JP3307681B2 - End mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end mill in which an outer peripheral edge of a substantially cylindrical tool main body is formed from a front end thereof to a base end side.

[0002]

2. Description of the Related Art In such end mills, it is unavoidable that wear and the like are caused on the outer peripheral edge and a cutting edge portion in the vicinity thereof as it is subjected to repeated cutting operations.
As a result, the cutting performance originally possessed by the end mill gradually deteriorates.

In the case where such wear or the like occurs, if the end mill is a so-called throw-away type end mill having a cutting edge on a throw-away tip removably mounted on a tool body, this throw-away insert is used. Replacement can restore the original cutting performance. However, if this end mill is a so-called solid end mill in which a cutting edge is formed directly on the tool body, such a means cannot be adopted, and therefore, by grinding (re-grinding) the cutting edge portion of the tool body. Thus, the above-mentioned initial cutting performance is obtained.

[0004] When a new outer peripheral edge is formed by re-polishing the cutting edge in this way, the outer peripheral edge 1 that is worn or the like is connected radially inward of the outer peripheral edge 1. Rake surface (wall facing chip rotation direction of chip discharge groove 2)
3, peripheral flank surface of the tool rotation direction rear side so on are polished toward the (right side in FIG. 14), which newly formed by a rake face 4 and the tool body 5 as shown by a chain line Y ₁ in FIG. 14 a method of forming a new peripheral cutting edge 7 at the intersection ridgeline portion between 6 and peripheral relief surface 6 connecting to the tool rotation direction rear side of the outer peripheral edge 1 radially inward as indicated by a chain line Y ₂ in FIG. 14 There is a method in which polishing is performed, and a new outer peripheral edge 9 is formed at the intersection ridge line between the new outer flank 8 and the rake face 3 formed thereby.

[0005] However, comparing these methods, in order to form a new outer peripheral blade 7 or 9 at the same outer diameter d indicated by a broken line in FIG. As shown, the former method requires a large polishing allowance t ₁ , while the latter method requires a much smaller polishing allowance t ₂ . In such an end mill, a cutting angle is often given to the outer peripheral edge 1 to reduce the cutting resistance. In such a case, the chip discharge groove 2 is also formed in a spiral shape on the outer periphery of the tool body 1. Becomes For this reason, in the case of the former method, re-polishing must be performed while accurately moving the grinding wheel in a spiral shape along the chip discharge groove 2, and corresponding equipment and technology are required. Becomes Therefore, in the case of performing such re-polishing, the latter method has generally been generally used.

[0006]

On the other hand, in the manufacturing process of such a solid end mill, when forming the outer peripheral edge 1 having the twist angle as described above, first, the chip discharge groove 2 is formed in a spiral shape. The tool body 5 thus set is set in a grinding device, and then, as shown in FIG. 15, a disc-shaped grinding wheel 10 is inserted into the chip discharge groove 2, and a predetermined wheel swing angle A is given to the grinding wheel 10. The grinding wheel shaft 11 is fixed as described above. Thereafter, the grinding wheel 10 is rotated around the grinding wheel shaft 11, and the tool body 5 is rotated in the axial direction while rotating around the torsion angle given to the outer peripheral blade 1. The wall 3 facing the tool rotation direction of the chip discharge groove 2 is ground and formed into a predetermined shape by the ridge line portion between one side surface and the peripheral surface and the peripheral portion thereof, and the intersection between the wall surface 3 and the outer peripheral flank 6 is formed. The outer peripheral edge 1 is formed on the ridge. The cutting edge portion of the outer peripheral blade 1 in a cross section perpendicular to the axis of the end mill thus formed, that is, a cross section perpendicular to the axis is as shown in FIGS. 16 and 17. However, FIG. 16 shows a case where the radial rake angle γ ₁ of the outer peripheral edge 1 is a negative angle set on the negative angle side.
7 shows a case of a positive this radial rake angle gamma ₁ is set to a positive angle side.

However, the outer peripheral blade 1 formed in this way suffers from the above-mentioned abrasion. Therefore, a new outer peripheral blade 9 is formed by the latter method of re-polishing the outer peripheral flank 6 inward in the radial direction. Is formed, the radial rake angle γ ₉ of the new outer peripheral edge 9 changes from the initial radial rake angle γ ₁ of the outer peripheral edge 1. That is, the position of the new outer peripheral edge 9 moves radially inward from the initial position of the outer peripheral edge 1 by re-polishing,
It moves in the circumferential direction with respect to the reference plane P passing through the outer peripheral edge 1 along the wall surface 3 of the chip discharge groove 2 which faces the tool rotation direction, and a new reference plane P ₉ passing through the new outer peripheral edge 9 here.
Will be provided.

Accordingly, the radial rake angle γ ₉ of the new outer peripheral edge 9 is defined by the tangent S ₉ passing through the position of the new outer peripheral edge 9 of the line formed by the wall surface 3 in the section perpendicular to the axis and the tangent S ₉ . so that the crossing at the location of a new peripheral cutting edge 9, the new reference plane P ₉ is determined as a crossing angle between the eggplant meridian at the axial normal plane. As a result, as shown in FIG. 16, a new cutting edge 9 obtained by re-polishing the negative outer peripheral edge 1 has a larger negative rake angle γ ₁ than the initial radial rake angle γ ₁ of the outer peripheral edge 1. The radial rake angle γ ₉ is given, and even when the positive outer peripheral edge 1 is polished again as shown in FIG. 17, the new outer peripheral edge 9 has a radial rake angle γ ₁ of the original outer peripheral edge _1. 0 °, that is, a large radial rake angle γ ₉ is provided on the negative angle side.

Thus, the radial rake angle γ ₉ of the new outer peripheral edge 9 is thus changed to the radial rake angle γ 1 of the original outer peripheral edge _1.
When it becomes larger on the negative angle side, the cutting resistance first increases, and accordingly, the cutting portion of the work material and the outer peripheral edge 9
The temperature of the cutting edge of the blade increases. As a result, the material of the tool main body 5 is softened, or chips generated during cutting are welded to the tool main body 5, resulting in a significant reduction in tool life. When the rake angle γ ₉ in the radial direction is increased as described above, the rake face is formed on the rake face (the wall face of the chip discharge groove 2 facing the tool rotation direction).
Also, the distance of contact with and rubbing of the contact 3 becomes longer, which causes crater wear and the like, which further reduces the tool life.

In addition, as the cutting force increases, the bending of the tool body 1 increases, thereby increasing the surface roughness of the work material or generating undulation, thereby increasing the processing accuracy. Is significantly deteriorated. In particular, in the latter re-polishing method, the outer peripheral flank 6 of the tool main body 5 is polished inward in the radial direction to form a new outer peripheral blade 9.
Is formed, so that the tool body 5
It is inevitable that the diameter and the cross-sectional area of the tool body gradually decrease, and the rigidity of the tool body 5 also gradually decreases, and when the rigidity is reduced, the cutting force increases as described above. In such a case, the bending of the tool body 21 may be further increased, and the machining accuracy may be further deteriorated.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and is directed to the outer periphery of a tool body rotated about an axis, from the distal end of the tool body to the proximal side. with chip discharge groove is formed in the end mill made it is formed peripheral cutting edge at the intersection ridgeline portion between the outer peripheral surface of the wall and the tool body facing the tool rotational direction of the chip discharge groove Te, positive to the outer peripheral cutting edge Or negative radial rake angle γ ₁
And the wall surface of the chip discharge groove facing the tool rotation direction is at least 15% of the diameter of the tool main body from the outer peripheral edge toward the radial inside of the tool main body, and the wall surface is The intersection angle formed by a tangent passing through an arbitrary point on a line formed by the cross section perpendicular to the axis and a radial line crossing the tangent at the arbitrary point is a rake angle in the radial direction of the outer peripheral blade. γ ₁ is formed so as to be set in a range of γ ₁ ± 5 °.

[0012]

In the end mill having such a configuration, the wall surface of the chip discharge groove facing the tool rotation direction at least in a range of at least 15% of the diameter of the tool body from the initial position of the outer peripheral edge toward the radially inner side is as described above. A tangent passing through an arbitrary point on a line formed by the cross section perpendicular to the axis is a diameter line on the cross section perpendicular to the axis passing through the arbitrary point, that is, a line passing through the arbitrary point and the axis of the tool body in the cross section perpendicular to the axis. The angle is set so as to intersect with the initial radial rake angle γ ₁ of the outer peripheral edge within an angle range of γ ₁ ± 5 °. Therefore, when re-polishing is performed by the latter method described above, a new outer peripheral edge is formed as an arbitrary point on a line formed by the wall surface in the cross section perpendicular to the axis. The reference plane will coincide with the radial line, and the angle formed by the wall surface with respect to the new reference plane at the position of the new outer peripheral blade, that is, the radial rake angle of the new outer peripheral blade is the arbitrary arbitrary It will coincide with the intersection angle between the tangent and the radial line that intersect at the point.

Therefore, according to the end mill having the above structure,
When the radial rake angle of the new outer peripheral edge is within 15% of the diameter of the tool body radially inward from the original outer peripheral edge, γ ¹ ± 5 with respect to the initial radial rake angle γ ₁ °, that is, the variation in the radial rake angle of the outer peripheral blade due to re-polishing can be suppressed within a small range of ± 5 °, and the initial outer peripheral blade The rake angle in the radial direction can be maintained. As a result, it is possible to prevent a situation in which the cutting resistance is significantly increased in the end mill after the re-grinding, and it is possible to suppress a decrease in tool life and maintain the processing accuracy.

In the present invention, the intersection angle between the tangent and the radial line is defined as γ _{1 with} respect to the radial rake angle γ _1.
The reason for adopting the configuration of setting the range of ± 5 ° within the range of at least 15% of the diameter of the tool main body from the initial outer peripheral edge toward the radial inside of the tool main body is as follows. by. That is, in such an end mill, each time a new outer peripheral edge is formed by the latter re-polishing method, the outer peripheral flank of the tool body is sequentially polished radially inward, and the tool The diameter of the body gradually decreases. As a result, the cutting speed of the outer peripheral blade at the same rotation speed gradually decreases from the initially set value, and the rigidity of the tool body also decreases. For this reason, it is impossible to endlessly grind the outer peripheral flank. Usually, the outer peripheral flank is polished from the position of the original outer peripheral edge to the inner side in the radial direction by about 15% of the initial diameter of the tool body. By the way, re-polishing is stopped and discarded. Therefore, it is practically meaningless to adopt the above-described configuration in a portion radially inward from this, and if the configuration is employed within the range of 15% of the tool body diameter, it is practically impossible. That's enough.

Further, in the present invention, the intersection angle between the tangent line and the radial line in the cross section perpendicular to the axis is set in the range of γ ₁ ± 5 ° with respect to the initial radial rake angle γ ₁ of the outer peripheral blade. If the change in the direction rake angle is suppressed within such a range, the influence of the change such as an increase in cutting resistance can be slightly suppressed. If the crossing angle exceeds this range, adverse effects such as fluctuations in the radial rake angle due to re-polishing and an increase in cutting resistance due to this cannot be ignored, leading to a significant reduction in tool life. May occur. Incidentally, it is naturally desirable that the variation of the intersection angle is small, and if possible, γ ₁ ±
It is better to be within the 3 ° range.

[0016]

1 to 4 show an embodiment of the present invention. In these figures, the tool main body 21 is formed of a hard material such as a cemented carbide or tool steel and has a substantially cylindrical outer shape, and a portion on the base end side in the direction of the axis O is provided with the end mill attached to the main shaft end of the machine tool. The shank portion 22 is used for the shaping. On the other hand, in the distal end portion of the tool main body 21, two chip discharge grooves 23, 23 that open toward the distal end surface of the tool main body 21 and extend toward the base end side, are provided.
Are formed at equal intervals in the circumferential direction. Each of these chip discharge grooves 23, 23 is formed so as to draw a spiral while maintaining the same interval around the axis O, and its base end extends to the center of the tool body 21 in the direction of the axis O. Have been.

The intersecting ridge portion between the wall surfaces 24, 24 of the chip discharge grooves 23, 23 facing in the tool rotation direction (counterclockwise direction in FIGS. 2 and 3) and the outer peripheral surface 25 of the tool body 21. Are formed with outer peripheral blades 26, 26. Accordingly, the wall surface 24 is a rake face of the outer peripheral blade 26, and the outer peripheral blade 26,
Reference numeral 26 indicates that the chip discharge grooves 23 are formed spirally in accordance with the spiral shape. Incidentally, in the present embodiment, the twist angle of the outer peripheral blade 26 is set to 30 °. Further, an outer peripheral flank 27 is formed on the outer peripheral surface 25 so as to be connected rearward in the tool rotation direction of the outer peripheral blade 26. In this embodiment, the clearance angle of the outer peripheral flank 27 is 10.
° is set. Further, on the distal end surface of the tool body 21, a bottom blade 2 connected to the distal ends of these outer peripheral blades 26, 26 is provided.
8, 28 are formed so as to extend linearly toward the axis O, that is, toward the center of the distal end surface. In addition,
A long groove-shaped concave portion (gash) 29 concaved toward the base end side in the direction of the axis O is formed in the center portion of the distal end surface.

FIG. 3 is a cross section perpendicular to the axis of the tool body 21, and FIG.
6 is an enlarged view of the cutting edge portion of FIG. 6, in which the outer peripheral edge 26 is provided with a positive radial rake angle γ ₁ as shown in FIG. 4, that is, the outer peripheral edge 26 is formed as a positive cutting edge. Have been. In this embodiment, however, the radial rake angle γ ₁ of the outer peripheral blade 26 is set to 7 °.
Further, in this embodiment, the wall 24 continuing radially inside of the outer peripheral edge 26, in the axis perpendicular section, the tool rotation direction rear side of the radial line P ₁ formed by a reference plane passing through the position of the peripheral cutting edge 26 It is formed so as to draw a concave curve,
For more radially inward from the position of the outer peripheral cutting edge 26, after drawing a convex curve without exceeding the diameter line P _1,
It is formed so as to draw a concave curve smoothly continuing to this.

Here, the wall surface 24 is formed by two outer peripheral blades 26 and 2 whose curves formed by the wall surface 24 in the section perpendicular to the axis are symmetrically positioned with respect to the axis O in the section perpendicular to the axis.
Assuming that the distance between 6, ie, the diameter of the tool body 21, is D, in the range R of the length (width) from the position of the outer peripheral blade 26 to 0.15D inward in the radial direction with respect to this diameter D, Are formed so as to draw a locus as described below. That is, the curve formed by the wall surface 24 is
At any point E _x of the curved line within the range R, a tangent line S _x of the curve at this point E _x, E the point
line through the _x and the axis O, intersection angles between the radial line P _x on the axis perpendicular section through the clogging point E _x (indicated by gamma _x 4)
Is γ ₁ ± 5 with respect to the radial rake angle γ ₁ of the outer peripheral blade 26.
°, that is, in the range of 2 ° to 12 °. Incidentally, there is a position of the peripheral cutting edge 26 in FIG. 4 as a point E _1.

In the end mill having such a configuration, when the outer peripheral edge 26 is worn out or the like, the outer peripheral flank 27 is polished radially inward by the above-mentioned re-polishing method, so that a new one is obtained. Assuming that the outer peripheral blade 30 is formed at the point E ₂ shown in FIG.
Radial rake angle gamma ₂ of a tangent line S ₂ in the point E ₂ of curve wall 24 forms in the axis perpendicular section, a reference plane passing through the point E ₂ is a radial line P ₂ which forms the axial normal plane Is given as the intersection angle of. However, a broken line indicated by reference numeral 31 in FIG. 4 is a position of a new outer peripheral flank formed by the re-polishing. Thus, as described above in this embodiment, the tangent S _x of the curve through an arbitrary point E _x on the curve where the wall 24 is made in the cross section perpendicular to the shaft within the range R, the arbitrary point E _x Diameter line P formed by passing reference plane
The intersection angle with _x is the initial radial rake angle γ ₁ of the outer peripheral blade 26.
Is set so as to fall within the range of γ ₁ ± 5 °, so that the radial rake angle of the outer peripheral blade 30 formed at the point E ₂ is also equal to the initial radial rake angle γ of the outer peripheral blade 26. ₁ is formed within the range of γ ₁ ± 5 °.

Further, as a result of cutting using the new outer peripheral blade 30, wear and the like are generated on the outer peripheral blade 30, so that the new outer peripheral flank 31 is formed in the radial direction again by the latter re-polishing method. According to the end mill having the above configuration, even if the inner peripheral edge 33 is formed by polishing inward to the position indicated by the broken line 32 and forming a new outer peripheral edge 33 at the position of the point E ₃ within the range R, the cross section at the axis perpendicular to the axis is obtained. a tangent S ₃ at the point E ₃ curves the wall 24 forms, forms a straight line reference plane passing through the said point E ₃ is at the shaft cross section perpendicular, i.e. the radial line P ₃ passing through the point E ₃ in axial cross-section perpendicular There eggplant intersection angle is in the range of .gamma.1 ± 5 ° with respect to the radial rake angle gamma ₁ of the original outer peripheral cutting edge 26. As a result, the radial rake angle γ ₃ of the further outer peripheral edge 33 formed at the position of the point E ₃ is also set within the range of γ ₁ ± 5 °.

As described above, according to the end mill having the above structure, the wall surface 24 of the chip discharge groove 23 facing the tool rotation direction is
The tool body 21 is moved radially inward from the position of the outer peripheral blade 26.
In the 15% of the range R of the diameter D, a tangent S _x of the curve at any point E _x on eggplant curve wall surface 24 at a cross section perpendicular to the shaft, the arbitrary point E in this cross section perpendicular to the shaft _{Since the} intersection angle between the radial line P _x passing through _x and the radial rake angle γ ₁ of the outer peripheral blade 26 is formed within the range of γ ₁ ± 5 °, the angle R In this case, even if new outer peripheral blades 30, 33,... Are formed by polishing the outer peripheral flank 27 radially inward as a result of wear or the like of the outer peripheral blade 26, these new outer peripheral blades 30, 33,. …
Of the radial rake angles γ ₂ , γ ₃ ,... With respect to the initial radial rake angle γ ₁ of the outer peripheral blade 26 are kept within a range of γ ₁ ± 5 ° with respect to the radial rake angle γ ₁ . Will be done.

That is, according to the present embodiment, the radial rake angles γ ₁ , of the outer peripheral blades 26, 30, 33,.
It is possible to slightly suppress the fluctuation of γ ₂ , γ ₃ , ...
That is, the initial radial rake angle γ ₁ of the outer peripheral blade 26 can be maintained at a near value, thereby preventing a change in the cutting characteristics of the end mill due to such re-polishing. In particular, the radial rake angles γ ₁ , γ ₂ ,
Since γ ₃ ,... can be prevented from increasing to the negative angle side due to re-polishing as in the past, the cutting resistance generated during cutting is assumed at the time of re-polishing at the initial design of the end mill. It can be prevented from gradually increasing from the value. As a result, for example, during cutting, the temperature of the cut portion of the work material and the temperature of the cutting edges of the outer peripheral blades 30, 33,... Rise more than expected, and the tool body 21 is softened or chips are welded. Can be prevented, and a situation in which the tool life is significantly deteriorated by the re-polishing can be prevented.

According to this embodiment, the radial rake angles γ ₂ , γ ₃ ,... Of the new outer peripheral blades 30, 33,.
Since ... it can be prevented from day become larger negative angle side with respect to the radial direction rake angle gamma ₁ of the original peripheral cutting edge 26, the outer peripheral edge 30 and 33 of the chips generated during cutting, ... rake face The curl can be quickly curled, separated, and discharged without contacting the wall surface 24 that is longer than necessary. For this reason, it is possible to prevent a situation in which the distance over which the chips scrape on the rake face becomes longer and crater wear or the like occurs on the rake face. Thus, it is possible to more effectively prevent the tool life from being deteriorated due to the re-polishing described above.

Further, since the increase of the cutting force every re-polishing is suppressed as described above, the bending of the tool body 21 at the time of cutting caused by such an increase of the cutting force can be suppressed, and therefore, the coating resistance can be reduced. It is possible to prevent the machining accuracy from deteriorating by preventing an increase in the surface roughness of the work material and the occurrence of undulations. In particular, as described above, the outer peripheral flank 27 of the tool body 21 is used.
Is polished radially inward, and new outer peripheral blades 30, 3
In the latter re-grinding method of forming 3,..., It is inevitable that the diameter D and the cross-sectional area of the tool main body 21 gradually decrease with the re-grinding.
1 will also be gradually reduced. Therefore,
In the case where the cutting resistance increases as described above in the state where the rigidity is reduced, the bending of the tool body 21 due to this is further remarkable, and the increase in the surface roughness and the undulation are more severe. As a result, the processing accuracy is remarkably deteriorated. On the other hand, in the end mill having the above-described configuration, an increase in the cutting resistance can be prevented as described above, so that even if the diameter D and the cross-sectional area of the tool main body 21 are gradually reduced by the regrind, the end mill is generated during the cutting. An increase in the bending of the tool body 21 can be suppressed, thereby making it possible to suppress a deterioration in machining accuracy.

Next, a method for manufacturing such an end mill will be described with reference to FIG. In FIG. 5, reference numeral 41 denotes a grinding wheel used to form the outer peripheral edge 26 of the end mill, and reference numeral 42 denotes a grinding wheel shaft of the grinding wheel 41. This grinding wheel 41 is formed in a substantially disk shape similarly to the grinding wheel 10 shown in FIG. 15, but at the intersection ridge portion between one side surface 41A and the peripheral surface 41B which contributes to the grinding of the outer peripheral blade 26. As shown in FIG. 5B, a conical surface 41C whose diameter gradually increases as the distance from the one side surface 41A in the direction of the grinding wheel shaft 42 increases is formed. Note the conical surface 41C is formed in a uniform width W ₁ intersect at an inclination angle theta _1, also in the circumferential direction of the grinding wheel 41 with respect to the one side face 41A.

Such a grinding wheel 41 is inserted into the spirally formed chip discharge groove 23 of the tool body 21 set in the grinding device, similarly to the conventional grinding wheel 10 described above, and FIG. The grinding wheel shaft 42 is fixed so that a predetermined grinding wheel swing angle A is given as shown in FIG. Then, the grinding wheel 41 is rotated around a grinding wheel axis 42, and then the tool body 2 is rotated.
1 is fed in the direction of the axis O while rotating around the axis O according to the torsion angle (lead) given to the outer peripheral blade 26, whereby the wall surface 24 of the chip discharge groove 23 facing the tool rotation direction is formed. The outer peripheral blade 2 is formed into a predetermined shape.
6 is formed.

Here, in the grinding wheel 41 having the above-described configuration, the conical surface 41 is formed at the intersection ridge portion between the one side surface 41A and the peripheral surface 41B.
C is formed, together with the time of grinding is intersecting ridgeline portion between the conical surface 41C and the one side face 41A Yuku by shaving the portion of the peripheral cutting edge 26 (part of point E ₁ in FIG. 4), the The wall surface 2 where the portion of the conical surface 41C is continuous with the outer peripheral blade 26
The portion 4 (portion R in FIG. 4) is ground. At this time, the conical surface 41 </ b> C is
The grinding wheel 41 so that it is in sliding contact with the tool body 21
Inclined into the chip discharge groove 23 as described above.
By inserting, the positive
The wall surface 24 serving as a rake face can be ground. Only
After the grinding wheel 41 is tilted in this way,
Given the angle A, on the wall surface 24 of the spiral chip discharge groove 23
By the sliding contact, the conical surface 41C is brought into contact with its wall surface 2C.
When the sliding contact position with the grinding wheel 4 moves toward the outer peripheral side of the grinding wheel 41,
Therefore, grind the wall 24 so that it gradually shifts in the circumferential direction.
Therefore, even if the inclination angle θ ₁ is constant, the wall surface 24 is
It is formed so as to draw a convex curve as described above in an angular section
Can be Therefore, according to the method for manufacturing the end mill, one side surface 4C of the conical surface 41C of the grinding wheel 41 is provided.
By appropriately setting the intersection angle θ _{1 with} respect to 1A, the width W ₁ of the conical surface 41C, and the whetstone swing angle A of the grinding whetstone 41, the cutting edge portion of the outer peripheral blade 26 has a cross section perpendicular to the axis as shown in FIG. It is possible to produce an end mill that exhibits. Moreover, in this manufacturing method, the above-described excellent effects can be obtained without changing the grinding device or the like by simply replacing the grinding wheel 41 with a conventional grinding wheel and setting the wheel swing angle A appropriately. The advantage that end mills can be manufactured can also be obtained.

The embodiment shown in FIGS. 1 to 4 is a case where the initial radial rake angle γ ₁ of the outer peripheral blade 26 is 7 ° (conformal angle), and therefore, in the cross section perpendicular to the axis. the wall 24 is in the above range R is formed so as to draw a curve that is recessed in the tool rotation direction rear side of the radial line P ₁ formed by a reference plane passing through the position of the peripheral cutting edge 26 (point E ₁₎ However, by appropriately setting the intersection angle θ ₁ between the one side surface 41A of the grinding wheel 41 and the conical surface 41C, the width W ₁ of the conical surface 41C, and the whetstone swing angle A as shown in FIG. radial rake angle gamma ₁ of the original peripheral cutting edge 26 such that a negative angle, it is also possible to form a negative peripheral cutting edge 26. As shown in FIG. 6, the wall surface 24 facing the tool rotation direction of the chip discharge groove 23 connected to the negative outer peripheral blade 26 formed as described above has the position of the outer peripheral blade 26 (point E ₁ ) as shown in FIG. ) in the above-mentioned range R than diameter line P ₁ where the reference surface is formed through are formed so as to draw a convex curve bulging tool rotation direction. However, in FIG. 6, the same parts as those shown in FIG. 4 are denoted by the same reference numerals.

According to the end mill having the above structure,
Thus, even if the initial outer peripheral blade 26 is formed in a negative manner, at least 15% of the diameter D of the tool main body 21 from the outer peripheral blade 26 toward the radial inside of the tool main body 21.
Within the range R, the shaft above the wall 24 is intersecting the tangent S _x through an arbitrary point E _x on eggplant the convex curve at a cross section perpendicular to the shaft, to the tangent S _x at the arbitrary point E _x The intersection angle γ _x formed by the radial line P _x on the right-angle cross section is determined by the initial outer peripheral edge 26.
By forming the wall surface 24 so as to be set in the range of γ ₁ ± 5 ° with respect to the radial rake angle γ ₁ of the outer peripheral blade 26
When the outer peripheral flank 27 is polished radially inward due to wear or the like to form new outer peripheral blades 30, 33,..., The radial rake angles of the new outer peripheral blades 30, 33,. γ ₂ , γ ₃ ,... can be formed within the range of γ ₁ ± 5 ° with respect to the initial radial rake angle γ ₁ . That is, the radial rake angle gamma ₁ of the original peripheral cutting edge 26 can be maintained near a value to, thereby making it possible to obtain the same effects as described above.

Further, in each of the embodiments shown in FIGS. 1 to 4 and 6, the line formed by the wall surface 24 in the section perpendicular to the axis is formed so as to draw a convex curve within the range R. but the wall surface 24 forms lines within this range R is, the peripheral cutting edge intersection angle gamma _x is the original and the radial line P _x passing through the point E _x the tangent S _x in an arbitrary point E _x of the line If the radial rake angle γ ₁ is set to be in the range of γ ₁ ± 5 ° with respect to the radial rake angle γ ₁ , the line formed by the wall surface 24 does not necessarily have to draw a curve. As shown, the wall surface 24 may be formed so as to draw a straight line within the range R in a section perpendicular to the axis. 7 shows a case where the outer peripheral blade 26 is positive, and FIG. 8 shows a case where the outer peripheral blade 26 is negative. In these figures, the same reference numerals are assigned to the same elements as in FIG. 4 as in FIG.

As described above, the chip discharge groove 2 has a cross section perpendicular to the axis.
When the wall 24 facing the tool rotating direction of the 3 draws a straight line in the range R in order to match the tangent S _x is the straight line at an arbitrary point E _x on the straight line, newly formed by regrinding , The radial rake angles γ ₂ ,
After all, γ ₃ ,...
A radial line P passing through arbitrary points E ₂ , E ₃ ,.
_2, P _3, ... made given that the as intersection angles between. However, in the embodiment shown in these figures, since the wall surface 24 forms a straight line in a cross section perpendicular to the axis, the radial rake angles γ ₂ , γ ₃ ,... Of the new outer peripheral blades 30, 33,. blades 30 and 33, as the point E _x which ... is formed of is radially inward, that is, as re-polishing repeated, the positive angle side in the example shown in FIG. 7, the negative angle side in the example shown in FIG. 8 It will be bigger. Therefore, crossing of the most diameter of the line located inward point E _R of the range R in the embodiment shown in FIG. 7, the tangent S _R in this respect E _R and radial line P _R passing through the point E _R angle gamma _R is as long initial peripheral cutting edge 26 radially rake angle gamma gamma ₁ + 5 ° or less with respect to _1, and FIG. 8
In E _R the same point in the embodiment shown, the tangent line S _R and diameter line P
Crossing angle gamma _R with _R can fall within gamma ₁ -5 ° or more.

Also, such an end mill can be obtained by a manufacturing method as shown in FIG. In this figure, reference numeral 43 denotes a grinding wheel.
As shown in FIG. 9 (b), the outer surface of the grinding wheel has a substantially disk shape, and a groove 43C opening on both of the surfaces 43A and 43B is formed at the intersection ridge of one side surface 43A and the peripheral surface 43B. 43 are formed to have the same cross-sectional shape in the circumferential direction. In FIG. 9, the same elements as those in FIG. 4 are denoted by the same reference numerals. The grinding wheel 43 is inserted into the chip discharge groove 23 of the tool body 21 set in the grinding device and rotated around the grinding wheel shaft 42 in the same manner as in the manufacturing method shown in FIGS. You. On the other hand, while rotating the tool body 21 around the axis O,
As a result, the wall surface 24 of the chip discharge groove 23 facing the tool rotation direction is formed in a predetermined shape.

Here, when forming the wall surface 24,
The portion of the groove 43C of the grinding wheel 43 does not participate in the grinding, and the ridge portion 43D of the intersection between the groove 43C and the one side surface 43A and the ridge portion 43E of the intersection between the groove 43C and the peripheral surface 43B make the wall surface 24 Is formed.
That is, the intersecting ridge portion 43D forms a wall portion 24 which is straight in FIGS. 7 and 8, and the intersecting ridge portion 43E forms a radially inner portion. Therefore, the groove 4 of this grinding wheel 43
By appropriately setting the cross-sectional shape and dimensions of 3C and the whetstone swing angle A, as shown in FIGS. 7 and 8, the wall surface 24 of the chip discharge groove 23 facing the tool rotation direction has the above range R in the cross section perpendicular to the axis. It is possible to manufacture an end mill that forms a straight line inside.

Although the case where an end mill as shown in FIGS. 7 and 8 is manufactured by using one grinding wheel 43 has been described, such an end mill is sequentially formed by two disk-shaped grinding wheels having different outer diameters. Chip discharge groove 2
3 can also be manufactured by grinding the wall surface 24. That is, the linear portion of the wall surface 24 is ground and formed by the intersection ridge portion between one side surface and the peripheral surface of the grinding wheel having a small outer diameter, and one side surface and the peripheral surface of the grinding wheel having a large outer diameter are formed. The radially inner portion is formed by the crossed ridge line portion, and as a result, an end mill having the same wall surface 24 as the wall surface 24 ground and formed by the grinding wheel 43 shown in FIG. 9 can be obtained. You can.

[0036] Further, in the present invention, the wall 24 forms line facing the tool rotational direction of the chip discharging groove 23 in the cross section perpendicular to the shaft, through any point E _x of the line from the outer peripheral cutting edge 26 be within the range R the tangent S _x, crossing angle gamma _x formed by the radial line P _x on the axis perpendicular section crossing at this arbitrary point E _x in該接line S _x is the radial rake angle gamma ₁ of the peripheral cutting edge 26 For γ
If set to a range of ₁ ± 5 °, the wall 24 forms lines may be configured such that bent in multi-stage through the point E _F as shown in FIG. 10. Such end mills, as shown in FIG. 11, the intersecting edge line region of the one side surface 44A and the circumferential surface 44B, and the conical surface 44C of the width W ₂ which intersect at an intersection angle theta ₂ with respect to the one side surface 44A, the can be produced by using a contour substantially disk-shaped grinding wheel 44 and the conical surface 44D is formed of a width W ₃ that intersect at intersection angle theta ₃ against the conical surface 44C. Thus, in this case, portions of the peripheral cutting edge 26 (point E ₁₎ to point E _F of the wall surface 24 by the conical surface 44C grinding, is formed, radially from this point E _F by the tapered surface 44D The inner part is formed. Note that, even in this case,
The grinding wheel 44 is tilted in the same manner as
Angle A is given and the wall surface 24 of the spiral chip discharge groove 23
The conical surfaces 44C and 44D are brought into sliding contact with
The sliding contact position with the wall surface 24 is on the outer peripheral side of the grinding wheel 41.
Wall 24 so that it gradually shifts in the circumferential direction as
Is ground, that is, in the cross section perpendicular to the axis,
And relatively change the inclination of the grinding wheel 44
The grinding will be performed by shifting the sliding contact position
Then, as shown in FIG. 10 by a grinding wheel 44 as shown in FIG.
It is possible to form the wall 24 that bends in a multi-step manner as described above.
Wear. Therefore, by forming the conical surface of the intersecting ridge line portion of the grinding wheel in more stages, the wall surface of the end mill can be further increased in stages.

Further, as shown in FIG. 12, a grinding wheel 45 having an arc-shaped concave groove 45C having a cross section of a radius r is formed at the intersection ridge line between one side surface 45A and the peripheral surface 45B. By manufacturing an end mill, for example, FIG.
It is also possible to form a honing portion such as a broken line indicated by reference numeral 46 in the cutting edge portion. 10 to 1
In FIG. 2, the same elements as those in the embodiment and the manufacturing method shown in FIGS. 4 to 9 are denoted by the same reference numerals.

As described above, according to the end mill having the above configuration, the initial radial rake angle γ ₁ of the outer peripheral blade 26 can be maintained at a near value, whereby the cutting resistance remarkably increases by re-polishing. It is possible to prevent a situation in which the life of the tool is reduced or the processing accuracy is deteriorated. Therefore, in order to demonstrate such an effect, cutting was performed using a negative end mill of the embodiment in which the cross section of the cutting edge portion was shown in FIG. 6 and a conventional negative end mill as a comparative example, and the initial outer peripheral edge was cut. After the end of the service life, re-grinding is performed, cutting is performed again, and the tool life of the new outer peripheral edge is measured. Once formed, their lifetime was measured. FIG. 13 shows the result. However, in FIG.
It was set to 0%, and the life time of the new outer peripheral blade with respect to this life time was compared. The rake angle in the radial direction of the new outer peripheral blade after each re-polishing was as shown in Table 1.

[0039]

[Table 1]

As shown in Table 1, in the conventional end mill as a comparative example, as the polishing allowance increases, that is, as re-polishing increases, the radial rake angle of a new outer peripheral edge formed by the re-polishing increases. While は increases sharply toward the negative angle side, the end mill of the embodiment has no extremely large change in the radial rake angle, and the substantially initial radial rake angle of the outer peripheral blade is maintained. As shown in FIG. 13, in the end mill of the comparative example, the tool life deteriorates remarkably as re-grinding overlaps, and in the case of the outer peripheral edge polished 0.6 mm from the initial outer peripheral edge, 1 / one of the initial life.
While the tool life has deteriorated to less than 2 in the end mill of the embodiment, the tool life deterioration is moderate in the end mill of the embodiment,
Even after polishing by 0.6 mm, a life of nearly 80% of the original life could be obtained.

[0041]

According to the present invention as described above, according to the present invention, the outer
D positive or negative radial rake angle gamma ₁ is applied to the peripheral edge
In a mill, the wall surface of the chip discharge groove facing the tool rotation direction is defined by a tangent line passing through an arbitrary point on a line formed by the wall surface in a section perpendicular to the axis, and the axis perpendicular to the axis crossing the tangent at the arbitrary point. positive and negative crossing angle formed by the radial line is, with respect to the radial rake angle gamma ₁ of the original peripheral cutting edge, by forming so as to be set in the range of gamma ₁ ± 5 °, the peripheral cutting edge in this way
Also be given radial rake angle gamma ₁ of, it is possible to suppress variation in radial rake angle between the original peripheral cutting edge and a new peripheral cutting edge after regrinding in the small range, the near In value, the initial radial rake angle of the outer peripheral edge can be maintained.
As a result, it is possible to prevent the cutting resistance from increasing due to the re-polishing, and to suppress deterioration of the tool life and the processing accuracy.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a front view of the embodiment shown in FIG.

FIG. 3 is a ZZ cross-sectional view of the embodiment shown in FIG.

FIG. 4 is a sectional view at right angles to an enlarged axis of a cutting edge portion of an outer peripheral blade 26 of the embodiment shown in FIG.

5A and 5B are a perspective view and a cross-sectional view of a grinding wheel 41, respectively, showing a method of manufacturing an end mill according to the present invention.

FIG. 6 is an enlarged right-angle cross-sectional view of a cutting edge portion of an outer peripheral blade 26 according to another embodiment of the present invention.

FIG. 7 is an enlarged right-angle cross-sectional view of a cutting edge portion of an outer peripheral blade 26 according to another embodiment of the present invention.

FIG. 8 is a cross-sectional view perpendicular to an enlarged axis of a cutting edge portion of an outer peripheral blade 26 according to another embodiment of the present invention.

9A and 9B are a perspective view and a cross-sectional view of a grinding wheel 43, respectively, showing a method of manufacturing the end mill of the embodiment shown in FIGS. 7 and 8;

FIG. 10 is a cross-sectional view perpendicular to an enlarged axis of a cutting edge portion of an outer peripheral blade 26 in another embodiment of the present invention.

11 (a) is a perspective view and (b) is a cross-sectional view of a grinding wheel 44, showing a method of manufacturing the end mill of the embodiment of FIG.

FIG. 12 is a perspective view (a) showing a method of manufacturing an end mill in which the honing portion 46 is formed in the embodiment of FIG. 6;
(B) A cross-sectional view of the grinding wheel 45.

FIG. 13 is a diagram comparing the end mill of the present invention and the conventional end mill with respect to deterioration of tool life due to re-grinding.

FIG. 14 is a cross-sectional view perpendicular to the axis of the cutting edge showing two methods for re-polishing the outer peripheral blade 1 in a conventional end mill.

FIG. 15 is a perspective view illustrating a method for manufacturing a conventional end mill.

FIG. 16 is a cross-sectional view perpendicular to the axis of a cutting edge showing a change in a radial rake angle due to re-polishing in a conventional negative end mill.

FIG. 17 is a cross-sectional view perpendicular to the axis of the cutting edge showing a change in a radial rake angle due to re-polishing in a conventional positive end mill.

[Explanation of symbols]

Reference Signs List 21 tool body 23 chip discharge groove 24 wall surface (rake face) of chip discharge groove 23 facing the tool rotation direction 26 outer peripheral blade (initial outer peripheral blade) 27 outer peripheral flank surface 28 bottom blade 30, 33 new outer peripheral blade 31, 32 new Outer flank 41, 43, 44 Grinding wheel D Diameter of tool body 21 R 15% of diameter D radially inward from outer edge 26
Tangent P _x in the region gamma ₁ initial radial rake point E _x of E _x-axis wall 24 forms line at an arbitrary point S _x axis perpendicular cross-section on the line wall 24 forms at a right angle cross-section of the peripheral cutting edge 26 of the tangent S _x and longitude line P intersection angles between _x (radial rake angle of peripheral cutting edge formed at point E _x) O that intersects with a cross section perpendicular to the shaft diameter line passing through the point E _x at gamma _x point E _x Axis line of the tool body 21 A Grinding wheel swing angle of the grinding wheels 41, 43, 44

Claims (1)

(57) [Claims] 1. A chip discharge groove is formed on an outer periphery of a tool body rotated about an axis from a tip end of the tool body toward a base end, and a wall surface of the chip discharge groove facing a tool rotation direction. in the end mill made is formed peripheral cutting edge at the intersection ridgeline portion between the outer peripheral surface of the tool body, the said peripheral cutting edge gives a positive or negative radial rake angle gamma ₁
And the wall surface of the chip discharge groove facing the tool rotation direction is at least 15% of the diameter of the tool main body from the outer peripheral edge toward the radial inside of the tool main body, and the wall surface is axial. The intersection angle between a tangent passing through an arbitrary point on a line formed by the right-angled cross section and a diameter line on the axis perpendicular cross-section intersecting the tangent at the arbitrary point is a radial rake angle γ of the outer peripheral blade. end mill, characterized in that for _one, are formed so as to be set in the range of gamma ₁ ± 5 °.