JPH08112712A - Milling tool - Google Patents

Abstract

PURPOSE: To provide a milling tool which high-efficiently executes the cutting of a deep bottom face being separated from the main spindle end of a machine among the milling tools applied to a cutting work. CONSTITUTION: A milling tool has a cemented carbide alloy edge part 4 composed of a plurality of twisted outer peripheral cutting edges 2 and bottom edges 3 connecting with the edges 2 at one end of a tool body 1 and a shank 5 extending from the edge part 4 at the other end of the tool body 1, and the edge diameter 6 of the edge part 4 is set up more than 25mm, and its protrusive length is set up more than three times as long as the edge diameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a milling machine or machine tool such as a machining center, which is used for machining a deep bottom surface spaced from the end of a machine spindle.

[0002]

2. Description of the Related Art As a conventional cutting tool used in a machine tool such as a milling machine or a machining center, there is an end mill (hereinafter referred to as conventional product 1) shown in Japanese Patent Laid-Open No. 5-337719. . This is a cemented carbide end mill with a strong helix angle, a negative rake angle, and a large core thickness. In addition, as a general purpose, as shown in FIGS.
If there is a carbide end mill (hereinafter referred to as conventional product 2) specified in JIS standard B4116 shown in Fig. 1 and is used for machining a deep bottom surface spaced from the machine spindle end, the blade length or shank of this It is used by changing the design to extend the length.

As an example of a tool used for machining a deep bottom surface, there is a slot-away cutter (hereinafter referred to as conventional product 3) shown in Japanese Patent Laid-Open No. 2-76613 shown in FIG.
The combination of a cutter used for bottom surface cutting and an arbor that grips this enables deep bottom surface processing, and uses a throwaway tip for the cutting edge. Also, the
You can adjust the length by choosing the length of the bar.

[0004]

However, although the conventional product 1 and the conventional product 2 are end mills having a relatively small diameter and can be used for bottom machining, when machining a large workpiece in a deep and wide area, the tool size is large. Or there was a problem in terms of cutting efficiency. In particular, in the case of the design to which the conventional product 2 is applied, the tool rigidity is insufficient because the emphasis is placed on the enhancement of the machinability, and there is a problem in the machining accuracy and the tool durability when used for cutting the deep bottom. In addition, the conventional product 3 should have sufficient strength and accuracy in the shape of the cutting edge because the cutting edge uses a throwaway tip in order to respond to high-speed cutting, although some results can be obtained in the processing of general materials. However, there is a problem that vibration is easily induced during cutting.

[0005]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the above-mentioned problems, and has a cutting edge with a negative rake angle, a blade shape with a large helix angle and a large core diameter, and a blade portion with high rigidity. (EN) A milling tool that solves the above-mentioned problems by combining with a shank and a shank and can efficiently perform cutting of a relatively large deep bottom surface.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is a cemented carbide comprising a plurality of twisted peripheral cutting edges 2 at one end of a tool body 1 and a bottom blade 3 connected to the cutting edges 2. A milling tool having a blade portion 2 made of an alloy and a sufficiently long shank 5 extending from the blade portion at the other end of the tool body 1, having a blade diameter of 25 mm or more and a protruding length of 3 times the blade diameter.
It is more than doubled. Further, in the blade portion, the rake angle of the outer peripheral cutting edge in the cross section perpendicular to the axis is set to a range of more than -30 ° and less than 0 °, and the core diameter of the blade portion is 70% to 90% of the tool blade diameter. The number of cutting edges set in the range of 8 is 8 or more. The length of the outer peripheral cutting edge 2 in the tool axis direction is equal to or smaller than the blade diameter. next,
The tip of the outer peripheral side of the bottom blade 3 may be slightly chamfered from the rake face side in the direction of decreasing the helix angle, and the shank 5 is made of a material different from that of the blade portion 4, and a method such as brazing is used. It is a technical measure to obtain an even better effect by joining them together with each other and integrally forming them.

[0007]

[Operation] By providing the cutting edge of the milling tool with a blade such as a solid end mill, the machinability is improved, and at the same time, the rigidity or strength of the entire milling tool is improved, and it is possible to easily machine even a relatively large deep bottom surface. It has an effect. Further, the cutting edge has a rake angle of the outer peripheral cutting edge in the cross section perpendicular to the axis of the blade portion set to a range of more than -30 ° and less than 0 °, and the strength of the cutting edge is determined by the negative rake angle and the large blade angle. It enables high-speed cutting and facilitates chip evacuation. Here, if the rake angle becomes larger than -30 ° on the negative side, the machinability is remarkably deteriorated, and on the positive side of 0 °, it becomes a region of a conventional milling tool. Furthermore, the core diameter is 7
0 to 90% requires a larger core thickness in order to maintain the rigidity of the blade portion, less than 70% does not have sufficient rigidity, and more than 90% does not allow sufficient space for the tip pocket or the like. It was set to 70 to 90%.

The term "core diameter" is commonly used in ordinary solid end mills, but since the core thickness means the same material as the blade, it is made of a different material in the present invention. In this case, various methods can be used, such as joining or the like, and therefore, it is defined as "the diameter connecting the bottoms of the flutes".

Further, the processing of the deep bottom surface poses a problem when processing a large area. In the case of a small area, a solid milling tool with a small blade diameter can be used, but as it becomes wider, a tool with a large diameter is desirable in terms of work efficiency. In the present invention, the blade diameter is set to 25 mm or more, which exceeds the upper limit of the conventional product, and the number of blades is set to 8 or more blades by taking advantage of the large core diameter to obtain a further excellent efficiency. In addition, by providing a small chamfer at the tip of the outer peripheral side of the bottom blade in the direction of decreasing the helix angle from the rake face side, the strength of the tip of the cutting edge is reinforced and various cutting processes such as cutting hard materials are smoothed. Can be carried out.

The neck portion of the milling tool according to the present invention is a solid material having a thickness corresponding to the blade diameter, and exhibits a sufficient effect in transmitting the cutting force. For a beam-shaped member that is mechanically mechanically loaded like a milling tool in a cantilevered state, the displacement of the tip end that receives the load is proportional to the cube of the protruding length of the member and inversely proportional to the cube of the member diameter. It is known.
Even from this relationship, the neck diameter is thicker when compared with the case where the tool body is fitted to a thin shank like a throwaway tool or the case where a long flute is provided like a milling tool with a long flute length. The set effect is clear. The blade part of the milling tool and the main body may be integrated by a method such as brazing, and the weight of the entire milling tool is reduced while maintaining the above-mentioned strength, and the characteristics of the material to be the shank are selected to suppress vibration. Can be given.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing the embodiments. FIG. 5 is a side view of the milling tool according to the present invention, and 1 is a tool body. The tool body 1 has a blade portion 4 having a blade diameter of 50 mm, a number of blades of 12 and a cutting edge length of 15 mm for a peripheral blade at one end thereof. The other end of the tool body 1 constitutes a shank 5 having a length of 285 mm and a diameter of 42 mm. Here, although the blade portion is made of cemented carbide, it is joined to the steel shank by brazing at a position 20 mm from the bottom blade side in appearance. Furthermore, after the cutting edge is completed, a titanium-based hard material is coated. FIG. 6 is a front view of the present invention, and FIGS. 7 and 8 are enlarged views and vertical sectional views for explanation. The cutting edge has a rake angle of -15
°, the helix angle was 52 °, the core diameter was 41.5 mm, that is, 83% of the blade diameter. A chamfer having a length of 0.5 mm from the blade bottom is provided at the end gash portion at an angle of 10 ° in the axial direction from the rake face side.

This was subjected to cavity processing of a die casting mold. In the case of a shank diameter of 42 mm, the amount of clamping to the holder was about 70 mm, and the bottom surface having a depth of 200 mm could be efficiently processed. Although cemented carbide is used as the tool material of the blade portion 4 here, cermet may be used.

[0013]

As described above, according to the present invention, the deep bottom surface having a large area, which has been difficult with the conventional tools, is extremely efficient and can be easily cut, and the working time can be shortened. It became.

[Brief description of drawings]

FIG. 1 shows a conventional product 1 and a front view thereof.

FIG. 2 shows an example of a conventional product 2 and shows a front view thereof.

3 shows a side view of the conventional product 2 shown in FIG.

FIG. 4 shows a conventional product 3 and a front view thereof.

FIG. 5 shows an embodiment of the present invention and shows a side view thereof.

FIG. 6 shows a front view of the product of the present invention shown in FIG.

7 is an enlarged view of the blade portion of FIG.

8 is a vertical cross-sectional view of the main part of FIG.

[Explanation of symbols]

 1 Tool body 2 Outer peripheral cutting edge 3 Bottom edge 4 Blade section 5 Shank 6 Blade diameter 7 Core diameter 8 Chamfer 9 Joining position 10 Throwaway tip 11 Blade groove α Twist angle β Rake angle

Claims (5)

[Claims] 1. A tool body 4 made of a cemented carbide consisting of a plurality of twisted peripheral cutting edges 2 at one end of a tool body 1, and a bottom blade 3 connected to the cutting edge, and at the other end of the tool body 1. A milling tool comprising a shank 5 extending from a blade portion, wherein the blade diameter of the blade portion 4 is 25 mm or more, and the protruding length is 3 times or more the blade diameter. 2. The milling tool according to claim 1, wherein
The rake angle of the outer peripheral cutting edge in the cross section perpendicular to the axis of the blade portion is −
It is characterized by comprising eight or more cutting edges which are set in the range of more than 30 ° and less than 0 °, and the core diameter of the blade portion 4 is set in the range of 70% to 90% with respect to the tool blade diameter. Milling tool. 3. The milling tool according to claim 1, wherein the length of the blade portion 4 is equal to or less than the blade diameter, and the shank 5 is a solid cylindrical shape having a diameter slightly smaller than the blade diameter. A milling tool characterized by being. 4. The milling tool according to claim 1, wherein the tip of the outer peripheral side of the bottom blade 3 is slightly chamfered from the rake face side in a direction to reduce the helix angle. . 5. The milling tool according to claim 1, wherein the shank 5 is made of a material different from that of the blade portion 4,
An end mill characterized by being joined.