JP2004209559A - End mill with back taper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an end mill, in which its tip end corners and outside peripheral edges are difficult to break, and by which the roughness of a finished surface is improved. <P>SOLUTION: The end mill uses a radius end mill having a corner radius R of at least 0.2 mm at a tip end round corner 5, an end mill having a chamfering cutting edge C of at least 0.2 mm at a tip end corner, or an end mill having a flat end cutting edge 1 or an end cutting edge having a concave angle, which end cutting edge is formed instead of a ball cutting edge after removing the tip end of the ball cutting edge. At this time, a back taper θ not smaller than 0.2° and smaller than 3° is given within the region from the outer end portion of the tip end round corner R, the chamfering cutting edge C, or the ball cutting edge of the end mill, or the neighborhood of the outer end portion to the rear end of flutes 3. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an end mill with a back taper that improves machining accuracy and tool life in helical machining.
[0002]
[Prior art]
Conventional examples of end mills that perform helical machining include those disclosed in the following patent documents.
[0003]
[Patent Document 1]
Japanese Patent Publication No. 6-4205 [Patent Document 2]
JP-A-3-88620 [Patent Document 3]
Japanese Patent Application Laid-Open No. 2002-29514 [Patent Document 4]
Japanese Patent Application Laid-Open No. 2002-292515
Among these, the end mill of Patent Document 1 is provided with a radial cutting edge formed of a throwaway tip at the front end of the main body, and the cutting edge assumes that the direction in which the inner end side retreats from a line perpendicular to the tool axis is negative. It has a front cutting edge angle (watermark angle) of -5 to -15 ° and a back taper of 0 to 1 ° on the outer peripheral portion.
[0005]
The end mill of Patent Document 2 has a blade portion and a blade portion integrally, and the blade portion has a cutting edge at a tip, and a side blade and a groove extending spirally from the cutting edge toward a rear end. The diameter is gradually reduced from the front end to the rear end, and both outer ends of the cutting edge form the most protruding acute angle of the front end of the blade portion.
[0006]
The end mill of Patent Literature 3 is a small-diameter contour end cutting radius end mill having an outer peripheral blade, a bottom blade having a middle-low gradient, and a blade portion formed with a corner R blade at a connecting portion between the outer peripheral blade and the bottom blade. The outer peripheral edge is formed so as to have a reverse taper (back taper) with one angle of 3 ° to 30 °.
[0007]
Furthermore, the end mill of Patent Document 4 is for cutting small-diameter contour lines, has a blade portion having an outer peripheral blade and a bottom blade, and a connecting portion between the outer peripheral blade and the bottom blade has a straight line perpendicular to the tool axis. The reverse gradient blade has an angle of 5 to 30 [deg.] With a straight line perpendicular to the tool axis in a direction opposite to the gradient toward the rotation center of the bottom blade.
[0008]
[Problems to be solved by the invention]
In the helical machining, as shown in FIG. 7, the end mill E is spirally moved while being rotated, and holes and grooves formed in the work W are dug.
[0009]
The end mill of Patent Document 1 is a throw-away type and has a sharp tip corner, so that the feed mark (M in FIG. 8) attached to the side surface of the hole or groove processed in the helical processing increases. Processing accuracy deteriorates.
[0010]
The end mill of Patent Document 2 is also a square end mill having a sharp tip corner, and therefore has the same problem as described above. In addition, this end mill is liable to chip at the tip corner.
[0011]
In the end mills of Patent Documents 3 and 4, since the back taper is too large, the diameter decreases at the end of the groove, and the tool rigidity decreases. Further, although not as much as the end mills of Patent Documents 1 and 2, a feed mark remains on the processing side surface.
[0012]
It is an object of the present invention to solve this problem and improve the quality of a machined surface in helical machining, and to further improve the life and the like by suppressing wear and chipping due to use.
[0013]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, in the present invention, a radius end mill having a tip corner R of 0.2 mm or more, an end mill with a chamfering blade having a chamfering blade of C0.2 or more at a tip corner portion, or a ball blade ( The end mill with a flat bottom blade or a bottom blade having a bottom angle with a water mark is formed by removing the top of the spherical bottom blade and instead forming a flat bottom blade or a bottom edge with a water mark. A back taper of not less than 0.2 ° and less than 3 ° was provided at the outer end portion or a portion from the vicinity of the outer end portion to the rear end of the groove.
[0014]
The end mill of the present invention is limited to a solid or brazing type. The material of the cutting blade is not limited to a cemented carbide, an ultra-high pressure sintered body, and a high-speed steel.
[0015]
The end mill according to the present invention has a straight side blade having a length of 10 mm or less and a back taper of 0.1 ° or less between an outer end portion of the tip corner R, a C chamfering blade or a ball blade and a start end of the back taper applying portion. Alternatively, it is preferable to provide a large arc-shaped side blade whose center having a length of 10 mm or less is located outside the end mill. The side edge referred to here is an outer edge, but is referred to as a side edge to distinguish it from the outer edge of the back taper providing portion.
[0016]
In addition, an outer peripheral edge is formed in the back taper applying portion, and the outer peripheral edge is provided with a margin having a width of 0.02 mm or more, an outer peripheral edge of the back taper applying portion is omitted, and a side edge is 0.02 mm. As described above, those having a margin of 0.3 mm or less and those having a through hole for supplying a cutting fluid or air at the axis thereof can be cited as preferable embodiments.
[0017]
[Action]
In the end mill of the present invention, since the corner R, the C chamfer, or the R of the ball blade is provided, the tip corner portion is strengthened and is not easily chipped.
[0018]
Further, since the outer periphery is provided with a back taper, it is possible to prevent adverse effects due to a blade not involved in cutting during helical machining being rubbed against the finished surface, for example, deterioration of the finished surface and tool wear.
[0019]
Further, when processing is performed by feeding in the axial direction with a square end mill with a back taper, a large feed mark M remains on the side surface of the processed hole or groove, as shown in FIG. 8, and the finished surface has poor surface roughness. However, when the corner R is added to the cutting edge, the feed mark M becomes small as shown in FIG. 9, and the finished surface quality can be improved.
[0020]
A straight side blade with a length of 10 mm or less and a back taper of 0.1 ° or less, or a large arc side blade with a center of 10 mm or less located outside the end mill, has a tool axial feed amount of 10 mm or less. When the helical machining is performed under the conditions, the wiper effect by the side blade is obtained, and the feed mark is reduced, and the finished surface roughness of the side surface of the hole or groove to be machined is improved.
[0021]
In addition, in the case where a margin is provided on the outer peripheral edge of the back taper applying portion, the effect of strengthening by the margin is obtained, and an effect of preventing the outer peripheral edge from being lost due to biting of chips or so-called chatter of a tool is generated.
[0022]
In the case where the outer peripheral edge of the back taper applying portion is eliminated, there is no fear of the outer peripheral edge being damaged.
[0023]
When the side edge is provided with a margin, a guide effect is generated by the margin, so that chatter of the tool during machining is reduced, and cutting stability is enhanced.
[0024]
In addition, although machining by an end mill is usually performed by an external lubrication method, when digging a hole or a groove by helical processing, the cutting oil hardly reaches a cutting portion by external lubrication. On the other hand, those provided with through holes in the shaft center can be machined by internal lubrication, so that the lubrication and cooling of the cutting edge can be reliably performed. In addition, since chips can be forcibly discharged using the flow of the supplied oil or air, roughening of the processing surface and processing trouble due to chip clogging are reduced.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an end mill of the present invention will be described with reference to the accompanying drawings. In addition, all end mills other than FIG. 1 are shown in a schematic diagram.
[0026]
FIG. 1 shows a radius end mill having a round corner 5 at the tip. The corner R of the round corner 5 shown in the schematic diagram of FIG. 1B is set to 0.2 mm or more. If this corner R is 0.2 mm or less, the effect of strengthening the corner is insufficient.
[0027]
In FIG. 1A, 1 is a bottom blade, 2 is an outer peripheral blade, 3 is a groove, and 4 is a margin of the outer peripheral blade 2. If the width W1 of the margin 4 (see FIG. 1 (c), the dashed-dotted line is a blade shape without margin) is less than 0.02 mm, the strength is insufficient, and the effect of strengthening the outer peripheral blade cannot be expected. Therefore, the width is set to 0.02 mm or more. In this end mill, a portion from the outer end of the round corner 5 to the rear end of the groove 3 has a back taper θ of 0.2 ° or more and 3 ° or less.
[0028]
If the back taper θ is less than 0.2 °, the outer peripheral edge that is not involved in cutting during helical machining rubs the finished surface, thereby deteriorating the properties of the machined surface and increasing the rubbing wear of the tool. If the back taper θ is 3 ° or more, the tool rigidity decreases, and chatter during machining is likely to occur. According to Patent Document 3 mentioned above, if the back taper is less than 3 °, the contact length between the side blade and the finished surface becomes long, so that the tool becomes easy to chatter (page 3, lower right column 0011). Since the allowance in the tool axis direction (= the axial feed amount during one revolution of the tool) is smaller than the allowance in the tool radial direction, chatter due to contact with the workpiece is less likely to occur. Rather, when the angle is 3 ° or more, the diameter at the rear end of the groove 3 becomes smaller, and the tool stiffness is reduced and chatter is more likely to occur.
[0029]
FIG. 2 shows an end mill with a chamfered blade provided with a chamfered blade 6 of C0.2 or more at a corner portion at the tip. This end mill also has a back taper .theta. On the outer periphery of a portion from the outer end of the chamfering blade 6 to the rear end of a groove (not shown). The chamfering amount of the chamfering blade 6 is set to 0.2 mm or more for the same reason as the round corner 5 in FIG. The back taper θ is set to 0.2 ° or more and 3 ° or less for the same reason as in the end mill of FIG. Also in this end mill, it is preferable that a margin (4 in FIG. 1) having a width W1 of 0.02 mm or more is provided on the outer peripheral edge 2 provided in the back taper applying portion.
[0030]
FIG. 3 shows an end mill with a bottom blade in which the tip of the ball blade 7 of the ball end mill is removed and a flat bottom blade 8 or a bottom blade having a watermark angle is provided instead. Is provided with a back taper .theta. On the outer periphery of a portion extending from the outer end to the rear end of a groove (not shown). The back taper θ is not less than 0.2 ° and not more than 3 ° for the same reason as that of the end mill of FIG. 1, and the outer edge 2 provided in the back taper applying portion has a margin having a width of not less than 0.02 mm (FIG. 1). 4) is attached.
[0031]
FIG. 4 shows the back end between the outer end of the round corner 5 of the radius end mill (the corner R is 0.2 mm or more) and the start end a of the portion having a back taper θ of 0.2 ° or more and 3 ° or less. A straight side blade 9 shown in FIG. 4B having a taper angle of 0.1 ° or less, and a large arc side blade 10 whose center O is outside the end mill shown in FIG. 4C are provided. .
[0032]
The side blade 9 (10) can be provided in the end mill with a chamfered blade in FIG. 2 and the end mill with a bottom blade in FIG. FIG. 5 shows an example in which the side blade 9 is provided in the end mill with a bottom blade shown in FIG. The side blade 9 (10) is preferably provided with a margin 11 (see FIG. 4D) having a width of 0.02 mm or more and 0.3 mm or less. When the margin width is less than 0.02 mm, the strength of the side blade becomes insufficient, and when it exceeds 0.3 mm, the cutting resistance increases and the work becomes easy to chatter.
[0033]
If the side blades 9 and 10 described here are provided, the side blades function as wiper blades during helical machining (there is no effect if the feed amount in the tool axis direction exceeds 10 mm during one revolution of the end mill. The feed marks attached to the side surfaces of the holes and grooves during the preceding machining are scraped off at the next and subsequent machining, thereby improving the surface roughness of the finished surface.
[0034]
In the end mill having the side blades 9 and 10 described here, the outer peripheral blade of the back taper applying portion can be omitted. It is of course possible to attach the outer peripheral edge, but when attaching the outer peripheral edge, it is preferable to use an outer peripheral edge having a margin of 0.02 mm or more in order to strengthen the edge.
[0035]
FIG. 6 shows an end mill in which a through hole 12 is provided in a shaft center portion. The configuration excluding the through hole 12 is the same as that shown in FIGS. When the through hole 12 is provided, cutting oil and air can be efficiently supplied to the processing point by using an internal oil supply and an internal air supply method, and further, chips can be forcibly discharged by a returning liquid flow or air flow. Processing troubles due to wear and clogging of chips can be reduced.
[0036]
【The invention's effect】
As described above, in the end mill of the present invention, since the tip corner is strengthened, chipping of the corner in helical machining is reduced. A back taper that is not too small and not too large is attached to the outer circumference to prevent the outer blade from contacting the finished surface, which reduces the deterioration of the finished surface and the abrasion of the tool, and reduces the surface roughness of the machined surface. The purpose of improvement and tool life improvement is achieved.
[0037]
In the case of having a side blade of 10 mm or less, the feed mark on the side surface of the hole or groove processed by the helical processing due to the wiper effect is reduced, and the surface roughness of the finished surface is improved.
[0038]
In addition, when the outer peripheral edge is provided with a margin, chipping of the outer peripheral edge and loss of the outer peripheral edge due to chatter are reduced.
[0039]
Further, with the side edge having a margin, the chatter of the tool is suppressed, and the stability of machining is improved.
[0040]
In addition, those with a through hole in the shaft center can efficiently supply cutting oil and air to the processing point, improve tool life, suppress roughening of the processing surface due to clogging of chips, and suppress processing trouble. .
[Brief description of the drawings]
1A is a side view showing an embodiment of an end mill of the present invention. FIG. 1B is a schematic view of the end mill of the embodiment. FIG. 1C is a sectional view of an outer peripheral blade. FIG. 2 is a schematic view of another embodiment. FIG. 4 (a) is a schematic view of still another embodiment, FIG. 4 (b) is a schematic view of the end mill of the same embodiment, and FIG. 4 (c) is an enlarged schematic view of the end side of the end mill. d) Cross-sectional view of the side blade [Fig. 5] Schematic diagram of still another embodiment [Fig. 6] Schematic diagram of still another embodiment [Fig. 7] Explanatory diagram of helical machining [Fig. 8] Processed by helical machining Diagram showing exaggerated feed marks attached to the side surfaces of holes and grooves [FIG. 9] Diagram showing the reduced number of feed marks due to removal of tip corners [Description of reference numerals]
DESCRIPTION OF SYMBOLS 1 Bottom blade 2 Perimeter blade 3 Groove 4 and 11 Margin 5 Round corner 6 Chamfering blade 7 Ball blade 8 Flat bottom blade 9 Straight side blade 10 Large circular side blade 12 Through hole θ Back taper M Feed mark

Claims (6)

A radius end mill with a corner R at the tip of 0.2 mm or more, an end mill with a chamfer blade with a C 0.2 or more chamfer at the tip corner, or a flat bottom blade or a watermark instead of removing the tip of a ball blade For an end mill with a bottom blade having a bottom edge with a corner, the end corner R of the end mill, the chamfering blade or the outer end of the ball blade or a portion from the vicinity of the outer end to the rear end of the groove. A solid or brazed end mill with a back taper characterized by having a back taper of 0.2 ° or more and less than 3 °. Between the outer edge with the tip corner R, C chamfering blade or ball blade and the beginning of the back taper imparting portion, a straight side blade with a length of 10 mm or less, a back taper of 0.1 ° or less, or a length of 10 mm or less 2. A back tapered end mill according to claim 1, further comprising a large arc-shaped side blade whose center is located outside the end mill. 3. The end mill according to claim 1, wherein an outer peripheral edge is formed in the back taper applying portion, and the outer peripheral edge is provided with a margin having a width of 0.02 mm or more. 3. The end mill according to claim 2, wherein an outer peripheral edge of the back taper applying portion is omitted. The end mill with a back taper according to any one of claims 2 to 4, wherein a margin of a width of 0.02 mm or more and 0.3 mm or less is provided to the side blade. The end mill with a back taper according to any one of claims 1 to 5, wherein a through hole for supplying a cutting fluid or air is provided at the shaft center.

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