JP2014037008A - Boring drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boring drill capable of boring a highly precise through hole from a first relatively soft layer into a plate having the first layer and a second relatively hard layer laminated on each other.SOLUTION: A boring drill is formed of a stepped shaft having a diametrically smaller portion formed at the leading end of a body. A through hole H of a diameter of 5 to 13 mm is bored. A diametrically larger portion 22 is formed to have a diameter larger by 0.3 to 2.0 mm than a diametrically smaller portion 21. A stepped portion 23 between the diametrically smaller portion 21 and the diametrically larger portion 22 is formed such that a taper portion comes closer at an angle of 175 to 180 degrees toward the leading end side. The individual axial lengths of the diametrically smaller portion 21 and the diametrically larger portion 22 are made longer than the axial length of the bored through hole H. The torsion angles of the grooves of the diametrically smaller portion 21 and the diametrically larger portion 22 are 15 to 45 degrees.

Description

  The present invention belongs to a technical field related to a drill for drilling a through hole in a plate material made of a composite material in which different materials are laminated.

  Recently, many kinds of plate materials made of composite materials in which different materials are laminated have been provided in order to improve strength and lightness. When the plate material made of such a composite material is formed by laminating a relatively soft first layer and a relatively hard second layer, a bolt is drilled from the first layer side with a drill for drilling. If a through-hole for insertion such as a rivet is drilled, the inner peripheral surface of the through-hole in the first layer is damaged by the chips in the second layer, so that a highly accurate through-hole cannot be machined. There is a problem.

  For example, in a plate material in which the first layer provided as an aircraft material is a fiber reinforced synthetic resin material and the second layer is made of a titanium metal material, the titanium metal material is rich in malleability, ductility, and viscosity. Due to the characteristics of high long strength, the inner peripheral surface of the through hole of the first layer is formed by continuously cutting in the spiral shape (curl shape) without breaking the chips of the second layer with the drilling of the drill for drilling. The phenomenon of rubbing strongly occurs.

  For this reason, there is a development of a technique capable of machining a through hole with high accuracy from the first layer side on a plate material in which a relatively soft first layer and a relatively hard second layer are laminated. Although it is expected, improvement of the drilling technique by the drill for drilling which has been frequently used so far is demanded.

  Conventionally, as a drill for drilling, the thing of patent documents 1, 2 is known, for example.

  Patent Documents 1 and 2 describe a step-drilling drill having a small-diameter portion having a small diameter at the tip of the body.

  The drills for drilling according to Patent Literatures 1 and 2 are accurate by removing burrs on the outlet side of the through hole, using the small diameter part at the front end of the body for roughing and the large diameter part having a large rear end diameter for finishing. A high through hole is drilled.

Japanese Utility Model Publication No. 1-99517 JP 2001-54810 A

  In the drill for drilling according to Patent Documents 1 and 2, although effective for removing burrs on the outlet side of the through hole, the relatively soft first layer and the relatively hard second layer are laminated. To prevent the inner peripheral surface of the through hole of the first layer from being damaged by the chips of the second layer when a highly accurate through hole is drilled from the first layer side in the plate material There is a problem that can not be.

  The present inventor prevents damage to the inner peripheral surface of the through hole of the first layer with the chips of the second layer from the research on the drill with a stepped shape for solving this problem. A threshold specific could be obtained.

  The present invention has been made on the basis of such research, and the accuracy of the first layer side from the first layer side on the plate material in which the relatively soft first layer and the relatively hard second layer are laminated. It is an object of the present invention to provide a drill for drilling capable of drilling high through holes.

  In order to solve the above-described problems, the drill for drilling according to the present invention employs means described in each of the claims.

  That is, according to the first aspect, in the step-shaped drill for drilling having a small-diameter portion having a small diameter at the tip of the body, the relatively soft first layer and the relatively hard second layer are laminated. This is used when a through-hole having a diameter of 5 to 13 mm is drilled from the first layer side in the formed plate material, and the large-diameter portion having a large diameter at the rear end of the body has a diameter of 0.3 than the small-diameter portion. ~ 2.0mm larger, the step part of the small diameter part and the large diameter part is formed in a tapered shape having an angle of 175 to 180 degrees and approaching the tip side, and each of the small diameter part and the large diameter part The axial length is longer than the axial length of the through-hole to be drilled, and the twist angle of the groove of the small diameter portion and the large diameter portion is 15 to 45 degrees.

  With this means, it was confirmed that the setting of each threshold value significantly prevented the second layer of chips from damaging the inner peripheral surface of the through hole of the first layer.

  According to a second aspect of the present invention, in the drill for drilling according to the first aspect, the first layer of the plate material is made of a fiber-reinforced synthetic resin material, and the second layer of the plate material is made of a titanium metal material.

  In this means, the first layer and the second layer of the plate material are specifically specified.

  According to a third aspect of the present invention, in the drill for drilling according to the second aspect, the first layer of the plate material is made of a carbon fiber reinforced synthetic resin material, and the second layer of the plate material is made of a titanium alloy containing aluminum and vanadium. It is characterized by.

  In this means, the first layer and the second layer of the plate material are more specifically specified.

  In the drill for drilling according to the present invention, it was confirmed that the inner peripheral surface of the through hole of the first layer was significantly prevented from being damaged by the chips of the second layer by setting each threshold value. There is an effect that a highly accurate through-hole can be drilled from the first layer side in the plate material in which the relatively soft first layer and the relatively hard second layer are laminated.

  Furthermore, as claimed in claim 2, the first layer and the second layer of the plate material are specifically specified, and there is an effect that a highly accurate through-hole can be drilled also for the plate material made of this specific material. .

  Furthermore, as claimed in claim 3, the first layer and the second layer of the plate material are more specifically specified, and an effect that the through-hole with high accuracy can be drilled also for the plate material made of this more specific material. There is.

It is a side view of the form for implementing the drill for a drilling which concerns on this invention. It is a top view which shows the drilling process of FIG. It is a graph explaining the chip outflow angle in the drilling work of FIG.

  EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the drill for drilling which concerns on this invention is demonstrated based on drawing.

  In this embodiment, as shown in FIG. 1, a body 2 in which a stepped blade groove is formed at the tip of a shank 1 is shown.

  As shown in FIG. 1, the plate material P to be drilled by this form includes a first layer Pa made of a relatively soft fiber-reinforced synthetic resin material and a relatively hard titanium-based metal material. And a second layer Pb made of And this form demonstrates effectiveness, when the through-hole H whose diameter b is 5-13 mm is drilled from the 1st layer Pa side of the board | plate material P to the plate | board thickness a direction. The diameter b of the through hole H is a size normally required for insertion of bolts, rivets and the like in the aircraft industry and precision equipment industry.

  The body 2 of this form is provided with a small diameter portion 21 having a small diameter (diameter) c at the front end and a large diameter portion 22 having a large diameter (diameter) d at the rear end. A tapered step portion 23 is provided therebetween. The grooves (blades) formed in the small diameter portion 21 and the large diameter portion 22 are continuous with a twist angle (rake angle) θ1 set to 15 to 45 degrees.

  The small-diameter portion 21 has a distal end angle θ2 set to 100 to 140 degrees and an axial length e set to be longer than the plate thickness a of the plate material P.

  The large diameter portion 22 is set such that the axial length f is longer than the plate thickness a of the plate material P, and the diameter d is set 0.3 to 2.0 mm larger than the diameter c of the small diameter portion 21. Incidentally, the diameter d coincides with the diameter b of the through hole H.

  The step portion 23 is formed in a tapered shape that is close to the distal end side, and a wedge angle θ3 that is a taper angle is set to 175 to 180 degrees.

  In the perforation according to this form, the plate material P is perforated in the thickness a direction from the first layer Pa side. At this time, as shown in FIG. 2, a relatively large volume W of the plate material P is cut by the small diameter portion 21 to punch a raw hole (lower hole) h, and subsequently, the large diameter portion 22 relatively small the plate material P. The volume W is cut and the through hole H is drilled. That is, like the drill for drilling according to Patent Documents 1 and 2 described above, the small diameter portion 21 functions for rough machining, and the large diameter portion 23 functions for finishing.

  In the perforation by the small diameter portion 21, the so-called biting to the plate material P becomes good by setting the tip angle θ2 to 100 to 140 degrees. When the tip angle θ2 is less than 100 degrees, the axial length of the tool (small diameter portion 21) becomes long, and when the tip angle θ2 exceeds 140 degrees, the bite of the small diameter portion 21 to the plate material P is poor. Become.

The chips formed by the large diameter portion 22 are guided in a direction parallel to the axis L of the through hole H (body 2) by a twist angle θ1 set to 15 to 45 degrees. Therefore, the chips are formed in a straight line that is somewhat curved without being spiral. If the twist angle θ1 is less than 15 degrees, the cutting resistance of the cutting edge of the stepped portion 23 increases, and if the twist angle θ1 exceeds 45 degrees, the chips are guided in a direction perpendicular to the axis L and become spiral. I'll do it.

  Chips formed by the large diameter portion 22 are guided in a direction parallel to the axis L at the step portion 23 in which the wedge angle θ3 is set to 175 to 180 degrees. As shown in FIG. 3, when a calculation graph is created in which the horizontal axis is the wedge angle θ3 and the vertical axis is the chip discharge angle (angle relative to the axis L), the wedge angle θ3 is preferably 175 to 180 degrees. It is understood. When the wedge angle θ3 exceeds 180 degrees, wear of the tool (the cutting edge of the stepped portion 23) becomes severe.

  The chips that have passed through the step portion 23 are guided in a direction parallel to the axis L at the large diameter portion 22. At this time, the diameter d of the large-diameter portion 22 is set to be 0.3 to 2.0 mm larger than the diameter c of the small-diameter portion 21, so that cutting as finishing is reliably performed. When the diameter d of the large-diameter portion 22 is less than 0.3 mm with respect to the diameter c of the small-diameter portion 21, the first layer Pa, which is the soft material of the plate material P, has a small diameter portion 21. Damage due to scratching with spiral chips generated from the second layer Pb expands outside the diameter b of the through hole H, and effective cutting cannot be expected, and the diameter d of the large diameter portion 22 is smaller than that of the small diameter portion 21. When the size is larger than 2.0 mm with respect to the diameter c, only normal cutting function can be expected instead of cutting as finishing.

  As a result, the chips generated from the second layer Pb of the plate material P are not spiraled but are formed in a slightly curved straight line and are discharged to the surface of the first layer Pa in a manner that follows the groove of the body 2. Will be. For this reason, the inner peripheral surface of the through hole H of the first layer Pa is not rubbed and damaged by the chips generated from the hard second layer Pb of the plate material P. As a result, damage to the resin-processed surface caused by hard titanium alloy chips is reduced, and high-efficiency, high-quality drilling in one process is possible.

  About the form for implementing the drill for drilling concerning the above-mentioned this invention, the carbon fiber reinforced synthetic resin material (CFRP) of thickness 4mm is selected as the 1st layer Pa of the board | plate material P, and the 2nd layer of the board | plate material P is selected. An experiment was conducted in which a 4 mm thick titanium alloy (Ti-6Al-4V) containing aluminum (6%) and vanadium (4%) was selected as Pb, and a through hole H having a diameter b of 6 mm was drilled. .

  Note that drilling was performed under conditions of a cutting speed of 25 m / min or less and a feed of 0.1 mm / rev or less.

  The arithmetic average roughness (Ra) of the through holes H according to the experimental results was 2 μm or less.

  Since the arithmetic average roughness (Ra) when using a conventional drill for drilling is about 5 μm, the finishing accuracy is extremely high. Incidentally, the arithmetic average roughness (Ra) required in the aircraft industry that requires the highest accuracy is 5 μm or less.

  The drill for drilling according to the present invention can be applied to drilling through holes in a wide range of plate materials in which a relatively soft first layer and a relatively hard second layer are laminated.

2 Body 21 Small diameter portion 22 Large diameter portion 23 Step portion H Through hole P Plate material Pa First layer Pb Second layer a Plate thickness (of plate material)
b Diameter (through hole)
c, d diameter e, f axial length θ1 helix angle
θ3 wedge angle

Claims (3)

  In a step-shaped drill for drilling having a small-diameter portion having a small diameter at the tip of the body, a first member is formed on a plate material in which a relatively soft first layer and a relatively hard second layer are laminated. It is used when drilling through holes with a diameter of 5 to 13 mm from the layer side, and the large diameter part with a large diameter at the rear end of the body is formed 0.3 to 2.0 mm larger in diameter than the small diameter part. The step portion of the small diameter portion and the large diameter portion is formed in a tapered shape having an angle of 175 to 180 degrees and close to the tip side, and the axial length of each of the small diameter portion and the large diameter portion is perforated. A drill for drilling, characterized in that it is formed longer than the axial length of the through hole, and the twist angle of the groove between the small diameter portion and the large diameter portion is 15 to 45 degrees.   2. The drill for drilling according to claim 1, wherein the first layer of the plate material is made of a fiber reinforced synthetic resin material, and the second layer of the plate material is made of a titanium metal material.   3. The drill for drilling according to claim 2, wherein the first layer of the plate is made of a carbon fiber reinforced synthetic resin material, and the second layer of the plate is made of a titanium alloy containing aluminum and vanadium. .

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