KR20120055442A - Drilling tool - Google Patents

Abstract

PURPOSE: A drilling tool is provided to guarantee favorable positioning accuracy of holes and prevent a fracture even in case of a drill having a small diameter. CONSTITUTION: A drilling tool comprises a tool body(1) and a spiral chip discharging grooves. One or a plurality of cutting edges is installed in a leading end of the tool body. A plurality of the spiral chip discharging grooves is formed in an outer circumference toward a base end from a front end. A plurality of the spiral chip discharging grooves comprises a main groove and more than one sub groove. A torsion angle of the main groove and sub groove is set at a same angle in the base end of the tool. A length of the sub groove is set as 50~95% of the length of the main groove. The sub groove is arranged side by side with the main groove from a connecting portion to the predetermined position right before the end of the main groove.

Description

Drilling tool {DRILLING TOOL}

The present invention relates to a drilling tool.

In the punching of the printed wiring board PCB, a drill composed of a body portion A and a shank portion B having a blade portion C as shown in FIG. 1 is used. Although the size is various according to a use, in general, the drill of 0.7 mm or less in diameter is used a lot.

Specifically, in the blade portion C, spiral chip discharge grooves 22 are formed on the outer periphery of the main body 20 from the drill tip to the base end side, as shown in FIG. The cutting edge 21 is formed in the cross | ridge ridge part of the 1st flank 24 provided in the rake face of the chip | tip discharge groove | channel 22, and the front-end | tip (for example, patent document) 1, 2). In the figure, reference numeral 25 denotes a second flank which extends to the rear side in the tool rotation direction of the first flank 24, d 'denotes a tool diameter, l' denotes a groove length of the chip discharge groove, and α 'is twisted. It is angle.

In addition, an amorphous carbon coating is put into practical use as a coating for wear resistance and welding resistance for nonferrous metal workpieces such as aluminum alloy, titanium, magnesium, copper, and the like, and is used for cutting tools such as drills, end mills, and blade cutting type cutting chips. Is used by covering it (for example, refer patent document 3).

By the way, a PCB is comprised by joining copper and glass fiber cloth which impregnated resin as an insulating layer, and the recent PCB is a thing of the improvement of heat resistance and bending strength for further reliability improvement. Reinforcement and low thermal expansion are demanded, and high reliability is increasing by increasing the mechanical strength of the glass fiber cloth and resin which comprise a PCB.

However, when considered as a workpiece to be drilled, the PCB of the above-described structure is easy to promote the wear of the drill by the increase in the mechanical strength, and the hole quality such as the hole position precision accompanied by the drill breakage or excessive wear during the drilling. Easy to cause deterioration.

On the other hand, with the increase in the PCB density, the required hole diameter (diameter of the drill) has a smaller diameter year by year, and a number of drilling operations with a diameter of 0.4 mm or less are increasing.

In the drilling processing step, in consideration of processing efficiency, it is common to drill a plurality of PCBs having the same specification by laminating them. Specifically, an aluminum plate or an aluminum plate with a resin coated with a resin on the surface is placed on the upper surface of a plurality of stacked PCBs in order to increase the centripetality of the drill. Is common. Since the aluminum plate with resin has a higher effect of improving the centripetality than the aluminum plate and also contributes to the improvement of the breakage of the drill, the aluminum plate with resin is often used for the drilling of small diameter drills having a diameter of 0.4 mm or less.

In recent years, even a small diameter drill for PCBs used for processing a PCB having a relatively poor workability as described above, a drilling life that can be drilled without increasing the number of overlapping PCBs for the purpose of reducing the processing cost and without damaging the drill. Extension of is required.

However, when the punching process is performed using an aluminum plate with resin as the butting plate, the chips wound around the proximal end of the drill blade portion C are more remarkably generated than when the punching process is performed using the aluminum plate. The higher the viscosity of the resin and the thicker the coated resin, the higher the tendency for the chipped chips of the chips described above to occur, and it is difficult to realize the demand.

This is because chips generated at the time of drilling are usually sucked by the chip suction function attached to the punching machine and carried out to a predetermined dust box. However, when an aluminum plate with resin is used, the resin softened by the cutting heat at the time of drilling The chip is guided and discharged along with the chip discharge groove, and it is thought to act to stick the drill and the chip in the vicinity of the base end of the blade part C. By repeating the punching process, the amount of chipped chips of the chip will increase. do.

Although the amount of chipped chips varies depending on the number of revolutions of the drill during drilling, the processing conditions of the transfer speed, and the material of the PCB, as shown in FIG. 3 (a), significant chipped chips are generated. During the drilling process in which the chipped chip continues, the chip (chip chunk) is separated from the drill by any vibration or the like, falls on the butt plate without being sucked by the suction function, and then drills to be drilled. It is thought that deterioration of hole positional accuracy and breakage of the drill occur by interfering with the dropped chip lump. And the chip chunk which fell on the butt board in FIG.3 (b) is illustrated.

For example, in Patent Document 4, in a PCB drill having two cutting blades and two chip discharge grooves, the chip discharge grooves are joined at a position where a predetermined amount has been retracted from the front end, and one is located behind the confluence point. Although a technique of improving the rigidity is disclosed by forming a groove, there is no mention of the coiling of the chip, and the above requirements cannot be satisfied.

Japanese Unexamined Patent Publication No. 56-39807 Japanese Unexamined Patent Publication No. 2006-55915 Japanese Unexamined Patent Publication No. 2001-341021 Japanese Patent Laid-Open No. 2007-307642

The present invention has been made in view of the above-described phenomenon, and it is possible to prevent chip sticking, and even a small diameter drill having a diameter of 0.7 mm or less, particularly 0.4 mm or less, has a long break life and good hole position accuracy. It is to provide a drilling tool with extremely practicality that can realize stable drilling processing.

The gist of the present invention will be described with reference to the accompanying drawings.

One or more cutting blades are provided at the tip of the tool main body 1, and a plurality of spiral chip ejection grooves are formed on the outer periphery of the tool main body 1 from the tool tip toward the base end side. 2 and 3 are formed, and the plurality of chip discharge grooves 2 and 3 include one main groove and one or more minor grooves, and the middle of the main grooves 2. As the drilling tool in which the sub groove 3 is spoken to the part, the twist angle of the main groove 2 and the sub groove 3 is the tool proximal side from the main groove 2 and the protruding portion 4 of the sub groove 3. Set at approximately the same angle, the groove length of the sub groove 3 is set to 50 ~ 95% of the groove length of the main groove 2, the sub groove 3 is the main groove from the speaker (4) It relates to a drilling tool, characterized in that formed in parallel with the main groove (2) to a predetermined position immediately before the end of (2).

In addition, one or a plurality of cutting blades are provided at the tip of the tool main body 1, and a plurality of spiral chip ejection grooves 2, 3 are formed on the outer periphery of the tool main body 1 from the tool tip toward the proximal side. The plurality of chip discharging grooves 2 and 3 include a main groove and at least one sub groove, and the main groove is a drilling tool in which the sub groove 3 is protruded in the middle of the main groove 2. (2) and the torsion angle of the sub groove (3) is set at approximately the same angle at the tool proximal side from the main groove (2) and the speaker (4) of the sub groove (3), the groove of the sub groove (3) The length is set to 70 to 95% of the length of the groove of the main groove (2), the main groove (2) from the speaker (4) to a predetermined position immediately before the end of the main groove (2) It relates to a drilling tool, characterized in that formed in parallel with the.

Moreover, in the drilling tool of Claim 1, the width | variety of the speech groove of the said main groove 2 and the said sub groove 3 in the said speech part 4 is 1.1 of the groove width of the said main groove 2 before speech. It relates to a drilling tool, characterized in that 1.9 times.

Moreover, in the drilling tool of Claim 2, the width | variety of the speech groove of the said main groove 2 and the said sub groove 3 in the said speech part 4 is 1.1 of the groove width of the said main groove 2 before speech. It relates to a drilling tool, characterized in that 1.9 times.

Moreover, in the drilling tool of Claim 1, the width | variety of the speech groove of the said main groove 2 and the said sub groove 3 in the said speech part 4 is 1.3 of the groove width of the said main groove 2 before speech. It relates to a drilling tool, characterized in that 1.8 times.

Moreover, in the drilling tool of Claim 2, the width | variety of the speech groove of the said main groove 2 and the said sub groove 3 in the said speech part 4 is 1.3 of the groove width of the said main groove 2 before speech. It relates to a drilling tool, characterized in that 1.8 times.

Further, in the drilling tool according to any one of claims 1 to 6, the start end of the protruding portion 4 is a position at least twice the diameter of the tool from the tool tip, and the groove length of the main groove 2. It relates to a drilling tool, characterized in that formed at a position of 50% or less.

Further, in the drilling tool according to any one of claims 1 to 6, each ball including the drawback disadvantages 5,6 of the ends of the main groove 2 and the sub groove 3, respectively. In the construction right angled cross section, the first and second weaknesses of the main groove 2 and the first axis connecting the rotary shaft center of the tool and the minor disadvantage 3 of the sub groove 3 and the tool At least one of the narrow angles which the said 1st line and said 2nd line make in this projection surface, when projecting the 2nd line which connects the rotating shaft center (O) to the same axial perpendicular projection surface viewed from the axial direction of a tool. And a dog's narrow angle γ is greater than 90 ° and less than 180 °.

Further, in the drilling tool according to claim 7, the cutting of the main groove 2 in each of the tool axis perpendicular cross sections including the cutting disadvantages 5 and 6 of the ends of the main groove 2 and the sub groove 3. The first line connecting the disadvantage 5 and the rotation axis of the tool O and the second line connecting the disadvantage 6 of the sub groove 3 and the rotation axis O of the tool are in the axial direction of the tool. When projecting to the same axial perpendicular projection surface from the above, at least one narrow angle γ is larger than 90 degrees and less than 180 degrees among the narrow angles formed by the first line and the second line on the projection surface.

Further, the drilling tool according to claim 8, wherein the main groove 2 and the secondary groove 3 are formed one by one as the chip discharge grooves 2 and 3, respectively.

The drilling tool according to claim 9, wherein the main groove 2 and the secondary groove 3 are formed one by one as the chip discharge grooves 2 and 3, respectively.

Moreover, the drilling tool of Claim 10 WHEREIN: It relates to the drilling tool characterized by the coating of an amorphous carbon film as a lubricity film.

Moreover, the drilling tool of Claim 11 WHEREIN: It relates to the drilling tool characterized by the coating of an amorphous carbon film as a lubricity film.

Furthermore, the drilling tool of Claim 12 WHEREIN: It is related with the drilling tool characterized by the tool diameter being 0.4 mm or less.

Moreover, the drilling tool of Claim 13 WHEREIN: It is related with the drilling tool characterized by the tool diameter being 0.4 mm or less.

Since the present invention is constituted as described above, even a small diameter drill having a diameter of 0.7 mm or less, particularly 0.4 mm or less can be prevented from being wound, and long drilling life and good hole position accuracy are achieved to achieve stable drilling. As far as possible, a drilling tool having excellent practicality is obtained.

1 is a schematic side view illustrating a drill for a PCB.
2 is an enlarged schematic explanatory diagram of a conventional example.
FIG. 3: (a) is a photograph which illustrates the wound of the chip | tip wound in the vicinity of the base end of the blade part C of a drill, and (b) is a photograph which illustrates the chip | tip mass which fell on the butt board.
4 is a schematic explanatory diagram of a blade of the present embodiment.
5 is a schematic explanatory diagram of a raised narrow angle of the present embodiment.
6 is a schematic exploded view showing the outline of the torsion angle between the main groove and the sub groove.
7 is a schematic exploded view showing the outline of the torsion angle between the main groove and the sub groove.
8 is a schematic exploded view showing the outline of the torsion angle between the main groove and the sub groove.
9 is a schematic exploded view showing the outline of the torsion angle between the main groove and the sub groove.
10 is a table showing experimental conditions and experimental results.
11 is a photograph showing experimental results.

DESCRIPTION OF EMBODIMENTS Embodiments of the present invention, which are considered to be mutually preferred, will be described briefly with reference to the drawings with the operation of the present invention.

When chips generated at the tip of the tool at the time of punching are discharged along the chip discharge grooves 2 and 3, the chips collide with each other in the opening part 4 between the main groove 2 and the sub groove 3. Since the chip is forcibly scattered (in the tool radial direction) and hard to reach the tool base end, the chipping at the tool base end is prevented.

Further, after the speaker 4, the main grooves 2 and the sub grooves 3 are arranged side by side, so that the groove volume is reduced and the rigidity is secured as compared with the case where the plurality of chip discharge grooves are formed independently without speech. It becomes possible, and the hole position precision can be improved by that much.

In addition, by varying the groove lengths of the main grooves 2 and the sub grooves 3, the tool base end side (the source portion) which tends to be the starting point of the breakage, as compared with the case where the groove lengths of the plurality of chip discharge grooves have the same length. Rigidity can be secured, and the fracture resistance can be improved.

[Example]

Specific embodiments of the present invention will be described with reference to FIGS. 4 to 11.

In this embodiment, one or a plurality of cutting blades are provided at the tip of the tool main body 1, and a plurality of spiral chip ejection grooves 2 are formed on the outer periphery of the tool main body 1 from the tool tip toward the proximal side. 3) is formed, the plurality of chip discharge grooves (2, 3) comprises one main groove and one or more sub grooves, the sub groove (3) in the middle of the main groove (2) As the drilling tool to be formed, the torsion angles of the main groove 2 and the sub groove 3 are set at approximately the same angle from the protruding portion 4 of the main groove 2 and the sub groove 3 at the proximal end of the tool, The groove length of the sub groove 3 is set to 50 to 95% of the groove length of the main groove 2, and the sub groove 3 is predetermined from the speaker 4 just before the end of the main groove 2. It is formed to be arranged side by side with the main groove (2) to the position.

In addition, in the present embodiment, the main groove 2 refers to a groove having the longest groove length, and the sub groove 3 refers to a groove having a shorter groove length than the main groove 2.

Specifically, in the present embodiment, the tool diameter is 0.1 mm, and the main groove 2 and the sub grooves 3 extending to the main groove 2 are formed one by one, and the main groove 2 and the sub groove are formed. A drill having a cutting blade formed integrally with the tool main body 1 at the cross ridge portion between the rake surface (3) and the tip flank (first flank) of the tool main body, respectively, is used for boring a PCB.

For the punching of this PCB, for example, four PCBs (substrate: 0.15mm thickness / front and back Cu layers) for a semiconductor package, which are difficult-to-use materials, are stacked in the same manner as in the following experimental example. A thickness generally used as a backup board on the lower surface of the PCB so that an aluminum plate with a resin of 0.11 mm in thickness can be mounted as an abutting plate to allow through hole processing. It is performed in the state which arrange | positioned 1.5 mm of paper phenol materials. The thickness of the butt plate is suitably set in the range of 0.04 to 1.0 mm. In addition, the thickness of the Cu layer of PCB about 0.1 mm in thickness is about 2-80 micrometers normally.

In this embodiment, a drill (two blade drill) having two cutting blades and two chip discharge grooves (one main groove and one sub groove) will be described. The same applies to a drill having three or more blades (for example, having one main groove and two sub grooves). At this time, when a single blade drill is used, a higher centripetal effect can be obtained, and when a three blade drill is used, better machinability can be obtained.

Specifically, in the present embodiment, the twist angles of the main grooves 2 and the sub grooves 3 are set at approximately the same angles from the protruding portion 4 between the main grooves 2 and the sub grooves 3 at the tool proximal side. In addition, the groove length l2 of the sub groove 3 is set to 50 to 95% of the groove length l1 of the main groove. If less than 50%, the groove volume from the middle of the groove to the base, which is important for discharging the chip out of the substrate, becomes small, so that the possibility of breakage is increased due to chip blockage, and when longer than 95%, the main groove 2 Becomes smaller than the groove length l1, making it difficult to secure rigidity at the root portion. In addition, when the groove length l2 of the sub groove 3 is set to 70% or more of the groove length l1 of the main groove 2, more stable chip discharge is performed, so that longer life and stable hole processing can be realized. It was confirmed by the present inventors. Therefore, the groove length l2 of the sub groove 3 is more preferably set to 70 to 95% of the groove length l1 of the main groove 2.

As a result, the termination (lower disadvantage 6) of the sub groove 3 becomes the tool tip side than the termination of the main groove 2 (lower disadvantage 5), and the sub groove 3 is the main groove 2 and the sub groove. It is arrange | positioned in parallel with the main groove to the predetermined position (between section Q of FIG. 4) immediately before the termination of the main groove 2 from the speech part 4 (terminal end) of (3).

Specifically, the main groove 2 and the sub groove 3 are spoken in the speech section 4 so that some of them overlap so that the two grooves are arranged side by side while the lowest point of each groove is a predetermined distance apart. That is, the main groove 2 and the sub groove 3 are formed so as to be arranged side by side in a state in which a part of the groove shape before the speech is left overlapped after the speech portion 4 (see FIG. 4). 4 (a) to 4 (d) also see the blades from the sides in different rotational phases.

In the present embodiment, the width W2 of the speech groove between the main groove 2 and the sub groove 3 in the speech section 4 (in the state where the main groove 2 and the sub groove 3 at the end of the speech section partially overlap each other). The total groove width W2} is delivered to be 1.1 to 1.9 times the groove width W1 of the main groove 2 before the speech. If it is less than 1.1 times, the groove volume is too small to achieve smooth chip evacuation, and if it is larger than 1.9 times, it is difficult to secure the rigidity of the drill because the groove volume is large. In addition, it is more preferable that the width W2 of the speech groove is set to 1.3 to 1.8 times the groove width W1 of the main groove 2 before the speech, in consideration of the balance of the opposite properties of chip discharge and stiffness. As a result of intensive studies by the present inventors, it was obtained by knowledge. In addition, in this embodiment, the groove width of the sub groove 3 is set equal to the groove width W1 of the main groove 2. In other words, the closer the width W2 of the speech groove is to twice the groove width W1 of the main groove 2 (the sub groove 3) before the speech, the smaller the degree of overlap between the two.

In addition, in the present embodiment, the speech starting point in the speech section 4 between the main groove 2 and the sub groove 3 is a position at least twice the tool diameter from the tool tip and the groove length of the main groove 2 ( It is installed at 50% or less of l1). In the present embodiment, the speech section 4 between the main groove 2 and the sub groove 3 is formed of the sub groove 3 separated from the tool tip by a distance M2 from the speech start point away from the tool tip in FIG. The range to 2 torsion angle change point (the starting point of a side by side arrangement) is shown. If the starting point of the speech (starting point of the speech section 4) is formed at a position less than twice the diameter of the tool from the tool tip, it is likely to be polished to the speech section at the time of re-polishing, and it becomes difficult to obtain a suitable blade shape. When provided at a position at the proximal end from 50% of the groove length of the main groove from the tool tip, the rigidity is deteriorated, and the hole position accuracy is deteriorated.

In addition, in this embodiment, when the sub groove 3 is delivered to the middle portion of the main groove 2, the sub groove 3 or the main groove 2 is changed by changing the torsion angle on the way. For example, the main groove 2 is a constant torsion angle from the start to the end, and the sub groove 3 may be addressed in the middle of the main groove 2 by changing the torsion angle of the sub groove 3 on the way. You can change your speech on the way. Specifically, for example, a form as shown in Figs. 6 to 9 can be considered.

6 and 7 make the torsion angle α of the main groove 2 constant and change the torsion angle of the sub groove 3 from small beta 1 to large beta 2 to small beta 3. Specifically, the initial torsion angle β1 of the sub groove 3 is changed to be larger β2 at the first torsion angle change point away from the tool tip by a distance M1, so that the sub groove 3 approaches the main groove 2. Immediately after being addressed to 2) (FIG. 6) or after intersecting with the main groove 2 (FIG. 7), the angle equal to the torsion angle α of the main groove 2 at the second torsion angle change point away by the distance M2 from the tool tip. It is changed to β3 and arranged side by side. In this case, since the torsion angle α of the main groove is constant, there is an advantage that it is easy to secure rigidity. 6 and 7, α, β1, and β3 are set to 45 °, and β2 is set to 55 °. In this embodiment, the form of Fig. 6 is employed.

8 and 9 change the torsion angles of the main groove 2 and the sub groove 3 from small (45 °) to the large (55 °), respectively. To speak. Specifically, by increasing the torsion angle of the sub groove 3 on the way, the main groove 2 is approached, and after the sub groove 3 speaks to the main groove 2 (FIG. 8) or after crossing the main groove (FIG. 8). 9), the torsion angle of the main groove 2 is changed to the same angle as the torsion angle of the sub groove 3. In this case, since the torsion angle of both is changed in the middle, the chips are not wound so much and the torsion angle becomes large at the tool proximal end, so that the chips generated at the tool tip are smoothly discharged by the good pumping action. There is an advantage to this. 6 to 9, the main groove 2 and the sub groove 3 may be reversed. That is, in FIGS. 6 and 7, the torsion angle of the sub groove 3 may be made constant, and both may be addressed by changing the torsion angle of the main groove 2 from small to large to small. In FIGS. 8 and 9, the main groove By increasing the torsion angle of (2) in the middle, the sub-groove 3 is approached, and the main groove 2 immediately after the speech to the sub-groove 3 (Fig. 8) or after crossing the sub-groove (Fig. 9), the sub-groove ( The twist angle of 3) may be changed to the same angle as the twist angle of the main groove 2.

In addition, the present embodiment also has the disadvantages of the notch 5 of the main groove 2 in the right angle cross section of each tool axis including the disadvantages 5, 6 of the ends of the main groove 2 and the minor groove 3. And the first line connecting the rotary shaft center O of the tool and the second weakness 6 of the cut-off disadvantage 6 of the sub-groove 3 and the second line connecting the rotary shaft center O of the tool in the axial direction of the tool. When projecting on a perpendicular projection surface, it is comprised so that at least 1 narrow angle (gamma) may become larger than 90 degrees and become 180 degrees or less among the narrow angles which the said 1st line and said 2nd line make in this projection surface. In other words, in each of the tool shaft perpendicular cross sections including the cutting disadvantages 5 and 6 of the ends of the main groove 2 and the sub groove 3, the respective cutting disadvantages 5 and 6 and the axis of rotation of the tool. Each line connecting (O) is a projection line projected on the same axial orthogonal projection plane viewed from the axial direction of the tool, so that the projection line and the respective subgrooves 3 each include a cut-off disadvantage 5 of the main groove 2. Among the narrow angles formed by the projection line including the above-mentioned disadvantage 6, at least one narrow angle γ is configured to be greater than 90 degrees and less than 180 degrees.

Specifically, in the present embodiment, one of the main grooves 2 and the sub grooves 3 are formed one by one, and in the right angle cross section of the tool axis including the disadvantage disadvantages 5 of the main groove 2, In the right angle cross section of the tool axis, including the first line connecting the rotary shaft center of the tool O (see FIG. 5 (b)) and the cut-off disadvantage 6 of the sub-groove 3, A second line connecting the axis of rotation O (see Fig. 5 (a)) is projected on the same axial perpendicular projection plane in the axial direction of the tool, and the narrow angle formed by the respective lines (projection lines) on the axial perpendicular projection plane. γ (hereinafter referred to as a reclining narrow angle) is configured to be greater than 90 degrees and less than 180 degrees.

That is, the groove lengths 1 and 1 of the main grooves 2 and the sub grooves 3 are set so that the raised narrow angle γ is larger than 90 degrees and becomes 180 degrees or less. This is derived from the experimental results described later, and the hole positional accuracy becomes extremely good if the raised narrow angle γ is within the above range. On the other hand, if all of the raised narrow angles are 90 degrees or less, since the discharge direction of the chip is biased, unbalanced discharge may occur at the tool proximal end, and unexpected hole bending may occur. An example of the axial perpendicular projection surface in the case of a drill having three or more blades (for example, having one main groove and two sub grooves) is shown in FIG. 5 (d). In the case of the three grooves, the cut angle formed by the projection line (first line) including the raise disadvantage 5 of the main groove 2 and the projection line (second line) including the raise disadvantage 6 of the one sub groove 3. If γ is greater than 90 ° and less than 180 °, bias in the discharge direction of the chip can be avoided, so that a good balance of discharge can be obtained. That is, when two or more sub grooves exist, two or more second lines exist, but one of the raised narrow angles γ formed by the first line and the plurality of second lines is greater than 90 degrees and 180 degrees. If it is below, since the bias of the discharge direction of a chip | tip can be avoided, a balanced discharge | emission can be obtained.

And the cut-off angle γ is represented by the rotational phase difference (angle difference) between the cut-off disadvantage 5 of the main groove 2 and the cut-off disadvantage 6 of the sub groove 3.

In addition, an amorphous carbon film is coated on the tool body 1 as a lubricity film. That is, in this embodiment, since the groove volume becomes smaller on the tool proximal side (when the web and the web taper value are the same) compared to the shape of the conventional two-blade drill, it depends on the type of substrate, the thickness, and the number of overlaps. It is difficult to obtain a smooth chip discharging performance, which may cause deterioration and loss of inner wall roughness. However, by coating the amorphous carbon film, chip evacuation can be improved and high-precision drilling can be performed utilizing the point of rigid shape.

Each part is explained concretely.

In this embodiment, the base material is a cemented carbide alloy composed of hard particles composed mainly of WC and a binder composed mainly of Co, and the average particle diameter of the WC particles of this cemented carbide is 0.1 µm? It is 2 micrometers and the Co content is 5 to 15% by weight, and the amorphous carbon film is coat | covered at least by the chip discharge groove | channel of the tool main body 1. As shown in FIG. Since the amorphous carbon film is hard, it suppresses abrasion of the tool and has high lubricity, so that the chip is easily discharged to the base end of the tool main body 1 along the chip discharge groove, thereby preventing chip clogging and not being broken.

In addition, in the present embodiment, an amorphous carbon film composed of high hardness amorphous carbon (DLC) composed mainly of carbon atoms as a lubricating film and having Vickers hardness of 3000 or more is used. A coating made of a relatively low hardness amorphous carbon (DLC) or a mixture of DLC and another substance (for example, metal) may be employed, or another lubricity coating such as chromium nitride may be employed.

In this embodiment, the amorphous carbon film is formed directly on the substrate, but for example, one or two or more elements selected from group 4a, 5a, 6a and Si of the periodic table directly on the substrate. It is also possible to form a lower layer coating layer (base film) composed of a metal or a semimetal consisting of a metal layer having a thickness of 200 nm or less and 1 nm or more, and forming the amorphous carbon film on the lower layer. In addition, the lower coating layer is not limited to the above-described structure, and is composed of a compound of one or two or more elements selected from Groups 4a, 5a, 6a and Si of the periodic table with one or more elements selected from nitrogen and carbon. You may employ | adopt.

In the present embodiment, an arc ion plating method film forming apparatus is used for forming an amorphous carbon film or a base film, but a PVD film forming apparatus such as a sputtering method or a laser ablation method may be used.

The present invention has been invented as a drill coated with a lubricating film such as an amorphous carbon film for use in the drilling of nonferrous workpieces such as PCBs, etc., but the substrate is composed of hard particles containing WC as a main component and a binder containing Co as a main component. Cemented carbide is preferable because it is a balanced material of hardness and toughness.

If the average particle diameter of the WC particles is made too small, it becomes difficult to uniformly disperse the WC particles in the binder, and the breakdown force of the cemented carbide is likely to occur. On the other hand, when the WC particles are too large, the hardness of the cemented carbide decreases. On the other hand, when the Co content is too small, the strength of the cemented carbide decreases. On the contrary, when the Co content is too high, the hardness of the cemented carbide decreases. Therefore, it is preferable that the average particle diameter of WC particle | grains is 0.1 micrometer-2 micrometers, and Co content is 5 to 15% based on a cemented carbide.

In addition, in order to perform stable punching processing without film peeling, such as PCB, it is preferable to make adhesiveness of a base material and an amorphous carbon film higher. A metal or semimetal consisting of one or two or more elements selected from group 4a, 5a, and 6a elements of the periodic table such as Ti, Cr, Ta, and Si is formed as a base film directly on the substrate, and an amorphous carbon film is formed thereon. By film-forming, the adhesiveness of a base material and an amorphous carbon film can further be improved. In addition, a compound of one or two or more elements selected from group 4a, 5a, 6a and Si of the periodic table with one or more elements selected from nitrogen and carbon may be formed as a base film directly on the substrate.

Since the base film is formed for the purpose of improving the adhesion between the substrate and the amorphous carbon film, the base film has no meaning even if it is too thick. The base film is preferably 200 nm or less and 1 nm or more.

Since the present embodiment is constituted as described above, when the chip generated at the tool tip during the drilling is discharged along the chip discharge grooves 2 and 3, the swelling portion 4 between the main groove 2 and the sub groove 3 is discharged. In this case, the chips collide with each other, so that the chips are forcibly scattered (in the tool radial direction) and do not reach the tool base end, thereby preventing the chip from being wound at the tool base end.

Further, after the speaker 4, the main grooves 2 and the sub grooves 3 are arranged side by side, so that the groove volume is reduced and the rigidity is secured, as compared with the case where the plurality of chip discharge grooves are formed independently without each other. It becomes possible, and the hole position precision can be improved by that much.

Further, by varying the groove lengths of the main grooves 2 and the sub grooves 3, the rigidity at the tool proximal side (source portion), which tends to be a starting point of breakage, is compared with the case where the groove lengths of the plurality of chip discharge grooves have the same length. It is possible to secure the, it is possible to improve the damage resistance.

Therefore, even if the aluminum plate with resin is used as the butting plate, the present embodiment is less likely to be damaged and the chip discharging performance is remarkably improved, so that the chip can be prevented from being wound and the diameter is 0.7 mm or less, especially 0.4 mm or less. Even a small diameter drill has a long tool life and a good hole positional accuracy, and thus makes a drilling tool excellent in practicality which can realize stable drilling.

The experimental example which demonstrates the effect of this Example is demonstrated.

FIG. 10 is a table showing experimental conditions and experimental results of evaluating hole position accuracy and wound residues by varying the subgroove length (to accompany the changed narrowing angle). In the drill used in this experiment, the tool diameter was 0.1 mm, the groove length of the main groove 2 was 1.8 mm, and the conventional example was a conventional two-blade two groove-shaped drill (the twist angles of two chip ejection grooves were 45 Experimental Examples 1 to 10 speak the main groove and the sub groove in the form shown in FIG. 6, and Experimental Example 11 speak the main groove and the sub groove in the form shown in FIG. Other forms, such as thickness and tip angle, are made the same value. In addition, each drill is coated with an amorphous carbon film (DLC).

In this experiment, four PCBs (semiconductor: thickness 0.15mm / front and back Cu layers) for a semiconductor package, which are difficult-to-use materials, are stacked, and an aluminum plate with a thickness of 0.11 mm is placed as an abutting plate on the upper surface, and through hole processing is performed. On the lower surface of the PCB was placed a paper phenol material of thickness 1.5mm which is generally used as a backup board. In addition, the number of revolutions of the drill (spindle) was 200 krpm, the feed rate was 1.8 m / min, the ascending speed was 25.4 m / min, and the set hit number was 3,000 hits.

From FIG. 10, it was confirmed that Experimental Examples 1 to 8 and Experimental Example 11 had less residues which were all wound up compared with the conventional example. In particular, as shown in FIG. 11, Experimental Example 11 confirmed that it was the best because there was hardly any leftover dregs. It is thought that this is because the chip scattering effect is higher by changing the twist angle of both in the middle.

In addition, in Experimental Examples 1 to 8 and Experimental Example 11, it was confirmed that the hole positional accuracy was good as compared with the conventional example. In addition, Experimental Examples 2, 4, 6, 7, and 11 in the case where the sub groove length was 56 to 89% of the main groove length and the cut narrow angle was 106 to 180 ° showed that the hole position accuracy was particularly good. . And in Experimental Examples 3, 5, and 8 in which the sub groove length is in the range of 56 to 89% of the main groove length, the hole positional accuracy is better than that of the conventional example. It may generate | occur | produce and the Max value will become large (it expresses in Max increment in FIG. 10), and there exists a possibility that stable hole processing cannot be obtained. In Experimental Example 1, the hole positional accuracy is better than that of the conventional example, but similarly due to both factors that the groove length of the main groove 2 and the groove length of the sub groove 3 are the same, and the raised narrow angle is small. There is a possibility that Max increment occurs and stable hole machining cannot be obtained.

And in Experimental example 9 and 10 whose sub groove length was extremely short, a drill was broken. This is thought to be due to the deterioration of chip discharge.

From the above, it can be confirmed that the wound of the chip does not depend on the raised narrow angle but only affects the hole position accuracy, and Experimental Examples 2, 4, 6, and 7 in which both the subgroove length and the raised narrow angle fall within the above ranges. 11 confirmed that the drilling tool had a small amount of wound residue and good hole positional accuracy.

1: tool body
2: chip discharge groove
3: chip discharge groove
4: speech
5: recoup
6: recoup
O: tool axis

Claims (15)

One or a plurality of cutting blades are formed at the tip of the tool main body, and a plurality of spiral chip ejection grooves are formed on the outer periphery of the tool main body from the tool tip to the base end side. The plurality of chip discharging grooves include a main groove and at least one sub groove, wherein the main groove and the sub hole are drilled in the middle of the main groove. The torsion angle of the sub groove is set at approximately the same angle from the proximal side of the main groove and the sub groove, and the groove length of the sub groove is set to 50 to 95% of the groove length of the main groove, and the sub groove is A drilling tool, characterized in that it is formed so as to be arranged in parallel with the main groove to a predetermined position immediately before the end of the main groove from the speaker. One or a plurality of cutting blades are formed at the tip of the tool body, and a plurality of spiral chip ejection grooves are formed on the outer periphery of the tool body from the tool tip to the proximal side. And at least one sub groove, wherein the sub groove is struck in the middle of the main groove, wherein the torsion angle of the main groove and the sub groove is at approximately the same angle from the proximal side of the tool from the speech portion of the main groove and the sub groove. And the groove length of the sub groove is set to 70 to 95% of the groove length of the main groove, and the sub groove is formed to be arranged side by side with the main groove from the speaker to a predetermined position immediately before the end of the main groove. Drilling tools characterized by the above. The drilling tool according to claim 1, wherein the width of the speech groove between the main groove and the sub groove in the speech section is 1.1 to 1.9 times the width of the groove of the main groove before the speech. The drilling tool according to claim 2, wherein the width of the speech groove between the main groove and the sub groove in the speech section is 1.1 to 1.9 times the width of the groove of the main groove before the speech. The drilling tool according to claim 1, wherein the width of the speech groove between the main groove and the sub groove in the speech section is 1.3 to 1.8 times the width of the groove of the main groove before the speech. The drilling tool according to claim 2, wherein the width of the speech groove between the main groove and the sub groove in the speech section is 1.3 to 1.8 times the width of the groove of the main groove before the speech. 7. The start end of the speech section is located at least twice the tool diameter from the tool tip and is formed at a position of 50% or less of the groove length of the main groove. Drilling tools. The cut-off of the said main groove in any one of Claims 1-6 in each tool-axis right angle cross section containing the drawback disadvantage of the end of the said main groove and the sub-groove. The first line connecting the disadvantage and the axis of rotation of the tool and the raise of the sub groove and the second line connecting the axis of rotation of the tool are projected on the same axial perpendicular projection plane when viewed in the axial direction of the tool, the first line in this projection plane. The drilling tool, characterized in that at least one narrow angle is greater than 90 degrees and less than 180 degrees among the narrow angles formed by the line and the second line. 8. The tool according to claim 7, wherein the first line connecting the cutting axis of the main groove and the axis of rotation of the tool and the tool at the right angle cross section of each tool axis including the cutting disadvantages of the ends of the main groove and the sub groove, At least one narrow angle of the narrow angle formed by the first line and the second line in the projection surface when the second line connecting the rotational axis of the projection is projected on the same axial perpendicular projection surface in the axial direction of the tool. A drilling tool, characterized in that it is greater than 90 ° and less than 180 °. The drilling tool according to claim 8, wherein the main groove (2) and the sub groove are formed one by one as the chip discharge groove. The method of claim 9, wherein as the chip discharge grooves Drilling tool, characterized in that the main groove (2) and the secondary groove is formed one by one. The drilling tool according to claim 10, wherein an amorphous carbon film is coated as a lubricity film. The drilling tool according to claim 11, wherein an amorphous carbon film is coated as a lubricity film. 13. The drilling tool of claim 12, wherein the tool diameter is 0.4 mm or less. 14. The drilling tool of claim 13, wherein the tool diameter is 0.4 mm or less.

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