JP2013075339A - Drill for machining laminated board of frp and metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drill for machining a laminated board of FRP and metal, which has achieved life-improved and high quality drilling.SOLUTION: In a twist drill having a thinned portion 3 and a cutting edge 2 an outer diameter side of which is more gently bent concavely in a front view than the thinned portion, a margin 6 formed on an edge forward of a drill rotation direction of land part 5 is made into a right-angled margin rising up at a right angle from the land part 5 and in parallel with a groove surface of torsional groove 4 along the margin. Moreover, the width W of the margin is set to 0.3-0.6 mm.

Description

  The present invention relates to a drill suitable for processing an FRP (fiber reinforced plastics) and metal laminate.

  In recent years, FRP, especially CFRP (carbon fiber reinforced plastics), has attracted particular attention as a structural material for aircraft fuselage and wings. This CFRP may be provided as a composite plate material by combining metals such as titanium and aluminum.

  As the composite plate material, a material in which a metal is stacked on one surface of CFRP (hereinafter simply referred to as a stacked plate) is used. For example, when forming the fuselage or wing of an airplane, it is necessary to make a hole through which a fastening material such as a bolt or a rivet passes.

  For the drilling, a standard blade type solid drill is used. The standard blade shape is a shape in which the ridgeline at the position where the groove surface of the torsional groove intersects the flank surface of the tip is a cutting edge, and a thinning part is provided at the center of rotation to reduce the core thickness of the tip. say.

  For drilling a single FRP material, a drill as disclosed in Patent Document 1 below is also provided. In the drill of the same document, the tip angle is continuously decreased from the rotation center to the outer diameter so as to be 0 ° at the outermost diameter, and the clearance angle of the cutting edge is further decreased from the rotation center. It continuously decreases toward the diameter.

  The following Patent Document 2 shows an embodiment of a drill to which the present invention is applied. This drill is referred to as a blade replacement type, and has a detachable cutting head at the tip of the main body, and a cutting blade and a tip side of a twist groove are formed on the cutting head.

JP 2008-36759 A JP 2003-136319 A

  The above-mentioned standard blade type solid drill has a short life in the use for punching a laminated plate. Since the work material is a laminated plate of CFRP and metal, it is basically difficult to adopt a hard coat coat used for improving wear resistance, and it is inevitable that the life will be shortened.

  In addition, the margin width increases as the margin wears. For this reason, especially in CFRP processing, where margin wear is likely to occur, the friction area increases due to margin wear, and wear is further promoted, resulting in reduced life, burned hole surfaces due to frictional heat, metal welding, etc. The problem is likely to occur.

  On the other hand, the drill of Patent Document 1 is suitable for drilling a single FRP material because the thrust load is reduced toward the outer diameter side, but in the case of a composite material in which metals are stacked, it is processed into a metal layer. Cylindrical burrs are likely to occur at the outlet of the hole, and it is difficult to make a hole that satisfies the required quality.

  The document also describes that margins are provided on both edges along the twisted groove of the land portion (so-called double margin). In the double margin, the work material is a laminated plate of CFRP and metal. As a result, the burned surface of the processed hole and metal welding are more likely to occur.

  An object of the present invention is to provide a drill for processing FRP and metal stacks that achieves improved life and high-quality drilling as a solution to the above problems.

  In order to solve the above problems, in the present invention, a twist drill having a thinning portion for reducing the core thickness and a cutting blade whose outer diameter side is gently bent into a concave shape in front view of the drill from the thinning portion is described below. Configured as follows. That is, the margin formed at the front edge in the drill rotation direction of the land portion is a right-angled margin that rises at right angles from the land portion and parallel to the groove surface of the torsion groove along the margin. It set to 3 mm-0.6 mm.

  This drill preferably has a reinforced treatment on the outer diameter side of the cutting edge. On the rake face (groove face of the torsion groove) on the outer diameter side of the cutting edge, a return face parallel to the axis of the center of the drill that makes the torsion angle of the face 0 ° is processed and strengthened.

  In addition, when the present invention is applied to a blade-tip-exchangeable drill as disclosed in the above-mentioned Patent Document 2, the effectiveness thereof is more significantly exhibited, which is preferable.

  In the drill of the present invention, since the margin is a right-angle margin, the margin width does not change even if the margin is worn, and the friction surface does not increase due to the margin wear. In addition, since the margin is a single margin and the width of the margin is 0.3 mm to 0.6 mm, which is smaller than the standard design, the friction area during processing is reduced, resulting in a reduction in life due to the promotion of friction and processing. Hole surface burns and metal welding are less likely to occur.

The side view which shows the principal part of the 1st form of the drill of this invention End view of the tip side of the drill of FIG. 1 is an enlarged side view of the drill of FIG. 1 as viewed in the direction of arrow III in FIG. Side view showing the main part of the second embodiment of the drill of the present invention End view of the tip side of the cutting head of the drill of FIG. 4 is a side view showing the drill of FIG. 4 with the cutting head removed. Side view showing the main part of the third embodiment of the drill of the present invention An enlarged side view of the drill of FIG. 7 as viewed in the direction of arrow III in FIG.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a stacked plate machining drill according to the present invention will be described below with reference to FIGS. 1 to 3 show an example in which the present invention is applied to a solid drill. This drill is composed of two cutting edges 2, 2 having a centrally symmetric shape at the tip of a drill body 1 made of cemented carbide or the like, and two thinning portions 3 arranged at a centrally symmetric position for reducing the core thickness. , 3.

  Further, two twisted grooves 4, 4 are provided on the outer periphery of the drill body 1, and further, margins 6, 6 are provided at the drill rotation direction front edges of the two land portions 5, 5, respectively.

  The cutting edge 2 has a small chisel edge that does not clearly appear in the drawing at the center of the tip. The part excluding the chisel edge is composed of a ridge line at a position where the rake face 7 (groove face of the twisted groove 4) and the flank 8 at the tip intersect, and a ridge line at a position where the surface of the thinning part and the flank 8 intersect. The outer diameter side of the thinning part 3 is a blade that is gently bent into a concave shape when viewed from the front of the drill.

  The amount of dent in the concave portion of the cutting edge is about 0.01 to 0.03D as a ratio to the diameter D when the drill diameter is D.

  The one provided with the bent cutting edge has a function of slightly curling the chips, improving the performance of the chip processing and making it difficult for the chips to be rubbed against the surface of the hole processed in the work material. Further, since the curling force is applied to the chips, the chips are processed without applying stress.

  Since the cutting edge 2 is preferably a sharp edge in the cutting of CFRP or GFRP, the cutting edge 2 is maintained in a sharp state even when performing a honing process on the cutting edge.

  The tip angle of the drill is set to 125 ° to 135 °, which is slightly larger than the tip angle of a general metal working drill (120 ° is common). By selecting the tip angle within this range, it is possible to stabilize the biting behavior with respect to the prepared hole when processing a laminated plate with prepared holes.

  The twist groove 4 has a twist angle of about 10 ° to 30 °.

  The margin 6 is a margin that rises at a right angle from the land portion 5. Further, the surface rising from the land portion 5 is a surface parallel to the groove surface of the twisted groove 4 so that the margin width is constant in the entire height direction (radial direction) of the margin. Further, the width W of the margin (see FIG. 2) is set to 0.3 mm to 0.6 mm to reduce the contact area with the work material.

  As explained earlier, the margin width W is made smaller than the standard design to reduce the friction area during processing, such as reduced life due to the acceleration of friction, burned hole surface, metal welding, etc. Suppression can be achieved.

  In addition, the flank 8 has a rake face of 3 rakes, and the front flank angle γ (see FIG. 3) of the flank is about 14 ° to 15 °, which is more easily deformed by CFRP than metal. No. 2 is unlikely to occur even during processing. This is effective for suppressing wear on the flank face in FRP processing.

  4-6 has shown the example which applied this invention to the blade-tip-exchange-type drill. This drill is provided in a cutting head 10 in which a cutting edge 2, a thinning portion 3, a tip end side of a torsion groove 4 and a land portion 5, and a margin 6 are made independent of the drill main body 1, and the cutting head 10 is provided in the drill main body 1. Removably attached to the tip of the.

  The drill body 1 is not provided with a margin 6. Further, a back taper is attached to the outer periphery of the cutting head 10. The back taper is set in a range of 1.0 to 1.2 mm / 100 mm (gradient per 100 mm length is 1.0 to 1.2 mm). The value is very large as a back taper of a drill, and is a numerical value that cannot be set in terms of manufacturing in a solid drill.

  By attaching a back taper only to the cutting head 10, such a numerical value of the back taper can be set. The large back taper has an effect of suppressing heat generation that adversely affects the work material in the CFRP processing.

  The cutting head 10 is attached to the drill body 1 by using two fastening bolts (not shown). The cutting head 10 and the drill body 1 are provided with radial serrations 9 on their abutting surfaces, and the serrations 9 mesh with each other to produce a centripetal effect and a detent effect, but other fastening structures are employed. May be.

  FIGS. 7 and 8 show the rake face on the outer peripheral side of the tip subjected to front-return processing for reinforcing the cutting edge. A return surface 11 is formed on the outer diameter side of the tip of the twisted groove 4 to return the twist of the groove so that a part of the groove surface (rake surface) is parallel to the axis of the drill. The outer diameter side of the cutting edge 2 is reinforced.

  The drill of this invention has a sharp cutting edge because the front clearance angle γ of the most flank is set to be large. The sharp cutting edge is a laminating plate as defined in the present invention, and when a pilot hole is formed in advance in the punched portion of the plate, the cutting edge is lost due to load fluctuation when it bites into the metal layer. Easy to do.

  The installation of the return surface 11 is effective as a countermeasure against the loss. The cutting edge can be strengthened by negative land processing or honing treatment, but with these methods, the sharpness is dull and delamination (delamination, CFRP separation or CFRP and metal separation) occurs at the CFRP hole exit. It becomes easy to do. Compared with these methods, the strengthening by the return surface 11 makes it easy to suppress blunting of the cutting edge, and it is possible to achieve both the maintenance of the sharpness of the edge and the enhancement of the cutting edge strength. The cutting edge strengthening measure by installing the return surface 11 can also be applied to a solid drill.

  The blade tip type drill has a smaller number of re-polishing operations than the solid drill for regrinding, but has the advantage that the cutting blade damaged by replacing only the cutting head can be easily and quickly regenerated.

  In addition, this cutting edge-replaceable drill can attach a large back taper to the cutting head, and a margin can be formed only in the cutting head, so that friction with the work material can be reduced and machining can be performed. It is easy to improve the quality of holes.

  In addition, there is less loss of tool material costs compared to solid drills and it is economical, and the drill head can be replaced with a cutting machine or hand drill to improve drilling efficiency. Can contribute.

  Therefore, the present invention can be expected to have a better effect when applied to a blade tip type drill. Further, the problem of wear of the cutting edge, burning of the hole surface due to heat generation, and metal welding is particularly noticeable in the CFRP laminated plate, but FRP contained in the work material is GFRP (glass fiber reinforced plastics), etc. Therefore, the present invention is also effective in processing a GFRP laminated plate.

  In the drill according to the present invention, the blade type applies a certain amount of thrust load to the work material. However, it is rather difficult to form a cylindrical burr at the exit of the hole that is processed into metal by working better.

  In addition, in drilling a single FRP material, it is said that a tool with a thrust load is not preferable because it easily causes delamination during processing. Since the thrust load can be received by the metal layer by processing with the layer facing down, a hole that satisfies the required quality can be formed even with a blade mold that does not reduce the thrust load so much.

DESCRIPTION OF SYMBOLS 1 Drill body 2 Cutting edge 3 Thinning part 4 Torsion groove 5 Land part 6 Margin 7 Rake face 8 Relief face 9 Serration 10 Cutting head 11 Return face

Claims (3)

  A twist drill having a thinning portion (3) for reducing the core thickness and a cutting edge (2) whose outer diameter side is gently bent into a concave shape with respect to the thinning portion when viewed from the front of the drill, The margin (6) formed at the front edge of the drill rotation direction is a right-angled margin that rises at a right angle from the land and parallel to the groove surface of the torsion groove (4) along the margin, and further, the margin width (W ) Drills for processing FRP and metal stacks set to 0.3 mm to 0.6 mm.   The outer diameter side of the cutting edge (2) is reinforced by machining a return surface (11) parallel to the axis of the center of the drill that makes the twist angle of the surface 0 ° on the rake face of the part. Drill for processing FRP and metal laminates described in 1.   A cutting head (10) having a cutting edge (2), a thinning portion (3), a tip side of a torsion groove (4) and a land portion (5), and a margin (6); The drill for processing FRP and metal according to claim 1 or 2, wherein 10) is detachably attached to the tip of the drill body (1) and configured as a blade-tip exchange drill.

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