JPH01321108A - Machining tool with small relief - Google Patents

Abstract

PURPOSE:To prevent a cutting edge from chipping when an are concerned and hinder fusion deposition of machined material when a reamer is used, by forming No.1 secondary taking surface having a specified run-off angle and width behind the cutting edge, and behind it forming No.2 secondary taking surface having a greater run-off angle. CONSTITUTION:The wall facing in the rotating direction of a twisted groove 13 constitutes a scooping face 14, and a cutting edge 15 is formed on the peripheral ridge, and behind it a small relief 19 is formed composed of a margin 16, No.1 secondary taking surface 17, and No.2 secondary taking surface 18. The margin width T shall be below 0.05mm with the machine material prevented from fusion deposition, and the run-off angle alpha of No.1 secondary taking surface 17 be 1-5 deg. to prevent secondary touch with possibility of high feed, and the width of No.1 run-off surface 17 is added to the margin width T with the run-in width W ranging 0.05mm thru 0.5mm so as to prevent drop of the cutter tip strength, which accomplishes prolonged lifetime of the tool without enlarging the wear width relative to the wear depth. The run-off angle beta of No.2 secondary taking surface 18 shall be 8-20 deg. to provide sufficient rigidity of the cutter tip without enlarging the wear width relative to the wear depth. Accordingly the cutter tip strength is increased to cause decrease of chippings as long as an end mill is concerned, while there is a certain wear and vibration so far as a reamer is concerned, however with favorable points involved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cutting tool having a margin such as an end mill, a side cutter, a reamer, a drill, etc.
This invention relates to the improvement of a cutting tool such as a cutting tool that simply has a square corner.

[Prior art and its features] Generally speaking, there are two types of cutting tools: those with a sharp corner immediately on the rear side of the cutting edge, and those with a margin formed on the rear side of the cutting blade.

As an example of the former, in the case of a cutting tool, for example, the cutting edge often breaks off instantly after cutting starts. In addition, for example, in the case of a milling cutter, the cutting blade undergoes intermittent cutting in which impact force is repeatedly applied to the cutting blade, so chipping or breakage of the cutting blade is likely to occur, which often significantly shortens the life of the tool.

Examples of the latter include reamers and end mills. Fig. 6 shows a cross section perpendicular to the cutting edge 1 of a conventional cutting tool having a margin.A margin 2 is formed at a predetermined width at the rear of the cutting edge 1 in the rotational direction. A second chamfered surface 3 with a predetermined clearance angle is formed on the portion.

Here, the margin 2 is formed on a cylindrical curved surface without a second cut, and by slidingly contacting the inner wall surface of the machined hole without digging into it, it prevents chatter vibration of the cutting tool and improves the hole. During machining, it has the function of improving the dimensional accuracy and surface roughness of the machined hole through a burnishing effect.

However, in actual cutting, the margin 2
On the contrary, the presence of such substances may have various adverse effects.

For example, the work material may be welded to the rear part of the margin 2, and this welding may progress and become adhered as deposits 4. Such deposits 4 are almost the same as the wIIIR cutting edge, and are extremely hard and not only cause deep streaks on the inner wall surface of the workpiece, but especially when the cutting tool is a reamer, they can also cause deep scratches into the workpiece. This may cause the reamer to become stuck and become unable to be removed from the workpiece, or in some cases may lead to a breakage accident. Moreover,
As mentioned above, the deposit 4 adhered to the margin 2 is extremely hard and requires a great deal of effort to remove.
Because it is deeply adhered to the fine irregularities of the polished surface of Margin 2, even if it is removed with an oil grindstone, it will stick again when cutting is performed, resulting in product defects and cutting tools. This often causes serious problems such as the inability to use the equipment.

Furthermore, the cutting speed cannot be increased due to significant heat generation due to friction between the margin 2 and the inner wall surface of the workpiece.
Even at normal cutting speeds, heat generation in the margins may not be suppressed depending on the cutting oil.

Here, the reason why the margin 2 has the above-mentioned adverse effect is as follows.

That is, since most of the material to be stiffened is an elastic material, the drilled hole immediately contracts and tightens the cutting tool.

In this case, the compressive force that the margin 2 receives from the rigid material is removed near the cutting edge 1, which is the ridgeline of the margin 2, by the cutting action of the cutting edge 1, but increases toward the rear in the rotational direction. Moreover, cutting oil that cools the workpiece and prevents welding is difficult to reach the margin 2, so it easily generates heat and increases its affinity with the rigid material, and if even a small amount of welding occurs at the margin 2, it will progress rapidly. This causes an adhesion phenomenon.

Furthermore, when cutting by horizontally feeding the workpiece,
Since the margin 2 moves in a trochoidal curve, the above-mentioned problems appear more prominently than when machining is carried out by feeding the tool in the axial direction. For example, cutting allowance 0.2mm/
When machining is performed using rev, the clearance angle of margin 2 with respect to the rigid material will be -33'', and the rear part of margin 2 will be approximately 0.0067 mm ahead of the cutting edge l at the ridge. The compressive force due to the cross-feeding is added to the compressive force due to the contraction of the cut material, and a large compressive force acts on the margin 2.

[Object of the Invention] This invention was made in view of the above circumstances, and can effectively prevent chipping of the cutting edge in a cutting tool having a second corner such as a 7-rice cutter, and can effectively prevent chipping of the cutting edge, etc. It is an object of the present invention to provide a cutting tool having a margin of 1, which can eliminate various troubles by preventing welding and adhesion of workpiece materials to the margin.

[Means for Solving the Problems] The cutting tool of the present invention has a twelfth chamfer surface having a predetermined relief angle formed on the margin or the rear side of the cutting edge, and a twelfth chamfer surface on the rear side of the twelfth chamfer surface. A second chamfer surface having a clearance angle larger than the clearance angle of the twelfth chamfer surface is formed on the twelfth chamfer surface, and the margin width is set to 0.05 mm or less, and the twelfth chamfer surface in a cross-sectional view orthogonal to the margin or the cutting edge. The clearance angle is 1° to 5°, and the clearance width obtained by adding the width of the 12th chamfer to the margin width is 0.05mm to 0.5mm.

[Embodiment] FIGS. 1 to 5 show an embodiment of the present invention, and FIG. 2 is a perspective view showing an end mill. In the figure, reference numeral 1O is the tool body.

The tool body IO has a cylindrical shape that is rotated around an axis, and at its tip, three chip pockets 11 extending from the axis toward the outer circumference are formed at equal intervals in the circumferential direction. A cutting edge 12 is formed at the tip ridgeline of the wall surface of each chip pocket 11 facing the rotation direction. Furthermore, three twisted grooves 13 are formed on the outer periphery of the tool body IO, and the tip end of each twisted groove 13 is continuous with the chip pocket 11.

Here, the wall portion of the helical groove 13 facing the rotation direction is a rake face 14, as shown in FIG.

A cutting edge 15 is formed on the outer peripheral ridgeline of the rake face 14, and a margin 1 is provided at a portion of a predetermined width behind the cutting edge 15.
6. A small relief 19 consisting of a first second chamfered surface 17 and a first second chamfered surface 18 is formed.

The margin 16 has a cylindrical curved surface with no double cut, and its margin width T is set to 0.05 mm or less. However, the margin width T may be zero (that is, there is no margin). Further, the first second chamfered surface 17 is formed flat at a portion of a predetermined width behind the margin 16, and is provided with a relief angle α.

Further, a flat second chamfered surface 18 having a relief angle β larger than the clearance angle α is formed behind the first chamfered surface 17 .

Here, the relief angle α of the first second chamfer surface 17 is 1° to 5°.
is set to . In addition, in the margin width T direction,
The clearance W, which is the margin width T plus the width of the first second chamfered surface 17, is set to 0.05 mm to 0.5 mm.

Furthermore, the relief angle β of the second counter-challenged surface 18 is 8° to 20°.
is set to . In FIG. 1, a line segment a, which serves as a reference for relief angles α and β, is a tangent to the margin 16 at the rearmost side.

Here, the basis for the above numerical limitation will be explained along with specific experimental results.

■Reason for setting the margin width T to 0.05 mm or less: If the margin width T exceeds 0.05 mm, the friction with the work material becomes intense, making it easier for the work material to adhere.

(2) Reason for setting the clearance angle α of the first second chamfer surface 17 to 1° to 5″: Table 1 shows the results when drilling was performed with various clearance angles σ selected.

Table 1 As can be seen from Table 1, when the relief angle α is 30', the cutting blade 15 does not perform cutting action and the first and second Friction with the chamfer 17 causes streaks on the inner wall surface of the hole. However, when the clearance angle α is 1.0°, the cutting blade 15 performs a somewhat cutting action, and as a result, no streaks are generated on the inner wall surface of the hole. In other words, by setting the relief angle α to 10 or more, the compressive force applied from the inner wall surface of the hole due to the cutting action of the cutting blade 15 can be removed.

However, when cutting is performed by feeding the work material laterally, the outer periphery of the end mill moves in a trochoidal curve as described above, so the clearance angle σ needs to be set larger. In the general cutting process currently performed,
The cutting allowance may be increased to 1.0 mm/r ev, but in this case, assuming that the relief angle α is zero,
The clearance angle of the first second chamfered surface 17 with respect to the work material is minus 35'. Therefore, in order to prevent second contact of the first second cut surface 17, it is necessary to set the clearance angle σ to 5° with some margin. Although this value is sufficient to prevent welding of the workpiece material in the cutting process currently being performed, unnecessarily increasing the clearance angle α will also lead to chipping and tool chatter due to a decrease in the strength of the cutting edge. This causes a new problem called vibration. Therefore, the relief angle α must be set to the minimum value that can prevent friction between the first counter-facing surface 17 and the inner wall surface of the hole, and the upper limit should be 5° in consideration of the high-feed cutting described above. did.

■ Reason for setting the relief width W, which is the margin radius T plus the width of the first flank surface 17, to 0.05 mm - 0.5 mm Second, when the relief width W is less than 0.05 mm, the strength of the cutting edge decreases.
This is because chipping of the cutting edge 15 is likely to occur. In particular, in horizontal feed cutting, since the cutting blade 15 cuts intermittently,
The cutting edge 15 is likely to break due to the impact force at that time. On the other hand, if the escape radius W exceeds 0.5 mm, as will be described later, the wear width relative to the wear depth becomes wider, resulting in a decrease in service life.

The reason why the clearance angle β of the second chamfered surface 18 is set to 8° to 206° is because if the clearance angle β is less than 8°, the wear width relative to the wear depth becomes wider as described above. This is because if the relief angle β exceeds 20°, the rigidity of the cutting edge will be insufficient when a large amount of cutting resistance is applied, such as in heavy cutting of steel or the like.

However, in the end mill having the above configuration, the cutting edge 15
Since the small relief 19 is formed at the rear of the hole, the friction between the outer circumference of the tool and the inner wall surface of the hole can be reduced. Therefore, it is possible to prevent the work material from adhering to the margin 16 and the first second chamfer surface 17, and it is possible to effectively prevent serious troubles such as the occurrence of streaks on the inner wall surface of the hole due to deposits. can. Furthermore, since the amount of heat generated is small, it is possible to cope with high-speed cutting, and the cooling effect of the cutting oil can be enhanced even at normal cutting speeds.

By the way, as mentioned above, a cutting tool such as a conventional milling cutter with a second corner immediately attached to the rear of the cutting edge (i.e., a cutting tool with no margin formed) is repeatedly cut due to interrupted cutting. There was a drawback that the cutting edge was easily damaged by impact force. However, even in such a cutting tool, by forming the small relief 19 as described above, the wedge angle of the cutting edge becomes larger, thereby increasing the strength of the cutting edge. It is possible to prevent the occurrence of chipping, chipping, etc. of the blade. As a result, the rake angle of the cutting edge and the clearance angle β of the second counter-facing surface 18 can be set larger than the rake angle and counter-counting angle of conventional tools. Hitting can be effectively prevented, and cutting performance can be significantly improved due to the synergistic effect of increasing the strength of the cutting edge. Further, even if the cutting edge portion is made of a material with high hardness such as CBN, cutting can be performed without any problem.

Furthermore, in the above end mill, since the clearance W, which is the margin radiation T plus the width of the first second chamfer surface 17, is set to 0.5 mm or less, as shown in FIGS. 1 and 4, the tool outer periphery Even if the end mill wears down to the point indicated by the dotted chain line in the figure in the same manner as the conventional end mill, the width of the wear is narrower than that of the conventional end mill. Therefore, tool life can be significantly extended.

Figure 4 shows the relationship between the cutting distance and the width of outer circumferential wear when cutting is performed using the end mill with small relief of the present invention (however, clearance angle σ is 1030'') and the conventional end mill. ■ is a carbide end mill with a small relief of the present invention, ■ is a conventional carbide end mill, and ■ is a conventional end mill made of cemented carbide and coated with titanium on the surface. They have similar margins.Also, the cutting conditions are: tool outer diameter:
16 mm, work material: Fe12, and other feeds etc. are the same.

As can be seen from Figure 4, the outer circumferential wear of the small relief end mill ■ is significantly reduced.

Furthermore, it was confirmed that the end mill (2) of the present invention has a lifespan three times that of (2) and four times that of (2). Furthermore, with ■ and ■, the compressive force acting on the margin is large, so almost the entire outer periphery of the end mill is burnt black due to heat generation, whereas with the end mill ■ with small relief, only the area near the cutting edge is burnt. there were.

Further, FIG. 5 shows the relationship between the cutting distance and the radius of outer circumferential wear when cutting is performed using a workpiece material of 550C.

Note that the outer diameter of the tools was 20 mm in both cases, and the cutting conditions were the same. In the figure, ■ is a carbide end mill with a small relief of the present invention, ■ is a carbide end mill with a margin similar to the conventional one on the outer periphery, and ■ is a carbide end mill with a second corner immediately on the rear side of the outer peripheral cutting edge. be.

From FIG. 5, it can be seen that the end mill (2) with small relief significantly reduces outer periphery wear than the conventional end mill (2) with a margin, even if the work material is 5 soc, which has a high tensile strength. In addition, when the cutting distance is short, the end mill with small relief ■ has a wider wear width than the conventional end mill ■ with a double corner, but as the cutting distance becomes longer, the wear width becomes wider compared to the conventional end mill ■. It has become much narrower, and the effect of Small Relief 19 is clearly visible.

Further, the present invention was applied to a reamer, and drilling was performed using a reamer with a clearance angle σ of 10 and a reamer with a relief angle of 1°30'.

In the reamer with a relief angle of 1, there was some friction between the 12th chamfer surface 17 and the inner wall of the hole, but due to the use of cutting oil, there were no problems such as adhesion of chips to the outer circumference of the tool. It did not occur. Furthermore, in the case of the reamer with a relief angle α of 1630', there was no friction with the inner wall surface of the hole, but a slight chatter vibration occurred. However, the chatter vibration had no effect on the dimensional accuracy or surface roughness of the hole, and a smoother machined surface was obtained than with the conventional reamer.

In the above embodiment, the twelfth cut surface 17 is formed flat, but it may be formed into a convex curved surface or a concave curved surface as shown in FIG. Furthermore, the present invention is not limited to end mills, reamers, and drills; it goes without saying that the same effect can be achieved by forming small reliefs on various other cutting tools such as bits, indexable tips, side cutters, and milling cutters. It is.

[Effects of the Invention] As explained above, in the cutting tool with small relief of the present invention, the 12th chamfer surface having a predetermined relief angle is formed on the margin or the rear side of the cutting edge, and the 12th chamfer surface has a predetermined relief angle. A second chamfered surface having a clearance angle larger than the clearance angle of the twelfth chamfered surface is formed on the rear side of the surface, and the margin width is set to 0.05 mm or less, and the second chamfered surface in a cross-sectional view orthogonal to the margin or cutting edge is The clearance angle of the 12th chamfer is 1° to 5°, and the clearance width obtained by adding the width of the 12th chamfer to the margin width is O105mm = 0.5mm, so it can be cut like 7 rice etc. In the case of a cutting tool in which a second bevel is immediately provided at the rear of the blade, it is possible to prevent the occurrence of chipping of the cutting edge. As a result, the clearance angle of the second second chamfer surface can be set to be larger than that of the conventional one, so that double contact can be effectively prevented. Further, even if the cutting edge portion is made of a material with high hardness such as CBN, cutting can be performed without any problem.

In addition, for cutting tools such as reamers that have a margin, the friction between the outer circumference of the tool and the workpiece can be reduced.
Therefore, it is possible to reduce heat generation on the outer periphery of the tool and prevent welding of the work material to the outer periphery of the tool. This makes it possible to prevent troubles such as the occurrence of scratches on the material to be stiffened, and to obtain a number of excellent effects such as the ability to significantly extend the life of the tool.

[Brief explanation of the drawing]

1 to 5 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a diagram showing details of a cross section perpendicular to the margin.
2 is a perspective view showing an end mill, FIG. 3 is a sectional view taken along line ■-■ in FIG. 2 showing a modification of the cutting tool shown in FIG. 1, FIG. FIG. 5 is a diagram showing the relationship between cutting distance and outer circumferential wear width, and FIG. 6 is a cross-sectional view orthogonal to the margin of a conventional cutting tool. l...cutting edge, 2...margin, 3...second chamfer, 10...tool body, 13...twisted groove , 15... Cutting edge, 16... Margin, 17... First chamfer surface, 18... Second chamfer surface. Applicant Nissin Tool Manufacturing Co., Ltd. Figure 1 11

Claims (2)

[Claims] (1) Form a first second chamfer with a predetermined clearance angle on the rear side of the margin or cutting edge, and form a first second chamfer with a clearance angle greater than the clearance angle of the first second chamfer on the rear side of the first second chamfer. A second chamfered surface having a large clearance angle is formed, the margin width is 0.05 mm or less, and the clearance angle of the first chamfered surface in a cross-sectional view perpendicular to the margin or the cutting edge is 1° to 1°.
A cutting tool with a small relief, characterized in that the relief width is 0.05 mm to 0.5 mm, which is the margin width plus the width of the first second chamfer surface. (2) The cutting tool with a small relief according to claim 1, wherein the second chamfered surface has a clearance angle of 8° to 20°.