Doctor blade handling system

A doctoring apparatus has a flexible doctor blade advanced longitudinally across a surface being doctored. The doctor blade is feed in a continuous length from a storage cartridge and sequentially supported in a blade holder to apply the blade to a moving surface to be doctored. One or both of a pneumatic blade advancing device and a pneumatically operated clamping system are opened and closed in timed sequence with reciprocation of the blade holder longitudinally shifting the doctor blade in a selected direction across the doctored surface. The pneumatic blade advancing device includes an idler roller and a powered roller that co-operate to indexingly advance the doctor blade along the blade path. The clamping system includes a blade cutter to cut the doctor blade and that drives the cut off end of the doctor blade into a discard container.

FIELD OF THE DISCLOSURE

The present disclosure relates to a doctoring apparatus having a flexible doctor blade that is advanced longitudinally across a surface being doctored. More specifically, the present disclosure relates to continuously feeding a flexible doctor blade longitudinally through a blade holder to one or more of a pneumatic blade advancing device and a pneumatically operated clamping system, each of which operate in timed sequence with reciprocation of the blade holder, to achieve, longitudinal shifting of the doctor blade in a selected direction across the doctored surface and to cut the free-end of the used doctor blade for disposal.

BACKGROUND

In the discussion that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art against the present invention.

Doctor blades are used in many coating operations, including to level or remove excess material from a surface being coated and in releasing operations applied to products casted in thin layers (for example, tobacco). Typically, the angle of contact is controlled to achieve the desired result. Oscillation of the doctor blade, usually by oscillation of the entire doctor blade assembly, contributes to more even wear and more even coating as well as to an effective product release.

Typically, doctor blades are made of an inexpensive material and are replaced as they wear. Replacement can be by removal of the blade, usually removal of a blade and its holder (as in a so-called “cut-to-length” system), or by continuous or intermittent feeding of an elongated doctor blade to a blade holder (as in a so-called “pull through” system”). When fed continuously, the elongated doctor blade is typically unwound from a supply reel, fed into a blade holder, and wound on a take-up reel. Clamping systems operate to hold the doctor blade in operative position and also to advance the elongated doctor blade from supply reel to take-up reel. When the trailing end of one elongated doctor blade leaves the supply reel, the now empty reel is removed and replaced by a new supply reel containing a fresh coil of elongated doctor blade and, after any initial set up, the operation of the apparatus continued. Representative doctor blades and “pull through” system” doctor blade apparatus are disclosed in U.S. Pat. Nos. 5,007,132; 5,138,740, 5,264,035; and 5,782,976, the entire contents of which are incorporated herein by reference.

SUMMARY

It is desirable to improve the doctoring apparatus for pull through systems with doctor blade feeding and clamping systems. For example, it is desirable to make improvements and introduce innovations in doctor blades that reduce lost production time and simplify the exchange or replacement of supply reels containing a fresh coil of elongated doctor blade to allow a nearly continuous mode of operation of the doctoring apparatus.

An exemplary embodiment of a pull through doctor blade handling system comprises means for mounting a supply source for an elongated doctor blade, a blade holder including a blade back with a seat for releasably holding a portion of the doctor blade, a pneumatic multi-position cylinder unit including a blade clamp and a blade cutter, a blade path for the doctor blade, the blade path running from proximate the means for mounting the supply source, through the blade holder, and to the pneumatic multi-position cylinder unit, and an oscillation system operably connected to the blade holder to translate the blade holder, relative to the blade path, reciprocatingly between a first position and a second position, wherein, in the first position, the blade holder is operably proximate a portion of a surface to be coated, and wherein, in the second position, the blade holder is closer to the blade clamp than in the first position.

Another exemplary embodiment of a pull through doctor blade handling system comprises means for mounting a supply source for an elongated doctor blade, a blade holder including a blade back with a seat in which a portion of the doctor blade is positioned, a pneumatic blade advancing device including an idler roller and a powered roller, a pneumatic multi-position cylinder unit including a blade clamp and a blade cutter, a blade path for the doctor blade, the blade path running from proximate the means for mounting the supply source, through the blade holder, through the pneumatic blade advancing device and to the pneumatic multi-position cylinder unit, and a biasing system operably connected to the blade holder to move an edge of the doctor blade seated in the blade holder between a biased position and an unbiased position, wherein, in the biased position, the edge of the doctor blade is in force-exerting contact with a surface to be doctored, an oscillation system operably connected to the blade holder to translate the blade holder, relative to the blade path, reciprocatingly between a first position and a second position, wherein, in the first position, the blade holder is operably proximate a portion of a surface to be coated, and, in the second position, the blade holder is closer to the blade clamp than in the first position, and wherein the idler roller and the powered roller are translatable, relative to each other, between a closed position in which surfaces of the idler roller and the powered roller exert a pressure to the doctor blade and an open position in which the surface of at least one of the idler roller and the powered roller is spaced apart from the doctor blade.

An exemplary method of advancing a pull through doctor blade longitudinally across a surface being doctored by a series of translations of a blade holder comprises the steps of: (a) frictionally engaging a first portion of an elongated, continuous doctor blade with the blade holder, (b) translating the blade holder in a first direction to pay out the elongated, continuous doctor blade from a supply source and to extend a free end of the doctor blade through a cutting zone of a blade cutter, (c) clamping the elongated, continuous doctor blade in a blade clamp, (d) cutting off a free end of the doctor blade with the blade cutter, (e) translating the blade holder in a second direction to slidably move the blade holder from frictionally engaging the first portion of the doctor blade to frictionally engaging a second portion of the doctor blade, and (e) unclamping the doctor blade in the blade clamp.

Another exemplary method of advancing a pull through doctor blade longitudinally across a surface being doctored comprises the steps of (a) biasing the blade holder to be in force-exerting contact with a surface to be doctored, wherein the force imparted to the doctor blade frictionally engages the doctor blade with a seat of the blade holder, (b) translating the blade holder in a first direction from a first position to a second position to pay out the elongated, continuous doctor blade from a supply source and to advance a portion of the doctor blade into a clamping zone of a pneumatic blade advancing device, (c) clamping the elongated, continuous doctor blade in a stationary position relative to a blade path of the doctor blade, (d) unbiasing the doctor blade, and (e) translating the blade holder in a second direction to slidably move the doctor blade relative to the seat of the blade holder as the blade holder moves from the second position toward the first position.

A further exemplary method of advancing a pull through doctor blade longitudinally across a surface being doctored comprises the steps of (a) removing or reducing frictional contact between a doctor blade and a blade seat of the blade holder by removing or reducing a bias on a blade holder to remove or reduce a force-exerting contact between a portion of the doctor blade and a surface to be doctored, (b) placing a pneumatic blade advancing device in a closed position, wherein, in the closed position, surfaces of an idler roller and a powered roller exert a pressure to the doctor blade, (c) rotating the powered roller of the pneumatic blade advancing device to move the doctor blade along the blade path and through the blade seat of the blade holder a length sufficient to position a new portion of doctor blade to be in contact with the surface to be doctored, and (d) biasing the blade holder to establish a force-exerting contact between a portion of the doctor blade and a surface to be doctored, wherein the force imparted to the doctor blade frictionally engages the doctor blade with a seat of the blade holder.

DETAILED DESCRIPTION

A schematic illustration of an exemplary embodiment of a doctor blade handling system in a doctoring apparatus is shown inFIGS. 1A and 1B. The exemplary embodiment of the doctoring apparatus1comprises an elongated and continuous doctor blade10, a rotating cylinder20rotatable on axis and having a first axial end24and a second axial end26and a circumferential surface28on which the surface to be doctored30is located, and a doctor blade handling system40. The illustrated doctor blade handling system40is of the “pull through” type.

The elongated and continuous doctor blade10is generally sufficiently flexible to be wound along a blade path from a supply source50, through intermediate features of the doctoring apparatus1including features of the doctor blade handling system40, to a discharge end60. As seen inFIGS. 1A and 1B, the elongated, continuous doctor blade10positioned in the example blade path extends past the first and second axial ends24,26of the rotating cylinder20. By extending past the axial ends, the doctor blade10is assured of being in position for doctoring processes on any portion of the rotating cylinder20, including if the entire rotating cylinder20is the surface to be doctored30. Furthermore, flexibility of the doctor blade10allows the doctor blade10to be compactly stored in the supply source50. For example, the doctor blade can be coiled onto a blade cartridge or can be serpentinely layered in a container for unconstrained removal and feeding to the doctor blade handling system40.

A collection device can be positioned at the discharge end60to collect the doctor blade10, or portions of the doctor blade10, as they are cut discharged. InFIG. 1A, the collection device is illustrated as a box62, but any container can be used as long as it is capable of being suitably positioned and has a suitable size and capacity to hold the cut off ends of the doctor blade10that are formed at the discharge end60of the doctor blade handling system40.

The doctor blade handling system40will now be described further in connection withFIGS. 1A, 1B and 2. Exemplary embodiments of the doctor blade handling system40comprise means for mounting70a supply source for an elongated, continuous doctor blade10, a blade holder80including a blade back82and a blade seat84for releasably holding a portion of the doctor blade10; a pneumatic multi-position cylinder unit100including a blade clamp110and a blade cutter120, and an oscillation system130operably connected to the blade holder80. Within the pull through doctor blade handling system40, the blade path runs from proximate the means for mounting70the supply source, through the blade holder80, and to the pneumatic multi-position cylinder unit100.

Means for mounting70a supply source for the doctor blade10can be any suitable means70on which a supply source50can rest and which facilitates the supply of the doctor blade10to the doctor blade handling system40. For example, for supply sources that have wound doctor blades, means for mounting can be a spindle or other rotatable device and can include a mating feature at a distal end to facilitate attachment of the supply source, rotation of the supply source, and the transfer of any rotational motion to the supply source. In another example, for supply sources that have layered or serpentine storage of doctor blades, means for mounting can be a surface for a container and a moving arm to guide the doctor blade being pulled from the supply source by the doctor blade handling system and to minimize tangling. In a specific example, the supply source is in the form a rotatable reel doctor blade cartridge attached to a means for mounting the supply source in the form of a rotatable spindle attached to a motor for powered rotation and tensioning. Attachment can be by mating correspondingly shaped male and female features or threaded features on the distal tip of the spindle and in the cartridge.

As seen inFIGS. 1A and 1B, blade holder80extends longitudinally in a common direction with the blade path as it traverses the rotating cylinder20in a desired orientation for doctoring. It will be understood that the rotating cylinder depicted inFIGS. 1A and 1Bcan be replaced by other surfaces to be doctored, such as a surface on a shifting belt. In the illustrated example, the blade holder80is oriented in the axial direction from the first axial end24to the second axial end26. The blade holder80has a blade back82in a first portion and a blade seat84in a second portion. The blade seat84releasably holds a portion of the doctor blade10, e.g., an intermediate portion12of the doctor blade10, with a suitable orientation with respect to the surface being doctored30to apply or manipulate the coating or other material in the doctoring process. In an exemplary embodiment, the blade seat84can incorporate a slit with opposing surfaces and the intermediate portion12of the doctor blade10can be held in the blade seat84in a releasable friction fit between the intermediate portion12and the opposing surfaces of the slit. The friction fit results from, for example, the thickness of the doctor blade10being larger than the corresponding width of the slit, e.g., the separation distance between opposing surfaces of the slit, or, in alternative example, in the width of the slit being adjustable such that it releasably contacts the intermediate portion12of the doctor blade10to form a friction fit and then releases the intermediate portion12during reciprocation of the blade holder80(discussed further herein). The blade holder80applies a working edge14of an intermediate portion12of the doctor blade10to the surface being doctored30. The doctor blade10has a bottom edge16which is parallel to a working edge14and which is supported in the blade holder80. The blade back82is adjustable to urge the blade holder80towards the rotating cylinder20, thus applying the working edge14of the doctor blade10to the surface to be doctored30in a suitable manner.

Relative to the blade path, the blade holder80reciprocates between a first position (an example of which is shown inFIG. 1A) and a second position (an example of which is shown inFIG. 1B) in the direction indicated by arrow M. In the first position, the blade holder80is operably proximate a portion of a surface to be coated30with the blade holder80positioned axially between the first and second axial ends24,26of the rotating cylinder20. In the second position, the blade holder80has moved downstream (relative to the direction of motion of the blade path from supply source50to discharge end60). In the exemplary embodiment shown, when the blade holder80moves in the downstream direction, the second position of the blade holder80is closer to the discharge end60than is the first position. Alternatively, in the second position the blade holder80is proximate the circumferential surface of the rotating cylinder20with at least a portion of the blade holder80positioned axially outside one of the first and second axial ends24,26of the rotating cylinder20.

An oscillation system130is operably connected to the blade holder80to cause reciprocating translation motion. In the exemplary embodiment ofFIGS. 1A and 1B, the oscillation system130includes an electric drive system with an electric gear motor132provided with a crank throw134and a connecting rod136. This connecting rod138is directly connected to the blade holder80. When electric gear motor132operates, the crank throw134rotates and the connecting rod136reciprocates, causing reciprocating motion in the connected blade holder80and its associated features.

An exemplary embodiment of a pneumatic multi-position cylinder unit is illustrated inFIG. 2. The pneumatic multi-position cylinder unit100includes a blade clamp110and a blade cutter120. The blade clamp110can be pneumatically actuated and is arranged to act on a continuing portion of the doctor blade10and is operable between a closed position in which a surface of the blade clamp contacts the doctor blade with sufficient force that relative translational movement between the doctor blade10and the surface to be doctored30is prevented and an open position in which such relative movement is permitted. The blade cutter120can also be pneumatically actuated and is arranged to act on a portion140of the doctor blade10that extends past a cutting zone142and presents a free end144of the continuous doctor blade10. In an open position of the blade cutter120, the doctor blade10can be freely moved through a cutting zone142; in a closed position of the blade cutter120, the cutting blade has traversed through the cutting zone142and separated, e.g., cut, the portion140from the doctor blade10, which portion140is then collected for discarding.

Also illustrated in the exemplary embodiment of a pneumatic multi-position cylinder unit inFIG. 2is the arrangement to operate the blade clamp110and a blade cutter120. The arrangement includes master valve200and electrically operated pneumatic valves202,204in communication with pneumatic operated pistons206,208via one or more pneumatic lines210,212. Pneumatic line210is in fluid communication with chambers214,216for the piston head at a location that is above the respective piston head218,220and pneumatic line212is in fluid communication with chambers214,216for the piston head at a location that is below the respective piston head218,220. Thus, supplying pressure to pneumatic line210while venting pneumatic line212establishes a differential pressure across the respective piston head218,220to move the pistons206,208in a first direction D, equivalent to downward inFIG. 2, and supplying pressure to pneumatic line212while venting pneumatic line210establishes a differential pressure across the respective piston head218,220to move the pistons206,208in a second direction U, equivalent to upward inFIG. 2. This pneumatic operation provides the actuation of blade clamp110and blade cutter120, either sequentially or simultaneous depending on the control of the electrically operated pneumatic valves202,204. Although discussed here using the term pneumatic and implying a gas or air operated system, it should be understood that the relevant features and operation are not limited to gas or air operation but could also be implemented with features and operation based on hydraulics, i.e., a fluid operated system, or with a combination of pneumatic and hydraulic features.

Exemplary embodiments of a pull through doctor blade handling system40also include a sensor300proximate the blade holder80and a control unit400operably connected to the oscillation system130, the pneumatic multi-position cylinder unit100and the sensor300. An example of a sensor300is an inductive switch. In exemplary embodiments, the sensor300discriminates between the blade holder80located in the first position and the blade holder80not in the first position or, for example, located in the second position.

The blade clamp110is opened and closed in timed sequence with reciprocation of the blade holder80to achieve longitudinal shifting of the doctor blade10in a selected direction across the doctored surface, from supply source50to discharge end60. Additionally, the blade clamp110and blade cutter120can be used to clamp and to cut the worn doctor blade. The blade cutter120can also be used to drive the cut-off portion140of the doctor blade into the collection device.

The control unit400coordinates the operation and sequence of the oscillation system130, the blade holder80and the pneumatic multi-position cylinder unit100, based on position information communicated from the sensor300. The operations and sequence include:

(i) moving the blade holder80from the first position to the second position,

(ii) moving the blade clamp110to the clamping position,

(iii) cycling the blade cutter120between the open position and the cutting position,

(iv) moving the blade holder80from the second position to the first position, and

(iv) moving the blade clamp110to the open position.

Moving the blade holder80from the second position to the first position before moving the blade clamp110to the open position, e.g., before unclamping the doctor blade10from blade clamp110, slidably moves the blade holder80from frictionally engaging a first portion of the doctor blade10to frictionally engaging a second portion of the doctor blade10. In this way, the doctor blade10is longitudinal shifted in a selected direction across the surface to be doctored30.

In a more detailed description of the operation of the embodiment inFIGS. 1A and 1B, the blade holder80shifts from the first position to the second position (the second position downstream in a direction of the blade path from the first position) and sensor300communicates positional information of the blade holder80to the control unit400, which is connected to the solenoid of the pneumatic valves202,204. In the illustrated configuration inFIG. 2, valve202is operated first then valve204is operated. By this staggered operation, pneumatic fluid is first supplied to chamber214and then to chamber216of pneumatic multi-position cylinder unit100. As a consequence of this sequencing, the blade clamp110is closed first, then the blade cutter120is actuated to cut the doctor blade10. Typically, actuation of the blade cutter120cycles from open to closed and returns to the open position. When the blade holder80is shifted in the opposite direction and back to the first position, the doctor blade10is prevented from moving by the still closed blade clamp110, thus shifting the doctor blade10relative to the blade holder80. Once returned to the first position, the sensor300updates the control unit400, which operates the pneumatic valve202to cause the blade clamp110to actuate to the open position. When the next stroke of the oscillation system130occurs, the blade path is again open and the blade holder80will move again to the second position while frictionally engaged with the doctor blade10and pull the doctor blade10forward on the blade path. In this way, the doctor blade10is incrementally shifted longitudinally across the cylinder20from a supply source50to a discharge end60.

During doctoring operation, the blade holder80is oscillated by the oscillation system, and the blade clamp110and blade cutter120are employed in timed sequence with this oscillation to shift the doctor blade10longitudinally and in an indexed-like fashion across the surface of the cylinder20, with doctor blade10being gradually pulled from supply source50and cut-off by blade cutter120and collected in collection device, such as box62. The handling system allows for the continuous or nearly continuous supply and disposal of the doctor blade.

When a first doctor blade10has been passed through the doctor blade handing system40and the trailing end of the doctor blade leaves the supply source50, that supply source50is replaced by a new one containing a second doctor blade10. This having been accomplished, the doctoring operation is momentarily interrupted, the blade clamp110and blade cutter120are set to an open position and the leading end of the second doctor blade10is then advanced by the operator along the blade path through the blade clamp110and blade cutter120. The second doctor blade10is also attached to the blade holder80. Then the doctoring operation is continued and, when full, the collection device containing the cut pieces of doctor blade is replaced by an empty one.

A schematic illustration of another exemplary embodiment of a doctor blade handling system in a doctoring apparatus is shown inFIG. 3. The exemplary embodiment of the doctoring apparatus500comprises an elongated and continuous doctor blade510, a rotating cylinder520rotatable on an axis and having a first axial end524and a second axial end526and a circumferential surface528on which the surface to be doctored530is located, and a doctor blade handling system540. The illustrated doctor blade handling system540is of the “pull through” type.

The elongated and continuous doctor blade510is generally sufficiently flexible to be wound along a blade path from a supply source550, through intermediate features of the doctoring apparatus500including features of the doctor blade handling system540, to a discharge end560. As seen inFIG. 3, the elongated, continuous doctor blade510positioned in the example blade path extends past the first and second axial ends524,526of the rotating cylinder520. By extending past the axial ends, the doctor blade510is assured of being in position for doctoring processes on any portion of the rotating cylinder520, including if the entire rotating cylinder520is the surface to be doctored530. Furthermore, flexibility of the doctor blade510allows the doctor blade510to be compactly stored in the supply source550. For example, the doctor blade can be coiled onto a blade cartridge or can be serpentinely layered in a container for unconstrained removal and feeding to the doctor blade handling system540.

A collection device can be positioned at the discharge end560to collect the doctor blade510, or portions of the doctor blade510, as they are cut and discharged. InFIG. 3, the collection device is illustrated as a box562, but any container can be used as long as it is capable of being suitably positioned and has a suitably size and capacity to hold the cut off ends of the doctor blade510that are formed at the discharge end560of the doctor blade handling system540.

An exemplary doctor blade handling system540will now be described further in connection withFIGS. 3, 4A-B and5A-B. Exemplary embodiments of the doctor blade handling system540comprise means for mounting570a supply source for an elongated, continuous doctor blade510, a blade holder580including a blade back582and a blade seat584for releasably holding a portion of the doctor blade510; a pneumatic blade advancing device700including an idler roller710and a powered roller720, and an oscillation system630operably connected to the blade holder580. Within the pull through doctor blade handling system540, the blade path runs from proximate the means for mounting570the supply source, through the blade holder580, and to pneumatic blade advancing device700. An optional pneumatic multi-position cylinder unit100including a blade clamp110and a cutter blade120(as described in connection with the embodiment shown and described in connection withFIGS. 1A-Band2) can be included in the doctor blade handling system540and in the blade path, in particular after the pneumatic blade advancing device700and towards or as part of the discharge end560of the blade path.

Means for mounting570a supply source for the doctor blade510can be any suitable means570on which a supply source550can rest and which facilitates the supply of the doctor blade510to the doctor blade handling system540. For example, for supply sources that have wound doctor blades, means for mounting can be a spindle or other rotatable device and can include a mating feature at a distal end to facilitate attachment of the supply source, rotation of the supply source, and the transfer of any rotational motion to the supply source. In another example, for supply sources that have layered or serpentine storage of doctor blades, means for mounting can be a surface for a container and a moving arm to guide the doctor blade being pulled from the supply source by the doctor blade handling system and to minimize tangling. In a specific example, the supply source is in the form a rotatable reel doctor blade cartridge attached to a means for mounting the supply source in the form of a rotatable spindle attached to a motor for powered rotation and tensioning. Attachment can be by mating correspondingly shaped male and female features or threaded features on the distal tip of the spindle and in the cartridge.

As seen inFIGS. 3 and 4A and 4B, blade holder580extends longitudinally in a common direction with the blade path as it traverses the rotating cylinder520in a desired orientation for doctoring. It will be understood that the rotating cylinder depicted inFIGS. 3 and 4A-B can be replaced by other surfaces to be doctored, such as a surface on a shifting belt. In the illustrated example, the blade holder580is oriented, relative to the rotating cylinder520, in the axial direction from the first axial end524to the second axial end526. The blade holder580has a blade back582in a first portion and a blade seat584in a second portion. The blade seat584releasably holds a portion of the doctor blade510, e.g., an intermediate portion512of the doctor blade510, with a suitable orientation with respect to the surface being doctored530to apply or manipulate the coating or other material in the doctoring process.

In an exemplary embodiment and observable in cross-sectional view inFIGS. 4A and 4B, the blade seat584can incorporate a slit590with opposing surfaces592,594. The intermediate portion512of the doctor blade510can be held in the blade seat584in a friction fit. The friction fit between the doctor blade510and the blade seat584is releasable. In one embodiment, a biasing system is incorporated into the doctor blade handling system. The biasing system can, for example, generate a reversible or removable rotational force (indicated by arrow R) on the blade holder580relative to its longitudinal axis.

Any mechanical or electrical apparatus internal or external to the blade holder580can be used in the biasing system to control the rotational position of the blade holder and can contribute to establishing the removable rotational force. As an example of a structure suitable for use in the biasing system, the rotational force can be associated with a spring incorporated into the interior of the blade holder or attached externally to the blade holder. When mounting the blade holder on its mounting axis, the spring can be attached such that threading the doctor blade into the blade seat requires rotation of the blade holder and tensioning of the spring. At least a portion of this tension remains present when the edge of the intermediate portion of the doctor blade is in contact with the surface being doctored.

In exemplary embodiments, the biasing system is capable of both applying and removing the bias urging the working edge514of the doctor blade510to the surface being doctored530. Alternatively, separate systems can be utilized to provide biasing/unbiasing functions to the doctoring apparatus500.

However established, a force originating with the contact of the working edge514of the doctor blade510to the surface being doctored530skews the doctor blade510in the slit590. The skewed doctor blade510contacts a first of the opposing surfaces at a base596of the slit590and contacts a second of the opposing surfaces at a mouth598of the slit590. In conjunction with the force-exerting contact between the working edge514of the doctor blade510to the surface being doctored530, the two contact points P1,P2establish a friction fit between the doctor blade510and the blade seat584.

The friction fit is sufficient to prevent translational movement of the doctor blade510in the blade seat584. As a result, when the friction fit is present, the doctor blade510will move in connection with any translational movement of the blade holder580. When the force originating with the contact of the working edge514of the doctor blade510to the surface being doctored530is sufficiently reduced or removed, then the friction fit is reduced or removed and the doctor blade510and blade holder580can move independently. For example, relative to the blade path, the blade holder580reciprocates between a first position and a second position (an example of such first and second positions have been shown and described in connection withFIGS. 1A and 1B; inFIG. 3, the blade holder is in a first position) in the direction indicated by arrow M. An oscillation system630operably connected to the blade holder580causes the reciprocating translation motion. With the biasing system in operation to produce a friction fit, when moving the blade holder580from the first position to the second position (which corresponds with advancing the doctor blade510along the blade path) the doctor blade510will correspondingly move with the blade holder580. With the biasing system operating to reduce or remove the friction fit, when moving the blade holder580from the second position to the first position the doctor blade510can slide in the seat590while the blade holder580moves. If the doctor blade510is restrained from moving during the return reciprocation of the blade holder580, then the doctor blade510moves relative to the blade holder580and repetition of this step-wise movement indexes the doctor blade510to advance along the blade path. The indexing is periodic and based on the frequency the blade holder580reciprocates between the first position and the second position.

In summary, in an indexing mode the sequence of operations to index the doctor blade includes: (i) biasing the blade holder to be in force-exerting contact with a surface to be doctored, wherein the force imparted to the doctor blade frictionally engages the doctor blade with a seat of the blade holder, (ii) translating the blade holder in a first direction from a first position to a second position to pay out the elongated, continuous doctor blade from a supply source and to advance the doctor blade along the blade path, (iii) clamping the elongated, continuous doctor blade in a clamp of a device, (iv) removing or lessening the biasing on the doctor blade to reduce or remove the friction fit between the doctor blade and the blade holder, (v) translating the blade holder in a second direction to slidably move the doctor blade in the seat of the blade holder as the blade holder moves from the second position toward the first position. The biasing is then reapplied and the sequence repeated in step-wise movement to index the doctor blade to advance along the blade path.

In addition to the indexing mode described above, the doctor blade handling system inFIG. 3can operate in a speed mode. In the speed mode, the doctor blade510is advanced along the blade path by operation of the pneumatic blade advancing device700and without the translational movement of the blade holder580. Advancing of the doctor blade510occurs when the bias on the doctor blade510has been removed or sufficiently reduced to remove or sufficiently reduce the friction fit of the doctor blade510doctor blade510in the blade seat584to allow relative motion between the doctor blade510and the blade holder580in the direction of the blade path. Once the friction fit is removed or sufficiently reduced, the pneumatic blade advancing device700operates to advance (relative to at least one of, if not both, the blade holder580and the surface to be doctored530) the doctor blade510a desired length, which is typically at least equal to or greater than an axial length of the surface being doctored530(an example of a typical length is about 2 meter). The pneumatic blade advancing device700operates to advance the doctor blade510by, for example, rotating a powered roller that is in contact with the doctor blade with sufficient force to overcome any residual force in the friction fit between the doctor blade510and the blade seat584and translates the doctor blade510as the powered roller rotates for a desired time at a desired speed or for a desired number of rotations (additional description of the structure and operation of the pneumatic blade advancing device700is set forth in further detail below in connection with the description ofFIGS. 5A and 5B). Once the doctor blade510is advanced as necessary or desired, the friction fit between the doctor blade510and the blade seat584is restored by reapplying a bias to the doctor blade510and doctoring operations can resume.

An example of the sequence of operations to advance the doctor blade510in the speed mode includes: (i) stopping the feeding of product on the rotating cylinder520(or the like), (ii) stopping the reciprocation of the blade holder580, (iii) removing or lessening the biasing on the doctor blade510to reduce or remove the friction fit between the doctor blade510and the blade seat584, (iv) placing the blade clamp810and the blade cutter820(when present) in an open position, (v) placing the pneumatic blade advancing device700in a closed position, (vi) activating the powered roller720of the pneumatic blade advancing device700to move the doctor blade510though the blade seat584of the blade holder580a length sufficient to position a new portion of doctor blade510to be in contact with the surface to be doctored530, (vii) placing the blade clamp810and the blade cutter820(when present) in a closed position to one or more clamp, cut and discharge the doctor blade510into the collection device, and (viii) placing the pneumatic blade advancing device700in an open position, and (when present) placing the blade clamp810and the blade cutter820in an open position, (ix) biasing the doctor blade to establish a sufficient friction fit between the doctor blade510and the blade seat584to stationarily position the doctor blade510in the blade seat584, (x) activating the reciprocation of the blade holder580, and (xi) feeding product on the rotating cylinder520(or the like). Both before and after the speed mode, the doctor blade handling system can operate in the indexing mode to doctor material on the surface to be doctored530while replacing worn doctor blade510by intermittent indexed feeding with the oscillation system630.

The speed mode can advance any length of doctor blade510by increasing the length of time the pneumatic blade advancing device700is operated while the doctor blade510is unbiased or has sufficiently reduced bias. Also an alternative speed mode can combine translational movement of the blade holder580with the above speed mode. However, less time is needed to advance the doctor blade510in the speed mode than in the alternative speed mode. Also, there may be instances, such as a damaged doctor blade, where the doctor blade needs to be advanced a length that is greater than the indexing length before a suitable doctor blade is in place for doctoring operations, in which case the added translational movement may not be suitable or may not add to the efficient operation of the doctor blade handling system.

Returning to the translational movement of the blade holder580, in the first position the blade holder580is operably proximate a portion of a surface to be coated530with the blade holder580positioned axially between the first and second axial ends524,526of the rotating cylinder520. In the second position, the blade holder580has moved downstream (relative to the direction of motion of the blade path from supply source550to discharge end560). In the exemplary embodiment inFIG. 3, when the blade holder580moves in the downstream direction, the second position of the blade holder580is closer to the discharge end560than is the first position. Alternatively, in the second position the blade holder580is proximate the circumferential surface of the rotating cylinder520with at least a portion of the blade holder580positioned axially outside one of the first and second axial ends524,526of the rotating cylinder520.

Returning to the oscillation system630, in the exemplary embodiment ofFIG. 3the oscillation system630includes an electric drive system with an electric gear motor632provided with a crank throw634and a connecting rod636. This connecting rod636is directly connected to the blade holder580. Similar to the embodiment shown inFIGS. 1A and 1B, when electric gear motor532inFIG. 3operates, the crank throw634rotates and the connecting rod636reciprocates, causing reciprocating motion in the connected blade holder580and its associated features.

An exemplary embodiment of a pneumatic blade advancing device700is illustrated inFIGS. 5A and 5B. The pneumatic blade advancing device700includes an idler roller710and a powered roller720. The relative motion translating (T) the idler roller710toward the powered roller720can be pneumatically actuated between a closed position and an open position.FIG. 5Aillustrates the pneumatic blade advancing device700in a closed position. In the closed position, a surface712of the idler roller710and a surface722of the powered roller720contact surfaces of the doctor blade510and exert a pressure to the doctor blade510. While in the closed position, the exerted pressure is sufficient to hold the doctor blade510substantially stationary, alternatively stationary, relative to an imaginary line extending between the axis of rotation714of the idler roller710and the axis of rotation724of the powered roller720. Further, in the closed position there is sufficient friction between the surface722of the powered roller720and a surface of the doctor blade510so that, when the powered roller720rotates (r), the unbiased doctor blade510can be drawn longitudinally through the blade seat584and the doctor blade510advanced along the blade path. Typically, the friction between the surface722of the powered roller720and a surface of the doctor blade510is not sufficient to longitudinally draw the biased doctor blade510through the blade seat584when the powered roller720rotates (r).

FIG. 5Billustrates the pneumatic blade advancing device700in an open position. In the open position, the surface of at least one of the idle roller710and the powered roller720is spaced apart from the surfaces of the doctor blade510. While in the open position, rotation (r) of the powered roller720, by itself, is generally not sufficient to longitudinally draw the biased doctor blade through the blade seat584.

Positioning and relative translation of at least one of the idle roller710and the powered roller720of the pneumatic blade advancing device700are made by a pneumatic circuit730that includes pneumatic valve732that supplies pneumatic fluid alternately to different sides of a pneumatic cylinder operably connected to at least one of the idle roller710and the powered roller720.

A pneumatic multi-position cylinder unit with a blade clamp and a blade cutter can optionally, but is not required to be, included in the doctoring apparatus500shown and descried in connection with the embodiment inFIG. 3. When a pneumatic multi-position cylinder unit is not present, the doctor blade510that advances down the blade path past the pneumatic blade advancing device700can be collected in a collection device positioned at the discharge end560. The collection device illustrated inFIG. 3is a box562, but can be any container as long as it is capable of being suitably positioned and has a suitably size and capacity to hold the doctor blade510that indexingly advances from the discharge end560of the doctor blade handling system540.

If included, a pneumatic multi-position cylinder unit with a blade clamp and a blade cutter can be the same as or similar to that shown and descried in connection with the embodiment inFIGS. 1A-Band2. Alternatively, the pneumatic multi-position cylinder unit can be the same as or similar to that shown inFIGS. 6, 7A-B,8A-B, and9A-B.FIG. 6is a perspective view of an exemplary embodiment of a pneumatic multi-position cylinder unit800with a blade clamp and blade cutter system to clamp and cut a doctor blade510;FIGS. 7A-B,8A-B, and9A-B shows details of an embodiment of a pneumatic multi-position cylinder unit800with a blade clamp810and a blade cutter820in cut-away, side views in different operating positions in the operating sequence.

FIGS. 7A-Bshow the pneumatic multi-position cylinder unit800with both the blade cutter820retracted from the cutting zone642and the blade holder810retracted away from the doctor blade510. Here, the pneumatic piston head830for the blade clamp810and the pneumatic piston head840for the blade cutter820are both in the unactuated position. In the unactuated position in this embodiment, both the pneumatic piston head830for the blade clamp810and the pneumatic piston head840for the blade cutter820are positioned, relative to the respective cavity in which the piston head translates, at a position that is furthest from the side of the cavity that includes a channel for a piston rod of the piston head. With respect to the blade clamp810, the retracted position removes a positional force from a biasing device, such as the spring850, so that the blade clamp810is spaced from the doctor blade510to form a gap (G). The gap (G) exists between the blade holder810and the surface of the doctor blade510. Typical sizes for the gap (G) are 0.25 mm to 2.0 mm, alternatively 0.5 mm to 2.0 mm or 0.5 mm to 1.5 mm. In this position, the pneumatic multi-position cylinder unit800does not interfere with movement through the gap (G) of the doctor blade510by the doctor blade handling system540as the doctor blade510is advanced along the blade path. With respect to the blade cutter820, the retracted position positions the blade cutter spaced apart from doctor blade510in area of the cutting zone642. The blade cutter820is positioned in the spaced apart spatial relationship by suitable means, such as by being mechanically connected to the retracted pneumatic piston head840for the blade cutter820or by a biasing device, such as a spring, that urges the blade cutter to the spaced apart position.

FIGS. 8A-Bshow the pneumatic multi-position cylinder unit800with the blade holder810engaged against the doctor blade510. Here, the pneumatic piston head830for the blade clamp810is in a fully actuated position in that the piston head is positioned, relative to the respective cavity in which the piston head translates, at a position that is closest from the side of the cavity that includes a channel for a piston rod of the piston head. In this position, i.e., the clamp actuated position, a positional force is applied to the biasing device, such as the spring850, so that the blade clamp810is urged toward the doctor blade510to eliminate the gap (G). Contact between the blade clamp810and the surface of the doctor blade interferes with movement of the doctor blade510by the doctor blade handling system540as the doctor blade510is advanced along the blade path. Also, the blade cutter820is partially advanced in the cutting zone642(relative to the retracted position inFIGS. 7A-B) and is spaced apart from the doctor blade510by a gap (g). Here, the pneumatic piston head840for the blade cutter820is in an intermediate position (relative to the translational limits of the piston head within the respective cavity) that is neither a fully actuated position nor a fully unactuated position. However, this intermediate position is sufficiently moved from the unactuated position (as inFIGS. 7A-B) that the cutter blade has moved in the cutting zone642some of the distance towards contact with the doctor blade510.

FIGS. 9A-Bshow the pneumatic multi-position cylinder unit800with the blade holder810engaged against the doctor blade510and with the blade cutter820in an actuated position. Here, the pneumatic piston head830for the blade clamp810has not moved from the position associated withFIGS. 8A-B, i.e., is still in the clamp actuated position, but the pneumatic piston head840for the blade cutter820has continued moving (relative to the cavity) from the intermediate position to an actuated position to advance the cutting blade820in the cutting zone642(relative to retracted position when unactuated as inFIGS. 7A-B) through the blade path such that the blade cutter820has cut the portion640of the doctor blade510that extends past the cutting zone642. Also in the illustrated position, the pneumatic multi-position cylinder unit800still interferes with movement of the doctor blade510by the doctor blade handling system540as the doctor blade510is advanced along the blade path because the blade holder810is still engaged against the doctor blade510.

The arrangement to operate the blade clamp810and the blade cutter820, for example the arrangement of pneumatic valves and lines, are not shown inFIGS. 7A-B,8A-B and9A-B, but an arrangement similar to that shown and described in connection withFIGS. 1A and 2can be used or adapted by one of ordinary skill in the art to function with the arrangement inFIGS. 6, 7A-B,8A-B and9A-B.

Exemplary embodiments of a pull through doctor blade handling system540also include a sensor900proximate the blade holder580and a control unit1000operably connected to the oscillation system630, a pneumatic blade advancing device700, a pneumatic multi-position cylinder unit800(if present), and the sensor900. An example of a sensor900is an inductive switch. In exemplary embodiments, the sensor900discriminates between the blade holder580located in the first position and the blade holder580not in the first position or, for example, located in the second position.

The pneumatic blade advancing device700and the blade clamp810(if present) are opened and closed in timed sequence with reciprocation of the blade holder580to achieve longitudinal shifting of the doctor blade510in a selected direction across the doctored surface, from supply source550to discharge end560. Additionally, the blade clamp810and blade cutter820(if present) can be used to provide a further clamping of the doctor blade510and to cut the worn doctor blade. The blade cutter820can also be used to drive any cut-off portion640of the doctor blade into the collection device562.

The control unit1000coordinates the operation and sequence of the oscillation system630, the blade holder580, a pneumatic blade advancing device700, and a pneumatic multi-position cylinder unit800(if present) based on position information communicated from the sensor900. The operations and sequence include one or more of:

(i) biasing the blade holder580to place a portion of the doctor blade510in force-exerting contact with a surface to be doctored530,

(ii) translating (M) the blade holder580in a first direction from a first position to a second position,

(iii) operating the pneumatic blade advancing device700to clamp the elongated, continuous doctor blade510in a stationary position relative to the blade path,

(iv) unbiasing the blade holder580to reduce or remove the force-exerting contact between the doctor blade510and the surface to be doctored530, and

(v) operating the pneumatic blade advancing device700to advance the elongated, continuous doctor blade510relative to a fixed point along the blade path

(vi) translating (M) the blade holder580from the second position to the first position.

Several functions of the doctoring apparatus are enabled by the operations and sequencing coordinated and controlled by the control unit1000. For example, biasing the blade holder to be in force-exerting contact with a surface to be doctored imparts a force to the doctor blade that frictionally engages the doctor blade with a seat of the blade holder. An example of this is shown and described in connections withFIGS. 4A and 4B. Also, translating (M) the blade holder580in a first direction from a first position to a second position pays out the elongated, continuous doctor blade510from a supply source550and to advance a portion of the doctor blade510into a clamping zone of a pneumatic blade advancing device700. Operation of the pneumatic blade advancing device700clamp the elongated, continuous doctor blade510in a stationary position relative to the blade path, an example of which is a stationary position relative to an imaginary line extending between the axis of rotation714of the idler roller710and the axis of rotation724of the powered roller720. In addition, translating (M) the blade holder580in a second direction slidably moves the doctor blade510relative to the seat584of the blade holder580as the blade holder580moves from the second position toward the first position. In this way, the doctor blade510is longitudinal shifted in a selected direction across the surface to be doctored530.

In addition to the above operations and sequences (i) to (v), after the doctor blade510is unbiased and before the doctor blade510is rebiased and with the pneumatic blade advancing device700in the actuated to clamp position, the powered roller720can be rotated to move the doctor blade510along the blade path by a length that is greater than just the oscillation distance of the blade holder580between the first position and the second position. For example, the powered roller720can be rotated in direction of rotation (r) a plurality of full or partial revolutions and, because the doctor blade is unbiased and can be drawn through the blade seat584, the doctor blade510will advance along the blade correspondingly to the rotation of the powered roller720. The sequencing of this operation in the overall operation of the doctoring apparatus and the timing and amount of rotation of the powered roller720is controlled and coordinated by the control unit1000. In this manner, any length of doctor blade510can be programmed to be the indexing length when the doctor blade is advanced along the blade path and not just lengths associated with the oscillation distance between the first position and the second position. Preferably the indexing length is a length that represents the axial length of the surface to be doctored530or the axial length of the rotating cylinder520or is minimally one of these lengths.

In addition to the above operations and sequences, the control unit1000can optionally coordinate (when present) the operations and sequences of the pneumatic multi-position cylinder unit800to include:(a) moving the blade clamp110to the clamping position,(b) cycling the blade cutter120between the open position and the cutting position,(c) moving the blade clamp110to the open position.
The operations and sequences (a) to (c) of the pneumatic multi-position cylinder unit800can occur at any point in the operation and the sequence that is after the blade holder580is translated (M) in a first direction from a first position to a second position.

In a more detailed description of the operation (i) to (v) of the embodiment inFIG. 3, the blade holder580is biased against the surface to be doctored530and the doctor blade is friction fit in the blade seat584. The blade holder shifts from the first position to the second position (the second position downstream in a direction of the blade path from the first position) and sensor900communicates positional information of the blade holder580to the control unit1000, which is connected to the control valving of the pneumatic blade advancing device700, e.g., pneumatic circuit730, and is optionally connected (if present) to the solenoid of the pneumatic valves202,204of the pneumatic multi-position cylinder unit800. In the illustrated configuration inFIGS. 3 and 5A-B, first idler roller710is translated then powered roller720is operated. As a consequence of this sequencing, the clamping of the blade is first achieved, before the pneumatic blade advancing device700is actuated. Typically, actuation of the pneumatic blade advancing device700cycles from an unclamped position to a clamped position and, at a later time, a reverse actuation of the pneumatic blade advancing device700returns the idler roller710and powered roller720to the unclamped position. While still clamped, the doctor blade510is unbiased and then the blade holder580is shifted in the opposite direction and back to the first position. Because the doctor blade510is prevented from moving by the still actuated to clamp pneumatic blade advancing device700(with or without the assistance of rotation (r) of the powered roller720), the shifting of the blade holder causes the doctor blade510move in the blade seat584relative to the blade holder580. Additionally, the powered roller720can be rotated additional revolutions to draw additional length of doctor blade510from the supply source550into and/or past the blade holder580or to advance the doctor blade510an additional distance along the blade path. Once returned to the first position, the sensor900updates the control unit1000, which operates the pneumatic blade advancing device700in a reverse actuation that returns the idler roller710and power roller720to the unclamped position. When the next stroke of the oscillation system630occurs, the blade path is again open and the blade holder580will move again to the second position while the doctor blade510is biased against the surface to be doctored530and the doctor blade510that is friction fit in the blade seat584will be pulled forward on the blade path by the forward movement of the blade holder580. In this way, the doctor blade510is incrementally shifted longitudinally across the cylinder520from a supply source550to a discharge end560.

During doctoring operation, the blade holder580is oscillated by the oscillation system, and the idler roller710and powered roller720(and the optional blade clamp810and blade cutter820, if present) are employed in timed sequence with this oscillation to shift the doctor blade510longitudinally and in an indexed-like fashion across the surface of the cylinder520, with doctor blade510being gradually pulled from supply source550and cut-off by blade cutter820and collected in collection device, such as box562. The handling system allows for the continuous or nearly continuous supply and disposal of the doctor blade.

When a first doctor blade510has been passed through the doctor blade handing system540and the trailing end of the doctor blade leaves the supply source550, that supply source550is replaced by a new one containing a second doctor blade510. This having been accomplished, the doctoring operation is momentarily interrupted, the idler roller710and powered roller720(and the optional blade clamp810and blade cutter820, if present) are set to an open position and the leading end of the second doctor blade510is then advanced by the operator along the blade path through the idler roller710and powered roller720(and the blade clamp810and blade cutter820, if present). The second doctor blade510is also attached to the blade holder580. Then the doctoring operation is continued and, when full, the collection device containing the cut pieces of doctor blade is replaced by an empty one.

Additional information and description of the operation of optional pneumatic multi-position cylinder unit800according to (a) to (c) and its coordination by control unit1000is similar to that described in connection with the operation of the embodiment inFIGS. 1A and 1B.