JP5593910B2 - drill - Google Patents

Description

  The present invention relates to a drill mainly used for drilling a metal material such as a general steel material.

  When drilling a part (member) made of a metal material such as an automobile or an aircraft, various drills corresponding to the size and shape of the hole are used. However, when the material of the part or the number of holes to be processed exceeds the allowable range of the drill to be used, there are problems such as the tip of the drill being chipped or the drill itself being broken. In addition, there have been problems such as the position of the hole to be processed being shifted and the processed surface of the hole becoming rough.

  Therefore, in Patent Document 1, the second angle of the cutting edge of the drill (the relief angle of the second surface) is set to 8 ° or more and 12 ° or less, and a third surface continuous to the second surface is provided, so that A drill that can ensure a large flank on the center side and ensure the strength of the cutting edge and reduce cutting resistance is disclosed.

  Further, in Patent Document 2, the cutting edge of a drill mainly used for drilling a printed wiring board is set to 10 ° or more and 15 ° or less so that the cutting edge becomes strong and the cutting edge is not chipped. A drill capable of preventing the hole position accuracy and the surface roughness of the hole is disclosed.

JP 2006-75938 A JP 2005-118923 A

  However, in the drill disclosed in Patent Document 1, when the second angle of the cutting edge is a constant angle in the range of 8 ° to 12 °, the cutting edge near the chisel edge is degraded. As a result, there has been a problem that the biting property to the work material required at the moment when the drill comes into contact with the work material cannot be secured sufficiently. In addition, the provision of the third surface on the drill increases the number of drill manufacturing steps, and the quality control of the drill shape becomes complicated.

  Further, in the drill disclosed in Patent Document 2, when the second angle of the cutting edge is a constant angle in the range of 10 ° to 15 °, the sharpness of the cutting edge in the vicinity of the outer peripheral corner decreases. As a result, there is a problem that it takes time until the cutting force generated between the drill and the work material is stabilized.

  This is because the chisel edge corner, which is the center side of the drill cutting edge, and the outer periphery corner, which is the outer peripheral side of the drill cutting edge, have different roles for the second angle of the cutting edge in the cutting process. Conceivable. In other words, the second angle of the cutting edge in the chisel edge corner is the second angle of the cutting edge that first comes into contact with the work material in the cutting process, so that the biting property with the work material depends on the second angle. Is greatly affected. In addition, the second corner of the cutting edge in the outer corner ensures the hole diameter corresponding to the drill diameter as the cutting process proceeds, so that the deflection of the drill itself and the hole position accuracy are greatly affected by the second corner. It depends.

  Therefore, for example, by changing only the second angle of the cutting edge of the chisel edge corner and the outer periphery corner to 20 ° or 5 °, and the second angle of the other portion of the cutting edge is constant at 10 °, It is also possible to use a drill that changes so that the second angle of the cutting edge gradually decreases from the chisel edge toward the outer corner.

  However, in the former drill, a large thrust (cutting resistance) is generated at a portion where the second angle of the cutting edge changes during cutting, which is not preferable for both the drill and the work material. Also, the latter drill is not preferable for both the drill and the work material because a large thrust is generated at the portion where the second angle of the cutting edge changes during the cutting process in the same manner as described above.

  Therefore, in view of the above-described problems, the present invention provides a drill that can sufficiently secure the biting property to a work material during drilling with a drill and can shorten the time until the cutting resistance is stabilized. Let it be an issue.

In order to solve the above-described problems, in the present invention, a drill in which the second angle of the cutting edge continuously decreases from the chisel edge corner to the outer corner, A drill capable of suppressing the thrust fluctuation range during drilling by setting the angle between 20 ° and 25 ° and the second angle of the cutting edge at the outer corner within the range between 3 ° and 7 °. provide.

In the present invention, since the second angle of the cutting edge in the chisel edge corner is in the range of 20 ° to 25 ° , it is possible to prevent the sharpness of the cutting edge near the chisel edge corner from being lowered. The reason for limiting the second angle in the chisel edge corner to a certain range is that when the maximum value exceeds 25 ° or the minimum value is 15 ° or less, the thrust value during cutting as described later, This is because the thrust fluctuation range becomes large.

In addition, since the second angle of the cutting edge in the outer corner is in the range of 3 ° to 7 ° , it is possible to prevent the cutting edge from being deteriorated in the outer corner. The reason for limiting the second corner in the outer corner to a certain range is that when the maximum value is 8 ° or more, or the minimum value is less than 3 °, the thrust value during cutting as will be described later. This is because the thrust fluctuation range becomes large. For example, if the drill has a small diameter of 1.0 mm or less, a sufficient amount of escape between the drill and the work material cannot be secured, and the cutting resistance increases because the drill contacts the work material. It is also possible.

As described above, in the present invention, the second angle of the cutting edge continuously decreases from the chisel edge corner toward the outer corner, and the second angle of the cutting edge in the chisel edge corner is 20 ° or more and 25 °. By using a drill that has a range of less than or equal to ° and the second corner of the cutting edge in the outer corner is in the range of 3 to 7 degrees , the thrust generated in both the drill and the work material is greatly reduced. There is an effect that the biting property to the work material can be sufficiently secured at the time of drilling.

Further, since the sharpness of the cutting edge near the chisel edge corner can be prevented from being lowered, the amount of escape between the drill and the work material can be secured, and the increase in the thrust value can be suppressed.

Furthermore, in order to prevent the sharpness of the cutting edge from being lowered at the outer corner, the drill runout after the machining hole diameter becomes the same as the drill diameter is reduced, and the time from the start of machining to the stabilization of the thrust value can be shortened. Moreover, the thrust fluctuation range of the drill during cutting can also be suppressed.

It is a front view of drill 1 which is an example of an embodiment of the invention. It is a right view of the drill 1 tip part of FIG. (A) is sectional drawing of the XX arrow of FIG. 1, (b) is sectional drawing of the YY arrow of FIG. It is a graph which shows the time-dependent change of the thrust value during the cutting test using the drill (The 2nd angle 20 degrees in a chisel edge corner, The 2nd angle 3 degrees in an outer periphery corner) which concerns on this invention. It is a graph which shows the time-dependent change of the thrust value during the cutting test using the comparison drill (20 degrees in a chisel edge corner, 2 degrees in an outer periphery corner) outside this invention. These are graphs which show the time-dependent change of the thrust value during the cutting test using the comparative drill (second angle 10 ° constant) outside the present invention. (A) shows the change of the thrust value in the XY direction during the cutting test using the drill (second angle 20 ° in the chisel edge corner, second angle 3 ° in the outer corner) according to Example 1 of the present invention; (B) is a graph which shows the change of the thrust value in the XY direction during the cutting test using the comparative drill (20 degrees in a chisel edge corner, 2 degrees in an outer periphery corner) outside this invention.

  Embodiments of the present invention will be described with reference to the drawings, in which the drill 1 according to the present invention is applied to a twist drill having two twist grooves. 1 is a front view of a drill 1 which is an example of an embodiment of the present invention, FIG. 2 is a right side view of the tip of the drill 1 in FIG. 1, and FIG. 3 (a) is a view taken along line XX in FIG. A sectional view, (b) is a sectional view taken along line YY in FIG.

  As shown in FIGS. 1 and 2, the drill 1 having two torsional grooves 6, 6 has a cutting edge 3 that is a ridge line extending from a chisel edge corner 2 that is an end portion of a chisel edge at a tip portion thereof. An outer peripheral corner 4 is formed at the intersection of the cutting edge 3 and the outer periphery of the drill 1. Furthermore, the flank 5 of the drill 1 is comprised from the 2nd surface 5a and the 3rd surface 5b formed continuously from the 2nd surface 5a.

  Further, the clearance angle (second angle) of the second surface of the cutting edge 3 of the drill 1 is formed so as to continuously decrease from the chisel edge corner 2 toward the outer periphery corner 4, and FIG. As shown in FIG. 3, the second angle α1 located at the chisel edge corner 2 is set to a range of more than 15 ° and 25 ° or less, and the second angle α2 located at the outer corner 4 is set as shown in FIG. It is set to be in the range of 3 ° or more and less than 8 °.

  In order to confirm the influence on the drill or work material due to the change in the second angle of the cutting edge of the drill according to the present invention, a cutting test was performed using drills having various specifications. The results will be described with reference to Table 1 and FIGS.

  The drill used in this cutting test has a drill diameter of 6.0 mm, a drill length of 81 mm, a groove length of 41 mm, a helix angle of 30 °, a tip angle of 134 °, and a shank diameter of 6.0 mm. The number angle is 5 levels of 10 °, 15 °, 20 °, 25 ° and 30 °, and the angle angle of the outer corner is 6 levels of 1 °, 3 °, 5 °, 7 °, 10 ° and 15 °. A total of 30 types of drills were used. In addition, as a conventional drill, the drill diameter is 6.0 mm, the drill length is 82 mm, the groove length is 41 mm, the helix angle is 30 °, the tip angle is 136 °, the shank diameter is 6.0 mm, and the second angle of the cutting edge is 10 ° (fixed) The angle drill was used as a comparative drill.

This cutting test was performed under the following conditions, and the cutting test was performed while measuring the axial cutting resistance (thrust value) of the drill applied to the drill with a dynamometer until the drilled hole reached a depth of 19 mm.
・ Cutting speed: 80 mm / min
・ Drill feed rate: 0.116 mm / rev
・ Drill feed rate: 491.7 mm / min
-Drill rotation speed: 4250 min ^-1
-Work material: Carbon steel S50C
・ Cutting oil: Water-soluble cutting fluid ・ Drilling machine: FANUC vertical MC (model number: BT30)
Cutting resistance measuring instrument: Kistler dynamometer (model number: 9273)

  Table 1 shows the results of this cutting test using the 30 types of drills described above. “× A” in the table indicates that the cutting edge was chipped during the cutting test, “× B” indicates that the thrust value during the cutting test was 600 N or more, and “× C” indicates that cutting is in progress. It was assumed that the fluctuation range of thrust was 100 N or more, and this was used as a criterion for determining the drill failure. In addition, “◯” in the table does not correspond to any of the above, that is, no chip occurs in the drill edge, the thrust value during the cutting test is less than 600 N, and the thrust fluctuation range is less than 100 N It was decided that it was a drill with no defects.

  As shown in Table 1, drills whose chisel edge corners have a second angle of 10 ° and 30 ° are “× A”, “× B” in all six levels where the outer corner has a second angle of 1 ° to 15 °. ”Or“ × C ”, that is, the chip of the drill tip is chipped during the cutting test, the thrust value during the cutting test is 600 N or more, or the thrust fluctuation range during cutting is 100 N or more. There was a bug that occurred. In addition, drills having chisel edge corners with second angles of 15 °, 20 °, and 25 ° are similarly “× A” or “xA” when the outer corners have second angles of 1 °, 10 °, and 15 °. XC ”, that is, a defect occurred in the cutting edge of the drill blade during the cutting test, or a thrust fluctuation width during cutting was 100 N or more. The test result of the conventional comparative drill was “× B”, and the thrust value during the cutting test was about 640 N.

  On the other hand, the test results for drills with chisel edge corners of 2 °, 15 °, 20 ° and 25 ° and outer corners of 2 °, 3 °, 5 ° and 7 ° are shown in Table 1. As shown in the figure, it was “◯”, that is, no chipping occurred in the cutting edge, the thrust value during the cutting test was less than 600 N, and the thrust fluctuation range was less than 100 N, and no defect occurred.

  FIG. 4 shows the time-dependent change of the thrust value during the cutting test using the drill according to the present invention (second angle 20 ° in the chisel edge corner, second angle 3 ° in the outer corner), and FIG. FIG. 6 shows the change over time in the thrust value during a cutting test using an outer comparative drill (second angle 20 ° in the chisel edge corner, second angle 1 ° in the outer corner), and FIG. The change with time of the thrust value during a cutting test using a constant angle of 10 ° is shown.

  The change with time of the thrust value during the cutting test using the drill according to the present invention (second angle 20 ° in the chisel edge corner, 3 ° second angle in the outer corner) is 0 from the start of cutting as shown in FIG. After 14 seconds (interval indicated by A1), the thrust value became stable at about 530 N (value indicated by a broken line in the figure) and was less than 600 N. Further, the thrust fluctuation range after the thrust value became stable was about 90 N (the width of the thrust value indicated by A2), which was less than 100 N.

  On the other hand, the time-dependent change of the thrust value during the cutting test using the drill (the second angle 20 ° in the chisel edge corner and the second angle 1 ° in the outer corner) other than the present invention is as shown in FIG. After 0.18 seconds (interval indicated by B1) from the start of cutting, the thrust value became stable at about 560 N (value indicated by the broken line in the figure). From this, regarding the thrust value and the time required from the start of cutting until the thrust value is stabilized, the same results as in the case of the drill according to the present invention shown in FIG. 4 were obtained. However, the thrust fluctuation range during cutting was about 90 N (thrust fluctuation range indicated by A2) in the drill according to the present invention as shown in FIG. 4, whereas in the drill outside the present invention, it is shown in FIG. Thus, it increased to about 180 N (thrust fluctuation range indicated by B2), and as a result, the thrust fluctuation range was double that of the drill according to the present invention.

  From this, even if the second angle at the chisel edge corner of the drill is the same angle (20 ° in this embodiment), the width of thrust fluctuation during cutting can be reduced by setting the second angle at the outer corner to 3 ° or more. Can be suppressed. Therefore, the drill itself can be prevented from swinging and at the same time, the hole position accuracy can be ensured.

  In the case of a drill having a constant second angle of the cutting edge as in the conventional drill, as shown in FIG. 6, in the comparative drill outside the present invention (constant at a second angle of 10 °), the thrust fluctuation during the cutting process. Since the width was about 90 N (thrust fluctuation range indicated by C4), the result was the same as that of the drill according to the present invention shown in FIG. However, regarding the thrust value and the time required for the thrust value to stabilize, the thrust value once stagnated at about 600 N after 0.18 seconds (section indicated by C1) from the start of cutting, but then again 0.29 seconds (C2 The thrust value rises to about 640 N (the value indicated by the broken line in the figure), and finally the thrust value is about 640 N (the section indicated by C3) after the start of cutting. It became stable at the value indicated by the broken line in the figure). From this, it was shown that the comparative drill outside the present invention requires a longer time to stabilize the thrust value than the drill according to the present invention, and the thrust value is also large.

  Therefore, the drill according to the present invention (the second angle 20 ° in the chisel edge corner and the second angle 3 ° in the outer corner) has a thrust value as compared with a drill having a constant second angle of the cutting edge. Since it fell, the thrust value which generate | occur | produces in both a drill and a to-be-cut material in cutting will be relieve | moderated largely. At the same time, the time required for the thrust value to stabilize is shortened.

  From the above results, the second angle in the drill according to the present invention, that is, the chisel edge corner is in the range of more than 15 ° and 25 ° or less, and the second angle in the outer corner is in the range of 3 ° to less than 8 °. Compared with the drill of the present invention, the drill shortened the time from the start of cutting until the thrust value became stable, and at the same time, the thrust value and the range of fluctuation of the thrust during cutting could be reduced.

  Next, in the above-described cutting test, in order to confirm the biting property to the work material, a drill according to the present invention (double angle 20 ° in chisel edge corner, double angle 3 ° in outer corner) and Changes in the thrust value in the XY direction in the same plane were measured using a drill outside the present invention (second angle 20 ° in the chisel edge corner, second angle 1 ° in the outer corner), and the results are shown in FIG. It explains using. The drill specifications and cutting test conditions used in this test are the same as in Example 1.

  FIG. 7A shows changes in the thrust value in the XY directions during a cutting test using the drill according to the present invention (second angle 20 ° in the chisel edge corner, third angle 3 ° in the outer corner). FIG. 4B shows changes in the thrust value in the XY direction during a cutting test using a comparative drill (second angle 20 ° in the chisel edge corner, second angle 1 ° in the outer corner) outside the present invention. The thrust value applied to the drill at the time of the cutting test performed using the drill according to the present invention was 30 N or less in any of the XY directions as shown in FIG. On the other hand, the drill outside the present invention showed a thrust value of about 30N in the X direction as shown in FIG. 7 (b), but the Y direction increased to a thrust value of about 40N.

  From the above results, the drill according to the present invention suppresses the increase of the thrust value in the same plane as compared with the drill outside the present invention, so that the drill does not run out and bites the work material. Also improved.

1 Drill 2 Chisel Edge Corner 3 Cutting Edge 4 Outer Corner Corner α1, α2 Double Corner

Claims (1)

A drill in which the second angle of the cutting edge continuously decreases from the chisel edge corner to the outer corner, and the second angle of the cutting edge in the chisel edge corner is in the range of 20 ° to 25 °. The drill is characterized in that a thrust fluctuation range of the drill during cutting can be suppressed by setting the second angle of the cutting edge in the outer corner to a range of 3 ° to 7 ° .

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