US20010002559A1 - Cutting tool and method for producing the same - Google Patents
Cutting tool and method for producing the same Download PDFInfo
- Publication number
- US20010002559A1 US20010002559A1 US09/774,050 US77405001A US2001002559A1 US 20010002559 A1 US20010002559 A1 US 20010002559A1 US 77405001 A US77405001 A US 77405001A US 2001002559 A1 US2001002559 A1 US 2001002559A1
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- US
- United States
- Prior art keywords
- drill
- hole
- shank portion
- cutting tool
- shank
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23B—TURNING; BORING
- B23B31/00—Chucks; Expansion mandrels; Adaptations thereof for remote control
- B23B31/005—Cylindrical shanks of tools
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23B—TURNING; BORING
- B23B51/00—Tools for drilling machines
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23B—TURNING; BORING
- B23B51/00—Tools for drilling machines
- B23B51/02—Twist drills
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
- B23P15/28—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass cutting tools
- B23P15/32—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass cutting tools twist-drills
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23B—TURNING; BORING
- B23B2231/00—Details of chucks, toolholder shanks or tool shanks
- B23B2231/02—Features of shanks of tools not relating to the operation performed by the tool
- B23B2231/0204—Connection of shanks to working elements of tools
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23B—TURNING; BORING
- B23B2240/00—Details of connections of tools or workpieces
- B23B2240/28—Shrink-fitted connections, i.e. using heating and cooling to produce interference fits
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23B—TURNING; BORING
- B23B2251/00—Details of tools for drilling machines
- B23B2251/02—Connections between shanks and removable cutting heads
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23B—TURNING; BORING
- B23B51/00—Tools for drilling machines
- B23B51/011—Micro drills
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49826—Assembling or joining
- Y10T29/49833—Punching, piercing or reaming part by surface of second part
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49826—Assembling or joining
- Y10T29/49945—Assembling or joining by driven force fit
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T403/00—Joints and connections
- Y10T403/49—Member deformed in situ
- Y10T403/4949—Deforming component is inserted section
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T403/00—Joints and connections
- Y10T403/49—Member deformed in situ
- Y10T403/4966—Deformation occurs simultaneously with assembly
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T408/00—Cutting by use of rotating axially moving tool
- Y10T408/89—Tool or Tool with support
- Y10T408/907—Tool or Tool with support including detailed shank
Definitions
- the present invention relates to composite-type cutting tools, whose drill portion and shank portion are made of different materials, and a method for producing such tools, for example, miniature drills used for making small-diameter holes in a printed circuit board.
- miniature drills are used for making holes having extremely small-diameters.
- miniature drills have: a cylindrical drill portion having a diameter of approximately 0.1 to 3.175 mm at the tip end of the drill body; and a larger-diameter shank portion at the rear end, which is used for holding the drill body in the axis of rotation of the machine tools.
- the drill portion is formed from a cemented carbide.
- the drill portion and the shank portion are integrally formed, for example, by grinding a cylindrical cemented carbide. Since such a cemented carbide is expensive and a large amount of the cemented carbide is ground for forming the drill portion, the cost inevitably increases.
- composite drills which are produced as follows: a small-diameter drill portion is formed from a substantially cylindrical cemented carbide; a large-diameter shank portion is made from a low-cost material, such as steel or SUS, different from the material used for the drill portion; and the rear of the drill portion is allowed to fit into a hole made in the tip end of the shank portion.
- FIGS. 12 (A) to 12 (E) show a method for producing such a conventional composite drill.
- a shank portion 1 shown in FIG. 12(A) has a tapered portion 1 a at the tip end and a hole 1 b made in the end face of the tapered portion 1 a.
- a substantially cylindrical drill portion 2 is pressed into the hole 1 b while enlarging the diameter of the hole 1 b by high-frequency heating (see FIG. 12(B)). Since the outer diameter of the drill portion 2 is set to be slightly larger than the inner diameter of the hole 1 b , the inner wall of the hole 1 b is shaved to produce chips by the insertion. The chips are pushed into the bottom of the hole 1 b by the drill portion 2 . The diameter of the hole 1 b is then shrunk by cooling to achieve a tight fit.
- the drill portion 2 can also be fitted to the hole 1 b by brazing as follows: the drill portion 2 is pressed into the hole 1 b having an inner diameter slightly larger than the outer diameter of the drill portion 2 , and then, brazed.
- Both sides of a joint 3 shown in FIG. 12(C), formed between the tapered portion 1 a of the shank portion 1 and the drill portion 2 are finely ground to form a tapered face 3 a having a smooth linear taper from the shank portion 1 to the drill 2 (see FIG. 12(D)), and the tip end of the drill portion 2 in succession to the tapered face 3 a is ground to form a drill edge 2 a (see FIGS. 12 (D) and 12 (E)).
- the drill portion 2 heated by high frequency heating is undesirably deformed when it is pressed into the hole 1 b .
- the fastening strength due to fitting is also lowered by shaving the inner wall of the hole 1 b .
- the length of the drill portion 2 exposed outside the shank portion 1 varies with the amount of the shaved chips, it is necessary to adjust the length of the shank portion 1 to achieve a constant total length of the miniature drills.
- the inner wall of the hole 1 b is readily corroded by the flux at the time of brazing.
- shank portion 1 and the drill portion 2 are made of different materials, it is difficult to simultaneously grind both of them into the linearly tapered face 3 a over both sides of the joint 3 between the shank portion 1 and the drill portion 2 .
- an object of the present invention is to provide a method for producing a cutting tool, by which method the drill portion is not deformed by fitting to the shank portion, and a cutting tool that can be easily produced having a high fastening strength.
- Another object of the present invention is to provide a cutting tool whose drill portion and shank portion are joined by a joint having high fastening strength and which can be easily produced.
- a method for producing a cutting tool incorporated in the present invention is characterized in that where a cutting tool prepared by fitting a drill portion into a hole of a shank portion, the inner diameter of the hole of the shank portion is formed slightly smaller than the outer diameter of the drill portion, and the rear of the drill portion is pressed into the hole of the shank portion at normal temperature which is room temperature.
- the drill portion By forcibly pressing the drill portion into the hole of the shank portion at normal temperature, the drill portion shaves the inner wall of the hole while enlarging the hole, and is tightly fitted into the hole. Since the joint is achieved without brazing, the number of steps is low and the procedure is simplified, and furthermore, the drill portion, which is to be used for cutting, is not deformed because the procedure is carried out at normal temperature which is room temperature.
- the drill edge of the drill portion is formed by grinding after pressing the drill portion into the shank portion.
- the drill portion is required to be ground to form the drill edge, resulting in easier grinding.
- the shank portion is quenched before fitting. Therefore, the hardness of the resulting shank portion increases, and a cutting tool having a high joint strength can be formed with high accuracy because the inner diameter of the hole is enlarged by pressing the drill portion into the hole of the shank portion without being readily shaved. Thus, the shank portion is not damaged by shaved chips produced by processing. Furthermore, a less deformed shank portion having a smooth surface can be achieved by quenching under vacuum. Moreover, if the surface of the shank portion is hardened by nitriding before fitting, the shank portion becomes harder, the joint strength with the drill portion increases, and deformation does not occur because heat treatment such as quenching is not required.
- the rear of the drill portion has a rounded or linearly chamfered edge, or the like.
- the chamfered edge presses and enlarges the inner diameter of the hole without shaving the inner wall, resulting in a reliable fastening fit. If the rear of the drill portion has a sharp edge, the inner wall of the hole is shaved by pressing the drill portion into the hole.
- a cutting tool incorporated into the present invention is characterized in that a small-diameter drill portion is fitted to a hole of a large-diameter shank portion, a step is formed at the joint between the shank portion and the drill portion, and the drill portion is formed into a drill edge.
- the diameter of the shank portion is larger than that of the drill portion by the height of the step formed at the joint between the shank portion and the drill portion. Therefore, the strength of the cutting tool increases and the tool life is extended. Additionally, it is not necessary to grind the joint into a tapered shape over the shank portion and the drill portion. Thus, the grinding step becomes simpler, resulting in simplified production.
- FIG. 1 is a cross-sectional diagram showing a drill portion and a shank portion of a composite drill incorporated in the first embodiment of the present invention before fitting;
- FIG. 2 is a cross-sectional diagram showing the drill portion and the shank portion of the composite drill incorporated in the first embodiment of the present invention during fitting;
- FIG. 3 is a cross-sectional diagram showing the drill portion and the shank portion of the composite drill incorporated in the first embodiment of the present invention after fitting;
- FIG. 4 is a diagram showing the rear edge of a drill portion incorporated in a modification
- FIG. 5 is a diagram showing the rear edge of a drill portion incorporated in another modification
- FIG. 6 is a side view showing a miniature drill incorporated in the second embodiment of the present invention.
- FIGS. 7 (A) to (D) show production steps of the miniature drill shown in FIG. 6,
- FIG. 7(A) is a side view of a shank portion
- FIG. 7(B) is a diagram showing a drill portion and the shank portion before inserting the drill portion into the shank portion
- FIG. 7(C) is a diagram showing the drill portion and the shank portion after the insertion
- FIG. 7(D) is a diagram showing a tapered portion of the drill portion and a drill edge both formed by grinding;
- FIG. 8 is a cross-sectional diagram showing a drill portion and a shank portion of a composite drill incorporated in the third embodiment before inserting the drill portion into the shank portion;
- FIG. 9 is a cross-sectional diagram showing the drill portion and the shank portion of a composite drill incorporated in the third embodiment during insertion;
- FIG. 10 is a cross-sectional diagram showing the drill portion and the shank portion of a composite drill incorporated in the third embodiment after the insertion;
- FIG. 11 is a side view of a cylinder of material before being machined into a shank portion
- FIGS. 12 (A) to 12 (E) show production steps of a conventional miniature drill
- FIG. 12(A) is a side view of a shank portion
- FIG. 12(B) is a diagram showing a drill portion and the shank portion before inserting the drill portion into the shank portion
- FIG. 12(C) is a diagram showing the drill portion and the shank portion after the insertion
- FIG. 12(D) is a diagram showing a tapered portion of the shank portion and a drill portion both formed by simultaneously grinding
- FIG. (E) is a side view of the miniature drill provided with a twist through flute.
- a miniature drill 10 shown in FIG. 1 is formed from a substantially cylindrical drill portion 11 which has a diameter of approximately 0.1 to 3.175 mm and which is made of cemented carbide and a substantially cylindrical shank portion 12 which has a larger diameter (e.g., 3 to 6 mm as the outer diameter) and which is made of SUS, steel, or the like.
- a rear edge 11 b of a rear 11 a of the drill portion 11 has a sharp square edge (e.g., not more than 90°) which is not chamfered.
- the shank portion 12 has a substantially cylindrical hole 13 coaxially formed from the tip end face 12 a along the longitudinal axis of the shank portion 12 .
- the inner diameter of the hole 13 is, for example, 1.4 mm, and is smaller than the outer diameter of the drill portion 11 by a small amount (e.g., by 10 ⁇ m).
- the difference between the inner diameter of the hole 13 and the outer diameter of the drill portion 11 alters according to the size of the drill portion 11 and the shank portion 12 , for example, the difference is set above 0 and not more than 100 ⁇ m. If the difference is larger than 100 ⁇ m, the force fitting becomes difficult. Preferably, the difference is not more than 50 ⁇ m, and more preferably, not more than 20 ⁇ m.
- the opening of the hole 13 of the shank portion 12 is not chamfered, and the outer edge of the tip end face 12 a is chamfered leaving the shoulder 12 b .
- the depth of the hole 13 is set to be slightly longer than the length of the rear 11 a of the drill portion 11 to be fitted into the hole 13 .
- the inner wall 13 a of the hole 13 is gradually narrowed near the bottom of the hole 13 so that a space 13 b is formed for storing chips when the rear 11 a of the drill portion 11 is fitted (see FIG. 3).
- This embodiment has the above-described structure. A method for assembling the miniature drill 10 will be explained below.
- the rear 11 a of the drill portion 11 is coaxially put onto the hole 13 made in the tip end face 12 a of the shank portion 12 and pressed into the hole 13 with high strength or force (FIG. 1).
- the diameter of the inner wall 13 a of the hole 13 is enlarged and shaved, little by little, by the rear edge 11 b of the drill portion 11 , and the rear 11 a of the drill portion 11 is pressed into the hole 13 (see FIG. 2).
- the shaved chips are gradually pushed to the bottom of the hole 13 .
- the fitting between the drill portion 11 and the shank portion 12 is completed when the rear 11 a of the drill portion 11 is pushed into the bottom of the hole 13 with the chips shaved from the inner wall 13 a being stored in the space 13 b formed in the bottom of the hole 13 .
- the drill portion 11 may then be ground to a more slender shape, as is shown by the single dot chain line in FIG. 3.
- the drill portion 11 can be tightly fitted to the shank portion 12 at normal temperature, which is room temperature, without brazing or shrinkage fitting.
- normal temperature which is room temperature
- highly accurate miniature drills can be readily produced since the drill portion 11 and the shank portion 12 are not deformed by heat.
- the rear edge 11 b is sharp, the drill portion 11 can be easily produced at low cost, and the inner wall 13 a of the hole 13 is shaved by the rear edge 11 b when the drill portion 11 is pressed into the hole 13 .
- the rear edge 11 b is not always required to be sharp.
- the rear edge 11 b may be chamfered in a circular arc (R ⁇ 0.1 mm), as is shown in FIG. 4.
- the drill portion 11 can be more readily pressed into the hole 13 , and also, more easily produced by barrel finishing or the like.
- the rear edge 11 b may be linearly chamfered (C ⁇ 0.1 mm), as is shown in FIG. 5.
- the processing costs for such chamfered shapes are higher than those for other shapes, the drill portion 11 can be fitted to the hole 13 while enlarging the diameter of the inner wall of the hole 13 without producing shaved chips from the inner wall if the rear edge 11 b is chamfered. Therefore, the length of the miniature drill 10 can be made a certain value by setting the lengths of the drill portion 11 and the shank portion 12 , resulting in a reliable joint between the drill portion 11 and the shank portion 12 by fitting, and easier insertion.
- FIGS. 6 and 7(A) to 7 (D) show the second embodiment of the present invention.
- a miniature drill 20 shown in FIG. 6 has a substantially cylindrical drill portion 21 having a small diameter and a substantially cylindrical shank portion 22 having a larger diameter.
- the diameter of the tip side of the shank portion 22 is gradually reduced to form a conically tapered portion 22 a , and the tip end face of the tapered portion 22 a has a circular planar shoulder 22 b .
- the diameter of the shoulder portion 22 b is larger than the outer diameter of the drill portion 21 , and a hole 13 is made from the shoulder 22 b towards the inside of the shank portion 22 , coaxially with the shank portion 22 .
- the drill portion 21 has: a substantially cylindrical stem 21 a having a relatively large diameter; a cylindrical drill edge 21 c having a smaller diameter; and a tapered portion 21 b formed between the stem 21 a and the drill edge 21 c such that the diameter of the tapered portion 21 b is gradually decreased from the stem 21 a to the drill edge 21 c .
- the rear of the stem 21 a is pressed into the hole 13 of the shank portion 22 to fit the drill portion 21 to the shank portion 22 .
- the drill edge 21 c has: a twist through flute 24 ; and a cutting edge 25 , which is the cross ridge line made by a wall of the twist through flute 24 facing the rotating direction and the tip end face of the drill edge 21 c.
- a step 26 having a shoulder 22 b is formed between the tapered portion 22 a of the shank portion 22 and the stem 21 a of the drill portion 21 , and at the tip side of the drill portion 21 , a certain distance from the step 26 , the tapered portion 21 b and the drill edge 21 c are continuously formed.
- the miniature drill 20 of the second embodiment has the above structure. A method for producing the miniature drill 20 will be explained with reference to FIGS. 7 (A) to 7 (D).
- the shank portion 22 has the same shape as that shown in FIG. 6, the drill portion 21 to be fitted to the shank portion 22 is formed in a substantially cylindrical shape having the same outer diameter as that of the stem 21 a shown in FIG. 6, and the rear end of the drill portion 21 is chamfered with a taper into a chamfered portion C.
- the minimum diameter of the chamfered portion C is smaller than the inner diameter of the hole 13 of the shank portion 22
- the maximum diameter of the chamfered portion C is the same as the stem 21 a which is slightly larger than the inner diameter of the hole 13 .
- the inner diameter of the hole 13 of the shank portion 22 is, for example, approximately 1.4 mm, and is set to be smaller than the outer diameter of the drill portion 21 (the stem 21 a ), except for the chamfered portion C, by a slight value (e.g. 10 ⁇ m).
- the chamfered portion C of the rear end of the drill portion 21 is coaxially pressed into the hole 13 of the shoulder 22 b of the shank portion 22 at normal temperature which is room temperature.
- the inner wall of the hole 13 is thereby pressed by the chamfered portion C of the drill portion 21 and its diameter is enlarged, little by little, to allow the rear of the drill portion 21 to be inserted into the hole 13 .
- the total length of the miniature drill 20 is determined by allowing the drill portion 21 to be inserted into the shank portion 22 until the length from the rear end of the shank portion 22 to the tip of the drill portion 21 reaches the predetermined value, and the fitting step of pressing the drill portion 21 into the shank portion 22 is completed (see FIG. 7(C)). As a result, a step 26 having a shoulder 22 b is formed between the tapered portion 22 a and the drill portion 21 at the joint between the shank portion 22 and the drill portion 21 .
- a portion of the drill portion 21 is then ground to form the tapered portion 21 b and the cylindrical drill edge 21 c having a small diameter.
- the drill edge 21 c is provided with the twist through flute 24 and the cutting edge 25 .
- the shank portion 22 has a step 26 due to the shoulder 22 b .
- the strength of the miniature drill 20 is higher than that of conventional miniature drills because of the height of the step 26 , resulting in longer tool life.
- the tapered portion 21 b of the drill portion 21 is formed in a portion at a predetermined distance from the step 26 of the shank portion 22 in the second embodiment, the present invention is not restricted, and the tapered portion 21 b may be formed continuously from the step 26 (shoulder 22 b ). Furthermore, the shank portion 22 is not always required to have the tapered portion 22 a . In such a case, the step 26 is determined by the difference between the outer diameter of the shank portion 22 and the drill portion 21 .
- a miniature drill 30 shown in FIG. 8 has: a substantially cylindrical drill portion 31 having a diameter of approximately 0.1 to 3.175 mm; and a substantially cylindrical shank portion 32 having a larger diameter (e.g., 3 to 6 mm as the outer diameter).
- a rear edge 31 b of a rear 31 a of the drill portion 31 has a sharp square edge (e.g., not more than 90°) without being chamfered.
- the shank portion 32 has a substantially cylindrical hole 13 coaxially formed with the shank portion 32 from the tip end face 32 a along its longitudinal axis.
- the inner diameter of the hole 13 is set to 1.4 mm, which is smaller than the outer diameter of the drill portion 31 by a small amount (e.g., by 10 ⁇ m).
- the shank portion 32 is prepared as follows: a cylinder of material of approximately 35 to 50 HRC is obtained by vacuum quenching (prism-shaped materials or the like may be used instead); and is machined such that the opening of the hole 13 is not chamfered and the outer edge of the tip end face 32 a is chamfered leaving a shoulder 32 b .
- the depth of the hole 13 is set to be slightly longer than the rear 31 a to be pressed into the hole 13 of the drill portion 31 . Near the bottom of the hole 13 , the inner diameter of the hole 13 is gradually decreased to form a space 13 b for storing shaved chips when the rear 31 a of the drill portion 31 is fitted (see FIG. 10).
- This embodiment has the above-described structure. A method for assembling the miniature drill 30 will be explained below.
- a cylinder of material 40 shown in FIG. 11 to be formed into the shank portion 32 is vacuum quenched so as to achieve approximately 35 to 50 HRC, which is higher than that obtained without quenching (approximately 24 HRC).
- HRC high-density carbonate
- a smoother surface can be obtained with less deteriorated accuracy in size by quenching under vacuum because of less deformation and no oxidation. Therefore, the polishing step for surface treatment after quenching becomes unnecessary or simplified.
- the rear 31 a of the drill portion 31 is then inserted into the hole 13 with high strength or force at normal temperature which is room temperature.
- the diameter of the inner wall 33 a of the hole 13 is enlarged by the rear edge 31 b of the drill portion 31 , and the rear 31 a of the drill portion 31 is pressed into the hole 13 (see FIGS. 8 and 9).
- the inner wall 33 a of the hole 13 is disadvantageously damaged by being shaved or the shank portion 32 may be damaged by cutting chips while using the miniature drill 30 for cutting.
- the rear 31 a of the drill portion 31 is pressed into the bottom of the hole 13 with a small amount of chips shaved from the inner wall 33 a being stored in the space 13 b formed in the bottom of the hole 13 .
- the drill portion 31 may then be ground to a more slender shape, as is shown by the single dot chain line in FIG. 10.
- the shank portion 32 is hardened beforehand by vacuum quenching.
- the drill portion 31 has a smoother surface and is not deformed by heat, resulting in a highly accurate miniature drill.
- the shank portion 32 is not damaged by cutting chips while using the miniature drill 30 for cutting.
- the shank portion 32 may be vacuum quenched after being machined. In such a case, the forming accuracy of the resulting shank portion 32 deteriorates to some extent, and surface treatment is required; also quenching under a normal atmosphere may be employed instead of vacuum quenching.
- Nitriding can also be employed instead of quenching.
- the shank portion is heated at approximately 500°C. for 18 to 19 hours in a gaseous ammonium atmosphere, and then, allowed to stand for cooling. The surface of the shank portion 32 is thereby hardened. Furthermore, deformation does not occur because heat treatment such as quenching is unnecessary.
- the materials used for the drill portions 11 , 21 , and 31 are not limited to cemented carbide, and other suitable materials such as cermet can be employed as long as they are harder than the shank portions.
- the materials used for the shank portions 12 , 22 , and 32 are not restricted to SUS and steel, and other materials such as aluminum alloys may be used.
- the hole 13 of the shank portions 12 , 22 , and 32 and the rear 11 a , 21 a , and 31 a of the drill portions 11 , 21 , and 31 , respectively, are not limited to cylindrical shapes, and may be prismatic shapes.
- the present invention can be applied not only to miniature drills but also to other cutting tools such as drilling tools, small-diameter end mills, and the like.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Drilling Tools (AREA)
Abstract
A method for producing cutting tools incorporated in the present invention is carried out as follows: a shank portion and a drill portion are formed separately such that the inner diameter of a hole made in the shank portion is slightly smaller than the outer diameter of the drill portion. The rear of the drill portion is forcibly inserted into the hole of the shank portion at normal temperature which is room temperature. The diameter of the inner wall of the hole is thereby enlarged, resulting in a tight fitting. After the insertion of the drill portion in the shank portion, the drill portion may be ground to form a drill edge. Before the insertion of the drill portion in the shank portion, the shank portion may be quenched under vacuum or the like, or the surface of the shank portion may be hardened by nitriding.
Description
- 1. Field of the Invention
- The present invention relates to composite-type cutting tools, whose drill portion and shank portion are made of different materials, and a method for producing such tools, for example, miniature drills used for making small-diameter holes in a printed circuit board.
- This application claims priority of Japanese Patent Application Nos. 9-19485, 9-161393, and 9-208101 which are hereby incorporated by reference.
- 2. Discussion of the Background
- Generally, miniature drills are used for making holes having extremely small-diameters. Thus, miniature drills have: a cylindrical drill portion having a diameter of approximately 0.1 to 3.175 mm at the tip end of the drill body; and a larger-diameter shank portion at the rear end, which is used for holding the drill body in the axis of rotation of the machine tools. In general, the drill portion is formed from a cemented carbide.
- Thus, to produce a solid-type miniature drill, the drill portion and the shank portion are integrally formed, for example, by grinding a cylindrical cemented carbide. Since such a cemented carbide is expensive and a large amount of the cemented carbide is ground for forming the drill portion, the cost inevitably increases.
- Meanwhile, composite drills have been suggested which are produced as follows: a small-diameter drill portion is formed from a substantially cylindrical cemented carbide; a large-diameter shank portion is made from a low-cost material, such as steel or SUS, different from the material used for the drill portion; and the rear of the drill portion is allowed to fit into a hole made in the tip end of the shank portion.
- FIGS.12(A) to 12(E) show a method for producing such a conventional composite drill.
- A
shank portion 1 shown in FIG. 12(A) has a tapered portion 1 a at the tip end and a hole 1 b made in the end face of the tapered portion 1 a. - According to shrinkage fitting, a substantially
cylindrical drill portion 2 is pressed into the hole 1 b while enlarging the diameter of the hole 1 b by high-frequency heating (see FIG. 12(B)). Since the outer diameter of thedrill portion 2 is set to be slightly larger than the inner diameter of the hole 1 b, the inner wall of the hole 1 b is shaved to produce chips by the insertion. The chips are pushed into the bottom of the hole 1 b by thedrill portion 2. The diameter of the hole 1 b is then shrunk by cooling to achieve a tight fit. - The
drill portion 2 can also be fitted to the hole 1 b by brazing as follows: thedrill portion 2 is pressed into the hole 1 b having an inner diameter slightly larger than the outer diameter of thedrill portion 2, and then, brazed. - Both sides of a
joint 3, shown in FIG. 12(C), formed between the tapered portion 1 a of theshank portion 1 and thedrill portion 2 are finely ground to form a tapered face 3 a having a smooth linear taper from theshank portion 1 to the drill 2 (see FIG. 12(D)), and the tip end of thedrill portion 2 in succession to the tapered face 3 a is ground to form a drill edge 2 a (see FIGS. 12(D) and 12(E)). - However, since such methods for producing composite drills need a large number of steps, the process becomes complicated and laborious, disadvantageously increasing the cost. Furthermore, before pressing the
drill portion 2 into theshank portion 1, theshank portion 1 is annealed by high frequency heating in the case of shrinkage fitting and by a flux in the case of brazing. Thus, the hardness of theshank portion 1 decreases so that the fastening strength due to the fitting to thedrill portion 2 is disadvantageously reduced. - Furthermore, the
drill portion 2 heated by high frequency heating is undesirably deformed when it is pressed into the hole 1 b. The fastening strength due to fitting is also lowered by shaving the inner wall of the hole 1 b. Furthermore, since the length of thedrill portion 2 exposed outside theshank portion 1 varies with the amount of the shaved chips, it is necessary to adjust the length of theshank portion 1 to achieve a constant total length of the miniature drills. - Moreover, disadvantageously, the inner wall of the hole1 b is readily corroded by the flux at the time of brazing.
- In addition, since the
shank portion 1 and thedrill portion 2 are made of different materials, it is difficult to simultaneously grind both of them into the linearly tapered face 3 a over both sides of thejoint 3 between theshank portion 1 and thedrill portion 2. - Accordingly, an object of the present invention is to provide a method for producing a cutting tool, by which method the drill portion is not deformed by fitting to the shank portion, and a cutting tool that can be easily produced having a high fastening strength.
- Another object of the present invention is to provide a cutting tool whose drill portion and shank portion are joined by a joint having high fastening strength and which can be easily produced.
- To achieve the above objects, a method for producing a cutting tool incorporated in the present invention is characterized in that where a cutting tool prepared by fitting a drill portion into a hole of a shank portion, the inner diameter of the hole of the shank portion is formed slightly smaller than the outer diameter of the drill portion, and the rear of the drill portion is pressed into the hole of the shank portion at normal temperature which is room temperature.
- By forcibly pressing the drill portion into the hole of the shank portion at normal temperature, the drill portion shaves the inner wall of the hole while enlarging the hole, and is tightly fitted into the hole. Since the joint is achieved without brazing, the number of steps is low and the procedure is simplified, and furthermore, the drill portion, which is to be used for cutting, is not deformed because the procedure is carried out at normal temperature which is room temperature.
- Moreover, according to one preferred embodiment of the present invention, the drill edge of the drill portion is formed by grinding after pressing the drill portion into the shank portion. Thus, only the drill portion is required to be ground to form the drill edge, resulting in easier grinding.
- According to another preferred embodiment of the present invention, the shank portion is quenched before fitting. Therefore, the hardness of the resulting shank portion increases, and a cutting tool having a high joint strength can be formed with high accuracy because the inner diameter of the hole is enlarged by pressing the drill portion into the hole of the shank portion without being readily shaved. Thus, the shank portion is not damaged by shaved chips produced by processing. Furthermore, a less deformed shank portion having a smooth surface can be achieved by quenching under vacuum. Moreover, if the surface of the shank portion is hardened by nitriding before fitting, the shank portion becomes harder, the joint strength with the drill portion increases, and deformation does not occur because heat treatment such as quenching is not required.
- The rear of the drill portion has a rounded or linearly chamfered edge, or the like. Thus, when the drill portion is pressed into the hole, the chamfered edge presses and enlarges the inner diameter of the hole without shaving the inner wall, resulting in a reliable fastening fit. If the rear of the drill portion has a sharp edge, the inner wall of the hole is shaved by pressing the drill portion into the hole.
- A cutting tool incorporated into the present invention is characterized in that a small-diameter drill portion is fitted to a hole of a large-diameter shank portion, a step is formed at the joint between the shank portion and the drill portion, and the drill portion is formed into a drill edge.
- The diameter of the shank portion is larger than that of the drill portion by the height of the step formed at the joint between the shank portion and the drill portion. Therefore, the strength of the cutting tool increases and the tool life is extended. Additionally, it is not necessary to grind the joint into a tapered shape over the shank portion and the drill portion. Thus, the grinding step becomes simpler, resulting in simplified production.
- A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
- FIG. 1 is a cross-sectional diagram showing a drill portion and a shank portion of a composite drill incorporated in the first embodiment of the present invention before fitting;
- FIG. 2 is a cross-sectional diagram showing the drill portion and the shank portion of the composite drill incorporated in the first embodiment of the present invention during fitting;
- FIG. 3 is a cross-sectional diagram showing the drill portion and the shank portion of the composite drill incorporated in the first embodiment of the present invention after fitting;
- FIG. 4 is a diagram showing the rear edge of a drill portion incorporated in a modification;
- FIG. 5 is a diagram showing the rear edge of a drill portion incorporated in another modification;
- FIG. 6 is a side view showing a miniature drill incorporated in the second embodiment of the present invention;
- FIGS.7(A) to (D) show production steps of the miniature drill shown in FIG. 6, FIG. 7(A) is a side view of a shank portion, FIG. 7(B) is a diagram showing a drill portion and the shank portion before inserting the drill portion into the shank portion, FIG. 7(C) is a diagram showing the drill portion and the shank portion after the insertion, and FIG. 7(D) is a diagram showing a tapered portion of the drill portion and a drill edge both formed by grinding;
- FIG. 8 is a cross-sectional diagram showing a drill portion and a shank portion of a composite drill incorporated in the third embodiment before inserting the drill portion into the shank portion;
- FIG. 9 is a cross-sectional diagram showing the drill portion and the shank portion of a composite drill incorporated in the third embodiment during insertion;
- FIG. 10 is a cross-sectional diagram showing the drill portion and the shank portion of a composite drill incorporated in the third embodiment after the insertion;
- FIG. 11 is a side view of a cylinder of material before being machined into a shank portion; and
- FIGS.12(A) to 12(E) show production steps of a conventional miniature drill, FIG. 12(A) is a side view of a shank portion, FIG. 12(B) is a diagram showing a drill portion and the shank portion before inserting the drill portion into the shank portion, FIG. 12(C) is a diagram showing the drill portion and the shank portion after the insertion, FIG. 12(D) is a diagram showing a tapered portion of the shank portion and a drill portion both formed by simultaneously grinding, and FIG. (E) is a side view of the miniature drill provided with a twist through flute.
- Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to FIGS. 1 through 3 thereof which show the first embodiment of the present invention. For example, a
miniature drill 10 shown in FIG. 1 is formed from a substantially cylindrical drill portion 11 which has a diameter of approximately 0.1 to 3.175 mm and which is made of cemented carbide and a substantiallycylindrical shank portion 12 which has a larger diameter (e.g., 3 to 6 mm as the outer diameter) and which is made of SUS, steel, or the like. - A rear edge11 b of a rear 11 a of the drill portion 11 has a sharp square edge (e.g., not more than 90°) which is not chamfered. The
shank portion 12 has a substantiallycylindrical hole 13 coaxially formed from the tip end face 12 a along the longitudinal axis of theshank portion 12. The inner diameter of thehole 13 is, for example, 1.4 mm, and is smaller than the outer diameter of the drill portion 11 by a small amount (e.g., by 10 μm). - Although the difference between the inner diameter of the
hole 13 and the outer diameter of the drill portion 11 alters according to the size of the drill portion 11 and theshank portion 12, for example, the difference is set above 0 and not more than 100 μm. If the difference is larger than 100 μm, the force fitting becomes difficult. Preferably, the difference is not more than 50 μm, and more preferably, not more than 20 μm. - The opening of the
hole 13 of theshank portion 12 is not chamfered, and the outer edge of the tip end face 12 a is chamfered leaving theshoulder 12 b. The depth of thehole 13 is set to be slightly longer than the length of the rear 11 a of the drill portion 11 to be fitted into thehole 13. Theinner wall 13 a of thehole 13 is gradually narrowed near the bottom of thehole 13 so that aspace 13 b is formed for storing chips when the rear 11 a of the drill portion 11 is fitted (see FIG. 3). - This embodiment has the above-described structure. A method for assembling the
miniature drill 10 will be explained below. - At normal temperature, which is room temperature, the rear11 a of the drill portion 11 is coaxially put onto the
hole 13 made in the tip end face 12 a of theshank portion 12 and pressed into thehole 13 with high strength or force (FIG. 1). As a result, the diameter of theinner wall 13 a of thehole 13 is enlarged and shaved, little by little, by the rear edge 11 b of the drill portion 11, and the rear 11 a of the drill portion 11 is pressed into the hole 13 (see FIG. 2). The shaved chips are gradually pushed to the bottom of thehole 13. - As is shown in FIG. 3, the fitting between the drill portion11 and the
shank portion 12 is completed when the rear 11 a of the drill portion 11 is pushed into the bottom of thehole 13 with the chips shaved from theinner wall 13 a being stored in thespace 13 b formed in the bottom of thehole 13. - The drill portion11 may then be ground to a more slender shape, as is shown by the single dot chain line in FIG. 3.
- As is mentioned above, according to the first embodiment, the drill portion11 can be tightly fitted to the
shank portion 12 at normal temperature, which is room temperature, without brazing or shrinkage fitting. Thus, low-cost production is achieved by a small number of steps, and highly accurate miniature drills can be readily produced since the drill portion 11 and theshank portion 12 are not deformed by heat. Since the rear edge 11 b is sharp, the drill portion 11 can be easily produced at low cost, and theinner wall 13 a of thehole 13 is shaved by the rear edge 11 b when the drill portion 11 is pressed into thehole 13. - The rear edge11 b is not always required to be sharp. For example, the rear edge 11 b may be chamfered in a circular arc (R≧0.1 mm), as is shown in FIG. 4. In such a case, the drill portion 11 can be more readily pressed into the
hole 13, and also, more easily produced by barrel finishing or the like. Furthermore, the rear edge 11 b may be linearly chamfered (C≧0.1 mm), as is shown in FIG. 5. Although the processing costs for such chamfered shapes are higher than those for other shapes, the drill portion 11 can be fitted to thehole 13 while enlarging the diameter of the inner wall of thehole 13 without producing shaved chips from the inner wall if the rear edge 11 b is chamfered. Therefore, the length of theminiature drill 10 can be made a certain value by setting the lengths of the drill portion 11 and theshank portion 12, resulting in a reliable joint between the drill portion 11 and theshank portion 12 by fitting, and easier insertion. - Other embodiments of the present invention will be described below. The numerals in the different views identify substantially identical parts in the first embodiment, and detailed explanations thereof are omitted.
- FIGS. 6 and 7(A) to7(D) show the second embodiment of the present invention.
- A
miniature drill 20 shown in FIG. 6 has a substantiallycylindrical drill portion 21 having a small diameter and a substantiallycylindrical shank portion 22 having a larger diameter. - The diameter of the tip side of the
shank portion 22 is gradually reduced to form a conically tapered portion 22 a, and the tip end face of the tapered portion 22 a has a circular planar shoulder 22 b. The diameter of the shoulder portion 22 b is larger than the outer diameter of thedrill portion 21, and ahole 13 is made from the shoulder 22 b towards the inside of theshank portion 22, coaxially with theshank portion 22. - The
drill portion 21 has: a substantially cylindrical stem 21 a having a relatively large diameter; acylindrical drill edge 21 c having a smaller diameter; and a taperedportion 21 b formed between the stem 21 a and thedrill edge 21 c such that the diameter of the taperedportion 21 b is gradually decreased from the stem 21 a to thedrill edge 21 c. The rear of the stem 21 a is pressed into thehole 13 of theshank portion 22 to fit thedrill portion 21 to theshank portion 22. For example, thedrill edge 21 c has: a twist through flute 24; and a cutting edge 25, which is the cross ridge line made by a wall of the twist through flute 24 facing the rotating direction and the tip end face of thedrill edge 21 c. - As a result, a
step 26 having a shoulder 22 b is formed between the tapered portion 22 a of theshank portion 22 and the stem 21 a of thedrill portion 21, and at the tip side of thedrill portion 21, a certain distance from thestep 26, the taperedportion 21 b and thedrill edge 21 c are continuously formed. - The
miniature drill 20 of the second embodiment has the above structure. A method for producing theminiature drill 20 will be explained with reference to FIGS. 7(A) to 7(D). - In FIGS.7(A) to 7(D), the
shank portion 22 has the same shape as that shown in FIG. 6, thedrill portion 21 to be fitted to theshank portion 22 is formed in a substantially cylindrical shape having the same outer diameter as that of the stem 21 a shown in FIG. 6, and the rear end of thedrill portion 21 is chamfered with a taper into a chamfered portion C. The minimum diameter of the chamfered portion C is smaller than the inner diameter of thehole 13 of theshank portion 22, and the maximum diameter of the chamfered portion C is the same as the stem 21 a which is slightly larger than the inner diameter of thehole 13. - The inner diameter of the
hole 13 of theshank portion 22 is, for example, approximately 1.4 mm, and is set to be smaller than the outer diameter of the drill portion 21 (the stem 21 a), except for the chamfered portion C, by a slight value (e.g. 10 μm). - For producing the
miniature drill 20, the chamfered portion C of the rear end of thedrill portion 21 is coaxially pressed into thehole 13 of the shoulder 22 b of theshank portion 22 at normal temperature which is room temperature. The inner wall of thehole 13 is thereby pressed by the chamfered portion C of thedrill portion 21 and its diameter is enlarged, little by little, to allow the rear of thedrill portion 21 to be inserted into thehole 13. - The total length of the
miniature drill 20 is determined by allowing thedrill portion 21 to be inserted into theshank portion 22 until the length from the rear end of theshank portion 22 to the tip of thedrill portion 21 reaches the predetermined value, and the fitting step of pressing thedrill portion 21 into theshank portion 22 is completed (see FIG. 7(C)). As a result, astep 26 having a shoulder 22 b is formed between the tapered portion 22 a and thedrill portion 21 at the joint between theshank portion 22 and thedrill portion 21. - A portion of the
drill portion 21, at a predetermined distance from the shoulder 22 b, is then ground to form the taperedportion 21 b and thecylindrical drill edge 21 c having a small diameter. Thedrill edge 21 c is provided with the twist through flute 24 and the cutting edge 25. - By the above procedure, the
miniature drill 20 shown in FIG. 6 is produced. - As is mentioned above, according to the
miniature drill 20 of the second embodiment, theshank portion 22 has astep 26 due to the shoulder 22 b. Thus, the strength of theminiature drill 20 is higher than that of conventional miniature drills because of the height of thestep 26, resulting in longer tool life. - Furthermore, according to a method for producing the
miniature drill 20 incorporated in the second embodiment of the present invention, in addition to the advantages due to the first embodiment, grinding can be carried out more readily and accurately because the tapered portion 22 a of theshank portion 22 and the taperedportion 21 b of thedrill portion 21 are not formed in a continuous linear shape and only the taperedportion 21 b of thedrill portion 21 is ground. - Although, the tapered
portion 21 b of thedrill portion 21 is formed in a portion at a predetermined distance from thestep 26 of theshank portion 22 in the second embodiment, the present invention is not restricted, and the taperedportion 21 b may be formed continuously from the step 26 (shoulder 22 b). Furthermore, theshank portion 22 is not always required to have the tapered portion 22 a. In such a case, thestep 26 is determined by the difference between the outer diameter of theshank portion 22 and thedrill portion 21. - The third embodiment of the present invention will be described with reference to FIGS.8 to 11.
- For example, a
miniature drill 30 shown in FIG. 8 has: a substantiallycylindrical drill portion 31 having a diameter of approximately 0.1 to 3.175 mm; and a substantiallycylindrical shank portion 32 having a larger diameter (e.g., 3 to 6 mm as the outer diameter). - A rear edge31 b of a rear 31 a of the
drill portion 31 has a sharp square edge (e.g., not more than 90°) without being chamfered. Theshank portion 32 has a substantiallycylindrical hole 13 coaxially formed with theshank portion 32 from the tip end face 32 a along its longitudinal axis. For example, the inner diameter of thehole 13 is set to 1.4 mm, which is smaller than the outer diameter of thedrill portion 31 by a small amount (e.g., by 10 μm). - The
shank portion 32 is prepared as follows: a cylinder of material of approximately 35 to 50 HRC is obtained by vacuum quenching (prism-shaped materials or the like may be used instead); and is machined such that the opening of thehole 13 is not chamfered and the outer edge of the tip end face 32 a is chamfered leaving ashoulder 32 b. The depth of thehole 13 is set to be slightly longer than the rear 31 a to be pressed into thehole 13 of thedrill portion 31. Near the bottom of thehole 13, the inner diameter of thehole 13 is gradually decreased to form aspace 13 b for storing shaved chips when the rear 31 a of thedrill portion 31 is fitted (see FIG. 10). - This embodiment has the above-described structure. A method for assembling the
miniature drill 30 will be explained below. - A cylinder of material40 shown in FIG. 11 to be formed into the
shank portion 32 is vacuum quenched so as to achieve approximately 35 to 50 HRC, which is higher than that obtained without quenching (approximately 24 HRC). As compared with conventional quenching under a normal atmosphere, a smoother surface can be obtained with less deteriorated accuracy in size by quenching under vacuum because of less deformation and no oxidation. Therefore, the polishing step for surface treatment after quenching becomes unnecessary or simplified. - The resulting cylinder of material40 is then machined into the
shank portion 32 as is shown in FIG. 8. - Coaxially with the
hole 13 formed in the tip end face 32 a of theshank portion 32, the rear 31 a of thedrill portion 31 is then inserted into thehole 13 with high strength or force at normal temperature which is room temperature. As a result, the diameter of the inner wall 33 a of thehole 13 is enlarged by the rear edge 31 b of thedrill portion 31, and the rear 31 a of thedrill portion 31 is pressed into the hole 13 (see FIGS. 8 and 9). - Since the
whole shank portion 32 is hardened by quenching, when the rear edge 31 b of thedrill portion 31 is pressed into thehole 13 of theshank portion 32, the inner wall 33 a of thehole 13 is not largely shaved and the inner diameter is gradually enlarged, resulting in an increased joint strength with thedrill portion 31. - Meanwhile, assuming that the
drill portion 31 is pressed into theshank portion 32 made of an unquenched material, such as untreated SUS, the inner wall 33 a of thehole 13 is disadvantageously damaged by being shaved or theshank portion 32 may be damaged by cutting chips while using theminiature drill 30 for cutting. - As is shown in FIG. 10, the rear31 a of the
drill portion 31 is pressed into the bottom of thehole 13 with a small amount of chips shaved from the inner wall 33 a being stored in thespace 13 b formed in the bottom of thehole 13. - The
drill portion 31 may then be ground to a more slender shape, as is shown by the single dot chain line in FIG. 10. - As is mentioned above, according to the third embodiment of the present invention, the
shank portion 32 is hardened beforehand by vacuum quenching. Thus, when the diameter of the inner wall 33 a is enlarged by fitting thedrill portion 31 into thehole 13, the fastening joint strength due to the enlargement of the inner wall 33 a increases. Furthermore, thedrill portion 31 has a smoother surface and is not deformed by heat, resulting in a highly accurate miniature drill. Moreover, theshank portion 32 is not damaged by cutting chips while using theminiature drill 30 for cutting. - Although the cylinder of material40 to be formed into the
shank portion 32 is vacuum quenched in the third embodiment, theshank portion 32 may be vacuum quenched after being machined. In such a case, the forming accuracy of the resultingshank portion 32 deteriorates to some extent, and surface treatment is required; also quenching under a normal atmosphere may be employed instead of vacuum quenching. - Nitriding can also be employed instead of quenching. For example, after forming the cylinder of material40 into the
shank portion 32 shown in FIG. 8, the shank portion is heated at approximately 500°C. for 18 to 19 hours in a gaseous ammonium atmosphere, and then, allowed to stand for cooling. The surface of theshank portion 32 is thereby hardened. Furthermore, deformation does not occur because heat treatment such as quenching is unnecessary. - The materials used for the
drill portions shank portions - The
hole 13 of theshank portions drill portions - The present invention can be applied not only to miniature drills but also to other cutting tools such as drilling tools, small-diameter end mills, and the like.
- Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
Claims (15)
1. A method for producing a cutting tool comprising a drill portion and a shank portion, the method comprising the steps of:
forming a hole in the shank portion such that an inner diameter of the hole is slightly smaller than an outer diameter of the drill portion; and
fitting the drill portion into the shank portion by pressing a rear of the drill portion into the hole of the shank portion at normal temperature.
2. A method for forming a cutting tool as set forth in ,
claim 1
further comprising a step of grinding the drill portion to form a drill edge after said fitting step.
3. A method for forming a cutting tool as set forth in ,
claim 1
further comprising a step of quenching the shank portion before said fitting step.
4. A method for forming a cutting tool as set forth in ,
claim 3
wherein said step of quenching is carried out under a vacuum.
5. A method for forming a cutting tool as set forth in ,
claim 1
further comprising a step of hardening a surface of the shank portion by nitriding before the fitting step.
6. A method for forming a cutting tool as set forth in ,
claim 1
further comprising a step of forming a space for storing chips produced by shaving the inner wall of the hole of the shank portion by insertion of the drill portion during said step of fitting, the space formed at a bottom of the hole of the shank portion.
7. A method for forming a cutting tool as set forth in ,
claim 1
further comprising a step of chamfering the rear edge of the drill portion so as to form a rounded chamfer.
8. A method for forming a cutting tool as set forth in ,
claim 1
further comprising a step of chamfering the rear edge of the drill portion so as to form a linear chamfer.
9. A method for forming a cutting tool as set forth in ,
claim 1
wherein the rear edge of the drill portion is sharp.
10. A cutting tool comprising:
a shank portion having a hole; and
a drill portion fitted into said hole of said shank portion to form a joint, said drill portion having a drill edge, wherein a step is formed at said joint.
11. A cutting tool according to ,
claim 10
wherein a surface of said shank is hardened.
12. A cutting tool according to ,
claim 10
wherein a rear edge of said drill portion has a rounded chamfer.
13. A cutting tool according to ,
claim 10
wherein a rear edge of said drill portion has a linear chamfer.
14. A cutting tool according to ,
claim 10
wherein a rear edge of said drill portion forms a sharp point.
15. A cutting tool according to ,
claim 10
further comprising a space between a rear edge of said drill portion and a bottom of said hole of said shank portion.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US09/774,050 US20010002559A1 (en) | 1997-01-31 | 2001-01-31 | Cutting tool and method for producing the same |
Applications Claiming Priority (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP9-019485 | 1997-01-31 | ||
JP1948597A JPH10217017A (en) | 1997-01-31 | 1997-01-31 | Cutting tool connecting method |
JP16139397A JPH1110422A (en) | 1997-06-18 | 1997-06-18 | Manufacture of cutting tool and cutting tool |
JP20810197A JPH1148014A (en) | 1997-08-01 | 1997-08-01 | Joining method for cutting tool |
US09/015,664 US6058807A (en) | 1997-01-31 | 1998-01-29 | Cutting tool and method for producing the same |
US09/497,858 US6200076B1 (en) | 1997-01-31 | 2000-02-04 | Cutting tool and method for producing the same |
US09/774,050 US20010002559A1 (en) | 1997-01-31 | 2001-01-31 | Cutting tool and method for producing the same |
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US09/497,858 Continuation US6200076B1 (en) | 1997-01-31 | 2000-02-04 | Cutting tool and method for producing the same |
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US20010002559A1 true US20010002559A1 (en) | 2001-06-07 |
Family
ID=27282641
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US09/015,664 Expired - Fee Related US6058807A (en) | 1997-01-31 | 1998-01-29 | Cutting tool and method for producing the same |
US09/497,858 Expired - Fee Related US6200076B1 (en) | 1997-01-31 | 2000-02-04 | Cutting tool and method for producing the same |
US09/774,050 Abandoned US20010002559A1 (en) | 1997-01-31 | 2001-01-31 | Cutting tool and method for producing the same |
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US09/015,664 Expired - Fee Related US6058807A (en) | 1997-01-31 | 1998-01-29 | Cutting tool and method for producing the same |
US09/497,858 Expired - Fee Related US6200076B1 (en) | 1997-01-31 | 2000-02-04 | Cutting tool and method for producing the same |
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KR (1) | KR19980070951A (en) |
CN (1) | CN1200968A (en) |
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KR102193189B1 (en) | 2020-02-12 | 2020-12-18 | 주식회사 삼도 | Method for manufacturing cutting tool |
CN113042787B (en) * | 2021-03-24 | 2022-06-21 | 武汉理工大学 | Twist drill and manufacturing method thereof |
CN114192847A (en) * | 2021-12-31 | 2022-03-18 | 江苏博瑞工具有限公司 | Die-casting zinc alloy hexagonal-handle twist drill and manufacturing method thereof |
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US1539413A (en) * | 1923-01-10 | 1925-05-26 | Fish Harold | Lathe centering tool |
US1703899A (en) * | 1925-05-28 | 1929-03-05 | Whitman Barnes Detroit Corp | Method of electrically welding alpha drill |
US2161062A (en) * | 1934-03-24 | 1939-06-06 | Robert J Killgore | Percussion tool |
US3053118A (en) * | 1960-04-29 | 1962-09-11 | Lavallee & Ide Inc | Method of manufacturing reamers |
US3850054A (en) * | 1971-03-11 | 1974-11-26 | B Weissman | Composite drill |
DE2811977A1 (en) * | 1978-03-18 | 1979-09-27 | Hawera Probst Kg Hartmetall | HARD METAL TWIST DRILLS, IN PARTICULAR. FOR DRILLING CIRCUIT BOARDS |
US4225114A (en) * | 1978-10-19 | 1980-09-30 | General Signal Corporation | Butterfly valve with improved shaft connection |
CH650182A5 (en) * | 1981-06-16 | 1985-07-15 | Sphinxwerke Mueller & Cie Ag | Drills and use thereof for drilling printed circuit boards. |
US4462293A (en) * | 1982-09-27 | 1984-07-31 | Gunzner Fred G | Wear-resistant and shock-resistant tools and method of manufacture thereof |
JPH0247139U (en) * | 1988-09-22 | 1990-03-30 | ||
US5074025A (en) * | 1991-03-05 | 1991-12-24 | Jarvis Cutting Tools, Inc. | Threaded shank drill assembly |
US5240356A (en) * | 1991-03-28 | 1993-08-31 | Mitsubishi Materials Corporation | Nitrided cutter machining |
JPH06344212A (en) | 1993-06-04 | 1994-12-20 | Toshiba Tungaloy Co Ltd | Drill of super-small diameter for printed circuit board |
DE19800097A1 (en) * | 1997-01-31 | 1998-08-06 | Mitsubishi Materials Corp | Manufacturing procedure for cutting tool |
-
1998
- 1998-01-02 DE DE19800097A patent/DE19800097A1/en not_active Withdrawn
- 1998-01-27 CN CN98104346A patent/CN1200968A/en active Pending
- 1998-01-29 US US09/015,664 patent/US6058807A/en not_active Expired - Fee Related
- 1998-01-30 KR KR1019980002579A patent/KR19980070951A/en not_active Application Discontinuation
-
2000
- 2000-02-04 US US09/497,858 patent/US6200076B1/en not_active Expired - Fee Related
-
2001
- 2001-01-31 US US09/774,050 patent/US20010002559A1/en not_active Abandoned
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20060207398A1 (en) * | 2003-07-08 | 2006-09-21 | Nicolson Peter J | Saw blade |
Also Published As
Publication number | Publication date |
---|---|
KR19980070951A (en) | 1998-10-26 |
US6200076B1 (en) | 2001-03-13 |
DE19800097A1 (en) | 1998-08-06 |
US6058807A (en) | 2000-05-09 |
CN1200968A (en) | 1998-12-09 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: EXPRESSLY ABANDONED -- DURING EXAMINATION |