Shaping tools and methods for shaping workpieces

Abstract

A shaping tool for shaping and polishing a workpiece. The shaping tool comprises a hard shaping section for shaping a workpiece in use, which shapes the workpiece by the movement of the outward-facing surface of the hard shaping section and the surface of the workpiece relative to each other to remove material from at least a portion of the workpiece, and a polishing surface which is biasable toward a first position projecting toward an adjacent region of the outward-facing surface of the hard shaping section and movable toward a second position at the same height as the aforementioned adjacent region of the outward-facing surface of the hard shaping section. When the shaping tool is applied to a workpiece to remove material from the workpiece and to polish the workpiece, the polishing surface is biased toward the first position while moving toward that portion of the workpiece to polish that portion of the workpiece by contacting the portion of the workpiece from which the material has been removed by the hard shaping section.

Description

Technical Field

[0001] The present invention relates to a tool for shaping and polishing a workpiece. The tool according to an embodiment of the present invention is suitable for use in the manufacture of a variety of components such as lenses, semiconductor wafers, and artificial prostheses. The present invention also provides a method for shaping a workpiece.

Background Art

[0002] Manufacturing components with a smooth finish is a requirement in many industries. Examples of components that need to be shaped and smoothed include optical components such as lenses and mirrors, artificial prostheses, and semiconductor wafers. Typically, the manufacture of these components involves a multi-step process in which the component is shaped from an initial workpiece (e.g., by grinding, milling, or turning) and then polished to an increasingly smooth finish through successive polishing steps. Each step generally involves processing the workpiece using different tools that can sequentially provide a smoother finish, which is necessary to reduce the surface roughness to the required level but makes the manufacturing process complex and time-consuming.

[0003] Recently, the emergence of fine grinding processes such as Shape Adaptive Grinding (SAG) techniques has improved the speed of manufacturing some shaped components, which is because such processes can achieve both a high material removal rate and a high degree of smoothness. Examples of SAG tools and SAG processes are described in detail in WO2016 / 051121A1. Despite the advantages of SAG, these techniques are still typically incorporated as part of a multi-step process involving multiple tools and are thus plagued by limited throughput and a certain degree of complexity. Therefore, there is a need to further simplify component manufacturing and improve its speed.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] WO2016 / 051121A1 [Non-patent literature]

[0005] [Non-Patent Document 1] Pratap, A., Patra, K., and Dyakonov, AA, 2018, On-Machine Texturing of PCD Micro-Tools for Dry Micro-Slot Grinding of BK7 Glass, Precis.Eng., 55 (November 2018), pp. 491-502. [Non-Patent Document 2] Nagamatsu A (1985) Modal Analysis, Baihukan [Non-Patent Document 3] Altintas Y (2012) Manufacturing Automation, Cambridge University Press [Overview of the project] [Means for solving the problem]

[0006] A first aspect of the present invention is a shaping tool for shaping and polishing a workpiece, A rigid shaping part for shaping a workpiece during use, wherein the rigid shaping part removes material from at least a portion of the workpiece by the movement of the outward-facing surface of the rigid shaping part and the surface of the workpiece relative to each other; A polished surface that can be biased toward a first position protruding toward an adjacent region of the outward-facing surface of the hard shaped portion, and is movable toward a second position at the same height as the aforementioned adjacent region of the outward-facing surface of the shaped portion, Equipped with, A shaping tool is provided, wherein when the shaping tool is applied to a workpiece to remove material from the workpiece and to polish the workpiece, the polishing surface is biased toward a first position while moving toward that part of the workpiece so as to polish that part of the workpiece by contacting the part of the workpiece from which the material has been removed by the hard shaping part.

[0007] This tool combines a hard shaping section, capable of shaping a workpiece by removing material from it, and a polishing surface, capable of smoothing the portion of the workpiece shaped by the hard shaping section, into a single tool. The arrangement of the hard shaping section and the polishing surface as defined above (the polishing surface is biasable toward a first position projecting toward the adjacent surface of the hard shaping section) ensures that at least some of the areas of the workpiece shaped by the hard shaping section are subsequently polished by the polishing section as the shaping tool moves toward the workpiece. Once a portion of the workpiece is removed by the hard shaping section, the polishing surface, biased toward the first position at least during use, allows the polishing surface to remove a thin, further layer of excess material from the workpiece, leaving the polished surface intact. Thus, two types of operations (shaping and polishing), which previously required different tools and separate operations, can be performed in a single operation using the tool defined above. This significantly reduces the time required to manufacture components from workpieces, enabling faster and lower-cost component production.

[0008] The tools defined above have been shown to offer a further advantage by combining a polished surface and a hard shaping section, where the polished surface provides a damping effect against vibrations of the hard shaping section. This damping effect reduces chatter between the hard shaping section and the workpiece. Chatter—that is, vibration of the tool relative to the workpiece being shaped—can be a significant problem in shaping operations using hard tools, particularly grinding and cutting. Therefore, the presence of a polished surface improves the quality of shaping, even before any polishing is performed.

[0009] The relative movement of the outward-facing surface of the hard shaping component and the workpiece can most typically be achieved by rotation of the shaping tool around its axis of rotation, as will be shown with reference to several examples. However, in principle, the shaping tool may be configured to produce any other method of generating relative motion between the workpiece and the hard shaping component when they are in contact with each other, for example, generating rotation of the workpiece when the tool is held in place. Other types of tool motion, including orbital motion, eccentric motion, and random motion, may be applied in addition to or as alternatives to the examples just described in the methods of tool use.

[0010] As described above, the polishing surface is biasable toward a first position in which it protrudes toward the adjacent region of the outward-facing surface of the hard-shaped cutting section. The polishing surface is provided in this biasable configuration so that it may be possible to polish the workpiece surface by biasing the polishing surface toward the surface when the hard-shaped cutting section is in contact with the workpiece. Furthermore, the polishing surface is movable to a second position in which it is at the same height as the adjacent portion of the outward-facing surface, which ensures that the outward-facing surface of the hard-shaped cutting section can contact the workpiece simultaneously with the polishing surface.

[0011] In a preferred embodiment, the shaping tool further comprises a deformable polishing part having a polishing surface, the polishing surface being movable between a first position and a second position by deformation of the deformable polishing part. The polishing part may include, for example, an elastic member (e.g., a rubber part) positioned such that the polishing surface occupies the first position when not subjected to any deformable force. The elastic member in this example is compressible so that the polishing surface can be moved to the second position by compression of the elastic member. However, other configurations are also possible, for example, the polishing surface may be attached to a movable piston. The deformable polishing part also further enhances the chatter reduction effect of the polishing surface described above, as additional damping is achieved through the deformation of the polishing part.

[0012] In some preferred embodiments, the deformable polishing section includes a cavity configured to receive a pressurized fluid during use to control the pressure between the polishing surface and the workpiece. The cavity may be formed by a deformable bladder, with the polishing surface mounted outside the bladder. Thus, the position of the polishing surface and the biasing force applied to the polishing surface can be controlled by changing the amount and / or pressure of the fluid in the cavity.

[0013] As described above, the hard cutting section may be advantageously positioned so that it contacts the workpiece during use and removes material from the workpiece as the cutting tool rotates around its axis of rotation. For this purpose, the cutting tool may be provided with a spindle that allows the cutting tool to be attached to a grinding machine during use. The grinding surface is preferably positioned so that, as the cutting tool rotates around its axis of rotation, the grinding surface can come into contact with the portion of the workpiece from which the material has been removed by the hard cutting section. This is advantageous because, in this arrangement, the grinding surface and the hard cutting section can alternately pass over the same portion of the workpiece as the tool rotates. Thus, this arrangement ensures that all portions of the workpiece being cut by the hard cutting section are also ground by the grinding surface.

[0014] In some preferred embodiments, the polishing surface is positioned such that, as the shaping tool is moved along the tool path along which the material is removed from the workpiece, the polishing surface can come into contact with the portion of the workpiece from which the material has been removed by the hard shaping section. For example, the outward-facing surfaces of the polishing surface and the hard shaping section may be positioned concentrically with each other. This provides a relatively simple tool structure.

[0015] The hardened shaping section may be configured to form the workpiece by grinding, milling, or turning.

[0016] The polishing surface is preferably configured for shape-adaptive grinding (SAG). As described above, the principle of SAG and examples of tools configured for this process are described in WO2016 / 051121A1. A SAG tool generally comprises an elastic section that can conform to the shape of the workpiece and a polishing surface on which hard pellets are carried. A polishing surface configured for SAG is advantageous because SAG can achieve a smooth finish in a relatively short period of time, which further enhances the tool's ability to increase the speed of component manufacturing.

[0017] Advantageously, the polishing surface may include a flexible support layer that holds abrasive particles positioned to contact the surface of the workpiece during use. These features may be particularly present when the polishing surface is configured for SAG.

[0018] In some preferred embodiments, the aforementioned adjacent regions of the polishing surface and the outward-facing surface of the hard turning portion are arranged concentrically with each other. As described above, this provides a simple structure for the tool. In these embodiments, the aforementioned adjacent region of the outward-facing surface of the hard turning portion is preferably arranged outwardly with respect to the polishing surface. When the adjacent regions of the polishing surface and the outward-facing surface are concentric, the hard turning portion is preferably shaped to define an opening, and the polishing surface is arranged to protrude from the opening when in the first position.

[0019] A turning tool according to any of the preceding claims, wherein the polishing surface comprises an opening, and the opening is arranged such that when the turning tool is rotated about an axis extending through the opening, the entire polishing surface moves at a non-zero speed due to the rotation of the tool. Thereby, all parts of the polishing surface will move relative to the workpiece surface at a minimum speed determined at least by the diameter of the opening. This is advantageous because when parts of the polishing surface move slowly (or not at all) across the surface of the workpiece, especially when a fluid (e.g., water) is supplied to cool the area being polished (since the fluid has difficulty reaching the slowly moving parts of the polishing surface), it has been found that those parts may achieve relatively little polishing and be subject to significant heating. These problems are overcome by removing the part of the polishing surface through which the axis of rotation passes.

[0020] Advantageously, the outward-facing surface of the hard turning portion may be shaped to define one or more grooves, and the polishing surface, when in the first position, protrudes from the one or more grooves and, when in the second position, is at the same height as the region of the outward-facing surface adjacent to the grooves. This is one way of arranging the polishing surface such that each part of the workpiece processed by the hard turning portion is also processed by the polishing surface.

[0021] In a preferred embodiment, the hard cutting section comprises one or more cutting elements, each cutting element having a cutting edge positioned in contact with the surface of the workpiece and arranged to remove material from the workpiece when moved relative to the surface of the workpiece, and the outward-facing surface comprises the cutting edges of one or more cutting elements. Here, the term “cutting element” means an element capable of removing material from a workpiece by cutting, as opposed to other modes of material removal such as grinding. Tools incorporating this type of cutting element are typically used in milling operations. It will be recognized that the outward-facing surface in these embodiments, which comprises the cutting edges of a particular or each cutting element, does not have to be a single continuous surface region, since the cutting edges typically form a (discontinuous) surface that is spatially separated from each other but still capable of removing material from the workpiece when in use. The shaping tools according to these embodiments have been shown to significantly reduce chatter (i.e., tool vibration or oscillation relative to the workpiece) during use, particularly in milling operations, which improves the quality of the surface finish achieved by the tool and extends the tool's life. This reduction in chatter is thought to be at least partially due to the damping effect provided by the polished surface. Therefore, in these embodiments, it is preferable that the polished surface is composed of a deformable polishing portion as defined above, particularly an elastic member (e.g., a rubber portion) positioned such that the polished surface occupies a first position when not subjected to any deformable force. The deformable polishing portion enhances the damping effect of the polished surface.

[0022] The cutting element can be removably attached to a tool body portion configured to elastically hold the cutting element when removing material from a workpiece. This allows for convenient replacement when the cutting element wears out. The cutting element may be, for example, a milling insert. Milling inserts are commercially available and are typically made of ceramic or "cermet" (a type of composite material in which ceramic particles are bonded by a metal binder).

[0023] In a preferred embodiment, the cutting edge of the cutting element is rounded. This is preferred because a rounded cutting element is particularly suitable for forming curved, irregular, and complex shapes.

[0024] The polished surface is preferably a three-dimensional surface that preferably includes a rounded edge region extending circumferentially around a central region of the polished surface, in which case the central region is preferably substantially flat. "Three-dimensional surface" means that the polished surface does not occupy a single flat surface—in other words, there are several parts of the surface that have a different orientation from other parts of the surface. For example, while a flat circular disk defines a two-dimensional surface, a curved hemispherical surface is an example of a three-dimensional surface. This type of rounded edge region is advantageous because it can handle curved workpiece shapes, irregular workpiece shapes, and complex workpiece shapes that are difficult or impossible to polish with flat tools. In a particularly preferred embodiment, the rounded edge is shaped to define one or more recessed regions, and each cutting element is positioned inside one of the recessed regions such that when the polished surface is in a second position, the portion of the polished surface adjacent to the recessed region is at the same height as the cutting edge of the cutting element positioned inside the aforementioned recessed region. This arrangement allows the cutting edge and the rounded cutting edge to alternately pass over the same portion of the workpiece surface as the tool rotates while in contact with the workpiece, thereby providing a particularly effective method for simultaneously cutting and polishing curved, irregular, and complex areas of the workpiece. The use of cutting elements including rounded cutting edges as defined above is particularly advantageous in these embodiments.

[0025] A second aspect of the present invention is a method for polishing a workpiece, To provide a shaping tool according to the first embodiment to the surface of a workpiece, Moving a hard shaping tool against the surface of a workpiece to remove material from at least a portion of the workpiece, and The polishing surface is biased toward a first position while in contact with the portion of the workpiece from which material has been removed by the hard cutting section, and at the same time the polishing surface is moved relative to that portion of the workpiece, thereby polishing that portion of the workpiece. This provides a method that includes [something].

[0026] This method realizes the advantages described above in relation to the first embodiment and therefore provides a method for manufacturing components from a workpiece in a faster and less complex manner than previously possible embodiments.

[0027] A method for polishing a workpiece, To form at least one machined region of a workpiece by moving the hard shaping part against the surface of the workpiece while it is in contact with the workpiece, thereby removing material from the workpiece, and simultaneously, Polishing the aforementioned areas of the workpiece by applying the polished surface of the deformable polishing part to one or more of the at least one shaped areas of the workpiece. Methods that include...

[0028] The advantages of the present invention are most strongly felt when the polishing surface and the hard-shaping section are integrated into a single tool; however, when the hard-shaping section and the polishing surface are not part of the same integrated tool, it has been recognized that the same advantages can be achieved to some extent by applying the hard-shaping section and the polishing surface to the workpiece simultaneously. In this embodiment, it is preferable that the movement of the hard-shaping section and the application of the polishing surface are performed simultaneously by applying the method of the second embodiment. [Brief explanation of the drawing]

[0029] [Figure 1A] This figure shows a first example of a shaping tool according to one embodiment of the present invention. [Figure 1B] This figure shows a first example of a shaping tool according to one embodiment of the present invention. [Figure 2] This figure shows the shaping tools used in a method according to one embodiment of the present invention, as shown in Figures 1A and 1B. [Figure 3] This figure shows a second example of a shaping tool according to one embodiment of the present invention. [Figure 4A] This figure shows a third example of a shaping tool according to one embodiment of the present invention. [Figure 4B] This figure shows a third example of a shaping tool according to one embodiment of the present invention. [Figure 4C] This figure shows a third example of a shaping tool according to one embodiment of the present invention. [Figure 5] This figure shows a fourth example of a shaping tool according to one embodiment of the present invention. [Figure 6] Figure 5 is a magnified view of a portion of the polished surface of the shaping tool. [Figure 7] This figure shows the shaping tools arranged in the experimental setup shown in Figure 5. [Figure 8A] This figure shows an example of the tool path used in an experiment using the settings in Figure 7. [Figure 8B] This figure shows an example of the tool path used in an experiment using the settings in Figure 7. [Figure 9A] This figure shows the results obtained in experiments using the tool shown in Figure 5 and other tools as comparative examples. [Figure 9B] This figure shows the results obtained in experiments using the tool shown in Figure 5 and other tools as comparative examples. [Figure 10A] This figure shows the measured material removal rate as a function of the feed rate. [Figure 10B] This figure shows the measured material removal rate as a function of grid size. [Figure 10C] This figure shows the measured material removal rate as a function of the compression offset. [Figure 10D] This figure shows the measured material removal rate as a function of the measured shape error for different tools. [Figure 11A] This figure shows the shape error between a conventional grinding tool and a shaping tool produced by the method of the present invention. [Figure 11B] This figure shows the roughness Ra measurement values ​​for conventional grinding tools and shaping tools using the method of the present invention. [Figure 12A] This figure shows the surface properties of glass workpieces processed with conventional grinding tools and the tool shown in Figure 5. [Figure 12B] This figure shows the transparency of glass workpieces processed with conventional grinding tools and the tool shown in Figure 5. [Figure 13] This figure shows a further example of a shaping tool according to one embodiment of the present invention. [Figure 14] This figure shows a further example of a shaping tool according to one embodiment of the present invention. [Figure 15] This figure shows an example of a shaping tool configured for milling operations according to one embodiment of the present invention. [Figure 16A] This figure shows another example of a shaping tool configured for milling operations according to one embodiment of the present invention. [Figure 16B] This figure shows another example of a shaping tool configured for milling operations according to one embodiment of the present invention. [Figure 16C] This figure shows another example of a shaping tool configured for milling operations according to one embodiment of the present invention. [Figure 16D] This figure shows another example of a shaping tool configured for milling operations according to one embodiment of the present invention. [Figure 16E] This figure shows another example of a shaping tool configured for milling operations according to one embodiment of the present invention. [Figure 17A] This figure shows the shaping tool (Figure 15) positioned in an experimental setup. [Figure 17B] This figure shows the shaping tool (Figure 15) positioned in an experimental setup. [Figure 18A] This figure shows the profiles for conventional milling and hybrid mill-SAG (Single-Axle-Ground Milling) performed on aluminum using the tools shown in Figure 15. [Figure 18B] This figure shows the profiles for conventional milling and hybrid mill-SAG (Single-Axle-Ground Milling) performed on steel using the tool shown in Figure 15. [Figure 19] This figure shows surface micrographs under various process conditions. [Figure 20A] This figure shows the measured values ​​of the variation in surface roughness Ra for aluminum with respect to feed rate. [Figure 20B] This figure shows the measured values ​​of the variation in surface roughness Ra for steel with respect to feed rate. [Figure 21A] This figure shows the measured frequency response function (FRF) of the tool in Figure 15 at an offset of P0 = 0 mm. [Figure 21B] This figure shows the measured frequency response function (FRF) of the tool shown in Figure 15 at an offset P0 = 1.5 mm. [Figure 22A] This figure shows the measured values ​​of viscous damping coefficient and stiffness variation due to SAG offset. [Figure 22B] This figure shows the measured values ​​of viscous damping coefficient and stiffness variation due to SAG offset. [Figure 23A] This figure shows the average force relative to the cutting force coefficient at an offset of 0 mm. [Figure 23B] This figure shows the average force for verifying the cutting force coefficient at an offset of 1.0 mm. [Figure 24] This is a stability lobe diagram for conventional tools and the hybrid tool shown in Figure 15 under various compression offset (P0) conditions. [Figure 25] This figure shows the FFT analysis of cutting force for conventional milling tools and hybrid tools (offset = 1.5 mm) at N = 5735 rpm and a = 0.4 mm. [Modes for carrying out the invention]

[0030] This section first describes examples of tools according to embodiments of the present invention. Next, it describes in detail experiments conducted using tools according to embodiments of the present invention and the results of these experiments.

[0031] 1. Examples of tools Figures 1A and 1B are cross-sectional views of a first example of a shaping tool 100 according to one embodiment of the present invention. The tool comprises a spindle 101 on which a hard shaping section 103 is fixed. In use, the tool 100 is rotated around a rotation axis A parallel to the spindle 101. The outward-facing surface 103a of the hard shaping section is applied to a workpiece (e.g., a glass blank to be shaped into a lens) while the tool is rotating around axis A, and as a result, the outward-facing surface removes material from the workpiece by moving relative to the surface of the workpiece. Thus, the hard shaping section 103 can be moved along a predetermined tool path to give the workpiece a desired shape by removing material.

[0032] The shaping tool 100 includes a deformable grinding section 105. The deformable grinding section 105 includes an elastic section 107 that is fitted into a recess 106 of the hard grinding section 103. The elastic section carries a grinding surface 109, which in this case is a sheet of material carrying abrasive particles. The grinding surface 109 is configured to grind the surface of the workpiece when moved relative to the workpiece.

[0033] When the deformable grinding portion 105 is not subjected to a deformable force, the grinding surface 109 occupies a first position (shown in Figure 1A), in which position the grinding surface 109 protrudes by a distance P0 from the adjacent portion of the outward-facing surface 103a of the hard-shaped grinding portion 103. This distance P0 is sometimes called the "compression offset" of the tool 100 and is determined by the shape of the elastic portion 107 in its undeformed state.

[0034] Figure 1B shows the shaping tool 100 as viewed from directly below along axis A. The outward-facing surface 103a has an annular shape, such that the recess 106 is also annular. The deformable shaping section is cylindrical and is positioned within the recess 106, concentric with the annular surface 103a around the axis of rotation A. In this example, the hard shaping section 103 and the deformable polishing section 105 are rotationally symmetric with respect to axis A.

[0035] Next, an example of how to use the shaping tool 100 will be described with reference to Figure 2. This figure shows the shaping tool 100 used to shape and polish a workpiece 201. The tool is rotated around a rotation axis A and applied to the workpiece 201, which is held in place while being processed by the tool 100. The shaping tool 100 and the workpiece 201 can be mounted in a shaping machine as shown in Figures 1-4 of WO2016 / 051121A1 to perform this work. In such a mechanism, the tool 100 is mounted in the shaping machine by a spindle 101. While rotating, the shaping tool 100 is applied to the surface 203 of the workpiece and moved in a direction F along a predetermined tool path that is parallel to the workpiece surface 203 and perpendicular to the rotation axis A. The hard cutting section 103 contacts the workpiece surface 203 and removes material from the workpiece surface 203 (by moving relative to the workpiece 201 due to the rotation of the tool 100 while in contact with the stationary workpiece 201). The tool path is thickness t g The configuration is such that a layer of material having the specified properties is removed from the workpiece surface 203 by the hard cutting section 103.

[0036] As the tool 100 moves along its path, the deformable grinding section 105 is compressed along the direction of axis A. The grinding surface 109 is biased toward a first position by the elastic section 107, and as a result, the grinding surface 109 is pressed against the machined portion of the workpiece 201. As the grinding surface 109 rotates around axis A, it grinds that portion of the workpiece. Thus, as the tool 100 moves along its path, the workpiece is first machined by the hard shaping section 103 and then ground by the grinding surface 109, at least at points along the tool path.

[0037] While the majority of the material removed from the workpiece 201 is due to the action of the hard shaping section 103, the polishing of the workpiece 201 by the polishing surface 109 also removes a certain (relatively small) amount of material from the workpiece 201. As the material is polished and removed, the polishing surface 109 begins to protrude relative to the adjacent portion of the outward-facing surface 103a of the shaping section 103, so that the polished portion of the workpiece 201 does not undergo further grinding as the trailing edge of the hard shaping section 103 passes over it.

[0038] While the workpiece is being processed by the tool, a cutting fluid such as water may be supplied to the contact point between the workpiece and the tool 100. Such a fluid can cool and lubricate the shaping and grinding parts.

[0039] Figure 3 shows a second example of a shaping tool 300 according to one embodiment of the present invention. Here, the tool 300 has a spindle 301 on which a hard shaping section 303 is fixed, and the hard shaping section 303 has a curved outward surface 303a. The overall shape of the outward surface 303a is the shape of a spherical cross-section. As in the previous example, this tool 300 is rotated in use around an axis aligned with the spindle 301, and the outward surface 303a of the hard shaping section is applied to the workpiece being processed in order to shape the workpiece.

[0040] In this example, the hard cutting section 303 has a plurality of grooves that extend along its surface and converge on the opposite side of the spindle 301 (through which the tool's axis of rotation passes). Within the grooves are deformable polishing sections having polishing surfaces 309. Similar to the cutting tool 100 in Figure 1A, the polishing surface 309 in this example is biased toward a first position, in which the polishing surface 309 protrudes toward the adjacent area of ​​the outward-facing surface 303a by an elastic section located within the groove. The polishing surface 309 occupies the first position when the deformable polishing section is not subjected to any deformable force. Each portion of the deformable polishing section can be compressed (for example, by pressing the tool against a workpiece) such that the polishing surface 309 is in a second position at the same height as the adjacent area of ​​the outward-facing surface 303a (in the second position, the polishing surface 309 is biased toward the first position by a compressed elastic section). Therefore, when the tool 300 is rotated around an axis aligned with the spindle 301 and applied to the workpiece, the material is removed by the hard cutting portion, and the polishing surface 309 is biased toward a protruding first position, so the material is polished by the movement of the polishing surface 309 relative to the cut portion of the workpiece.

[0041] This "spherical" tool 300 is particularly useful for processing workpieces with complex shapes and hard-to-reach areas, such as artificial prostheses.

[0042] A third example of a shaping tool 400 according to one embodiment of the present invention is shown in Figures 4A-4C. The tool also includes a spindle 401 on which a hard shaping section 403 is fixed, having an outward-facing surface 403a suitable for shaping a workpiece during use. The hard shaping section 403 has an overall cylindrical shape, similar to the corresponding section in Figure 1A. However, the hard shaping section 403 here has a plurality of grooves, which extend across the opposite surface of the spindle and intersect with each other at the point where the spindle axis A intersects the outward-facing surface 403a. The deformable polishing section 405 biases the polishing surface 409 toward a first position shown in Figure 4A, where the polishing surface 409 protrudes relative to the adjacent area of ​​the outward-facing surface, but can be deformed to be at the same height as the same area of ​​the outward-facing surface 403a.

[0043] The shaping tools shown in Figures 3 and 4A-4C are particularly advantageous because, when applied to a workpiece, the entire area shaped by the hard shaping sections 303 and 403 is also polished by the polishing surfaces 309 and 409. This is because the arrangement of the polishing surfaces 309 and 409 is such that the rotation of the tool alternately traverses the portion of the workpiece to which the tool 300 and 400 is applied to the shaping sections 309 and 409 and the polishing surfaces 309 and 409. In contrast, the concentric design shown in Figure 1A requires the tool 100 to be translated parallel to the portion of the workpiece to which the polishing surface 109 reaches the portion shaped by the hard shaping section 103 (as seen in Figure 2).

[0044] 2. Experiment Figure 5 shows a shaping tool 500 according to one embodiment of the present invention. The tool design is similar to the design in Figure 1A in that the tool 500 comprises a spindle 501 fixed to a hard shaping section 503 and a polishing surface 509 positioned on an elastic section mounted in a central recess of the hard shaping section 503. However, the polishing surface here has a central opening 511 so that the rotation axis A of the tool 500 does not pass through the annular-shaped polishing surface 509. This is advantageous because when the polishing tool in Figure 1A is rotated around its rotation axis A, the speed of the polishing surface near the radial axis A is very low. This means that the central portion of the polishing surface 109 does not provide significant polishing but still contributes to heating and wear of the polishing surface. Furthermore, if a cutting fluid such as water is supplied to the polishing surface during use, the fluid cannot easily reach the central portion of the polishing surface, which exacerbates these problems. By providing a central opening 511 in the polishing surface 509, the entire polishing surface 509 now moves quickly relative to the workpiece surface, and if provided, it also provides a good supply of cutting fluid, thus overcoming these drawbacks.

[0045] Figure 6 shows an SEM micrograph of a portion of the polished surface 509. The polished surface is supported by abrasive pellets 600 containing diamond grit (shown magnified at different scales in the three frames on the right).

[0046] The shaping tool 500 shown in Figure 5 was used for an experiment using the apparatus shown in Figure 7. The tool 500 was attached by a spindle to a shaping machine 700, which was configured to rotate the tool 500 around its axis A and to keep the tool 500 in contact with the workpiece. The workpiece was clamped in an appropriate position in a tank of cutting fluid (water), and the tool was moved in parallel. The conditions and results of this experiment are described in detail below.

[0047] 2.1 Preparing the Tools In this experiment, three types of tools were investigated: (1) rigid grinding tools, (2) SAG tools, and (3) hybrid tools as shown in Figure 5. A commercially available cup grinding tool with a diameter (Φ) of 12 mm was procured. JPEG2026514028000002.jpg987 This grinding tool can produce a surface roughness Ra < 0.5 μm on ceramic and glass surfaces. The SAG tool was prepared in-house using a Φ8 mm steel shank. Natural rubber with a Shore hardness of 64A and a thickness of 3 mm was bonded to the shank using contact glue. Nickel-bonded diamond (NBD) pellet pads were then fixed onto the rubber surface. A hybrid tool was prepared by combining a commercially available grinding tool with the SAG tool, thereby inserting the assembly of soft rubber and NBD pads into a pocket on the cup grinding tool. Preliminary experiments revealed that the SAG pads could wear and separate quite rapidly. This is thought to be due to insufficient supply of cutting fluid across the SAG pad surface, where the pad is completely surrounded by the cutting head, resulting in almost negligible cutting speed near the center and a high degree of rubbing and friction (Pratap, A., Patra, K., and Dyakonov, AA, 2018, On-Machine Texturing of PCD Micro-Tools for Dry Micro-Slot Grinding of BK7 Glass, Precis.Eng., 55 (November 2018), pp. 491-502). Therefore, a Φ2 mm hole was drilled in the center of the SAG tool, which was found to significantly reduce pad wear. Hybrid tools with different compression offsets (P0) were prepared by varying the depth of the pocket on the tool. SAG pads with different abrasive grit sizes (e.g., 9, 20, 40 μm) were used experimentally, and their SEM micrographs are also shown in Figure 6. [Table 1] [Table 2]

[0048] 2.2 Experimental Design Experiments were conducted on a 3-axis CNC machining platform (NVX5000, DMG Mori Ltd.). A cutting fluid storage unit was mounted on a dynamometer (Kistler, 257B), and the dynamometer was mounted on the machine stand as shown in Figure 7. A workpiece, a highly polished BK7 glass window with an initial surface roughness Ra of approximately 3 nanometers (nm), was clamped inside the storage unit. This method, in which a highly polished mirror surface is degraded by the grinding process, is commonly used to determine the potential for removal and roughness achievable in a target process. A peristaltic pump was used to supply cutting fluid (water) to the workpiece surface. A collet chuck was used to clamp the tool on the spindle, and a constant path length of 35 mm was maintained for each tool to neutralize any surface property dependence on vibration or chatter caused by different path lengths. Two sets of experiments were planned. The first set of experiments would compare the performance of the proposed hybrid tool with that of conventional grinding tools and SAG tools. Four experiments were set up at this stage. Three experiments were conducted using each type of tool and its associated parameters, as described in Table 1. Furthermore, a fourth experiment was planned using conventional grinding and SAG tools (hereinafter referred to as "grinding-SAG") used sequentially on the same surface to verify whether the proposed hybrid tool could achieve performance similar to that of separate tools used in sequence.

[0049] The second set of experiments establishes the removal and surface finishing capabilities of the hybrid tool with respect to process parameters, namely feed rate (f), compression offset (P0), and abrasive grit size, as shown in Table 2. Two types of tool paths were employed, as shown in Figures 8A-8B. To observe the removal rate of the process, a single-line tool path in which the tool crosses the workpiece surface only once was considered, as shown in Figure 8A. Next, to establish the tool performance for precision grinding, a raster tool path with a track spacing (TS) of 0.2 mm was generated over a 20 mm x 20 mm square surface, as shown in Figure 8B, and the roughness and shape error were measured within it.

[0050] 2.3 Results and Discussion 2.3.1 Relative material removal and finishing performance The material removal profiles of various tools were measured using a contact profile meter containing a 2 μm radius diamond tip (Taylor-Hobson, Form Talysurf PGI1240). As shown in Figures 9A-B, the data was analyzed to obtain the removal rate (mm3 / min) and average roughness Ra (μm). Conventional grinding removed the smallest amount of material, while the amount of material removed steadily increased in the case of SAG, grind-SAG, and hybrid processes. Since the removal depth in SAG is inversely proportional to the feed rate, the large removal amount by SAG was achieved by a low feed rate of 30 mm / min. The removal rate with hybrid tools was almost comparable to using two separate tools in sequence, which establishes that hybrid tools can be used to save machining time. The average roughness Ra measured inside the raster area was 0.18 μm for conventional grinding and 0.016 μm for the SAG process. The surface roughness obtained with the hybrid tool (Ra=0.025μm) and the surface roughness obtained with grinding-SAG (Ra=0.031μm) were similar, but the processing time with the hybrid tool of the present invention was only half the processing time with grinding-SAG.

[0051] 2.3.2 Grinding characteristics according to control parameters In the experiments described above, it was found that the material removal by the SAG pad was very large, and the removal profile was distorted in the central region of the removal (see inset in Figure 8A). The goal of optical surface generation is to achieve the smallest possible removal by the SAG pad when using the hybrid tool of the present invention, where cracks and damaged layers are barely removed from the ground surface. Therefore, the influence of control parameters was investigated to achieve this goal of shallow removal, controlled surface shape, and good surface finish.

[0052] Figures 10A–10D show the removal rates based on experiments with hybrid tools, relating to feed rate f, SAG pad abrasive grit size, and compression offset P0. As the feed rate increased from 30 mm / min to 90 mm / min, the overall removal rate increased, but the removal depth decreased, due to the reduced involvement of the SAG pad. Therefore, a high feed rate of 90 mm / min appears suitable for achieving high removal rates with less profile distortion. As shown in Figure 10B, the removal rate also increased when the pad grit size was changed from 9 μm to 40 μm. Smaller grit sizes resulted in shallower removal depths. As shown in Figure 10C, the compression offset P0 had a relatively small effect on the removal rate compared to the feed rate and grit size. As shown in the inset in Figure 10C, a low offset value of 0.15 mm was found to be favorable for producing a distortion-free, flat removal profile. The material removal depth increases towards the edge of the SAG contact zone, but this variation can be mitigated by reducing the compression offset. As shown in Figure 10D, the shape error in terms of peak-to-valley (PV) height of the raster-generated surface at two different compression offsets (P0 = 0.15 mm and 0.35 mm) was compared to a conventionally ground surface. The PV was 1.10 μm for the hybrid tool at P0 = 0.15 mm, compared to PV = 0.64 μm for the conventionally ground surface. The shape error increased to approximately 1.74 μm at P0 = 0.35 mm. Therefore, high feed rates, small grit sizes, and low compression offset values ​​are suitable for maximizing material removal rates while maintaining the flatness of the grinding profile.

[0053] Surface roughness, properties, and transparency were observed. As shown in Figure 11A, the average roughness Ra increased from 0.017 μm to 0.061 μm as the grit size increased from 9 μm to 40 μm. Surface roughness profiles rasterized by conventional and hybrid tools are plotted in Figure 11B. As shown in Figure 12A, surface topography was captured using a scanning electron microscope (Hitachi High-Tech Corporation, FE-SEM SU-8020). Significant brittle fracture and pitting were observed on conventionally ground surfaces. Surfaces processed with a 20 μm grit hybrid tool showed fine depressions on the surface, indicating a mixed ductile-brittle mode. Surfaces processed with a 9 μm grit hybrid tool had almost no cracks or fissures and were therefore nearly suitable for the ductile mode. The relative transparency of the surfaces is compared in Figure 12B. Both surfaces were obtained within the same processing time, but the surface produced by the hybrid tool had a glossy finish, while the conventionally ground surface had a matte finish.

[0054] The example just described demonstrated a method for reducing processing time when generating optical surfaces. The hybrid tool according to the present invention enables precise finishing of flat surfaces in a single run, eliminating the need for sequential grinding, micro-grinding, and polishing operations. The performance of the developed hybrid tool was established with respect to process parameters such as feed rate, compression offset, and grit size. High feed rates, along with a small grit size and low compression offset, were able to produce a smooth, flat surface with an average roughness of 0.017 μm Ra, compared to 0.21 μm Ra for conventionally ground surfaces in the same processing time.

[0055] The proposed hybrid tool design is easy to use and provides a basis for developing other integrated tools that combine SAG with milling or turning processes. The potential for such tools to achieve single-step finishing on a wide variety of materials seems promising.

[0056] Figure 13 shows a further example of a shaping tool 1400 according to one embodiment of the present invention. The tool is shown in a disassembled state. In this embodiment, the shaping tool 1400 is adapted for milling operations. The tool includes a hard shaping section 1403 that is rotationally symmetric with respect to the tool's axis of rotation A. Multiple teeth 1404 are arranged around the hard shaping section 1403, and the upper surfaces of the teeth 1404 along direction A form outward-facing surfaces 1403a, which, when in use, can shape the workpiece when in contact with the workpiece while the tool 1400 is rotating around axis A. A tool having this configuration may be described as a "face milling cutter" because it contacts the workpiece along the direction of the axis of rotation A.

[0057] The hard shaping section is formed to define a recess 1402, and within the recess 1402, a deformable polishing section 1407 having a polishing surface 1409 is positioned when assembled. The recess 1402 and the deformable polishing section 1407 are balanced such that the polishing surface 1409 protrudes in the direction of the rotation axis A relative to the outward-facing surface 1403a formed by the upper part of the teeth 1404 in the assembled tool. Thus, the shaping tool 1400 in this embodiment processes the workpiece in the same way as the shaping tools in Figures 1A and 2, in that the centrally located polishing surface polishes the portion of the workpiece from which material has been removed by the teeth 1404 as the tool is moved laterally in parallel while in contact with the workpiece in the manner shown in Figure 2.

[0058] Figure 14 shows a further example of a shaping tool 1500 according to one embodiment of the present invention, which, as in the previous example, is configured for milling operations. The shaping tool 1500 is shown in a disassembled state. The structure of this tool 1500 differs from that of Figure 13 in that it is an example of a "side milling cutter," in which case the part of the tool configured to contact the workpiece during use is formed not by a part facing along the direction of the rotation axis A, but by the side of the tool (parallel to the rotation axis A of the tool).

[0059] The tool 1500 has a hard cutting section 1503 that has an overall cylindrical shape. Multiple helical grooves 1502 are formed in the hard cutting section 1503, and the curved surface portions between the grooves form an outward surface 1503a, which contacts the workpiece during use and removes material from the workpiece as the tool rotates around axis A.

[0060] The tool comprises a plurality of deformable abrasive sections 1507, each of which is formed from a strip of a deformable (e.g., elastic) material. Each deformable abrasive section carries an abrasive surface 1509. In the assembled tool, each deformable abrasive section 1507 is placed in each of the helical grooves 1502 such that the abrasive surface 1509 protrudes from the helical grooves 1502 relative to the outward-facing surface 1503a formed by the tool portion between the grooves. As the tool 1500 is rotated around axis A and contacts the workpiece, each portion of the workpiece in contact with the tool 1500 is alternately exposed to sections of the outward-facing surface 1503 between the grooves 1502 and sections of the abrasive surface 1509 protruding from the grooves 1502.

[0061] 3. Further examples of milling tools Next, further examples of tools according to one embodiment of the present invention will be described. The tools of these embodiments are configured for performing milling operations and offer specific advantages in relation to milling, as described below. Experiments performed with tools configured according to these embodiments will then be described.

[0062] Figure 15 shows an example of a shaping tool 1600 according to one embodiment of the present invention. This tool is an example of an embodiment in which a hard shaping section comprises one or more cutting elements, each containing a cutting edge, positioned to contact the surface of a workpiece and move relative to the surface of the workpiece to remove material from the workpiece, and an outward-facing surface comprising the cutting edges of one or more cutting elements.

[0063] The tool 1600 is configured to perform milling operations. The tool comprises a spindle 1601 to which the tool body 1620 is fixed and held in a plane by a grab screw 1621. Two cutting elements 1604 are mounted on the tool body 1620, which in this case are diamond-shaped milling inserts having cutting edges 1604a. The tool rotates around a rotation axis aligned with the spindle 1601, and when the cutting edges contact the workpiece to be shaped, the cutting edges 1604a move relative to the surface of the workpiece, thereby removing material from the workpiece. In this embodiment, the hard shaping portion is provided by the cutting elements 1604, and the cutting edges 1604a define the outward-facing surface of this portion.

[0064] The tool body 1620 includes a recess 1602 in which a deformable grinding section is arranged. The deformable grinding section comprises a compressible rubber section 1607 and a grinding surface 1609, the grinding surface 1609 being a pad that carries abrasive particles on its outer surface (therefore, shape-adaptive grinding can be performed).

[0065] The compressible rubber portion 1607 and the polishing surface 1609 are positioned such that when undeformed, the polishing surface 1609 protrudes away from the tool body 1620 and relative to the cutting edge 1604a, and can be compressed so that when positioned in contact with a workpiece, the polishing surface 1609 is at the same height as the cutting edge 1604a. Thus, when the tool rotates around an axis aligned with the spindle 1601 and the cutting edge 1604a comes into contact with a workpiece, the cutting edge 1604a removes material from the workpiece, and the rotating polishing surface 1609 polishes the portion of the workpiece that is in contact. The tool 1600 may be moved laterally relative to the workpiece surface while rotating so that the polishing surface comes into contact with the portion of the workpiece surface from which the cutting edge 1604a has removed material.

[0066] In the tool shown in Figure 15, the milling insert 1604 is an indexable milling insert (manufactured by Kyocera, model: PV720) with a cutting radius of 0.1 mm, positioned 13 mm from the tool axis. The SAG tool section (i.e., the polished surface 1609) was cut from an existing standard 15 mm diameter cap-type SAG tool (manufactured by Zeeko, model: C15).

[0067] Further examples of the shaping tool 1700 configured for milling operations are shown in Figures 16A–16E, where Figure 16A shows a perspective view of the tool 1700, and Figure 16B shows a plan view of the tool 1700 facing the end of the tool. As with the tools in Figures 16A–16E, the tool 1700 comprises a spindle 1701 to which the tool body 1720 is attached. The tool 1700 also includes a deformable grinding section comprising a three-dimensional grinding surface 1709 and a deformable rubber section (invisible) below the grinding surface.

[0068] In this example, the polishing surface 1709 is a three-dimensional surface (i.e., not a flat surface) comprising a flat central region 1709a and a rounded edge region 1709b extending circumferentially around the central region 1709a. The rounded edge region 1709b is shaped to define two recessed regions 1724 on opposing sides of the polishing surface 1709, with a rounded cutting element 1704 positioned within each of the recessed regions 1724. In this case, the rounded cutting element is a milling insert that is removably mounted on the tool body 1720. The cutting element 1704 has cutting edges 1704a that can remove material from the workpiece when the tool rotates around an axis aligned with the spindle 1701 and contacts the workpiece.

[0069] The polishing surface 1609 is positioned such that when the deformable polishing portion is not deformed, the polishing surface 1609 protrudes away from the tool body 1720 relative to the cutting edge 1704a. When the cutting edge is positioned in contact with the workpiece, the polishing portion can be compressed such that the portion of the polishing surface 1609 adjacent to the recessed region 1724 is at the same height as each cutting edge 1704a.

[0070] The tool 1700 can shape and polish a workpiece when positioned in contact with the workpiece in a range of orientations, thanks to the rounded edge region 1709b of the polishing surface 1709 and the rounded cutting element 1704. For example, flat areas of the workpiece can be shaped by bringing the flat central region 1709a into contact with the workpiece when the tool 1700 is rotated and moved laterally relative to the workpiece surface, while the rounded edge region 1709b can shape non-flat areas of the workpiece (e.g., concave or convex areas). When the rounded edge region 1709b is positioned in contact with the workpiece while the tool 1700 is rotating, it will be recognized that the rotation of the tool causes the cutting edge 1704 and the rounded edge region 1709b to alternately contact the same area on the workpiece surface, so that the portion shaped by the cutting edge 1704 is not required to be polished by the polished surface 1709. Therefore, the shaping tool 1700 shown in Figures 16A-16E is a particularly preferred embodiment of the present invention because it can shape and polish curved workpieces, irregular workpieces, and complex workpieces.

[0071] As demonstrated by the experiments described in Section 4, the types of tools shown in Figures 15 and 16A-16E achieve a significant reduction in chatter (i.e., vibration of the tool relative to the workpiece) during milling operations, in addition to the advantages mentioned above. This is thought to be at least partially due to the damping effect provided by the deformable grinding section. This reduction in chatter is particularly beneficial for milling performed by industrial robots, which typically hold tools in configurations that are significantly less rigid than conventional machines and are therefore particularly susceptible to significant tool vibration during use.

[0072] Figure 16C shows a further example of a shaping tool 1800 according to one embodiment, which is a variation of the tool 1700 shown in Figures 16A and 16B. Like the tool in Figure 16A, the shaping tool 1800 in Figure 16C comprises a spindle 1801 to which a tool body 1820 is fixed. Three rounded cutting elements 1804 (in this case, rounded milling inserts) are removably mounted on the tool body 1820, and these rounded cutting elements 1804 are equally spaced apart from each other in the circumferential direction around the axis of the tool along which the spindle 1801 is oriented. The tool has a polishing surface 1809, which is formed to have three recesses, each positioned to accommodate one of the cutting elements 1804.

[0073] The polishing surface 1809 is part of the polishing section shown in Figure 16D. The polishing section includes an elastic (e.g., rubber) section 1807 on which the polishing surface 1809 is supported. The elastic section 1807 is fixed to a shank 1841 which is molded to be received by a corresponding bore 1842 in the tool body, the bore 1842 shown in Figure 16E (together with the spindle 1801).

[0074] 4. Experiment with milling tools Next, we will describe the experiment conducted using the tools shown in Figure 15.

[0075] An experiment using the shaping tool 1600 shown in Figure 15 was conducted on a 4-axis CNC machine (manufacturer: Fanuc, model: Robodrill α-D21MiA). The experimental setup is shown in Figure 17A. Figure 17B shows the tool-workpiece contact state of the hybrid tool. The process performed using the hybrid tool is hereafter referred to as hybrid milling-SAG. The SAG portion of the tool is positioned at an offset P0 from the cutting insert. When a cutting depth α is set relative to the milling insert, the SAG core (i.e., the deformable polishing portion including the polishing surface 1609 and the rubber portion 1607) is compressed relative to the workpiece due to the elastic properties of the SAG core. The cutting insert (i.e., the milling insert 1604) machines the workpiece material, while the SAG core simultaneously finishes the cut surface.

[0076] Process parameters for conventional milling and hybrid milling-SAG are presented in Table 3. Both steel and aluminum workpieces were machined using conventional and hybrid milling tools. The tool rotation speed was kept constant, and the effect of feed rate on surface formation was established. 3 wt% Syntilo® 9913 was used as the cutting fluid. [Table 3]

[0077] 4.1 Surface creation using milling versus hybrid tools The primary objective was to observe the suppression of large-amplitude roughness generated by conventional milling tools when using hybrid tools. Surface roughness was measured using a contact-type profile meter (manufactured by Taylor Hobson, model: PGI1240). Surface profiles for machined aluminum and steel are shown in Figures 18A-18B. The profiles clearly show that hybrid tools successfully suppress the large roughness introduced by indexable cutting inserts. Micrographs of surfaces produced by conventional milling and hybrid milling-SAG are shown in Figure 19. The variation in surface roughness with respect to feed rate is shown in Figures 20A-20B. Conventional milling tools produce arc-like marks on the surface. In the case of aluminum, the surface produced by hybrid milling-SAG appears slightly worse at low feed rates. The aluminum surface appears blurred at low feed rates due to the high degree of abrasion and friction of the SAG pad, coupled with the high ductility of the material. This phenomenon is more widely observed when using 9μm or 40μm NBD pads, because those pads have more grit per unit area, and therefore each abrasive grit receives a lower load to press against the workpiece surface. This results in less penetration and a greater abrasive effect on softer workpiece materials such as aluminum. As shown in Figure 20A, when using a hybrid tool including an 80μm NBD pad, there was no evidence of material blurring, and the surface roughness was very stable across the entire range of feed rate values. In the case of steel, there was no evidence of material blurring with any of the SAG pads. Hybrid tools including 9μm, 40μm, and 80μm NBDs were suitable for producing a lower surface finish compared to the surface finish of conventional milling-only tools. However, at a feed rate of 800 mm / min, the 9μm NBD pad was unable to improve the surface. This may be due to the very rough surface produced by the milling insert at such a high feed rate.Hybrid tools containing an 80μm NBD performed well at high feed rates on both aluminum and steel materials. The surface roughness achieved by the hybrid tools at 800 mm / min was comparable to that achieved by milling at 160–320 mm / min. This suggests a potential productivity improvement of approximately 60–80%. These results suggest that hybrid tools have the potential to eliminate the need for sequential rough milling followed by finish milling or grinding.

[0078] 4.2 Vibration Stability of Hybrid Tools A vibration model of a mechanical structure with two degrees of freedom (2-DOF) is defined by the displacement vector {x, y} T and force vectors {Fx, Fy} T The tool is modeled using a combination of mass elements (m), spring elements (k), and damping elements (c). However, for hybrid tools, the spring elements (k) and damping elements (c) of the frequency response function (FRF) change because the SAG portion conforms to the workpiece. Therefore, a new dynamic characteristic model is proposed that takes into account the change in the tool's dynamic characteristics due to the presence of the SAG.

[0079] The FRF of the structure was measured using a hammer tap test. In the test, two accelerometers (manufactured by Ono Sokki, model: NP-3412) were attached to the tool in the x (feed) and y (vertical) directions, and the tool was stimulated with an impact hammer (manufactured by Dytran Instruments Inc., model: 5800B4) with a built-in force sensor. The FRF of the mechanical structure was then obtained from the input and output signals, as shown in Figures 21A-21B. The hybrid tool was tested for offset values ​​from 0 mm to 1.5 mm in 0.1 mm increments. During these experiments, the SAG portion of the tool was compressed towards the machine stand at various compression offsets. The obtained decibel values ​​for inertance increase were converted to compliance increase values. This data was used to analyze the mode parameters of the tool's FRF. The single-degree-of-freedom (SDOF) method was used to estimate the parameters. The damping ratio ζ, stiffness k, and damping c were calculated as described in the literature (Nagamatsu A (1985) Modal Analysis, Baihukan). The results of the experimental modal analysis are shown in Table 4. [Table 4]

[0080] The variations in damping and stiffness with respect to SAG offset are plotted in Figures 22A and 22B. It is clear that the increase in damping or stiffness is not linear across the offset range, but rather can be divided into three separate regions. Based on this variation, a new dynamical model that takes the effect of SAG into account is considered to be as follows, where P0 is the offset.

number

[0081] To estimate the cutting force coefficient of the tool, a series of cutting experiments were performed at various feed rates while keeping the axial depth of immersion and cutting constant. The average force per tooth period was measured in the x, y, and z directions. To avoid the effect of runout on the measurements, the sum of forces per spindle revolution was collected and divided by the number of teeth on the tool. Tests were performed with hybrid tools having offset values ​​of 0 mm, 1.0 mm, and 1.5 mm (the stiffness and damping ratios for offset values ​​of 0.5 mm and 1.0 mm were very close, and therefore the 0.5 mm offset was not considered). When full immersion conditions were applied, the average force per tooth period was obtained as described in the literature (Altintas Y (2012) Manufacturing Automation, Cambridge University Press).

number

[0082] The average cutting force can be expressed as a linear function of the offset, which is influenced by the feed rate f (mm / rev / tooth) and the edge force, as follows:

number

[0083] The average force at each feed rate is measured, and the cutting edge component is calculated by linear regression of the data.

number

number

[0084] Average force plots in the feed direction (x), vertical direction (y), and axial direction (z) are shown in Figures 23A and 23B. The calculated cutting force coefficients are listed in Table 5. [Table 5]

[0085] As shown in Figure 24, stability lobe diagrams (SLDs) are generated for offsets of 0 mm (conventional milling), 1 mm, and 1.5 mm (hybrid tool) based on the cutting force coefficient and calculated mode parameters. It is observed that the stability lobes shift upward and to the right as the compression offset increases, indicating greater damping and better cutting stability. Experiments were conducted to validate the stability lobe diagrams by detecting chatter for conventional milling tools and hybrid tools. Experiments were performed under various conditions, indicated as crosses (confirmed chatter during experiments) and circles (confirmed stable cutting) on ​​the stability lobe diagram in Figure 24.

[0086] Figure 25 shows the FFT analysis of force data for a cutting depth of 0.3 mm and a spindle speed of 5735 rpm. In the case of conventional milling, a peak in chatter frequency could be observed, but with the hybrid tool, only harmonics of the tool pass-through frequency were present. This supports the idea that the hybrid tool is well-suited for chatter damping, which should be extremely beneficial in achieving good surface finish and extended tool life.

[0087] 4.3 Conclusion These experiments confirmed that the types of tools shown in Figures 15 and 16A-16E are effective in suppressing large amplitude roughness characteristics and chatter under aggressive conditions. The proposed tools were able to reduce surface roughness by 20-84% in steel and aluminum compared to the surface roughness of conventional milling tools. A chatter model for hybrid tools was developed, and the mode parameters for hybrid tools were determined using impact hammer tests while the SAG tool was in contact with the machine backing. Stability lobe and chatter experiments demonstrated that hybrid tools can achieve chatter damping.

Claims

1. A shaping tool for shaping and polishing a workpiece, wherein the shaping tool is A hard shaping section for shaping the workpiece during use, wherein the hard shaping section removes material from at least a portion of the workpiece by the movement of the outward-facing surface of the hard shaping section and the surface of the workpiece relative to each other, A polished surface that is biasable toward a first position protruding toward an adjacent region of the outward-facing surface of the hard-shaped cutting portion, and movable toward a second position at the same height as the adjacent region of the outward-facing surface of the hard-shaped cutting portion, and Equipped with, A shaping tool, wherein when the shaping tool is applied to the workpiece to remove material from the workpiece and to polish the workpiece, the polishing surface is biased toward the first position while moving relative to the portion of the workpiece from which the material has been removed by the hard shaping portion, so as to polish the portion of the workpiece.

2. The shaping tool according to claim 1, further comprising a deformable polishing portion including the polishing surface, wherein the polishing surface is movable between a first position and a second position by deformation of the deformable polishing portion.

3. The shaping tool according to claim 2, wherein the deformable polishing portion comprises a cavity configured to receive a pressurized fluid during use for controlling the pressure between the polishing surface and the workpiece.

4. The shaping tool according to any one of claims 1 to 3, wherein the hard shaping portion is positioned to contact the workpiece during use, and is positioned to remove material from the workpiece when the shaping tool is rotated around its axis of rotation.

5. The shaping tool according to any one of claims 1 to 4, wherein the polishing surface is arranged such that, when the shaping tool is rotated around the rotation axis, the polishing surface can come into contact with the portion of the workpiece from which the material has been removed by the hard shaping portion due to the rotation of the shaping tool.

6. The shaping tool according to any one of claims 1 to 5, wherein the polishing surface is arranged such that, when the shaping tool is moved in parallel along the tool path that removes material from the workpiece, the polishing surface can come into contact with the portion of the workpiece from which the material has been removed by the hard shaping portion as the shaping tool moves in parallel along the tool path that removes material from the workpiece.

7. The shaping tool according to any one of claims 1 to 6, wherein the hard shaping portion is configured for shaping the workpiece by grinding, milling, or turning.

8. The shaping tool according to any one of claims 1 to 7, wherein the polished surface is configured for shape-adaptive grinding.

9. The shaping tool according to any one of claims 1 to 8, wherein the polishing surface comprises a flexible support layer that carries abrasive particles arranged to contact the surface of the workpiece during use.

10. The shaping tool according to any one of claims 1 to 9, wherein the adjacent regions of the polished surface and the outward-facing surface of the hard shaping portion are arranged concentrically with respect to each other.

11. The shaping tool according to claim 10, wherein the adjacent region of the outward-facing surface of the hard shaping portion is arranged outward with respect to the polished surface.

12. The shaping tool according to claim 10 or 11, wherein the hard shaping portion is formed to define an opening, and the polishing surface is positioned to protrude from the opening when in the first position.

13. The shaping tool according to any one of claims 1 to 12, wherein the polishing surface comprises an opening, the opening being positioned such that the entire polishing surface moves at a non-zero speed as the shaping tool is rotated around an axis extending through the opening.

14. The shaping tool according to any one of claims 1 to 13, wherein the outward-facing surface of the hard shaping portion is shaped to define one or more grooves, and the polishing surface protrudes from the one or more grooves when in the first position and is at the same height as the region of the outward-facing surface adjacent to the grooves when in the second position.

15. The shaping tool according to any one of claims 1 to 14, wherein the hard shaping portion comprises one or more cutting elements, each of which has a cutting edge positioned in contact with the surface of the workpiece and positioned to remove material from the workpiece when moved relative to the surface of the workpiece, and the outward-facing surface comprises the cutting edges of the one or more cutting elements.

16. The shaping tool according to claim 15, wherein the cutting element is removably attached to a tool body configured to elastically hold the cutting element when removing material from the workpiece.

17. The cutting element is a milling insert, as described in claim 15 or 16.

18. The cutting edge of the cutting element is rounded, the shaping tool according to any one of claims 15 to 17.

19. The shaping tool according to any one of claims 15 to 17, wherein the polished surface is a three-dimensional surface that preferably includes a rounded edge region extending circumferentially around a central region of the polished surface, and the central region is preferably substantially flat.

20. The shaping tool according to claim 19, wherein the rounded edge is shaped to define one or more recessed regions, and each cutting element is positioned inside one of the recessed regions such that when the polished surface is in the second position, the portion of the polished surface adjacent to the recessed region is at the same height as the cutting edge of the cutting element positioned inside the recessed region.

21. A method for polishing a workpiece, wherein the method is To provide the shaping tool described in any one of claims 1 to 20 to the surface of the workpiece, Moving the hard cutting part relative to the surface of the workpiece to remove material from at least a portion of the workpiece, and When the polishing surface is in contact with the portion of the workpiece from which the material has been removed by the hard cutting portion, the polishing surface is biased toward the first position and at the same time moved relative to the portion of the workpiece, thereby polishing the portion of the workpiece. A method for polishing a workpiece, including [specific details omitted].

22. A method for polishing a workpiece, wherein the method is To form at least one machined region of the workpiece by moving the hard shaping part against the surface of the workpiece while it is in contact with the workpiece and removing material from the workpiece, and simultaneously, Polishing the workpiece by applying the polished surface of the deformable polishing part to one or more of the at least one shaped regions of the workpiece. A method for polishing a workpiece, including [specific details omitted].

23. The method according to claim 22, wherein the movement of the hard-shaped cutting portion and the application of the polished surface simultaneously are provided by applying the method of claim 21.

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