Rotary cutting tool with honed edges

Abstract

A rotary cutting tool includes a shaft having and outer surface and having a longitudinal axis, a plurality of helical flutes formed in the shaft about the longitudinal axis, a plurality of helical cutting edges formed at an interface with the outer surface and a respective helical flute about the longitudinal axis, and a plurality of end cutting edges located on an axial distal end of a cutting portion of the shaft, the end cutting edges being contiguous with a corresponding one of the plurality of helical cutting edges and forming a corner in the transition between each of the end cutting edges and the corresponding one of the plurality of helical cutting edges. A hone edge extends along a portion of each of the end cutting edges, the associated corner and a portion of the corresponding one of the plurality of helical cutting edges.

Claims

1. An end mill rotary cutting tool comprising: a shaft having an outer surface and having a longitudinal axis, the shaft including a shank portion and cutting portion; a helical flute formed in the shaft in the cutting portion about the longitudinal axis; and a helical cutting edge formed at an interface with the outer surface and the helical flute about the longitudinal axis; and an end cutting edge located on an axial distal end of the cutting portion of the shaft, the end cutting edge being contiguous with the helical cutting edge and forming a corner in a transition between the end cutting edge and the helical cutting edge; where the helical cutting edge, the corner, and the end cutting edge form a contiguous hone edge extending a hone edge length and where the contiguous hone edge includes an edge radius, where the edge radius is variable along the hone edge length through the helical cutting edge, the corner, and the end cutting edge and where an axial angle and a radial angle of the contiguous hone edge are geometrically positive relative to rotating the shaft in a clock-wise rotational direction about the longitudinal axis.

2. The end mill of claim 1 where the edge radius continuously varies the entire hone edge length.

3. The end mill of claim 2 where the edge radius increases from the helical cutting edge toward the end cutting edge.

4. The end mill of claim 1 where the edge radius is greater on the corner as compared to the helical cutting edge.

5. The end mill of claim 1 where the edge radius is greater on the corner as compared to the end cutting edge and the helical cutting edge.

6. The end mill of claim 1 where the edge radius varies along the entire hone edge length of the corner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a side view of a known end mill.

(2) FIG. 2 is an enlarged portion of the end mill of FIG. 1.

(3) FIG. 3 is a view similar to FIG. 2 except showing the end will after significant wear. and show new and used corners.

(4) FIG. 4 is a tangential view of a portion of an end mill with corner radius.

(5) FIG. 5 is a side of the portion of the end mill of FIG. 4.

(6) FIG. 6 is a tangential view of a portion of an end mill with faced hook.

(7) FIG. 7 is a side of the portion of the end mill of FIG. 4.

(8) FIG. 8 is a tangential view of a portion of an end mill with B-Rad.

(9) FIG. 9 is a side of the portion of the end mill of FIG. 4.

(10) FIG. 10 is an enlarged front view of a portion of an end mill with hone edges.

(11) FIG. 11 is a further enlarged portion of FIG. 10.

(12) FIG. 12 is a tangential view the end mill of FIG. 10.

(13) FIG. 13 is a side view of the end mill of FIG. 10.

(14) FIG. 14 is an enlarged perspective view of the hone edge of the end mill of FIG. 10.

(15) FIG. 15 is a schematic illustration of a first hone edge.

(16) FIG. 16 is a schematic illustration of a second hone edge.

(17) FIG. 17 is a schematic illustration of a third hone edge.

(18) FIG. 18 is a schematic illustration of a fourth hone edge.

(19) FIG. 19 is a schematic illustration of a fifth hone edge.

(20) FIG. 20 is an enlarged view of a cutting edge of a conventional end mill after use.

(21) FIG. 21 is an enlarged view of a cutting edge of an end mill with hone edge after use.

(22) FIG. 22 is a front view of a portion of a CNC machine including a chuck holding a shaft.

(23) FIG. 23 is a front view of another portion of the CNC machine of FIG. 22 including a machine brush.

(24) FIG. 24 is a perspective view of the brush of FIG. 23.

(25) FIG. 25 is another perspective view of the CNC machine of FIGS. 22-24 showing the machine in operation.

(26) FIG. 26 is a further perspective view of the CNC machine of FIGS. 22-24 showing the machine in further operation.

(27) FIG. 27 shows an end mill with B-Rad.

(28) FIG. 28 shows an end mill with hone edge.

DETAILED DESCRIPTION

(29) There is shown in FIGS. 10-14, 21 and 28 an end mill rotary cutting tool 110. The tool 110 includes a shaft 112 having and an outer surface 114 and having a longitudinal axis X. The shaft 112 includes a shank portion 116, see FIG. 22, and cutting portion 118. A plurality of helical flutes 120 are formed in the shaft 112 in the cutting portion 118 about the longitudinal axis X.

(30) A plurality of helical cutting edges 122 are formed at an interface with the outer surface 114 and a respective helical flute 120 about the longitudinal axis X. A plurality of end cutting edges 124 are located on an axial distal end 126 of the cutting portion 118 of the shaft 112. The end cutting edges 124 are contiguous with a corresponding one of the plurality of helical cutting edges 122 and form a corner 128 in the transition between each of the end cutting edges 124 and the corresponding one of the plurality of helical cutting edges 122.

(31) A hone edge 130 extends along a portion of each of the end cutting edges 124, the associated corner 128 and a portion of the corresponding one of the plurality of helical cutting edges 122.

(32) The hone edges 130 may all be varying hone edges, that is to say that the amount of honing may vary along the length of the edge. The varying hone edges 130 may, for example, increase from the associated helical cutting edge 122 toward the associated end cutting edge 124. There may be increased honing on the corners 128 as compared to the helical cutting edges 122 or as compared to the end cutting edges 124 or both. The hone edges 130 may be formed to all be geometrically positive.

(33) The end mill of claim 2 where the helix angle of the helical flutes varies along the longitudinal axis.

(34) The rake angle of the helical cutting edges 122 may vary along the longitudinal axis X.

(35) There is illustrated in FIGS. 15-19 a variety of hone edge with the thickness of the hone line 132 indicating the amount of honing by location.

(36) In one embodiment, edges are rounded with a diamond impregnated fiber brush. Upon testing, see the method of corner strengthening has produced significant results. The corner radius stronger, as compared to other methods, and cutting force and torque were lower, and overall tool condition was better.

(37) This method may include that the treatment size would not be consistent over the entire edge length. For example, it may vary so as to provide protection according to the load associated with a specific location on an end mill, or vary in any other way as desired. As an example, the axial edges may receive 0.001-0.002 (inch) radius, transitioning around the corner radius to 0.0003-0.0005 (inch) on the radial edges.

(38) Listed are some of the benefits discovered provided by varying edge treatment as compared to other edge treatments: reduction of maximum force by 13.8% and torque by 11.5%, improvement of chip resistance at the corners over conventional protection methods, and improvement of chip resistance along the radial cutting edge.

(39) In one embodiment this may be combine with varying helix and/or varying rake to create a tool where the combination of two or three work together. It is expected that the varying rake/varying helix will reduce vibration, while the varying hone may be able to withstand more vibration. It is expected that when combined these features will create a highly chip resistant design.

(40) Illustrated is a test that compares a standard Z-Carb AP manufactured with a B-Rad, see FIGS. 20 and 27, to the identical product manufactured without a B-Rad, but with an axial edge treatment (hone) of 0.001 (inch), see FIGS. 21 and 28.

(41) Profile cuts were made in 4140 and 316 stainless at Tool Wizard parameters. Parameters for Test 085-09 were duplicated, which was a test that had shown the comparison between a B-Rad and a conventional unprotected corner radius. In the 4140 profile test, the stockroom sample (T1) showed micro-chipping, as typically observed during a coating test. T2, without the B-Rad but with the axial hone, did not show this edge condition. Neither tool showed any notable corner radius area damage. In Test 2, profile milling in 316 stainless, the stockroom sample (T3) showed edge chipping which was not exhibited by T4, the non-B-Rad/axial honed tool. Neither tool showed any corner damage. Test 3 involved profile milling in 15-5 PH stainless and after milling 1600 inches both tools (T5 and T6) had identical wear and chipping and no corner radius area damage. Test 4 used the load cell to determine tool load while plunging. Each tool was plunged into the 4140 workpiece three times and the forces measured, recorded and averaged. Tool 8 with no B-Rad and the axial hone averaged 14 percent less maximum Z-axis force and 12 percent less maximum torque than the stockroom sample (T7).

(42) In summary, in these tests, the stockroom samples showed edge damage equal to or worse than the axial honed tools, as well as generating more Z-axis force and torque while plunging. Overall, the preliminary results suggest the axial edge treatment is not detrimental to performance, and is likely beneficial to reduce corner damage as compared to the non-axial honed tools.

(43) Below are Tables representing Test 1-Test 4 that illustrate four tests of stock sample compared to a honed sample.

(44) TABLE-US-00001 Tool.Math.Wizard.Math.parameters.Math.(Test.Math.1) MACHINE TOOL.Math.HOLDER COOLANT 4140.Math.alloy.Math.steel.Math.28HRc Haas.Math.VM3 Techniks.Math.ER-32.Math.short S-373 SPEED FEED RADIAL.Math.WIDTH AXIAL.Math.DEPTH 2,865.Math.rpm/.Math.375.Math.sfm 26.24.Math.ipm/.Math..00229.Math.ipt .250.Math.(50%.Math.D) .500.Math.(D) TOOL TYPE TIR.Math.IN NO. DESCRIPTION MACHINE USAGE INSPECTION . . . NOTES 1 ZAP1C05000_030TX.Math.stockroom.Math. .0003 640 .Math.Varying.Math.micro.Math.chipping.Math.on.Math.cutting.Math.edges.Math.and.Math.corner.Math.radii. sample 2 Test.Math.sample.Math.without.Math.B-Rad; .Math..001.Math.axial.Math. .0004 640 Even.Math.and.Math.consistent.Math.on.Math.cutting.Math.edges.Math.and.Math.corner.Math.radii hone,

(45) TABLE-US-00002 Tool.Math.Wizard.Math.parameters.Math.(Test.Math.2) WORKPIECE MACHINE TOOL.Math.HOLDER COOLANT 316.Math.stainless Haas.Math.VM3 Techniks.Math.ER-32.Math.short S-373 SPEED FEED RADIAL.Math.WIDTH AXIAL.Math.DEPTH 3,025.Math.rpm/.Math.396.Math.sfm 21.78.Math.ipm/.Math..0018.Math.ipt .250 (50%.Math.D) .400.Math.(80%.Math.D) TOOL TYPE TIR.Math.IN NO. DESCRIPTION MACHINE USAGE INSPECTION . . . NOTES 3 ZAP1C05000_030TX.Math.stockroom.Math. .0003 640 Varying.Math.edge.Math.damage.Math.with.Math.chipping.Math..0044.Math.to.Math..007.Math.on.Math.primary.Math. sample Corners/.Math.B-Rad.Math.intact 4 Test.Math.sample.Math.without.Math.B-Rad; .Math..001.Math.axial.Math. .0002 640 .0008.Math.edge.Math.wear, .Math.even.Math.and.Math.consistent.Math.on.Math.cutting.Math.edges.Math.and.Math.corner.Math.radii hone,

(46) TABLE-US-00003 Parameters.Math.from.Math.test.Math.085-09.Math.(Test.Math.3) WORKPIECE MACHINE TOOL.Math.HOLDER COOLANT 15-5 PH.Math.stainless Haas.Math.VM3 Techniks.Math.ER-32.Math.short S-373 35/37.Math.HRc SPEED FEED RADIAL.Math.WIDTH AXIAL.Math.DEPTH 2,180.Math.rpm/.Math.285.Math.sfm 17.0.Math.ipm/.Math..0019.Math.ipt .250 .125 TOOL TYPE TIR.Math.IN NO. DESCRIPTION MACHINE USAGE INSPECTION . . . NOTES 5 ZAP1C05000_030TX.Math.stockroom.Math. .0002 1120 .0025.Math.wear, .Math.not.Math.tool.Math.damage sample 1600 .0032.Math.wear, .Math.each.Math.flute.Math.has.Math.a.Math.small.Math.chip.Math.on.Math.edge. .Math.No.Math.corner.Math.area.Math.damage 6 Test.Math.sample.Math.without.Math.B-Rad; .Math..001.Math.axial.Math. .0004 1120 .0025.Math.wear, .Math.no.Math.tool.Math.damage. hone, 1600 .0033.Math.wear, .Math.each.Math.flute.Math.has.Math.a.Math.small.Math.chip.Math.on.Math.edge. .Math.No.Math.corner.Math.area.Math. damage.

(47) TABLE-US-00004 Plunge.Math.in.Math.load.Math.cell.Math.(Test.Math.4) WORKPIECE MACHINE TOOL.Math.HOLDER COOLANT 4140.Math.alloy.Math.steel.Math.28HRc Haas.Math.VM3 Techniks.Math.ER-32.Math.short S-373 SPEED FEED RADIAL.Math.WIDTH AXIAL.Math.DEPTH 2,865.Math.rpm/.Math.375.Math.sfm 13.0.Math.ipm/.Math..0045.Math.ipr .500.Math.(D) .050.Math. TOOL TYPE TIR.Math.IN NO. DESCRIPTION MACHINE USAGE INSPECTION . . . NOTES 7 ZAP1C05000_030TX.Math. stockroom.Math. .0003 3.Math.plunges 328.14.Math.lbs.Math.average.Math.maximum.Math.Z-axis.Math.load..Math.69.1.Math.average.Math.in.Math.lbs.Math.torque.Math. sample 8 Test.Math.sample.Math.without.Math.B-Rad; .Math..001.Math.axial.Math. .0003 3.Math.plunges 282.89.Math.lbs.Math.average.Math.maximum.Math.Z-axis.Math.load..Math.61.1.Math.average.Math.in.Math.lbs.Math.torque hone, Comments: Tool.Math.8.Math.had.Math.approximately.Math.14%.Math.less.Math.average.Math.Z-axis.Math.load.Math.and.Math.12%.Math.less.Math.average.Math.torque.Math.requirement.Math.(maxiumuns)

(48) Below are Tables Tool 7 and Tool 8 that give the parameters for the stock sample and honed sample, Plunges 1-3.

(49) TABLE-US-00005 Tool.Math.7.Math.stockroom.Math.sample Plunge.Math.1 Plunge.Math.2 Plunge.Math.3 UNITS .fwdarw. lbs UNITS .fwdarw. lbs UNITS .fwdarw. lbs MEAN .fwdarw. 265.72 MEAN .fwdarw. 265.85 MEAN .fwdarw. 275.03 STD DEV. .fwdarw. 50.05 STD DEV. .fwdarw. 54.32 STD DEV. .fwdarw. 66.14 MINIMUM .fwdarw. 104.80 MINIMUM .fwdarw. 117.05 MINIMUM .fwdarw. 70.62 MEDIAN .fwdarw. 282.62 MEDIAN .fwdarw. 284.24 MEDIAN .fwdarw. 291.65 MAXIMUM .fwdarw. 315.67 MAXIMUM .fwdarw. 315.67 MAXIMUM .fwdarw. 353.08 UNITS .fwdarw. inlb UNITS .fwdarw. inlb UNITS .fwdarw. inlb MEAN .fwdarw. 52.211 MEAN .fwdarw. 50.895 MEAN .fwdarw. 50.236 STD DEV. .fwdarw. 11.651 STD DEV. .fwdarw. 15.633 STD DEV. .fwdarw. 15.741 MINIMUM .fwdarw. 19.342 MINIMUM .fwdarw. 5.120 MINIMUM .fwdarw. 6.827 MEDIAN .fwdarw. 54.233 MEDIAN .fwdarw. 54.327 MEDIAN .fwdarw. 52.716 MAXIMUM .fwdarw. 66.274 MAXIMUM .fwdarw. 71.204 MAXIMUM .fwdarw. 69.687

(50) TABLE-US-00006 Tool.Math.8.Math.without.Math.B-Rad.Math.and.Math..001.Math.axial.Math.edge.Math.prep/.Math.hone Plunge.Math.1 Plunge.Math.2 Plunge.Math.3 UNITS .fwdarw. lbs UNITS .fwdarw. lbs UNITS .fwdarw. lbs MEAN .fwdarw. 238.00 MEAN .fwdarw. 244.21 MEAN .fwdarw. 248.13 STD DEV. .fwdarw. 15.09 STD DEV. .fwdarw. 20.69 STD DEV. .fwdarw. 38.18 MINIMUM .fwdarw. 205.42 MINIMUM .fwdarw. 184.60 MINIMUM .fwdarw. 119.71 MEDIAN .fwdarw. 239.90 MEDIAN .fwdarw. 247.55 MEDIAN .fwdarw. 253.56 MAXIMUM .fwdarw. 261.21 MAXIMUM .fwdarw. 267.55 MAXIMUM .fwdarw. 319.92 UNITS .fwdarw. inlb UNITS .fwdarw. inlb UNITS .fwdarw. inlb MEAN .fwdarw. 46.779 MEAN .fwdarw. 47.885 MEAN .fwdarw. 48.260 STD DEV. .fwdarw. 7.386 STD DEV. .fwdarw. 7.835 STD DEV. .fwdarw. 13.354 MINIMUM .fwdarw. 22.394 MINIMUM .fwdarw. 20.964 MINIMUM .fwdarw. 7.433 MEDIAN .fwdarw. 49.076 MEDIAN .fwdarw. 49.409 MEDIAN .fwdarw. 48.028 MAXIMUM .fwdarw. 55.175 MAXIMUM .fwdarw. 57.938 MAXIMUM .fwdarw. 70.136

(51) The developed method addresses the corner strength issue while also maintaining efficient shearing capability. By utilizing a CNC brush honing machine, method has been crafted to utilize brush wheel of the hone machine to produce a relatively wider, heavier hone at the axial end of the tool which diminishes in size as it proceeds down the radial side of the flutes.

(52) By eliminating the faced hook and B-Rad, the shearing capability is improved and by adding the variable hone the corners are protected.

(53) One method of forming a rotary cutting tool includes the steps of: providing a shaft having and outer surface and having a longitudinal axis; forming a plurality of helical flutes in the shaft about the longitudinal axis defining a cutting portion, the remainder of the shaft defining a shank portion; forming a plurality of helical cutting edges at an interface with the outer surface and a respective helical flute about the longitudinal axis; forming a plurality of end cutting edges on an axial distal end of cutting portion of the shaft, the end cutting edges being contiguous with a corresponding one of the plurality of helical cutting edges and forming a corner in the transition between each of the end cutting edges and the corresponding one of the plurality of helical cutting edges; and forming a hone edge extending along a portion of each of the end cutting edges, the associated corner and a portion of the corresponding one of the plurality of helical cutting edges.

(54) Referring to FIGS. 22-26, the shaft may be secured in chuck at the shank portion and then rotated. A machining brush may be provided and applied to the helical cutting edges, the corners, and/or the end cutting edges to form hone edges, such as varying hone edges. The brush may include filaments flanged between two disks. This may be performed by a CNC machine.

(55) While principles and modes of operation have been explained and illustrated with regard to particular embodiments, it must be understood, however, that this may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.