Patent Application
20180105989
The present application relates to the general field of paper, film and foil coating manufacturing and converting. It relates in particular to metering rod holder assemblies used in the coating of papers, films and foils during various coating processes.
During the coating process, a coating or metering rod holder assembly lays against a high speed transfer roller. A generous chemical coating is applied to the transfer roller. Excess coating is removed by the metering rod holder assembly leaving only a thin film of chemical treatment or coating on the transfer roller. Then the coating is transferred to a web of material, such as paper, for example. In some instances, an excess amount of coating is applied directly to the web and then the excess is removed with the metering rod.
The metering rod holder assembly includes a body having a rod channel (rod holder) that is designed to receive a metering rod (sometimes referred to as a doctor blade). The metering rod is generally, but not always, small in diameter and can be very long in length (e.g., up to 15 meters). During the coating process, the metering rod primarily controls the coating film thickness. In addition, the rod is rotated within the rod channel to provide uniform wear along the circumference of the rod.
Both metering rods and rod holders are wear parts that have service lives, depending on the application, anywhere from a few hours to a few months. The part of the rod holder that typically wears out is called a cradle and includes the rod channel in which the metering rod rotates. As the metering rod rotates, friction between the metering rod and the cradle, combined with sometimes abrasive coatings and other factors, causes the “lips” of the rod holder cradle to wear down.
In some instances, the cradle is included in an insert that is received in the body of the rod assembly. Such inserts allow replacing the cradle without having to replace the entire body resulting in a cost savings to the customer. Known metering rod assemblies utilizing an insert have generally required replacement of a conventional body with a body designed to accommodate an insert. A body configured to accommodate an insert generally will include one or more features designed to enable clamping the insert in the body to reduce or eliminate vibration and/or unintended separation of the insert from the body. For example, pneumatic clamping tubes are often supported by the body and used for securing an insert in a channel or groove of the body. Such clamping tubes can be pressurized to achieve a variable clamping effect on a metering rod.
While metering rod assemblies utilizing inserts and clamping pressure tubes have met with commercial success, the addition of clamping pressure tubes to the metering rod assemblies complicates the device, increases cost, and can result in an increased risk of operator errors or equipment failure. In addition, upgrading a metering rod holder assembly to accommodate an insert with the variable clamping features described above typically requires replacing the body of the assembly with a body equipped with a clamping pressure tube, and plumbing pneumatic lines to the body to inflate the pressure tube, and a control unit. This increases costs and complexity of metering rod assemblies.
The present disclosure sets forth a metering rod holder assembly including a body for accommodating a metering rod insert and configured to clamp the metering rod and/or metering rod insert without the use of an auxiliary clamping device, such as a pressure tube or the like.
In accordance with one aspect, a metering rod holder assembly for supporting an associated metering rod in compressive engagement with an associated surface from which a fluid is to be metered comprises a base member having a channel opening to a first face thereof and having a base wall and first and second side walls spaced about a central plane of the channel, at least one of the side walls having a flank surface extending at a non-zero angle relative to the central plane, and a rod bed insert at least partially received in the channel of the base member in spaced relation to the base wall of the channel, the rod bed insert having a metering rod slot for receiving the associated metering rod, and further including a flank engaging surface thereof engaged with the at least one flank surface, the rod bed insert movable from a first position to a second position within the channel, wherein the rod bed insert is closer to the base wall of the channel when in the second position than when in the first position.
At least one of the first and second side walls of the channel, or a portion thereof, can extend at a non-zero angle relative to the central plane of the channel in a taper fit manner, whereby as the metering rod urges the rod bed insert deeper into the channel the first and second side walls of the base member clamp the rod bed insert in the channel. The rod bed insert can be configured to be closely received in the channel, the first and second side walls of the insert having a mating shape to the first and second side walls of the channel. At least one of the flank surface of the base member or the flank engaging surface of the rod bed insert can include a relieved flank region. The rod bed insert can be spaced apart from the flank surface of the base member at the relieved flank region. A plurality of relieved flank regions can be spaced along a length of the metering rod holder assembly, including opposite end portions of the metering rod holder assembly. The assembly can further comprise a pressure hose disposed in the channel between the base wall and the rod bed insert for urging the rod bed insert outwardly from the channel. The rod bed insert can include at least one retaining element adapted to cooperate with a corresponding retaining element of the base member to restrict separation of the metering rod insert from the base member in both the first position and the second position. The retaining elements can include at least one protrusion and at least one recess into which the protrusion is received. At least one of the base member or the rod bed insert can be comprised of a resilient material. The flank engaging surface can be a portion of a jaw extending from a main body portion of the rod bed insert, the rod bed insert including a longitudinally extending slot between the main body portion and the jaw for allowing the jaw to flex as the rod bed insert is urged into the channel.
In accordance with another aspect, a rod bed insert is adapted to move relative to an associated base member to provide a consistent radial clamping pressure on and associated metering rod as the rod bed insert wears during use, the rod bed insert configured to be received in a channel of the associated base member, wherein the rod bed insert has a metering rod slot for receiving the associated metering rod, and includes a flank engaging surface for engaging a corresponding flank surface of the associated base member, the rod bed insert movable from a first position to a second position within the channel, wherein the rod bed insert is closer to the base wall of the channel when in the second position than when in the first position.
The flank engaging surface can include a relieved flank region. The rod bed insert can be spaced apart from the flank surface of the associated base member at the relieved flank region. The insert can further comprise a plurality of relieved flank regions spaced along a length of the flank engaging including at opposite end portions of the rod bed insert.
In accordance with another aspect, a base member of a metering rod holder assembly comprises a channel opening to a first face thereof for receiving an associated rod bed insert, the channel having a base wall and first and second side walls spaced about a central plane of the channel, at least one of the side walls having a flank surface extending at a non-zero angle relative to the central plane, wherein the associated rod bed insert can be at least partially received in the channel of the base member in spaced relation to the base wall of the channel.
At least one of the first and second side walls of the channel can extend at a non-zero angle relative to the central plane of the channel in a taper fit manner. The flank surface of the base member can include a relieved flank region. The associated rod bed insert can be spaced apart from the flank surface of the base member at the relieved flank region when received in the channel. The flank surface can include a plurality of relieved flank regions spaced apart along a length of the base member, including at opposite end portions of the base member.
The following is a brief description of the drawings, which are presented for the purpose of illustrating the exemplary embodiments disclosed herein and not for the purpose of limiting the same.
With reference to
With additional reference to
A rod bed insert 46 is received in the channel 34 and includes a metering rod slot 50 in which a metering rod 54 is supported. The rod bed insert 46 is configured to be closely received within the channel 34, with first and second sidewalls 56a and 56b of the insert 46 have a mating shape and slope to the first and second side walls 40A and 40B of the channel 34. The rod bed insert 46 includes a narrow or necked-down portion 57 connecting the first and second sidewalls 56a and 56b allowing the insert 46 to flex about the necked-down portion 57 to accommodate insertion and/or removal of the metering rod 54 from the metering rod slot 50.
The rod bed insert 46 includes a pair of tab portions 58a and 58b that serve as retaining elements when the rod bed insert 46 is inserted in the channel 34. As best seen in
Returning to
To this end, it will be appreciated that when force is applied to a rear surface 64 of the base member 30, the force is transmitted through the base member 30 and rod bed insert 46 to the metering rod 54. A reactive force is applied to the metering rod 54 by the roller 14 which tends to force the metering rod 54 deeper into the rod bed insert 46. The net effect is that surfaces 40a and 40b are urged towards each other thereby clamping the rod bed insert 46 and/or metering rod 54 in the channel 34 of the base member 30. As the force urges the insert 46 deeper into the channel 34, the interaction of the sloping surfaces 56a and 56b with sloping surfaces 40a and 40b urges the sides of the insert 46 together gripping the rod more tightly.
It will be appreciated that, for a given pressure applied to the base member 30 by the pressure tube 60, the clamping force can be altered by changing the angle of surfaces 40a and 40b relative to the plane A-A. For example, a relatively shallow angle, such as 20 degrees, will produce more clamping force on the rod bed insert 46 than a relatively steeper angle, such as 40 degrees. Accordingly, depending on the specific application, the clamping effect can be tuned to achieve desired performance. For example, an application requiring light pressure on the metering rod may benefit from a relative steep angle of side walls 40a and 40b (greater clamping force at lower pressure on the metering rod), while an application requiring higher pressure on the metering rod may benefit from a more shallow angle (less clamping force at higher pressure on the metering rod).
Turning to
In this embodiment, the hinge portion 88 facilitates flexing of the head portion 86 relative to the mounting portion 84 when a force is applied to the head portion 86, such as by a pressure tube (e.g., pressure tube 60 of
As with the embodiment of
Turning now to
For example,
With additional reference to
The rod bed insert 150 is received in the channel 134 and includes a metering rod slot 152 in which the metering rod 154 is configured to be supported. The rod bed insert 150 is configured to be closely received within the channel 134, with first and second sidewalls 156a and 156b of the insert 150 have a mating shape/configuration as the first and second side walls 140a and 140b of the channel 134. To this end, the first and second sidewalls 156a and 156b of the insert 150 each have a lower portion LP for abutting the inner portion IP of a respective sidewall 140a/140b of the channel 134, and a beveled flank engaging surface 160a/160b for engaging the beveled flanks 144a/144b of the sidewalls 140a and 140b of the channel 134.
The beveled flank engaging surfaces 160a/160b are surfaces of respective upper and lower jaws 162a and 162b that together at least partially define the rod slot 152. The jaws 162a/162b extend from a main body portion 166 of the rod bed insert 150. Longitudinally extending slots 170a and 170b define respective necked-down portions 172a and 172b between the main body portion 166 and the upper and lower jaws 162a and 162b. The necked-down portions 172a and 172b allow the jaws 162a and 162b to flex as the rod bed insert 150 is urged into the channel 134, as will be described in more detail below.
It should be appreciated that the magnitude of the flank angle, at least in part, generally has an inverse relationship between a force applied to the rod 154 by the loading hose 116/contact with an applicator roll 114 or other surface, and the amount of radial force applied to the metering rod 154 by the jaws 162a/162b of the rod bed insert 150. The lesser the flank angle, the greater the radial clamping force applied to the metering rod for a given constant application of force by the loading hose 116. Accordingly, the beveled flanks 144a/144b cooperate with the rod bed insert 150 to allow for a self-adjustment mechanism that generally adjusts the radial force applied to the metering rod 154 by the jaws 162a and 162b of the rod bed insert 150 as the rod bed insert 150 wears and seats further into channel 134, thus reducing or eliminating the need to provide other adjustment mechanisms and/or prolonging the useful life of the rod bed insert 150 by maintaining a desired radial force on the metering rod 154 as the rod bed insert 150 wears during normal use.
In some examples, the flank angle is between 100 and 220 degrees, more particularly between about 150 degrees and 170 degrees.
In the illustrated embodiment, as the material (e.g., polymer) of the rod bed insert 150 wears out, the rod bed insert 150 will naturally seat further into the base member 130 as loading tube 116 applies constant pressure thereby maintaining a constant and/or more consistent clamping force on the metering rod 154 and enhancing performance.
It should further be appreciated that the longitudinally extending slots 170a and 170b (e.g., flank relief cuts) can also be varied in size, depth, shape and/or location relative to the jaws 162a and 162b to customize the radial clamping force and/or relationship between the pressure applied by loading tube 116 and the clamping force, for certain applications.
The exemplary metering rod holder assembly 110 is designed such that the replaceable rod bed insert 150 can be snapped into the base member 130 from the top (e.g., inserted into the channel 134 in the vertical direction as shown in
The rod bed insert 150 includes a pair of tab portions 178a and 178b that serve as retaining elements when the rod bed insert 150 is inserted in the channel 134. As best seen in
With additional reference to
Turning now to
The rod bed insert 150 is usually made of a single piece of machined polyethylene or cast polyurethane and is considered a consumable wear part. Using a two-piece assembly (e.g., base and rod bed insert) in accordance with the present disclosure allows for a smaller consumable portion of the metering rod holder assembly to reduce cost and waste.
Aspects of the present disclosure allow the rod bed insert 150 to be manufactured from certain flexible polymers that do not take a set (e.g., polyurethane). Accordingly, the rod bed inserts of the present disclosure can be coiled for shipping and uncoiled at a final destination by the end user. As compared to prior art rigid, straight rod bed inserts made of polyethylene that must be shipped in very long boxes (e.g., 40 feet), the rod bed inserts of the present disclosure offer significant saving from a shipping standpoint.
The exemplary embodiments have been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
The present application is a continuation-in-part of currently pending U.S. patent application Ser. No. 13/961,061, filed on Aug. 7, 2013, which claims priority to U.S. Provisional Patent Application Ser. No. 61/681,397, filed on Aug. 9, 2012, the entire contents of both applications being incorporated herein by reference. The present application also claims priority to U.S. Provisional Patent Application Ser. No. 62/509,341, filed on May 22, 2017, the entire contents being incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61681397 | Aug 2012 | US | |
| 62509341 | May 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13961061 | Aug 2013 | US |
| Child | 15844969 | US |
