JP2001252817A - Cutting edge changing cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool having a cutting edge changing type medium and small diameter cutting tool and allowing a cutting tool edge part to be fixed to a shank with good accuracy in the axial and radial directions and with high rigidity. SOLUTION: In this cutting edge changing cutting tool formed by a tool main body having a connecting shaft body integrally formed at the rear part of the edge part, and a shank part removably connected to the tool main body, a fitting shaft part concentrically provided on the connecting shaft part and a fitting hole part concentrically provided on the shank side are mutually fitted, the edge part is a cemented carbide single body of ultra-fine particles WC with a mean particle diameter of 1 micron or smaller, and the Young's modulus is 550 GPa or larger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool having a replaceable blade, and more particularly, to a medium- and small-diameter cutting tool capable of replacing a blade, a connecting shaft, and a shank.

[0002]

2. Description of the Related Art When a diameter is 0. From a few millimeters to more than 10 millimeters
Small-diameter end mills are widely used as solid tools made of cemented carbide or high-speed tool steel, but have many advantages of being integrally formed, but also have disadvantages caused by the integration. In particular, as a disadvantage, the tool cost is higher than that of a tool with a replaceable cutting edge (a throw-away type). However, solid end mills made of cemented carbide are expensive and therefore uneconomical. If damaged, the cost of repolishing is high. In addition, there is a problem in re-polishing accuracy.

Further, among end mills having a diameter as large as 10 or more millimeters, various throw-away type end mills have been put to practical use. A type in which a polygonal plate-shaped insert is clamped and fixed with a screw or the like is used in an end mill having a relatively large diameter, and there is a type in which a medium diameter of about several tens of millimeters is fixed by sandwiching called a keyinger method. Further, it has been applied to an end mill having a diameter of several millimeters. Recently, a method of fixing the end mill blade portion and the shank by shrink-fitting, which includes an end mill blade portion and a shank portion, has been performed. (For example, see JP-A-11-7
No. 7443)

[0004]

According to the present invention, in order to make the cutting tools of medium and small diameters replaceable, the shrink-fitting method has a problem that it takes time to heat, insert, set and cool down. . Furthermore, in the method using heat, no matter how much the heating method is improved, a certain amount of time is required for cooling, and the cooling time more affects the mounting accuracy than the heating method.

Therefore, in the present invention, in consideration of the above-mentioned problems, the cutting tools of medium and small diameters are replaced with blades, and the blades are formed with high accuracy in the axial and radial directions with respect to the shank and with high rigidity. An object of the present invention is to provide a cutting tool that can be mounted and fixed.

[0006]

According to the present invention, there is provided a tool body having a connecting shaft integrally formed at a rear portion of a blade portion, and a shank portion detachably connected to the tool body. In a blade-portion-replaceable cutting tool in which a fitting shaft portion provided concentrically on a connecting shaft body and a fitting hole portion provided concentrically on the shank side are fitted and fixed to each other, wherein the blade portion is A blade-replaceable cutting tool characterized in that it is a cemented carbide of ultrafine particles WC having an average particle diameter of 1 micron or less and has a Young's modulus of 550 GPa or more.

According to a second aspect of the present invention, in the cutting tool of the end mill according to the first aspect, the fitting shaft and the fitting hole are each formed to be tapered so that they are taperedly fitted to each other. This is a cutting tool with a replaceable blade portion.

In the present invention, in order to use the blade portion with higher strength and higher rigidity, the blade portion is formed as a single body and the characteristics of the cemented carbide used for the blade portion are defined. In order to achieve high strength and high rigidity, first, an ultra-fine cemented carbide having an average particle diameter of WC of 1 micron or less is applied. The amount is relatively large, so that the Young's modulus is reduced and the rigidity is somewhat inferior. Therefore, in the present invention, in addition to high strength, in order to increase the Young's modulus, using ultrafine particles having an average particle size of about 1.0 to 0.6 micron which is slightly coarse, without decreasing the strength, reducing the amount of Co. And a blade portion having an increased Young's modulus. The Young's modulus is 550 GPa or more, preferably 580 Gpa.
Pa or more, more preferably 600 GPa or more.

[0009] The cemented carbide used for the blade portion can be produced by a usual powder metallurgy method, but since the entire length of the tool is short, it can be produced by injection molding or the like. . When this injection molding is applied, since the overall length is short, handling at the time of injection is easy, and grinding processing can be reduced to a minimum position. Particularly, since the tapered shaft portion and the like have a draft angle, it is easy to manufacture a mold.

[0010]

FIG. 1 shows a small-diameter ball end mill having an outer diameter of 10 mm. This small-diameter ball end mill is constituted by being detachably connected to the shank 5 even though the rear part 3 of the blade part 2 and the connecting shaft 4 are fitted to each other. The body 3 further fits the fitting shaft 6 and the fitting hole 7 on the shank 5 side to each other,
The connecting shaft 4 and the shank 5 are detachably connected and fixed by the fitting shaft 8 provided on both the connecting shaft 3 and the shank 5 and the fitting hole 9 on the shank 5. It was done. The structure of the end mill is as follows. First, the blade portion 2 of the end mill is made of an ultra-fine-grain cemented carbide having a ball cutting edge.
Are manufactured and fitted and fixed to a connecting shaft 4 made of steel or the like. The connecting shaft 4 is protruded from a fitting shaft 6, and the shank 5 has a fitting hole 7. It is provided and fixed by fitting. A portion where the blade portion and the connecting shaft 3 are in contact with each other;
Contact portions 10 and 11 are provided on an outer peripheral portion of a portion where the connecting shaft 3 and the shank 5 are in contact with each other.

FIG. 2 shows an end mill blade, which has a cutting edge at one end and a fitting projection at the other end. FIG. 3 shows the connecting shaft 3 and the shank 5 in a sectional view. To assemble the end mill, the fitting shaft 6 of the connecting shaft 4 is fitted into the fitting hole 7 of the shank 4 main body, and the connecting shaft 4 is further fitted.
The fitting shaft portion 6 of the end mill blade portion 2 is fitted into the fitting hole portion 7, and the contact surface 10 and the contact surface 11 are pressed against each other to complete the process. In the end mill assembled as described above, there are two places where the fitting shaft and the fitting hole are fitted to each other, and if the precision is not maintained, the peripheral runout accuracy and the like deteriorate. . On the other hand, when high-precision components are combined, they are coaxially coupled with high precision. Therefore, by maintaining the blade portion with high rigidity, high accuracy can be maintained, and the accuracy when the end mill is used, particularly, the durability against runout accuracy and vibration during cutting can be increased.

In the above-described embodiment, the fitting shaft portion of the connecting shaft 4 and the shank 5 is tapered, and the accuracy can be further improved by using a taper of 1/50 or less. The tapered shaft portion and the hole portion are advantageous when the length of the shaft portion is short as in the case of the connecting shaft 4. Further, by providing the contact surfaces 10 and 11 of the connecting shaft 4 and the shank main body 5 with each other, there is an operation such as acting as a stopper.

Next, the blade portion 1 was arbitrarily selected and repeatedly attached to and detached from the main body 3, and the runout accuracy of the outer periphery of the cutting edge based on the shank was recorded. Here, the blade portion and the main body tried the press-fitting method and the shrink-fitting method. Among the products of the present invention, in the case of the press-fitting method, the mounting is performed by using a special jig so as not to hurt the cutting edge portion, and slowly press-fitting and extracting until the fillet of the cutting edge head comes into contact with the end face of the main body tip. Was based on a method of inserting a bar into a through hole provided in the main body and extruding the same using a dedicated jig. In the shrink fit method, the attachment and detachment were performed by heating with hot air. This was subjected to cutting to evaluate the cutting state. For comparison, a conventional method using the collet 7 shown in FIG. 4 is added. Using a structural carbon steel S50C material as a workpiece, the amount of protrusion from the machine tool was fixed at 70 mm, and straight machining was performed by downward cutting. The cutting conditions were 1 mm depth of cut and 1 blade feed.
1 mm, pick feed 3 mm, dry type linear cutting. Table 1 shows the results.

[0014]

[Table 1]

The cutting sound is a sound generated during cutting due to chatter and vibration of the tool, and is affected by tool rigidity and cutting conditions. The surface properties are evaluated comprehensively based on the roughness of the cut surface, peeling, gloss, and the like. These are all affected by the rigidity of the tool installation and the run-out accuracy of the cutting edge when the cutting ability of the cutting edge is the same, and the product of the present invention shows a marked improvement over the conventional product.

FIG. 4 shows a modified example of the blade-exchangeable cutting tool according to the first embodiment. As shown in FIG.
The shank part is further divided into two parts, which are fixed. As a result, it is possible to adopt a structure that further matches the cutting specifications. For example, in the roughing, when vibration is a problem, a structural steel or the like is further used on the blade side (hereinafter, referred to as a connection portion) of the shank portion.
The vibration may be designed to be absorbed. In the case of finish cutting, etc., the blade part has a Young's modulus of 620 to
By increasing the tool protrusion to about 650 GPa and shortening the tool protrusion, a high-quality finished surface can be formed. When a connecting portion is provided, taper fitting may be used as in the case of the shank portion and the blade portion. However, if two portions are connected, it becomes difficult to control runout accuracy and the like. May be fixed using a reinforcing means such as brazing. Further, in the above-described example, the material of the blade portion and the shank portion is a cemented carbide, but the material is not limited to this, and the blade portion may be made of CB.
A high hardness sintered body such as N may be used.

In the end mill thus assembled, the end mill blade, the connecting shaft and the shank are fitted to each other, and the fitting shaft 6 and the fitting hole 7 are tapered. The outer peripheral surface of the fitting shaft 6 and the inner peripheral surface of the tapered fitting hole 7 are almost completely in close contact with each other, and the mounting accuracy with the shank 5 is further improved. Further, as another embodiment, the end mill as shown in FIG. 4 can cope with a case where the tool overhang is long, which is more advantageous than a solid tool.

[0018]

As described above, by using the cutting tool of the present invention, the blade portion can be made of a material having high rigidity, and the occurrence of chatter vibration during cutting can be reduced. If other connecting members are provided, the material of the blade, the connecting part and the shank part is selected from materials having high rigidity according to the cutting specifications, for example, according to the amount of tool protrusion, thereby generating chatter vibration during cutting. Can be reduced, and a high quality surface can be obtained in finishing and the like. Furthermore, by applying the present invention, the blade portion, the connecting shaft, and the shank are fitted by fitting the blade and the connecting shaft, or the connecting shaft and the shank using ultrasonic waves. The three members are coaxially and accurately coupled to each other in the axial direction and the radial direction, so that the mounting accuracy is improved, and the resistance to run-out or vibration during use of the end mill can be increased. The outer diameter is 20 m because the fitting structure between the fitting shaft and the fitting hole is tapered as described above.
It is possible to easily manufacture medium and small diameter cutting tools of m or less.

[Brief description of the drawings]

FIG. 1 shows a front view of an example of the present invention.

FIG. 2 shows a front view of the blade part of FIG.

FIG. 3 shows an axial sectional view of FIG. 1;

FIG. 4 shows a front view of an example of a conventional product.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Blade part 2 Taper shaft part 3 End mill body 4 Adapter part 5 Shank part 6 Tapered hole part 7 Collet

Claims (4)

[Claims] 1. A tool body in which a connecting shaft is integrally formed at a rear portion of a blade portion, and a shank portion detachably connected to the tool body, wherein the shank is concentric with the connecting shaft. A blade-exchangeable cutting tool in which the provided shaft portion is fitted and fixed to a fitting hole portion provided concentrically on the shank side, wherein the blade portion has an average particle diameter of 1 micron or less. Fine particles of WC cemented carbide alone and have a Young's modulus of 550
A blade-replaceable cutting tool having a GPa or more. 2. The cutting tool according to claim 1, wherein the fitting shaft and the fitting hole are formed in a tapered shape so as to be tapered into each other. Replaceable cutting tool. 3. The cutting tool according to claim 1, wherein the ultra-fine-grain cemented carbide has an average particle size of 1.0 to 0.5.
A blade-replaceable cutting tool having a diameter of 6 microns. 4. The cutting tool according to claim 1, wherein the cemented carbide has a Young's modulus of 5.8 GPa or more.