Patent Application
20090217794
Oriented strand board (OSB) is a wood product formed from layered wafers of wood oriented in a particular pattern. For example, conventional OSB includes top and bottom layers of wood wafers with the longitudinal axes of the wafers aligned substantially parallel to a longitudinal axis of the board. Conventional OSB also includes a central layer disposed between the top and bottom layers with the longitudinal axes of wafers aligned substantially perpendicular to the longitudinal axis of the board.
As part of the OSB manufacturing process, manufacturers utilize waferizing machinery, such as ring strander devices or disk flaker devices to shave logs, such as aspen, yellow pine, or white birch, into thin wafers in a procedure termed waferizing. Taking ring strander devices as an example, typical ring strander devices include a clamping portion and a drum having between twenty-four and forty-four cutting assemblies disposed within the drum. In use, the log clamping portion receives a set of logs and secures a portion of the logs within the ring strander device such that a longitudinal axis of each log is substantially parallel to the axis of rotation of the drum. As the drum rotates, the clamping portion holds the logs against the cutting assemblies of the drum thereby allowing the cutting assemblies to shave the logs into wafers.
Ring strander devices can utilize different types of cutting assemblies to form the wood wafers. For example, one type of cutting assembly or knife pack, as manufactured by Simonds International Corporation, is illustrated in
During operation, the cutting assemblies 10 of the ring strander devices become worn and, as a result, cannot effectively form the wood wafers. Accordingly, ring strander operators must change the cutting assemblies 10 multiple times per day. To change a cutting assembly 10, an operator unclamps and removes a worn cutting assembly 10 from the ring strander device. The operator then inserts a replacement cutting assembly 10 into the ring strander and clamps the replacement into place. The procedure is repeated for all of the cutting assemblies 10 disposed within the ring strander device drum. The operator transfers the worn cutting assemblies to a grinding area for resharpening of the knife plates.
Conventional cutting assemblies, however, suffer from a variety of deficiencies. Typically, the three components of a cutting assembly are secured together using a series of fasteners. Accordingly, during a replacement procedure, each cutting assembly in its entirety must be removed from the ring strander device. However, each cutting assembly weighs about 25 pounds, thereby making replacement of the worn cutting assemblies a cumbersome process to the operator. Additionally, because the cutting assemblies are relatively heavy, the replacement process can be time intensive causing the ring strander device to be inoperative for several hours.
Alternates to conventional cutting assemblies have been utilized in the OSB manufacturing process. For example, certain manufacturers have utilized keyed chipper knives, as produced by Key Knife Inc. (Key Knife Inc., Portland Oreg.) and as shown in U.S. Pat. No. 5,819,826, to form wood wafers in the OSB manufacturing process. The keyed chipper knives are relatively lightweight and can be replaced in the ring strander device. However, the key chipper knives do not include counter knives or appropriate counter knife geometry. Accordingly, during the shaving process, the keyed chipper knives can generate oversized wood wafers (i.e., termed postcards) that are unusable in the manufacture of OSB. Additionally, the keyed chipper knives can generate a relatively large amount of waste wood particles or fines as a result of inefficient formation of the wood wafers, thereby minimizing the amount of usable wood wafers formed in the waferizing process.
By contrast to conventional cutting assemblies such as used in ring strander devices, embodiments of the present invention relate to a cutting assembly that includes a removable and replaceable knife blade. The cutting assembly includes a knife assembly having a knife holder and a knife blade, a counter knife, and a scoring tip holder. The counter knife is secured to a ring strander drum, the knife holder and scoring tip holder are carried by a ring strander clamping element, and knife blade is disposed between the counter knife and the knife holder. In a closed position, the ring strander clamping element causes the knife holder and the scoring tip holder to generate a compressive force against the knife blade and counter knife, thereby securing the knife blade within the cutting assembly. In an open position, the ring strander clamping element positions the knife holder and the scoring tip holder in a spaced relationship relative to the counter knife, thereby allowing removal of the knife blade from the cutting assembly. With such a configuration of the cutting assembly, as the knife blade becomes dull, an operator can easily replace the knife blade in the cutting assembly without having to remove the entire cutting assembly from the ring strander device. Accordingly, use of the cutting assembly can reduce the amount of time required to replace the cutting elements, thereby reducing ring strander device downtime while allowing a manufacturer to maintain a suitable geometry of wood wafers for OSB manufacture and minimize creation of dust or fines.
In one arrangement, a cutting assembly includes a knife assembly having a knife holder, and a knife blade supported by the knife holder. The cutting assembly includes a counter knife opposing a first portion of the knife assembly. The counter knife has a leading edge defining a set back distance with the knife blade of the knife assembly where the set back distance constructed and arranged to provide a travel path for a wafer. The cutting assembly includes a scoring tip holder opposing a second portion of the knife assembly where the scoring tip holder is constructed and arranged to carry at least one scoring tip blade. The counter knife and the scoring tip holder are positionable between a first position relative to the knife assembly to secure the knife blade relative to the cutting assembly and a second position relative to the knife assembly to release the knife blade from the cutting assembly.
In one arrangement, a cutting assembly includes a knife assembly having a knife holder and a knife blade supported by the knife holder. The cutting assembly includes a counter knife opposing a first portion of the knife assembly. The counter knife has a leading edge defining a set back distance with the knife blade of the knife assembly, the set back distance being constructed and arranged to provide a travel path for a wafer. The cutting assembly includes a scoring tip holder opposing a second portion of the knife assembly. The scoring tip holder is constructed and arranged to carry at least one scoring tip blade. The cutting assembly includes a first coupling mechanism constructed and arranged to couple the counter knife to a drum of a ring strander device and a second a coupling mechanism disposed between the knife holder of the knife assembly and the scoring tip holder, the second coupling mechanism constructed and arranged to couple the knife holder to the scoring tip holder. The counter knife and the scoring tip holder are positionable between a first position relative to the knife assembly to secure the knife blade relative to the cutting assembly and a second position relative to the knife assembly to release the knife blade from the cutting assembly.
In one arrangement, a method for replacing a knife blade of a cutting assembly includes releasing a clamping pressure generated between a clamp of a ring strander device and a ring strander drum of the ring strander device from the cutting assembly. The method also includes positioning the clamp to dispose a knife assembly of the ring strander cutting assembly in a spaced apart relation relative to a counter knife of the ring strander cutting assembly, the knife assembly having a knife holder and the knife blade carried by the clamp and the counter knife carried by the ring strander drum. The method further includes removing the knife blade from the knife holder carried by the clamp.
The foregoing and other objects, features and advantages will be apparent from the following description of particular embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of various embodiments of the invention.
Embodiments of the present invention relate to a cutting assembly that includes a removable and replaceable knife blade. The cutting assembly includes a knife assembly having a knife holder and a knife blade, a counter knife, and a scoring tip holder. The counter knife is secured to a ring strander drum, the knife holder and scoring tip holder are carried by a ring strander clamping element, and knife blade is disposed between the counter knife and the knife holder. In a closed position, the ring strander clamping element causes the knife holder and the scoring tip holder to generate a compressive force against the knife blade and counter knife, thereby securing the knife blade within the cutting assembly. In an open position, the ring strander clamping element positions the knife holder and the scoring tip holder in a spaced relationship relative to the counter knife, thereby allowing removal of the knife blade from the cutting assembly. With such a configuration of the cutting assembly, as the knife blade becomes dull, an operator can easily replace the knife blade in the cutting assembly without having to remove the entire cutting assembly from the ring strander device. Accordingly, use of the cutting assembly can reduce the amount of time required to replace the cutting elements, thereby reducing ring strander device downtime while allowing a manufacturer to maintain a suitable geometry of wood wafers for OSB manufacture and minimize creation of dust or fines.
Each cutting assembly 50 is configured to allow removal and replacement of a cutting element held by the cutting assembly 50 without requiring an operator to remove the entire cutting assembly from a ring strander device 40. Details of the components of the cutting assembly 50 are provided below.
The knife holder 54 defines a carrier portion 72 configured to carry the knife blade 56. In one arrangement, the carrier portion 72 extends along a length L of the knife holder is defined as a substantially L-shaped recess formed in the knife holder 54. For example, the carrier portion 72 includes a backing portion 74 and a base portion 76 which extend along the length L of the knife holder 54. The backing portion 74 and base portion 76 are configured to support a body portion of the knife blade 56 to minimize deflection or bending of the knife blade 56 during a cutting procedure. The carrier portion 72 is also configured to position a cutting edge 78 of the knife blade 56 relative to the cutting assembly 50 such that the cutting edge 78 extends beyond a distal edge 80 of the knife holder 54. Such a configuration allows the cutting edge 78 of the cutting assembly 50 to contact a work piece, such as a log, during operation of the ring strander device 40.
The knife blade 56 is configured to be easily inserted into and removed from the cutting assembly 50 while the cutting assembly is installed in the ring strander device 40. For example, while the knife blade 56 can be configured as having a variety of thicknesses, in one arrangement, the knife blade has a thickness of up to about 0.062. The relative thinness of the knife blade 56 reduces the overall weight of the knife blade, compared top conventional plate knives, and allows an operator to handle the knife blade 56 without requiring the use of excessive force. For example, the knife blade 56 weighs between about two pounds and three pounds.
In the arrangement illustrated, the knife blade 56 is formed as a bi-metal material. For example, the knife blade 56 includes a body portion 82 formed of a first material and a cutting or edge portion 84 formed of a second material and disposed along an edge of the body portion 82. While the body portion 82 can be formed from a variety of materials, in one arrangement, the body portion 82 is formed of a material having relatively high fatigue-resistance properties. For example, the body portion 82 can be formed from a medium carbon, low alloy steel, such as D6A, 6135 steel, or 6150 steel having a hardness of between about 42 and 48 HRC. Additionally, while the edge portion 84 can be formed from a variety of materials, in one arrangement, the edge portion 84 is formed from a material having relatively high wear-resistance properties. For example, the edge portion 84 can be formed from a high-speed steel material such as high-speed steel material M42 having a hardness of at least about 60 HRC and, in one arrangement, between about 63 and 70 HRC. The high-speed steel material helps to minimize wear of the knife blade 56 when used during the waferizing process.
The knife blade 56 includes a weld zone 86 disposed between the body portion 82 and the edge portion 84. For example, during the manufacturing process, an assembler secures the high-speed steel edge portion 84 to the body portion 82 using a welding technique, such as an electron welding technique. During the welding process, the high-speed steel edge portion 84 and the body portion 82 enter a lead lined vacuum chamber where a carbide guide pushes the edge portion 84 and the body portion 82 together. An electron source shoots beam of electrons at the interface of the body and edge portions 82, 84. The friction of the electrons passing between the portions 82, 84 heats the materials to melting temperatures and fuses the body and edge portions 82, 84 together at an interface termed the weld zone. The weld zone maintains the coupling of the body and edge portions 82, 84 during use of the knife blade 56. Once welded together, the assembler then grinds a bevel into the edge portion 84 of the knife blade 56. In one arrangement, the assembler grinds a bevel angle 81 of between about 30° and 35° relative to a planar surface 94 the knife blade 56. While an electron welding technique is described as being used to join the high-speed steel edge portion 84 and the body portion 82, alternate joining techniques can be used as well. For example, any form or welding or a permanent adhesive can be used to join the high-speed steel edge portion 84 and the body portion 82.
The counter knife 58 of the cutting assembly 50 is configured to cause the shavings generated by the knife blade 56 to break into wood wafers having a particular range of widths. For example, a distal portion or edge of the counter knife 58 defines a set back distance 90 of about 0.38 inches with the knife blade 56. Furthermore, the distal portion of the counter knife defines an angle 92 of between about 55° and 65° relative to a planar surface 94 of the knife blade 56. The set back distance 90 and the angle 92 define a travel path 96 for the shavings generated by the knife blade 56 which causes the shavings to break into wood wafers or strands having a width of between about 1 inch and 2 inches.
In one arrangement, the counter knife 58 is formed from a metal material and includes a coupling mechanism 98 configured to secure the counter knife 58 to the ring strander drum 42. For example, the coupling mechanism 98 can be a screw element which is matable with a correspondingly tapped hole formed in the ring strander drum 42. However, other coupling mechanisms 98, such as magnets, can be utilized.
The scoring tip holder 60 carries one or more scoring tips 100 that are configured to slice into a work piece, such as a log, to define the lengths of the shavings produced by the ring strander, typically about 4 inches in length. The scoring tip holder 60 also includes one or more fasteners 62 configured to secure the knife holder 54 to the scoring tip holder 60. The fasteners, such as screw elements, limit relative movement between the knife holder 54 and the scoring tip holder 60 during replacement of the knife blade 56.
As indicated above, the configuration of the cutting assembly 50 allows and operator to remove and replace the knife blade 56 without requiring removal of the entire cutting assembly 50 from the ring strander device 40.
In order to secure the knife blade 56 to the cutting assembly 50, as indicated in
During operation of the ring strander device 40, and with reference to
In the event that the operator detects the knife blades 56 have become dull, the operator stops the rotation of the ring strander drum 42 and replaces each of the knife blades 56. Returning to
As indicated above, during operation, the ring strander drum 42 rotates about a central axis thereby causing the cutting assemblies 50 to generate wood wafers. As the ring strander drum 42 rotates, the ring strander drum generates a centrifugal force on the knife blades 56 to drive the knife blades 56 against the ring strander drum 42 to further secure the knife blades within the cutting assemblies 50. As an operator detects dulling of knife blades 56 during the waferizing process, the operator stops rotation of the ring strander drum 42 and, for each cutting assembly 50, the knife blades 56. However, referring to
While various embodiments of the invention have been particularly shown and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
For example, the knife blade 56 is illustrated as having a single cutting edge portion 84. Such description is by way of example only. In one arrangement as illustrated in
As indicated above, the cutting assembly 50 includes a separate knife holder 54 and scoring tip holder 60. Such description is by way of example only. In one arrangement, the knife holder 54 and the scoring tip holder 60 are integrally formed as a single piece.
As indicated above, the knife blade 56 can include an interlock portion 121 to help secure the knife blade 56 with a corresponding cutting assembly 50. The description of the widened back portion and L-shaped interlock portions were given as examples only. Other interlock mechanisms can be used to help secure the knife blade 56 with a corresponding cutting assembly 50. For example, dovetail joints, tongue and groove joints, magnetic interlocks, and adhesives can be utilized to help secure the knife blade 56 within the cutting assembly 50.
As indicated above, the edge portion 84 of the knife blade 56 can be formed from a high-speed steel material such as high-speed steel material M42. Such description is by way of example only. In one arrangement, the edge portion 84 can be formed from a high-speed steel material, such as an M-series, T-series, H-series, or D-series high-speed steel material.
As indicated above, and with reference to
As indicated above and with reference to
As indicated above, the counter knife 14 is formed from a metal material. Such description is by way of example only. In one arrangement, the counter knife 14 is formed from a plastic material, such as an injection molded plastic, having a distal edge formed from a metal material, such as a wear resistant (e.g., high speed steel). The use of the plastic material reduces the weight of the counter knife 14 thereby providing ease of handling to an operator.
