Cutter blade and assembly for a rotary cutter

A blade assembly for a rotary cutter. The blade assembly comprises a blade carrier rotatably connected to the rotary cutter. The blade assembly additionally comprises one or more cutter blades secured to the blade carrier such that rotation of the blade carrier causes a corresponding rotation of the cutter blades. The blade assembly further comprises a blade stop associated with the blade carrier and configured to inhibit rotation of the cutter blades with respect to the blade carrier.

FIELD

Embodiments of the present invention are directed to a cutter blade and a cutter blade assembly for agricultural equipment. More particularly, embodiments of the present invention are directed to a cutter blade and a cutter blade assembly configured for use with for a rotary cutter.

BACKGROUND

Rotary cutters are agricultural implements used for cutting large areas of vegetation, such as grass, weeds, shrubs, or the like. In general, a rotary cutter comprises a deck, which is supported above the ground by one or more wheels. The rotary cutter additionally includes one or more rotating blade assemblies that extend from a bottom of the deck. The blade assemblies each include one or more rotating blades configured to cut vegetation as the rotary cutter travels over the ground. Certain types of rotary cutters are configured to be pulled behind a heavy-equipment machine, such as a tractor. As such, rotary cutters are capable of traversing the ground on which the vegetation to be cut is present.

In previously used rotary cutters, the cutter blades used in the blade assemblies were commonly known to become locked in skewed orientations with respect to their respective blade assemblies. Such locking of the cutter blades in a skewed orientation inhibited cutting action. In addition, such previously-used cutter blades were often known to cause unwanted vibrations throughout the rotary cutters. The inventors of the present invention have determined that such problems were due, in part, to the previously-used cutter blades having low centers of gravity (the term “low” is used herein to mean located in a direction away from the deck of the rotary cutter and towards the ground when the blade assemblies extend from a bottom of the deck). As discussed herein, the term “center of gravity” is used to mean a point in or on the cutter blade that defines the cutter blade's center of mass.

In general, the center of gravity of previously-used cutter blades was generally positioned below a horizontal plane that bisected a height of the cutter blade (with the height being defined as a distance from a lowest point of the cutter blade to a highest point of the cutter blade). Such low centers of gravity were due, in part, to previously-used cutter blades being “vertically offset.” Specifically, free-ends of most previously-used cutter blades were positioned lower than (i.e., vertically-offset from) the proximal ends of the cutter blades, with the proximal ends being connected to the blade assemblies. Such vertically-offset cutter blades were thought to be beneficial because the free-ends of the cutter blades would not impact the blade assemblies (or the cutter deck) if the cutter blades were permitted to freely rotate with respect to the cutter assemblies. As such, vertically-offset cutter blades could avoid causing damage to the rotary cutter, to the blade assemblies, and to the cutter blades themselves. Nevertheless, such vertically-offset cutter blades have drawbacks. For example, because such cutter blades extend far below the deck of the rotary cutter, they are prone to come into contact with the ground and/or debris when the rotary cutter is in operation.

SUMMARY

A blade assembly for a rotary cutter. The blade assembly comprises a blade carrier rotatably connected to the rotary cutter. The blade assembly additionally comprises one or more cutter blades secured to the blade carrier such that rotation of the blade carrier causes a corresponding rotation of the cutter blades. The blade assembly further comprises a blade stop associated with the blade carrier and configured to inhibit rotation of the cutter blades with respect to the blade carrier.

Embodiments of the present invention are also directed to a rotary cutter for cutting vegetation growing from the ground. The rotary cutter comprises a deck, one or more wheels for supporting the deck above the ground, and one or more rotatable blade assemblies extending below the deck. Each of the blade assemblies comprises a blade carrier and one or more cutter blades secured to the blade carrier, such that rotation of the blade carrier causes a corresponding rotation of the cutter blades. Each of the blade assemblies further comprise a blade stop associated with the blade carrier and configured to inhibit rotation of the cutter blades with respect to the blade carrier.

Embodiments of the present invention additionally comprise a method of operating a rotary cutter configured to be pulled behind a tractor. The method comprises the initial step of connecting the rotary cutter to the tractor, with the rotary cutter comprising one or more rotatable blade assemblies extending below the rotary cutter, and with each of the blade assemblies comprising one or more cutter blades rotatably secured to the blade assembly. Each blade assembly further comprises a blade stop for inhibiting rotation of the cutter blades with respect to the blade assembly. The method comprises the additional step of providing power to the rotary cutter to cause rotation of the blade assemblies. During the providing power step, the cutter blades are prevented from rotating more than 120 degrees from a radial extension with respect to the blade carrier.

DISCLOSURE

The inventors of the present invention determined that due to the low center of gravity of previously-used rotary cutter blades, when a rotary cutter's blade assemblies are initially caused to rotate (e.g., via Power-Take-Off (PTO)/gear boxes, motors, or the like), the impulse of such rotational forces acting on the cutter blade assemblies can cause the cutter blades to be forced into a skewed orientation. The rotational acceleration acting on the cutter blades can cause the cutter blades to be lifted into contact with the blade carrier of the blade assembly, or into engagement with the deck of the rotary cutter. The magnitude of the contact force was found to be related to the cutter blade's center of gravity and the amount of angular acceleration imparted to the cutter blade. If the contact force was too strong, the cutter blade would be prone to lock into engagement with the blade carrier (or the deck of the rotary cutter) at a skewed orientation and, due to the continuing power delivered by the PTO, motors, etc, the cutter blades were not permitted to return to a radial extension, which is preferred for efficient cutting action.

For example, in certain rotary cutters powered by a PTO of a tractor, upon initialization of the rotary cutter, the PTO can cause an impulse force that accelerates the cutter blades from 0 to 1200 rotations per minute (RPM) in less than 1 second. When previously-used cutter blades with low centers of gravity are used, such a high impulse force can cause the cutter blades to become locked in place against the blade carrier due to the large contact force. If the cutter blades are initially positioned in a skewed orientation (i.e., not in a radial extension with respect to the blade carrier), the cutter blades can remain locked in such a skewed orientation due to their engagement with the blade carrier and/or the rotary cutter deck. Such a skewed orientation can be problematic because it reduces the cutter blade's cutting efficiency. Furthermore such a skewed orientation can cause significant vibrations to be transmitted throughout the rotary cutter.

Embodiments of the present invention are broadly directed to a rotary cutter with cutter blades that include a relatively high center of gravity, so as to prevent the cutter blades from being forced upward into a skewed orientation during initialization of the rotary cutter. In addition, certain embodiments of the present invention broadly include a blade carrier that restricts cutter blades from freely rotating around the entirety of the cutter assembly, so as to prevent the cutter blades from impacting and damaging the cutter assembly and/or other portions of the rotary cutter.

FIGS. 1-3illustrate a rotary cutter10according to embodiments of the present invention. The rotary cutter10will generally include a housing or a frame in the form of a deck12. One or more wheels may extend from the deck12to support the rotary cutter10while it is being pulled by the tractor (not shown). As illustrated inFIGS. 2-3, the rotary cutter10may include one or more rotatable blade assemblies20extending from a bottom side of the deck12. Specifically, each of the blade assemblies20may include a blade carrier22extending below the deck12and configured to support one or more cutter blades24. However, in some other embodiments, the blade assemblies20may not include a blade carrier22, but may, instead, include a dishpan, which may comprise a thin, disc-shaped piece of material rotatably secured underneath the deck12and configured to support one or more cutter blades24.

As shown inFIG. 4-6, each blade assembly20of embodiments of the present invention may include the blade carrier22, which may have two or more (e.g., 3, 4, or more) cutter blades24pivotally secured thereto via a blade pin26. As perhaps best shown inFIG. 6, the blade carrier22may include an upper portion28formed as an elongated section of metal that extends in opposite directions from its center30. A top of the center30of the upper portion28may be connected to a rotation coupler32. As described in more detail below, the rotation coupler32may be connected with rotary-power elements of the rotary cutter10, so as to provide rotation to the blade assembly20. The center30of the upper portion28may be raised with respect to outer ends34of the upper portion28. As such, the cutter blades24, which are secured to the blade carrier22at positions adjacent to the outer ends34of the upper portion28, are configured to extend below the deck12of the rotary cutter10. In some embodiments, the blade carrier22may also include a lower portion36secured to a bottom of the upper portion28. The lower portion36may be a generally planar section of metal that is secured (e.g., via weld) to the bottom of the upper portion28, and, particularly, to the outer ends34of the upper portion28. As such, the blade carrier22may be presented to include a gap extending between the lower portion36and the center30of the upper portion28.

As noted above, the cutter blades24may be connected to opposite ends of the blade carrier22, such that the cutter blades24are generally configured to extend from opposite sides of the blade carrier22. Specifically, with reference toFIG. 6, a first end (“proximal end”38) of each of the cutter blades24may be pivotally secured to the blade carrier22via blade pin26, or alternatively via a bolt (e.g., a shoulder bolt) or the like. A second end (“distal end”39or “free end”) of each of the cutter blades24may extend away from the blade carrier22. As such, when the blade carrier22is caused to rotate, each of the cutter blades24will correspondingly rotate, thereby, creating a cutting action for the rotary cutter10to cut vegetation.

In more detail, and returning back toFIG. 1, a rear side of the tractor (not shown) can be connected to a front side40of the rotary cutter10, such that the rotary cutter10can be pulled from behind the tractor. In addition to pulling the rotary cutter10, in some instances, the tractor can provide the rotary power required to rotate the blade assemblies20and, thus, the cutter blades24of the rotary cutter10. For instance, as shown inFIG. 1, the rotary cutter10may include a power take off (PTO) connection42for connecting to a PTO of the tractor. In other embodiments, the rotary cutter10may include its own power source, such as an internal engine or motor, for powering the blade assemblies20and/or other features of the rotary cutter10.

The rotary cutter10may include various mechanisms for transferring rotary power from the PTO (or from the engine or motor) to the blade assemblies20. For instance, as shown inFIG. 3, each of the blade assemblies20may be associated with a gear box44configured to transfer rotational power down through the deck12to the blade assemblies20. Specifically, rotational power may be provided by the PTO of the tractor to each of the gear boxes44(in some cases via one or more intermediate transfer gear boxes) via the PTO connection42. Such rotational power may then be transitioned 90 degrees downward, via the gear boxes44, to the blade assemblies20to cause rotation of the blade carriers22. Rotation of the blade carriers22will cause a corresponding rotation of the cutter blades24so as to provide a cutting action for the rotary cutter10. In alternate embodiments, the rotary cutter10may have one or more motors in place of the PTO and gear boxes, such that the motors are configured to provide rotary motion to the blade carriers22and to the cutter blades24.

Returning toFIG. 6, and with further reference toFIGS. 7 and 8, certain embodiments of the present invention provide for the blade assembly20to include a base element50with a raised blade stop52. The base element50may be secured to the blade carrier22by various methods of attachment, such as by fasteners or by weldments. For example, as shown inFIG. 6, the base element50may be connected to the lower portion36of the blade carrier22via nut and bolt combinations. With the cutter blades24attached to the bottom of the blade carrier22, the base element50may be connected to a bottom side of the cutter blades24, such that the cutter blades24are sandwiched between the blade carrier22and the base element50. The blade pins26may extend through each of the blade carrier22, the cutter blades24, and the base element50so as to maintain each of the components together. Although the blade pin26secures the components together, the blade pin24is configured to permit rotation of the cutter blade24with respect to the remaining components of the blade assembly20. As illustrated inFIG. 5, a bottom surface of the base element50may have beveled outer edges, which may facilitate movement of the rotary cutter10over the ground by reducing the chance that a blade assembly20is impeded by contact with the ground or with objects and debris.

Beneficially, the blade stop52of the base element50may function to restrict rotation of the cutter blades24with respect to the other components of the blade assembly20(e.g., blade carrier22and base element50). As perhaps best illustrated byFIG. 6, the blade stop52may be raised with respect to the remaining portions of the base element50, such that the blade stop52presents stop surfaces54that are configured to engage sides of the cutter blades24when the cutter blades24rotate too far with respect to the blade carrier22. In more detail, during normal operation of the rotary cutter10, the blade assemblies20are caused to rotate such that the cutter blades24will normally extend radially outward from a center of the blade assembly20(i.e., radially from the rotation coupler32), as is illustrated inFIGS. 4 and 5. However, in some instances, such as during initialization of the rotary cutter10(i.e., when the blade assemblies20are initially caused to rotate during start-up of the rotary cutter10), the cutter blades24may be forced out of a radial extension, such that they rotate with respect to the remaining portions of the blade assembly20. In such instances, as shown inFIGS. 7 and 8, the cutter blades24will be forced into contact with the stop surfaces54of the raised blade stop52so as to prevent the cutter blades24from rotating too far (with respect to the blade assembly20) and impacting and/or damaging the blade carrier22. In some embodiments, the blade stop52may be configured to restrict the cutter blades24from rotating more than 70 degrees, more than 80 degrees, more than 90 degrees, more than 100 degrees, more than 110 degrees, more than 120 degrees, more than 130 degrees, or more than 140 degrees from a radial extension (with such a radial extension illustrated inFIGS. 4 and 5).

In addition to the blade carrier22, embodiments of the present invention are further directed to a cutter blade24designed to include a center of gravity that is generally higher than cutter blades previously used for rotary cutters. The cutter blade24of the present invention may be formed from various types of material with high strength and high durability, such as5160or5160H heat treated steel. In more detail, as shown inFIG. 9, the cutter blade24of the present invention may broadly comprise a longitudinally-extending blade with proximal end38, distal end39, a leading edge60, a back edge62, an upper surface64, and a lower surface66. The proximal and distal ends38,39are separated by a length of the cutter blade24and extend along a width of the cutter blade24. The leading and back edges60,62are separated by the width of the cutter blade24and extend along the length of the cutter blade24. The upper and lower surfaces64,66are separated by a thickness of the cutter blade24and extend between the length and the width of the cutter blade24.

In more detail, and remaining withFIG. 9, the cutter blade may be comprised of three primary sections, including a base section70, a cutting section72, and a connecting section74that transitions between and connects the base section70and the cutting section72. The base section70may extend from the proximal end38of the cutter blade24to the connecting section74. The base section70may include a through-hole75or an opening by which the cutter blade24is securable to the blade carrier22via the blade pin26, as was previously described.

The connecting section74may extend in a twisting manner from the base section70to the cutting section72. Specifically, in some embodiments, as shown inFIG. 9, the leading edge60of the connecting section74may extend downward to the leading edge60of the cutting section72, and the back edge62of the connecting section74may extend upward to the back edge62of the cutting section72. As such, the connecting section74extends in a twisting manner from the base section70to the cutting section72.

The cutting section72may extend from the connecting section74to the distal end39of the cutter blade24. In some embodiments, the cutting section72may be shaped in the form of an airfoil that extends upward from the leading edge60to the back edge62. The cutting section72may generally include a cutting surface76, which extends along the leading edge60of the cutter blade24. The cutting surface76may be sharpened to perform the cutting action of the cutter blade24. In some embodiments, the cutting surface76may be milled, while in other embodiments, the cutting surface76may be formed by compressing the metal of the cutter blade24when it is in a malleable form. In some embodiments, the cutting surface76may extend along the entire length of the cutting section72. In some embodiments, the cutting surface76may also extend along at least a portion of the connecting section72.

In some embodiments, the cutter blade24according to embodiments of the present invention is configured as a “straight blade.” As used herein, and with reference toFIG. 10, the term “straight blade” is defined to mean a cutter blade that includes a horizontal plane80that bisects a height “Hcs” of the cutting section74that is no more than 0.25*Hcs (the asterisk here is meant to indicate the multiplication operator), no more than 0.20*Hcs below, no more than 0.15*Hcs below, no more than 0.10*Hcs below, no more than 0.05*Hcs below, or not below (i.e., even with or located above) a horizontal plane82that bisects a thickness “Tbs” of the base section70. Other embodiments of the present invention may be directed to a “vertically-offset blade,” which will be described in more detail below.

Remaining with the straight blade embodiments of the cutter blades, such as illustrated by cutter blade24shown inFIGS. 9-10, such cutter blades24are beneficially formed with a generally high center of gravity. To facilitate such a high center of gravity, the cutter blade24may be formed with the following dimensions, measurements and/or measurement ranges. As shown inFIG. 10, a length “L” of the cutter blade24(as measured from a center of the through-hole75of the base section70to the distal end39of the cutter blade24) may be between 5 to 30 inches, between 10 and 25 inches, between 15 and 20 inches, or about 18 inches. Nevertheless, embodiments of the present invention may provide for the length “L” to be formed with other lengths as may be required for a specific cutting job or for use with a particular rotary cutter. Furthermore, the cutter blade24may extend a distance of between 1 and 5 inches, between 2 and 4 inches, or about 2.5 inches from the through-hole75to the proximal end38of the cutter blade24, such that the overall length of the cutter blade24may be about 20.5 inches.

With reference toFIG. 11, the cutter blade24may include the width “W” as measured from the leading edge60to the back edge62of between 2 to 8 inches, between 3 to 6 inches, about 4 inches, or about 5 inches. The thickness “T” of the cutter blade24, as measured from the lower surface66to the upper surface64, of between 0.1 to 2 inches, between 0.25 to 1 inches, or about 0.5 inches. The height “H” of the cutter blade24, measured as the maximum vertical distance of the cutter blade24between the lower surface66and the upper surface64, of between 1 to 6 inches, between 2 to 5 inches, about 3.14 inches, or about 3.49 inches. It is understood that the height “H” of the cutter blade24(i.e., the maximum vertical distance of the cutter blade24between the lower surface66and the upper surface64) will generally be, for cutter blade24, equal to the height “Hcs” of the cutting section72, as is shown inFIG. 10.

Turning to the individual sections of the cutter blade24in more detail, and with reference toFIG. 12, the base section70may have a base length “BL” (as measured from the center of the through-hole75of the base section70to the connecting section74). With reference toFIG. 10, the base length BL may be illustrated approximately as L1. The base length BL may be between 4 to 10 inches, between 6 to 8 inches, or about 6.5 inches. In some embodiments, a ratio of the base length BL to the cutter blade24length L (i.e., BL:L) may be between 1:5 to 1:2, between 3:10 to 2:5, or about 1:3. Furthermore, in some embodiments, the proximal end38of the base section70may be rounded so as to facilitate the ability of the cutter blade24to rotate with respect to the blade assembly20without the proximal end38substantially interfering with the blade stop52. As such, the proximal end38of the base section70may be formed with a radius of curvature R1(SeeFIG. 9) of between 2 and 3 inches, between 2.25 and 2.75 inches, or about 2.5 inches.

Returning toFIG. 12, the connecting section74may have a connecting length “CnL” (as measured from the base section70to the cutting section72). With reference toFIG. 10, the connecting length CnL may be illustrated approximately as the distance between L1and L2. The connecting length CnL may be between 1 to 5 inches, between 2 to 4 inches, or about 3.25 inches. In some embodiments, a ratio of the connecting length CnL to the cutter blade length L (i.e., CnL:L) may be between 1:20 to 2:5, between 1:10 to 3:10, or about 1:5. As previously described, the connecting section74may extend in a twisting manner to the cutting section72. For example, in some embodiments, the leading edge60of the connecting section74may extend downward to the leading edge60of the cutting section72a distance of between 1.0 to 1.5 inches, between 1.1 to 1.4 inches, about 1.2 inches, or about 1.3 inches. In addition, the back edge62of the connecting section74may extend upward to the back edge62of the cutting section72between 1.2 to 1.9 inches, between 1.3 to 1.8 inches, about 1.4 inches, or about 1.7 inches. As such, the connecting section74extends in a twisting manner from the base section70to the cutting section72.

Returning toFIG. 12, the cutting section72may have a cutting length “CtL” (as measured from the connecting section74to the distal end39of the cutter blade24). As shown inFIG. 10, the cutting length CtL may be illustrated approximately as the distance between L2and L3. The cutting length CtL may be between 6 to 10 inches, between 7 to 9 inches, or about 8.25 inches. In some embodiments, a ratio of the cutting length CtL to the cutter blade length L (i.e., CtL:L) may be between 1:3 to 2:3, between 2:5 to 3:5, or about 1:2. As indicated above, the cutting section72may be formed in an airfoil shape. To create such an airfoil shape, the cutting section72may be curved to include a radius of curvature R2, as illustrated inFIG. 11, of between 2 and 7 inches, between 3 and 6 inches, about 3.75 inches, or about 5 inches. The airfoil design may, in some embodiments, provide a lifting force during rotation of the cutter blades24, which functions to lift vegetation from the surface of the ground so that the vegetation can be more easily cut by the rotating cutter blades24.

As described previously, the cutting surface76, may, in some embodiments, extend generally along the entire leading edge60of the cutting section72. As such, and as shown inFIG. 12, the cutting surface may have a length “CsL” may be between 6 to 10 inches, between 7 to 9 inches, or about 8.25 inches. In additional embodiments, however, a portion of the cutting surface76may extend along at least a portion of the leading edge60of the connecting surface74. As such, some embodiments may provide for the cutting surface76to have a longer length. The cutting surface76may be formed to include a sharp edge so as to facilitate cutting of vegetation. For example, as illustrated inFIG. 11, the cutting surface76may be formed to include a cutting angle θ1 (defined between the lower surface66and the upper surface64) of between 15 and 23 degrees, between 17 and 21 degrees, or about 19 degrees. In addition, the cutting surface76may be formed to include an angle of attack82(defined between the lower surface66of the cutting section72and horizontal plane82) of between 10 and 30 degrees, between 15 and 25 degrees, about 15 degrees, or about 20 degrees.

Given the dimensions described above, the cutter blade24of the present invention can be formed with a center of gravity that is higher than previously-used cutter blades for rotary cutters. In some specific embodiments, such as shown inFIG. 11, the center of gravity84may be positioned no lower than (i.e., even with or located above) horizontal plane82, which bisects height H of the cutter blade24. In some embodiments, the center of gravity84may be positioned between 0.0 to 0.75 inches, between 0.0 and 0.5 inches, or between 0.0 and 0.25 inches above the horizontal plane80bisecting a height H of the cutter blade24. As such, the center of gravity84of the cutter blade of the present invention may be positioned between 0.0*H to 0.25*H, between 0.0*H to 0.15*H, or between 0.0*H and 0.10*H above the horizontal plane82bisecting a height H of the cutter blade24.

Given the relatively high center of gravity of the cutter blade24of embodiments of the present invention, the cutter blade24is restricted from raising into engagement with the blade carrier22and/or the deck12of the rotary cutter when the blade assembly20is caused to rotate. Specifically, even under a significant impulse force, such as caused from the rotary power provided by the PTO of the tractor, the cutter blade24of the present invention will not raise significantly into engagement with the blade carrier22or the deck12, thereby alleviating such above-described issues associated with the cutter blade24becoming locked in a skewed orientation. As such, the cutter blade24of the present invention also reduces unwanted vibration that can result from cutter blades becoming locked in such skewed orientations.

Embodiments of the present invention may also be directed to an additional cutter blade90, as illustrated inFIG. 13, which includes a center of gravity that is generally higher than the centers of gravity included in previously-used cutter blades for rotary cutters. The cutter blade90of the present invention may be formed from various types of material with high strength and high durability, such as5160or5160H heat treated steel. In more detail, as shown inFIG. 13, the cutter blade90of the present invention broadly comprises a longitudinally-extending blade with proximal end38, distal end39, leading edge60, back edge62, upper surface64, and lower surface66. The proximal and distal ends38,39are separated by a length of the cutter blade90and extend along a width of the cutter blade90. The leading and back edges60,62are separated by the width of the cutter blade90and extend along the length of the cutter blade90. The upper and lower surfaces64,66are separated by a thickness of the cutter blade90and extend between the length and the width of the cutter blade90.

In more detail, and remaining withFIG. 13, the cutter blade90may be comprised of three primary sections, including base section70, cutting section72, and connecting section74that transitions between and connects the base section70and the cutting section72. The base section70may extend from the proximal end38of the cutter blade90to the connecting section74. The base section70may include a through-hole75or an opening by which the cutter blade90is securable to the blade carrier22via the blade pin26, as was previously discussed. The connecting section74may extend at a downward angle from the base section70to the cutting section72. The cutting section72may extend from the connecting section74to the distal end39of the cutter blade90. The cutting section72may be shaped in the form of an airfoil that extends upward from the leading edge60to the back edge62. The cutting section72may generally include a cutting surface76, which extends along the leading edge60of the cutter blade90. The cutting surface76may be sharpened to perform the cutting action of the cutter blade90. In some embodiments, the cutting surface76may be milled, while in other embodiments, the cutting surface76may be formed by compressing the metal of the cutter blade90when it is in a malleable form. In some embodiments, the cutting surface76may extend along the entire length of the cutting section72. In some embodiments, the cutting surface76may also extend along at least a portion of the connecting section72.

In some embodiments, the cutter blade90, formed according to embodiments of the present invention, may be configured as a “vertically-offset blade.” As used herein, the term “vertically-offset blade” is defined to mean that (with reference toFIG. 14) a horizontal plane92that bisects a height “Hcs” of the cutting section72is positioned at least 0.15*Hcs, at least 0.20*Hcs, or at least 0.25*Hcs below a horizontal plane94that bisects a thickness “Tbs” of the base section70. In general, such vertically-offset blades may include cutter blades in which the distal ends39of the cutter blades are positioned lower than the proximal ends38of the cutter blades.

Nevertheless, to facilitate a generally high center of gravity, the cutter blade90may be formed with the following dimensions, measurements and/or measurement ranges. As shown inFIG. 14, a length “L” of the cutter blade (as measured from a center of the through-hole75of the base section70to the distal end39of the cutter blade90) may be between 5 to 30 inches, between 10 and 25 inches, between 15 and 20 inches, or about 18 inches. However, embodiments of the present invention may provide for the length L to be formed with other lengths as may be required for a specific cutting job or for use with a particular rotary cutter. With reference toFIG. 15, the cutter blade90may have a width “W” as measured from the back edge62to the leading edge60of between 2 to 6 inches, between 3 to 5 inches, or about 4 inches. The cutter blade90may have a thickness “T” as measured from the upper surface64and the lower surface66of between 0.1 to 2 inches, between 0.25 to 1 inches, or about 0.5 inches. The cutter blade90may have a depth “H,” measured as the maximum vertical distance between the upper surface64and the lower surface66of between 1 to 4 inches, between 2 to 3 inches, or about 2.5 inches.

Turning to the individual sections of the cutter blade90in more detail, and with reference toFIG. 16, the base section70may have a base length “BL” (as measured from the center of the through-hole75of the base section70to the connecting section74of the cutter blade90). With reference toFIG. 14, the base length BL may be illustrated approximately as L3. The base length BL may be between 5 to 10 inches, between 6 to 8 inches, or about 7.25 inches. In some embodiments, a ratio of the base length BL to the cutter blade90length L (i.e., BL:L) may be between 1:5 to 3:5, between 3:10 to 1:2, or about 2:5.

With reference toFIG. 16, the connecting section74may have a connecting length “CnL” (as measured from the base section70to the cutting section72). With reference toFIG. 14, the connecting length CnL may be illustrated approximately as the distance between L3and L5. The connecting length CnL may be between 3 to 7 inches, between 4 to 6 inches, or about 5 inches. In some embodiments, a ratio of the connecting length CnL to the cutter blade90length L (i.e., CnL:L) may be between 1:10 to 1:2, between 1:5 to 2:5, or about 3:10. As previously described, the connecting section74may be angled downwardly from the base section70to the cutting section72. In some embodiments, as illustrated inFIG. 14, the connecting section may be angle downwardly at an angle θ3 between 15 and 25 degrees, between 18 and 22 degrees, or about 20 degrees.

With reference toFIG. 16, the cutting section72may have a cutting length “CtL” (as measured from the connecting section74to the distal end39of the cutter blade90). As shown inFIG. 14, the cutting length CtL may be illustrated approximately as the distance between L5and L8. The cutting length CtL may be between 3 to 7 inches, between 4 to 6 inches, or about 5.5 inches. In some embodiments, a ratio of the cutting length CtL to the cutter blade90length L (i.e., CtL:L) may be between 1:10 to 1:2, between 1:5 to 2:5, or about 3:10.

In some embodiments, at least a portion of the cutter blade90may have a partial twist along part of its length L. For example, as illustrated inFIG. 13, the leading edge60of the connecting and cutting sections74,72may extend downward from the base section70at a steeper angle than the back edge62. As such, when viewing lateral cross sections of the cutter blade90, the depth of the cutter blade90(measured on the cross-section as the distance between a lowermost portion of the lower surface66and the upper most portion of the upper surface64) may be greater than the thickness of the cutter blade90. With reference toFIG. 15, the cutter blade may include the following depths “Dp” as measured at the following cross sections (with “L” being the cutter blade length as previously defined): Dp0=0.03*L (measured at the L0cross-section), Dp1=0.03*L (measured at the L1cross-section), Dp2=0.03*L (measured at the L2cross-section), Dp3=0.03*L (measured at the L3cross-section), Dp4=0.06*L (measured at the L4cross-section), Dp5=0.10*L (measured at the L5cross-section), Dp6=0.12*L (measured at the L6cross-section), Dp7=0.13*L (measured at the L7cross-section), and Dp8=0.14*L (measured at the L8cross-section). In some embodiments, the maximum depth Dp of the cutter blade90will be at least 0.08*L, at least 0.10*L, at least 0.12*L, at least 0.14*L, at least 0.16*L, at least 0.18*L, or at least 0.20*L. Furthermore, it is understood that the thickness T of the cutter blade90may be approximately 0.03*L. As such, the depths Dp may alternatively be defined as Dp0=T, Dp1=T, Dp2=T, Dp3=T, Dp4=2*T, Dp5=3.3*T, Dp6=4*T, Dp7=4.3*T, and Dp8=4.7*T.

The twist in the cutter blade90provides for the connecting section74and the cutting section72to include cutting section angle θ4, as measured from the leading edge60(which includes the cutting surface76) to the back edge62. In some embodiments, as shown inFIG. 15, a maximum value of the cutting section angle θ4 may be between 15 and 25 degrees, between 18 and 22 degrees, or about 20 degrees.

As described previously, the cutting surface76may extend generally along the entire leading edge60of the cutting section72. As such, and as shown inFIG. 16, the cutting surface76may have a length “CsL” of between 3 to 7 inches, between 4 to 6 inches, or about 5.5 inches. In addition, however, a portion of the cutting surface76may extend along at least a portion of the leading edge60of the connecting section74. As such, the cutting surface76may have a total length CsL of between 6 to 10 inches, between 7 to 9 inches, or about 8.4 inches.

Given the dimensions described above, the cutter blade90of the present invention can be formed with a center of gravity that is higher than previously used cutter blades. In some specific embodiments, such as shown inFIG. 15, the center of gravity96may be positioned between 0.1 to 0.75 inches, between 0.25 and 0.5 inches, or about 0.425 inches above a horizontal plane97that bisects a maximum height H of the cutter blade90(with such horizontal plane97also illustrated inFIG. 14). As such, the center of gravity96of the cutter blade90of the present invention may be positioned between 0.1*H to 0.25*H, between 0.15*H to 0.2*H, or about 0.17*H above the horizontal plane97that bisects the height H of the cutter blade90.

Given the relatively high center of gravity96of the cutter blade90of the present invention, the cutter blade90can be prevented from raising and locking with the blade carrier22or the deck12of the rotary cutter10when the cutting assembly is caused to rotate. Specifically, even under a significant impulse force, such as caused from the PTO of the tractor, the cutter blade90of the present invention will not raise significantly into engagement with the blade carrier22or the deck12, thereby alleviating issues associated with the cutter blade90becoming locked in a skewed orientation. As such, the cutter blade90of the present invention also reduces unwanted vibration that can result from previously-used cutter blades that may become locked in such skewed orientations.

Although the invention has been described with reference to the exemplary embodiments illustrated in the attached drawings, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims.