JP2979823B2 - Cutting tools - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool such as a boring bar and a cutting tool.

[0002]

2. Description of the Related Art As this kind of cutting tool, for example, FIG.
A boring bar as shown in FIG. 12 is known. In the boring bar shown in these figures, a cutting head 2 is provided at the tip of a cylindrical shaft-shaped tool body 1 formed of steel, cemented carbide, tool steel, powdered high-speed steel, or the like, alone or in combination. The cutting head 2 has a tip mounting seat 3 formed at the tip of the cutting head 2 and a throw-away tip 4 attached thereto. In such a boring bar, the base end of the tool main body 1 is mounted and held on a holding table 5 of a machine tool, and the work material is cut by a cutting blade 6 formed on the indexable insert 4.

[0003]

By the way, in such a cutting tool, the tool main body 1 is integrally formed, and especially when a cemented carbide, tool steel or the like is used as a material, a high tool rigidity is to be ensured. On the other hand, the stability limit is low for the vibration caused by cutting, so if the cutting condition is increased by increasing the cutting speed or increasing the cutting depth or feed rate, chatter will occur immediately and machining will occur. There is a problem that the surface is deteriorated. Further, in such a cutting tool, as the protrusion length L of the tool body 1 from the holding table 4 is increased, the stability limit against vibration is reduced. If so, there is a possibility that severe chatter vibration may occur and the cutting itself may become impossible.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problem, and is provided so as to be open at least at a tip end of a tool body along an axial direction of the tool body. A hole is formed, a rod spring is loosely inserted into the insertion hole to be supported by the tool body, and a cutting head having a cutting edge is provided at a tip of the rod spring,
Each of a pair of frictional vibration absorbing members is disposed so as to be able to abut each other on opposing surfaces of the cutting head and the tool body, and a viscoelastic material made of a viscoelastic material is provided between the insertion hole and the rod spring. It is characterized by having a layer interposed.

[0005]

In the cutting tool having such a configuration, the vibration generated by the cutting blade of the cutting head during cutting displaces the connected body of the cutting head and the rod spring to which the cutting head is attached, and propagates to the tool body. Among these, first, vibration for displacing the cutting head propagates from the contact surface between the cutting head and the tool body to the tool body. Here, in the present invention, a frictional vibration absorbing material is disposed on each of these contact surfaces, and the cutting head vibrates,
When these frictional vibration absorbing members slide and rub against each other, the vibration energy is converted into frictional heat, and the vibration that propagates to the tool body is reduced.

On the other hand, the vibration that propagates to the tool body by displacing the rod spring is attenuated by the viscoelastic layer provided between the rod spring and the insertion hole of the tool body.
Here, when a beam such as a rod spring is covered and supported by the viscoelastic layer, if the amount of coverage is the same, the beam is covered only at the center of the beam, rather than a so-called center-covered beam. It is known that a so-called divided covered beam, in which both ends are covered so that a hollow portion is formed in the center, has a larger damping action. Therefore, it is desirable that the viscoelastic layer is separately provided on the distal end side and the proximal end side of the rod spring.

[0007]

1 to 4 show an embodiment in which the present invention is applied to a boring bar. In these figures, the tool main body 11 is formed in a cylindrical shaft shape by using steel material, cemented carbide, tool steel, powdered high-speed steel, or the like individually or in part, and the tip of the tool main body 11 is formed from the tip thereof. Along the axis O, an insertion hole 12 having a circular cross section is formed substantially at the center of the tool main body 11. Also,
A mounting screw hole 13 is formed on the bottom surface of the insertion hole 12 along the axis O.

Further, the rod spring 1 is inserted into the insertion hole 12.
4 is loosely inserted. The rod spring 14 is a substantially columnar member formed of a steel material or the like, and has a male screw portion 15 formed at a base end thereof. The male screw portion 15 is screwed into the mounting screw hole 13. By doing so, the rod spring 14 is supported by the tool body 11. An adjusting screw hole 16 is formed at the tip of the rod spring 14 along the axis O. The rod spring 14
Is set smaller than the inner diameter of the insertion hole 12, so that a cylindrical space is formed between them. The length of the rod spring 14 is such that when the male screw portion 15 is screwed into the mounting screw hole 13 and the rod spring 14 is attached to the tool body 11, the tip of the rod spring 14 is It is set to protrude slightly from the tip.

Further, a cutting head 17 made of steel or the like is attached to the tip of the rod spring 14, and is positioned at the tip of the tool body 11.
The cutting head 17 is formed by screwing an adjusting screw 18 inserted into the cutting head 17 into the adjusting screw hole 16 of the rod spring 14.
4 and is adjustable in its tightening strength. Further, a tip mounting seat 19 is formed at the tip of the cutting head 17, and a throw-away tip 20 made of a hard material such as a cemented carbide is detachably mounted on the tip mounting seat 19 with a clamp screw 21. The attached cutting edge 22 formed on the indexable insert 20 is used for cutting.

Then, the base end face 17A of the cutting head 17 and the tool body 1 facing the base end face 17A
A pair of annular frictional vibration absorbers 23 are joined to the first end surface 11A, respectively. These friction dampers 23 are made of ceramic, copper or P
The adjusting screw 18 is made of a TFE material or the like.
By tightening them, they can abut each other in the direction of the axis O, and can slide relative to the axis O in the radial direction.

On the other hand, the outer periphery of the rod spring 14 and the insertion hole 12
A viscoelastic material is filled in the cylindrical space formed between the inner space and the viscoelastic layer, and viscoelastic layers 24 are formed. Here, these viscoelastic layers 24, 24 are made of a viscoelastic material such as a rubber-based material, a silicon-based material, a urethane-based material, or various adhesives. The rod spring 14 is divided and provided on the distal end side and the proximal end side, so that a cavity 25 is formed between the viscoelastic layers 24, 24.

In the boring bar having such a configuration, similarly to the conventional boring bar, the base end of the tool main body 11 is held by the holding base 26 of the machine tool and is subjected to cutting. In such cutting with a boring bar, when vibration such as chatter is applied to the cutting edge, the vibration is transmitted from the throw-away tip 20 to the cutting head 17.
To the cutting head 17 and the rod spring 1
4 is displaced in the radial direction with respect to the axis O and propagates to the tool body 11.

Here, of these vibration propagation paths,
The vibration propagating from the cutting head 17 to the tool body 11 is caused by the contact surface between the cutting head 17 and the tool body 11, that is, the frictional vibration absorber 23 joined to the base end face 17 </ b> A of the cutting head 17 and the tip face of the tool body 11. 1
The light propagates from the contact surface with the frictional damping material 23 joined to 1A. However, due to the vibration propagating through the contact surface, the frictional damping material 23,
23 is rubbed by sliding in the radial direction with respect to the axis O,
As a result, frictional heat is generated. That is,
Due to the sliding of the frictional vibration absorbing members 23, the energy of vibration is converted into thermal energy by friction, and the vibrational energy transmitted from the cutting head 17 to the tool body 11 is reduced by the converted thermal energy. As a result, the vibration of the tool body 11 is suppressed.

On the other hand, of the vibration propagation path, the vibration transmitted to the tool body 11 by displacing the rod spring 14 includes the rod spring 14 having a spring effect and the damper effect provided around the rod spring 14. The viscoelastic layers 24, 24 having the following are damped and suppressed by the suspension. By the way, when the supporting beam such as the rod spring 14 is covered with the viscoelastic layer 24 as described above, if the covering amount is the same, for example, a so-called center-covered beam covering only the central portion of the beam. With a so-called split covered beam in which the viscoelastic layer is divided and covered at both ends of the beam so that a cavity is formed in the center of the beam, the viscoelastic layer near the vibration abdomen It is known that the latter has a greater damping effect than the former because it does not contribute to dissipation. However, in the present embodiment, the viscoelastic layer 24 is divided and disposed in the insertion hole 12 at the distal end side and the proximal end side of the rod spring 14, whereby the viscoelastic layer 24 is provided between the two viscoelastic layers 24. The cavity 25 is formed, so that the vibration propagating to the rod spring 14 can be effectively attenuated.

As described above, according to the boring bar having the above-described structure, the vibration absorbing function of the frictional vibration absorbing members 23 and 23 interposed between the tool body 11 and the cutting head 17 and the rod spring 14 and the insertion hole 12 are formed. The vibration reduction effect of the viscoelastic layers 24 formed therebetween acts synergistically to effectively suppress the transmission of vibration transmitted from the indexable insert 20 to the cutting head 17 to the tool body 11 during cutting. Therefore, it is possible to improve the stability limit against vibration of the entire tool. Thus, even in high cutting conditions, the occurrence of chatter can be suppressed and the finished surface accuracy can be improved, and the protruding length L of the tool main body 11 from the holding table 27 is set large in the case of deep hole drilling or the like. Even if this is done, it is possible to perform stable cutting while preventing the occurrence of severe chatter vibration in the tool body 11.

According to the boring bar of this embodiment,
Tightening strength of the cutting head 17 to the rod spring 14, that is, the cutting head 17 side and the tool body 11
The contact pressure between the two frictional vibration absorbing members 23 and 23 can be adjusted by the adjusting screw 18, whereby the magnitude of the vibration absorbing action by the two frictional vibration absorbing members 23 and 23 can be adjusted. And, together with this, the tool body 11
The rigidity of the entire tool is adjusted by appropriately setting the shape, material, and the like of the viscoelastic layer 24, the cutting head 17, or the rod spring 14, or the material of the viscoelastic material constituting the viscoelastic layer 24 and the viscoelastic layer 24, 24. By appropriately setting the coating amount and the like, it is possible to finely adjust the vibration absorbing material 23, 23 and the viscoelastic layer 24, 24 so that the vibration absorbing function and the viscoelastic layer 24, 24 work most effectively. An optimum vibration prevention effect according to the cutting conditions and the like can be achieved.

In this embodiment, the viscoelastic layers 24, 24
Is divided and disposed at both ends of the rod spring 14 in the cylindrical space formed in the insertion hole 12. In some cases, a viscoelastic material is filled over the entire space to form the viscoelastic layer 24. It may be formed or another arrangement. In this embodiment, the insertion hole 12 is formed so as to open only at the tip of the tool body 11, and the male screw portion 15 is formed in a mounting screw hole 13 formed on the bottom surface of the insertion hole 12.
Is screwed to support the rod spring 14 on the tool body 11, but such a configuration is not necessarily required.

For example, FIG. 5 to FIG. 8 show another embodiment of the present invention, and the same reference numerals are assigned to the same parts as those in the embodiment shown in FIG. 1 to FIG. In this embodiment, an insertion hole 32 is provided so as to open at both ends of the tool main body 31 along the axis O direction of the shaft-shaped tool main body 31, and a flange portion is formed at the base end of the insertion hole 32. A rod spring 34 formed with 33 is loosely inserted. An annular supporting portion 35 is formed in the tool body 31 at the center of the insertion hole 32 in the direction of the axis O so as to protrude radially inward with respect to the axis O. The tool is inserted into the support portion 35 and is supported by the tool body 31.

In this embodiment, a pair of frictional vibration absorbing members 23 are joined to the base end face 17A of the cutting head 17 and the front end face 31A of the tool body 31 opposed to the base end face 17A in the same manner as in the conventional example. At the same time, the proximal end surface 31B of the tool body 31 and the distal end surface 33A of the flange 33 of the rod spring 34 facing the proximal end surface 31B are also provided.
A pair of other frictional vibration absorbing members 36, 36 are respectively provided in an annular shape. These other frictional vibration absorbers 36, 36 are also made of ceramics, like the above frictional vibration absorbers 23, 23.
It is made of copper or a PTFE-treated material. In this embodiment, the tool body 31 is narrowed in the direction of the axis O by the cutting head 17 and the flange 33 of the rod spring 34 by screwing the adjusting screw 18 into the adjusting screw hole 16 of the rod spring 34 and tightening. In this state, the frictional vibration absorbing members 23, 23 and the other frictional vibration absorbing members 36, 36 can abut each other in the direction of the axis O, and are relatively relative to the axis O in the radial direction. It is slidable.

Further, in this embodiment, a viscoelastic material made of a rubber-based material, a silicon-based material, a urethane-based material, or various adhesives is provided in a space between the outer periphery of the rod spring 34 and the inner periphery of the insertion hole 32. Are formed, and viscoelastic layers 37, 37 divided into a distal end side and a proximal end side of the rod spring 34 are formed, and a cavity 38 is formed between these viscoelastic layers 37, 37. Have been.

Also in the boring bar having such a configuration, the vibration transmitted from the throw-away tip 20 provided in the cutting head 17 and displacing the cutting head 17 and the rod spring 34 includes the cutting head 17 and the tool body 31. The vibration propagating from the contact surface of the rod spring 34 is reduced by the vibration absorbing action with the frictional vibration absorbing members 23, 23, and the vibration displacing the rod spring 34 is
It is attenuated by 7,37. In addition, in the present embodiment, a flange 33 is provided at the base end of the rod spring 34, and the base end surface 31B of the tool body 31 and the flange 33
The other pair of frictional vibration absorbing members 36 provided on the distal end surface 33A and abutting against each other slide and rub against each other due to the vibration of the rod spring 34, so that the vibration of the rod spring 34 is converted into frictional heat. . As described above, according to the present embodiment, the vibration of the rod spring 34 can be reduced by the vibration absorbing action of the other pair of frictional vibration absorbing members 36, 36, thereby further increasing the stability limit for the vibration of the boring bar. It can be improved.

Further, also in the present embodiment, the tightening strength of the adjusting screw 18 is adjusted to adjust the vibration absorbing effect of the frictional vibration absorbing members 23, 23 and the other frictional vibration absorbing members 36, 36, and to configure the boring bar. By appropriately setting the shape, material and the like of each member to adjust the tool rigidity, or by appropriately setting the material of the viscoelastic material and the coating amount of the viscoelastic layers 37, 37, the frictional vibration absorber 23, It is possible to finely adjust the vibration absorbing action of the viscoelastic layer 37 and the vibration absorbing action of the viscoelastic layer 37. In addition to this, in the present embodiment, the rod spring 34 is supported by the tool main body 31 by an annular support portion 35 provided in the insertion hole 32, and the number and position of the support portion 35,
Alternatively, the vibration damping action can be finely adjusted by appropriately setting the width δ of the support portion 35 and the like. For this reason, according to the present embodiment, it is possible to obtain an optimal vibration suppression effect according to a wider range of cutting conditions.

In this embodiment, the support portion 35 is provided in the insertion hole 32 of the tool main body 31 as described above. However, a configuration without such a support portion may be employed. Further, this support portion is used as the tool main body 31 as in this embodiment.
The ring need not necessarily be formed integrally with the tool body 31, but may be such that a separately formed ring is fixed to the tool body 31 or the rod spring 34. Further, in the present embodiment, the viscoelastic layer 37 is formed by dividing the rod spring 34 into the distal end side and the proximal end side. However, the viscoelastic layer 37 may be provided over the entire rod spring 34. Of the distal end, the proximal end, and the support portion 35
It may be divided into three parts with the peripheral central part or more.

[0024]

As described above, according to the present invention, the vibration absorbing effect of the frictional vibration absorbing material disposed on the contact surface between the cutting head and the tool body, and the viscoelastic layer formed around the rod spring , It is possible to improve the stability limit of the cutting tool against vibration.
Thus, even under high cutting conditions, occurrence of chatter and the like can be prevented, and the accuracy of the finished surface can be improved. In addition, the rigidity of the whole tool, the contact pressure of each friction damper,
Alternatively, by appropriately adjusting the material, arrangement, and the like of the viscoelastic material forming the viscoelastic layer, it is possible to obtain an optimal vibration suppression effect according to the cutting conditions.

[Brief description of the drawings]

FIG. 1 is a sectional view of a boring bar showing one embodiment of the present invention.

FIG. 2 is a front view of the embodiment shown in FIG. 1 as viewed from a tool tip side.

FIG. 3 is a side view of a tip of the embodiment shown in FIG. 1;

FIG. 4 is a YY sectional view of the embodiment shown in FIG. 1;

FIG. 5 is a sectional view of a boring bar showing another embodiment of the present invention.

FIG. 6 is a front view of the embodiment shown in FIG. 5 as viewed from the tool tip side.

7 is a side view of the tip of the embodiment shown in FIG.

FIG. 8 is a sectional view taken along the line ZZ of the embodiment shown in FIG.

FIG. 9 is a sectional view of a conventional boring bar.

FIG. 10 is a front view of the conventional example shown in FIG. 9 as seen from the tool tip side.

11 is a side view of the tip of the conventional example shown in FIG.

FIG. 12 is a sectional view taken along the line XX of the conventional example shown in FIG.

[Description of Signs] 1,11,31 Tool Body 2,17 Cutting Head 4,20 Throwaway Tip 12,32 Insertion Hole 14,34 Rod Spring 18 Adjustment Screw 23,36 Friction Absorbing Material 24,37 Viscoelastic Layer 25, 38 Cavity part 33 Flange part 35 Support part O Tool main body axis L Projecting length of boring bar

Claims (4)

(57) [Claims] An insertion hole is formed in the axial direction of the tool main body so as to open at least at the tip of the tool main body, and a rod spring is loosely inserted into the insertion hole to support the tool main body. A cutting head having a cutting blade is provided at the tip of the rod spring, and a pair of frictional vibration absorbers abut each other on opposing surfaces of the cutting head and the tool body. A cutting tool, wherein the cutting tool is provided so as to be capable of being provided, and a viscoelastic layer made of a viscoelastic material is interposed between the insertion hole and the rod spring. 2. The viscoelastic layer is disposed in the insertion hole and divided into a distal end side and a proximal end side of the rod spring, and a cavity is formed between these viscoelastic layers. The cutting tool according to claim 1, wherein the cutting tool is provided. 3. The insertion hole is opened at both ends of the tool main body, and a flange is formed at a base end of the rod spring. The cutting tool according to claim 1, wherein each of the other pair of frictional vibration absorbers is disposed on the facing surface. 4. The cutting tool according to claim 1, wherein the insertion hole is provided with a support portion that contacts the outer periphery of the rod spring and supports the rod spring.