JP2014161946A - Drilling machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit flank wear while preventing occurrence of uncut fiber or delamination even when applying a drilling process to the fiber-reinforced plastics such as carbon fiber-reinforced ones.SOLUTION: A chip discharge groove 2 is formed at the tip periphery of a drilling machine body 1 rotating around an axial line O, and a cutting blade 6 having the wall face facing the drill rotation direction of the chip discharge groove 2 as a cutting face 4 is formed at the tip of the drilling machine body 1. The cutting blade 6 is provided with: a main cutting blade 6a positioned at the tip inner periphery side of the drilling machine body 1; a chamfer 6b positioned at the rear end outer periphery side of the main cutting blade 6a and having a point angle αb smaller than that αa of the blade 6a; and a projecting curve part 6c positioned between the blade 6a nd the chamfer 6b and heading for a rear end side as heading for an outer periphery side while curving a projecting curve in view of a direction facing the cutting face 4.

Description

  The present invention relates to a drill suitable for use in drilling a workpiece made of fiber reinforced plastic (FRP) such as carbon fiber reinforced plastic (CFRP).

  When drilling a through-hole by drilling a workpiece made of such fiber-reinforced plastic, the through-hole is opened without cutting the reinforcing fiber such as carbon fiber especially when the through-hole is pulled out. The occurrence of so-called uncut fibers, which are pushed out from the periphery of the part in the penetrating direction and generate burrs, is a problem. In addition, so-called delamination, in which the layer on the penetration direction side of the fiber reinforced plastics laminated in layers, is also a problem.

  Therefore, Patent Document 1 and the like include a first cutting edge having a first tip angle and a second cutting blade formed continuously from the first cutting edge and smaller than the first tip angle. A drill with a two-stage tip angle provided is described. Similarly, Patent Document 2 describes a drill having two stages of tip angles of cutting edges in order to suppress the occurrence of burrs.

JP 2010-017817 A JP 2001-328016 A

  However, in the drills described in these Patent Documents 1 and 2, the first cutting edge having a large tip angle and the second cutting blade having a small tip angle are continuous as described above. The portion where the two cutting edges continuously intersect protrudes with an angle toward the outer periphery of the tip of the drill body. For this reason, the flank wear at the portion where the first and second cutting edges intersect increases, and it is necessary to re-grind frequently, and as a result, the drill life is shortened. There was a risk.

  The present invention has been made under such a background. In particular, even when drilling a fiber reinforced plastic such as a carbon fiber reinforced plastic, the flank face is prevented while preventing the occurrence of uncut fibers and delamination. An object of the present invention is to provide a long-life drill capable of suppressing wear.

  In order to solve the above problems and achieve such an object, according to the present invention, a chip discharge groove is formed on the outer periphery of the tip of the drill body rotated about the axis, and the drill rotation direction of the chip discharge groove is changed. A drill having a cutting edge with a facing wall as a rake face formed at a tip of the drill body, wherein the cutting edge includes a main cutting edge portion located on a tip inner peripheral side of the drill body, and the main cutting edge. A chamfer portion that is located on the outer peripheral side of the rear end from the portion and has a tip angle smaller than the main cutting edge portion, and the rake face located between the main cutting edge portion and the chamfer portion. And a convex curve portion that is directed toward the rear end side toward the outer peripheral side while drawing a convex curve as viewed from the direction facing the.

  In the drill configured as described above, the outer peripheral side of the rear end of the cutting edge is a chamfer portion having a smaller tip angle than the main cutting edge portion on the inner peripheral side of the front end. In this chamfer portion, the cutting edge is the work material. The action of pressing the peripheral edge of the through-hole opening of the work material in the penetrating direction when exiting is reduced. Therefore, the reinforcing fibers at the periphery of the opening can be cut without being pushed out in the penetrating direction, and generation of uncut fibers and delamination can be prevented. Also, in the convex curve portion, the action of pressing the peripheral edge of the through hole opening gradually decreases from the main cutting edge portion toward the chamfer portion side, so that uncut fibers and delamination can be prevented more reliably. it can.

  And, between these main cutting edge part and chamfer part is provided with a convex curve part toward the rear end side toward the outer peripheral side while drawing a convex curve as seen from the direction facing the rake face, Compared with the case where the first and second cutting blades continuously intersect like the drill described in Patent Documents 1 and 2, projecting toward the outer periphery of the tip of the drill body in an angle toward the outer periphery of the tip of the drill body. Since it can be kept small, flank wear can be suppressed.

  Here, the main cutting edge portion forms the main portion of the through hole in the work material by being sent out to the tip end side in the axial direction while the drill body is rotated around its axis, and its clearance angle Is preferably set large. On the other hand, if the clearance angle equivalent to the main cutting edge part is given to the chamfer part, for example, the tool angle may be reduced, leading to chipping or chipping. It is desirable to provide a smaller clearance angle.

  In such a case, in the convex curve portion, for example, the relief angle decreases continuously from the main cutting edge portion toward the chamfer portion, so that, for example, the convex curve portion from the chamfer portion. Compared to the case where a constant small clearance angle is given over the whole, the cutting resistance on the main cutting edge side of the convex curve portion can be reduced, and the convex cutting portion can be reduced from the main cutting edge portion. Compared with the case where a certain large clearance angle is given over the whole, it is possible to ensure the cutting edge strength on the chamfer portion side of the convex curve portion and prevent the occurrence of chipping and chipping.

  As described above, according to the present invention, even when drilling a workpiece made of fiber reinforced plastic such as carbon fiber reinforced plastic, the tip angle located on the outer peripheral side of the rear end of the cutting blade is small. The chamfer part can prevent uncut fibers and delamination, and the convex curve part from the main cutting edge part to the chamfer part suppresses flank wear and extends the drill life. Is possible.

It is the side view seen from the direction which opposes the rake face of the drill body tip part which shows one embodiment of the present invention. It is a front view of embodiment shown in FIG. It is AA expanded sectional drawing in FIG. It is BB expanded sectional drawing in FIG. It is CC sectional drawing in FIG.

  1 to 5 show an embodiment of the present invention. In the present embodiment, the drill body 1 is formed of a hard material such as cemented carbide or high-speed tool steel, and the outer shape is substantially cylindrical with the axis O as the center, and the rear end portion not shown is the main spindle of the machine tool. 2 and a distal end portion as a cutting edge portion, and is rotated around the axis O in the drill rotation direction T shown in FIG. Drilling is performed to form a through hole in a work material made of fiber reinforced plastic such as reinforced plastic.

  In the cutting edge portion, a pair of chip discharge grooves 2 that are twisted toward the rear side in the drill rotation direction T around the axis O toward the rear end side from the front end of the drill body 1 toward the rear end side are symmetrical with respect to the axis O. A clearance angle extending along the chip discharge groove 2 with a constant short width from the outer peripheral edge of the wall surface facing the drill rotation direction T of the chip discharge groove 2 is given to the outer peripheral surface of the cutting blade portion. No margin part 3 is formed. However, the margin portion 3 is provided with a back taper so that the diameter thereof is slightly reduced toward the rear end side in the axis O direction.

  Further, at the tip of the chip discharge groove 2, the wall surface facing the drill rotation direction T is a rake surface 4. In the present embodiment, thinning is applied from the inner peripheral portion of the rake face 4 to the wall surface facing the drill rotation direction T rear side of the tip of the chip discharge groove 2, and the inner peripheral portion of the rake face 4 is A thinning surface 4a is formed so as to extend toward the axis O as it goes toward the inner peripheral side of the drill body 1.

  Furthermore, a tip flank 5 is formed on the tip surface of the cutting edge portion, that is, the tip surface of the drill body 1, which intersects the rake face 4 and continues to the rear side in the drill rotation direction T of the chip discharge groove 2. A cutting edge 6 is formed at the intersecting ridge line portion between the tip flank 5 and the rake face 4. The tip flank 5 extends toward the rear end side in the axis O direction toward the rear side of the drill rotation direction T to give a clearance angle, and also toward the rear end side in the axis O direction toward the outer peripheral side of the drill body 1. The cutting edge 6 is given a tip angle.

  And the cutting edge 6 is located on the outer peripheral side of the rear end of the main cutting edge 6a and the main cutting edge 6a located on the inner peripheral side of the tip of the drill body 1, and the leading edge angle αa of the main cutting edge 6a. A chamfer portion 6b having a smaller tip angle αb and a position between the main cutting edge portion 6a and the chamfer portion 6b, as viewed from the direction facing the rake face 4 as shown in FIG. And a convex curve portion 6c directed toward the rear end side toward the outer peripheral side while drawing a convex curve. Further, in the present embodiment, from the main cutting edge portion 6a extending toward the axis O, located further on the inner peripheral side of the main cutting edge portion 6a, at the intersecting ridge line portion between the thinning surface 4a and the tip flank surface 5. A thinning blade portion 6d having a larger tip angle is formed.

  In the present embodiment, the main cutting edge portion 6a and the chamfer portion 6b extend linearly when viewed from the direction facing the rake face 4, and the convex curve portion 6c has the main cutting edge portion 6a and the chamfer portion 6b. For example, it is formed in a convex arc shape in contact with. Accordingly, the tip angle of the convex curve portion 6c is continuously decreased from the tip angle αa equal to the main cutting edge portion 6a at the contact point with the main cutting edge portion 6a toward the outer periphery of the rear end along the convex curve portion 6c. Thus, the tip angle αb is equal to that of the chamfer portion 6b at the contact point with the chamfer portion 6b.

  Further, as shown in FIGS. 3 to 5, the clearance angle of the cutting blade 6 is such that the clearance angle βb of the chamfer portion 6b is smaller than the clearance angle βa of the main cutting edge portion 6a, and the convex curve portion 6c. The clearance angle βc is continuously reduced between the clearance angles βa and βb from the main cutting edge portion 6a toward the chamfer portion 6b. In the present embodiment, the clearance angle βc of the convex curve portion 6c is made equal to the clearance angle βa at the contact point with the main cutting edge portion 6a of the convex curve portion 6c, and the clearance angle βb at the contact point with the chamfer portion 6b. Are equal. Further, the clearance angle βa of the main cutting edge portion 6a is, for example, 10 °, and the clearance angle βb of the chamfer portion 6b is, for example, 5 °.

  In the present embodiment, of the main cutting edge portion 6a, chamfer portion 6b, and convex curve portion 6c of the cutting edge 6, the main cutting edge portion 6a has the longest cutting edge length, and then the convex shape. The length of the curved portion 6c along the convex curve is long, and the length of the chamfer portion 6b is the shortest. Further, the leading flank 5 of the main cutting edge 6a, the convex curve 6c, and the thinning blading 6d are a first flank 5a continuous with the cutting edge 6, and a drill rotation direction T rear side of the first flank 5a. 3 and FIG. 4, the clearance angles βa and βc of the main cutting edge portion 6a and the convex curve portion 6c are shown in FIG. 3 and FIG. As shown, the clearance angle of the first flank 5a. Furthermore, the flank 5 of the chamfer portion 6 b is connected to the margin portion 3.

  In the drill having such a configuration, the chamfer portion 6b having a tip angle αb smaller than the tip angle αa of the main cutting edge portion 6a on the tip inner peripheral side is formed on the outer peripheral side of the rear end of the cutting blade 6, and carbon When a through hole is formed in a work material made of fiber reinforced plastic such as fiber reinforced plastic, when the through hole is pulled out, the chamfer portion is sent to the front end side in the axis O direction while cutting the periphery of the opening. The action of 6b pressing the work material in the penetration direction can be kept small.

  Also, in the convex curve portion 6c located between the main cutting edge portion 6a and the chamfer portion 6b, the tip angle becomes smaller toward the outer peripheral side, so the action of pressing the work material in the penetration direction is also small. Become. Therefore, according to the drill having the above-described configuration, it is possible to prevent the reinforcing fibers such as the carbon fibers in the work material at the periphery of the opening from being pushed out in the penetrating direction due to the action of the work material, thereby forming a burr. It is possible to prevent the occurrence of uncut fibers by forming through holes while cutting the reinforcing fibers reliably. In addition, so-called delamination, in which the layer in the penetration direction of the fiber reinforced plastics laminated in layers can be prevented.

  Further, in the drill having the above-described configuration, a convex curve is drawn between the main cutting edge portion 6a and the chamfer portion 6b as viewed from the direction facing the rake face 4, and the rear end side is directed toward the outer peripheral side. A convex curve portion 6c is formed. For example, the cutting blade 6 toward the outer peripheral side of the tip end of the drill body 1 is compared with the case where the main cutting blade portion 6a and the chamfer portion 6b are extended and intersected as they are. Can be reduced.

  For this reason, according to the drill having the above-described configuration, the flank wear of the tip flank 5 connected to the cutting edge 6 protruding to the outer periphery of the tip can be suppressed, and the flank wear on the tip flank 5 is caused by such flank wear. A long-life drill can be provided by preventing frequent re-grinding and concomitant shortening of the drill life. Therefore, it is possible to perform a stable drilling process over a long period of time on a work material such as the carbon fiber reinforced plastic.

  In the present embodiment, the chamfer portion 6b is given a clearance angle βb smaller than the clearance angle βa of the main cutting edge portion 6a, and the cutting angle of the cutting blade 6 in the chamfer portion 6b is secured. The blade strength can be improved, and chipping and chipping can be prevented to further improve the drill life. Conversely, the main cutting edge portion 6a is given a clearance angle βa larger than the clearance angle βb of the chamfer portion 6b, so that the bottom surface of the processed hole during drilling and the tip clearance of the main cutting edge portion 6a are provided. Interference with the surface 5 can be prevented, cutting resistance can be reduced, and flank wear of the tip flank 5 connected to the main cutting edge 6a can be suppressed.

  Further, in the present embodiment, the clearance angle βc in the convex curve portion 6c between the main cutting edge portion 6a and the chamfer portion 6b is continuously reduced from the main cutting edge portion 6a toward the chamfer portion 6b. Has been. For this reason, for example, compared with the case where the relief angle βc of the convex curve portion 6c is constant at a small relief angle βb equal to the chamfer portion 6b, the relief angle βc is particularly large on the main cutting edge portion 6a side of the convex curve portion 6c. Insufficient cutting resistance can be prevented and flank wear can be prevented from being promoted, and stable and smooth drilling can be performed.

  Further, for example, compared with a case where the relief angle βc of the convex curve portion 6c is constant at a large relief angle βa equal to the main cutting edge portion 6a, the blade angle becomes small particularly on the chamfer portion 6b side of the convex curve portion 6c, There is a risk of chipping and chipping. That is, according to the present embodiment, by reducing the clearance angle βc of the convex curve portion 6c from the main cutting edge portion 6a toward the chamfer portion 6b, the cutting resistance is reduced on the main cutting edge portion 6a side. The flank wear is suppressed, and the chamfer 6b side can secure the cutting edge strength to prevent chipping and chipping, and can provide stable drilling and a long-life drill. It becomes possible.

  Moreover, in the present embodiment, the relief angle βc of the convex curve portion 6c is made equal to the relief angle βa at the contact point with the main cutting edge portion 6a of the convex curve portion 6c, and the chamfer portion 6b of the convex curve portion 6c. Is set equal to the clearance angle βb, and the clearance angle of the cutting edge 6 (the clearance angle of the first clearance surface 5a) does not become discontinuous along the cutting edge 6. Therefore, it is possible to prevent the flank wear from being promoted at the portion where the clearance angle is discontinuous in this way.

  Further, in the present embodiment, the convex curve portion 6c is formed so as to contact the main cutting edge portion 6a and the chamfer portion 6b when viewed from the direction facing the rake face 4. For this reason, since there is no portion that is bent at an angle in the cutting edge 6 from the main cutting edge portion 6a to the chamfer portion 6b, stress due to cutting resistance concentrates on such a portion and chipping or It is also possible to prevent defects from occurring.

  However, since the convex curve portion 6c is directed toward the rear end side toward the outer peripheral side while drawing a convex curve when viewed from the direction facing the rake face 4, the angle with the main cutting edge portion 6a and the chamfer portion 6b Even if it intersects so as to bend, the intersection angle becomes a large obtuse angle. For this reason, the convex curve portion 6c may intersect with at least one of the main cutting edge portion 6a and the chamfer portion 6b so as to bend at an angle.

DESCRIPTION OF SYMBOLS 1 Drill main body 2 Chip discharge groove 3 Margin part 4 Rake face 4a Thinning surface 5 Tip flank 6 Cutting edge 6a Main cutting edge part 6b Chamfer part 6c Convex curve part 6d Thinning edge part O Drill body 1 axis T Drill rotation direction αa Tip angle of main cutting edge portion 6a αb Tip angle of chamfer portion 6b βa Clearance angle of main cutting edge portion 6a βb Clearance angle of chamfer portion 6b βc Clearance angle of convex curve portion 6c

Claims (2)

  A drill in which a chip discharge groove is formed on the outer periphery of the tip of the drill body rotated about the axis, and a cutting blade whose rake face is a wall facing the drill rotation direction of the chip discharge groove is formed at the tip of the drill body. The cutting edge includes a main cutting edge portion located on the inner peripheral side of the tip of the drill body, and a tip angle smaller than the main cutting edge portion located on the outer peripheral side of the rear end of the main cutting edge portion. Is located between the main cutting edge portion and the chamfer portion, and draws a convex curve as viewed from the direction facing the rake face toward the outer peripheral side toward the rear end side. A drill characterized by having a convex curve section facing.   The chamfer portion is given a clearance angle smaller than that of the main cutting edge portion. In the convex curve portion, the clearance angle is continuously reduced from the main cutting edge portion toward the chamfer portion. The drill according to claim 1, wherein:

Images