JP2022102447A - Cutting tool - Google Patents

Abstract

To provide a cutting tool which is used for further cutting an outer peripheral part of a prepared hole formed in a work-piece, can achieve improvement in chip discharge performance by finely dividing the generated chip and can prevent that the chip extends long and damages the work-piece and so on, and further, is excellent in reusability.SOLUTION: A cutting tool 1 comprises a cutting blade part 12 which further cuts an outer peripheral part of a prepared hole H formed in a work-piece W. The cutting blade part 12 comprises a first cutting blade part 12A on an outermost diameter part of a body 10, and comprises a second cutting blade part 12B which is formed with a face continuous with the first cutting blade part 12A and is extended in parallel to a central axis C of the body 10 on an inner diameter side with respect to the first cutting blade part 12A. The second cutting blade part 12B is so formed as to have a surface roughness larger than the first cutting blade part 12A, and is formed in a region inside 50% from an outermost diameter side of a cutting allowance E of the outer peripheral part of the prepared hole H in the central axial direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cutting tool, and more particularly to a cutting tool provided with a cutting edge portion for further cutting an outer peripheral portion of a prepared hole formed in a work.

Mechanical equipment parts exemplified for caliper bodies for automobiles and motorcycles are generally cast by a casting process using cast iron, aluminum or an aluminum alloy as a base material, and then a predetermined hole for mounting parts is formed in the cutting process. Will be done.

When forming the above-mentioned hole, if the required accuracy cannot be obtained by cutting only with a drill, a processing step of forming a pilot hole and further cutting the outer peripheral portion thereof is performed. Reamers and stepped drills are known as tools for performing such cutting.

Japanese Unexamined Patent Publication No. 04-217404 US Patent Application Publication No. 2010/0278603 Japanese Patent No. 5953173

By the way, in a general cutting process, when a work (object to be cut) is cut with a cutting tool, if the chips are in a long stretched state, they will get into the space between the work and the cutting tool. There is a risk of damaging the workpiece or cutting tool. In particular, when the work is formed of aluminum or an aluminum alloy, there is a tendency that a problem of long chip elongation tends to occur. As an example, FIG. 5 shows a photograph of a long stretched chip when cut with a conventional cutting tool.

To solve such a problem, for example, like a cutting tool provided with a throw-away tip disclosed in Patent Document 1, a configuration having a different surface roughness makes it easier to curl chips and improves chip discharge. The technology is known. However, since the throw-away insert is a technique that is premised on replacement when it is worn, the replacement blade is costly and the cost of the cutting tool is increased.

On the other hand, with the object of suppressing the wear of the cutting edge portion itself, the first cutting edge portion and the second cutting edge portion are formed of different materials to obtain a friction coefficient as in the cutting tool disclosed in Patent Document 2. There is known a technique for improving the wear resistance of the cutting edge portion by using different configurations.

In addition, as in the cutting tool disclosed in Patent Document 3, the friction coefficient between the first cutting edge portion and the second cutting edge portion is different, and the rake angle of each rake face is different. , A technique for improving the separation property (easiness of separation) of chips is known.

Since these cutting tools have been developed on the assumption that they are used for drill cutting without pilot holes, it is unlikely that chips will grow for a long time in the cutting process. The reason is that since the cutting speed (speed in the circumferential direction) of the drill differs depending on the radial position, the chips generated from the tip are curled by the speed difference and have a shape that is easily broken. Therefore, the chips usually do not grow long. However, when a pilot hole is provided and these cutting tools are used for drill cutting of the outer diameter portion, a narrow region near the outer diameter of the cutting edge portion comes into contact with the work, so that the cutting target portion is used. The above speed difference (difference in cutting speed depending on the radial position) does not occur so much. Therefore, there is a high risk that the chips will grow for a long time.

INDUSTRIAL APPLICABILITY The present invention has been made in view of the above circumstances, and is used for further cutting the outer peripheral portion of a pilot hole formed in a work. By finely dividing the generated chips, it is possible to improve the chip discharge property. At the same time, it is possible to prevent the chips from extending for a long time and damaging the work or the like, and it is an object of the present invention to provide a cutting tool having excellent reusability.

The present invention solves the above-mentioned problems by means of a solution as described below as an embodiment.

The cutting tool according to the present invention is a cutting tool provided with a cutting edge portion for further cutting the outer peripheral portion of a prepared hole formed in the work, and the cutting edge portion is first on the outermost diameter portion of the cutting tool. A second cutting edge portion is provided and is formed by a surface continuous with the first cutting edge portion, and is extended on the inner diameter side of the first cutting edge portion in parallel with the central axis of the cutting tool. The second cutting edge portion is provided with a cutting edge portion, and the surface roughness of the second cutting edge portion is formed to be larger than that of the first cutting edge portion. It is characterized in that it is formed inside the central axis direction from the% point.

According to the above configuration, in the process of further cutting the outer peripheral portion of the prepared hole formed in the work, the generated chips can be finely divided. Therefore, it is possible to improve the dischargeability of chips and prevent the chips from extending for a long time and damaging the work or the like. Moreover, since re-polishing becomes extremely easy, it is excellent in reusability.

Further, the above configuration can be suitably applied to a reamer as a cutting tool and a stepped drill in which the cutting edge portion is formed on the stepped drill shoulder portion.

According to the cutting tool according to the present invention, it is possible to finely divide the generated chips by further cutting the outer peripheral portion of the prepared hole formed in the work. Therefore, it is possible to improve the dischargeability of chips and prevent the chips from extending for a long time and damaging the work or the like. Further, the structure in which the cutting edge portion, that is, the first cutting edge portion and the second cutting edge portion are formed by continuous surfaces facilitates re-polishing of the cutting edge portion. Therefore, the reuse of the cutting tool can be promoted, and the cost can be reduced.

It is a schematic diagram which shows the example of the cutting tool which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the state of the cutting process using the cutting tool shown in FIG. 1. It is a schematic diagram which shows the example of the cutting tool which concerns on 2nd Embodiment of this invention. It is a photograph which shows the example of the chip when the cutting tool which concerns on this embodiment is used. It is a photograph which shows the example of the chip when the cutting tool which concerns on the conventional embodiment is used.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 (a) is a front view (schematic view) showing an example of the cutting tool 1 (1A) according to the present embodiment, and FIG. 1 (b) is a bottom view (schematic view) thereof. (C) is an enlarged view of part A in FIG. 1 (a). In all the drawings for explaining the embodiment, the members having the same function may be designated by the same reference numerals, and the repeated description thereof may be omitted.

The cutting tool 1 according to the present embodiment is a cutting tool having a cutting edge portion for further cutting the outer peripheral portion of a prepared hole formed in a work, such as a reamer or a stepped drill. Here, the work is not particularly limited, and an example thereof includes mechanical device parts such as a caliper body attached to an automobile or a motorcycle.

(First Embodiment)
First, the first embodiment of the present invention will be described. As shown in FIGS. 1 and 2, the cutting tool 1 is an example configured as a reamer 1A. That is, it is used for machining to further cut a predetermined region (cutting allowance E) of the outer peripheral portion of the prepared hole H provided in the work W.

The cutting tool 1 (1A) according to the present embodiment includes a cutting edge portion 12 at the tip portion 10a of the main body 10. The cutting edge portion 12 has a first cutting edge portion 12A on the outermost diameter portion of the main body 10 and a second cutting edge portion 12B on the inner diameter side with respect to the first cutting edge portion 12A.

Here, the second cutting edge portion 12B is a plane continuous with the first cutting edge portion 12A (in the same plane) and parallel to the central axis (axis center when rotated) C of the main body 10. It is provided as a surface.

At this time, the surface roughness of the first cutting edge portion 12A is relatively small, and the surface roughness of the second cutting edge portion 12B is relatively large, so that the friction coefficients of the respective surfaces are made different. It is composed. The method of making the friction coefficient of each surface different (method of setting the surface roughness) is not particularly limited, but for example, the first cutting edge portion 12A and the second cutting edge portion 12B are made of different materials. You may. Further, a method of making the surface roughness of the surface of the second cutting edge portion 12B different by processing can be used.

According to the above configuration, as shown in FIG. 2 (schematic diagram for explaining the state of cutting, particularly the state of chip generation), the configuration in which the friction coefficient of the surface is different, that is, the first cutting edge portion The structure in which the surface roughness of the 12A is small and the surface roughness of the second cutting edge portion 12B is large makes it possible to generate the chips D from the cutting edge portion 12 in a curled state. This is because the difference in the coefficient of friction between the first cutting edge portion 12A and the second cutting edge portion 12B causes a difference in the discharge rate between the chip portions discharged from the respective regions. More specifically, the discharge speed of the chip portion discharged from the region of the first cutting edge portion 12A having a small friction coefficient becomes faster, and the discharge speed of the chip portion discharged from the region of the second cutting edge portion 12B having a large friction coefficient becomes faster. By slowing down the speed, it is possible to obtain an action of curling the chips D on the side having a large friction coefficient (the side of the second cutting edge portion 12B).

Since the curled chip D is easily broken, the chip D is finely divided (in this example, as shown in FIG. 4 (photograph of the chip when cutting with the cutting tool according to the present embodiment)). , It can be divided into fan shapes). Therefore, it is possible to improve the dischargeability of the chips D and prevent the occurrence of a state in which the chips D are elongated for a long time. Therefore, it is possible to solve the above-mentioned problem that the elongated chip D damages the work W and the cutting tool 1.

As an application of the above-mentioned action and effect, the friction coefficient in the first cutting edge portion 12A and the second cutting edge portion 12B is appropriately set according to the material constituting the work W, so that the friction coefficient is discharged from each region. It is possible to control the discharge rate of the chip portion. That is, it is possible to optimize the shape and length of the fragment by controlling the curl state (that is, the curvature, etc.).

Next, due to the configuration in which the friction coefficient of the second cutting edge portion 12B is set to be large, a larger amount of metal powder of the chips D adheres to the cutting surface 12a of the second cutting edge portion 12B. With conventional tools, metal powder of chips adheres between the outer peripheral surface, which is not the cutting surface, and the work, which often causes deterioration of the finished state. However, in the present embodiment, more metal powder of the chips D adheres to the cutting surface 12a of the cutting edge portion 12 (here, the second cutting edge portion 12B), but the metal powder is arranged inside the outermost diameter. Therefore, the effect on the finished state is small.

Further, as compared with the configuration of the cutting edge portion provided with the rake angle as in the conventional tool, in the cutting edge portion 12 according to the present embodiment, the first cutting edge portion 12A and the second cutting edge portion 12B are continuous. The re-polishing of the cutting edge portion 12 becomes extremely easy because the structure is formed on the same surface (inside the surface of the cutting surface 12a) and as a surface parallel to the central axis C of the main body 10. Therefore, even if the cutting edge portion 12 is worn due to use, the reuse of the cutting tool 1 by re-polishing can be promoted, so that the conventional cutting tool replacement / replacement process is unnecessary and the cost is reduced. Is also possible. In the configuration of the present embodiment, as in the case of a normal tool, re-polishing can be performed as long as the diameter reduction due to the back taper is allowed.

Further, in the present embodiment, as an example, the second cutting edge portion 12B is formed in a rectangular shape, that is, the region formed as the second cutting edge portion 12B in the cutting edge portion 12 is processed into a rectangular shape. It is composed. In particular, according to the rectangular structure, it is extremely easy to form the same shape as the original shape even if it is re-polished at the time of wear. Therefore, stable cutting can be continuously performed without a slight change in the machinability before and after regrinding. However, the configuration is not limited to a rectangular shape, and various shapes such as a triangular shape, a circular shape, or a combination shape thereof can be considered (not shown).

It is preferable that the second cutting edge portion 12B is arranged in a region inside the central axial direction from the 50% point from the outermost diameter side of the cutting allowance E on the outer peripheral portion of the prepared hole H. According to this, the area occupied by the second cutting edge portion 12B in the cutting allowance E can be reduced, which is effective in solving the following problems. That is, since the surface roughness of the second cutting edge portion 12B is relatively large and the coefficient of friction is large, the resistance force received from the work W during cutting becomes large, wear is promoted, and the maintenance cycle is shortened. At the moment when the reamer comes into contact with the work (at the time of biting, at the time of approaching), it is shaken by the resistance and there is a problem that the quality becomes poor. Further, when the cutting edge portion 12 is worn, there arises a problem that the finished state of the cutting process is also deteriorated. These problems can also be solved by adopting the above configuration.

(Second embodiment)
Subsequently, a second embodiment of the present invention will be described. As shown in FIG. 3, this is an example in which the cutting tool 1 is configured as a stepped drill 1B. That is, it is used for processing in which a predetermined area (cutting allowance) of the outer peripheral portion of the prepared hole is further cut by the intermediate stepped drill shoulder portion 11B while the prepared hole is formed in the work W by the drill portion 11A at the tip. 3A is a front view (schematic view) showing an example of the cutting tool 1 (1B) according to the present embodiment, and FIG. 3B is a bottom view (schematic view) thereof. FIG. 3 (c) is an enlarged view of part B in FIG. 3 (a).

The cutting tool 1 according to the present embodiment has the same basic configuration as the first embodiment described above, but has differences in the arrangement position of the cutting edge portion 12 and the like. Hereinafter, the present embodiment will be described with a focus on the differences.

The cutting tool 1 (1B) according to the present embodiment includes a drill portion 11A at the tip portion 10a of the main body 10. Further, the stepped portion 10b at the intermediate position in the axial direction is provided with the stepped drill shoulder portion 11B.

Here, in the case of the present embodiment, the cutting edge portion 12 is provided on the stepped drill shoulder portion 11B. The basic configuration of the cutting edge portion 12 is the same as that of the first embodiment described above.

Since the action and effect obtained by the cutting tool 1 (1B) having the above configuration is the same as that of the first embodiment described above, the repeated description will be omitted.

As described above, according to the cutting tool 1 according to the present invention, in the processing of further cutting the outer peripheral portion (cutting allowance E) of the prepared hole H formed in the work W, the generated chips D are curled and finely divided. Can be divided. Therefore, it is possible to improve the dischargeability of the chips D and prevent the chips D from extending for a long time and damaging the work W and the cutting tool 1. Further, the structure in which the cutting edge portion 12, that is, the first cutting edge portion 12A and the second cutting edge portion 12B are formed by continuous surfaces makes it extremely easy to re-polish the cutting edge portion 12. Therefore, the reuse of the cutting tool 1 can be promoted, and the cost can be reduced. In particular, it can be said that this technique has a high advantage over conventional cutting tools in that it can achieve both subdivision of chips D and facilitation of re-polishing of the cutting edge portion 12 to a high degree.

The present invention is not limited to the embodiments described above, and can be variously modified without departing from the present invention.

1, 1A, 1B Cutting tool 10 Main body 11A Drill part 11B Stepped drill Shoulder part 12 Cutting edge part 12A First cutting edge part 12B Second cutting edge part W Work

Claims (3)

A cutting tool provided with a cutting edge that further cuts the outer peripheral portion of the prepared hole formed in the work.
The cutting edge portion is provided with a first cutting edge portion on the outermost diameter portion of the cutting tool, is formed on a surface continuous with the first cutting edge portion, and is on the inner diameter side of the first cutting edge portion. A second cutting edge portion extending parallel to the central axis of the cutting tool is provided.
The surface roughness of the second cutting edge portion is formed to be larger than that of the first cutting edge portion, and the surface is formed in the central axis direction from the 50% point from the outermost diameter side of the cutting allowance with respect to the cutting allowance of the outer peripheral portion of the prepared hole. A cutting tool characterized by being formed inside. In the cutting tool according to claim 1,
The cutting tool is a cutting tool characterized by being a reamer. In the cutting tool according to claim 1,
The cutting tool is a stepped drill, and the cutting tool is characterized in that the cutting edge portion is formed on the shoulder portion of the stepped drill.

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