JP4540292B2 - Radius end mill - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radius end mill, and more particularly, to a radius end mill that can ensure a cutting edge strength and a tip room to achieve a long life.
[0002]
[Prior art]
For machining a three-dimensional shape such as a mold, a radius end mill in which a bottom blade and an outer peripheral blade are connected by a corner R blade is frequently used. Conventionally, in this radius end mill, in order to improve the machinability, the rake angle of the corner R blade is generally configured as a positive angle (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
Japanese Utility Model Laid-Open No. 60-142012 (4th column, lines 36-39).
[0004]
[Problems to be solved by the invention]
By the way, in recent years, in die machining, it is desired to shorten the time for cutting work, and there is a strong demand for high-speed cutting. As a result, high-speed machine tools having the performance of a rotational speed of tens of thousands of revolutions / minute and a feed speed of several to several tens of meters / minute are becoming popular. If this high-speed machine tool can be used to perform die machining with a light cutting depth and a high feed rate, the cutting operation can be made more efficient and the working time can be shortened. Therefore, it is desired to realize a radius end mill that can fully utilize the performance of the high-speed machine tool under such cutting conditions.
[0005]
However, under the processing conditions as described above, the conventional radius end mill has a problem that chipping and wear of the corner R blade occur early, and a satisfactory tool life cannot be obtained. Further, since the conventional radius end mill is not premised on the generation of a large amount of chips, there is a problem that the chip room capacity is not sufficiently secured and the chips are easily clogged.
[0006]
The present invention has been made to solve the above-mentioned problems, and it is possible to ensure the cutting edge strength and the tip room, and to achieve a long life even under cutting conditions with light cutting depth and high feed rate. The object is to provide a radius end mill that can be used.
[0007]
[Means for Solving the Problems]
In order to achieve this object, a radius end mill according to claim 1 is provided with a tool body made of a super hard material, a bottom blade provided on the tip side of the tool body, and connected to the bottom blade. The tool body is provided with a gash that forms a rake face between the bottom blade and the corner R blade in the chip discharge groove from the outer peripheral side toward the rotation axis. The tip side of the tool body In the axial center portion between a pair of bottom blades arranged symmetrically with respect to the rotation axis and extending beyond the rotation axis A leftover is formed, and the gouache is configured to have a gouache angle of 55 ° to 60 °, and the corner R blade is Beyond 0 ° It is configured to recede in a curved shape opposite to the cutting direction within a range of 20 ° or less, and the cross-sectional shape in a plane perpendicular to the slope of the groove bottom of the gasche is determined by the rake face of the bottom blade and the corner R blade. A one-sided gash surface, a gash surface connected to the one-side gash surface to form a groove bottom, and an opposing interval between the gash surface forming the groove bottom and connected to the gash surface forming the groove bottom; The three sides of the gash surface on the other side, which gradually decreases toward the groove bottom, are configured in a substantially wedge shape in cross section, and the opening angle of the gash is 55 ° or more and 70 ° or less.
[0008]
The radius end mill according to claim 2 is the radius end mill according to claim 1, wherein the gash is configured such that a rake angle of the corner R blade is a negative angle of -10 ° or more and 0 ° or less.
[0009]
The radius end mill according to claim 3 is the radius end mill according to claim 1 or 2, wherein a corner radius of the corner R blade is in a range of 1/6 or more and 1/4 or less of a blade diameter.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a front view of a radius end mill 1 according to an embodiment of the present invention, and illustration of one end side (shank side) of the radius end mill 1 is omitted in the drawing. First, the overall configuration of the radius end mill 1 will be described with reference to FIG.
[0011]
The radius end mill 1 is a solid-type end mill having a tool body 2 made of cemented carbide, and machining a machining center or the like via a holder (not shown) that holds one end of the tool body 2 (the right side in FIG. 2). It is a tool that is used for applications in which the rotational force of a machine is transmitted and three-dimensional machining such as a mold is performed. The radius end mill 1 of the present embodiment is particularly configured as a tool suitable for cutting a high hardness material at a light cutting depth and a high feed rate.
[0012]
The tool body 2 is made of a cemented carbide obtained by pressure-sintering tungsten carbide (WC) or the like, and a shank (not shown) is formed in a columnar shape on one end side (left side in FIG. 1). ing. By holding this shank by the holder, the radius end mill 1 is attached to the processing machine.
[0013]
On the other hand, as shown in FIG. 1, a blade portion 3 is formed on the other end side of the tool body 2 (right side in FIG. 1). The blade portion 3 mainly includes chip discharge grooves 4a to 4d, outer peripheral blades 5a to 5d, bottom blades 7a to 7d, corner R blades 8a to 8d, gashes 9a to 9d, and the like. Free curved surface machining such as molds is performed.
[0014]
The chip discharge grooves 4 a to 4 d are for generating, receiving and discharging chips during cutting, and the four chip discharge grooves 4 a to 4 d with twist are the rotation axis O of the tool body 2. Are arranged symmetrically. The outer peripheral blades 5a to 5d are cutting blades formed on the outer peripheral side of the tool main body 2, and the above-described chip discharge grooves 4a to 4d intersect with the lands 6a to 6c formed with a bank-like width. Four sheets are formed on each ridge line portion.
[0015]
The bottom blades 7a to 7d are cutting blades formed on the end surface (right end surface in FIG. 1) of the tool body 2, and the corner R blades 8a to 8d connect the bottom blades 7a to 7d and the outer peripheral blades 5a to 5d. A cutting edge for forming a round corner at the connecting portion. The bottom blades 7a to 7d are formed with a central recess angle ε. In this embodiment, the center recess angle ε is approximately 5 °.
[0016]
Here, the corner radius R of the corner R blades 8a to 8d is in a range of approximately D / 6 or more and approximately D / 4 or less with respect to the blade diameter (maximum diameter of the blade portion 3) D of the blade portion 3. Is preferred. When the corner radius R is smaller than approximately D / 6, the rigidity of the corner portion is reduced. On the other hand, when the corner radius R exceeds approximately D / 4, the cut in the radial direction is reduced due to the end face cutting that requires a flat surface. This is because of lowering. In this embodiment, the corner radius R of the corner R blades 8a to 8d is 2 mm (R = D / 5) with respect to the blade diameter D = 10 mm of the blade portion 3.
[0017]
The gashes 9a to 9d are grooves for improving chip discharging performance in the bottom blades 7a to 7d and the corner R blades 8a to 8d, and a total of four grooves are recessed in the chip discharging grooves 4a to 4d. Has been. As for these gashes 9a-9d, the gash surface of the one side is comprised by both scoop surfaces of the bottom blades 7a-7d and the corner R blades 8a-8d (refer FIG.2 and FIG.3), As a result, this gasche Four bottom blades 7a to 7d and corner R blades 8a to 8d are formed in each ridge line portion where 9a to 9d intersect the lands 6a to 6d, respectively.
[0018]
Here, it is preferable that the gash angles ρ of the gashes 9a to 9d are angles in a range of approximately 45 ° or more and approximately 60 ° or less. This is because if the gash angle ρ is smaller than about 45, a chip pocket having a sufficient capacity cannot be secured and chip clogging occurs. On the other hand, if the gash angle ρ exceeds about 60 °, the heart thickness becomes thin and the rigidity decreases. . In this embodiment, the gash angle ρ is approximately 55 °.
[0019]
FIG. 2 is a side view of the radius end mill 1 as seen from the direction of arrow II in FIG. As shown in FIG. 2, the gashes 9 a to 9 d are recessed in the chip discharge grooves 4 a to 4 d from the outer peripheral side toward the rotation axis O. As described above, each of the gashes 9a to 9d is a portion that forms both rake faces of the bottom blades 7a to 7d and the corner R blades 8a to 8d. The gashes 9b and 9d are formed from the lands 6a and 6c to the bottom blade 7a. , 7c is provided so as to extend forward in the cutting direction (counterclockwise in FIG. 2), while the gashes 9a, 9c are provided in the middle of the lands 6b, 6d, respectively. As a result, on the distal end side (the front side in FIG. 2) of the radius end mill 1, a leftover is formed, and the bottom blades 7 b and 7 d are extended beyond the rotational axis O, respectively.
[0020]
Further, as shown in FIG. 2, each of the gasches 9a to 9d extends linearly on the side of the bottom blades 7a to 7d and cuts on the side of the corner R blades 8a to 8d (FIG. 2). (Counterclockwise) It is formed to extend in a curved shape toward the rear side. As a result, the corner R blades 8a to 8d retreat toward the rear side in the cutting direction at a predetermined twist angle (hereinafter referred to as “retraction angle”) α, and are formed in a convex curve shape in the cutting direction. Yes.
[0021]
The receding angle α of the corner R blades 8a to 8d is preferably greater than approximately 0 ° and approximately 20 ° or less. In the conventional radius end mill, the corner R blade is generally configured to be retreated to the side opposite to the cutting direction with a twist angle of approximately 30 ° (corresponding to the retraction angle α in this embodiment). This is because wear during cutting at the corner R blades 8a to 8d can be suppressed by weakening the receding angle α to an angle of about 20 ° or less. In this embodiment, the receding angle α is approximately 15 °.
[0022]
However, the receding angle α may be substantially 0 °. That is, the corner R blades 8a to 8d may be formed in a linear shape substantially parallel to the bottom blades 7a to 7d in the radial end mill 1 front end view without retreating backward in the cutting direction (counterclockwise in FIG. 2). . Further, as shown in FIG. 2, the corner R blades 8a to 8d do not have to be formed in a curved shape in the entire region, and a part or all of the corner R blades 8a to 8d are formed in a linear shape. You may make it back backward in the cutting direction.
[0023]
FIG. 3 is a cross-sectional view of the radius end mill 1 taken along the line III-III in FIG. 2 and shows a cross-sectional shape in a plane perpendicular to the groove bottom gradient (gash angle ρ) of the gash 9b. However, the rake angle γ means a rake angle in the axial direction. In addition, since the structure of each gash 9a-9d is the same, it demonstrates using the gash 9b as a typical example.
[0024]
As shown in FIG. 3, the gash 9b is recessed in the chip discharge groove 4b in a substantially wedge shape in cross-section, and is configured such that the opening angle β gradually decreases toward the groove bottom. The opening angle β of the gash 9b is preferably about 55 ° or more and about 70 ° or less. When the opening angle β is smaller than about 55 °, the chip discharge property is reduced and chip clogging occurs. On the other hand, when the opening angle β exceeds 70 °, the cross-sectional area of the blade shape is reduced and its rigidity is reduced. This is because of a decrease. In this embodiment, the opening angle β is set to 60 °.
[0025]
Here, as described above, the rake face of the corner R blade 8b is formed by the gash face on one side of the gash 9b (left side in FIG. 3), and the rake angle γ is approximately −10 ° or more and substantially 0. It is preferable to set the recessed angle of the gash 9b so that the negative angle is less than or equal to °. This is because the cutting edge strength of the corner R blade 8b is secured while obtaining good cutting performance. In this embodiment, the rake angle γ is a negative angle of −5 °. The second corner of the corner R blade 8b is 10 °.
[0026]
Next, test results of two types of cutting tests (hereinafter referred to as “region test” and “endurance test”) performed using the radius end mill 1 configured as described above will be described. In the following description, the same symbol as the radius end mill 1 described above (for example, “R” for the corner radius) is used, but the dimension value itself is the radius end mill 1 in the above-described embodiment. Unrelated.
[0027]
FIG. 4 is a perspective view of the work material 20 used in the area test and the durability test, and the depth direction (upper left in FIG. 4) and the width direction (upper right in FIG. 4) of the work material 20 are omitted. ing.
[0028]
In the area test and the endurance test, the radius end mill 1 (not shown) is erected substantially perpendicularly to the cut surface 20a provided on the work material 20, and the radius end mill 1 is rotationally driven around the axis while FIG. As shown in FIG. 5, the surface to be cut 20a was cut by moving it in a direction substantially perpendicular to the axial center under predetermined cutting conditions (axial cutting depth aa, radial cutting depth ar).
[0029]
First, the area test will be described. The area test is a test for investigating the influence of the shapes of the corner R blades 8a to 8d and the gash angles ρ of the gashes 9a to 9d on the cutting performance. In this area test, a high-hardness material (quenched steel) is cut by a predetermined length (for example, 350 mm) under a cutting condition with a light cutting depth and a high feed rate, and whether or not cutting is possible is confirmed.
[0030]
Detailed specifications of the area test are: Work material 20: JIS-SKD61 (40HRC), cutting method: down cut (outward path) and up cut (return path), cutting oil: not used (dry cutting by air blow), machine used : Horizontal machining center, spindle rotation speed: 9550 revolutions / min, table feed speed: 15.3 m / min, tool protrusion amount: 40 mm, axial depth of cut aa: 0.25 mm, 0.5 mm, 0.75 mm, 1. Four types of 0 mm, the radial cutting depth ar: 5 mm.
[0031]
FIG. 5 is a diagram showing the results of the area test. In the area test, the radius end mill 1 (hereinafter referred to as “the product of the present invention”) in the above-described embodiment is the same as the product of the present invention, but the gash is formed only on the bottom blade portion. And a radius end mill (hereinafter referred to as “conventional product”) that does not extend to the corner R blade as in the present invention.
[0032]
There are 16 types of the present invention shown in the A1 column to the A3 column in FIG. 5, and the values of the corner radius R and the gash angle ρ are variously changed. Specifically, the corner radius R of the corner R blades 8a to 8d, the rake angle γ, the receding angle α, and the gash angle ρ of the gouache 9a to 9d are as shown in the A1 column to the A3 column of FIG. . All other specifications are the same. Number of blades: 4 blades, nominal (blade diameter D): φ10 mm, blade length: 16 mm, twist angle of chip discharge grooves 4a to 4d: 30 °, corner R blade The second angle of 8a to 8d is 10 °, the opening angle β of the gashes 9a to 9d is 60 °, and the central concave angle ε of the bottom blades 7a to 7d is 5 °.
[0033]
On the other hand, the conventional product is one type shown in the A4 column of FIG. 5, and the corner radius R, the rake angle γ, the receding angle α, and the gouache gash angle ρ of the corner R blade are respectively shown in the A4 column of FIG. As shown in In addition, as above-mentioned, as for the conventional product, since the gouache is provided only in the bottom blade part, the receding angle α (= 30 °) in the A4 column in FIG. 5 means the twist angle of the corner R blade. .
[0034]
The other specifications of the conventional product are the same as those of the product of the present invention described above, and will be omitted. The conventional product and the product of the present invention are both made of the same tool material (hard metal).
[0035]
The results of the area test are as shown in FIG. In FIG. 5, the symbols “◯”, “Δ”, and “X” mean that the cutting results are “good”, “somewhat problematic”, and “bad”, respectively. The symbol “-” means that a cutting test under such conditions has not been performed.
[0036]
First, the result of the A1 column in FIG. 5 will be described. As a result of setting the corner radius R of the corner R blades 8a to 8d to 1.5 mm and changing the rake angle γ, the product according to the present invention has a rake angle γ of −10 as shown in the A1 column of FIG. In the case of °, it was found that the best cutting performance was obtained among the conditions in the column A1.
[0037]
Specifically, when the rake angle γ is a positive angle of 10 ° (first row of the A1 column), the value of the axial cutting depth aa is 0. As shown in the A1 column of FIG. Chipping occurred at the corner R blades 8a to 8d at both 25 mm and 0.5 mm. This is probably because the rake angle γ is a positive angle of 10 °, so that the blade edge angle is small and sufficient blade edge strength cannot be secured.
[0038]
Even when the rake angle γ is set to 0 ° (second row of the A1 column), as shown in the A1 column of FIG. 5, when the value of the axial cutting depth aa reaches 1.0 mm, the corner R Chipping occurred in the blades 8a to 8d. This is because the corner radius R (1.5 mm) is smaller than the blade diameter D (φ10 mm) (R = approximately D / 6.67), and the corner portion cannot be sufficiently secured. Seem.
[0039]
The result of the A2 column in FIG. 5 will be described. As a result of setting the corner radius R of the corner R blades 8a to 8d to 2 mm and changing the gash angle ρ of the gashes 9a to 9d between 40 ° and 55 °, the product of the present invention is shown in the column A2 in FIG. As shown, it was found that better cutting performance can be obtained when the gash angle ρ is 55 °.
[0040]
Specifically, when both the rake angle γ and the receding angle α are set to 0 ° and the gash angle ρ is set to 40 ° (second row in the A2 column), the axial cut depth The aa value up to 0.5 mm showed good cutting performance as in the case of the A1 column described above. However, when the axial cut depth aa reached 0.75 mm, chip clogging occurred. It was confirmed that the chipping of the corner R blades 8a to 8d due to this occurred.
[0041]
On the other hand, when both the rake angle γ and the receding angle α are set to 0 ° and the gash angle ρ is set to 55 ° (the fourth row in the A2 column), the value of the axial cutting depth aa Even when the thickness reached 1.0 mm, generation of chip clogging was not confirmed, and good cutting performance was obtained. As a result, when the value of the axial cutting depth aa reaches 0.75 mm when the gash angle ρ is about 40 °, the chip pocket capacity corresponding to the value cannot be secured, and the chip discharge capacity is insufficient. It turned out to be.
[0042]
In the above-described A1 column, when the rake angle γ is 0 °, chipping occurs in the corner R blades 8a to 8d when the axial cut depth aa reaches 1.0 mm (A1 column). 2nd line). On the other hand, in the A2 column, as shown in the fourth line, the chipping did not occur and good cutting performance was exhibited. This is because the corner radius R (2 mm) is appropriately set with respect to the blade diameter D (φ10 mm) (R = D / 5), and the corner portion is sufficiently rigid. Seem.
[0043]
Further, as a result of comparison by changing the receding angle α in the range of 0 ° to 30 ° while fixing the gash angle ρ to 55 °, the direction in which the receding angle α is set to 0 ° or 15 ° is 30 °. It was found that better cutting performance can be obtained than in the case of. That is, when the receding angle α was set to 30 °, the cutting noise increased and chatter vibration occurred when the value of the axial cutting depth aa reached 1.0 mm.
[0044]
The result of the A3 column in FIG. 5 will be described. The corner radius R of the corner R blades 8a to 8d is set to 2.5 mm, the gash angle ρ of the gashes 9a to 9d is set to 55 °, and the rake angle R is set back to 0 °, −5 °, and −10 °. As a result of comparison by changing the angle α to 0 ° and 15 °, it was found that the product of the present invention can obtain good cutting performance in any case as shown in the A3 column of FIG.
[0045]
The result of the A4 column in FIG. 5 will be described. As shown in the A4 column of FIG. 5, the conventional product showed good cutting performance up to a value of 0.5 mm in the axial cutting depth aa, but the value of this axial cutting depth aa was 0.00. When reaching 75 mm, occurrence of chipping of the corner R blades 8a to 8d was confirmed.
[0046]
Next, the durability test will be described. In the durability test, a high hardness material (hardened steel) is cut under cutting conditions of light cutting depth and high feed rate until a predetermined flank maximum wear width VB is generated in the corner R blades 8a to 8d. This is a test for measuring the cutting distance.
[0047]
In the following description, only the points that are different from the specifications of the test specifications and the radius end mill described in the above-described region test will be described, and the description of the same test specifications and the specifications of the radius end mill will be omitted.
[0048]
Detailed specifications of the durability test are: work material 20: JIS-SKD61 (50HRC), axial cut depth aa: 0.3 mm, and test cut flank maximum wear width VB: 0.1 mm.
[0049]
FIG. 6 is a diagram showing the results of the durability test, and the content of the remarks column located at the right end of FIG. 6 shows the state at the end of the durability test. The durability test was performed using the product of the present invention (columns B1 to B3) and the conventional product (column B4) as in the above-described area test. For the product of the present invention, 9 types were selected from the 16 types used in the above-described area test.
[0050]
The result of the durability test is as shown in FIG. First, as shown in the B4 column of FIG. 6, in the conventional product, when the cutting distance is 15 m, the flank maximum wear width of the corner R blade reaches the test cut flank maximum wear width VB (= 0.1 mm). did. Further, at this time point, occurrence of chipping was observed in a part of the corner R blade.
[0051]
In the product of the present invention shown in the B1 column, when the cutting distance is 150 m, the maximum flank wear width of the corner R blades 8a to 8d reaches the test cut flank maximum wear width VB (= 0.1 mm). The length of the flank wear has also grown compared to other products of the present invention described later. As described above, this seems to be caused by the fact that the corner radius R (= 1.5 mm) is smaller than the blade diameter D (= φ10 mm) (R = approximately D / 6.67).
[0052]
In the product of the present invention shown in the third row of the B2 column, when the cutting distance is 80 m, the flank maximum wear width of the corner R blades 8a to 8d becomes the test cut flank maximum wear width VB (= 0.1 mm). In addition, the length of the flank wear has grown from other products of the present invention described later. This seems to be due to the fact that the receding angle α (= 30 °) is too strong.
[0053]
In the product of the present invention shown in the first row of column B3, the tool body 2 was broken during the cutting process when the cutting distance was 56 m. As described above, since the rake angle γ is a positive angle, sufficient cutting edge strength cannot be ensured, resulting in large damage to the corner R blades 8a to 8d. It seems that the tool body 2 was broken.
[0054]
On the other hand, in other products of the present invention (first and second rows in the B2 column, second to fifth rows in the B3 column), as shown in the B2 and B3 columns in FIG. At 190 m to 252 m, the maximum flank wear width of the corner R blades 8a to 8d reached the test flank flank maximum wear width VB (= 0.1 mm). Also at this time point, the corner R blades 8a to 8d did not have any defects, and the wear progressed with normal wear.
[0055]
As described above, the radius end mill 1 is provided such that the gashes 9a to 9d extend along the bottom blades 7a to 7d and the corner R blades 8a to 8d, and a chip pocket having a sufficient capacity is secured. ing. Therefore, since chip | tip accommodation and discharge | emission can be performed smoothly, the chipping and abrasion of the corner R blades 8a-8d resulting from chip | tip clogging can be suppressed.
[0056]
In addition, since the corner radius R of the corner R blades 8a to 8d is easily set to an angle γ or the like, it is possible to suppress wear and to secure the edge strength and to suppress chipping during cutting. Therefore, the life of the radius end mill 1 can be increased. As a result, it is possible to cut high-hardness materials with a light cutting depth and high feed rate using a high-speed machine tool, thereby making the cutting work more efficient and shortening the work time. It can be done.
[0057]
The present invention has been described based on the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be easily made without departing from the spirit of the present invention. It can be guessed.
[0058]
For example, in the present embodiment, the radius end mill 1 is configured as a four-blade having four cutting edges. However, the present invention is not limited to this, and the radius end mill 1 may be a two-blade or three-blade, for example. You may comprise as a blade. In this case as well, as in the above-described embodiment, a sufficient chip room capacity can be secured to prevent chip clogging.
[0059]
However, it is not preferable to use five or more cutting edges. This is because not only the capacity of the chip room is insufficient, but also the blade thickness is reduced, leading to a decrease in rigidity.
[0060]
In the present embodiment, the surface treatment of the radius end mill 1 was not particularly described, but the radius end mill 1 is made of a high-hardness material such as titanium carbide, titanium nitride, titanium carbonitride, aluminum oxide titanium, or the like alone. Alternatively, a combination of these may be multi-layer coated.
[0061]
【The invention's effect】
According to the radius end mill of the first aspect, the tool body is provided with a gash that forms a rake face between the bottom blade and the corner R blade. By forming a leftover in the axial center portion between a pair of bottom blades that are disposed symmetrically with respect to the rotation axis and extend beyond the rotation axis on the tip side of the tool body The gash angle is 55 ° or more. Therefore, since the chip pocket in the corner R blade can be made sufficiently large, even when a large amount of chips are generated, the amount of chips stored is ensured and chip clogging during cutting is reliably prevented. There is an effect that can be. In addition, since the corner R blade is configured to recede in a curved shape, that is, in a shape that can easily use the centrifugal force of the end mill, a large amount of chips contained in the gash pocket are removed from the curved corner R blade. Can be smoothly discharged to the outside. Therefore, there is an effect that chip clogging can be surely prevented. As a result, it is possible to suppress chipping and wear of the corner R blade due to chip clogging. In addition, since the gash angle is set to 60 ° or less, there is an effect that it is possible to prevent the thickness of the radius end mill from being lowered and the rigidity of the entire radius end mill from being lowered due to excessive cutting of the tool body.
[0062]
Furthermore, the gash provided in the tool body has a corner R blade in the axial front end view of the tool body. 0 ° It is comprised so that it may reverse | retreat within the range of 20 degrees or less exceeding. In the conventional radius end mill, the corner R blade is generally retracted to the opposite side of the cutting direction with a twist angle of about 30 °. In this way, the corner R blade is opposite to the cutting direction. By reducing the amount of retreat to the side, there is an effect that wear at the corner R blade can be suppressed.
[0063]
According to the radius end mill according to claim 2, in addition to the effect exerted by the radius end mill according to claim 1, the gasche is configured such that the rake angle of the corner R blade is a negative angle of -10 ° or more and 0 ° or less. Has been. Therefore, the edge strength of the corner R blade can be ensured and chipping during cutting can be suppressed, so that there is an effect that the life of the radius end mill can be extended.
[0064]
According to the radius end mill of the third aspect, in addition to the effect of the radius end mill of the first or second aspect, the corner radius of the corner R blade is set to 1/6 or more of the blade diameter. There is an effect that the rigidity can be secured and chipping or the like during cutting of the corner R blade can be suppressed. As a result, the life of the radius end mill can be extended. In addition, since the corner radius is ¼ or less of the blade diameter, the end face cutting that requires a flat surface (flat surface) can increase the cutting in the radial direction and improve the machining efficiency. There is an effect.
[Brief description of the drawings]
FIG. 1 is a front view of a radius end mill according to an embodiment of the present invention.
FIG. 2 is a side view of the radius end mill viewed from the direction of arrow II in FIG.
3 is a cross-sectional view of a radius end mill taken along line III-III in FIG. 2;
FIG. 4 is a perspective view of a work material used for an area test and an endurance test.
FIG. 5 is a diagram showing the results of a region test.
FIG. 6 is a diagram showing a result of an endurance test.
[Explanation of symbols]
1 Radius end mill
2 Tool body
8a-8d Corner R blade
7a-7d Bottom blade
9a-9d Gash
R Corner radius of the R blade
γ Rake angle of corner R blade
α Corner R blade receding angle
ρ Gash angle

Claims (3)

In a radius end mill comprising a tool body made of a super hard material, a bottom blade provided on the tip side of the tool body, and a corner R blade provided in connection with the bottom blade,
In the tool body, a gash forming a rake face between the bottom blade and the corner R blade is recessed in the chip discharge groove from the outer peripheral side toward the rotation axis,
A leftover is formed in the axial center portion between a pair of bottom blades that are disposed symmetrically with respect to the rotational axis on the tip side of the tool body and extend beyond the rotational axis ,
The gouache is configured in a range where the gouache angle is 55 ° or more and 60 ° or less, and the cutting direction in the range where the corner R blade exceeds 0 ° and is 20 ° or less in the axial front end view of the tool body. Configured to recede in a curved shape on the opposite side,
A cross-sectional shape in a plane perpendicular to the slope of the groove bottom of the gash is a gash surface formed by a scoop surface of the bottom blade and the corner R blade, and a groove bottom connected to the gash surface of the one side. A cross-sectional view is formed by three surfaces of the gash surface to be formed and the gash surface on the other side connected to the gash surface forming the groove bottom and gradually facing the gash surface on the one side gradually decreasing toward the groove bottom. A radius end mill having a substantially wedge shape and an opening angle of the gash of 55 ° to 70 °.   The radius end mill according to claim 1, wherein the gouache is configured such that a rake angle of the corner R blade is a negative angle of −10 ° to 0 °.   The radius end mill according to claim 1 or 2, wherein a corner radius of the corner R blade is in a range of 1/6 or more and 1/4 or less of the blade diameter.

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