JP3847109B2 - Drill - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drill.
[0002]
[Prior art]
An example of a conventional drill will be described. FIG. 17 shows a side view of the drill, and FIG. 18 also shows a front view.
The drill shown in FIG. 17 is a straight blade drill, and the drill body 1 is integrally provided with the cutting portion 2 and the shank portion 4.
As shown in FIG. 18, the cutting portion 2 includes two blade portions 3. The blade portion 3 has a cutting blade 5 and a pad portion 6 extending from the tip to the side edge portion. The tip angle 5θ (see FIG. 17) of the cutting blade 5 is set to 180 ° or less, for example, 120 °.
The groove part 8 (refer FIG. 18) between the both blade parts 3 guides cutting oil to a cutting part, or discharges the cut chips.
Conventionally, in addition to the above, the outer periphery of the drill similar to the above-described drill (see FIGS. 17 and 18) is located behind the cutting edge and in a plane perpendicular to the axis of the drill. Some are provided with an outer cutting edge (for example, see Japanese Patent Application Laid-Open No. 58-149115). Further, there is a drill tool similar to the above-described drill (see FIGS. 17 and 18) provided with a blade tool that is located behind the cutting blade and exists in a plane perpendicular to the axis of the drill. (For example, refer to JP-A-9-150315). However, in any drill, at the start of machining, there is no change in what is drilled with the same cutting edge as the above-described drill (see FIGS. 17 and 18).
[0003]
[Problems to be solved by the invention]
In FIG. 19 which showed the processing state of the drill with the schematic diagram, the workpiece W to be drilled is, for example, a material made of aluminum die casting and has a cast hole (referred to as a pilot hole) H. The pilot hole H is a hole penetrating the workpiece W, and a machining allowance P around the pilot hole H is drilled, that is, cut.
In such a case, misalignment between the drill (drill body 1) and the prepared hole W of the workpiece W during processing is inevitable.
[0004]
Therefore, at the start of machining, machining is performed only with one of the cutting edges 5 (see FIG. 17) (referred to as single-edged machining).
For this reason, “drill fall” (refer to the two-dot chain line 1 in FIG. 19) that the drill body 1 tilts is likely to occur, and the rotation of the drill (drill body 1) becomes unstable and vibration tends to increase. .
As described above, when the machining state becomes unstable due to the tilt or vibration of the drill, the machining accuracy is deteriorated and the machining efficiency is lowered.
[0005]
In addition to the workpiece W, as in the case of a blind hole shown in a cross-sectional view in FIG. 20, even when drilling the machining allowance P including the bottom portion Ha of the bottomed pilot hole H1 into a bottomed shape, A problem similar to the above occurred. Further, the same problem as described above also occurred when drilling the machining allowance P around the bottom portion Ha of the bottomed pilot hole H1 in a penetrating manner. Furthermore, as shown in a cross-sectional view in FIG. 21, the same problem as described above also occurs when the machining allowance P including the bottom Hb of the bottomed pilot hole H1 is drilled from the bottom Hb side in a penetrating manner. occured.
[0006]
The problem to be solved by the present invention is to provide a drill capable of improving machining accuracy and machining efficiency by stabilizing the machining state.
[0007]
[Means for Solving the Problems]
The above-mentioned problem can be solved by a drill having the structure described in the claims.
That is, according to the drill described in claim 1, the outer peripheral portion of each cutting portion of the cutting portion of the drill body has a tip angle of 180 ° or more in order from the front side to the rear side in the rotation direction of the drill body . A rough cutting blade, a finishing blade formed to be shifted rearward in the axial direction of the drill body with respect to the first rough cutting blade, and the same with respect to the axial direction of the drill body with respect to the first rough cutting blade, and A second rough cutting edge having a tip angle of 180 ° or more is provided . Therefore, even if a misalignment with respect to the prepared hole of the workpiece occurs, it is possible to prevent single-edged machining at the start of machining. Thereby, since the machining state of the drill is stabilized, machining accuracy and machining efficiency can be improved. Moreover, the inner peripheral surface of the processing hole of the workpiece cut by the first rough cutting blade and the second rough cutting blade can be finished with high accuracy by the finishing blade.
[0008]
According to the drill described in claim 2, the bottom cutting edge protruding at the tip of the drill body and having a tip angle of 180 ° or less at the inner peripheral portion of the first rough cutting edge allows the workpiece to be processed. The bottom of the bottomed prepared hole can be drilled.
[0009]
According to the drill described in claim 3, the first rough cutting blade and the second rough cutting blade respectively formed on the plurality of blade portions of the drill main body are substantially equally spaced in the circumferential direction. by and Nde parallel, it can be well-balanced drilling pilot holes from the circumferential direction of the workpiece.
[0010]
According to the drill described in claim 4, when the tip angle of the first rough cutting edge is 180 ° + α1, and the tip angle of the second rough cutting edge is 180 ° + α2, the angle α1 The angle α2 is
α2 ≦ α1
What is set in the relationship is obtained .
[0011]
Moreover, according to the drill described in claim 5, since it is a finishing blade formed of a diamond sintered body or a boron nitride sintered body, the properties of the inner peripheral surface of the processed hole can be improved, The life of the blade can be improved.
[0012]
According to the drill described in claim 6, when drilling, guide pads that are respectively continuous with the first rough cutting blade, the second rough cutting blade, and the finishing blade of the drill body are provided on the inner peripheral surface of the processing hole. By sliding contact, the inner peripheral surface of the processed hole is burnished.
At the same time, the drill body receives a self-holding action, that is, a so-called self-bushing action, whereby the shaft center is held at a fixed position. For this reason, the processing state of the drill can be further stabilized.
[0013]
Moreover, according to the drill described in Claim 7, since the front-end | tip angle of each of the 1st rough cutting blade and the 2nd rough cutting blade was set to the angle in the range of 180-200 degrees, processing A drill excellent in processing performance such as hole expansion allowance, roughness, and roundness can be obtained.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
Embodiment 1 of the present invention will be described. Since this Embodiment 1 changes the tip shape of the drill in the above-described conventional technology, the changed portion will be described in detail, and the same parts are denoted by the same reference numerals, and redundant description will be omitted. 1 is a front view of the tip of the drill, FIG. 2 is a side view taken along the line II in FIG. 1, FIG. 3 is a side view taken along the line III in FIG. 1, and FIG.
[0015]
In the cutting part 2 of the drill main body 1, the first rough cutting edge 10, the finishing edge 30, and the back of the outer peripheral part of each blade part 3 in order from the front side in the rotation direction (see arrow Y in FIG. 1), Second rough cutting edges 20 are respectively formed. Further, the first rough cutting edge 10 and the second rough cutting edge 20 are formed at the same position with respect to the axial direction of the drill body 1, and the finishing blade 30 is in the axial direction of the drill body 1 with respect to both rough cutting edges 10 and 20. It is formed by shifting a predetermined amount backward. The drill body 1 is made of, for example, a cemented carbide.
[0016]
As shown in FIG. 4, the first rough cutting edge 10 includes a rake face 10 a formed on one plane including the axis L of the drill body 1 and a flank face formed with a relief angle 10 θA of, for example, 8 °. 10b. Furthermore, the tip angle 10θ (see FIG. 2) of the first rough cutting edge 10 is formed at 180 ° or more. The outer diameter dimension of the first rough cutting blade 10 is formed smaller than the outer diameter dimension of the guide pad 40 (described later) at the outer peripheral portion.
[0017]
As shown in FIG. 2, the second rough cutting edge 20 includes a rake face 20 a formed on one plane including the axis L of the drill body 1 and a flank face formed with a flank angle 20θA of 8 °, for example. 20b. Furthermore, the tip angle 20θ (see FIG. 4) of the second rough cutting edge 20 is formed at 180 ° or more. Further, if the tip angle 20θ of the second rough cutting blade 20 is 180 ° + α2, and the tip angle 10θ (see FIG. 2) of the first rough cutting blade 10 is 180 ° + α1, α2 and α1 are α2 ≦ The relationship of α1 is set. The second rough cutting edge 20 and the first rough cutting edge 10 are formed at the same position in the axial direction. Further, a total of four second rough cutting blades 20 and two first rough cutting blades 10 are formed, and the four rough cutting blades are arranged at substantially equal intervals in the circumferential direction.
[0018]
As shown in FIG. 3, the finishing blade 30 is located behind the rough cutting blades 10 and 20 at the tip of the drill body 1 in the axial direction, and is formed by a rake face 30 a and, for example, a 10 ° angle 30θA. It has a cutting edge. The outer diameter dimension of the finishing blade 30 is formed larger than the outer diameter dimension of both the rough cutting edges 10 and 20.
The finishing blade 30 is formed of a diamond sintered body or a boron nitride sintered body. The finishing blade 30 may be formed integrally with the blade portion 3 or may be separately attached to the blade portion 3 by fixing means such as brazing. Incidentally, when the workpiece is an aluminum material, the finishing blade 30 may be formed of a diamond sintered body. Further, when the workpiece is a cast iron material having high hardness, the finishing blade 30 may be formed of a boron nitride sintered body.
[0019]
As shown in FIG. 1, a total of six guide pads 40 respectively connected to the first rough cutting blade 10, the second rough cutting blade 20, and the finishing blade 30 are provided on the outer peripheral portion of the drill body 1. Is formed. Each guide pad 40 is formed so as to be slidable on the inner peripheral surface of a hole (referred to as a machining hole) in which a workpiece is drilled.
[0020]
The case where the workpiece is drilled with the above-described drill will be described. In FIG. 5 showing the machining state of the drill in a schematic view, at the start of machining, the first rough cutting edge 10 and the first rough cutting edge 10 and regardless of whether the drill (drill body 1) is misaligned with respect to the pilot hole H of the workpiece W The drill (drill body 1) is positioned at a predetermined position on the workpiece W by a well-balanced cutting process from the circumferential direction by the second rough cutting edge 20 (see FIG. 1).
At this time, the first rough cutting edge 10 of the drill body 1 has a tip angle 10θ (see FIG. 2) of 180 ° or more, and the second rough cutting blade 20 has a tip angle 20θ of 180 ° or more (FIG. 4). See). Thereby, single blade processing can be prevented and the processing state of a drill is stabilized.
[0021]
As the drilling progresses in the above-described stable machining state, the prepared hole H of the workpiece W cut by the two rough cutting blades 10 and 20 (see FIG. 1), that is, the machining hole H2 (see FIG. 5). The inner peripheral surface is cut to a target diameter by the finishing blade 30 (see FIG. 1).
[0022]
Further, a total of six guide pads 40 (see FIG. 1) are in sliding contact with the inner peripheral surface of the machining hole H2 (see FIG. 5) of the workpiece W. Thereby, the inner peripheral surface of the processing hole H2 is burnished (so-called polishing processing).
At the same time, the drill body 1 is subjected to a self-holding action, that is, a so-called self-bushing action, so that its axial center (axis L) is held at a fixed position, so that the machining state of the drill is stabilized.
Then, what is necessary is just to advance a drill to a predetermined position.
[0023]
Further, an oil agent such as cutting oil is supplied to the cutting portion through the groove portion 8 (see FIG. 1) of the drill body 1, whereby a lubrication / cooling effect can be obtained.
[0024]
The performance of which the effectiveness was recognized by the comparative test between the above-described drill and the conventional drill (see FIGS. 17 and 18) is listed below.
FIG. 6 shows a characteristic diagram of the roundness of the processing hole entrance. In FIG. 6, the horizontal axis represents the depth (mm) from the entrance of the machining hole H2 (see FIG. 5), and the vertical axis represents the roundness (μm) of the machining hole entrance. The characteristic line L1 is a measurement result of the roundness of the machining hole entrance portion by the drill of the present embodiment, and the characteristic line L2 is a roundness of the machining hole entrance portion by the conventional drill (see FIGS. 17 and 18). It is a measurement result of degree.
[0025]
As is apparent from FIG. 6, according to the drill of the present embodiment, an accuracy improvement of about twice as much was recognized in the roundness of the processing hole entrance portion as compared with the conventional drill.
This is considered to be a result of the first rough cutting edge 10 and the second rough cutting edge 20.
[0026]
FIG. 7 shows a comparison diagram of the positional accuracy of the processing hole. In FIG. 7, the horizontal axis and the vertical axis indicate the positional deviation amount (μm) of the processing hole with the processing origin set to “0” (zero). A point L3 indicates the center position (referred to as a pilot hole position) of the pilot hole H (see FIG. 5). The ♦ mark is the measurement result of the positional deviation amount of the processed hole by the drill of the present embodiment, and the ▲ mark is the measurement result of the positional deviation amount of the processed hole by the conventional drill (see FIGS. 17 and 18). .
[0027]
As is clear from FIG. 7, according to the drill of the present embodiment, an accuracy improvement of about 5 times in the amount of displacement of the processed hole was recognized as compared with the conventional drill.
This is considered to be the result of the first rough cutting edge 10 and the second rough cutting edge 20 and the six guide pads 40.
[0028]
FIG. 8 shows a comparative diagram of the relationship between machining accuracy and machining efficiency. In FIG. 8, the horizontal axis indicates the machining accuracy, and the vertical axis indicates the machining efficiency. Then, ● mark is a drill of this embodiment, ○ mark is a conventional drill (see FIGS. 17 and 18).
[0029]
As is apparent from FIG. 8, according to the drill of the present embodiment, it can be seen that even if the machining efficiency is increased as compared with the conventional drill, the machining accuracy is not deteriorated. This is considered to be a result of the first rough cutting edge 10 and the second rough cutting edge 20, the six-point guide pad 40, and the finishing edge 30.
That is, in order to improve the machining accuracy with the conventional drill, the machining efficiency has to be lowered, whereas the drill of the present embodiment has a machining accuracy significantly as is clear from FIGS. Be improved. From this, FIG. 8 shows that according to the drill of the present embodiment, the machining accuracy is improved while the machining efficiency is increased.
[0030]
According to the drill described above, the rough cutting edges 10 and 20 (see FIG. 1) provided on the outer peripheral portion of the drill body 1 have tip angles 10θ (see FIG. 2) and 20θ (see FIG. 4) of 180 ° or more. ing. Therefore, even if the misalignment with respect to the pilot hole H of the workpiece W (see FIG. 5) occurs, it is possible to prevent single-edged machining at the start of machining. Thereby, since the machining state of the drill is stabilized, machining accuracy and machining efficiency can be improved.
[0031]
Further, the rough holes 10 and 20 (see FIG. 2) arranged in the axial direction at substantially equal intervals can drill the prepared hole H (see FIG. 5) of the workpiece W (see FIG. 5) from the circumferential direction with a good balance.
[0032]
Further, the inner peripheral surface of the machining hole H2 (see FIG. 5) of the workpiece W cut by the rough cutting blades 10 and 20 (see FIG. 1) can be finished with high accuracy by the finishing blade 30 (see FIG. 1). it can.
[0033]
Moreover, since it is the finishing blade 30 (refer FIG. 1) formed with the diamond sintered compact or the boron nitride sintered compact, the property of the internal peripheral surface of the processed hole H2 (refer FIG. 5) of the workpiece W is improved. In addition, the life of the finishing blade 30 can be improved.
[0034]
Further, when drilling, the guide pad 40 of the drill main body 1 is in sliding contact with the inner peripheral surface of the processing hole H2 (see FIG. 5), so that the inner peripheral surface of the processing hole H2 is burnished.
At the same time, the drill body 1 is subjected to a self-holding action, a so-called self-bushing action, so that its axis is held in place. For this reason, the processing state of the drill can be further stabilized.
[0035]
In addition, the tip angle 10θ (see FIG. 2) (or 20θ (see FIG. 4)) of the rough cutting edge 10 (or 20) is set to an angle within the range of 180 to 200 °, so that the machining hole H2 ( A drill having excellent machining performance such as expansion allowance, roughness, and roundness can be obtained.
Specifically, FIG. 9 shows a characteristic diagram of the relationship between the tip angle 10θ (or 20θ) of the rough cutting edge 10 (or 20) and the expansion margin of the machining hole H2 (see FIG. 5). In FIG. 9, the horizontal axis indicates the rough cutting edge angle (°), and the vertical axis indicates the machining hole enlargement allowance (μm). The expansion allowance is the difference between the diameter of the drilled hole and the diameter of the finishing blade 30.
[0036]
FIG. 10 is a characteristic diagram showing the relationship between the tip angle 10θ (or 20θ) of the rough cutting edge 10 (or 20) and the roughness of the processed hole. In FIG. 10, the horizontal axis represents the tip angle (°) of the rough cutting edge, and the vertical axis represents the roughness Rz of the processed hole. The roughness Rz is the roughness of the inner peripheral surface of the drilled hole.
[0037]
FIG. 11 is a characteristic diagram showing the relationship between the tip angle 10θ (or 20θ) of the rough cutting edge 10 (or 20) and the roundness of the processed hole. In FIG. 11, the horizontal axis indicates the tip angle (°) of the rough cutting edge, and the vertical axis indicates the roundness (μm) of the processed hole.
Note that “conventional” in the cutting edge angles in FIGS. 9 to 11 indicates a drill having a cutting edge angle of 120 °, for example.
[0038]
As is apparent from FIGS. 9 to 11, the tip angle 10θ (see FIG. 2) of the first rough cutting edge 10 and / or the tip angle 20θ (see FIG. 4) of the second rough cutting blade 20 is 180 to 200. By setting the angle within the range of °, it is possible to obtain a drill excellent in processing performance such as machining hole expansion allowance, roughness, and roundness.
[0039]
Further, according to the drill of the first embodiment, even when the machining allowance P including the bottom Hb in the bottomed prepared hole H1 of the workpiece W as shown in FIG. The same actions and effects as described above can be obtained.
[0040]
[Embodiment 2]
A second embodiment of the present invention will be described. Since the second embodiment is obtained by changing a part of the first embodiment described above, the changed portion will be described in detail, and a duplicate description will be omitted. 12 is a front view of the tip of the drill, FIG. 13 is a side view taken along line XIII of FIG. 12, FIG. 14 is a side view taken along line XIV of FIG. 12, and FIG.
[0041]
In the drill according to the present embodiment, a bottom cutting edge 50 located at the inner peripheral portion of the first rough cutting edge 10 is provided at the tip of the drill body 1 according to the first embodiment. The bottom cutting edge 50 has a tip angle 50θ of 180 ° or less (see FIG. 13) and protrudes forward (upward in FIGS. 13 to 15) from both the rough cutting edges 10 and 20. The bottom cutting edge 50 has substantially the same configuration as the cutting edge 5 (see FIG. 18) in a conventional drill.
[0042]
According to the drill of the second embodiment, the bottom cutting edge 50 having a tip angle 50θ (see FIG. 13) of 180 ° or less, for example, a bottomed bottom of the workpiece W as shown in a sectional view in FIG. The bottom portion Ha in the hole H1 can be cut, that is, drilled. In addition, the outer diameter dimension of the bottom cutting edge 50 is set to the dimension which does not process the internal peripheral surface of the pilot hole H1.
[0043]
The present invention is not limited to the above-described embodiments, and modifications can be made without departing from the gist of the present invention. For example , the guide pad 40 can be omitted. Further, the blade portion 3 is not limited to two, but may be three or more.
[0044]
【The invention's effect】
As described above, according to the drill of the present invention, since the machining state is stabilized, machining accuracy and machining efficiency can be improved.
[Brief description of the drawings]
FIG. 1 is a front view showing a drill according to a first embodiment of the present invention.
FIG. 2 is a side view taken along the line II in FIG.
3 is a side view taken along the line III in FIG. 1;
4 is a side view taken along the line IV in FIG. 1. FIG.
FIG. 5 is a schematic view showing a processing state of a drill.
FIG. 6 is a characteristic diagram showing the roundness of the processing hole entrance.
FIG. 7 is a comparative view showing the positional accuracy of a processed hole.
FIG. 8 is a comparative diagram showing the relationship between machining accuracy and machining efficiency.
FIG. 9 is a characteristic diagram showing the relationship between the tip angle of the rough cutting edge and the machining hole expansion allowance.
FIG. 10 is a characteristic diagram showing the relationship between the tip angle of the rough cutting edge and the roughness of the machining hole.
FIG. 11 is a characteristic diagram showing the relationship between the tip angle of the rough cutting edge and the roundness of the machining hole.
FIG. 12 is a front view showing a drill according to a second embodiment of the present invention.
13 is a side view taken along the line XIII of FIG.
14 is a side view taken along the line XIV in FIG. 12;
15 is a side view taken along the line XV in FIG. 12. FIG.
FIG. 16 is a cross-sectional view showing a prepared hole in the workpiece.
FIG. 17 is a side view showing a conventional drill.
FIG. 18 is a front view of the same.
FIG. 19 is a schematic diagram showing a machining state of a drill.
FIG. 20 is a cross-sectional view showing another example of the prepared hole for the workpiece.
FIG. 21 is a cross-sectional view showing another example of the prepared hole for the workpiece.
[Explanation of symbols]
1 Drill body 10 First rough cutting edge (rough cutting edge)
10θ Tip angle 20 Second rough cutting edge (rough cutting edge)
20θ Tip angle 30 Finishing blade 40 Guide pad 50 Bottom cutting edge 50θ Tip angle

Claims (7)

The cutting portion of the drill body includes a plurality of blade portions and a groove portion formed between the blade portions,
A first rough cutting edge having a tip angle of 180 ° or more in order from the front side in the rotation direction of the drill body to the outer periphery of each blade part , and a drill body with respect to the first rough cutting edge. A finishing blade formed by being shifted rearward in the axial direction and a second rough cutting blade that is formed in the same direction in the axial direction of the drill body with respect to the first rough cutting blade and has a tip angle of 180 ° or more are provided. A drill characterized by The drill according to claim 1,
The tip of the drill body is provided with a bottom cutting edge having a tip angle of 180 ° or less at the inner peripheral portion of the first rough cutting edge and protruding further forward than the first rough cutting edge. A drill characterized by that. The drill according to claim 1 or 2,
Drill the first coarse cutting edge and the second rough cutting edge, characterized in that has Nde parallel at substantially equal intervals in the circumferential direction are formed on the edge portion of the plural rows of the drill body. The drill according to claim 1, 2 or 3,
The tip angle of the first rough cutting blade is 180 ° + α1,
When the tip angle of the second rough cutting edge is 180 ° + α2,
The angle α1 and the angle α2 are
α2 ≦ α1
A drill characterized by having a relationship of The drill according to any one of claims 1 to 4,
A drill characterized in that the finishing blade is formed of a diamond sintered body or a boron nitride sintered body. The drill according to any one of claims 1 to 5,
A guide pad that is continuous with the first rough cutting blade, the second rough cutting blade, and the finishing blade and that can be slidably contacted with the inner peripheral surface of the hole is provided on the outer peripheral portion of the drill body. A drill characterized by being made. The drill according to any one of claims 1 to 6 ,
The drill characterized by each tip angle | corner of the said 1st rough cutting blade and the said 2nd rough cutting blade being set to the angle within the range of 180-200 degrees.

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