GB2304321A

GB2304321A - Film web clamping and cutting apparatus for a bale wrapper machine

Info

Publication number: GB2304321A
Application number: GB9517051A
Authority: GB
Inventors: Martyn Nicholas Mills
Original assignee: VOLAC INTERNATIONAL Ltd
Current assignee: VOLAC INTERNATIONAL Ltd
Priority date: 1995-08-19
Filing date: 1995-08-19
Publication date: 1997-03-19
Anticipated expiration: 2015-08-19
Also published as: GB9517051D0; GB2304321B

Abstract

The apparatus comprises an abutment plate 64, a cutting blade 66 and a movable plate 68, having a roller 70, for cutting and clamping a portion 31 of film therebetween when the plate 68 is retracted towards the cutting blade 66. The plate 68 is movable by means of a rod 72 from an extended to a retracted position under the action of a spring 74 and the rod is extendable in a stepwise fashion. The stepwise extension is provided by means of apertured plates 102, 104, and a drive cam 116 for causing alternating advance and return strokes of movement of plate 102 relative to the other, the plates 102, 104 being operable to releasably grip the rod (similar to the mechanism used in a mastic gun) so that advance strokes move the rod towards its extended position, whilst movement of the rod in the opposite direction is prevented during the return strokes. The film may be gathered and cut before the turntable, on which the bale is wrapped, is tilted to discharge the bale therefrom.

Description

TITLE: IMPROVEMENTS IN AND RELATING TO BALE WRAPPERS Field of the Invention This invention relates to film web cutting and clamping apparatus for a bale wrapper machine, to a bale wrapper machine when fitted with a film cutting and clamping apparatus, and to a method of wrapping a bale.

Background to the Invention It is known to treat agricultural crop (for example to make silage), by wrapping cylindrical bales of the crop are wrapped in a pre-stretched plastics film. The film provides a substantially airtight and watertight seal for the bale, thus enabling the crop, for example grass, to ferment.

EP 0 367 529 shows a bale wrapper machine in which a turntable is rotatably mounted on a chassis, and has a pair of spaced rollers for rotating a bale thereon about its horizontal axis. In use, the turntable rotates about a vertical axis while the bale is rotated about its horizonal axis via the rollers. This compound movement of the bale causes it to be wrapped in plastics film supplied from a reel mounted on the chassis.

After the bale has been wrapped, the turntable tilts, causing the portion of the film extending between the reel and the bale to be gathered into a small bundle situated between two jaws of a clamping and cutting apparatus which is mounted on the turntable.

The clamping and cutting apparatus cuts the web at that bundle, so that the wrapped bale can be discharged from the turntable, and clamps the end of the remaining web to enable the wrapping of the next bale to be initiated by the rotation of the turntable with the end of the web clamped thereto.

The jaws are moved together by means of a spring biased toothed track which is extended by means of a pair of pawls during the wrapping of a bale. It has been found that this kind of mechanism is prone to wear.

In addition, the timing of the operation of the cutting and clamping means in relation to the tilting of the turntable is very important. The cutting and clamping means must not operate before the web has been properly gathered, but the web must be cut and clamped before the bale rolls off the turntable.

Summarv of the Invention According to a first aspect of the invention, there is provided film web clamping and cutting apparatus for a bale wrapper machine, the apparatus comprising a pair of opposed jaw means for cutting and clamping a portion of film therebetween, a rod to which one of said jaw means is connected, the rod being movable from and extended to a retracted position, under the action of biasing means, to bring the jaws means together; and extension means for extending the rod in a stepwise fashion, wherein said extension means comprises first and second gripping members, drive means for causing alternating advance and return strokes of movement of the first gripping member relative to the second, the first and second gripping members being operable releasably to grip the rod so that said advance strokes move the rod towards its extended position, whilst movement of the rod in the opposite direction is prevented during the return strokes.

The rod and gripping members perform a similar function to the pawl and track assembly of the prior art, but are less prone to wear than the latter.

Preferably, the jaw means comprise two abutments for clamping the film web therebetween, and a separate cutting tool positioned adjacent one of said abutments.

Preferably, the second gripping member is situated at a position which is substantially fixed relative to the jaw means not connected to the rod, so that the rod is moved towards its extended position only by said advance strokes of the first gripping member.

Preferably, each gripping member has an aperture through which the rod extends, and is pivotable relative to the rod between a locking position in which the rod is gripped in said aperture, and a release position in which the rod passes through the aperture with clearance.

Such a gripping member can grip and release a rod simply by being rotated, does not need to have any moving parts, and can therefore be of a simple construction.

Thus, the first gripping member may comprise a first apertured plate, and the second gripping member may comprise a second apertured plate.

Preferably, the second plate is spring biased into its locking position, but is movable out of said position by advance movement of the rod, while the first plate is spring biased into its release position and the engagement of the first plate by the drive means to cause said advance stroke also pivots the first plate into its locked position.

Preferably, the rod has a reduced width portion which cannot be gripped by a plate and which defines a limit beyond which the rod cannot be extended by the extension means.

Preferably, the clamping and cutting apparatus is adapted to be mounted on a turntable of the bale wrapper machine, on which turntable a bale is wrapped, and the drive means comprises a camming member which, in use, engages the first plate so as to cause said advance stroke, and which is connected by a linkage to the chassis on which the turntable is rotatably mounted so that said camming member is driven by the rotation of the turntable.

This avoids the need for the turntable to be equipped with any separate power source for extending the rod.

Preferably, the cutting and clamping apparatus includes a solenoid operable to rotate the second plate into its release position, so as to trigger the movement of the rod into its retracted position.

The invention also lies in a bale wrapping machine comprising a turntable rotatably mounted on a chassis, means for mounting a reel of film web in a position fixed relative to the chassis, the turntable being operable to rotate the bale so as to wrap the latter with film from said reel, the machine further including clamping and cutting apparatus, in accordance with the first aspect of the invention, mounted on said turntable and being operable to cut and clamp the film web in a region of the latter between a reel and a wrapped bale, the turntable being tiltable to discharge a wrapped bale therefrom.

Preferably, the machine includes gathering means for gathering a portion of the web, between the supply reel and a wrapped bale, into a bundle between the jaw means of the cutting and clamping apparatus, to enable the said web to be cut and clamped at that portion, wherein the gathering means includes engagement means for engaging the web to form said bundle before the turntable is tilted.

To that end, the relative positions of the extended rod and the engagement means are preferably such that, with the engagement means in an inoperative position, the film web extends between the engagement means and the rod, which is situated adjacent opposite edges of the web, the engagement means being movable from its inoperative position towards the edge of the web adjacent to the rod thereby to gather the web against the rod.

Thus the operation of the clamping and cutting apparatus does not have to occur at a specific time dictated by the tilting of the turntable.

Preferably, the range of movement of the engagement means from said inoperative to said operative positions is such that the perpendicular distance travelled by the engagement means relative to the edges of the web is at least substantially the same as the width of the ungathered web.

Preferably, the gathering means comprises a pivotal arm, the engagement means comprising a bar for projecting laterally therefrom.

Preferably, when in its operative position, the bar is situated between the mounting means for the film reel and said rod of the cutting and clamping means.

Preferably, said arm is connected to a hydraulic cylinder for raising and lowering the arm and the cylinder may to advantage be connect to hydraulics used to tilt and rotate the turntable through a switch valve which also actively causes the cylinder to move the arm into its inoperative position as the turntable is tilted.

The method also lies in a method of wrapping a bale in a film web, the method comprising the steps of placing the bale on a turntable, attaching film web from a reel to the bale, rotating the turntable, and hence the bale, relative to the reel until the bale is wrapped, gathering a portion of the web between the bale and the reel into a bundle and cutting said web at said bundle, and tilting the turntable to discharge the bale therefrom, wherein the web is gathered into said bundle and cut before the turntable is tilted.

Brief Description of the Drawings The invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a perspective view of a bale wrapper machine which has a tiltable turntable, and which is fitted with film web clamping and cutting apparatus in accordance with the invention; Figure 2 is the same view of the machine when the clamping and cutting apparatus is operating; Figure 3 is a view to an enlarged scale of part of the underside of the turntable; Figure 4 is a plan view of the clamping and cutting apparatus; Figure 5 is a sectional side view of the clamping and cutting apparatus; Figures 6a-6c are fragmentary views of the clamping and cutting apparatus at various stages in its cycle of operation;; Figures 7-9 are cross-sectional views of part of the clamping and cutting apparatus, taken along the lines A-A, B-B and C-C respectively; Figures 10 and 11 are plan views of part of the clamping and cutting apparatus showing how the latter clamps and cuts film web; Figure 13 is a sectional fragmentary plan view of the mechanism for rotating the turntable and linkage through which the clamping and cutting apparatus is driven; and Figure 14 is a sectional fragmentary view of the mechanism shown in Figure 13.

Detailed Description Referring to Figure 1, a bale wrapping machine is adapted to be towed by, for example, a tractor, and comprises a wheeled chassis 2 having a forward mounting point 4 for connection to the towing linkage of a tractor. A turntable 6 is mounted on the chassis 2 for rotation about a vertical axis as indicated by the arrow Y. The turntable 6 includes a pair of laterally spaced rollers 8 and 10 which are rotatable about their axes so as to rotate a cylindrical bale 12 supported on the turntable about its horizontal axis as indicated by the arrow X.

A vertical post 14 is attached to the chassis 2 between the turntable 6 and the forward mounting 4, and carries upper and lower horizontal bars 16 and 18 connected to respective ends of a vertical spindle 20. The spindle 20 carries a reel 22 of pre-stretched plastics film web.

An arm 24 is pivotally mounted on the post 14, and is pivotally connected to one end of a hydraulic ram 26, the other end of which is pivotally mounted on a lug 28 protruding from the bar 16.

A bar 30 projects perpendicularly from the arm 24. With the arm 24 in the position shown in Figure 1, the bar 30 is positioned above a portion, 31, of the film web, indicated by dotted lines, extending from the reel 22 to the bale 12 on the turntable 6.

The turntable 6 includes a bobbin 32 to help locate the bale 12 in position thereon and a bar 34 on which film web clamping and cutting apparatus 36 is mounted.

Figure 3 shows how the turntable 6 is mounted on the chassis 2. A girder 38 is pivotally connected at one end to the rear of the chassis, and is attached at its other end region to a hydraulic ram 39 which acts between the girder 38 and the chassis 332 to tilt the turntable 6. The turntable 6 is shown tilted.

Referring to Figures 13 and 14, a hollow hub 43 is bolted to the girder 38, and receives a central shaft 41 which is attached to the underside of a housing 51 which is in turn attached to the turntable 6. The shaft 41 extends downwardly through the hub 43 and through an aperture in the girder 38 to project from the bottom of the latter. The bottom of the shaft 41 carries a pair of slip rings 45 which enable electrical power to be supplied to a component (described below) on the turntable 6. A set of bearings and bushes 47 and 49 are mounted on the hub and enable relative rotation of the hub and shaft.

The hub 43 and shaft 41 are encircled by a ring gear 42 which is attached to the underside of the housing 51. A motor 46 is attached to the girder 38, and has a spur gear 53 which meshes the teeth of the ring gear 42 so that operation of the motor 46 rotates the gear 42 and hence the turntable 6. A cylindrical skirt 40 decends from the underside of the turntable 6 and surrounds the hub 43 and the shaft 41, the ring gear 42, the spur gear 53 and the housing 51.

A bevel gear 50 is situated above the ring gear 42 and is attached to the hub 43 so that the gear 50 is rotationally fixed relative the chassis 2. A shaft 52 is mounted on the turntable, for rotation therewith, extends through an aperture in the housing 51 and is attached at one end to a bevel gear 54 which meshes with the gear 50 so that rotation of the turntable also causes the shaft 52 to rotate about its axis.

The shaft 52 is connected to the roller 8 so that the rotation of the shaft 52 drives the roller 8, and hence the roller 10 through three drive belts 56. The shaft 52 is kinked so as to define a crank pin 60 which is connected to the clamping and cutting apparatus 36 through a rod 62.

With reference to Figure 4, the cutting and clamping apparatus has first jaw assembly which comprises an abutment 64 and a cutting blade 66 attached to the bar 34. The other jaw for the apparatus comprises an abutment 68 on which a roller 70 is mounted, and which is attached to the outboard end of a rod 72.

A tension spring 74 is attached at its opposite ends to the inboard end of the rod 72 and to a post 76 which projects upwardly from a base plate 78.

Lateral location of the end of the rod adjacent the string 74 is achieved by a plate 80 which is welded to the rod at its inboard end, and which includes a lower recess 82 (Figure 7). A ridge 84 projects from the plate 78 into the recess 82. The ridge 84 runs parallel to the axis of the rod 72 and thus allows the plate 80 to move in a direction parallel to the axis of the rod 72, but engages in the recess 82 to prevent lateral movement of the inboard end of the rod.

The rods 72 is formed with a neck 86 which is adjacent the plate 80 and on the opposite side thereof from the spring 74.

Further lateral location of the rod is provided by three sleeves 88, 90 and 92 which are welded to two plate portions 94 and 96. The portions 94 and 96 are co-planar with each other and with the axis of the rod 72.

The portions 94 and 96 constitute a plate assembly which includes two windows 98 and 100. A first locking plate 102 extends through the first window 98, and a second locking plate 104 extends through the window 100. Each of the plates 102 and 104 has a respective aperture which is of a slightly larger diameter than that of the rod 72 and through which the rod 72 extend.

The first locking plate 102 is shown in more detail in Figure 8, and includes an increased width upper portion 106 which defines two shoulders 108 and 110 by which the plate 102 is supported on the plate assembly 94, 96.

The plate 102 is urged into the position shown in Figure 4 by means of a compression spring 112 acting between the plate 102 and the sleeve 90. When in this position, the plate 102 is substantially perpendicular to the axis of the rod 72 so that the latter passed with clearance through an aperture 114 in the plate 102. A camming member 116 is operable to bear against the plate 102 to pivot the latter until it locks against the rod 72 and to cause the plate to travel along an advanced stroke in the direction of the axis of the rod 72 towards the right of the apparatus as viewed in Figure 4. When the camming member returns to the position shown in Figure 4, the spring 112 unlocks the plate 102 and pushes the latter back towards the position shown in Figure 4 in a return stroke of the plate 102.

The top of the plate 104 extends into a recess in a longitudinal plate 118 welded to the sleeve 90, and is biased towards the sleeve 90 by a compression spring 120 acting between the plate 104 and the sleeve 92. The plate 104 thus tends to pivot around the plate 118 under the influence of the spring 120 which therefore tends to lock the plate 104 against the rod 72. The force exerted on the rod 72 by the spring 74 also tends to increase the force with which the plate 104 grips the rod 72. At the bottom of the plate 104 there is provided a lug 122 which is connected to a solenoid switch 124, the power for which is supplied by cables connected to the slip rings on the bottom of the shaft 41.

During each advance stroke of the plate 102 towards the sleeve 90, the rod 72 is locked against the plate 102 so that said advance stroke also advances the rod 72. This movement tends to pivot the plate 104 in an anti-clockwise direction as viewed in Figure 5 so that the plate 104 is substantially perpendicular to the axis of the rods 72 which therefore can travel through the aperture 126 in the plate 104. Thus the plate 104 allows the rod to be extended. However, during the return stroke of the plate 102 (ie towards the sleeve 88), the plate 104 locks against the rod 72 to prevent the latter from retracting. Thus the plates 102 and 104 act with a ratchet action against the rod 72, each plate allowing the rod to travel relative thereto in only one direction so that a succession of advance strokes of the plate 102 extends the rod in a stepwise fashion.The action of the plates 102 and 104 is similar to the mechanism used in a mastic gun.

The rod 72 is fully extended when the neck 86 has reached the aperture in the plate 102 which consequently can no longer grip the rod 72. As a result, the advance strokes of the plate 102 will no longer extend the rod 72.

In order to trigger a cutting and clamping operation, the solenoid 124 then pivots the plate 104 until it is perpendicular to the axis of the rod 72, releasing the rod 72, whilst plate 102 is held by the spring 112 perpendicular to the rod 72, so that the latter moves rapidly to the left (as viewed in Figures 4 and 5) under the action of the spring 74 causing the abutment of the jaw 68 to push the web of material against the blades 56, to cut the web, while the portion of the web upstream of the blade 66 is clamped against the abutment 64 by the roller 70. This action is illustrated in Figures 10 and 11.

Figure 6a shows the rod 72 when in its fully retracted condition in which web between the jaws is clamped and cut. In Figure 6b the rod 72 has been partially extended, while in Figure 6c the rod 72 is shown fully extended with the plate 102 at the neck 86.

In operation, the bale 12 is placed on the turntable 6 which is then rotated about the vertical axis, causing the bale 12 to be rotated about its own axis and the web from the reel 22 to be wrapped around the bale 12. During each revolution of the turntable 6, the shaft 52 undergoes one revolution, causing the rod 62 to operate the camming member 116, and thus causing the rod to be advanced by one step. After twelve or thirteen revolutions, the rod 72 is fully extended, as shown in Figure 6, so that further revolutions of the turntable 6 do not move the rod 72. Once the bale 12 has been fully wrapped, the arm 24 is lowered, causing the bar 30 to gather the web material between the reel 22 and the bale 12 against the extended rod 72.It will be seen that the range of movement of the arm 24 is such that the vertical distance travelled by the bar 30 corresponds to the width of the film web.

The solenoid 124 is then operated, causing the rod 72 rapidly to retract, and the abutment 68 to urge the web against the blade 66 thereby cutting the web, as illustrated in Figure 11. The free end of the cut web from the reel 22 is also firmly clamped between the roller 70 and the abutment 64. The turntable 6 can then be tilted to discharge the bale 12 and another bale placed thereon. During the first one or two subsequent revolutions of the turntable 6, the jaws of the cutting and clamping apparatus continue to clamp the web material so as to draw the material around the bale in those first revolutions. By the time the web is released by the cutting and clamping apparatus 32, a sufficient amount of web has been wound onto the bale for the web not to slip off the bale. The rest of the wrapping process can be conducted as before.

Claims

1. Film web clamping and cutting apparatus for a bale wrapper machine, the apparatus comprising a pair of opposed jaw means for cutting and clamping a portion of film therebetween, a rod to which one of said jaw means is connected, the rod being movable from and extended to a retracted position under the action of biasing means, to bring the jaw means together; and extension means for extending the rod in a stepwise fashion, wherein said extension means comprises first and second gripping members, drive means for causing alternating advance and return strokes of movement of the first gripping member relative to the second, the first and second gripping members being operable releasably to grip the rod so that said advance strokes move the rod towards its extended position, whilst movement of the rod in the opposite direction is prevented during the return strokes.

2. Apparatus according to claim 1, in which the jaw means comprise two abutments for clamping the film web therebetween, and a separate cutting tool positioned adjacent one of said abutments.

3. Apparatus according to claim 1 or claim 2, in which the second gripping member is situated at a position which is substantially fixed relative to the jaw means not connected to the rod, so that the rod is moved towards its extended position only by said advance strokes of the first gripping member.

4. Apparatus according to any of the preceding claims, in which each gripping member has an aperture through which the rod extends, and is pivotable relative to the rod between a locking position in which the rod is gripped in said aperture and a release position in which the rod passes through the aperture with clearance.

5. Apparatus according to claim 4, in which the first gripping member comprises a first apertured plate. and the second gripping member comprises a second apertured plate.

6. Apparatus according to claim 5, in which the second plate is spring biased into its locking position, but is movable out of said position by advance movement of the rod, while the first plate is spring biased into its release position wherein the engagement of the first plate by the drive means to cause said advance stroke also pivots the first plate into its locked position.

7. Apparatus according to claim 5 or claim 6, in which the rod has a reduced width portion which cannot be gripped by a plate and which defines a limit beyond which the rod cannot be extended bv the extension means.

8. Apparatus according to any of claims 5 to 7, in which the apparatus is adapted to be mounted on a turntable of the bale wrapper machine, on which turntable a bale is wrapped, and the drive means comprises a camming member which, in use, engages the first plate so as to cause said advance stroke, and which is connected by a linkage to the chassis on which the turntable is rotatably mounted so that said camming member is driven by the rotation of the turntable.

9. Apparatus according to any of claims 5 to 8. in which the apparatus includes a solenoid operable to rotate the second plate into its release position so as to trigger the movement of the rod into its retracted position.

10. A bale wrapping machine comprising a turntable rotatably mounted on a chassis, means for mounting a reel of t.^ilrn web in a position fixed relative to the chassis, the turntable being operable to rotate the bale so as to wrap the latter with film from said reel, the machine further including clamping and cutting apparatus, according to any of the preceding claims, mounted on said turntable and being operable to cut and clamp the film web in a region of the latter between a reel and a wrapped bale, the turntahle being tiltable to discharge a wrapped bale therefrom.

11. A machine according to clairn 1O, in which the machine includes gathering means for gathering a portion of the web, between the supply reel and a wrapped bale, into a bundle between the jaw means of the cu:ting and clamping apparatus, to enable the said web to be cut and clamped at that portion, wherein the gathering means includes engagement means for engaging the web to form said bundle before the turntable is tilted.

12. A machine according to claim 11, in which the relative positions of the extended rod and the engagement means are preferably such that, with the engagement means in an inoperative position, the film web extends between the engagement means and the rod, which is situated adjacent opposite edges of the web, the engagement means being movable from its inoperative position towards the edge of the web adjacent to the rod thereby to gather the web against the rod.

13. A machine according to claim 11 or claim 12, in which the range of movement of the engagement means from said inoperative to said operative positions is such that the perpendicular distance travelled by the engagement means relative to the edges of the web is at least substantially the same as the width of the ungathered web.

14. Apparatus according to any of claims 11 to 13, in which the gathering means comprises a pivotal arm, and the engagement means comprises a bar proiecting laterally therefrom.

15. Apparatus according to claim 14, in which, when in its operative position, the bar is situated between the mounting means for the film reel and said rod of the cutting and clamping means.

16. Apparatus according to claim 14 or claim 15, in which said arm is connected to a hydraulic cylinder for raising and Iowering the arm and the cylinder is connected to hydraulics used to tilt and rotate the turntable through a switch valve which also actively causes the cylinder to move the arm into its inoperative position as the turntable is tilted.

17. A method of wrapping a bale in a film web, the method comprising the steps of placing the bale on a turntable, attaching film web from a reel to the bale, rotating the turntable, and hence the bale, relative to the reel until the bale is wrapped, gathering a portion of the web between the bale and the reel into a bundle, cutting said web at said bundle, and tilting the turntable to discharge the bale therefrom, wherein the web is gathered into said bundle and cut before the turntable is tilted.

18. Film web clamping and cutting apparatus substantially as described herein with reference to, and as illustrated in, the accompanying drawings.

19. A bale wrapping machine substantially as described herein, with reference to, and as illustrated in, the accompanying drawings.

20. A method of wrapping a bale in a film web substantially as described herein, with reference to the accompanying drawings.