A double-edge ball-end mill insert

Abstract

The application discloses a double-blade ball-end milling cutter blade, and relates to the field of machining and cutter design. The double-blade ball-end milling cutter blade comprises a blade base body, a positioning hole arranged in the middle part of the blade base body and a ball-end cutting edge arranged at the front end of the blade base body. The ball-end cutting edge comprises a first cutting edge and a second cutting edge. The first cutting edge and the second cutting edge are centrally divided along the direction of the cutter rotation axis and are distributed in a staggered manner in the radial direction, so that the first cutting edge and the second cutting edge do not coincide with each other in the spatial position. The double-blade ball-end milling cutter blade with the above structure is adopted. The central division and staggered structure design of the conventional blade ball-end blade shape make the ball-end cutting edge not pass through the position of r=0 near the rotation center, avoid the central zero linear velocity area in geometry, and improve the cutting state of the central area, the surface quality of the cut workpiece and the cutter life.

Description

Technical Field

[0001] This invention relates to the fields of machining and tool design, and in particular to a double-edged ball end mill insert. Background Technology

[0002] Ball end mills are widely used in the semi-finishing and finishing of precision parts such as complex curved surfaces and mold cavities due to their excellent surface forming capabilities. They are one of the key cutting tools in aerospace, automotive manufacturing, precision mold and other fields.

[0003] However, traditional ball end mills suffer from a long-standing technical flaw in their structure—the zero-velocity problem at the center. Specifically, as the ball end mill rotates around its axis, the radius of gyration *r* at each point on the cutting edge decreases as the distance from that point to the center of rotation decreases. When the cutting edge extends to the center of rotation, its radius of gyration *r* = 0. According to the cutting speed formula *v=ω×r*, the theoretical cutting speed at this position is *v=0*. This means that in the central region of the tool, the cutting edge cannot achieve effective shearing, and the material removal process is actually an abnormal cutting pattern dominated by extrusion and plowing.

[0004] This abnormal cutting pattern mainly brings two technical problems: First, in terms of processing quality, the extrusion and plowing in the central area will cause defects such as burrs, built-up edge, and scratches on the workpiece surface, which seriously affects the integrity and smoothness of the processed surface. Especially in the processing of precision molds and complex curved surfaces, such problems often directly lead to the scrapping of the workpiece or the addition of subsequent grinding processes.

[0005] Secondly, regarding tool performance, the intense compression and friction caused by the lack of effective cutting speed in the central area subject the tool's central part to extremely high contact stress and thermal load, leading to accelerated local wear and increased machining vibration, severely limiting tool life and machining stability. In actual use, this often results in the tool needing to be replaced before reaching its expected service life, increasing tool consumption costs and downtime for tool changes.

[0006] In summary, how to effectively avoid the position of the turning radius r=0 by the cutting edge of the ball end mill from the root level of geometric structure design, thereby completely eliminating the squeezing and plowing problems caused by the center zero speed, while ensuring that the strength of the tool structure is not weakened and maintaining good compatibility with existing machining equipment and process systems, has become a long-standing and urgent technical problem in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a double-edged ball end mill insert. By designing a central segmentation and offset structure for the ball end mill's cutting edge shape, the ball end mill cutting edge no longer passes through the position r=0 near the center of rotation, geometrically avoiding the zero linear velocity region in the center and improving the cutting condition, surface quality, and tool life in the central region.

[0008] To achieve the above objectives, the present invention provides a double-edged ball end mill insert, comprising an insert body, a positioning hole disposed in the middle of the insert body, and a ball end cutting edge disposed at the front end of the insert body. The ball end cutting edge comprises a first cutting edge and a second cutting edge. The first cutting edge and the second cutting edge are centrally divided along the tool rotation axis and are radially staggered, so that the first cutting edge and the second cutting edge do not coincide in spatial position.

[0009] Preferably, both the first cutting edge and the second cutting edge include a large circular arc edge, a small circular arc edge, and a straight edge. The large circular arc edge and the small circular arc edge are distributed in an arc shape along the outer surface of the ball head, and the straight edge is disposed at the transition between the ball head and the base. The three edges are connected to form their own independent cutting edge trajectories.

[0010] Preferably, the first cutting edge and the second cutting edge are each independently provided with a rake face, a main flank face and a secondary flank face, wherein the main flank face and the secondary flank face are used to support the large arc cutting edge to participate in cutting during the cutting process.

[0011] Preferably, the first cutting edge and the second cutting edge distribute the cutting load, which was originally concentrated at the center of the ball head, to the two cutting edges, thereby reducing the peak contact stress and wear rate in the central region of the insert.

[0012] Preferably, the cutting blade engages with the mounting groove of the ball end mill body through the positioning hole to achieve precise radial and axial positioning and clamping.

[0013] Preferably, the first cutting edge and the second cutting edge alternate cutting in the central region of the ball head, so that the material removal in the central region is completed by the first cutting edge and the second cutting edge in turn, avoiding the continuous squeezing and plowing phenomenon caused by a single cutting edge.

[0014] Preferably, the blade is a replaceable structure, so that only the blade needs to be replaced after wear, without replacing the blade body.

[0015] The beneficial effects of this invention are: By employing a center-segmented and offset structural design for the ball end cutting edge, the geometric point r=0, which the conventional continuous cutting edge of a ball end inevitably passes through at the center of rotation, is eliminated from the cutting edge trajectory. The linear velocity of the cutting edge decreases closer to the tool tip, and the linear velocity at each point is not equal to zero. This ensures that no cutting edge coincides with the r=0 position near the tool's center of rotation, geometrically avoiding the generation of a zero-linear-velocity region at the center. When the minimum turning radius is structurally raised to At this time, the central area of ​​the ball head can obtain an effective linear velocity, which fundamentally improves the cutting state of the central area, which is mainly extrusion or plowing, reduces the risk of burrs, built-up edge and surface scratches, and significantly improves machining stability and tool life.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a double-edged ball end mill insert according to the present invention; Figure 2 This is a front view of a double-edged ball end mill insert according to the present invention; Figure 3 This is a top view of a double-edged ball end mill insert according to the present invention; Figure 4 This is a left view of a double-edged ball end mill insert according to the present invention; Figure 5 This is a cross-sectional view of a double-edged ball end mill insert according to the present invention; Figure 6 This is a schematic diagram of the blade cutting process; Figure 7 This is a schematic diagram of the cutting profile of the blade; Figure 8 This is a top view of the cutting profile of the blade; Figure 9 This is a detailed view of the cutting edge of the blade.

[0018] Among them, 1. positioning hole; 2. first cutting edge; 3. rake face; 4. large arc cutting edge; 5. small arc cutting edge; 6. main flank face; 7. secondary flank face; 8. second cutting edge; 9. straight cutting edge. Detailed Implementation

[0019] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0020] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0022] Example like Figure 1-9 As shown, a double-edged ball end mill insert includes an insert body, a positioning hole 1 located in the middle of the insert body, and a ball end cutting edge located at the front end of the insert body. The insert body is used for detachable connection with the ball end mill body, and the positioning hole 1 is used to cooperate with the corresponding mounting groove of the ball end mill body to achieve precise positioning and clamping of the insert in the radial and axial directions.

[0023] The ball end cutting edge includes a first cutting edge 2 and a second cutting edge 8. The first cutting edge 2 and the second cutting edge 8 are centrally divided along the tool rotation axis and are radially staggered, so that the first cutting edge 2 and the second cutting edge 8 do not coincide, coplanar, or circular in spatial position, thereby forming an interlaced effective cutting trajectory in the central region of the ball end. The dividing surface is located on both sides of the tool rotation axis, so that the originally continuous ball end cutting edge is decomposed into two independent ball end cutting edge bands.

[0024] Both the first cutting edge 2 and the second cutting edge 8 include a large circular arc edge 4, a small circular arc edge 5, and a straight edge 9. The large circular arc edge 4 and the small circular arc edge 5 are distributed in an arc shape along the outer surface of the ball head, and the straight edge 9 is set at the transition between the ball head and the base. The three edges connect to form their own independent cutting edge trajectories. The first cutting edge 2 and the second cutting edge 8 are each independently provided with a rake face 3, a primary flank face 6, and a secondary flank face 7. The primary flank face 6 and the secondary flank face 7 are used to support the large circular arc edge 4 during the cutting process.

[0025] like Figure 6 As shown, when the cutting tool rotates at a speed of N and simultaneously feeds linearly at a feed rate of V, the trajectory of any point on the cutting edge relative to the workpiece coordinate system is a composite trajectory formed by the combined action of the tool's rotation and the tool's feed motion relative to the workpiece. Near the lowest point of contact between the tool and the workpiece, it can be equivalent to a circular arc trajectory.

[0026] When the tool rotates and participates in cutting, the first cutting edge 2 and the second cutting edge 8 alternately remove material from the workpiece near the center of the ball end mill, eliminating the continuous squeezing and plowing phenomenon caused by a single cutting edge in the central area, as is common in traditional ball end mills. This is because the minimum turning radius of both the first cutting edge 2 and the second cutting edge 8 meets the requirements... This ensures that there is always an effective cutting speed in the center area of ​​the ball head when the tool rotates, thereby avoiding built-up edge, burrs and surface scratches caused by zero cutting speed.

[0027] During the cutting process in this embodiment, the first cutting edge 2 and the second cutting edge 8 form an effective cutting ring with a limited width in the central region of the ball head. This structural feature transforms the point contact cutting of the central region of the ball head from the point contact cutting of traditional tools into strip contact cutting. By increasing the effective area of ​​the contact area, the local contact stress and the degree of frictional heat concentration are significantly reduced, and the stress and heat conditions of the cutting tool are improved.

[0028] At the same time, due to the staggered arrangement of the first cutting edge 2 and the second cutting edge 8, the cutting mechanism in the central region of the ball end mill has undergone a fundamental change: it has changed from plowing and squeezing in the central region by traditional ball end mills to shearing removal, thereby reducing the tendency of built-up edge formation, significantly improving the surface quality of the machined surface, and making the machined surface smoother and flatter.

[0029] In terms of load distribution, the staggered arrangement of the first cutting edge 2 and the second cutting edge 8 disperses the cutting load that was originally concentrated at the center of the ball head to the two staggered cutting edge bands, effectively reducing the peak contact stress in the center area of ​​the insert, making the wear distribution more uniform, significantly slowing down the local wear rate in the center area, and extending the service life of the insert.

[0030] In terms of thermal management, the misaligned ball end cutting edge splits the frictional heat generated in the central area of ​​the ball end from a single concentrated heat source in traditional cutting tools into multiple dispersed heat sources, effectively reducing the peak heat flux density in the central area, avoiding local overheating, and significantly improving the thermal stability and thermal fatigue resistance of the cutting edge under high-speed cutting conditions.

[0031] In this embodiment, for a cutting blade with thickness H and radius R, the actual cutting radius of the workpiece is given by the formula... Confirmed. Figure 7 As shown, the radius of its bottom cutting plane Determined by the blade thickness H, i.e. In the pre-cutting preparation work, the programming should be based on the rotational profile of the cutting tool.

[0032] When the insert is mounted on the ball end mill body and rotates with the spindle, the double-edged offset ball end mill structure can ensure an effective cutting speed in the central area of ​​the ball end mill under various tool paths and machining postures, except for axial cutting from top to bottom, which significantly improves the surface quality and machining stability in complex curved surfaces and precision machining.

[0033] The double-edged ball end mill insert of this application adopts a replaceable structure. When the insert wears out, the insert can be replaced individually without replacing the entire cutter. Compared with traditional solid ball end mills, it can significantly reduce material consumption and usage costs, while achieving a structural improvement in ball end mill cutting performance while keeping the original cutter body and machine tool system unchanged.

[0034] Therefore, the present invention adopts a double-edged ball end mill insert with the above-mentioned structure. By designing the center division and misalignment structure of the ball end mill's cutting edge shape of the conventional insert, the ball end cutting edge no longer passes through the position r=0 near the center of rotation, thus geometrically avoiding the zero linear velocity region in the center and improving the cutting state, surface quality and tool life in the center region.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A double-edged ball end mill insert, characterized in that: The tool includes a cutting tool body, a positioning hole in the middle of the cutting tool body, and a ball-end cutting edge in the front end of the cutting tool body. The ball-end cutting edge includes a first cutting edge and a second cutting edge. The first cutting edge and the second cutting edge are centrally divided along the tool rotation axis and are radially staggered so that the first cutting edge and the second cutting edge do not coincide in spatial position.

2. The double-edged ball end mill insert according to claim 1, characterized in that: Both the first cutting edge and the second cutting edge include a large circular arc edge, a small circular arc edge, and a straight edge. The large circular arc edge and the small circular arc edge are distributed in an arc shape along the outer surface of the ball head, and the straight edge is set at the transition between the ball head and the base. The three are connected to form their own independent cutting edge trajectories.

3. A double-edged ball end mill insert according to claim 2, characterized in that: The first cutting edge and the second cutting edge are each independently provided with a rake face, a main flank face and a secondary flank face, wherein the main flank face and the secondary flank face are used to support the large arc cutting edge to participate in the cutting process.

4. A double-edged ball end mill insert according to claim 3, characterized in that: The first and second cutting edges disperse the cutting load, which was originally concentrated at the center of the ball head, onto the two cutting edges, reducing the peak contact stress and wear rate in the central region of the insert.

5. A double-edged ball end mill insert according to claim 4, characterized in that: The cutting blade engages with the mounting groove of the ball end mill body through the positioning hole, achieving precise radial and axial positioning and clamping fixation.

6. A double-edged ball end mill insert according to claim 5, characterized in that: The first cutting edge and the second cutting edge alternately cut in the central region of the ball head, so that the material removal in the central region is completed by the first cutting edge and the second cutting edge in turn, avoiding the continuous squeezing and plowing phenomenon caused by a single cutting edge.

7. A double-edged ball end mill insert according to claim 6, characterized in that: The blade is replaceable; once worn, only the blade needs to be replaced, without replacing the blade body.

Images