JP2000117523A - Diamond coating end mill or drill and cutting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cut a material hard to be cut at high speed by forming a front rake and a cutting face length of an end mill or a drill cutter having a blade part coated with a diamond coating layer within a prescribed value range. SOLUTION: In an end mill or a drill for a high-speed rotation cutting tool, a front rake E is set to not less than -10 deg. and not more than -60 deg. and its cutting face length F is set to one time or more of the cutting depth for changing a positive rake into a negative rake to be used. The cutting depth is always smaller than the negative cutting face length F so that the cutting starts from a line segment GH on the cutting face and ends at a point G. It is so considered that this fact brings about a different effect from that of the positive rake in discharge of cutting chip. A material hard to be cut such as high silicone aluminium alloy can be cut at high speed, at least approximately 200 m/min or more, in short, approximately 2000 m/min without increasing the cutting resistance and with improving the cutting work roughness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool used for cutting nonferrous metal materials, electronic materials, and the like, and more particularly to an end mill or a drill having a blade portion coated with diamond by a vapor phase synthesis method.

[0002]

2. Description of the Related Art The demand for processing difficult-to-cut materials such as high silicon aluminum alloys with high precision and high efficiency has increased.
High-speed end mills and cemented carbide end mills with high high-temperature hardness, excellent wear resistance and rigidity have begun to be used more and more. An improved product in which a cemented carbide end mill is coated with TiN is also known. It has higher abrasion resistance and has less welding of cutting chips to the cutting edge, so it can cut hard-to-cut materials such as stainless steel. Not usually, 200m /
It is cut at a cutting speed of about min or less.

A polycrystalline diamond material is known as a blade material having a higher hardness. Although it can withstand high-precision continuous cutting and exhibits excellent performance, it is difficult to apply to complicated spiral-shaped drills and end mills, and there is a disadvantage that chipping easily occurs in the cutting edge in intermittent cutting.

[0004]

As a supplement to the disadvantages and costs of the above-mentioned polycrystalline diamond sintered body, there is known a diamond-coated cutting tool in which the surface of a substrate is coated with diamond by a vapor phase synthesis method.

[0005] One example is JP-A-64-51202. According to this proposal, the defect of diamond layer loss due to stress concentration at the cutting edge due to the positive brake at the cutting edge of the cutting tool is reduced to 0. 0 from the flank of the cutting edge.
Honing or chamfer honing is applied to a portion of not less than 01 mm and not more than 0.08 mm to solve the problem.

Although this proposal is excellent, it is not always satisfactory under more severe cutting conditions. Particularly in the end mill described above, at least 200 m / m
in or more, preferably exceeding 1000 m / min and 200
When cutting at a high speed of about 0 m / min or more,
With this honing or chamfer honing, it is not possible to sufficiently prevent the diamond coating layer from being deficient, and cutting by an end mill or a drill in a high-speed region exceeding this cannot be practically used.

[0007]

A first feature of the present invention is that a positive brake, which has conventionally been used as a common sense in a diamond coated rotary cutting tool, has been modified and used as a negative brake in an end mill or a drill. Rake face rake angle -10 °
To -60 [deg.], And the rake face length is specified to be at least 1 time, preferably at least 2 times the cutting depth.

The second characteristic is that the WC layer has a crystal grain size of 4 μm or less, a transverse rupture strength of 100 kg / mm ² or more, and a thermal expansion coefficient of 5.
The rake face length is at least 0.2 mm or more using a cemented carbide of 0 × 10 ⁻⁶ / ° C. or less. The rake face length is determined to be preferably 0.2 mm or more in view of the usual maximum cutting depth in the end milling of a difficult-to-cut material for forming a negative rake angle as described above.

A third feature is that the diamond coating layer is firmly bonded to diamond having an average particle size of 10 μm or less to a thickness of 20 μm or less.

[0010] The fourth feature is that an end mill or a drill having the above-mentioned requirements is used for the purpose.
An object of the present invention is to provide a method for cutting a difficult-to-cut material such as a high silicon aluminum alloy at a cutting speed of 00 m / min or more.

In order to form the diamond coating layer, it is preferable that the cemented carbide substrate is previously heat-treated at about 900 ° C. for about one hour in a reducing atmosphere containing a carbon element.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described in the section of Examples. (Embodiment 1) FIGS. 1 (a), 1 (b) and 1 (c) are front views, side views and an enlarged detailed view of a portion D in an end mill in which the whole tool is made of an integral cemented carbide 1. FIG. The tool length A is 85 mm, the blade diameter B is 30 mm, and the blade length C of 6 blades is 4
3 mm.

[0013] As the cemented carbide 1, WC- ⁶ % Co
The crystal grain size of the WC layer is 2 μm or less and the transverse rupture strength is 150
kg / mm ² or more, coefficient of thermal expansion 5.0 × 10 ⁻⁶ / ° C
The following were used. The entire surface of the portion of the blade length C is covered with a thin film of the diamond coating layer 2 as shown by hatching by the following method. This thin film is the cutting edge part 3.
Although it may be provided only on the (cutting edge), it is often more advantageous to provide it over the entire blade length C in terms of production and use.

The substrate of the cemented carbide 1 was machined to produce an end mill substrate without the diamond layer 2 in FIG. In this production, a large number of trial production examples having different rake angles E shown in Table 1 were produced, and thereafter, heat treatment, diamond coating and cutting tests were also performed on all of the majority. Example 1 has a rake angle of -30 ° in Table 1. The rake face length F was 0.4 mm.

[0015]

[Table 1]

[0016] The above-mentioned end mill substrate is heated filament CV
D device₂-1% CH ₄Substrate temperature in the atmosphere
The temperature was maintained at about 900 ° C. for 1 hour to perform a heat treatment. Heat treatment
Precipitates on the surface of the substrate, especially on the surface on which the cutting edge is formed
Scrub the soot and soot or remove the atmosphere in the CVD equipment.
H₂And remove by heating.

The surface of the substrate subjected to the above treatment has a reduced amount of the bonding metal, a narrow interval between the hard phase particles, small cracks, and it is easy for the next diamond coating to proceed. The adhesive strength with the adhesive is extremely strong. Prior to diamond coating, seeding of ultrafine diamond on the surface of the substrate and / or setting the surface of the substrate to Rmax 1 μm or less,
Since this tendency is stronger, the average diamond particle size is 3
This method is preferable for applying a fine, thin diamond coat having a thickness of 5 μm or less and a thickness of 5 μm or less.

In the diamond coating, the end mill substrate subjected to the above treatment is inserted into the hot filament CVD apparatus with the cutting edge side up so as to stand upright, and the diamond coating layer is formed over the entire length of the cutting edge under the following conditions. Was formed.

[0019]

The thickness of the formed diamond coating layer was about 10 μm, and the adhesion to the end mill substrate surface was strong. A trial production using seeds of the ultrafine diamond was also performed. In this case, since the film formation time was reduced to 5 hours, the diamond crystal grains were 1 μm.
The growth was suppressed to about m and the growth was suppressed to about 5 μm, and a uniform diamond coating layer having a thickness of 5 μm was obtained. As a result, it was confirmed that the average diameter of the diamond crystal could be reduced to 3 μm or less, and the thickness of the diamond coating layer could be uniformly reduced to 5 μm or less, if necessary.

The cutting test was performed on the diamond coating layer having a thickness of about 10 μm under the following conditions. The results are shown in Table 1. In addition, as for the positive rake angles of 10 ° and 0 °, in order to prevent chipping and chipping of the cutting edge, a cutting edge having a roundness of about 5 μm was used in advance.

[0022]

As can be understood from Table 1, even when the rake angle is negative, the cutting force hardly increases at this cutting speed, and particularly, -20 ° to -4 °.
In the case of 0 °, the value is reduced. And the surface roughness of the machined surface is also excellent. The chipping of the cutting edge of the positive one is lower than that of the negative one because the edge strength is low.
The chipping at 60 ° and −70 ° seems to be caused by the increase in cutting force. The number of chips in Table 1 is 10
The number of occurrences of chipping of the cutting edge during the 00m cutting process is shown.

In the above description, the edge portion 3 has a WC layer having a crystal grain size of 4 μm or less and a transverse rupture strength of 100 kg / m 2.
m ² or more, since it is intended to thermal expansion coefficient is formed by providing a diamond coating layer 2 to 5.0 × 10 -6 ^/ ℃ or less of the cemented carbide 1 surface, in what rake angle is negative is , Without having to make the cutting edge round,
It is considered that the strength of the cemented carbide 1 was maintained as it was to the cutting edge, and chipping of the cutting edge due to chipping or the like was prevented.

Furthermore, the diamond coating layer 2 is uniform without providing a rounded edge, and the end mill edge shape produced by machining the base material of the cemented carbide 1 is accurately maintained and is shown in Examples. The effect becomes large in the region of the minute cut as shown in FIG. Therefore, it is considered that the cutting resistance did not increase unexpectedly and the roughness of the machined surface was improved. In general, it is said that the thicker the coating layer, the better the adhesion to the substrate, but the larger the thickness, the more diamond crystal grains grow, and the more uniform the coating surface.
Since the surface roughness is reduced, it is preferable to reduce the thickness as long as the wear resistance can be maintained.

Cut amount (Rd = radial depth)
Is smaller than the length of the negative rake face, cutting always starts between the line segments GH on the rake face and ends at the point G. It is also conceivable that this may have an effect different from that of the conventional positive brake in terms of chip discharge.

(Example 2) Example 2 (rake angle -30 °) having the same configuration as described in Example 1 except that the blade diameter B was changed to 32 mm, and Comparative Example 2 (rake angle) 10
°) created. The rotation speed is 20,000 rpm
FIG. 2 shows the results of a test performed under the same conditions as the cutting test conditions described in the section of Example 1 except that the m and the cutting speed were set to 2010 m / min.

As can be understood from FIG. 2, the working example 2 has a roughness Rmax of 0.75 μm in comparison with the comparative example 2.
Improved and 4N lower in back force.

(Embodiment 3) Embodiment 3 (rake angle minus rake angle) having the same configuration as described in Embodiment 1 except that the tool length A was 175 mm, the blade diameter B was 40 mm, and the blade length C was 60 mm.
30 °) and Comparative Example 3, and a cutting test was performed under the following conditions.

[0030]

FIG. 3 shows the results of the cutting test. Example 3 is different from Comparative Example 3 in terms of the surface roughness Rmax.
It improves by 0.4 μm and the back force is reduced by 4N.

In each of the above embodiments, an end mill is used. However, similar effects can be expected in a drill having an outer peripheral edge and a tip end similarly to the end mill.

[0033]

As described above, according to the present invention, it is possible to provide an end mill or a drill capable of performing cutting with improved cutting surface roughness without increasing cutting resistance. Also, by using the above tools,
Difficult-to-cut materials such as high-silicon aluminum alloy, which has been conventionally considered difficult in practice, are at least 200 m / mi.
It is possible to cut at a high speed of at least n and, if necessary, at least 2000 m / min.

[Brief description of the drawings]

FIGS. 1 (a), 1 (b) and 1 (c) are an enlarged detail view of a part D in a front view, a side view and a front view of an end mill according to an embodiment.

FIG. 2 is a chart showing cutting test results of Example 2.

FIG. 3 is a table showing cutting test results of Example 3.

[Explanation of symbols]

 1 Integrated cemented carbide 2 Diamond coating layer 3 Cutting edge part A Tool length B Cutting diameter C Cutting length D Enlarged portion E Rake angle F Rake surface length H Rake surface axial center end G Rake surface outer periphery end

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Makoto Kawanishi 80-80 Hokita-cho, Sakai-shi, Osaka F-term in Osaka Diamond Industry Co., Ltd. (reference) 3C022 AA01 AA10 KK01 KK06 KK16 KK21 3C036 AA00 JJ01 JJ03 JJ04 3C037 AA02 CC01 CC04 FF04 FF06 FF08

Claims (4)

[Claims] 1. A rake face having a diamond coating layer formed on a surface of a base material, wherein the rake face has a rake angle of -10 ° or more and -60 ° or less and a rake face length of the cut depth. A diamond-coated end mill or drill, wherein the diameter is at least one time. 2. A WC layer having a crystal grain size of 4 μm as a base material.
In the following, using a cemented carbide having a transverse rupture strength of 100 kg / mm ² or more and a thermal expansion coefficient of 5.0 × 10 ⁻⁶ ° C. or less, and a rake face length of at least 0.2 mm or more. The end mill or drill according to claim 1, wherein 3. The end mill or drill according to claim 1, wherein the diamond layer is formed of diamond having an average particle diameter of 10 μm or less to a thickness of 20 μm or less. 4. A difficult-to-cut material is cut by an end mill or a drill according to claim 1, at a cutting speed of 200 m / mi.
A cutting method characterized by cutting at n or more.