JP3639227B2 - Drilling tools for brittle materials - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drilling tool for a brittle material, which drills a hard brittle material containing silicon, various ceramics, glass, or a cemented carbide material such as tungsten carbide (WC).
[0002]
[Prior art]
For example, in the case of manufacturing a shower head used in a semiconductor device manufacturing apparatus, when drilling a brittle material such as single crystal silicon, it has been mostly performed by laser processing conventionally. Laser processing has the problem that the laser processing apparatus required for processing is expensive and the running cost is high, which is uneconomical. Accordingly, the inventors of the present invention have a predetermined cutting edge at the tip of the tool body that is rotated around the axis, even in the case of such a brittle material, as in the case of drilling a normal metal material. An attempt was made to drill a hole using a drill-shaped drilling tool formed with a tip angle.
[0003]
[Problems to be solved by the invention]
However, when trying to drill the brittle material with such a drilling tool, such a material is brittle, so compared to the case of drilling a metal material such as a general steel material. Cracks, cracks, and the like are very likely to occur. In particular, such cracks and cracks are likely to occur when a tip having a tip angle of a cutting blade located on the axis at the tip of the tool body bites the workpiece. This is because the rotation speed of the tool body is 0 on this axis, so that the tip of the cutting blade comes into contact with the work piece at one point, thereby causing an excessive load on the work piece. This is thought to be due to the action of cracks. Such a problem is caused by the fact that the hole diameter is extremely small as in the case of using the drilled brittle material for the shower head in the above-mentioned semiconductor device manufacturing apparatus, and therefore, the outside diameter of the cutting tool's cutting blade is small. This is particularly noticeable when the diameter becomes extremely small and the tip of the cutting edge comes into contact with the workpiece at an extremely small point.
[0004]
Then, in order to solve such a problem, the inventors of the present invention previously described in Japanese Patent Application No. 2000-331508 the tip portion of a cylindrical shaft-shaped tool body rotated around the axis line. The surface may be a flat surface orthogonal to the axis or a concave surface whose inner peripheral portion is recessed with respect to the outer peripheral portion, and can be bitten by surface contact or line contact with the workpiece. A drilling tool for brittle materials with a diamond coating on the tip is proposed. Therefore, in such a drilling tool, the tip of the tool body bites into the workpiece by surface contact or line contact, and at this time, the uneven projections microscopically formed by the diamond coating applied to the tip surface are cut. Since it acts as a blade and the recess acts as a chip pocket, as if grinding with a grindstone, however, it becomes possible to perform drilling by cutting action with many cutting blades extremely smaller than the abrasive grains of the grindstone, An excessive load does not act on the workpiece, and even if the workpiece is a brittle material, cracks such as cracks and cracks can be prevented.
[0005]
However, with such a drilling tool in which the tip surface is made flat or concave to make surface contact or line contact with the workpiece, cracks and cracks are reliably generated when the workpiece is made of a brittle material. However, it is not easy to secure the centripetal property of the tool body because the biting is surface contact or line contact. That is, in such a drilling tool, when the bite is bitten, the above-mentioned tip surface made flat is evenly in contact with the work piece, or the outer peripheral edge of the tip surface made concave is evenly around the entire circumference. If you do not touch the workpiece at once, there is a risk that the tool body may sway, which makes it difficult to improve the accuracy of straightness and roundness of the machined hole. It turns out that a problem arises.
[0006]
The present invention has been made under such a background. In the case of drilling a workpiece made of a brittle material as described above with a drilling tool, the diameter of the drilled hole is particularly small. However, it is an object of the present invention to provide a drilling tool for a brittle material that can prevent cracks and cracks from occurring in the workpiece, as well as ensure high centripetality and form a highly accurate drilled hole. .
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve such an object, the present invention is a drilling tool for a brittle material that drills a workpiece made of a brittle material, and is a cylinder rotated about an axis. At the tip of the shaft-shaped tool body, three or more tip surfaces that intersect with each other at one intersection located on the axis and toward the rear end side from the intersection toward the outer peripheral side are formed in the circumferential direction. And at least two of the intersecting ridge lines of the tip surfaces adjacent to each other are cutting edges extending from the intersection, and at least the cutting edge portion is covered with a hard carbon film, or at least the cutting edge portion is made of a hard carbon body. It is formed.
[0008]
Here, the hard carbon film that covers the cutting edge portion is, for example, a diamond film or a DLC film, and, as in the previously proposed drilling tool described above, the uneven projections microscopically formed by such a film. Cutting is performed by the part, and the concave part acts as a chip pocket to drill a brittle material. Further, as the hard carbon body forming the cutting edge portion, a diamond sintered body or a diamond single crystal can be used, and the same effect can be obtained. And this cutting edge part is an intersection ridgeline of three or more tip surfaces formed at the tool body tip, and is formed so as to extend from the intersection point on the axis line where these tip surfaces intersect. When the intersection first bites into the workpiece, centripetality is obtained and the tool body is prevented from being shaken. If the cutting edge is one of the above-mentioned cross ridge lines, that is, if only one cutting edge is formed on the tool body, the load on the cutting edge is large, and the tool body at the time of drilling Stability will be impaired. On the other hand, the cracks and cracks in the brittle material due to the load when this intersection bites, the cutting of the brittle material is due to the fine uneven projections of the hard carbon film as described above, and the feed of the tool body becomes extremely small This can be prevented. In addition, for example, the generation of cracks such as cracks and cracks can be avoided by performing step feed processing with such minute feed.
[0009]
In the present invention, first, the above-mentioned There are four tip surfaces. The intersecting ridge lines formed by intersecting the tip surfaces are arranged so as to be unequal in the circumferential direction. In addition, the fan-shaped central angles formed by the pair of tip surfaces located on opposite sides of the intersection point in the axial tip view are made equal to each other. As a result, the tip surface located on the tool rotation direction side of the intersecting ridge line, which is the cutting edge, can be increased in the circumferential direction, and therefore the space defined between the tip surface and the hole bottom of the machining hole is increased. Since the cutting edge can be largely secured on the side of the tool rotation direction, the chips generated by the cutting edge can be accommodated in this space and processed smoothly. Second, the intersection angle formed by at least some of the intersecting ridge lines with the axis at the intersection is set to an angle different from the intersection angle formed by the other intersecting ridge lines with the axis at the intersection. Only the intersecting ridge line with a large corner acts as a cutting edge, and a large space can be secured between the tip surface between the cutting edges adjacent in the circumferential direction and the hole bottom of the machining hole. It is possible to achieve a smooth chip treatment. Thirdly, the intersecting ridge lines are arranged at irregular intervals in the circumferential direction, and at least some of the intersecting ridge lines are intersected with the axis at the intersecting points, and the other intersecting ridge lines are at the intersecting points. If the angle is different from the crossing angle formed with the axis, smooth chip treatment can be achieved more reliably. Furthermore, by arranging the intersecting ridge lines at unequal intervals as described above, or by setting the intersecting angles to different angles, among the pair of tip surfaces adjacent to intersecting the intersecting ridge line that is the cutting edge. The tip surface located on the rotational direction side of the tool body forms an angle with respect to the plane including the axis and the cutting edge, and the tip surface located on the rear side in the rotational direction of the tool body forms the plane. The cutting edge can be set smaller than the angle, so that the cutting angle can be increased by increasing the rake angle in the axial direction of the cutting edge toward the positive side, and the cutting edge angle can be increased by decreasing the clearance angle. Blade strength can be ensured.
[0010]
In addition, at least the intersecting ridge line that is the cutting edge can be sharpened by biting the work piece of the cutting edge at the intersection to obtain higher centripetalness, By forming a convex curve that bulges toward the tip end in the axial direction, the cutting edge gradually bites into the work piece from the intersection point, so that the work piece can be more reliably prevented from cracking. At the same time, it is possible to prevent chipping from occurring on the cutting edge due to the impact load at the time of biting. However, even when the cutting edge is linear or convex, the intersection angle between the intersecting ridgeline of the cutting edge and the axis at the intersection is set in the range of 45 to 87.5 °. If it is smaller than this, centripetality can be obtained, but the biting may be too sharp and cracking and chipping may not be avoided, and if it is larger than this, sufficient centripetality cannot be obtained. There is a fear. In addition, if one or more chip discharge grooves that open to the front end surface and extend to the rear end side are formed on the outer periphery of the tip of the tool body, the chips generated by the cutting blade are smoothly discharged. Therefore, it is possible to prevent deterioration of processing accuracy due to biting of chips. However, even when the chip discharge groove is formed in this way, in order to ensure the rigidity of the tool body and prevent breakage or the like, the core thickness at the tip of the tool body is set to the outer diameter of the cutting blade. It is desirable to set it to 0.5D or more with respect to D, and in order to further ensure both the chip dischargeability and the rigidity of the tool, the core thickness is in the range of 0.6D to 0.9D. It is more desirable to set.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
1 to 5 show a first embodiment of the present invention. In the present embodiment, the tool body 1 is integrally formed of a hard material such as a cemented carbide, and a tip portion 2 that is inserted into a workpiece to perform drilling is gripped by a spindle of a machine tool and a shank portion. The tapered portion 4 has a multi-stage cylindrical shaft shape with the axis O reduced by one step with respect to the rear end portion 3 being formed, and the portion between both end portions 2 and 3 is gradually reduced in diameter toward the front end side. Is tied by In the present embodiment, the four flat ends that intersect the tip of the tip 2 at one intersection P on the axis O and incline toward the rear end from the intersection P toward the outer peripheral side. Tip surfaces 5 are formed, and therefore, in the tool body 1, the position of the intersection point P is projected to the most tip side, and the four intersecting ridge lines 6 where the tip surfaces 5 intersect each other are From the intersection point P, it is formed so as to recede linearly toward the rear end side toward the outer peripheral side and to extend radially from the intersection point P when viewed from the front in the axis O direction.
[0012]
In the present embodiment, the four tip surfaces 5 are different from each other in the sector-shaped central angle formed by the tip surfaces 5 in the front view in the direction of the axis O, and thereby the tip surfaces 5 adjacent in the circumferential direction. ... 4 intersecting ridgelines 6 of each other are arranged at different intervals in the circumferential direction. However, in the present embodiment, among the four tip surfaces 5..., The sector-shaped central angles formed by the pair of tip surfaces 5 and 5 located on opposite sides of the intersection point P with respect to the tip view in the direction of the axis O are made equal to each other. Therefore, the cross ridge lines 6... Are also formed so that the pair of cross ridge lines 6 and 6 located on the opposite side across the intersection P extend on one straight line as shown in FIG. As a result, they are arranged symmetrically with respect to the axis O.
[0013]
In the present embodiment, these four intersecting ridgelines 6... Intersect with the axis O at the intersection P at the same intersection angle θ. And in this embodiment, the whole surface of the said front-end | tip part 2 including these front-end | tip surfaces 5 ... and its intersection ridgeline 6 ..., and the intersection P is made from a diamond film or a DLC film as shown with a dot in the figure. The hard carbon film 7 is covered. Therefore, in the drilling tool configured in this way, the rotation trajectories formed by the four intersecting ridge lines 6 at the tip of the tool body 1 around the axis O coincide with each other, and one cone having the intersection P as the apex. Therefore, all of these four intersecting ridgelines 6... Act as cutting edges 8 extending from the intersection point P, and these cutting edges 8. Will be coated.
[0014]
Here, the drilling tool of the present embodiment forms an extremely small diameter processing hole in a brittle material such as single crystal silicon in the case of manufacturing a shower head used in a semiconductor device manufacturing apparatus as described above. Therefore, the outer diameter D of the cylindrical shaft-shaped tip portion 2 for drilling the brittle material is also extremely small, about 0.2 to 3 mm, and the length L of the tip portion 2 is Is about 1 to 10 mm. Further, when the hard carbon film 7 applied to the surface of the tip 2 is, for example, a diamond film, a microwave plasma CVD method or a hot filament is applied to the tip 2 of the tool body 1 made of cemented carbide. It is formed by a method such as a CVD method, and as a raw material gas at this time, a mixed gas such as hydrogen and methane or CO is used, and a processing temperature is generally about 800 to 900 ° C. The film thickness is about 5 to 25 μm, and the formed hard carbon particles such as diamond particles have a particle size of about 0.1 to 10 μm.
[0015]
In the drilling tool of the present embodiment configured as described above, the rear end portion 3 of the tool body 1 is gripped by the main spindle of the machine tool and rotated about the axis O as described above, and the front end side in the axis O direction. Is drilled into a workpiece made of a brittle material such as single crystal silicon. However, the feed amount of the tool body 1 to the tip end side in the axis O direction at this time is set to be extremely small, for example, 0.025 to 0.15 μm / rev, and more preferably while the feed and retraction of the tool body 1 are repeated. Step feed processing is performed to gradually cut into the workpiece. Further, at the time of drilling, it is desirable to supply cutting oil to the drilled part of the workpiece.
[0016]
Accordingly, in the drilling process having the above-described configuration, since the intersection point P is projected to the most distal end side in the tool body 1 as described above, the intersection point P first bites the work piece, Cutting edges 8 extending from the intersection point P are cut into the workpiece from the inner peripheral side, and the workpiece is scraped from the intersection point P by the fine irregularities of the hard carbon film 7 covered on the cutting blade 8. Are cut to form a processed hole. Since the intersection point P that first bites into the workpiece is located on the axis O that is the center of rotation of the tool body 1, the diameter of the tool body 1 is reduced during the biting or drilling process. High centripetality can be obtained by preventing the occurrence of directional deflection, and therefore the straightness and roundness of the formed hole can be improved, and high-precision drilling can be achieved. it can. On the other hand, the load concentrated on the work piece when the intersection point P bites the work piece at one point is caused by minimizing the feed of the tool body 1 or performing step feed work as described above. Therefore, it is possible to prevent cracks such as cracks and cracks from occurring when a workpiece made of a brittle material is bitten by such a load.
[0017]
Further, in the first embodiment, as described above, the intersecting ridge lines 6 that are the cutting edges 8 at the tip of the tool body 1 are arranged so as to be unequally spaced in the circumferential direction of the tool body 1. Therefore, even if the tool body 1 is rotated to any side in the circumferential direction during drilling, the cutting edge located on the tool rotation direction T side among the cutting edges 8 and 8 whose circumferential distance is reduced. On the side of the tool rotation direction T of 8, a tip surface 5 having a large central angle is disposed. Accordingly, the tip surface 5 with the increased central angle and the conical surface having the intersection P formed by the rotation locus around the axis O of the cutting edge 8, that is, the machining formed by the cutting edge 8 during drilling. Since a large space is secured on the tool rotation direction T side of the cutting blade 8 between the hole bottom and the hole, according to the present embodiment, the hard carbon film 7 coated on the cutting blade 8 is used. The chips generated by scraping the workpiece by the fine irregularities of the metal can be accommodated and discharged in this large space, and such chips are caught between the machining hole and the tool body 1. When the cutting oil is supplied as described above, the cutting oil is retained in this space while preventing clogging between the bottom of the hole and the tip surface 5. As a result, it is possible to efficiently supply the cutting blade 8 or the hole bottom of the processed hole.
[0018]
On the other hand, instead of making the intersection angles θ of the intersecting ridge lines 6 with respect to the axis O equal to each other and causing all the intersecting ridge line portions 6 to act as the cutting edges 8 as in the first embodiment, FIG. As in the second embodiment shown in FIG. 9, the intersection angle α with respect to the axis O of the pair of intersection ridge lines 6a, 6a located on the opposite side of the intersection P among the four intersection ridge lines 6. The crossing angle β of a part of the crossing ridge lines 6a is made larger than the crossing angle β of the pair of crossing ridgelines 6b, 6b located on the opposite side across P with respect to the axis O, and the crossing angle β of the other crossing ridgelines 6b. Different angles may be used. In the second embodiment and the subsequent embodiments to be described later, the same reference numerals are assigned to components common to each other, and the description thereof is omitted. Moreover, in this 2nd Embodiment, the space | interval of the circumferential direction of intersection ridgeline 6 ... is mutually made equal.
[0019]
In such a second embodiment, when the feed of the tool body 1 is minimized as described above, the intersecting ridge lines 6a and 6a having a large intersecting angle α are shown by chain lines in FIG. As shown in Fig. 5, the intersection ridge lines 6b and 6b having a small intersection angle β are positioned on the tip side, and only these intersection ridge lines 6a and 6a act as the cutting edge 8, and intersect with each other. The portions on the outer peripheral side of the ridge lines 6b, 6b are located on the rear end side of the cross ridge lines 6a, 6a and do not participate in the cutting, and thus the cross ridge lines that are the cutting edges 8 in the circumferential direction of the tool body 1. Between 6a and 6a, a large reciprocal space with respect to the rotation trajectory formed by the cutting edge 8 around the axis O, that is, the bottom of the drilled hole is secured. Therefore, according to the second embodiment as well, it becomes possible to store and discharge the chips generated by the cutting blade 8 in this space, and smooth chip processing and cutting oil as in the first embodiment. It becomes possible to plan supply.
[0020]
10 to 14 show a third embodiment of the present invention. In the third embodiment, the configurations of the first and second embodiments are combined, that is, As in the first embodiment, the intersecting ridge lines 6 are arranged at unequal intervals in the circumferential direction, and among these, a pair of intersecting ridge lines 6a, 6a located on opposite sides with respect to the axis O with respect to the axis O The crossing angle α is made larger than the crossing angle β with respect to the axis O of the pair of crossing ridge lines 6b, 6b located on the opposite side across the other crossing point P. The crossing ridge line 6b is different from the crossing angle β. However, in this third embodiment, among the intersecting ridgelines 6 and 6 whose circumferential intervals are reduced by arranging the intersecting ridgelines 6 at unequal intervals, the intersection located on the tool rotation direction T side. The crossing angle α of the ridge line 6a is made larger than the crossing angle β of the crossing ridgeline 6b located behind the tool rotation direction T of the crossing ridgeline 6a, and the crossing ridgeline 6a acts as the cutting edge 8. Has been made. Therefore, according to the drilling tool of the third embodiment as described above, the tip surface 5 having a large central angle is arranged on the tool rotation direction T side of the cutting blade 8 as in the first embodiment. As in the second embodiment, the intersection ridge line 6b is positioned on the rear end side of the intersection ridge line 6a, so that the space formed on the tool rotation direction T side of the cutting edge 8 is further secured. Therefore, as compared with the first and second embodiments, it is possible to achieve more smooth chip disposal and cutting oil supply.
[0021]
By the way, as in the third embodiment, among the crossed ridgelines 6... Arranged at unequal intervals in the circumferential direction, the crossing angles α of some crossing ridgelines 6a are different from the crossing angles β of other crossing ridgelines 6b. In the case of an angle, an angle formed by a pair of front end surfaces 5 and 5 that intersect the intersecting ridge line 6a serving as the cutting edge 8 and that are adjacent in the circumferential direction with respect to the plane Q including the axis O and the intersecting ridge line 6a. 14, that is, as shown in FIG. 14, of the pair of tip surfaces 5, 5, the tip surface 5 a located on the tool rotation direction T side of the cutting edge 8 is relative to the plane Q. Can be set smaller than the angle δ formed by the tip surface 5b positioned on the rear side in the tool rotation direction T with respect to the plane Q. Therefore, for the tip surface 5a connected to the tool rotation direction T side of the intersecting ridge line 6a that becomes the cutting edge 8, that is, the tip face 5a that becomes the rake face of the cutting edge 8, the rake angle is a negative angle, but more A large angle on the regular angle side can improve the sharpness by the cutting edge 8 and can reduce the resistance at the time of drilling. On the other hand, the cross ridge line 6a to be the cutting edge 8 is in the tool rotation direction T rear side. The inclination of the leading end surface 5b, that is, the leading end surface 5b serving as the flank of the cutting edge 8, is small with respect to the plane Q, that is, the flank angle is small, so that the axial rake angle is increased as described above. Nevertheless, it is possible to ensure a large edge angle of the cutting edge 8, and therefore it is possible to ensure the edge strength of the cutting edge 8, and to reduce the resistance, chipping the cutting edge 8 and the like. Prevent the occurrence of tools Extension of life can be achieved.
[0022]
Furthermore, in each of the above-described embodiments, the entire surface of the tip 2 from the tip surface 5 of the tool body 1 to the outer periphery of the tip 2 is provided with a hard carbon coating 7 such as a diamond coating or a DLC coating. The wear resistance of the entire tip 2 of the main body 1 can be improved and damage to the tool main body 1 can be prevented more reliably, and the outer periphery of the tip 2 thus provided with the hard carbon film 7 can be prevented. Is inserted into the machining hole along with the feed of the tool body 1 and is brought into sliding contact with the inner circumference thereof, so that the inner circumference of the machining hole is made higher by the fine irregularities of the hard carbon film 7 on the outer circumference of the tip portion 2. There is also an advantage that the finished surface can be processed with accuracy. However, in the present embodiment, the entire surface of the tip portion 2 is covered with the hard carbon film 7 in this way. However, the cutting blade 8 is in direct contact with the workpiece and is involved in cutting exclusively. Since this is the intersection ridge line portion 6 (6a) portion of the intersection point P and the distal end surface 5 ..., for example, only the distal end side of the distal end portion 2 is covered or only the distal end surface 5 including the intersection point P and the intersection ridge line 6 ... Or, in some cases, only the cutting edge 8 portion of the intersection point P or the intersection ridge line 6 may be covered on the front end surface 5.
[0023]
In the above embodiment, at least the cutting edge 8 is coated with the hard carbon film 7 such as a diamond film or a DLC film, and the brittle material surface is cut off by fine irregularities on the surface. However, the same effect can be obtained even if at least the cutting blade 8 portion is formed of a hard carbon body such as a diamond sintered body or a diamond single crystal. Therefore, instead of coating the hard carbon film 7 as described above, the intersection P or the tip portion 2 of the tool body 1 or the portion including the tip surface 5. A portion including at least the cutting edge 8 around the intersecting ridge line 6 may be formed by joining such a hard carbon body to the tool body 1 by brazing or the like.
[0024]
On the other hand, in each of the above-described embodiments, the tip end faces 5 are all flat, and all of the intersecting ridge lines 6 including the intersecting ridge line 6 (6a) serving as the cutting edge 8 are linear. Therefore, it is possible to sharpen the biting of the work piece at the intersection point P, to obtain higher centripetality, and to reliably prevent the tool body 1 from swinging when biting. However, instead of making the cutting edge 8 linear in this way, as shown in the fourth embodiment shown in FIG. 15 to FIG. Accordingly, at least the intersecting ridge line 6 that is the cutting edge 8 is formed in a convex curved surface that bulges and curves so as to be convex toward the tip end side (tip outer periphery side) of the tool body 1 in the axis O direction. You may make it make the convex curve shape which swells to the front end side. From the fourth embodiment to the subsequent sixth embodiment, the intersection ridgelines 6 of the tip surfaces 5 are made unequal in the circumferential direction as in the third embodiment. Of the intersecting ridge lines 6 and 6 whose direction intervals are reduced, the intersecting angle α with respect to the axis O of the intersecting ridge line 6a located on the tool rotation direction T side is equal to the intersecting angle α of the intersecting ridge line 6b on the rear side in the tool rotation direction T. The intersecting ridge line 6 a is a cutting edge 8. However, in the fourth embodiment in which the intersection ridge line 6 is a convex curve, the intersection angles α and β are intersection angles between the tangent line of the intersection ridge line 6 and the axis O at the intersection point P.
[0025]
Accordingly, also in the fourth embodiment in which the cutting edge 8 has a convex curve in this way, the intersection point P bites into the work piece and drilling is performed. The mentality can be ensured, and the deflection of the tool body 1 can be suppressed to prevent the processing accuracy from deteriorating. In addition, by making the cutting edge 8 convex in this way, the cutting edge 8 gradually bites into the work piece from the intersection P toward the outer peripheral side. Can prevent the occurrence of cracks more reliably by suppressing the abrupt action on the workpiece, while also improving the strength of the cutting edge 8 on the drilling tool side. It is possible to prevent chipping from occurring especially in the vicinity of the intersection point P of the cutting edge 8 due to the mechanical load, and it is possible to further extend the tool life.
[0026]
In addition, including the case where the cutting edge 8 has a convex curve shape as described above, the intersecting ridge lines 6 (6a) acting as the cutting edge 8 at least intersecting angles θ and α with respect to the axis O are 45 to 87. It is desirable to set the angle within a range of 5 °, that is, when the pair of cutting blades 8 and 8 are formed in a straight line when viewed from the front in the direction of the axis O with the intersection point P therebetween as in the above embodiments. Is preferably set so that the crossing angle formed by these cutting edges 8 and 8 is in the range of 90 to 175 ° which is twice the crossing angle θ and α. This is because if the crossing angles θ and α formed by the cutting edge 8 with respect to the axis O are smaller than the above range, the biting when the cutting edge 8 bites the work piece at the intersection P becomes too sharp. Although the mentality is increased, there is a risk that cracks in the workpiece and chipping in the vicinity of the intersection P of the tool body 1 may not be prevented. Conversely, if the crossing angles θ and α are larger than the above ranges, such cracks and chipping may occur. Can be effectively prevented, but sufficient centripetality may not be obtained, which may lead to deterioration of the accuracy of the machined hole. In other words, in the present embodiment, by setting the crossing angles θ and α of the cutting edge 8 in the above range, it is possible to provide sufficient centripetalness to the tool body 1 while reliably preventing cracks and chipping, and machining accuracy. This can be improved.
[0027]
Moreover, in each said embodiment, the front-end | tip part 2 of the tool main body 1 is formed in the column shape, and when the said front-end | tip surface 5 ... is formed in the front-end | tip, the said intersection is made to the intersection ridgeline part 6 (6a). A cutting edge 8 is formed from P to the outer periphery of the tip 2, and therefore the core thickness d of the tool body 1 at the tip 2 is made equal to the outer diameter D of the cutting edge 8. 2 has a high rigidity, but for example, as in the fifth embodiment shown in FIGS. 18 and 19, the cutting edge 8 is provided on the outer peripheral surface of the tip portion 2. Except for the part that reaches the outer periphery, the second picking surface 9 is formed so as to be recessed one step on the inner peripheral side, or the second picking surface 9 is formed as in the sixth embodiment shown in FIGS. In addition to or alone, the chip discharge groove 10 is for example cut. Adjacent to the tool rotation direction T side of the outer peripheral end of the 8 may be may be formed so as to open to the front end face 5.
[0028]
Thus, in the drilling tool in which the second surface 9 is formed, the contact area between the inner periphery of the machining hole and the tip 2 of the tool body 1 can be reduced, so that the resistance especially during drilling is reduced. It is effective in the case. Further, in addition to the second picking surface 9, or in a drilling tool in which the chip discharge groove 10 is formed alone, the hole bottom generated by the cutting blade 8 and the tip surface 5 is processed as described above. The chips accommodated in the space between them can be discharged even when the tip 2 is inserted into the machining hole, and therefore, the chips are more reliably prevented from being caught and clogged. In addition, the cutting oil can be supplied efficiently. In addition, a certain amount of chip discharging effect and cutting oil supply effect can be obtained only by the second picking surface 9. Further, the second picking surface 9 and the chip discharge groove 10 may be formed straight in parallel with the axis O, but as these are directed toward the rear end side as illustrated, toward the rear side in the tool rotation direction T. If formed so as to be twisted, the chips can be pushed out to the rear end side as the tool body 1 rotates, whereas if formed so as to be twisted in the opposite direction, the hole is formed from the opening side of the machining hole. Cutting oil can be fed to the bottom side.
[0029]
However, when the second catching surface 9 and the chip discharge groove 10 are formed on the outer periphery of the tip portion 2 of the tool body 1 in this way, the core thickness d of the tool body 1 at the tip portion 2 is outside the cutting edge 8. Although it is smaller than the diameter D, it is desirable to secure a core thickness d of 0.5 × D or more with respect to the outer diameter D of the cutting blade 8 even when the core thickness d is thus reduced. That is, if the core thickness d is smaller than 0.5 × D, it is difficult to ensure rigidity at the tip 2 of the tool body 1 and the tip 2 may be broken. There is. In addition, in order to achieve both of ensuring the rigidity of the tool and improving the chip discharge performance by forming the second catching surface 9 and the chip discharge groove 10 as described above, It is more desirable to set the core thickness d in the range of 0.6 × D to 0.9 × D with respect to the outer diameter D of the cutting blade 8.
[0030]
Further, in each of the above embodiments, four tip surfaces 5 are formed on the tip 2 of the tool body 1 so that four intersecting ridge lines 6 are formed. However, as described above, the intersection P is the tool body. In order to obtain centripetality at the time of drilling by being located at the forefront of 1, it is sufficient that there are at least three front end surfaces 5 intersecting at this intersection point P. For example, the seventh embodiment shown in FIG. As described above, six tip end faces 5 may be formed to form six intersecting ridge lines 6. Even in this case, if the intersecting angles of the intersecting ridge lines 6 with respect to the axis O are equal to each other, all the intersecting ridge lines 6 act as the cutting edges 8, and the intersecting angles of some of the intersecting ridge lines 6 are different from the others. Then, as shown in the figure, the intersection ridge portion 6a having the largest intersection angle acts as the cutting edge 8. Further, the number of the tip surfaces 5 and the intersecting ridge lines 6 may be an odd number as long as there are three or more. However, even in such a case, at least two items are required to prevent the tool body 1 from swinging during drilling. Are made to act as cutting edges 8.
[0031]
【The invention's effect】
As described above, according to the present invention, the tool body bites into the work piece at the intersection located on the axis of the tip, so that the centripetality of the tool body during the biting or drilling process is secured. As a result, the machining accuracy such as straightness and roundness of the machined hole can be improved, and the hard carbon film coated on the cutting edge extending from this intersection and the cutting edge The hard carbon body that forms can reliably prevent cracks, cracks and the like from occurring on a workpiece made of a brittle material. Further, the intersection ridgelines of the front end surface intersecting the intersection point are arranged at unequal intervals in the circumferential direction, or the intersection angle formed by some of the intersection ridgelines with the axis line is different from the others, or these are By combining them, it is possible to secure a large space on the side of the tool rotation direction of the intersecting ridge line, which is the cutting edge during drilling, and the cutting edge generated by the hard carbon film or hard carbon body of the cutting edge. It becomes possible to process the powder smoothly.
[Brief description of the drawings]
FIG. 1 is a side view showing a first embodiment of the present invention.
FIG. 2 is an enlarged perspective view of a distal end portion 2 of the first embodiment.
FIG. 3 is a front view of the distal end portion 2 of the first embodiment as viewed from the distal end side in the axis O direction.
4 is a cross-sectional view taken along the line AA in FIG.
5 is a cross-sectional view taken along the line BB in FIG.
FIG. 6 is an enlarged perspective view of a distal end portion 2 according to a second embodiment of the present invention.
FIG. 7 is a front view of the distal end portion 2 of the second embodiment as viewed from the distal end side in the axis O direction.
8 is a cross-sectional view taken along AA in FIG.
9 is a cross-sectional view taken along the line BB in FIG.
FIG. 10 is an enlarged perspective view of a distal end portion 2 according to a third embodiment of the present invention.
FIG. 11 is a front view of the distal end portion 2 of the third embodiment as viewed from the distal end side in the axis O direction.
12 is a cross-sectional view taken along AA in FIG.
13 is a cross-sectional view taken along the line BB in FIG.
14 is a cross-sectional view orthogonal to the cutting edge 8 in the third embodiment. FIG.
FIG. 15 is an enlarged perspective view of a distal end portion 2 according to a fourth embodiment of the present invention.
FIG. 16 is a front view of the distal end portion 2 of the fourth embodiment as viewed from the distal end side in the axis O direction.
FIG. 17 is a cross-sectional view taken along AA in FIG.
FIG. 18 is an enlarged perspective view of a distal end portion 2 according to a fifth embodiment of the present invention.
FIG. 19 is a front view of the distal end portion 2 of the fifth embodiment viewed from the distal end side in the axis O direction.
FIG. 20 is an enlarged perspective view of a distal end portion 2 according to a sixth embodiment of the present invention.
FIG. 21 is a front view of the distal end portion 2 of the sixth embodiment when viewed from the distal end side in the axis O direction.
FIG. 22 is an enlarged perspective view of a distal end portion 2 according to a seventh embodiment of the present invention.
[Explanation of symbols]
1 Tool body
5 (5a, 5b) Tip surface
6 (6a, 6b) Intersecting ridgeline of the end face 5 ...
7 Hard carbon film
8 Cutting blade
9 Second face
10 Chip discharge groove
O Axis of tool body 1
P Intersection of tip surface 5 ...
T Tool rotation direction
Q plane including cutting edge 8 and axis O
D Outer diameter of cutting edge 8
d Core thickness at the tip 2 of the tool body 1
θ, α, β Intersection angle formed by the intersecting ridge line 6 (6a, 6b) with respect to the axis O
Angle formed by the tip surface 5a of the γ cutting edge 8 on the tool rotation direction T side with respect to the plane Q
δ Angle formed by the tip surface 5b of the cutting edge 8 on the rear side in the tool rotation direction T with respect to the plane Q

Claims (14)

A drilling tool for a brittle material that drills a workpiece made of a brittle material, and intersects each other at one intersection point located on the axis at the tip of a cylindrical shaft-shaped tool body that rotates about the axis. In addition, four leading end surfaces are formed toward the rear end side from the intersection point toward the outer peripheral side, and at least two of the intersecting ridge lines of the tip end surfaces adjacent in the circumferential direction extend from the intersection point. while being, at least the cutting edge portion is covered by the hard carbon film, is further disposed at unequal intervals the intersecting edge line in the circumferential direction Rutotomoni, located on the opposite side of the intersection to the axial forward end viewed A fan-shaped drilling tool for a brittle material, characterized in that the sector-shaped central angles formed by the pair of tip surfaces are equal to each other . A drilling tool for a brittle material that drills a workpiece made of a brittle material, and intersects each other at one intersection point located on the axis at the tip of a cylindrical shaft-shaped tool body that rotates about the axis. In addition, three or more front end faces toward the rear end side from the intersection point toward the outer peripheral side are formed, and at least two of the intersecting ridge lines between the front end faces adjacent in the circumferential direction extend from the intersection point. And at least a part of the cutting edge is covered with a hard carbon film, and at least a part of the intersecting ridge line has an intersection angle with the axis at the intersection, and the other intersecting ridge line has the axis at the intersection. A drilling tool for brittle materials, characterized in that it is set at an angle different from the crossing angle. A drilling tool for a brittle material that drills a workpiece made of a brittle material, and intersects each other at one intersection point located on the axis at the tip of a cylindrical shaft-shaped tool body that rotates about the axis. In addition, three or more front end faces toward the rear end side from the intersection point toward the outer peripheral side are formed, and at least two of the intersecting ridge lines between the front end faces adjacent in the circumferential direction extend from the intersection point. And at least a portion of the cutting edge is covered with a hard carbon film, and the intersecting ridge lines are arranged at irregular intervals in the circumferential direction, and at least a part of the intersecting ridge lines are the axis line at the intersection point. The brittle material drilling tool is characterized in that the crossing angle formed is set to an angle different from the crossing angle formed by the other crossing ridge line with the axis at the crossing point. The brittle material drilling tool according to any one of claims 1 to 3, wherein the hard carbon film is a diamond film or a DLC film. A drilling tool for a brittle material that drills a workpiece made of a brittle material, and intersects each other at one intersection point located on the axis at the tip of a cylindrical shaft-shaped tool body that rotates about the axis. In addition, four leading end surfaces are formed toward the rear end side from the intersection point toward the outer peripheral side, and at least two of the intersecting ridge lines between the tip end surfaces adjacent in the circumferential direction extend from the intersection point. together are opposite at least the cutting edge is formed by the hard carbon material, is further disposed at unequal intervals the intersecting edge line in the circumferential direction Rutotomoni, across the intersection to the axial direction front end viewed A brittle material drilling tool, characterized in that the center angles of the sector formed by the pair of tip surfaces located on the side are equal to each other . A drilling tool for a brittle material that drills a workpiece made of a brittle material, and intersects each other at one intersection point located on the axis at the tip of a cylindrical shaft-shaped tool body that rotates about the axis. In addition, three or more front end faces toward the rear end side are formed from the intersection toward the outer peripheral side, and at least two of the intersecting ridge lines between the front end faces adjacent in the circumferential direction extend from the intersection. A cutting edge, at least the cutting edge portion is formed of a hard carbon body, and at least a part of the intersecting ridge line has an intersecting angle with the axis at the intersecting point, and the other intersecting ridge line is the intersecting point. A drilling tool for a brittle material, characterized in that it is set at an angle different from the crossing angle formed with the axis. A drilling tool for a brittle material that drills a workpiece made of a brittle material, and intersects each other at one intersection point located on the axis at the tip of a cylindrical shaft-shaped tool body that rotates about the axis. In addition, three or more front end faces toward the rear end side are formed from the intersection toward the outer peripheral side, and at least two of the intersecting ridge lines between the front end faces adjacent in the circumferential direction extend from the intersection. It is a cutting edge, at least the cutting edge portion is formed of a hard carbon body, and the intersecting ridge lines are arranged at unequal intervals in the circumferential direction, and at least some of the intersecting ridge lines are A brittle material drilling tool, characterized in that an intersection angle formed with the axis at an intersection is set to an angle different from an intersection angle formed with the other axis at the intersection. The brittle material drilling tool according to any one of claims 5 to 7, wherein the hard carbon body is formed of a diamond sintered body or a diamond single crystal. Of the pair of tip surfaces that intersect and intersect the intersecting ridge line that is the cutting edge, the angle formed by the tip surface that is located on the rotational direction side of the tool body with respect to the plane that includes the axis and the cutting blade is The brittle material according to any one of claims 1 to 8, wherein a tip surface located on the rear side in the rotation direction of the tool body is set to be smaller than an angle formed with respect to the plane. Drilling tool. The brittle material drilling tool according to any one of claims 1 to 9, wherein at least the intersecting ridge line used as the cutting edge is linear. The brittle material drilling tool according to any one of claims 1 to 9, wherein at least the intersecting ridge line that is the cutting edge has a convex curved shape that swells toward the tip end in the axial direction. . The crossing angle which the intersecting ridgeline made into the said cutting edge makes with the said axis line in the said intersection is set to the range of 45-87.5 degrees, The one of Claim 1 thru | or 11 characterized by the above-mentioned. Drilling tool for brittle materials. 13. One or more chip discharge grooves that open to the front end surface and extend to the rear end side are formed on the outer periphery of the front end of the tool body. Drilling tool for brittle materials as described in 1. The brittle material according to any one of claims 1 to 13, wherein a core thickness at a tip portion of the tool body is set to 0.5D or more with respect to an outer diameter D of the cutting blade. Drilling tool.

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