Indexable drilling tools for metal cutting

Abstract

The metal-cutting indexable drill tool (100) includes an elongated drill body (101) having a drill shaft (102) and a mount shank (103), a central drill insert (104) mounted on a distal end (105) of the drill shaft (102) within an insert seat (106), the insert seat (106) configured to hold the insert against a bottom of the insert seat (106), and drill flutes (107) on the drill shaft (102) configured to guide and form chips from the central drill insert (104), the drill flutes (107) including chip-forming surfaces (108) at distal ends (109) of the drill flutes (107). the tip-forming surface (108) is perpendicular to the bottom of the insert seat (106) for the central drill insert (104); the tip-forming surface (108) is located at a distance X from a peripheral corner (110) of the central drill insert (104) to a point (301) on a curve (302) formed by the intersection of the tip-forming surface (108) and an imaginary inscribed sphere (302); the center (303) of the imaginary inscribed sphere coincides with the center of the distal end (105) of the drilling shaft (102); the radius of the imaginary inscribed sphere is defined by the peripheral corner (110) of the insert (104); the distance X divided by the diameter of the drill tool Dc is equal to a tip parameter A indicating the ratio of the tip diameter to the drilling diameter, wherein the tip parameter A is in the range of 0.3≦A≦0.5.

Description

[Technical Field]

[0001] The present invention relates to indexable metal-cutting drill tools, and more particularly to indexable metal-cutting drill tools with a center drill insert. [Background technology]

[0002] In modern subtractive manufacturing, drilling is a critical operation, and drilling metal in particular has proven to be a demanding operation.

[0003] In metal drilling, drill tools with replaceable metal-cutting inserts are often used, especially in CNC operations. These types of drill tools include an elongated drill body with a mounting shank and a drill shaft. At the distal end of the drill shaft are a central insert for cutting material from the central region of the drill hole and a peripheral insert for cutting material from the peripheral region of the hole. To achieve a successful drilling operation, chip evacuation and chip control are paramount for surface finish and drilling speed. However, chip evacuation and control are also crucial for process safety and reliability. Chip control and chip evacuation, especially for central inserts, prove to be demanding. The chips cut by the central insert are in the shape of a spiral cone due to the fact that the peripheral edge of the insert edge cuts a longer chip than the central edge of the insert edge. Another important parameter for chip formation is the chip length, which is preferably long enough but not too long. If the tip is too long, it may entangle the drill tool, reducing the safety of the process and causing surface damage to the drilled hole; if the tip is too short, it may also cause problems with chip ejection from the drill tool, which will naturally have a negative impact on the safety and reliability of the process.

[0004] It is known in the art to provide drilling tools with drill flutes for improved chip evacuation and control, which allows continuous chips to be formed and directed away from the cutting zone. However, the problem of overly long chips is not addressed by drill flutes.

[0005] Therefore, there remains a need for further improvements in the geometry of metal-cutting drill tools to achieve good chip evacuation and prevent chips from being formed that are too long.

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

[0007] According to the present invention, the above object is achieved by an indexable drill tool for metal cutting having the features defined in claim 1.

[0008] The indexable metal-cutting drill tool according to the present invention includes an elongated drill body having a drill shaft and a mounting shank, and a central drill insert mounted on the distal end of the drill shaft within an insert seat configured to hold the insert against the bottom of the insert seat. The indexable metal-cutting drill tool further includes drill flutes on the drill shaft configured to guide and form chips from the central drill insert, the drill flutes including chip-forming surfaces at their distal ends. The indexable metal-cutting drill tool is characterized in that the chip-forming surfaces are perpendicular to the bottom of the insert seat for the central drill insert, the chip-forming surfaces are located a distance X from a peripheral corner of the central drill insert to a point on a curve formed by the intersection of the chip-forming surfaces with an imaginary inscribed sphere, the center of the imaginary inscribed sphere coinciding with the center of the distal end of the drill shaft, the radius of the imaginary inscribed sphere being defined by the peripheral corner of the insert, and the distance X divided by the diameter of the drill tool Dc is equal to a chip parameter A indicating the ratio of the chip diameter to the drill hole diameter. The chip parameter A is in the range of 0.3≦A≦0.5.

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

[0010] According to one embodiment, the tip parameter A is A≦0.42, which allows for the formation of tips with diameters smaller than the maximum.

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

[0012] According to one embodiment, the indexable metal-cutting drill tool according to any one of the preceding claims, characterized in that the chip-forming surface extends radially relative to a longitudinal axis of the metal-cutting drill tool a distance w≧Dc / 4), where Dc is the diameter of the metal-cutting drill tool, in such a way that a chip-forming surface of sufficient size is formed.

[0013] According to one embodiment, the tip 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 tool. In this way, efficient 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 the diameter of the drill tool. In this way, more efficient chip evacuation is achieved.

[0016] Further advantages of the present invention will become apparent from the following description. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a perspective view of an indexable metal-cutting drill tool according to an embodiment of the present invention; FIG. [Figure 2] 2 is a top view of the indexable metal-cutting drill tool disclosed in FIG. 1. FIG. [Figure 3] 3 is a perspective view of the distal end of the drilling shaft of the metal-cutting indexable drill tool disclosed in FIGS. 1 and 2 having an imaginary inscribed sphere; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] 1 , which illustrates a metal-cutting indexable drill tool 100 including an elongated drill body 101 having a drill shaft 102 and a mounting shank 103. The metal-cutting indexable drill tool further includes a central drill insert 104 mounted at a distal end 105 of the drill shaft 102 within an insert seat 106 configured to hold the insert against a bottom of the insert seat 106, and drill flutes 107 on the drill shaft 102 configured to guide and form chips from the central drill insert 104. The drill flutes 107 include chip-forming surfaces 108 at distal ends 109 of the drill flutes 107. The indexable drill tool for metal cutting is characterized in that the tip-forming surface 108 is perpendicular to the bottom of the insert seat 106 for the central drill insert 104, and the tip-forming surface 108 is located a distance X from a peripheral corner 110 of the central drill insert 104 to a point 301 on a curve 302, as seen in FIG. 3 . The curve is formed by the intersection of the tip-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 drilling shaft 102, and the radius of the imaginary inscribed sphere is defined by the peripheral corner 110 of the insert 104. The distance X divided by the diameter of the drill tool Dc is equal to a tip parameter A, which indicates the ratio of the tip diameter to the drill hole diameter. The tip parameter A is in the range of 0.3≦A≦0.5.

[0019] The inventors have recognized that by setting the tip parameter A within the above interval, a good tip formation process is achieved, resulting in the formation of a tip with a diameter X = A · Dc. The diameter of the tip formed is the diameter of the spiral tip formed in the drilling operation, and is an important parameter for designing a drilling shaft. The tip diameter can be used to optimize the amount of material in the drilling shaft, which means that a stronger drilling shaft can be obtained. In this way, the drilling shaft can be designed to increase strength while maintaining chip control and chip evacuation.

[0020] In one embodiment, the tip parameter A is 0.37≦A. In this way, tips with diameters larger than the minimum value are obtained.

[0021] In one embodiment, the tip parameter A is A≦0.42. In this way, tips with a diameter smaller than the maximum are obtained.

[0022] Referring again to FIG. 3 , an imaginary inscribed sphere 309 is shown positioned at the center of the distal end 105 of the drilling shaft 102. The center 303 of the imaginary inscribed sphere 309 coincides with the center of the distal end 105 of the drilling shaft 102. The radius of the imaginary inscribed sphere is defined by the peripheral corner 110 of the insert 104. The peripheral corner is the radial peripheral corner and the 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 insert 104 relative to the drilling tool 100, and is therefore the effective corner of the insert closest to the wall of the hole formed during drilling. A curve 302 is formed by the intersection of the tip-forming surface 108 and the imaginary inscribed sphere 309.

[0023] 3, point 301 on curve 302 is located at the midpoint of curve 302. However, due to the geometric relationship between curve 302 and peripheral corner 110, point 301 can be located anywhere on curve 302 without significantly affecting the length of distance X, as shown. Distance X is the shortest distance from peripheral corner 110 to point 301.

[0024] As shown in FIG. 2, the chip-forming surface 108 extends radially relative to the longitudinal axis of the metal-cutting drill tool 100 a distance w≧Dc / 4, where Dc is the diameter of the metal-cutting drill tool 100.

[0025] FIG. 2 shows that the tip forming surface 108 is perpendicular to the bottom of the insert seat 106 over its entire length.

[0026] 2 also shows the radial distance d1 from the top 201 of the insert 104 to the chip forming surface 108. This radial distance d1 is d1=Dc·P, where P is 0.04≦P≦0.08, and Dc is the diameter of the drill tool 100. This distance d1 is important for chip evacuation, and P is preferably 0.04≦P≦0.06.

Claims

1. an elongated drill body (101) having a drilling shaft (102) and a mounting shank (103); a central drill insert (104) mounted on the distal end (105) of the drilling shaft (102) in an insert seat (106), the insert seat (106) configured to hold the central drill insert (104) against a bottom of the insert seat (106); a drill flute (107) of the drilling shaft (102) configured to guide and form a tip from the central drill insert (104), the drill flute (107) including a tip-forming surface (108) at a distal end (109) of the drill flute (107); A metal-cutting indexable drill tool (100) comprising: the tip forming surface (108) is perpendicular to the bottom of the insert seat (106) for the central drill insert (104); a peripheral corner (110) of the central drill insert (104) being the radially outermost and axially outermost corner of the central drill insert (104) relative to the indexable metal-cutting drill tool (100); A curve (302) is formed by the intersection of the tip forming surface (108) and an imaginary inscribed sphere (309); A point (301) on the curve (302) is on the midpoint of the curve (302), the tip forming surface (108) is located at a distance X from the peripheral corner (110) to the point (301) on the curve (302); the center of the distal end (105) on the cross section of the drilling shaft (102) is the intersection of the distal end (105) on the cross section of the drilling shaft (102) and a rotation centerline of the metal-cutting indexable drill tool (100); the center (303) of the imaginary inscribed sphere (309) and the center of the distal end (105) on the cross section of the drilling shaft (102) are located on the rotation centerline of the metal-cutting indexable drill tool (100); the radius of the imaginary inscribed sphere is defined by the peripheral corner (110); The distance X divided by the diameter of the drill tool Dc is equal to the tip parameter A, which indicates the ratio of the tip diameter to the drill hole diameter, 10. An indexable drill tool (100) for metal cutting, characterized in that the tip parameter A is in the range of 0.3≦A≦0.

5.

2. 2. The indexable metal cutting drill tool (100) of claim 1, wherein the tip parameter A is 0.37≦A.

3. 3. The indexable drill tool (100) for metal cutting according to claim 1 or 2, characterized in that the tip parameter A is A≦0.

42.

4. 4. The metal cutting indexable drill tool (100) of claim 1, wherein the chip forming surface (108) extends radially relative to a longitudinal axis of the metal cutting indexable drill tool (100) a distance w≧Dc / 4, where Dc is a diameter of the metal cutting indexable drill tool (100).

5. 5. The metal-cutting indexable drill tool (100) according to claim 1, wherein the chip-forming surface (108) is perpendicular to the bottom of the insert seat (106) along the entire length of the chip-forming surface (108).

6. 6. The metal cutting indexable drill tool (100) of claim 1, wherein the radial distance d1 from the top of the central drill 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 metal cutting indexable drill tool (100).

7. 7. The metal cutting indexable drill tool (100) of claim 1, wherein the radial distance d1 from the top of the central drill 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 metal cutting indexable drill tool (100).

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