JP4324211B2 - 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 good or bad.

  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. Moreover, there are a plurality of tip 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 current situation as described above, and even a very small diameter drilling tool is not easily broken and need not 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.

Comprises a helical chip-evacuating flutes 2 of the multiple, a drilling tool land portions 3 and 4 is provided between each other the plurality of chip discharge groove 2, the tip portion Is provided with a flat tip surface 5 having no ridge line intersecting the tool central axis, and the longer one of the plurality of intersecting ridge line portions 6 and 7 between the chip discharge groove 1 and the tip surface 5. The present invention relates to a drilling tool characterized in that there is a cutting-edge point on the intersecting ridge line portion 6 and the intersecting ridge line portion 6 is configured to exhibit a cutting action .

Further, it is a drilling tool comprising a plurality of spiral chip discharge grooves 1 and 2, and land portions 3 and 4 provided between the plurality of chip discharge grooves 1 and 2. A flat tip surface 5 having no ridge line intersecting the tool center axis is provided at the portion, and the longer one of the plurality of intersecting ridge line portions 8 and 9 between the land portions 3 and 4 and the tip surface 5 is provided. The present invention relates to a drilling tool characterized in that there is a leading edge on the ridge line portion 8 and the intersecting ridge line portion 8 is configured to exhibit a cutting action .

Further, in the drilling tool according to any one of claims 1 and 2 , the tip surface 5 is inclined at a predetermined inclination angle α with respect to the tool center axis. It is concerned.

The drilling tool according to any one of claims 1 to 3 , wherein an inclination angle α of the tip surface 5 with respect to the tool center axis is set to 0 ° to (90 °-torsion angle). It relates to a drilling tool.

The drilling tool according to claim 4 , wherein the inclination angle α is set to 10 ° to 30 °.

  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.

  It has a configuration in which one flat tip surface 5 without a ridge line is provided at the tool tip, for example, has a chisel edge near the center of the tool tip, and has a cutting edge that is connected to the chisel edge to form a predetermined tip angle. Unlike general drills, most of the cutting force during drilling is received in the thrust direction (tool axis direction), and bending stress due to external force (cutting resistance during drilling) in the direction perpendicular to the tool axis is reduced accordingly. It will be difficult.

  Further, cutting is gradually performed while the most protruding portion of the tip surface 5 (and the ridge portion of the land portion or the chip discharge groove) hits the workpiece processing surface, but unlike the above-described general drill, processing is performed. Since it is difficult to bite into the surface, the tool swings slightly in the initial stage of cutting, and the hole diameter on the inlet side is appropriately expanded, so that drilling progresses. The proximal end side is unlikely to contact the inner wall of the machining hole, and breakage due to the proximal end side of the tool coming into contact with the inner wall of the machining hole is suppressed.

  Further, the tip surface 5 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 on which the chip discharge groove is formed at an appropriate position and an appropriate angle. Can be easily formed.

  In addition, since there is only one tip surface 5, there is no occurrence of left and right unbalance of each tip surface as in a tool having a plurality of tip surfaces, and there is no need for left and right balance inspections. The inspection of the flank width resulting from the formation of the flank (tip surface) is not required, and the inspection can be simplified and the yield is improved.

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

  In the present embodiment, as shown in FIG. 2, a spiral first chip discharge groove 1 and a spiral second chip discharge groove 2 are provided, and between the chip discharge grooves 1 and 2, The drilling tool is provided with land portions 3 and 4 and is provided with one flat tip surface 5 having no ridge line intersecting the tool center axis at the tip portion. In the figure, reference numerals 6 and 7 denote intersecting ridge line portions between the chip discharge grooves 1 and 2 and the front end surface 5, and reference numerals 8 and 9 denote intersecting ridge line portions between the land portions 3 and 4 and the front end surface 5.

  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 surface 5 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. 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. Specifically, the inclination angle α of the front end surface of the present embodiment is set to 20 °.

  Further, the front end surface 5 of the present embodiment is obtained by removing the front end portion 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. Although the shape and the desired inclination angle α can be obtained, the shape of the tip surface 5 is roughly divided into the following two shapes.

  First, as shown in FIG. 3, among the plurality of intersecting ridge line portions 6 and 7 of the chip discharge grooves 1 and 2 and the front end surface 5, the first point (first The cross ridge line portion 6 exhibits a cutting action, and the second is a plurality of land portions 3 and 4 and the tip surface 5 as shown in FIG. Of the intersecting ridgeline portions 8 and 9, the longest intersecting ridgeline portion 8 has a cutting edge, and the intersecting ridgeline portion 8 exhibits a cutting action. 3 and 4, the inclination angle α is set to 30 °.

  In the present embodiment of FIG. 2, the first configuration is adopted. In this case, since the foremost point 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. A stable and long life can be achieved. In the second configuration, since the most advanced point is on the land portions 3 and 4 (outer periphery), the cutting ability is increased, and good hole quality (hole position accuracy, hole inner wall surface roughness) can be obtained. it can.

  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 cutting edge having a general tip angle, but the external force in the direction perpendicular to the tool axis is difficult to bite. Since the intersection ridge line portion between the tip surface 5 and the rake face of the chip discharge groove gradually processes the processing surface, the tool tip is not easily damaged.

  Further, the cutting is gradually performed while the intersecting ridge line portion 6 between the most protruding portion of the tip surface 5 and the chip discharge groove 1 hits the processing surface. However, as described above, the tool is difficult to bite into the processing surface. Drilling progresses while the diameter of the hole on the inlet side is moderately enlarged due to a slight swing, and therefore the shape of the processed hole is moderately larger on the inlet side, and therefore the base end side of the tool is less likely to contact the inner wall of the processed hole. The breakage due to the proximal end side of the tool coming into contact with the inner wall of the machining hole is suppressed.

  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 surface 5, there is no occurrence of left / right unbalance of each tip surface as in the case of having a plurality of tip surfaces, and there is no need for left / right balance inspection. The inspection of the flank width resulting from the formation of the flank (tip surface) is not required, and the inspection can be simplified and the yield is 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.

  As shown in FIG. 5, the tool life of a tool (example) having a flat tip surface with no ridge line provided at a right angle to the axis and the tool having the configuration shown in FIG. 1 (conventional example) is hit against the PCB. As a result of comparison, the tool life is confirmed to be about twice as long when the tip surface is the only flat surface with no ridgeline compared to the conventional configuration with many tip surfaces (tip flank surfaces). did it.

  Further, as shown in FIG. 6, when the inclination angle of the flat tip surface having no ridge line is changed from 0 ° (the embodiment in FIG. 5) to 45 ° and the tool life is compared by the number of hits against the PCB, 0 is obtained. It was confirmed that the breakage life was longer than that of the conventional example at a temperature of from 45 ° to 45 °, and that it was particularly long at a temperature of from 10 ° to 30 °.

It is a schematic explanatory drawing of a prior art example. It is a schematic explanatory drawing of a present Example. It is a schematic explanatory drawing explaining a front-end | tip shape. It is a schematic explanatory drawing explaining a front-end | tip shape. It is the table | surface which compared the tool life of a present Example and the prior art example. It is the graph which compared the tool life with respect to the inclination-angle of a front end surface.

1 and 2 Chip discharge groove 3 and 4 Land part 5 Tip surface 6 and 7 Cross ridge line part (of chip discharge groove and tip face) 8 and 9 Cross ridge line part of land part and tip surface α Inclination angle

Claims (5)

Comprises a helical chip flutes of multiple, a drilling tool land portion is provided between each other the plurality of chip discharge grooves, the ridge line that intersects the tool center axis at the distal end A flat tip surface is provided, and among the plurality of intersecting ridge line portions of the chip discharge groove and the tip surface, there is a leading edge on the longer intersecting ridge line portion, and the intersecting ridge line portion is cut. A drilling tool characterized by being configured to exert its action . A drilling tool having a plurality of spiral chip discharge grooves and a land portion provided between the plurality of chip discharge grooves, and having no ridge line intersecting the tool center axis at the tip part A flat tip surface is provided, and among the plurality of intersecting ridge line portions of the land portion and the tip surface, there is a cutting-edge point on the longer intersecting ridge line portion, and the intersecting ridge line portion exhibits a cutting action. A drilling tool characterized by being configured to do so. 3. The drilling tool according to claim 1 , wherein the tip surface is inclined at a predetermined inclination angle with respect to the tool center axis. 4. 4. The drilling tool according to claim 1, wherein an inclination angle of the tip surface with respect to a tool center axis is set to 0 ° to (90 ° −twist angle). 5. tool. The drilling tool according to claim 4 , wherein the inclination angle is set to 10 ° to 30 °.

Images