A high-efficiency ball-end milling cutter for rough machining

Abstract

A high-efficiency roughing ball-end mill comprises a cutter body with a concave chip groove at the center of the bottom blade of the cutter body, enabling a positive or zero-degree cutting rake angle. The chip groove has a centrally symmetrical or asymmetrical structure, and its cross-sectional projection comprises a bottom segment and two side segments. The bottom segment connects between the inner ends of the two side segments, and the side segments are arc-shaped. This invention prevents direct contact between the center of the bottom blade and the workpiece being machined, thereby increasing tool life and increasing the chip storage and cooling space of the bottom blade.

Description

Technical Field

[0001] The invention relates to the field of machining and manufacturing cutting tools, in particular to a high-efficiency ball-end milling cutter for rough machining. Background Art

[0002] Ball end mills are widely used in profiling in mold, vehicle and aviation industries. With the development of processing and manufacturing technology, higher requirements are placed on the service life and processing efficiency of ball end mills. However, for difficult-to-process materials such as titanium alloys, high-temperature alloys and high-hardness steel, see Figure 1 、 Figure 2 , ball end mills have the following problems during rough machining:

[0003] 1. Due to the limitations of conventional ball end milling cutter design, the AA section at the bottom edge center 2 of the conventional ball end milling cutter 1 is shown in Figure 3 , the cutting back angle a is positive, but the cutting front angle b is negative, which causes the center of the bottom edge to easily break during rough machining, resulting in premature tool failure and even scrapping of the machined parts;

[0004] 2. Since the center of the bottom edge of conventional ball end mills is prone to chipping, the method of reducing processing efficiency is usually adopted, resulting in reduced production efficiency;

[0005] 3. During rough machining, since more chips and greater cutting heat are generated, the bottom edge of the ball end mill requires a larger space for chip accommodation and to ensure cooling of the cutting fluid. Summary of the Invention

[0006] The main purpose of the present invention is to overcome the defect of the existing ball-end milling cutter in the rough machining that the bottom blade center is easy to break, and to propose a rough machining efficient ball-end milling cutter to avoid the bottom blade center from being damaged during machining and to increase the service life of the tool.

[0007] The present invention adopts the following technical solutions:

[0008] A high-efficiency ball-end mill for rough machining, comprising a cutter body, characterized in that: an inwardly concave chip groove is provided at the center of the bottom edge of the cutter body so that the cutting front angle is a positive angle or 0 degree; the chip groove is a centrally symmetrical structure or an asymmetrical structure and its cross-sectional projection is provided with a bottom surface segment and two side surface segments, the bottom surface segment is connected between the inner ends of the two side surface segments, and the side surface segments are circular arcs.

[0009] Preferably, the bottom surface segment is a straight line or a curve, or is formed by connecting multiple straight lines and / or curves.

[0010] Preferably, the minimum radius of the two side segments is r min , the maximum machining angle γ of the tool body must satisfy the following relationship:

[0011] (1-cosβ)r min+r min sinβ·tanγ=Dtanγ

[0012] Wherein, D is the distance between the centers of the two side segments, and β is the angle between the tangents at the endpoints of both sides of the side segment.

[0013] Preferably, the outer end of the side segment is connected to a transition segment, and the transition segment extends outward along the outer end of the side segment and toward the concave direction of the chip groove.

[0014] Preferably, the transition segment is a combination of one or more of a circular arc, an elliptical arc, a parabola segment, or a straight line.

[0015] Preferably, the minimum radius of the two side segments is r min , its value range is 0.02%R≤r min ≤0.1%R, where R is the radius of the cutting portion of the tool body.

[0016] Preferably, the depth of the chip groove from the bottom edge is H, the value range of H is 0.02%R≤H≤0.2%R, and H≥r min .

[0017] Preferably, the center distance D between the two side segments is in the range of 0.01%R≤D≤0.1%R, where R is the radius of the cutting portion of the tool body.

[0018] Preferably, the bottom blade of the blade body has an even number of blades of 2 or more.

[0019] Preferably, the cutter body is made of a composite of one or more materials selected from high-speed steel, cemented carbide, ceramic and diamond.

[0020] From the above description of the present invention, it can be seen that compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. In the present invention, a chip groove design is adopted at the bottom edge center of the cutting part of the cutter body, so that the cutting front angle is a positive angle or 0 degree, thereby avoiding the situation where the bottom edge center directly contacts the processed parts and is easily damaged when the cutter body is rough-machining difficult-to-machining materials such as titanium alloys and high-temperature alloys, thereby improving the service life of the tool.

[0022] 2. In the present invention, the chip groove is provided to increase the chip holding space and cooling space of the bottom edge, which is more conducive to the discharge of chips. At the same time, it is beneficial to the cooling of the bottom edge of the tool body and the workpiece, reducing cutting heat, so that the tool body can perform processing at a higher speed and a greater cutting depth, thereby improving the rough processing efficiency of the tool.

[0023] 3. In the present invention, the chip groove adopts a multi-segment line design, including a bottom segment and a side segment. The side segment adopts an arc design to improve the strength of both ends of the chip groove and make the bottom edge cutting angle a positive angle or 0 degrees, thereby increasing the service life of the tool and increasing the processing angle range of the milling cutter's contour milling, ensuring the adaptability of the milling cutter to complex processing conditions and improving processing efficiency.

[0024] 4. In the present invention, a transition section is provided at the outer end of the side section. The transition section is a combination of one or more of a circular arc, an elliptical arc, a parabolic segment, or a straight line, so that the cutter body can produce thinner chips when moving the same distance horizontally during face milling. Therefore, a higher feed speed can be used to increase the milling efficiency of the tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the bottom edge of a conventional ball end mill;

[0026] Figure 2 for Figure 1 Magnified view of the bottom blade center;

[0027] Figure 3 for Figure 2 AA cross-sectional view;

[0028] Figure 4 A schematic diagram of the bottom edge of the blade body of the present invention;

[0029] Figure 5 Schematic diagram of the ball head radius of the cutter body of the present invention;

[0030] Figure 6 The center of the bottom blade of the present invention is enlarged Figure 1 ;

[0031] Figure 7 for Figure 6 AA cross-sectional view;

[0032] Figure 8 The center of the bottom blade of the present invention is enlarged Figure 2 ;

[0033] Figure 9 for Figure 8 BB cross-sectional view;

[0034] Figure 10 for Figure 9 The local structure diagram of

[0035] Figure 11 Schematic diagram of the machining angle of the cutter body;

[0036] in:

[0037] 10. Cutter body, 11. Cutting part, 12. Chip groove, 13. Bottom section, 14. Side section, 15. Transition section, 16. Bottom edge center, 17. Tool holder.

[0038] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0039] The present invention is further described below through specific embodiments.

[0040] In the present invention, the terms "first", "second", "third", etc. are only used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. In the description, the directions or positional relationships indicated by "upper", "lower", "left", "right", "front", and "back" are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and are not intended to indicate or imply that the device referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0041] In this application, unless otherwise specified, "plurality" refers to two or more. "And / or" describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. The character " / " generally indicates that the related objects are in an "or" relationship.

[0042] See also Figure 4-11 A high-efficiency ball-end mill for rough machining includes a cutter body 10 having a shank 17 and a cutting portion 11. The shank 17 is used to mount the tool. The cutting portion 11 is located at one end of the shank 17 and has a radius R. A chip groove 12 is provided at the bottom edge center 16 of the cutting portion 11 of the cutter body 10. The chip groove 12 is concave along the axial direction of the shank 17.

[0043] The chip groove 12 can make the cutting back angle a1 of the cutting portion 11 a positive angle and the cutting front angle b1 a positive angle or 0 degrees, thereby preventing the ball bottom edge center 16 from squeezing the processing surface and causing the bottom edge center 16 to be damaged. Figure 7 After the chip groove 12 is set, the cutting clearance angle a1 becomes a positive angle.

[0044] The chip groove 12 of the present invention is a central symmetrical structure or an asymmetrical structure. Figure 8 The cross-sectional projection in the BB direction is provided with a bottom segment 13 and two side segments 14 , and the bottom segment 13 is connected between the inner ends of the two side segments 14 . Figure 8The BB direction and Figure 6 The bottom surface segment 13 is a straight line or a curve, or is formed by connecting multiple straight lines and / or curves. The bottom surface segment 13 can constitute the main shape of the chip groove 12. The side surface segment 14 is an arc line, and the side surface segment 14 can be located on the top surface of the chip groove 12. The radii of the two side surface segments 14 can be the same or different. The radii of the two side surface segments 14 can be set to r1 and r2 respectively. If they are different, the minimum value of r1 and r2 is set to r1. min Setting the side segment 14 into an arc line can improve the strength of both ends of the chip groove 12, increase the machinable angle range of the cutter body 10, and ensure the adaptability of the milling cutter to complex machining conditions.

[0045] Furthermore, the outer ends of the side segments 14 are connected to transition segments 15. Specifically, the cross-sectional projection of the chip flute 12 in the BB direction further includes two transition segments 15, one located at the outer end of the side segments 14. The inner end of the side segments 14 is connected to the bottom segment 13. Each transition segment 15 is a combination of one or more of a circular arc, an elliptical arc, a parabolic segment, or a straight line, with a parabolic segment being a portion of a parabola. The transition segments 15 extend along the outer ends of the side segments 14 and inwardly toward the concave portion of the chip flute 12. The provision of transition segments 15 allows the cutter body 10 to produce thinner chips when moving the same horizontal distance during face milling. This allows for higher feed rates and improves tool milling efficiency.

[0046] The present invention will min The value range is set to 0.02% R≤r min ≤0.1%R. If r min If the size is too large, the chip groove 12 will be too large, which will reduce the workpiece accuracy and be detrimental to semi-finishing and finishing. min If the size is too small, the transition section 15 will be directly involved in the machining, and the bottom edge center 16 of the cutting portion 11 will be quickly damaged. Therefore, the machining angle of the cutter body 10 will be reduced, reducing the profiling capability of the ball end mill.

[0047] Furthermore, the minimum radius of the two side segments 14 of the present invention is r min To ensure the maximum machining angle γ of the cutter body 10, the following relationship must be satisfied:

[0048] (1-cosβ)r min +r min sinβ·tanγ=Dtanγ

[0049] Wherein, D is the distance between the centers of the two side surface segments 14, and β is the angle between the tangent lines at the endpoints of both sides of the side surface segment.

[0050] Furthermore, along the axial direction of the cutter body 10, the maximum distance between the chip flute 12 and the bottom edge is the chip flute 12 depth H, with the value range of H being 0.02%R≤H≤0.2%R, and H≥r. If H is too large, the milling cutter becomes more difficult to manufacture, resulting in a higher scrap rate, reduced cutter strength, and a shortened cutter lifespan.

[0051] Furthermore, the center distance between the two side segments of the chip flute 12 is D, and the value range of D is 0.01%R≤D≤0.1%R. If D is too large, the chip flute 12 will be too large, and the workpiece precision will be reduced. If D is too small, the machinable angle of the cutter body 10 will be reduced, reducing the profiling capability of the ball end mill.

[0052] In the present invention, the cutter body 10 is made of a composite of one or more materials selected from high-speed steel, cemented carbide, ceramics and diamond. The bottom edge of the cutter body 10 has an even number of edges of 2 or more.

[0053] The cutter of the present invention adopts a chip groove 12 design to avoid direct contact between the bottom blade center 16 and the workpiece being processed, improves the negative angle cutting of the bottom blade of a conventional ball-end milling cutter, avoids the situation where the bottom blade center 16 is easily damaged when a conventional ball-end milling cutter is rough-processing difficult-to-process materials such as titanium alloys and high-temperature alloys, and improves the service life of the tool.

[0054] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A high-efficiency ball-end milling cutter for rough machining, comprising a cutter body, characterized in that: The center of the bottom edge of the cutter body is provided with a concave chip groove so that the cutting front angle is a positive angle or 0 degree; the chip groove is a central symmetrical structure or an asymmetrical structure and its cross-sectional projection is provided with a bottom surface segment and two side surface segments, the bottom surface segment is connected between the inner ends of the two side surface segments, and the side surface segments are circular arcs; the minimum radius of the two side surface segments is r min , the maximum machining angle γ of the tool body must satisfy the following relationship: (1-cosβ)r min +r min sinβ·tanγ=Dtanγ Among them, D is the distance between the centers of the two side segments, β is the angle between the tangents at the endpoints of both sides of the side segment; the outer end of the side segment is connected to a transition segment, and the transition segment extends outward along the outer end of the side segment and toward the concave direction of the chip groove.

2. The high-efficiency ball-end milling cutter for rough machining according to claim 1, characterized in that: The bottom surface segment is a straight line or a curve, or is formed by connecting multiple straight lines and / or curves.

3. The high-efficiency ball-end milling cutter for rough machining according to claim 1, characterized in that: The transition section is a combination of one or more of a circular arc, an elliptical arc, a parabola segment, or a straight line.

4. The high-efficiency ball-end milling cutter for rough machining according to claim 1, characterized in that: The minimum radius of the two side segments is r min , its value range is 0.02%R≤r min ≤0.1%R, where R is the radius of the cutting portion of the tool body.

5. The high-efficiency ball-end milling cutter for rough machining according to claim 4, characterized in that: The depth of the chip groove from the bottom edge is H, and the value range of H is 0.02%R≤H≤0.2%R, and H≥r min .

6. The high-efficiency ball-end milling cutter for rough machining according to claim 1, characterized in that: The range of the center distance D between the two side segments is 0.01%R≤D≤0.1%R, where R is the radius of the cutting portion of the tool body.

7. The high-efficiency ball-end mill for rough machining according to claim 1, characterized in that: The bottom blade of the knife body has an even number of blades, which is more than 2.

8. The high-efficiency ball-end milling cutter for rough machining according to claim 1, characterized in that: The cutter body is made of a composite of one or more materials selected from high-speed steel, hard alloy, ceramic and diamond.

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