JP2000052126A - Cutting part replaceable cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce generation of chattering vibration during cutting by increasing the rigidity of a cutting part replaceable cutting tool. SOLUTION: A cylindrical projected part 15 and a fitting-projected part 16 are respectively formed at the rear end of a cutting part 10 and at the top of a shank 11 so that they are coaxial with an axis P of a tool body 9. First and second clamping holes 18, 19 respectively having specified interferences in relation to the outside diameters of the projected part 15 and the fitting- projected part 16 are formed in a connecting member 12. The first clamping hole 18 and the projected part 15, and the second clamping hole 19 and the fitting-projected part 16, are respectively interference-fitted to fix the cutting part 10 and the shank part 11. The cutting part 10 and the shank part 11 are manufactured using a material having lower expansion coefficient and higher rigidity than those of the connecting member 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool with a replaceable blade, the blade of which is detachable.

[0002]

2. Description of the Related Art Heretofore, with regard to a cutting tool having a replaceable blade portion, a protruding portion is formed on one of a blade portion and a shank portion, and the other protrudes from the protruding portion. It is known that a clamp hole having a predetermined interference is formed, and a blade portion and a shank portion are fixed by utilizing an interference fit between the convex portion and the clamp hole.

FIG. 5 is a side view of a ball end mill which is an example of the above-mentioned blade-part-replaceable cutting tool, in which a connecting portion between a blade and a shank is cut away.
And the shank 3.

The blade portion 2 is made of a high-rigidity cemented carbide, and has a tip portion 4 and a shaft portion 5 in order from the tip side to the base end (rear end) side in the direction of the axis O of the tool body. And the convex portion 6. The tip 4 is a part directly involved in cutting, and is provided with a cutting blade (not shown). The shaft portion 5 is formed in a columnar shape coaxial with the axis O. The convex portion 6 has a smaller diameter than the shaft portion 5 in an appropriate dimension and is formed in a cylindrical shape coaxial with the axis O, and the length in the axis O direction is set to a predetermined value.

The shank portion 3 is made of steel and has a larger expansion coefficient than the blade portion 2. The shank portion 3 is formed in a cylindrical shape coaxial with the axis O, has an outer diameter equal to that of the shaft portion 5 of the blade portion 2, and extends from the distal end face 7 toward the base end side along the axis O.
And a clamp hole 8 is provided coaxially. Clamp hole 8
Is set so that its inner diameter has a predetermined interference with respect to the outer diameter of the convex portion 6 of the blade portion 2, and in the direction of the axis O,
The length is formed to be the same as or slightly deeper than the length of the convex portion 6.

[0006] In the cutting tool with the replaceable blade portion having the above configuration,
To connect the blade 2 and the shank 3, first, the shank 3 is heated and the clamp hole 8 is thermally expanded until the protrusion 6 of the blade 2 can be inserted. The protrusion 6 is inserted. Next, when the shank portion 3 is cooled, the clamp hole 8 is thermally contracted and the convex portion 6 is tightened, and the fixing of the blade portion 2 is completed. On the other hand, when removing the blade portion 2 from the shank portion 3, the blade portion 2 is removed by heating the shank portion 3 and thermally expanding the clamp hole 8 until the protrusion 6 can be extracted.

[0007]

In the cutting tool having the above-mentioned construction, the shank portion in which the clamp hole is formed is formed as follows.
It is necessary to manufacture with a material having a larger coefficient of expansion than the blade part on which the convex part is formed, and a material with a large coefficient of expansion has low rigidity, so the rigidity of the shank part is low, and chatter vibration is likely to occur during cutting. There is a problem.

The present invention has been made in view of the above circumstances, and is a cutting tool for connecting a blade portion and a shank portion using an interference fit, wherein the shank portion is made of a highly rigid material. It is an object of the present invention to provide a cutting tool with a replaceable blade portion.

[0009]

According to a first aspect of the present invention, there is provided a cutting tool according to the present invention, wherein a blade portion and a shank portion are detachably fixed via a connecting member. A cutting tool, wherein a convex portion is formed at the rear end of the blade portion, and the connecting member is made of a material having a larger expansion coefficient than the blade portion and the shank portion. On the other hand, a hole is provided so as to have a predetermined interference, and the convex portion of the blade portion is inserted into the hole of the connecting member and fixed in a tightly fitted state. .

According to such a configuration, the hole provided in the connecting member is thermally expanded and contracted by heating and cooling the connecting member to connect the hole with the blade portion having the convex portion. The material of the portion and the shank portion may be a material having a smaller expansion coefficient than that of the connecting member. Here, for example, by manufacturing the blade portion and the shank portion with a high-rigidity cemented carbide, it is possible to perform heavy cutting of a difficult-to-cut material and increase the rigidity of the cutting tool. It is possible to reduce occurrence of chatter vibration.

The cutting tool according to the second aspect of the present invention is a blade-replaceable cutting tool in which a blade portion and a shank portion are detachably fixed via a connecting member. The connecting member is made of a material having a larger expansion coefficient than the blade portion and the shank portion, and has a hole so as to have a predetermined interference with the convex portion of the shank portion. Is provided, and the protruding portions of the blade portion and the shank portion are inserted into holes of the connecting member so as to face each other in the axial direction, and are fixed in a tightly fitted state. And

According to such a configuration, in addition to making the blade part detachable, the connecting member can also be made detachable with respect to the shank part, so that the material of the blade part and the shank part is connected. A material having a smaller expansion coefficient than that of the member can be adopted, and the connecting member can be replaced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a side view showing an embodiment of a cutting tool having a replaceable blade portion according to the present invention, in which a connecting portion between a blade portion and a shank portion is cut away.
Is constituted by a blade portion 10, a shank portion 11, and a connecting member 12 for connecting these in the direction of the axis P.

The blade 10 is made of, for example, a cemented carbide,
In the direction of the axis P, in order from the distal end side to the base end (rear end) side, a substantially hemispherical distal end portion 13, a substantially cylindrical axial portion 14 coaxial with the axis P, and a convex portion 15 are provided. It is configured. The tip portion 13 is a part directly participating in cutting, and a cutting edge (not shown) is formed in, for example, a substantially 1/4 arc shape. The convex portion 15 is a portion that serves to connect with the connecting member 12, and has a smaller diameter than the shaft portion 14 in an appropriate size and is formed in a coaxial cylindrical shape.

The shank portion 11 is made of, for example, a cemented carbide, and has a larger outer diameter than the fitting convex portion 16 and the shaft portion 14 in order from the distal end side to the proximal end side in the direction of the axis P. Further, it is constituted by a cylindrical shaft portion 17 coaxial with the axis P. The fitting convex portion 16 is a portion that serves to connect with the connecting member 12, has a smaller diameter than the cylindrical shaft portion 17 in an appropriate size, and is formed in a coaxial cylindrical shape.

The connecting member 12 is made of a material having a larger expansion coefficient than that of the blade portion 10 and the shank portion 11, for example, steel, and has a substantially conical outer peripheral surface. The outer diameter of the base end is equal to the outer diameter of the cylindrical shaft 17 of the shank 11. A first clamp hole (hole) 18 formed from the distal end side and a second clamp hole (hole) 19 formed from the proximal end side are provided on the inner peripheral surface of the connecting member 12 along the axis P. The center of the diameter of each of the clamp holes 18 and 19 is made to coincide with the axis P, and the first clamp hole 18 penetrates the second clamp hole 19 at an appropriate position in the direction of the axis P, It has a stepped shape. Here, the depth of the first and second clamp holes 18 and 19 in the direction of the axis P is set to be equal to or slightly longer than the protrusion 15 of the blade 10 and the fitting protrusion 16 of the shank 11, respectively. Have been.

The inner diameter of the first clamp hole 18 is set slightly smaller than the outer diameter of the convex portion 15 of the blade portion 10 so as to have a predetermined interference, and the inner diameter of the second clamp hole 19 is set in the shank portion 11. The first clamp hole 18 and the convex portion 15, and the second clamp hole 19 and the fitting convex portion 16 are set so as to have a predetermined interference with respect to the outer diameter of the mounting convex portion 16. Are fixed in an interference-fitted state.

Here, the value of the interference is, for example, 0.
By setting the thickness in the range of 005 mm to 0.100 mm, the internal stress caused by interference fit does not become excessive.

The cutting tool according to the present embodiment has the above-described configuration. Next, a method of attaching and detaching the blade portion 10 to and from the shank portion 11 via the connecting member 12 will be described.

First, when attaching the blade portion 10 to the shank portion 11, the connecting member 12 is heated to
The first and second clamp holes 18 and 19 are thermally expanded until the fitting protrusion 16 of the shank portion 5 and the shank portion 11 can be inserted. 15 and the fitting projection 16 are inserted.

Next, when the connecting member 12 is cooled, the first and second clamp holes 18 and 19 are thermally contracted.
The convex portion 15 of 0 and the fitting convex portion 16 of the shank portion 11 are firmly tightened with a predetermined interference, and the fixing of the blade portion 10 and the shank portion 11 is completed.

On the other hand, when the blade portion 10 is to be removed from the shank portion 11, the connecting member 12 is heated to thermally expand the first and second clamp holes 18, 19, so that the convex portion 15 of the blade portion 10 is formed.
Then, each of the fitting projections 16 of the shank portion 11 is removed. Here, the connecting member 12 includes the blade portion 10 and the shank portion 1.
Since the expansion coefficient is larger than 1, even when the heat due to the above-mentioned heat is transmitted to the blade portion 10 and the shank portion 11, it is possible to remove them.

According to the cutting tool of the present embodiment, as long as the material has a smaller expansion coefficient than the material of the connecting member 12, the cutting portion 10 and the shank portion 11 can be freely combined.
Material can be selected. For this reason, in particular, by manufacturing the shank portion 11 from, for example, a high-rigidity cemented carbide, the rigidity of the tool main body 9 can be increased, and the occurrence of chatter vibration during cutting can be reduced.

Also, as a problem in the interference fitting, a member having a clamp hole may be damaged due to excessive internal stress when tightened with a convex portion, and thermal expansion and thermal contraction are repeated. In such a member, fatigue may be accumulated in the material, and the life of the member may be shortened.
Here, in the cutting tool having the above-described configuration, the above-described problem spreads only to the connection member 12 that is inexpensive in terms of material and structure as compared with the blade portion 10 and the shank portion 11. This has been effective in reducing costs.

FIG. 2 shows a first modification of the cutting tool with replaceable blades according to the first embodiment. As shown in FIG. 2, the convex portion 15 of the blade portion 10 and the fitting convex portion 1 of the shank portion 11 are provided.
6 may have the same outer diameter, and the first and second clamp holes 18 and 19 of the connecting member 12 may have the same inner diameter. Further, the second modification shown in FIG. like,
The outer diameter of the distal end and the proximal end of the connecting member 12 may be the same, and the connecting member 12 may have a cylindrical shape. in short,
Clamp holes 18 and 19 having a predetermined interference are provided coaxially with the axis P with respect to the respective outer diameters of the protrusion 15 of the blade 10 and the fitting protrusion 16 of the shank 11 in the connecting member 12. It should just be done.

Next, a description will be given of a second embodiment of the blade-exchangeable cutting tool according to the present invention with reference to FIG. FIG.
FIG. 4 is a side view showing a second embodiment of the blade-exchangeable cutting tool according to the present invention, in which a connecting portion between a blade and a shank is cut away. The same parts as those in the first embodiment described above include:
The same reference numerals are given and the description is omitted.

The tool body 20 of the ball end mill according to the present embodiment comprises the blade portion 10, the shank portion 21, and a connecting member 22 for connecting these in the direction of the axis P.

The shank portion 21 is made of, for example, a cemented carbide, and has an outer diameter larger than that of the fitting convex portion 23 and the shaft portion 14 of the blade portion 10 in order from the distal end to the proximal end in the direction of the axis P. Is large and is coaxial with the axis P.
And is constituted by. The fitting projection 23 is a connecting member 2
2 and is formed in a conical shape coaxial with the axis P.

The connecting member 22 is made of a material having a larger expansion coefficient than the blade portion 10 and the shank portion 21, for example, steel, and has an outer peripheral surface formed in a tapered shape. The outer diameter of the base end is made equal to the outer diameter of the cylindrical shaft portion 24 of the shank portion 21. A clamp hole 26 is provided coaxially with the axis P from the distal end surface 25 toward the base end side, and the inner diameter of the clamp hole 26 has a predetermined interference with the outer diameter of the convex portion 15 of the blade portion 10. The length of the projection 15 is set to be slightly smaller than that of the projection 15 in the direction of the axis P, and the clamp hole 26 and the projection 15 are fixed in a tightly fitted state. The conical recess 2 is coaxial with the axis P so that the fitting protrusion 23 of the shank portion 21 is fitted to the base end.
7 is formed, and the fitting projection 23 of the shank 21 is fitted and fixed by brazing.

The cutting tool according to the present embodiment has the above-described configuration. By heating and cooling the connecting member 22, the clamp hole 26 thermally expands and contracts, and the protrusion 15 of the blade 10 is formed. It is removable.

In the above-described first and second embodiments, the material of the blade portion 10 and the shank portions 11 and 21 is made of cemented carbide. However, the material is not limited to this, and the blade portion 10 may be made of cermet, high speed steel or the like. The shank portions 11 and 21 may be a cermet or a high-hardness sintered body.

In the first and second embodiments described above, the shapes of the projection 15 of the blade 10 and the fitting projection 16 of the shank 11 are columnar. An appropriate shape such as a column shape can be applied. In this case, the connecting member 1
The clamp holes 18 and 19 of the second and the clamp holes 26 of the connecting member 22 may have a corresponding shape such as a prismatic shape.

In the present embodiment, the ball end mill has been described. However, the present invention can be applied to other cutting tools such as a rolling tool and a turning tool.

[0034]

As described above, according to the cutting tool of the present invention, the blade portion and the shank portion are fixed along the axis of the tool body by the interference fit via the connecting member. Since the blade portion is detachable by the thermal expansion and thermal contraction of the connecting member, a material having a smaller expansion coefficient than the connecting member can be used for the material of the blade portion and the shank portion, and the rigidity is high. By selecting a material, occurrence of chatter vibration during cutting can be reduced.

Further, according to the cutting tool of the present invention, the cutting portion and the shank portion are fixed along the axis of the tool main body by an interference fit via the connecting member. The blade and shank are removable due to the thermal expansion and contraction of the blade, so the blade and shank can be made of a material with a lower expansion coefficient than that of the connecting member, and a material with high rigidity should be selected. This can reduce the occurrence of chatter vibration at the time of cutting and can make the connecting member replaceable.

[Brief description of the drawings]

FIG. 1 is a side view of a first embodiment of an exchangeable cutting tool according to the present invention, in which a connecting portion between a blade and a shank is cut away.

FIG. 2 is a side view of a first modification of the blade-exchangeable cutting tool shown in FIG.

FIG. 3 is a side view of a second modification of the blade-exchangeable cutting tool shown in FIG. 1 with a connecting portion between a blade and a shank broken away.

FIG. 4 is a side view of a second embodiment of the blade-exchangeable cutting tool according to the present invention, in which a connecting portion between a blade and a shank is cut away.

FIG. 5 is a side view of a conventional blade-exchangeable cutting tool, in which a connecting portion between a blade and a shank is cut away.

[Explanation of symbols]

 9 Tool Body 10 Blade 11 Shank 12 Connection Member 15 Convex 16 Fitting Convex 18 First Clamp Hole 19 Second Clamp Hole P Axis of Tool Body

Claims (2)

[Claims] 1. A blade-exchangeable cutting tool in which a blade portion and a shank portion are detachably fixed via a connecting member, wherein a convex portion is formed at a rear end of the blade portion. The connecting member is made of a material having a larger expansion coefficient than the blade portion and the shank portion, and is provided with a hole so as to have a predetermined interference with the convex portion. A cutting tool with an exchangeable blade portion, wherein the cutting tool is inserted into a hole of the connecting member and fixed in a tightly fitted state. 2. A protruding portion is formed at a tip of the shank portion, and a hole is provided in the connecting member so as to have a predetermined interference with the protruding portion of the shank portion. 2. The projection according to claim 1, wherein the protruding portions of the blade portion and the shank portion are inserted into holes of the connecting member so as to face each other in the axial direction, and are fixed in a tightly fitted state. An exchangeable cutting tool as described.