Patent Description:
For a given blade, the number of teeth per inch of length of a cutting edge, the "TPI," is fixed. The TPI along with gullet size, width and depth of the space between the teeth generally dictates the kinds of material that can be cut with the blade. The TPI of a blade also tends to dictate the range of workpiece sizes that can be cut with the blade. Blades with a low TPI generally deliver faster cuts with rougher edges and are ideal for cutting wood. A general rule of thumb is that a saw blade with more teeth results in a smoother cut and a saw blade with fewer teeth results in a faster cut. Other considerations impact the cut quality and the feed speed, such as how fast the material is fed into the saw blade and how fast the saw blade is turning.

<FIG> is a side view of a blade during a cutting process. A blade <NUM> includes at least one tooth <NUM>. The tooth <NUM> defines a tip <NUM> and a rake face <NUM>. The blade <NUM> is passing through a workpiece <NUM> to remove material from the workpiece <NUM>. The direction of movement of the blade <NUM> is referenced at <NUM>. A present outer surface of the workpiece <NUM> is referenced at <NUM> and a cutting depth is referenced at <NUM>. A surface that will be exposed after the cutting motion is referenced at <NUM>.

The present invention provides a band saw blade comprising the combination of features of appended independent claim <NUM> and a method of using such a band saw blade comprising the combination of features of appended independent claim <NUM>. Preferred embodiments of the invention are disclosed by the dependent claims.

Various aspects will become apparent to those skilled in the art from the following detailed description and the accompanying drawings.

The present disclosure provides a blade that can have a longer life. The present disclosure includes altering a standard blade to include a profile formed in a back edge of the blade. During passage of the blade through a workpiece, the portion of the blade that defines the profile can elastically deflect away from workpiece. In operation, the blade can rock back and forth in the cut, like a logger cuts wood. The deflection of the blade can be in response to the rise of a high stress sticking zone in the cut, helping the tips of the teeth of the blade to last longer.

Referring now to the drawings, there is illustrated in <FIG> a side view of the blade <NUM> during a cutting process in which the blade <NUM> is pulsated in and out of the cut. An exemplary path <NUM> of motion of the tip <NUM> is represented by solid-line portions and dashed-line portions. The exemplary path <NUM> reflects movement across the workpiece <NUM> (lateral or horizontal movement relative to the perspective of <FIG>) and feeding movement towards and away from the workpiece <NUM> (vertical movement relative to the perspective of <FIG>). The feeding movement and the lateral movement are orthogonal to one another. An exemplary solid-line portion of the path <NUM> is referenced at <NUM>. During the movement along the portion of the path <NUM> referenced by solid-line portions, the tooth <NUM> is engaged with the workpiece and removing material. An exemplary dashed-line portion of the path <NUM> is referenced at <NUM>. During the movement along the portion of the path <NUM> referenced by dashed-line portions, the tooth <NUM> is disengaged with the workpiece and not removing material. The exemplary path <NUM> thus defines a pulsating motion of the blade <NUM>, the motion having a frequency and an amplitude.

The path <NUM> is exemplary. Paths applied to the blade <NUM> in other embodiments of the present disclosure can be differently shaped. In one example, the blade <NUM> can be moved along a path appearing as a square-wave. When such a path is chosen, the tooth <NUM> can move linearly through part of the workpiece <NUM>, can be raised vertically away from the workpiece <NUM>, can move linearly over the workpiece <NUM>, and then be lowered vertically back into the workpiece <NUM>.

A bandsaw tool can be configured to move the blade <NUM> along the path <NUM>. In the prior art, a bandsaw is operated based on selecting the speed of the blade <NUM> and the feed rate. The speed of the blade <NUM> corresponds to movement of the blade <NUM> in a direction across the workpiece <NUM>. The feed rate corresponds to movement of the blade <NUM> into the workpiece <NUM>. For movement along the path <NUM>, a bandsaw can be configured to be operated based on selecting the speed of the blade <NUM>, the feed rate, a frequency, and an amplitude.

Referring now to <FIG>, an exemplary embodiment of the present disclosure provides a blade with a profile in a back edge of the blade. An exemplary blade 10a is a bandsaw blade. Only a portion of the blade 10a is shown. The blade 10a includes a body 11a that extends in an "endless ribbon," as that term is used in <CIT>.

A cutting edge 32a on a first side of the body 11a defines a plurality of cutting teeth configured to engage and remove material from the workpiece 18a during movement of the body 11a across the workpiece 18a in a cutting direction. The exemplary cutting edge 32a is substantially flat. The plurality of teeth includes the at least one tooth 12a that defines a tip 14a and a rake face 16a. The tooth 12a projects away from the front edge 32a of the blade 10a.

The exemplary blade 10a also includes a back edge 34a on a second side of the body 11a opposite of the first side and thus opposite to the front edge 32a. A length of the exemplary blade 10a can be defined along the edges 32a, 34a, along the endless ribbon, such as by an axis referenced at 36a. A height of the exemplary blade 10a can be defined perpendicular to the length, such as by an axis referenced at 38a. The height is defined as the distance between the tips 14a and the back edge 34a.

In the exemplary embodiment, the blade 10a includes a series of notches formed in the back edge 34a whereby the height varies along the length. The back edge 34a is otherwise flat. <FIG> shows a continuously arcuate notch 40a formed in the back edge 34a. The exemplary notch 40a does not include any planar/flat surface portions. The exemplary continuously arcuate notch 40a is defined by a radius of curvature, referenced at 42a. A "depth" of the continuously arcuate notch 40a at any location along the length 36a can be defined as the reduction or loss of the height 38a of the blade 10a from the maximum height 38a of the blade 10a. The maximum depth of a continuously arcuate notch in the back edge 34a can be less than or equal to about twice the tooth height in one or more embodiments of the present disclosure. In one or more embodiments of the present disclosure, the maximum depth can be chosen without reference to the tooth height. For example, in one or more embodiments of the present disclosure, the maximum depth can be less than one quarter of a millimetre (one hundredth of an inch).

The exemplary arcuate continuously arcuate notch 40a extends a width 45a between locations 44a and 46a of the back edge 34a. The exemplary locations 44a and 46a are separated from one another along the length of the blade 10a by the width 45a. The height of the exemplary blade 10a reduces along the length from the location 44a to approximately the location of the tooth 12a. The height of the exemplary blade 10a increases along the length from the tooth 12a to the location 46a.

<FIG> is front, planar view of a portion of the blade partially shown in <FIG>. The exemplary blade <NUM> includes a series of notches arranged in the back edge 34a in a repeating pattern. <FIG> is a view of the series and the series repeats, over and over, in the back edge 34a along the endless ribbon. The series of notches includes the first continuously arcuate notch 40a, a second continuously arcuate notch 140a, and a third continuously arcuate notch 240a. As set forth above, the first continuously arcuate notch 40a has the first radius of curvature 42a, the first width 45a along the back edge 34a, and extends into the back edge 34a a first depth 58a.

The second continuously arcuate notch 140a has a second radius of curvature 142a and a second width 145a along the back edge 34a. The second continuously arcuate notch 140a extends into the back edge 34a the first depth 58a. The exemplary second continuously arcuate notch 140a is adjacent to the first continuously arcuate notch 40a along the back edge 34a. The exemplary second continuously arcuate notch 140a is spaced a first distance 60a from the first continuously arcuate notch 40a along the back edge 34a.

The third continuously arcuate notch 240a has a third radius of curvature 242a and a third width 245a along the back edge 34a. The third continuously arcuate notch 240a extends into the back edge 34a the first depth 58a. The exemplary third continuously arcuate notch 240a is adjacent to the second continuously arcuate notch 140a along the back edge 34a. The exemplary third continuously arcuate notch 240a is spaced the first distance 60a from the second continuously arcuate notch 140a along the back edge 34a. The second continuously arcuate notch 140a thus is positioned between the first continuously arcuate notch 40a and the third continuously arcuate notch 240a along the back edge 34a. With respect to the perspective of <FIG>, another series begins, a distance equal to the first distance 60a, to the right of the third continuously arcuate notch 240a and another series ends, a distance equal to the first distance 60a, to the left of the first continuously arcuate notch 40a. This pattern continues along the full distance of the back edge 34a of the endless ribbon.

The first radius of curvature 42a and the second radius of curvature 142a and the third radius of curvature 242a are all different from one another. In an exemplary embodiment, the first radius of curvature 42a is <NUM> centimetres (<NUM> inches), the second radius of curvature 142a is <NUM> centimetres (<NUM> inches), and the third radius of curvature 242a is <NUM> centimetres (<NUM> inches). Thus, in such an embodiment, the smallest of the first radius of curvature 42a and the second radius of curvature 142a and the third radius of curvature 242a is at least two-thirds of the largest of the first radius of curvature 42a and the second radius of curvature 142a and the third radius of curvature 242a. Also, in such an embodiment, all of the first radius of curvature 42a and the second radius of curvature 142a and the third radius of curvature 242a are at least three hundred and thirty centimetres (one hundred and thirty inches) and all of the first radius of curvature 42a and the second radius of curvature 142a and the third radius of curvature 242a are less than five hundred and eight centimetres (two hundred inches). In an exemplary embodiment, the first depth is <NUM> millimetre (<NUM> inch). In such an embodiment, all of the first radius of curvature 42a and the second radius of curvature 142a and the third radius of curvature 242a can be at least four orders of magnitude greater than the first depth 58a. In an exemplary embodiment, all of the first width 45a and the second width 145a and the third width 245a can be between eight and ten centimetres (between three and four inches). For example, the first width 45a can be <NUM> centimetres (<NUM> inches) the second width 145a can be <NUM> centimetres (<NUM> inches), and the third width 245a can be <NUM> centimetres (<NUM> inches). In such an embodiment, the smallest of the first width 45a and the second width 145a and the third width 245a is at least three-quarters of the largest of the first width 45a and the second width 145a and the third width 245a. Also, in such an embodiment, all of the first width 45a and the second width 145a and the third width 245a are at least eight centimetres (three inches). In an exemplary embodiment, the first distance 60a is <NUM> centimetres (<NUM> inches). In such an embodiment, the first distance 60a is thus greater than all of the first width 45a and the second width 145a and the third width 245a. In an exemplary embodiment, the blade 10a has a blade height that is <NUM> centimetres (<NUM> inches). Embodiments of the present disclosure can include a blade having a blade height in the range of <NUM> centimetre to <NUM> centimetres (<NUM> inch to <NUM> inches). In an exemplary embodiment, the thickness of the blade 10a is <NUM> centimetres (<NUM> inch). The thickness is referenced at 74a in <FIG>. In an exemplary embodiment, the tooth height of teeth on the blade 10a can be around <NUM>. Embodiments of the present disclosure can include a blade having teeth with a tooth height in the range of <NUM> - <NUM>. In an exemplary embodiment, the height of teeth on the blade can vary along the length of the blade. For example, a first tooth can have a height of <NUM>, a second tooth immediately adjacent to and behind the first tooth in the cutting direction can have a height of <NUM>, a third tooth immediately adjacent to and behind the second tooth in the cutting direction can have a height of <NUM>, and so on if desired, in an exemplary sequence of a plurality of teeth having a <NUM> tooth variation. The blade can include a plurality of such sequences adjacent to one another such that the tallest tooth of a first sequence is immediately followed by the shortest tooth of the next sequence. Embodiments of the present disclosure can include a blade having teeth with a tooth height in the range of <NUM> - <NUM>. Embodiments of the present disclosure can include a blade having a thickness in the range of <NUM> - <NUM> centimetre (<NUM> - <NUM> inch).

Referring now to <FIG>, in a method of using the band saw blade 10a, the endless ribbon of the body 11a of the band saw blade 10a can be arranged around a driving wheel 62a and a driven wheel 64a of a band saw arrangement. The plurality of cutting teeth of the cutting edge 32a on the first side of the body 11a can be engaged with a workpiece 18a. The driving wheel 62a can be rotated to move the body 11a across the workpiece 18a in a cutting direction 20a and thereby remove material from the workpiece 18a.

Rollers 66a, 68a, each having a radius of curvature, can support the back edge 34a on the second side of the body 11a opposite of the first side. <FIG> is an isometric and detail view of the roller 66a schematically in <FIG>, with the axis of rotation of the roller 66a referenced at 72a. The exemplary rollers 66a, 68a ride in the series of notches 42a, 142a, 242a formed in the back edge 34a as the body 11a moves. The exemplary rollers 66a, 68a ride into and out of the first continuously arcuate notch 40a and the second continuously arcuate notch 140a and the third continuously arcuate notch 240a during movement of the blade 10a. Both of the rollers 66a, 68a can have respective radii of curvature that are less than all of the first radius of curvature 42a and the second radius of curvature 142a and the third radius of curvature 242a, so that the rollers 66a, 68a are fully received in the notches 40a, 140a, 240a.

The band saw blade 10a can be fed through the workpiece 18a at a continuously positive feed rate in a feeding direction. The feeding direction is referenced at 70a in <FIG> and is orthogonal to the movement 20a across the workpiece 18a. The feeding direction is into the page relative to <FIG>. The exemplary feed rate is continuously positive in that the blade 10a is not oscillated between the direction 70a and a direction opposite to the direction 70a.

The axis 72a of rotation of the roller 66a can be maintained a predetermined distance away from a plane containing the back edge 34a. The notches 40a, 140a, 240a extend away from this plane. This predetermined distance can be equal to the radius of curvature of the roller 66a. Thus, when the roller 66a and the back edge 34a are aligned, the roller 66a contacts the back edge 34a and supports the back edge 34a and prevents movement of the body 11a of the blade 10a away from the workpiece 18a. When the roller 66a and respective portions of the body 11a at the first continuously arcuate notch 40a and the second continuously arcuate notch 140a and the third continuously arcuate notch 240a are aligned, the body 11a of the blade 10a is permitted to elastically deflect away from the workpiece 18a.

When the roller 66a and the first continuously arcuate notch 40a are aligned with one another, the body 11a of the blade 10a is permitted to elastically deflect away from the workpiece 18a as the roller 66a maintains contact with the first continuously arcuate notch 40a and controls the extent of elastic deflection. When the roller 66a and the second continuously arcuate notch 140a are aligned with one another, the body 11a of the blade 10a is permitted to elastically deflect away from the workpiece 18a as the roller 66a maintains contact with the second continuously arcuate notch 140a and controls the extent of elastic deflection. When the roller 66a and the third continuously arcuate notch 240a are aligned with one another, the body 11a of the blade 10a is permitted to elastically deflect away from the workpiece 18a as the roller 66a maintains contact with the third continuously arcuate notch 240a and controls the extent of elastic deflection.

Because the notches 40a, 140a, 240a have different radii of curvature, the rate of deflection of the body 11a is different as the roller 66a aligns with the different notches 40a, 140a, 240a. However, in the exemplary embodiment, the first depth 58a is the same and thus the extent of deflection of the body 11a is the same at all of the notches 40a, 140a, 240a. Also, because the notches 40a, 140a, 240a are continuously arcuate, the deflections do not include abrupt periods, such as would occur if any of the notches 40a, 140a, 240a had a straight portion extending parallel to the direction 70a. Such abrupt deflections would elevate stress levels in the body 11a and the roller 66a.

Referring now to <FIG>, in a cutting operation with the blade 10a, the blade 10a is passing through the workpiece 18a to remove material from the workpiece 18a. A present outer surface 22a of the workpiece 18a will be removed to the cutting depth 24a to expose the surface 26a. It is noted that <FIG> and line 26a is illustrative and not drawn to scale.

An exemplary path 27a is illustrative relative cutting depths occurring due to motion of the body 11a and the tips of the blade teeth when the blade 10a elastically deforms. The distance between the line 22a and the path/line 27a/26a represents the depth of cut. The lowest points along the line 26a, such as points 48a and 50a, represent the cut created by teeth that are not adjacent to one of notches 40a, 140a, 240a along the back edge 34a, such as tooth 52a in <FIG>. This cut is the deepest cut. The highest points along the line 26a, such as points 54a and 56a, represent the cut created by teeth that are adjacent to the lowest point of notches 40a, 140a, 240a along the back edge 34a, such as tooth 12a in <FIG>. This cut is the shallowest cut. The points along the line 26a between a lowest point and a highest point represent cuts created by teeth that are between the tooth 12a and a tooth 112a and that are between the tooth 12a and a tooth 212a in <FIG>. The teeth 112a, 212a are at opposite ends of the notch 40a.

During movement of the blade 10a, the portions of the blade 10a that include one of the notches 40a, 140a, 240a will be slightly deflected elastically away from the workpiece 18a. Teeth adjacent to one of the notches 40a, 140a, 240a will be urged away from the cut. However, as illustrated in <FIG>, these teeth will not be separated from the cut and will continue to remove material from the workpiece 18a. Rather, the depth of the cut will reduce slightly. The teeth adjacent to one of the notches 40a, 140a, 240a will remain engaged with the workpiece 18a and will be removing material. The instantaneous depth of cut is thus varying. This reduces notch wear and the high temperature point, thereby increasing tool-life. The blade 10a acts like a quasi-vibrational-assisted tool and the sticking (or high stress) zone is reduced, helping the tool-tip to last longer. It can be desirable to apply a higher feed when using the blade 10a to keep the teeth in the cut. The blade 10a will also tend to rock back and forth in the cut like a logger cutting wood. Compared to straight back-edge, the blade 10a reduces the cross section of the cut at any given instance, thus momentarily reducing chip loads.

The teachings of the present disclosure increases blade-life when implemented. For the blade 10a, the typical break-in process in which the initial feed rate is relatively slow is not recommended, since it may cause the teeth to leave the cut. A higher feed is recommended to keep the teeth in cut. It is noted that the attributes of a profile can be based on the number of teeth per inch of the blade and also on the qualities of the material being cut.

Details of testing of exemplary embodiments of the present disclosure against non-embodiments (blades having a fully flat back edge) are set forth below.

In the testing that produced the results set forth in Table <NUM>, a blade being an embodiment of the present disclosure was tested against a blade with a straight/flat back edge. The designation "# Cut" refers to the number of workpieces that were cut before the respective blade failed. A blade failure was defined when the respective blade lost a tooth. The non-embodiment blade, for example, failed after three (<NUM>) workpieces were cut while the embodiment blade cut through nine (<NUM>) workpieces. All of the workpieces in these tests were round in cross-section. The designation "Area" refers to the total square area cut by the respective blade, in square inches, before the respective blade failed. The designation "Feed" refers to feed rate. During testing, the instantaneous condition of the respective blade was monitored and the feed rate was maximized to the extent possible in view of the instantaneous condition of the respective blade. The blade speed was the same for both blades during cutting of NO6625 workpieces. As shown in Table <NUM>, the embodiment blade cut <NUM>% more area than the non-embodiment blade and permitted a greater feed rate than the non-embodiment blade.

In the testing that produced the results set forth in Table <NUM>, a blade being an embodiment of the present disclosure was tested against a blade with a straight/flat back edge. All of the workpieces were round in cross-section. During testing, the instantaneous condition of the respective blade was monitored and the feed rate was maximized to the extent possible in view of the instantaneous condition of the respective blade. The blade speed was the same for both blades during cutting of K3403 (<NUM> Brinell) workpieces. As shown in Table <NUM>, the embodiment blade cut <NUM>% more area than the non-embodiment blade and permitted a greater feed rate than the non-embodiment blade.

In the testing that produced the results that are set forth in Table <NUM>, a blade being an embodiment of the present disclosure was tested against a blade with a straight/flat back edge. All of the workpieces were round in cross-section. During testing, the instantaneous condition of the respective blade was monitored and the feed rate was maximized to the extent possible in view of the instantaneous condition of the respective blade. The blade speed was the same for both blades during cutting of <NUM> workpieces. As shown in Table <NUM>, the embodiment blade permitted a greater feed rate than the non-embodiment blade and, based on the size of the workpieces, the greater feed rate resulted in a time savings of seventy-one minutes for each workpiece. Cutting a workpiece by the embodiment blade took seventy-one minutes less than cutting a workpiece by the non-embodiment blade.

In the testing that produced the results that are set forth in Table <NUM>, a blade being an embodiment of the present disclosure was tested against a blade with a straight/flat back edge. All of the workpieces were rectangular in cross-section. During testing, the instantaneous condition of the respective blade was monitored and the feed rate was maximized to the extent possible in view of the instantaneous condition of the respective blade. The blade speed was the same for both blades during cutting of NO5500 workpieces. As shown in Table <NUM>, the embodiment blade cut <NUM>% more area than the non-embodiment blade and permitted a greater feed rate than the non-embodiment blade.

Claim 1:
A band saw blade (10a) comprising:
a body (11a) extending in an endless ribbon;
a cutting edge (32a) on a first side of said body, said cutting edge defining a plurality of cutting teeth (12a) configured to engage and remove material from a workpiece during movement of said body across the workpiece in a cutting direction, said plurality of teeth including at least one sequence of teeth having a variable height with a tooth height variation defined by a difference in height between a height of a tallest tooth of said sequence and a height of a shortest tooth of said sequence;
a back edge (34a) on a second side of said body opposite of said first side;
a series of notches formed in said back edge, said back edge otherwise flat, said series arranged in said back edge in a repeating pattern, and said series of notches having:
a first continuously arcuate notch (40a) having a first radius of curvature (42a) and a first width (45a) along said back edge and extending into said back edge a first depth (58a);
a second continuously arcuate notch (140a) having a second radius of curvature (142a) and a second width (145a) along said back edge and extending into said back edge said first depth (58a), said second continuously arcuate notch adjacent to said first continuously arcuate notch along said back edge and spaced a first distance (60a) from said first continuously arcuate notch along said back edge; and
a third continuously arcuate notch (240a) having a third radius of curvature (242a) and a third width (245a) along said back edge and extending into said back edge said first depth (58a), said third continuously arcuate notch adjacent to said second continuously arcuate notch along said back edge and spaced said first distance (60a) from said second continuously arcuate notch along said back edge, said second continuously arcuate notch thus positioned between said first continuously arcuate notch and said third continuously arcuate notch along said back edge; and
characterized in that said first radius of curvature (42a) and said second radius of curvature (142a) and said third radius of curvature (242a) are all different from one another.