JPH0957515A - Drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drill which can restrain abrasion of a drill main body, improve surface roughness of the inner circumference of a worked hole, remove a burr, and is suitable for the case of machining of FRP material and the like in particular. SOLUTION: In a drill in which the cutting edge 7 is formed on the crossing ridge line part of a wall 5a facing to the drill rotational direction side of the chip discharge groove 5 formed on the outer circumference of a drill main body and the flank on the extreme end of the drill main body 1, an abrasive grain layer 10 containing hard abrasive grains is formed at least extending over from the extreme end of the drill main body to the outer circumferential face. This abrasive grain layer 10 is an electrodeposition abrasive grain layer of which the main component is nickel binder containing super abrasive grains of grain size 50#-1000# as hard abrasive grains, and formed in the range from a point 11 positioning on the most base end side on the crossing ridge line of the flank on the extreme end and the outer circumferential face at least up to the range of the width W=1mm on the base end side in the direction of the axis O of drill main body, on the outer circumferential face of the drill main body.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a glass fiber reinforced plastic and a carbon fiber reinforced plastic (CFR).
The present invention relates to an optimum drill used for drilling such as P).

[0002]

2. Description of the Related Art This type of fiber reinforced plastic (FR
P) has many advantages that it is excellent in specific rigidity, specific strength, fatigue resistance, wear resistance, chemical resistance, vibration damping, etc., and it is currently used for daily goods to aerospace equipment. It is applied as a material in a wide range of fields. With the expansion of such application fields, it has been required for tools for processing such FRP materials to simultaneously satisfy high productivity and processing accuracy.

[0003]

However, this type of F
In the cutting process of RP material, since the material has high strength and wear resistance, there is a problem that the tool body is significantly worn on the cutting tool side and the life thereof is significantly shortened. Further, in particular, in the case of cutting such an FRP material, it is common that fine powdery chips are generated without continuously forming ribbon-like chips unlike the case of cutting a metal material. Is. However, such chips tend to stay inside the drilled holes, especially during drilling, and the chips are trapped between the drill body and the drilled holes, further promoting wear of the drill body. There is also a problem that the surface roughness of the inner circumference of the machined hole is deteriorated. In addition, such FR
In the drilling of P material, burrs are likely to occur at the opening of the machined hole, and if such burrs occur, it is necessary to scrape off the burrs after drilling, which complicates the machining work. This resulted in hindering the efficiency of processing.

The present invention has been made under such a background, and in particular, when drilling the FRP material,
An object of the present invention is to provide a drill capable of suppressing the shortening of the service life due to wear of the drill body, improving the surface roughness of the machined hole, and obtaining excellent workability with less burrs.

[0005]

In order to solve the above problems and to achieve the above object, the present invention relates to the outer periphery of a drill body rotated around an axis, and the axis line from the flank of the tip of the drill body. A drill in which a chip discharge groove extending toward the base end side in the direction is formed, and a cutting blade is formed at a ridge line intersecting a wall surface of the chip discharge groove facing the drill rotation direction side and the tip flank, at least the drill body. An abrasive grain layer containing hard abrasive grains is formed from the tip to the outer peripheral surface.

According to the drill having such a structure, an abrasive grain layer containing hard abrasive grains is formed from the flank of the tip of the drill body to the outer peripheral surface, and the hard abrasive grains of the abrasive grain layer form the abrasive grains of the drill body. Since wear is prevented, it is possible to prevent the life of the drill from being shortened even when drilling the FRP material. Further, since the inner circumference of the processed hole is ground by this abrasive grain layer, the surface roughness can be greatly improved. Moreover, burrs generated at the opening of the processed hole can be removed evenly in the process of drilling due to the grinding action of the abrasive grain layer.

Here, as the hard abrasive grains contained in the abrasive grain layer, so-called super-abrasive grains made of diamond or CBN are used, and the wear resistance of the drill body and the surface roughness of the machined hole are used. It is desirable for improvement. Further, in order to obtain a more excellent processed surface roughness, it is desirable that the grain size of the above-mentioned superabrasive grains is small, and it is desirable that the grain size is within the range of 50 # to 1000 #. Furthermore, in order to prevent the above-mentioned abrasive grains from falling off and peeling off the abrasive grain layer and to reliably achieve the above-mentioned effects, the above-mentioned abrasive grain layer should be an electrodeposition abrasive grain layer containing a nickel binder as a main component. Is desirable.

On the other hand, the wear of the drill body during drilling of the above FRP material is most remarkable at the tip of the drill body which comes into contact with the material at the time of machining. By forming the above-mentioned abrasive grain layer over the surface, promotion of such wear is prevented. However, the range of formation of the abrasive grain layer on this outer peripheral surface is at least 1 mm from the point closest to the base end side on the ridge line intersecting the tip flank and the outer peripheral surface to the base end side in the axial direction. It is sufficient to prevent the wear from occurring, and
The inner periphery of the machined hole formed by the cutting edge can be ground and burrs can be removed.

[0009]

1 to 4 show an embodiment in which the present invention is applied to a two-blade gun drill. In the present embodiment, as shown in FIG. 1, the drill body 1 is a cylindrical driver 2 that is mounted on a tool holding part of a machine tool and is rotated around an axis O of the drill body 1.
And a shaft-shaped shank 3 coaxially fitted in the central hole 2a of the driver 2, and a cutting blade tip 4 made of cemented carbide and fixed to the tip of the shank 3 by brazing. There is.

On the outer periphery of the drill body 1, there are two chips discharge grooves 5 and 5 which are open at the tip end surface of the cutting blade tip 4 and extend toward the base end side along the axial direction of the drill body 1. It is formed from the cutting blade tip 4 to the shank 3 so as to sandwich the axis O. Each of these chip discharge grooves 5, 5 has a wall surface 5a whose bottom surface faces the drill rotation direction (counterclockwise direction in FIG. 2) and a wall surface 5b which faces the rear side in the drill rotation direction. As shown in FIG. 2, the drill body 1 is formed in a substantially V-shape when viewed from the direction of the axis O from the tip side. Further, the wall surfaces 5a, 5a of the both chip discharge grooves 5, 5 and the wall surfaces 5b, 5b are formed to be parallel to each other.

On the other hand, the tip surface of the cutting edge tip 4 is provided with tip flanks 6 and 6 so as to extend from the tip end side opening of the chip discharge grooves 5 and 5 to the rear side in the drill rotation direction. There is. Here, in the present embodiment, the tip flank 6
Are the first and second flanks 6a which are continuous to the rear side of the opening of the chip discharge groove 5 in the drill rotation direction and incline toward the outer peripheral side in the radial direction of the drill body 1 toward the base end side in the axis O direction. 6b and these first and second flanks 6a,
6b is further connected to the rear side in the drill rotation direction, and is also composed of a third flank 6c which is inclined toward the outer peripheral side of the drill as it goes toward the base end side in the axis O direction. The first and second flanks 6a and 6b have an intersection angle between the second flank 6b located on the base end side in the axis O direction and the axis O on the tip end side in the axis O direction. It is set to be smaller than the intersection angle between the first flank 6a located and the axis O.

Further, from the vicinity of the drill rotation center C at the tip of the cutting blade tip 4, the wall surfaces 5a, 5a of the two chip discharge grooves 5, 5 facing the drill rotation direction and the first flanks 6, 6 of the respective tip flanks are formed. First cutting edge portions 7a and 7a are formed along the ridge line portion intersecting with the first flanks 6a and 6a, respectively. Further, so as to reach the outer periphery of the drill main body 1 along the ridge line portion intersecting the wall surfaces 5a, 5a and the second flanks 6b, 6b, which are continuous with the first cutting edge portions 7a, 7a,
The second cutting edge portions 7b, 7b are formed. The first cutting edge portion 7a and the second cutting edge portion 7b constitute the cutting edge 7. Therefore, in the present embodiment, the axis O is sandwiched and symmetrical with respect to the axis O. To 2
The two cutting edges 7, 7 are formed in such a direction that they gradually recede toward the base end side in the axial direction from the drill rotation center C toward the outer peripheral side. In addition, in the vicinity of the drill rotation center C, the first cutting edge portion 7 of both cutting edges 7,
Cross thinning is applied to a and 7a.

The first and second of the tip flank 6 are also provided.
The flanks 6a and 6b are set so that the crossing angle with the axis O is smaller in the second flank 6b than in the first flank 6a, as described above. Therefore, the tip angles α and β of the first and second cutting edge portions 7a and 7b are set to the second outer peripheral side with respect to the tip angle α of the first cutting edge portion 7a on the drill rotation center C side. The tip angle β of the cutting edge portion 7b becomes smaller.

Further, inside the drill body 1, a driver 2
From the hollow hole 2a to the shank 3 to reach the cutting blade tip 4, a pair of hollow pipe lines 8, 8 are drilled so as to penetrate the drill main body 1. These hollow pipe lines 8,
The tip of 8 is opened on the tip flanks 6 and 6,
Air holes 9a and 9a are formed, respectively. In the present embodiment, these air holes 9a, 9a are
Each of the first to third flanks 6a, 6b, 6c constituting the tip flank 6 is opened so as to be located substantially at the intersection of the intersecting ridge lines. The hollow pipe lines 8 and 8 are formed so as to branch to the outer peripheral side of the drill at the tip side of the cutting blade tip 4, and the branched pipe line 8 is provided on the outer peripheral flank surface of the cutting blade tip 4 which will be described later. Open the air holes 9b, 9
b is formed.

In the gun drill of this embodiment, the abrasive grain layer 10 containing hard abrasive grains is formed at the tip of the cutting blade tip 4 of the drill body 1 as described above. In this embodiment, the abrasive grain layer 10 contains super-abrasive grains such as diamond and CBN (cubic boron nitride), and is formed by electrodeposition using a nickel binder as a main component. There is. The superabrasive grains contained in the abrasive grain layer 10 have a grain size in the range of 50 # to 1000 #. Further, in the present embodiment, such an abrasive grain layer 10 is located closer to the base end side on the ridgeline of the intersection between the tip flank 6 of the cutting blade tip 4 and the outer peripheral surface than the drill rotation center C. Width W = 1 at the base end side in the axis O direction
It is formed in the range of mm. However, in the present embodiment, the heel side portion of the third flank 6c located on the rear side in the drill rotation direction of the tip flank 6 is positioned closest to the proximal end side of the tip flank 6. Therefore, the width W in the present embodiment is from the heel side end 11 of the ridge line intersecting the third flank 6c and the outer peripheral surface of the cutting edge tip 4 to the base end side in the axis O direction. It is set as width.

In the present embodiment, on the outer peripheral surface of the cutting blade tip 4 on the rear side of the chip discharge groove 5 in the drill rotation direction,
The margin 12 is formed so as to extend toward the base end side in the axis O direction of the high hardness portion 30, while the pad having the same diameter as the margin 12 is provided on the drill rotation direction side of the chip discharge groove 5, that is, on the heel side. The portion 13 is also formed so as to extend toward the base end side in the direction of the axis O. Further, on the outer peripheral surface of the cutting blade tip 4, the portion between the margin 12 and the pad portion 13 is recessed toward the inner peripheral side by one step from the outer diameter of the margin 12 and the pad portion 13, that is, the cutting blade diameter of the gun drill. The outer peripheral flank 14 is formed. Furthermore,
In the present embodiment, the cutting edge 7 is formed so as to be centered so that the radial rake angle becomes a negative angle.

In the gun drill thus constructed, the abrasive grain layer 10 containing hard superabrasive grains such as diamond or CBN is provided from the flank 6 of the cutting edge tip 4 at the tip of the drill body 1 to the outer peripheral surface. Since it is formed and the tip of the cutting edge tip 4 is covered with the hard abrasive grain layer 10, the strength and wear resistance of the FRP material are improved even when the FRP material is perforated. Alternatively, it is possible to suppress wear of the drill main body 1 side due to biting of chips generated in the form of powder, and prevent shortening of tool life. Moreover, in this embodiment, the hard abrasive grains contained in the abrasive grain layer 10 are diamond or C.
Since it is a super-abrasive grain such as BN having an ultra-high hardness and a high wear resistance, it is possible to prevent wear of the drill body 1 more reliably and extend its life.

In the gun drill, the cutting edge 7
Since the processed hole formed by the above is ground by the abrasive grain layer 10, it is possible to improve the surface roughness of the inner periphery of the processed hole. In particular, since the abrasive grain layer 10 is formed over the outer peripheral surface of the cutting edge tip 4, that is, is also formed on the margin 12 and the pad portion 13 having the same diameter as the outer diameter of the cutting edge 7, these margins are also formed. The so-called burnishing effect is achieved by the progress of drilling while the abrasive grain layer 10 formed on the pad 12 and the pad portion 13 slidably contacts the inner circumference of the drilled hole, so that the surface roughness of the drilled hole is significantly improved. It becomes possible.

In addition, in the present embodiment, the abrasive grain layer 10 described above is used.
The grain size of the super-abrasive grains contained in is set to a relatively fine grain size of 50 # to 1000 #, so it is possible to grind the inner periphery of the machined hole more smoothly and obtain a higher surface roughness. Becomes Moreover, the abrasive grain layer 10 is formed by electrodeposition using a nickel binder as a main component, and therefore, even for the abrasive grains having such a fine grain size, the detachment is suppressed, and the abrasive grain layer 10 is It is possible to prevent peeling from the cutting edge tip 4 and maintain the above-described effects of improving the wear resistance and surface roughness by the abrasive grain layer 10 for a longer period of time. Further, by forming the abrasive grain layer 10 by electrodeposition, it is possible to obtain the advantage that the uniform abrasive grain layer 10 can be formed relatively easily even at the tip portion of the cutting edge tip 4 having a complicated shape. it can. In order to more surely achieve both wear resistance and high finished surface roughness, it is more desirable that the grain size of the abrasive grains be set in the range of 100 # to 600 #.

Further, since the abrasive grain layer 10 is formed from the tip flank 6 of the cutting edge tip 4 to the outer peripheral surface in this way, with the feeding of the drill body 1 during drilling,
After the cutting blade 7 has passed, the abrasive grain layer 10 formed on the outer peripheral surface of the cutting blade tip 4 always grinds the inner periphery of the processed hole. Therefore, even if burrs are generated in the opening of the processed hole on the side where the drill is inserted or the opening when the drill is removed, the burrs will pass through the abrasive grain layer 1 on the outer peripheral surface thereafter.
Since 0 is scraped off and removed in the process of drilling, it is not necessary to remove the burr again after the processing, and it is possible to reduce the labor and time and improve the efficiency of the entire machining work.

In the present embodiment, the abrasive grain layer 10 is provided on the outer peripheral surface of the cutting edge tip 4 of the drill body 1 on the ridge line intersecting the tip flank 6 (third flank 6c) and the outer peripheral surface. Is formed in a range of width W = 1 mm from the point 11 located closest to the base end side to the base end side in the direction of the axis O. This is because the abrasive grain layer 10 is below this range and the outer circumference of the drill body 1 is smaller. If it is formed only in a small portion on the tip side of the surface, the above-mentioned effects such as suppression of wear of the drill body 1 and improvement of surface roughness due to grinding of the inner periphery of the machined hole may not be sufficiently exerted. Is.

On the other hand, in the present embodiment, the hollow pipe lines 8 formed in the drill body 1 are opened in the tip flank 6 of the cutting edge tip 4 to form air holes 9a, 9a. Compressed air supplied from the machine tool side on which the No. 1 is mounted through the hollow pipe line 8 is supplied to the air holes 9a, 9a.
A hole can be drilled while ejecting from a. As a result, even in the drilling process of the FRP material in which the above-mentioned powdery chips are generated, it is possible to perform the drilling while forcibly and efficiently removing the chips from the processed hole. This makes it possible to more reliably prevent the progress of wear of the drill body 1 and the deterioration of the surface roughness of the machined hole due to the inclusion of chips. Moreover, in the present embodiment, since the hollow pipe lines 8 and 8 are branched in the middle of the cutting blade tip 4 to form the air holes 9b and 9b in the outer peripheral flank 16 as well, the cutting powder can be more reliably cut. It is possible to encourage the elimination of.

Further, in the gun drill of this embodiment, each of the two cutting edges 7, 7 has the above-mentioned rotation center portion C.
It is constituted by two cutting edge portions 7a, 7b whose tip angles α, β gradually decrease from the outer peripheral side toward the outer peripheral side. Therefore, the second cutting edge portion 7b having a small tip angle β on the outer peripheral side can suppress the action of the cutting edge 7 attempting to spread the material at the time of punching, and thereby the drill body 1 It becomes possible to perform drilling while smoothly guiding in the direction of the axis O, and since the expanding action on the outer peripheral side of the cutting edge 7 is reduced in this way, for example, the occurrence of burrs when slipping out of a machining hole is suppressed. In combination with the effect of removing burrs by the abrasive grain layer 10, it is possible to prevent burrs more reliably and perform high-quality drilling in drilling of FRP materials and the like.

On the other hand, on the other hand, on the tip side of the drill body 1, since the tip angle α of the first cutting edge portion 7a is set to be large, for example, the entire cutting edge 7 is set to the tip angle of the second cutting edge portion 7b. The length of the cutting edge 7 in the direction of the axis O can be shortened as compared with the case where β is left as it is. Therefore, for example, when forming a processing hole that penetrates the material, it is possible to shorten the time from when the tip of the cutting blade 7 bites the material to when the rear end of the cutting blade 7 completely comes out. Can be shortened to improve efficiency. Furthermore, by increasing the tip angle α of the cutting edge 7 (first cutting edge portion 7a) at the center of rotation C of the drill, it becomes possible to prevent the cutting edge 7 from chipping at this portion, which further improves the life of the drill. There is also the advantage that it can be extended. However, in the present embodiment, the cutting blade 7 is configured by the two cutting blade portions 7a and 7b as described above, but it is configured by one cutting blade that linearly extends like a general drill. Good.

In the present embodiment, the case where the present invention is applied to a two-blade gun drill has been described, but the present invention is applied to, for example, a one-blade gun drill or a well-known twist drill. Of course, it is also possible to do so. Further, in the present embodiment, the abrasive grain layer 10 is formed from the tip of the drill body 1 to the range of the width W described above, but it may be formed to extend to a range larger than that, for example, in the present embodiment. In a drill such as a gun drill in which the cutting blade tip 4 is attached to the tip of the drill body 1, the abrasive grain layer 1 is provided over the entire length of the cutting blade tip 4.
0 may be formed.

[0026]

As described above, according to the present invention, the drill body is covered with the abrasive grain layer containing the hard abrasive grains formed from the tip to the outer peripheral surface of the drill body to suppress the wear thereof. By the grinding action of this abrasive grain layer, the surface roughness of the inner periphery of the machined hole can be improved, and burrs generated at the opening of the machined hole can be removed in the process of drilling. Therefore, even in the case of machining FRP material or the like in particular, it is possible to significantly extend the life of the drill and to perform high-precision drilling with high accuracy.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is an enlarged view of the tip of the embodiment shown in FIG.

FIG. 3 is a side view as viewed in the X direction in FIG.

FIG. 4 is a side view as viewed in the Y direction in FIG.

[Explanation of symbols]

1 Drill Main Body 4 Cutting Edge Chip 5 Chip Discharge Groove 6 Tip Relief Surface 7 Cutting Edge 10 Abrasive Grain Layer 11 Point located on the most proximal end side on the ridge line intersecting the tip flank 6 of the cutting edge tip 4 and the outer peripheral surface Drill axis C Drill rotation center W Axis O from the point 11 in the range where the abrasive grain layer 10 is formed
Width of direction

Claims (5)

[Claims] 1. A chip discharge groove extending from the tip flank of the drill body toward the base end side in the axial direction is formed on the outer periphery of the drill body rotated around the axis, and the chip discharge groove is formed on the drill rotation direction side. In a drill in which a cutting edge is formed at an intersecting ridge line portion of the facing wall surface and the tip flank, at least from the tip to the outer peripheral surface of the drill body, an abrasive grain layer containing hard abrasive grains is formed. A drill characterized by being present. 2. The drill according to claim 1, wherein the abrasive grain layer contains superabrasive grains as hard abrasive grains. 3. The grain size of the superabrasive grains is 50 # to 1000 #.
The drill according to claim 2, wherein the drill is within the range. 4. The abrasive grain layer is an electrodeposited abrasive grain layer containing a nickel binder as a main component.
Alternatively, the drill according to claim 3. 5. The abrasive grain layer on the outer peripheral surface of the drill body is located at least at the base end side in the axial direction from the point located at the most base end side on the ridge line intersecting the tip flank and the outer peripheral surface. The drill according to any one of claims 1 to 4, wherein the drill is formed to a range of 1 mm.