JP2007268648A - End mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an end mill capable of improving chip discharge efficiency to favorably perform cutting, and preventing the breakage of an end mill body and the defect of a cutting blade caused by the jam of chips to lengthen a life. <P>SOLUTION: In this end mill, a plurality of chip discharge grooves 4A, 4B are formed at the outer periphery of the tip of the end mill body 1 rotated around the axis O, and cutting blades 5A, 5B are formed on outer peripheral side edges of wall surfaces of these chip discharge grooves 4A, 4B that direct toward the forward side in the end mill rotating direction T. The chip discharge groove 4 includes multi-stage groove parts 11, 12 adjacent to each other in the circumferential direction, and at least one chip discharge groove 4A is constituted in multi-stages different in number from multi-stages of the other chip discharge groove 4B at least partially in the direction of the axis O. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is an end mill in which a plurality of chip discharge grooves are formed on the outer periphery of a tip end portion of an end mill body rotated about an axis, and a cutting edge is formed on an outer peripheral side ridge portion of a wall surface facing the front side in the end mill rotation direction. About.

In this type of end mill, if the chips generated by the cutting edge are clogged in the chip discharge groove, the cutting resistance will increase significantly, causing troubles such as damage to the end mill body and chipping of the cutting edge. Smooth discharge to the rear end side of the main body is required.
Incidentally, in Patent Documents 1 to 4, for example, a plurality of cutting blades that are spirally twisted are formed on the outer periphery of the tip portion of the end mill body, and the twist angle of at least one of these cutting blades is set to the other angle. It is called an unequal lead end mill in which the interval in the end mill rotation direction of the cutting blade is made different at least in part along the axial direction of the end mill body by making the unequal twist different from the twist angle of the cutting blade. Things have been proposed.

In such unequal lead end mills, the intervals at which the cutting blades bite into the work piece are different at the portions where the cutting blades have different intervals in the end mill rotation direction, and the torsion angles are also different. It is possible to prevent the end mill body from generating periodic vibration that resonates with its natural frequency because the cutting force by the blade and its action time are different, and chatter vibration caused by such resonance is prevented. Induction can be prevented. In addition, the same effect can be obtained even with an unequal division end mill in which only the interval in the end mill rotation direction of the cutting edge is set to an unequal pitch with the same twist angle, because the cutting edge biting interval becomes an unequal period. Can do.
Japanese Patent Publication No. 63-62323 Japanese Patent Publication No. 5-49408 Japanese Patent Publication No.7-115254 Japanese Patent Publication No. 3-19004

  By the way, in the end mill in which the intervals between the end blades in the end mill rotation direction are different in this way, as described above, the intervals at which each cutting edge bites on the work material are different. The amount of cut in the feed direction by means of is also different for each cutting edge, and the amount of cutting by the cutting edge, that is, the amount of generated chips and the thickness of the chips are also different. That is, in a cutting blade in which the circumferential interval between the cutting blade adjacent to the front side in the end mill rotation direction is larger than that of the other cutting blades, the cutting blade on the front side in the end mill rotation direction cuts the workpiece. Since the end mill main body is fed more before the cutting edge bites into the workpiece, the thicker chip than other cutting edges is generated and the amount of generated chips increases.

  In this way, a cutting blade having a larger distance from the cutting blade adjacent to the front side in the end mill rotation direction generates chips having a larger wall thickness than other cutting blades as described above, and the generation amount thereof is increased. The cutting load on the blade is large, and there is a possibility that a chipping or the like may occur as compared with other cutting blades having a small interval. Therefore, the life of the end mill is determined by the life of the cutting edge, and the end mill must be replaced even if there is little damage to the other cutting edges, leading to a reduction in the life of the end mill.

In addition, in a cutting blade that generates a large amount of chips with a large distance from the cutting blade adjacent to the front side in the end mill rotation direction, the width of the chip discharge groove located on the front side in the end mill rotation direction of the cutting blade is also It is possible to secure a certain amount of chip dischargeability, but depending on cutting conditions, the chip that is thick and difficult to curl is directed toward the rear end side of the end mill body through this chip discharge groove. May be difficult to discharge smoothly.
As described above, in the unequal division end mill and the unequal lead end mill, the chip discharge property is a big problem.

  The present invention has been made in view of such circumstances, and it is possible to perform cutting well by improving the chip dischargeability, and the end mill main body breakage or chipping of the cutting edge due to chip clogging. It is an object of the present invention to provide an end mill that can prevent the occurrence of the problem and extend the life.

  In order to solve this problem, according to the present invention, a plurality of chip discharge grooves are formed on the outer periphery of a tip end portion of an end mill body rotated about an axis, and the outer periphery of a wall surface facing the front side in the end mill rotation direction of these chip discharge grooves In an end mill in which a cutting edge is formed on a side ridge, the chip discharge groove includes a plurality of grooves adjacent to each other in the circumferential direction, and at least one chip discharge groove is the other in at least a part of the axial direction. It is characterized by having a different number of steps from the chip discharge groove.

  In the end mill of this configuration, for example, one chip discharge groove located on the front side in the end mill rotation direction of one cutting blade is cut out by one step more than the other chip discharge grooves, thereby forming a multi-stage. The size of the chip discharge groove is larger than that of the other chip discharge grooves, and the chips generated by one cutting blade can be reliably discharged to the rear end side of the end mill body. Therefore, the occurrence of chip clogging can be prevented and cutting can be performed satisfactorily, and damage to the end mill body and chip breakage due to chip clogging can be prevented, and the life of the end mill can be extended. .

  Here, the one cutting edge formed on the outer peripheral side ridge of the one chip discharge groove is at least partially in the axial direction in the end mill rotation direction with the cutting edge adjacent to the front side in the end mill rotation direction. By making the distance different from that of other cutting edges, a large quantity of thick chips generated by a single cutting edge with a large distance from the cutting edge adjacent to the front side in the end mill rotation direction in the so-called unequal division end mill. Can be reliably discharged to the rear end side of the end mill main body through one chip discharge groove that is multi-stage than the other chip discharge grooves.

  Further, by forming the twist angle of the one chip discharge groove to be different from the twist angle of the other chip discharge groove, in the so-called unequal lead end mill, the cutting edge adjacent to the front side in the end mill rotation direction A large amount of thick chips generated by the cutting blades having a large interval can be reliably discharged to the rear end side of the end mill body through the chip discharge grooves that are multi-staged than the other chip discharge grooves.

Therefore, even in an unequal division end mill or an unequal lead end mill in which chip dischargeability is a problem, it is possible to facilitate chip discharge by promoting chip discharge and to extend the life of the end mill.
In an unequal lead end mill, since the interval in the end mill rotation direction between cutting edges having different helix angles changes in the axis O direction, only the portion where the distance between the cutting edges is large is multistage than the other chip discharge grooves. If it comprises, chip discharge | emission property can be improved.

  The one chip discharge groove is connected to the front end in the end mill rotation direction of the cutting blade at least in a part of the axial direction, and is recessed inward in the radial direction of the end mill body, and the end mill rotation of the cutting blade. The other cutting blade adjacent to the front side in the direction is composed of a secondary groove connected to the front side in the end mill rotation direction, and an auxiliary groove arranged between the main groove and the secondary groove, and the other chip discharge groove is By configuring only the main groove and the sub-groove or the main groove, the size of one chip discharge groove can be assured as the auxiliary groove or the auxiliary groove and the sub-groove are formed rather than the other chip discharge groove. It is possible to increase the size, and it is possible to more reliably discharge the chips generated by one cutting blade to the rear end side of the end mill body.

  Similarly, at least a part of the one chip discharge groove in the axial direction is connected to the front end in the end mill rotation direction of the cutting edge and recessed inward in the radial direction of the end mill body, and the end mill of the cutting edge By configuring the other cutting edge adjacent to the front side in the rotational direction with a secondary groove connected to the front side in the rotational direction of the end mill, and configuring the other chip discharging groove only with the main groove, The size can be surely made larger than the other chip discharge grooves by the amount of forming the sub-grooves.

  Further, the cutting blade formed on the outer peripheral side ridge portion of the wall surface facing the front side in the end mill rotation direction of the one chip discharge groove and the other cutting blade adjacent to the front side in the end mill rotation direction of the cutting blade. The interval in the end mill rotation direction is gradually decreased from the front end side of the end mill main body toward the rear end side, and the one chip discharge groove is formed on the front end side of the end mill main body, the sub groove, and the auxiliary groove. In the rear end side of the end mill main body, the main groove and the auxiliary groove or the main groove alone is used, so that only the portion in the end mill rotation direction between the cutting blade and the other cutting blade is large. By forming the auxiliary groove or the auxiliary groove and the auxiliary groove, it is possible to improve the chip discharging property and perform the cutting work well.

  Similarly, the cutting edge formed on the outer peripheral side ridge of the wall surface facing the front side in the end mill rotation direction of the one chip discharge groove, and the other cutting edge adjacent to the front side in the end mill rotation direction of the cutting edge, The end mill rotation direction interval is gradually reduced from the end mill body front end side toward the rear end side, and the one chip discharge groove is constituted by the main groove and the sub groove on the end mill body front end side. By forming the main groove only on the rear end side of the end mill body, a sub-groove is formed only in a portion where the distance between the cutting edge and the other cutting edge in the end mill rotation direction is large, thereby reducing chip discharge. It is possible to improve the cutting process.

  According to the present invention, it is possible to perform cutting favorably by improving the chip discharge property, and it is possible to extend the life by preventing damage to the end mill body and chipping of the cutting edge due to chip clogging. An end mill can be provided.

Embodiments of the present invention will be described with reference to the accompanying drawings. 1 to 4 show an end mill according to an embodiment of the present invention.
This end mill has an end mill body 1 that is formed in a substantially cylindrical shape and rotated about an axis O, and the rear end side (right side in FIG. 1) of the end mill body 1 is gripped by the spindle end of a machine tool or the like. The end side of the end mill body 1 (the left side in FIG. 1) is the cutting edge 3.

  A plurality of strips (four strips in the present embodiment) that are twisted at a predetermined angle around the axis O from the front end side to the rear end side of the end mill body 1 toward the rear end side in the end mill rotation direction T are provided on the outer periphery of the cutting blade portion 3. A chip discharge groove 4 is formed, and a cross ridge line portion between a wall surface facing the front side in the end mill rotation direction T of the chip discharge groove 4 and an outer peripheral surface continuous to the rear side in the end mill rotation direction T, that is, the outer peripheral side of the wall surface. A cutting edge 5 serving as an outer peripheral edge is formed on the side ridge.

  That is, four cutting edges 5 that are twisted at a predetermined angle around the axis O from the front end side to the rear end side of the end mill main body 1 toward the rear side in the end mill rotation direction T are formed. Accordingly, the wall surface of the chip discharge groove 4 facing the front side in the end mill rotation direction T is the rake face 6, and the outer peripheral surface of the chip discharge groove 4 connected to the rear side in the end mill rotation direction T is the flank face 7 of the cutting blade 5. The Here, the rake face 6 has a concave curved shape recessed toward the rear side in the end mill rotation direction T, and the cutting edge 5 is given a positive rake angle. In addition, the rotation locus | trajectory which this cutting blade 5 makes around the axis line O is made into the cylindrical surface shape centering on the axis line O in this embodiment.

  On the other hand, a gash 8 extending from the chip discharge groove 4 to the inner peripheral side is formed at the tip of the cutting edge 3, and the edge on the tip side of the wall surface facing the front side in the end mill rotation direction T of the chip discharge groove 4. A bottom blade 9 extending from the tip of the cutting blade 5 to the vicinity of the axis O on the radially inner side of the end mill body 1 is formed in the portion. Here, the end mill of the present embodiment is a square end mill in which the bottom blade 9 and the cutting blade 5 that is an outer peripheral blade are arranged so as to be substantially orthogonal to each other in the rotation locus around the axis O.

Here, at least one cutting blade 5A (5B) of the plurality of cutting blades 5 is formed to have a twist angle different from that of the other cutting blade 5B (5A) adjacent to the front side in the end mill rotation direction T. The end mill of this embodiment is a so-called unequal lead end mill.
Further, the two cutting blades 5A, 5A (5B, 5B) facing each other across the axis O among the four cutting blades 5 have the same twist angle, and the cutting blade 5A adjacent to the end mill rotation direction T is the same. 5B, the torsion angles of 5B are different from each other. That is, the first cutting edges 5A having a twist angle α and the second cutting edges 5B having a twist angle β are alternately arranged in the end mill rotation direction T. In the present embodiment, the twist angle α of the first cutting edge 5A is α = 40 °, the twist angle β of the second cutting edge 5B is β = 45 °, and α <β.

  By arranging the first cutting edge 5A and the second cutting edge 5B in this way, the end mill between the first cutting edge 5A and the second cutting edge 5B adjacent to the front side in the end mill rotation direction T of the first cutting edge 5A. The interval P1 in the rotation direction T gradually decreases as it goes toward the rear end side of the end mill main body 1, and the second cutting edge 5B and the first cutting edge 5A adjacent to the front side in the end mill rotation direction T of the second cutting edge 5B. The interval P2 in the end mill rotation direction T gradually increases as it goes toward the rear end side of the end mill body 1.

  Therefore, at the tip end side of the end mill body 1, as shown in FIG. 2, the end mill rotation direction T between the first cutting edge 5A and the second cutting edge 5B adjacent to the front end side in the end mill rotation direction T of the first cutting edge 5A. Is larger than the interval P2 in the end mill rotation direction T between the second cutting edge 5B and the first cutting edge 5A adjacent to the front side of the end mill rotation direction T of the second cutting edge 5B. On the rear end side of the main body 1, as shown in FIG. 4, the interval P1 is smaller than the interval P2.

  Further, the groove widths W1 and W2 of the chip discharge grooves 4A and 4B located on the front side in the end mill rotation direction T of the first and second cutting edges 5A and 5B are also different from each other in the twist angle of the cutting edges 5A and 5B. , It gradually changes in the direction of the axis O. That is, the groove width W1 of the first chip discharge groove 4A located between the first cutting edge 5A and the second cutting edge 5B adjacent to the front side in the end mill rotation direction T of the first cutting edge 5A is the end mill body 1. The second chip discharge groove 4B is gradually narrowed toward the rear end side and is located between the second cutting edge 5B and the first cutting edge 5A adjacent to the front side in the end mill rotation direction T of the second cutting edge 5B. The groove width W2 is configured to gradually become wider toward the rear end side of the end mill body 1.

  As shown in FIGS. 1 and 3, the first chip discharge groove 4 </ b> A is connected to the front end of the first cutting edge 5 </ b> A in the end mill rotation direction T and is largely recessed toward the inner end in the radial direction of the end mill body 1. The sub-groove 12 connected to the rear side in the end mill rotation direction T of the flank 7 of the second cutting edge 5B adjacent to the front side in the end mill rotation direction T of the first cutting edge 5A, and between the main groove 11 and the sub-groove 12 And an auxiliary groove 13 located at the same position.

Here, at the front end side of the end mill body 1, as shown in FIG. 2, the curvature formed by the sub-groove 12 and the auxiliary groove 13 is substantially the same, and is configured to form one convex curve. The auxiliary groove 13 is rounded up in the direction of the axis O, and the auxiliary groove 13 is not disposed on the rear end side of the end mill body 1 as shown in FIG.
That is, the auxiliary groove 13 is formed in the end mill main body 1 front end side portion where the interval P1 in the end mill rotation direction T between the first cutting edge 5A and the second cutting edge 5B located on the front side in the end mill rotation direction T is large. The auxiliary groove 13 is not formed in the rear end side portion of the end mill body 1 having the small interval P1.

  On the other hand, the second chip discharge groove 4B is connected to the front side in the end mill rotation direction T of the second cutting edge 5B and is largely recessed toward the inner side in the radial direction of the end mill body 5 and the end mill rotation direction of the second cutting edge 5B. It has the sub-groove 12 which continues in the end mill rotation direction T back side of the flank 7 of the 1st cutting blade 5A adjacent to T front side.

  Further, in the present embodiment, in the groove depth D of the main groove 11, that is, in the cross section orthogonal to the axis O of the end mill body 1, the difference between the cutting edge radius and the radial length at the groove bottom of the main groove 11 is the axis. Since the groove depth of the sub-groove 12 and the auxiliary groove 13 is set to be shallower than the groove depth D of the main groove, the end mill has a center thickness in the axis O direction. It is assumed to be constant.

  In the end mill configured as described above, the shank portion 2 formed at the rear end of the end mill body 1 is gripped by the spindle end of the machine tool, rotated around the axis O, and in a direction intersecting the axis O. It is sent toward and forms a groove in the material to be cut, or performs surface processing and end surface processing.

According to the end mill of the present embodiment, the end mill rotation direction between the first cutting edge 5A and the second cutting edge 5B located on the front side in the end mill rotation direction T of the first cutting edge 5A on the distal end side of the end mill body 1. The interval P1 of T is increased, and many thick chips are generated by the first cutting edge 5A.
Here, the first chip discharge groove 4A located on the front side in the end mill rotation direction T of the first cutting edge 5A includes the auxiliary groove 13 in addition to the main groove 11 and the sub-groove 12, and the second chip discharge groove 4B. Since the size of the first chip discharge groove 5A is larger than that of the second chip discharge groove 4B, the chips generated by the first cutting blade 5A are disposed behind the end mill body 1 because the first chip discharge groove 5A is larger than the second chip discharge groove 4B. It is possible to reliably discharge toward the end side. Therefore, occurrence of chip clogging can be prevented and cutting can be performed satisfactorily, and damage to the end mill body 1 and loss of the first cutting edge 5A due to chip clogging can be prevented, thereby extending the life of the end mill. Can be planned.

  Here, in the present embodiment, the distance P2 between the second cutting edge 5B and the first cutting edge 5A located on the front side in the end mill rotation direction T gradually increases toward the rear end side of the end mill body 1, and the end mill The interval P2 is increased on the rear end side of the main body 1 and a lot of thick chips are generated by the second cutting edge 5B. However, since the distance that the chips scrape the second chip discharge groove 4B is short, It is not necessary to provide the auxiliary groove 13 in the second chip discharge groove 4B.

  Further, by making the groove depth D of the main groove 11 that is the most recessed inward in the radial direction of the end mill body 1 constant, the core thickness of the end mill is also constant in the direction of the axis O, ensuring the rigidity of the end mill and cutting resistance. It is possible to prevent deformation due to bending.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.
For example, in the present embodiment, the description has been given as a four-blade end mill in which the chip discharge groove and the four cutting edges are formed, but a two-blade, three-blade end mill may be used, and five or more cutting blades may be used. It may be an end mill equipped with.

Moreover, although it demonstrated as an unequal lead end mill from which the twist angle of an adjacent cutting blade differs in an end mill rotation direction, it is not limited to this, For example, the twist angle of only one of four cutting blades is different. It may be an unequal lead end mill, or may be an unequal division end mill having the same twist angle but different only in the interval in the end mill rotation direction between adjacent cutting edges.
Further, it may be an end mill having the same helix angle and the same distance between the cutting edges. In this case, the rigidity of one cutting edge is different, and vibration of the end mill main body can be prevented as in the case of the unequal lead end mill and the unequal split end mill.

  Furthermore, although the description has been made with the twist angle α of 40 ° and the twist angle β of 45 °, the twist angles α and β are not limited and are preferably set appropriately in consideration of the work material, cutting conditions, and the like. .

It is a side view of the end mill which is an embodiment of the present invention. It is AA 'sectional drawing in FIG. It is BB 'sectional drawing in FIG. It is CC 'sectional drawing in FIG.

Explanation of symbols

1 End mill body 4A, 4B Chip discharge groove 5A, 5B Cutting edge 11 Main groove 12 Sub groove 13 Auxiliary groove

Claims (7)

An end mill in which a plurality of chip discharge grooves are formed on the outer periphery of the tip end portion of the end mill body rotated around the axis, and a cutting edge is formed on the outer side edge of the wall surface facing the front side in the end mill rotation direction of these chip discharge grooves. In
The chip discharge groove includes a plurality of groove portions adjacent to each other in the circumferential direction, and at least one chip discharge groove is configured to have a different number of steps from other chip discharge grooves in at least a part of the axial direction. Features an end mill.   One cutting edge formed on the outer peripheral side ridge portion of the one chip discharge groove has an interval in the end mill rotation direction with a cutting blade adjacent to the front side in the end mill rotation direction at least in a part of the axial direction. The end mill according to claim 1, wherein the end mill has a size different from that of the cutting edge.   The end mill according to claim 1 or 2, wherein a twist angle of the one chip discharge groove is different from a twist angle of the other chip discharge groove. The one chip discharge groove is connected to the front end in the end mill rotation direction of the cutting edge at least in a part in the axial direction, and is recessed inward in the radial direction of the end mill main body, and the front end in the end mill rotation direction of the cutting edge. It is composed of a sub-groove that continues to the front side in the end mill rotation direction of the other cutting blade adjacent to the side, and an auxiliary groove disposed between the main groove and the sub-groove,
The end mill according to any one of claims 1 to 3, wherein the other chip discharge groove includes only the main groove and the sub-groove or the main groove. The one chip discharge groove is connected to the front end in the end mill rotation direction of the cutting edge at least in a part in the axial direction, and is recessed inward in the radial direction of the end mill main body, and the front end in the end mill rotation direction of the cutting edge. Consists of sub-grooves connected to the front side in the end mill rotation direction of the other cutting blade adjacent to the side,
The end mill according to any one of claims 1 to 3, wherein the other chip discharge groove includes only the main groove. End mill rotation between the cutting edge formed on the outer peripheral side ridge portion of the wall surface facing the front side in the end mill rotation direction of the one chip discharge groove and the other cutting edge adjacent to the front side in the end mill rotation direction of the cutting edge. The direction interval is gradually reduced from the front end side of the end mill body toward the rear end side,
The one chip discharge groove is constituted by the main groove, the sub groove, and the auxiliary groove on the front end side of the end mill body, and the main groove, the sub groove, or the main groove on the rear end side of the end mill body. The end mill according to claim 4, wherein the end mill is constituted only by the above. End mill rotation between the cutting edge formed on the outer peripheral side ridge portion of the wall surface facing the front side in the end mill rotation direction of the one chip discharge groove and the other cutting edge adjacent to the front side in the end mill rotation direction of the cutting edge. The direction interval is gradually reduced from the front end side of the end mill body toward the rear end side,
The one chip discharge groove is constituted by the main groove and the sub groove on the end mill main body front side, and is constituted only by the main groove on the end mill main body rear end side. Item 5. The end mill according to Item 5.

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