Dental end mill and dental machining device

Abstract

To smoothly machine a surface of a dental prosthesis in machining using a dental end mill.SOLUTION: A dental end mill 10 for machining a workpiece comprises a shank part 11 to be held by a dental machining device, and a neck lower part 12 connected to the shank part 11. The neck lower part 12 includes a plurality of end cutting edges 13 formed on a tip side not connected to the shank part 11, and a plurality of peripheral cutting edges 16 formed in a spiral shape at predetermined intervals on an outer peripheral surface on the tip side. The plurality of end cutting edges 13 are so formed that intervals between the adjacent end cutting edges 13 are unequally divided. At least two peripheral cutting edges out of the plurality of peripheral cutting edges 16 are formed at different inclination angles. A method for machining a workpiece includes a step of machining the workpiece using the dental end mill 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a dental end mill and a dental processing device including the dental end mill. [Background technology]

[0002] Dental prostheses are manufactured by cutting a workpiece using a dental end mill (for example, Patent Document 1). A cutting tool having a helical blade and grooves is generally called an end mill.

[0003] Incidentally, various techniques are known for improving the machining quality of a workpiece by an end mill (see, for example, Patent Documents 2 and 3).

[0004] Patent Document 2 discloses a cutting tool including an end mill, in which a plurality of bottom blades are formed on the tip side and a plurality of peripheral blades are formed on the outer peripheral surface of the tip side. It also discloses that the plurality of bottom blades are unequally divided, and the plurality of peripheral blades are set to unequal leads. However, this end mill is suitable for cutting industrially difficult-to-cut materials such as stainless steel, titanium alloys, and heat-resistant alloys, and is therefore an industrial end mill. For this reason, there is no mention of processing dental materials, and it is not suitable for processing complex and diverse dental prostheses. Here, unequal division refers to the angle between adjacent bottom blades among the plurality of bottom blades not being divided uniformly. Unequal lead refers to the twist angle of adjacent peripheral blades among the plurality of peripheral blades being alternatingly different.

[0005] Patent Document 3 discloses a cutting tool including a ball end mill, in which three or more end blades are formed on the tip surface. It also discloses that the end blades are unequally divided. However, this ball end mill is an industrial end mill, since it is used to cut high-hardness materials such as small and precise machine parts and molds, non-ferrous metals, and general steel materials. For this reason, there is no mention of processing dental materials, and it is not suitable for processing complex and diverse dental prostheses. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2023 / 282173 [Patent Document 2] JP 2020-192611 A [Patent Document 3] JP 2021-115684 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present disclosure has been made in consideration of the above circumstances, and makes it possible to smoothly process the surface of a dental prosthesis when processed with a dental end mill. [Means for solving the problem]

[0008] In order to solve the above problems, the inventors focused on the shape of the neck portion (blade) of dental end mills and conducted extensive research. As a result, they discovered that the above problems can be solved by focusing on the shape of the neck portion of dental end mills. Based on this knowledge, they conducted further research and completed the present invention.

[0009] That is, the dental end mill according to the present disclosure is a dental end mill for processing a workpiece, and includes a shank portion held by a dental processing device and a neck portion connected to the shank portion. The neck portion has a plurality of bottom blades formed on the tip side not connected to the shank portion, and a plurality of peripheral blades formed in a spiral shape at a predetermined interval on the outer peripheral surface on the tip side. The plurality of bottom blades are unequally spaced apart from each other. At least two of the plurality of peripheral blades are formed at different inclination angles.

[0010] In addition, a dental processing apparatus according to the present disclosure is a dental processing apparatus equipped with the above-mentioned dental end mill. Effect of the Invention

[0011] According to the present disclosure, it is possible to smoothly process the surface of a dental prosthesis using a dental end mill. [Brief description of the drawings]

[0012] [Figure 1] 1A and 1B are a left side view and a plan view showing a configuration of a dental end mill according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a simplified left side view of FIG. 1, and is a schematic view illustrating that the intervals between adjacent bottom cutting edges are unequal. [Diagram 3] FIG. 11 is a schematic diagram illustrating that the intervals between adjacent bottom cutting edges are equally divided. [Figure 4] FIG. 2 is a simplified plan view of FIG. 1, and is a schematic diagram illustrating the inclination angles of the two peripheral cutting edges. [Diagram 5] FIG. 2 is a diagram for explaining a workpiece and a dental prosthesis, showing an example of the workpiece and a dental prosthesis obtained by cutting the workpiece. [Figure 6] FIG. 2 is a diagram for explaining a dental processing apparatus according to one embodiment of the present disclosure, and is a schematic diagram of the dental processing apparatus equipped with the dental end mill shown in FIG. 1. [Figure 7A] This is a schematic diagram of another modified dental end mill, which has three bottom cutting edges and one of the three angles formed by adjacent bottom cutting edges is different from the remaining two angles. [Figure 7B] This is a schematic diagram of another modified dental end mill having four bottom cutting edges, one of the four angles formed by adjacent bottom cutting edges being different from the remaining three angles. [Figure 7C] This is a schematic diagram of another modified dental end mill having five bottom cutting edges, one of the five angles formed by adjacent bottom cutting edges being different from the remaining four angles. [Figure 8A]This is a schematic diagram of another modified dental end mill having three bottom cutting edges, with the three angles formed by adjacent bottom cutting edges being different from each other. [Figure 8B] This is a schematic diagram of another variant of a dental end mill, which has five bottom cutting edges, and of the five angles formed by adjacent bottom cutting edges, three are different angles and adjacent angles are different. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (Structure of dental end mill 10) A dental end mill 10 according to one embodiment of the present invention will be described below with reference to Figures 1 to 4. The dental end mill 10 according to this embodiment is mounted on a dental processing device 1 (see Figure 6) described below, and is used to process a workpiece W (material to be cut) to produce a dental prosthesis P (see Figure 5).

[0014] The dental end mill 10 according to this embodiment includes a shank portion 11 and a neck portion 12. The neck portion 12 is connected to the shank portion 11. Therefore, the shank portion 11 and the neck portion 12 are integrally formed as the dental end mill 10. The neck portion 12 has no organic components on a surface 12a of the neck portion 12, and is formed of, for example, a cemented carbide. In this embodiment, the neck portion 12 of the dental end mill 10 may be a cemented carbide that has been treated with a diamond coat or the like, or may be a non-coated product that has not been coated.

[0015] "No organic components are present" does not only mean that organic components are not present in the strict sense, but also means that organic components are present to an extent that does not cause hygiene problems when used for dental purposes and does not affect the deterioration of the physical properties of the workpiece. In other words, "no organic components are present" does not only mean that organic components are not present in the strict sense, but also means that organic components are almost not present.

[0016] Here, the material of the neck portion 12 is not limited to cemented carbide. Suitable materials for the neck portion 12 include, for example, cermet, which is a composite material of ceramics and metal, cemented carbide such as tungsten carbide (WC)-based cemented carbide, ultra-high pressure sintered body (CBN, cubic boron nitride), high speed tool steel, polycrystalline diamond (PCD), etc. The coating process used for the neck portion 12 of the dental end mill 10 is not limited to diamond coating, and may be DLC, TiN, CrN, etc.

[0017] (Diameter of dental end mill 10) The diameter D1 (blade diameter) of the neck portion 12 of the dental end mill 10 is preferably smaller than the diameter D2 (shank diameter) of the shank portion 11. That is, the diameter D1 of the neck portion 12 is preferably 0.1 mm or more and 6.0 mm or less, and more preferably 0.3 mm or more and 2.0 mm or less. If the diameter D1 of the neck portion 12 is too large compared to the upper limit, fine machining is not possible, which is not preferable. Also, if the diameter D1 of the neck portion 12 is too small compared to the lower limit, machining efficiency is reduced, which is not preferable. The diameter D2 of the shank portion 11 is preferably 2.0 mm or more and 10.0 mm or less.

[0018] (Blade shape of dental end mill 10) In the dental end mill 10, the shape of the tip side (tip portion) of the neck portion 12 that is not connected to the shank portion 11 can be selected from flat end shapes, radius end shapes, ball end shapes, etc., but since the dental prosthesis P is composed of a free curved surface, a hemispherical ball end shape as shown in Figure 1 is preferable. This makes it possible to obtain a dental prosthesis P with a smooth surface texture.

[0019] The neck portion 12 has a plurality of bottom cutting edges 13 and a plurality of peripheral cutting edges 16. The plurality of bottom cutting edges 13 are formed on the tip side. The number of bottom cutting edges 13 is, for example, four. Each bottom cutting edge 13 is formed at the intersection of each rake face 14 and each flank face 15. The rake face 14 is the surface through which chips pass during cutting. The flank face 15 is an angled surface to avoid unnecessary friction with the cutting surface.

[0020] The intervals between the adjacent bottom blades 13 of the multiple bottom blades 13 are unequally divided. Unequally divided means that the angle between the adjacent bottom blades 13 is not uniformly divided. For example, a description will be given with reference to FIG. 2. A case will be described in which the angle between the adjacent bottom blades 13A and 13B is θ1, the angle between the adjacent bottom blades 13B and 13C is θ2, the angle between the adjacent bottom blades 13C and 13D is θ3, and the angle between the adjacent bottom blades 13D and 13A is θ4. In this case, the angle θ1 is different from the adjacent angles θ2 and θ4, and the angle θ1 is the same as the opposing angle θ3. Similarly, the adjacent angles are different and the opposing angles are the same for each of the angles θ2 to θ4. The angles θ1 to θ4 are 10° or more and less than 180°. For example, the angles θ1 and θ3 are 105°, and the angles θ2 and θ4 are 75°.

[0021] Here, equal division as opposed to unequal division will be explained with reference to the simplified diagram of Fig. 3. Equal division is a division in which the angle θ5 between adjacent bottom blades 13 is constant. In the case of four bottom blades 13, each angle is the same 90°.

[0022] As shown in FIG. 1, the multiple peripheral blades 16 are formed in a spiral shape at a predetermined interval on the outer peripheral surface (side surface) of the tip side of the neck portion 12, continuing from each bottom blade 13. For this reason, the dental end mill 10 can cut, for example, in a direction intersecting the center line CL of the dental end mill 10, using the multiple peripheral blades 16. Since the multiple peripheral blades 16 are formed in a spiral shape continuing from each bottom blade 13, the multiple peripheral blades 16 are four, like the four bottom blades 13. Each peripheral blade 16 is formed at a portion where the peripheral flank 17 and the peripheral groove 18 intersect. The peripheral flank 17 is a surface formed on the outer peripheral surface, and is an angled surface to avoid unnecessary friction with the cutting surface when cutting with the multiple peripheral blades 16. The peripheral groove 18 is a recessed portion formed between the adjacent peripheral blades 16 and the peripheral flank 17, and is a groove through which chips pass during cutting.

[0023] As shown in FIG. 4, among the four peripheral blades 16, for example, two peripheral blades 16A and 16B are formed with different inclination angles (angles θ11 and θ13). The inclination angle is the twist angle (twist angle) of the two peripheral blades 16A and 16B. The inclination angle is an acute angle among the angles at which each of the two peripheral blades 16A and 16B intersects with the center line CL in the longitudinal direction of the dental end mill 10. Above the center line CL in FIG. 4, the inclination angle of one peripheral blade 16A is the acute angle θ11 between the angles θ11 and θ12. Similarly, above the center line CL, the inclination angle of the other peripheral blade 16B is the acute angle θ13 between the angles θ13 and θ14. The angles θ11 and θ13 are 20° or more and 60° or less, for example, the angle θ11 is 35° and the angle θ13 is 38°. The remaining two inclination angles may be the same as either the angle θ11 or θ13, or adjacent inclination angles may be alternately different, or all four inclination angles may be different. In short, it is sufficient that at least two inclination angles are different.

[0024] (Length L1 of dental end mill 10 and length L2 of neck part 12) The length L1 of the dental end mill 10, which is the sum of the shank portion 11 and the neck portion 12 shown in FIG. 1, is not particularly limited, but is preferably 30.0 mm or more and 100.0 mm or less. The length L2 of the neck portion 12 shown in FIG. 1 is not particularly limited, but is preferably 1.0 mm or more and 30.0 mm or less, and more preferably 1.0 mm or more and 5.0 mm or less. If the length L1 of the dental end mill 10 and the length L2 of the neck portion 12 are each longer than the upper limit value, the rigidity decreases, which is not preferable, and if they are shorter than the lower limit value, the processing range is limited, which is not preferable. If the length L1 of the dental end mill 10 is shorter than the lower limit value, and especially if the length (=L1-L2) of the shank portion 11 is short, the holding force of the spindle 2a (see FIG. 6) of the dental processing device 1 described later decreases, which is not preferable.

[0025] (Shank 11) The shank portion 11 shown in FIG. 1 is made of, for example, a carbide substrate. The carbide substrate is not particularly limited, but may be, for example, a cermet, which is a composite material of ceramics and metal, or a carbide alloy such as a tungsten carbide (WC)-based carbide alloy, but is not limited thereto. When the shank portion 11 and the neck portion 12 are made of the same material, the shank portion 11 and the neck portion 12 are not joined, and are integrally formed from the stage of forming the dental end mill 10. When the shank portion 11 and the neck portion 12 are made of different materials, the neck portion 12 of the dental end mill 10 is joined to each other by, for example, welding, brazing, or the like. This configuration improves the durability of the dental end mill 10.

[0026] (Material of workpiece W) The material of the workpiece W (see FIG. 5) cut by the dental end mill 10 of this embodiment is not particularly limited as long as it is a dental material, but dental ceramics, dental resins, and dental metals (e.g., titanium alloys, etc.) are preferred. By using dental ceramics as the material of the workpiece W, a dental prosthesis P with excellent long-term aesthetics can be obtained because it has high biocompatibility and strength and is less likely to deteriorate over time. In addition, by using dental resin as the material of the workpiece W, a dental prosthesis P with good biocompatibility, strength, aesthetics, and light weight can be obtained relatively inexpensively and in a short time. Furthermore, by using dental metal as the material of the workpiece W, a dental prosthesis P with high strength can be obtained. In addition, the shape of the workpiece W is not particularly limited, and it may be any shape such as a block shape or a disk shape.

[0027] (Type of dental prosthesis P to be processed) The dental end mill 10 of this embodiment does not limit the type of dental prosthesis P to be machined. For example, the dental prosthesis P to be machined may be an artificial tooth corresponding to any of a central incisor, a lateral incisor, a canine, and a molar, and examples of the dental prosthesis P include, but are not limited to, a crown, an inlay, an onlay, a bridge, a multiple crown, and a crown to be attached to an abutment of an implant.

[0028] (Dental processing device 1 equipped with dental end mill 10) Hereinafter, a dental processing device 1 according to an embodiment of the dental processing device of the present disclosure will be described with reference to Figs. 5-6. As shown in Fig. 6, the dental processing device 1 includes a cutting unit 2, a holding unit 3, a control unit 4, a door body 5, and the like. The cutting unit 2 includes a spindle (main shaft) 2a for holding a dental end mill 10, a motor 2b for rotating the spindle 2a, a moving unit for moving the spindle 2a in a predetermined direction, and the like. The holding unit 3 includes a holding member 3a for holding a workpiece W, a moving unit for moving the holding member 3a in a predetermined direction, and the like. The control unit 4 includes an NC device or the like including a processor, a memory, an operation button, and the like. The door body 5 is provided so as to be freely opened and closed, and is capable of inserting and removing the workpiece W and the dental prosthesis P. The dental processing device 1 is a dental CNC multi-axis processing device that can be automated and mass-produced. The dental processing apparatus 1 processes a workpiece W by operating the cutting unit 2 and the like by the control unit 4 based on a processing program created in advance using dental CAM software or the like.

[0029] Specific processing conditions of the dental processing device 1 will be described. A processing tool (dental end mill 10) in which a cemented carbide alloy is used in the neck portion 12 is attached to the dental processing device 1 (DWX-52D manufactured by DGSHAPE). Using this dental processing device 1, dental zirconia ("Noritake Katana (registered trademark) Zirconia Block ONE", manufactured by Kuraray Noritake Dental Co., Ltd.) [17.8 mm x 19.2 mm x 20.2 mm] as a workpiece W is cut under the high-precision processing conditions for a dental crown shown in Table 1 below. A dental prosthesis P in the shape of a dental crown (see FIG. 5, before firing) is obtained by cutting.

[0030] Table 1 below shows an example of processing conditions. The spindle rotation speed shown in Table 1 indicates the spindle rotation speed of the spindle that holds the dental end mill 10, the spindle feed speed indicates the spindle movement feed speed, the cutting depth indicates the processing depth in the Z direction, and the cutting width indicates the processing width in the XY directions. The Z direction is the axial direction of the spindle, and the XY directions are directions that form a plane perpendicular to the Z direction.

[0031] Furthermore, the numerical values ​​(machining conditions) listed in Table 1 below are not particularly limited. The spindle rotation speed is preferably 5,000 rpm or more and 80,000 rpm or less. The spindle feed speed is preferably 500 mm / min or more and 5,000 mm / min or less. The cutting depth is preferably 0.1 mm or more and 3.0 mm or less. The cutting width is preferably 0.1 mm or more and 3.0 mm or less.

[0032] [Table 1]

[0033] As shown in Fig. 5, for example, a block body having a substantially cubic shape is used as the workpiece W. A metal mounting member 6 for mounting the workpiece W to the holding part 3 is adhesively fixed to one surface of the workpiece W. The mounting member 6 is provided with a base 6a and a pin 6b protruding from the base 6a. As shown in Fig. 6, the holding member 3a is provided with a hole 3b into which the base 6a and the pin 6b are inserted and fixed. By inserting the base 6a and the pin 6b into the hole 3b, the workpiece W is fixed by the holding member 3a, and unexpected falling off, rattling, and the like are suppressed.

[0034] As shown in Fig. 6, the dental end mill 10 of this embodiment is attached to the spindle 2a of such a dental processing device 1, and a workpiece W is attached to the holding member 3a. After that, the relative positional relationship between the dental end mill 10 and the workpiece W is changed in three dimensions, and the dental end mill 10 is rotated. This makes it possible to carry out the processing method of this embodiment.

[0035] That is, the processing method according to this embodiment is a method for processing a workpiece W executed by a dental processing apparatus 1 equipped with the dental end mill 10 according to this embodiment, and includes a process of processing the workpiece W using the dental end mill 10 of this embodiment. This process includes a rough processing process and a finish processing process using the dental end mill 10. Furthermore, the processing method according to this embodiment may include a coloring process, a firing process, and the like in addition to this process.

[0036] The mechanism of the dental baking furnace used in the baking step is not particularly limited, and may be an electric heater type, an IH type, or a microwave type.

[0037] First, the workpiece W is processed by the dental processing apparatus 1 into a dental prosthesis P in the shape of a crown (see FIG. 5, before firing).

[0038] Next, the dental prosthesis P is subjected to a firing process in a dental firing furnace at a predetermined temperature (e.g., 1,550°C) and for a predetermined time (e.g., 90 minutes) according to the composition of the dental prosthesis P, and a final prosthesis is obtained by the firing process. The final prosthesis is in a state where the dental prosthesis P has been fired and hardened.

[0039] The final prosthesis that has undergone the firing process is then polished to complete. The purpose of polishing is to improve the appearance of the product by adding a glossy finish, and to ensure the mechanical performance of the prosthesis.

[0040] Furthermore, when the dental prosthesis P (see FIG. 5) in the shape of a crown that has undergone a processing step is fired at a predetermined temperature (e.g., 1,550°C) and then dental porcelain is built up to produce the final prosthesis, dental porcelain (e.g., Cerabian ZR External Stain E Glaze) is built up on the fired dental prosthesis P. After this building up, the dental prosthesis P is fired at a predetermined temperature (e.g., 850°C) and for a predetermined time (e.g., 1 minute of retention at the predetermined temperature) according to the composition of the dental prosthesis P and the dental porcelain, and the final prosthesis is obtained.

[0041] (effect) As described above, according to the dental end mill 10 and dental processing device 1 of this embodiment, as shown in Figs. 1-2, the intervals (angles θ1-θ4) between the adjacent bottom blades (13A and 13B, 13B and 13C, 13C and 13D, 13D and 13A) of the multiple bottom blades 13 are unequally divided. That is, when the workpiece W is cut by the dental end mill 10, the period in which the workpiece W and the four bottom blades 13 come into contact with each other is shifted, thereby avoiding unnecessary friction with the cutting surface, and vibration (chatter vibration) during cutting is suppressed more than when the workpiece W and the four bottom blades 13 come into contact with each other periodically. Furthermore, according to the dental end mill 10 and dental processing device 1 of this embodiment, as shown in Figs. 1 and 4, two of the four peripheral blades 16, 16A and 16B, are formed with different inclination angles (θ11, θ13). That is, when the workpiece W is cut by the dental end mill 10, the direction in which the cutting chips pass changes, and the period in which the workpiece W and the two peripheral cutting edges 16A, 16B come into contact shifts, so that vibrations (chatter vibrations) during cutting are suppressed more than when the workpiece W and the two peripheral cutting edges 16A, 16B come into contact periodically. In short, when the workpiece W is cut by the dental end mill 10 shown in Fig. 1, that is, using only the four bottom cutting edges 13, only the four peripheral cutting edges 16, or both the four bottom cutting edges 13 and the four peripheral cutting edges 16, vibrations (chatter vibrations) during cutting are suppressed.

[0042] Therefore, in the processing using the dental end mill 10, it is possible to process the surface of the dental prosthesis P (see FIG. 5) smoothly. In other words, when the processing of the workpiece W by the dental end mill 10 is completed, the dental prosthesis P having a smooth surface property can be obtained. In this way, since the dental prosthesis P having a smooth surface property can be obtained, even if there is a polishing residue generated when the shape of the crown is complicated in the polishing process for the purpose of ensuring mechanical performance performed after the firing process, it is possible to prevent the adhesion of plaque to the surface of the final prosthesis after the oral cavity is mounted. In addition, when a porcelain material is used in other finishing processes, it is possible to prevent the entrapment of air bubbles during the porcelain material build-up and to increase the firing strength of the porcelain material.

[0043] As described above, when the workpiece W is cut using the dental end mill 10 of this embodiment, vibrations (chatter vibrations) during cutting are suppressed. Therefore, even under high-load processing conditions, the processing conditions are maintained, and the processing time can be shortened. For example, even under high-load processing conditions in which the spindle rotation speed is faster than that shown in Table 1, the accuracy does not decrease and the processing time can be shortened, and the dental end mill 10 of this embodiment can obtain a high-precision and high-definition dental prosthesis P in a short time. Furthermore, by suppressing vibrations (chatter vibrations) during cutting, the dental end mill 10 of this embodiment can save the effort of manual polishing work. As a result, the dental end mill 10 and dental processing device 1 of this embodiment can suppress the deterioration of the processing quality of the dental prosthesis P and stably obtain a high-precision dental prosthesis P. In addition, the dental end mill 10 and dental processing device 1 of this embodiment make it possible to more precisely and smoothly process dental prostheses P of complex and diverse shapes, whose shapes, sizes, and crown lengths vary from patient to patient, site to site, and case to case.

[0044] 1 and 4, the dental end mill 10 of this embodiment has four peripheral cutting edges 16, of which two are formed with different inclination angles (θ11, θ13), so that the direction in which chips pass changes when the dental end mill 10 cuts the workpiece W. This prevents the peripheral groove 18 from becoming clogged with chips.

[0045] In addition, since conventional end mills are for industrial use, organic components (e.g., oil) are attached to the surfaces of the bottom blades and peripheral blades. For this reason, when conventional end mills are used for dental use, it is unhygienic, and depending on the material of the workpiece W to be cut, there is a risk of deterioration in physical properties. In contrast, according to the dental end mill 10 and dental processing device 1 of this embodiment, no organic components are present on the surface 12a of the neck portion 12. That is, when the workpiece W is cut by the dental end mill 10, no organic components are present on the surfaces (surface 12a of the neck portion 12) of the four bottom blades 13 and the four peripheral blades 16 that come into contact with the workpiece W. Specifically, in industrial end mills, components contained in cutting oil, etc. used in the manufacturing process (organic components, hereinafter referred to as "components of cutting oil, etc.") remain or are applied. For example, components of cutting oils and the like include machine oils, polyolefin oils, diester oils, hindered ester oils, vegetable oils and fats, animal oils and fats, methyl esters, palm methyl esters, chlorinated paraffins, chlorinated fatty acids, chlorinated fatty acid esters, sulfurized mineral oils, sulfurized and chlorinated oils and fats, sulfurized oils and fats, polysulfides, phosphates, phosphites, zinc dialkyldithiophosphate, molybdenum compounds, fatty acid soaps, naphthenic acid soaps, long-chain alcohol sulfates, sulfated oils of animal and vegetable oils, Petroleum sulfonates, polyoxyethylene alkylphenol ethers, polyoxyethylene mono fatty acid esters, sorbitan mono fatty acid esters, fatty acid diethanolamides, carboxylic acids, carboxylates, sulfonates, phosphates, borates, carbonates, molybdates, isopropyl alcohol, polyhydric alcohols, benzotriazole, imidazoline, thiodiazole polysulfides, alkyldithiobenzimidazoles, zinc dialkyldithiophosphates, phenylphenols, tetrachlorophenols, hexahydrotriazine, tribrom salicylanilide, dibrom salicylanilide, silicones, etc. In contrast, dental end mills are shipped in a state where no organic components are attached to the surface by cleaning, etc. Therefore, components such as cutting oil are present on the surface of industrial end mills to the extent that the components of cutting oil, etc. are visible to the naked eye when touching the surface of the end mill, but components such as cutting oil are not present on the surface of dental end mills.Therefore, when the dental end mill 10 is used for dental purposes, there is no hygiene problem and no deterioration in physical properties occurs. As described above, "no organic components are present" does not only mean that organic components are strictly absent, but also that organic components are almost absent.

[0046] Furthermore, according to the dental end mill 10 and dental processing device 1 of this embodiment, as shown in Fig. 2, there are four bottom cutting edges 13, and angles θ1 to θ4 formed by adjacent bottom cutting edges (13A and 13B, 13B and 13C, 13C and 13D, and 13D and 13A) are 10° or more and less than 180°. Of the four angles θ1 to θ4 formed by adjacent bottom cutting edges (13A and 13B, 13B and 13C, 13C and 13D, and 13D and 13A), two angles θ1 and θ3 are different from the remaining angles θ2 and θ4. Specifically, among the four angles θ1 to θ4 formed by adjacent bottom blades (13A and 13B, 13B and 13C, 13C and 13D, and 13D and 13A), the adjacent angles (θ1 to θ4) are different, and the opposing angles (θ1 and θ3, θ2 and θ4) are the same. That is, when there are four bottom blades 13, the four angles θ1 to θ4 alternate in the circumferential direction (the direction of rotation of the dental end mill 10), so that the intervals between the adjacent bottom blades (13A and 13B, 13B and 13C, 13C and 13D, and 13D and 13A) are unequally divided. For this reason, as described above, when the workpiece W is cut by the dental end mill 10, the period in which the workpiece W and the four bottom blades 13 come into contact with each other is shifted, so that vibrations (chatter vibrations) during cutting are suppressed more than when the workpiece W and the four bottom blades 13 come into contact with each other periodically.

[0047] Furthermore, according to the dental end mill 10 and dental processing device 1 of this embodiment, as shown in Fig. 4, the inclination angle (θ11, θ13) is an acute angle (θ11, θ13) among the angles (θ11 and θ12, θ13 and θ14) at which each of the two peripheral blades 16A, 16B intersects with the center line CL in the longitudinal direction of the dental end mill 10, and is 20° or more and 60° or less. Specifically, the angle θ11 is 35°, and the angle θ13 is 38°. That is, when the peripheral blade 16 is four, the two peripheral blades 16A, 16B are formed with different inclination angles (θ11, θ13). For this reason, as described above, when the dental end mill 10 cuts the workpiece W, the period of contact between the workpiece W and the two peripheral blades 16A and 16B is shifted, so that vibrations (chatter vibrations) during cutting are suppressed more than when the workpiece W and the two peripheral blades 16A and 16B periodically contact each other. In addition, the inclination angles of the remaining two of the four peripheral blades 16 may be set to be different from each other so that the adjacent inclination angles are alternately different, or all four inclination angles may be set to be different. In this state, when the dental end mill 10 cuts the workpiece W, the period of contact between the workpiece W and each peripheral blade 16 is shifted more than when the remaining two inclination angles are the same as either of the angles θ11 and θ13, so that vibrations (chatter vibrations) during cutting are suppressed more.

[0048] Furthermore, in the dental field, since the processing apparatus is generally a small tabletop type, the number of end mills that can be mounted on the processing apparatus is limited. In contrast, according to the dental end mill 10 and the dental processing apparatus 1 of this embodiment, as shown in FIG. 1, the length L1 of the shank portion 11 and the neck portion 12 combined is 30.0 mm or more and 100.0 mm or less, and the length L2 of the neck portion 12 is 1.0 mm or more and 30.0 mm or less. In addition, the diameter D1 of the neck portion 12 is 0.1 mm or more and 6.0 mm or less, and the diameter D2 of the shank portion 11 is 2.0 mm or more and 10.0 mm or less. With this configuration, the dental processing apparatus 1 can mount more dental end mills 10, and a small dental processing apparatus 1 suitable for use in the dental field can be provided. In addition, by providing the dental end mill 10 having such a configuration, the dental processing apparatus 1 can perform fine processing, has excellent processing efficiency, and can process dental prostheses P of complex and diverse shapes with higher accuracy and precision.

[0049] Furthermore, in the dental end mill 10 and dental processing device 1 of this embodiment, if the neck portion 12 is formed using at least any one of polycrystalline diamond, cermet which is a composite material of ceramics and metal, cemented carbide, ultra-high pressure sintered body, and high speed tool steel, a dental end mill 10 having excellent wear resistance can be obtained.

[0050] Furthermore, in the dental end mill 10 and dental processing apparatus 1 of this embodiment, if the workpiece W is formed using at least one of dental resin, dental ceramic, and dental metal, a dental prosthesis P having excellent biocompatibility, strength, and aesthetics can be obtained.

[0051] Here, according to the dental end mill 10 and the dental processing device 1 of the embodiment described above, as shown in Fig. 1 and Fig. 2, there are four bottom cutting edges 13, and among the four angles θ1 to θ4 formed by the adjacent bottom cutting edges 13A to 13D, the adjacent angles θ1 to θ4 are different, and the opposing angles (θ1 and θ3, θ2 and θ4) are the same. However, this is not limited to this, and other configurations may be used as follows.

[0052] First, it is sufficient that there are a plurality of bottom blades 13, and for example, the bottom blades 13 may be configured as three or five, provided that the intervals between adjacent bottom blades are unequal.

[0053] Next, when the number of bottom blades is 3 to 5, the angle between adjacent bottom blades may be 10° or more and less than 180°, and at least one of the angles between adjacent bottom blades may be different from the remaining angles. For example, as in the modified example shown in Figs. 7A to 7C, when the number of bottom blades is 3 to 5, one angle (θ20, θ22, θ24) among the multiple angles between adjacent bottom blades 13 (angles θ20 to θ21 when the number of bottom blades is 3, angles θ22 to θ23 when the number of bottom blades is 4, and angles θ24 to θ25 when the number of bottom blades is 5) may be different from the remaining angles (θ21, θ23, θ25). The same symbol indicates the same angle, and different symbols indicate angles different from the other symbols.

[0054] Also, as in the modified example shown in FIG. 8A, when there are three bottom blades 13, the three angles θ26-θ28 formed by adjacent bottom blades 13 may be configured to include three different angles θ26-θ28. That is, in FIG. 8A, the adjacent angles θ26-θ28 are configured to be different. Furthermore, as in the modified example shown in FIG. 8B, when there are five bottom blades 13, the five angles θ29-θ31 formed by adjacent bottom blades 13 may be configured to include three different angles θ29-θ31. In addition, in FIG. 8B, the adjacent angles θ29-θ31 are configured to be different. Note that the same reference numerals indicate the same angles, and different reference numerals indicate angles different from the other reference numerals.

[0055] In this way, in each of the configurations in which the number of bottom blades is changed or the angle between adjacent bottom blades is different, as described above, when the workpiece W is cut with the dental end mill 10, the period in which the workpiece W and the multiple bottom blades 13 come into contact is shifted, thereby suppressing vibrations (chatter vibrations) during cutting more than when the workpiece W and the multiple bottom blades 13 come into contact periodically.

[0056] In addition, the following will be further disclosed in relation to the above-described embodiment. (1) A dental end mill for machining a workpiece, comprising: The dental processing device includes a shank portion that is held by the dental processing device, and a neck portion that is connected to the shank portion. The neck portion has a plurality of end cutting edges formed on a tip side not connected to the shank portion, and a plurality of peripheral cutting edges formed in a spiral shape at predetermined intervals on an outer peripheral surface on the tip side, The plurality of bottom cutting edges are arranged such that the intervals between adjacent bottom cutting edges are unequal, Among the plurality of peripheral blades, at least two of the peripheral blades are formed with different inclination angles. Dental end mill. (2) The dental end mill according to (1), The surface of the neck portion is free of organic components; Dental end mill. (3) The dental end mill according to (1) or (2), The number of end blades is 3 or more and 5 or less, The angle between the adjacent end cutting edges is 10° or more and less than 180°, At least one of the angles between the adjacent end cutting edges is different from the remaining angles. Dental end mill. (4) The dental end mill according to (3), The number of end blades is four, Among the four angles formed by the adjacent end cutting edges, adjacent angles are different and opposing angles are the same. Dental end mill. (5) The dental end mill according to (3), The number of end blades is three or five, Among the three or five angles formed by the adjacent end cutting edges, three different angles are included, and adjacent angles are different. Dental end mill. (6) The dental end mill according to any one of (1) to (5), The inclination angle is an acute angle among the angles at which each of the at least two peripheral cutting edges intersects with the center line of the dental end mill in the longitudinal direction, and is 20° or more and 60° or less. Dental end mill. (7) The dental end mill according to any one of (1) to (6), The combined length of the shank portion and the neck portion is 30.0 mm or more and 100.0 mm or less, The length of the neck portion is 1.0 mm or more and 30.0 mm or less, The diameter of the neck portion is 0.1 mm or more and 6.0 mm or less, The diameter of the shank portion is 2.0 mm or more and 10.0 mm or less. Dental end mill. (8) The dental end mill according to any one of (1) to (7), The neck portion is formed using at least one material selected from the group consisting of polycrystalline diamond, cermet, which is a composite material of ceramics and metal, cemented carbide, ultra-high pressure sintered body, and high-speed tool steel. Dental end mill. (9) The dental processing device includes the dental end mill according to any one of (1) to (8). [Explanation of symbols]

[0057] 1: Dental processing equipment θ11, θ13: Inclination angle (angle) 10: Dental end mill Cl: Center line 11: Shank D1: Diameter of the underside of the neck 12: Neck diameter D2: Shank diameter 12a: Surface of the neck L1: Length of the dental end mill 13, 13A~D: Bottom blade L2: Length of neck θ1~θ4: Angle between adjacent end cutting edges W: Workpiece 16, 16A~B: Peripheral blade

Claims

1. A dental end mill for machining a workpiece, comprising: The dental processing device includes a shank portion that is held by the dental processing device, and a neck portion that is connected to the shank portion. The neck portion has a plurality of end cutting edges formed on a tip side not connected to the shank portion, and a plurality of peripheral cutting edges formed in a spiral shape at predetermined intervals on an outer peripheral surface on the tip side, The plurality of bottom cutting edges are arranged such that the intervals between adjacent bottom cutting edges are unequal, Among the plurality of peripheral blades, at least two of the peripheral blades are formed with different inclination angles. Dental end mill.

2. 2. The dental end mill according to claim 1, The surface of the neck portion is free of organic components; Dental end mill.

3. 2. The dental end mill according to claim 1, The number of end blades is 3 or more and 5 or less, The angle between the adjacent end cutting edges is equal to or greater than 10° and less than 180°, At least one of the angles formed by the adjacent end cutting edges is different from the remaining angles. Dental end mill.

4. 4. The dental end mill according to claim 3, The number of end blades is four, Among the four angles formed by the adjacent end cutting edges, adjacent angles are different and opposing angles are the same. Dental end mill.

5. 4. The dental end mill according to claim 3, The number of end blades is three or five, Among the three or five angles formed by the adjacent end cutting edges, three different angles are included, and adjacent angles are different. Dental end mill.

6. 2. The dental end mill according to claim 1, The inclination angle is an acute angle among the angles at which each of the at least two peripheral cutting edges intersects with a center line in the longitudinal direction of the dental end mill, and is 20° or more and 60° or less. Dental end mill.

7. 2. The dental end mill according to claim 1, The combined length of the shank portion and the neck portion is 30.0 mm or more and 100.0 mm or less, The length of the neck portion is 1.0 mm or more and 30.0 mm or less, The diameter of the neck portion is 0.1 mm or more and 6.0 mm or less, The diameter of the shank portion is 2.0 mm or more and 10.0 mm or less. Dental end mill.

8. 2. The dental end mill according to claim 1, The neck portion is formed using at least one material selected from the group consisting of polycrystalline diamond, cermet, which is a composite material of ceramics and metal, cemented carbide, ultra-high pressure sintered body, and high-speed tool steel. Dental end mill.

9. The dental end mill according to any one of claims 1 to 8 is provided. The dental processing apparatus.

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