JP4941356B2 - Drilling tool - Google Patents

Description

  The present invention relates to a drilling tool.

In recent years, in the case of drilling a workpiece having a complicated shape such as an engine part of an automobile, there is a strong demand for finer chips generated during machining from the viewpoint of improving chip disposal.
As a response to this requirement, there is known a drill with a nick provided with a nick for dividing a chip obtained by cutting a part of a cutting edge of a drill tip along a flank (for example, Patent Document 1). reference.).
In this drill with a nick, a plurality of concave nicks perpendicular to the cutting edge are formed on each of the plurality of cutting blades, and these nicks shift the rotation trajectory around the axis between the cutting blades adjacent in the circumferential direction. By arranging in this manner, chips can be generated by dividing them in the width direction within a short range between nicks.
JP 2007-50477 (FIG. 1)

However, in the invention of Patent Document 1, since the nick is provided along the flank from the cutting edge, the problem that the nick must be ground again when the cutting edge of the drill tip is re-polished. was there. In order to avoid such reworking of the nick, when the nick is formed long in the direction perpendicular to the cutting edge, there is a problem that the strength decreases.
In addition, since the nick is formed so that the rotation trajectory around the axis is shifted between the cutting blades adjacent in the circumferential direction, the nick groove width, position, number, etc. cannot be freely set, and the cutting can be divided. There was a limit to the width of the waste.
In addition, since the rotation trajectory of the nicks between the cutting blades is configured to be non-uniformly spaced in the radial direction, the size of the generated chips and the manner of deformation differ between adjacent cutting blades in the circumferential direction. Come. Therefore, the thickness of some chips becomes thicker than others, the strength increases, the chips extend longer, the cutting force becomes unbalanced, and chatter vibration is induced, deteriorating the hole machining accuracy. There was a risk of it.
In addition, since it is configured to cut the uncut portion due to the nick of the machining hole cut by the preceding cutting edge in the drill rotation direction by the subsequent cutting edge in which the rotation trajectory of the nick is shifted, There was also a problem that it could not be applied to rotating tools.

  This invention is made | formed in view of the situation mentioned above, Comprising: It aims at providing the rotary tool which can divide and refine | miniaturize a chip and was excellent in chip disposal property.

In order to achieve the above object, the present invention provides the following means.
The present invention relates to a tool main body rotated about an axis, a groove formed on the outer periphery of the tool main body so as to extend from the front end toward the rear end side, and an inner side facing the front side in the tool rotation direction of the groove. A rotary tool having a rake face formed on a peripheral surface, a tip flank face formed on a tip face of the tool body, and a cutting edge formed at a cross ridge line portion between the tip flank face and the rake face. The rake face is formed in a step shape having at least one step portion divided in the radial direction of the tool body, and the rising surface of the step portion is a rotation drawn by a corner portion of the step portion. Provided is a rotary tool which is inclined rearward in the tool rotation direction and radially inward with respect to a tangent to the locus circle.

According to the present invention, since the rake face is formed in a step shape having at least one step portion divided in the radial direction of the tool body, the cutting edge is divided into the rake face and the tip flank face divided by the step portion. And is divided into a plurality of portions in the radial direction. Therefore, since cutting is performed by the plurality of divided cutting edges, it is possible to divide the chips in the width direction.
Further, since the rising surface of the step portion is inclined rearward in the tool rotation direction and radially inward with respect to the tangent of the rotation locus circle drawn by the corner portion of the step portion, the leading edge of the cutting edge leading in the tool rotation direction is inclined. The outer peripheral end portion, that is, the inner peripheral end portion of the subsequent cutting edge disposed immediately behind the corner portion does not participate in the cutting. Accordingly, there is no possibility that a step is lost due to a part of the chip being welded to the inner peripheral end portion of the subsequent cutting edge accompanying cutting, and the chip is reliably divided at the corner portion of the step portion. be able to.

In this case, according to the present invention, by appropriately setting the number of stepped portions, the width in the radial direction, and the like, and adjusting the length in the radial direction of each of the divided cutting edges, the chips are made to have a desired width. It becomes possible to subdivide. Therefore, the chip disposal can be improved by making the chips finer.
Further, unlike the conventional drill with a nick, a complicated operation of reworking the nick each time the cutting edge is repolished is not necessary. Also, it can be applied to a single blade gun drill or reamer.

In the above invention, the inclination angle α of the rising surface with respect to the tangent line may be 0 ° <α ≦ 45 °.
Moreover, in the said invention, it is good also as the level | step difference Q of the perpendicular | vertical direction with respect to the said rake face of the said step part being 0.15 mm or more and 2.0 mm or less.

Moreover, in the said invention, the said rake face is good also as being divided | segmented substantially equally in the radial direction of the said tool main body.
By doing in this way, the lengths of the plurality of divided cutting edges provided at the intersecting ridge line portion between the rake face and the tip flank which are divided substantially evenly become substantially equal. As a result, since the width of the generated chip, the manner of deformation, and the like are aligned, it is possible to make the chip finer stably and in the same manner at each of the divided cutting edges.

Further, in the above invention, the groove is formed in two rotationally symmetrical positions with respect to the axis, and the stepped portions are mutually connected to the axis on a pair of rake faces provided in these grooves. It is good also as arrange | positioning so that it may become rotationally symmetric.
By doing in this way, a plurality of cutting edges provided at the intersection ridge line part of the rake face and the tip flank divided by the step part on one rake face, and a rake divided by the step part on the other rake face The plurality of cutting edges provided at the intersecting ridge line portion of the surface and the tip flank are arranged at rotationally symmetric positions with respect to the axis. That is, a pair of cutting blades divided into a plurality of pieces are provided at rotationally symmetric positions with respect to the axis so as to constitute a two-blade rotary tool. Therefore, the balance of the cutting force acting on the cutting blade that is divided into two or more during cutting is maintained. In other words, the cutting resistance can be received in a balanced manner at each cutting edge. As a result, the rotation of the tool body is stabilized and the occurrence of vibration is suppressed, so that the machining accuracy is excellent.

  According to the rotary tool of the present invention, chips can be divided and refined, and an effect of excellent chip disposal is achieved.

Hereinafter, an embodiment of a drilling tool according to the present invention will be described with reference to FIGS.
As shown in FIG. 1, the gun drill 1 according to the present embodiment has a substantially round bar shape, and is integrally formed with a body 2 that has a blade portion and serves as a basic portion of the drill, and a rear end of the body 2. It is comprised from the shank 3 used as the handle | pattern part of a drill. The diameter φ of the gun drill 1 is, for example, 7 mm.
The body 2 is made of cemented carbide, cermet, ceramics, ultra-high pressure sintered body, etc., has a substantially cylindrical shape centering on the axis O rotated about the axis O, and has an outer peripheral portion from the front end to the rear end side. A groove 4 for discharging chips formed so as to extend toward the tip, a rake surface 5 formed on the inner peripheral surface of the groove 4 facing forward in the drill rotation direction T, and a tip clearance formed on the tip surface The surface 7 and the cutting edge 8 formed in the intersection ridgeline part of the tip flank 7 and the rake face 5 are provided.

The groove 4 is a straight groove extending linearly from the front end to the rear end side of the body 2, and two grooves 4 are provided at rotationally symmetric positions with respect to the axis O.
As shown in FIG. 2, the rake face 5 is divided into three steps substantially equally in the radial direction of the drill, and is formed in a step shape, and includes two step portions 6 and 6.
As shown in FIG. 3, the stepped portion 6 includes a divided rake face 5a facing forward in the drill rotation direction T, a rising face 6a intersecting with the divided rake face 5a, the divided rake face 5a and the rising face 6a. And a corner portion 6b intersecting with each other. The width W of the stepped portion 6 in the drill radial direction (see FIG. 4A) is set to 0.8 mm, for example. The step Q (see FIG. 4A) in the direction perpendicular to the rake face 5 of the step portion 6 is set to 0.5 mm, for example. As shown in FIG. 4 (b), the rising surface 6a is rearward in the drill rotation direction T with respect to a tangent L of a rotation locus circle (circle indicated by a chain line in the figure) drawn by the corner 6b of the step 6. It is inclined to the side and the inside in the radial direction of the drill. The inclination angle α with respect to the tangent L of the rising surface 6a is set to 15 °, for example. And each two step part (6,6) with which each of a pair of rake face 5,5 is provided so that a pair of rake face 5,5 provided in each of two groove | channels 4, 4 may be mutually rotationally symmetrical. ), (6, 6) are arranged at rotationally symmetric positions with respect to the axis O.

  The cutting edge 8 is formed by being divided into approximately three equal parts in the radial direction of the drill by the two step portions 6, 6, and the intersection of each divided rake face 5 a, 5 a, 5 a and the tip flank 7. Three ridged cutting edges 8a, 8a, 8a are provided in the ridge line portion. The lengths of these divided cutting edges 8a, 8a, 8a are substantially equal, for example, set to 0.8 mm. The pair of cutting edges 8 and 8 are arranged so that the three divided cutting edges (8 a, 8 a, 8 a) and (8 a, 8 a, 8 a) provided in each are rotationally symmetrical with respect to the axis O. The two-blade gun drill 1 is provided, and drilling is performed by the two cutting edges 8 and 8.

An oil hole 9 for ejecting cutting fluid is formed along the axis O at the center of the gun drill body.
In addition, a margin 10 is provided on the outer peripheral portion of the body 2 in a cylindrical surface portion adjacent to the rear side of the groove 4 in the drill rotation direction T. A land 11 is provided in a portion having a bank-like width from the leading edge to the heel provided at the intersection line of the margin 10 and the groove 4. On the land 11, a guide pad 12 having substantially the same shape as the margin 10 is provided at a position spaced apart from the margin 10 in the drill rotation direction T.

The operation of the gun drill 1 according to this embodiment configured as described above will be described below.
According to the gun drill 1 according to the present embodiment, each of the two cutting edges 8 and 8 is divided by the step portion 6 to form three divided cutting edges 8a and 8a. Chips that are divided into three vertically per 8 are generated.
Further, the rising surface 6a of each step portion 6 is inclined by a predetermined angle α to the rear side of the drill rotation direction T and the inner side of the drill radial direction with respect to the tangent line L of the rotation locus circle drawn by the corner portion 6b. The inner peripheral end 8b of the subsequent divided cutting edge 8a disposed immediately behind the corner 6b corresponding to the outer peripheral end of the preceding divided cutting edge 8a in the direction T does not participate in cutting (see FIG. 4B). ). Therefore, there is no case where the step Q is lost due to, for example, a part of the chips being welded to the inner peripheral end portion 8b of the subsequent divided cutting edge 8a.
That is, the chips can be reliably divided in the width direction. Since the narrow chip is easily elastically deformed and easily curled, the chip can be broken into small pieces. As a result, chip clogging does not occur and the chip disposal is excellent, so that the finish surface quality, machining accuracy, and tool life can be improved.

In this case, in the gun drill 1 according to the present embodiment, since all of the six divided cutting edges 8a involved in cutting have substantially the same length, the width of chips generated for each divided cutting edge 8a. And how to deform. As a result, only a part of the chips do not extend for a long time, and the chips can be divided and miniaturized stably in the same manner at each of the divided cutting edges 8a.
Further, the three divided cutting edges 8a, 8a, 8a provided on one cutting edge 8 and the three divided cutting edges 8a, 8a, 8a provided on the other cutting edge 8 are mutually connected to the axis O. Therefore, the cutting force acting on the two cutting edges 8 and 8 is balanced at the time of cutting. In other words, the cutting resistance can be received in a balanced manner at each of the cutting edges 8, that is, at each of the divided cutting edges 8a provided thereto. As a result, the rotation of the drill is stabilized and the occurrence of vibration is suppressed, so that the processing accuracy of the processing hole such as the hole position accuracy, the hole diameter size, the roundness, the straightness, and the finished surface roughness is excellent.
Further, since the cutting edge 8 is divided in the radial direction, there is no problem such as an increase in the cutting stroke and deterioration of the hole bottom shape due to the cutting edge 8 retreating in the axial direction for a long time. Can be maintained.

Also, unlike conventional nicked drills, where the nick groove width, position, number, etc. are limited by design, the number of stepped portions and the radial width are appropriately set according to the required chip width. be able to. That is, since the length of the divided cutting edge 8a can be set as appropriate without being restricted in design, the chip can be formed unlike a conventional nicked drill in which the width of the chip can be subdivided only to about 4 mm. It can be further refined by subdividing it to a desired width. As a result, even when drilling a workpiece with a complicated shape such as a control valve body for automobiles or engine parts, the chips can be easily discharged to the outside by making the chips finer. , Chip residue can be prevented.
Further, unlike the conventional drill with a nick, the work of reworking the nick every time the cutting edge 8 is repolished is not necessary, so that the width of the discharged chips is stabilized and the work efficiency is excellent.

  In addition, in the gun drill 1 which concerns on this embodiment, although it was set as the double blade drill which provided the two cutting blades 8, it may replace with this and may be a single blade drill as FIG. 5 shows. Moreover, it can also be set as a 3 blade drill. In this case, by configuring the three cutting edges 8 so that the respective divided cutting edges 8a are arranged symmetrically three times with respect to the axis O, the rotation of the drill can be stabilized, and vibrations can be generated. It is possible to improve the processing accuracy of the processing hole by suppressing it.

In the gun drill 1 according to the present embodiment, two step portions 6 having a width W of 0.8 mm, a step Q of 0.5 mm, and a rising surface inclination angle α of 15 ° are provided on one rake face 5. The length of the divided cutting edge 8a is set to 0.8 mm. However, the number of the stepped portions 6, the step Q, the width W, the inclination angle α of the rising surface 6a, and the length of the divided cutting edge 8a are as follows. It is not limited to, and can be set arbitrarily.
Since the number of chips corresponding to the number of the step portions 6 can be subdivided in the width direction, it is preferable to increase the number of the step portions 6 when a thinner chip is desired. For example, if the diameter φ of the drill is 12 mm, 2 to 4 steps are provided, and if the drill has a diameter of 16 mm, 3 to 5 steps are provided, so that the chips can be subdivided to a width of about 1 to 4 mm.

  The step Q of the step portion 6 is preferably 0.15 mm to 2.0 mm, more preferably 0.25 mm to 1.0 mm. This is because if the level difference Q is smaller than 0.15 mm, the level difference Q is substantially eliminated due to the welded material generated by cutting, and the chips may not be divided in the width direction. Further, if the level difference Q is larger than 2.0 mm, the cross-sectional area of the body 2 is reduced, and the rigidity of the body 2 may be reduced.

  The width W of the stepped portion 6 is preferably 4.0 mm or less, more preferably 2.0 mm or less. If the width W of the stepped portion 6 is larger than 4.0 mm, the number of the stepped portions 6 cannot be increased in the case of a drill having a small diameter φ, and the chip is made finer by increasing the number of the stepped portions 6. This may be difficult. Further, as the width W of the stepped portion 6 is smaller, the length of the divided cutting edge 8a is shortened and a finer chip is generated. Therefore, from the viewpoint of chip fragmentation, the width W of the stepped portion 6 is Smaller is preferable. However, when the step Q of the step 6 is increased, if the width W of the step 6 is too small, a narrow and deep groove is formed between the outermost step 6 and the inner wall of the processed hole. Since the chips are likely to be clogged in the groove, the chips may extend long, or the chips may be welded to the stepped portion. For this reason, the width W of the stepped portion 6 is preferably 0.2 mm or more, more preferably 0.4 mm or more. Further, in order to reduce the width W of the step portion 6 from the viewpoint of chip miniaturization, it is effective to set the step Q of the step portion 6 to be small.

  The inclination angle α of the rising surface 6a is preferably 0 ° <α ≦ 45 °, more preferably 2 ° <α ≦ 20 °. When the rising surface 6a is inclined forward in the tool rotation direction T with respect to the tangent line L of the rotation locus circle drawn by the corner 6b, cutting is also performed at the inner peripheral end 8b of the subsequent divided cutting edge 8a. This is because there is a possibility that the chips cannot be divided in the radial direction. Further, when the inclination angle α of the rising surface 6a is reduced to 0 °, the cutting break that precedes, for example, a part of the chip is welded to the inner peripheral end 8b of the cutting edge 8a that follows the cutting. This is because it is connected to the outer peripheral end (corner) 6b of the blade 8a, and there is a possibility that the chips are not divided in the width direction. Further, if the inclination angle α of the rising surface 6a exceeds 45 °, the strength of the ridge line portion where the divided rake surface 5a and the rising surface 6a intersect may not be maintained.

  In the gun drill 1 according to the present embodiment, the rake face 5 is divided into three substantially equally in the radial direction of the drill. However, the rake face 5 is not divided equally according to the purpose of use. The length may be different.

Moreover, in the gun drill 1 which concerns on this embodiment, although it decided to provide the oil hole 9 for injecting a cutting oil agent from a drill front-end | tip from a viewpoint of chip disposal improvement, it is not limited to this. In shallow hole drilling or the like, chip dischargeability can be improved by supplying cutting oil from the outside without providing an oil hole in the drill body.
Further, in the gun drill 1 according to the present embodiment, the margin 10 is provided from the viewpoint of improving the finished surface roughness and the guide pad 12 is provided from the viewpoint of improving the guide performance. Instead, only the margin 11 is provided. It is good also as providing.
Moreover, in the said embodiment, although the gun drill 1 was mentioned as an example as a drilling tool which concerns on this invention, it is not limited to this as a rotary tool which concerns on this invention, A general peeling drill, attachment It can be applied to various drilling tools such as blade drills, point drills, core drills, reamers, and boring cutters.

It is a perspective view which shows the gun drill which concerns on one Embodiment of this invention. It is a front-end | tip part enlarged view of the gun drill shown in FIG. It is a left view of the gun drill shown in FIG. It is a longitudinal cross-sectional view which shows the front-end | tip part of the gun drill shown in FIG. 1, (a) is a figure explaining the level | step difference of a step part, (b) is a figure explaining the inclination-angle of a standing surface. It is a figure which shows the modification of the gun drill of FIG. 1, (a) is a front-end | tip part enlarged view, (b) is a left view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gun drill 2 Body 4 Groove 5 Rake face 5a Divided rake face 6 Step part 6a Rising face 6b Corner part 7 Tip flank 8 Cutting edge 8a Divided cutting edge L Tangent O Axis line Q Step T Rotation direction α Rising angle

Claims (3)

Formed on a tool body rotated about an axis, a groove formed on the outer peripheral portion of the tool body so as to extend from the front end toward the rear end side, and an inner peripheral surface facing the front side in the tool rotation direction of the groove A rotary tool having a rake face formed, a tip flank formed on a tip face of the tool body, and a cutting edge formed at a cross ridge line portion between the tip flank face and the rake face,
The rake face is formed in a step shape having at least one step portion divided in the radial direction of the tool body,
The rising surface of the step portion is inclined rearward in the tool rotation direction and radially inward with respect to the tangent to the rotation locus circle drawn by the corner portion of the step portion ,
An inclination angle α of the rising surface with respect to the tangent line is 0 ° <α ≦ 45 °,
The step Q in the direction perpendicular to the rake face of the stepped portion is 0.15 mm or more and 2.0 mm or less,
The rotary tool having a width W of the stepped portion of 0.2 mm or more and 4.0 mm or less . The rotary tool according to claim 1 , wherein the rake face is divided substantially equally in a radial direction of the tool body. Two grooves are formed at rotationally symmetric positions with respect to the axis,
The rotary tool according to claim 1 or 2 , wherein the stepped portions are arranged on a pair of rake faces provided in the grooves so as to be rotationally symmetrical with respect to the axis.

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