JP2006068877A - Double-margin drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability by restraining welding of a margin without impairing brazing strength of a cutting edge tip. <P>SOLUTION: Since the surfaces of margins 18, 20 are provided with a diamond film 32, welding to the margins 18, 20 is restrained, and on the other hand, since the cutting edge tip 24 is brazed to the drill body 12 after coating with the diamond film 32, a predetermined brazing strength is obtained to substantially improve the life of a tool. Since the cutting edge tip 24 is brazed to the drill body 12 after coating with the diamond film 32 and the cutting edge 30 or the like is shaped, there is no fear that the knife edge is rounded due to coating of the cutting edge 30 with the diamond film 32, and excellent sharpness is obtained to further improve the working accuracy. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a double margin drill, and more particularly to an improvement of a double margin drill in which a cutting edge tip provided with a cutting edge of a high hardness sintered body is brazed.

(a) a drill body provided with a land; and (b) a cutting edge tip provided with a cutting edge of a high-hardness sintered body and brazed to the drill body, and (c) the land of the land. A double margin drill in which margins are provided on both the leading edge side and the heel side is known. The drill described in Patent Document 1 is an example, and a diamond sintered body or a CBN (cubic boron nitride) sintered body is used as a high-hardness sintered body. According to such a double margin drill, the center runout is suppressed and the burnishing action is obtained by the engagement between the margin provided at the front and rear of the land and the inner diameter surface of the machining hole, and aluminum, copper or the like can be obtained. It is possible to perform drilling with high processing accuracy even for soft metals such as alloys containing as a main component.
JP 2002-66820 A

  However, since such a double margin drill performs drilling while rubbing the margin against the inner diameter surface of the processing hole, welding tends to occur in the margin depending on the processing conditions. In some cases, it was damaged and sufficient durability could not be obtained.

  On the other hand, it is conceivable that the surface is coated with diamond or TiAlN. However, since the coating process temperature is relatively high, the brazing strength of the cutting edge tip may be impaired, and the durability may be impaired. There is. That is, the brazing temperature is generally about 700 to 800 ° C., while the diamond coating processing temperature is about 1000 to 1200 ° C., and the TiAlN processing temperature is about 600 to 700 ° C., which is higher or similar to the brazing temperature. Therefore, there is a possibility that the brazing strength is lowered and the cutting edge tip is peeled off.

  The present invention has been made against the background described above, and its object is to improve the durability by suppressing the welding of the margin without impairing the brazing strength of the cutting edge tip.

  In order to achieve such an object, the present invention provides: (a) a drill body provided with lands; and (b) a cutting edge tip brazed to the drill body provided with a cutting edge made of a high-hardness sintered body. (C) in a double margin drill in which a plurality of margins are provided in the land, (d) the drill body is coated with diamond or TiAlN before the cutting edge tip is brazed. The surface of the margin is processed, and a diamond coating or a TiAlN coating is provided.

  In such a double margin drill, since a diamond film or a TiAlN film is provided on the surface of the margin, welding to the margin is suppressed, and after coating such a film, the cutting edge tip is attached to the drill body. Since brazing is performed, a predetermined brazing strength is obtained and the tool life is substantially improved. Since the oxidation start temperature (durability) of the diamond coating and TiAlN coating is about 800 ° C., there is no risk of deterioration due to subsequent brazing of the cutting edge tip. Good welding resistance is maintained. As a result, even when drilling a soft metal such as aluminum, copper, or an alloy thereof, excellent machining accuracy is achieved over a long period of time with respect to the surface roughness and diameter of the inner surface of the hole due to the burnishing action of the margin. To be obtained.

  Moreover, since the cutting edge tip is brazed after coating the drill body with the diamond coating or TiAlN coating, the cutting edge is not covered with such coating and the cutting edge is not rounded, and an excellent sharpness is obtained. Processing accuracy is further improved.

  The double margin drill of the present invention is suitably used for drilling soft materials such as aluminum, copper, or soft metals such as alloys based on them, but also for drilling other work materials. Can be used. Cemented carbide is preferably used as the material of the drill body, but steel materials such as high-speed tool steel and alloy tool steel can also be employed.

  There may be one chip discharge groove or a plurality of chip discharge grooves forming the land of the drill body, and the groove may be a twist groove twisted around the axis or a straight groove parallel to the axis. In general, two grooves are provided, and a cutting edge is provided at each end opening of the groove.

  The cutting edge tip is configured to include a high-hardness sintered body having at least a cutting edge. As the high-hardness sintered body, a diamond sintered body or a CBN sintered body is preferably used. For example, by sintering integrally with a base such as cemented carbide, the base is sintered with high hardness. A cutting edge tip to which the body is integrally fixed is formed. The brazing temperature for brazing the cutting edge tip to the drill body is, for example, about 700 to 800 ° C.

  After the cutting edge tip is brazed to the drill body, the drill tip including the cutting edge tip is shaped as necessary to form the intended cutting edge and flank. This shaping process is performed, for example, by cutting with wire-cut electric discharge machining or grinding with a grinder.

  A plurality of margins are provided, for example, on the front and rear sides of the land, that is, on the leading edge side and the heel side, but may be provided at intermediate positions thereof. This margin is desirably provided over the entire length of the land in the axial direction in order to stabilize the position of the drill, but it may be provided only partially on a part of the cutting edge side (front end side in the axial direction).

  The diameter of the margin is the same as, for example, the drill diameter (outer diameter of the cutting edge) D, but may be slightly larger or smaller than the drill diameter D. It is also possible to make the diameter dimensions of a plurality of margins provided on the leading edge side and the heel side different from each other.

  As a diamond film coating method, a microwave plasma CVD method is preferably used. The processing temperature is about 1000 to 1200 ° C., which is sufficiently higher than the brazing temperature, and the oxidation start temperature of the diamond film is about 800 ° C. Yes, there is no possibility that the coating performance such as wear resistance and welding resistance of the diamond coating is impaired by brazing of the cutting edge tip. The film thickness of the diamond coating is suitably in the range of 6 to 16 μm. If it is thinner than 6 μm, sufficient effects of welding resistance and wear resistance cannot be obtained. On the other hand, if it is thicker than 16 μm, the internal stress increases and peeling occurs. It becomes easy to do. The diamond film can be coated by other film forming methods such as a filament CVD method, an arc plasma CVD method, and an ionized vapor deposition method.

  As a coating method for the TiAlN film, an arc discharge ion plating method is preferably used. The processing temperature is about 600 to 700 ° C., which is lower than the brazing temperature, but the oxidation start temperature of the TiAlN film is about 800 ° C. There is no fear that the coating performance such as wear resistance and welding resistance of the TiAlN coating is impaired by brazing of the cutting edge tip. The thickness of the TiAlN coating is suitably in the range of 0.5 to 20 μm, and if it is thinner than 0.5 μm, sufficient effects of welding resistance and wear resistance cannot be obtained, while if it is thicker than 20 μm, it is easy to peel off. Become. Note that the TiAlN film can be coated by another film forming method such as a sputtering method.

  When coating the drill body with the diamond coating or TiAlN coating, a masking agent is applied to the tip mounting seat for brazing the cutting edge tip so as not to impair the brazing strength of the cutting edge tip. For example, it is desirable to prevent such a coating from adhering to the chip mounting seat.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1A and 1B are diagrams illustrating a double margin drill 10 for soft material according to an embodiment of the present invention. FIG. 1A is a front view of a tip portion, and FIG. 1B is a right side view of FIG. (C) is a cross-sectional view of the surface layer portion of the drill body 12 portion. This double margin drill 10 is mainly composed of a cemented carbide drill body 12, and by forming two straight grooves 14 as chips discharging grooves, a pair of lands 16 are formed at the center of the axis. The lands 16 are provided with margins 18 and 20 on the leading edge side and the heel side, respectively. The margins 18 and 20 both have the same diameter as the drill diameter D, and are provided over the entire length of the land 16 in the drill axis direction.

  A concave chip mounting seat 22 is provided at each opening of the straight groove 14 on the drill tip side, and a cutting edge chip 24 is integrally fixed by brazing. The cutting edge tip 24 is obtained by sintering a diamond sintered body 26 as a high-hardness sintered body integrally with a cemented carbide base 28, and the base 28 is brazed to the chip mounting seat 22. In addition, a cutting blade 30 is provided in the diamond sintered body 26 that is integrally fixed on the base 28 by sintering. N-type thinning is applied to the center of the tip of the drill body 12, and a diamond coating 32 is provided on the surface of the drill body 12 with a predetermined film thickness in the range of 6 to 16 μm. The double margin drill 10 has a drill diameter D of 8.6 mm (φ8.6), a core thickness of 0.23 D, a drill tip angle of 120 °, and the thickness of the base 28 of the cutting edge tip 24 is as follows. About 0.9 mm, and the thickness of the diamond sintered body 26 is about 0.7 mm.

  FIG. 2 is a diagram showing the manufacturing process of such a double margin drill 10. First, a chip mounting seat 22 and the like are formed by grinding or the like on a cemented carbide rod-shaped material provided with straight grooves 14 and lands 16. A drill body 12 is prepared. Next, in a state where a masking agent is applied to the tip mounting seat 22 of the drill body 12, a diamond coating process is performed at a processing temperature of about 1000 to 1200 ° C. by a microwave plasma CVD method, and the surface of the drill body 12 is made of diamond. Cover with a coating 32. Thereafter, the cutting edge tip 24 is brazed to the tip mounting seat 22 on which the diamond coating 32 is not provided, and the drill tip including the cutting edge tip 24 is shaped into a target shape. The cutting edge tip 24 is brazed at a predetermined temperature in the range of 700 to 800 ° C., and the shaping of the drill tip is performed by cutting by wire-cut electric discharge machining or grinding with a grinder. Form relief surfaces.

  In the double margin drill 10 of this embodiment, since the diamond coating 32 is provided on the surfaces of the margins 18 and 20, the welding to the margins 18 and 20 is suppressed, while the diamond coating 32 is coated. Since the cutting edge tip 24 is later brazed to the drill body 12, a predetermined brazing strength is obtained and the tool life is substantially improved. Since the oxidation start temperature of the diamond coating 32 is about 800 ° C., there is no risk of deterioration due to subsequent brazing of the cutting edge tip 24, and the wear resistance and welding resistance of the diamond coating 32 are maintained well. The As a result, even when drilling a soft metal such as aluminum, copper, or an alloy thereof, excellent machining accuracy with respect to the surface roughness and diameter of the inner surface of the processed hole due to the burnishing action of the margins 18 and 20 Can be obtained over a long period of time.

  Further, since the cutting edge tip 24 is brazed after the diamond coating 32 is coated on the drill body 12, and the cutting blade 30 or the like is shaped, the cutting edge 30 is covered with the diamond coating 32 so that the cutting edge is formed. There is no fear of rounding, an excellent sharpness is obtained, and the processing accuracy is further improved.

  Next, the results of a durability test and the like conducted by the present inventors will be described. FIG. 3A shows the specifications of the product of the present invention and the comparative product used in the test. The product of the present invention is the same as the double margin drill 10 of the above embodiment, and the comparative product is compared with the product of the present invention. The only difference is that the diamond coating 32 is not provided. Then, using a vertical machining center, tool protrusion size 50 mm, vegetable oil MQL (Minimum Quantity Lubrication; minimum amount lubrication, air pressure 0.5 MPa) oil supply, two kinds of processing conditions 1 shown in FIG. Then, drilling was performed on ADC12 (aluminum alloy die casting) under the processing condition 2.

  The cutting test 1 in FIG. 4A was performed when 1000 holes were continuously drilled under the processing condition 1, and both the present invention product and the comparative product were capable of drilling 1000 holes or more. In the product of the present invention having the diamond coating 32, no welding was observed at the margins 18 and 20 even after the test, but the non-coated comparative product had a white rubbing trace of aluminum and was slightly welded. Admitted.

  The cutting test 2 in FIG. 4 (b) is a case where 5000 holes were continuously drilled under the processing condition 2, and the product of the present invention was able to drill more than 5000 holes, but the comparative product was From the initial stage, welding occurred in the margins 18 and 20, the inner surface of the processed hole was peeled off, and the surface roughness was poor.

  The cutting test 3 in FIG. 4 (c) is the cutting torque when drilling is performed under the machining condition 1 when it is new, and is an average value of 5 holes. The product of the present invention is substantially the same as the non-coated comparative product. Value.

  FIG. 4 (d) shows the results of examining the surface roughness of the inner diameter surface of the processed hole and the hole diameter of the final hole in cutting tests 1 and 2, and the product of the present invention is superior to the comparative product particularly in the final hole. Surface roughness was obtained. In the cutting test 2 under the processing condition 2 where the cutting speed and the feeding speed are fast, the surface roughness of the product of the present invention is superior to that of the comparative product even for the first hole. There was almost no difference in the hole diameter.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention implements in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

It is a figure explaining the double margin drill which is one Example of this invention. It is a figure which shows the manufacturing process of the double margin drill of FIG. It is a figure explaining the test article and processing conditions which were used in the durability test etc. which the present inventors performed. It is a figure which shows test results, such as durability.

Explanation of symbols

  10: Double margin drill 12: Drill body 16: Land 18, 20: Margin 24: Cutting edge tip 26: Diamond sintered body (high hardness sintered body) 30: Cutting edge 32: Diamond coating

Claims (1)

A drill body provided with a land,
A cutting edge tip provided with a cutting edge of a high hardness sintered body and brazed to the drill body,
In a double margin drill having a plurality of margins in the land,
The double-margin drill is characterized in that the drill body is coated with diamond or TiAlN before the cutting edge tip is brazed, and a diamond coating or a TiAlN coating is provided on the surface of the margin. .

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