KR100388167B1 - Indexable ball nose endmill with recess cutting edge - Google Patents

Abstract

The cutting insert's pickling consists of arch-shaped main cut, straight side pickled and recess pickled, and gives an uneven inclined surface on the upper surface, which facilitates chip evacuation, which reduces cutting resistance and reduces cutting heat generation. Disclosed is an indexable ball nose end mill with a cutting insert with greatly improved cutting strength and wear resistance. The cutting insert of the indexable ball nose end mill according to the present invention has at least one side paging clearance between the top and bottom surfaces, and is a straight lateral section, which is an arch-shaped major section at the boundary between the lateral paging clearance and the top surface. Seth pickles are located. Adjacent positions of the main cutting, straight side cutting and recess picking are to form a land surface to compensate the cutting edge stiffness of the cutting insert during the cutting operation, and provide an uneven chipbreaker on the top surface to smooth the flow of chips. do. The main cutting insert and the sub cutting insert mounted on the tip of the holder cut the workpiece into the desired shape while drawing a spherical trajectory while the holder is rotating.

Description

Indexable ball nose endmill with recess cutting edge

The present invention relates to an indexable ball nose end mill for fastening two or more ball nose-shaped cutting inserts to the tip of a rotary milling holder during milling and performing milling cutting of curved surfaces such as molds. By cutting the cutting insert into arcuate main cutting, straight side pickling and recess pickling and giving irregularities to the inclined surface of the upper surface, it is easy to discharge chips, reducing cutting resistance and reducing cutting heat generation. The present invention relates to an indexable ball nose end mill with greatly improved strength and wear resistance.

There are three types of ball nose end mills for surface milling and cutting, the first being a solid ball nose end mill made of the same material as the high speed steel or cemented carbide, and the second being a tip end of an end mill body made of tool steel. Solid indexable ball nose end mills for dispensing two cemented carbide inserts so that only inserts can be exchanged when the tool is worn, and finally indexable for use of two or more ball nose inserts on an end mill body made of tool steel. There is a ball nose end mill.

Among them, the problem that occurs when using an indexable ball nose end mill is a cutting chip entanglement caused by a decrease in surface roughness due to the position of one insert at the center of rotation of the end mill tip, a defect in the edge of the insert center, and a lack of chip discharge space. Such as distortion of the ball nose insert during machining of the ball nose insert due to the increase of the cutting load as the whole pickling of the ball nose part contributes to the cutting of the workpiece, and the chipping defect of the ball nose cutting part due to the increase of the cutting load. In order to solve this problem, various efforts have been made such as reduction of cutting force and prevention of defects in insert pickling.

For example, U.S. Patent No. 5,562,370 provides sinusoidal undulations by forming land surfaces at the same angle throughout the cutting edge, thereby reducing vibration, reducing shear forces, improving chip breaking, and improving chip flow. Cutting inserts for ball nose end mills have been disclosed.

By the way, the cutting insert formed the land surface at the same angle throughout the pickled portion to reinforce the pickling strength and give the sinusoidal relief to obtain the functions of vibration reduction and shear cutting force, but this is rather in view of the concept of cutting Due to the sinusoidal undulation, the vibration and shear cutting force increases due to thermal shock and mechanical impact on the cutting part during cutting operation, and thus the cutting resistance increases, resulting in tool life, such as defects in edges, breakage, deterioration in wear resistance and deterioration in surface finish. There has been a problem.

Another example is a cutting insert having a flat top surface or a negative inclination angle only at the corners, which leads to an increase in the cutting resistance in the entire cutting edge in the cutting operation, leading to a decrease in wear resistance. Insufficient space for facilitating chip evacuation has caused a problem of cutting chipping. On the other hand, when the upper surface is convex, the above-mentioned problems could be corrected and compensated, but there was a squareness problem due to side picking during cutting, and it was difficult to maintain and manufacture precision based on the lower surface which was flat. It is also holding. In addition, since the inclined surface is positively formed during the discharge of the chip, a large area of the chip simultaneously rubs the inclined surface, thereby increasing the heat applied to the cutting insert.

As a result of the rigorous analysis of the prior art, unreasonable characteristics are caused by the change in shape and depth of cut, resulting in lower cutting edge strength, or increased cutting resistance, resulting in reduced tool life and chipping or breakage. It can be seen that this may be caused.

The present invention has been made to solve the conventional problems as described above, the object of the present invention is to make the cutting insert of the arcuate main cutting, straight side pickling and recess pickling and to form the irregularities on the inclined surface of the upper surface In addition, it is possible to provide an indexable ball nose end mill having a recess picking, in which chip dissipation is easy to reduce cutting resistance and cutting heat generation, thereby greatly improving the strength and wear resistance of the main cutting edge.

Another object of the present invention is to improve the coupling structure between the lower surface of the cutting insert and the cutting insert seating surface of the holder, so that the cutting insert is mounted on the milling holder to perform axial shear forces and circumferential rotational forces when performing cutting operations. By being able to withstand it, it is to provide a new concept of indexable ball nose end mill which has good durability and excellent repetitive tightening precision.

1 is a partially exploded perspective view of an indexable ball nose end mill according to the present invention;

2 is a coupled state of the indexable ball nose end mill according to the present invention,

3A and 3B are side views of the indexable ball nose end mill seen in the "X" and "Y" directions of FIG.

4 is a view showing a holder of the indexable ball nose end mill according to the present invention,

5 is a perspective view of a cutting insert according to the present invention,

6 is a plan view and a side view of the cutting insert according to the present invention;

7A-7C are cross-sectional views taken along the lines "A-A", "B-B", "C-C" in FIG. 5,

8 is a bottom view of a cutting insert according to the invention, and

FIG. 9 is a cross-sectional view taken along the line “D-D” of FIG. 8.

<Explanation of symbols for main parts of drawing>

10: indexable ball nose end mill 20, 22: cutting insert

30: upper surface 33: corner portion

34: main pickling 35: straight side pickling

36: recessed pickled 37: land cut

38: Land surface which is a side joint 39: Land surface which is a recess

40: lower surface 42: fixing groove

50: side

51-1,51-2,51-3,52-1,52-2,52-3: Side Forging Clearance

51-4,51-5: Corner side 80: Holder

84a, 84b: site 85a, 85b: mounting surface

86a, 86b: Straight Forge Clearance 87a, 87b: Arched Forge Clearance

88a, 88b: protrusion

In order to achieve the above object, the present invention,

A long body having a semi-circular end portion formed at a front end portion thereof, and a plurality of sites each having a cutting insert mounting surface are formed at adjacent positions of the semi-circular end portion, and a holder having a through hole formed at a central portion of the cutting insert mounting surface;

It is detachably mounted to the cutting insert mounting surface, and has a top surface, a bottom surface provided with a chip breaker, and a side surface located between the top surface and the bottom surface, and a circular opening is vertically in the center. It is formed through, the boss portion is provided in the circular opening, and provided with the corner portion provided on the upper surface to be symmetrical in the diagonal direction, the side surface at a forge clearance angle of 5 to 25 degrees from the upper surface to the lower surface A plurality of side forcing clearances and a corner side surface positioned between the plurality of side forcing clearances, the second side foraging clearances being formed symmetrically with respect to the circular opening. A first corner side surface is provided between the surface and the third side forging clearance surface, and the first side forcing clearance surface Between the first edge side, the first edge side smoothly runs to the radius of curvature, the upper side and the third side forging clearance surface, which is an arch-shaped major section formed at the boundary position between the upper surface and the first side forge clearance surface. A plurality of cutting inserts having straight side edges extending from said major edges to said corner portions in parallel with said lower surface at a boundary position of said recesses and recess recess edges formed between said straight side edges and said edge portions; And

And a fixing means for detachably mounting and fixing the cutting insert on the mounting surface of the holder.

At the cutting insert mounting surface, a protrusion is formed to protrude in the longitudinal direction of the rotation axis of the holder at an adjacent position of the through hole, and a fixing groove having a size and shape corresponding to the protrusion is formed at a central position of the lower surface. In this case, the fixing groove is formed to a predetermined depth across the circular opening along the longitudinal direction of the cutting insert. When mounting the cutting insert to the holder, the protrusion of the holder is fitted into the fixing groove of the cutting insert, and in this state is inserted into the circular opening of the cutting insert and the through hole of the holder in turn. The cutting insert is firmly engaged on the mounting surface of the holder by the fastening means.

Between the main cutout and the chip breaker of the upper surface is formed a main land surface having a width of 0.05 ~ 1.5mm inclined at an angle of -30 to +10 degrees toward the upper surface at the main cut-in. A land surface, which is a side section having a width of 0.05 to 1.5 mm, is formed to be inclined at an angle of -30 to +10 degrees from the straight side section to the upper surface between the straight side cut and the chip breaker. A land surface, which is a recess section having a width of 0.05 to 1.5 mm, is formed between the recess pickled and the chip breaker to be inclined at an angle of -30 to +10 degrees toward the upper surface at the recess pickled.

As mentioned above, the cutting insert of the indexable ball nose end mill according to the present invention has a recessed cut, which is a straight side section, which is an arc-shaped main section, and a land surface formed along these cuts, and an uneven upper surface. do. In addition, in order to prevent rotation of the cutting insert during cutting, grooves are formed in the lower surface of the cutting insert and protrusions are formed on the cutting insert mounting surface of the holder to enhance the fastening force. Therefore, chip cutting is well performed in all of the surface processing, groove processing, and hole processing, the cutting resistance at the time of cutting is excellent, and excellent cutting strength can be obtained. In addition, it is designed to show excellent picking strength and excellent chip cutting ability not only for curved processing but also for mid-cutting areas of side processing and square processing (grooving and hole processing).

Conventionally, when using the cutting insert for indexable ball nose end mills in the medium cutting area, there is a problem that the picking strength is reduced and the chip is not cut well. In the present invention, the pickled land surface is configured to overcome such problems. Chip shape change and resistance in cutting in the indexable ball nose end mill cutting area are reasonably designed by predicting the direction and angle of chip discharge and setting the shape and inclination angle of the upper surface to ensure chip cutting well. Overcome problems such as increase and seasoning.

Hereinafter, with reference to the accompanying drawings will be described in more detail the indexable ball nose end mill for mold surface processing according to the present invention.

1 and 2 are a partially exploded perspective view and a coupling state diagram of the indexable ball nose end mill according to the present invention.

As shown in Figures 1 and 2, the indexable ball nose end mill 10 for machining the curved surface according to the present invention mainly includes a cutting insert (20, 22) and a holder 80 for holding and holding it.

First, the holder 80 has an elongated body 82 that rotates about the central axis CL of the indexable ball nose end mill 10 during cutting. The rear end portion of the elongated body 82 is formed with a bag portion 81 mounted directly to the milling holder, and the semicircular end portion 83 is formed at the front end portion of the elongated body 82. At this time, the elongated body 82 has a tapered shape that gradually tapers toward the semi-circular end portion 83 from the bag portion 81.

4 is a view showing a holder of the indexable ball nose end mill according to the present invention.

As shown in FIG. 4, adjacent to the semicircular end 83 of the indexable ball nose end mill 10, a plurality of sites 84a for receiving the main cutting insert 20 and the sub cutting insert 22, respectively. 84b) is formed. The sites 84a and 84b are formed at symmetrical positions about the central axis CL of the ball nose end mill 10 at the semicircular end 83 of the holder 80. At this time, the sites 84a and 84b are provided with cutting insert mounting surfaces 85a and 85b which are planes parallel to the central axis CL of the ball nose end mill 10, respectively.

3A and 3B are side views of the indexable ball nose end mill seen in the "X" and "Y" directions of FIG.

As shown in Figs. 3A, 3B and 4, the main cutting insert 20 is mounted on the cutting insert mounting surface 85a, and the secondary cutting insert 22 is mounted on the cutting insert mounting surface 85b. Through-holes 89a and 89b are formed in the central portions of the cutting insert mounting surfaces 85a and 85b, respectively, and are cut at the time of rotation by the rotation shaft CL of the holder 80 at adjacent positions of the through-holes 89a and 89b. Protrusions 88a and 88b are formed to prevent rotation of the inserts 20 and 22. The projections 88a and 88b are formed to protrude in the longitudinal direction of the rotation axis CL of the holder 80 on the cutting insert mounting surfaces 85a and 85b. The projections 88a and 88b engage with the fixing grooves 42 formed in the lower surfaces of the cutting inserts 20 and 22, respectively, when the cutting inserts 20 and 22 are seated on the cutting insert mounting surface 85a. In the cutting operation using the indexable ball nose end mill 10, the cutting inserts 20 and 22 are firmly fixed to the holder 80.

The sites 84a and 84b are straightforward clearances 86a and 86b formed in a direction perpendicular to the cutting insert mounting surfaces 85a and 85b and arcuate forge clearances 87a and 87b curved arcuately adjacent thereto. It is provided. The straight forging clearance surfaces 86a and 86b adjacent to some of the inner periphery of the cutting insert mounting surfaces 85a and 85b are the side forcing clearance angles δ = δ '= δ "of the cutting inserts 20 and 22 (FIGS. 7A to 7). The same slope as FIG. 7C).

5 is a perspective view of a cutting insert according to the present invention, Figure 6 is a plan view and a position-specific side view of the cutting insert according to the present invention.

5 and 6, the cutting insert of the indexable ball nose end mill 10 for curved surfaces according to the present invention is mainly manufactured by cementing the cemented carbide material through a powder metallurgy process, that is, a mold pressure, sintering, grinding, etc. do. Since the above-described main cutting insert 20 and the sub cutting insert 22 have the same configuration only with a difference in size, only the main cutting insert 20 will be described below for convenience of description.

The cutting insert 20 has an upper surface 30 and a lower surface 40 and a side surface 50 positioned therebetween. In the center of the cutting insert 20, a circular opening 31 is vertically penetrated, and a boss portion 32 for fixing the cutting insert 20 to the holder 80 is provided in the circular opening 31. . The boss portion 32 is located 0 to 0.25 mm lower than the highest land surface of the cutting insert 20. When the cutting insert 20 is fixed to the holder 80, a fixing screw (not shown) is inserted into the circular opening 31. The cutting insert 20 is configured to be rotationally symmetrical by 180 degrees about the center of the circular opening 31. Thus, the cutting insert 20 has an edge 33 provided on the upper surface 30 so as to be symmetrical in the diagonal direction.

On the other hand, the side surface 50 is the side surface paper clearance surface (51-1 to 51-3, 52-1 to 52-3) leading from the upper surface 30 to the lower surface 40 at a forcing clearance angle of 5 to 25 degrees and The edge side surfaces 51-4 and 51-5 located between these side holding spaces 51-1 to 51-3 and 52-1 to 52-3 are provided. At this time, a first edge side surface 51-4 is provided between the second side surface holding surface 51-2 and the third side surface holding surface 52-3, and the first side surface holding surface 51-1 is provided. ) And the first corner side 51-4, the second corner side 51-5 smoothly runs on the radius of curvature. At this time, the side forging clearance surfaces 51-1 to 51-5 and 52-1 to 52-5 connecting the upper surface 30 and the lower surface 40 are circular openings penetrating the center of the cutting insert 20 ( 31 are formed symmetrically with respect to each other.

At the boundary position between the upper surface 30 and the side surfaces 51-1 and 52-1 which are major sections, a main section 34 having an arc shape is formed. The main cutting edge 34 contributes to cutting while primarily contacting the workpiece during cutting, and indicates the path of the sphere when the indexing ball nose end mill 10 rotates the rotation axis CL about the center. Cut. Preferably, the radius of curvature R of the major cutting 34 is 10 to 30 mm (set to 1/2 of the diameter of the ball nose portion of the indexable ball nose end mill 10).

Then, a linear side cut 35 is formed at the boundary position between the upper surface 30 and the side surface retaining surface 51-3. That is, the straight lateral cut 35 extends from the main cut 34 toward the corner portion 33 in parallel to the lower face 40 at the boundary position between the upper face 30 and the side forgable allowance 51-3. Is formed. At this time, the straight side cutting 35 is formed at the highest position on the upper surface (30). The straight side cutting section 35 draws a cylindrical trajectory when the indexable ball nose end mill 10 rotates about the rotational axis CL, and the workpieces such as curved, side, groove, and hole processings can be processed. Perform the cutting function.

A recess cutout 36 is formed between the edge portion 33 and the straight side pickled 35. That is, the recess cutout 36 is formed to be inclined toward the edge portion 33 from the straight side cutout 35. The edge part 33 is located at the lowest part in the upper surface 30 of the cutting insert 20. Accordingly, the main cutout 34 formed in an arc shape is connected to r smaller than the radius of curvature of 1.2 mm, which is smoothly connected, and is connected to the recess cutout 36 at an obtuse angle of 120 to 140 degrees in plan view.

The length L _r of the linear side cutting 35 is 0.2 to 0.8 times the radius of curvature R of the main cutting 34. In addition, the angle (λ _r ) formed by the recess pickle 36 and the straight side pickle 35 at the side is 25 to 40 degrees, and the angle formed by the recess pickle 36 and the straight side pickle 35 in the plane. (λ _t ) is composed of 5 to 9 degrees.

The arcuate forging clearances 87a and 87b (see Fig. 4) of the cutting insert sites 84a and 84b, which are formed transversely to the rotation axis CL of the holder 80, have the main cuts 34 and the lower surface 40. Side posing clearances 51-2, 52- which are adjacent to the lower surface 40 of the side posing clearances 51-1, 51-2, 52-1, 52-2 of the main cutting insert 20 to be joined. It consists of the same angle and the same radius of curvature as 2).

On the other hand, between the main cutout 34 and the chip breaker (not shown) of the upper surface 30, the land surface 37 as the main cutout is formed to have a width of 0.05 to 1.5 mm. At this time, the land surface 37, which is the major section, extends inclined at an angle α _L (see FIG. 7A) of -30 to +10 degrees from the main section 34 to the upper surface 30. Similarly, between the straight side section 35 and the chip breaker of the upper surface 30, the land surface 38, which is a side section, is formed with a width of 0.05 to 1.5 mm, wherein the land surface 38, which is a side section, is a straight side section ( 35, it extends obliquely toward the upper surface 30 at an angle β _L (see FIG. 7B) from −30 to +10 degrees. In addition, a land surface 39 that is a recessed section is formed between the recess cutout 36 and the chip breaker of the upper surface 30. The land surface 39, which is a recessed section, extends inclined at an angle γ _L (see FIG. 7C) from the recessed section 36 toward the upper surface 30 at an angle of -30 to +10 degrees. The land surface 37 which is a major section, the land surface 38 which is a side section, and the land surface 39 which is a recess section continue smoothly.

On the other hand, the cutting insert 20 uses only the upper surface 30 at the time of cutting the ferrous or nonferrous metal. Thus, only the upper surface 30 is provided with a chip breaker of irregularities. At this time, the chip breaker is gently slid down toward the circular opening 31 in the land surface (37, 38, 39) integrally formed along the main cut 34, the straight side cut 35 and the recess cut 36 It has a shape and has a function of smoothing the flow of chips during cutting.

7A to 7C are cross-sectional views taken along the lines "A-A", "B-B", and "C-C" in FIG.

Referring to FIGS. 7A to 7C, FIG. 7A is a view taken along the middle portion of the floor and the valley of the concave-convex shape of the upper surface, and the reference numeral “ℓ” is a major section formed along the arch-shaped main section 34. 37) the width. Preferably, the width (l) of the land surface 37, which is the major cut, is 0.05 to 1.5 mm. Reference numeral "α" indicates a sliding angle that slides down from the land surface 37, which is a major section, toward the circular opening 31. Preferably, the sliding angle α is 7 to 13 degrees.

Reference numerals (θ, θ ') and (δ, δ', δ "denote side flank clearance angles, where (θ, θ ') are side flank clearance surfaces 51-1 located near the main cut 34. 52-1 is an angle formed by an imaginary vertical line lowered from the boss portion 32 to the lower surface 40, and forms an angle of 5 to 20 degrees, and reference numeral δ designates a side foreside surface 51-. 3,52-3 is an angle formed by an imaginary vertical line lowered from the boss portion 32 to the lower surface 40, and forms an angle of 8 to 25 degrees. Reference numerals δ 'and δ " The side forge clearance surfaces 51-2 and 52-2 located near 40 form an angle with an imaginary vertical line lowered from the boss portion 32 to the lower surface 40 to form an angle of 8 to 25 degrees.

The width l 'of the land surface 38, which is the side section shown in Figs. 7B and 7C, and the width l " of the land surface 39, which is the recessed section, are the width (l) of the land surface 37, which is the major section of Fig. 7A. In addition, the side position clearance angles θ 'and δ " shown in Fig. 7B and the side position clearance angles δ shown in Fig. 7C are equal to the side position clearance angles θ, δ' shown in Fig. 7A. The relationship of θ = θ 'and δ' = δ "= δ is satisfied. The sliding angle β shown in FIG. 7B is formed by the virtual plane parallel to the bottom surface 40 and the floor of the chip breaker. The angle is 3 to 15 degrees, preferably 3 to 8. The sliding angle γ shown in Fig. 7C is an angle formed by the imaginary surface parallel to the lower surface 40 and the valley of the chip breaker. It is -20 degree | times, Preferably it is 10-15 degree | times.

8 is a bottom view of the cutting insert according to the invention, and FIG. 9 is a sectional view taken along the line “D-D” of FIG. 8.

8 and 9, the lower surface 40 is firmly fixed when the cutting insert 20 is fixed to the cutting insert mounting surface 85a of the tool holder 80 to support the cutting insert 20. Play a role. To this end, the fixing groove 42 is formed at the central position of the lower surface 40. The fixing groove 42 is formed to a depth of about 1.0 to 1.5 mm across the circular opening 31 along the longitudinal direction of the cutting insert 20, wherein the inner inclined surface 41 of the fixing groove 42 is a lower surface. Meet at an angle of about 5 to 20 degrees with respect to the outer surface of (40). The fixing groove 42 accommodates the protrusions 88a and 88b formed by protruding the cutting insert mounting surfaces 85a and 85b of the holder 80 when the cutting insert 20 is mounted to the holder 80. To be combined.

In the case where the cutting inserts 20 and 20 configured as described above are mounted on the cutting insert mounting surfaces 85a and 85b of the holder 80, the side-possible clearance surfaces 51-1 and 51-2 of the cutting inserts 20 and 22, At least one of the side forcing clearances among the 51-3,52-1,52-2,52-3 is formed by the forage clearance surfaces 86a, 86b, 87a, 87b provided on the cutting insert mounting surfaces 85a, 85b. They come in contact with the same slope.

In the case where the workpiece is cut using the indexable ball nose end mill 10 after mounting the cutting inserts 20 and 22 to the holder 80, the indexable ball nose end mill (see FIG. When 10) rotates, the major cutting insert 20 of the main cutting insert 20 and the main cutting insert 34 of the sub cutting insert 22 process the workpiece while drawing a spherical trajectory, and the main cutting insert 20 The straight side cut 35 of and the straight side cut 35 of the subcutting insert 22 process the workpiece while drawing the trajectory of the cylindrical shape. And the edge part 33 (refer FIG. 5) of the main cutting insert 20 is put on the rotating shaft CL, and processing is performed. In Fig. 2, the hatched portion S, which is partially enlarged, shows a portion which is not processed by the secondary cutting insert 22 during cutting, and the reference numeral “P” denotes the main cutting insert 20 after 180 degrees of rotation. It is a virtual representation of the state where is located.

As described above, the indexable ball nose end mill 10 according to the present invention, unlike the existing indexable ball nose end mill, the arch-shaped main section 34, straight side section 35, recessed ( 36) and a chip breaker provided in an uneven shape on the upper surface 30, it is possible to induce a reduction in cutting resistance and natural chip discharge of the cut portion in accordance with the change in the depth of cut, thereby resulting in heat generated during cutting The transfer to this tool can be minimized. In addition, the frictional resistance is minimized to significantly improve the wear resistance of the cutting inserts 20 and 22 and to improve the edge strength of the main cutting edge 34.

In addition, the cutting inserts 20 and 22 of the indexable ball nose end mill 10 according to the present invention are used in the recess pickling 36 in the processing of low carbon steel, low carbon alloy steel, etc. having tough properties as well as general steel and alloy steel. Since sufficient chip discharge space can be secured, excellent tool life is achieved due to small cutting resistance, efficient chip evacuation and excellent pickling strength. In addition, the arched main cuts (34) and straight side cuts (35) provide a smooth curved surface and a right angled side working surface suitable for high speed and high feed, reducing heat generation and maintaining pickling strength of the main ship. It is possible to obtain an effect of significantly reducing breakage and chipping.

In addition, the indexable ball nose end mill 10 according to the present invention is a solid ball end mill, which is expensive and cannot be processed with high cutting power, and is only available for low productivity solid ball end mill or finishing and medium cutting. Compared to the mill, finishing, medium cutting and roughing are possible, and the productivity can be greatly improved because of the advantages of excellent quality precision of the machining surface and low tool cost.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention described in the claims below. It will be appreciated.

Claims (7)

A long body having a semi-circular end portion formed at a front end portion thereof, and a plurality of sites each having a cutting insert mounting surface are formed at adjacent positions of the semi-circular end portion, and a holder having a through hole formed at a central portion of the cutting insert mounting surface; It is detachably mounted to the cutting insert mounting surface, and has a top surface, a bottom surface provided with a chip breaker, and a side surface located between the top surface and the bottom surface, and a circular opening is vertically in the center. It is formed through, the boss portion is provided in the circular opening, and provided with the corner portion provided on the upper surface to be symmetrical in the diagonal direction, the side surface at a forge clearance angle of 5 to 25 degrees from the upper surface to the lower surface A plurality of side forcing clearances and a corner side surface positioned between the plurality of side forcing clearances, the second side forcing clearance being formed symmetrically with respect to the circular opening. A first corner side between the face and the third side forging clearance, Between the first edge side, the second edge side smoothly runs to the radius of curvature r, and is an arch-shaped major section formed at the boundary position between the upper side and the first side forging clearance surface, wherein the upper surface and the third side forging clearance A plurality of rectilinear side sections formed by extending from the major section to the corner section parallel to the lower surface at a boundary position of the surface, and a plurality of recess sections formed by the section section extending obliquely between the straight section section and the corner section Cutting inserts; And Fixing means for detachably mounting and fixing the cutting insert on the mounting surface of the holder, the site of the holder being formed at a symmetrical position with respect to the central axis of the ball nose end mill at the semicircular end; And a straight forge clearance surface formed in a direction perpendicular to the cutting insert attachment surface at an inner periphery of the cutting insert mounting surface, and an arcuate forge clearance surface curved arcuately adjacent thereto, wherein the straight forge clearance surface is provided. At the same inclination as the side insert clearance angle of the cutting insert, whereby when the cutting insert is mounted on the cutting insert mounting surface of the holder, at least one side forging clearance of the side insert clearance surfaces of the cutting insert Forge provided with face on the cutting insert mounting face It is in contact with the same inclination as the clearance surface, the projection is formed protruding in the longitudinal direction of the rotation axis of the holder in the adjacent position of the through hole in the cutting insert mounting surface, the center position of the lower surface corresponding to the projection A fixing groove having a size and shape is formed, wherein the fixing groove is formed to a predetermined depth across the circular opening along the longitudinal direction of the cutting insert, and when the cutting insert is mounted to the holder, The protrusion of the holder is fitted into the fixing groove of the cutting insert, and in this state the cutting insert is inserted into the holder by the fixing means which is sequentially inserted into the circular opening of the cutting insert and the through hole of the holder. Indexable ball nose, characterized in that firmly coupled to the mounting surface End mill. delete delete The main section of claim 1, wherein the main section has a width of 0.05 to 1.5 mm and extends inclined at an angle of -30 to +10 degrees from the main section to the upper surface. Land surface is formed, the land surface is a side section extending inclined at an angle of -30 to +10 degrees toward the upper surface in the straight side section while having a width of 0.05 ~ 1.5mm between the straight side section and the chip breaker The land surface is formed between the recess pickled and the chip breaker and has a width of 0.05 to 1.5 mm and extends inclined at an angle of -30 to +10 degrees toward the upper surface at the recess pickled. Indexable ball nose end mill, characterized in that formed. 5. The land according to claim 4, wherein the straight side cut is placed at the highest position on the upper surface, and the boss portion of the cutting insert is a land surface that is the major cut of the cutting insert, a land surface that is the side cut, and a land that is the recessed section. It is located lower than the highest land surface in the plane, and the edge portion of the cutting insert is located at the lowest portion of the upper surface of the cutting insert, whereby the edge portion is the main cutting edge with a radius of curvature smaller than the radius of curvature of the cutting edge. An indexable ball nose end mill, which is smoothly connected and is connected to the recess pickled at an angle of inclination of 120 to 140 degrees when the cutting insert is viewed from above the upper surface. The radius of curvature of the main cutting edge is 10 to 30 mm, and the length of the straight side cutting edge is 0.2 to 0.8 times the radius of curvature of the main cutting edge, and the cutting insert in the lateral direction of the cutting insert. When viewed, the angle between the recess pickled and the straight side pickled is 25 to 40 degrees, and when the cutting insert is viewed from above the upper surface, the angle between the recess pickled and the straight side pickled is 5 to 9 degrees. Indexable ball nose end mill, characterized in that made. According to claim 1, wherein the chipbreaker has a concave-convex shape consisting of the floor and the valley, the sliding angle of sliding down from the major land surface to the circular opening when measured along the middle portion of the floor and the valley is 7 ~ 13 ° and the side lateral clearance angle formed by the first side forage clearance surface located near the major cutting line with an imaginary vertical line lowered from the boss portion to the lower surface is an angle of 5 to 20 degrees, and is close to the straight lateral cut. The sliding angle between the virtual plane parallel to the lower surface and the floor of the chipbreaker is 3 to 15 degrees when measured from the main cutting edge to the upper surface at the position, and is measured from the straight side cut to the upper surface. The sliding angle between the virtual plane parallel to the lower surface and the valley of the chip breaker is 5 to 20 degrees. The angle formed by the third side forging clearance surface with the imaginary vertical line lowered from the boss portion to the bottom surface is at an angle of 8 to 25 degrees, and the second side forging clearance surface located near the bottom surface is disposed at the boss portion. Indexable ball nose end mill, characterized in that the angle formed with the imaginary vertical line lowered to the lower surface is 8 to 25.