JP2014213414A - Drilling tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drilling tool having excellent practicability, which can further improve hole position precision while maintaining breakage resistance and other performance.SOLUTION: In a drilling tool where one or more of spiral chip-discharge grooves 2 directed from a tool tip side to a base end side are formed in an outer periphery of a tool body 1, lands 3 present in a range of one time or less of tool diameter D from the tool tip in the axial direction satisfy the following two conditions: (1) a total of outer peripheral lengths is 20% or more and 60% or less of the circumferential length of a circle with the tool diameter D, (2) the outer peripheral length of a land 3 with the longest outer peripheral length out of the lands 3 is 20% or more and 50% or less of the circumferential length of a circle with the tool diameter D, and further, the land 3 is provided with a hard coating 4 which is thicker toward the tool tip side.

Description

  The present invention relates to a drilling tool.

  In recent years, printed wiring boards (PCBs) have become smaller, thinner, and lighter, and higher heat resistance and higher rigidity have been promoted to improve reliability. Therefore, the resin structure of the glass cloth and the insulating part becomes difficult to cut, and the wear of a drill used for drilling a PCB (hereinafter referred to as a PCB drill) easily progresses accordingly, and the hole position accuracy accompanying the wear is increased. Deterioration is a problem.

  Thus, for example, various drills coated with a hard coating for improving wear resistance as disclosed in Patent Document 1 have been proposed, and the hole position accuracy has been improved, but further drills have been proposed. Improvement is desired.

JP 2012-11489 A

  The present inventors have obtained the following knowledge as a result of various repeated studies on a drill coated with a hard coating in order to further improve the hole position accuracy.

  Factors that cause deterioration in the accuracy of the hole position include the positional deviation when the drill bites into the work material as shown in FIG. 1, and the progress after the drill enters the work material as shown in FIG. Direction misalignment is mentioned. Furthermore, when the wear of the drill progresses due to contact with the work material, the positional deviation when the drill bites into the work material or the advance direction of the drill after entering the work material becomes significant, and the hole position accuracy deteriorates. It becomes easy to do. FIGS. 1 and 2 are examples when a PCB drilled with a PCB drill is drilled with a PCB drill.

  Specifically, misalignment of the drill when it bites into the work material worsens due to a decrease in the bite due to wear of the cutting edge of the drill, the flank and the flank edge (chisel edge), The deviation in the direction of travel after the drill enters the workpiece is due to the so-called front taper, where the outer circumference gradually decreases in diameter toward the tip due to outer wear near the corner where the tool outer periphery and cutting edge of the tool intersect. It is thought that it is getting worse.

  The misalignment of the drill when it bites into the work material can be controlled to some extent by changing the backing plate, but there is still room for improvement in the shape of the drill in addition to changing the backing plate. . In addition, since the deviation of the direction of travel after the drill enters the work material cannot be controlled by changing the backing plate, etc., the influence of the deviation of the direction of travel after entering the work material of the drill is possible by changing the shape of the drill as much as possible. It is necessary to make it smaller.

  The present invention has been completed based on the above knowledge of the inventors and the like, and by providing a hard coating on the land of a predetermined outer circumferential length so as to become thicker toward the tip of the tool, the bite to the work material of the drill Drilling with excellent practicality capable of further improving the hole position accuracy while preventing breakage and other performance while suppressing the deviation of the advancing direction after entering the work material while preventing the position deviation A tool is provided.

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

A drilling tool in which one or a plurality of spiral chip discharge grooves 2 extending from the tool tip toward the base end are formed on the outer periphery of the tool body 1, and the tool diameter D is not more than 1 times the tool diameter D in the axial direction from the tool tip Land 3 in the range of satisfies the following two conditions:
(1) 20% or more and 60% or less of the circumferential length of the circle with the tool diameter D being the total outer circumferential length (2) Among the lands 3, the outer circumferential length of the land 3 having the longest outer circumferential length That is, 20% or more and 50% or less of the circumferential length of the circle of the tool diameter D. Further, the land 3 is provided with a hard coating 4, and the hard coating 4 is thicker toward the tool tip side. This relates to a characteristic drilling tool.

  2. The drilling tool according to claim 1, wherein the film thickness T <b> 1 of the hard coating 4 at the tool tip side position of the land 3 is twice the tool diameter D or the tool diameter in the axial direction from the tool tip of the land 3. A drilling tool characterized in that the ratio T2 / T1 of the film thickness T2 of the hard coating 4 at the tool rear end position in the range of 2 times or less of D is 0.50 or more and 0.98 or less It is.

  The drilling tool according to any one of claims 1 and 2, wherein the hard coating 4 includes at least Al and Cr as metal components and at least N as a nonmetal component, In the axial direction, the film thickness in the range of 1 times or less of the tool diameter D is 1 μm or more and 5 μm or less.

  Further, in the drilling tool according to any one of claims 1 to 3, the drilling tool is characterized in that the number of cutting edges 5 is one.

  Moreover, the drilling tool of any one of Claims 1-4 WHEREIN: The said hard film | membrane 4 is not provided in the tool front end surface, It concerns on the drilling tool characterized by the above-mentioned.

  5. The drilling tool according to claim 1, wherein the hard coating 4 is not provided on a tool tip surface and an inner surface of the chip discharge groove 2. It is related to.

  Further, in the drilling tool according to any one of claims 1 to 6, a plurality of the lands 3 are present in a range of not more than 1 times the tool diameter D in the axial direction from the tool tip, and the plurality of lands 3 provided. Of these, the ratio TW of the film thickness TW of the hard coating 4 provided on the land 3 with the longest outer circumferential length and the film thickness TN of the hard coating 4 provided on the land 3 with the shortest outer circumferential length. / TN is related to a drilling tool characterized by being 0.60 or more and 0.98 or less.

  Further, in the drilling tool according to claim 7, the present invention relates to a drilling tool characterized in that the two lands 3 exist in a range of not more than 1 times the tool diameter D in the axial direction from the tool tip. .

  Further, in the drilling tool according to any one of claims 1 to 8, the tool diameter D is 0.2 mm or more and 1.0 mm or less, and WC and Co are at least from the tip to the chip discharge groove rear end. The present invention relates to a drilling tool characterized by being made of cemented carbide.

  Since the present invention is configured as described above, it is a drilling tool excellent in practicality that can further improve the hole position accuracy while maintaining breakage resistance and other performances.

It is a schematic explanatory drawing explaining the position shift at the time of the biting to the work material of a drill. It is a schematic explanatory drawing explaining the advancing direction shift | offset | difference after the work material approach of a drill. It is a schematic explanatory perspective view of a present Example. It is an expansion perspective view of the front end side of FIG. It is a schematic explanatory front view which shows the structural example of the tool front-end | tip part of a drilling tool. It is AA sectional drawing of FIG. It is a schematic explanatory side view of a present Example. FIG. 8 is a side view schematically illustrating an enlarged main part of FIG. 7 in a simplified manner. It is a schematic explanatory drawing explaining the film-forming method. It is a table | surface which shows an experimental condition and an experimental result. It is a table | surface which shows an experimental condition and an experimental result. It is a table | surface which shows an experimental condition and an experimental result. It is a table | surface which shows an experimental condition and an experimental result.

  An embodiment of the present invention which is considered to be suitable will be briefly described with reference to the drawings showing the operation of the present invention.

  In addition to improving the durability of the hard coating 4 by sufficiently increasing the outer circumferential length of the land 3 at the tool tip, the hard coating 4 on the tool tip side is worn by providing the hard coating 4 thicker toward the tool tip. Even when worn, it is difficult for the tool tip side to gradually decrease in diameter toward the tip of the tool (front taper). Therefore, the front due to outer wear near the corner where the tool outer periphery of the tool tip and the cutting edge intersect is formed. Tapering is favorably suppressed.

  Further, for example, as the hard coating 4, a film containing at least Al and Cr as metal components and at least N as a non-metal component is adopted, and a film in a range of not more than 1 times the tool diameter D in the axial direction from the tool tip. When the thickness is set to 1 μm or more and 5 μm or less, the positional deviation at the time of biting can be improved. Moreover, even when it is set as the structure which does not provide the hard film | membrane 4 in the tool front end surface and the inner surface of the chip | tip discharge groove | channel 2, the position shift at the time of biting can be improved.

  Accordingly, the present invention further improves the hole position accuracy by minimizing the influence of the deviation in the advancing direction after entering the work material of the drill while preventing the position deviation when the drill bites into the work material. Can be achieved.

  Specific embodiments of the present invention will be described with reference to the drawings.

  The present embodiment is a drilling tool in which one or a plurality of spiral chip discharge grooves 2 are formed on the outer periphery of the tool body 1 from the tool tip to the base side, and the tool diameter extends in the axial direction from the tool tip. The total length of one or a plurality of lands 3 existing in the range of 1 or less of D (1D) in the outer circumferential direction is 20% of the circumferential length (πD, π is the circumferential ratio) of the circle having the tool diameter D Of the lands 3, the land 3 having the longest outer circumferential length is 20% to 50% of the πD, and the land 3 is provided with a hard coating 4. The hard coating 4 is thicker toward the tool tip side.

  Specifically, as shown in FIGS. 3 and 4, the drilling tool includes a tool body 1 in which a spiral chip discharge groove 2 is provided on the outer periphery, and a tool base connected to the tool body 1. This is a PCB drill comprising a shank taper portion that gradually increases in diameter toward the end side, and a shank portion that is connected to the shank taper portion and has a diameter of 3.175 mm. The tool body 1 contains WC and Co at least from the tip to the rear end of the chip discharge groove, and is formed of a cemented carbide member that adheres well to the hard coating 4 described later, and the shank portion is formed of a stainless steel member. The two are joined together. The Co content of the cemented carbide member is preferably 3% to 15% by weight. The taper angle of the shank taper portion is 30 ° in this embodiment.

  The diameter D of the tool body 1 (blade part) is the maximum diameter including the hard coating 4 provided on the land 3 (see FIG. 8), and is set to 0.3 mm in this embodiment. The shape of the blade portion of the tool body 1 that does not include the hard coating 4 may be a so-called straight shape (see FIG. 8A) in which the diameter is constant from the distal end side to the proximal end side of the tool body 1. It is good also as what is called an undercut shape (refer FIG.8 (B)) which becomes a step diameter small on the base end side. In addition, as long as the hole position accuracy is easily deteriorated from 0.2 mm to 1.0 mm, the effect of the present invention is particularly exerted similarly to the present embodiment.

  Further, the present embodiment is a so-called one-blade, two-groove drill as shown in FIG. 5A in which one cutting edge is provided and two chip discharge grooves 2 are provided. The land 3 is provided with two lands 3 having a long outer peripheral length and a land 3 having a short outer peripheral length. Specifically, the land 3 on the rear side in the tool rotation direction of the cutting edge 5 has a larger outer peripheral length. It is set long. In this invention, a land refers to the outer peripheral surface which contacts a hole inner wall surface. That is, as shown in FIG. 5B, when the land 3 is provided with the second surface 8, the second surface is not regarded as a land. In the figure, reference numeral 6 is a first flank and 7 is a second flank.

  In the case of a general so-called two-blade, two-groove drill as shown in FIG. 5C, if the length of the land 3 in the outer circumferential direction is increased (when the land 3 is enlarged), the groove volume is reduced accordingly. Therefore, the chip discharge property may deteriorate and the hole inner wall roughness may increase. In this respect, if the shape is one blade, the groove volume with respect to one cutting blade 5 can be sufficiently increased even if the length of the land 3 in the outer circumferential direction is increased, and good chip discharge performance can be obtained. As a result, the inner wall roughness of the hole is improved. 5A and 5B, since the two lands maintain the balance and stably bite the work material, the drill as shown in FIG. 5D is used. The biting property can be further improved as compared with a general so-called 1-blade 1-groove shape in which there is a single cutting edge 5 and one chip discharge groove 2 is provided.

  Further, in the present embodiment, the hard coating 4 is not provided on the tool tip surface (first flank 6 and second flank 7) and the inner surface of the chip discharge groove 2, as shown in FIGS. In addition, the configuration is provided only on the land 3. Therefore, the cutting edge existing at the intersection ridge line portion between the flank and the rake face at the tip of the tool is not covered with the hard coating 4, the blade angle can be sharpened, and the biting property to the work material is improved accordingly. Therefore, the hole position accuracy at the time of biting on the work material becomes good. In addition, the case where the hard coating 4 is provided on the tool front end surface and the inner surface of the chip discharge groove 2 is also within the scope of the present invention. In this case, since the entire tool is covered with the hard coating 4, the wear resistance is low. Although improved, fine metal particles called droplets in the hard coating 4 are present on the inner surface of the chip discharge groove 2, and chip discharge performance deteriorates. Further, the hard coating on the flank and rake surface of the tool tip 4, the cutting tool angle becomes dull and the cutting resistance increases, so that the possibility of breakage during drilling is slightly higher than when the hard coating 4 is not provided on the tip surface of the tool and the inner surface of the chip discharge groove 2. Further, since the blade angle becomes dull, it is easy to cause positional deviation when biting on the work material, and the hole position is compared with the case where the hard coating 4 is not provided on the tool tip surface and the inner surface of the chip discharge groove 2. The accuracy is a little worse.

  In the present embodiment, a hard coating 4 is used that contains at least Al and Cr as metal components and at least N as non-metal components. Such a hard coating 4 suppresses the wear of the tool base material, but the coating itself is worn with processing, so that an appropriate thickness is required and is desirably 1 μm or more. On the other hand, if it is too thick, the sharp edge of the cutting edge and chisel edge will be lost when the hard coating 4 is also provided on the tool tip surface and the inner surface of the chip discharge groove 2, resulting in misalignment of the work material. Since it becomes easy, it is desirable that it is 5 micrometers or less. Accordingly, the hard coating 4 is set so that the film thickness in the range of 1D or less in the axial direction from the tool tip is 1 μm or more and 5 μm or less.

  In the present embodiment, the total length of one or a plurality of lands 3 existing in the axial direction from the tool tip in the range of 1D or less is 20% or more and 60% or less of πD, and two lands 3 are provided. Among them, the land 3 having a long outer peripheral length is set so that the outer peripheral length of the land 3 is 20% or more and 50% or less of πD.

  Here, when the total length in the outer peripheral direction of each land 3 is increased, the film durability of the land 3 is improved, and the peripheral wear near the corner of the tool tip portion is less likely to progress, and the hole position accuracy is less likely to deteriorate. However, if the total length of the lands 3 in the outer circumferential direction is longer than 60% of πD, the cutting resistance increases and breaks easily, and if it is shorter than 20% of πD, the film durability of the land 3 is greater. As a result, the peripheral wear near the corner of the tool tip tends to progress and the hole position accuracy tends to deteriorate. Further, when the outer circumferential direction length of the land 3 having the longest outer circumferential direction length is longer than 50% of πD, it is easy to break for the same reason as above, and when it is shorter than 20% of πD, the same as above. For this reason, the hole position accuracy tends to deteriorate.

  The present embodiment has the shape of one blade and two grooves as described above. As shown in FIG. 4, there are two lands 3 in the range of 1D or less in the axial direction from the tool tip, and the outer periphery of the two lands 3. The total length in the direction is set to 43% of πD, and the length in the outer peripheral direction of the land 3 having a long length in the outer peripheral direction is set to 33% of πD. As described above, in the present embodiment, the outer circumferential direction length of the land 3 on the rear side in the tool rotation direction of the cutting edge 5 is set longer. In this case, since the rigidity can be secured by supporting the cutting edge 5 with the land 3 having a long length in the outer peripheral direction and the deflection of the tool can be suppressed, deterioration of the hole position accuracy can be prevented.

  In addition, since the drill receives a cutting force more strongly at the tip portion, the durability of the coating is deteriorated near the corner of the tool tip portion, and wear tends to progress. Therefore, the hard coating 4 formed thicker as the land 3 on the tip side of the tool (provided that the film thickness gradually increases from the base side to the tip side of the tool body 1) suppresses the deterioration of the hole position accuracy. Cheap.

  Therefore, in this embodiment, as shown in FIG. 7, the film thickness T1 of the hard film 4 at the tool tip side position (corner position of the tool tip portion) L1 of the land 3 and the tool tip of the land 3 in the axial direction. The ratio T2 / T1 of the film thickness T2 of the hard coating 4 at the tool rear end position L2 in the range of 2 times the tool diameter (2D) or 2D or less is set to be 0.50 or more and 0.98 or less. Yes. Note that the film thicknesses T1 and T2 in FIG. 7 roughly indicate that the film thickness is provided so as to gradually increase from the base side to the tip side of the tool body 1. Specifically, as shown in FIG. 8, FIG. 8A shows an example in which L2 is 2D in the axial direction from the tool tip of the land 3, and FIG. 8B shows L2 in the axial direction from the tool tip of the land 3. 2 is an example of the tool rear end side position within a range of 2D or less. When there are a plurality of lands 3 in the range of 1D or less in the axial direction from the tool tip, the value of T2 / T1 is set for each land 3.

  Here, when T2 / T1 is smaller than 0.5, the coating protrudes in the tool radial direction at the position L1, and the cutting load is concentrated, and stress exceeding the coating strength is generated. On the other hand, the film tends to be lost, and the hole position accuracy is deteriorated. When T2 / T1 is larger than 0.98, the film thickness is almost constant from the root side to the tip side of the tool body 1 or gradually decreases from the root side to the tip side. There is no sufficient film thickness in the vicinity of the corner of the tip, and the durability of the coating at the tip is deteriorated and wear tends to progress, and the hole position accuracy is likely to deteriorate.

  For example, as shown in FIG. 9, T2 / T1 is set so that the jig holding the drill in the film forming furnace for forming the film is sufficiently large in the horizontal direction with respect to the diameter D of the drill. It can be set as appropriate by changing the insertion depth of the drill. Specifically, T2 / T1 can be reduced by increasing the insertion depth of the drill (the thickness of T1 in L1 can be increased), and T2 / T1 can be increased by decreasing the depth (the thickness of T1 in L1 can be reduced). .

  Further, when a plurality of the chip discharge grooves 2 are provided, the durability of the film is deteriorated in the land 3 having the shortest outer circumferential length, and the hole position accuracy is deteriorated. That is, since the wear of the shortest land 3 progresses with respect to the land 3 having the longest length in the outer peripheral direction, the wear at which the base material of the tool is exposed becomes conspicuous in the shortest land 3 and is in a partially reduced state. As a result, the contact between the work material and the respective lands 3 becomes unbalanced, and the influence of the deviation in the advancing direction after the drill enters the work material becomes large, and the hole position accuracy deteriorates.

  Therefore, the film thickness TW of the hard coating 4 provided on the land 3 having the longest length in the outer circumferential direction among the plurality of lands 3 existing in the axial direction from the tool tip in a range of not more than 1 times the tool diameter D, It is preferable to set the ratio TW / TN of the film thickness TN of the hard coating 4 provided on the land 3 having a short length in the outer circumferential direction to be 0.60 or more and 0.98 or less.

  In the present embodiment, as shown in FIG. 6, the film thickness TW of the hard coating 4 provided on the land 3 having an outer circumferential length P1 in the axial direction of 1D or less from the tool tip and the outer circumference shorter than P1. The ratio TW / TN of the film thickness TN of the hard coating 4 provided on the land 3 of the direction length P2 is set to be 0.60 or more and 0.98 or less. Although not shown, even if there are three or more lands 3 in a range of 1D or less in the axial direction from the tip of the tool, the film thickness of the hard coating 4 provided on the land 3 having the longest length in the outer circumferential direction. TW, and the film thickness of the hard coating 4 provided on the land 3 having the shortest length in the outer circumferential direction may be set to TN.

  Here, when TW / TN is smaller than 0.6, the cutting load is concentrated on the land having a short length in the outer peripheral direction, and the wear of the film tends to proceed or the film is likely to be lost. The hole position accuracy deteriorates, and when it is larger than 0.98, the durability of the film tends to deteriorate in the land having a short outer peripheral length, and the hole position accuracy tends to deteriorate. .

  The TW / TN is formed, for example, by forming a hard film 4 with a constant film thickness on the entire drill blade, and then forming a land 3 with the shortest outer peripheral length in the land 3 within a range of 1D from the tool tip. It can be made smaller by performing the film formation process by setting it so as to face the direction of the metal evaporation source in the furnace (the TN can be made thicker), and the land 3 having the longest peripheral direction length is the direction of the metal evaporation source. It can be increased by installing the film so that it faces and the film forming process can be performed (the TN can be reduced).

  Since the present embodiment is configured as described above, the length of the land 3 in the outer peripheral direction is sufficiently increased at the tool tip to improve the durability of the hard coating 4, and the hard coating 4 is provided thicker toward the tool tip. As a result, the hard coating 4 on the tool tip side is not easily worn, and even if worn, the outer periphery is less likely to have a gradually reduced outer diameter. It will be suppressed well.

  Therefore, the present embodiment prevents the positional deviation at the time of drill biting on the work material while minimizing the influence of the deviation in the traveling direction after entering the work material of the drill as much as possible. It is possible to further improve the hole position accuracy while maintaining the performance.

  An experimental example supporting the effect of the present embodiment will be described.

  FIGS. 10-13 is a table | surface which shows the experimental conditions and experimental result which changed the drill shape, the structure of the land 3, and the structure of the hard membrane | film | coat 4, and evaluated the hole position accuracy. The details of FIGS. 10 to 13 will be described. FIG. 10 is a diagram of comparative evaluation results of various drill shapes and differences in the outer circumferential length of the land, FIG. 11 is a diagram of comparative evaluation results of differences in T2 / T1, and FIG. FIG. 13 is a diagram of comparative evaluation results for differences in TN, and FIG. 13 is a diagram of comparative evaluation results for differences in drill size.

  The drill used in the experiment of FIG. 10 is a two-blade two-groove drill having a tool diameter D of 0.3 mm and a groove length l of 6.5 mm, a one-blade one-groove drill, and a one-blade two-groove drill. Various changes are made. The circumferential ratio (%) in the figure represents the ratio of the total outer circumferential length of the land to πD and the outer circumferential length of the land having the longest outer circumferential length. Further, the basic shapes such as the tip angle and the twist angle are the same, but the groove depth of one blade shape is 10% deeper than the two blade shape. In the figure, the display of the coating part column indicates that the entire surface is coated on the entire blade portion, the groove inner surface, the land is uncoated on the tip surface, and the land is only uncoated on the groove inner surface and tip surface. Moreover, not only a coated drill provided with a hard coating in each sample but also an uncoated drill (no hard coating provided) is evaluated. The film thickness of the hard coating was 2 μm at T2, and T2 / T1 was 0.65 or more and 0.75 or less. No. About 7-13, TW / TN was 0.76 or more and 0.85 or less.

  In addition, No. No. 13 is an example in which the second face is provided on the land on the rear side in the tool rotation direction of the cutting edge.

  Using the above drill, 4 sheets of “FR-4 halogen-free material, thickness 1.2 mm, 6-layer copper foil” as a base material are stacked, an aluminum plate (thickness 0.2 mm) as a backing plate, and a bake plate ( Drilling experiment with 10 holes for each specification at a drill (spindle) speed of 120 krpm, feed rate: 3.0 m / min, spindle lift rate: 25.4 m / min. Went.

  The evaluation method in FIGS. 10-13 is demonstrated. Regarding the number of breaks, FIGS. 10 to 12 show the number of breaks in 10 in the 6,000 hit processing, and FIG. 13 shows the number of breaks in 10 within the set number of hits. Regarding the hole position accuracy, in FIGS. 10 to 12, the Avg. +3 s value is Avg. Of the hole position deviation amount on the back side of the bottom substrate of 10 set hit numbers in FIG. +3 s values are listed. Note that the number of broken holes was not measured, and the number of broken holes where the number of broken lines was less than 10 was recorded as the number of holes that were not broken. Also, the Avg. The effect of the hard coating was confirmed by the difference in the + 3s value (non-coating difference) (◯: large effect, x: small effect (non-coating difference is 1 μm or less)). In addition, the hole inner wall roughness was evaluated by confirming the appearance of the five hole inner walls in the vicinity of 6,000 hits in FIG. 10 (◯: hole inner wall roughness less than 25 μm, Δ: hole inner wall roughness 25 μm) In FIG. 13, evaluation was made by confirming the appearance of the inner wall of the five holes near the set hit (◯: hole inner wall roughness is less than 15 μm, Δ: hole inner wall roughness is 15 μm). Less, but relatively bad in appearance). Further, in FIG. 11, the film defect is confirmed by confirming the appearance of the film state near the corner after 6,000 hits in FIG. 11, and in FIG. 12, the film state of the land having a short outer peripheral length after 6,000 hits. Was evaluated by confirming the appearance (◯: the film was not missing, ×: the film was missing). In addition, film abrasion is confirmed by confirming the appearance of the state of the film near the corner after 6,000 hits in FIG. 11, and in FIG. 12, the film state of the land having a short outer peripheral length after 6,000 hits. Was evaluated by confirming its appearance (O: wear of the film was not noticeable, x: wear of the film was remarkable,-: wear was not confirmed due to film defect).

  From the evaluation results, the following points were confirmed.

  The two-blade, two-groove shape is not easily broken, and the hole position accuracy is somewhat improved by the coating, but the inner wall roughness tends to be deteriorated when the outer peripheral length of the land is increased. In addition, the single-blade, single-groove shape has a great effect of hard film coating, so the hole position accuracy is good and the hole inner wall roughness is not bad, but it is easy to break even if the outer peripheral length of the land is within the preferred range. Tend. In addition, since the 1-blade 2-groove shape has good bite to the work material, the hole position accuracy is good, the effect of the hard coating is great, and the hole inner wall roughness is also good.

  Further, in the case where a coating is provided on the inner surface of the groove and the land (No. 10 in FIG. 10) with one blade and two grooves, or in the case where a coating is provided only on the land (No. 11 in FIG. 10), In addition to the effect of the drill shape, there was no tendency to break because the coating was not provided on the tip surface or on the tip surface and the groove inner surface. In the case of a 1-flute 2-groove shape with a second surface on the land (No. 13 in FIG. 10), the hole position accuracy is the best among the same shape, it is difficult to break, and the hole inner wall roughness is also Good results were obtained.

  From the above, it was confirmed that the best results were obtained when a film was provided only on the land with a one-blade, two-groove shape.

  The drill used in the experiment of FIG. 11 has a tool diameter D of 0.3 mm and a groove length l of 6.5 mm. 9 is a drill having the same shape as 9. Each sample is evaluated not only for coated drills with a hard coating but also for non-coated drills. The film thickness of the hard coating was 2 μm at T2, and T2 / T1 was changed. Moreover, TW / TN was set to 0.76 or more and 0.88 or less.

  Using the above drill, 4 sheets of “FR-4 halogen-free material, thickness 1.2 mm, 6-layer copper foil” as a base material are stacked, an aluminum plate (thickness 0.2 mm) as a backing plate, and a bake plate ( Drilling experiment with 10 holes for each specification at a drill (spindle) speed of 120 krpm, feed rate: 3.0 m / min, spindle lift rate: 25.4 m / min. Went.

  From the evaluation results, it was confirmed that when T2 / T1 is small, film defects near the corner are conspicuous. Moreover, when T2 / T1 was large, it was confirmed that the abrasion of the film near the corner was conspicuous.

  From the above, it is considered that T2 / T1 is preferably 0.50 or more and 0.98 or less.

  The drill used in the experiment of FIG. 12 has a tool diameter D of 0.3 mm and a groove length l of 6.5 mm. 9 is a drill having the same shape as 9. Each sample is evaluated not only for coated drills with a hard coating but also for non-coated drills. The film thickness of the hard coating was 2.8 μm in TW, and TW / TN was changed. Further, T2 / T1 was set to 0.65 or more and 0.75 or less.

  Using the above drill, 4 sheets of “FR-4 halogen-free material, thickness 1.2 mm, 6-layer copper foil” as a base material are stacked, an aluminum plate (thickness 0.2 mm) as a backing plate, and a bake plate ( Drilling experiment with 10 holes for each specification at a drill (spindle) speed of 120 krpm, feed rate: 3.0 m / min, spindle lift rate: 25.4 m / min. Went.

  From the evaluation results, it was confirmed that when TW / TN is small, the film defect of the land having a short length in the outer peripheral direction is conspicuous. Moreover, when TW / TN was large, it was confirmed that the abrasion of the land having a short length in the outer circumferential direction was conspicuous.

  From the above, it was confirmed that TW / TN is not preferably at least 0.51 or less or 1.17 or more.

  The drill used in the experiment of FIG. 13 is a two-blade two-groove drill and a one-blade two-groove drill with a tool diameter D of 0.1 mm and a groove length l of 2.2 mm, a tool diameter D of 0.2 mm, and a groove length. 1-blade 2-groove drill with l of 3.5 mm, 2-blade 2-groove drill and 1-blade 2-groove drill with a tool diameter D of 0.6 mm and a groove length l of 8.5 mm, and a tool diameter D of 1.0 mm A two-blade two-groove drill with a groove length l of 9.0 mm, and a two-blade two-groove drill with a tool diameter D of 1.1 mm and a groove length l of 9.0 mm. The hard coating is provided on the entire blade portion. Moreover, not only the coated drill which provided the hard film | membrane in each sample but the non-coated drill is evaluated.

  Using the above drills, drilling experiments were performed for each tool diameter D under the following conditions.

・ Tool diameter D: 0.1 mm
Three sheets of “halogen-free material 0.4 mm thick 2-layer copper foil” as a base material are stacked, an aluminum plate with resin (thickness 0.1 mm) as a backing plate, and a bake plate (thickness 1.5 mm) as a discard plate 6,000 hit holes are drilled for each of the specifications at a drill (spindle) rotational speed of 330 krpm, a feed rate of 2.4 m / min, and a spindle ascending speed of 50.0 m / min.

・ Tool diameter D: 0.2mm
"FR-4 material 1.2mm thickness 6 layer copper foil" as a base material is piled up, aluminum plate with resin (thickness 0.17mm) as a backing plate, bake plate (thickness 1.5mm) as a discard plate ), 3,000 hit holes are drilled in units of 10 at a drill (spindle) rotation speed of 180 krpm, a feed rate of 2.4 m / min, and a spindle lift rate of 25.4 m / min.

・ Tool diameter D: 0.6mm
Three sheets of “FR-4 material 1.6mm thickness 6 layer copper foil” as a base material are stacked, an aluminum plate (thickness 0.2mm) as a backing plate, and a bake plate (thickness 1.5mm) as a discard plate Using a drill (spindle) rotation speed: 75 krpm, feed speed: 2.05 m / min, spindle ascending speed: 25.4 m / min.

・ Tool diameter D: 1.0mm
Three sheets of “FR-4 material, 1.5mm thickness, 4 layer copper foil” as a base material are stacked, an aluminum plate (thickness 0.15 mm) as a backing plate, and a bake plate (thickness 1.5 mm) as a discard plate 2,000 hit holes are drilled in units of 10 at a drill (spindle) rotation speed of 48 krpm, a feed speed of 0.96 m / min, and a spindle lift speed of 25.4 m / min.

・ Tool diameter D: 1.1 mm
Three sheets of “FR-4 material 1.6mm thickness 2-layer copper foil” as a base material are stacked, an aluminum plate (thickness 0.15 mm) as a backing plate, and a bake plate (thickness 1.5 mm) as a discard plate 2,000 hit holes are drilled in units of 10 at a drill (spindle) rotation speed of 48 krpm, a feed speed of 0.96 m / min, and a spindle lift speed of 25.4 m / min.

  From the evaluation results, it was confirmed that a drill with a tool diameter D of 0.1 mm or 1.1 mm has a small wear resistance effect of the hard coating.

  From the above, it was confirmed that the effect of the present invention was particularly exhibited with a drill having a tool diameter D of 0.2 mm to 1.0 mm.

1 Tool body 2 Chip discharge groove 3 Land 4 Hard coating 5 Cutting edge D Tool diameter

  The present invention relates to a drilling tool.

  In recent years, printed wiring boards (PCBs) have become smaller, thinner, and lighter, and higher heat resistance and higher rigidity have been promoted to improve reliability. Therefore, the resin structure of the glass cloth and the insulating part becomes difficult to cut, and the wear of a drill used for drilling a PCB (hereinafter referred to as a PCB drill) easily progresses accordingly, and the hole position accuracy accompanying the wear is increased. Deterioration is a problem.

  Thus, for example, various drills coated with a hard coating for improving wear resistance as disclosed in Patent Document 1 have been proposed, and the hole position accuracy has been improved, but further drills have been proposed. Improvement is desired.

JP 2012-11489 A

  The present inventors have obtained the following knowledge as a result of various repeated studies on a drill coated with a hard coating in order to further improve the hole position accuracy.

  Factors that cause deterioration in the accuracy of the hole position include the positional deviation when the drill bites into the work material as shown in FIG. 1, and the progress after the drill enters the work material as shown in FIG. Direction misalignment is mentioned. Furthermore, when the wear of the drill progresses due to contact with the work material, the positional deviation when the drill bites into the work material or the advance direction of the drill after entering the work material becomes significant, and the hole position accuracy deteriorates. It becomes easy to do. FIGS. 1 and 2 are examples when a PCB drilled with a PCB drill is drilled with a PCB drill.

  Specifically, misalignment of the drill when it bites into the work material worsens due to a decrease in the bite due to wear of the cutting edge of the drill, the flank and the flank edge (chisel edge), The deviation in the direction of travel after the drill enters the workpiece is due to the so-called front taper, where the outer circumference gradually decreases in diameter toward the tip due to outer wear near the corner where the tool outer periphery and cutting edge of the tool intersect. It is thought that it is getting worse.

  The misalignment of the drill when it bites into the work material can be controlled to some extent by changing the backing plate, but there is still room for improvement in the shape of the drill in addition to changing the backing plate. . In addition, since the deviation of the direction of travel after the drill enters the work material cannot be controlled by changing the backing plate, etc., the influence of the deviation of the direction of travel after entering the work material of the drill is possible by changing the shape of the drill as much as possible. It is necessary to make it smaller.

The present invention has been completed on the basis of the above knowledge of the inventors and the like, and when a hard coating is provided so as to become thicker toward the tool tip side in a margin of a predetermined outer circumferential direction length, Drilling with excellent practicality capable of further improving the hole position accuracy while preventing breakage and other performance while suppressing the deviation of the advancing direction after entering the work material while preventing the position deviation A tool is provided.

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

A drilling tool in which one or a plurality of spiral chip discharge grooves 2 extending from the tool tip toward the base end are formed on the outer periphery of the tool body 1, and the tool diameter D is not more than 1 times the tool diameter D in the axial direction from the tool tip A plurality of margins 3 are provided in the range of , and this margin 3 satisfies the following two conditions:
(1) 20% or more and 60% or less of the circumferential length of the circle with the tool diameter D being the total circumferential length (2) Among the margins 3, the circumferential length of the margin 3 having the longest circumferential length of the above tool diameter D 20% to 50% addition of the circumference length of a circle, it said margin 3 hard film 4 is provided, the hard film 4 is provided so thick as the tool tip side, further Of the plurality of margins 3, the film thickness TW of the hard coating 4 provided in the margin 3 having the longest outer circumferential length and the hard coating 4 provided in the margin 3 having the shortest outer circumferential length. The ratio TW / TN of the film thickness TN is 0.60 or more and 0.98 or less .

Further, in the drilling tool according to claim 1, wherein a thickness T1 of the hard film 4 of the tool tip end position of the margin 3, 2 times or tool diameter of the tool diameter D in the axial direction from the tool tip of the margin 3 A drilling tool characterized in that the ratio T2 / T1 of the film thickness T2 of the hard coating 4 at the tool rear end position in the range of 2 times or less of D is 0.50 or more and 0.98 or less It is.

  The drilling tool according to any one of claims 1 and 2, wherein the hard coating 4 includes at least Al and Cr as metal components and at least N as a nonmetal component, In the axial direction, the film thickness in the range of 1 times or less of the tool diameter D is 1 μm or more and 5 μm or less.

  Further, in the drilling tool according to any one of claims 1 to 3, the drilling tool is characterized in that the number of cutting edges 5 is one.

  Moreover, the drilling tool of any one of Claims 1-4 WHEREIN: The said hard film | membrane 4 is not provided in the tool front end surface, It concerns on the drilling tool characterized by the above-mentioned.

  5. The drilling tool according to claim 1, wherein the hard coating 4 is not provided on a tool tip surface and an inner surface of the chip discharge groove 2. It is related to.

The drilling tool according to any one of claims 1 to 6 , wherein the two margins 3 exist in a range of not more than 1 times the tool diameter D in the axial direction from the tool tip. It concerns tools.

  Further, in the drilling tool according to any one of claims 1 to 7, the tool diameter D is 0.2 mm or more and 1.0 mm or less, and WC and Co are at least from the tip to the rear end of the chip discharge groove. The present invention relates to a drilling tool characterized by being made of cemented carbide.

  Since the present invention is configured as described above, it is a drilling tool excellent in practicality that can further improve the hole position accuracy while maintaining breakage resistance and other performances.

It is a schematic explanatory drawing explaining the position shift at the time of the biting to the work material of a drill. It is a schematic explanatory drawing explaining the advancing direction shift | offset | difference after the work material approach of a drill. It is a schematic explanatory perspective view of a present Example. It is an expansion perspective view of the front end side of FIG. It is a schematic explanatory front view which shows the structural example of the tool front-end | tip part of a drilling tool. It is AA sectional drawing of FIG. It is a schematic explanatory side view of a present Example. FIG. 8 is a side view schematically illustrating an enlarged main part of FIG. 7 in a simplified manner. It is a schematic explanatory drawing explaining the film-forming method. It is a table | surface which shows an experimental condition and an experimental result. It is a table | surface which shows an experimental condition and an experimental result. It is a table | surface which shows an experimental condition and an experimental result. It is a table | surface which shows an experimental condition and an experimental result.

  An embodiment of the present invention which is considered to be suitable will be briefly described with reference to the drawings showing the operation of the present invention.

The length of the margin 3 in the outer peripheral direction at the tool tip is sufficiently increased to improve the durability of the hard coating 4, and the hard coating 4 on the tool tip side is worn by providing the hard coating 4 thicker toward the tool tip. Even when worn, it is difficult for the tool tip side to gradually decrease in diameter toward the tip of the tool (front taper). Therefore, the front due to outer wear near the corner where the tool outer periphery of the tool tip and the cutting edge intersect is formed. Tapering is favorably suppressed.

  Further, for example, as the hard coating 4, a film containing at least Al and Cr as metal components and at least N as a non-metal component is adopted, and a film in a range of not more than 1 times the tool diameter D in the axial direction from the tool tip. When the thickness is set to 1 μm or more and 5 μm or less, the positional deviation at the time of biting can be improved. Moreover, even when it is set as the structure which does not provide the hard film | membrane 4 in the tool front end surface and the inner surface of the chip | tip discharge groove | channel 2, the position shift at the time of biting can be improved.

  Accordingly, the present invention further improves the hole position accuracy by minimizing the influence of the deviation in the advancing direction after entering the work material of the drill while preventing the position deviation when the drill bites into the work material. Can be achieved.

  Specific embodiments of the present invention will be described with reference to the drawings.

The present embodiment is a drilling tool in which one or a plurality of spiral chip discharge grooves 2 are formed on the outer periphery of the tool body 1 from the tool tip to the base side, and the tool diameter extends in the axial direction from the tool tip. The sum of the circumferential lengths of one or more margins 3 existing in a range equal to or less than 1 (1D) of D is 20% of the circumferential length of the circle with the tool diameter D (πD, π is the circumferential ratio) The marginal length of the margin 3 having the longest length in the circumferential direction is 20% or more and 50% or less of the πD, and the hard coating 4 is provided on the margin 3. The hard coating 4 is thicker toward the tool tip side.

  Specifically, as shown in FIGS. 3 and 4, the drilling tool includes a tool body 1 in which a spiral chip discharge groove 2 is provided on the outer periphery, and a tool base connected to the tool body 1. This is a PCB drill comprising a shank taper portion that gradually increases in diameter toward the end side, and a shank portion that is connected to the shank taper portion and has a diameter of 3.175 mm. The tool body 1 contains WC and Co at least from the tip to the rear end of the chip discharge groove, and is formed of a cemented carbide member that adheres well to the hard coating 4 described later, and the shank portion is formed of a stainless steel member. The two are joined together. The Co content of the cemented carbide member is preferably 3% to 15% by weight. The taper angle of the shank taper portion is 30 ° in this embodiment.

The diameter D of the tool body 1 (blade part) is the maximum diameter including the hard coating 4 provided on the margin 3 (see FIG. 8), and is set to 0.3 mm in this embodiment. The shape of the blade portion of the tool body 1 that does not include the hard coating 4 may be a so-called straight shape (see FIG. 8A) in which the diameter is constant from the distal end side to the proximal end side of the tool body 1. It is good also as what is called an undercut shape (refer FIG.8 (B)) which becomes a step diameter small on the base end side. In addition, as long as the hole position accuracy is easily deteriorated from 0.2 mm to 1.0 mm, the effect of the present invention is particularly exerted similarly to the present embodiment.

Further, the present embodiment is a so-called one-blade, two-groove drill as shown in FIG. 5A in which one cutting edge is provided and two chip discharge grooves 2 are provided. Margin 3 are two of the peripheral direction length long margin 3 and the outer circumferential direction shorter lengths margin 3 is provided, in particular, more of the outer peripheral length of the margin 3 of the tool rotation direction rear side of the cutting edge 5 It is set long. In the present invention, the margin refers to the outer peripheral surface that contacts the inner wall surface of the hole. That is, as shown in FIG. 5B, when the tool body 1 is provided with the second picking surface 8, the second picking surface is not regarded as a margin . In the figure, reference numeral 6 is a first flank and 7 is a second flank.

In the case of drilling a typical so-called two-blade 2 groove shape as shown in FIG. 5 (C), the longer the outer peripheral length of the margin 3 (A larger margin 3), correspondingly the groove volume is small Therefore, the chip discharge property may deteriorate and the hole inner wall roughness may increase. In this respect, if the shape is one blade, the groove volume with respect to one cutting blade 5 can be sufficiently increased even if the length of the margin 3 in the outer circumferential direction is increased, and good chip discharge performance can be obtained. As a result, the inner wall roughness of the hole is improved. 5A and 5B, since the two margins keep the balance and stably bite the work material, as shown in FIG. 5D. The biting property can be further improved as compared with a general so-called 1-blade 1-groove shape in which there is a single cutting edge 5 and one chip discharge groove 2 is provided.

Further, in the present embodiment, the hard coating 4 is not provided on the tool tip surface (first flank 6 and second flank 7) and the inner surface of the chip discharge groove 2, as shown in FIGS. Further, only the margin 3 is provided. Therefore, the cutting edge existing at the intersection ridge line portion between the flank and the rake face at the tip of the tool is not covered with the hard coating 4, the blade angle can be sharpened, and the biting property to the work material is improved accordingly. Therefore, the hole position accuracy at the time of biting on the work material becomes good. In addition, the case where the hard coating 4 is provided on the tool front end surface and the inner surface of the chip discharge groove 2 is also within the scope of the present invention. In this case, since the entire tool is covered with the hard coating 4, the wear resistance is low. Although improved, fine metal particles called droplets in the hard coating 4 are present on the inner surface of the chip discharge groove 2, and chip discharge performance deteriorates. Further, the hard coating on the flank and rake surface of the tool tip 4, the cutting tool angle becomes dull and the cutting resistance increases, so that the possibility of breakage during drilling is slightly higher than when the hard coating 4 is not provided on the tip surface of the tool and the inner surface of the chip discharge groove 2. Further, since the blade angle becomes dull, it is easy to cause positional deviation when biting on the work material, and the hole position is compared with the case where the hard coating 4 is not provided on the tool tip surface and the inner surface of the chip discharge groove 2. The accuracy is a little worse.

  In the present embodiment, a hard coating 4 is used that contains at least Al and Cr as metal components and at least N as non-metal components. Such a hard coating 4 suppresses the wear of the tool base material, but the coating itself is worn with processing, so that an appropriate thickness is required and is desirably 1 μm or more. On the other hand, if it is too thick, the sharp edge of the cutting edge and chisel edge will be lost when the hard coating 4 is also provided on the tool tip surface and the inner surface of the chip discharge groove 2, resulting in misalignment of the work material. Since it becomes easy, it is desirable that it is 5 micrometers or less. Accordingly, the hard coating 4 is set so that the film thickness in the range of 1D or less in the axial direction from the tool tip is 1 μm or more and 5 μm or less.

In the present embodiment, the total length of one or more margins 3 in the axial direction from the tool tip in the axial direction is not less than 20% and not more than 60% of πD, and two margins 3 are provided. Among them, the length in the outer peripheral direction of the margin 3 having a long outer peripheral direction length is set to be 20% or more and 50% or less of πD.

Here, if the total length in the outer peripheral direction of each margin 3 is increased, the film durability of the margin 3 is improved, and the peripheral wear near the corner of the tool tip is less likely to progress, and the hole position accuracy is less likely to deteriorate. However, if the total length of each margin 3 in the outer circumferential direction is longer than 60% of πD, the cutting resistance increases and breaks easily, and if it is shorter than 20% of πD, the film durability of margin 3 As a result, the peripheral wear near the corner of the tool tip tends to progress and the hole position accuracy tends to deteriorate. Further, when the outer peripheral length of the margin 3 having the longest outer peripheral length is longer than 50% of πD, it is easy to break for the same reason as above, and when it is shorter than 20% of πD, the same as above. For this reason, the hole position accuracy tends to deteriorate.

The present embodiment has the shape of one groove and two grooves as described above. As shown in FIG. 4, there are two margins 3 in the range of 1D or less in the axial direction from the tool tip, and the outer periphery of the two margins 3. The total length in the direction is set to 43% of πD, and the length in the outer peripheral direction of the margin 3 having a long length in the outer peripheral direction is set to 33% of πD. As described above, in the present embodiment, the outer circumferential direction length of the margin 3 on the rear side in the tool rotation direction of the cutting edge 5 is set longer. In this case, since the cutting edge 5 is supported by the margin 3 having a long length in the outer circumferential direction, the rigidity can be ensured and the deflection of the tool can be suppressed, so that the deterioration of the hole position accuracy can be prevented.

In addition, since the drill receives a cutting force more strongly at the tip portion, the durability of the coating is deteriorated near the corner of the tool tip portion, and wear tends to progress. Therefore, when the hard coating 4 is formed thicker as the margin 3 on the tip side of the tool (provided so that the film thickness gradually increases from the base side to the tip side of the tool body 1), deterioration of the hole position accuracy is suppressed. Cheap.

Therefore, the present embodiment, as shown in FIG. 7, the thickness T1 of the hard film 4 of the tool tip end position of the margin 3 (corner position of the tool tip) L1, in the axial direction from the tool tip of the margin 3 The ratio T2 / T1 of the film thickness T2 of the hard coating 4 at the tool rear end position L2 in the range of 2 times the tool diameter (2D) or 2D or less is set to be 0.50 or more and 0.98 or less. Yes. Note that the film thicknesses T1 and T2 in FIG. 7 roughly indicate that the film thickness is provided so as to gradually increase from the base side to the tip side of the tool body 1. Specifically, as shown in FIG. 8, FIG. 8A is an example in which L2 is 2D in the axial direction from the tool tip with margin 3, and FIG. 8B is an axial direction from the tool tip with L2 in margin 3. 2 is an example of the tool rear end position within a range of 2D or less. When there are a plurality of margins 3 in the range of 1D or less in the axial direction from the tool tip, the value of T2 / T1 is set for each margin 3.

Here, T2 / T1 is 0.5 0 if less than the cutting load is concentrated coating at position L1 is in a shape projecting tool diameter direction, since the film strength or more stresses are generated, around the On the contrary, the film tends to be lost and the hole position accuracy is deteriorated. When T2 / T1 is larger than 0.98, the film thickness is almost constant from the root side to the tip side of the tool body 1 or gradually decreases from the root side to the tip side. There is no sufficient film thickness in the vicinity of the corner of the tip, and the durability of the coating at the tip is deteriorated and wear tends to progress, and the hole position accuracy is likely to deteriorate.

  For example, as shown in FIG. 9, T2 / T1 is set so that the jig holding the drill in the film forming furnace for forming the film is sufficiently large in the horizontal direction with respect to the diameter D of the drill. It can be set as appropriate by changing the insertion depth of the drill. Specifically, T2 / T1 can be reduced by increasing the insertion depth of the drill (the thickness of T1 in L1 can be increased), and T2 / T1 can be increased by decreasing the depth (the thickness of T1 in L1 can be reduced). .

Further, when a plurality of chip discharge grooves 2 are provided, the durability of the film is deteriorated at the margin 3 having the shortest outer circumferential length, and the hole position accuracy is deteriorated. That is, since the wear of the film with the shortest margin 3 progresses with respect to the margin 3 with the longest length in the outer circumferential direction, the wear at which the base material of the tool is exposed becomes noticeable at the shortest margin 3 and is reduced. As a result, the contact between the work material and each margin 3 becomes unbalanced, and the influence of the deviation in the advancing direction after the drill enters the work material increases, and the hole position accuracy deteriorates.

For this reason, the thickness TW of the hard coating 4 provided on the margin 3 having the longest length in the outer circumferential direction among the plurality of margins 3 present in the axial direction from the tool tip in the range of not more than 1 times the tool diameter D, It is preferable to set the ratio TW / TN of the film thickness TN of the hard coating 4 provided in the margin 3 having a short length in the outer circumferential direction to be 0.60 or more and 0.98 or less.

In this embodiment, as shown in FIG. 6, the film thickness TW of the hard coating 4 provided in the margin 3 of the outer circumferential length P1 in the axial direction from the tool tip to 1D or less, and the outer circumference shorter than P1. The ratio TW / TN of the film thickness TN of the hard coating 4 provided in the margin 3 of the direction length P2 is set to be 0.60 or more and 0.98 or less. Although not shown, even when there are three or more margins 3 in the range of 1D or less in the axial direction from the tool tip, the film thickness of the hard coating 4 provided on the margin 3 having the longest length in the outer circumferential direction. Is set to TW, and the film thickness of the hard coating 4 provided in the margin 3 having the shortest length in the outer circumferential direction may be set to TN.

Here, TW / TN is, when 0.6 0 less than concentrates the cutting load in the short outer peripheral direction length margin, or rather becomes worn coating easily proceeds by Nearby, coating deficient The hole position accuracy deteriorates, and if it is greater than 0.98, the durability of the film tends to deteriorate at a margin with a short outer peripheral length, and the hole position accuracy tends to deteriorate. Become.

This TW / TN is formed, for example, by providing a hard coating 4 with a constant film thickness on the entire drill blade, and then forming a margin 3 having a shortest peripheral length in a margin 3 in a 1D range from the tool tip. It can be made smaller by performing the film formation process by setting it so as to face the direction of the metal evaporation source in the furnace (the TN can be made thicker), and the margin 3 having the longest outer peripheral direction length is the direction of the metal evaporation source. It can be increased by installing the film so that it faces and the film forming process can be performed (the TN can be reduced).

Since the present embodiment is configured as described above, the length of the margin 3 in the outer circumferential direction is sufficiently increased at the tool tip to improve the durability of the hard coating 4, and the hard coating 4 is provided thicker toward the tool tip. As a result, the hard coating 4 on the tool tip side is not easily worn, and even if worn, the outer periphery is less likely to have a gradually reduced outer diameter. It will be suppressed well.

  Therefore, the present embodiment prevents the positional deviation at the time of drill biting on the work material while minimizing the influence of the deviation in the traveling direction after entering the work material of the drill as much as possible. It is possible to further improve the hole position accuracy while maintaining the performance.

  An experimental example supporting the effect of the present embodiment will be described.

10 to 13 are tables showing experimental conditions and experimental results in which the hole position accuracy and the like are evaluated by changing the drill shape, the configuration of the margin 3 and the configuration of the hard coating 4. The details of FIGS. 10 to 13 will be described. FIG. 10 is a diagram of comparative evaluation results of various drill shapes and marginal length differences in the outer periphery direction, FIG. 11 is a diagram of comparative evaluation results of T2 / T1 differences, and FIG. FIG. 13 is a diagram of comparative evaluation results for differences in TN, and FIG. 13 is a diagram of comparative evaluation results for differences in drill size.

Drill used in the experiment of FIG. 10 is a tool diameter 0.3mm to D, 2 blades 2 grooves drill has a groove length l and 6.5 mm, 1 blade 1 groove drill 1 blade 2 groove drills, construction margin Various changes are made. Circumference ratio in FIG. (%) Is a representation of the outer peripheral direction length ratio of the long margin of the outer peripheral direction length sum and the most outer circumferential direction of the length of the margin for [pi] D. Further, the basic shapes such as the tip angle and the twist angle are the same, but the groove depth of one blade shape is 10% deeper than the two blade shape. In the drawing, the display of the coating part column indicates that the entire surface is coated on the entire blade portion, the groove inner surface, the margin : no coating on the tip surface, and the margin only: no coating on the groove inner surface and the tip surface. Moreover, not only a coated drill provided with a hard coating in each sample but also an uncoated drill (no hard coating provided) is evaluated. The film thickness of the hard coating was 2 μm at T2, and T2 / T1 was 0.65 or more and 0.75 or less. No. About 7-13, TW / TN was 0.76 or more and 0.85 or less.

In addition, No. Reference numeral 13 denotes an example in which the tool body 1 is provided with the above-described second catching surface (see FIG. 5B) .

  Using the above drill, 4 sheets of “FR-4 halogen-free material, thickness 1.2 mm, 6-layer copper foil” as a base material are stacked, an aluminum plate (thickness 0.2 mm) as a backing plate, and a bake plate ( Drilling experiment with 10 holes for each specification at a drill (spindle) speed of 120 krpm, feed rate: 3.0 m / min, spindle lift rate: 25.4 m / min. Went.

The evaluation method in FIGS. 10-13 is demonstrated. Regarding the number of breaks, FIGS. 10 to 12 show the number of breaks in 10 in the 6,000 hit processing, and FIG. 13 shows the number of breaks in 10 within the set number of hits. Regarding the hole position accuracy, in FIGS. 10 to 12, the Avg. +3 s value is Avg. Of the hole position deviation amount on the back side of the bottom substrate of 10 set hit numbers in FIG. +3 s values are listed. Note that the number of broken holes was not measured, and the number of broken holes where the number of broken lines was less than 10 was recorded as the number of holes that were not broken. Also, the Avg. The effect of the hard coating was confirmed by the difference in the + 3s value (non-coating difference) (◯: large effect, x: small effect (non-coating difference is 1 μm or less)). In addition, the hole inner wall roughness was evaluated by confirming the appearance of the five hole inner walls in the vicinity of 6,000 hits in FIG. 10 (◯: hole inner wall roughness less than 25 μm, Δ: hole inner wall roughness 25 μm) In FIG. 13, evaluation was made by confirming the appearance of the inner wall of the five holes near the set hit (◯: hole inner wall roughness is less than 15 μm, Δ: hole inner wall roughness is 15 μm). Less, but relatively bad in appearance). Further, in FIG. 11, the film defect is confirmed by confirming the appearance of the film state near the corner after 6,000 hits in FIG. 12, and in FIG. 12, the film state with a short margin in the outer peripheral direction after 6,000 hits. Was evaluated by confirming the appearance (◯: the film was not missing, ×: the film was missing). In addition, film abrasion is confirmed by confirming the appearance of the film state near the corner after 6,000 hits in FIG. 11, and the film state with a short margin in the outer peripheral direction after 6,000 hits in FIG. Was evaluated by confirming its appearance (O: wear of the film was not noticeable, x: wear of the film was remarkable,-: wear was not confirmed due to film defect).

  From the evaluation results, the following points were confirmed.

The two-blade, two-groove shape is not easily broken, and the hole position accuracy is somewhat improved by the coating, but the inner wall roughness of the hole tends to be deteriorated when the outer peripheral length of the margin is increased. In addition, the 1-blade 1-slot shape has a great effect of hard coating coating, so the hole position accuracy is good and the hole inner wall roughness is not bad, but it is easy to break even if the outer peripheral length of the margin is within the preferred range. Tend. In addition, since the 1-blade 2-groove shape has good bite to the work material, the hole position accuracy is good, the effect of the hard coating is great, and the hole inner wall roughness is also good.

Further, in the case where a film is provided on the inner surface of the groove and the margin (No. 10 in FIG. 10) in the shape of one blade and two grooves (No. 10 in FIG. 10), or in the case where a film is provided only on the margin (No. 11 in FIG. 10), In addition to the effect of the drill shape, there was no tendency to break because the coating was not provided on the tip surface or on the tip surface and the groove inner surface. When the tool body is provided with a two-flute surface in the shape of one blade and two grooves (No. 13 in FIG. 10), the hole position accuracy is the best among the same shapes, and is not easily broken. Also good results were obtained.

From the above, it was confirmed that the best results were obtained when a film was provided only on the margin in the shape of one blade and two grooves.

  The drill used in the experiment of FIG. 11 has a tool diameter D of 0.3 mm and a groove length l of 6.5 mm. 9 is a drill having the same shape as 9. Each sample is evaluated not only for coated drills with a hard coating but also for non-coated drills. The film thickness of the hard coating was 2 μm at T2, and T2 / T1 was changed. Moreover, TW / TN was set to 0.76 or more and 0.88 or less.

  Using the above drill, 4 sheets of “FR-4 halogen-free material, thickness 1.2 mm, 6-layer copper foil” as a base material are stacked, an aluminum plate (thickness 0.2 mm) as a backing plate, and a bake plate ( Drilling experiment with 10 holes for each specification at a drill (spindle) speed of 120 krpm, feed rate: 3.0 m / min, spindle lift rate: 25.4 m / min. Went.

  From the evaluation results, it was confirmed that when T2 / T1 is small, film defects near the corner are conspicuous. Moreover, when T2 / T1 was large, it was confirmed that the abrasion of the film near the corner was conspicuous.

  From the above, it is considered that T2 / T1 is preferably 0.50 or more and 0.98 or less.

  The drill used in the experiment of FIG. 12 has a tool diameter D of 0.3 mm and a groove length l of 6.5 mm. 9 is a drill having the same shape as 9. Each sample is evaluated not only for coated drills with a hard coating but also for non-coated drills. The film thickness of the hard coating was 2.8 μm in TW, and TW / TN was changed. Further, T2 / T1 was set to 0.65 or more and 0.75 or less.

  Using the above drill, 4 sheets of “FR-4 halogen-free material, thickness 1.2 mm, 6-layer copper foil” as a base material are stacked, an aluminum plate (thickness 0.2 mm) as a backing plate, and a bake plate ( Drilling experiment with 10 holes for each specification at a drill (spindle) speed of 120 krpm, feed rate: 3.0 m / min, spindle lift rate: 25.4 m / min. Went.

From the evaluation results, it was confirmed that when TW / TN is small, a film defect with a short margin in the outer peripheral direction is conspicuous. Moreover, when TW / TN was large, it was confirmed that the abrasion of the film with a short margin in the outer circumferential direction was conspicuous.

  From the above, it was confirmed that TW / TN is not preferably at least 0.51 or less or 1.17 or more.

  The drill used in the experiment of FIG. 13 is a two-blade two-groove drill and a one-blade two-groove drill with a tool diameter D of 0.1 mm and a groove length l of 2.2 mm, a tool diameter D of 0.2 mm, and a groove length. 1-blade 2-groove drill with l of 3.5 mm, 2-blade 2-groove drill and 1-blade 2-groove drill with a tool diameter D of 0.6 mm and a groove length l of 8.5 mm, and a tool diameter D of 1.0 mm A two-blade two-groove drill with a groove length l of 9.0 mm, and a two-blade two-groove drill with a tool diameter D of 1.1 mm and a groove length l of 9.0 mm. The hard coating is provided on the entire blade portion. Moreover, not only the coated drill which provided the hard film | membrane in each sample but the non-coated drill is evaluated.

  Using the above drills, drilling experiments were performed for each tool diameter D under the following conditions.

・ Tool diameter D: 0.1 mm
Three sheets of “halogen-free material 0.4 mm thick 2-layer copper foil” as a base material are stacked, an aluminum plate with resin (thickness 0.1 mm) as a backing plate, and a bake plate (thickness 1.5 mm) as a discard plate 6,000 hit holes are drilled for each of the specifications at a drill (spindle) rotational speed of 330 krpm, a feed rate of 2.4 m / min, and a spindle ascending speed of 50.0 m / min.

・ Tool diameter D: 0.2mm
"FR-4 material 1.2mm thickness 6 layer copper foil" as a base material is piled up, aluminum plate with resin (thickness 0.17mm) as a backing plate, bake plate (thickness 1.5mm) as a discard plate ), 3,000 hit holes are drilled in units of 10 at a drill (spindle) rotation speed of 180 krpm, a feed rate of 2.4 m / min, and a spindle lift rate of 25.4 m / min.

・ Tool diameter D: 0.6mm
Three sheets of “FR-4 material 1.6mm thickness 6 layer copper foil” as a base material are stacked, an aluminum plate (thickness 0.2mm) as a backing plate, and a bake plate (thickness 1.5mm) as a discard plate Using a drill (spindle) rotation speed: 75 krpm, feed speed: 2.05 m / min, spindle ascending speed: 25.4 m / min.

・ Tool diameter D: 1.0mm
Three sheets of “FR-4 material, 1.5mm thickness, 4 layer copper foil” as a base material are stacked, an aluminum plate (thickness 0.15 mm) as a backing plate, and a bake plate (thickness 1.5 mm) as a discard plate 2,000 hit holes are drilled in units of 10 at a drill (spindle) rotation speed of 48 krpm, a feed speed of 0.96 m / min, and a spindle lift speed of 25.4 m / min.

・ Tool diameter D: 1.1 mm
Three sheets of “FR-4 material 1.6mm thickness 2-layer copper foil” as a base material are stacked, an aluminum plate (thickness 0.15 mm) as a backing plate, and a bake plate (thickness 1.5 mm) as a discard plate 2,000 hit holes are drilled in units of 10 at a drill (spindle) rotation speed of 48 krpm, a feed speed of 0.96 m / min, and a spindle lift speed of 25.4 m / min.

  From the evaluation results, it was confirmed that a drill with a tool diameter D of 0.1 mm or 1.1 mm has a small wear resistance effect of the hard coating.

  From the above, it was confirmed that the effect of the present invention was particularly exhibited with a drill having a tool diameter D of 0.2 mm to 1.0 mm.

1 Tool body 2 Chip discharge groove 3 Margin 4 Hard coating 5 Cutting edge D Tool diameter

Claims (9)

A drilling tool in which one or a plurality of spiral chip discharge grooves extending from the tool tip to the base end side are formed on the outer periphery of the tool body, and the tool is in an axial direction from the tool tip in the range of 1 or less times the tool diameter. Land fulfills the following two conditions:
(1) The total length in the outer circumferential direction is 20% or more and 60% or less of the circumferential length of the circle of the tool diameter. (2) Among the lands, the outer circumferential length of the land having the longest outer circumferential length is A drilling tool characterized in that a hard film is provided on the land, and the hard film is provided thicker toward the tip of the tool.   2. The drilling tool according to claim 1, wherein a film thickness T <b> 1 of the hard coating at a tool tip side position of the land and a range of twice the tool diameter in the axial direction from the tool tip of the land or less than twice the tool diameter. A drilling tool characterized in that the ratio T2 / T1 of the film thickness T2 of the hard coating at the tool rear end side position is 0.50 or more and 0.98 or less.   The drilling tool according to any one of claims 1 and 2, wherein the hard film includes at least Al and Cr as metal components and at least N as a non-metal component, and extends axially from the tool tip. A drilling tool characterized in that a film thickness in a range of 1 times or less of the tool diameter is 1 μm or more and 5 μm or less.   The drilling tool according to any one of claims 1 to 3, wherein the number of cutting edges is one.   The drilling tool according to any one of claims 1 to 4, wherein the hard coating is not provided on a tool front end surface.   The drilling tool according to any one of claims 1 to 4, wherein the hard coating is not provided on a tool front end surface and an inner surface of the chip discharge groove.   The drilling tool according to any one of claims 1 to 6, wherein a plurality of the lands are present in a range of not more than one times the tool diameter in the axial direction from the tool tip, and the outermost periphery among the plurality of lands provided. The ratio TW / TN of the film thickness TW of the hard coating provided on the land having a long direction length to the film thickness TN of the hard coating provided on the land having the shortest outer circumferential length is 0.60 or more and 0 A drilling tool characterized by being 98 or less.   8. The drilling tool according to claim 7, wherein the two lands exist in a range of not more than one time the diameter of the tool in the axial direction from the tip of the tool.   The drilling tool according to any one of claims 1 to 8, wherein the tool diameter is 0.2 mm or more and 1.0 mm or less, and at least from the tip to the rear end of the chip discharge groove contains WC and Co. A drilling tool characterized by being made of a hard alloy.

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