Patent Description:
In particular but not exclusively, the invention relates to an agricultural baler that makes round bales having a pair of circular end faces and a cylindrical circumferential surface. Such balers are generally referred to as "round balers". Typically, a round baler has a bale chamber in which the bale is formed and a binding mechanism that binds the bale by applying a binding material to the circumferential surface of the bale. The binding material, which may be stretch film or netting, binds the bale to prevent expansion of the compressed bale material after the bale is ejected from the bale chamber.

A round baler is typically configured to form a bale by implementing a baling process that includes a bale-forming phase in which a bale is formed, a binding phase in which the bale is bound with a binding material, and a cutting phase in which the binding material is cut, after which the bound bale may be ejected from the bale chamber.

During the bale-forming phase crop material is fed into the bale chamber and rotated by rotating pressing elements to form a bale. When the bale has reached a desired size or pressure the baler enters the binding phase in which a leading end of the binding material is presented to the outer surface of the bale. The binding material is then wrapped once or more around the circumference of the bale by feeding the binding material into the bale chamber while rotating the bale. After binding has been completed the supply of binding material is severed in the cutting phase and the bound bale is then either ejected from the bale chamber or wrapped within the opened bale chamber.

An apparatus for applying a binding material to the outer surface of an agricultural bale is described in <CIT>. This apparatus has a cycle of operation in which the leading end of the binding material is presented to the outer surface of the bale when the bale has reached a required size, the binding material is wrapped at least once around the bale (typically <NUM>-<NUM> times for netting or <NUM>-<NUM> times for film), and the supply of binding material from the apparatus to the bale is severed when binding of the bale has been completed. The binding mechanism includes a supply device for a supply of binding material and a feed mechanism that feeds the binding material from the supply device to the bale chamber. The feed mechanism includes a pull-off device that draws binding material from the supply reel and a feed mouth that feeds and guides the binding material to the outer surface of the bale. The feed mouth is moveable between an operative feeding position near to the outer surface of the bale where the binding material is presented by the feed mouth to the outer surface of the bale, and a retracted position which the feed mouth takes up when binding has been completed so that the binding material can be severed.

<CIT> describes an apparatus for tensioning wrap material in a baler, comprising a brake configured to slow the payoff of wrap material from a reel of wrap material and a controller that manipulates the brake. The apparatus enables a degree of passive control over the speed at which the wrap material is delivered to the bale chamber.

Lately, the demand for silage bales that are bound with stretch film instead of net binding material has increased, owing to the fact that if the bales are subsequently wrapped for full coverage with stretch film only one type of material is used for both binding and wrapping. Then, when the bale is to be used as silage, the film binding material and the film wrapping can be peeled off in one operation and can be more easily disposed of or recycled, as they do not need to be separated.

Film binding material needs to be stretched before it is fed into the bale chamber to provide a tight binding on the bale and to economise on film usage. The binding mechanism includes a supply device for a supply of binding material, and a feed mechanism that feeds the binding material from the supply device to the bale chamber. The supply device typically includes a pre-stretcher that stretches the film binding material lengthwise by about <NUM>-<NUM>%.

Additional stretching is usually provided between the feed mechanism and the bale chamber. The feed mechanism may for example include a pull-off device comprising a driven feed roller that feeds the film from the supply device to the bale chamber at a feed speed that is less than the circumferential speed of the bale as it rotates in the bale chamber. As a result, the film binding material is additionally stretched lengthwise between the feed mechanism and the bale chamber, typically by about <NUM>-<NUM>%.

As the film binding material is highly stretched during the binding phase, when the film is subsequently severed during the cutting phase the stretched film contracts and may spring back rapidly. As a result the severed end of film can be flung back and get caught up in the feed mouth or around rotating parts of the feed mechanism, causing a blockage that has to be cleared before binding can recommence.

A high degree of stretching is desirable to ensure that the bale is tightly bound and to economise on film usage. However, the risk of a blockage increases as stretching of the film is increased, owing to the increased tension in the film. This imposes a practical limit on the amount of stretching that can be applied to the film.

This problem may also be present when net binding material is used, but generally to a lesser degree as net binding material is not usually highly stretched during binding. However, it is still desirable to control the amount that the binding material springs back, even when net binding material is used. Therefore, reducing the risk of the binding material springing back after it has been cut may be important both for film binding material and net binding material, even though it is generally more important for film binding material.

It is an object of the present invention to provide a baler that mitigates one or more of the aforementioned problems.

According to an aspect the present invention there is provided a baler in accordance with claim <NUM>.

According to the present invention there is provided a baler configured to form a round bale by implementing a baling process that includes a bale-forming phase in which a bale is formed, a binding phase in which the bale is bound with a binding material, and a cutting phase in which the binding material is cut, the baler comprising:.

The rotary drive actively drives rotation of the rotary drive element during at least part of the binding phase and the cutting phase, thus ensuring that the binding material is drawn from the supply device and fed to the bale chamber at a controlled speed during both phases of the binding process. This avoids problems associated with prior art balers where the speed at which binding material is drawn from the supply device and fed to the bale chamber is controlled only passively, for example by braking the reel of binding material.

Optionally, the second feed speed S2 is equal to E*S1 where E is a coefficient in the range <NUM> to <NUM>.

Increasing the feed speed of the binding material from S1 to S2 during the cutting phase, before the binding material is cut, reduces the tension in the binding material and reduces the risk that it can spring back in an uncontrolled fashion, potentially causing a blockage within the feed mechanism. The reliability of the baler can thus be improved.

This also allows the amount of pre-stretching of the binding material during the binding phase to be increased, thereby increasing the tension in the binding to bind the bale more tightly and reducing the consumption of binding material.

Optionally, the circumferential speed SB of the bale during the binding process is greater than S1. Rotating the bale at a circumferential speed SB that is greater than the feed speed S1 during the binding phase causes stretching of the binding material between the pull-off device and the bale chamber, in addition to any stretching that may have been applied to the binding material previously.

Optionally, the circumferential speed SB of the bale during the binding process is equal to D*S1 where D is a coefficient in the range <NUM> to <NUM>. This is equivalent to an increase in the length of the binding material of <NUM>% to <NUM>%.

Optionally, S2 is equal to F multiplied by the circumferential speed SB of the bale during the cutting phase, where F is a coefficient in the range <NUM> to <NUM>. In other words, the second feed speed S2 during the cutting phase, before cutting, may be <NUM>% to <NUM>% faster than the circumferential speed SB of the bale during the binding phase.

Optionally, the pull-off device is configured to feed the binding material at a third feed speed S3 during at least one different part of the binding phase, where S3 is different from S1. In other words, the pull-off device may be operable to adjust the tension in the binding material during different parts of the binding process in order to control various properties of the binding.

As noted above, the pull-off device may be operable to adjust the tension in the binding material during different parts of the binding process in order to control various properties of the binding. For example, the baler may be configured to apply one or more layers of binding material at a first tension level then one or more further layers of binding material at a second, higher tension level to bind the bale more tightly and reduce the amount of binding material used. Alternatively, the tension may be reduced for the outermost layer or layers, to reduce the risk of tearing or unwinding. The rotary drive actively drives rotation of the rotary drive element during at least part of the binding phase and the cutting phase, thus ensuring that the binding material is drawn from the supply device and fed to the bale chamber at a controlled speed during both phases of the binding process.

Optionally, the pull-off device is configured to feed the binding material at a fourth feed speed S4 during a feeding phase of the baling process, during which a cut end of the binding material is introduced into the bale chamber prior to the binding phase. The fourth feed speed S4 may for example be equal to or slightly less than the speed at which a feed device carries a cut end of the binding material to the bale chamber, which may be useful to control the position of the cut end as it is introduced into the bale chamber. S4 may also be slower than the circumferential speed of the bale S4, for example approximately <NUM>*SB.

Optionally, the baler includes a controller that controls operation of the pull-off device during each phase of the baling process. The controller may for example be a computer or other electronic control device.

Optionally, the controller includes an operator interface that allows an operator to adjust one or more of the feed speeds of the pull-off device. The operator interface may optionally include a display and one or more operator controls, and/or a touch-sensitive display.

The pull-off device comprises a rotary drive element that draws the binding material from the supply device, for example a drive roller or a pair of rollers, and a rotary drive that drives rotation of the rotary drive element. The rotary drive may comprise a rotating component of the baler or it may be a separate drive motor, for example an electric or hydraulic motor.

Optionally, the rotary drive comprises a clutch that transfers rotary drive to the rotary drive element, wherein the clutch is configured to control the feed speeds of the pull-off device by adjusting slippage within the clutch. This allows the clutch to drive the pull-off device at different drive speeds without changing the input speed of the rotary drive.

Optionally, the clutch is an electromagnetic clutch in which slippage is controlled by a PWM control signal delivered to the electromagnetic clutch. The amount of slippage can for example be determined by a controller or it may be selected by an operator.

Optionally, the supply device includes a pre-stretcher device that stretches the binding material before it reaches the feed mechanism.

Optionally, the pre-stretcher device is configured to stretch the binding material lengthwise by a factor in the range <NUM> to <NUM>.

Optionally, the pre-stretcher device and the feed mechanism are configured to stretch the binding material lengthwise by a combined factor in the range <NUM> to <NUM>.

The binding material is a stretch film binding material.

Optionally, the feed mechanism includes a feed device between the pull-off device and the bale chamber, which is configured to transfer a cut end of the binding material to the bale chamber.

Optionally, the feed device is configured for movement relative to the supply device between a feed position adjacent a feed opening of the bale chamber, which the feed device adopts when feeding binding material into the bale chamber, and a retracted position spaced from the feed opening. The feed device may for example be configured for pivoting movement between the feed position and the retracted position.

<FIG> illustrates the main components of a round baler <NUM> according to an embodiment of the invention. The baler <NUM> may be of the variable chamber type or the fixed chamber type.

In this embodiment the baler <NUM> is a combined baler/wrapper machine, which includes a front section <NUM> where a bale is formed from bale material, and a rear section <NUM> where the bale is wrapped with a stretch film wrapping material. It should be noted that the invention is also applicable to balers that do not include an integrated wrapper section. In that case, bales formed by the baler <NUM> may optionally be wrapped subsequently using a separate wrapping machine as is well known in the art. It should also be noted that the wrapper comprising the rear section <NUM> may take alternative forms, as are known in the art. The wrapper illustrated is of a conventional orbital type and will not be further described.

The baler <NUM>, which in this embodiment is of the variable chamber type, includes a pick-up device <NUM> for picking up bale material, for example cut straw or grass, from the ground, a drawbar <NUM> for attaching the baler to a tractor, support wheels <NUM>, <NUM> and a plurality of press elements comprising elongate belts <NUM> that are guided around a set of rollers <NUM>, <NUM> and/or driven press rollers <NUM>, <NUM>, <NUM>. The belts <NUM> together with a pair of side plates (not shown) create a cylindrical bale chamber <NUM> in which a round bale can be formed. The pick-up device <NUM> is configured to feed the bale material into the bale chamber <NUM> through a crop mouth <NUM>. The sides of the baler <NUM> are covered by covers <NUM>. The baler may be driven, for example, via the power take off (PTO) of the tractor. Again, these components are conventional and will not be further described.

The baler also includes a binding apparatus <NUM> that is configured to apply a binding material, optionally a film binding material, to a cylindrical circumferential surface of the bale formed in the bale chamber to bind the bale, and a cutter device <NUM> that is configured to cut the film binding material after the bale has been bound. Additional components of the baler are shown in <FIG> and <FIG>, which show the internal mechanism of the baler with the covers <NUM> and belts <NUM> removed.

The binding apparatus <NUM> includes a supply device <NUM> for a supply <NUM> of film binding material. In this embodiment the supply <NUM> comprises two reels of film binding material, each reel being mounted on a separate support <NUM>. In this embodiment the supports <NUM> are each mounted on a pivot <NUM> which allows the support and the associated reel to pivot through <NUM> degrees from a vertical bundling position shown in <FIG>, <FIG>, <FIG> and <FIG> to a horizontal binding position shown in <FIG> and <FIG>. An actuator <NUM> is provided to drive rotation of the supports <NUM> and reels <NUM> between the vertical and horizontal positions. Alternatively, the reels may be mounted on a fixed supports so that they cannot be rotated to bundle the film binding material.

The supply device <NUM> also includes a pre-stretcher device <NUM> for stretching the film binding material lengthwise as it is drawn from the reel <NUM>. The pre-stretcher device <NUM> may be of a conventional kind, comprising two rollers that are driven at different circumferential speeds to stretch the film binding material lengthwise as it passes around the two rollers. A freely-rotating supply guide roller <NUM> located after the pre-stretcher device <NUM> also comprises part of the supply device <NUM>.

In this embodiment, the baler also includes a reel <NUM> of net binding material, which can be used instead of the film binding material if, for operational reasons, the use of net binding material is preferred. The provision of a net binding system is optional.

Further features of the binding apparatus <NUM> can be seen in <FIG>. The binding apparatus <NUM> comprises a feed mechanism <NUM> that supplies film binding material F from the supply <NUM> to the bale chamber <NUM>. The feed mechanism <NUM> includes a pull-off device <NUM> comprising at least one driven roller <NUM>, which can optionally be braked by an adjustable brake <NUM>. The pull-off device <NUM> may also include a freely rotating pinch roller <NUM> that cooperates with the driven roller <NUM> to grip the film F as it passes through the pinch between the rollers <NUM>, <NUM>. Alternatively, the pinch roller <NUM> may be driven or it may be omitted. The film binding material F may optionally be guided from the supply device <NUM> to the feed mechanism <NUM> by first and second freely-rotating feed guide rollers <NUM>, <NUM>'.

The pull-off device <NUM> can be actively driven from a drive pulley <NUM> via a drive belt <NUM> (see <FIG>). The drive belt <NUM> passes around a driven pulley <NUM>, which is connected to the driven roller <NUM> of the pull-off device <NUM> via clutch, for example an electromagnetic clutch <NUM>. The electromagnetic clutch <NUM> can be controlled electronically by a control signal, for example by a pulse-width modulation (PWM) control signal, to adjust the degree of slippage between the input and output sides of the clutch <NUM>. Alternatively, a different kind of clutch can be used that allows the slippage to be controlled. The control signal can be provided, for example, by a controller <NUM> (<FIG>). The pull-off device <NUM> can optionally be braked by the adjustable brake <NUM> after the binding material has been severed, to limit or prevent further driving of the binding material by the inertia of the pull-off device <NUM>.

As shown in <FIG>, the controller <NUM> may include an operator interface <NUM> that allows an operator to adjust the feed speed of the pull-off device <NUM> by adjusting the slippage of the clutch <NUM> as it transfers rotary drive from the driven pulley <NUM> to the pull-off device <NUM>. The controller <NUM> may be connected to receive sensor signals from one or more sensors including, for example, a bale speed sensor <NUM> that senses the circumferential speed SB of a bale as it rotates in the bale chamber and/or a feed speed sensor <NUM> that senses the feed speed (e.g.S1, S2, S3 and/or S4) of the binding material as it is fed by the pull-off device <NUM> to the bale chamber. Furthermore, the controller <NUM> may be connected to send control signals to one or more actuators that operate different components of the baler including, for example, a reel position actuator <NUM> that drives rotation of the supply reels between upright and horizontal positions to control bundling of the binding material, and/or a feed mouth actuator <NUM> that drives movement of a feed device between different operational positions, such as a feed position, a binding position and a cutting position.

In this embodiment the feed mechanism <NUM> includes an optional feed device <NUM>, which is located after the pull-off device <NUM>. In this embodiment the feed device <NUM> comprises a feed mouth with a pair of opposed feed elements, for example comprising upper and lower lips <NUM>, <NUM>. The lips <NUM>, <NUM> can be pressed against one another to define a narrow slot through which the film binding material F passes or opened apart to provide a wider slot.

Alternatively, the feed device <NUM> may comprise a single feed element, for example a plate, which takes the place of the lower lip <NUM> (the upper lip <NUM> being omitted).

The feed device <NUM> is mounted on an arm <NUM> that can pivot about a pivot point <NUM> (<FIG>). An actuator (not shown) is provided for driving pivoting movement of the pivot arm <NUM> and the feed device <NUM>.

Operation of the binding apparatus is illustrated in <FIG>. Referring first to <FIG>, this shows the configuration of the binding apparatus during the binding phase, in which a binding is applied to a round bale B in the bale chamber. The film binding material F is drawn from the supply reel <NUM> and passes through the pre-stretcher device <NUM>, which stretches the film lengthwise, typically by about <NUM>-<NUM>%. As the film is elastic this pre-stretching ensures that when the film is applied to the cylindrical surface of the bale B it is in tension so that it binds the bale tightly.

Optionally, the pre-stretcher device <NUM> may include a stretch adjustment mechanism for adjusting the amount of pre-stretching applied to the film. The stretch adjustment mechanism may for example comprise two or more gear sets between the rollers, which can be engaged alternately to provided different relative speeds between the rollers. Alternatively, the rollers may be connected to one another by a continuously variable transmission (CVT), a chain drive system with alternative gear wheel ratios, a belt drive or separate electric drive motors for the two rollers, allowing them to be driven at different speeds.

The film binding material F passes along a feed path from the pre-stretcher device <NUM> via the pull-off device <NUM> to the surface of the bale B via a feed opening <NUM> in the bale chamber <NUM>. The feed opening <NUM> is located between a pair of adjacent press elements comprising, in this case, an idler roller <NUM> that supports the belts <NUM> (if provided) and a driven press roller <NUM>. The feed opening <NUM> for the binding material is relatively narrow, having a width between the idler roller <NUM> and the press roller <NUM> of typically <NUM>-<NUM>.

The feed opening <NUM> is located away from the crop mouth <NUM> through which bale material is introduced into the bale chamber <NUM>. The crop mouth <NUM> is located between a second press roller <NUM> and a third press roller <NUM> below the feed opening <NUM>. The crop mouth <NUM> is much wider than the feed opening <NUM>, typically having a width of <NUM>-<NUM>. The feed path along which the film binding material F is fed from the pre-stretcher device <NUM> to the surface of the bale B is defined by various components of the feed mechanism <NUM> including the pull-off device <NUM> and the feed device <NUM>.

During binding of a bale, the bale B is rotated within the bale chamber <NUM> by the press elements, which may include belts and/or rollers. In the embodiment shown in <FIG> the bale B rotates in a clockwise direction indicated by arrow A and the press elements, which in this embodiment include both belts <NUM> and rollers (including the idler roller <NUM> and the driven press rollers <NUM>, <NUM> and <NUM>), rotate anti-clockwise. A tongue T of the film binding material F is fed into the bale chamber <NUM> though the feed opening <NUM>, between the two adjacent press elements (idler roller <NUM> and press roller <NUM>).

The film binding material F is drawn from the reel <NUM> primarily by rotation of the bale B within the bale chamber <NUM>. The pull-off device <NUM> is driven during binding of the bale, for example from the drive pulley <NUM>, via the drive belt <NUM> and the electromagnetic clutch <NUM> (see <FIG>). The drive belt <NUM> passes around a driven pulley <NUM>, which is connected to the driven roller <NUM> of the pull-off device <NUM> via the electromagnetic clutch <NUM>. The output speed of the magnetic clutch <NUM> can be adjusted by modulating the PWM control signal, which allows the pull-off device <NUM> to feed film towards the bale chamber at an adjustable feed speed.

Optionally, the pull-off device <NUM> can be braked by the adjustable brake <NUM> after the binding material has been severed, to limit or prevent further driving of the binding material by inertia.

During binding of the bale with film binding material, the pull-off device <NUM> is driven to feed film binding material at a speed that is less than the circumferential speed of the bale B in the bale chamber <NUM>. Typically, the pull-off device <NUM> may be driven at approximately <NUM>% of the circumferential speed of the bale B. Because the feed speed of the pull-off device <NUM> is less than the speed at which the film binding material is drawn by the bale, which is substantially equal to the circumferential speed of the bale, the binding material will be stretched between the pull-off device <NUM> and the bale chamber <NUM>, typically by about <NUM>-<NUM>%, ensuring a tight binding. This stretching of the binding material is in addition to any pre-stretching that may have been applied by the pre-stretcher device <NUM>.

If net is used to bind the bale, the net binding material is normally drawn from the supply entirely by rotation of the bale, without activating the pull-off device. However, the pull-off device may also be driven to feed the net at a speed less than the circumferential speed of the bale to apply a small amount of stretch to the net binding material.

If the film binding material starts to tear during binding, the actively-driven pull-off device <NUM> will continue to rotate, reducing the risk that the film binding material will tear across its full width.

During binding of the bale the feed device <NUM> is located in a binding position, which is approximately mid-way between the pull-off device <NUM> and the feed opening <NUM>, where it serves to guide the film binding material F from the pull-off device to the feed opening.

Optionally, during binding of the bale B the reel <NUM> may be located in the horizontal binding position so that the axis of the reel <NUM> is substantially parallel to the axes of the feed guide rollers <NUM>, <NUM>', the axis of the pull-off device <NUM>, the axes of the rollers <NUM>-<NUM> and longitudinal axis the cylindrical bale B. Therefore, there is no twisting of the plane of the film binding material F as it passes from the reel <NUM> to the surface of the bale B. This ensures that the film binding material F is spread to its full width as it is applied to the bale.

In this embodiment two strips of film binding material F are applied side by side to the cylindrical surface of the bale B to cover the width of the bale B. Alternatively, a single strip or more than two strips of film binding material F may be applied to bind the bale.

Once binding of the bale has been completed, the feed device <NUM> is retracted and the cutter <NUM> is activated to cut the binding material F, so that the bound bale B can be ejected from the bale chamber <NUM>. The configuration of the feed mechanism <NUM> after the film binding material F has been cut is illustrated in <FIG>.

It should be noted that in this embodiment the reels <NUM> of film binding material F have been rotated through <NUM> degrees from the horizontal binding position shown in <FIG> to a vertical bundling position, in which the axis of the supply guide roller <NUM> is perpendicular to the axes of the feed guide rollers <NUM>, <NUM>'. As a result, the film binding material F is gathered together to form a narrow strip of bundled film binding material as it passes over the feed guide rollers <NUM>, <NUM>'. The bundled strip of film binding material typically has a width of only <NUM>-<NUM>, compared to a width of typically <NUM> for the unbundled film binding material. Bundling of the film is optional and may be omitted if not required.

The bundled strip of film binding material passes through the pull-off device <NUM> and into the feed device <NUM>. When the feed device <NUM> is in the fully retracted position it adopts an open configuration as shown in <FIG>, where the two lips <NUM>, <NUM> are spaced apart to form a substantially vertical open passageway <NUM>.

Optionally, the feed device <NUM> may be opened when it reaches the retracted position by the engagement of a roller <NUM> with a fixed part <NUM> of the frame of the baler. This causes the lower lip <NUM> to pivot open about a pivot <NUM>. When the feed device <NUM> is in the open configuration, the pull-off device <NUM> can be driven to feed a length of film binding material F through the feed device <NUM> to increase the length of the cut end of the film binding material that extends from the front end of the feed device <NUM>. If the film material has been bundled this cut end of bundled film binding material forms a relatively stiff tongue T of film binding material that extends from the end of the feed device <NUM>.

The length of the tongue T can be adjusted by controlling operation of the pull-off device <NUM>, for example by adjustable braking of the pull-off device and/or by operation of the electromagnetic clutch <NUM>. Optionally, operation of the pull-off device <NUM> can be controlled automatically for example by an electronic control system or a computer based on a number of factors including, for example, one or more of the following factors: a user setting for a long or short tongue, the PTO speed, the stretch setting of the pre-stretcher device <NUM>, and environmental conditions such as temperature or humidity.

<FIG> illustrates the feed mechanism <NUM> in a holding configuration, which it adopts while a bale is being formed in the bale chamber <NUM>. The feed device <NUM> has moved forward from the retracted position shown in <FIG> and the upper and lower lips <NUM>, <NUM> have closed, gripping the tongue T of film binding material that extends from the feed device. Because the feed device <NUM> is closed, the cut end of the film material is held securely and cannot blow around, for example in windy conditions. Also, because the feed device <NUM> is closed, dust and dirt from the baler cannot enter the mouth of the feed device.

<FIG> illustrates the feed mechanism <NUM> in the feeding position, in which the cut end of the film binding material (the tongue T) is fed by the feed device <NUM> into the bale chamber <NUM> through the feed opening <NUM>. The feed device <NUM> has pivoted forwards towards the bale chamber <NUM> so that the tongue T is caught between the rotating bale B and the press roller <NUM>, thus drawing the film binding material into the bale chamber <NUM>. It will be noted that the feed device <NUM> extends into the narrow feed opening <NUM> between the press elements (rollers) <NUM>, <NUM>, so that the position of the tongue T is closely controlled.

The tongue T is optionally formed from bundled film binding material, which has a much greater stiffness that unbundled film binding material. This makes it easier to control the position of the tongue during feeding. The length of the tongue T may be controlled by operating the pull-off device <NUM> as described above, to ensure that it passes correctly through the feed opening <NUM> and is caught by the bale B.

As the feed device <NUM> moves forwards from the holding position to the feed position, the pull-off device <NUM> is driven by the arc gear <NUM> to draw film binding material from the supply device <NUM>. The pull-off device <NUM> is configured to draw a length of film binding material that is less than the length required to accommodate movement of the feed device <NUM> from the holding position to the feed position. As a result, the tongue T is partially drawn back into the mouth of the feed device <NUM>, which causes the tongue T to stand up in a more erect position. This allows it to be fed more accurately through the feed opening <NUM>. The length of the tongue T is sufficient to allow it to be caught between the rotating bale B and the press roller <NUM>, so that the film binding material is drawn around the cylindrical surface of the bale B as it rotates.

Once the tongue T of film binding material has been caught by the bale B, binding of the bale can commence. The feed mouth <NUM> is partially retracted from the feed opening <NUM> to the binding position shown in <FIG>. In this embodiment the reel <NUM> of film binding material is rotated to the horizontal binding position so that the film binding material F is not bundled as it is drawn off the reel. The film binding material F is stretched by the pre-stretching device <NUM>, to increase the length of the film binding material, for example by a stretch ratio of about <NUM>-<NUM>%. The pull-off device <NUM> is activated to draw film from the supply, but it is driven to feed the binding material at a speed S1 that is less that the circumferential speed SB of the bale in the bale chamber, so that the film is additionally stretched by about <NUM>-<NUM>% as it is drawn into the bale chamber <NUM> by rotation of the bale B. In the event that the film binding material starts to tear, the pull-off device <NUM> will continue to feed the film towards the bale chamber, to ensure that the tear does not spread across the entire width of the film.

The film binding material F passes through the feed device <NUM> and is drawn over the edges of the upper lip <NUM>, which spreads the film so that the two strips of film cover the full width of the bale. Most of the stretching of the film takes place as the film is drawn over the edges of the upper lip <NUM>, owing to friction between the film and the lip. Thus, the maximum tension occurs in the section of the film between the lip and the bale. The total amount of stretching is controlled by adjusting the degree of slippage in the clutch <NUM>, thereby adjusting the difference between the feed speed S1 of the film by the pull-off device <NUM> and the speed at which the film is drawn into the bale chamber by rotation of the bale at the circumferential speed SB. Binding continues until an adequate thickness of film binding material has been applied to the cylindrical surface of the bale B. Typically, this may require three to five layers of film binding material.

Once binding of the bale has been completed, the reel <NUM> of film binding material F may optionally be rotated back to the vertical bundling position shown in <FIG>, so that the film binding material is gathered together into a narrow, bundled strip. The speed of the pull-off device <NUM> is then increased, preferably to feed the binding material at a feed speed S2 that is greater than S1 and optionally greater than the circumferential speed SB of the bale in the bale chamber, to reduce stretching of the film. The cutter device <NUM> is then activated to cut the film between the feed device <NUM> and the feed opening <NUM>, and the brake <NUM> is applied to halt rotation of the pull-off device <NUM>. The feed device <NUM> is then retracted fully, causing the feed device to open. The bound bale can then be ejected from the bale chamber <NUM>.

As the film binding material F has been stretched by the pre-stretcher device <NUM>, it is under tension. Therefore, when the film binding material is cut, the tongue T contracts into the feed device <NUM> towards the pull-off device <NUM>. The feed speed of the pull-off device <NUM> is increased prior to cutting to the tension in the binding material and prevent the tongue T from springing back excessively.

After cutting, the pull-off device <NUM> is actuated to feed an additional length of film binding material towards the feed device <NUM>, to increase the length of the tongue T that extends from the end of the feed device <NUM>. As the mouth of the feed device <NUM> is open, the film binding material falls freely through the passageway <NUM>. Once the correct length of the tongue T has been fed through the feed device <NUM>, the pull-off device <NUM> is deactivated, for example by disengaging the electromagnetic clutch <NUM>.

Optionally, the feed device <NUM> may then be moved forward from the fully retracted position to the holding position shown in <FIG>. As it moves to this position, the mouth of the feed device <NUM> closes, gripping the tongue T of film material between the lips <NUM>,<NUM>. The feed device <NUM> remains in the holding position until the next bale has been formed in the bale chamber <NUM>.

Upon completion of the bale, the feed device <NUM> moves to the feed position shown in <FIG> to repeat the binding process. During movement of the feed mouth <NUM> from the holding position shown in <FIG> to the feeding position shown in <FIG>, the pull-off device <NUM> is driven by an arc gear <NUM> to draw a length of film binding material that is less than the length required to accommodate movement of the feed mouth <NUM> from the holding position to the feed position, so that the tongue T is drawn partially back into mouth of the feed device <NUM>. This causes the tongue T to adopt an erect position in which it can be inserted more easily into the feed opening <NUM>.

In an embodiment of the invention, the baler is configured to form a round bale by implementing a baling process that includes a bale-forming phase in which a bale is formed, a binding phase in which the bale is bound with a binding material, and a cutting phase in which the binding material is cut.

The pull-off device <NUM> is configured to feed the binding material at a first feed speed S1 during the binding phase and at a second feed speed S2 during the cutting phase, where S2 is greater than S1. The cutting phase may include first increasing the feed speed of the pull-off device <NUM> and then activating the cutter <NUM> to cut the binding material. Increasing the feed speed of the pull-off device <NUM> from S1 to S2 during the cutting phase reduces the tension in the binding material before it is cut, thereby reducing the risk that the cut end of binding material will spring back and cause an obstruction in the feed mouth or become wound around the feed mechanism. Optionally, S2 is equal to E. S1 where E is a coefficient in the range <NUM> to <NUM>.

Optionally, during the binding phase the bale B rotates in the bale chamber with a circumferential speed SB, where SB is greater than S1. This increases the tension in the binding material. Optionally, SB is equal to D. S1 where D is a coefficient in the range <NUM> to <NUM>.

Optionally, the pull-off device <NUM> may be configured to feed the binding material at a third feed speed S3 during part of the binding phase, where S3 is different from S1. By varying the feed speed during the binding phase the tension in the binding material in different parts of the binding can be adjusted. For example, a first layer of the binding can have a lower tension than a second layer, to reduce the risk of tearing. The pull-off device <NUM> may also be configured to feed the binding material at a fourth feed speed S4 during a feeding phase of the baling process, during which a cut end of the binding material is introduced into the bale chamber prior to the binding phase.

In the embodiments described above, the binding material is described primarily as film binding material. However, the invention is also applicable to other types of binding material including net binding material.

The invention is primarily described in relation to a baler that includes a bundling device for bundling the binding material to produce a bundled tongue. However, the invention is also applicable to balers that do not have a bundling device, in which an unbundled tongue of binding material is fed into the bale chamber.

The feed device <NUM> is described above primarily as a feed mouth that includes upper and lower feed elements/lips <NUM>, <NUM>. Alternatively, the feed device may include only a single feed element equivalent to the lower feed element <NUM>, which may for example take the form of a plate, the upper feed element <NUM> being omitted.

A second embodiment of the invention is illustrated in <FIG>. This embodiment is identical to the first embodiment shown in <FIG>, except as described below.

As shown in <FIG>, a speed sensor <NUM> is provided for monitoring the speed of the film binding material F at the pull-off device <NUM> as it is supplied to the bale chamber <NUM> during the binding process.

In this embodiment the speed sensor <NUM> comprises a freely rotatable detection roller <NUM>, which extends across the width of the baler between the two pivot arms <NUM>. Optionally, the detection roller <NUM> may be divided lengthwise into two parts 92a, 92b so that if two strips of film binding material F are used to bind the bale, each of the roller parts 92a, 92b contacts one of the strips of film binding material F. In this embodiment the detection roller <NUM> is located in the upper part of the feed mouth <NUM>, just behind the rear edge of the upper lip <NUM>. However, it may alternatively be mounted elsewhere, for example between the feed rollers <NUM>,<NUM> and the feed mouth <NUM>.

The detection roller <NUM> is located in the path of the film binding material F and it is positioned so that the film binding material F runs over the surface of the detection roller <NUM> during the binding process. Contact with the film binding material causes the detection roller to <NUM> rotate as the binding material is drawn into the bale chamber <NUM> by rotation of the bale B.

Rotation of the detection roller <NUM> is detected by at least one rotation sensor <NUM>, which is associated with the detection roller <NUM>, to detect rotation thereof. Various kinds of sensor can be used for the rotation sensor <NUM>. For example, the rotation sensor <NUM> may comprise an optical sensor that detects light reflected from a mark <NUM> provided on the surface of the detection roller <NUM>, or it may comprise a magnetic sensor that senses a magnetic marker on the roller, or a Hall-effect sensor, or a contact sensor, or numerous other kinds of sensor.

Instead of a detection roller, the speed sensor <NUM> may comprise a non-contact sensor that senses movement of the film binding material as the binding material is drawn into the bale chamber, without contacting the binding material. For example, a non-contact speed sensor <NUM> may comprise an optical sensor, an ultrasonic sensor, a Doppler sensor or any other suitable sensor. Alternatively, the speed sensor <NUM> may be configured to sense the rotational speed of one of the rollers <NUM>, <NUM> of the pull-off device.

Claim 1:
A baler configured to form a round bale (B) by implementing a baling process that includes a bale-forming phase in which a bale (B) is formed, a binding phase in which the bale (B) is bound with a binding material (F), and a cutting phase in which the binding material (F) is cut, the baler comprising:
a bale chamber (<NUM>) in which a bale (B) is formed during the bale-forming phase,
a bale drive mechanism that rotates the bale (B) in the bale chamber (<NUM>) with a circumferential speed SB,
a binding mechanism that binds a bale (B) in the bale chamber (<NUM>) during the binding phase by wrapping a binding material (F) around a circumferential surface of bale, where the binding material is a stretch film binding material (F), and
a cutter device (<NUM>) that cuts the binding material (F) during the cutting phase,
the binding mechanism including:
a supply device (<NUM>) that holds a supply of binding material (F) and
a feed mechanism (<NUM>) that feeds the binding material (F) from the supply device (<NUM>) to the bale chamber (<NUM>),
wherein the feed mechanism (<NUM>) includes at least one pull-off device (<NUM>) that draws binding material (F) from the supply device (<NUM>) and feeds the binding material (F) to the bale chamber (<NUM>), wherein the pull-off device (<NUM>) comprises a rotary drive element (<NUM>) and a rotary drive that drives rotation of the rotary drive element (<NUM>), and wherein the pull-off device (<NUM>) is configured to feed the binding material (F) at a first feed speed S1 during at least a part of the binding phase and at a second feed speed S2 during the cutting phase, where S2 is greater than S1 and S2 is greater than the circumferential speed SB of the bale during the cutting phase, characterised in that the rotary drive actively drives rotation of the rotary drive element (<NUM>) during at least part of the binding phase and the cutting phase, thereby ensuring that the binding material (F) is drawn from the supply device (<NUM>) and fed to the bale chamber (<NUM>) at a controlled speed during both phases of the binding process.