JP5645333B2 - Christmas cutter - Google Patents

Description

The present invention relates to a Christmas cutter, more particularly, to a Christmas cutter chip discharge grooves are provided linearly so as to be inclined at a predetermined inclination angle with respect to the axis.

  An outer peripheral cutting edge is provided along the chip discharge groove, and the diameter dimension of the outer peripheral cutting edge is changed in the tool axis direction, and is rotated with respect to the workpiece while being rotated about the axis S. A general-purpose rotary cutting tool that cuts a groove having a predetermined shape whose groove width changes in the groove depth direction by being relatively moved in a direction perpendicular to the center S is known. The Christmas cutter described in Patent Document 1 is an example thereof, and a tree-shaped groove that is symmetrical with respect to the groove center and narrows toward the groove bottom side while increasing or decreasing the groove width in the groove depth direction as in an inverted Christmas tree. Cutting is performed, and the diameter of the outer peripheral cutting edge is gradually reduced to a smaller diameter while increasing or decreasing toward the tip of the tool in response to a change in the groove width. Further, Patent Document 2 relates to a tapered end mill in which the diameter dimension of the outer peripheral cutting edge becomes smaller toward the tool tip side, and a twisted groove twisted in the direction opposite to the tool rotation direction viewed from the shank side is provided as a chip discharge groove. Have been proposed.

JP 2009-226533 A Japanese Patent Laid-Open No. 7-9237

  However, the chip discharge groove of such a conventional general-purpose rotary cutting tool is a straight groove parallel to the shaft center S or a twist groove twisted at a predetermined twist angle with respect to the shaft center S. There was still room for improvement, such as the fact that satisfactory sharpness could not be obtained, the cutting resistance was great, and vibrations and groove collapse could occur.

  The present invention has been made against the background of the above circumstances. The purpose of the present invention is to improve the cutting accuracy and reduce cutting resistance and vibration, and to improve the machining accuracy by suppressing the collapse of the groove and the amount of machining expansion. There is to make it.

To achieve the above object, the first invention, with the peripheral cutting edge is provided along the chip discharge groove, the axis S perpendicular while being rotated around the axis S with respect to the workpiece By moving relative to each other, a tree-shaped groove that is symmetrical with respect to the groove center and narrower toward the groove bottom side while increasing or decreasing the groove width in the groove depth direction can be cut like an inverted Christmas tree. As described above, in the Christmas cutter in which the diameter of the outer peripheral cutting edge gradually decreases as the diameter of the outer peripheral cutting edge increases and decreases in response to the change in the groove width, the chip discharge groove is formed from the shank side. It is characterized by being linearly provided so as to incline at a constant inclination angle within a range of 1 ° to 8 ° with respect to the axis S in a direction opposite to the seen tool rotation direction.

The second aspect, in the first shot bright Christmas cutter, the peripheral cutting edge is formed in a wave shape diameter is small oscillations with a groove width smaller than the groove having a desired shape, and, A luffing cutting edge in which the wave shapes of a plurality of outer peripheral cutting edges are shifted from each other, and is used for roughing or intermediate finishing.

The third aspect, in the first shot bright Christmas cutter, the peripheral cutting edge is diameter are approximately the same dimension as the groove width of the groove having a desired shape, and characterized by being used in finishing To do.

In such a Christmas cutter , the chip discharge groove is straight so as to incline at a constant inclination angle within a range of 1 ° to 8 ° with respect to the axis S in the direction opposite to the tool rotation direction seen from the shank side. Therefore, according to experiments by the present inventors, the amount of groove collapse, the amount of processing expansion, and the cutting resistance were reduced as compared with the case of straight grooves and twisted grooves. In addition, vibration, cutting sound, and machined surface were improved as compared with the straight groove, and the same or better results were obtained when compared with the twisted groove. Thus, the cutting performance is improved as a whole, and excellent machining accuracy can be obtained, so that it is possible to perform further highly efficient machining.

  Further, for example, the chip discharge groove is machined by moving the grinding wheel relatively linearly in a direction inclined at a constant inclination angle with respect to the axis S of the tool material while the tool material is fixed in a fixed posture. Compared to the case where the grinding wheel is moved relative to the axial direction while rotating the tool material around the axis S like a torsion groove, the device for machining the chip discharge groove is simple and inexpensive. In addition, since there is no change in the shape of the groove cross-section due to interference grinding, setting of the groove cross-sectional shape becomes easy.

The second invention relates to a Christmas cutter for roughing or semi-finishing, and since the tilting of the groove and the amount of processing expansion are improved, roughing and semi-finishing can be performed with dimensions closer to the finishing dimension. It is possible, and the cutting dimension (finishing allowance) at the time of finishing can be reduced, so that more stable and highly accurate finishing can be performed. In other words, the Christmas cutter for roughing and semi-finishing machining generally employs a twisted groove (twisted blade) twisted around the axis S with an emphasis on cutting performance, but the tilt type chip discharge groove of the present invention. According to this, it was possible to improve machining accuracy while maintaining cutting performance such as sharpness.

The third invention relates to a Christmas cutter for finishing, and since the tilting of the groove, the processed surface, and the amount of processing expansion are improved, finishing can be performed with higher dimensional accuracy. That is, the Christmas cutter for finishing machining generally adopts a straight groove (straight blade) parallel to the axis S with an emphasis on machining accuracy, but according to the tilt type chip discharge groove of the present invention, the sharpness is sharp. Since the vibration and cutting resistance are reduced by improving the cutting performance such as the above, the machining accuracy can be further improved.

It is a figure explaining the case where the present invention is applied to a Christmas cutter for finishing, (a) is a front view with a part cut away, (b) is an enlarged view of the blade, (c) is (b) It is IC-IC sectional drawing in. It is a figure which compares and demonstrates the difference with the conventional straight groove | channel and the twist groove | channel, and the inclination groove | channel of this invention. In the case of an inclined groove, it is a figure explaining the groove cross-sectional shape which changes with the distance from a front-end | tip. It is a figure explaining the result of having calculated | required the rake angle of each part concretely regarding the inclination groove | channel of this invention, the conventional twist groove | channel, and the straight groove | channel about the Christmas cutter from which the diameter dimension is changing. The figure explaining the result of examining the cutter performance by cutting under the cutting conditions of (a) using the product of the present invention, the conventional product, and the comparative product, (b) is the case of the intermediate finish cutter, (c) Is the case of a finishing cutter. FIG. 3 is a diagram for explaining a case where the present invention is applied to a Christmas cutter for intermediate finishing, in which (a) is a front view with a part cut away, (b) is an enlarged view of an outer peripheral cutting edge, and (c) is ( It is an enlarged view of the VIC-VIC cross section in a). It is a figure explaining the difference (finishing allowance of a finishing cutter) of the dimension of the finishing cutter used in the performance test of FIG. 5, and a finishing cutter. FIG. 6 is a diagram for specifically explaining the groove collapse amount, the processing expansion amount, and the cutting resistance examined in the performance test of FIG. 5.

The present invention is suitably applied to a Christmas cutter for intermediate finishing and finishing when a tree-shaped groove is cut in two stages of intermediate finishing and finishing. The present invention can also be applied to Christmas cutters for intermediate finishing and roughing when processing. The roughing and intermediate finishing Christmas cutters of the second invention are provided with corrugated roughing cutting edges, but the present invention is also applied to roughing and intermediate finishing Christmas cutters provided with nicks. Can be applied. These Christmas cutters are configured to have a bottom blade at the tip of the tool in addition to the outer peripheral cutting blade.

For example, the roughing and intermediate finishing Christmas cutters have, for example, three blades, and the finishing Christmas cutter has, for example, four blades. Can be determined. For example, it is possible to provide four or more outer peripheral cutting edges of a Christmas cutter for roughing or intermediate finishing, or three or five outer cutting edges of a Christmas cutter for finishing. .

  The chip discharge groove is provided linearly so as to incline at a constant inclination angle within a range of 1 ° to 8 ° with respect to the axis S in the direction opposite to the tool rotation direction as viewed from the shank side. When cutting by rotating clockwise when viewed from the side, the chip discharge groove is provided so as to incline in the left direction from the front to the front. Further, when cutting is performed by rotationally driving counterclockwise as viewed from the shank side, the chip discharge groove is provided so as to incline in the right direction from the front toward the front.

  If the inclination angle of the chip discharge groove is smaller than 1 °, there will be no difference from the case of the straight groove, and the effect of improving cutting performance and machining accuracy cannot be obtained sufficiently. Or the falling of the groove increases or the cutting resistance increases, and the effect of improving the cutting performance and processing accuracy cannot be obtained sufficiently. That is, if the inclination angle is not within the range of 1 ° to 8 °, the effect of improving the cutting performance and machining accuracy cannot be appropriately obtained as compared with the straight groove or the twisted groove, and the range of about 3 ° to 5 °. The inside is desirable.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram illustrating a finishing Christmas cutter 10 according to an embodiment of the present invention, and FIG. 6 is a diagram illustrating an intermediate finishing Christmas cutter 30, both of which are illustrated in FIG. ) And (c) for cutting the tree-shaped groove 50 on the workpiece 52. The workpiece 52 is used for testing, and is actually used when machining the tree-shaped groove 50 with respect to a rotating shaft such as a turbine shaft. Each of the Christmas cutters 10 and 30 is driven to rotate about the axis S while being moved relative to the workpiece 52 in a direction perpendicular to the axis S, so that the Christmas cutters 10 and 30 are centered on the groove like an inverted Christmas tree. A tree-shaped groove 50 that is symmetrical to the left and right and that is narrower toward the groove bottom while increasing or decreasing in the groove depth direction, the diameter dimension corresponding to the change in the groove width is the tool tip side. A plurality of outer peripheral cutting edges 18 and 38 that are gradually reduced in diameter while increasing / decreasing in three peaks and three valleys as they go to are provided. The finishing Christmas cutter 10 performs finishing processing with a predetermined finishing allowance (for example, 0.3 mm) on the tree-shaped groove 50 formed by the intermediate finishing Christmas cutter 30. As shown in FIG. 7, the diameter dimensions of 18, 38, that is, the rotation trajectory shape (corresponding to the machining shape) are different by the finishing allowance, and the tree-shaped groove 50 is also different in the groove width dimension by the finishing allowance.

  FIG. 1A is a front view of the finishing Christmas cutter 10 as seen from a direction perpendicular to the axis S, and FIG. 1B is an enlarged view of the blade 14 of the Christmas cutter 10. Fig. 3 (c) is a cross-sectional view of IC-IC in (b). The Christmas cutter 10 is integrally provided with a shank 12 and a blade portion 14, and the blade portion 14 has an inverted Christmas tree shape corresponding to the concavo-convex shape of the tree-shaped groove 50 to be machined. The diameter is gradually made smaller with increasing and decreasing smoothly as it goes downward (downward in the figure). The blade portion 14 is provided with four chip discharge grooves 16 at equiangular intervals around the axis S, and four outer peripheral cutting edges 18 along the chip discharge groove 16 and the outer peripheral cutting edges 18. The bottom blade 20 is provided continuously. The outer peripheral cutting edge 18 and the bottom cutting edge 20 are cut by rotating the Christmas cutter 10 clockwise when viewed from the shank 12 side (above in FIGS. 1 (a) and 1 (b)). The chip discharge groove 16 is linearly provided so as to incline to the left with a constant inclination angle θ1 within the range of 1 ° to 8 ° with respect to the axis S. Thus, since the chip discharge groove 16 is provided at a constant inclination angle θ1, the rake angle γ1 in the cross section perpendicular to the axis S of the outer peripheral cutting edge 18 continuously changes in the axial direction. ing. The rake angle γ1 also varies depending on the diameter of the outer peripheral cutting edge 18.

  6A is a front view in which a part of the Christmas cutter 30 for intermediate finishing is viewed from a direction perpendicular to the axis S, and FIG. 6B is an enlarged view of the outer peripheral cutting edge 38. c) is an enlarged view of the VIC-VI cross section in (a). The Christmas cutter 30 is integrally provided with a shank 32 and a blade portion 34, and the blade portion 34 has an inverted Christmas tree shape corresponding to the concavo-convex shape of the tree-shaped groove 50 to be machined. The diameter is gradually made smaller with increasing and decreasing smoothly as it goes downward (downward in the figure). The blade portion 34 is provided with three chip discharge grooves 36 at equiangular intervals around the axis S, and the three outer peripheral cutting edges 38 and the outer peripheral cutting edges 38 along the chip discharge grooves 36. A bottom blade 40 that is continuous is provided. The three outer peripheral cutting edges 38 are composed of roughing cutting edges whose diameters are finely increased or decreased by providing fine corrugations on the flank and whose corrugated phases are shifted from each other. ing. The outer peripheral cutting edge 38 and the bottom cutting edge 40 are provided so as to perform cutting by rotating the Christmas cutter 30 clockwise when viewed from the shank 32 side (upper side in FIG. 6A). The waste discharge groove 36 is linearly provided so as to incline to the left with a constant inclination angle θ2 within a range of 1 ° to 8 ° with respect to the axis S. Since the chip discharge groove 36 is thus provided at a constant inclination angle θ2, the rake angle γ2 in the cross section perpendicular to the axis S of the outer peripheral cutting edge 38 changes continuously in the axial direction. Yes. The rake angle γ2 also varies depending on the diameter of the outer peripheral cutting edge 38. The inclination angle θ2 may be the same as or different from the inclination angle θ1.

  Here, like the chip discharge grooves 16 and 36, the left inclined groove 60 inclined leftward with respect to the axis S at a constant inclination angle θ is, for example, as shown in FIG. The grinding wheel 62 that is driven to rotate around the axis O is arranged in a predetermined posture with respect to the axis S of the tool material 64 (in the drawing, the posture is inclined at substantially the same angle as the inclination angle θ with respect to the axis S). In addition, the tool material 64 can be formed by linearly moving in a direction C (direction indicated by a hollow arrow) C parallel to the inclination angle θ. The lower cross-sectional view of FIG. 2 (c) is a cross-sectional view taken along the line II-II after the four left inclined grooves 60 are processed. On the other hand, the straight groove 66 parallel to the conventional shaft center S arranges the grinding wheel 62 substantially parallel to the shaft center S and the tool material 64 to the shaft center S as shown in FIG. It is formed by relatively linearly moving in the parallel direction A. Further, the twist groove 68 twisted clockwise around the axis S with a predetermined twist angle λ has a predetermined twist angle λ with respect to the axis S with respect to the grinding wheel 62 as shown in FIG. The tool material 64 is arranged in a posture inclined at substantially the same angle, and is rotated by rotating around the axis S while relatively moving the tool material 64 in a direction B parallel to the axis S. In this case, the groove cross section of the straight groove 66 of (a) and the left inclined groove 60 of (c) is a shape corresponding to the cross-sectional shape of the grinding portion of the grinding wheel 62, although it differs depending on the posture of the grinding wheel 62. The cross-sectional shapes approximate to each other. On the other hand, the cross-sectional shape of the twisted groove 68 of (b) is different from the cross-sectional shape of the grinding wheel 62 due to the interference of the grinding wheel 62 and is greatly different from the cross-sectional shapes of the straight groove 66 and the left inclined groove 60. To do. Further, FIG. 2 is for explaining the difference between the conventional straight groove 66 and the twisted groove 68 and the left inclined groove 60, and the tool material 64 has a cylindrical shape with a fixed diameter.

  The straight groove 66 (a) and the twisted groove 68 (b) are formed with a constant groove cross-sectional shape in the axial direction when the outer diameter of the tool material 64 is constant, and are perpendicular to the axis S. Although the rake angle of the cross section is constant, the groove shape of the left inclined groove 60 in (c) changes continuously in the axial direction. FIG. 3 is a diagram for explaining the change in the groove cross-sectional shape of the left inclined groove 60. (b), (c), and (d) are front end views as viewed from IIIB-IIIB in FIG. 3A and IIIC-IIIC, respectively. In the cross-sectional views and IIID-IIID cross-sectional views, the longer the distance from the tip, the narrower the groove width, and the rake angles thereof have a relationship of γb> γc> γd. In FIG. 3, the rake angle γd is negative. The alternate long and short dash line shown in (d) shows the groove shape in (b) for comparison, and the difference in groove width is clear.

Comparing the characteristics of the straight groove 66, the twisted groove 68, and the left inclined groove 60, the groove sectional shape of the twisted groove 68 is such that the grinding wheel 62 is relatively moved along the lead of the twisted groove 68. Causes the rake face to be hooked (curved). Further, when there is no change in the groove bottom diameter ratio in the square blade type, that is, when the tool material 64 has a constant outer diameter, the rake angle and the outer peripheral blade thickness are not changed. The cutting edge length becomes longer than the cutting edge length, and the outer peripheral cutting edge contact length when using the tool gradually becomes maximum and gradually becomes minimum.
As for the cross-sectional shape of the straight groove 66, the shape of the grinding part of the grinding wheel 62 is transferred as it is, so that the rake face is not hooked. When there is no change in the groove bottom diameter ratio in the square blade type, that is, when the outer diameter of the tool material 64 is a constant cylindrical shape, there is no change in the rake angle and the outer peripheral blade thickness. The cutting edge length is equal to the cutting edge length, and the outer peripheral cutting edge contact length when using the tool is instantaneously maximized and instantaneously minimized. Accordingly, the cutting resistance changes greatly periodically.
As for the cross-sectional shape of the left inclined groove 60, the shape of the grinding part of the grinding wheel 62 is transferred as it is, so that the rake face is not hooked. When there is no change in the groove bottom diameter ratio with the square blade type, that is, even when the outer diameter of the tool material 64 is constant, the rake angle and outer peripheral blade thickness change depending on the axial position, and the distance from the tool tip As the length increases, the rake angle decreases and the outer peripheral blade thickness increases. For this reason, the inclination angle θ is limited by the blade diameter, the blade length, the groove bottom diameter, and the like. The cutting edge length becomes longer than the cutting edge length, and the outer peripheral cutting edge contact length when using the tool gradually becomes maximum and gradually becomes minimum.
That is, the left inclined groove 60 has a groove cross-sectional shape close to that of the straight groove 66 and high machining accuracy can be expected. On the other hand, fluctuations in the outer peripheral cutting edge contact length when using a tool have characteristics close to that of the twisted groove 68 and Improvement of cutting performance can be expected.

  FIG. 4 shows a rake of peaks and valleys having different diameters in the case of the left inclined groove 60, the straight groove 66, and the twisted groove 68 for the two-crest and two-valley Christmas cutters having different diameter dimensions. It is a figure explaining the result of having calculated the angle concretely, About the left inclination groove | channel 60, the inclination angle (theta) investigated 2 types, 1 degree of left, and 8 degrees of left. The twisted groove 68 was examined when the twist angle λ was 5 ° to the right. When the diameter dimension of the tool material 64 is constant, the rake angles γb, γc, and γd are different in the left inclined groove 60 as shown in FIG. 3, whereas the rake angle is constant in the straight groove 66 and the twist groove 68. However, when the diameter dimension is changed as in a Christmas cutter, as is apparent from the result of FIG. 4, any of the left inclined groove 60, the straight groove 66, and the twisted groove 68 is raked due to the change in the diameter dimension. The angle changes greatly. However, this excludes when the straight groove 66 has a rake angle of 0 °.

  The results shown in FIG. 4 were calculated so that the average of the rake angles at one and two peaks was constant (here, 8 °) so that the influence of the change in the rake angle was as small as possible. Focusing on the rake angle of one small ridge and valley where the cutting speed is small when the Christmas cutter is actually used, in the case of the left inclined groove 60 ((b) and (c) in FIG. 4), the twist The rake angle can be set at a stronger angle than the groove 68 (FIG. 4 (d)), and the cutting performance can be expected to improve at a small crest and trough with a small cutting speed.

  Next, the product of the present invention having a left inclined groove (chip discharge groove) in which the inclination angles θ1, θ2 are in the range of 1 ° to 8 °, a comparative product having inclination angles θ1, θ2 larger than 8 °, a straight groove, Using a conventional product with a right-handed twist groove, the tree-shaped groove 50 is cut under the cutting conditions shown in FIG. 5 (a), and the cutting performance and processing accuracy shown in (b) and (c) are shown. The results of the investigation will be described. SNCM439 in the column of “Machining material” in FIG. 5A is a nickel chrome molybdenum steel material according to JIS regulations. In addition, the intermediate finishing process shown in FIG. 5B is a three-blade intermediate finishing process in which a roughing cutting edge is provided in the same manner as the Christmas cutter 30 on a solid workpiece 52 without a lower groove or the like. When the tree-shaped groove 50 is cut using a conventional Christmas cutter, “0 ° tilt (straight groove)” and “right 5 ° twist” are the conventional Christmas cutters, “left 3 ° tilt” and “left 5”. “Inclination” is a product of the present invention (Christmas cutter 30) with an inclination angle θ2 of 3 ° and 5 °, and “Left 10 ° inclination” is a comparative product with an inclination angle θ2 = 10 °. The finishing process of FIG. 5 (c) is the same as that of the Christmas cutter 10 with respect to the tree-shaped groove 50 that has been subjected to the intermediate finishing process according to the product of the present invention having the “left 3 ° inclination”, which has the highest processing accuracy in the intermediate finishing process. In the case of finishing cutting at a finishing allowance of 0.3 mm using a 4-blade finishing Christmas cutter configured similarly, “0 ° tilt (straight groove)” is the conventional Christmas cutter, “Left 3 “Inclination of 5 °” and “Inclination of 5 ° to the left” are products of the present invention (Christmas cutter 10) having an inclination angle θ1 of 3 ° and 5 °, and “Inclination of 10 ° to the left” are comparative products having an inclination angle of θ1 = 10 °. In the finishing process, a Christmas cutter with a twisted groove has not been used so far, so it was omitted in this test.

  In the column of “vibration”, “cutting sound” and “machined surface” in FIG. 5 (b) above, the evaluation “◎” is good, “◯” is slightly good, “△” is normal, “×” is bad, In the sensory evaluation by the examiner's visual or auditory sense, relative evaluation was made based on the conventionally used “right 5 ° twist”. The same applies to “vibration” and “cutting sound” in FIG. 5 (c), but in this case, relative evaluation was made based on “0 ° inclination (straight groove)”. The reason why the evaluation of “0 ° inclination (straight groove)” is “△” is that it is worse than the case of “right 5 ° twist” which is the standard in the intermediate finishing of (b).

  In addition, the “groove collapse amount” in FIGS. 5B and 5C is an average value of the displacement amounts ΔX1 and ΔX2 shown in FIG. 8A, and the tilt toward the up-cut side shown in FIG. It was. The tree-shaped groove 50 in FIG. 8 (a) is a simplified view with the groove irregularities omitted. “Processing expansion amount” is the difference between the groove width and tool diameter shown in FIG. 8B (groove width−tool diameter), and was measured at the maximum valley diameter portion as shown in the figure. The “cutting resistance” is obtained by measuring the displacement of the main component force Fx, the feed component force Fy, and the back component force Fz shown in FIG. 8C with a three component force meter, and using the resultant force F as a cutting resistance. Calculated. In any case, the values were obtained in the machining stable region excluding the beginning of contact of the tool with respect to the workpiece 52 and the time when the tool was removed.

  And, as is clear from the test results shown in FIG. 5 (b), the Christmas cutter for intermediate finishing processing according to the product of the present invention of “left 3 ° inclination” and “left 5 ° inclination” The vibration, cutting sound, and cutting performance of the machined surface are all improved compared to the conventional product of “0 ° inclination (straight groove)”, and the result is equal to or better than the conventional product of “5 ° right twist”. was gotten. Regarding the cutting resistance, according to the products of the present invention of “Left 3 ° Inclination” and “Left 5 ° Inclination”, it was less than half in 43% to 46% of the conventional product of “0 ° inclination (straight groove)”. . Even compared with the “right 5 ° twist”, it was reduced by about 13% to 20%. Regarding the processing accuracy of the groove collapse amount and the processing enlargement amount, according to the products of the present invention of “left 3 ° inclination” and “left 5 ° inclination”, “0 ° inclination (straight groove)” and “right 5 ° twist” Better results were obtained than any of the conventional products. Compared with the conventional product of “Left 10 ° tilt”, compared to the conventional product of “Right 5 ° twist”, the machining expansion amount and cutting resistance are improved, but the machining surface and the groove collapse amount are slightly deteriorated. A sufficient performance improvement effect could not be obtained.

  As is clear from the test results shown in FIG. 5C, with respect to the Christmas cutter for finishing, according to the products of the present invention of “left 3 ° inclination” and “left 5 ° inclination”, vibration and cutting noise were obtained. Regarding the cutting performance of the processed surface roughness, the result was similar to or better than the conventional product of “0 ° inclination (straight groove)”. The cutting resistance is also 59% to 71% of the conventional product of “0 ° inclination (straight groove)” according to the present invention products of “left 3 ° inclination” and “left 5 ° inclination”, which is about 2/3. Reduced to With respect to the machining accuracy of the groove collapse amount and the machining enlargement amount, according to the products of the present invention of “left 3 ° inclination” and “left 5 ° inclination”, it is better than the conventional product of “0 ° inclination (straight groove)” Results were obtained. The comparative product of “Left 10 ° Inclination” improves the cutting sound, the amount of processing expansion, and the cutting resistance compared to the conventional product of “0 ° Inclination (straight groove)”, but the machining surface roughness and groove collapse amount are “0”. It was rather worse than the conventional product of “° inclination (straight groove)”, and a sufficient performance improvement effect could not be obtained.

  As described above, according to the Christmas cutters 10 and 30 of the present embodiment, the chip discharge grooves 16 and 36 are 1 ° to 8 ° with respect to the axis S in the direction opposite to the tool rotation direction viewed from the shank 12 or 32 side. Since it is provided linearly so as to incline at a constant inclination angle θ1, θ2 within the range, the amount of groove collapse, the amount of processing expansion, and the cutting resistance are reduced compared to the conventional products of straight grooves and twisted grooves. It was. In addition, vibration, cutting sound, and machined surface were improved as compared with the straight groove, and the same or better results were obtained when compared with the twisted groove. Thus, the cutting performance is improved as a whole, and excellent machining accuracy can be obtained, so that it is possible to perform further highly efficient machining.

  When machining the chip discharge grooves 16 and 36, the grinding wheel 62 that is driven to rotate about the axis O is used as the axis S of the tool material 64 in the same manner as the left inclined groove 60 shown in FIG. In contrast, the tool material 64 is disposed in a posture that is inclined at substantially the same angle as the predetermined inclination angles θ1 and θ2, and the tool material 64 is relative to a direction parallel to the inclination angles θ1 and θ2 (the direction of arrow C in FIG. 2C). In order to process the chip discharge grooves 16 and 36 as compared with the case where the tool material 64 is rotated around the axis S and moved relative to the axial direction as in the case of the twisted groove 68, it is only necessary to move it linearly. This device is simple and inexpensive, and since there is no change in the shape of the groove cross section due to interference grinding, the groove cross section shape can be easily set.

  In addition, with respect to the Christmas cutter 30 for intermediate finishing, since the tilting of the groove and the amount of expansion of processing are improved, it is possible to perform intermediate finishing with dimensions closer to the final dimensions, and cutting during finishing By reducing the size (finishing allowance), it becomes possible to perform more stable and accurate finishing. In other words, the mid-finishing Christmas cutter generally employs a twisted groove (twisted blade) 68 that is twisted around the axis S with emphasis on cutting performance, but the inclined type chip discharge groove 36 of the present embodiment. According to this, it was possible to improve machining accuracy while maintaining cutting performance such as sharpness. In addition, since it has three blades, it is possible to provide a chip discharge groove 36 having a relatively large groove cross section, and the chip discharge performance is improved, and the cutting resistance is also reduced in this respect.

  About the Christmas cutter 10 for finishing, since the fall of a groove | channel and the amount of process expansion are improved, finishing can be performed with higher dimensional accuracy. That is, the Christmas cutter 10 for finishing machining emphasizes machining accuracy and generally employs a straight groove (straight blade) 66 parallel to the axis S, but the tilt type chip discharge groove 16 of this embodiment is used. According to this, since the vibration and cutting resistance are reduced by improving the cutting performance such as sharpness, the processing accuracy can be further improved. Further, since it has four blades, the outer peripheral cutting edge 18 simultaneously contacts both side surfaces of the tree-shaped groove 50 of the workpiece 52 to stabilize the tool posture. Machining accuracy is improved.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention is implemented in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

10, 30: Christmas cut capacitor 16, 36: chip discharge grooves 18 and 38: outer peripheral cutting edge 50: Tree-shaped groove 52: workpiece S: axial .theta.1, .theta.2: inclination angle

Claims (3)

With the peripheral cutting edge is provided along the chip discharge grooves, by being moved relative to the axis S and perpendicular to the workpiece while being rotated around the axis S, the inverse Christmas tree In order to cut a tree-shaped groove that is symmetrical with respect to the groove center and that is narrower toward the groove bottom side while increasing or decreasing the groove width in the groove depth direction, In the Christmas cutter that is gradually reduced in diameter while increasing and decreasing as it goes to the tool tip side in response to the change in width ,
The chip discharge groove is linearly provided so as to incline at a constant inclination angle within a range of 1 ° to 8 ° with respect to the axis S in a direction opposite to the tool rotation direction seen from the shank side. A Christmas cutter characterized by that. The outer peripheral cutting edge has a corrugated shape in which the diameter dimension is smaller than the desired groove width width and is finely increased and decreased, and the plurality of outer peripheral cutting edges are out of phase with each other. The Christmas cutter according to claim 1, wherein the Christmas cutter is used for roughing or intermediate finishing with a luffing cutting edge. 2. The Christmas cutter according to claim 1, wherein the outer peripheral cutting edge has a diameter that is substantially the same as a groove width dimension of a target groove shape, and is used for finishing. 3.

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