JP2555676B2 - Surface coated tungsten carbide based cemented carbide end mills and drills - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has a surface-coated tungsten carbide (hereinafter referred to as WC) based cemented carbide having particularly excellent fracture resistance and excellent wear resistance. The present invention relates to end mills and drills.

[Conventional technology]

Conventionally, generally, in order to impart wear resistance to a part or the whole of the surface of a WC-based cemented carbide substrate, 4a, 5 of the periodic table is used.
Carbides, nitrides, and oxides of Group a and 6a metals,
And a hard coating layer composed of two or more solid solutions of these, and a single layer of Al ₂ O ₃ or two or more layers of Al ₂ O ₃ formed by a conventional chemical vapor deposition method or physical vapor deposition method. A surface-coated WC-based cemented carbide end mill and a drill are known. A typical example of this end mill is shown in FIG. 1 and a typical example of the drill is shown in FIG. 2 in a front view.
The drawing shows a cross-sectional view taken along the line I-I in FIG. 1, in which a is a flute portion and b is a margin portion, and this structure is the same for a drill.

[Problems to be Solved by the Invention]

However, in the above-mentioned conventional surface WC-based cemented carbide end mill and drill, in particular, in the hard coating layer of the ridge line portion where the flute portion of the cutting edge and the margin portion intersect, due to lack of fracture resistance, chipping or chipping may occur. It is likely to occur and reaches the end of its useful life in a relatively short time.

[Means for solving the problem]

Therefore, the present inventors, from the above viewpoints, pay attention to the conventional surface-coated WC-based cemented carbide end mills and drills, as a result of conducting research to impart excellent fracture resistance thereto, One of Ti carbide, nitride, carbonitride, and carbonitride oxide (hereinafter referred to as TiC, TiN, TiCN, and TiCNO) for the hard coating layer in the surface-coated WC-based cemented carbide end mill and drill. When specifying a single layer or multiple layers of two or more and forming it by physical vapor deposition, the WC-based cemented carbide substrate is housed, for example, in a cylindrical net made of stainless steel at predetermined intervals. When the hard coating layer is formed under the normal condition, that is, the hard coating layer formed without the tubular net body has a substantially constant thickness in any part in a plane, in this case, the hard coating layer is formed. Layer thickness depends on cutting edge flute and margin The WC-based cemented carbide end mill and drill in this state are gradually reduced toward the ridgeline where We obtained the finding that it showed deficiency.

This invention has been made based on the above findings, and a part or the whole surface of the WC-based cemented carbide substrate,
Hard consisting of one type of TiC, TiN, TiCN, and TiCNO, or multiple types of multiple layers, with the thickness gradually decreasing toward the ridge line where the flute part of the cutting edge and the margin part intersect. It is characterized by a surface-coated WC-based cemented carbide end mill and a drill formed by forming a coating layer.

〔Example〕

Next, the surface-coated WC-based cemented carbide end mill and drill of the present invention will be specifically described by way of examples.

As a WC-based cemented carbide substrate, by weight%, WC-0.5% VC-1
Ion plating, which is classified as a physical vapor deposition device, is prepared by using a 2-flute end mill material with a diameter of 6 mm and a composition of 2% Co, and covering it with a cylindrical net made of stainless steel with a diameter of 7.5 mm. Load into the device and under normal conditions
The surface-coated WC-based cemented carbide end mills of the present invention (hereinafter referred to as the coated end mills of the present invention) 1 to 7 were produced by forming hard coating layers having the compositions and layer thicknesses shown in the table.

The thickness of the hard coating layer is 5m from the tip of the end mill.
Cut the position m at a right angle to the cutting edge, observe the cross section with a microscope, and see that the flute part and the margin part are Measure 0.01 mm and 0.03 mm inside positions from the intersecting ridge position and the flute side and margin side ridge lines, respectively.
The results are shown in Table 1. In this case, on the flute side and the margin side, the 0.01 mm inner side position and the 0.03 mm inner side position from the ridge line showed almost the same value, and therefore Table 1 shows the measured value on the margin side.

Also, for comparison purposes, comparative surface-coated WC-based cemented carbide end mills (hereinafter comparative coated end mills) 1 to 7 were manufactured under the same conditions except that a cylindrical net body was not used.

Then, for various coated end mills obtained as a result, work material: SCM440 (hardness: H _B 249), cutting speed: 30 m / min, end mill rotation speed: 1592 r.pm, axial cut: 9 mm, radial direction A wet cutting test of steel was performed by a down-cut method under the condition of depth of cut: 1.2 mm, and the processing time until the wear width of the margin of the cutting edge reaches 0.2 mm was measured. The results are shown in Table 1.

〔The invention's effect〕

From the results shown in Table 1, the coated end mill 1 of the present invention
In all of Nos. 7 to 7, the thickness of the hard coating layer gradually decreases toward the ridge line where the flute portion and the margin portion intersect, which ensures excellent fracture resistance and causes the occurrence of chipping or chipping on the cutting edge. However, in the comparative coated end mills 1 to 7 having a constant hard coating layer thickness, all of the coated coated end mills 1 to 7 have defects and have a relatively short service life. It is clear that this will happen.

In addition, in the said Example, although the end mill was described, the same result is shown also about a drill.

As described above, the surface-coated WC-based cemented carbide end mill and drill of the present invention have extremely excellent fracture resistance, and also have excellent wear resistance, so that excellent cutting is achieved over a significantly long period of time. It exerts its performance.

[Brief description of drawings]

1 is a front view of an end mill, FIG. 2 is a front view of a drill, and FIG. 3 is a sectional view taken along the line I-I of FIG. a: flute part, b: margin part.

Claims (1)

(57) [Claims] 1. A carbide, a nitride, and an oxide of a group 4a, 5a, and 6a metal of the periodic table, and two or more thereof on a part or the whole of the surface of a tungsten carbide-based cemented carbide substrate.
A surface-coated tungsten carbide-based cemented carbide end mill and drill, comprising a hard coating layer comprising one or more solid solutions and one or more multi-layers of aluminum oxide. The layer is composed of a single layer of one or more of Ti carbide, nitride, carbonitride, and carbonitride, and the flute part of the cutting edge and the margin part intersect each other. A surface-coated tungsten carbide-based cemented carbide end mill and drill, characterized in that the thickness of the hard coating layer is gradually reduced toward the ridgeline.