BROADHEAD WITH SINGLE BEVEL BLADES ALIGNED EDGE TO CENTER

Abstract

A chisel like cut-on-contact broadhead with at least three single bevel blades aligned ‘edge-to-center’. The fixed broadhead allow single bevel cutting edges to continuously extend from the rearmost radial point to the foremost tip of the broadhead; forming a cut-on-contact point for improved three blade penetration. The ‘edge-to-center’ design where all blade edges align with the longitudinal axis prevent abundant rotation and unnecessary air resistant upon the body of the broadhead during both flight and impact. The right or obtuse angle where the enneagon ferrule and blade intersect provides faster manufacturing while still retaining a smooth polygon shaped ferrule.

Description

REFERENCE

U.S. Patent No. 20070243959A1 Louis Grace

U.S. Pat. No. 4,210,330A John V. Kosbab

U.S. Patent No. 20040138016A1 Todd A. Kuhn

U.S. Patent No. 20130203530A1 Stephan C. Patton

U.S. Pat. No. 9,157,710B1 Shane Darin Huntsman

U.S. Pat. No. 4,616,835A George H. Trotter

BACKGROUND

This invention relates to archery arrowheads. More particular broadheads used for hunting. There are several different groups of broadheads where hunting broadheads can be categorized in. Usually inventors aim for increased hemorrhage effect, maximizing penetration and/or for structural integrity while still keeping good flight capability. One trait often replace another. Further on the type of bevel on the blade provide two other classes; single bevel or double bevel. The class of single bevel broadheads present great penetration and are often structurally reliable. But they can fall behind other groups of broadheads when comparing hemorrhage effect.

Single bevel broadheads create a slight rotation from existing air resistance without creating more drag. No extra drag is added since the broadhead has a straight edge-to-center alignment with a lean profile, later described in more detail. The slight rotation from the single bevel means that smaller, straighter fletching can be used at the rear of the arrow which also reduces drag and increase speed. Opposite effect may occur with offset blades which create unnecessary rotation and extra drag. This phenomenon is comparable to autorotation; the offset blades and abundant spinning of the broadhead blades act like a parachute, increasing drag and decreasing speed. More drag at the front of the arrow also means bigger fletching at the rear is needed to keep the flight stable which in turn also slows the arrow down. Offset blades gives a slower arrow and less penetration. The main reason for the single bevel may be for the penetrating capability on hard tissues; bones, sinew and/or tough skin. When a double bevel broadhead hit a hard surface the energy is gonna try to push the broadhead back into the arrow-shaft until it, most likely, breaks. A broken arrow-shaft is not good since the energy has been lost.

With a single bevel broadhead the forces instead pushes on each unidirectional bevel creating rotation. Instead of forces destroying the arrow; we use the waste energy for rotation until the hard tissue is penetrated. We don't want unnecessary rotation from offset blades, just enough rotation from the single bevel blades to break the tissue, the rest of the energy should continue in a forward motion through the game.

To increase the hemorrhage effect on a single bevel broadheads the blades need a bigger cutting circumference. This stepping stone might be reached by increasing the width of the cutting blades. Another alternative to achieve this goal is to increase the number of cutting blades to more than two; which is most occurring with double bevels. This needs to be done without replacing any of the beneficial traits. Penetration is, among other things, benefited by; cut-on-contact points, aligned and smooth transitioning ferrules, non-offset design and structural reliability; a broken blade can't cut nor penetrate sufficiently. To obtain increased hemorrhage while keeping the capabilities mention above a device comprised of three or more single bevel blades aligned edge-to-center is in demand.

On a double bevel broadhead the cutting edge of the blade is located on the blades middle plane. Following the center-line of the blade it aligns with the longitude center axis of the ferrule. The edge is aligned to the center; edge-to-center. U.S. Patent No. 20070243959A1 FIG. 6 show a double bevel blade edge 44 which is in alignment with the longitude axis A FIG. 3.

On a single bevel broadhead the edge of the bevel is located on the underside of the blade. For a single bevel blade to keep the edge-to-center alignment the underside of the blade needs to be aligned radially to the longitude axis of the ferrule. All existing embodiment of edge-to-center designed broadheads are consisting of double bevel blades.

The opposite of edge-to-center is offset blades. Meaning that the blades are orientated off-center to the longitude axis. This can be done in many variations. John V. Kosbab U.S. Pat. No. 4,210,330A showcase a straight off-set design with replaceable blades, most prone in FIG V where blade 40 is offset from the longitude axis. A pitch variant is showcased by Todd. U.S. Patent No. 20040138016A1 FIG. 3 where a curved blade 110 has an airfoil 604. Stephans broadhead in U.S. Patent No. 20130203530A1 has a tangent blade offset 16, 18 which tapers with the ferrule 33 body. Straight, tapered and pitched are some variations of off-center design.

A problem with three blade broadheads is to achieve sharp edges combined with a cut-on-contact point. A profile of an evenly distributed three bladed broadhead forms a triangle with 60 degree corners. 60 degree is a crude cutting angle for a blade. A meat cleaver often have a 40 degree bevel and a kitchen knife often have a 25 degree bevel. A broadhead with 60 degree bevels have poor cutting ability. Broadhead blades with sharper than 60 degree bevels can't easily join the blades together at the point. One way to overcome the 60 degree bevel limitation is to use replaceable blades and a tip consisting of a cone which can come in different shapes, but it's a compromise to penetration and durability. A cone doesn't have any cutting ability. Instead it pushes the tissues to the side, expanding a hole until the blades come in contact and start cutting.

This is loss of energy. John V. Kosbab U.S. Pat. No. 4,210,330A demonstrates different cones in FIG XIX-XXVI. Another examples to increase hemorrhage effect is to create an offset, though this might increase drag.

Solutions for increasing hemorrhage of a single bevel broadhead vary, but are few. An embodiment are Shane U.S. Pat. No. 9,157,710B1 who configured the blades in a “Z” shape; a straight offset that increase the cutting circumference. George U.S. Pat. No. 4,616,835A stacked the blades in front of each other creating four cutting blades with single bevels.

Milling as manufacturing process may be time consuming but offer great structural reliability. Many tool-passes is needed to obtain a smooth circular surface on a ferrule; increasing cost of each product. Ball-mill tools takes smaller cuts then a square-mill tool, but it's needed to get a smooth ferrule. Changing between spindles and/or fixtures may cause misalignment. Offsetting blades creates areas unreachable by simple milling tools. These are a few problems that needs to be overcome.

SUMMARY

Penetration, cutting circumference and structural reliability are key features to what makes a projectile lethal. This broadhead contributes to a new group of broadheads with solutions to problems above-described while still keeping good flight capability.

In the illustrated embodiment; the broadhead has single bevel cutting edges with at least three blades oriented edge-to-center. The cut-on-contact point has blades of its own that correspond with the cutting edges of each blade. Each blade is beveled with single edges oriented circularly unidirectional with each other. The ferrule has a polygon profile shape and stretch along the longitude axle from the shoulder to the cut-on-contact point. As it stretch forward it tapers in a straight fashion. Each side of the ferrule that intersect with a blade consists of a right or obtuse angle between said planes. To the rearmost part of the ferrule is a cylinder with a diameter corresponding with the polygon ferrule; entitled shoulder, this is the ferrule rearward end. Behind the shoulder is a reduction in diameter; another cylinder for creating stability if inserted in a projectile carrying system. Followed by yet another reduced cylinder with treads; the insert portion of the body may be threaded into an arrow shaft.

In the illustrated embodiment; the broadhead provides a sharper than 60 degree cutting bevel without loosing the cut-on-contact point, without using removable blades and without creating an offset. This is achieved by using single bevel edge-to-center alignment. The broadhead cutting edges may be sharpened to 25 degree bevel. The straight edge-to-center design gives greater speed and deeper penetration.

The solution to time consuming milling manufacturing is a polygon ferrule profile. The device is designed with a right or obtuse angle intersecting between the enneagon ferrule and blade which allow a square end mill tool to reach all planes using indexing, without leaving any uncut surfaces. The 90 degree angle between blade and ferrule plane extends all the way from the shoulder to the tip. That angle is consistent since the blade is aligned edge-to-center. Allowing the cut-on-contact point to coexist with more than two substantially sharp single bevel cutting blades.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 Perspective front view of the broadhead.

FIG. 2 Perspective rearward view of the broadhead.

FIG. 3 Rearward view of the broadhead with the edge-to-center illustrated with radial line B.

FIG. 4 Front view of the broadhead.

FIG. 5 Side view of the broadhead with cross-section and longitude axle illustration with line A.

FIG. 6 Side view of broadhead and longitude axle illustration with line A.

FIG. 7a-b Illustration of backside taper; forward and barbed.

FIG. 8 Illustration of a backside bevel.

FIG. 9a-c Illustrated embodiment of blades with serrated edges.

FIG. 10a-b Further embodiment of the broadhead with two different blade tapers.

FIG. 11 Another embodiment with an open hollow core in the ferrule, an additional wooden shaft is also included.

FIG. 12 Yet Another embodiment of the broadhead with four blades.

FIG. 13a-d A method of mill-turning manufacturing, mill tool marked as C, rearward view of the broadhead.

DETAILED DESCRIPTION OF THE DRAWINGS

An arrowhead, described as broadhead, in accordance with the embodiment illustrated in FIGS. 1-10 and 12, is described as followed: A solid one-piece construction divided into areas of point 6, ferrule 21, insert 22 and blade 20. Description of each area is described in following text.

The point 6 have multiple cutting edges 4 stretching from intersecting point 3 to the tip 5 forming a cut-on-contact point 6. The number of cutting edges may vary upon application. The number of blades 20 will be the same as the number of cutting edges 4. In the illustrated embodiment FIG. 1-11 the broadhead has three blades 20 and three cutting edges 4. With the illustrated embodiment in FIG. 12 there are four blades 20 and four cutting edges 4. Each cut-on-contact blade 4 is oriented edge-to-center. Meaning that blade edge 4 and the blade 20 underside 2 is aligned in a radial position to the longitude axle A. The edge is aligned with the center-line; edge-to-center. This is illustrated in FIG. 3 with radial line B. Edge 4 and 1 is one continues cutting edge starting at the rearmost radial point 14, stretching forward through intersecting point 3, to the tip 5. Intersecting point 8 and 3 defines the ferrules 21 front end and it's where the cut-on-contact point 6 starts. The point 6 have a steeper or equal angle between the cutting edge 4 and the longitude axle A than the angle between edge 1 and the longitude axle A; this is to reduce the overall length of the broadhead and increase the durability of the point 6. The tapered angle of the point 6 may variate between 25-40 degree. The bevel of the cut-on-contact point may vary between 25-40 degree. Variations occur to get a good balance between durability and penetration.

The ferrule 21 plane 18 is angled 90 degree to the underside 2 of a blade 20. The 90 degree angle can especially be seen in FIGS. 3 and 4. The ferrule plane 18 stretches from the shoulder 15, pass the ferrule front end 8 all the way to the tip 5, keeping the 90 degree angle all the way to the tip 5. This allows for easier manufacturing, the designed advantage of manufacturing process is described in later description. In the illustrated embodiment plane 18 is a longitude intersecting portion for blade 20; the portion of the ferrule where the blade is attached to, seen in FIG. 3. Plane 12 of the ferrule 21 is at an obtuse angle to the over-side 11 of the blade 20. This allows machining tools to pass without obstruction. Between plane 12 and 18 is plane 13; connecting the two planes 12 and 18 together. Plane 12, 13 and 18 comprises a third of the total nine sides on the polygon shaped ferrule 21. The shape and angles of the three planes 12, 13 and 18 of ferrule 21 repeats itself between each blade 20. For FIG. 1-11 the shape and angles repeat itself three times. For FIG. 12 the shape and angles repeat itself four times. The ferrule planes 12 and 13 stretches from shoulder 15 to the ferrule front end 8.

In the illustrated embodiment FIG. 2, the ferrule 21 start at the ferrule rearward end as a substantially thin cylindrical shoulder 15 and transits forward into a polygon profile with nine sides, an enneagon. The diameter of the shoulder correspond with the diameter of the polygon profile. The shoulder and polygon planes 12, 13 and 18 make up the ferrule 21. The ferrule 21 is centered symmetrically around the longitude axle A.

The insert 22 comprises of two cylinders 16 and 17. Connected to that ferrule rearward end is cylinder 17 with a reduced diameter compared to the shoulder 15. This cylinder is meant to increase stability if the broadhead is inserted into a broadhead carrying system. Furthest back of cylinder 17 there is a small bevel before the diameter reduces yet again into another cylindrical portion 16. Cylinder 16 have threads that are meant to attach in a broadhead carrying system. The threads pitch and size may vary upon the broadhead carrying system. Furthest back of cylinder 16 is a slight bevel before it cuts off. The insert may be inserted in an arrow-shaft or other carrying systems such systems might be a bolt, spear, handle, dart or harpoon. Cylinder 17 and 16 is centered around longitude axle A.

In the illustrated embodiment FIG. 1-11, the blades are located 120 degree from each other, circulating the longitude axle A. In the illustrated embodiment FIG. 12, the blades are located 90 degree from each other, circulating the longitude axle A. The blades are attached through the longitude intersecting portions which tapers along the longitude face of the ferrule, in the embodiment shown in FIG. 1-11 the longitude intersecting portions is located on plane 18, can be seen most clearly in FIG. 3. Each blade is oriented edge-to-center. Meaning that edge 1 and the blade 20 underside 2 is aligned in a radial position to the longitude axle A. The edge is aligned with the center line; edge-to-center. This is illustrated in FIG. 3 with radial line B. The underside 2 of blade 20 stretches all the way from the shoulder 15 to the tip 5, seen in FIGS. 4 and 5. This makes for easier machining and easier blade sharpening, manufacturing process is described in later description. The over-side 11 of blade 20 stretches from the shoulder 15 to the ferrule front end 8 where the cut-on-contact point starts. The backside 19 FIG. 2 of each blade connect to the shoulder 15. The most radial point of the broadhead is point 14 at the rearmost part of the blade external edge. The shape of the blades resembles a triangle.

Blade 20 has one single bevel 9 per blade. The edge 1 is on the external side of the blade. Each bevel 9 are circularly unidirectional with the corresponding bevels 9 on the other blades 20. The angle of bevel 9 may vary upon application. The taper between edge 1 and the longitude axle A may also variate upon application to create product groups with different attributes of durability and penetration. Illustration of variations is seen in FIG. 10a-b. FIG. 10a has a smaller tapered angle between edge 1 and the longitude axle A, making it longer and giving it attributes such as greater penetration. FIG. 10b has a larger tapered angle between edge 1 and the longitude axle A, making it shorter and giving it attributes such as greater durability. Embodiment with different tapers of edge 1 and the longitude axle A still keeps the spirit of the broadhead.

The ferrule 21 polygon profile has a plurality of sides. The amount of sides and angle between each side of the polygon profile may variate upon the favored manufacturing method where reach-ability of a milling tools is a key feature in design choice. In FIG. 1-11 the enneagon is the preferred profile shape of the ferrule for a three blade embodiment. In FIG. 12 the amount of sides and angle between said sides is adjusted for reach-ability of manufacturing tools, where the space between four blades are smaller than the space between three blades.

The following embodiment still keeps the spirit of the broadhead and the distinctive features such as; single bevel, edge-to-center alignment, cut-on-contact point and the polygon profiled ferrule. The minor alterations doesn't depart from the spirit of the broadhead, such alternations are described hence-forth in order of ferrule, blade, cutting edge and taper.

The shoulder of the ferrule creates a flat surface for a projectile carrying system to transfer load onto. In one embodiment the ferrule shoulder 15 has a polygon shaped profile instead of a cylinder, eliminating the cylinder portion of the ferrule 21, still keeping the flat surface for load transfer.

In another embodiment the polygon profile of the ferrule 21 stretches forward to the ferrule front end 8 and tip 5 in a curved fashion instead of a straight fashion. This curve may be parabolic, hyperbolic, ellipse or circular. Curved alternations might increase speed or penetration.

The angle between the blade 20 and ferrule 21 is a key feature where reach-ability of a milling tools is of importance in design choice. In one embodiment, both the over-side 11 and the underside 2 of the blade 20 is at a right angle toward the polygon profiled ferrule 21. In another embodiment, both the over-side 11 and the underside 2 of the blade 20 is at an obtuse angle toward the polygon profiled ferrule 21. In yet another embodiment, the over-side 11 and the underside 2 of the blade 20 is at alternating obtuse and right angles toward the polygon profiled ferrule.

In further embodiment the blades are plurality spread out in a circular fashion around the longitude axle A in an edge-to-center orientation. One of such embodiment can be seen in FIG. 12 where the broadhead has four blades 20 instead of three.

In one embodiment, the cutting edge 1 is connected to the cut-on-contact edge 4 through point 3 in a curved manner. This curve may be parabolic, hyperbolic, ellipse or circular. In another embodiment both edge 1 and 4 are curved as well; individually or both. Such a curve may increase cutting performance. In yet another embodiment the cutting edges 1 and 4 are serrated; it may consist of circular notches 25, triangle notches 26 or saw-tooth shapes 27 seen in the examples in FIG. 9a-c. Other variations and combinations of serration may exist. Serration and curves can be combined.

In one embodiment the angle of the backside 19 toward the longitude axle A may be tapered forward or backwards, illustrated in FIG. 7a-b. FIG. 7a illustrates a forward tapered backside 19, an angle forward increase the length and weight of the broadhead. In FIG. 7b the backside 19 may be angled backward creating a barbed rearward tapered backside, decreasing overall length and weight. In yet another embodiment the backside 19 FIG. 8 can be beveled at an angle to create a single bevel cutting edge for increased hemorrhage effect. It may also be used as means to reduce weight. With a rearward 19 bevel, cutting edge 4 and 1 extend further back around the rearward radial point 14 to the back-side 19 stopping at the shoulder 15, creating a longer cutting edge, seen in FIG. 8. The angle of the beveled surface 19 can also be seen in the four bladed embodiment in FIG. 12.

In one embodiment the broadhead, in accordance with the illustrations in FIGS. 1-10 and 12, is described as followed: A molded one-piece broadhead manufactured in plastic, rubber or metal divided into areas of ferrule 21, blade 20, insert 22 and point 6. The molded embodiment may use a circular profiled ferrule 21 instead of a polygon shape, since machining reach-ability isn't a key-feature in design for the molding process. Different embodiment of the molded embodiment may occur just as for the one-piece machined embodiment described previously, such as; serration, barbed, rearward cutting edge, curved edge, curved ferrule front end intersection, plurality blades, different bevel angle, different taper and similar features. In combination or by themselves while still keeping the spirit of the broadhead.

In one embodiment the broadhead, in accordance with the illustration in FIG. 11, is described as followed: A molded one-piece broadhead manufactured in metal, rubber or plastic divided into areas of ferrule 21, blade 20 and point 6. The molded embodiment may use a circular profiled ferrule 21 instead of a polygon shape, since machining reach-ability isn't a key-feature in design for the molding process. In said embodiment an open hollow core 24 exist in the ferrule 21 shown in FIG. 11. The open hollow core 24 introduce a hole on the shoulder 15 surface. The hole tapers forward inside the ferrule creating a hollow ferrule 21. Said hollow core can receive a shaft 23. Such shaft 23 may be made out of wood. The taper of the open hollow core 24 correspond with the taper of the shaft 23. An insert can also be inserted in the hollow core 24 and later attached to a shaft. Such insert may be made out of metal and may have threads. The metal insert increase weight of the plastic or rubber molded broadhead for a less expensive way of manufacture while still keeping the weight of a full metal broadhead. Different embodiment of the molded embodiment may occur just as for the one-piece machined embodiment described previously above, such as; serration, barbed, rearward cutting edge, curved edge, curved ferrule front end intersection, plurality-blades, different edge bevel, different taper and similar features. In combination or by themselves while still keeping the spirit of the broadhead.

In the illustrated embodiment FIG. 13a-d illustrates the indexing process during mill-turning manufacturing. An end mill tool is illustrated as a rectangle with dotted lines marked with the letter C. These illustration are meant to emphasize the importance of the right or obtuse angle between ferrule 21 and blade 20, the importance of the edge-to-center alignment and the importance of the polygon profiled ferrule. The design allow for an obstruction free manufacture process with simple square end mill tools. FIG. 13a illustrates milling across the underside 2 of blade 20 and across plane 18 at the same time. FIG. 13b illustrate side milling across plane 13. FIG. 13c illustrates milling across over-side 11 of blade 20. FIG. 13d illustrates side milling across plane 12. This process is repeated as many times as there are blades on the broadhead.

The above mentioned methods and descriptions are the preferable ways of manufacturing and preferable embodiment of the invention. Various alternation that doesn't depart from the spirit of the invention or the appended claims may occur. While the description and drawings above are detailed it will clearly be apparent for those in the field of art that several modifications such as; taper, thickness, bevel, angle, width, length, material, manufacture operation order and manufacture machine may be made without departing from the spirit of the broadhead. Any references to claim elements in the singular, for example, using the articles “a,” “an,” “the,” or “said” is not to be construed as limiting the element to the singular.

Claims

1. A broadhead comprising:

a ferrule, which includes a body extending from a rearward end to a front end along a central longitudinal axis;

the ferrule including a plurality of planar portions arranged around a circumference of the body and extending from the rearward end to the front end, to form a polygonal cross section;

a point linked with the ferrule front end; said point comprising a plurality of cutting edges, each cutting edge includes an underside edge in alignment with, and which extends radially away from, the central longitudinal axis, and a single bevel which extends toward an overside edge;

a plurality of blades mounted along the planar portions, each blade includes an underside cutting edge in alignment with, and which extends radially away from, the central longitudinal axis, and a single bevel which extends toward an overside edge;

an insert linked to said rearward end.

2. The broadhead as recited in claim 1, wherein said broadhead is manufactured from plastic material.

3. The broadhead as recited in claim 1, wherein said broadhead is manufactured from rubber material.

4. The broadhead as recited in claim 1, wherein a rearmost underside edge of said blades, extending radially from said ferrule rearward end to the outermost point of the blades, has a cutting edge, and a single bevel extending toward an overside edge.

5. The broadhead as recited in claim 1, wherein a rearmost underside edge of said blades, extending radially from said ferrule rearward end to the outermost point of the blades, is angled forward.

6. The broadhead as recited in claim 1, wherein a rearmost underside edge of said blades, extending radially from said ferrule rearward end to the outermost point of the blade, is angled rearward.

7. The broadhead as recited in claim 1, wherein said underside cutting edge of said blades are curved, each curved underside cutting edge is in alignment with, and which extends radially away from, the central longitudinal axis, and a single bevel which extends toward an overside edge.

8. The broadhead as recited in claim 1, wherein said ferrule, which includes a body extending from a rearward end to a front end along a central longitudinal axis include concave groves in said planar portions.

9. The broadhead as recited in claim 1, wherein said ferrule, which includes a body extending from a rearward end to a front end along a central longitudinal axis includes convex fillets between said planar portions.

10. A broadhead comprising:

a ferrule, which includes a body extending from a rearward end to a front end along a central longitudinal axis;

the ferrule including a plurality of planar portions arranged around a circumference of the body and extending from the rearward end to the front end, to form a polygonal cross section;

a point linked with the ferrule front end; said point comprising a plurality of cutting edges, each cutting edge includes an underside edge in alignment with, and which extends radially away from, the central longitudinal axis, and a single bevel which extends toward an overside edge;

a plurality of blades mounted along the planar portions, each blade includes an underside cutting edge in alignment with, and which extends radially away from, the central longitudinal axis, and a single bevel which extends toward an overside edge;

an open hollow core linked to said rearward end of the ferrule.

11. The broadhead as recited in claim 10, wherein said broadhead is manufactured from plastic material.

12. The broadhead as recited in claim 10, wherein said broadhead is manufactured from rubber material.

13. The broadhead as recited in claim 10, wherein a rearmost underside edge of said blades, extending radially from said ferrule rearward end to the outermost point of the blade, has a cutting edge, and a single bevel extending toward an overside edge.

14. The broadhead as recited in claim 10, wherein a rearmost underside edge of said blades, extending radially from said ferrule rearward end to the outermost point of the blade, is angled forward.

15. The broadhead as recited in claim 10, wherein a rearmost underside edge of said blades, extending radially from said ferrule rearward end to the outermost point of the blade, is angled rearward.

16. The broadhead as recited in claim 10, wherein said underside cutting edge of said blades are curved, each curved underside cutting edge is in alignment with, and which extends radially away from, the central longitudinal axis, and a single bevel which extends toward an overside edge.

17. The broadhead as recited in claim 10, wherein said ferrule, which includes a body extending from a rearward end to a front end along a central longitudinal axis include concave groves in said planar portions.

18. The broadhead as recited in claim 10, wherein said ferrule, which includes a body extending from a rearward end to a front end along a central longitudinal axis includes convex fillets between said planar portions.