JP2010069578A - Edge-exchangeable rotary tool for use in high-feed machining - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an edge-exchangeable rotary tool having an insert suitable for high-feed machining, which can reduce cutting resistance while keeping high defect-resistance of a main cutting blade of a cutting insert. <P>SOLUTION: In the edge-exchangeable rotary tool for high-feed machining employing a detachable insert, a negative horning, a flat land and a breaker groove are provided from a main cutting blade. In the edge-exchangeable rotary tool for high-feed machining, a negative horning width and a flat land width gradually increase from the lowest point to a joint and satisfy the relation of 0.03≤H1≤0.1, 0.15≤H1/H2≤0.5, 0.03≤F1≤0.1 and 0.15≤F1/F2≤0.5 where the negative horning width (mm) refers to H1 and the flat land width (mm) refers to F1 at the lowest point, and the negative horning width (mm) refers to H2 and the flat land width (mm) refers to F2 at the joint portion. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cutting edge exchangeable cutting tool equipped with an insert having a structure suitable for high feed processing with a long tool protrusion.

  Patent Documents 1 to 3 disclose techniques related to the cutting edge-exchangeable cutting tool. Patent document 1 is disclosing the technique which improves the fracture resistance by changing the honing width and angle of a linear main cutting edge. Patent Document 2 discloses a blade-tip-exchange-type cutting tool suitable for high-feed cutting. Patent Document 3 discloses a cutting edge exchangeable cutting tool provided with a flat land.

JP 2002-46002 A Japanese Patent No. 3317490 JP 2008-207273 A

  The present invention makes it possible to reduce the cutting resistance while maintaining the fracture resistance of the main cutting edge of the cutting insert, and in particular, an insert suitable for high-feed machining when the tool protrusion amount exceeds 200 mm. It is to provide an attached blade-tip-replaceable rotary tool.

  The present invention relates to a high-feed-blade replaceable rotary tool using a detachable insert, wherein the insert has a ridge line portion between a rake face and a flank face as a cutting edge, and the cutting edge includes a corner edge and the corner edge. The main cutting edge and the outer peripheral edge are sandwiched, and the angle formed by the line segment connecting the lowest point of the rotary tool on the main cutting edge and the connecting portion between the main cutting edge and the corner edge with the perpendicular of the tool rotation axis ( Θ) is 5 ≦ θ ≦ 30, and the main cutting edge has a convex shape in a direction perpendicular to the tool rotation axis with respect to the line segment, and the rake face has the main cutting edge on the main cutting edge. From the ridgeline portion of the main cutting edge in a direction substantially perpendicular to the main knives, there is a negative honing, a flat land, and a breaker groove, and the width (mm) of the negative honing at the lowest point is H1, The width (mm) is F1, the negative honing width (mm) at the joint is H2, When the width (mm) of the rat land is F2, the negative honing width and the flat land width gradually increase from the lowest point toward the connecting portion, and 0.03 ≦ H1 ≦ 0.1,. 15 ≦ H1 / H2 ≦ 0.5, 0.03 ≦ F1 ≦ 0.1, 0.15 ≦ F1 / F2 ≦ 0.5. . By adopting the above configuration, it is possible to reduce the cutting resistance while maintaining the fracture resistance of the main cutting edge of the cutting insert, and in particular, high feed machining when the tool protrusion exceeds 200 mm. It is possible to provide a blade-exchangeable rotary tool equipped with a suitable insert.

  The high-feed cutting edge replaceable rotary tool of the present invention has a plurality of U's formed vertically at least in the vicinity of the main cutting edge on the upper surface of the insert in a direction substantially orthogonal to the tangent to the main cutting edge It is preferable to have a groove and a rake face between the U-shaped grooves. Further, the width (mm) of the rake face between the U-shaped grooves in the connecting portion is RW, the horizontal width (mm) of the U-shaped groove is UW, the longitudinal length (mm) is UH, and the main cutting edge When the length (mm) from the ridge line portion to the U-shaped groove end is UL, 0.3 ≦ RW ≦ 0.35, 1.5 ≦ RW / UW ≦ 2.0, UH ≧ 1, 0. It is preferable that 45 ≦ UL ≦ 0.8.

  The present invention makes it possible to reduce the cutting resistance while maintaining the fracture resistance of the main cutting edge of the insert, and in particular, an insert suitable for high-feed machining when the tool protrusion amount exceeds 200 mm is mounted. We were able to provide a blade-changeable rotary tool.

  An outline of the high-feed cutting edge replaceable rotary tool of the present invention will be described with reference to the drawings. First, FIG. 1 shows a view for explaining how the rotary tool main body 1 and the insert 2 of the present invention are mounted. As shown in FIG. 1, the insert 2 is attached to the rotary tool main body 1 by a clamp screw 4 through an attachment hole 3 provided in the center portion. FIG. 2 shows a view when the insert 2 is mounted on the rotary tool body 1. In FIG. 2, the cutting blade of the present invention has a main cutting edge 6 and an outer peripheral edge 7 so as to sandwich the corner blade 5. When the insert is mounted on the rotary tool body, the main cutting edge has the lowest point 8. The outer peripheral blade is located on the outer side with respect to the tool rotation axis. On the other hand, a surface symmetrical to the outer peripheral blade with respect to the mounting hole is a restraining surface when the rotating tool body is mounted. The insert is mounted in a state of being inclined at a predetermined angle with respect to the tool rotation axis direction, and is in a state of having a back taper. Since the cutting edge replaceable cutting tool of the present invention sets the cutting depth ap value within the range of the main cutting edge, even if a vertical vertical wall is machined, the outer peripheral blade is not involved in cutting, Therefore, no cutting resistance is generated. FIG. 3 is an enlarged view of the insert 2 shown in FIG. The insert 2 shown in FIG. 3 is a first embodiment of the present invention. As shown in FIG. 3, the lowermost point 8 of the main cutting edge of the insert mounted on the cutting edge-exchangeable cutting tool of the present invention is set as the connecting portion 9 between the main cutting edge and the corner blade, and the lowermost point 8 is connected. 5 ≦ θ ≦ 30, where θ is an angle (degree) formed by a line connecting the part 9 and a straight line perpendicular to the tool rotation axis. Further, the main cutting edge has a convex shape in the direction perpendicular to the tool rotation axis with respect to the line segment. The shape of the main cutting edge may be formed by a curved shape, an arc shape, or a combination of these and a straight line. As for the size of the insert of the present invention, the radius R of the arc connecting the three points of the inscribed circle having a diameter of 6 mm to 16 mm, the lowest point 8, the intersection point 10, and the connecting portion 9 is preferably 6 mm to 20 mm. Here, the intersection point 10 is an intersection point of the perpendicular bisector of the line segment and the main cutting edge, and the intersection point 10 is a tool with respect to a line segment connecting the lowest point 8 and the connecting portion 9. It is outside in the direction perpendicular to the rotation axis. FIG. 4 shows a perspective view of the insert of the present invention. The insert has a substantially rectangular shape, and includes a bottom surface 11 in contact with the seating surface of the tool body, a rake surface 12 facing the bottom surface, and a flank surface 13 formed between the bottom surface and the rake surface. And the cutting edge is formed in the ridgeline part which a rake surface and a flank face make, and the cutting edge is similarly formed in the symmetrical position with respect to the attachment hole provided in the insert center part.

  FIG. 5 is a cross-sectional view taken along line AA in the vicinity of the lowest point 8 in the main cutting edge of the insert shown in FIG. 4, and shows that the negative honing width is H1 and the flat land width is F1. FIG. 6 is a cross-sectional view taken along line BB in the vicinity of the connecting portion 9 between the main cutting edge and the corner edge shown in FIG. 4, and shows that the negative honing width is H2 and the flat land width is F2. For high-feed cutting tools with replaceable cutting edges, the main cutting edge has an improved chipping resistance on the rake face side, especially for the purpose of improving the chipping resistance on the outer peripheral side near the corner cutting edge. Negative honing and flat lands are provided to enhance the cutting edge strength. However, with negative honing and flat lands, the chipping resistance is improved if the width is wide, but the cutting resistance increases and the load on machine tools used for cutting, such as machining centers, increases. Efficient high-feed machining is not possible. In addition, when the protruding amount is longer than 200 mm, or when the protruding amount is more than 4 times the tool diameter, the chatter vibration is increased and the cutting edge is likely to be broken. Degradation of the processed surface roughness of the material also occurs. On the other hand, if the negative honing and flat land are small in width, the cutting resistance becomes small, but the strength of the cutting edge is insufficiently strengthened and the cutting edge tends to be lost. Accordingly, the negative honing width and the flat land width are set when the work material has a low rigidity and the protrusion amount that tends to generate chatter vibration during cutting is longer than 200 mm, or with respect to the tool diameter. The negative honing width and the flat land width are set small for a tool having a protrusion amount of 4 times or more, and conversely, when the cutting edge is likely to be broken due to strong interrupted cutting. The angle α (degree) of negative honing is preferably set to 5 ≦ α ≦ 30, and the α value may be changed between the lowest point 8 and the connecting portion 9. Furthermore, cutting resistance can be reduced by providing a breaker groove on the rake face. The rake angle β (degree) of the breaker groove is preferably β ≦ 20, more preferably 10 ≦ β ≦ 20.

  FIG. 7 is a schematic diagram for explaining the chip thickness at the main cutting edge portion of the cutting tool of the present invention. In the present invention, the chip thickness generated by the arcuate main cutting edge that is convex downward in the tool rotation axis direction is not constant over the entire length direction of the main cutting edge. For example, when the radius R of the main cutting edge is 15 mm, the chip thickness when machining is performed with a cutting depth ap value of 1.5 mm and a cutting amount fz value of 1.5 mm as cutting conditions for high-feed machining. T2 is about 0.6 mm, and the chip thickness T1 near the lowest point 8 is about 0.06 mm. That is, the T1 value is reduced to about 1/10 of the T2 value. Thus, in the present invention, an appropriate negative honing width and flat land width are provided depending on the portion of the cutting blade in the vicinity of the corner blade where the thickness of the chip becomes thick and in the vicinity of the lowest point 8 where the thickness of the chip becomes the thinnest. Thus, it is possible to realize a cutting edge-exchangeable cutting tool with reduced cutting resistance and at the same time improved fracture resistance. As described above, in order to reduce the cutting resistance, the H1 value and the F1 value of the lowest point 8 at which the chip thickness is the thinnest are reduced. At this time, even if the H1 value and the F1 value are reduced, the chip thickness is thin, so that the fracture resistance is not significantly impaired. On the other hand, fracture resistance must be improved by increasing the negative honing width and the flat land width at the outer peripheral portion in the vicinity of the corner blade where the chip thickness is maximum. Here, on the outer peripheral side in the vicinity of the corner edge of the main cutting edge of the insert, the fracture resistance is preferentially improved. In the present invention, the negative honing width and flat land width minimize the H1 value and F1 value of the lowest point 8 of the main cutting edge, and maximize the H2 value and F2 value of the joint portion 9 between the main cutting edge and the corner blade. Further, by gradually increasing from the lowest point 8 of the rotary tool toward the connecting portion 9, both the fracture resistance of the main cutting edge and the reduction in resistance can be achieved. On the other hand, since the negative honing width of the insert in the conventional high-feed machining tool is a constant width of approximately 0.2 mm and the flat land width is also constant, the vicinity of the lowest point of the tool is in the negative honing area. In other words, cutting was performed, and the sharpness was poor and the cutting resistance was high.

  In the insert of the present invention, first, the H1 value (mm) of the main cutting edge must be 0.03 ≦ H1 ≦ 0.1. The reason for this is that when the fz value at the time of machining and the chip thickness near the lowest point 8 are determined, and the H1 value is set based on that value, the fracture resistance is significantly reduced if the H1 value is less than 0.03 mm. Because. This is because the cutting edge strength is insufficient, so that the chipping occurs due to the impact when the lowermost point of the insert comes into contact with the work material during cutting rather than the influence of the chip thickness. On the other hand, if the H1 value exceeds 0.1 mm, the cutting resistance increases, which is inconvenient. Next, after setting the H1 value, the H2 value (mm) needs to be set such that the ratio between the H1 value and the H2 value, and the H1 / H2 value is 0.15 to 0.5. By doing so, the balance between the fracture resistance of the main cutting edge and the cutting resistance is the best, and the cutting resistance can be reduced by 10% or more without impairing the fracture resistance. However, the H2 value is preferably set within a range of 0.1 to 0.5 mm in consideration of chipping resistance and cutting resistance increase. By doing this, even if the H1 value is about 30% wider than the chip thickness T1 near the lowest point, the cutting range is less in the negative honing width, so the cutting resistance is reduced by 10% or more. Is possible.

  Next, in the insert of the present invention, the F1 value (mm) of the main cutting edge needs to be 0.03 ≦ F1 ≦ 0.1. The reason is that if the F1 value is less than 0.03 mm, it is not effective in strengthening the cutting edge strength and the fracture resistance is lowered. If the strength of the cutting edge is insufficient, a chipping occurs due to an impact when the lowermost point of the insert comes into contact with the work material during cutting. On the other hand, if the F1 value is larger than 0.1 mm, there is a disadvantage that the cutting resistance increases. Next, after setting the F1 value, the F2 value (mm) needs to be set so that the F1 / F2 value is 0.15 to 0.5. This is effective in delaying the progress of wear on the rake face of the main cutting edge. A wider F2 value has an effect of delaying wear on the rake face, particularly on the outer peripheral side in the vicinity of the corner blade, and the fracture resistance is improved. However, it is preferable to set the F2 value within a range of 0.1 to 0.5 mm in consideration of chipping resistance and cutting resistance increase. When the F2 value is excessively wide, the chip discharge performance is impaired and the cutting resistance increases. This is because the flow of guiding the chips into the breaker groove is hindered.

In the cutting tool of the present invention, chips generated during cutting in high-feed machining are discharged in a direction substantially orthogonal to the main cutting edge. Therefore, as shown in FIG. 3, at least on the outer peripheral side of the rake face of the insert, in the vicinity of the corner blade, a plurality of U-shapes that are vertically formed in a direction substantially perpendicular to the tangent to the substantially arc-shaped main cutting blade It is preferable to provide the groove 16. A rake face 18 is provided between the U-shaped grooves. Chips pass along the rake face 18, the contact area between the rake face and the chips is reduced, the frictional force is reduced, and the temperature rise due to friction is also alleviated. This is preferable because the resistance can be lowered and the progress of wear can be delayed. In particular, on the outer peripheral side of the main cutting edge near the corner blade, both negative honing width and flat land width are set widely, and cutting resistance tends to increase. Is preferred. Here, the cross-sectional shape of the rake face portion provided between the adjacent U-shaped grooves forms a gentle hill shape, and this hill shape portion is a surface in contact with the chips. Since the load applied to the main cutting edge increases as it approaches the joint portion on the outer peripheral side of the tool, in the previous improvement, the H2 value was set larger than the H1 value to improve the cutting edge strength. Here, the vicinity of the connecting portion is a range from the intersection 10 between the main cutting edge and the perpendicular bisector of the line segment to the connecting portion 9. In improving the cutting edge strength, measures for reducing the cutting resistance were not taken, but it is preferable because the measures for reducing the cutting force can be taken here by arranging the U-shaped grooves. A U-shaped groove can be provided on the rake face on the outer peripheral side of the tool to reduce cutting resistance. This is because the contact area between the chips and the rake face can be reduced. In particular, an insert suitable for high-feed machining when the tool protrusion exceeds 200 mm is preferably reduced in cutting resistance.
Moreover, FIG. 8 shows sectional drawing of CC line of the honing part in the insert shown in FIG. As shown in FIG. 8, when the width (mm) of the U-shaped groove in the vicinity of the joint is UW and the width (mm) of the rake face between the U-shaped grooves is RW, 0.3 ≦ RW ≦ It is preferable that 0.35 and 1.5 ≦ RW / UW ≦ 2.0. By setting the UW value and RW value on the rake face on the tool outer peripheral side in the vicinity of the joint to the above ranges, the cutting resistance is reduced in a range that does not adversely affect the progress of rake face wear on the tool outer peripheral side. be able to. If the RW value is less than 0.3 or the RW / UW value is less than 1.5, the contact area with the chips is reduced and cutting resistance is reduced, but on the other hand, the wear of the rake face becomes remarkable. This will deteriorate the chipping resistance of the cutting blade. On the other hand, when the RW value is longer than 0.35 or the RW / UW value is larger than 2.0, the progress of wear on the rake face is suppressed, and the chipping resistance of the cutting edge can be maintained. However, since the reduction of the contact area with the chips is insufficient, the cutting resistance cannot be reduced.
The UH value of the U-shaped groove is preferably UH ≧ 1. The reason is that if the UH value is less than 1, the U-shaped groove is too short and the chip contact area is not sufficiently reduced, so that it is not effective in reducing the cutting resistance. Here, since the upper limit value of the UH value is determined by the form of the rake face, it is not particularly defined.
The UL value is preferably 0.45 ≦ UL ≦ 0.8. This is because the cutting resistance can be reduced within a range in which the U-shaped groove does not adversely affect the progress of wear of the rake face in consideration of the region where the chips come into contact with the rake face. If the UL value is less than 0.45, the starting position of the U-shaped groove is too close to the cutting edge, so that the wear of the rake face is accelerated and the fracture resistance is deteriorated. On the other hand, when UL exceeds 0.8, it is not effective for reducing the cutting resistance.
In addition, when the U-groove pitch (mm) is UP, the UP value is changed so as to gradually increase from the lowest point of the rotary tool toward the joint, thereby reducing resistance and fracture resistance during cutting. And the balance is suitable. In addition, if the UP value changes so as to gradually increase from the lowest point of the rotary tool toward the connecting portion, the number of U-shaped grooves on the outer periphery side of the tool will be reduced compared to the lowest point of the tool, It is also effective in delaying the progress of wear on the side of the rake face, and it is possible to balance the reduction in cutting resistance and the fracture resistance of the cutting edge. On the contrary, if the UP value in the vicinity of the joint portion is set to be relatively narrow, the existence density of the U-shaped grooves increases and the area of the rake face decreases. Then, although the contact area with the chip becomes smaller and the cutting resistance can be reduced, the wear of the rake face proceeds and the chipping resistance of the cutting edge is impaired. On the other hand, setting a small UP value in the vicinity of the lowest point of the rotary tool on the rake face is effective for increasing the existence density of U-shaped grooves and further reducing the cutting resistance. In the vicinity of the lowest point, the chip thickness is also thin and the progress of wear on the rake face is slow, so it is more effective to set the UP value small.
Further, when the depth of the U-shaped groove is d, if the d value is deeper than 1 mm, the strength of the insert is insufficient, and particularly in high-feed machining, a large load is applied to the cutting blade, and it is easy to break. The value is preferably set to 1 mm or less. In order to maintain the cutting edge strength, it is preferable that the d value gradually decreases from the lowest point toward the joint. Further, as a second embodiment of the present invention, FIG. 9 shows a configuration in which three main cutting edges each having a substantially triangular shape are provided. Also in these cases, effects similar to those of the present invention can be obtained.

In order to confirm the effects of cutting resistance reduction and fracture resistance according to the present invention, evaluation was performed under the following cutting test conditions. As the insert of Example 1 of the present invention, an insert made of WC-based cemented carbide prepared by using powder metallurgy technology was used. As for the size of the insert, the diameter of the inscribed circle was 14 mm, the thickness was 5.56 mm, and the radius R value of the main cutting edge was 15 mm. The application of negative honing and the U-shaped groove in the insert of Example 1 of the present invention were performed at the time of setting the shape of the press mold, and a molded body of the insert was created with a mold press machine. For other Invention Examples 2-17, Comparative Examples 18-22 and Conventional Example 23, the shape of the negative honing width, flat land width and U-shaped groove was changed by changing the shape setting of the molding die. Other than that was created in the same manner as in Example 1 of the present invention. At this time, the H2 values of Invention Examples 1 to 17 and Comparative Examples 19 to 22 were all set to 0.2 mm, and the F2 values were all set to the same value of 0.2 mm. In all cases, the negative honing angle α (degree) was 20 degrees, the rake angle β (degree) of the breaker groove was 12 degrees, and the d value was 1 mm or less. However, the insert of Conventional Example 23 used a negative honing width of 0.2 mm and a constant width over the entire main cutting edge. This is because it is considered that the blade edge strength is sufficiently secured with the above values.
The cutting resistance measurement was evaluated with a single blade in which one insert according to Invention Example 1 was mounted on a cutting tool body having a tool diameter of 63 mm. The evaluation of the cutting resistance is effective when cutting is performed for 10 minutes using an S50C material having a flat work surface as the work material, and the cutting resistance value is reduced by 10% or more compared to the conventional example 23. It was judged.
Next, as a work material, an S50C material having a large number of holes with a diameter of 6 mm shown in FIG. 10 was used, and high-feed surface cutting by strong interrupted cutting was performed for 60 minutes to evaluate fracture resistance. . In this fracture resistance evaluation test, five inserts were used, and a 60-minute cut was performed five times with a single blade mounted on the cutting tool body for evaluation. In the evaluation, the presence / absence of a cutting edge defect was evaluated after cutting for 60 minutes. The inserts of Invention Examples 2 to 17, Comparative Examples 18 to 22, and Conventional Example 23 were also evaluated in the same manner as Invention Example 1. The results were indicated by a mark “◯” for those that could be processed without loss of all 5 pieces after cutting for 60 minutes, and a mark “×” for cases where even 1 out of 5 pieces was broken. Table 1 shows the H1 value, H1 / H2 value, F1 value, F1 / F2 value, U-groove condition of the rake face, and evaluation results of Invention Examples 1 to 17, Comparative Examples 18 to 22, and Conventional Example 23.
(Test conditions)
Processing method: Planing, dry cutting Cutting speed Vc: 120 m / min Rotational speed n: 606 min ⁻¹
Feed rate per tooth fz: 1.5 mm / tooth Axial cutting depth ap: 1.5 mm
Radial cutting depth ae: 40 mm
Tool overhang length: 250 mm

From the evaluation results shown in Table 1, first, in the test of cutting resistance measurement, when high feed processing with fz value of 1.5 mm / blade was performed using the insert of Conventional Example 23, the negative honing width was kept constant at 0.2 mm. The cutting resistance value at the time of performing the cutting for 10 minutes of the conventional example 23 was 3777N. Based on this value, Invention Examples 1 to 17 and Comparative Examples 18 to 22 were evaluated for the effectiveness of reducing the cutting resistance by 10% or more. As a result, Examples 1 to 17 of the present invention and Comparative Examples 18 to 20 achieved a target reduction in cutting resistance of 10% or more. Inventive examples 1 to 17 were able to be processed without chatter vibration despite the long tool protrusion length of 250 mm. By reducing the cutting resistance, the load on the machine tool was reduced, and it became possible to further increase the cutting feed amount. In particular, the H1 value is preferably less than the chip thickness near the tool lowest point.
Further, when compared with Examples 1 to 17 of the present invention, Examples 1, 2, 4 to 17 of the present invention provided a plurality of U-shaped grooves on the rake face, and thus achieved a cutting resistance reduction of 16.6% or more. . However, in Example 3 of the present invention, the U-shaped groove was not provided, so the cutting resistance reduction rate was only 14%. Providing the U-shaped groove was effective for cutting resistance reduction. The RW values were compared using the four types of Invention Examples 1, 4 to 6. In Invention Example 4, since the RW value was 0.25, the cutting resistance reduction rate was 20.6%, which was the best, but in the rake face observation, the progress of wear was the most advanced among the four types. In Invention Example 6, since the RW value was 0.4, the progress of wear was small, but the cutting resistance reduction rate remained at 17.9%. In Invention Examples 1 and 5, since the RW value was 0.3 to 0.35, a high cutting resistance reduction rate was obtained while the progress of wear was suppressed, and the balance between the two was good. The RW / UW values were compared using the inventive examples 1 and 7 to 9. In Example 7 of the present invention, the RW / UW value was 1.0, and the cutting resistance reduction rate was 20.3%, but the wear progress of the rake face was observed. In Invention Example 9, since the RW / UW value was 2.5, the progress of wear was small, but the cutting resistance reduction rate was only 16.6%. In Invention Examples 1 and 8, since the RW / UW value was 1.5 to 2, a high cutting resistance reduction rate was obtained while the progress of wear was suppressed, and the balance between them was good. Using four types of Invention Examples 1, 10 to 12, the UH values were compared. Invention Example 10 had a UH value of 0.5, so the cutting resistance reduction rate remained at 18.3%, but Invention Examples 1, 11, and 12 had UH values of 1.0 or more, so the cutting resistance reduction rate. Was 19.1% or more and was excellent. The UL values were compared using the four types of Invention Examples 1 and 13 to 15. All four types showed the same cutting force reduction rate, but a larger rake face wear progression was observed from Example 13 of the present invention to Examples 1, 14, and 15 of the present invention in ascending order of the UL value. Using the three types of Invention Examples 1, 16, and 17, the H1 value and the H1 / H2 value were the same, and the cutting resistance when the F1 value and the F1 / F2 value were changed was compared. The cutting force increased as the flat land width increased. In particular, the difference from Examples 1 and 16 of the present invention was 25N. Further, when the cutting resistance when the H1 value and the H1 / H2 value were changed using the present invention examples 2 and 16 under the same conditions of the F1 value and the F1 / F2 value, the difference between them was 30N. there were. Therefore, it is considered that the negative honing width has a greater influence on the reduction of the cutting resistance.
On the other hand, Comparative Examples 21 and 22 have large H1 / H2 values of 0.6 and 0.75 and F1 / F2 values of 0.6 and 0.75, respectively, and have a negative honing width in the vicinity of the lowest point of the tool. Since the cutting range was long, the targeted cutting resistance could not be reduced by 10%. Further, in Comparative Examples 21 and 22, chatter vibration occurred during cutting. In particular, when the tool protrusion length was as long as 250 mm, chatter vibrations were prominent, and a defect was induced in the main cutting edge. Furthermore, since the spindle of the machine is damaged, the machine tool of the BT50 spindle having a spindle output of 15 kW used in the test cannot perform high-efficiency high-feed machining.
Next, in the evaluation of chipping resistance of the main cutting edge, the presence or absence of each chipping was confirmed until the cutting time was processed up to 60 minutes. The test results are also shown in Table 1. From Table 1, Examples 1 to 17 of the present invention and Comparative Examples 21 and 22 were indicated by ◯ because they could be processed without loss of all 5 pieces after cutting for 60 minutes. However, in Comparative Example 18, all 5 out of 5 pieces could not be processed for 60 minutes, and breakage occurred. The cutting time of each insert was 37 minutes, 40 minutes, 50 minutes, 43 minutes, and 49 minutes. Similarly, in Comparative Example 19, 4 out of 5 pieces, and in Comparative Example 20, 2 out of 5 pieces could not be processed for 60 minutes, and defects occurred. Those in which a defect occurred even in one of the five was indicated by a cross. Since the cutting edge was observed after the test and the location where the defect occurred was near the lowest point of the main cutting edge, the cause of the defect was both the negative honing width and the flat land width at the lowest point. It was thought that it was because the edge strength was insufficient due to the small size. Therefore, in order to maintain the fracture resistance, the H1 value and the F1 value need to be 0.03 mm or more. In particular, since the chip thickness near the lowest point is about 0.06 mm, the chipping resistance can be secured if the H1 value is about half or more of the chip thickness. From the above test results, Examples 1 to 17 of the present invention showed good results in the comprehensive evaluation of the two items of cutting resistance and fracture resistance, and the cutting resistance could be reduced without impairing fracture resistance.

FIG. 1 shows a perspective view of a high feed cutting edge exchangeable rotary tool of the present invention. FIG. 2 shows a view of the high feed cutting edge-replaceable rotary tool of the present invention. FIG. 3 shows an enlarged view of the insert portion of FIG. FIG. 4 shows a first embodiment of the insert according to the present invention. FIG. 5 is a sectional view taken along line AA shown in FIG. 6 shows a cross-sectional view taken along line BB shown in FIG. FIG. 7 shows an enlarged view of a main cutting edge portion in the cutting tool of the present invention. FIG. 8 is a cross-sectional view taken along line CC shown in FIG. FIG. 9 shows a second embodiment of the insert in the present invention. FIG. 10 shows a work material in which many holes are formed.

Explanation of symbols

1: Rotating tool body 2: Insert 3: Insert mounting hole 4: Clamp screw 5: Corner blade 6: Main cutting blade 7: Outer peripheral blade 8: Bottom point of main cutting blade 9: Connection between main cutting blade and corner blade Part 10: Intersection of the perpendicular bisector of the line segment connecting the lowest point 8 and the connecting part 9 and the main cutting edge 11: Insert bottom 12: Rake face 13: Flank 14: Main at the cutting depth ap Point on cutting edge 15: Negative honing 16: U-shaped groove 17: Flat land 18: Rake face between U-shaped grooves H1: Negative honing width H2: Negative honing width F1: Flat land width F2: Flat land width UP : U-shaped groove pitch UW: U-shaped groove width UH: Vertical length of U-shaped groove UL: Length from the ridge line portion of the main cutting edge to the U-shaped groove end RW: Rake surface between U-shaped grooves Width R: Radius of the main cutting edge T1: Chip thickness T2: Chip thickness

Claims (3)

In a high-feed-blade replaceable rotary tool using a detachable insert, the insert has a cutting edge at the ridge line between the rake face and the flank face, and the cutting edge is a main cutting part sandwiching the corner blade and the corner blade. An angle (degree) formed by a line segment connecting the lowest point of the rotary tool in the main cutting edge and the connecting portion between the main cutting edge and the corner blade with the perpendicular of the tool rotation axis 5 ≦ θ ≦ 30, the main cutting edge has a convex shape in a direction perpendicular to the tool rotation axis with respect to the line segment, and the rake face is substantially perpendicular to the main cutting edge. Inwardly in the direction of the main cutting edge from the ridge line of the main cutting edge has a negative honing, flat land, breaker groove, the negative honing width (mm) at the lowest point is H1, the flat land width (mm) F1, and the width (mm) of the negative honing at the joint is H2, the flat land When the width (mm) of F2 is F2, the negative honing width and the flat land width gradually increase from the lowest point toward the connecting portion, and 0.03 ≦ H1 ≦ 0.1, 0.15 ≦ H1 / H2 ≦ 0.5, 0.03 ≦ F1 ≦ 0.1, 0.15 ≦ F1 / F2 ≦ 0.5. The high feed edge-changeable rotary tool according to claim 1, wherein the breaker groove has a plurality of U-shaped grooves formed in a longitudinal direction in an inward direction in a direction substantially perpendicular to the main cutting edge. And a cutting tool exchange-type rotary tool for high-feed machining, which has a rake face between the U-shaped grooves. 3. The high feed edge-changeable rotary tool according to claim 2, wherein a width (mm) of the rake face between the U-shaped grooves in the joint portion is RW, and a lateral width (mm) of the U-shaped groove is UW. When the longitudinal length (mm) is UH and the length (mm) from the ridge line portion of the main cutting edge to the U-shaped groove end is UL, 0.3 ≦ RW ≦ 0.35, 1.5 ≦ RW / UW ≦ 2.0, UH ≧ 1, 0.45 ≦ UL ≦ 0.80.

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