TWI577471B - Drilling tools - Google Patents

Description

Drilling tool

This invention relates to drilling tools.

In recent years, with the miniaturization, thinning, and weight reduction of printed wiring boards (PCBs), in order to improve reliability, heat resistance and rigidity are further increased. The hard-to-cutting of the resin of the glass fiber cloth and the insulating portion makes it difficult to wear the drill bit (hereinafter referred to as a PCB drill bit) used for drilling the PCB, which causes problems such as deterioration of the positional accuracy of the hole with wear.

For this reason, various types of drills which are coated with a hard film for improving wear resistance, such as disclosed in Patent Document 1, are proposed, and further improvement of the improvement in the hole position accuracy is desired.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2012-11489

The inventors of the present invention have found various hard coatings in various research results. When the drill bit of the film is drilled, the accuracy of the hole position is deteriorated due to the loss of the hard film and the rigidity of the drill, and the problem that the hard film is coated and the fracture resistance is lowered.

Specifically, as the number of machining holes increases, the wear on the periphery of the drill increases, and when the resistance in the tool radial direction becomes easy after the material to be cut enters, as shown in FIG. 1, the drill bit may have a traveling direction. The offset makes the hole position accuracy worse. The hard film should be coated to suppress the wear of the periphery of the above-mentioned drill, but it is degraded (destroyed) as the hard film wear increases, and it becomes impossible to suppress the wear of the periphery of the drill when the base material of the drill is exposed. Further, when the rigidity of the drill itself is low, even a slight resistance due to the radial direction of the tool becomes easy to bend, and it is difficult to obtain an effect of suppressing the deterioration of the hole position accuracy even if the hard film is coated. Further, Fig. 1 is an example of a case where a PCB drill bit is used to drill a PCB held by a plate and a backing plate.

Further, the hard film coated on the drill has low toughness, and is likely to be cracked due to compression, stretching, and twisting due to bending of the drill during drilling, and cracking of the hard film is a starting point for damage of the drill. When the hard film is coated, there is a case where the fracture resistance is lowered.

In order to solve the above problems, the present invention provides a predetermined chip flute shape in which a chip evacuation groove is connected (combined) in a two-blade and two-groove-shaped drilling tool, and is predetermined at an edge of a predetermined peripheral direction length. The more the ratio is set, the thicker the hard coating on the tool front end side, and the drilling tool which is excellent in the hole position accuracy and the fracture resistance can be further improved.

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

The related drilling tool is provided with two cutting edges 2 at the front end of the tool body 1, and two spiral flutes 3a, 3b are formed on the periphery of the tool body 1 from the tool front end toward the base end side. One of the chip flutes is connected to the middle portion of the other chip flute, and the flutes 3a and 3b are equally twisted from the connecting portions of the flutes 3a and 3b. A drilling tool provided in parallel with an angle, characterized in that the total length of the peripheral direction of the edge 4 is more than 20% of the circumference of the circle of the tool diameter in a range from the front end of the tool toward the axial direction of less than one time of the diameter of the tool. 55% or less, a hard film 5 is provided on the outer peripheral surface of the tool, and the thickness of the hard film 5 is 0.5 μm or more and 10 μm or less in the range of 1 or less of the tool diameter from the tip end of the tool in the axial direction, and the hard film 5 is provided. The thicker the tip end side of the tool, the film thickness T1 of the hard film 5 at the tool leading end side position of the edge 4 and the tool tip from the edge 4 toward the axial direction at twice the tool diameter or twice the tool diameter. The following range of tools on the back end side of the above hard location Film thickness of 5 to T2 ratio T2 / T1 is 0.50 or more and 0.98 or less, more than 20% of the core thickness of the tool W is below 60% of the tool diameter.

Further, the related drilling tool is the drilling tool according to claim 1, wherein the groove length of one of the chip flutes is set to be the groove length of the other chip flute. 50% or more and 97% or less.

Further, the related drilling tool is the drilling tool according to claim 1, wherein the drilling tool has a lower cut shape and an edge. The length is 0.2 mm or more and 1.0 mm or less.

Further, a drilling tool according to the second aspect of the invention is characterized in that the drilling tool has a lower cut shape and an edge length of 0.2 mm or more and 1.0 mm or less.

Further, the related drilling tool is the drilling tool according to any one of claims 1 to 4, wherein the hard film 5 contains at least Al and Cr as a metal component and includes at least N is a metal component.

Further, the related drilling tool is the drilling tool according to any one of the items 1 to 4, wherein the drilling tool comprises the tool body 1 and the tool body. The shank portion 10 of the shank main body 9 having a large diameter is formed. At least the tool body 1 is made of a cemented carbide containing tungsten carbide and cobalt, and has a tool diameter of 0.05 mm or more and 1.0 mm or less.

Further, the related drilling tool is the drilling tool according to claim 5, characterized in that the drilling tool comprises a tool body 1 having the tool body 1 and a larger diameter than the tool body 1. The tool holder portion 10 is configured such that at least the tool body 1 is made of a cemented carbide containing tungsten carbide and cobalt, and has a tool diameter of 0.05 mm or more and 1.0 mm or less.

Further, the boring tool according to the sixth aspect of the invention is characterized in that the shank main body 9 is made of stainless steel, and the front end side of the shank main body 9 is provided at the front end side. The thinner the shank conical portion 8, the at least the vicinity of the shank main body 9 of the shank conical portion 8 is formed of stainless steel.

The boring tool according to the seventh aspect of the invention is characterized in that the shank main body 9 is made of stainless steel, and the front end side of the shank main body 9 is provided at the front end side. The thinner the shank conical portion 8, the at least the vicinity of the shank main body 9 of the shank conical portion 8 is formed of stainless steel.

According to the above configuration, the present invention is a drilling tool which is excellent in practicality in which the hole position accuracy and the fracture resistance can be further improved.

1‧‧‧Tool body

2‧‧‧ cutting edge

3a, 3b‧‧‧

4‧‧‧ edge

5‧‧‧hard film

8‧‧‧ shank cone

9‧‧‧Knife body

10‧‧‧Knife

T1, T2‧‧‧ film thickness

W‧‧‧heart

Fig. 1 is a schematic explanatory view for explaining a deviation of the traveling direction of the drill after the workpiece is entered.

Fig. 2 is a schematic side view showing the embodiment.

Fig. 3 is a schematic explanatory view of the tool body of the embodiment.

Fig. 4 is an enlarged schematic perspective view showing the tool body of the tool rotation phase 0 (Fig. 3 (a)) of Fig. 3;

Fig. 5 is a cross-sectional view taken along line A-A of Fig. 4.

Fig. 6 is a schematic side view showing the main part of the embodiment.

Fig. 7 is a schematic explanatory view for explaining a film forming method.

The embodiments of the present invention which are appropriate in consideration will be briefly described by showing the effects of the present invention.

In the front end of the tool, the length of the peripheral direction of the edge 4 has a sufficient length The durability of the hard film 5 is increased, and the hard film 5 is made thicker at the front end side of the tool with a predetermined film thickness, so that the hard film 5 on the tool front end side is less likely to be worn. Therefore, it is possible to suppress the deviation of the traveling direction of the tool after the workpiece is entered as much as possible, and it is difficult to deteriorate the positional accuracy of the hole.

In addition, the two chip flutes 3a and 3b are connected in parallel (joining) in parallel, and the rigidity of the tool body 1 can be improved as compared with the case where the chip flutes are independently provided, and the positional accuracy of the hole by the hard film 5 can be better exhibited. The deterioration prevents the effect. Further, by setting the groove lengths of the two chip grooves 3a and 3b to the same length, the effect of preventing the deterioration of the hole position accuracy can be sufficiently exerted, but the groove lengths of the two chip grooves 3a and 3b are different from each other. In the case of the length, it is possible to ensure the rigidity of the tool base end side which is likely to be the starting point of the breakage, and the above-described effects can be more satisfactorily improved, and the breakage resistance can be improved.

Moreover, the inner surface portion of the chip grooves 3a and 3b which are not covered with the hard film 5 serves as a portion for compressing, stretching, twisting, etc., which acts on the hard film of the tool during the cutting. Since cracks are prevented from occurring in the hard film 5, it is difficult to deteriorate the resistance of the tool.

Further, by setting the core thickness of the tool to a predetermined size, the rigidity of the tool body 1 can be ensured at this point, and the tolerance against the load such as compression, stretching, and torsion of the hard film coated on the tool can be improved.

[Examples]

Specific embodiments of the invention are illustrated in accordance with the drawings.

In this embodiment, two cutting edges 2 are provided at the front end of the tool body 1, and a peripheral portion of the tool body 1 is formed from the tool front end toward the base end side. Two spiral flutes 3a, 3b are connected to one of the other chip flutes in the middle of the other chip flutes, and the flutes 3a, 3b are from the flutes 3a, The boring tool in which the connection positions (connection portions) of 3b are respectively arranged at the same torsion angle, in the range from the tool front end toward the axial direction within 1 (1D) or less of the tool diameter D, the peripheral direction of the edge 4 The total length is 20% or more and 55% or less of the circumference of the circle of the tool diameter, and the hard surface 5 is provided on the outer surface, and the thickness of the hard film 5 is 0.5 μm in the range of 1 D or less from the tip end of the tool toward the axial direction. 10 μm or less, and the thicker the tool film 5 is, the thicker the tool tip end side is, the film thickness T1 of the hard film 5 at the tool tip end side position of the edge 4 and the tool tip end from the edge 4 toward the axial direction The ratio T2/T1 of the film thickness T2 of the hard film 5 at the tool rear end side position at twice the diameter or twice the tool diameter (2D) or less is 0.50 or more and 0.98 or less, and the heart thickness W of the tool (see the 3(a) Figure) is 20% or more and 60% or less of the diameter of the tool.

Specifically, the above-described drilling tool is a tool main body 1 having spiral flutes 3a and 3b provided on the outer periphery as shown in Figs. 2 and 3, and a knives having a shank main body 9 having a larger diameter than the tool main body 1. A PCB drill bit made of the handle 10. Further, the shank portion 10 is composed of a shank main body 9 having a diameter of 3.175 mm and a shank conical portion 8 which is connected to the distal end side of the shank main body 9 and which is thinner toward the distal end side.

In the above-described drilling tool, at least the tool body 1 is formed of a high-hard alloy member which can be intimately bonded to a hard film 5 which will be described later, which contains tungsten carbide and cobalt, and the shank main body 9 is formed of a stainless steel member, and the two are joined. Composed of. That is, a so-called compound drill bit can reduce its cost. again In the present embodiment, the shank conical portion 8 has a portion near the shank main body 9 made of stainless steel and the other is made of a super hard alloy. That is, the tool body 1 is entirely made of a superhard alloy, and the superhard alloy portion of the tool body 1 and the shank conical portion 8 is an integral superhard alloy member joined to the stainless steel member. Further, the drilling tool may be connected to the intermediate cylindrical portion having a larger diameter at the distal end of the shank conical portion 8 than the tool body 1, and the tool body may be connected to the distal end of the intermediate cylindrical portion. The shape of the second tapered portion which is thinner at the distal end side of the base end, and the joint position of the cemented carbide member and the stainless steel member may be disposed in the shank conical portion 8 as in the present embodiment, or may be disposed in the middle. Cylindrical portion or second conical portion.

Further, the amount of cobalt contained in the above-mentioned cemented carbide member is preferably 3% or more and 15% or less by weight%. Further, the taper angle of the shank conical portion is 30° in this embodiment.

Further, the present invention is particularly effective for a small-diameter drill having a diameter D of 0.05 mm or more and 1.0 mm or less in the tool body 1 which is easily deteriorated by the wear of the tool. The diameter D is the maximum diameter of the hard film 5 provided on the edge 4 (see Fig. 6), and more preferably 0.05 mm or more and 0.6 mm or less. This embodiment is set to 0.3 mm.

Further, the shape of the tool body 1 may be a so-called linear shape that is constant from the distal end side of the tool body 1 toward the proximal end side (see FIG. 6(A)), or the proximal end side may be a small diameter. The so-called undercut shape (see Figure 6(B)).

In the present embodiment, the tool body 1 has an undercut shape, and the axial length l ₂ (edge length) of the distal end side portion having a large diameter is set to be 0.2 mm or more and 1.0 mm or less as compared with the proximal end side. In other words, it is effective to increase the area of the edge 4 in order to improve the durability of the hard film 5. However, if the contact area with the inner wall of the machined hole becomes too large, the inner wall roughness is deteriorated or the cutting resistance is increased and it is easy. The possibility of breakage.

In this regard, the present embodiment is such that the tool body 1 has a lower cut shape so that the contact area between the edge 4 and the inner wall surface of the machined hole becomes smaller (the length of the edge 4 increases in the circumferential direction), and the deterioration of the inner wall roughness can be prevented and reduced. Small cutting resistance. When the edge length is less than 0.2 mm, the wear of the tool becomes easy, and the hole position accuracy is easily deteriorated. Moreover, when it is longer than 1.0 mm, the cutting resistance becomes large and it is easy to cause breakage. Further, the edge length is preferably 0.3 mm or more and 0.9 mm or less. In the present invention, the edge 4 refers to the tool outer surface of the tool body 1 which can be in contact with the inner wall surface of the hole, and the linear outer shape of the tool body 1 as shown in Fig. 6(A), although the tool outer surface of the tool body 1 is The edge portion 4 is synonymous, but in the case of the undercut shape as illustrated in Fig. 6(B), the cylindrical surface (tool peripheral surface) on the proximal end side having a smaller diameter is different from the edge portion 4. In the case where the tool body 1 is provided with a structure of the drill body void, the drill body void is different from the edge 4.

Further, in the present embodiment, a so-called two-blade and two-groove type drill having the two cutting edges 2 and the two chip flutes 3a and 3b provided in point symmetry at the tool leading end position as shown in Figs. In the figure, reference numeral 6 denotes a first discharge surface, and 7 denotes a second discharge surface.

In the present embodiment, in order to ensure the rigidity (the small groove volume) at the root portion, the first chip groove 3a is connected to the middle of the second chip groove 3b. Composition. From the connecting portion to the tool base end side, the helix angles of the respective chip flutes 3a, 3b are set at the same angle, and the respective chip flutes 3a, 3b are arranged in parallel to the predetermined position of the tool base end side (see Fig. 3). The third (a) to (d) diagrams show the front end portion (front end surface, side surface) of Fig. 2 with a rotation phase of 90 degrees.

Specifically, the groove length of the first chip flute 3a is set to be 50% or more and 97% or less of the groove length l of the second chip flute 3b. The groove length of the two chip flutes 3b may be the same, but the length of the two chip ends 3b may be parallel to the predetermined position on the tool base end side, thereby ensuring the rigidity of the base end portion (the root portion) of the tool body 1 which is likely to be the starting point of the breakage. The breakage resistance can be further improved. Further, the groove lengths of the two chip flutes may be reversed, and the groove length of the second chip flute 3b may be set shorter than the groove length of the first chip flute 3a. When the groove length of one of the chip flutes is less than 50% of the groove length of the other chip flute, the volume of the ditch from the intermediate portion of the important groove to the base end becomes smaller due to chip clogging, which may increase the breakage due to chip clogging. When the probability is longer than 97%, the difference in groove length is small, and it is difficult to secure the rigidity of the base portion. In addition, when the groove length of one of the chip flutes is set to 70% or more of the groove length of the other chip flute, the inventors have confirmed that it is for more stable chip evacuation or for a longer life. Stable hole processing. Therefore, it is more preferable to set the groove length of one of the chip flutes to 70% or more and 97% or less of the groove length of the other chip flute.

Further, in the present embodiment, as shown in Figs. 2 to 4, the hard film 5 is not provided on the inner surface of the tool leading end surface and the chip grooves 3a and 3b, and the hard film 5 is provided only on the outer peripheral surface of the tool.

Here, the peripheral surface of the tool refers to the front side of the tool and the chip groove. The outer surface of the tool on the inner side of 3a, 3b. In the case where the tool body 1 is provided with a structure of the drill body void, the drill body void is different from the tool outer surface. That is, as in the case of the linear shape illustrated in Fig. 6(A), the peripheral surface of the tool refers to the edge 4, as in the case of the shape cut under the illustration of Fig. 6(B), the peripheral surface of the tool refers to the edge. 4 and a cylindrical surface on the proximal end side where the diameter becomes smaller, and a hard film 5 is provided on the outer peripheral surface of the tool. That is, in the present embodiment, the hard film 5 is provided on the outer peripheral surface of the tool body 1. However, the base surface of the tool body 1 may be equal to the outer surface of the shank conical portion 8 and the shank main body 9. The outer surface of the tool on the side is provided with a structure of the hard film 5. Further, at least the configuration in which the hard film 5 is provided on the outer peripheral surface of the tool body 1 can obtain the abrasion resistance improving effect by the hard film.

Therefore, the inner surface portion of the chip grooves 3a and 3b which are not covered with the hard film 5 serves as a portion for reducing the load such as compression, stretching, and torsion applied to the hard film of the tool during cutting, and can be prevented. Cracks are generated in the hard film 5. Further, the cutting edge 2 existing at the intersection ridge line portion between the discharge surface of the tool tip and the rake face is not covered by the hard film 5, and a sharp blade edge angle can be formed, and the occlusion property to the workpiece can be improved. Therefore, the positional accuracy of the hole when the workpiece is engaged is improved, and the deviation of the traveling direction of the tool after entering the workpiece can be prevented.

In the present embodiment, a film containing at least Al and Cr as a metal component and at least N as a non-metal component is used as the hard film 5. Although the above hard film 5 can suppress the wear of the tool base material, the film itself is worn together with the processing, so that it is necessary to have a moderate thickness so that it does not disappear within a proper number of times of usual processing. With 0.5μm It is better. On the other hand, when it is too thick, it is easy to peel, and it is preferable that it is 10 micrometer or less. Therefore, in the present embodiment, the hard film 5 is set to have a film thickness in the range of 1 D or less in the axial direction from the tip end of the tool of 0.5 μm or more and 10 μm or less.

In the present embodiment, the total length of the peripheral direction of the edge 4 of the range of 1 D or less from the tip end of the tool toward the axial direction (P1 + P2 of Fig. 5) is the circumference of the circle of the tool diameter (π D, π is the pi) 20% or more and 55% or less (hereinafter, the ratio of the total length of the direction around the edge of the π D is referred to as the edge-to-circumference ratio).

Here, when the edge circumferential ratio becomes large, the film durability of the edge 4 becomes good, and the peripheral wear near the corner of the tip end portion of the tool is difficult, so that the deterioration of the hole position accuracy becomes difficult, but the edge peripheral ratio is larger than π. When 55% of D is used, the cutting resistance is increased and it is easy to be broken. When the thickness is less than 20% of π D, the durability of the film of the edge 4 is deteriorated, and the peripheral wear near the corner of the tip end of the tool becomes easy. This will make the hole position accuracy easy to deteriorate.

Further, the cutting resistance of the drill bit at the front end is increased, and the durability of the film is deteriorated near the corner of the tip end portion of the tool, and the wear is facilitated. Therefore, the hard film 5 is formed into a film having a thickness of the edge 4 on the tool tip end side (the thickness of the tool body 1 is gradually increased from the base side toward the tip end side), and it is easy to suppress the deterioration of the hole position accuracy.

For this reason, the present embodiment is a diagram as shown in Fig. 6, and the film thickness T1 of the hard film 5 of the tool front end side position (corner position of the tool front end portion) L1 of the edge 4 is set toward the tool front end from the edge 4 Axial 2D position or 2D The ratio T2/T1 of the film thickness T2 of the hard film 5 at the tool rear end side position L2 in the following range is 0.50 or more and 0.98 or less. Further, Fig. 6(A) shows an example in which L2 is positioned from the tool front end of the edge 4 toward the axial direction 2D, and Fig. 6(B) is a tool rear end of L2 from the tool front end of the edge 4 toward the axial direction 2D or less. An example of a side position. That is, as shown in Fig. 6(B), the tool axial end of the edge 4 (the rear end of the large diameter portion) is located under the shape of the lower cut from the tip end of the tool toward the axial direction of 2D, and the tool shaft of the above edge 4 is provided. The position to the rear end (the rear end of the large diameter portion) is L2, and the tool axial end of the edge 4 (the rear end of the large diameter portion) is an undercut shape that is positioned from the front end of the tool beyond the axial direction 2D (not shown). In the case of the tool 2D, the position in the axial direction 2D is L2. That is, at this time, the linear shape of the drill of the figure shown in Fig. 6(A) is set to L2.

Here, when T2/T1 is less than 0.50, the shape of the film forming in the radial direction of the tool at the position L1 causes the cutting load to concentrate, and the stress of the film strength or more is generated, and the film is easily damaged in the vicinity. The accuracy of the hole position is deteriorated. When T2/T1 is more than 0.98, the film thickness from the fundamental side to the front end side of the tool main body 1 is substantially constant, or the film thickness is gradually decreased from the fundamental side to the front end side, and the film edge portion of the tool does not have a sufficient film thickness near the corner portion. As a result, the film of the front end portion is deteriorated or worn, and the hole position accuracy is easily deteriorated.

The T2/T1 is, for example, the illustration of Fig. 7, and the jig for holding the drill in the film forming furnace in which the film is formed is formed, and the diameter D of the drill is sufficiently large in the horizontal direction to make the drill bit relative to the jig. The change in the insertion depth can be set as appropriate. Specifically, when the insertion depth of the drill bit is deep, T2/T1 is set to be small (so that the film thickness of T1 of L1 is thick), and when it is shallow, T2/T1 is set to be large. (Lake the film thickness of T1 of L1 to be thin).

Further, in the present embodiment, in order to secure the rigidity of the drill body, the tolerance of the load such as compression, tension, and torsion of the hard film coated on the drill is improved, and the core thickness W of the tool is set to 20% of the tool diameter D. The above 60% or less (hereinafter, the ratio of the core thickness W of the tool with respect to the diameter D of the tool is the thickness-to-diameter ratio). The heart thickness W of the tool is as shown in Fig. 3(a) as the thickness of the front end of the tool. When the core-thickness diameter ratio is less than 20%, the hole position accuracy is deteriorated or broken due to insufficient rigidity. Further, when the core-thickness diameter ratio is more than 60%, the groove volume becomes small, and the inner wall roughness is deteriorated or the chips are clogged, which is easily broken.

The present embodiment is constructed as described above, in which the length of the peripheral direction of the edge 4 is sufficiently long in the front end portion of the tool to enhance the durability of the hard film 5, and the hard film 5 is set to a predetermined thickness so that the front end side of the tool The thicker, the harder the hard film 5 on the front end side of the tool becomes worn. Therefore, it is possible to suppress the deviation of the traveling direction of the tool after entering the workpiece as much as possible, and it is difficult to deteriorate the positional accuracy of the hole.

In addition, the two chip flutes 3a and 3b are connected (joined) in the middle to be parallel to the tool base end side, so that the rigidity of the tool body 1 can be increased, and the deterioration of the positional accuracy of the hole by the hard film 5 can be more effectively exhibited. effect. Moreover, the groove lengths of the two chip grooves 3a and 3b are set to be different, and the rigidity of the tool base end side which is likely to be the breakage starting point can be secured as compared with the case of the same length.

Moreover, the inner surface portion of the chip grooves 3a and 3b which are not covered with the hard film 5 serves as a pressure which acts on the hard film coated on the tool during the gradual cutting. The portion of the load such as shrinkage, stretching, and torsion prevents cracking in the hard film 5.

Further, it is assumed that the core thickness W of the tool is a predetermined size, and the rigidity of the tool body 1 can be ensured at this point, and the tolerance against the load such as compression, stretching, and torsion of the hard film coated on the tool can be improved.

Therefore, this embodiment is a further improved practicality having excellent hole positional accuracy and fracture resistance.

An experimental example for verifying the effects of the present invention will be described.

Tables 1 to 7 are tables showing experimental conditions and experimental results for evaluating the hole position accuracy by changing the shape of the drill bit or the hard film.

Specifically, Table 1 is a two-blade, two-blade, two-blade, two-blade, two-blade, two-blade, two-blade, two-blade, two-blade, two-blade, two-blade, two-blade, two-blade, two-blade A table for comparing the evaluation results of different coated portions of the hard film of the parallel-shaped drill bit in the trench. Table 2 is a table showing the results of the comparison evaluation of the edge circumference ratios. Table 3 is a table showing the results of comparative evaluation of different film thicknesses. Table 4 is a table showing the results of comparative evaluation of different T2/T1. Table 5 is a table showing the results of comparative evaluation of the difference in heart-thickness ratio. Table 6 is a table showing the results of comparative evaluation of the difference in edge length. Table 7 is a table showing the results of comparative evaluation of different tool diameters.

The experiments related to Tables 1 to 5 (Test Nos. 1 to 5) are described in detail.

The drill used in the experiment of Table 1 was a two-blade two-groove normal-shaped drill having a tool diameter D of 0.3 mm and a parallel-shaped drill having two-blade two-grooves to change the coating portion of the hard coating.

The drill used in the experiment of Table 2 is two tools with a diameter D of 0.3 mm. The two grooves of the blade are connected with a parallel-shaped drill bit to change the circumferential ratio of the edge. The heart-thickness diameter ratio is 38% or more and 42% or less.

The drill used in the experiment of Table 3 was a two-blade two-groove with a tool diameter D of 0.3 mm, and a parallel-shaped drill was connected to change the film thickness. Further, T2/T1 is 0.70 or more and 0.88 or less.

The drill used in the experiment of Table 4 was a two-blade two-groove with a tool diameter D of 0.3 mm, and a parallel-shaped drill was connected to change T2/T1. Further, the film thickness is 8.7 μm or more and 9.6 μm or less.

The drill used in the experiment of Table 5 was a two-blade two-groove with a tool diameter D of 0.3 mm, and a parallel-shaped drill was connected to change the core-thickness ratio. The edge circumference ratio is 37% or more and 44% or less.

In addition, in the experiments related to Tables 1 to 5, the groove length of the chip flutes of all the two-blade and two-blade parallel drills was set to 91% of the length of the other chip flute. In addition, in the table, the display of the covered portion column is respectively indicated, and the whole: the tool body 1 is completely covered with a hard film; the tool peripheral surface: in the tool body 1, only the peripheral surface of the tool is covered with a hard film; -: is no Coated (completely without a hard film). Further, the film thickness was measured at the position of L1 of the drill. And the coated drill bit was coated under the same conditions in each experiment.

By the above drill, two pieces of "FR-4 halogen-free material with a thickness of 1.6 mm and 6 layers of copper foil" were laminated, and an aluminum plate (thickness: 0.15 mm) was used as a plate, and a sintered plate (thickness: 1.5 mm) was used as a backing plate. For each of the specifications, 10 drilled holes were performed under predetermined conditions, and hole position accuracy evaluation and damage evaluation experiments were performed. Furthermore, in the hole position accuracy evaluation experiment, the number of revolutions of the drill (mandrel): 120,000 min ^-1 , the feed rate: 1.8 m/min, the rate of rise of the mandrel: 25.4 m/min, and the number of collisions: 10,000, In the damage evaluation experiment, the number of revolutions of the drill (mandrel): 100,000 min ^-1 , the feed rate: 3.0 m/min, the rate of rise of the mandrel: 25.4 m/min, and the number of collisions: 4,000.

The evaluation methods for Tables 1 to 5 are explained. For the positional accuracy of the hole, the Avg.+3s value of the hole position shift amount inside the lowermost substrate of the 10,000 collision processing is described (×: the effect is small (45 μm or more), Δ: the degree of the effect (40 μm or more and 45 μm or less). ), ○: The effect is large (40 μm or less)). The damage count is the number of breaks in 10 out of 4,000 collisions (×: small effect (4 or more), △: degree of effect (2 or more and 4 or less), ○: large effect (less than 2) )).

From the evaluation results, confirm the following points.

The two-blade and two-ditch generally shaped drills have low rigidity, and the hole position accuracy is inferior to that of the two-blade two-groove. Further, even when the two-blade and two-groove grooves are connected in a parallel shape and are not coated, the hole position accuracy is poor when the hard film is coated, and the fracture resistance is deteriorated when the hard film-coated portion and the tool body are integrated. 1).

Further, even if the parallel shape is connected by the two-blade groove, only the hard film is coated on the outer peripheral surface of the tool, so that the edge position ratio is deteriorated, the hole position accuracy is deteriorated, and when the outer diameter is increased, the fracture resistance is deteriorated. In the case where the edge circumferential ratio is 40% or 50%, particularly good results are obtained in the hole positional accuracy and the fracture resistance (Table 2).

Moreover, when the film thickness is 3.9 μm and 9.6 μm, the position of the lifting hole can be obtained. The result of the improvement effect (Table 3).

Further, when T2/T1 was 0.78 or 0.90, the hole positional accuracy was good (Table 4).

Further, when the core thickness diameter ratio is small, the hole position accuracy is deteriorated, and when it is large, the fracture resistance is deteriorated. Good results were obtained with either a 38% or 48% heart-thickness ratio with good hole position accuracy and fracture resistance (Table 5).

As described above, the configuration according to the present embodiment can be confirmed as a configuration in which good hole position accuracy and fracture resistance are obtained.

The experiment related to Table 6 (Test No. 6) is described in detail.

The drill used in the experiment of Table 6 is a two-blade two-groove with a tool diameter D of 0.3 mm and a groove length l (long groove length in two chip grooves) of 5.5 mm. Long l ₂ changes. Further, only the experimental example 8 has a linear shape, and the other is a lower cut shape. The hard film is provided only on the outer peripheral surface of the tool, and has a film thickness of 4.3 μm or more and 5.0 μm or less.

By the above drill, two pieces of "FR-4 halogen-free material with a thickness of 1.6 mm and 6 layers of copper foil" were laminated, and an aluminum plate (thickness: 0.15 mm) was used as a plate, and a sintered plate (thickness: 1.5 mm) was used as a backing plate. For each specification, the hole position accuracy evaluation and the damage evaluation experiment were carried out with 10 pieces, and the hole inner wall roughness evaluation experiment was performed for each specification. Furthermore, in the hole position accuracy evaluation experiment and the hole inner wall roughness evaluation experiment, the number of revolutions of the drill (mandrel): 120,000 min ^-1 , the feed rate: 1.8 m/min, and the rise speed of the mandrel: 25.4 m /min, number of collisions: 10,000, in the damage evaluation experiment, the number of revolutions of the drill (mandrel): 100,000 min ^-1 , feed rate: 3.0 m / min, the rate of rise of the mandrel: 25.4 m / min, the number of collisions : 4,000.

Description of the evaluation method for Table 6. For the positional accuracy of the hole, the Avg.+3s value of the hole position shift amount inside the lowermost substrate of the 10,000 collision processing is described (×: the effect is small (45 μm or more), Δ: the degree of the effect (40 μm or more and 45 μm or less). ), ○: The effect is large (40 μm or less)). Measurement of the inner wall roughness of the hole in the vicinity of the 10,000 collision in the hole inner wall roughness (×: small effect (30 μm or more), Δ: degree of effect (20 μm or more and 30 μm or less), ○: large effect (20 μm or less) )). The damage count is the number of breaks in 10 out of 4,000 collisions (×: small effect (4 or more), △: degree of effect (2 or more and 4 or less), ○: large effect (less than 2) )).

From the evaluation results, it was confirmed that the use of the undercut shape can improve the inner wall roughness and the fracture resistance of the hole. Further, it was confirmed that the edge l ₂ became easy to wear when it was short, and the hole position accuracy was easily deteriorated, and the length and the cutting resistance became large, and the breakage was likely to occur.

From the above description, the undercut shape and the edge length of 0.2 mm or more and 1.0 mm or less which are used in the present embodiment can be confirmed, and a favorable hole positional accuracy, a hole inner wall roughness, and a fracture resistance can be obtained.

The experiment related to Table 7 (Test No. 7) is described in detail.

The drill used in the experiment of Table 7 is a coated drill bit (a hard coated drill bit) and an uncoated drill bit in which a two-blade groove having a variable diameter of the tool is connected in parallel. Moreover, as the diameter of the tool changes, the groove length (the length of the groove on the longer side of the two chip grooves), the length of the edge, and the back of the film also change. The coated drill bit only has a hard film on the outer surface of the tool.

With the above drill bit, the hole position accuracy evaluation experiment and the damage evaluation experiment were performed under the following conditions for each tool diameter.

‧Tool diameter D: 0.05mm

Two sheets of "halogen-free material having a thickness of 0.1 mm and two layers of copper foil" as a base material were stacked, and a resin-attached aluminum plate (thickness: 0.1 mm) was used as a plate, and a sintered plate (thickness: 1.5 mm) was used as a backing plate. In the hole position accuracy evaluation experiment, the number of revolutions of the drill (mandrel): 300,000 min ^-1 , feed rate: 1.5 m/min, the rate of rise of the mandrel: 50.0 m/min, number of collisions: 4,000, damage evaluation experiment In the middle, the number of revolutions of the drill (mandrel): 250,000 min ^-1 , the feed rate: 2.5 m/min, the rate of rise of the mandrel: 50.0 m/min, and the number of collisions: 2,000.

‧Tool diameter D: 0.15mm

Three sheets of "halogen-free material having a thickness of 0.4 mm and two layers of copper foil" as a base material were stacked, and a resin-attached aluminum plate (thickness: 0.1 mm) was used as a plate, and a sintered plate (thickness: 1.5 mm) was used as a backing plate. In the hole position accuracy evaluation experiment, the number of revolutions of the drill (mandrel): 200,000 min ^-1 , feed rate: 2.0 m/min, the rate of rise of the mandrel: 25.4 m/min, number of collisions: 4,000, damage evaluation experiment In the middle, the number of revolutions of the drill (mandrel): 180,000 min ^-1 , the feed rate: 2.6 m/min, the rate of rise of the mandrel: 25.4 m/min, and the number of collisions: 2,000.

‧Tool diameter D: 0.3mm

Two sheets of "FR-4 halogen-free material having a thickness of 1.6 mm and six layers of copper foil" as a substrate were stacked, and an aluminum plate (thickness: 0.15 mm) was used as a plate, and a sintered plate (thickness: 1.5 mm) was used as a backing plate. In the hole position accuracy evaluation experiment, the number of revolutions of the drill bit (mandrel): 120,000 min ^-1 , feed rate: 1.8 m/min, the rate of rise of the mandrel: 25.4 m/min, number of collisions: 6,000, damage evaluation experiment In the middle, the number of revolutions of the drill (mandrel): 100,000 min ^-1 , the feed rate: 3.0 m/min, the rate of rise of the mandrel: 25.4 m/min, and the number of collisions: 4,000.

‧Tool diameter D: 0.6mm

Three sheets of FR-4 halogen-free material having a thickness of 1.6 mm and six layers of copper foil were laminated as a substrate, and an aluminum plate (thickness: 0.2 mm) was used as a plate, and a sintered plate (thickness: 1.5 mm) was used as a backing plate. In the hole position accuracy evaluation experiment, the number of revolutions of the drill bit (mandrel): 75,000 min ^-1 , feed rate: 2.05 m/min, the rate of rise of the mandrel: 25.4 m/min, number of collisions: 4,000, damage evaluation experiment In the middle, the number of revolutions of the drill (mandrel): 40,000 min ^-1 , the feed rate: 3.0 m/min, the rate of rise of the mandrel: 25.4 m/min, and the number of collisions: 2,000.

‧Tool diameter D: 1.0mm

Two sheets of "FR-4 material thickness: 1.5 mm, four-layer copper foil" as a substrate were stacked, and an aluminum plate (thickness: 0.15 mm) was used as a plate, and a sintered plate (thickness: 1.5 mm) was used as a backing plate. In the hole position accuracy evaluation experiment, the number of revolutions of the drill (mandrel): 48,000 min ^-1 , feed rate: 0.96 m/min, the rate of rise of the mandrel: 25.4 m/min, number of collisions: 3,000, damage evaluation experiment In the middle, the number of revolutions of the drill (mandrel): 30,000 min ^-1 , the feed rate: 1.4 m/min, the rate of rise of the mandrel: 25.4 m/min, and the number of collisions: 2,000.

‧Tool diameter D: 1.2mm

Three sheets of "FR-4 material thickness: 1.6 mm two-layer copper foil" as a base material were stacked, and an aluminum plate (thickness: 0.15 mm) was used as a plate, and a sintered plate (thickness: 1.5 mm) was used as a backing plate. In the hole position accuracy evaluation experiment, the number of revolutions of the drill (mandrel): 48,000 min ^-1 , feed rate: 0.96 m/min, the rate of rise of the mandrel: 25.4 m/min, number of collisions: 3,000, damage evaluation experiment In the middle, the number of revolutions of the drill (mandrel): 30,000 min ^-1 , the feed rate: 1.5 m/min, the rate of rise of the mandrel: 25.4 m/min, and the number of collisions: 2,000.

Explain the evaluation method in Table 7. For the hole position accuracy, the difference between the Avg.+3s value of the hole position offset of the uncoated drill bit and the coated drill bit of 10 sets of collision numbers is recorded (no difference in coating) (×: the effect is small (no coating) The layer difference is less than 2 μm), Δ: the degree of effect (no difference in coating layer is 2 μm or more and 4 μm or less), and ○: effect is large (no difference in coating layer is 4 μm or more). For the number of breakages, the number of breakages in the coated drill bit 10 is indicated within the set number of collisions (×: small effect (4 or more), △: degree of effect (2 or more and 4 or less), ○: large effect (2 or less)).

According to the evaluation results, it is confirmed that the tool diameter D is 0.05mm~1.0mm, which can be used to coat the drill bit with respect to the uncoated drill bit. Film lifting hole position accuracy and resistance to breakage).

From the above description, it has been confirmed that the drill having a tool diameter D of 0.05 mm to 1.0 mm can particularly exhibit the effects of the present invention.

1‧‧‧Tool body

3a, 3b‧‧‧

4‧‧‧ edge

5‧‧‧hard film

8‧‧‧ shank cone

9‧‧‧Knife body

10‧‧‧Knife

Claims (9)

A drilling tool is provided with two cutting edges at the front end of the tool body, and two spiral flutes are formed on the outer periphery of the tool body from the tool front end toward the base end side, and one of the above-mentioned chip flutes And being connected to the middle portion of the other of the chip flutes, wherein each of the flutes is a drilling tool that is disposed in parallel at equal twist angles from the connecting portions of the flutes, and is characterized in that: The length of the peripheral direction of the edge is 20% or more and 55% or less of the circumference of the circle of the tool diameter from the front end of the tool toward the axial direction in the range of 1 or less of the diameter of the tool, and a hard film is provided on the outer surface of the tool. The thickness of the hard film is 0.5 μm or more and 10 μm or less in the range of one or less times the tool diameter in the axial direction from the tip end of the tool, and the hard film is set to be thicker toward the tool tip end side, and the hard end of the tool is at the tool tip end side position. The film thickness T1 of the film and the ratio T2 of the film thickness T2 of the hard film at the tool rear end side position from the tool tip end of the edge toward the axial direction at twice the tool diameter or twice the tool diameter. T1 is 0.50 or more 0.98 or less, a thickness of the heart is at least 20% of the tool diameter of the tool 60%. In the drilling tool according to the first aspect of the invention, the groove length of one of the chip flutes is set to be 50% or more and 97% or less of the groove length of the other chip flute. The drilling tool according to claim 1, wherein the drilling tool has a lower cut shape and an edge length of 0.2 mm or more and 1.0 mm. the following. The drilling tool according to claim 2, wherein the drilling tool has a downward shape and an edge length of 0.2 mm or more and 1.0 mm or less. The drilling tool according to any one of claims 1 to 4, wherein the hard film contains at least Al and Cr as a metal component and at least N as a non-metal component. The drilling tool according to any one of claims 1 to 4, wherein the drilling tool comprises a shank portion including the tool body and a shank main body having a larger diameter than the tool body. At least the tool body is made of a superhard alloy containing tungsten carbide and cobalt, and the tool has a diameter of 0.05 mm or more and 1.0 mm or less. The drilling tool according to claim 5, wherein the drilling tool comprises a shank portion having the tool body and a shank main body having a larger diameter than the tool body, and at least the tool body is carbonized. Made of tungsten and cobalt superhard alloy, the tool diameter is 0.05mm or more and 1.0mm or less. The boring tool according to the sixth aspect of the invention, wherein the shank main body is made of stainless steel, and a shank conical portion that is thinner at a distal end side is provided on a distal end side of the shank main body, and the shank conical portion At least the vicinity of the body of the shank is formed of stainless steel. The drilling tool according to claim 7, wherein the shank main body is made of stainless steel, and is provided at a front end side of the shank main body. The closer to the tip end side, the thinner the shank conical portion, and at least the vicinity of the shank main body of the shank conical portion is formed of stainless steel.