving the upper end of eccentric base155.

The outer lower edge of bearing170engages shoulder126on inner wall125of housing122when bearing170is positioned in the passage through housing122and a snap ring (not shown) positioned in a groove127engages the outer upper edge of bearing170. The lower surface124of housing122is spaced from the upper surface of mounting plate110, as is the lower surface of arm167on bracket165. The eccentric elements150and155are secured to and supported by setscrew161to motor shaft162.

Referring toFIGS. 5,6, and7, the housing122includes a body having an upper surface123, a lower surface124, and an internal cylindrical wall125. The wall125has a shoulder126extending inwardly adjacent the lower surface124of housing122and a snap ring groove127adjacent upper surface123of housing122. A snap ring (not shown) can be positioned in the snap ring groove127to restrain the bearing170.

The rear end of reciprocating member180is supported by a pin182, which is allowed to reciprocate through an opening in a block184secured to side plate115, while the front end of reciprocating member180is supported by a bearing in an opening formed in lower faceplate17. A flat surface185is formed on a central portion of reciprocating member180to facilitate connecting to flange166on bracket165.

The cam assembly120is operatively connected to reciprocate the reciprocating member180. As best shown inFIGS. 6 and 7, the housing122includes an actuating lever130for use in operatively connecting the housing122to reciprocate the reciprocating member180. An elongated channel131is formed in the side of the housing122and the actuating lever130. A groove128is formed in housing122adjacent the lever130and a slot129is formed in actuating lever130adjacent the groove128.

Over-Travel Compensation Assembly

The over-travel compensation assembly134preferably includes an actuating arm135, a bolt140, a spring145, a washer144, and a tensioning nut143. As best shown inFIGS. 5,6, and7, the bolt140connects the actuating arm135to the housing122. The bolt140has a head141and a shank142. The shank142of the bolt140extends through a slot129when head141is positioned in groove128.

The actuating arm135has a boss136formed on one end thereof and a hole138for receiving a pivot shaft168. The actuating arm135has a passage137into which the shank142of bolt140extends for positioning actuating arm135in the elongated channel131formed in actuating lever130on housing122. As best illustrated inFIGS. 8-11, the bolt140has a spring145, washer144, and a tensioning nut143on the shank142for urging actuating arm135into the elongated channel131formed in actuating lever130. The lower end of pivot shaft168is secured to arm167on bracket165, which has a flange166in which elongated openings164are formed to receive bolts169screwed into threaded holes in reciprocating member180.

The actuator arm135has a rocker face139, which abuts channel131, seen best inFIG. 6, which provides for a rocking motion, or angular movement, of the actuator arm135in relation to the lever130of housing122. The spring145is attached and compressed by washer144and tensioning nut143on the exposed side of the pivot shaft168. The actuating arm135is connected to a bracket165, which is attached to the reciprocating member180. The actuating arm135is preferably formed of Delrin® acetyl resin commercially available from DuPont.

Proximity Switch

The upper eccentric cap150has a short proximity switch actuator lug146and a long proximity switch actuator lug148projecting in opposite directions from motor drive shaft162. The ends of lugs146and148are equal distances from the axis of motor shaft162. When the end of the long proximity switch actuator lug148is positioned adjacent proximity switch190supported by bracket192secured to side plate115, as illustrated inFIGS. 5 and 11, the high side of the eccentric element urges reciprocating member180to the extended position (to the right as viewed inFIG. 11). When the end of the short proximity switch actuator lug146is positioned adjacent proximity switch190, as illustrated inFIG. 8, the high side of the eccentric element urges reciprocating member180to the retracted position (to the left as viewed inFIG. 8).

Motions of Holder-Shear and Over-Travel Compensation Assemblies

As shown inFIGS. 8-11, the eccentric element149, comprising upper eccentric cap150and lower eccentric base155, is confined in bearing170in housing122. As the motor shaft162turns, rotating the eccentric element149through 180 degrees, the housing122translates side to side. The housing122also moves up and down, such that the housing moves in an orbital path as the shaft162and the eccentric element149rotates. The housing122is also free to pivot in the up/down direction, allowing it to move angularly in relation to the reciprocating member180, arm167, and pivoting actuating arm135. The housing122is operatively connected to actuating aim135, which is in turn operatively connected to a pivot shaft168. Actuating arm135pivots about pivot shaft168. The housing122and actuating arm135are operatively connected to one another via the over-travel compensation assembly134, including in a preferred embodiment, bolt140, head141, tensioning nut143, washer144, and spring145.

As the eccentric element149rotates, the reciprocating member180is pushed side to side as the housing122is free to pivot in the up/down direction. Since the force to move the reciprocating member180is being transferred from the eccentric element149via the actuator arm135, when the holder-shear assembly60bottoms-out, the over-travel compensation assembly134takes up the additional travel of the housing122. In this way, the motor160can turn without feeling the holder-shear assembly60bottom out, that is, without bending or placing undue torque on other elements in the bag tying apparatus10. This over-travel compensation assembly134also alleviates the problem of critical adjustments since it can allow a large amount of over-travel without problems.

Turning toFIGS. 8-11,FIG. 8shows the holder-shear drive assembly100in a first position with the drive shaft162at its right-most position, and with the orbiting housing122, actuator arm135, and reciprocating member180at their left-most positions. That is, the reciprocating member180has completed its leftward travel, and gripper arm62of the holder-shear assembly60is engaged with anvil68. Similarly, the housing122and the over-travel compensation assembly134are at their left-most positions. The reciprocating member180has a shorter distance of travel than the housing122. The housing122of the holder-shear assembly100over-travels in comparison to the reciprocating member180connected to the holder-shear assembly60. This over-travel is compensated for, or allowed for, by the over-travel compensation assembly134. InFIG. 8, the actuator arm135has pivoted in relation to arm167of the reciprocating member180. Similarly, the housing122is free to pivot as well. These elements continue to move to the left-most position even though the reciprocating member180has stopped its leftward motion. The actuator arm135has a rocker face139, which abuts channel131, seen best inFIG. 6, which provides for a rocking motion, or angular movement, of the actuator arm135in relation to the lever130of housing122. As the actuator arm135rocks in relation to the lever130, the spring145is compressed slightly.

InFIG. 9, the shaft162has rotated 90 degrees to a top position. In this position, the reciprocating member180, which is attached to the holder-shear assembly60, particularly at gripper arm62via link75a, has traveled rightward and gripper arm62of the holder-shear assembly60is not engaged with an anvil68or69. Also in this position, note that the orbiting housing122, pivoting actuator arm135, reciprocating member180are moving in synch. The spring145operates to hold actuator arm135in contact with housing122along channel131.

InFIG. 10, the shaft162has rotated another 90 degrees to a right-most position, moving the eccentric element and therefore housing122to its right-most position, as shown. The reciprocating member180is also at its right-most position and has moved the gripper arm62such that it is in contact with the other anvil69. However, the gripper arm62of the holder-shear assembly moves into contact with anvil69before the reciprocating member180completes its path of travel. That is, the holder-shear assembly60bottoms-out before the reciprocating member180has completed its rightward movement. The housing122of the holder-shear assembly100over-travels in comparison to the reciprocating member180attached to the holder-shear assembly60. This over-travel is compensated for, or allowed for, by the over-travel compensation assembly134. InFIG. 10, the actuator arm135has pivoted, as has the housing122. These elements continue to move during rotation of the shaft162even though the reciprocating member180has stopped its motion. The actuator arm135has a rocker face139, which abuts channel131, seen best inFIG. 6, which provides for a rocking motion, or angular movement, of the actuator arm135in relation to the lever130of housing122. As the actuator arm135rocks in relation to the lever130, the spring145is compressed slightly. Note also, that the orbiting housing122has pivoted to some degree as well.

InFIG. 11, the shaft162has rotated another 90 degrees to its bottom position. The eccentric element149, housing122, actuator arm135and reciprocating member180have traveled leftward into a central position. These elements are situated with respect to one another much as inFIG. 9. The actuator arm has pivoted back to a home position, and is not pivoted along rocker face139in channel131.

Numerous modifications, alterations, subcombinations, and changes can be made in the invention without departing from the spirit and scope of the invention as set forth in the appended claims. It is the intention to cover all embodiments and forms of the invention within the allowable scope of the claims.