JP2014161985A - Tip structure of drill, drill having the same, and drill head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tip structure of a drill whose point angles are gradually changed, and which has particularly excellent chip discharge performance in drilling.SOLUTION: A tip structure of a drill has at a tip (3) a plurality of cutting edges (4, 104, and 204) in which tip angles (α1 and α2) are changed so as to gradually decrease from a rotation center axis (O) to an outer periphery (7). When a boundary of a region having the tip angle (α1) in a first stage from the rotation center axis (O) and a region having the tip angle (α2) in a second stage is on a circumference of a diameter (A) around the rotation center axis (O), the diameter (A) is in the range of 10% or more and 40% or less with respect to a tool diameter (D).

Description

  The present invention relates to a tip structure of a drill used for drilling a metal workpiece or the like, and a drill and a drill head having the tip structure.

  As a conventional drill, for example, there is one shown in Patent Document 1. The drill disclosed in this document is based on the technique described in Patent Document 2 corresponding to Japanese Patent Application No. 2004-242446, and the tip of the drill having a plurality of cutting edges at the tip is changed stepwise. The structure is adopted. In this document, the center angle of the drill tip, that is, the tip angle α1 of the cutting edge portion is made larger than the outer peripheral portion of the drill tip, that is, the tip angle α2 of the peripheral blade portion, and the boundary between the biting blade portion and the peripheral blade portion, A tip structure is disclosed in which the diameter of the boundary where the tip angle changes is in the range of more than 20% and less than 90% of the tool diameter. And in patent document 1, by adopting such a tip structure, in the drilling process of a high carbon steel workpiece or the like, the shoulder portion (cutting edge and leading edge between the cutting edge and the leading edge) due to contact with the processing hole. Suppression of the corner part) and frictional heat suppresses work hardening and increases the strength of the central part without impairing the strength of the shoulder. In the case of machining a large-diameter hole having a large diameter, it is described that chipping of the chamfered blade portion is suppressed.

Japanese Patent Laid-Open No. 2007-7808 JP 2006-55965 A

  In Patent Document 1, there is a description of the dimensional ratio of the boundary diameter to the tool diameter at which the tip angle changes, but the range is more than 20% and less than 90%, which is a very wide range. However, this is merely a range that can be generally adopted in the case where the drill is changed, and it is not recognized that the other performance required for the drill is taken into consideration.

  It is an object of the present invention to provide a structure for improving chip disposal in drilling, particularly with respect to a drill tip structure in which the tip angle is changed stepwise.

  Therefore, the present invention has a plurality of cutting edges (4, 104, 204) at the tip (3), and the tip angles (α1, α2) are stepped from the rotation center axis (O) toward the outer periphery (7). The tip structure of the drill changes so as to become smaller, and includes a region having a first-stage tip angle (α1) and a region having a second-stage tip angle (α2) from the rotation center axis (O). If the boundary is on the circumference of the diameter (A) centered on the rotation center axis (O), the diameter (A) is 10% or more and 40% with respect to the tool diameter (D) of the drill. It is characterized by being in the following range.

  Moreover, this invention exists in the drill which has this front-end | tip structure integrally, and the drill head which has the front-end | tip structure and can be attached or detached to a holding | maintenance part.

  In the tip structure of the drill of the present invention, the tip angle changes stepwise, so that the generated chips are distorted and the chips are easily divided. In particular, the boundary between the region having the tip angle (α1) and the region having the second stage tip angle (α2) is provided near the rotation center axis of the drill, that is, the boundary is centered on the rotation center axis (O). If the diameter (A) is on the circumference of the tool diameter (D), the segmentation generated near the rotation center axis by setting the diameter (A) in the range of 10% to 40% with respect to the tool diameter (D). The width of the difficult chip is limited to be small, and chip discharge becomes easy.

FIG. 1 is a perspective view of a drill according to a first embodiment of the present invention. FIG. 2 is a plan view of the drill of FIG. FIG. 3 is a bottom view of the drill of FIG. FIG. 4 is a front view of the drill of FIG. FIG. 5 is a right side view of the drill of FIG. FIG. 6 is a left side view of the drill of FIG. FIG. 7 is an enlarged plan view in the vicinity of the tip of the drill of FIG. FIG. 8 is a perspective view of a drill according to the second embodiment of the present invention. FIG. 9 is an enlarged perspective view of the vicinity of the tip of the drill of FIG. FIG. 10 is a plan view of the drill of FIG. FIG. 11 is a front view of the drill of FIG. FIG. 12 is an enlarged plan view in the vicinity of the tip of the drill of FIG. FIG. 13 is a perspective view of a drill according to the third embodiment of the present invention. FIG. 14 is an enlarged perspective view in the vicinity of the tip of the drill of FIG. FIG. 15 is a plan view of the drill of FIG. FIG. 16 is a bottom view of the drill of FIG. FIG. 17 is a front view of the drill of FIG. 18 is an enlarged plan view in the vicinity of the tip of the drill of FIG. FIG. 19 is a further enlarged plan view in the vicinity of the tip of the drill of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In each of the following embodiments, two cutting edges formed in a rotationally symmetric position and shape with respect to the rotation center axis O when viewed from the tip direction along the rotation center axis of the tool (drill). A drill having a tip or a tip structure thereof will be described. However, the present invention can also be applied to a drill having three or more cutting edges or a tip structure thereof, and n-fold symmetry, that is, a forming position with respect to the rotation center axis O according to the number (n) of cutting edges. Of course, the shape can be appropriately determined.

(First embodiment)
FIG. 1 is a perspective view of a drill according to a first embodiment of the present invention. 2 and 3 are a plan view and a bottom view of the drill of FIG. 1, respectively. FIG. 4 is a front view of the drill of FIG. 5 and 6 are a right side view and a left side view of the drill of FIG. 1, respectively. FIG. 7 is an enlarged plan view showing the vicinity of the tip of the drill of FIG. 2 to 7 correspond to the drills shown in FIG. 1 viewed from the directions of arrows II to VII, respectively.

  As shown in FIGS. 1 to 7, the drill 1 of the first embodiment is formed in a rotationally symmetric position and shape with respect to the rotation center axis O when viewed from the front end direction along the rotation center axis O. The two cutting edges 4 and the two chip discharge grooves 2 are provided, and an oil hole 6 is opened in the distal end surface 5 (see particularly FIG. 4). The tip angles (α1, α2) of these two cutting edges 4 change stepwise from the chisel including the tip 3 of the drill 1 on the rotation center axis O of the drill to the outer periphery 7, as shown in FIG. . In the drill 1 of this embodiment, the tip angle α1 at the first stage from the rotation center axis O is 150 °. The tip angle α2 of the second stage is 130 °, and the cutting edge 4 is extended to the outer periphery 7 at this angle. As shown in FIG. 7, a range having the first-stage tip angle α1 is a range from the rotation center axis O to the diameter A. In the drill 1 of this embodiment, the diameter A is about 3.5 mm, while the tool diameter D is about 10 mm. Therefore, in the drill 1 of this embodiment, the diameter A is about 35% of the tool diameter D. That is, the boundary between the region forming the first-stage tip angle α1 and the region forming the second-stage tip angle α2 (these regions may be smoothly connected by a curve) is close to the rotation center axis O. The position is far from the outer periphery 7.

  By adopting such a tip structure, the generated chips are distorted, the chips are easily divided, and the width of the chips discharged from the vicinity of the rotation center axis O is reduced as will be described later. It has been confirmed that chip disposal is easy. Here, easy chip control has two meanings. One is that the chip becomes easy to be finely divided due to the reduced width of the chip, and is easily discharged from the hole to be processed through the chip discharge groove 4. The other is that in the processing of the through hole, the generation of ring-shaped chips that are likely to occur when the hole is removed is suppressed. Ring-shaped chips are likely to be a problem when drilling a highly ductile metal material such as an aluminum alloy.

  In a conventional drill in which the tip angle is changed stepwise, when the main purpose is to suppress the occurrence of flash or the like, it seems that the tip angle is reduced from the general 120 °. However, the drill 1 of this embodiment has a two-stage structure in which the tip angle α1 is a large tip angle in the range of 130 ° to 160 °, and the second tip angle α2 is also a large tip angle of 130 °. Then, by bringing the boundary between the region forming the tip angle α1 and the region forming the tip angle α2 closer to the rotation center axis O, the chip discharging property is improved and the generation of the ring-shaped chip is suppressed. Note that increasing the tip angles α1 and α2 means that the dimension B (see FIG. 7) in the rotation center axis direction O of the drill from the tip 3 of the drill to the outer periphery 7 of the cutting edge is shortened. . As a result, for example, when the workpiece to be machined through the hole and the wall that is not to be drilled are facing each other with a gap in between, the tip of the drill after passing the hole through the workpiece The effect of avoiding the interference with the wall or the effect of facilitating the feed control for avoiding such interference can be obtained.

  The angle of the tip angle, the number of steps to be changed, or the position of the connecting portion between the region forming the tip angle α1 and the region forming the tip angle α2, that is, the diameter A, is suitable for the purpose of the present invention to improve chip disposal. As long as it is a thing, it can determine suitably, without being limited to this embodiment. For example, the diameter A is preferably in the range of 10% to 40% of the tool diameter D, and more preferably in the range of 20% to 35% of the tool diameter D. Further, the tip angle α1 at the first stage from the rotation center axis O is preferably in the range of 130 ° to 160 °, and more preferably in the range of 140 ° to 150 °. Furthermore, the tip angle α2 of the second stage is preferably in the range of 110 ° to 140 °, and more preferably in the range of 120 ° to 130 °.

(Second Embodiment)
FIG. 8 is a perspective view of a drill according to the second embodiment of the present invention, and FIG. 9 is an enlarged perspective view of the vicinity of the tip of the drill. 10, FIG. 11 and FIG. 12 are a plan view, a front view and an enlarged plan view of the vicinity of the tip of the drill of FIG. 8, respectively, with the drill shown in FIG. 8 viewed from the direction of arrows X to XII. It corresponds. Note that, in these drawings, the same reference numerals are assigned to corresponding portions of the respective components configured in the same manner as in the first embodiment.

  As shown in FIGS. 8 to 12, the drill 101 of this embodiment is provided with two cutting edges 104 on the ridgeline where the two chip discharge grooves 2 and the tip surface 5 intersect. Step portions 106a and 106b are provided in the vicinity of the tool rotation center axis O of these cutting edges 104 and 104, respectively, and these step portions 106a and 106b extend along the chip discharge grooves 2 and 2, respectively. ing. The step portions 106a and 106b divide the cutting edges 104 and 104 into two cutting edge portions, that is, first cutting edge portions 104a and 104c and second cutting edge portions 104b and 104d, respectively. Each of the cutting edges 104 is divided into two parts by the intervening step, so that chips are formed by being divided by the respective cutting edges 104, and the width of each of the divided chips is reduced. When the width of the chip is reduced, the chip is easily broken finely, so that an effect that the chip processing is further facilitated can be obtained.

  The position where the step portions 106a and 106b near the tool rotation center axis O are provided is aligned with the position on the circumference of the diameter A, which is the position of the boundary between the region forming the tip angle α1 and the region forming the tip angle α2. The effect of improving chip disposal is further enhanced. Further, it is desirable that the step portions 106a and 106b are provided at positions and shapes that are rotationally symmetric with respect to the tool rotation center axis O. When the step portions 106a and 106b are formed in rotationally symmetrical positions and shapes, the cutting resistance of the drill 101 acts evenly on the step portion 106a and the step portion 106b, and the accuracy of the hole position is improved particularly when drilling is performed. In addition, the finished surface roughness of the hole to be processed is also improved. However, the present invention is not limited to forming the step portions 106a and 106b at positions on the circumference of the diameter A or forming them in a rotationally symmetric position and shape, which can be appropriately determined. It is a matter. The first tip angle α1 formed by the first cutting edge portions 104a and 104c and the second tip angle α2 formed by the second cutting edge portions 104b and 104d are respectively the tip angles α1 in the first embodiment. And α2.

(Third embodiment)
FIG. 13 is a perspective view of a drill according to the third embodiment of the present invention, and FIG. 14 is an enlarged perspective view of the vicinity of the tip of the drill. 15, FIG. 16, FIG. 17 and FIG. 18 are a plan view, a bottom view, a front view, and an enlarged plan view of the vicinity of the tip, respectively, of the drill of FIG. It corresponds to the state seen from the direction. FIG. 19 is a further enlarged plan view in the vicinity of the tip of the drill of FIG. Note that, in these drawings, the same reference numerals are assigned to corresponding portions of the respective components configured in the same manner as in the first embodiment.

  As shown in FIGS. 13 to 19, the drill 201 of this embodiment is provided with step portions 206 a and 206 c on the outer peripheral side of the cutting edges 204 and 204. The shape in the vicinity of the outer peripheral side first cutting edge portions 204a and 204e provided by these step portions 206a and 206c and the step portion is referred to as an outer peripheral breaker, and is referred to by reference numeral 207. The outer peripheral breaker 207 extends along the chip discharge groove 2. In the drill 201 of this embodiment, the outer peripheral breakers 207 and 207 are formed in rotationally symmetric positions and shapes near the outer peripheries of the two cutting edges 204 and 204, respectively. However, the present invention is not limited to this, and it may be formed in any position and shape as long as it is a step that divides the cutting edge near the outer periphery. Similarly to the step portions 106a and 106b of the second embodiment, the outer peripheral breaker 207 also has an effect of easily breaking the chips finely by dividing the chips and reducing the width of the chips.

  As shown in FIG. 17, when the drill 201 is viewed from the front, that is, from the tip, the outer peripheral breaker 207 has a step, so that the width L and the height H are defined. The outer peripheral breaker 207 is provided only in the vicinity of the outer periphery, and its width L is preferably in the range of 5% or more and 10% or less with respect to the tool diameter D. The height H of the outer peripheral breaker 207 is preferably smaller than the width L, and is preferably in the range of 3% to 8% with respect to the tool diameter D.

  The drill 201 of this embodiment has the second cutting edge portions 204b and 204f and the third cutting edge portions 204c and 204g by further dividing the cutting edges 204 and 204 by the recesses 208a and 208b. The third cutting edge portions 204c and 204g are formed on the extension lines of the second cutting edge portions 204b and 204f, respectively. That is, the second cutting edge portions 204b and 204f and the third cutting edge portions 204c and 204g are formed on the same line. Hereinafter, these recesses 208a and 208b are referred to as narrow groove breakers 208a and 208b, respectively. The fine groove breakers 208a and 208b are also divided into two chips, and the width of the chips is reduced, so that the chips are easily broken finely.

  The narrow groove breakers 208a and 208b are provided one by one on the two cutting edges 204 and 204, respectively, and extend along the chip discharge groove 2. In this embodiment, as shown in FIG. 17, the two narrow groove breakers 208a and 208b are not in a rotationally symmetric position of 180 ° with respect to the tool rotation center axis O, but are offset from each other from the tool rotation center axis O. Formed in position. By forming in this way, the two narrow groove breakers 208a and 208b located at a position shifted from the tool rotation center axis O divide the chips, thereby reducing the width of the chips and making the chips fine. The effect of breaking is increased.

  In the drill 201 of this embodiment, step portions 206b and 206d are further provided in the vicinity of the tool rotation center axis O of the cutting edges 204 and 204, whereby the fourth cutting edge portion 204d is provided in the vicinity of the tool rotation center axis O. , 204h are formed. As a result, the chips are divided and formed in the respective portions 204d and 204h, and the width of each divided chip is further reduced, so that the chips can be more easily broken. These step portions 206 b and 206 d are also extended along the chip discharge grooves 2 and 2.

  Since the outer peripheral breaker 207, the narrow groove breakers 208a and 208b, and the step portions 206b and 206d are all provided along the chip discharge groove 2, they disappear even when the tool is worn and the tip surface is reground. The same cutting edge shape as a new article is reproduced by re-grinding. Their length can be arbitrarily set according to the number of necessary re-grinding.

  As described above, the step portion such as the outer peripheral breaker and the narrow groove breaker each have a function of dividing chips. By using an appropriate combination of a stepped portion such as an outer peripheral breaker and a narrow groove breaker, the chip processing performance is greatly improved by these synergistic effects.

  In the drill 201 of this embodiment, the tip angle changes twice stepwise as shown in FIG. That is, the first tip angle α1 formed by the fourth cutting edge portions 204d and 204h, the second tip angle α2 formed by the second cutting edge portions 204b and 204f and the third cutting edge portions 204c and 204g, And a third tip angle α3 formed by the first cutting edge portions 204a and 204e. The first tip angle α1 and the second tip angle α2 can be determined in the same manner as in the first embodiment, while the third tip angle α3 is in the range of 85 ° to 95 °. Is desirable, for example, 90 °. By setting it as the shape which has such 3rd front-end | tip angle (alpha) 3, generation | occurrence | production of the flash and burr of the hole to be processed are suppressed, and chip disposal property further improves.

In order to verify the effect of the present invention, the following experiment was conducted.
(First experiment)
In the first experiment, the influence of the diameter A corresponding to the position of the connecting portion between the region forming the tip angle α1 and the region forming the tip angle α2 is tested. In the experiment, a drill having the configuration shown in the first embodiment was used, the tool diameter D was all 10 mm, the tip angle α1 was 145 °, and the tip angle α2 was 125 °. And the chip processability was compared about Examples 1-3 in which the ratio of the diameter A with respect to the tool diameter D is contained in the prescription | regulation range of this invention, and Comparative Examples 1 and 2 which are not contained. The cutting conditions were such that the cutting speed was 150 m / min, the feed amount per rotation was 0.06 mm, and a through hole was formed in an aluminum alloy having a plate thickness of 10 mm.

  The results of the first experiment are shown in Table 1.

  As a result of the experiment, good chip disposal was performed when the diameter A was set to a ratio of 10% to 40% with respect to the tool diameter D. However, when the diameter A was 55% or more of the tool diameter D, the chips were broken. I can't. That is, it was confirmed that the diameter A is preferably 10% or more and 40% or less of the tool diameter D. That is, in this experiment, since a drill having a tool diameter D of 10 mm was used, the actual diameter A was preferably in the range of 1.0 mm or more and 4.0 mm or less.

(Second experiment)
In the second experiment, the chip processing performance is compared between Examples 4 to 6 in which the tip angle α1 and the tip angle α2 are included in the range defined in the first embodiment and Comparative Examples 3 to 6 that are not included. did. However, Comparative Examples 5 and 6 are comparative examples in which the tip angle does not change stepwise and the tip angle is constant from the vicinity of the tool rotation center axis to the outer periphery. In all examples, the tool diameter D is 10 mm and the diameter A is 3.5 mm. Therefore, the ratio of the diameter A to the tool diameter D is 35% included in the range defined in the present invention. The cutting conditions are the same as in the first experiment.

  The results of the second experiment are shown in Table 2.

  As a result of the experiment, the tip angle changed stepwise, and in Examples 3 to 5 in which the first tip angle α1 was included in the range of 130 ° to 160 °, good chip treatment was performed, but the tip angle α1 was In Comparative Examples 3, 4 and 6 at 165 ° and 125 °, the chips could not be broken. That is, it was confirmed that the first tip angle α1 is preferably 130 ° or more and 160 ° or less. Further, even when the tip angle was the same as the first tip angle of Example 5, in Comparative Example 5 in which the tip angle was constant, chip disposal was not possible as in Comparative Example 6. Therefore, it was confirmed that the chip disposal is improved by appropriately determining the tip angles α1 and α2 that are changed in stages.

  The drill 1 described above is detachably mounted on a machine tool such as a machining center, and can perform cutting (drilling) by giving a relative motion to a workpiece. A drilling machine or a lathe may be used for the machine tool.

  The present invention is not limited to the embodiment described above, and it goes without saying that the configuration can be changed, added, and deleted as appropriate without departing from the gist of the invention. For example, the present invention can be applied to drills having various thinning shapes and groove shapes. The present invention is also characterized by the tip structure of the drill. Therefore, in addition to being applied to a solid drill having the tip structure integrally therewith, a drill head that is detachably held on the tip side of the drill holder or holding portion, that is, a drill head employed in a so-called head replaceable drill is used. Of course, application is also possible.

DESCRIPTION OF SYMBOLS 1 Drill of 1st Embodiment 2 Groove 3 Tip 4 Cutting edge 5 Tip surface 6 Oil hole 7 Outer periphery of cutting edge 101 Drill of 2nd Embodiment 104 Cutting edge 104a, 104b, 104c, 104d Cutting edge part 106a, 106b Step 201 Drill of the third embodiment 204 Cutting edge 204a, 204b, 204c, 204d, 204e, 204f, 204g, 204h Cutting edge 206a, 206b, 206c, 206d Step 207 Peripheral breaker 208a, 208b Narrow groove breaker ( Recess)
A Diameter A
D Tool diameter O Tool rotation center axis α1 Tip angle of the first step from the rotation center axis α2 Tip angle of the second step from the rotation center axis α3 Tip angle of the third step from the rotation center axis

Claims (11)

The tip (3) has a plurality of cutting edges (4, 104, 204), and the tip angle (α1, α2) changes from the rotation center axis (O) toward the outer periphery (7) so as to decrease stepwise. The tip structure of the drill that
The boundary between the region having the first-stage tip angle (α1) and the second-step tip angle (α2) from the rotation center axis (O) is a diameter centered on the rotation center axis (O). The tip of the drill characterized in that the diameter (A) is in the range of 10% or more and 40% or less with respect to the tool diameter (D) of the drill when it is on the circumference of (A). Construction.   2. The drill tip structure according to claim 1, wherein an angle of the first stage tip angle (α1) is in a range of 130 ° to 160 °.   The cutting edge (204) has at least two cutting edge portions (204b, 204c, 204f, 204g) that are divided by the recesses (205, 206) when the drill is viewed from the distal direction along the rotation center axis. The tip structure of a drill according to claim 1 or 2, wherein the two cutting edge portions (204b, 204c, 204f, 204g) are formed on the same line. The recess (205, 206) is formed in each of the plurality of cutting edges (204),
The positions at which the recesses (205, 206) are formed in the plurality of cutting edges (204) are determined when the drill is viewed from the front end direction along the rotation center axis (O). The tip structure of the drill according to claim 3, wherein the drill tip structure is deviated from a rotationally symmetric position with respect to. The plurality of cutting edges (104, 204) are respectively formed on intersecting ridge lines of the plurality of chip discharge grooves (2) and the tip surface (5),
Each said cutting edge (104,204) is divided | segmented by the step part (106a, 106b, 206a, 206b, 206c, 206d), and the 1st cutting blade part (104a, 104c, 204a, 204e) connected to the outer periphery. 5) and a second cutting edge portion (104b, 104d, 204b, 204f) on the center side, the tip structure of the drill according to any one of claims 1 to 4.   When the drill is viewed from the front end direction along the rotation center axis, the length L of the first cutting edge portion (104a, 104c, 204a, 204e) is set to the tool diameter (D), The drill tip structure according to claim 5, wherein the drill tip structure is in a range of 5% or more and 10% or less.   When the drill is viewed from the distal direction along the rotation center axis, the first cutting edge portion (104a, 104c, 204a, 204e) and the second cutting edge portion (104b, 104d, 204b, 204f) The height H of the step portions (106a, 106b, 206a, 206b, 206c, 206d) interposed between the tool diameter (D) and the tool diameter (D) should be in the range of 3% or more and 8% or less. The tip structure of a drill according to claim 5 or 6.   Each of the plurality of cutting edges (104, 204) is divided by a stepped portion (106a, 106b, 206b, 206d), and the cutting edge portion (104b, 104d, 204d, 204h) near the rotation center axis (O). ) And a cutting edge part (104a, 104c, 204c, 204g) adjacent to the cutting edge part (104b, 104d, 204d, 204h). Drill tip structure.   The tip angle (α1, α2, α3) changes in three or more stages, and the tip angle (α3) on the outermost peripheral side is in a range of 85 ° to 95 °. The tip structure of a drill according to any one of the above.   A drill comprising the tip structure according to any one of claims 1 to 9 integrally.   A drill head comprising the tip structure according to claim 1 and detachable from a holding portion.

Images