JPH0570821U - Rotary cutting tool - Google Patents

Abstract

(57) [Summary] [Object] To provide a rotary cutting tool with improved cutting performance by using a flat cutting edge tip and attaching a twisting edge of a hard sintered body having a large lead angle. [Structure] On the outer periphery of a tool body 1, a chip pocket 2 and a straight seat groove 3 inclined at an angle close to the lead angle of a helical blade are provided, and a cutting blade tip 4 is attached to the seat groove. This cutting blade tip positions the cemented carbide material layer 6 forward of the tool in the rotational direction and brazes it into the seat groove 3. Then, the hard sintered body 5 of the chip 4 has the starting end A near the joint surface with the cemented carbide layer 6 and the ending end B with the twisting blade 7 and the rake face 8 on the back surface of the chip. With this structure, there is no restriction on the design of the twisting blade due to the thickness of the hard sintered body 5 and there is no reduction in the joint area of the cemented carbide layer 6 on the cutting edge termination side, and the radial rake is made substantially constant in each region of the cutting edge. As a result, the effective twist angle α can be increased and the lead angle can be increased, resulting in improved sharpness and chatter suppressing effect.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rotary cutting tool such as an end mill or a reamer equipped with a twisted blade of a hard sintered body containing diamond or cubic boron nitride (CBN) as a main component.

[0002]

[Prior Art]

 Since hard sintered bodies such as diamond and CBN have extremely high hardness, they are often used as cutting edges for processing non-ferrous metals such as aluminum alloys and for processing hardened steel and cast iron.

Conventionally, a hard sintered body for a cutting edge is formed into a flat plate shape by a hard layer such as diamond or CBN and a cemented carbide support layer integrally formed by simultaneous sintering. It is made up of a cemented carbide support layer brazed to the seating surface of the tool body.

However, when such a plate-shaped hard sintered body is attached as it is along the axis of the tool body and used as a cutting blade for a rotary tool such as an end mill or a reamer, the shape of the hard sintered body is As a result, the shape of the cutting edge is limited, and it is not possible to design a tool with good sharpness.

That is, in rotary tools such as end mills and reamers, it is required to increase the cutting edge length and to twist the cutting edge to give a large rake angle in order to improve sharpness. In the structure where the hard sinter of No. 2 is attached in alignment with the axis of the tool, or with a slight inclination, the cutting edge cannot have a large rake angle, and sharpness cannot be improved significantly.

Therefore, a rotary tool using a conventional hard sintered body for the cutting blade has a large cutting resistance and tends to cause chattering. Also, since the rake angle is small, the cutting tool is less likely to be discharged. Is not good either.

Therefore, the present applicant has proposed a tool effective for solving the above-mentioned problems in Japanese Utility Model Application No. 2-1027989. As shown in FIGS. 3 and 4, this tool has a flat seat surface 13 that is inclined at an angle close to the lead angle of the twisting blade on the outer periphery of the tool body 1, and the hard sintered body is provided on the seat surface. The cutting blade tip 4 composed of 5 and the supporting cemented carbide layer 6 is brazed so that the cemented carbide layer 6 is located behind the twisting blade 7 in the rotational direction.

[0008]

[Problems to be solved by the device]

 The rotary cutting tool proposed by the present applicant has design restrictions on the twisting blade depending on the thickness of the hard sintered body 5. In addition, as the cutting edge starts from the starting end A to the ending end B, the brazing of the cemented carbide layer 6 is increased. The attachment area is reduced and the holding power of the tip is also reduced. Therefore, the rotation angle (effective helix angle) α of the cutting edge in the front view of FIG. 4 cannot be increased so much that the blade length increases. In the case of a long tool, the lead angle of the twisting blade that determines the axial rake must be reduced, and there is a problem in that the effects of improving sharpness and preventing chatter are insufficient.

It is an object of the present invention to solve this problem and make it possible to increase the lead angle of the twisting blade while keeping the radial rake constant.

[0010]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention provides a straight seat groove on the outer circumference of the tool body that is inclined at an angle close to the lead angle of the twisting blade, and the seat groove has a hard surface on one surface of the cemented carbide material layer. A cutting edge chip with a structure in which sintered bodies are laminated and integrated is brazed in a direction in which the cemented carbide layer is located in front of the tool rotation direction. The structure that forms the twisting blade on the back surface of the chip on the terminal side is used near the joint surface with the layer.

[0011]

[Operation] Since the seat groove is tilted at an angle close to the lead angle of the cutting edge and the cutting edge chip is fixed thereto, a twisted blade can be formed by using a flat-shaped chip with a regulated size. it can.

Further, since the cemented carbide layer of the tip is arranged in front of the tool in the rotating direction, the brazing area of the cemented carbide layer does not extremely decrease from the starting end side to the terminating side of the cutting edge, Since there is no restriction on the design of the twisting blade due to the thickness of the hard sintered body 5, the effective twisting angle α can be increased to increase the lead angle.

The design regulation of the twisting blade will be described in more detail below. If the radial rake of the twisting blade is made to be almost constant in each part of the cutting edge, the direction of the rake face 8 gradually rotates by the same angle as the angle α from the point A to the point B in FIG. However, in the case of the tip configuration shown in FIG. 4, the rotation of the cutting blade causes the cutting blade position to be gradually biased toward the cemented carbide layer 6 side, so that the cutting blade reaches the layer 6 to make a cutting blade of a hard sintered body. The end point B must be set before the lead angle (axial rake) that can be set becomes small. On the other hand, in the tip structure of the present invention, the cutting edge end is on the back surface of the tip opposite to the cemented carbide layer, and at this position, the cutting back force is in the width direction of the tip (the laminating direction of the layers 5 and 6). Since it acts in a direction perpendicular to (), the effective radial angle should be kept almost constant and the effective twist angle α should be increased to the point where the width W ₁ (see Fig. 2) of the hard sintered body is reduced to the minimum necessary size. You can

[0014]

【Example】

 1 and 2 show an example of the rotary cutting tool of the present invention. As shown in the figure, a cylindrical tool body 1 is provided with chip pockets 2, 2 extending in the axial direction from the tip surface, and the pockets 2, 2 of the chip pockets 2, 2 are formed in the axial direction at the rear edge of the tool pocket in the axial direction. Seat grooves 3, 3 that are inclined toward and extend linearly are formed. The inclination angles of the seat grooves 3 and 3 are set to an angle close to the lead angle of the twisted blade so as to follow the twisted blade 7 of the cutting edge tip 4 fixed thereto.

The cutting edge tip 4 is formed by integrally molding a hard sintered body 5 made of diamond or CBN and a cemented carbide material layer 6 made of cemented carbide by simultaneous sintering. The material layer 6 is housed in the seat groove 3 in a direction in which it is positioned in the front in the rotational direction of the tool, and the cemented carbide material layer 6 is brazed to the groove surface of the seat groove and attached to the main body. This cutting edge tip 4 uses a prismatic elongated shape or one whose outer surface is curved in a shape close to the final shape. After brazing to the main body, a cutting process is applied to remove unnecessary parts and lead angle. It has a constant twisting edge 7 and a rake face 8. It should be noted that the rake face 8 makes almost α rotation between the starting end A and the ending end B of the twisting blade, so that the radial rake is substantially constant at each part of the cutting edge.

With such a structure, the hard sintered body 5 can be provided with a cutting edge even if the effective helix angle α is increased, and the radial rake at each part of the helix blade is also equal to that of the embodiment. It can be of any size.

According to the calculation results, in the conventional structure shown in FIGS. 3 and 4, in the case of a tool having a blade length of 2.5 D (D = tool diameter), the effective twist angle α that can be adopted is the rigidity of the tool body 1 and the cutting edge tip. The holding angle, the strength of the cutting edge at the end of the twisting blade, the service life, etc. are limited to 50 °. Therefore, the lead angle of the twisting blade is limited to 10 °.

On the other hand, in the structure of the present invention, in the case of a tool having the same blade length, the effective twist angle α can be increased to 100 °, and the upper limit of the lead angle is doubled to 20 °.

Below, the results of the cutting performance test with the prototype tool will be described. A cutting blade tip having a hard sintered body (CBN) with a thickness of 1 mm was brazed to an end mill with an outer diameter D of 13 mm, and a twisting blade with a blade length of 35 mm was formed on this tip with a lead angle of 15 °. Finished into the tool of the present invention. Then, the cutting performance was compared between this and an end mill having a lead angle of 8 ° according to the conventional structure shown in FIGS.

When the surface roughness of gray cast iron FC25 was machined on the side surface under the conditions of a rotational speed of 5000 rpm, an axial depth of cut of 30 mm and a radial depth of cut of 0.1 mm, it was found that the tool of the present invention produced Rmax 1. 6 μm, and Rma x 4.1 μm with a conventional tool. From this result, it is clear that the tool of the present invention performed stable cutting with less chatter.

[0021]

[Effect of the device]

 As described above, the cutting tool of the present invention employs a simple method in which the mounting direction of the cutting edge chip with respect to the straight seat groove is opposite to that proposed in Japanese Patent Application No. 2-102789. It is said that it is possible to make the lead angle of the twisting blade larger by making the angle constant and further improve the sharpness and chip discharge performance, which will be more advantageous in terms of high precision machining and high efficiency machining. The effect is obtained.

[Brief description of drawings]

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

FIG. 2 is an enlarged front view of the tool shown in FIG.

[Fig. 3] Side view of a conventional tool

FIG. 4 is an enlarged front view of the tool shown in FIG.

[Explanation of symbols]

 1 Tool Body 2 Chip Pocket 3 Seat Groove 4 Cutting Edge Tip 5 Hard Sintered Body 6 Carbide Layer 7 Twisting Blade 8 Rake Face A Starting Point of Twisting Blade B End of Twisting Blade α Effective Twisting Angle 13 Seating Surface

Claims (1)

[Scope of utility model registration request] 1. A rotary cutting tool having a hard sintered body twisting blade, wherein a straight seat groove inclined at an angle close to the lead angle of the twisting blade is provided on the outer periphery of the tool body, and the seat groove is provided with: A cutting blade tip having a structure in which a hard sintered body is laminated and integrated on one surface of a cemented carbide layer is brazed in a direction in which the cemented carbide layer is located in front of the rotation direction of the tool, and the cutting blade has a cutting blade. A rotary cutting tool characterized in that a twisting blade is formed at a position near the joining surface with the cemented carbide layer on the starting end side and on the back surface of the tip at the terminating end side.