Metal cutting indexable drill

Abstract

A metal cutting indexable drill tool (100) comprising: an elongated drill body (101) having a boring shaft (102) and a mounting shank (103); a center drill insert (104) mounted in an insert seat (106) at a distal end (105) of the boring shaft (102), the insert seat (106) being configured to hold the insert against a bottom of the insert seat (106); a drill flute (107) of the boring shaft (102) being configured to guide and form chips from the center drill insert (104), wherein the drill flute (107) comprises a chip forming surface (108) at a distal end (109) of the drill flute (107); wherein the chip forming surface (108) is perpendicular to a center drill insert (104) and a center drill insert (104) disposed on the center drill insert (104). The bottom of the insert seat (106); and the chip forming surface (108) is arranged at a distance X from the outer corner (110) of the center drill insert (104) to a point (301) on a curve (302), the curve being formed by the intersection of the chip forming surface (108) and an imaginary inscribed sphere (302), wherein the center (303) of the imaginary inscribed sphere coincides with the center of the distal end (105) of the boring axis (102), wherein the radius of the imaginary inscribed sphere is defined by the outer corner (110) of the insert (104); and wherein the distance X divided by the diameter Dc of the drill tool is equal to a chip parameter A, which represents the ratio of the chip diameter to the boring diameter; wherein the chip parameter A is 0.3≤A≤0.5.

Description

Technical Field

[0001] The invention relates to a metal cutting indexable drill tool, and more particularly to a metal cutting indexable drill tool with a center drill blade. Background Art

[0002] Drilling is an important operation in modern subtractive manufacturing, especially drilling holes in metals proves to be a demanding operation.

[0003] In metal drilling, drills with replaceable metal cutting inserts are often used, especially in CNC operations. Drills of the aforementioned type include an elongated drill body having a mounting shank and a boring shaft. At the distal end of the boring shaft, a central insert for cutting material from the central region of the drilled hole and a peripheral insert for cutting material in the peripheral region of the hole are arranged. In order to achieve a good drilling operation, chip removal and chip control are crucial for surface finish and drill speed. However, chip removal and control are also very important for process safety and reliability. In particular, chip control and chip removal of the central insert have proven to be very demanding. The chips cut by the central insert are in the form of spiral cones, because the peripheral end of the blade of the insert cuts longer chips than the central end of the blade of the insert. Another important parameter of chip formation is the length of the chip, which is preferably long enough, but not too long. If the chips become too long, they may entangle the drill and lead to poor process security and surface damage in the drilled hole, and chips that are too short may also lead to problems with chip ejection from the drill, which of course also has a negative impact on process security and reliability.

[0004] It is well known in the art to provide a drill with drill flutes for improved chip removal and control. This allows continuous chips to be formed and directed away from the cutting area. However, the problem of chips that are too long cannot be solved with drill flutes.

[0005] Therefore, there is still a need to further improve the geometry of metal cutting drills to achieve good chip evacuation and prevent the formation of too long chips.

[0006] It is therefore an object of the present invention to provide a metal cutting drill which allows for improved chip control. Summary of the invention

[0007] According to the present invention, the above objects are achieved by a metal cutting indexable drill having the features defined in the present invention.

[0008] The metal cutting indexable drill according to the present invention comprises an elongated drill body having a boring shaft and a mounting shank, a center drill insert mounted in an insert seat at a distal end of the boring shaft, the insert seat being configured to hold the insert against a bottom of the insert seat. The metal cutting indexable drill further comprises a drill flute of the boring shaft, the drill flute being configured to guide and form chips from the center drill insert, wherein the drill flute comprises a chip forming surface at a distal end of the drill flute. The metal cutting indexable drill is characterized in that the chip forming surface is perpendicular to the bottom of the insert seat for the center drill insert, and the chip forming surface is arranged at a distance X from the peripheral corner of the center drill insert to a point on a curve formed by the intersection of the chip forming surface and an imaginary inscribed sphere, wherein the center of the imaginary inscribed sphere coincides with the center of the distal end of the boring axis, wherein the radius of the imaginary inscribed sphere is defined by the peripheral corner of the insert; and wherein the distance X divided by the diameter Dc of the drill tool is equal to a chip parameter A, which represents the ratio of the chip diameter to the boring diameter. The chip parameter A is 0.3≤A≤0.5.

[0009] According to one embodiment, the chip parameter A is 0.37≦A. In this way, chips having a diameter greater than the minimum value are formed.

[0010] According to one embodiment, the chip parameter A is A≤0.42. This allows chips with a diameter smaller than the maximum value to be formed.

[0011] According to one embodiment, said point on the curve is located at the midpoint of said curve.

[0012] According to one embodiment, the metal cutting indexable drill according to the present invention is characterized in that the chip forming surface extends in a radial direction relative to the longitudinal axis of the metal cutting drill by a distance w≥Dc / 4, and wherein Dc is the diameter of the metal cutting drill. In this way, a chip forming surface of sufficient size is formed.

[0013] According to one embodiment, the chip forming surface is perpendicular to the bottom of the insert seat over its entire length.

[0014] According to one embodiment, the radial distance d1 from the top of the insert to the chip forming surface is d1 = Dc·P, where P is 0.04≤P≤0.08, and Dc is the diameter of the drill. In this way, effective chip evacuation is achieved.

[0015] According to one embodiment, the radial distance d1 from the top of the insert to the chip forming surface is d1 = Dc·P, where P is 0.04≤P≤0.06, and Dc is said diameter of the drill. In this way, an even more efficient chip evacuation is achieved.

[0016] Other advantages of the present invention will become apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a stereoscopic diagram of a metal cutting indexable drill according to an embodiment of the present invention,

[0018] Figure 2 yes Figure 1 A top view of the metal cutting indexable drill disclosed in

[0019] Figure 3 is an imaginary inscribed sphere Figure 1 and Figure 2 A perspective view of the distal end of the boring shaft of the metal cutting indexable drill disclosed in. DETAILED DESCRIPTION

[0020] refer to Figure 1 , Figure 1 A metal cutting indexable drill 100 is shown, which includes an elongated drill body 101 having a boring shaft 102 and a mounting shank 103. The metal cutting indexable drill further includes a center drill insert 104 mounted in an insert seat 106 at a distal end 105 of the boring shaft 102, the insert seat 106 being configured to hold the insert against the bottom of the insert seat 106, a drill flute 107 of the boring shaft 102, which is configured to guide and form chips from the center drill insert 104. The drill flute 107 includes a chip forming surface 108 at a distal end 109 of the drill flute 107. The metal cutting indexable drill is characterized in that the chip forming surface 108 is perpendicular to the bottom of the insert seat 106 for the center drill insert 104, and the chip forming surface 108 is arranged at a distance X from a peripheral corner 110 of the center drill insert 104 to a point 301 on a curve 302, as shown in FIG. Figure 3 As shown. The curve is formed by the intersection of the chip forming surface 108 and an imaginary inscribed sphere 309. The center 303 of the imaginary inscribed sphere coincides with the center of the distal end 105 of the boring axis 102, wherein the radius of the imaginary inscribed sphere is defined by the peripheral corner 110 of the insert 104, and wherein the distance X divided by the diameter Dc of the drill tool is equal to the chip parameter A, which represents the ratio of the chip diameter to the boring diameter. The chip parameter A is 0.3≤A≤0.5.

[0021] The inventors have realized that by making such a chip parameter A within the above interval, an advantageous chip formation process is achieved and a chip having a diameter X=A·Dc is formed. The diameter of the chip formed is the diameter of the spiral chip formed in the drilling operation and is an important parameter for designing a boring shaft. The diameter of the chip can be used to optimize the amount of material in the boring shaft, which means that a stronger boring shaft can be obtained. In this way, the boring shaft can be designed for increased strength while maintaining chip control and chip evacuation.

[0022] In one embodiment, the chip parameter A is 0.37 ≤ A. In this way, chips having a diameter greater than the minimum value are obtained.

[0023] In one embodiment, the chip parameter A is ≤ 0.42. Thus, chips with a diameter smaller than the maximum value are obtained.

[0024] Now refer to it again Figure 3 , Figure 3 An imaginary inscribed sphere 309 is shown arranged at the center of the distal end 105 of the boring axis 102. The center 303 of the imaginary inscribed sphere 309 coincides with the center of the distal end 105 of the boring axis 102. The radius of the imaginary inscribed sphere is defined by the peripheral corner 110 of the blade 104. The peripheral corner is a radial peripheral corner and an axial peripheral corner relative to the longitudinal axis of the drilling tool 100. In other words, the peripheral corner 110 is the radially outermost and axially outermost corner of the blade 104 relative to the drilling tool 100, and is therefore the active corner of the blade, which is closest to the hole wall of the hole formed when drilling. The curve 302 is formed by the intersection of the chip forming surface 108 and the imaginary inscribed sphere 309.

[0025] exist Figure 3 , the point 301 on the curve 302 is located at the midpoint of the curve 302. However, due to the geometric relationship between the curve 302 and the peripheral corner 110, the point 301 can be placed anywhere on the curve 302 without significantly affecting the length of the distance X as shown. The distance X is the shortest distance from the peripheral corner 110 to the point 301.

[0026] like Figure 2 As shown, the chip forming surface 108 extends in a radial direction by a distance w≧Dc / 4 relative to the longitudinal axis of the metal cutting drill 100 , and wherein Dc is the diameter of the metal cutting drill 100 .

[0027] Figure 2 The chip forming surface 108 is shown to be perpendicular to the bottom of the insert seat 106 over its entire length.

[0028] Figure 2 Also shown is the radial distance d1 from the top 201 of the insert 104 to the chip forming surface 108. The radial distance d1 is d1 = Dc·P, where P is 0.04≤P≤0.08, and Dc is the diameter of the drill 100. The distance d1 is important for chip evacuation, and P is preferably 0.04≤P≤0.06.

Claims

1. A metal cutting indexable drill (100), comprising: An elongated drill body (101) having a boring shaft (102) and a mounting handle (103); a center drill blade (104) mounted in a blade seat (106) at a distal end (105) of the boring shaft (102), the blade seat (106) being configured to hold the blade against a bottom of the blade seat (106); a drill flute (107) of the boring shaft (102), the drill flute (107) being configured to guide and form chips from the center drill insert (104), wherein the drill flute (107) includes a chip forming surface (108) at a distal end (109) of the drill flute (107); characterised in that the chip forming surface (108) is perpendicular to the bottom of the insert seat (106) for the centre drill insert (104); and The chip forming surface (108) is arranged at a distance X from a peripheral corner (110) of the center drill insert (104) to a point (301) on a curve (302) formed by the intersection of the chip forming surface (108) and an imaginary inscribed sphere (302), wherein the center (303) of the imaginary inscribed sphere coincides with the center of the distal end (105) of the boring axis (102), wherein the radius of the imaginary inscribed sphere is defined by the peripheral corner (110) of the insert (104); and wherein the distance X divided by the diameter Dc of the drill tool is equal to a chip parameter A, wherein the chip parameter A represents a ratio of a chip diameter to a boring hole diameter; The chip parameter A is 0.3≤A≤0.

5.

2. The metal cutting indexable drill (100) according to claim 1, characterized in that: The chip parameter A is 0.37≤A.

3. The metal cutting indexable drill (100) according to any one of claims 1 to 2, characterized in that: The chip parameter is A≤0.

42.

4. The metal cutting indexable drill (100) according to any one of claims 1 to 2, characterized in that: The point (301) on the curve (302) is located at the midpoint of the curve (302).

5. The metal cutting indexable drill (100) according to any one of claims 1 to 2, characterized in that: The chip forming surface (108) extends in a radial direction by a distance w≥Dc / 4 relative to a longitudinal axis of the metal cutting indexable drill (100), and wherein Dc is a diameter of the metal cutting indexable drill (100).

6. The metal cutting indexable drill (100) according to any one of claims 1 to 2, characterized in that: The chip forming surface (108) is perpendicular to the bottom of the insert seat (106) over its entire length.

7. The metal cutting indexable drill (100) according to any one of claims 1 to 2, characterized in that: The radial distance d1 from the top of the insert (104) to the chip forming surface (108) is d1=Dc·P, where P is 0.04≤P≤0.08, and Dc is the diameter of the drill.

8. The metal cutting indexable drill (100) according to any one of claims 1 to 2, characterized in that: The radial distance d1 from the top of the insert (104) to the chip forming surface (108) is d1=Dc·P, where P is 0.04≤P≤0.06, and Dc is the diameter of the drill (100).

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