Variable curvature drum milling cutter

Abstract

The present invention relates to a variable curvature drum milling cutter, comprising a shank portion and a cutting portion, wherein the cutting portion comprises a ball-end cutting edge for fine milling of blades and a drum-shaped cutting edge for rough milling of blades to remove excess, wherein the ball-end cutting edge is located at the tip of the drum milling cutter; a plane coordinate system is established with the end point of the ball-end cutting edge as the origin O, a tangent of a generatrix S1 of the ball-end cutting edge at the end point of the blade as the X-axis, and a center axis O-O of the shank portion as the Y-axis, wherein the generatrix S2 of the drum-shaped cutting edge satisfies a cubic parabola equation in the coordinate system, i.e., the generatrix S2 of the drum-shaped cutting edge of the drum milling cutter provided by the present invention is a part of a cubic parabola, and therefore, four constants a, b, c, d of the parabola can be adjusted according to different blade curved surface shapes, thereby adjusting the curvature radius at different positions on the drum-shaped cutting edge, thereby avoiding interference and overcutting when milling blades.

Description

Technical Field

[0001] The invention relates to the field of metal cutting, in particular to a drum milling cutter. Background Art

[0002] Blades and integral impellers are core components of turbine generators, turbocharged engines, and turbofan engines. They are widely used in energy, aerospace, petrochemical and other industries. The machining accuracy, surface quality and efficiency of the blade profile directly affect the aerodynamic performance and mechanical efficiency of the engine, and have a decisive influence on the engine performance. There are generally two types of blade profiles, namely straight surface blades and complex curved surface blades. Regardless of the type of blade, a five-axis machining center must be used with special tools for processing. The most advanced special tool at present is the drum milling cutter.

[0003] Authorization announcement number CN1186157C discloses a drum-cone tool and a method for machining a centrifugal impeller with a complex curved surface. The cutting part of the tool is a rotating surface, and the generatrix is ​​a circular arc with a radius of R. The bottom of the tool has no cutting edge. The drum-shaped tool has higher machining efficiency than a ball-end milling cutter and greater rotation flexibility than a taper milling cutter, which can easily avoid overcutting and collision that may occur during machining. The main defect is that there is no cutting edge at the bottom, and rough and fine machining cannot be completed at one time.

[0004] Application publication number CN110695426A discloses a high-efficiency drum-shaped profiling end mill, whose cutting part is divided into a circumferential cutting edge and a ball-end cutting edge. The circumferential cutting edge profile consists of two symmetrical arcs, and the bottom cutting edge is a ball-end cutting edge. The drum-shaped milling cutter can greatly improve the semi-finishing and finishing efficiency of workpieces, can process narrow workpieces, has high strength and long service life.

[0005] Application publication number CN107243668A discloses a drum-shaped alloy milling cutter, the side of the cutter body of which is an arc-shaped milling edge, the arc-shaped milling edge is a rotating surface, the generatrix is ​​an arc with a radius of R, and the center of the arc is located on a plane passing through the midpoint of the arc and perpendicular to the axis of the tool rod.

[0006] Application publication number CN114888342A discloses a method for machining blisk blades using a drum-shaped cutter, wherein the cutting edge of the drum-shaped cutter is composed of a tip with an arc radius of R1 and a side edge with an arc radius of R2.

[0007] The side blades of these drum milling cutters are all composed of one or more arcs, and all have the problem of a small range of blade adjustment parameters. The only adjustable parameter is the arc radius R, and the curvature radius is fixed. During processing, if interference or overcutting occurs, it is difficult to adjust, which limits the further improvement of the processing efficiency of the drum milling cutter. Summary of the invention

[0008] The purpose of the present invention is to avoid the shortcomings of the prior art and provide a variable curvature drum milling cutter that can adjust the curvature radius at different positions on the drum-shaped cutting edge to avoid interference and overcutting when milling blades, can complete rough and fine machining at one time, has high edge strength and long tool life.

[0009] To achieve the above object, the technical solution adopted by the present invention is: a variable curvature drum milling cutter, comprising a shank portion and a cutting portion, wherein the cutting portion comprises a ball-end cutting edge for fine milling of blades and a drum-shaped cutting edge for rough milling of blades to remove excess, wherein the ball-end cutting edge is located at the tip of the drum milling cutter;

[0010] The ball-end cutting edge is obtained by rotating the generatrix S1 of the ball-end cutting edge around the center axis OO of the shank, and the drum-shaped cutting edge is obtained by rotating the generatrix S2 of the drum-shaped cutting edge around the center axis OO of the shank, and the generatrix S1 of the ball-end cutting edge and the generatrix S2 of the drum-shaped cutting edge are tangent to each other, so as to reduce the excessive arc and ensure that the entire cutting portion has no sharp points, reduce stress concentration, and improve the edge strength and tool life;

[0011] With the end point of the ball-end cutting edge as the origin O, the tangent of the generatrix S1 of the ball-end cutting edge at the end point of the cutting edge as the X-axis, and the center axis OO of the shank as the Y-axis, a plane coordinate system is established, in which the generatrix S2 of the drum-shaped cutting edge satisfies the cubic parabola equation:

[0012] y=ax 3 +bx 2 +cx+d,

[0013] Among them, a, b, c, d are all constants, and a∈(-5, 0), b∈(-50, 0), c∈(-200, -20), d∈(-200, -20), which are used to prevent interference and overcutting when a variable curvature drum milling cutter with a shank diameter of 12 to 20 mm mills blades according to different blade surface shapes.

[0014] The drum-shaped cutting edge includes at least two spiral blades formed by spiral rotation around the center axis OO of the shank, and a chip groove is provided between the two spiral blades. The chip groove is also a spiral chip groove formed by rotating around the center axis OO of the shank and continuously extending along the two spiral blades.

[0015] Furthermore, the chip groove extends from the rear of the ball-end cutting edge to the end of the drum-shaped cutting edge, and the helix angle of the chip groove is 10° to 45°.

[0016] Furthermore, the diameter of the drum-shaped cutting edge gradually increases from the top end of the cutting edge to the shank.

[0017] Furthermore, the center of the ball-end cutting edge is located on the center axis OO of the shank.

[0018] Furthermore, the cutting part and the shank of the drum milling cutter are both made of solid carbide, wherein a Ti-Al-N or Ti-Al-Si-N or Al-Cr-N coating is attached to the surface of the cutting part.

[0019] Furthermore, the cemented carbide is a tungsten-cobalt cemented carbide or a tungsten-cobalt-titanium cemented carbide or a general-purpose cemented carbide.

[0020] Furthermore, the diameter of the shank portion (3) is 20 mm, the radius of the ball-end cutting edge is 4 mm, and the generatrix S2 of the drum-shaped cutting edge satisfies the equation y=-0.4952x 3 -9.0253x 2 -57.1091x-111.5981.

[0021] Furthermore, the diameter of the shank portion (3) is 12 mm, the radius of the ball-end cutting edge is 2.4 mm, and the generatrix S2 of the drum-shaped cutting edge satisfies the equation y=-2.524x 3 -27.6595x 2 -98.3775x-108.4305.

[0022] Furthermore, the diameter of the shank portion (3) is 16 mm, the radius of the ball-end cutting edge is 4 mm, and the generatrix S2 of the drum-shaped cutting edge satisfies the equation y=-0.8611x 3 -12.9428x 2 -66.9503x-106.4261.

[0023] The beneficial effect of the present invention is that the drum cutting edge generatrix S2 of the drum milling cutter provided by the present invention is a part of a cubic parabola. Therefore, the four constants a, b, c, and d of the parabola can be adjusted according to the different blade surface shapes, thereby adjusting the curvature radius at different positions on the drum cutting edge to avoid interference and overcutting when milling the blades.

[0024] Secondly, the drum-shaped cutting edge is used for rough milling of blades to remove excess, and the ball-end cutting edge is used for fine milling of blades. One tool can complete the rough and fine processing of blades, reducing tool change time and improving processing efficiency;

[0025] In addition, the generatrix S1 and S2 of the ball-end cutting edge and the drum-shaped cutting edge are directly tangent, which, on the one hand, reduces the excessive arc and simplifies the drum milling cutter structure; on the other hand, ensures that the entire cutting part has no sharp points, reduces stress concentration, and is beneficial to improving the edge strength and increasing the tool life. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A structural diagram of a variable curvature drum-shaped milling cutter of the present invention;

[0027] Figure 2 It is a schematic diagram of the generatrix of the cutting part of a variable curvature drum-shaped milling cutter of the present invention;

[0028] Figure 3 It is the position of the generatrix S1 and S2 of the variable curvature drum milling cutter of the present invention in the coordinate system.

[0029] Numbers in the figure:

[0030] 1. Cutting part; 2. Chip groove; 3. Shank; 11. Ball-end cutting edge; 12. Drum-shaped cutting edge. DETAILED DESCRIPTION

[0031] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0032] In order to achieve the above object, the present invention provides the following specific implementation methods:

[0033] Embodiment 1: A variable curvature drum milling cutter, comprising a shank portion 3 and a cutting portion 1, wherein the cutting portion 1 comprises a ball-end cutting edge 11 for fine milling of blades and a drum-shaped cutting edge 12 for rough milling of blades to remove excess, wherein the ball-end cutting edge 11 is located at the tip of the drum milling cutter; the diameter of the drum-shaped cutting edge 12 gradually increases from the top of the blade to the shank portion 3. The center of the ball-end cutting edge 11 is located on the central axis OO of the shank portion 3.

[0034] The ball-end cutting edge 11 is obtained by rotating the generatrix S1 of the ball-end cutting edge 11 around the central axis OO of the shank 3, and the drum-shaped cutting edge 12 is obtained by rotating the generatrix S2 of the drum-shaped cutting edge 12 around the central axis OO of the shank 3, and the generatrix S1 of the ball-end cutting edge 11 and the generatrix S2 of the drum-shaped cutting edge 12 are tangent to each other, so as to reduce excessive arcs and ensure that the entire cutting portion 1 has no sharp points, reduce stress concentration, and improve edge strength and tool life;

[0035] With the end point of the ball-end cutting edge 11 as the origin O, the tangent of the generatrix S1 of the ball-end cutting edge 11 at the end point of the cutting edge as the X-axis, and the center axis OO of the shank 3 as the Y-axis, a plane coordinate system is established, in which the generatrix S2 of the drum-shaped cutting edge 12 satisfies the cubic parabola equation:

[0036] y=ax 3 +bx 2 +cx+d,

[0037] Among them, a, b, c, d are all constants, and a∈(-5, 0), b∈(-50, 0), c∈(-200, -20), d∈(-200, -20), which are used to prevent interference and overcutting when a variable curvature drum milling cutter with a shank diameter of 12 to 20 mm mills blades according to different blade surface shapes.

[0038] The drum-shaped cutting edge 12 includes at least two spiral blades formed by spiral rotation around the central axis OO of the shank 3, and a chip groove 2 is provided between the two spiral blades. The chip groove 2 is also a spiral chip groove formed by rotating around the central axis OO of the shank 3 and continuously extending along the two spiral blades; the chip groove 2 extends from the rear of the ball-end cutting edge 11 to the end of the drum-shaped cutting edge 12, and the helix angle of the chip groove 2 is 10° to 45°.

[0039] The cutting part 1 and the shank 3 of the drum milling cutter are both made of solid cemented carbide, wherein the surface of the cutting part 1 is coated with Ti-Al-N or Ti-Al-Si-N or Al-Cr-N; the cemented carbide is tungsten-cobalt cemented carbide or tungsten-cobalt-titanium cemented carbide or general cemented carbide.

[0040] The diameter of the shank 3 is 20 mm, the radius of the ball-end cutting edge 11 is 4 mm, and the generatrix S2 of the drum-shaped cutting edge 12 satisfies the equation y=-0.4952x 3 -9.0253x 2 -57.1091x-111.5981.

[0041] Figure 1 and Figure 2 An embodiment of a variable curvature drum milling cutter of the present invention is shown, comprising a cutting portion 1, a chip groove 2 and a shank 3, wherein the cutting portion 1 comprises a ball-end cutting edge 11 and a drum-shaped cutting edge 12, wherein the ball-end cutting edge 11 is formed by rotating a generatrix S1 around the center axis OO of the shank 3, and the drum-shaped cutting edge 12 is formed by rotating a generatrix S2 around the center axis OO of the shank 3, and the generatrix S1 and S2 are tangent to each other. Figure 3 The present invention shows a variable curvature drum milling cutter, the radius of the ball-end cutting edge 11 is 4 mm, and the generatrix S2 of the drum cutting edge 12 satisfies the equation y=-0.4952x 3 -9.0253x 2 -57.1091x-111.5981.

[0042] Embodiment 2: Same as Embodiment 1, except that the diameter of the shank 3 is 12 mm, the radius of the ball-end cutting edge 11 is 2.4 mm, and the generatrix S2 of the drum-shaped cutting edge 12 satisfies the equation y=-2.524x 3 -27.6595x 2-98.3775x-108.4305.

[0043] Embodiment 3: Same as Embodiment 1, except that the diameter of the shank 3 is 16 mm, the radius of the ball-end cutting edge 11 is 4 mm, and the generatrix S2 of the drum-shaped cutting edge 12 satisfies the equation y=-0.8611x 3 -12.9428x 2 -66.9503x-106.4261.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A variable curvature drum milling cutter, characterized in that: The tool comprises a handle portion (3) and a cutting portion (1), wherein the cutting portion (1) comprises a ball-end cutting edge (11) for fine milling of blades and a drum-shaped cutting edge (12) for rough milling of blades to remove excess, wherein the ball-end cutting edge (11) is located at the tip of the drum-shaped milling cutter; The ball-end cutting edge (11) is obtained by rotating the generatrix (S1) of the ball-end cutting edge (11) around the central axis OO of the shank (3), and the drum-shaped cutting edge (12) is obtained by rotating the generatrix (S2) of the drum-shaped cutting edge (12) around the central axis OO of the shank (3), and the generatrix (S1) of the ball-end cutting edge (11) and the generatrix (S2) of the drum-shaped cutting edge (12) are tangent to each other, so as to reduce excessive arcs and ensure that the entire cutting portion (1) has no sharp points, reduce stress concentration, and improve edge strength and tool life; With the end point of the ball-end cutting edge (11) as the origin O, the tangent of the generatrix (S1) of the ball-end cutting edge (11) at the end point of the cutting edge as the X-axis, and the center axis OO of the shank (3) as the Y-axis, a plane coordinate system is established, in which the generatrix (S2) of the drum-shaped cutting edge (12) satisfies the cubic parabola equation: y=ax 3 +bx 2 +cx+d, Among them, a, b, c, d are all constants, and a∈(-5, 0), b∈(-50, 0), c∈(-200, -20), d∈(-200, -20), which are used to prevent interference and overcutting when a variable curvature drum milling cutter with a shank diameter of 12 to 20 mm mills blades according to different blade surface shapes.

2. The variable curvature drum milling cutter according to claim 1, characterized in that: The drum-shaped cutting edge (12) comprises at least two spiral blades formed by spirally rotating around the central axis OO of the shank (3), and a chip groove (2) is provided between the two spiral blades. The chip groove (2) is a spiral chip groove formed by rotating around the central axis OO of the shank (3) and continuously extending along the two spiral blades.

3. The variable curvature drum milling cutter according to claim 2, characterized in that: The chip groove (2) extends from the rear of the ball-end cutting edge (11) to the end of the drum-shaped cutting edge (12), and the helix angle of the chip groove (2) is 10° to 45°.

4. The variable curvature drum milling cutter according to claim 1, characterized in that: The diameter of the drum-shaped cutting edge (12) gradually increases from the top end of the cutting edge to the shank (3).

5. The variable curvature drum milling cutter according to claim 1, characterized in that: The center of the ball-end cutting edge (11) is located on the center axis OO of the shank (3).

6. The variable curvature drum milling cutter according to claim 1, characterized in that: The cutting part (1) and the shank (3) of the drum milling cutter are both made of solid hard alloy, wherein a Ti-Al-N or Ti-Al-Si-N or Al-Cr-N coating is attached to the surface of the cutting part (1).

7. The variable curvature drum milling cutter according to claim 6, characterized in that: The hard alloy is tungsten-cobalt hard alloy or tungsten-cobalt-titanium hard alloy or general hard alloy.

8. The variable curvature drum milling cutter according to any one of claims 1 to 7, characterized in that: The diameter of the shank (3) is 20 mm, the radius of the ball-end cutting edge (11) is 4 mm, and the generatrix (S2) of the drum-shaped cutting edge (12) satisfies the equation y=-0.4952x 3 -9.0253x 2 -57.1091x-111.5981.

9. The variable curvature drum milling cutter according to any one of claims 1 to 7, characterized in that: The diameter of the shank (3) is 12 mm, the radius of the ball-end cutting edge (11) is 2.4 mm, and the generatrix (S2) of the drum-shaped cutting edge (12) satisfies the equation y=-2.524x 3 -27.6595x 2 -98.3775x-108.4305.

10. The variable curvature drum milling cutter according to any one of claims 1 to 7, characterized in that: The diameter of the shank (3) is 16 mm, the radius of the ball-end cutting edge (11) is 4 mm, and the generatrix (S2) of the drum-shaped cutting edge (12) satisfies the equation y=-0.8611x 3 -12.9428x 2 -66.9503x-106.4261.

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