GB2228246A

GB2228246A - Bale wrapping machine

Info

Publication number: GB2228246A
Application number: GB9002377A
Authority: GB
Inventors: Alfred Anthony Cox; Desmond Charles Rich Townshend
Original assignee: Idough Investment Co
Current assignee: Idough Investment Co
Priority date: 1989-02-06
Filing date: 1990-02-02
Publication date: 1990-08-22
Anticipated expiration: 2010-02-02
Also published as: GB2228246B; BE1003396A6; GB9002377D0; IE890370A1; IE890370L

Abstract

The invention relates to bale wrapping machines of the kind used in agriculture to wrap large round bales of fodder with a plastics film. The machine has a turntable 1 which rotates about a vertical axis 18. The turntable supports a pair of rollers and an endless belt which carry, and rotate about a horizontal axis, the bale to be wrapped. The rollers are driven by a drive shaft 3 the shaft mounting a drive sprocket, which is rotatably-driven by engagement with an indexing rack 20 (Fig. 2) of rollers or pegs mounted on platform supporting the turntable. The invention is particularly concerned to prevent accidental contra-rotation of the drive shaft 3 and comprises a brake 30 which normally acts on the drive shaft 3 to prevent rotation of the drive shaft but is released to permit rotation of the drive shaft 3 when the rollers are driven i.e. when the shaft drive sprocket is engagement with the indexing rack or racks. The brake 30 is a disc brake 33 which acts on a disc 32 fixed to the drive shaft 3. The brake is released by a cam mechanism 40, 50 (Fig. 4). <IMAGE>

Description

A BALE WRAPPING MACHINE The present invention relates to improvements in a machine for wrapping bales of silage and the like, particularly large round bales, with a plastics film. The invention is particularly concerned with improvements in bale wrapping machines of the kind disclosed in U.K.

Patent Specification No. 2191984A, the contents of which are incorporated herein by way of reference.

A problem encountered with bale wrapping machines of the kind described is that if the machine is fed with an "out-of-round" bale there is a tendency for such bales to flick-over during rotation on the bale-wrapping belt. This can cause a reverse drive action in which the bale powers the drive system for the belt, which typically includes a shaft having a toothed sprocket. The spinning of the bale causes the shaft to rotate in reverse resulting in a mechanical crash when the sprocket engages a pegged indexing quadrant. Not only can this cause mechanical damage to the machine, but the wrapping overlap sequence gets out of step such that the bale may be wrapped in places with only two layers of film instead of four.Unfortunately, this may not become evident until the bale is stacked or, indeed, until the bale is opened for feeding and is found to be damaged due to insufficient wrapping.

The drive shaft for the belt normally is provided with a band brake, comprising a band, approximately 2" in width, which is clamped around the shaft. This band acts as a brake to prevent the shaft running on after the toothed sprocket, carried by the shaft, disengages from the pegged indexing quadrant.

Previous attempts to overcome the problem included increasing the width of the brake belt and the surface area of contact, but this led to a situation where excessive braking effort could be applied very easily, resulting in increased resistance to movement and greater mechanical impact when the sprocket engaged the pegged indexing quadrant.

It is an object of the invention to provide a braking system which serves to overcome the aforesaid problem.

Accordingly, the invention provides a braking system for use with the drive shaft of the bale-carrying belt of a bale wrapping machine comprising a brake which is adapted to act on the shaft to prevent rotation of the shaft, means for disengaging the brake when a sprocket carried by the shaft enters an indexing quadrant, and means for re-engaging the brake when the sprocket exits from the quadrant.

Preferably, the brake comprises a disc mounted on the shaft, and pressure pads which are normally closed on the disc to prevent rotation of the disc and the shaft, and cam means to disengage the pads when the sprocket engages with the indexing quadrant.

One embodiment of the invention is hereinafter described with reference to the accompanying drawings, wherein: Figure 1 is an exploded view of the chain drive assembly for the belt rollers of a bale wrapping machine fitted with a conventional band brake; Figure 2 is a plan view of the tipping platform a bale wrapping machine of the invention showing the indexing quadrant; Figure 3 is a plan view of the turntable of the bale wrapping machine showing the braking system of the invention; Figure 4 is an elevation on the lines x to x of Figure 3; and Figure 5 shows details of the braking system illustrated in Figure 4.

Referring firstly to Figure 1, this shows part of the turntable 1 of the bale wrapping machine on which is mounted the chain drive assembly for driving a belt roller 2. The belt roller 2 is one of a pair of rollers (the other not shown in Figure 1) mounted at each end of the rotating platform of the bale wrapping machine. An endless belt (not shown) is stretched between the rollers and rotates with the rollers.

A bale to be wrapped is carried on the belt. As explained in patent specification GB2191984A a bale of silage or the like to be wrapped with cling film is lifted onto the belt, and the platform 1 is then rotated about a generally vertical axis to cause a sheet of cling film to be wrapped around the bale. However, if no movement of the bale about its longitudinal axis were to occur then the bale would merely be wrapped with a single band having the thickness of the width of the cling film sheeting. The chain drive assembly illustrated in Figure 1 is intended to rotate the rollers 2 and hence the bale-carrying belt upon each rotation of the platform. This causes the belt to move for a predetermined distance which in turn causes the bale to roll about its surface.This rolling of the bale on the belt allows a new area of bale to be wrapped by the film on each rotation of the platform, thus eventually achieving a complete covering of the bale with a substantial degree of overlap of film.

The drive arrangement for the roller 2 comprises a drive shaft 3 which is mounted in bearings 4 and 5. A sprocket 6 is keyed onto the end of the shaft 1 and, through a chain 7 drives a larger sprocket 8 which is keyed onto the end of a shaft 9 of the roller 2. In the original bale wrapping machine a pawl 10 engages with teeth on the sprocket 8 to prevent contra-rotation of the pulley. However, this pawl and ratchet arrangement is not required when the brake system of the invention is used.

A toothed sprocket 11 is fixed on the shaft 3 and rotates with the shaft. The teeth of the sprocket 11 are adapted to engage between pegs or rollers of an indexing quadrant carried on the tipping platform of the bale wrapping machine about which the turn-table 1 rotates. The engagement of the sprocket with the indexing quadrant causes the sprocket to rotate and this drive is imparted to the roller 2.

As explained above, when a bale, which is not perfectly round in shape, for example it could be of lemon-shape, is placed on the belt roller there is a tendency for such bales to fall over during rotation on the belt. This can cause the belt to move in the opposite direction. This movement is transmitted through the belt 7 to the shaft 3. This in turn causes the shaft to rotate in reverse and puts the sprocket out of proper alignment with the indexing quadrant. One attempt to overcome this problem was to fit a band brake 12 on the shaft 3. As shown in Figure 1, the band brake comprised a band 13 which is fixed at one end, is turned around the shaft 3, and the other end is attached to a threaded adjuster 14 which leads to the outside of the frame. A wing-nut 15 is attached to the end of the threaded adjuster 14 by means of which tension in the band can be increased.However, as the brake is constantly applied it results in increased resistance to movement of the shaft 3, and greater mechanical impact when the sprocket engages in the pegged indexing quadrant. This band break is obviated and replaced by a new braking system according to the invention.

In the arrangement according to the invention, the chain drive assembly is substantially the same as that shown in Figure 1 except that the band brake is omitted, as is the ratchet arrangement 10.

Figure 2 is a plan view of the tipping platform 16 upon which the turntable rotates. The platform 16 has a main bearing 17 which carries the central spindle 18 (see Figure 3) of the turntable 1. An indexing quadrant 20 is mounted on the platform 16 by means of rubber buffers 21, which serve to absorb any shocks imparted to the indexing quadrant. If desired, a second indexing quadrant may be mounted on a diametrically opposite side of the platform at a position shown by the numeral 22. The indexing quadrant carries a plurality of rollers or pegs 23 between which the teeth of the sprocket 11 are intended to engage. It will be appreciated that the sprocket 11 thus acts as a cam and the rollers 23 act as cam followers. For every rotation of the turntable 1 about the tipping platform 6, the teeth of the sprocket 11 will engage with the rollers 23 thus imparting rotary action to the spindle 11, which in turn is transmitted to the roller 2 to cause the bale-carrying belt to rotate about the rollers as described above. The number of teeth and the spacing of the teeth in the indexing quadrant determine the length of movement of the belt for each rotation of the turntable 1. Typically, the belt is caused to move about 4" for each rotation.

The braking system of the invention is shown in Figure 3, which is a plan view of the turntable 1. The underside of the turntable is fitted with wheels (not shown) which are mounted on wheel mountings 25. The wheels are adapted to run upon the upper surface of the tipping platform 16.

It will be noted from Figure 3 that the spindle 3 is mounted between the bearing 4 attached to a frame member of the turntable, and an opposed bearing 5 which is fixed to the main beam 26 of the turntable.

The disk-brake assembly 30 of the invention is mounted on abutments 31 attached to the main beam 26. The disk-brake assembly comprises a main disk 32 which is fixedly attached to the shaft 3. Friction pads 33 are positioned to each side of the disk and may be moved in an axial direction against the surface of the disk by means of a cam 34.

The cam 34 is located between an outer plate 35 and an inner calliper 36 which carries the brake pads 33. When the cam 34 is activated it causes the callipers to move together to grip the disk.

The arrangement for activating the cam 34 is shown in more detail in Figure 4.

Figure 4 shows the shaft 3 and disk 32 to an enlarged scale. The cam 34 is moved by means of a lever 37. The outer (lower) end of the lever 37 is connected by a link 38 to the arm 39 of a cam-follower device.

The cam-follower is shown in more detail in Figure 5 and comprises the arm 39 which is formed with an elbow on the end of which is mounted a rotating roller 40. The arm 39 is bolted to a support member 41 carried by rubber buffers 42. The member 41 is angled, as shown in Figure 5, and is provided with a pair of elongate slots 43, 44 which coincide with slots 45, 46 of the cam follower 39. The slots 43, 44 allow horizontal adjustment of the cam follower, whereas the slot 45 allows vertical adjustment.

determine the length of movement of the belt for each rotation of the turntable 1. Typically, the belt is caused to move about 4 for each rotation.

The arrangement for activating the cam 34 is shown in more detail in Figure 4.

As shown in Figure 4, the end of the arm 39, remote from wheel 40, is attached to a tension spring 47. The tension from this spring is imparted, through link 38 to the lever 37 such that the lever is normally biased into the position shown in solid lines in Figure 4. In this position the disk brake is actuated to prevent rotation of the disk 32 and hence the shaft 3.

The cam comprising the roller 40 is adapted to engage with a ramp 50 which is mounted on the upper surface of the tipping platform 16, and which acts as a cam-follower for the roller 40.

The ramp 50 is located in an adjacent location to the indexing quadrant. Thus, when the turntable rotates and the sprocket engages with the indexing quadrant1 the roller 40 at the same time connects with the ramp 50 and rolls over the ramp, as shown in Figure 4. This causes the lever 37 to pivot, the pivoting movement being taken up by the rubber buffers 42. This in turn releases tension in the spring 47 and causes the lever 37 to move to the position shown in broken lines in Figure 4. In this position, the disk brake is released to allow the spindle 3 to rotate. The length of the ramp 50 is carefully chosen such that the disk break is released only while the sprocket is engaged with the indexing quadrant. Immediately the sprocket leaves the indexing quadrant, the roller 40 comes out of contact with the ramp 50 and the disk brake is reapplied thus preventing any further movement of the shaft 3.

Means are included to provide variations in the number of rollers in the indexing quadrant which in turn determines the degree of film overlap, and to allow for wear in the break pads and linkages.

The braking arrangement of the invention prevents any over-running of the shaft 3 or mechanical crashing due to reverse movement of the bales. Because the disk brake is totally disengaged during the meshing of the sprocket with the indexing quadrant there is no resistance to movement of the shaft 3 as is caused by the conventional brake band.

This results in more efficient and quieter operation of the machine.

Claims

1. A bale wrapping machine, comprising a turntable mounted for rotation about a generally vertical axis upon a platform, a pair of rollers mounted upon the turntable and adapted for rotation about generally horizontal axes, an endless belt fitted around the rollers and adapted to receive a bale to be wrapped, means for driving one of said rollers to rotate the endless belt about the rollers, said drive means comprising a drive shaft which is rotated when a cam on the shaft engages with a cam-follower on the platform with each rotation of the turntable about the platform, and means for controlling rotation of the shaft, wherein said control means comprises a brake which normally acts on the shaft to prevent rotation of the shaft but is adapted to be released to permit rotation of the shaft when the cam is in engagement with the cam-follower.

2. A bale wrapping machine as claimed in Claim 1, wherein the means for releasing the brake comprises a lever mechanism which on rotation of the turntable is adapted to engage with a ramp located on the platform to release the brake, the ramp being so located relative to the cam-follower that the brake is released when the cam is in engagement with the cam-follower.

3. A bale-wrapping machine as claimed in claim 2, wherein the lever mechanism comprises a lever which is connected by a link to a roller which is adapted to engage with the ramp.

4. A bale wrapping machine as claimed in any of the preceding claims, wherein the cam comprises a sprocket fixed on the shaft and the cam-follower comprises an indexing quadrant having a plurality of rollers which are adapted to engage with the sprocket

5. A bale wrapping machine as claimed in any of the preceding claims characterised in that the brake comprises a disc mounted on the drive shaft, friction pads mounted to each side of the disc, and adapted to be moved in an axial direction against the surface of the disc to prevent rotation of the disc and drive shaft on engagement of the brake.

6. A braking system for use with a bale wrapping machine of the kind including a turntable mounted for rotation about a generally vertical axis upon a platform, a pair of rollers mounted upon the turntable and adapted for rotation about generally horizontal axes, an endless belt fitted around the rollers and adapted to receive a bale to be wrapped, means for driving one of said rollers to rotate the endless belt about the rollers, said drive means comprising a drive shaft which is rotated when a cam on the shaft engages with a cam-follower on the platform with each rotation of the turntable about the platform, of Claim 1, said braking system comprising means for controlling rotation of said drive shaft, and wherein said control means comprises a brake which normally acts on the shaft to prevent rotation of the shaft but is adapted to be released to permit rotation of the shaft when a cam on the shaft is in engagement with a cam-follower.

7. A braking system substantially as hereinbefore described with reference to the accompanying drawings.

8. A bale wrapping machine substantially as hereinbefore described with reference to the accompanying drawings.