1) Field of the Invention
The present invention relates to rotatable cutting tools and, more specifically, to supporting one or more knives in alternate configurations.
2) Description of Related Art
Rotatable cutting tools are well known in the art and include, among others, saws, knives, cutterheads, heads or chucks with removable knives, drill bits, router bits, drills, end mills, moulders, and grinders of multiple shapes. These tools are used for cutting or grinding a variety of structural materials including, but not limited to, wood, metal, composite materials, plastic, foam, food products, and the like.
One conventional rotatable cutting tool, commonly referred to as a cutterhead, typically includes a generally cylindrical body that defines several longitudinally extending cavities for receiving knives. Each knife is inserted into one of the cavities and positioned so that a cutting edge of the knife extends from the cutterhead. The knife is then secured in place by tightening bolts that extend through part of the body and urge the knife against one wall of the cavity. Typically, the bolts are inserted through milled pockets on the outside of the cutterhead so that the heads of the bolts do not extend from the tool. The cutterhead is then rotated, for example, by a spindle that is connected to a motor. Structural material is brought into contact with the rotating knives, and the structural material is cut or scraped by the knives.
The configuration of the knives relative to the body affects the type of cutting or scraping that is achieved. For example, the hook and shear angles of the knives can affect the degree of material that is removed by each knife and the surface that is left on the structural material. The hook angle is measured as the angle between a leading surface of the knife and a radial line of the body that extends through the edge of the knife. A positive hook angle indicates that the leading surface of the knife is angled toward the direction in which the knife rotates. A knife with zero or little hook angle contacts the structural material so that the edge of the knife is approximately perpendicular to the surface of the structural material, thus resulting in a primarily scraping action of the structural material. A knife with positive hook angle, however, tends to achieve a slicing action because the cutting edge is directed closer to the direction of motion of the knife relative to the structural material.
The shear angle is measured as the angle between the longitudinal extension of the blade and the longitudinal axis of the body. For example, a zero shear angle indicates that the blade is parallel to the longitudinal axis of the body. A non-zero shear angle indicates that the blade is angled relative to the body so that a first end of the blade leads the blade and the opposite end of the blade trails as the body and blade are rotated.
An improper hook or shear angle can result in fracturing of the wood, rough or uneven work surfaces, excessive wear of the knives, and other poor cutting characteristics. The best hook and shear angle can depend on the structural material, including grain, fracture, and hardness characteristics. Thus, processing different structural materials can require adjustment of the hook and/or shear angle of the knives. For example, it is known in the art to use a hook angle of about 12° when cutting certain hard woods and 20° when cutting certain soft woods. Because the hook and shear angle of the knives is typically determined by the configuration of the cavities of the cutterhead, adjusting the hook or shear angle can require changing the knives and/or cutterhead, which can be time consuming, thereby reducing machine efficiency. Additionally, keeping multiple cutterheads with different hook and shear angles on hand for different processes requires a disadvantageous additional expense.
A known cutterhead includes a first pair of cavities configured at a first hook angle, and a second pair of cavities that are completely separate from the first pair of cavities and configured at a second hook angle. Knives are positioned in either the first or the second pair of cavities, and fillers are typically positioned in the other pair of cavities such that the fillers do not extend from the cavities. Bolts are used to secure the knives and fillers in the respective cavities. When it is desired to adjust the hook angle of the knives, the position of the knives and fillers are reversed. Thus, a single cutterhead provides two modes of operation, each characterized by a distinct hook angle. However, the provision of additional cavities that are not occupied by knives can change the rotational and balance characteristics of the cutterhead and the tool can be damaged if used without securing appropriate fillers in the cavities that are not being used to secure knives. If fillers are positioned in the unused cavities, there is a risk that improperly sized or weighted fillers will be used, thereby increasing the risk of tool failure and damage to nearby equipment. Additionally, the milled pockets provided for the bolts can also adversely affect the strength of the tool as well as the rotational and weight characteristics of the tool. Further, if the bolts are not properly tightened, the knives and/or fillers may become loose during operation and be projected from the tool.
Thus, there exists a need for an improved rotatable cutting tool that can support one or more knives in alternate angular configurations to achieve multiple hook angles at one or more shear angles. Preferably, the cutting tool should reduce the likelihood of incorrect installation of knives, fillers, bolts, and/or other components. Additionally, the cutting tool should be compatible with different knives and adaptable to conventional tool variations.
In accordance with one aspect, the present invention provides an improved rotatable cutting tool, which is preferably a cutterhead, for supporting at least one cutting instrument such as a knife in at least two alternate angular cutting configurations. The body of the cutting tool defines at least one cavity that preferably extends at least generally in a longitudinal direction of the body, for example, parallel to a longitudinal axis of the body or at an angle to the longitudinal axis of the body. Thus, each cavity can define a hook angle and a shear angle, and different cavities of the body can define different hook and/or shear angles.
According to one embodiment of the present invention, each cavity is preferably defined by first and second knife support surfaces that are in an opposing, face-to-face, non-parallel configuration. The knife support surfaces preferably extend divergingly inwardly from an exterior surface of the body. The first knife support surface is configured to support one of the knives at a first hook angle. The second knife support surface is configured to subsequently support one of the knives at a second, different hook angle. In one example, the first hook angle can be about 12 degrees and the second hook angle can be about 20 degrees. Each angle is measured relative to a radial direction of the body that extends through an edge of the knife supported by the respective knife support surface.
In one embodiment, each cavity is configured to alternately receive a knife against each knife support surface, a filler against the knife support surface that is not occupied by the knife, and a gib between the knife and filler such that the gib urges the knife and filler against the support surfaces and frictionally secures the knife in the cavity. Preferably, at least one of the knife, filler, and gib are slid into the cavity to achieve a frictional press-fit, such as between the gib and the knife and between the gib and the filler. In accordance with one aspect of the present invention, the gib can receive bolts that extend therethrough and, when tightened against a wall that defines the cavity, adjust the gib radially outward to secure the knife and filler. The body can optionally include one or more visual references for indicating a maximum extension position of each knife, the hook angles, or a rotational motion of the cutting tool.
According to another embodiment of the present invention, the rotating cutting tool includes first and second cavities that define different shear angles so that a knife can be selectively supported in the cavities at the different shear angles. For example, each cavity can have a shear angle that is between about 0 and 10 degrees relative to the longitudinal axis of the body. In particular, the first cavity can have a shear angle of about 5 degrees and a hook angle between about 10 and 12 degrees, and the second cavity can have shear angle that is about 10 degrees and a hook angle that is about 20 degrees. The body can define additional cavities that correspond to the first and second cavities so that multiple knives can be supported in each configuration.
The present invention also provides methods of cutting structural material, which in one example includes configuring the cutting tool as described above, mounting the cutting tool body on a rotatable spindle in rotational communication with a rotational actuator, and rotating the cutting tool. The rotational axis and the longitudinal axis of the cutting tool are preferably aligned with one another. Structural material is engaged against the knives and cut. In one embodiment, after cutting, the position of the knife in each cavity is switched with the filler in the respective cavity so that the knife extends from the body at a second angle different from the first angle. Alternatively, the configuration of the knife in each cavity can be otherwise adjusted, e.g., by removing each knife from one cavity and disposing the knife in a different cavity with a different hook and/or shear angle. The cutting tool is then rotated, and the structural material is cut.
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
The cavities 30 (
As diagrammatically illustrated in
The body 20 also defines a hole 28, which preferably extends completely through the body 20 and is configured to connect to a spindle 12, as shown in
Each cavity 30 of the body 20 is adapted to receive and support one of the knives 50 in at least two configurations. Each cavity 30 includes a first pocket or slot 36 and a second pocket or slot 38. The cavity 30 is at least partially defined by a first knife support surface 32, which at least partially defines the first slot 36, and a second knife support surface 34, which at least partially defines the second slot 38. Thus, when one of the knives 50 is positioned in the first slot 36, as shown in
The cavities 30 of the body 20 are also adapted to receive the fillers 60. The fillers 60 may comprise any suitable stock material and preferably do not extend from the cavities 30. In the illustrated embodiments, each filler defines an angled surface 62, which may be flat or curved, for example, to match the curvature of the outer surface 26 of the body 20. Although the fillers 60 are shown to have the same thickness as the knives 50, the fillers 60 may have different thickness. In one embodiment, fillers 60 of different thicknesses are used according to the thickness of the knives 50, such that the total thickness of one knife 50 and one filler 60 is equal to a predetermined dimension. For example, a ¼ inch filler can be used with a ¼ inch knife, a 3/16 inch filler can be used with a 5/16 inch knife, and a ⅛ inch filler can be used with a ⅜ inch knife, so that the total thickness of the knife 50 and the filler 60 is ½ inch. Different predetermined dimensions and proportions are also within the scope of the present invention.
Each knife 50 and filler 60 is preferably frictionally secured in place in the respective cavity 30 by one of the gibs 70, each of which is positioned in each cavity 30 between the respective knife 50 and the filler 60. Each gib 70 defines first and second surfaces 74, 76 in an opposed configuration. As shown, for example, in
Preferably the knives 50 and the fillers 60 can be positioned in the cavities 30 first and the gibs 70 can be positioned by positioning each gib 70 proximate to one of the sides 22, 24 of the body 20 and forceably sliding the gib 70 longitudinally into one of the cavities 30. Regardless of the order of assembly of the cutting tool 10, the knives 50, fillers 60, and gibs 70 preferably fit tightly in the cavities 30 so that a press fit is achieved and the gibs 70 urge the knives 50 and the fillers 60 respectively toward the knife support surfaces 32, 34 and thereby frictionally secure the knives 50 and the fillers 60 in the cavities 30. In one embodiment, bolts are not required for securing the knives 50, fillers 60, and gibs 70 in the cavities 30, but bolts can optionally be used to enhance securing, for example as discussed below with reference to
The knives 50, the fillers 60, the gibs 70, and/or the knife support surfaces 32, 34 can also be “corrugated,” knurled, or otherwise contoured to facilitate the secure engagement of the knives 50, fillers 60, gibs 70, and body 20. Those of ordinary skill in the art will understand that in this context, corrugations include an alternating series of ridges and grooves that extend at least generally in the longitudinal direction, or the like. For example, in one embodiment shown in
Further, for the embodiment of
The first and second knife support surfaces 32, 34 are preferably angled differently relative to a radial direction of the body 20. For example, as shown in
In one preferred embodiment, the first knife support surface 32 is angled radially outwardly toward the second knife support surface 34, and the second knife support surface 34 is angled radially outwardly toward the first knife support surface 32, such that the first and second knife support surfaces 32, 34 define a converging angle therebetween, for example, as shown in
The knives 50 can preferably also be secured in different radial positions in the cavities 30 to adjust the extension of the knives 50 from the body 20. Thus, a particular knife 50 can be adjusted to achieve different lengths of extension from the body 20 as may be desired for different operations. A visual reference is preferably provided on the cutting tool 10 for indicating the maximum extension position of the knives 50. For example, the body 20 of the illustrated embodiments defines a maximum extension line 40 that marks the maximum extension position for the knives 50, i.e., the knives should not be extended beyond the line 40. For illustration, the knives 50 are shown in
The axial orientation of the knives 50 can be reversed. For example, in
As noted above in connection with
Thus, the cutting tool 10 shown in
The knives 50 can define a variety of shapes and sizes, and preferably the knives used according to the present invention are conventional. For example, each knife can define a prismatic shape as illustrated in the figures, i.e., each knife can be uniform in the longitudinal (i.e., axial) direction. Alternatively, the edge 52 can define a non-linear profile to impart a corresponding profile onto the structural material. For example, the edge 52 can define one or more notches, curves, slants, and the like, which impart a corresponding profile on the structural material. Also, the knives 50 can be adjusted or maintained by machining or otherwise processing the surfaces 54, 56 to affect the cutting action of the knifes 50. For example, in the illustrated embodiment, the second surface 56 of each knife 50 defines a tapered portion, which can be machined in order to sharpen the edge 52, change the angle of the tapered portion, or smooth the second surface 56.
The cutting tool 10 can optionally include one or more visual references that indicate the rotational motion of the tool 10. For example, the cutting tool of
The tool 10 can be used with a wide variety of conventional knives 50, such as either corrugated or non-corrugated steel, carbide, stellite, or any other tool material.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
This application is a continuation of U.S. application Ser. No. 11/047,395, filed Jan. 31, 2005 now U.S. Pat. No. 7,237,586 which is a continuation-in-part of U.S. application Ser. No. 10/277,766, filed Oct. 22, 2002 now U.S. Pat. No. 6,896,017, which is hereby incorporated herein in its entirety by reference.
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Number | Date | Country | |
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20070199419 A1 | Aug 2007 | US |
Number | Date | Country | |
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Parent | 11047395 | Jan 2005 | US |
Child | 11743340 | US |
Number | Date | Country | |
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Parent | 10277766 | Oct 2002 | US |
Child | 11047395 | US |