JP2013022663A - Drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a machined hole of high quality with a desired inner diameter according to a diameter of a cutting edge in a work material made of copper or copper alloy.SOLUTION: A cutting chip discharge groove 4 is formed in an outer circumference of a tip of a drill body 1 rotated around an axis O and made of one kind of superhard material among cemented carbide, cermet, and ceramics, or high-speed tool steel. From the inner circumferential side of the drill body 1 toward the outer circumferential side, the cutting edge 5 extended to the rear end is formed on a tip lateral edge of a wall surface facing a drill rotating direction T of the cutting chip discharge groove 4. With respect to a diameter D of the cutting edge 5, a tip X of the cutting edge 5 is radially deviated from the axis O by a gap δ within a range of 0.01×D or more to 0.03×D or less. When the drill body 1 is made of the superhard material, a core diameter is 0.2×D or more, and when the drill body 1 is made of the high-speed tool steel, the core diameter is 0.3×D or more.

Description

  The present invention relates to a drill suitable for use in drilling a workpiece made of copper or a copper alloy.

  In the drilling process of a general steel material drill, due to factors based on the cutting mechanism and the balance of the cutting edge, the drilling hole expands by 1 to 2% with respect to the diameter of the cutting edge. On the other hand, it is known that the drilled hole of copper alloy contracts. Therefore, in Patent Document 1, as a twist drill suitable for drilling such copper and copper alloy, the work material shrunk by increasing the back taper to 0.056 / 100 to 0.187 / 100. There has been proposed a drill which prevents breakage due to frictional resistance with the side surface of the machined hole.

JP 2008-000875 A

  By the way, such a drill is generally reused by regrinding the cutting edge by grinding and retracting the tip flank when the cutting edge wear progresses. As described, in a drill having a large back taper, the reduction rate of the diameter of the cutting edge when the tip flank is retracted by a predetermined amount by regrinding becomes large. Therefore, the inner diameter of the processed hole to be formed in the work material is also significantly reduced after re-polishing compared to before re-polishing, especially when drilling a work material made of copper or copper alloy. In combination with the fact that the machining hole itself contracts, there is a problem that the inner diameter of the machining hole does not reach a desired size with a small number of re-polishings and the drill life is shortened.

  The present invention has been made under such a background, and it is possible to form a high-quality machining hole having a desired inner diameter corresponding to the diameter of the cutting edge for a work material made of copper or a copper alloy. The purpose is to provide a simple drill.

  In order to solve the above problems and achieve such an object, the present invention firstly provides a drill body made of any one of cemented carbide, cermet, and ceramics rotated around an axis. A chip discharge groove is formed on the outer periphery of the tip part, and a chip extending toward the rear end side from the inner peripheral side of the drill body toward the outer peripheral side is formed on the tip side edge of the wall facing the drill rotation direction of the chip discharge groove. A blade is formed, and the tip of the cutting blade is displaced in the radial direction from the axis with a deviation amount in the range of 0.01 × D to 0.03 × D with respect to the diameter D of the cutting blade. And the core thickness of the drill body is 0.2 × D or more.

  In addition, the present invention secondly, a chip discharge groove is formed on the outer periphery of the tip of the drill body made of high-speed tool steel rotated around the axis, and the tip side of the wall surface of the chip discharge groove facing the drill rotation direction A cutting edge extending toward the rear end side from the inner peripheral side to the outer peripheral side of the drill main body is formed at the side ridge portion. It is shifted in the radial direction from the axis with a shift amount in the range of 01 × D or more and 0.03 × D or less, and the core thickness of the drill body is 0.3 × D or more. .

  In the drill of the present invention configured as described above, the tip of the cutting edge extending toward the rear end side from the inner peripheral side to the outer peripheral side of the drill main body is 0.01 × with respect to the diameter D of the cutting edge. Since it is displaced in the radial direction from the rotation axis of the drill body by a deviation amount in the range of D or more and 0.03 × D or less, when the tip of the cutting blade bites into the work material, the cutting blade is centered on the tip. The cutting blade on the side opposite to the side on which the tip is shifted is rotated with a diameter larger than the diameter D by an amount corresponding to the amount of deviation.

  Therefore, it is possible to form a machining hole with a large inner diameter without changing the diameter D of the cutting blade itself for a work material made of copper or a copper alloy, and to obtain a desired inner diameter when the machining hole contracts. Can do. On the other hand, on the side where the tip of the cutting edge is shifted with respect to the axis of the drill body, a clearance corresponding to the amount of deviation occurs between the inner peripheral surface of the machining hole and the outer periphery of the tip of the drill body. Even if the back taper is not increased as in the drill described in Document 1, it is possible to suppress the frictional resistance against the shrunk inner peripheral surface of the machined hole and prevent breakage, etc., and the shrinkage rate of the diameter of the cutting edge by re-grinding The drill life can be extended by reducing the length of the drill.

  Here, if the amount of deviation is so small that it is less than 0.01 × D with respect to the diameter D of the cutting edge, it is impossible to obtain a desired inner diameter when the machining hole contracts as described above, and The clearance with the inner peripheral surface of the processing hole on the side where the tip is shifted becomes insufficient, and scratches are formed on the inner peripheral surface of the processing hole, or the outer periphery of the drill is significantly damaged. On the other hand, if the amount of deviation is larger than 0.03 × D, the runout of the cutting blade becomes large and scratches and life ring marks are formed on the inner peripheral surface of the processed hole, leading to deterioration of surface roughness. At the same time, the cutting load is uneven on the side where the tip of the cutting edge is shifted and the opposite side, making it impossible to stably drill the processing hole to the desired inner diameter. Will be formed.

  Further, when the drill body is made of any one of super hard materials of cemented carbide, cermet, and ceramics, if the core thickness of the drill body is less than 0.2 × D, the drill body is made of these super hard materials. If it is made of high-speed tool steel with lower hardness, if the core thickness of the drill body is less than 0.3 x D, the rigidity of the drill body tip will be impaired and the behavior during drilling will become unstable, May not be formed, or the inner diameter may be unnecessarily large, or scratches, life ring marks, and surface roughness may be deteriorated on the inner peripheral surface of the processed hole.

  The greater the core thickness, the higher the rigidity of the tip of the drill body. On the other hand, the chip discharge performance is impaired, and the inner peripheral surface of the processing hole is damaged by chip clogging, the cutting edge is missing, and in some cases There is also a risk of breaking the drill body. For this reason, even when the drill body is made of cemented carbide, cermet, ceramics or high-speed tool steel, the core thickness is about 0.5 × D with respect to the diameter D of the cutting edge. desirable.

  As described above, according to the present invention, a work material made of copper or a copper alloy can be stably and desired while preventing breakage of the drill body and ensuring the surface accuracy of the inner peripheral surface of the processed hole. A bore with an inner diameter can be formed.

It is a side view which shows one Embodiment of this invention. It is an enlarged front view of embodiment shown in FIG. FIG. 3 is a ZOXY sectional view in FIG. 2.

  1 to 3 show an embodiment of the present invention. In the drill of this embodiment, the drill body 1 is integrally formed of a superhard material made of any one of cemented carbide, cermet, and ceramics, or a high-speed tool steel, and the outer shape has an axis O. The drill body 1 has a cylindrical shape with the rear end portion (left side portion in FIG. 1) of the drill body 1 as a cylindrical shank portion 2 and the tip portion (right side portion in FIG. 1) is the blade portion 3. It is said that. However, in the illustrated example, the outer periphery of the rear end surface of the shank portion 2 is chamfered.

  On the other hand, the blade portion 3 has a pair of chip discharge grooves 4 that are twisted around the axis O so as to go to the rear side with respect to the drill rotation direction T at the time of drilling from the front end surface toward the rear end side. These chips are formed so as to be 180 ° rotationally symmetric with respect to O, and the chip discharge grooves 4 are cut off to the outer peripheral side on the rear end side of the drill body 1 and terminate. Therefore, with the end of the chip discharge groove 4, that is, the position of the raised end as a boundary, the rear end side is the shank portion 2 and the tip end side is the blade portion 3.

  Further, the front end surface of the blade portion 3 is inclined so as to go to the rear end side from the periphery of the axis O on the inner peripheral side toward the outer peripheral side, and intersects with the wall surface facing the drill rotation direction T of the chip discharge groove 4. Even if it goes to the rear side in the drill rotation direction T from the ridgeline, it is inclined so as to go to the rear end side. And the cutting edge 5 is formed in this intersection ridgeline, ie, the edge part edge part of the said wall surface, Therefore The said wall surface which faces the drill rotation direction T of the chip discharge groove | channel 4 continuing to this cutting edge 5 is the rake face of the cutting edge 5. In addition, the tip surface connected to the cutting blade 5 is a tip flank of the cutting blade 5.

  In this embodiment, the thinning blade 5A is formed on the inner peripheral side of the cutting blade 5 by thinning the tip flank. This thinning is referred to as X-type thinning in the present embodiment, and the thinning blades 5A of the pair of cutting blades 5 formed at the tip side ridges of the pair of chip discharge grooves 4 pass through chisel edges. Instead, the cutting edge 5 is crossed at an intersection of approximately one point, and with this intersection point as the tip X, the cutting edge 5 has a predetermined tip angle so as to go from the thinning blade 5A on the inner peripheral side toward the outer peripheral side of the drill body 1 toward the rear end It is inclined with.

  The tip X of the cutting blade 5 is displaced from the axis O in the radial direction by a deviation amount δ in the range of 0.01 × D to 0.03 × D with respect to the diameter D of the cutting blade 5. . Here, the diameter D of the cutting blade 5 is a diameter of a circle formed by the outer peripheral end of the cutting blade 5 around the axis O, and in the present embodiment, the diameter D of the pair of cutting blades 5 is equal to each other. In the present embodiment, the tip X has a cutting edge on the side where the tip X is shifted with respect to the diameter line L connecting the outer peripheral ends of the pair of cutting edges 5 as shown in FIG. The right cutting edge) 5 is positioned on the rear side of the drill rotation direction T, but may be positioned on the drill rotation direction T side with respect to the diameter line L, or on the diameter line L. It may be shifted from the axis O.

  On the other hand, in the blade part 3 in which the chip discharge groove 4 at the tip of the drill body 1 is formed, the diameter of a circle in contact with the groove bottom surface of the chip discharge groove 4 around the axis O in the cross section orthogonal to the axis O, That is, the core thickness is set to 0.2 × D or more with respect to the diameter D of the cutting blade 5 when the drill body 1 is made of any one of super hard materials of cemented carbide, cermet, and ceramics. ing. When the drill body 1 is made of high-speed tool steel having a hardness lower than that of these super hard materials, the core thickness is set to 0.3 × D or more.

  In the drill constructed in this manner, the shank portion 2 is mounted on the main shaft of the machine tool, and is sent to the front end side in the axis O direction while being rotated in the drill rotation direction T around the axis O. Drilling is performed on the work material made of copper or copper alloy by the cutting blade 5. However, since the tips X of these cutting edges 5 are shifted from the axis O that is the center of rotation of the drill body 1, if the tips X of the cutting edges 5 bite the work material, the tips of the blade 3 Is sent out while rotating eccentrically from the axis O around the tip X.

  Accordingly, the inner diameter (diameter) of the machining hole formed in the work material by the eccentric blade portion 3 is such that the tip X shifted from the axis O and the cutting blade 5 on the side from which the tip X is shifted. Is twice the radial distance to the tip X between the outer peripheral edge of the opposite cutting edge (left cutting edge in FIG. 2) 5, that is, the diameter D of the cutting edge 5 according to the deviation δ. Larger diameter machining holes are formed. For this reason, the diameter D of the cutting edge 5 is not changed, and thus a machining hole with a large diameter is formed in this way. Therefore, even if the machining hole shrinks in drilling of a work material made of copper or copper alloy, The inner diameter of the processed hole can be made more equal to the diameter D of the cutting edge 5.

  On the other hand, the radial distance between the outer peripheral end of the cutting blade 5 on the side where the tip X is shifted and the tip X is the distance from the outer peripheral end of the cutting blade 5 on the side opposite to the side where the tip X is shifted. Since the distance is shorter than the distance, on the side where the tip X is shifted, a clearance corresponding to the deviation δ is also generated between the outer peripheral surface of the blade portion 3 and the inner peripheral surface of the machining hole. For this reason, without giving a large back taper like the drill described in Patent Document 1, it is possible to suppress the frictional resistance with the inner peripheral surface of the processed hole and prevent the drill body 1 from being significantly damaged. It is possible to provide a long-life drill by reducing the shrinkage rate of the diameter D of the cutting edge 5 by polishing.

  Further, since the deviation δ is in the range of 0.01 × D to 0.03 × D with respect to the diameter D of the cutting blade 5, the inner diameter of the processed hole becomes larger than necessary or desired. It is possible to prevent the inner diameter from being reached and to prevent the surface roughness and quality of the processed hole from being impaired. In other words, if the amount of deviation δ is so small that it is less than 0.01 × D with respect to the diameter D of the cutting edge 5, a desired inner diameter is obtained when the machining hole shrinks in the work material made of copper or copper alloy. In addition, the clearance between the inner peripheral surface of the processing hole and the outer peripheral surface of the blade portion 3 on the side where the tip X of the cutting blade 5 is shifted becomes insufficient, and the friction cannot be sufficiently suppressed. Scratches are formed on the inner peripheral surface of the hole, or significant damage occurs on the outer peripheral portion of the drill.

  On the other hand, when the deviation amount δ is larger than 0.03 × D with respect to the diameter D of the cutting blade 5, the swinging of the cutting blade 5 rotating around the tip X becomes large, and the inner diameter is larger than necessary. Large machining holes are formed, and scratches and life ring marks are easily formed on the inner circumferential surface of the machining holes. Further, since the cutting load is unbalanced between the cutting edge 5 on the side where the tip X is shifted and the cutting edge 5 on the opposite side, a machining hole in which the center of the machining hole is eccentric or distorted is formed. As a result, it becomes impossible to stably drill the processing hole to a desired inner diameter.

  Furthermore, in the drill having the above-described configuration, the drill body 1 is formed of cemented carbide, cermet, or the like with respect to the diameter D of the cutting edge 5 when the core thickness of the tip 3 of the drill body 1 in which the cutting edge 5 is formed. When the drill body 1 is made of high-speed tool steel, it is set to 0.3 × D or more when the drill body 1 is made of high-speed tool steel. Therefore, even if the tip X of the cutting blade 5 is displaced from the axis O in this way, more stable drilling can be performed.

  In other words, when the drill body 1 is a high-speed tool steel, the core thickness of the blade portion 3 is smaller than 0.3 × D, and even when the drill body 1 is formed of the above-mentioned super-hard material having a higher hardness than this, If the core thickness of the portion 3 is smaller than 0.2 × D, the rigidity of the blade portion 3 is impaired. Therefore, especially when the tip X of the cutting blade 5 is displaced from the axis O as described above, drilling is performed. The behavior of the blade 3 at the time becomes unstable. For this reason, the straightness and roundness of the machined hole are also impaired, the desired machined hole is not formed, the inner diameter becomes larger than necessary, and the inner surface of the machined hole is scratched, life ring mark, surface roughness Degradation may occur.

  However, if the core thickness is increased too much, the cross-sectional area of the chip discharge groove 4 is reduced even if rigidity is ensured, thereby hindering smooth chip discharge. May be deteriorated, the cutting edge 5 may be damaged, or the resistance during drilling may increase, possibly leading to breakage of the drill body 1. Whether it is a hard material or a high-speed tool steel, it is desirable that the core thickness of the blade portion 3 is about 0.5 × D with respect to the diameter D of the cutting blade 5.

  In the present embodiment, as described above, the tip flank is subjected to X-shaped thinning on the inner peripheral side of the cutting blade 5 so that the thinning blades 5A of the pair of cutting blades 5 intersect without passing through the chisel. Thus, the intersection point is the tip X of the cutting edge 5, but even if not thinned or applied, the tip flank of the pair of cutting edges intersect to form a chisel, The chisel may be the tip X of the cutting blade 5 by connecting the cutting blade 5 to the chisel. The displacement amount δ of the tip X at this time may be a displacement amount from the axis O at the center of the chisel.

  Examples of the present invention will be given below to demonstrate the effects of the present invention. In this example, in the drill whose basic configuration is based on the above-described embodiment, the drill body 1 includes a plurality of types of drills in which the core thickness and the deviation amount δ are variously changed including 0 mm. Manufactured with cemented carbide and high-speed tool steel, and drills the work material made of copper or copper alloy with these drills. It was confirmed and confirmed. The results are shown in Table 1 for drilling hole inner diameter accuracy when the drill body 1 is an ultra-hard material, Table 2 for inner peripheral surface condition, and the hole bore inner diameter when the drill body 1 is high-speed tool steel. The accuracy is shown in Table 3, and the state of the inner peripheral surface is shown in Table 4.

  In any of these drills, the diameter D of the cutting edge 5 is 7.0 mm. Therefore, in Tables 1 to 4, the deviation δ is 0.07 mm (0.01 × D) and 0.14 mm (0.02). × D), and 0.21 mm (0.03 × D). In Tables 1 and 2, the core thickness is 0.2 × D or more, and in Tables 3 and 4, the core thickness is 0.3 ×. The thing of D or more becomes a drill of the Example of this invention, and a thing other than that becomes a comparative example with respect to an Example. The overall length of the drill body 1 is 90 mm, the length of the chip discharge groove 4 in the direction of the axis O, that is, the length of the blade 3 is 48 mm, the twist angle of the chip discharge groove 4 is 30 °, and the tip angle of the cutting edge 5 is 140. °.

  In addition, the evaluation of the inner diameter accuracy of machining holes shown in Tables 1 and 3 was performed using an inner diameter measuring pin with a diameter of 7.0 mm. A round mark was used for the pin, a pin that smoothly entered and no wobbling occurred, a double circle, and a pin that wobbled or wobbled even when the pin was inserted was a triangular mark. Furthermore, in the evaluation of the condition of the inner peripheral surface of the machining holes in Tables 2 and 4, the surface roughness is evaluated as a cross mark when a scratch or a life ring mark is confirmed on the inner peripheral surface, but no large scratch or a life ring mark is recognized. Slightly rough ones were marked with triangles, scratches were not recognized, and smooth ones were marked with double circles.

  In addition, the work material in the drilling process shown in Tables 1 and 2 is a 30 mm-thick plate material made by Kobe Steel Co., Ltd. trade name: HR750 (copper alloy), and is cut by a vertical machining center. A through hole was formed at a speed of 30 m / min and a feed amount of 0.2 mm / rev. Further, the work material in the drilling process shown in Tables 3 and 4 is a plate material made of brass having an alloy number C2801 specified in JIS H 3100: 2006 and having a thickness of 30 mm, which is cut by a vertical machining center. A through hole was also formed at a speed of 20 m / min and a feed amount of 0.15 mm / rev.

  Among these, first, as for the results of the bore hole accuracy shown in Tables 1 and 3, the deviation δ is in the range of 0.01 × D to 0.03 × D, and the drill body 1 is made of cemented carbide. The core thickness is 0.2 × D or more, and the drill body 1 is high-speed tool steel, the core thickness is 0.3 × D or more. It was confirmed that all of the drilled machining holes were evaluated as double circles, and the machining holes with high accuracy as the diameter D of the cutting blade 5 were formed.

  On the other hand, in the case of a normal drill in which the deviation amount is 0 mm, that is, in the normal drill in which the tip of the cutting edge coincides with the axis of the drill body, the machining hole contracts and the pin does not enter, and the deviation amount is 0. Even with a drill as small as .035 mm (0.005 × D), the pin does not enter due to shrinkage of the processing hole, or it is quite tight even if it enters, so the desired inner diameter is not obtained, Even when the deviation amount was 0.07 mm (0.01 × D), the same was true for a drill with a small core thickness. On the contrary, in the case of 0.28 mm (0.04 × D) where the deviation amount is larger than 0.03 × D, the case where the core thickness is large was evaluated as a double circle, but in the case where the core thickness is small. The inner diameter was enlarged too much, and this was the same even when the deviation amount was 0.21 mm (0.03 × D) and the core thickness was small.

  On the other hand, regarding the evaluation of the inner peripheral surface of the processed hole, the processed holes formed by the drills of the examples according to the present invention were all free from scratches and life ring marks, and had good surface roughness and smoothness. On the other hand, all of the drilled holes drilled with a normal drill with a deviation of 0 mm showed scratches on the inner peripheral surface, and this is the same for the small deviation of 0.035 mm with the larger core thickness. there were. On the other hand, a life ring mark was seen in the case where the deviation amount was as large as 0.28 mm and the core thickness was small. In addition, in the case where the core thickness is small, even if the deviation amount is in the range of 0.01 × D to 0.03 × D, the surface roughness of the case where scratches or life ring marks are recognized, or there are no large scratches. Some are rough.

  Therefore, based on a comprehensive evaluation of the inner diameter accuracy and the state of the inner peripheral surface of these processed holes, when the drill body 1 is made of cemented carbide, the deviation δ is 0.01 × D or more and 0.03 × D or less. If the core thickness is 0.2 × D or more and the drill body 1 is high-speed tool steel, the deviation δ is still in the range of 0.01 × D to 0.03 × D. In addition, the drill of the embodiment of the present invention having a core thickness of 0.3 × D or more can form a bore having excellent inner diameter accuracy and inner surface quality with respect to a copper alloy. I understand.

DESCRIPTION OF SYMBOLS 1 Drill main body 2 Shank part 3 Blade part 4 Chip discharge groove 5 Cutting blade 5A Thinning blade O The rotation axis of the drill body 1 T Drill rotation direction X Tip of the cutting blade D Diameter of the cutting blade 5 δ From the axis O of the tip X Deviation amount

Claims (2)

  A chip discharge groove is formed on the outer periphery of the tip of the drill body made of any one of cemented carbide, cermet, and ceramics rotated around the axis, and the tip of the wall surface of the chip discharge groove faces the drill rotation direction. A cutting edge extending toward the rear end side from the inner peripheral side to the outer peripheral side of the drill main body is formed at the side ridge portion. It is shifted in the radial direction from the axis with a shift amount in a range of 01 × D or more and 0.03 × D or less, and the core thickness of the drill body is 0.2 × D or more. drill.   A chip discharge groove is formed in the outer periphery of the tip of the drill body made of high-speed tool steel rotated about the axis, and the inner periphery of the drill body is formed on the edge of the tip side of the wall facing the drill rotation direction of the chip discharge groove. A cutting blade extending toward the rear end side from the side toward the outer peripheral side is formed, and the tip of the cutting blade is 0.01 × D or more and 0.03 × D or less with respect to the diameter D of the cutting blade. The drill is characterized in that it is displaced in the radial direction from the axis line by a deviation amount in the range of the above, and the core thickness of the drill body is 0.3 × D or more.

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