JP5301454B2 - Chip type ball end mill chip material - Google Patents

Description

  The present invention relates to a chip-type ball end mill, and more particularly to a technique for further improving the sharpness and edge rigidity of a ball blade without impairing the strength and rigidity of a tool body.

(A) A shaft-shaped tool main body provided with a mounting groove at the tip so as to be orthogonal to the shaft center, and (b) a plate-like portion inserted into the mounting groove, and from the mounting groove to the outside And (c) a state where the plate-like portion of the tip is inserted into the mounting groove of the tool body and fixed integrally therewith, There is known a chip-type ball end mill in which cutting is performed by the ball blade by being driven to rotate around an axis. The ball end mill described in Patent Document 1 is an example, and the replaceable tip is detachably and integrally attached to the cylindrical tool body by a clamping means such as a bolt. Are provided with a pair of ball blades which are twisted around the axis when symmetrically mounted on the tool body. The replaceable tip is made of a hard material such as cemented carbide and provides excellent durability. On the other hand, by providing the ball blade to be twisted around its axis, the sharpness is improved and cutting resistance is reduced. And good cutting performance can be obtained. The twist of the ball blade should be formed so that it is smoothly curved within the range of the thickness of the replaceable tip between the axis of the ball blade and the outer peripheral edge when viewed from the bottom of the ball end mill. Is granted by.
JP 2004-291096 A

  However, in such a conventional tip type ball end mill, the protrusion amount of the ball blade, that is, the size of twist (twist angle, etc.) is limited by the thickness of the tip, so that the effect of improving the sharpness due to twist is not always obtained sufficiently. In some cases, the thickness of the plate is limited, so that a sufficient cutting edge rigidity is not always obtained. That is, if the chip thickness is increased, the torsion of the ball blade can be increased and the cutting edge rigidity is increased, but the groove width of the mounting groove of the tool body is increased, and accordingly, in the tip mounting portion of the tool body. Since the strength and rigidity are lowered, there is a limit to increasing the thickness of the chip. In addition, when the thickness of the chip is increased, there is another problem that the cost of the expensive chip material is significantly increased and the cost is increased.

  The present invention has been made against the background of the above circumstances, and its purpose is to improve the sharpness of the ball blade and the rigidity of the blade edge without impairing the strength and rigidity of the tool body, and to obtain even better cutting performance. Is to be able to.

In order to achieve such an object, the first invention is as follows: (a) a shaft-shaped tool body provided with a mounting groove at the tip so as to be orthogonal to the shaft center; and (b) a plate inserted into the mounting groove. And a tip provided with a ball blade at a portion protruding from the mounting groove to the outside, and (c) the plate-like portion of the tip is inserted into the mounting groove of the tool body. In the state of being integrally fixed, the cutting operation is performed by the ball blade by being driven to rotate around the axis, and (d) the ball blade of the chip is inserted into the tool body. In a bottom view as viewed from the front end side of the tool body in the mounted state, a part of the plate-like portion protrudes from the plate-like portion in the plate thickness direction from the axis to the outer peripheral edge. A smoothly curved twisted blade, and (e) its bottom surface The projection angle α formed by the straight line connecting the maximum projection portion of the ball blade in the thickness direction of the plate-like portion and the axis and the center line of the mounting groove is within a range of 20 ° to 40 °. A chip material used for a chip-type ball end mill, wherein (f) the plate-like portion and (g) the plate-like portion is inserted into the attachment groove and protrudes outside from the attachment groove. among the partial, pre-Symbol ball blade at the portion protruding from the plate-like portion, and wherein the locally be closed and thick section thickness is thicker than the plate-like portion, the integrally.

According to a second aspect of the present invention, in the chip material of the chip-type ball end mill according to the first aspect, a portion protruding outward from the mounting groove in a state where the plate-like portion is inserted into the mounting groove is a spherical surface provided with the ball blade. The thick plate portion is provided so as to partially contact the outer periphery of the semicircular arc, and the outer peripheral surface of the semicircular arc includes the thick plate portion. The spherical shape is used .

In such a chip-type ball end mill, the ball ball of the chip is a smoothly curved twist blade provided so that a part thereof protrudes from the plate-like portion in the thickness direction of the plate-like portion, and the protrusion angle Since α is in the range of 20 ° to 40 °, the ball blade is protruded greatly according to the protrusion angle α and the torsion is increased while maintaining the plate thickness of the plate-like portion of the chip at the same level as before. The That is, since the chip is formed by using a chip material integrally including a thick plate portion that is locally thicker than the plate-like portion at the portion where the ball blade protrudes, the plate thickness of the plate-like portion is conventionally reduced. The amount of protrusion of the ball blade can be increased while maintaining the same level as the above. Thus, reduction in the strength and rigidity of the tool body due to the attachment groove, and while suppressing a large increase in the chip material, with sharpness twisted ball blade increases is to further improve the wall thickness of the ball cutter The dimension (dimension in the plate thickness direction in the plate-like portion) is increased, the rigidity is improved, and more excellent cutting performance can be obtained. For example, machining accuracy and finishing quality (surface roughness, etc.) are improved by improving sharpness and rigidity, and high-rigidity processing and machining for high-hardness materials and comparatively large machining finishes and rough machining. , ing so that it can also be used in high-efficiency machining or the like.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining an example of the chip type ball end mill to which this invention was applied, (a) is a front view, (b) is a bottom enlarged view, (c) is a left side view of (a). (D) is an enlarged view of the ID-ID cross section in (a). It is a figure which shows an example of the chip | tip raw material used for the chip | tip type | mold ball end mill of FIG. 1, (a) is a front view, (b) is a right view of (a), (c) was seen from the upper direction of (a). It is a top view. It is a figure which shows another example of the chip | tip raw material used for the chip | tip type | mold ball end mill of FIG. 1, (a) is a front view, (b) is a right view of (a), (c) is from the upper direction of (a). FIG. It is a figure explaining the test product and cutting surface profile at the time of finishing using the tip type ball end mill of this invention product, the conventional product, and a comparative product, and investigating the difference in a cutting surface. It is a figure which shows the photograph of the cutting surface which is a test result of FIG. The figure explaining the test product and the test result when cutting is performed while changing the processing conditions using the two types of chip-type ball end mills of the present invention and the conventional product, and the cutting sound and the processed surface are comparatively evaluated. is there. It is a figure explaining the test product and test result when cutting is performed by changing the feed using the two types of chip-type ball end mills of the present product and the conventional product, and the cutting power is examined.

Explanation of symbols

  10: Tip type ball end mill 12: Tool body 14: Exchangeable tip (tip) 20: Mounting groove 26: Plate-like portion 28a, 28b: Ball blade 40, 50: Tip material 42a, 42b: Thick plate portion O: Center axis S: Center line of mounting groove P: Maximum projecting part α: Projection angle

  The tip type ball end mill of the present invention is suitably applied to a blade end replaceable type ball end mill that is used with the tip material detachably attached, but when the tip material is integrally fixed so as not to be removed by brazing or the like. It can also be applied to. For example, tool steel such as high-speed tool steel or alloy tool steel is preferably used as the material of the tool body, and superhard tool material such as cemented carbide, cermet, CBN is preferably used as the tip material. . The chip material is detachably attached to the tool body, for example, by a clamping device such as a screw member such as a bolt or a wedge member, or by shrink fitting.

  The protrusion angle α of the ball blade provided on the chip is generally about 15 ° in the conventional case where the ball blade is formed within the plate thickness range of the plate-like portion, and if the protrusion angle α is less than 20 °, the sharpness, etc. The effect of improving the cutting performance is not sufficiently obtained. On the other hand, if the projection angle α exceeds 40 °, it differs depending on the thickness of the plate-like portion, but the projection size from the plate-like portion becomes too large and the ball blade is easily broken, so it is set at 40 ° or less. There is a need to. This protrusion angle α is more preferably within a range of 25 ° to 35 °.

Chip is a pair of ball blades on one chip preferably provided, even when configuring the chip type ball end mill with two chips one ball blades are respectively superimposed back to back, the The invention can be applied. Further, the present invention can also be applied to a chip-type ball end mill configured with a single chip provided with one ball blade, that is, a single-chip chip-type ball end mill.

In order to facilitate processing of the ball blade and the like after mounting on the tool body, the tip material can be provided with a spherical surface on which the ball blade is provided in advance, but the ball blade is formed with high accuracy on the basis of the tool body. For this purpose, various modes are possible, for example, it is desirable to form a ball blade by performing spherical processing and gashing after attachment to the tool body.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1A and 1B are diagrams showing a chip-type ball end mill 10 to which the present invention is applied, in which FIG. 1A is a front view seen from a direction perpendicular to the axis O, FIG. 1B is an enlarged bottom view seen from the tip side, c) is a left side view of (a), and is an enlarged view of the tip portion, and (d) is a cross-sectional view of (c), that is, a cross-sectional view of ID-ID in (a). It comprises a replaceable chip 14. The tool body 12 is made of high-speed tool steel, and has a stepped columnar shape integrally provided with a large-diameter shank 16 and a small-diameter neck 18 on the shank 16 side. Rotating clockwise about the axis O as viewed from the right side is for right rotation for cutting. The tip of the neck 18 has a hemispherical shape, and is provided with a mounting groove 20 having a rectangular cross section orthogonal to the axis O, and the replaceable tip 14 is fitted into the mounting groove 20. It is clamped in the mounting groove 20 by a screw 24 as a clamping device and fixed integrally, and it can be removed by loosening the screw 24. The bottom view shown in FIG. 1B corresponds to a bottom view seen from the front end side.

  The replaceable tip 14 is made of a cemented carbide and has a plate-like portion 26 to be inserted into the mounting groove 20 with a thickness t that is substantially the same as or slightly smaller than the groove width of the mounting groove 20. , And a pair of ball blades 28a, 28b provided in a portion protruding from the mounting groove 20 to the outside. The ball blades 28a and 28b are symmetrical with respect to the axis O in the bottom view shown in FIG. 1B, and are on a single spherical surface having a diameter slightly larger than the diameter of the neck 18. A two-blade chip-type ball end mill 10 is configured that is driven to rotate by the ball blades 28a and 28b by being rotated around the axis O. Then, while being rotated around the axis O and moved in a direction perpendicular to the axis O, an arc-shaped groove or curved surface corresponding to the spherical surface is cut and a predetermined pick feed (Pf) is used. By being moved, a substantially flat plane, a predetermined two-dimensional curved surface, a three-dimensional curved surface, or the like can be cut. The bottom surface of the plate-like portion 26 opposite to the side where the ball blades 28a and 28b are provided, that is, the bottom surface opposite to the semicircular arc shape, is a flat surface and is fitted in the mounting groove 20 so as to contact the groove bottom of the mounting groove 20. By being inserted, it is positioned in a predetermined fixed posture shown in FIG. 1, and at the center of the plate-like portion 26, that is, the center of the semicircular arc shape or the vicinity thereof, the insertion hole 29 through which the screw 24 is inserted. Is provided.

  As apparent from the bottom view shown in FIG. 1B, the pair of ball blades 28a and 28b are both in the rotational cutting direction from the axis O to the outer peripheral edge, that is, the axis O in FIG. 1B. A twisted blade that curves smoothly so as to swell in the counterclockwise direction, and a portion in the vicinity of the axis O is formed within the range of the thickness t of the plate-like portion 26. The portion is formed so as to protrude from the plate-like portion 26 in the plate thickness direction, that is, the vertical direction in FIG. That is, the dimension T to the maximum protrusion part P of the ball blades 28a and 28b in the plate thickness direction of the plate-like portion 26 is larger than the plate thickness dimension t, and the maximum protrusion part P and the axis O are connected. The protrusion angle α formed by the straight line and the center line S of the mounting groove 20 is in the range of 20 ° to 40 °, and in this embodiment is in the range of 25 ° to 35 °. A predetermined flank is formed on the outer peripheral surface of the semicircular arc shape of the replaceable tip 14 continuously from the ball blades 28a, 28b, while the ball blades 28a, 28b are formed at the tip of the neck 18 of the tool body 12. Gash 30a and 30b are provided so as to be continuous with the rake face.

  The replaceable tip 14 is made into a replaceable tip 14 by performing a predetermined grinding process after being attached to the tool body 12 using the tip material 40 shown in FIG.

2A is a front view, FIG. 2B is a right side view of FIG. 2A, FIG. 2C is a plan view viewed from above of FIG. When, of which the portion protruding from the mounting groove 20 to the outside in a state where the plate-like portion 26 is fitted into the mounting groove 20, before Symbol ball blades 28a, 28b are plate-shaped portion in the thickness direction of the plate portion 26 A portion protruding from 26 is integrally provided with thick plate portions 42 a and 42 b that are locally thicker than the plate-like portion 26. Further, the semicircular arc shape similar to that of the replaceable tip 14 is formed as a whole, and the outer peripheral surface 44 of the semicircular arc has a spherical shape provided with the ball blades 28a and 28b. A ball blade having a predetermined rake face or flank face by being subjected to gashing, flank face machining, etc. in a state where the plate-like portion 26 is fitted in the mounting groove 20 and fixed integrally with the screw 24 28a and 28b are formed. The gashes 30a and 30b of the tool main body 12 may be formed at the same time by the gash processing at this time. In addition, the dashed-dotted line shown to (c) of FIG. 2 represents the ball blades 28a and 28b provided after attaching to the tool main body 12. FIG.

  The chip material 50 in FIG. 3 is the same as the chip material 40 in that the plate-like portion 26 and the thick plate portions 42a and 42b are integrally provided, but does not have a spherical semicircular arc as a whole. It has a quadrangular shape (substantially square). Accordingly, in this case, after the plate-like portion 26 is fitted into the mounting groove 20 of the tool body 12 and integrally fixed by the screw 24, spherical machining is performed on the basis of the tool body 12, and gashing and flank surfaces are performed. By performing processing or the like, the ball blades 28a and 28b having predetermined rake faces and flank faces are formed. FIGS. 3A to 3C correspond to FIGS. 2A to 2C, respectively.

  In such a chip-type ball end mill 10, the ball blades 28 a and 28 b of the replaceable chip 14 are smoothly curved so that a part thereof protrudes from the plate-like part 26 in the plate thickness direction of the plate-like part 26. Since the projection angle α is in the range of 25 ° to 35 °, the projection angle α is maintained while maintaining the plate thickness dimension t of the plate-like portion 26 of the replaceable tip 14 at the same level as before. Accordingly, the ball blades 28a and 28b are protruded greatly to increase the twist. Thereby, while suppressing a decrease in strength and rigidity of the tool body 12 due to the mounting groove 20 or a significant increase in the chip material, the torsion of the ball blades 28a and 28b is increased and the sharpness is further improved. The wall thickness dimension of the ball blades 28a and 28b (the dimension in the plate thickness direction in the plate-like portion 26) is increased, the rigidity is improved, and a further excellent cutting performance can be obtained. For example, machining accuracy and finishing quality (surface roughness, etc.) are improved by improving sharpness and rigidity, and high-rigidity processing and machining for high-hardness materials and comparatively large machining finishes and rough machining. It can also be used for high-efficiency machining.

  Further, in this embodiment, since a pair of ball blades 28a and 28b are provided on one replaceable tip 14, it is compared with a case where two tips are stacked and attached to the tool body 12 for use. The positional accuracy of the pair of ball blades 28a and 28b is increased, and the cutting performance such as processing accuracy is further improved, so that it can be more suitably used for finishing processing.

  In addition, this embodiment is a replaceable tip 14 that is detachably attached to the tool body 12 and is used as compared with a case in which the tool body 12 is integrally fixed by brazing or the like. Since the reduction of the strength of the tool body 12 due to the mounting groove 20 is likely to be a problem, the projecting dimensions of the ball blades 28a and 28b while maintaining the plate thickness dimension t of the plate-like portion 26 of the replaceable tip 14 at the same level as before. The above effect of further improving the cutting performance without impairing the strength and rigidity of the tool body 12 can be obtained more remarkably by increasing.

  Further, as shown in FIG. 3, a rectangular chip material 50 is used, and after the chip material 50 is fixed to the tool main body 12, spherical processing, gash processing, or the like is performed on the basis of the tool main body 12. When forming 28a and 28b, since the ball blades 28a and 28b are provided with high accuracy on the basis of the tool body 12, cutting performance such as processing accuracy is further improved.

Incidentally, as shown in FIG. 4 (a), a conventional product (test product No. 1) in which ball blades 28a and 28b are provided within the range of the thickness t of the plate-like portion 26 at the projection angle α = 15 °. And a product of the present invention (test product No. 2) having a projection angle α = 30 ° and a comparative product (test product No. 3) having a thin plate thickness dimension t of the plate-like portion 26 and a projection angle α = 10 °, The profile shown in FIG. 4 (b) was cut under the following processing conditions for finishing, and the processed surface quality was compared. The result shown in FIG. 5 was obtained. FIG. 4B shows a cross-sectional shape (profile) of the cut surface, with an arc radius R1 = R2 = 50 mm, a mountain height h = 30 mm, and a cutting length L = 200 mm. Note that “fz” in the following processing conditions is a feed amount per blade.
"Processing conditions"
・ Tool diameter: R10
・ Machine: Horizontal machining center ・ Work material: S50C
・ Rotation speed (N): 16000 min ⁻¹
Feed (F): 12000 mm / min (fz = 0.375 mm / t)
Cutting speed (V): 1005 m / min
・ Cutting depth (Z): 0.3 mm
・ Pick feed (Pf): 0.3mm
・ Cutting oil: None

  As is clear from the photograph of the cut surface shown in FIG. 5, according to the product of the present invention (test product No. 2), the upper conventional product (test product No. 1) and the lower comparison product (test product No. 3). In comparison, a fine cut surface with good surface roughness and gloss can be obtained. The comparative product (test product No. 3) having a protrusion angle α = 10 ° was poor in sharpness and extremely rough, and the subsequent comparative test was stopped.

FIG. 6 shows the product of the present invention (test product No. 1) with a projection angle α = 30 ° as shown in (a) and a ball within the range of the thickness t of the plate-like portion 26 with a projection angle α = 15 °. A conventional product (test product No. 2) provided with blades 28a and 28b is prepared, and the profile shown in FIG. 4 (b) is cut under the following machining conditions for intermediate finishing to rough machining. When the cutting sound and the machined surface were evaluated visually and visually, the results shown in (b) were obtained. In FIG. 4B, the arc radius R1 = R2 = 50 mm, the peak height h = 30 mm, and the cutting length L = 200 mm. Further, “fz” in the following processing conditions is a feed amount per blade.
"Processing conditions"
・ Tool diameter: R10
・ Machine: Horizontal machining center ・ Work material: S50C
・ Rotation speed (N): 3840 min ^-1
-Feed (F): 12000 mm / min (fz = 1.563 mm / t)
Cutting speed (V): 241 m / min
・ Cutting depth (Z): 1 to 4 mm
・ Pick feed (Pf): 1-5mm
・ Cutting oil: None

  In the evaluation column of FIG. 6 (b), “◎” means “excellent”, “○” means good, “△” means acceptable, and “×” means impossible. The evaluated product No. 1 of the present invention (protrusion angle α = 30 °) is almost “」 ”or“ ○ ”, and high-efficiency machining such as rough machining with a relatively large pick feed Pf and cutting depth Z. However, it was “◯” or “△”. On the other hand, in the conventional product No. 2 (projection angle α = 15 °), the pick feed Pf and the depth of cut are “◯” under the intermediate finishing conditions where the pick feed Pf and the depth of cut Z are relatively small. In rough machining in which the amount Z increases, the result is “Δ” or “x”, and the product of the present invention can obtain good cutting performance even under severer machining conditions. In addition, in the evaluation column, ◎ = 4 points, ○ = 3 points, Δ = 2 points, and x = 1 point, and the total score is 55 points for the product of the present invention, 42 points for the conventional product. It can be seen that the cutting performance of the present invention is superior as a whole.

FIG. 7 shows the product of the present invention (test product No. 1) having a projection angle α = 30 ° as shown in FIG. 7A and a ball within the range of the thickness t of the plate-like portion 26 at the projection angle α = 15 °. A conventional product (test product No. 2) provided with blades 28a and 28b is prepared, cutting is performed by changing the feed F by 20% by an override mechanism under the following processing conditions, and the cutting power ( When the maximum value was measured, the result shown in (b) was obtained. Cutting power was measured with a spindle dynamometer. Note that “fz” in the following processing conditions is a feed amount per tooth.
"Processing conditions"
・ Tool diameter: R10
・ Machine: Horizontal machining center ・ Work material: S50C
・ Rotation speed (N): 4800 min ^-1
Feed (F): 1500 mm / min (fz = 0.156 mm / t)
~ 2700mm / min (fz = 0.281mm / t)
Cutting speed (V): 302 m / min
・ Cutting depth (Z): 8mm
・ Cutting length: 200mm (horizontal drawing)
・ Cutting oil: None

  In FIG. 7 (b), the “cutting power” corresponds to the cutting force, and changes depending on the sharpness of the ball blades 28a, 28b. According to the product No. 1 of the present invention (protrusion angle α = 30 °). It can be seen that the cutting power is reduced by about 3% to 6% and the sharpness is improved as compared with the conventional product (protrusion angle α = 15 °) of the test product No2. Note that “Δ” in the column of evaluation of the conventional product is due to loud cutting sound and large chattering of the work surface, and “x” means that cutting was impossible due to chipping. Further, in the case of the override 80% of the product of the present invention, the cutting power was relatively large at 23.8 kW, but the cutting could be appropriately performed within the allowable range of cutting noise and chatter vibration. This is thought to be due to the increased twisting of the ball blades 28a and 28b, and the cutting force is distributed around the axis O and the flow of chips is smooth, while the rigidity of the ball blades 28a and 28b is improved. It is done.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention implements in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

  The tip-type ball end mill of the present invention is a smoothly curved twist blade provided so that a part of a tip ball blade protrudes from the plate-like portion in the thickness direction of the plate-like portion, and a projection angle α Is within the range of 20 ° to 40 °, so that the ball blade is protruded greatly according to the protrusion angle α while maintaining the thickness t of the plate-like portion of the chip at the same level as before, and the torsion is large. Is done. As a result, the strength and rigidity of the tool body due to the mounting groove is reduced, or a significant increase in the chip material is suppressed, while the twist of the ball blade is increased and the sharpness is further improved. Larger dimensions improve rigidity, and even better cutting performance can be obtained. In addition to high-precision finishing, machining for high-hardness materials and intermediate finishing, rough machining, It is also suitable for high efficiency machining.

Claims (2)

An axial tool body provided with a mounting groove at the tip so as to be orthogonal to the shaft center;
A chip having a plate-like portion to be inserted into the mounting groove, and a tip provided with a ball blade at a portion protruding outside from the mounting groove;
In the state where the plate-like portion of the chip is inserted into the mounting groove of the tool body and fixed integrally, the cutting operation is performed by the ball blade by being driven to rotate about the axis. While doing
The ball blade of the tip is in the thickness direction of the plate-like portion between the axis and the outer peripheral edge when viewed from the front end side of the tool body with the tip attached to the tool body. Is a smoothly curved twist blade provided so that a part of the plate protrudes from the plate-like portion,
And in the bottom view, the projection angle α formed by the straight line connecting the maximum projection portion of the ball blade and the axis in the thickness direction of the plate-like portion and the center line of the mounting groove is 20 ° to Within the range of 40 °,
A chip material used for a chip-type ball end mill,
The plate-like portion;
Of the portion protruding from the attachment groove on the outside in a state where the plate-like portion is inserted into the mounting groove, the portion of front Symbol ball cutter protrudes from the plate portion, locally plate than the plate-like portion A thick plate that is thickened;
The chip material of the chip type ball end mill, characterized in that the organic together. The portion protruding outward from the mounting groove in a state in which the plate-like portion is inserted into the mounting groove has a semicircular arc shape corresponding to the spherical shape provided with the ball blade, and the thick plate portion Is provided so as to be partially in contact with the outer periphery of the semicircular arc, and the outer peripheral surface of the semicircular arc has the spherical shape including the thick plate portion.
The tip material of the tip type ball end mill according to claim 1 characterized by things.

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