JP4564562B2 - Drilling tool - Google Patents

Description

  The present invention relates to a drilling tool.

  In a general drill for a printed wiring board (PCB), for example, as shown in FIG. 1, a pair of chip discharge grooves 21 and 22 are provided at a predetermined twist angle β ′. , 22 and the first flank surfaces 23, 24 are formed with cutting edges having a predetermined tip angle γ ′ at the intersecting ridges 25, 26. In the figure, reference numerals 28 and 29 are second flank surfaces.

  Therefore, the tool in FIG. 1 has a total of four tip surfaces, and a chisel edge 27 is formed near the center of the tool tip by giving a predetermined angle to each tip surface (flank). 1A is a plan view, FIG. 1B is a front view, and FIG. 1C is a right side view.

  By the way, along with the recent high integration and high density of electronic devices, drilling of a small-diameter hole in a PCB is required, so that the drill is also required to have a smaller diameter.

  For example, a very small diameter drill with a tool diameter of about 0.05 mm may be used. However, since the rigidity of the tool is extremely small, there is a high possibility of breakage, and frequent tool change is required, or PCBs are overlapped at the same time. It is necessary to take measures such as reducing the number of sheets to be processed.

  Further, in the appearance inspection of the tip shape, the right / left balance (the deviation of the cutting edge and the eccentricity of the chisel edge) is measured to determine whether it is acceptable or not. However, if the diameter is reduced, this inspection becomes troublesome as well as machining.

  Therefore, for example, Patent Document 1 discloses a configuration of a predetermined single-edged drill that attempts to ensure rigidity even with a small-diameter tool, but a sufficient breakage life is not yet obtained. Currently. Also, there are a plurality of tip contact surfaces, and the pass / fail judgment inspection is troublesome as in the prior art.

JP 2003-31522 A

  The present invention has been made in view of the above situation, and even a very small diameter drilling tool is not easily broken and does not need to be frequently replaced. It is an object of the present invention to provide a drilling tool that has never been easier and is extremely practical.

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

  A drilling tool having one or a plurality of spiral chip discharge grooves 1 and 2, wherein the tool tip surface has one tip contact surface 5 a having no ridge line extending in a direction intersecting the tool central axis, The tip contact surface 5a is configured by a tip flank 5b that is inclined at a predetermined angle with respect to the tool center axis so as not to contact the workpiece to be contacted and is provided continuously with the tip contact surface 5a. It relates to drilling tools.

  Moreover, the drilling tool according to claim 1, wherein the tip contact surface 5a is inclined at a predetermined inclination angle α with respect to the tool central axis.

  The drilling tool according to any one of claims 1 and 2, wherein the tool diameter is 0.2 mm or less.

  Further, in the drilling tool according to any one of claims 1 to 3, land portions 3 and 4 are provided between the plurality of chip discharge grooves 1 and 2, and the chip discharge grooves 1 and 2 are provided. Among the plurality of intersecting ridge line portions 6 and 7 with the tip contact surface 5a, there is a leading edge on the longer intersecting ridge line portion 6, and the intersecting ridge line portion 6 is configured to exhibit a cutting action. The present invention relates to a drilling tool characterized by

  5. The drilling tool according to claim 4, wherein an inclination angle α of the tip contact surface 5a with respect to the tool center axis is set to 0 ° to (90 ° −twist angle). It is concerned.

  The drilling tool according to claim 5, wherein the inclination angle α is set to 10 ° to 30 °.

  Further, in the drilling tool according to any one of claims 5 and 6, the tip flank 5b is provided between the tip contact surface 5a and the land portions 3 and 4. This relates to the drilling tool to be used.

  Moreover, the drilling tool of any one of Claims 5-7 WHEREIN: The said front-end | tip flank 5b is provided in the tool rotation direction back side of the intersection ridgeline part 6 with the said most advanced point. It relates to a drilling tool.

  Further, in the drilling tool according to any one of claims 5 to 8, the drilling tool has two chip discharge grooves 1 and 2, and the tip flank 5b serves as the tip contact surface 5a and the land portion. 3 and 4 and the cutting edge discharge grooves 1 and 2 of the intersections A and B, the tool of the intersecting ridge line portion 6 where the cutting edge is within a range not exceeding the straight line L connecting the intersections A on the tool rotation front side The present invention relates to a drilling tool characterized in that it is provided on the rear side in the rotation direction with an inclination direction different from the tip contact surface 5a.

  Since the present invention is configured as described above, even a very small diameter drilling tool is not easily broken and need not be frequently replaced, and of course, the shape is simple and manufacture and inspection are easy. This is a very useful drilling tool.

  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 tool tip has a single tip contact surface 5a without a ridge line, and has, for example, a chisel edge near the center of the tool tip, and a cutting edge that is connected to the chisel edge to form a predetermined tip angle. Unlike general drills, there is no chisel edge near the center of the tool tip, and most of the cutting force during drilling is received in the thrust direction (tool axis direction), which is due to external force perpendicular to the tool axis (cutting resistance during drilling). This reduces bending stress and makes it difficult to break.

  Further, cutting is performed gradually while the most protruding portion of the tip contact surface 5a (and the intersecting ridge line portion between the land portions 3 and 4 or the chip discharge grooves 1 and 2) hits the workpiece processing surface. Unlike conventional drills, it is difficult to bite into the machined surface, so that the tool swings slightly in the initial stage of cutting, and the hole diameter on the inlet side is expanded appropriately, so that the drilled hole shape is closer to the inlet side. Therefore, the base end side of the tool is hardly brought into contact with the inner wall of the machining hole, and breakage due to the base end side of the tool coming into contact with the inner wall of the machining hole is suppressed.

  In addition, by forming the tip flank 5b that is connected to the tip contact surface 5a at a predetermined angle, it is difficult to prevent the cut chips from being led to the chip discharge grooves 1 and 2 and chip clogging is caused. It becomes difficult to occur.

  Further, the tip contact surface having a desired cross-sectional shape and a desired inclination angle α can be obtained by simply removing the tip portion of the tool material in which the chip discharge groove is formed at an appropriate position and an appropriate angle. 5a can be easily formed.

  In addition, since the tip shape is simplified, it is difficult for left and right unbalances of each tip surface to occur like a conventional tool having a large number of tip contact surfaces, and left and right balance inspection is facilitated, and inspection can be simplified. At the same time, the yield is improved.

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

  As shown in FIG. 2, the present embodiment is a drilling tool having two spiral chip discharge grooves 1 and 2, and is one flat without a ridge line extending in the direction intersecting the tool central axis. A front end contact surface 5a, and a flat front end flank 5b that is inclined at a predetermined angle so as not to contact the workpiece (workpiece) with which the front end contact surface 5a comes into contact, and is connected to the front end contact surface 5a. The tool tip surface is formed.

  In the figure, reference numerals 6 and 7 denote intersecting ridge line portions between the chip discharge grooves 1 and 2 and the tip contact surface 5a, reference numeral 8 denotes an intersecting ridge line portion between the land portion 3 and the tip flank 5b, and 9 denotes a land portion 4. And 10 is a cross ridge line portion between the tip flank 5b and the chip discharge groove 2. 2A is a plan view, FIG. 2B is a front view, and FIG. 2C is a right side view.

  Specifically, in the present embodiment, the present invention is applied to a two-groove drill having an extremely small diameter with a tool diameter (maximum outer diameter of the blade portion) of 0.05 mm. Note that the present invention is not limited to the two-groove drill, and can be applied to other drills such as a single-groove drill. Further, the present invention can be applied not only to a very small diameter tool but also to a general tool having a tool diameter exceeding 0.2 mm.

  Each part will be specifically described.

  The tip contact surface 5a is inclined at a predetermined inclination angle α with respect to the tool center axis. The inclination angle α is preferably set to an angle equal to or greater than 90 ° and equal to or less than the twist angle of the chip discharge groove in an angle parallel to the direction perpendicular to the tool axis (0 ° or greater). When the angle is greater than 90 ° -twist angle (45 ° in the present embodiment), that is, an angle greater than 90 ° -45 ° = 45 °, the tool tip becomes too sharp and easily chipped, resulting in tip cracks. The cutting ability is reduced and the breakage life is reduced. In particular, when the angle is set to 10 ° to 30 °, chipping of the tip is difficult to occur and sufficient cutting ability can be exhibited and the breakage life is long. In this embodiment, the inclination angle α of the tip contact surface 5a is set to 20 °, and the inclination direction X is set as shown in FIG. 3. From the intersecting ridge line portion 9 between the tip contact surface 5a and the land portion 4, It is comprised so that it may contact with the workpiece | work surface so that it may rub over the intersection ridgeline part 6 which has a front-end | tip point.

  Further, the tip contact surface 5a of the present embodiment can be obtained by removing the tip of the tool material at a predetermined position and a predetermined angle in a state where the chip discharge grooves 1 and 2 are formed in the tool material. The surface shape and the desired inclination angle α can be obtained.

  Further, in the present embodiment, the cutting edge (first contact with the workpiece) on the longer intersecting ridge line portion 6 among the plurality of intersecting ridge line portions 6 and 7 of the chip discharge grooves 1 and 2 and the tip contact surface 5a. This intersection ridge line portion 6 is configured to exhibit a cutting action. Therefore, since the leading edge is not on the land portions 3 and 4 (outer periphery), it is difficult to receive external force in the direction perpendicular to the tool axis, and a stable life can be increased.

  In the present embodiment, the tip contact surface 5a is formed of a single smooth surface. In addition, you may comprise not only a plane but the smooth concave curved surface or convex curved surface of the grade which does not have a bad influence on cutting action.

  A tip flank 5b is provided between the tip contact surface 5a and the land portion 3. The tip flank 5b is formed of a single flat surface, like the tip contact surface 5a. The tip flank 5b is not limited to a flat surface, and may be a smooth concave curved surface or a convex curved surface that does not adversely affect the cutting action, or may be a multi-surface configuration without being limited to a single surface. However, considering productivity, it is desirable to make it one side.

  Further, the tip flank 5b is provided on the rear side in the tool rotation direction (the R direction in FIG. 3) at the foremost point of the intersecting ridge line portion 6 and is a chip of chips cut in contact with the intersecting ridge line portion 6. The lead-out to the discharge groove 2 is not hindered, and is configured to be discharged satisfactorily.

  Specifically, as shown in FIG. 3, the tip flank 5 b is the tip contact surface 5 a, and the front of the tool rotates at the intersections A and B between the land portions 3 and 4 and the chip discharge grooves 1 and 2. Provided so that the inclination direction Y is different from the inclination direction X of the tip contact surface 5a on the rear side in the tool rotation direction of the intersecting ridge line portion 6 where the most advanced point is within a range not exceeding the straight line L connecting the intersections A on the side. It has been.

  The inclination angle of the tip flank 5b is set so that the tip flank 5b does not contact the workpiece. Specifically, the inclination angle of the tip flank 5b is preferably set to an angle equal to or greater than (0 ° or greater) parallel to the direction perpendicular to the tool axis and 90 ° or less to the twist angle of the chip discharge groove. When the angle is greater than 90 ° -twist angle (45 ° in the present embodiment), that is, an angle greater than 90 ° -45 ° = 45 °, the tool tip becomes too sharp and easily chipped, resulting in tip cracks. The cutting ability is reduced and the breakage life is reduced. In this embodiment, it is set to 30 °. That is, the tip contact surface 5a and the tip flank 5b are set at different inclination angles.

  Since this embodiment is configured as described above, there is no portion where the external force is concentrated, such as a sharp tip (chisel edge) or a general cutting edge, and the external force in the direction perpendicular to the tool axis is difficult. Since the intersecting ridge line portion between the tip contact surface 5a and the wall of the chip discharge groove gradually processes the processing surface, the tool tip is not easily damaged.

  Furthermore, although the cutting is performed gradually while the intersecting ridge line portion 6 between the most protruding portion of the tip contact surface 5a and the chip discharge groove 1 hits the processing surface, the tool is difficult to bite to the processing surface as described above. However, the hole diameter on the inlet side is moderately enlarged and drilling proceeds, so that the shape of the machined hole becomes moderately large on the inlet side, so the base end side of the tool is in contact with the inner wall of the machined hole. It is difficult to prevent breakage due to the proximal end side of the tool coming into contact with the inner wall of the machining hole.

  Further, the shape is simple, and it can be easily manufactured by simply removing the tip portion of the tool material in which the chip discharge groove is formed at an appropriate position and angle.

  Further, since there is only one tip contact surface 5a, there is no occurrence of left and right unbalance of each tip contact surface as in the case of having a plurality of tip contact surfaces, and right and left balance inspection is not required, and inspection is performed. Can be simplified and the yield can be improved.

  Moreover, the above-mentioned effect is remarkably exhibited when the tool diameter is 0.2 mm or less. That is, when the tool has a small diameter, the tip of the tool is likely to be chipped at the initial stage of cutting by the tool tip, so that the configuration of this embodiment that can reduce the external force at the initial stage of cutting as much as possible is extremely useful. Become.

  Therefore, the present embodiment is not practical to break, even if it is an extremely small diameter drilling tool, and it is not necessary to frequently replace it. It becomes a drilling tool with excellent characteristics.

  An experimental example supporting the above-described effect will be described.

  5 and 6 show a conventional drill (conventional example) having two conventional chip discharge grooves and two cutting edges as shown in the normal drill column of FIG. 4, and a tip flat (one surface) column. The drill (comparative example) which provided only the tip contact surface without providing the tip flank according to this embodiment as shown in FIG. 5 and the drill according to this embodiment as shown in the tip flat (two sides) column ( The result of comparing the tool life of Example) with the number of hits against PCB is shown. 5 and 6, it is confirmed that the tool life is drastically increased when the tip contact surface is a single flat surface without a ridgeline as compared with the configuration having a plurality of tip contact surfaces as in the conventional example. did it.

  7 and 8 show the results of comparing the hole position accuracy of the comparative example and the example. 7 and 8, it was confirmed that the hole position accuracy was improved in the example as compared with the comparative example. If this is inferred from the photograph after machining (after 10,000 Hit) in FIG. 4, in the comparative example, the portion that does not contribute to the machining on the tip contact surface (the rear of the intersecting ridge line portion where the cutting edge is located in the tool rotation direction) In the embodiment in which the evacuation surface is provided by removing the area, the discharge of the chips is not hindered. Therefore, it is considered that the chips are smoothly discharged accordingly, the inner wall roughness is improved, and the hole position accuracy is also improved accordingly.

It is a schematic explanatory drawing of a prior art example. It is a schematic explanatory drawing of a present Example. It is an expansion schematic explanatory drawing explaining the front-end | tip shape of a present Example. It is a tip photograph before and after processing of the tool used in the experimental example. It is the graph which compared tool life. It is the table | surface which compared the tool life. It is the graph which compared the hole position accuracy. It is the table | surface which compared the hole position accuracy.

Explanation of symbols

1 and 2 Chip discharge groove 3 and 4 Land portion 5a Tip contact surface 5b Tip clearance surface 6 and 7 Cross ridge line part between chip discharge groove and tip contact surface α Inclination angle A Intersection B (on the front side of tool rotation) Intersection point (on the tool rotation rear side) L Line connecting intersection points A

Claims (9)

  A drilling tool having one or a plurality of spiral chip discharge grooves, the tool tip surface having one tip contact surface having no ridge line extending in a direction intersecting the tool central axis, and the tip contact surface being A drilling tool comprising a tip flank inclined at a predetermined angle with respect to a tool center axis so as not to contact a workpiece to be brought into contact with the tip contact surface.   2. The drilling tool according to claim 1, wherein the tip contact surface is inclined at a predetermined inclination angle with respect to the tool center axis.   The drilling tool according to any one of claims 1 and 2, wherein the tool diameter is 0.2 mm or less.   The drilling tool according to any one of claims 1 to 3, wherein a land portion is provided between the plurality of chip discharge grooves, and a plurality of intersecting ridge lines between the chip discharge grooves and the tip contact surface. A drilling tool characterized in that a cutting edge is formed on the longer intersecting ridge line portion of the sections, and the intersecting ridge line portion is configured to exhibit a cutting action.   5. The drilling tool according to claim 4, wherein an inclination angle of the tip contact surface with respect to the tool center axis is set to 0 ° to (90 ° −twist angle).   6. The drilling tool according to claim 5, wherein an inclination angle of the tip contact surface with respect to a tool center axis is set to 10 ° to 30 °.   7. The drilling tool according to claim 5, wherein the tip flank is provided between the tip contact surface and the land portion. 8.   The drilling tool according to any one of claims 5 to 7, wherein the tip flank is provided on the rear side in the tool rotation direction of the intersecting ridge line portion where the most advanced point is located. tool.   9. The drilling tool according to claim 5, comprising two chip discharge grooves, wherein the tip flank is the tip contact surface, and the land portion and the chip discharge groove are provided. Are provided at an inclination direction different from the tip contact surface on the rear side in the tool rotation direction of the intersecting ridge line portion where the most advanced point is within a range not exceeding a straight line connecting the intersections on the tool rotation front side. Drilling tool characterized by that.