JPH039945Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application This invention relates to improvements in single-blade or multi-blade gun reamers, reamers, or similar drilling tools having twisted edges.

(b) Prior Art Conventionally, as shown in Fig. 1, there has been a gun reamer in which a torsion cutting edge part 3 made of cemented carbide or high-speed steel is provided at the tip of a shank part 2 extending from a driver part 1, and a gun reamer that is almost the same as this. A reamer as shown in FIG. 2, or a reamer in which a cutting edge 3 is formed by brazing a twisted tip 4 made of cemented carbide or the like to the tip of a shank portion 2, as shown in FIG. 3, is known. ing. Straight-blade reamers tend to cause problems such as chatter during cutting, so deep holes or holes where the pilot hole of the machined hole is not a perfect circle and a part of it is missing, or holes where a horizontal hole passes through the pilot hole. used for processing.

(c) Problems that the invention aims to solve However, in conventional drilling tools of this kind, the cutting edge wears out rapidly, and when drilling deep holes, even slight wear on the cutting edge deteriorates the sharpness, making it difficult to finish the hole. Since the diameters of the inlet and outlet are different, the cylindricity and roundness of the hole cannot be ensured, which has the disadvantage of prematurely reaching the end of its life. Additionally, if there is a notch in the pilot hole, the number of times the cutting blade bites into the work material increases, so the progress of wear on the biting part of the cutting blade is slower than with tools that machine circular holes without a notch. Therefore, in this case as well, the tool life is shortened as described above.

(d) Means to solve the problem This idea was made in view of the above, and is aimed at creating drilling tools such as reamers and gun reamers that have a long life, can maintain high machining accuracy for a long time, and have a good finished surface roughness. The purpose is to provide. Its main feature is that at least one of the total cutting edges of a single or multi-blade reamer, gun reamer, or similar drilling tool with twisted edges such as cemented carbide or high-speed steel This drilling tool is characterized in that a hard sintered chip is fixed to the tip, and the side surface of the hard sintered chip forms part of the rake face of the cutting blade. A diamond sintered body or a high-pressure phase type boron nitride sintered body is preferably used as the hard sintered body chip.
When a diamond sintered body is used as the hard sintered body chip, it is particularly desirable to use a diamond sintered body containing 70% by volume or more of diamond. diamond sintered body,
When used as a drilling tool as in this invention,
Tool flank wear is approximately inversely proportional to diamond content. Therefore, if the diamond content is less than 70% by volume, it is not desirable because a tool life as long as using an expensive diamond sintered body cannot be obtained.

On the other hand, when a high-pressure phase type boron nitride sintered body is used as a hard sintered body chip, it is desirable that the chip contains 55% by volume or more of high-pressure phase boron nitride. When the content of high-pressure phase boron nitride decreases, the hardness of the high-pressure phase boron nitride sintered body decreases. When the sintered body is used in a drilling tool as in the present invention, the work material may be hardened steel, cemented carbide, sintered heat-resistant steel, or the like. Among them, when hardened steel is used as the work material, the flank wear width is the smallest, although the reason is not clear, the high-pressure phase boron nitride is around 60% by volume. On the other hand, in cemented carbide and sintered heat-resistant steel, the flank wear width is approximately inversely proportional to the content of high-pressure phase boron nitride.

Therefore, the content of high-pressure phase boron nitride that can be commonly used in these materials is set to 55% by volume or more. Another feature of the present invention is effective when used as a drilling tool having this type of structure, and is particularly effective in the field of small diameter drilling tools. The reason is that as the diameter becomes smaller, the curvature becomes smaller and the shape of the tool itself becomes smaller.
Processing the shape into the shape shown in FIGS. 7 and 7 has a problem in that the back metal part of the shank is lost. That is, the hard sintered chip used in this application has a double structure as shown in 5 in FIG. The upper surface of the hard sintered body indicated by 5a is a hard sintered body containing diamond or high-pressure phase boron nitride,
The lower side is usually made of cemented carbide or the like. The reason for this is that hard sintered bodies containing diamond and high-pressure phase boron nitride, which form the upper surface of the hard sintered body, are difficult to join using ordinary brazing filler metals. Therefore, a hard sintered body usually has a structure in which a metal with good brazing properties, such as cemented carbide, is bonded in advance at the time of manufacture. When the upper surface of such a hard sintered chip as shown in FIGS. 6 and 8 is made into a rake surface, the wall thickness of the part that supports the hard sintered material becomes thinner. Strength problems arise. Therefore, it is particularly effective in fields where the outer diameter is 5 mm or less. Further, when a diamond sintered body or a high-pressure phase boron nitride sintered body, which has a high hardness, is used as the hard sintered body chip, it is particularly effective because it is difficult to form a complicated shape due to its difficulty in machining. The contents of the present invention will be explained in detail below using the drawings. Figures 4 and 5 show the application of the present invention to a reamer, in which every other cutting edge 3a is made of cemented carbide, high speed steel, etc.
A hard sintered chip is fixed to each cutting blade.
This hard sintered chip 5 is fixed so that its upper surface 5a becomes the outer peripheral surface of the tool, and the hard sintered chip 5 serves as a rake surface of the cutting edge. Currently, there are only a few straight-blade reamers in practical use that have a hard sintered body as a cutting edge, as shown in Figure 6. do not have. However, reamers and the like that have twisted edges typically have curved surfaces for both the rake face and the outer circumferential flank of the cutting edge. has not yet been put into practical use. A hard sintered body, especially a diamond sintered body, is extremely difficult to grind, and it is extremely difficult to process a large area into a complicated shape. When such a hard sintered body is fixed as a cutting edge of a twisted-blade reamer or the like and ground, machining of the rake face in particular becomes a problem due to the rigidity of the processing machine and the shape to be machined. For these reasons, as shown in FIGS. 7 and 8, it is very difficult to manufacture a twisted-blade reamer in which the upper surface of a hard sintered body is fixed so as to become the rake surface of the tool. In this invention, from this perspective, the fourth
As shown in FIG. 5, the upper surface of the hard sintered body is fixed so as to be the outer circumferential surface, and the side surface is the rake surface of the cutting edge, thereby facilitating grinding of the rake surface. This has made it easier to manufacture drilling tools such as reamers with twisted blades. FIG. 9 shows an example of application to a particularly small diameter drilling tool. With small-diameter reamers, etc., the hard sintered body becomes smaller and bonding strength to the shank becomes a problem, but especially in the case of small diameters, bonding can only be achieved by fixing the top surface to the outer circumferential surface. A strong joint can be achieved by increasing the area of the part.

[Brief explanation of the drawing]

FIG. 1 shows a conventional gun reamer, and FIGS. 2 and 3 show conventional reamers. 4 and 5 show a reamer according to the present invention, and FIG. 6 shows a conventional straight blade reamer. Figures 7 and 8 show the conventional reamer, and Figure 9 shows the conventional reamer.
The figure shows a small diameter reamer obtained according to the present invention. Each part in the figure is as follows. 1: Driver part, 2: Shank, 3: Cutting blade part, 5: Hard sintered body, 5a: Upper surface of hard sintered body, 5
b: Hard sintered body rake face.

Claims (1)

[Scope of utility model registration request] For single or multi-blade reamers, gun reamers, or similar drilling tools with twisted edges such as cemented carbide or high-speed steel, at least one cutting edge tip of all cutting edges shall be coated with 70% diamond. A hard sintered body chip made of a diamond sintered body containing at least 55% by volume or a high-pressure phase type boron nitride sintered body containing at least 55% by volume of high-pressure phase boron nitride is fixed, and the side surface of the hard sintered body chip is cut with a cutting edge. A drilling tool characterized by having a part of the rake face.