JPH04304907A - Tool for cutting - Google Patents

Abstract

PURPOSE:To provide a tool for cutting capable of restraining vibration even in the case of a shank part being slender as well as enabling an intermittent cutting in the tool for cutting CBN and diamond, etc., having the hard and brittle edge. CONSTITUTION:A shank 1 is composed of the 1st shank 4 at the tip side and 2nd shank 5 of the base end side, a 1st metal layer 6 is interposed between a tip 3 having an edge tip 2 and the 1st shank 4 and a 2nd metal layer 7 between the 1st shank 4 and 2nd shank 5. Now a 1st metallayer 6 is formed by the material of the smaller elastic modulus than the material composing the tip 3 and 1st shank 4 and the 2nd metal layer 7 than the material composing the 1st shank 4 and 2nd shank 5 respectively. An intermittent cutting and the cutting of the small diameter internal face, etc., of the member to be cut are made possible with the metal layers 6, 7 absorbing the impact acting on the edge tip 2 and the vibration under cutting work.

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 tip having a cutting edge attached to the tip of a shank portion.

0002

[Prior Art] As this type of cutting tool, for example, C.
Bits are often used in which a tip with a cutting edge coated with BN or diamond is joined to a shank made of ordinary steel by brazing or the like. Such a cutting tool is fixed on a machine tool such as a lathe, and is used to cut the workpiece (
While rotating the workpiece, the cutting edge is brought close to the workpiece to make a cut, thereby machining the member to be cut.

0003

[Problem to be solved by the invention] By the way, CBN and diamond that make up the cutting edge of such cutting tools have extremely high hardness and can be used to process almost any material, but on the other hand, they lack toughness and are brittle. Therefore, when a cutting tool or the like having the above-mentioned structure is subjected to an intermittent impact load due to contact with a cut member, the cutting edge may not be able to withstand this load and may break off. For this reason, it has been considered impossible to perform interrupted cutting, which involves frequent repeated contact with the workpiece, with a cutting tool using such CBN or diamond for the cutting edge.

[0004]Furthermore, such cutting tools generate vibrations due to contact with the workpiece during cutting operations, and these vibrations propagate from the cutting edge to the shank, resulting in so-called chatter, which reduces machining accuracy. This was a contributing factor. In order to suppress this vibration and prevent chatter from occurring, it is sufficient to give the shank a certain degree of wall thickness, but this limits the cross-sectional area of the shank at its lower limit. For this reason, it is difficult to maintain a certain level of machining accuracy in cutting operations that require a cutting tool with a narrow shank, such as cutting the small-diameter inner surface of a workpiece, or especially cutting an acute angle on this inner surface. It was considered extremely difficult.

[0005]

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and provides a cutting tool in which a tip having a cutting edge is attached to the tip of a rod-shaped shank portion. It is composed of a first shank on the distal side and a second shank on the proximal side, and the tip is provided at the distal end of the first shank with a first metal layer having a lower elastic modulus than those of the tip and the first shank. At the same time, a second metal layer having a lower elastic modulus than the first shank and the second shank is interposed between the first shank and the second shank. be.

[0006]

In the present invention, first, a first metal layer is interposed between the shank portion and the tip. Here, the first metal layer is made of a metal having a lower elastic modulus than the tip and the first shank, and the impact load that acts on the cutting edge of the tip due to contact with the workpiece at the start of cutting is , is absorbed by this first metal layer. For this reason, even when brittle materials such as CBN or diamond are used for the cutting edge and impact loads are applied intermittently, the first metal layer compensates for the lack of toughness of such materials and provides cushioning. This function prevents damage to the cutting edge.

Further, in the present invention, the shank portion is composed of a first shank on the distal side and a second shank on the proximal side, and there is also a gap between the first shank and the second shank. A second metal layer having a small elastic modulus is interposed. Therefore, even if an impact load that cannot be fully absorbed by the first metal layer is applied, this can be absorbed by the second metal layer, making it possible to more effectively prevent chipping of the cutting edge during interrupted cutting. can be prevented.

Furthermore, according to the present invention, since the first metal layer and the second metal layer also absorb vibrations propagating from the tip to the shank portion due to contact with the workpiece, the shank portion The occurrence of chatter is suppressed. This eliminates the need to provide the shank with a wall thickness to suppress chatter, and it becomes possible to form a cutting tool with a thin shank.

[0009]

[Embodiment] Next, an embodiment of the present invention will be described with reference to FIG. As shown in this figure, this embodiment is composed of a rod-shaped shank part 1 and a tip 3 having a cutting edge 2 attached to the tip of this shank part 1. It is composed of a first shank 4 and a second shank 5 on the proximal end side. Here, the first shank 4 is formed into a rectangular parallelepiped shape at its base end, and the second shank 5 is also formed into a rectangular parallelepiped shape with the same width and large thickness as the first shank 4. A recess 5A that engages with the proximal end of the first shank 4 is formed on the distal end side of the second shank 5, and the first shank 5 extends from 1/3 to 1/3 of its total length from the proximal end. 1/2 is superimposed on the recess 5A of the second shank 5. The cutting edge 2 portion of the tip 3 is made of CBN or diamond, while the first shank 4 of the shank portion 1 is made of cemented carbide, and the second shank 5 is made of steel such as carbon steel. has been done.

A first metal layer 6 is provided between the tip 3 and the first shank 4 of the shank portion 1, and a second metal layer is provided between the first shank 4 and the second shank 5. metal layer 7
is interposed over the entire surface of each joint. The first metal layer 6 and the second metal layer 7 are both made of copper and have a layer thickness of about 0.3 to 0.5 mm, and are used for the chip 3, the first shank 4, and the first metal layer, respectively. The tip 3, the first shank 4, and the second shank together constitute the cutting tool of this embodiment. Here, the elastic modulus of the cemented carbide forming the first shank 4 is 46,000 to 67,000 kg/mm2.
, the elastic modulus of the carbon steel constituting the second shank 5 is 200
00 to 25,000 kg/mm2. On the other hand, the elastic modulus of copper constituting the first metal layer 6 and the second metal layer 7 is 10,000 to 13,000 kg/mm<2>, which is smaller than that of the other constituent members.

In a cutting tool having such a structure, the impact caused by the load when the cutting edge 2 comes into contact with the workpiece at the start of cutting is absorbed by the blade inserted between the tip 3 and the first shank 4. It is mostly absorbed by the first metal layer 6, which has a small elastic modulus. Furthermore, even if the first metal layer 6 cannot absorb all of the impact, the impact will be absorbed by the first metal layer 6.
completely absorbed by the second metal layer 7 interposed between the shank 4 and the second shank 5. This results in
Even if the cutting edge 2 of the tip 3 is made of a brittle material such as CBN or diamond, and the impact is applied intermittently, the first metal layer 6 and the second metal layer 7 act as a cushion to prevent these. Since the lack of toughness of the material is compensated for and the impact is prevented from acting directly on the cutting edge 2, it is possible to prevent the cutting edge 2 from breaking. Therefore, it becomes possible to perform interrupted cutting using a cutting tool having a cutting edge made of CBN or diamond, which was previously considered impossible, and the machining applications of such a tool can be greatly expanded.

Furthermore, in this embodiment, since the first shank 4 is made of cemented carbide having a high elastic modulus and therefore high rigidity, it is possible to reduce the displacement of the cutting edge 2 due to the load during cutting work. There is no reduction in machining accuracy even in interrupted cutting. Further, according to the present invention, vibrations that propagate from the tip 3 to the shank portion 1 during cutting work and degrade the machining accuracy of the workpiece can also be prevented by the tip 3.
a first metal layer 6 interposed between the first shank 4 and the first shank 4;
, and the second metal layer 7 interposed between the first shank 4 and the second shank 5. Therefore, in order to suppress this vibration, it is now possible to reduce the wall thickness of the shank part, which was previously set to be larger than necessary. Sharp edges can be easily cut. Moreover, in this embodiment, the first shank 4
As described above, since it is made of a cemented carbide having a high elastic modulus, sufficient rigidity can be imparted to the shank portion 1 even if the shank portion 1 is made thin.

By the way, in such a cutting tool in which the tip 3 and the shank portion 1 are joined by brazing,
It is known that the tip 3 and the shank portion 1 undergo thermal expansion and contraction due to heat generated during brazing or cutting work. However, since the CBN and diamond that make up these tips 3 have different thermal expansion coefficients from the cemented carbide and carbon steel that make up the shank part 1, they frequently come into contact with and separate from the workpiece as in the above-mentioned interrupted cutting. If thermal expansion and contraction occur repeatedly, the tip 3 and shank part 1
The difference in thermal expansion coefficient between the two may cause distortion between the two, which may deteriorate processing accuracy.

In contrast, in the cutting tool of this embodiment,
The first metal layer 5 interposed between the chip 3 and the shank portion 1 is made of copper, and has the advantage that it also absorbs the distortion caused by the thermal expansion and contraction. Therefore, even in the case of interrupted cutting, the machining accuracy does not deteriorate due to the heat generated thereby, making it possible to further enhance the above-mentioned effects. Further, in this embodiment, as described above, the first shank 4 is joined to the concave portion 5A of the second shank 5 so that approximately 1/3 to 1/2 of the total length from the base end thereof is overlapped with the concave portion 5A of the second shank 5. . Thereby, it is possible to increase the bonding area between both shanks 4 and 5, thereby increasing the bondability and making it possible to further increase the rigidity of the shank portion 1.

Next, FIG. 2 shows another embodiment of the present invention, in which the same parts as in the embodiment shown in FIG. This embodiment is characterized in that the cutting edge 2 of the tip 3 attached to the tip of the shank portion 1 is formed into an acute angle. In a cutting tool having such a configuration, a first metal layer 6 is provided between the tip 3 and the first shank 4, and a second metal layer is provided between the first shank 4 and the second shank 5. Since the layers 7 are interposed, the same effect as the embodiment shown in FIG. 1 can be obtained. Further, since the cutting edge 2 is formed at an acute angle, it has the advantage that when cutting the small diameter inner surface of a workpiece, it is possible to easily process the acute angle portion of the inner surface.

In this embodiment, copper is used for the first metal layer 6 and the second metal layer 7, and the layer thickness is 0.3 mm.
-0.5 mm, but the present invention is not limited to this. The material and layer thickness of these metal layers 6 and 7 should be set in consideration of the materials, dimensions, cutting conditions, etc. of the tip 3, the first shank 4, and the second shank 5. However, when copper is used for the metal layers 6 and 7, it is desirable that the layer thickness is 0.1 to 0.7 mm. This is because if the layer thickness of the metal layers 6, 7 is less than 0.1 mm, there is a risk that the impact absorption effect by the metal layers 6, 7 will not be sufficiently exhibited, and also if the layer thickness is less than 0.1 mm,
．． This is because if the diameter exceeds 7 mm, the rigidity of the shank portion 1 will be affected.

[0017]

As explained above, according to the present invention, the first metal layer interposed between the chip and the first shank, and the first metal layer interposed between the first shank and the second shank. Since the interposed second metal layer absorbs the impact caused by the contact between the cutting edge and the workpiece at the start of cutting, the cutting edge will not be damaged even if cutting is performed intermittently. Therefore, it is possible to perform interrupted cutting using a cutting tool having a cutting edge made of CBN or diamond, which was previously considered impossible. In addition, these first metal layers and second metal layers
The metal layer prevents vibrations from propagating to the shank during cutting, and this allows the shank to be made thinner, making it easier to machine small-diameter inner surfaces and sharp corners of the workpiece. becomes possible.

[Brief explanation of drawings]

FIG. 1 is a side view showing one embodiment of the present invention.

FIG. 2 is a side view showing another embodiment of the invention.

[Explanation of symbols]

1 Shank part 2　Blade tip 3 Chip 4 First shank 5 Second shank 6 First metal layer 7 Second metal layer

Claims (1)

[Claims] 1. A cutting tool comprising a tip having a cutting edge attached to the distal end of a rod-shaped shank portion, the shank portion comprising a first shank on the distal end side and a second shank on the proximal end side. , the tip is attached to the tip of the first shank via a first metal layer having a lower elastic modulus than the tips and the first shank, and between the first shank and the second shank. A cutting tool characterized in that a second metal layer having a lower elastic modulus than the first shank and the second shank is interposed.