JP2006000985A - Cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform a much more efficient thrust cutting operation by improving the chip removability in bottom edge cutting without deteriorating the stiffness of a tool. <P>SOLUTION: An endmill 1 has a plurality of helicoidal chip removal grooves 3 formed on the outer periphery on the tip end side of a tool body 2. Outside peripheral cutting edges 6 are formed at the ridges where the groove wall surfaces 4 of the respective chip removal grooves 3 facing to the rotational direction of the tool intersect the outer peripheral surface of the tool body 2. In addition, end cutting edges 8 are arranged on the tip end surface of the tool body 2 toward the center of the tool body 2 so as to be connected with the respective outside peripheral cutting edges 6. Gashes 10 forming the rake surfaces 12 of the respective end cutting edges 8 are arranged so as to be connected with the tip end portions of the chip removal grooves 3 arranged in the axial direction of the tool body 2. The gashes 10 are formed, in a side view, such that groove widths B gradually increase with the depth in the axial direction of the tool body 2 because the rear wall surfaces 11b on the rear side in the rotational direction of the tool are directed to the twisted direction of the outside peripheral cutting edges 6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cutting tool such as an end mill or a drill for forming a hole or a recess in a workpiece by piercing using a machine tool.

A plurality of spiral chip discharge grooves are formed on the outer periphery of the tool body at intervals in the circumferential direction, and outer peripheral blades are formed on the outer peripheral surface of the tool body along the respective chip discharge grooves. A plurality of bottom blades having different lengths that are continuous with the blades and directed toward the center of the tool body are provided at the tip of the tool body, and a gash groove that forms a rake face of each bottom blade is the tool body of the chip discharge groove In the end mill continuously provided at the tip portion in the axial direction of each of the above, by setting each of the gash angles that are inclined angles with the surface perpendicular to the axis of the tool body of each gash groove to a predetermined value, The depth in the axial direction on the outer peripheral side of the tool body of the gash groove is a constant value, so that the volume of the chip discharge path related to each bottom blade is made substantially uniform, and the chip discharge performance is good and high. Cutting performance is obtained Is, there is known the end mill hardly occurs a defect of the end cutting edge (e.g., see Patent Document 1).
In order to achieve the same purpose, a bottom blade is provided on the extension of the lead rake face that forms a spiral outer peripheral blade provided on the outer periphery of the tip of the tool body, and the groove bottom surface of the gash groove In the direction along the outer peripheral edge, a convex surface facing the outer peripheral side of the tool body is formed, and a boundary portion where the lead rake surface and the gash groove intersect is formed in an arc surface, following the convex gash groove An end mill is also known that is configured to facilitate the flow of chips toward the outer periphery of the tool body (see, for example, Patent Document 2).
Japanese Utility Model Publication No. 7-40021 Japanese Patent Laid-Open No. 10-217024

  However, in the former end mill, the depth of the gash groove in the axial direction on the outer peripheral side of the tool body is about 0.10 to 0.14 times the diameter of the tool and is extremely shallow, and the bottom surface of the gash groove is constant. Since it is formed on the inclined surface of the angle, the volume of the chip discharge path related to each bottom blade at the tool tip cannot be sufficiently increased, and the connection between the gash groove and the chip discharge groove is not smooth, and therefore However, it is not possible to sufficiently enhance the discharge of chips generated by each bottom blade to the outside, and it does not sufficiently meet the demand as a cutting tool capable of performing highly efficient plunging. Also, in the case of the former end mill, the gash grooves are formed along the bottom blades and along the axial direction of the tool body. The side is notched deeply, and the tool rigidity may decrease as the number of tool blades increases.

  In the latter end mill, the gash groove is directed toward the chip discharge groove with a constant groove width, and the bottom surface is formed in a convex shape so that the chips generated by the bottom blade can easily flow toward the chip discharge groove side. However, since the depth of the gash groove is up to about 0.5 times the diameter of the tool because the gash angle is about 45 ° at the maximum, a chip pocket can be taken larger than the former end mill. There is still a problem that the size of the chip pocket is still insufficient for discharging chips generated in a large amount when performing a more efficient plunging process. Further, since the groove surface on the lead rake face side of the gash groove is provided in common along the lead rake face and the rake face of the bottom blade, the chips generated by the bottom blade rub the lead rake face and There is a risk of flowing to the blade side and damaging the outer peripheral blade.

  The present invention has been made in view of the above circumstances, and provides a cutting tool capable of performing a more efficient plunging process without impairing the rigidity of the tool, improving the chip discharging performance during the plunging process. With the goal.

The present invention is characterized by the following points in order to solve the above problems.
That is, in the cutting tool according to claim 1 of the present invention, a plurality of helically twisted chip discharge grooves are formed on the outer periphery on the tip side of the tool body at intervals in the circumferential direction, and the tool rotation of each chip discharge groove is performed. An outer peripheral blade is formed at the intersecting ridge line portion between the groove wall surface facing the direction and the outer peripheral surface of the tool body, and a bottom blade continuous with each outer peripheral blade is directed toward the center of the tool body at the tip of the tool body. A cutting tool provided with a gash groove that forms a rake face of each bottom blade provided continuously at a tip portion in the axial direction of the tool body of the chip discharge groove. As the depth in the axial direction of the main body increases, the groove width is gradually increased by directing the rear side wall surface facing the tool rotation direction in the twist direction of the outer peripheral blade. Yes.

The cutting tool according to claim 2 is the cutting tool according to claim 1, wherein a rear side wall surface of the gasche groove facing the tool rotation direction is formed as a convex curved surface facing the tool rotation direction in a side view. It is characterized by.
The cutting tool according to claim 3 is the cutting tool according to claim 1 or 2, wherein the rear side wall surface of the gash groove facing the tool rotation direction has a wide angle directed to the twisting direction of the outer peripheral blade. It is characterized in that it is set within the range of the twist angle of the outer peripheral blade at 5 ° or more from the rake face.

The cutting tool according to a fourth aspect is the cutting tool according to any one of the first to third aspects, wherein the gash groove exceeds the depth in the axial direction of the tool body by more than 0.5 times the tool diameter. It is characterized by being set in a range of 5 times or less.
The cutting tool according to claim 5 is the cutting tool according to any one of claims 1 to 4, wherein the gash groove has a gash angle set in a range of 20 ° to 70 °, and the groove bottom surface of the tool main body. It is formed in the convex curved surface which faces the outer peripheral side.

The present invention has the following excellent effects.
That is, according to the cutting tool of the first aspect, the gash groove increases in the groove width gradually toward the twist direction of the outer peripheral blade as the depth from the tip in the axial direction of the tool body increases in a side view. The chip discharge groove and the chip discharge path for sending the chip generated by the bottom blade to the chip discharge groove can be smoothly connected, and the chip discharge path can be secured largely. can do.
Therefore, even when a large amount of chips are generated by the bottom blade by high-efficiency plunging processing, the chips discharge path without clogging the chip discharge path or entangled with the outer peripheral blade. Can be smoothly discharged and discharged to the outside without causing damage to the outer peripheral blade and the work surface of the workpiece, and ensuring high-efficiency piercing without impairing tool rigidity. It can be carried out.

Further, according to the cutting tool according to claim 2, the rear side wall surface facing the tool rotation direction of the gash groove is formed into a convex curved surface, so that the chips are generated by the rear side wall surface and the bottom blade of the gash groove. Rubbing with the chips flowing into the discharge groove can be reduced, and the flow of the chips can be improved.
According to the third aspect of the present invention, the rear side wall surface facing the tool rotation direction of the gash groove can set the wide angle directed in the twist direction of the outer peripheral blade to an appropriate angle, and the chip discharge path The connection to the chip discharge groove can be made smoother, and the flow of the chip generated by the bottom blade to the chip discharge groove can be made better.

Moreover, according to the cutting tool which concerns on Claim 4, the depth in the axial direction of the tool main body of a gash groove can be set appropriately, and the chip discharge which sends out the chip | tip produced | generated with the bottom blade to the chip discharge groove side The route can be made sufficiently large.
According to the cutting tool of claim 5, the tool on the tool tip side is formed by setting the gash angle of the gash groove to an appropriate angle and forming the groove bottom surface as a convex curved surface facing the outer peripheral side of the tool body. The chips generated by the bottom blade can be more smoothly sent to the chip discharge groove side and discharged outside without impairing the rigidity.

Hereinafter, a cutting tool according to an embodiment of the present invention will be described with reference to the drawings.
1 to 3, reference numeral 1 denotes an end mill as a cutting tool according to an embodiment of the present invention. The end mill 1 includes a cylindrical tool body 2 made of a hard material such as cemented carbide. On the distal end side of the tool body 2, there are a plurality of (three in the illustrated example) chip discharge grooves 3, 3, and 3 spirally twisted to the right from the distal end (tool distal end) toward the proximal end side. The tool body 2 is formed at equal intervals in the circumferential direction. And the intersection ridgeline part of the groove wall surface 4 which faces the tool rotation direction (arrow T direction in FIG. 2, FIG. 3) of each said chip | tip discharge groove | channel 3, and the front end side outer peripheral surface 5 (refer FIG. 3) of the said tool main body 2 A plurality of (three in the illustrated example) outer peripheral blades 6, 6, 6 that are spirally twisted to the right along the chip discharge groove 3 are formed. A first flank 7a and a flank 7b are provided in this order on the rear side of the outer peripheral blades 6, 6, 6 in the tool rotation direction T.

  The groove wall surface 4 is continuously connected to the outer peripheral blades 6, 6, 6 on the outer peripheral side of the tool body 2, at the tip of the tool body 2 in the axial direction on the groove wall surface 4. A plurality of (three in the illustrated example) bottom blades 8, 8, 8 extending from the outer periphery of the tool body 2 toward the center are formed. One of the bottom blades 8, 8, 8 is formed as a long blade whose inner end reaches the vicinity of the center C of the tool body 2, and the other two bottom blades 8, 8 are substantially The short blade is shorter than the long blade with the same length. First and second tip flank surfaces 9a and 9b are provided in this order on the rear side of each bottom blade 8, 8, and 8 in the tool rotation direction T, and the second tip flank surface 9b is formed in the chip discharge groove 3. Have been contacted. In addition, each bottom blade 8,8,8 may be made into the same length, without making the length of a long blade and a short blade different.

  Further, at the tip end side in the axial direction of the tool body 2 in the chip discharge groove 3, only the portion along the bottom blade 8 which is a long blade in FIG. ), The recesses cut into the center C side of the tool body 2 as it goes to the tip, and the bottom blades 8, 8, 8 are provided with gash grooves 10, 10, 10 that form rake faces. . As shown in FIG. 2, the gash groove 10 has a groove width B as the length (depth) from the tool tip (bottom blade 8) in the axial direction of the tool body 2 increases in a side view (FIG. 2). However, it is formed so as to gradually expand (become large) in the twist direction of the outer peripheral blades 6, 6, 6 from the narrow groove width B1 to the wide groove width B2. The rear side wall surface 11b facing the front side wall surface 11a of the gash groove 10 and facing the tool rotation direction T has a distal end connected to the rake face 12 and a proximal end side along the twist direction of the outer peripheral blade 6 in a side view. It is formed to extend. And the groove bottom 10a of the gash groove | channel 10 is formed in circular arc shape in the cross section as shown in FIG. 4, FIG.

  And the length (depth) L in the axial direction from the front-end | tip (bottom blade 8) of the tool main body 2 of each said gash groove | channel 10 is a range exceeding 0.5D and 1.5D or less, when a tool diameter is set to D. Is set to Further, the spread angle (hereinafter referred to as “wide angle”) θ2 of the rear side wall surface 11b of the gash groove 10 in the twist direction of the outer peripheral blades 6, 6, 6 is a rake surface having the rake angle θ1 of the bottom blade 8. The twist angle of the outer peripheral blade 6 is set within a range of 12 to 5 ° or more. A rear side wall surface 11b of the gash groove 10 is formed as a convex curved surface 13 facing the inner side of the gash groove 10 (tool rotation direction T). The convex curved surface 13 includes a convex arc surface close to the convex arc surface and various other shapes of convex curved surfaces.

  Further, as shown in FIG. 6, each gash groove 10 has a gash angle (an angle formed with the tip surface of the tool body 2 (surface of the bottom blade 8)) α in a range of 20 ° to 70 °. A direction along the rear side wall surface 11b by gradually changing the gash angle α as the depth of the gash groove 10 in the axial direction of the tool body 2 increases with the minimum value of the gash angle α of the tip portion being 20 °. Is formed in a convex curved surface facing the outer peripheral side of the tool body 2, and the depth of the gash groove 10 in the radial direction of the tool body 2 is determined by the tool body. 2 gradually decreases from the distal end side toward the proximal end side, and is smoothly connected (continuously) to the bottom of the chip discharge groove 3. The maximum value of the gash angle α of the tip can be allowed to be 70 °, but it is more preferable to keep it within 50 ° as much as possible in order to ensure the rigidity of the tool.

  The end mill 1 according to the embodiment configured as described above is attached to a spindle of a machine tool such as a machining center by attaching a tool body 2 to a tool holder or the like, and rotates around the axis S of the tool body 2 by rotation of the spindle. And a cutting feed to the tip side in the direction of the axis S is given to perform a piercing process such as a drilling process at a predetermined position of the workpiece. At that time, chips generated by cutting the workpiece by the bottom blades 8, 8, 8 at the tip of the tool body 2 move in the chip discharge path formed by the gash grooves 10 in the outer peripheral direction of the tool body 2. However, after flowing to the base end side, it passes through the chip discharge groove 3 and is discharged to the outside from the machining hole of the workpiece.

  In this case, the axial direction of the tool body 2 is such that each of the gash grooves 10 has a wide angle of an angle θ2 of 5 ° or more from the rake face of the rake face 12 of the bottom blade 8 in a side view. As the depth from the tip increases, the groove width B is gradually increased from the narrow groove width B1 to the wide groove width B2 in the direction of twisting of the outer peripheral blades 6, 6 and 6. In addition, it is possible to smoothly connect the chip discharge groove 3 and the gash groove 10 for sending the chip generated by the bottom blade 8 to the chip discharge groove 3, and to ensure a large cross-sectional area of the gash groove. Moreover, the depth L from the tip of the tool body 2 in the axial direction of the tool body 2 is set sufficiently deep as a range of more than 0.5D and not more than 1.5D. The volume of the exit path can be secured sufficiently large.

Therefore, in the end mill 1 according to the embodiment, even when a large amount of chips are generated by the bottom blade 8 by high-efficiency piercing, the chips are clogged in the chip discharge path, and FIG. As shown in FIG. 7 (b), it is deformed as shown in FIG. 7 (a) without being entangled with the outer peripheral blade 6 of the tool body 2 and swung around, as shown in FIG. Since it passes smoothly through the gash groove 10 and is smoothly discharged to the outside, the peripheral blade 6 and the work surface of the workpiece are not damaged, and high-efficiency plunge machining is ensured without impairing the tool rigidity. It can be carried out.
When the wide angle θ2 of the rear side wall surface 11b of the gash groove 10 is smaller than 5 °, the rear side wall surface 11b is moved to the direction along the axis S (FIG. 1) of the tool body 2 (as indicated by the chain line in FIG. 2). It becomes close to the rear side wall surface 11x, and the spread (groove width B2) on the terminal side of the tool body 2 in the axial direction of the gash groove 10 cannot be increased. For this reason, the chips generated by the bottom blade 8 rub against the inner wall surface of the gash groove 10 and the shape of the chips is deformed as shown in FIG. It does not have a curl shape like 7 (a).
If the depth L from the tip of the gash groove 10 in the axial direction of the tool body 2 is smaller than 0.5D, the chip discharge path cannot be made sufficiently large. May decrease and the bottom blade 8 may be lost.

  Further, in the end mill 1 according to the embodiment, the rear side wall surface 11b of the gash groove 10 is formed on the convex curved surface 13 facing the inside of the gash groove 10, and the rear side wall surface 11b is the groove wall surface. 4 is set at a position closer to the front side in the tool rotation direction T. Therefore, when chips generated by the bottom blade 8 during the plunging process pass through the gash groove 10, the rear side wall surface 11b Reducing the friction with the chips, smoothing the flow of the chips to the base end side (left side of FIG. 2) of the tool body 2, and reducing the friction of the chips with respect to the groove wall surface 4 and the outer peripheral blade 6. The wear of the outer peripheral blade 6 can be reduced.

  Further, in the end mill 1 according to the embodiment, the gash groove 10 is set so that the gash angle α is in a range of 20 ° to 70 °, and the minimum value of the gash angle α at the tip is 20 °. As the depth of the tool body 2 in the axial direction increases, the gash angle α is gradually changed so that the gash surface 10b in the longitudinal section in the direction along the rear side wall surface 11b protrudes toward the outer peripheral side of the tool body 2. Since it is formed in a curved surface and smoothly continues to the chip discharge groove 3, the chip generated by the bottom blade 8 is made larger by increasing the chip discharge path without impairing the tool rigidity of the tool tip. It can be smoothly discharged to the chip discharge groove 3. When the gash angle α is smaller than 20 °, the chip discharge path at the tip of the tool becomes too small, and when it exceeds 70 °, the chip discharge path becomes large but the tool rigidity is lowered.

  In the cutting tool according to the above embodiment, the present invention is applied to a square end mill.However, the present invention is not limited to this, and end drilling such as a radius end mill and a ball end mill, and drilling such as a drill are performed. The same effect can be obtained by applying the same to the rotary cutting tool to be performed.

It is a side view which shows the end mill as a cutting tool which concerns on one embodiment of this invention. It is an enlarged side view of the tip part of the end mill. It is a front view of the front-end | tip part of an end mill similarly. FIG. 3 is a cross-sectional view taken along the line II in FIG. 2. FIG. 3 is a cross sectional view of FIG. FIG. 3 is a cross-sectional view of the haha of FIG. 2. It is a figure which shows the shape of the chip at the time of the drilling process by an end mill.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 End mill 2 Tool body 3 Chip discharge groove 4 Groove wall surface 6 Peripheral blade 8 Bottom blade 10 Gash groove 10a Gash groove groove bottom 11a Gash front side wall surface 11b Gash rear side wall surface 12 Rake angle 13 Convex curved surface α Gash angle θ1 Rake surface θ2 Wide angle B Groove width D Tool diameter L Gash groove depth T Tool rotation direction

Claims (5)

A plurality of spirally twisted chip discharge grooves are formed on the outer periphery on the tip side of the tool main body at intervals in the circumferential direction, and a groove wall surface facing the tool rotation direction of each chip discharge groove and the outer peripheral surface of the tool main body A peripheral edge is formed at the crossing ridge part, and a bottom blade continuous to each of the peripheral blades is provided toward the center of the tool body at the tip of the tool body, forming a rake face of each bottom blade In the cutting tool that is continuously provided at the tip portion in the axial direction of the tool body of the chip discharge groove,
As the depth of the tool body in the axial direction increases in the side view, the groove wall width gradually increases as the rear side wall surface facing the tool rotation direction is oriented in the twist direction of the outer peripheral blade. A cutting tool characterized by being formed as follows.   The cutting tool according to claim 1, wherein a rear side wall surface of the gash groove facing the tool rotation direction is formed as a convex curved surface facing the tool rotation direction in a side view.   The rear side wall surface of the gash groove facing the tool rotation direction has a wide angle directed in the twist direction of the outer peripheral blade set in a range of the twist angle of the outer peripheral blade at 5 ° or more from the rake face of the bottom blade. The cutting tool according to claim 1 or 2, characterized by the above.   The depth of the gash groove in the axial direction of the tool body is set in a range of more than 0.5 times and less than 1.5 times the tool diameter. The described cutting tool. The gash groove has a gash angle set in a range of 20 ° to 70 °, and the groove bottom surface is formed as a convex curved surface facing the outer peripheral side of the tool body. The cutting tool described in 1.

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