Film Tension Apparatus And Supply Roll Support For Stretch Wrapping Machines

Abstract

A film dispenser for stretch wrapping machines includes at least one roller and a first brake engageable with a braking surface the one roller. The first brake may include a flat brake pad that is pivotally movable for engagement with the braking surface, and is adjustable between a first configuration engaged with the braking surface and applying a first braking force, and a second configuration disengaged from the braking surface or only minimally engaged with the braking surface such that any braking force applied is substantially less than the first braking force.

Description

TECHNICAL FIELD

The present invention relates generally to stretch wrapping loads and, more particularly, to improved methods and apparatus for applying film tension and supporting a film supply roll in stretch wrapping machines.

BACKGROUND

Various packaging techniques have been used to assemble a load of unit products and subsequently wrap them for transportation, storage, containment and stabilization, protection and waterproofing. Products are often stacked as a load on a pallet to simplify handling of the products. The pallet load is commonly wrapped with stretch wrap packaging material. One system uses stretch wrapping machines to stretch, dispense, and wrap stretch packaging material around a load. Stretch wrapping can be performed as an inline, automated packaging technique that dispenses and wraps packaging material in a stretched condition around a load on a pallet to cover and contain the load. Pallet stretch wrapping, whether accomplished by a turntable, a rotating arm, or by a vertically movable rotating ring, typically covers the vertical sides of the load with a stretchable film, such as polyethylene film. In each of these arrangements, relative rotation is provided between the load and the packaging material dispenser to wrap packaging material around the sides of the load.

It is generally desirable to stretch the film material prior to wrapping the load. In some machines, pre-stretching of the film is accomplished by first and second pre-stretch rollers that rotate at different speeds so that film material passing between the two rollers is stretched prior to application to a load. In other machines, pre-stretching of the film may be accomplished by applying braking forces to a film web extending between a supply roll and the load.

Previous methods and apparatus for stretching film material through the application of braking forces have been unsatisfactory. For example, difficulties have been experienced controlling the braking force on a tension roller that stretches film between a supply roll and a load. These variations may be caused by fluctuations in forces in the film web due to the geometry of the load as the film web is being applied by relative rotation between the load and the film dispenser. Oscillation of the film supply roll on a support post may also cause force variations in the film web. These force variations can occur at different wrapping speeds due to the gradual reduction in the mass of the film roll as film is used up. Other force variations may result from the engagement between a brake pad used to apply a braking force to the tension roller as film is applied to a load.

Accordingly, there is a need for improved methods and apparatus for overcoming these and other drawbacks of conventional stretch wrapping machines.

SUMMARY

The present invention overcomes the foregoing and other shortcomings and drawbacks of apparatus and methods heretofore known for use in stretch wrapping loads. While the invention will be described in connection with certain embodiments, it will be understood that the invention is not limited to these embodiments. On the contrary, the invention includes all alternatives, modifications and equivalents as may be included within the spirit and scope of the present invention.

According to one aspect of the present disclosure, a film dispenser for stretch wrapping machines includes at least one roller and a first brake engageable with a braking surface the one roller. The first brake is adjustable between a first configuration engaged with the braking surface and applying a first braking force to the braking surface, and a second configuration disengaged from the braking surface or only minimally engaged with the braking surface such that any braking force applied is substantially less than the first braking force. In one embodiment, the first brake may be an electrically-actuated brake. In another embodiment, the first brake may include a flat brake pad that is pivotally movable about a pivot axis spaced from the roller such that the brake pad is movable into engagement with the braking surface generally along a radial direction of the roller.

In another aspect, a supply roll support for a film dispenser includes an elongate post sized to receive a roll of film thereon, and a pliable sheet coupled with the outer peripheral surface of the post and extending around at least a portion of the outer peripheral surface. At least a portion of the pliable sheet is spaced radially outwardly from the outer peripheral surface for engagement with the inner diameter of a supply roll supported on the post.

The above and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the general description of the invention given above, and the detailed description given below, serve to explain the principles of the invention.

FIG. 1 is a perspective view of an exemplary stretch wrapping machine in accordance with the principles of the present invention.

FIG. 2 is an exploded perspective view of an exemplary dispenser of the stretch wrapping machine of FIG. 1, illustrating an exemplary brake assembly and an exemplary film roll post in accordance with the principles of the present invention.

FIG. 3 is a perspective view of an exemplary brake assembly of the dispenser of FIG. 2.

FIG. 4A is a cross-sectional view of the brake assembly of FIG. 3, taken along line 4A-4A.

FIG. 4B is a cross-sectional view of the brake assembly, similar to FIG. 4A, illustrating operation of the brake assembly with increased preload.

FIG. 4C is a cross-sectional view of the brake assembly, similar to FIG. 4A, illustrating disengagement of the brake pad.

FIG. 5 is a partial top view of the brake assembly of FIG. 4C, taken along line 5-5.

FIG. 6A is a schematic illustration of the dispenser of FIG. 2, illustrating an exemplary path of film material through the dispenser.

FIG. 6B is a schematic illustration similar to FIG. 6A, illustrating an alternative film path through the dispenser.

FIG. 7 is a perspective view of a second exemplary brake assembly in accordance with the principles of the present invention.

FIG. 8 is a top plan view of the brake assembly of FIG. 7.

FIG. 9 depicts a perspective view of a third exemplary brake assembly in accordance with the principles of the present invention.

FIG. 10A is a side elevation view of the brake assembly of FIG. 9.

FIG. 10B is a side elevation view similar to FIG. 10A, depicting the brake assembly of FIG. 9 in an engaged condition.

FIG. 11 is a perspective view of a fourth exemplary brake assembly in accordance with the principles of the present invention.

FIG. 12A is a side elevation view of the brake assembly of FIG. 11.

FIG. 12B is a side elevation view similar to FIG. 12A, depicting the brake assembly of FIG. 11 in an engaged condition.

FIG. 13 is an enlarged detail view of the bottom of the tension roller of the brake assembly of FIG. 11.

DETAILED DESCRIPTION

FIG. 1 depicts an exemplary stretch wrapping machine 10 including a film dispenser 12 for applying pre-stretched film material 14 to a load 16 from a supply roll 18. The dispenser 12 is coupled to a vertically extending mast 20. During wrapping of the load 16, the dispenser 12 moves up and down the mast 20 while paying out film material 14 so that the film material 14 is spirally wrapped around the load 16. The stretch wrapping machine 10 further includes a load support 22 having a turntable 24 for rotating the load 16 supported thereon relative to the dispenser 12 during wrapping of the load 16.

FIG. 2 is an exploded perspective view of the exemplary film dispenser 12 of FIG. 1. The film dispenser 12 includes a bottom plate 30 supporting the components of the dispenser 12, and a supply roll post 32 coupled with the bottom plate 30. The dispenser 12 further includes first and second guide rollers 34, 36 supported in journal bearings 38 coupled between the bottom plate 30 and a top plate 40 spaced from the bottom plate 30. The dispenser 12 further includes a brake assembly 42 supported on the top plate 40 and enclosed by a removable cover 44. A tension roller 46 extends between the bottom plate 30 and a bearing plate 48 secured to the top plate 40. The tension roller 46 includes a circumferentially extending film engaging surface 50 that contacts film material 14 dispensed from the supply roll 18, and a circumferential braking surface 52 (see FIG. 4A).

With continued reference to FIG. 2, and referring further to FIGS. 1, 6A, and 6B, film material 14 from the supply roll 18 is directed along a film path around one or more of the guide rollers 34, 36 and around the tension roller 46 before being directed toward a load 16 on the turntable 24 for winding upon the load 16. FIGS. 6A and 6B illustrate two exemplary paths for threading film material 14 through the dispenser 12 for application to a load 16. In FIG. 6A, the supply roll 18 has been placed over the support post 32 such that film material 14 is dispensed by rotation of the supply roll 18 in a clockwise direction about the support post 32. In FIG. 6B, the supply roll 18 has been placed over the support post 32 such that film material 14 is dispensed from the supply roll 18 during counterclockwise rotation of the supply roll 18 about the support post 32. The tension roller 46 may be coated with a friction material 54 (see FIG. 4A) in the region of the film engaging surface 50 to increase friction between the tension roller 46 and the film material 14, or to prevent slipping of the film material 14 circumferentially around the tension roller 46.

Referring now to FIGS. 3, 4A, and 5, the brake assembly 42 includes first brake 60 having a brake pad 62 adjustably supported for engagement with the braking surface 52 of the tension roller 46, whereby the brake pad 62 is selectively adjustable between a first configuration engaged with the braking surface 52 such that the brake pad 62 applies a first braking force to the tension roller 46, and a second configuration disengaged from the braking surface 52, or only minimally engaging the braking surface 52 such that a braking force in the second configuration is substantially less than the first braking force. As contemplated herein, the substantially less braking force caused by the brake pad 62 in the second configuration may only be sufficient to prevent free rolling of the tension roller 46, but in no way adversely affects normal operation of the tension roller 46.

In the embodiment shown, the brake pad 62 has a generally flat contact surface 64 and is supported on a brake plate 66 for movement toward and away from the braking surface 52 of the tension roller 46 generally along a radial direction of the tension roller 46. To this end, the brake plate 66 is pivotally coupled between the bearing plate 48 and the top plate 40 at a distance spaced from the tension roller 46 such that the brake pad 62 is constrained for movement toward and away from the braking surface 52 of the tension roller 46 generally along a radial direction of the tension roller 46.

In one embodiment, the brake plate 66 may be pivotally coupled between the top plate 40 and the bearing plate 48 by a pin connection. Alternatively, the brake plate 66 may be formed with tabs configured to be received in complementary structure on the top plate 40 and bearing plate 48 to provide a hinge joint. While the brake assembly 42 has been shown and described herein as having a brake plate 66 pivotally coupled proximate the tension roller 46 to constrain the brake pad 62 for movement toward and away from the braking surface 52 along a generally radial direction, it will be appreciated that various other structure and methods for constraining movement of the brake pad 62 along a generally radial direction may alternatively be used.

The brake assembly 42 further includes a spring 70 biasing the brake plate 66 and brake pad 62 in a direction toward the braking surface 52 of the tension roller 46. The spring 70 is mounted on a shaft 72 extending generally radially from the braking surface 52. The shaft 72 is coupled with the bearing plate 48 by a journal 74 for rotation of the shaft 72 about its longitudinal axis. A length of the shaft includes screw threads 76, and the shaft 72 supports a pressure block 78 having a tapped aperture 80 for receiving the threads 76 of the shaft 72 such that when the shaft 72 is rotated the pressure block 78 may be moved axially along the shaft 72 to increase or decrease a preload of the spring 70 and thereby vary a biasing force of the spring 70 against the brake plate 66 and brake pad 62. A knob 82 or other control surface may be provided on an end of the shaft 72 opposite the threaded portion, to facilitate rotating the shaft 72 to vary the preload of the spring 70.

In the embodiment shown, movement of the pressure block 78 along the shaft 72 is guided by a guide rod 84 extending between the brake plate 66 and distal end 86 of the bearing plate 48 supporting the shaft 72. Accordingly, the braking force applied by the brake pad 62 to the circumferential braking surface 52 of the tension roller 46 may be selectively adjusted by manually turning the knob 82 of the shaft 72 to apply a preload to the brake pad 62 with the spring 70. FIG. 4B depicts brake assembly 42 in a condition wherein the preload applied by spring 70 has been increased relative to the preload depicted in FIG. 4A by rotating knob 82.

In one embodiment, the brake assembly 42 may further include an indicator 90 that provides a visual indication of the amount of preload selected by manually manipulating the knob 82, as depicted in FIGS. 2, 3, and 5. In the embodiment shown, the indicator 90 includes an indicator arm 92 pivotally coupled to the pressure block 78 for movement with the pressure block 78 as the shaft knob 82 is manipulated to increase or decrease preload of the spring 70. A first end 92a of the indicator arm 92 extends through an aperture 94 in the top plate 40, and a second end 92b of the indicator arm 92 is visible through a slot 96 in the cover 44 when the cover 44 is secured to the dispenser 12. The cover 44 may include graduations or other visual features adjacent the slot 96 so that the position of the second end 92b of the indicator arm 92 viewed through the slot 96 may give a visual indication of the amount of preload applied by the spring 70.

Referring now to FIGS. 2-5, the brake assembly 42 may further include a release mechanism 100 that enables a user to move the brake pad 62 from the first configuration engaged with the braking surface 52, to the second configuration disengaged from the braking surface 52 (or only minimally engaging the braking surface 52), as depicted generally in FIG. 4C. In the embodiment shown, the release mechanism 100 includes a lever arm 102 pivotally coupled to the top plate 40, such as by a pivot pin 104. A cam roller 106 is mounted to the lever arm 102 for engagement with a cam surface 108 of a cam bracket 110 extending upwardly from the pressure block 78. A distal end of the lever arm 102, opposite the pivot pin 104, includes a handle portion 112 whereby a user may apply force to the handle portion 112 to engage the cam surface 108 of the cam bracket 110 with the cam roller 106 during movement of the lever arm 102 from a first position depicted in FIGS. 4A and 4B, in a direction toward top plate 40 to a second position depicted in FIG. 4C. As the cam roller 106 engages the cam surface 108, the pressure block 78 and shaft 72 are forced away from the tension roller 46, thereby removing the bias of the spring 70 against the brake plate 66 such that the brake pad 62 can move to the second configuration away from the braking surface 52. In this configuration, the brake pad 62 either does not engage the braking surface 52, or only applies minimal force to the braking surface 52 as described above. When the lever arm 102 is moved from the second position depicted in FIG. 4C toward the first position depicted in FIGS. 4A and 4B, movement of the lever arm 102 is limited by engagement between a transverse stop member 114 and a vertically extending standoff 116. The distal end 166a of standoff 116 is threaded to receive a nut 118 for securing the cover 44 over the brake assembly 42, as depicted in FIGS. 4A-4C.

With continued reference to FIGS. 3 and 4A-4C, and referring further to FIG. 5, the brake assembly 42 may further include a second brake that also engages the circumferential braking surface 52 of the tension roller 46. In the embodiment shown, the second brake comprises a flexible band 120 engaging at least a portion of the circumferential braking surface 52. One end 120a of the band 120 is secured to a leg 122 of the bearing plate 48, although it will be appreciated that the band 120 may be secured to any other suitable structure. A second end 120b of the band 120 is secured to a post 124 coupled with the top plate 40 of the dispenser 12. In the embodiment shown, the second end 120b of the band 120 is secured to the post 124 by a spring member 126, whereby the band 120 is biased by the spring member 126 into engagement with the circumferential braking surface 52 of the tension roller 46. The tension of the band 120 against the circumferential braking surface 52 may be selectively adjusted by adjusting the tension in the spring member 126. The second brake applies a braking force against the circumferential braking surface 52 that is substantially less than the braking force of the first brake. In one embodiment, the braking force of the second brake is selected to prevent free rolling of the tension roller 46 while otherwise allowing the tension roller 46 to be rotated during threading of film 14 through the dispenser 12. Alternatively, the braking force of the second brake may be selected to provide a minimum resistance to rotation of tension roller 46 that will not cause film 14 to be pulled out of clamp structure that initially secures the film 14 to the load 16 when wrapping of the load 16 with the film 14 is started. In use, the second brake therefore prevents free rolling of the tension roller 46 when the first brake is in the second configuration and disengaged, or substantially less engaged, than the first configuration.

Referring now to FIGS. 7 and 8, a second exemplary embodiment of a brake assembly 130 in accordance with the principles of the present invention is described. In this embodiment, a flat brake pad 132 is supported on a brake arm 134 for pivotal movement with the brake arm 134 about a pivot axis 136 spaced from the tension roller 46 such that the brake pad 132 is movable into and out of engagement with the circumferential braking surface 52 of the tension roller 46, generally along a radial direction of the tension roller 46. In this embodiment, a first end 134a of the brake arm 134 is supported for pivotal movement about the pivot axis 136 by a tie rod 138. The tie rod 138 extends from a support block 141 coupled to the top plate 40a of the dispenser 12a, and is operatively coupled to a first end 134a of the brake arm 134. Accordingly, the pivot axis 136 is generally located at the intersection of the brake arm 134 and the tie rod 138. The brake assembly 130 further includes a solenoid actuator 140 operatively coupled to a second end 134b of the brake arm 134, at a location spaced from the pivot axis 136 and the brake pad 132. In the embodiment shown, the solenoid actuator 140 is coupled to the top plate 40a of the dispenser 12a by an L-shaped bracket 142. The output shaft, or armature, 144 of the solenoid 140 is secured to the second end 134b of the brake arm 134 by a coupling member 146. When the solenoid 140 is actuated to retract the armature 144, the brake arm 134 is moved about the pivot axis 136 such that the brake pad 132 is moved into engagement with the braking surface 52 of the tension roller 46. Because the solenoid 140 is spaced a distance from the pivot axis 136, braking force applied by the brake pad 132 to the braking surface of the tension roller 46 is increased by leverage of the brake arm 134 about the pivot axis 136.

Prior to the development of the embodiment depicted in FIGS. 7-8, it was believed that solenoids would not be suitable for use in braking a tension roller in a stretch wrapping operation because it was believed that a sufficient amount of force could not be developed over the relatively short stroke of the armature. The mechanical advantage provided by the increased leverage of the brake arm 134 about pivot axis 136 enables the solenoid actuator 140 to cause brake pad 132 to engage the braking surface 52 with sufficient force to enable control of the tension roller 46 as described herein.

In operation, the solenoid actuator 140 may be actuated to a first condition wherein the brake pad 132 engages the braking surface 52 with a first braking force that slows rotation of the tension roller 46 to stretch the film material 14 during wrapping of a load 16. The actuator 140 may also be actuated to a second condition wherein the brake pad 132 engages the braking surface 52 with a second braking force that is less than the first braking force, and which prevents free rolling of the tension roller 46 while still allowing the tension roller 42 to rotate when tension is applied to the film web 14, to facilitate threading film 14 through the dispenser 12a. Alternatively, the second braking force may be selected to provide a minimum resistance to rotation of tension roller 46 that will not cause film 14 to be pulled out of clamp structure that initially secures the film 14 to the load 16 when wrapping of the load 16 with the film 14 is started. The actuator 140 may also be actuatable to a third condition wherein the brake pad 132 engages the braking surface 52 of the tension roller 46 with a third braking force that locks the tension roller 46 against rotation. The third condition of the actuator 140 may be useful to facilitate intentional tearing or breaking the film 14 after a load 16 has been wrapped. The actuator 140 may also be actuatable to a fourth condition wherein the brake pad 132 is either disengaged from the braking surface 52, or the brake pad 132 only engages the braking surface 52 with a negligible force.

Actuator 140 may be remotely adjustable to vary the braking force applied to the braking surface 52 for the various operating conditions of the actuator 140 while the stretch wrapping machine 10 is in use. The actuator 140 may also be programmable to establish multiple settings of the actuator 140 corresponding to the various operating conditions. While the brake assembly 130 has been shown and described as including a solenoid actuator 140 for applying braking force to the tension roller 46 using a brake arm 134, it will be appreciated that various other actuators may alternatively be used to apply braking force to the tension roller 46. As non-limiting examples, such actuators may include linear or rotary actuators, magnetic, electronic, hydraulic, or pneumatic devices, or any other device suitable for applying force to move the brake arm 134 to bring the brake pad 132 into and out of engagement with the braking surface 52 of the tension roller 46.

In the embodiments depicted in FIGS. 2-5, 7, and 8, the brake pads engage only a portion of an area of the circumferential braking surface 52. The area can be represented in part by an arc that is defined by swinging a radius from the rotational axis of tension roller 46 through an acute angle.

Referring now to FIGS. 2 and 6A-6B, an exemplary film roll support post 32 in accordance with the principles of the present invention will be described. In the embodiment shown, the support post 32 is mounted to the dispenser 12 and is fixed against rotation about its longitudinal axis. The outer peripheral surface 150 of the post 32 is sized to be received within the inner diameter of a supply roll 18 mounted thereon. A first end 32a of the post 32 is secured to the bottom plate 30 of the film dispenser 12, and a thrust washer 152 and bushing 154 are provided thereon for engaging the core of a roll 18 of film material 14 placed over the post 32. The bushing 154 and thrust washer 152 facilitate rotation of the supply roll 18 around the post 32 as film material 14 is drawn from the supply roll 18 for application to a load 16 during wrapping. A selectively removable top cap 156 may be provided at the second end 32b of the post 32 to constrain the supply roll 18 thereon.

The post 32 further includes a sheet of pliable material 160 coupled with the outer peripheral surface 150 of the post 32 and extending generally circumferentially around at least a portion of the outer peripheral surface 150 of the post 32. At least a portion of the pliable sheet material 160 is secured to the circumferential surface 150 of the post 32, such as with fasteners 162, at a location generally opposite the tension roller 46 in the dispenser 12. The length of the pliable sheet 160 is selected such that a portion of the pliable sheet 160 generally opposite the fasteners 162 is bowed to extend outwardly away from the outer peripheral surface 150 of the post 32, and in a direction generally toward the tension roller 46. Accordingly, when a roll 18 of film material 14 is placed over the post 32, the outwardly bowed pliable material 160 biases the roll 18 of film material 14 in a direction toward the tension roller 46, as generally depicted in FIGS. 6A and 6B. The pliable sheet 160 is configured on the post 32 such that the pliable sheet 160 remains in engagement with the various sizes of cores 164 provided on supply rolls 18 used with the film dispenser 12, and applies a friction force to the cores sufficient to prevent the supply rolls 18 from freely rotating on the post 32. It has also been found that the pliable sheet 160 reduces or eliminates force variations in the film web 14 that would otherwise be present due to oscillating displacement of the film rolls 18 about the post 32.

While the post 32 has been shown and described herein with a pliable sheet 160 secured thereto for biasing the film roll 18 in a direction toward the tension roller 46, it will be appreciated that a tube of pliable material may alternatively be secured to post 32 in a manner similar to the pliable sheet 160, such that a portion of such tube extends outwardly from the post 32 to bias the film roll 18 in a direction toward tension roller 46.

While the exemplary embodiments shown and described with respect to FIGS. 2-8 include braking surfaces defined on circumferentially extending portions of a tension roller proximate the circumferential film engaging surface 50, and include brake pads that move generally along radial directions relative to a rotational axis of the tension roller, it will be appreciated that other embodiments in accordance with the principles of the present invention may include various other types of braking surfaces, and may have brake pads that move into engagement with braking surfaces other than along radial directions, as may be desired.

Referring now to FIGS. 9, 10A, and 10B, a third exemplary embodiment of a brake assembly 170 for use with a film dispenser 12b in accordance with the principles of the present invention is described. Various components of the film dispenser 12b are similar to those described above with respect to FIGS. 1-2 and 7-8, and similar features are similarly numbered. In this embodiment, the brake assembly 170 includes a brake disk 172 coupled with a distal end of the tension roller 46 such that the rotational axis 174 of the disk 172 corresponds with the rotational axis of the tension roller 46. A braking surface 176 is defined on a circumferentially extending portion of the disk 172, whereby the braking surface 176 extends circumferentially around the tension roller 46 relative to the circumferential film engaging surface 50.

The brake assembly 170 further includes a brake pad 178 supported on a first end 180a of a brake arm 180 for pivotal movement with the brake arm 180 about a pivot axis 182 spaced from the tension roller 46 such that the brake pad 178 is movable into and out of engagement with the braking surface 176 on disk 172, generally along a direction that is substantially parallel to the rotational axis 174 of the brake disk 172. In this embodiment, the first end 180a of the brake arm 180 is supported for pivotal movement about the pivot axis 182 by a shaft 184, wherein the pivot 182 axis is substantially perpendicular to the rotational axis 174 of the disk 172. The shaft 184 is supported by a pair of spaced apart journal brackets 186 coupled with the top plate 40 of the dispenser 12b. It will be appreciated, however that brake arm 180 may alternatively be supported by various other structure for pivotal movement about a pivot axis such that the brake pad 178 is movable into and out of engagement with the braking surface 176 on disk 172.

In another embodiment, brake pad 178 may alternatively be supported on an actuator for movement into and out of engagement with the braking surface 176, without being mounted on a brake arm 180. For example, brake pad 178 may be mounted on the armature of a solenoid actuator such that actuation of the armature in directions toward or away from the brake disk 172 moves the brake pad 178 into and out of engagement with the braking surface 176 on brake disk 172. In the embodiment shown, the brake pad 178 has a generally flat surface for engaging the braking surface 176, but it will be appreciated that the brake pad 178 may alternatively have various other configurations suitable for engagement with the braking surface 176.

The brake assembly 170 may further include brake force reaction assembly 190 located adjacent the brake disk 172 and generally opposite the brake pad 178 to support the disk 172 when braking forces are applied to the braking surface 176 by the brake pad 178. In the embodiment shown, the brake force reaction assembly 190 includes a rolling element 192 positioned beneath the brake disk 172 opposite the brake pad 178. When braking forces are applied to the braking surface 176 of the disk 172 by engagement of the disk 172 with the brake pad 178, the rolling element 192 limits deflection of the brake disk 172 under the action of braking forces.

In one embodiment, the brake assembly 170 may be configured such that the brake disk 172 engages and rides on rolling element 192 of the brake force reaction assembly 190 when tension roller 46 is rotating during operation of the film dispenser 12b. Accordingly, any geometrical irregularities of tension roller 46 with respect to other components of film dispenser 12b, such as misalignment or out-of-round conditions of the tension roller 46, may be accommodated by the brake disk 172 being supported on rolling element 192.

The brake assembly 170 further includes a solenoid actuator 194 operatively coupled to a second end 180b of the brake arm 180, at a location spaced from the pivot axis 182 and the brake pad 178. In the embodiment shown, the second end 180b of the brake arm 180 and the solenoid actuator 194 are positioned generally above a contact surface 196a defined by a contact block 196 coupled to the top plate 40 of the film dispenser 12b. An output shaft, or armature, 200 of the solenoid 194 is coupled with the contact surface 196a such that when the solenoid 194 is actuated to extend the armature 200 in the direction of the contact surface 196a, the brake arm 180 is moved about the pivot axis 182 to move the brake pad 178 into engagement with the braking surface 176 of the brake disk 172, as depicted in FIG. 10B. Because the solenoid actuator 194 is spaced a distance from the pivot axis 182, braking force applied by the brake pad 178 to the braking surface 176 of the brake disk 172 is increased by leverage of the brake arm 180 about the pivot axis 182.

In operation, the solenoid actuator 194 may be actuated to a first condition wherein the brake pad 178 engages the braking surface 176 with a first braking force that slows rotation of the tension roller 46 to stretch the film material 14 during wrapping of a load 16. The actuator 194 may also be actuated to a second condition wherein the brake pad 178 engages the braking surface 176 with a second braking force that is less than the first braking force, and which prevents free rolling of the tension roller 46 while still allowing the tension roller 46 to rotate when tension is applied to the film web 14, to facilitate threading film 14 through the dispenser 12b. Alternatively, the second braking force may be selected to provide a minimum resistance to rotation of tension roller 46 that will not cause film 14 to be pulled out of clamp structure that initially secures the film 14 to the load 16 when wrapping of the load 16 with the film 14 is started. The actuator 194 may also be actuatable to a third condition wherein the brake pad 178 engages the braking surface 76 of the brake disk 172 with a third braking force that locks the tension roller 46 against rotation. The third condition of the actuator 194 may be useful to facilitate intentional tearing or breaking the film 14 after a load 16 has been wrapped. The actuator 194 may also be actuatable to a fourth condition wherein the brake pad 178 is either disengaged from the braking surface 176, or the brake pad 178 only engages the braking surface 176 with a negligible force.

Solenoid actuator 194 may be remotely adjustable to vary the braking force applied to the braking surface 176 for the various operating conditions of the actuator 194 while the stretch wrapping machine 10 is in use. The solenoid actuator 194 may also be programmable to establish multiple settings of the actuator 194 corresponding to the various operating conditions. While the brake assembly 170 has been shown and described as including a solenoid actuator 194 for applying braking force to the tension roller 46 using a brake arm 180, it will be appreciated that various other actuators may alternatively be used to apply braking force to the tension roller 46. As non-limiting examples, such actuators may include linear or rotary actuators, magnetic, electronic, hydraulic, or pneumatic devices, or any other device suitable for applying force to move the brake arm 180 to bring the brake pad 178 into and out of engagement with the braking surface 176 of the brake disk 172.

Referring now to FIGS. 11, 12A, and 12B, a fourth exemplary embodiment of a brake assembly 210 for use with a film dispenser 12c in accordance with the principles of the present invention is described. Various components of the film dispenser 12c are similar to those described above with respect to film dispenser 12b shown in FIGS. 9, 10A, and 10B, and similar features are similarly numbered. The brake assembly 210 includes a brake disk 172 coupled with a distal end of the tension roller 46 such that the rotational axis 174 of the disk 172 corresponds with the rotational axis of the tension roller 46. In this embodiment, a braking surface 176 is defined on circumferentially extending portions of first and second oppositely disposed sides 172a, 172b of the disk 172, whereby the braking surface 176 extends circumferentially around the tension roller 46 relative to the circumferential film engaging surface 50.

The brake assembly 210 further includes a first brake pad 212 supported on a first end 214a of a first brake arm 214 for pivotal movement with the first brake arm 214 about a first pivot axis 216 that is substantially perpendicular to the rotational axis 174 of the disk 172, such that the first brake pad 212 is movable into and out of engagement with the braking surface 176 on the first side 172a of the disk 172, generally along a direction that is substantially parallel to the rotational axis 174 of the brake disk 172. In this embodiment, the second end 214b of the first brake arm 214 is pivotally coupled to a support block 218 disposed on top plate 40 of the film dispenser 12c.

A second brake pad 220 is supported on a first end 222a of a second brake arm 222 for pivotal movement with the second brake arm 222 about a second pivot axis 224 that is substantially perpendicular to the rotational axis 174 of the disk 172, such that the second brake pad 220 is movable into and out of engagement with the braking surface 176 on the second side 172b of the disk 172, generally along a direction that is substantially parallel to the rotational axis 174 of the brake disk 172. In this embodiment, the second end 222b of the second brake arm 222 is also pivotally coupled to the support block 218. It will be appreciated, however that first and second brake arms 214, 222 may alternatively be supported by various other structure for pivotal movement about pivot axes such that the first and second brake pads 178 are movable into and out of engagement with the braking surface 176 on disk 172.

The position of the second brake pad 220 relative to the braking surface 176 on the second side 172b of the brake disk 172 is selectively adjustable. In the embodiment shown, the position of the second brake pad 220 is selectively adjustable by a threaded member 224 disposed on top plate 40 and engaging second brake arm 222. The threaded member 224 can be selectively adjusted to vary the height above top plate 40 at which the threaded member 224 engages a pad mounting block 226 that supports the second brake pad 220 on the first end 222a of second brake arm 222. It will be appreciated that various other structure or methods could alternatively be used to vary the position of the second brake pad 220 relative to the braking surface 176.

The brake assembly 210 further includes a solenoid actuator 194 supported on bearing plate 48c and operatively coupled to the first end 214a of the first brake arm 214. In the embodiment shown, an output shaft, or armature, 200 of the solenoid 194 is coupled with a pad mounting block 228 that supports the first brake pad 212 on the first end 214a of the first brake arm 214 such that when the solenoid 194 is actuated to extend the armature 200 in the direction of the brake disk 172, the first end 214a of the first brake arm 214 is moved about the first pivot axis 216 to move the first brake pad 212 into engagement with the braking surface 176 on the first side 172a of the brake disk 172, as depicted in FIG. 12B. The brake disk 172 rides on or just slightly above the second brake pad 220 until the first brake pad 212 is actuated to move into engagement with the brake disk 172, whereby the brake disk 172 is engaged by the first brake pad 212 and the second brake pad 220.

In another aspect in accordance with this embodiment, the tension roller 46 may be resiliently supported proximate the bottom plate 30 of dispenser 12c for movement along the longitudinal axis of the roller, and biased in a direction toward the bearing plate 48c to counteract the weight of the tension roller 46. Supporting tension roller 46 in this manner allows the vertical position of the tension roller 46 and brake disk 172 to float relative to the position of the second brake pad 220, thereby reducing or eliminating friction between the second brake pad 220 and the braking surface 176 on the second side 172b of brake disk 172 when the first brake pad 212 is disengaged from the braking surface 176 on the first side 172a of brake disk 172. In the exemplary embodiment shown in FIG. 13, tension roller 46 is resiliently supported proximate bottom plate 30 by a biasing member 230, such as a spring. It will be appreciated, however, that various other structure and/or methods may be used to resiliently support tension roller 46 to counteract the weight of the tension roller 46.

In operation, the solenoid actuator 194 may be actuated to a first condition wherein the first and second brake pads 212, 220 engage the braking surface 176 with a first braking force that slows rotation of the tension roller 46 to stretch the film material 14 during wrapping of a load 16. The actuator 194 may also be actuated to a second condition wherein the first and second brake pads 212, 220 engage the braking surface 176 with a second braking force that is less than the first braking force, and which prevents free rolling of the tension roller 46 while still allowing the tension roller 46 to rotate when tension is applied to the film web 14, to facilitate threading film 14 through the dispenser 12c. Alternatively, the second braking force may be selected to provide a minimum resistance to rotation of tension roller 46 that will not cause film 14 to be pulled out of clamp structure that initially secures the film 14 to the load 16 when wrapping of the load 16 with the film 14 is started. The actuator 194 may also be actuatable to a third condition wherein the first and second brake pads 212, 220 engage the braking surface 176 of the brake disk 172 with a third braking force that locks the tension roller 46 against rotation. The third condition of the actuator 194 may be useful to facilitate intentional tearing or breaking the film 14 after a load 16 has been wrapped. The actuator 194 may also be actuatable to a fourth condition wherein one or both of the first and second brake pads 212, 220 are either disengaged from the braking surface 176, or only engage the braking surface 176 with negligible force.

Solenoid actuator 194 may be remotely adjustable to vary the braking force applied to the braking surface 176 for the various operating conditions of the actuator 194 while the stretch wrapping machine 10 is in use. The solenoid actuator 194 may also be programmable to establish multiple settings of the actuator 194 corresponding to the various operating conditions. While the brake assembly 210 has been shown and described as including a solenoid actuator 194 for applying braking force to the tension roller 46 using brake arms 214, 222, it will be appreciated that various other actuators may alternatively be used to apply braking force to the tension roller 46. As non-limiting examples, such actuators may include linear or rotary actuators, magnetic, electronic, hydraulic, or pneumatic devices, or any other device suitable for applying force to move the first brake arm 214 to bring the first brake pad 212 into and out of engagement with the braking surface 176 of the brake disk 172.

In the embodiments depicted in FIGS. 9-12B, the brake pads engage only a portion of an area of the circumferential braking surface 176 of brake disk 172. The area can be represented by a sector on one or both sides of disk 172 (according to the particular embodiment), wherein the sector is defined by swinging a radius from the rotational axis of tension roller 46 through an acute angle.

While the present invention has been illustrated by the description of one or more embodiments thereof, and while the embodiments have been described in considerable detail, they are not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of Applicants' general inventive concept.

Claims

1. A film dispenser for stretch wrapping machines, comprising: at least one roller, the roller having a longitudinal axis and a circumferential film engaging surface;a braking surface extending circumferentially around the roller relative to the circumferential film engaging surface; andan electrically-actuated first brake engageable with either a portion of a sector of the braking surface or a portion of an area defined by an arc along the braking surface of the at least one roller, the first brake selectively adjustable between a first configuration engaged with the braking surface and applying a first braking force to the braking surface, and a second configuration wherein the first brake is disengaged from the braking surface or is only minimally engaged such that any braking force applied is substantially less than the first braking force.

2. The film dispenser of claim 1, further comprising: a disk coupled with a first axial end of the at least one roller, the disk having first and second oppositely disposed sides;wherein the braking surface is located on circumferentially extending portions of the first and second sides of the disk.

3. The film dispenser of claim 2, wherein the first brake comprises a first brake pad adjacent the first side of the disk and a second brake pad adjacent the second side of the disk, such that the disk is disposed between the first and second brake pads; at least one of the first and second brake pads movable between the first and second configurations of the first brake along directions substantially parallel to an axial direction of the disk.

4. The film dispenser of claim 2, wherein the first brake is selectively adjustable to vary the amount of first braking force applied to the braking surface.

5. The film dispenser of claim 3, wherein the first brake comprises an actuator operatively coupled with the first brake pad, the actuator selectively actuatable to at least a first condition wherein the first and second brake pads engage the braking surface in the first configuration of the first brake, and wherein the first braking force stretches the film material during wrapping of a load.

6. The film dispenser of claim 5, wherein the actuator is actuatable to a second condition wherein the first and second brake pads engage the braking surface in the first configuration of the first brake, and wherein the first brake applies a second braking force that prevents free rolling of the roller while allowing the roller to rotate to facilitate threading of film through the dispenser.

7. The film dispenser of claim 6, wherein the actuator is actuatable to a third condition wherein the first and second brake pads engage the braking surface in the first configuration of the first brake, and wherein the first brake applies a third braking force that locks the roller against rotation.

8. The film dispenser of claim 7, wherein the actuator is actuatable to a fourth condition wherein at least the first brake pad is disengaged from the braking surface in the second configuration of the first brake.

9. The film dispenser of claim 5, further comprising: a first brake arm pivotally movable about a first pivot axis that is substantially perpendicular to the axial direction of the disk;the first brake pad supported on the first brake arm for pivotal movement about the first pivot axis into engagement with the braking surface.

10. The film dispenser of claim 9, further comprising: a second brake arm pivotally movable about a second pivot axis that is substantially perpendicular to the axial direction of the disk;the second brake pad supported on the second brake arm for pivotal movement about the second pivot axis into engagement with the braking surface.

11. The film dispenser of claim 10, wherein the roller is resiliently supported for movement in a direction along the longitudinal axis of the roller and biased in a direction toward the disk to compensate for the weight of the roller.

12. The film dispenser of claim 1, wherein the first brake comprises a solenoid actuator having an armature operatively coupled with a first brake pad, the armature moving the first brake pad to engage the braking surface in the first configuration of the first brake.

13. The film dispenser of claim 12, wherein the solenoid actuator is selectively actuatable to at least a first condition wherein the first brake pad engages the braking surface in the first configuration of the first brake, and wherein the first braking force stretches the film material during wrapping of a load.

14. The film dispenser of claim 13, wherein the solenoid actuator is actuatable to a second condition wherein the first brake pad engages the braking surface in the first configuration of the first brake, and wherein the first brake applies a second braking force that prevents free rolling of the roller while allowing the roller to rotate to facilitate threading of film through the dispenser.

15. The film dispenser of claim 14, wherein the solenoid actuator is actuatable to a third condition wherein the first brake pad engages the braking surface in the first configuration of the first brake, and wherein the first brake applies a third braking force that locks the roller against rotation.

16. The film dispenser of claim 15, wherein the solenoid actuator is actuatable to a fourth condition wherein the first brake pad is disengaged from the braking surface in the second configuration of the first brake.

17. A film dispenser for stretch wrapping machines, comprising: at least one roller, the roller having a circumferential film engaging surface and a circumferential braking surface;a brake arm pivotally movable about a pivot axis spaced from the roller;a brake pad supported on the brake arm for pivotal movement with the brake arm about the pivot axis into engagement with the braking surface along a substantially radial direction of the roller; andan actuator operatively engaging the brake arm at a location spaced from the pivot axis and the brake pad, whereby braking force applied by the brake pad when the actuator is actuated is increased by leverage of the brake arm about the pivot axis.

18. The film dispenser of claim 17, wherein the actuator selectively actuatable to at least one of: a first condition wherein the brake pad engages the braking surface with a first braking force that stretches the film material during wrapping of a load.a second condition wherein the brake pad engages the braking surface with a second braking force that prevents free rolling of the roller while allowing the roller to rotate to facilitate threading of film through the dispenser;a third condition wherein the brake pad engages the braking surface with a third braking force that locks the roller against rotation; ora fourth condition wherein the brake pad is disengaged from the braking surface.

19. A method of dispensing stretch wrap material to a load, the method comprising: feeding film from a supply roll;engaging the film from the supply roll with at least one roller;selectively engaging the roller with a first brake; andengaging the roller with a second brake.

20. The method of claim 19, further comprising applying at least one of: a first braking force to the roller with the first brake such that the film is stretched as it is applied to wrap the load;a second braking force to the roller with the second brake, the second braking force preventing prevent free rolling of the roller while allowing the roller to rotate sufficiently to facilitate threading film from the supply roll to the roller when the first brake is not engaged; ora third braking force to the roller with the first brake such that the roller is locked against rotation.