JPH08323526A - Rotary cutting tool - Google Patents

Abstract

PURPOSE: To provide a rotary cutting tool excellent in rigidity by making a core of a shank of a rotary cutting tool body with cemented carbide, the outer circumference with steel, and the core to occupy a specific percentage of the edge diameter. CONSTITUTION: Overhang magnitude 1 for a three dimension copy cutting is made in a shape occupying a long shank 2 of about four times of the edge diameter in the figure. The core 3 of the long shank 2 is made of cemented carbide and the outer circumference 4 is made of steel. The core 3 and the outer circumference 4 of the long shank 2 are fixed by fitting them together. While the outer circumference 4 and the edge 5 may either be made integrally or individually and then connected together, the edge 5 is connected to the core 3 which is made to occupy 50% to 95% of the edge diameter. Thus it can exhibit excellent performance in large overhand magnitude for three dimension copy cutting and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a rotary cutting tool used in a three-dimensional machine having a large overhang amount in a milling machine or the like.

[0002]

2. Description of the Related Art When a work material is three-dimensionally machined by an MC or the like by a ball end mill or the like, the amount of overhang (protruding amount of tool) must be selected at the deepest machining. In this case, although the influence of the tool protrusion amount is also related to the size of the cutting amount, tool performance, particularly chattering, vibration and the like are likely to occur, chipping and damage such as chipping are likely to occur, and the tool life is shortened. As a countermeasure,
For example, application of solid end mill consisting of single carbide,
As shown in Japanese Utility Model Publication No. 3-103105,
There is a boring bar with a shaft body made of cemented carbide or the like attached to the core.

[0003]

However, there are the following problems when the shank itself is made of cemented carbide or when the shaft is mounted. First, when the shank itself is made of cemented carbide, it is a cemented carbide integrated body, so there is no means to reinforce the brittleness of cemented carbide, which is a brittle material, and it is damaged by impact during processing. It may cause a problem. In particular, when the diameter is large, the weight is heavy and the cost is also high, so that it is currently applied only to a small diameter. In addition, when the shaft body is mounted as in Japanese Utility Model Laid-Open No. 3-103105, the rigidity of the shank portion improves, but the shaft body itself must be smaller than the shank diameter, and There is a problem that the shaft itself must be fixed because the steel part becomes too thick.

[0004]

The object of the present invention is to solve the above problems, to use a cemented carbide for the core, to reinforce the outside with steel and to limit the core to the shank diameter, An object of the present invention is to provide a rotary cutting tool having excellent rigidity by specifying a thickness of a steel portion that balances rigidity and vibration absorption, and further to provide a tool compatible with high-speed cutting and automation.

[0005]

In order to achieve the above object, the present invention is to attach and detach a throw-away tip with a predetermined interval in a circumferential direction and an axial direction between a rotary cutting tool main body and a front outer peripheral portion of the main body. In a rotary cutting tool provided with a freely fixed cutting edge part, the shank of the rotary cutting tool body is made of cemented carbide for the core part and steel for the outer peripheral part, and the core part has a blade diameter of 50-95. %, And the cemented carbide of the core portion is a rotary cutting tool using a material having a compressive strength of 300 to 500 kg / mm ² .

[0006]

According to the present invention, a cemented carbide, particularly a cemented carbide having a medium compressive strength, is used for the core of a rotary cutting tool to make brittleness less likely to occur as a brittle material, and to add a cutting force during cutting. The compressive strength is selected as a guide in order to withstand the force, especially the component force in the feed direction that causes chattering and vibration, and the thrust load during axial cutting. In particular, with a rotary cutting tool having a ball shape, there are many processes in which the feed is switched from axial cutting to radial cutting, so it is necessary to increase the rigidity against thrust load. Moreover, the reason why the cemented carbide of the core portion is set to 50 to 95% is that the rigidity is improved if it is less than 50%, but a special method of fixing the cemented carbide portion must be adopted, and if it exceeds 95%, it is relatively Since the thickness of the steel portion forming the outer periphery becomes too thin, the content was set to 50 to 95%. Furthermore, the steel part also has the function of absorbing vibration and softening the transmission to the machine tool body. Further, a material having a compressive strength of 300 to 500 kg / mm ² is used because when it is less than 300, sufficient rigidity cannot be imparted.
If it exceeds 500, the strength becomes insufficient and brittleness cannot be ignored, so 300 to 500 kg / mm ² was set. Also,
It is difficult to process the cemented carbide part that becomes the core part, especially for coolant holes, but because the outer peripheral part is steel, it is relatively easy to process, and it is possible to supply air, water-soluble cutting oil, etc. . An embodiment of the present invention will be described below with reference to the drawings.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a ball end mill used for three-dimensional contour cutting as an example of the present invention. Due to the three-dimensional copying cutting, the overhang amount 1 is about 4 times the blade diameter, and the shape has the long shank 2. The core 3 of the long shank 2 is made of cemented carbide and the periphery 4 is made of steel. The core 3 is equivalent to JIS K30 and has a compressive strength of 450k.
The material of g / mm ² is used, and the core and the outer periphery are fixed by fitting. Further, the outer peripheral portion 4 and the blade tip portion 5 may be integrally manufactured or may be individually manufactured and joined, and it is important that the blade tip portion 4 is joined to the core portion 3. Furthermore,
When fixing the machine tool body and the tool, a reinforcing means such as a side lock can be provided on the outer peripheral portion 4, and the outer peripheral portion can be made of steel.

FIG. 2 shows a third embodiment of the present invention.
The ball end mill used for dimensional copying cutting is shown. A part of the long shank 2 has a shape in which the carbide of the core is exposed. This is an example of the case where higher rigidity is required, and the cemented carbide of the core portion 3 of the long shank 2 and the reinforcing outer peripheral portion 4 are made of steel, and the core portion 3 is JISK5
0, using a material with a compressive strength of 320 kg / mm ² ,
The core part and the outer peripheral part are fixed by brazing or the like.

Further, a coolant hole for injecting compressed air to the cutting edge portion is provided in the steel portion which is the outer peripheral portion of the rotary cutting tool to cool the cutting edge portion and discharge chips, and to cut a surface to be cut. In particular, it is easy to add a function of discharging chips accumulated in the recess. The invention of the present application is not limited to the above embodiments, but can be applied to various rotary cutting tools within the scope of the concept of the invention, and the material, thickness, etc. of the cemented carbide shank can be adjusted by the end mill. Can be appropriately selected according to the size of the material, the material of the work material, and the like.

[0010]

EFFECTS OF THE INVENTION The present invention exhibits excellent performance in three-dimensional copying cutting with a large amount of overhang by using a carbide material, particularly a material having excellent compressive strength, for a part of the shank of a rotary cutting tool. You can do it.

[Brief description of drawings]

FIG. 1 shows a partial cross-sectional view of a face mill according to the present invention.

FIG. 2 is a partial cross-sectional view of a face mill according to another embodiment of the present invention.

[Explanation of symbols]

 1 Overhang amount 2 Long shank 3 Core part 4 Outer peripheral part 5 Cutting edge part

Claims (2)

[Claims] 1. A rotary cutting tool provided with a rotary cutting tool main body and a cutting edge portion to which a throw-away tip is detachably fixed at predetermined intervals in a circumferential direction and an axial direction of a front outer peripheral portion of the main body, The shank of the rotary cutting tool body comprises a core made of cemented carbide and an outer peripheral part made of steel, and the core has a blade diameter of 50 to 95%. 2. The shank member of the rotary cutting tool according to claim 1, wherein the cemented carbide of the core portion has a compressive strength of 300 to 500 kg / mm ² .