JPS6048211A - End mill with edge portion reinforced with coating - Google Patents

Abstract

PURPOSE:To prolong life of an end mill, by honing the edge portion of the tool to remove harmful conditions thereon to strengthen the same and then coating the same with hard substance. CONSTITUTION:The edge portion of an end mill provided with honing treatment in such a way that chamfered amount in the direction of the rake face is 0.5 to 6 times of the chamfered amount in the direction of the flank and the chamfered width in the direction of the rake face is 0.003-0.15mm. is coated with hard substance disposed in one or more layers for reinforcement of the edge portion, the hard substance being formed from one or more selected from carbite, nitride, oxide, and borite of Al, Si, and transition metals of groups 4a, 5a, and 6a of the periodic table, boron carbide, hard boron nitride, hard carbon, and solid solution and mixture of these.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of an end mill, and more specifically, the present invention relates to an end mill that has a strengthened cutting edge by honing the cutting edge shown in Utility Model Application No. 57-143897. This invention relates to improvements made by coating hard materials with abrasive properties.

Conventional end mills can be classified into three types based on the structure that holds the tool material that makes up the cutting edge: solid type, solder type, and 1゛A type. used in blades. This is used for relatively small diameters.

In these solid row type end mills.

Firstly, this is to reduce the top-slip phenomenon and cracking when the peripheral cutting edge, which is the main cutting edge, bites into the workpiece 1 or separates from the workpiece.Secondly, the cutting edge and chuck This is because the cutting force was being tried to be reduced as much as possible due to the distance between the two.

Despite having a sharp cutting edge as an end mill, conventional end mills had the following drawbacks. That is, in end mills using high-speed steel as the tool material, pars tend to remain on the cutting edge depending on the grinding conditions of the cutting edge at the time of manufacture, which affects the sharpness at the initial stage of use.

In addition, for cemented carbide end mills, the improvement of cemented carbide is 1%.
With the development of ultrafine grain cemented carbide, cemented carbide end mills have come to play an important role in practical use. Cemented carbide end mills are generally used for cutting cast iron in most cases, but they are used for cutting steel thread, except in areas where high-hardness steel is essentially impossible. Not used much.

Furthermore, even if it is used, there are restrictions on its use, such as requiring a relatively high outer circumferential speed.

This is because, as is well known, although cemented carbide has superior wear resistance compared to high-speed steel, it still has inferior toughness, and therefore, when cutting ordinary steel, etc., the cutting edge is likely to chip or break. ``If you observe the state of damage to the cutting edge after cutting, it is normal that when cutting steel, there are mainly fine chippings accumulated, and there are very few areas of normal wear (-!, scraping wear). The cutting edge of a carbide end mill is essentially required to be sharp.

It is no exaggeration to say that the blade is sharp only when it is not in use after grinding, but as soon as cutting started, the cutting edge chipped, and depending on the conditions, it could not be cut by several tens of meters, resulting in breakage.

Conventionally, among cutting tools, indexable inserts have been effective in preventing chipping of the cutting edge by honing, but the present invention targets end mills, especially solid type or cutting tools.

In soldering shapes, the use of sharp cutting edges has never been common knowledge or applied.

In view of the above two points, the present invention provides an end mill that has been honed to a practical level in advance in the previous application, but the present invention further improves wear resistance, welding resistance, etc. The cutting edge is mainly coated with a hard substance that has certain properties, and the performance is further improved.

That is, 9 the present invention provides an end mill with a honed cutting edge, AL 8i, periodic table No. 4a, 5a,
Group 5a transition metal carbides, nitrides, oxides, borides, and boron carbide, hard boron nitride.

Covered with one or more layers of one or more hard substances selected from the group consisting of hard carbon and solid solutions or mixtures thereof with a thickness of 0.2 to 20μ. An end mill having a coated and reinforced cutting edge, more preferably, the amount of chamfering in the direction of the rake face is 05 to 6 times the amount of chamfering in the direction of the flank face, and.

Chamfer width in rake face direction is 0.003 to 0.15116
The present invention is an end mill characterized in that the cutting edge portion is honed and then coated with the hard material.1 The present invention is applicable to a solid type or low Murayama type end mill in which the blade portion base body is made of carbide. , it is even more effective.

Details regarding the limitations on claims are given below with examples 5- Describe.

Purposes include improving wear resistance, preventing the formation of built-up edges during low-speed cutting, or preventing rake face crater damage that occurs when the cutting edges of pole end mills are non-linear and tend to concentrate. As, Aυ203.8i
aN4. Known coating materials such as TiC, '1''iN, 'I'1CN (titanium carbonitride), Cr carbide, Cl5N, and diamond can be applied to the present invention as hard coating materials. In this case, the coating layer structure is as described above. It can be coated with one type selected from the group of hard materials, or it can be a two-layer structure with TiN as the first layer and Aρ203 as the second outer layer, or even a layer between the first and second layers. A three-layer structure in which a solid solution layer of both is provided further improves the adhesion between the two is effective in the present invention, but if the total thickness of the coating layer is less than 0.2 μm, the effect is small, and if the thickness of the coating layer is 0.2 μm or less, the effect is small. In the above case, the coating layer is likely to peel off from 1 to 1. Particularly in the case of a zl-diameter end mill that mainly makes minute cuts, the coating thickness is preferably 0.3 to 2 μm.

6. Furthermore, the shape and amount of honing has a wider range of acceptable applications than when the honing is not covered. Fig. 1 is an enlarged view of the cutting edge honing part of the end mill, where 1 is the end mill, 2 is the rake face,
3 shows the flank surface, 4 shows the honed surface, (a) is a curved surface chamfered, and (b) is a straight chamfered surface, and then the connection parts of 2 and 4 and 3 and 4 are curved. It is chamfered.

The amount of chamfering a in the direction of the rake face and the amount of chamfering in the flank direction were investigated.

Example 1 Two square-shaped twisted end mills (made of ultra-fine cemented carbide) with outer diameters of 4 and 1610 were chamfered into a curved surface using the brush method so that when the end mill was ψ4, the shape would be A4.
For 16 end mills, a curved surface was chamfered using the brush method in the same way, and a curved surface was chamfered using a brush method after straight chamfering was performed using a bladed grinding jig and a universal tool abrasive for the % 6 end mill. I created a chamfered one. Next, these end mills and an end mill that is not subjected to honing treatment are subjected to the ion brating method to reduce l' i N to 1.
It was coated with a thickness of 2μ (flank surface).

Cutting tests for shoulder milling and down cutting were conducted on a rigid material of 5 soc (1-JR, e=23) using cutting oil under the conditions shown in Table 1.

Table 1 The results are shown in FIG.

The chipping rate in the figure is expressed as a percentage of the total length of the cutting blade, using the total length of the cutting blade.

It is clear that for an end mill of ψ4, a rake face honing amount of 3 to 30 .mu.m reduces the chipping rate, and that a value of 5 to 10 .mu.m is particularly desirable. For end mills of ψ16, those chamfered in a curved shape with a = A are approximately 50 μm.
is the upper limit of the honing amount, but when 34 = chopsticks, 1
Effective up to 50μ islands (=0.15μ), especially 10 to 6
It was a remarkable performance with a chipping rate of 0 at a honing amount of 0μ.

Example 2 Using a two-sided square helical end mill with an outer diameter of 112 m, various honing shapes and amounts were prepared in the same manner as in Example 1, and AbOa was polished from 07 to 07 using an ion blating method different from that in Example 1. A coated (-) sample and an uncoated sample were prepared with a thickness of 1μ.
Cutting tests for shoulder cutting and down cutting were conducted using cutting oil under the following conditions (l C () l Re = 23).

・ Feed = 0.036cm/blade axial depth of cut = 12- Radial depth of cut = 6 wm 9- Cutting length = 3 (1 (10 mm) is shown in Figure 3. The symbols in the figure are as shown in Table 2 below. It is.

Table 2 Cutting edge damage can be significantly reduced by an appropriate combination of grind ratio and rake face honing amount.

Two types of uncoated end mills were used: one with a door of %='/, a=10μ, and one with a/b=FA with a=50μ.

0.15 m, which was inferior to 0.05 sieve or less when coated.

Since the present invention is coated with a hard material, it is effective until the amount of chamfering in the direction of the flank face is twice the amount of chamfering in the direction of the rake face, but if the amount exceeds this, damage to the flank face becomes significant. Chamfering in the direction of the rake face -1 (1- amount is 6 times the amount of chamfering in the flank direction, ie.

The angle formed with the rake face in linear chamfering is approximately H1't
' is effective, but beyond this, the amount of chamfering in the direction of the rake face should be 0.5 to 6 times the amount of chamfering in the direction of the flank, since the effect of strengthening the cutting edge is small and chipping is likely to occur. It is.

Furthermore, in the -F ratio, the amount of chamfering in the rake face direction is less than 0.1103so+, the honing effect is strong and chipping is easy, and when the honing is 0.15a or more, large diameter end mills are partially effective. In general,
The increase in cutting force tends to cause chattering and poor finished surfaces, so the amount of chamfering in the direction of the rake face is set to 0.003 to 0.00.
156.

Furthermore, the present invention is most effective in solid or bladed end mills made of cemented carbide.
Even with high-speed steel end mills, after cutting edge grinding, 10
00~3 (1 (1 (1) By honing with No. 1 abrasive grain, the low hardness part caused by the grinding heat of the paris and cutting edge is removed,
The present invention, which is then coated with a wear-resistant hard material, does not perform conventional honing, thus eliminating harmful conditions such as fine burrs, chips, grinding marks, and low-hardness areas on the cutting edge. ! This shows superior cutting performance compared to end mills that have been coated.

As described above, the present invention removes harmful conditions from the cutting edge by properly honing it, strengthens the cutting edge, and coats it with a hard material, which is particularly effective in increasing the lifespan of steel cutting. It is.

[Brief explanation of drawings]

Fig. 1 is an enlarged cross-sectional view of the cutting edge of the honed end mill, (a) is curved honed, (b) is
indicates linear honing. FIG. 2 and FIG. 3 are diagrams showing the results of Example 1 and Example 2, respectively. 3 Figure rake face ponink amount a (, uyn) Procedural amendment December 21, 1981 Patent Application No. 158656 2 Name of the invention hM Kacho? jA%'B end mill 3 Relationship with the handiwork of the person making the amendment Patent applicant 4 Date of amendment order 1) Voluntary amendment application dated August 29, 1988 2) Application dated August 29, 1988, specifications Document 2 Drawing 6 Contents of amendment 1) Deletion of the indication “Past patent application pursuant to the proviso to Article 38 of the Patent Act” and the indication “Number of inventions stated in the scope of claims” r

Claims (1)

[Claims] 1) In an end mill with a honed cutting edge, k
l, Si, carbides, nitrides, oxides, borides, and boron carbide of transition metals of groups 4a, 5a, and 5a of the periodic table;
One layer or two or more layers of one or more hard substances selected from the group consisting of hard boron nitride, hard carbon, and solid solutions or mixtures thereof, with a hardness of 0.2 to 20%.
An end mill with a reinforced cutting edge and a coating with a thickness of μ. 2) The amount of chamfering in the direction of the rake face is 0.5 to 6 times the amount of chamfering in the direction of the flank face, and the amount of chamfering in the direction of the rake face is 0.
003 to 0.15 - A coated and reinforced end mill according to claim 1, characterized in that the cutting edge is honed to a diameter of 0.003 to 0.15. 3) A solid type or An end mill with a reinforced coated cutting edge according to claim 1 or 2, characterized in that the end mill is of a soldered type.