JPS6232731Y2 - - 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, high speed steel, etc. is provided at the tip of a shank part 2 extending from a driver part 1, and a gun reamer similar to this. A reamer with the same configuration 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. These drilling tools are mainly used for drilling deep holes, holes where the pilot hole is not a perfect circle and a part of it is missing, or holes where a horizontal hole passes through the pilot hole. ing.

(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 a slight amount of wear on the cutting edge deteriorates the sharpness, making it difficult to drill holes. Since the diameters of the inlet and outlet of the hole are different, the cylindricity and roundness of the hole cannot be ensured, which has the disadvantage of prematurely reaching the end of its life.

In addition, if there is a notch in the prepared hole, the cutting edge bites into the workpiece material many times, so the progress of wear on the biting part of the cutting blade is slower than with tools that machine circular holes without chips. Therefore, in this case as well, the tool life is shortened.

Note that reamers with hard chips fixed to the tips of straight blades with no helix angle are already known, but straight blade reamers tend to cause so-called chatter (lateral vibration) during cutting, making it difficult to perform high-precision machining. I can't wait.

(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 period of time, and have good surface roughness. A hard sintered chip is fixed to the tip of at least one twisted blade with an axial rake angle of 0, and the edge of this chip is used as a part of the cutting blade.

(e) Examples This invention will be explained in detail below based on the examples shown in the attached FIGS. 4 to 6.

Figures 4 and 5 show the reamer of the present invention, which is made of cemented carbide, high-speed steel, etc.
Hard sintered chips 5 are fixed to every other cutting blade 3a, a total of two cutting blades. This hard sintered chip 5 is fixed with an axial rake angle of 0°, that is, a helix angle of 0°, and the edge 5a that is substantially continuous with the cutting edge other than the hard sintered chip serves as a cutting edge. Note that all cutting edges other than those made of the hard sintered body have a helix angle α regardless of the presence or absence of the chip 5.

The reason why the hard sintered chip is fixed at a twist angle of 0° is to increase the wedge angle of the cutting edge to increase the strength of the cutting edge, and to prevent chipping of the cutting edge during cutting that causes intermittent bite, and to remove the drilling tool from the machine. This is to prevent cutting edges from chipping due to accidents, and this innovation makes it possible to use hard sintered chips in tools with twisted edges, which had been considered difficult, and overcomes the drawbacks of conventional tools. It has been resolved.

In other words, the hard sintered body itself has good edge sharpness, and even if it is not a twisted blade, it can maintain sharpness for a long period of time equivalent to or better than a twisted cutting edge made of cemented carbide. It leaves very little uncut material and has high wear resistance, so even if it is used for cutting with many bites, wear will not progress rapidly.

On the other hand, the function of the blade other than the hard sintered body in this tool is exclusively to burnish the machined hole at the outer peripheral margin, but if the machined hole is deep, a straight blade has the disadvantage that so-called chattering occurs during burnishing. To prevent this, the cutting edges other than the tip blade are twisted edges. With this twisted blade, even if a part of the pilot hole is chipped or a horizontal hole passes through the pilot hole, the outer periphery of the cutting blade will not bite into the chipped part of the workpiece at the same time, and will continue to work along the helix angle. Since one point on the outer periphery of the cutting edge bites continuously, burrs and burrs are less likely to occur at the notch, and it is also known to have the effect of smoothing the discharge of chips during cutting. If the cutting area or burnishing load is large, wear on the outer periphery of the cutting blade progresses and the function of the twisted blade itself is lost. However, in this design, a hard sintered chip is fixed to the tip of the cutting blade, so
The amount of chips or burnishing caused by the twisted blade is extremely small. Therefore, the surface roughness of the finished surface is further improved, and the life of the outer periphery of the cutting blade is dramatically extended compared to reamers, gun reamers, etc. that do not have a hard sintered body at the tip.

FIG. 6 shows a gun reamer as a second embodiment, in which a hard sintered chip 5 is fixed to the tip of the cutting blade with a twist angle of 0°, as in the first embodiment. The other cutting edges have a helix angle α, and the same effect as in the first embodiment can be obtained.

The drilling tool of this invention only needs to have at least one cutting edge with a hard sintered chip, and conversely, hard sintered chips can be attached to all the cutting edges.

Furthermore, the arrangement of the cutting edges with and without hard sintered chips may be irregular. However, considering the balance of cutting force, etc.
It is desirable to arrange both of them alternately as in the first embodiment.

Furthermore, the twisting direction of each twisted blade may be either right or left, and the chip 5 may be a diamond sintered body containing 70% by volume or more of diamond or a high-pressure phase type boron nitride containing 55% by volume or more of high-pressure phase type boron nitride. It is preferable to form it using a type of boron nitride sintered body or the like.

(F) Effect As explained above, the drilling tool of this invention has a hard sintered chip that performs preliminary cutting by fixing a hard sintered chip at the tip of at least one twisted blade with a twist angle of 0°. This protects the cutting edge from chipping, etc., while the other cutting edge, which is made of cemented carbide and contributes to the cutting and burnishing of uncut areas, has a predetermined helix angle to prevent chatter during machining. As a result, it is possible to obtain a hole with a beautiful top surface with high precision even when used for machining deep holes, holes with a chipped part of the pilot hole, or even holes with a horizontal hole penetrating the pilot hole. This provides excellent effects such as a much longer tool life.

[Brief explanation of the drawing]

Figures 1 to 3 are front views showing a conventional drilling tool, Figure 4 is a front view showing an example of the drilling tool of this invention, Figure 5 is a left end view thereof, and Figure 6 is another implementation. It is a front view showing an example. 1...driver part, 2...shank part, 3...
...Cutting blade portion, 3a...Cutting blade, 5...Hard sintered chip, 5a...Edge.

Claims (1)

[Claims for Utility Model Registration] (1) A single or multi-blade reamer, gun reamer, or similar tool having a cutting edge made of cemented carbide or high-speed steel, etc., which has at least one cutting edge. In a drilling tool in which a tip made of a hard sintered body is fixed to the tip and a part of the cutting blade is formed by the tip, the axial rake angle of the cutting blade made of the hard sintered body is set to 0°, A drilling tool characterized in that all cutting edges other than the sintered body are twisted edges having a predetermined helix angle. (2) The above hard sintered chip has 70% diamond
The drilling tool according to claim (1) of the utility model registration, characterized in that it is formed of a diamond sintered body containing at least % by volume. (3) The above hard sintered chip contains high-pressure phase boron nitride.
The drilling tool according to claim (1) of the utility model registration, characterized in that it is formed of a high-pressure phase type boron nitride sintered body containing 55% or more of boron nitride.