US20110312255A1 - Method for multiple cutoff machining of rare earth magnet - Google Patents

Method for multiple cutoff machining of rare earth magnet Download PDF

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Publication number
US20110312255A1
US20110312255A1 US13/161,034 US201113161034A US2011312255A1 US 20110312255 A1 US20110312255 A1 US 20110312255A1 US 201113161034 A US201113161034 A US 201113161034A US 2011312255 A1 US2011312255 A1 US 2011312255A1
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Prior art keywords
magnet block
cutoff
magnet
upside
blades
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Abandoned
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US13/161,034
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English (en)
Inventor
Kazuhito Akada
Koji Sato
Naomichi Yoshimura
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Shin Etsu Chemical Co Ltd
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Shin Etsu Chemical Co Ltd
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Assigned to SHIN-ETSU CHEMICAL CO., LTD. reassignment SHIN-ETSU CHEMICAL CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AKADA, KAZUHITO, SATO, KOJI, Yoshimura, Naomichi
Publication of US20110312255A1 publication Critical patent/US20110312255A1/en
Priority to US15/852,005 priority Critical patent/US10391602B2/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28D—WORKING STONE OR STONE-LIKE MATERIALS
    • B28D1/00—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor
    • B28D1/22—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor by cutting, e.g. incising
    • B28D1/24—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor by cutting, e.g. incising with cutting discs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B27/00—Other grinding machines or devices
    • B24B27/06—Grinders for cutting-off
    • B24B27/0675—Grinders for cutting-off methods therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B27/00—Other grinding machines or devices
    • B24B27/0076—Other grinding machines or devices grinding machines comprising two or more grinding tools
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B27/00—Other grinding machines or devices
    • B24B27/06—Grinders for cutting-off
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B41/00—Component parts such as frames, beds, carriages, headstocks
    • B24B41/06—Work supports, e.g. adjustable steadies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D5/00—Bonded abrasive wheels, or wheels with inserted abrasive blocks, designed for acting only by their periphery; Bushings or mountings therefor
    • B24D5/12—Cut-off wheels
    • B24D5/123—Cut-off wheels having different cutting segments
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28D—WORKING STONE OR STONE-LIKE MATERIALS
    • B28D7/00—Accessories specially adapted for use with machines or devices of the preceding groups
    • B28D7/02—Accessories specially adapted for use with machines or devices of the preceding groups for removing or laying dust, e.g. by spraying liquids; for cooling work
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered

Definitions

  • This invention relates to a method for cutoff machining a magnet block into multiple pieces.
  • FIG. 1 a illustrates the single part system including press molding, sintering or heat treating, and finishing steps.
  • a molded part 101 , a sintered or heat treated part 102 , and a finished part (or product) 103 are substantially identical in shape and size. Insofar as normal sintering is performed, a sintered part of near net shape is obtained, and the load of the finishing step is relatively low.
  • the multiple part system illustrated in FIG. 1 b eliminates the above-mentioned problems and allows press molding and sintering or heat treating steps to be performed with high productivity and versatility. It now becomes the mainstream of rare earth magnet manufacture.
  • a molded block 101 and a sintered or heat treated block 102 are substantially identical in shape and size, but the subsequent finishing step requires cutting. It is the key for manufacture of finished parts 103 how to cutoff machine the block in the most efficient and least wasteful manner.
  • Tools for cutting rare earth magnet blocks include two types, a diamond grinding wheel inner-diameter (ID) blade having diamond grits bonded to an inner periphery of a thin doughnut-shaped disk, and a diamond grinding wheel outer-diameter (OD) blade having diamond grits bonded to an outer periphery of a thin disk as a core.
  • ID diamond grinding wheel inner-diameter
  • OD diamond grinding wheel outer-diameter
  • FIG. 2 illustrates an exemplary multiple blade assembly 1 including a plurality of cutoff abrasive blades 11 coaxially mounted on a rotating shaft 12 alternately with spacers (not shown), each blade 11 including a core 11 b in the form of a thin doughnut disk and an abrasive grain layer 11 a on an outer peripheral rim of the core 11 b .
  • This multiple blade assembly 1 is capable of multiple cutoff machining, that is, to machine a block into a multiplicity of parts at a time.
  • diamond grains are generally bonded by three typical binding systems including resin bonding with resin binders, metal bonding with metal binders, and electroplating. These cutoff abrasive blades are often used in cutting off of rare earth magnet blocks.
  • the relationship of the cutting part (axial) width of the cutoff blade is crucially correlated to the material yield of the workpiece (magnet block). It is important to maximize a material yield and productivity by using a cutting part with a minimal thickness, machining at a high accuracy to minimize a machining allowance and reduce chips, and increasing the number of parts available.
  • the cutoff wheel core In order to form a cutting part with a minimal width (or thinner cutting part) from the standpoint of material yield, the cutoff wheel core must be thin.
  • its core 11 b is usually made of steel materials from the standpoints of material cost and mechanical strength.
  • alloy tool steels classified as SK, SKS, SKD, SKT, and SKH according to the JIS standards are often used in commercial practice.
  • the prior art core of alloy tool steel is short in mechanical strength and becomes deformed or bowed during cutoff machining, losing dimensional accuracy.
  • a cutoff wheel for use with rare earth magnet alloys including a core of cemented carbide to which high hardness abrasive grains such as diamond and cBN are bonded with a binding system such as resin bonding, metal bonding or electroplating, as described in JP-A 10-175172.
  • a binding system such as resin bonding, metal bonding or electroplating
  • the cutoff wheel may give rise to problems like dulling and loading even when a core of cemented carbide is used, which problems increase the machining force during the process and induce chipping and bowing, providing a detrimental impact on the machined state.
  • One process of multiple cutoff machining a rare earth magnet block involves providing a multiple blade assembly including a plurality of cutoff abrasive blades mounted on a rotating shaft at axially spaced apart positions, and rotating the plurality of cutoff abrasive blades.
  • a cutting fluid is effectively fed to the plurality of cutoff abrasive blades by providing a cutting fluid feed nozzle having a plurality of slits corresponding to the plurality of cutoff abrasive blades such that an outer peripheral portion of each cutoff abrasive blade may be inserted in the corresponding slit. Then the slits serve to restrict any axial run-out of the cutoff abrasive blades during rotation.
  • the cutting fluid reaching the slit and coming in contact with the outer peripheral portion of each cutoff abrasive blade is entrained on surfaces of the cutoff abrasive blade being rotated and transported toward the peripheral cutting part of the cutoff abrasive blade by the centrifugal force of rotation.
  • the cutting fluid is effectively delivered to points of cutoff machining on the magnet block during multiple cutoff machining.
  • each cutoff groove serves to restrict any axial run-out during rotation of the cutoff abrasive blade whose outer peripheral portion is inserted in the cutoff groove.
  • the cutting fluid flowing from each slit in the feed nozzle and across the surfaces of the cutoff abrasive blade flows into the cutoff groove and is then entrained on the surfaces of the cutoff abrasive blade being rotated whereby the cutting fluid is effectively fed to the blade cutting part during multiple cutoff machining.
  • a jig including a pair of jig segments for clamping the magnet block in the machining direction for securing the magnet block is proposed wherein the jig segments are provided on their surfaces with a plurality of guide grooves corresponding to the cutoff abrasive blades so that the outer peripheral portion of each cutoff abrasive blade may be inserted into the corresponding guide groove. Then the guide grooves serve to restrict any axial run-out of the cutoff abrasive blades during rotation.
  • the cutting fluid flowing from each slit in the feed nozzle and across the surfaces of the cutoff abrasive blade flows in the guide groove and is then entrained on the surfaces of the cutoff abrasive blade being rotated whereby the cutting fluid is effectively fed to the blade cutting part during multiple cutoff machining.
  • cutoff machining of the magnet block can be performed at a high accuracy and a high speed while effectively feeding a smaller volume of cutting fluid than in the prior art to points of cutoff machining.
  • the current desire for more efficient manufacture of rare earth sintered magnet entails a propensity to enlarge the size of magnet blocks to be cutoff machined, indicating an increased depth of cut.
  • the effective diameter of the cutoff abrasive blade that is, the distance from the rotating shaft or spacer to the outer periphery of the blade (corresponding to the maximum height of the cutoff abrasive blade available for cutting) must be increased.
  • Such larger diameter cutoff abrasive blades are more liable to deformation, especially axial runout.
  • a rare earth magnet block is cut into pieces of degraded shape and dimensional accuracy.
  • the prior art uses thicker cutoff abrasive blades to avoid the deformation.
  • Thicker cutoff abrasive blades are inconvenient in that more material is removed by cutting. Then the number of magnet pieces cut out of a magnet block of the same size is reduced as compared with thin cutoff abrasive blades. Under the economy where the price of rare earth metals increases, a reduction in the number of magnet pieces is reflected by the manufacture cost of rare earth magnet products.
  • An object of the invention is to provide a method for cutoff machining a rare earth magnet block having a substantial height into a multiplicity of pieces at a high accuracy, using a multiplicity of thin cutoff abrasive blades having a reduced effective diameter.
  • the invention is directed to a method for multiple cutoff machining a rare earth magnet block using a multiple blade assembly including a plurality of cutoff abrasive blades coaxially mounted on a rotating shaft at axially spaced apart positions, each said blade including a core in the form of a thin disk or thin doughnut disk and a peripheral cutting part on an outer peripheral rim of the core.
  • the cutoff abrasive blades are rotated to cutoff machine the magnet block into a multiplicity of pieces.
  • the inventor has found that the object is achievable by starting the machining operation from the upper surface of the magnet block downward, interrupting the machining operation before the magnet block is divided into pieces, turning the magnet block upside down, placing the magnet block such that the cutoff grooves formed before and after the upside-down turning may be vertically aligned with each other, and restarting the machining operation from the upper surface of the upside-down magnet block downward to form cutoff grooves in the magnet block until the cutoff grooves formed before and after the upside-down turning merge with each other, thereby cutting the magnet block into pieces.
  • the invention provides a method for multiple cutoff machining a rare earth magnet block using a multiple blade assembly including a plurality of cutoff abrasive blades coaxially mounted on a rotating shaft at axially spaced apart positions, each said blade including a core in the form of a thin disk or thin doughnut disk and a peripheral cutting part on an outer peripheral rim of the core, the method including the step of rotating the cutoff abrasive blades to cutoff machine the magnet block into pieces.
  • the method further includes the steps of starting the machining operation from the upper surface of the magnet block downward to form cutoff grooves in the magnet block, interrupting the machining operation before the magnet block is cut into pieces, turning the magnet block upside down, placing the magnet block such that the cutoff grooves formed before and after the upside-down turning may be vertically aligned with each other, and restarting the machining operation from the upper surface of the upside-down magnet block downward to form cutoff grooves in the magnet block until the cutoff grooves formed before and after the upside-down turning merge with each other, thereby cutting the magnet block into pieces.
  • the side surface of the magnet block which is not subject to the machining operation is a reference plane
  • the magnet block is turned upside down and placed such that the reference planes may be aligned with each other before and after the upside-down turning whereby the cutoff grooves formed before and after the upside-down turning are vertically aligned with each other.
  • a jig for securing the magnet block in place is disposed such that a side surface of the jig is parallel to the cutting plane of the magnet block.
  • the side surface is a reference plane.
  • the jig together with the magnet block secured thereby is turned upside down and placed such that the reference planes may be aligned with each other before and after the upside-down turning whereby the magnet block is turned upside down and the cutoff grooves formed before and after the upside-down turning are vertically aligned with each other.
  • the jig is designed to secure a plurality of magnet blocks, and the jig together with the plurality of magnet blocks secured thereby is turned upside down such that the cutoff grooves formed in the plurality of magnet blocks before and after the upside-down turning may be aligned with each other at the same time.
  • the side surface of the magnet block which is not subject to the machining operation is a reference plane
  • the magnet block is turned upside down such that the reference planes may be aligned with each other before and after the upside-down turning.
  • a jig for securing the magnet block in place is disposed such that a side surface of the jig is parallel to the cutting plane of the magnet block, the side surface is a reference plane, and the jig is turned upside down such that the reference planes may be aligned with each other before and after the upside-down turning.
  • the step at the connection between upper and lower side cutoff grooves is minimized.
  • the effective diameter of the cutoff abrasive blades can be reduced to less than the height of the rare earth magnet block, and even to about half of the height of the rare earth magnet block. Then the space that must be defined around the magnet block for allowing the cutoff abrasive blades to move may be reduced. Then the size of the cutoff machining system may be reduced.
  • the jig is designed to secure the magnet block by clamping at the opposite sides of the magnet block surface subject to machining, the length of slits which are formed in the jig to allow for entry of the cutoff abrasive blades may be reduced. From this aspect, the jig and hence the cutoff machining system can be reduced in size.
  • a rare earth magnet block having a substantial height can be cut into a multiplicity of pieces at a high accuracy.
  • the invention is of great worth in the industry.
  • FIG. 1 schematically illustrates rare earth magnet part manufacturing processes including press molding, sintering/heat treating and finishing steps, showing how the shape of parts changes in the successive steps.
  • FIG. 2 is a perspective view illustrating one exemplary multiple blade assembly used in the invention.
  • FIG. 3 illustrates one exemplary multiple blade assembly combined with a cutting fluid feed nozzle, FIG. 3 a being a plan view, FIG. 3 b being a side elevational view, and FIG. 3 c being a front view of the nozzle showing slits.
  • FIG. 4 illustrates one exemplary magnet block securing jig, FIG. 4 a being a plan view, FIG. 4 b being a side view, and FIG. 4 c being a front view of the jig segment showing guide grooves.
  • FIG. 5 illustrates another exemplary magnet block securing jig, FIG. 5 a being a plan view, and FIG. 5 b being a side view.
  • FIGS. 6 a and 6 b are graphs showing thickness variations of multiple magnet strips cut in Example 3 and Comparative Example 2, respectively, as measured at five points shown in FIG. 6 c.
  • the method for multiple cutoff machining a rare earth magnet block uses a multiple blade assembly including a plurality of cutoff abrasive blades coaxially mounted on a rotating shaft at axially spaced apart positions, each blade including a core in the form of a thin disk or thin doughnut disk and a peripheral cutting part on an outer peripheral rim of the core.
  • the multiple blade assembly is placed relative to the magnet block.
  • the cutoff abrasive blades are rotated to cutoff machine the magnet block into a multiplicity of magnet pieces.
  • cutoff grooves are formed in the magnet block.
  • one exemplary multiple blade assembly 1 includes a rotating shaft 12 and a plurality of cutoff abrasive blades or OD blades 11 coaxially mounted on the shaft 12 alternately with spacers (depicted at 13 in FIG. 3 ), i.e., at axially spaced apart positions.
  • Each blade 11 includes a core 11 b in the form of a thin disk or thin doughnut disk and a peripheral cutting part or abrasive grain-bonded section 11 a on an outer peripheral rim of the core 11 b .
  • the number of cutoff abrasive blades 11 is not particularly limited, although the number of blades generally ranges from 2 to 100, with 19 blades illustrated in the example of FIG. 2 .
  • the core has an outer diameter of 80 to 250 mm, more preferably 100 to 200 mm, and a thickness of 0.1 to 1.4 mm, more preferably 0.2 to 1.0 mm.
  • the core in the form of a thin doughnut disk has a bore having a diameter of preferably 30 to 80 mm, more preferably 40 to 70 mm.
  • the core of the cutoff abrasive blade may be made of any desired materials commonly used in cutoff blades including steels SK, SKS, SKD, SKT and SKH, although cores of cemented carbide are preferred because the cutting part or blade tip can be thinner.
  • Suitable cemented carbides of which cores are made include alloy forms of powdered carbides of metals in Groups IVB, VB and VIB in the Periodic Table, such as WC, TiC, MoC, NbC, TaC, and Cr 3 C 2 , which are cemented with Fe, Co, Ni, Mo, Cu, Pb, Sn or alloys thereof.
  • WC—Co, WC—Ni, TiC—Co, and WC—TiC—TaC—Co systems are typical and preferred for use herein.
  • the peripheral cutting part or abrasive grain-bonded section is formed to cover the outer peripheral rim of the core and consists essentially of abrasive grains and a binder.
  • abrasive grains typically diamond grains, cBN grains or mixed grains of diamond and cBN are bonded to the outer peripheral rim of the core using a binder.
  • Three binding systems including resin bonding with resin binders, metal bonding with metal binders, and electroplating are typical and any of them may be used herein.
  • the peripheral cutting part or abrasive grain-bonded section has a width W in the thickness or axial direction of the core, which is from (T+0.01) mm to (T+4) mm, more preferably (T+0.02) mm to (T+1) mm, provided that the core has a thickness T.
  • An outer portion of the peripheral cutting part or abrasive grain-bonded section that projects radially outward from the outer peripheral rim of the core has a projection distance which is preferably 0.1 to 8 mm, more preferably 0.3 to 5 mm, depending on the size of abrasive grains to be bonded.
  • An inner portion of the peripheral cutting part or abrasive grain-bonded section that radially extends on the core has a coverage distance which is preferably 0.1 to 10 mm, more preferably 0.3 to 8 mm.
  • the spacing between cutoff abrasive blades may be suitably selected depending on the thickness of magnet pieces after cutting, and preferably set to a distance which is slightly greater than the thickness of magnet pieces, for example, by 0.01 to 0.4 mm.
  • the cutoff abrasive blades are preferably rotated at 1,000 to 15,000 rpm, more preferably 3,000 to 10,000 rpm.
  • a rare earth magnet block is held as presenting upper and lower surfaces.
  • the magnet block is machined and cut into a multiplicity of pieces by rotating the cutoff abrasive blades.
  • the machining operation is started from the side of the upper surface of the magnet block downward to form cutoff grooves in the magnet block.
  • the machining operation is interrupted once before the magnet block is divided into discrete pieces.
  • the magnet block is turned upside down.
  • the machining operation is restarted from the side of the upper surface of the upside-down magnet block downward to form cutoff grooves in the magnet block until the cutoff grooves formed before and after the upside-down turning merge with each other, thereby cutting the magnet block into pieces.
  • the magnet block is machined in sequence from one surface side and then from the other surface side.
  • the cutoff machining method ensures that even though a multiplicity of thin cutoff abrasive blades having a reduced effective diameter are used, a rare earth magnet block having a substantial height can be cut into a multiplicity of pieces at a high accuracy.
  • the invention deals with a rare earth magnet block having a height of at least 5 mm, typically 10 to 100 mm and uses cutoff abrasive blades having a core thickness of up to 1.2 mm, more preferably 0.2 to 0.9 mm and an effective diameter of up to 200 mm, more preferably 80 to 180 mm.
  • the effective diameter is the distance from the rotating shaft or spacer to the outer edge of the blade and corresponds to the maximum height of a magnet block that can be cut by the blade. Then the magnet block can be cutoff machined at a high accuracy and high efficiency as compared with the prior art.
  • the magnet block is turned upside down, it is placed such that the upper and lower cutoff grooves before and after upside-down turning (specifically, upper grooves which will be machined and lower grooves which have been machined at this point of time) are vertically in alignment.
  • Alignment before and after upside-down turning may be conducted in mode ( 1 ) wherein the side surface of the magnet block which is not subject to cutoff machining is used as a reference plane, and the magnet block is turned upside down and placed such that the reference planes may be aligned with each other before and after the upside-down turning; or in mode ( 2 ) wherein the magnet block is secured by a jig such that the side surface of the jig is parallel to the cutting plane of the magnet block, the side surface is used as a reference plane, and the jig with the magnet block held therein is turned upside down and placed such that the reference planes may be aligned with each other before and after the upside-down turning.
  • mode ( 1 ) wherein the side surface of the magnet block which
  • a rare earth magnet block is cutoff machined into a multiplicity of pieces by rotating cutoff abrasive blades (i.e., OD blades), feeding cutting fluid, and moving the blades relative to the magnet block with the abrasive portion of the blade kept in contact with the magnet block (specifically moving the blades in the transverse and/or thickness direction of the magnet block). Then the magnet block is cut or machined by the cutoff abrasive blades.
  • cutoff abrasive blades i.e., OD blades
  • the magnet block is fixedly secured by any suitable means.
  • the magnet block is bonded to a support plate (e.g., of carbon base material) with wax or a similar adhesive which can be removed after machining operation, whereby the magnet block is fixedly secured prior to machining operation.
  • a jig is used for clamping the magnet block for fixedly securing it.
  • first either one or both of the multiple blade assembly and the magnet block are relatively moved in the cutting or transverse direction of the magnet block from one end to the other end of the magnet block, whereby the upper surface of the magnet block is machined to a predetermined depth throughout the transverse direction to form cutoff grooves in the magnet block.
  • the cutoff grooves may be formed by a single machining operation or by repeating plural times machining operation in the height direction of the magnet block.
  • the depth of the cutoff grooves is preferably 40 to 60%, most preferably about 50% of the height of the magnet block to be cut.
  • the width of the cutoff grooves is determined by the width of cutoff abrasive blades. Usually, the width of the cutoff grooves is slightly greater than the width of the cutoff abrasive blades due to the vibration of the cutoff abrasive blades during machining operation, and specifically in the range from more than the width of the cutoff abrasive blades (or peripheral cutting part) to 1 mm, and more preferably up to 0.5 mm.
  • the machining operation is interrupted once before the magnet block is divided into discrete pieces.
  • the magnet block is turned upside down.
  • the machining operation is restarted from the side of the upper (originally lower) surface of the upside-down magnet block downward.
  • either one or both of the multiple blade assembly and the magnet block are relatively moved in the cutting or transverse direction of the magnet block from one end to the other end of the magnet block, whereby the upper surface of the magnet block is machined to a predetermined depth throughout the transverse direction to form cutoff grooves in the magnet block.
  • the cutoff grooves may be formed by a single machining operation or by repeating plural times machining operation in the height direction of the magnet block. In this way, the portion of the magnet block left after the first groove cutting is cut off.
  • the cutoff abrasive blades are preferably rotated at a circumferential speed of at least 10 m/sec, more preferably 20 to 80 m/sec. Also, the cutoff abrasive blades are preferably fed at a feed or travel rate of at least 10 mm/min, more preferably 20 to 500 mm/min.
  • the inventive method capable of high speed machining ensures a higher accuracy and higher efficiency during machining than the prior art methods.
  • a cutting fluid is generally fed to the cutoff abrasive blades to facilitate machining.
  • a cutting fluid feed nozzle is preferably used which has a cutting fluid inlet at one end and a plurality of slits formed at another end and corresponding to the plurality of cutoff abrasive blades such that an outer peripheral portion of each cutoff abrasive blade may be inserted in the corresponding slit.
  • This cutting fluid feed nozzle 2 includes a hollow housing which has an opening at one end serving as a cutting fluid inlet 22 and is provided at the other end with a plurality of slits 21 .
  • the number of slits corresponds to the number of cutoff abrasive blades and is typically equal to the number of cutoff abrasive blades 11 in the multiple blade assembly 1 .
  • the number of slits is not particularly limited although the number of slits generally ranges from 2 to 100, with eleven slits illustrated in the example of FIG. 3 .
  • the feed nozzle 2 is combined with the multiple blade assembly 1 such that an outer peripheral portion of each cutoff abrasive blade 11 may be inserted into the corresponding slit 21 in the feed nozzle 2 . Then the slits 21 are arranged at a spacing which corresponds to the spacing between cutoff abrasive blades 11 , and the slits 21 extend straight and parallel to each other. It is seen from FIG. 3 that spacers 13 are disposed on the rotating shaft 12 between the cutoff abrasive blades 11 .
  • each cutoff abrasive blade which is inserted into the corresponding slit in the feed nozzle functions such that the cutting fluid coming in contact with the cutoff abrasive blades is entrained on the surfaces (outer peripheral portions) of the cutoff abrasive blades and transported to points of cutoff machining on the magnet block. Then the slit has a width which must be greater than the width of the cutoff abrasive blade (i.e., the width W of the outer cutting part). Through slits having too large a width, the cutting fluid may not be effectively fed to the cutoff abrasive blades and a more fraction of cutting fluid may drain away from the slits.
  • the slit in the feed nozzle preferably has a width of from more than W mm to (W+6) mm, more preferably from (W+0.1) mm to (W+6) mm.
  • the slit has such a length that when the outer peripheral portion of the cutoff abrasive blade is inserted into the slit, the outer peripheral portion may come in full contact with the cutting fluid within the feed nozzle. Often, the slit length is preferably about 2% to 30% of the outer diameter of the core of the cutoff abrasive blade.
  • a magnet block securing jig consisting of a pair of jig segments is preferably used for clamping the magnet block in the machining direction for fixedly securing the magnet block.
  • One or both of the jig segments are provided on their surfaces with a plurality of guide grooves corresponding to the cutoff abrasive blades so that the outer peripheral portion of each cutoff abrasive blade may be inserted into the corresponding guide groove.
  • FIG. 4 shows one exemplary magnet block securing jig.
  • the jig includes a support plate 32 on which a magnet block M is rested and a pair of block pressing segments 31 , 31 disposed on opposite sides of the plate 32 .
  • the pair of jig segments 31 , 31 are adapted to press the magnet block M in the machining direction (transverse direction) for fixedly securing the magnet block M to the support plate 32 while they are retained utilizing screws, clamps, pneumatic or hydraulic cylinders, or wax (not shown).
  • the jig segments 31 , 31 are provided on their surfaces with a plurality of guide grooves 31 a corresponding to cutoff abrasive blades 11 of multiple blade assembly 1 . Note that the number of guide grooves 31 a is not particularly limited, although eleven grooves are illustrated in the example of FIG. 4 .
  • FIG. 5 shows another exemplary magnet block securing jig.
  • the jig includes a pair of block pressing segments 31 , 31 disposed on opposite sides of three magnet blocks M in parallel arrangement.
  • the pair of jig segments 31 , 31 are adapted to press the magnet blocks M in the machining direction (transverse direction) for fixedly securing the magnet block M to the support plate 32 while they are retained utilizing screws, clamps, pneumatic or hydraulic cylinders, or wax (not shown).
  • three magnet blocks M are shown in FIG. 5 , the number of magnet blocks is not limited thereto.
  • the jig segments 31 , 31 are provided on their surfaces adjacent to the magnet block with a plurality of guide grooves 31 a corresponding to cutoff abrasive blades 11 of multiple blade assembly 1 .
  • the number of guide grooves 31 a is not particularly limited, although eleven grooves are illustrated in the example of FIG. 5 .
  • the guide grooves 31 a vertically penetrate throughout the segment 31 .
  • the jig of this construction has the advantage that the jig with the magnet blocks secured therein may be turned upside down without a need to remove the magnet blocks from the jig, and machining operation may be soon restarted on the magnet blocks in the jig.
  • each cutoff abrasive blade 11 is inserted into the corresponding guide groove 31 a in the jig segment 31 . Then the grooves 31 a are arranged at a spacing which corresponds to the spacing between cutoff abrasive blades 11 , and the grooves 31 a extend straight and parallel to each other.
  • the spacing between guide grooves 31 is equal to or less than the thickness of magnet pieces cut from the magnet block M.
  • each guide groove should be greater than the width of each cutoff abrasive blade (i.e., the width of the peripheral cutting part).
  • the guide groove should preferably have a width of more than W mm to (W+6) mm and more preferably from (W+0.1) mm to (W+6) mm.
  • the length (in cutting direction) and height of each guide groove are selected such that the cutoff abrasive blade may be moved within the guide groove during machining of the magnet block.
  • the workpiece which is intended herein to cutoff machine is a rare earth magnet block.
  • the rare earth magnet as the workpiece is not particularly limited. Suitable rare earth magnets include sintered rare earth magnets of R—Fe—B systems wherein R is at least one rare earth element inclusive of yttrium.
  • Suitable sintered rare earth magnets of R—Fe—B systems are those magnets containing, in weight percent, 5 to 40% of R, 50 to 90% of Fe, and 0.2 to 8% of B, and optionally one or more additive elements selected from C, Al, Si, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Ag, Sn, Hf, Ta, and W, for the purpose of improving magnetic properties and corrosion resistance.
  • the amounts of additive elements added are conventional, for example, up to 30 wt % of Co, and up to 8 wt % of the other elements. The additive elements, if added in extra amounts, rather adversely affect magnetic properties.
  • Suitable sintered rare earth magnets of R—Fe—B systems may be prepared, for example, by weighing source metal materials, melting, casting into an alloy ingot, finely dividing the alloy into particles with an average particle size of 1 to 20 ⁇ m, i.e., sintered R—Fe—B magnet powder, compacting the powder in a magnetic field, sintering the compact at 1,000 to 1,200° C. for 0.5 to 5 hours, and heat treating at 400 to 1,000° C.
  • OD blades cutoff abrasive blades
  • a doughnut-shaped disk core of cemented carbide consisting of WC 90 wt %/Co 10 wt %) having an outer diameter 120 mm, inner diameter 40 mm, and thickness 0.3 mm
  • bonding by the resin bonding technique, artificial diamond abrasive grains to an outer peripheral rim of the core to form an abrasive section (peripheral cutting part) containing 25% by volume of diamond grains with an average particle size of 150 ⁇ m.
  • the axial extension of the abrasive section from the core was 0.05 mm on each side, that is, the abrasive portion had a width of 0.4 mm (in the thickness direction of the core).
  • a cutting test was carried out on a workpiece which was a sintered Nd—Fe—B magnet block.
  • the test conditions are as follows.
  • a multiple blade assembly was manufactured by coaxially mounting 41 OD blades on a shaft at an axial spacing of 2.1 mm, with spacers interposed therebetween.
  • the spacers each had an outer diameter 95 mm, inner diameter 40 mm, and thickness 2.1 mm.
  • the multiple blade assembly was designed so that the magnet block was cut into magnet strips having a thickness of 2.0 mm.
  • the multiple blade assembly consisting of 41 OD blades and 40 spacers alternately mounted on the shaft was combined with a cutting fluid feed nozzle as shown in FIG. 3 , such that the outer peripheral portion of each OD blade was inserted into the corresponding slit in the feed nozzle. Specifically an outer portion of the OD blade radially extending 8 mm from the blade tip was inserted into the slit.
  • the slit portion of the feed nozzle had a wall thickness of 2.5 mm, and the slits had a width of 0.6 mm.
  • the OD blade extended in alignment with the slit.
  • the workpiece was a sintered Nd—Fe—B magnet block having a length 100 mm, width 30 mm and height 17 mm, which was polished on all six surfaces at an accuracy of ⁇ 0.05 mm by a vertical double-disk polishing tool.
  • the magnet block was transversely machined and longitudinally divided into a multiplicity of magnet strips of 2.0 mm thick. Specifically, one magnet block was cut into 40 magnet strips.
  • alignment was performed using the side surface of the magnet block appearing on the front side in FIG. 4 a as the reference.
  • the upper surface of the jig on the side of the multiple blade assembly
  • a cutting fluid was fed at a flow rate of 30 L/min.
  • the multiple blade assembly was placed above one jig segment by which the magnet block was secured, and moved downward toward the magnet block so that the OD blades were inserted 1 mm from their tip into the guide grooves.
  • the multiple blade assembly was fed at a rate of 100 mm/min from the one to the other jig segment for machining the magnet block in its transverse direction.
  • the assembly was fed back to the one jig segment side without changing its height. In this way, cutoff grooves of 1 mm deep were formed in the magnet block.
  • the multiple blade assembly was moved 1 mm downward toward the magnet block. While feeding cutting fluid from the feed nozzle and rotating the OD blades at 7,000 rpm, the multiple blade assembly was fed at a rate of 100 mm/min from the one to the other jig segment for machining the magnet block in its transverse direction. At the end of this stroke, the assembly was fed back to the one jig segment side without changing its height. This machining operation was repeated 9 times in total. In this way, cutoff grooves of 9 mm deep from the upper surface were formed in the magnet block.
  • the magnet block was once released from the jig.
  • the magnet block was turned upside down such that the side surface of the magnet block appearing on the front side in FIG. 4 a might appear on the front side again after the upside-down turning. Alignment was conducted using the side surface of the magnet block appearing on the front side in FIG. 4 a as the reference, and the magnet block was secured in place again by the jig.
  • the multiple blade assembly above one jig segment was moved downward toward the magnet block so that the OD blades were inserted 1 mm from their tip into the guide grooves. While feeding cutting fluid from the feed nozzle and rotating the OD blades at 7,000 rpm, the multiple blade assembly was fed at a rate of 100 mm/min from the one to the other jig segment for machining the magnet block in its transverse direction. At the end of this stroke, the assembly was fed back to the one jig segment side without changing its height. In this way, cutoff grooves of 1 mm deep were formed in the magnet block.
  • the multiple blade assembly was moved 1 mm downward toward the magnet block. While feeding cutting fluid from the feed nozzle and rotating the OD blades at 7,000 rpm, the multiple blade assembly was fed at a rate of 100 mm/min from the one to the other jig segment for machining the magnet block in its transverse direction. At the end of this stroke, the assembly was fed back to the one jig segment side without changing its height. This machining operation was repeated 9 times in total. In this way, cutoff grooves were formed in the magnet block to a depth of 9 mm from the upper surface whereupon the cutoff grooves merged with each other, that is, the magnet block was cut into discrete strips.
  • a magnet block was cutoff machined by the same procedure as in Example 1 except that the spacers used in the multiple blade assembly each had an outer diameter 80 mm, inner diameter 40 mm, and thickness 2.1 mm, and the magnet block was machined throughout its overall height by repeating the 1-mm machining operation 18 times in total without turning the magnet block upside down at a mid stage. In this way, 1,000 magnet blocks were cutoff machined, and the machined state was evaluated. The evaluation results are also shown in Table 1.
  • the multiple cutoff machining method of the invention maintains consistent dimensional accuracy for products over a long term despite the reduced blade thickness and is successful in reducing the number of spacer adjustments and the number of OD blade replacements. Then an increase in productivity is attained.
  • OD blades cutoff abrasive blades
  • a doughnut-shaped disk core of cemented carbide consisting of WC 90 wt %/Co 10 wt %) having an outer diameter 115 mm, inner diameter 40 mm, and thickness 0.35 mm, and bonding, by the resin bonding technique, artificial diamond abrasive grains to an outer peripheral rim of the core to form an abrasive section (peripheral cutting part) containing 25% by volume of diamond grains with an average particle size of 150 ⁇ m.
  • the axial extension of the abrasive section from the core was 0.025 mm on each side, that is, the abrasive portion had a width of 0.4 mm (in the thickness direction of the core).
  • a cutting test was carried out on a workpiece which was a sintered Nd—Fe—B magnet block.
  • the test conditions are as follows.
  • a multiple blade assembly was manufactured by coaxially mounting 42 OD blades on a shaft at an axial spacing of 2.1 mm, with spacers interposed therebetween.
  • the spacers each had an outer diameter 90 mm, inner diameter 40 mm, and thickness 2.1 mm.
  • the multiple blade assembly was designed so that the magnet block was cut into magnet strips having a thickness of 2.0 mm.
  • the multiple blade assembly consisting of 42 OD blades and 41 spacers alternately mounted on the shaft was combined with a cutting fluid feed nozzle as shown in FIG. 3 , such that the outer peripheral portion of each OD blade was inserted into the corresponding slit in the feed nozzle. Specifically an outer portion of the OD blade radially extending 8 mm from the blade tip was inserted into the slit.
  • the slit portion of the feed nozzle had a wall thickness of 2.5 mm, and the slits had a width of 0.6 mm.
  • the OD blade extended in alignment with the slit.
  • the workpiece was a sintered Nd—Fe—B magnet block having a length 99 mm, width 30 mm and height 17 mm, which was polished on all six surfaces at an accuracy of ⁇ 0.05 mm by a vertical double-disk polishing tool.
  • the magnet block was transversely machined and longitudinally divided into a multiplicity of magnet strips of 2.0 mm thick. Specifically, one magnet block was cut into 41 magnet strips.
  • Three sintered Nd—Fe—B magnet blocks were arranged in a transverse direction.
  • the jig segments had dimensions of 100 mm, 100 mm, and 17 mm in the longitudinal, transverse and height directions of the magnet block, respectively.
  • the guide grooves were formed in the segment adjacent to the magnet block and extended vertically throughout the segment.
  • alignment was performed using the side surface of the magnet blocks appearing on the rear side in FIG. 5 a as the reference.
  • the upper surface of the jig on the side of the multiple blade assembly
  • a cutting fluid was fed at a flow rate of 30 L/min.
  • the multiple blade assembly was placed above one jig segment by which the magnet blocks were secured, and moved downward toward the magnet block so that the OD blades were inserted 9 mm from their tip into the guide grooves.
  • the multiple blade assembly was fed at a rate of 20 mm/min from the one to the other jig segment for machining the magnet blocks in their transverse direction.
  • the assembly was fed back to the one jig segment side without changing its height. In this way, cutoff grooves of 9 mm deep were formed in the magnet blocks.
  • the jig was turned upside down such that the side surface of the jig appearing on the front side in FIG. 5 a might appear on the front side again after the upside-down turning. Alignment was conducted using the side surface of the magnet block appearing on the rear side in FIG. 5 a as the reference, and the jig was secured for holding the magnet blocks in place again.
  • the multiple blade assembly above one jig segment was moved downward toward the magnet block so that the OD blades were inserted 9 mm from their tip into the guide grooves.
  • the multiple blade assembly was fed at a rate of 20 mm/min from the one to the other jig segment for machining the magnet blocks in their transverse direction.
  • the assembly was fed back to the one jig segment side without changing its height. In this way, cutoff grooves were formed in the magnet blocks to a depth of 9 mm from their upper surface whereupon the cutoff grooves merged with each other, that is, the magnet block was cut into discrete strips.
  • magnet strips were cut using the OD blades constructed as above, they were measured for thickness between the machined surfaces at the center by a micrometer. The strips were rated “passed” if the measured thickness was within a cut size tolerance of 2.0 ⁇ 0.05 mm. If the measured thickness was outside the tolerance, the multiple blade assembly was tailored by adjusting the thickness of spacers, so that the measured thickness might fall within the tolerance. If the spacer adjustment was repeated more than two times for the same OD blades, these OD blades were judged as having lost stability and replaced by new OD blades. Under these conditions, 1,000 magnet blocks were cutoff machined. The evaluation results of the machined state are shown in Table 2.
  • the multiple cutoff machining method of the invention maintains consistent dimensional accuracy for products over a long term despite the thin abrasive blade based on cemented carbide core and is successful in reducing the number of spacer adjustments and the number of OD blade replacements. Then increases in productivity and the number of cutoff strips are attained.
  • OD blades cutoff abrasive blades
  • a doughnut-shaped disk core of cemented carbide consisting of WC 90 wt %/Co 10 wt %) having an outer diameter 145 mm, inner diameter 40 mm, and thickness 0.5 mm, and bonding, by the resin bonding technique, artificial diamond abrasive grains to an outer peripheral rim of the core to form an abrasive section (peripheral cutting part) containing 25% by volume of diamond grains with an average particle size of 150 ⁇ m.
  • the axial extension of the abrasive section from the core was 0.05 mm on each side, that is, the abrasive portion had a width of 0.6 mm (in the thickness direction of the core).
  • a cutting test was carried out on a workpiece which was a sintered Nd—Fe—B magnet block.
  • the test conditions are as follows.
  • a multiple blade assembly was manufactured by coaxially mounting 14 OD blades on a shaft at an axial spacing of 3.1 mm, with spacers interposed therebetween.
  • the spacers each had an outer diameter 100 mm, inner diameter 40 mm, and thickness 3.1 mm.
  • the multiple blade assembly was designed so that the magnet block was cut into magnet strips having a thickness of 3.0 mm.
  • the multiple blade assembly consisting of 14 OD blades and 13 spacers alternately mounted on the shaft was combined with a cutting fluid feed nozzle as shown in FIG. 3 , such that the outer peripheral portion of each OD blade was inserted into the corresponding slit in the feed nozzle. Specifically an outer portion of the OD blade radially extending 8 mm from the blade tip was inserted into the slit.
  • the slit portion of the feed nozzle had a wall thickness of 2.5 mm, and the slits had a width of 0.8 mm.
  • the OD blade extended in alignment with the slit.
  • the workpiece was a sintered Nd—Fe—B magnet block having a length 47 mm, width 70 mm and height 40 mm, which was polished on all six surfaces at an accuracy of ⁇ 0.05 mm by a vertical double-disk polishing tool.
  • the magnet block was transversely machined and longitudinally divided into a multiplicity of magnet strips of 3.0 mm thick. Specifically, one magnet block was cut into 13 magnet strips.
  • alignment was performed using the side surface of the magnet block appearing on the front side in FIG. 4 a as the reference.
  • the upper surface of the jig on the side of the multiple blade assembly
  • a cutting fluid was fed at a flow rate of 30 L/min.
  • the multiple blade assembly was placed above one jig segment by which the magnet block was secured, and moved downward toward the magnet block so that the OD blades were inserted 1 mm from their tip into the guide grooves.
  • the multiple blade assembly was fed at a rate of 150 mm/min from the one to the other jig segment for machining the magnet block in its transverse direction.
  • the assembly was fed back to the one jig segment side without changing its height. In this way, cutoff grooves of 1 mm deep were formed in the magnet block.
  • the multiple blade assembly was moved 1 mm downward toward the magnet block. While feeding cutting fluid from the feed nozzle and rotating the OD blades at 9,000 rpm, the multiple blade assembly was fed at a rate of 150 mm/min from the one to the other jig segment for machining the magnet block in its transverse direction. At the end of this stroke, the assembly was fed back to the one jig segment side without changing its height. This machining operation was repeated 21 times in total. In this way, cutoff grooves of 21 mm deep from the upper surface were formed in the magnet block.
  • the magnet block was once released from the jig.
  • the magnet block was turned upside down such that the side surface of the magnet block appearing on the front side in FIG. 4 a might appear on the front side again after the upside-down turning. Alignment was conducted using the side surface of the magnet block appearing on the front side in FIG. 4 a as the reference, and the magnet block was secured in place again.
  • the multiple blade assembly above one jig segment was moved downward toward the magnet block so that the OD blades were inserted 1 mm from their tip into the guide grooves. While feeding cutting fluid from the feed nozzle and rotating the OD blades at 9,000 rpm, the multiple blade assembly was fed at a rate of 150 mm/min from the one to the other jig segment for machining the magnet block in its transverse direction. At the end of this stroke, the assembly was fed back to the one jig segment side without changing its height. In this way, cutoff grooves of 1 mm deep were formed in the magnet block.
  • the multiple blade assembly was moved 1 mm downward toward the magnet block. While feeding cutting fluid from the feed nozzle and rotating the OD blades at 9,000 rpm, the multiple blade assembly was fed at a rate of 150 mm/min from the one to the other jig segment for machining the magnet block in its transverse direction. At the end of this stroke, the assembly was fed back to the one jig segment side without changing its height. This machining operation was repeated 20 times in total. In this way, cutoff grooves were formed to a depth of 20 mm from the magnet block surface whereupon the cutoff grooves merged with each other, that is, the magnet block was cut into discrete strips.
  • the magnet strips cut using the OD blades constructed as above were measured for thickness between the machined surfaces at five points (center and corners) as shown in FIG. 6 c by a micrometer. A difference between maximum and minimum thicknesses was determined, with the results shown in the graph of FIG. 6 a.
  • a magnet block was cutoff machined by the same procedure as in Example 3 except that the spacers used in the multiple blade assembly each had an outer diameter 60 mm, inner diameter 40 mm, and thickness 3.1 mm, and the magnet block was machined throughout its overall height by repeating the 1-mm machining operation 41 times in total without turning the magnet block upside down at a mid stage. The results of thickness difference are shown in the graph of FIG. 6 b.
  • the graphs of FIGS. 6 a and 6 b demonstrate that the multiple cutoff machining method of the invention achieves a significant improvement in the accuracy of cutoff machining.

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JP2012000708A (ja) 2012-01-05
CN102285007A (zh) 2011-12-21
US10391602B2 (en) 2019-08-27
KR20110137248A (ko) 2011-12-22
SG177099A1 (en) 2012-01-30
TWI551413B (zh) 2016-10-01
US20180200860A1 (en) 2018-07-19
CN102285007B (zh) 2015-09-09
EP2397254B1 (en) 2014-04-09
TW201217130A (en) 2012-05-01
EP2397254A1 (en) 2011-12-21
JP5505114B2 (ja) 2014-05-28
KR101782388B1 (ko) 2017-09-27
MY160802A (en) 2017-03-31

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