TWIST DRILL

• US 20090087275A1
• Filed: 08/02/2006
• Published: 04/02/2009
• Est. Priority Date: 08/02/2005
• Status: Active Grant

• Current Assignee: Dormer Tools Ltd. (Sandvik AB)
• Original Assignee: Dormer Tools Ltd. (Sandvik AB)
• Inventors: Goulbourne, David
• Granted Patent: US 8,540,463 B2
• Time in Patent Office: Days
• US Class Current: 408/230
• CPC Class Codes: B23B 2226/27 Composites
• CPC Class Codes: B23B 2250/12 Cooling and lubrication
• CPC Class Codes: B23B 2251/04 Angles, e.g. cutting angles
• CPC Class Codes: B23B 2251/14 Configuration of the cutting part, i.e. the main cutting edges
• CPC Class Codes: B23B 2251/18 Configuration of the drill point
• CPC Class Codes: B23B 51/02 Twist drills
• CPC Class Codes: Y10T 408/78 Tool of specific diverse material
• CPC Class Codes: Y10T 408/81 Tool having crystalline cutting edge
• CPC Class Codes: Y10T 408/899 Having inversely angled cutting edge
• CPC Class Codes: Y10T 408/906 Axially spaced
• CPC Class Codes: Y10T 408/9097 Spiral channel

Abstract

A metal-working twist drill is provided with inner cutting edges that form a point (18) having an angle, A, of 130°. An outer, peripheral, part of each cutting edge (55, 57) forms an outer cutting portion (59, 61). The outer cutting portions slope in the opposite direction to the corresponding inner cutting edges and form an angle B, of 3° with respect to a plane normal to the axis of rotation of the twist drill. The width of the outer cutting portion, D as measured at the cutting edge, is 10.5% of the diameter of the twist drill. The metal-working twist drill produces bores having a reduced exit burr height.

Claims

1-69. -69. (canceled)

70. A twist drill having

a shank,

an axis of rotation about which the twist drill rotates during use, and

a cutting tip, the cutting tip having a cutting edge, wherein an inner cutting portion of the cutting edge forms a point, the point angle being in the range 110°

to 160°

, characterized in that a radially outer part of the cutting edge includes

an outer cutting portion that is inclined in the opposite axial direction to the inner cutting portion.

71. A twist drill according to claim 70, wherein the point angle is in the range 125°

to 160°

.

72. A twist drill according to claim 71, wherein the point angle is in the range 128°

to 160°

.

73. A twist drill according to claim 72 wherein the point angle is in the range 130°

to 160°

.

74. A twist drill according to claim 70, wherein the outer cutting portion is inclined at an angle of from 2°

to <

10°

with respect to a plane normal to the axis of rotation.

75. A twist drill according to claim 74, wherein the outer cutting portion is inclined at an angle of from 20 to 80 with respect to a plane normal to the axis of rotation.

76. A twist drill according to claim 70, wherein the width of the outer cutting portion is in the range of 5% to 30% of the diameter of the twist drill.

77. A twist drill according to claim 76, wherein the width of the outer cutting portion is in the range of 5% to 15% of the diameter of the twist drill.

78. A twist drill according to claim 70, wherein the twist drill includes a cylindrical land.

79. A twist drill according to claim 78, wherein the outer cutting portion extends to the outermost edge of the cylindrical land.

80. A twist drill according to claim 70, wherein the radially outermost part of the outer cutting portion is located on the outer peripheral edge of the cutting tip.

81. A twist drill according to claim 70, wherein the outer portion and the point meet each other.

82. A twist drill according to claim 70, wherein the cutting tip includes 2 cutting edges, which form the point.

83. A twist drill according to claim 70, wherein the twist drill includes double helical flutes.

84. A twist drill according to claim 70, wherein the twist drill is made of tungsten carbide.

85. A twist drill according to claim 70, wherein the twist drill comprises polycrystalline diamond mounted on a metal substrate.

86. A twist drill having

a shank,

an axis of rotation about which the twist drill rotates during use,

a cutting tip, the cutting tip having a cutting edge, wherein an inner cutting portion of the cutting edge forms a point, the point angle being in the range 130°

to 160°

, wherein a radially outer part of the cutting edge includes an outer cutting portion that is inclined in the opposite axial direction to the inner cutting portion at an angle of from 2°

to 8°

with respect to a plane normal to the axis of rotation, wherein the outer cutting portion and the point meet each other; and

a cylindrical land wherein the outer cutting portion extends to the outermost edge of the cylindrical land.

87. A method of manufacturing a twist drill for drilling metal substrates, including the steps of

(i) fluting a drill blank to produce a helical flute;

(ii) forming a cutting edge at the end of the flute, wherein an inner cutting portion of the cutting edge forms a point having a point angle in the range 110°

to 160°

; and

(iii) forming an outer cutting portion as a radially outer part of the cutting edge, wherein the outer cutting portion is inclined in the opposite axial direction to the inner cutting portion.

88. A method according to claim 87, wherein the point angle is in the range 130°

to 160° and

the outer cutting portion is formed so as to have an angle of from 2°

to <

10°

with respect to a plane normal to the axis of rotation of the twist drill.

89. A method according to claim 87 wherein the step of forming an inner cutting portion includes the step of grinding a facet at the end of the flute and the step of forming the outer cutting portion includes the step of grinding a further facet.

90. A method of modifying a twist drill having a cutting tip with a point having a point angle in the range 110°

to 160°

, wherein the method includes the step of forming an outer cutting portion on an outer part of the cutting edge, wherein the outer cutting portion is inclined in the opposite axial direction to an inner cutting portion of the cutting edge.

91. A method of drilling a laminate material wherein a twist drill according to claim 90 is used to drill the laminate material.

92. A method according to claim 91, wherein the laminate material includes a layer of carbon fiber composite and an aluminum-containing layer.

93. A method according to claim 92, wherein the laminate material is a CFRP/Al material.