JP2010099790A - Drilling tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drilling tool which can suppress abrasion at an outer peripheral of an end part, improve a breakdown resistance during a drilling work and improve a roughness of an inner wall and a re-abrasiveness, and is simple in its structure, extremely easy in its production and excellent in its utility. <P>SOLUTION: The drilling tool has one or a plurality of spiral chip discharging grooves 2 formed from an end of the tool to a base end side on an outer periphery of a tool body 1 and a clearance forming stepped part 4 which is lower by one step than a land part 3 and is provided between the chip discharging groove 2 and the land part 3. The clearance forming stepped part 4 is not provided in the end side of the tool and provided only in the base end side of the tool. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a drilling tool.

  For example, Patent Document 1 discloses a drill 25 that has a blade portion 20 formed with a cutting edge for drilling a workpiece on the distal end side and a shank portion that is held by a tool holder on the proximal end side. Thus, there is a two-edged drill in which a clearance forming step 23 that is one step lower than the land portion 22 is formed between the chip discharge groove 21 and the land portion 22 to provide a so-called clearance 24.

  The clearance 24 is generally provided with a predetermined length from the drill tip as shown in FIG. Therefore, as compared with the drill 25 ′ having no clearance as shown in FIG. 2, the volume of the chip discharge groove (the space for chip discharge) is widened and the chip discharge performance is excellent. There is a problem that the progress is fast and the life is shortened accordingly.

  Further, when the clearance 24 is provided up to the drill tip, the tip shape becomes complicated by the amount of the clearance 24 and the machining becomes troublesome (particularly troublesome when the diameter is reduced).

  Further, usually, when an appearance inspection of the tip shape of the drill in the front end view is performed, the width of the land portion 22 after the clearance 24 is formed or the difference between them when there are a plurality of them is measured, and the clearance 24 is also measured. If there are a plurality of depths or a plurality of them, the difference between them is measured to determine whether it is good or bad. However, if the diameter is reduced, not only machining but also this inspection becomes troublesome, and it is inevitable that the cost is increased.

JP 2005-131751 A

  The present invention has been made in view of the above-described situation, and can suppress the outer peripheral wear of the tip portion, improve the breakage resistance during drilling, and improve the inner wall roughness and re-polishing properties. The present invention provides a drilling tool that has a simple structure and is easy to manufacture and excellent in practicality.

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

  One or a plurality of spiral chip discharge grooves 2 extending from the tool front end to the base end side are formed on the outer periphery of the tool body 1, and one step lower than the land section 3 between the chip discharge grooves 2 and the land section 3. A drilling tool provided with a clearance forming step 4, wherein the clearance forming step 4 is not provided on the tool distal end side but only on the tool base end side. It concerns tools.

  Further, in the drilling tool according to claim 1, the clearance forming step 4 is provided toward the tool proximal side from a position separated from the tool tip by a distance of 1.5 to 5 times the tool outer diameter D1. The present invention relates to a drilling tool characterized by being formed.

  3. The drilling tool according to claim 2, wherein the clearance forming step 4 is provided in a range not exceeding the end position of the chip discharge groove 2. It is.

  Further, in the drilling tool according to any one of claims 1 to 3, the clearance forming step 4 is provided at a depth of 5 to 20% of the tool outer diameter D1. It relates to drilling tools.

  The drilling tool according to any one of claims 1 to 4, wherein the clearance forming step 4 is provided at the same depth from a start end to an end. Is.

  Further, in the drilling tool according to any one of claims 1 to 5, the clearance forming step 4 is provided on the front side in the tool rotation direction of the chip discharge groove 2. It relates to drilling tools.

  Further, in the drilling tool according to any one of claims 1 to 6, the core thickness D2 of the tool body 1 is set to a front taper shape in which the core thickness D2 gradually increases from the tool tip toward the base end. The present invention relates to a drilling tool characterized by

  Further, in the drilling tool according to claim 7, the front taper shape of the core thickness D2 is set so that the inclination angle on the tool tip side is large and the inclination angle on the tool base end side is small. It relates to drilling tools.

  The drilling tool according to any one of claims 1 to 8, wherein the tool outer diameter D1 is 0.2 mm or less.

  Since the present invention is configured as described above, the outer peripheral wear of the tip portion can be suppressed to improve the breakage resistance at the time of drilling, and the inner wall roughness and regrindability can be improved, and the structure is simple. It is a drilling tool with excellent practicality that is easy to manufacture.

  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.

  When drilling a workpiece, the clearance formed by the clearance forming step 4 increases the groove volume of the chip discharge groove 2 so that the chip is discharged well. Since there is no clearance, the land portion 3 on the tool tip side that easily comes into contact with the work is less likely to be worn, and the outer peripheral wear on the tool tip side is suppressed accordingly. Therefore, it becomes difficult for the chips to be clogged, so that the breakage resistance at the time of drilling is improved, and damage to the inner wall of the processed hole due to the chips can be reduced, and the roughness of the inner wall can be improved accordingly.

  For example, even when the outer shape of the tool is set to a back taper shape in which the outer diameter of the tool is not constant but gradually decreases from the tip of the tool toward the proximal direction, this back is prevented by suppressing the outer peripheral wear on the tool tip side. The tapered shape is maintained, and the breakage life can be extended.

  Furthermore, it can be manufactured simply by forming the clearance from the middle part of the tool of the land part 3 to the base end side, and the tool tip shape is not complicated, and the manufacturing and appearance inspection can be easily performed as much. Become. Moreover, since there is little wear on the outer periphery of the tip of the tool, it can be stably fixed on the blade support, and it is excellent in re-polishing properties because it is easy to ensure the diameter after re-polishing. .

  Further, for example, when the core thickness D2 of the tool body 1 is set to a front taper shape in which the core thickness D2 gradually increases from the tool tip toward the base end, a sufficient center on the tool base end side due to the front taper shape. It is possible to suppress the clogging of the chips by remarkably increasing the groove volume while ensuring the thickness, and particularly excellent in breakage resistance.

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

  In the present embodiment, one or a plurality of spiral chip discharge grooves 2 extending from the tool front end to the base end side are formed on the outer periphery of the tool body 1, and the land is formed between the chip discharge grooves 2 and the land portion 3. A drilling tool provided with a clearance forming step 4 that is one step lower than the portion 3, wherein the clearance forming step 4 is provided only on the tool base end side, not on the tool distal end side. is there.

  Specifically, this embodiment has a blade portion 6 having a tool outer diameter D1 (diameter) of about 0.1 mm and having a cutting edge 5 formed on the distal end side for drilling a workpiece. This is a printed circuit board (PCB) drill having a shank portion 7 held by a tool holder on the side, and two chip discharge grooves 2 are provided on the outer periphery of the blade section 6. The land portion 3 is provided, and the cutting edge 5 is provided between the chip discharge groove 2 and the drill tip flank. Further, the tip flank is inclined with respect to the tool axis at a predetermined angle so as to form a chisel edge in the center of the drill. In the figure, reference numeral 8 denotes a continuous portion of the blade portion 6 and the shank portion 7.

  In the present embodiment, a PCB drill having a diameter of about 0.1 mm is used, but the present invention can be similarly applied even when the diameter is smaller or larger. In particular, it is suitable for a small diameter drill of 0.2 mm or less (about 0.05 mm).

  Each part will be specifically described.

  The clearance forming step 4 is located at a distance from the tool tip by a distance 1.5 to 5 times the tool outer diameter D1 (starting end) from the end position of the chip discharge groove 2 toward the tool base end side. It is provided up to the side position (terminal). When the tool is provided from a distance less than 1.5 times the tool outer diameter D1, it is difficult to obtain a sufficient effect of suppressing the outer peripheral wear of the tool tip, and the land portion 3 is eliminated during re-polishing, thereby forming a clearance. There is a risk that the step 4 will be exposed, and when it is provided from a position away from 5 times the tool outer diameter D1, a sufficient groove volume cannot be secured due to the absence of the clearance forming step 4. This is because the fluidity of the chips deteriorates and the chips are easily clogged.

  In the present embodiment, from a position that is separated from the tool tip by a distance of about twice the tool outer diameter D1 to the tool base end side of the blade portion 6, from the end position of the chip discharge groove 2 to a position slightly on the tool tip side. (The range of A in FIG. 4 is provided up to the position in the vicinity of the continuous portion with the tapered portion 8 of the blade portion 6). Specifically, the end of the clearance forming step 4 is provided from the end position of the chip discharge groove 2 to a position away from the end of the tool discharge by about 1 to 10% of the groove length of the chip discharge groove 2. Yes. It should be noted that the clearance forming step 4 may be provided so that the end of the clearance forming step 4 is located at the same position as the end of the chip discharge groove 2. In short, a sufficient groove volume can be secured and the end of the chip discharge groove 2 is exceeded. It may be provided in a range that does not exist.

  Accordingly, the clearance 9 does not exist at the distal end portion of the tool, but is provided from the middle portion of the tool to the proximal end side.

  Further, the clearance forming step 4 has a depth of 5 to 20% of the tool outer diameter D1 and the same depth from the start end to the end (distance from the land surface to the step surface 10 of the clearance forming step 4). Is provided). If the tool outer diameter D1 is less than 5%, the clearance forming step 4 is too shallow, causing a problem that the amount of increase in the groove volume is small and clogging is likely to occur, and if it exceeds 20%, the rigidity of the drill decreases. This is because not only the performance such as the hole position accuracy deteriorates but also the breakage resistance deteriorates due to insufficient rigidity of the drill. In the present embodiment, it is provided at a depth of about 10% of the tool outer diameter D1.

  Further, the connecting surface 11 that connects the land surface and the step surface 10 of the clearance forming step 4 has an obtuse angle α formed with the step surface 10 of the clearance forming step 4 in the axial section of the drill ( In this embodiment, it is set to be about 120 °. If α is an acute angle, chips are likely to be clogged at the corners where the step surface 10 and the connecting surface 11 intersect, and this causes a problem in that the chip discharge performance deteriorates and the breakage tends to break as a whole. .

  Further, the clearance forming step 4 is provided on the front side in the tool rotation direction of the chip discharge groove 2. Specifically, in this embodiment, the land portion of the drill having no clearance as shown in FIG. 2 is removed from the middle portion of the tool to form the land portion 3, and the chip discharge groove 2 on the front side in the tool rotation direction. A stepped surface 10 is formed at the end of this through the continuous surface 11. In addition, the cutting edge 5 is provided in the tool rotation direction back side of the chip discharge groove 2 at the tool tip.

  The core thickness D2 of the tool main body 1 is set to a front taper shape in which the core thickness D2 gradually increases from the tool tip toward the base end. Specifically, as shown in FIG. 4, the front taper shape of the core thickness D2 is set so that the inclination angle is large in the tool tip side region F1 and the inclination angle is small in the tool base side region F2. ing. Therefore, as apparent from FIG. 5 showing the cross section of the drill of the present embodiment and FIG. 6 showing the cross section of the drill 25 'without clearance shown in FIG. 2, the volume of the chip discharge space is remarkably increased. It is possible to suppress chip clogging by the clearance 9 while ensuring a sufficient core thickness D2 on the tool base end side by the front taper shape, and particularly excellent in breakage resistance.

  In the present embodiment, the tool outer diameter D1 (the outer diameter of the blade 6 of the tool body 1) is a back taper shape that gradually decreases from the tool tip toward the base end. You may comprise so that an outer diameter may become substantially constant from a front-end | tip to a base end.

  Since the present embodiment is configured as described above, when drilling a workpiece, the clearance formed by the clearance forming step 4 increases the groove volume of the chip discharge groove 2 so that the chip is removed. Of course, since the clearance is not present at the tip portion, the land portion 3 on the tool tip side that easily comes into contact with the work is hardly worn, and the outer peripheral wear on the tool tip side is suppressed accordingly. Therefore, since it is easy to maintain a stable drilling process, the fracture resistance during drilling is improved, and the fracture resistance is improved even when chips are hard to clog. Thus, the inner wall roughness can be improved accordingly.

  Even when the outer shape of the tool is set to a back taper shape in which the outer diameter of the tool is not constant but gradually decreases from the tool tip toward the base end, this back taper shape is suppressed by suppressing the outer peripheral wear on the tool tip side. Is maintained, and the breakage life can be extended.

  Furthermore, it can be manufactured simply by forming the clearance from the middle part of the tool of the land part 3 to the base end side, and the tool tip shape is not complicated, and the manufacturing and appearance inspection can be easily performed as much. Become. Moreover, since there is little wear on the outer periphery of the tip of the tool, it can be stably fixed on the blade support, and it is excellent in re-polishing properties because it is easy to ensure the diameter after re-polishing. .

  Even if the core thickness D2 of the tool body 1 is set to a front taper shape in which the core thickness D2 gradually increases from the tool tip toward the base end, a sufficient core thickness is secured on the tool base end side by the front taper shape. However, it is possible to remarkably increase the groove volume to suppress chip clogging, and in particular, it has excellent breakage resistance.

  Therefore, in this embodiment, the outer peripheral wear of the tip portion is suppressed, the breakage resistance at the time of drilling can be improved, the inner wall roughness and the regrindability can be improved, and the structure is simple and easy to manufacture. It is a drilling tool with excellent practicality.

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

  In the table and graph, the normal clearance refers to a general clearance formed from the tool tip as shown in FIG. 1, and the sub-clearance refers to the tool tip according to the present embodiment as shown in FIG. The clearance formed from the middle part of the tool so as not to be formed.

  FIG. 7 shows the results of measuring the outer wear state after 18000 hits of PCB for each of the three samples in FIGS. 1 (normal clearance), 2 (no clearance), and 3 (sub-clearance: this example). It is a graph to show. In addition, a new article shows the state before drilling. The measurement was performed at a pitch of 0.01 mm within a range of 0.2 mm from the drill tip. Each sample was measured under the same conditions such as material, length, diameter, etc., except for the presence / absence of clearance and the clearance formation range.

  As is clear from FIG. 7, it was confirmed that the sub-clearance type was suppressed in peripheral wear to the same extent as the non-clearance type, and was superior in outer wear resistance compared to the normal clearance type.

  FIGS. 8 and 9 show the results of breakage evaluation after hitting 12,000 PCBs in each sample.

  As is clear from FIGS. 8 and 9, the sub-clearance type has a significantly longer breakage life than the non-clearance type, and the above-mentioned peripheral wear is suppressed even with respect to the normal clearance, thereby extending the breakage life. It was confirmed that it was extremely excellent in breakability.

  FIGS. 10 and 11 show the results of measuring the roughness of the inner wall of the processed hole of the PCB 10 points after 6000 hits by stacking 4 PCBs in each sample, and expressing the results for each PCB stacking position. The PCB at the top (tool entry side) is described as top, and the PCB at the bottom (tool projection side) is described as bottom.

  10 and 11, it can be confirmed that the inner wall roughness of the sub-clearance type is significantly improved compared to the non-clearance type, and that the inner wall roughness similar to the normal clearance can be maintained even if there is no clearance at the tool tip. It was.

  From the above, according to this example, it was confirmed that the outer peripheral wear of the tip portion was suppressed, the breakage resistance at the time of drilling was improved, and the inner wall roughness and re-polishing property could be improved.

It is a schematic explanatory side view of a drill provided with a conventional clearance. It is a schematic explanatory side view of a conventional drill without clearance. It is a schematic explanatory side view of a present Example. It is a schematic explanatory drawing of a present Example. FIG. 4 is an enlarged schematic explanatory sectional view in which a part of FIG. 3 is enlarged. FIG. 3 is an enlarged schematic explanatory sectional view in which a part of FIG. 2 is enlarged. It is a graph which shows the experimental result regarding outer periphery abrasion. It is a table | surface which shows the experimental result regarding breakage. It is a graph which shows the experimental result regarding breakage. It is a table | surface which shows the experimental result regarding an inner wall roughness. It is a graph which shows the experimental result regarding an inner wall roughness.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tool main body 2 Chip discharge groove 3 Land part 4 Step part for clearance formation D1 Tool outer diameter D2 Center thickness

Claims (9)

  One or a plurality of spiral chip discharge grooves are formed on the outer periphery of the tool main body from the tip of the tool toward the base end, and the clearance forming step is one step lower than the land between the chip discharge groove and the land. The drilling tool is characterized in that the clearance forming step portion is not provided on the tool distal end side but is provided only on the tool proximal end side.   2. The drilling tool according to claim 1, wherein the step for forming the clearance is provided from a position away from the tool tip by a distance of 1.5 to 5 times the outer diameter of the tool toward the base side of the tool. Drilling tool characterized by   3. The drilling tool according to claim 2, wherein the clearance forming step is provided in a range not exceeding the end position of the chip discharge groove.   The drilling tool according to any one of claims 1 to 3, wherein the clearance forming step is provided at a depth of 5 to 20% of the outer diameter of the tool.   The drilling tool according to any one of claims 1 to 4, wherein the clearance forming step is provided at the same depth from a start end to an end.   The drilling tool according to any one of claims 1 to 5, wherein the step for forming the clearance is provided on a front side in the tool rotation direction of the chip discharge groove.   The drilling tool according to any one of claims 1 to 6, wherein the core thickness of the tool body is set to a front taper shape in which the core thickness gradually increases from the tool tip toward the base end. Drilling tool.   8. The drilling tool according to claim 7, wherein the front taper shape of the core thickness is set so that the inclination angle on the tool tip side is large and the inclination angle on the tool base end side is small. .   The drilling tool according to any one of claims 1 to 8, wherein the outer diameter of the tool is 0.2 mm or less.

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