JP2023136201A - Tool holder and machine tool - Google Patents

Abstract

To provide a versatile tool holder which has vibration suppression effect while keeping workability equivalent to those of convention structures, and to provide a machine tool.SOLUTION: A high-damping tool holder 31 includes: a fixing part 32 which may be fixed to a lathe 20 and having a tool insertion hole 3; and a damping part 33 which is incorporated into the fixing part 32, includes an elastic part 35 having rigidity lower than that of the fixing part 32, and may press a tool 22 inserted into the tool insertion hole 3 with an arbitrary pressure from the radial outer side of the tool 22.SELECTED DRAWING: Figure 6

Description

The present disclosure relates to a tool holder used to suppress vibrations generated in the tool during machining in a machine tool that performs machining while moving a tool and a workpiece relative to each other, and a machine tool equipped with the tool holder.

In a machine tool that cuts into a rotatable workpiece and moves the tool and workpiece relative to each other while feeding the workpiece to process the workpiece, when the tool is used with a large overhang such as in boring, the tool The decrease in rigidity can cause large machining vibrations (hereinafter referred to as chatter), which can lead to problems such as tool breakage and poor machined surface quality. Therefore, as a conventional technique for suppressing this chatter, for example, Non-Patent Document 1 discloses an invention that improves the holding rigidity of a slotted tool holder. Further, Patent Document 1 discloses an invention in which a mechanism for generating friction with a tool is attached to a tool holder to improve damping performance by adding friction damping.

"The ultimate anti-vibration tool" Silent Tools SANDVIK Electronic Catalog page 4 "How to clamp the tool tool", [Retrieved February 14, 2020], Internet <https://www.sandvik.coromant.com/ SiteCollectionDocuments/downloads/jp/brochures/CG-036J-R2_SilentTools.pdf＞

Patent No. 5728824

However, while the method of Non-Patent Document 1 can be used for general purposes without being restricted by the tools used or machining conditions, the effect is limited to vibration suppression due to improved holding rigidity. In addition, while the method of Patent Document 1 can provide a vibration suppression effect for all tools, it requires adjustment every time the tool is attached or detached, and the vibration suppression mechanism is located outside the tool holder, where chips are likely to adhere. There are issues with workability.

Therefore, the present disclosure was made in view of the above problems, and aims to provide a tool holder and a machine tool that are general-purpose and have a vibration suppressing effect while maintaining workability similar to conventional structures. It is.

In order to achieve the above object, a first configuration of the present disclosure is a tool holder provided in a machine tool and provided with a tool insertion hole capable of holding a tool,
a fixing part that can be fixed to the machine tool and has the tool insertion hole;
a damping part that includes a part that is built into the fixing part and has lower rigidity than the fixing part, and can press the tool inserted into the tool insertion hole with an arbitrary pressure from the outside in the radial direction of the tool; It is characterized by being prepared.
In the present disclosure, "the radial direction of the tool" includes not only the exact radial direction of the tool but also the radial direction inclined toward the axial direction of the tool.
Another aspect of the first configuration is that in the above configuration, the damping part includes a connecting part connected to the fixed part and a part connected to the connecting part and having the low rigidity, and the damping part is in contact with the tool. and a tool contact portion that presses the tool.
Another aspect of the first configuration is that in the above configuration, the tool contacting part includes an elastic part connected to the connecting part and a rigid part connected to the elastic part and contacting the tool. , the elastic part has lower rigidity than the fixed part, and the rigid body part has higher rigidity than the elastic part.
Another aspect of the first configuration is that in the above configuration, the tool contact portion protrudes from the inner diameter surface of the tool insertion hole, and the protrusion surface has a protruding amount from the inner diameter surface of the tool. It is characterized by a slope that is larger on the rear end side than on the front end side.
In order to achieve the above object, a second configuration of the present disclosure is a machine tool, and is characterized by being provided with the tool holder described in any one of the first configurations.

According to the present disclosure, it is possible to obtain a generally high vibration suppression effect for all tools. In addition, after the damping part is connected to the fixed part, the damping part is automatically pressed against the tool, so there is no need to make adjustments every time the tool is attached or removed.Furthermore, the damping part is built into the fixed part. This also reduces the possibility of chips adhering to the damping part. Therefore, it is possible to maintain the same workability as existing tool holders. As described above, it is possible to provide a general-purpose high vibration suppressing effect to tools without impairing workability.

FIG. 2 is a schematic configuration diagram showing the configuration of an existing tool holder. FIG. 2 is a schematic configuration diagram of a section taken along the line AA in FIG. 1; It is a schematic block diagram showing the structure of a high damping tool holder. FIG. 3 is a schematic configuration diagram showing the configuration of a damping section built into the high damping tool holder. 4 is a schematic configuration diagram showing the state of the high damping tool holder before the tool is attached, taken along the line BB in FIG. 3. FIG. FIG. 4 is a schematic configuration diagram showing the state of the high damping tool holder after the tool is attached, taken along the line BB in FIG. 3;

First, the structure of the existing tool holder 1 will be explained based on the drawings.
FIG. 1 is a schematic configuration diagram showing the configuration of a tool holder 1. As shown in FIG. FIG. 2 is a schematic configuration diagram showing a section taken along the line AA in FIG. Here, the tool holder 1 is applied to a turning turret 21 of a lathe 20, which is an example of a machine tool. The tool 22 held by the tool holder 1 has a substantially circular cross section and is provided with a tip 23 at its tip. For convenience, the distal end side (chip 23 side) of the tool 22 in FIG. 1 will be described as the front, and the upper side of the tool holder 1 will be described as the upper side.
The tool holder 1 includes a holder body 2 fixed to a mounting surface of a rotating turret 21. A tool insertion hole 3 having an inner diameter larger than the diameter of the tool 22 is formed through the holder body 2 in the front-rear direction. On the left and right sides of the holder body 2 with the tool insertion hole 3 in between, three holder fixing bolts 11, 11, . Above the tool insertion hole 3 and in the center of the holder main body 2 in the left-right direction, two tool fixing bolts 12, 12 are screwed in the front and rear.

When holding the tool 22 in this tool holder 1, after fixing the holder main body 2 to the rotating turret 21 using the holder fixing bolt 11, the tool 22 is inserted from the rear end with the tool fixing bolt 12 loosened. Insert into insertion hole 3. Subsequently, the tool fixing bolt 12 is tightened while adjusting the amount of protrusion from the holder main body 2, and the tool 22 is pressed against the inner diameter surface of the tool insertion hole 3 facing the tool fixing bolt 12. Thereby, the tool 22 is fixed to the holder body 2 in a state of protruding from the tool insertion hole 3.

Next, embodiments of the present disclosure will be described based on the drawings. However, the same components as those in FIGS. 1 and 2 are given the same reference numerals, and redundant explanations will be omitted.
FIG. 3 is a schematic configuration diagram showing the configuration of a high damping tool holder 31, which is an example of the tool holder of the present disclosure. FIG. 4 is a schematic configuration diagram showing the configuration of the damping section 33 built into the high damping tool holder 31. As shown in FIG. FIG. 5 is a schematic configuration diagram showing the state of the high-damping tool holder 31 before the tool is attached in the BB cross-sectional portion (cross-section defined by the front-rear, up-down direction) in FIG. 3 (the cross-section is shown with diagonal lines). . FIG. 6 is a schematic configuration diagram showing the state of the high damping tool holder 31 after the tool is attached, in the same cross section as in FIG. 5 of the tool insertion hole 3 of FIG.

The high damping tool holder 31 includes a fixing part 32 and a damping part 33. The fixing part 32 is fixed to the rotating turret 21 by the holder fixing bolt 11, like the tool holder 1 in FIG. 1, and the tool 22 inserted into the tool insertion hole 3 can be fixed by the tool fixing bolt 12.
The damping section 33 is built into the fixed section 32. The damping section 33 includes a connecting section 34, an elastic section 35, a rigid section 36, and a connecting section bolt 37. The connecting portion 34 is bonded to an elastic portion 35, and the elastic portion 35 is bonded to a rigid body portion 36, respectively. The connecting portion 34 is connected to the fixed portion 32 by a connecting portion bolt 37. Thereby, the damping part 33 is built into the fixed part 32 and becomes in a state where it can come into contact with the tool 22 inserted into the tool insertion hole 3. The elastic portion 35 and the rigid portion 36 form a tool contact portion 38 .

The elastic part 35 is made of a material (rubber or synthetic resin) with lower rigidity than the fixing part 32 and the connecting part 34, and deforms while generating a repulsive force when force is applied to the damping part 33. The front, rear, left, and right outer surfaces of the elastic portion 35 are in contact with the inner surface of the fixing portion 32 that accommodates the damping portion 33 .
The upper surface of the rigid body portion 36 is a concave curved surface along the inner diameter surface of the tool insertion hole 3 and protrudes from the inner diameter surface of the tool insertion hole 3. However, in the rigid body part 36, when the damping part 33 is fixed to the fixed part 32, the amount of radial protrusion of the front end inner diameter 41 from the inner diameter surface of the tool insertion hole 3 is equal to the inner diameter of the tool insertion hole 3 and the tool 22. It is set to be less than or equal to the difference from the outer diameter of Furthermore, on the protruding surface of the rigid body part 36, the amount of protrusion of the rear end inner diameter 42 from the inner diameter surface of the tool insertion hole 3 is larger than the amount of protrusion of the front end inner diameter 41 from the inner diameter surface of the tool insertion hole 3. A slope is provided that slopes downward toward the front so that the distance increases. Furthermore, gaps are provided between the front, rear, left, and right outer surfaces of the rigid body portion 36 and the inner surface of the fixing portion 32 .

With this configuration, even when the damping part 33 is fixed to the fixed part 32, the rear end of the tool 22 does not come into contact with the front end surface of the rigid body part 36 when the tool 22 is inserted into the tool insertion hole 3. Furthermore, when the rear end of the tool 22 comes into contact with the sloped upper surface of the rigid body part 36, the elastic part 35 deforms radially outward, so that it is possible to continue inserting the tool 22.
Finally, as shown in FIG. 6, by tightening the tool fixing bolt 12, the tool 22 pushes the rigid body part 36 radially outward, and the elastic part 35 further deforms. Therefore, the tool 22 and the damping portion 33 are brought into close contact with each other with a pressure that allows relative vibration when chatter occurs.

The high damping tool holder 31 configured as described above is attached to the rotating turret 21 via the fixing part 32, and when the tool 22 is fixed in the tool insertion hole 3, the tool 22 is fixed with high rigidity.
In the lathe 20, the tool 22 cuts into the workpiece while rotating it, and the tool 22 and the workpiece are moved relative to each other while being fed to machine the workpiece.
If chatter occurs during this machining, friction damping due to the relative vibration generated between the rigid body part 36 and the tool 22, friction damping due to the relative vibration generated between the elastic part 35 and the fixed part 32, Internal friction damping is provided by its own deformation. Thereby, the position of the tool 22 does not change due to the firm fixation of the fixing part 32, and chatter can be suppressed by the damping effect of the damping part 33.

In this way, the high damping tool holder 31 of the above configuration can be fixed to the lathe 20 and includes a fixing part 32 having the tool insertion hole 3 and an elastic part built in the fixing part 32 and having lower rigidity than the fixing part 32. 35, and a damping portion 33 capable of pressing the tool 22 inserted into the tool insertion hole 3 from the outside in the radial direction of the tool 22 with an arbitrary pressure.
According to this configuration, it is possible to obtain a generally high vibration suppressing effect for all tools. Furthermore, after the damping section 33 is connected to the fixed section 32, the damping section 33 is automatically pressed against the tool 22, so there is no need to make adjustments every time the tool 22 is attached or detached. Furthermore, since the damping part 33 is built into the fixed part 32, the possibility that chips will adhere to the damping part 33 is also reduced. Therefore, it is possible to maintain the same workability as existing tool holders. That is, according to the high-damping tool holder 31, it is possible to provide a high general-purpose vibration suppressing effect to the tool 22 without impairing workability.

The damping part 33 includes a connecting part 34 connected to the fixed part 32, a low-rigidity elastic part 35 connected to the connecting part 34, and a tool contacting part 38 that contacts the tool 22 and presses the tool 22. It consists of
Therefore, the damping part 33 can easily press the tool 22 from the outside in the radial direction inside the fixed part 32.
The tool contact part 38 is composed of an elastic part 35 connected to the connecting part 34 and a rigid part 36 connected to the elastic part 35 and in contact with the tool 22. The elastic part 35 is lower than the fixed part 32. The rigid body part 36 has higher rigidity than the elastic part 35.
Therefore, the pressing force by the elastic part 35 can be applied to the tool 22 via the rigid part 36, and the magnitude of the pressing force acting on the tool 22 can be determined by the material and shape of the elastic part 35, the shape of the rigid part 36, It can be adjusted by the tightening torque of the tool fixing bolt 12, etc.
The tool contact portion 38 protrudes from the inner diameter surface of the tool insertion hole 3, and the protrusion surface has a shape such that the amount of protrusion from the inner diameter surface is larger on the rear end side than on the front end side of the tool 22. A slope is provided.
Therefore, the rear end portion of the tool 22 can be pressed and fixed with a larger pressing force than the front end portion.

Note that the configuration of the high-damping tool holder 31 of the present disclosure is not limited to the aspects described in the embodiments above, and may be modified as necessary without departing from the spirit of the present disclosure. can.
For example, in the above embodiment, the damping part 33 is located between the two rows of holder fixing bolts 11 and the two tool fixing bolts 12, but the damping part 33 and the holder fixing bolts 11 and the tool fixing bolts 12 The positional relationship with can be changed. As an example, the damping portion 33 can be provided closer to the tool tip than the tool fixing bolt 12. In this case, although the static rigidity at the tip of the tool decreases and machining accuracy decreases, the relative displacement generated in the damping portion 33 increases, so higher damping performance can be obtained.
Further, the front end of the tool fixing bolt 12 may be provided with a resin material such as copper alloy or urethane. By providing a low-rigidity material at the front end of the tool fixing bolt 12 in this manner, the damping effect can be further enhanced.

In the above embodiment, the damping part 33 is provided below the fixed part 32 in order to avoid chips and cutting fluid, but it may be located at any position on the fixed part 32. As an example, a damping part 33 can be provided on the side surface of the fixing part 32. In this case, although the durability is reduced, the damping section 33 can be replaced even with the high damping tool holder 31 attached, so higher workability can be obtained.
The direction in which the damping portion 33 presses the tool 22 is not limited to strictly from the outside in the radial direction of the tool 22. The damping portion 33 may press the tool 22 from the outside in the radial direction, which is slightly tilted back and forth in the axial direction of the tool 22.
In the embodiment described above, the entire rigid body portion 36 is provided with a slope, but the edge portion of the front end inner diameter 41 may be chamfered to provide a slope only in a portion.
In the above embodiment, the rigid body part 36 is provided with a slope, but the damping performance is reduced due to the pressure drop between the tool 22 and the rigid body part 36. may be pressed against the damping portion 33.

On the other hand, if the cutting fluid adheres to the elastic portion 35, there is a risk that the elastic portion 35 will deteriorate due to chemical action. Furthermore, there is a risk that the elastic portion 35 will wear out if it comes into contact with the tool 22 or the like.
Therefore, the sealing performance of the damping part 33 may be improved by providing an O-ring, packing, or the like on the contact surface between the connecting part 34 and the fixed part 32 or in the gap between the rigid body part 36 and the fixed part 32. When the sealing performance is improved in this way, cutting fluid is less likely to adhere to the elastic portion 35, and deterioration of the elastic portion 35 due to adhesion of cutting fluid is suppressed. Further, since the elastic part 35 does not come into direct contact with the tool 22, wear of the elastic part 35 can be effectively prevented.
Rigid body portion 36 is not essential. Although the durability is greatly reduced, the elastic part 35 and the tool 22 may be brought into direct contact without providing the rigid part 36.
In addition, the tool holder of the present disclosure can be applied to machine tools other than lathes.

1...Tool holder, 2...Holder body, 3...Tool insertion hole, 11...Holder fixing bolt, 12...Tool fixing bolt, 20...Lathe, 21...Swivel turret, 22...Tool , 23...Tip, 31...High damping tool holder, 32...Fixed part, 33...Dampening part, 34...Connecting part, 35...Elastic part, 36...Rigid body part, 37...For connecting part Bolt, 38...Tool contact part, 41...Inner diameter on front end side, 42...Inner diameter on rear end side.

Claims (5)

A tool holder provided in a machine tool and equipped with a tool insertion hole capable of holding a tool,
a fixing part that can be fixed to the machine tool and has the tool insertion hole;
a damping part that includes a part that is built into the fixing part and has lower rigidity than the fixing part, and can press the tool inserted into the tool insertion hole with an arbitrary pressure from the outside in the radial direction of the tool; A tool holder comprising: The damping part includes a connecting part connected to the fixing part, and a tool contacting part connected to the connecting part and including the low-rigidity part, which contacts the tool and presses the tool. The tool holder according to claim 1, characterized in that: The tool contacting part includes an elastic part connected to the connecting part and a rigid part connected to the elastic part and contacting the tool, and the elastic part has lower rigidity than the fixed part. 3. The tool holder according to claim 2, wherein the rigid body part has higher rigidity than the elastic part. The tool contact portion protrudes from the inner diameter surface of the tool insertion hole, and the protrusion surface has a part such that the amount of protrusion from the inner diameter surface is larger on the rear end side than on the front end side of the tool. 4. The tool holder according to claim 2, wherein the tool holder is provided with a slope. A machine tool provided with the tool holder according to any one of claims 1 to 4.

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