JP7378765B2 - Machine tool vibration damping device - Google Patents

Description

The present invention relates to a vibration damping device for a machine tool that can improve machined surface quality by suppressing the natural vibration of a column that supports a spindle unit.

In recent years, various machine tools with improved machined surface quality have been proposed in order to reduce the manual finishing work of machined products.

For example, in Patent Document 1, in a machine tool equipped with an attachment/detachment mechanism that automatically attaches and detaches a tool holder with a tool attached to the spindle, the run-out of the tool with respect to the rotational axis of the spindle is automatically corrected and the tool is attached with high precision. A machine tool and a tool runout correction method are disclosed. The machine tool described in Patent Document 1 includes a runout sensor that measures the runout of a rotating system composed of a spindle, a tool holder, and a tool, and a runout sensor that measures the runout of a rotating system made up of a spindle, a tool holder, and a tool when the spindle rotates, and a runout sensor that measures the runout of a rotating system made up of a spindle, a tool holder, and a tool when the spindle rotates. a phase control mechanism mounted on the spindle, and the phase control mechanism compares runout of the rotating system measured at two or more different phases, and installs the tool holder on the spindle at the phase where the runout is minimum. Equipped with a mechanism.

Further, Patent Document 2 discloses that, in a machine tool, a flexible member is fixed to a structure such as a column and has a first position serving as a fixed end of a cantilever beam, and a second position on the free end side; A vibration damping device is disclosed having an adjustment mechanism for changing the distance between the first position and the second position, and a weight attached to the flexure member in two positions. This vibration suppression device suppresses the vibration of a structure using a weight attached to a flexible member, and also deals with vibrations with different characteristics by adjusting the distance between a first position and a second position. .

JP 2017-7030 Publication JP 2018-103298 Publication

However, as the machining accuracy of machine tools improved, the problem remained that even slight vibrations generated in the machine body affected the quality of the machined surface. The inventor focused on the natural vibration of the column that supports the spindle unit as a vibration problem that degrades the machined surface quality.

The natural vibration of the column is a mode that vibrates in a specific direction (for example, the X-axis direction) at a specific frequency, and because it has a low frequency, it is easily affected by disturbances from the floor and self-excited vibration. This natural vibration of the column is one of the factors that degrade machined surface quality.

The vibration suppression device described in Patent Document 2 suppresses the vibration of a structure such as a column using a weight attached to a flexible member, but since the weight is attached to the free end side of the cantilever, the weight vibrates along the circumference, and the direction of vibration constantly changes. For this reason, in the vibration suppression device described in Patent Document 2, vibrations occur in directions other than those in which vibrations are desired to be suppressed, and the vibrations of the weight affect other axes, especially when suppressing small vibrations with small amplitudes. There was fear.

In addition, the vibration suppression device described in Patent Document 2 uses an adjustment mechanism to adjust the vibration between the fixed end and the free end of the cantilever beam in order to cope with vibrations that have different characteristics depending on the characteristics of individual machine tools and the tools installed. There were problems in that it was necessary to change the distance, making the adjustment complicated, and that only natural vibrations in a narrow frequency band could be suppressed.

SUMMARY OF THE INVENTION Therefore, the present invention provides a vibration damping device for a machine tool that can easily and reliably suppress the natural vibration of a column that supports a spindle unit, thereby further improving machined surface quality.

In order to solve the above-mentioned problems, the present invention provides a machine tool equipped with a column that supports a spindle unit. It has a vibration absorption mechanism consisting of a leaf spring attached to the side surface of the leaf spring, a mass member provided in the center of the leaf spring, and a damping mechanism that elastically and/or magnetically damps vibrations of the mass member. The present invention provides a vibration damping device for machine tools.

Further, in the vibration damping device for a machine tool of the present invention, the vibration absorbing mechanism has a vertically symmetrical shape in which the plate spring is spanned between the supporting members arranged in pairs at predetermined intervals in the horizontal direction. It is something that accomplishes the following.

Further, in the vibration damping device for a machine tool of the present invention, the damping mechanism includes a viscoelastic body that elastically damps vibrations of the mass member.

Further, in the vibration damping device for a machine tool of the present invention, the damping mechanism includes the viscoelastic body accommodated in a cavity formed in the mass member, and the viscoelastic body disposed against the mass member with respect to the column. and a stopper member for restricting displacement in the vibration direction, and a cover body that covers the cavity.

Further, in the vibration damping device for a machine tool of the present invention, the viscoelastic body is a low resilience material having a resilience of 15% or less.

Further, in the vibration damping device for a machine tool of the present invention, the viscoelastic body is provided between the plate spring and the column.

Further, in the vibration damping device for a machine tool of the present invention, the damping mechanism includes a magnet provided on either the leaf spring or the column, and a conductor provided on the other, and It is equipped with a magnetic damping means for magnetically damping vibrations.

Further, the vibration damping device for a machine tool of the present invention includes a spacer member disposed between the leaf spring and the mass member and abutting a central portion of the leaf spring.

Further, in the vibration damping device for a machine tool of the present invention, the mass member has a protrusion that abuts a central portion of the leaf spring.

A vibration damping device for a machine tool according to the present invention is a machine tool equipped with a column that supports a spindle unit. It has a vibration absorption mechanism consisting of a leaf spring attached to a side surface, a mass member provided in the center of the leaf spring, and a damping mechanism that elastically and/or magnetically damps vibrations of the mass member. This allows the mass member to vibrate only in the direction you want to damp by using a double-supported beam structure in which leaf springs are attached via support members arranged in pairs, and it is possible to vibrate in the X-axis direction without affecting other axial directions. This has the effect of reliably suppressing the natural vibration of the column that occurs in the column.

In addition, in the machine tool vibration damping device of the present invention, the damping mechanism attenuates the vibration of the mass member, so that the frequency band of the natural vibration to be damped can be expanded. This has the effect of suppressing vibrations that have different characteristics depending on the tool.

Further, in the vibration damping device for a machine tool of the present invention, the vibration absorbing mechanism has a vertically symmetrical shape in which the plate spring is spanned between the supporting members arranged in pairs at predetermined intervals in the horizontal direction. By doing so, it is possible to reliably suppress the natural vibration of the column that occurs in the X-axis direction, which is the damping target, and it is possible to reduce the influence of vibration of the mass member in other axial directions.

Further, in the machine tool vibration damping device of the present invention, the damping mechanism includes a viscoelastic body that elastically damps the vibrations of the mass member, so that the vibrations of the mass member are elastically damped and controlled. This has the effect of widening the frequency band of the natural vibrations.

Further, in the vibration damping device for a machine tool of the present invention, the damping mechanism includes the viscoelastic body accommodated in a cavity formed in the mass member, and the viscoelastic body disposed against the mass member with respect to the column. and a stopper member that restricts displacement in the vibration direction of the cavity, and a cover body that covers the cavity, so that even in a working environment where cooling oil mist is diffused, the cover body can This has the effect of preventing oil from entering the covered cavity and preventing oil from adhering to the viscoelastic body and causing deterioration.

Further, in the vibration damping device for a machine tool of the present invention, since the viscoelastic body is a low resilience material with a resilience of 15% or less, a stable damping force can be obtained even against slight vibrations, This has the effect of reliably damping vibrations.

Further, in the machine tool vibration damping device of the present invention, by providing the viscoelastic body between the plate spring and the column, it is possible to elastically damp vibrations of the mass member via the plate spring. This has the effect of widening the frequency band of the natural vibration to be suppressed.

Further, in the vibration damping device for a machine tool of the present invention, the damping mechanism includes a magnet provided on either the leaf spring or the column, and a conductor provided on the other, and By providing a magnetic damping means that magnetically damps vibrations, it is possible to magnetically damp the vibrations of a mass member by utilizing the Lorentz force generated when a conductor moves in a magnetic field due to vibrations. This has the effect of widening the frequency band of the natural vibrations.

Further, the vibration damping device for a machine tool of the present invention includes a spacer member that is disposed between the leaf spring and the mass member and abuts a central portion of the leaf spring, so that the mass member can be moved through the spacer member. Since it contacts only the central part of the leaf spring, it is possible to maintain a wide range of motion of the leaf spring regardless of the shape and size of the mass member, and even if the installation space is small, the natural vibration of the column to be damped can be suppressed. This has the effect of ensuring the weight of the mass member while maintaining a suitable damping band.

Further, in the vibration damping device for a machine tool of the present invention, since the mass member has a protrusion that comes into contact with the center portion of the leaf spring, it is possible to maintain a wide range of motion of the leaf spring, and when the installation space is narrow. However, there is an effect that the weight of the mass member can be secured while maintaining a damping band that matches the natural vibration of the column that is the damping target.

1 is a sectional view showing an embodiment of a vibration damping device for a machine tool according to the present invention. FIG. 3 is a sectional view showing another form of the embodiment. FIG. 1 is a configuration diagram showing the configuration of a machine tool equipped with a vibration damping device according to the present invention. FIG. 3 is a sectional view showing another embodiment of the vibration damping device for a machine tool according to the present invention. FIG. 3 is a sectional view showing another embodiment of the vibration damping device for a machine tool according to the present invention. 6 is a diagram showing the functions of the vibration damping device according to the embodiment of FIG. 5. FIG. FIG. 3 is a comparison diagram showing a comparison before and after the measures taken by the vibration absorption mechanism of the present invention. FIG. 3 is a diagram showing a damping band of the vibration absorption mechanism of the present invention.

Embodiments of the present invention will be described based on illustrated examples.
The vibration damping device of the present invention includes a machine tool 1 equipped with a column 13 that supports a spindle unit 10. 13, a mass member 23 provided at the center of the leaf spring 21, and a damping mechanism 30 that elastically and/or magnetically damps vibrations of the mass member 23. It has a vibration absorption mechanism 2.

In the vibration absorption mechanism 2, the mass member 23 vibrates due to the vibration of the column 13 transmitted from the support member 22, and the leaf spring 21 holds the mass member 23. The vibration absorption mechanism 2 acts to cancel the vibration of the column 13 by the vibration of the mass member 23, and reduces the vibration of the body of the machine tool 1. Further, the vibration absorption mechanism 2 includes a damping mechanism 30 that elastically and/or magnetically damps the vibration of the mass member 23, and widens the frequency band in which the vibration is damped.

The vibration absorption mechanism 2 has a vertically symmetrical shape in which a plate spring 21 is spanned between support members 22 arranged in pairs at predetermined intervals in the horizontal direction. The vibration absorption mechanism 2 of the present invention has a double-supported beam structure in which the plate spring 21 is spanned between the support members 22 arranged in pairs, so that the mass member 23 is moved in the direction in which vibration is desired to be damped (X-axis direction). It has a structure that allows it to swing only in the direction of the axis, minimizing the influence on other axes such as the Y-axis and Z-axis. Furthermore, since the vibration absorption mechanism 2 has a vertically and horizontally symmetrical shape, even if the leaf spring 21 is thin, the influence of vibration of the mass member 23 on other axial directions can be suppressed. .

FIG. 1 is a sectional view showing an embodiment of a vibration damping device for a machine tool according to the present invention. FIG. 3 is a configuration diagram showing the configuration of a machine tool equipped with a vibration damping device according to the present invention.

In the illustrated embodiment, the machine tool 1 is a three-axis or five-axis vertical machining center having a column 13 supporting a spindle unit 10 . The main shaft unit 10 is driven by a drive device in the X-axis direction, and also drives the main shaft 11 in the Z-axis direction.

In the embodiment shown in FIG. 1, the vibration damping device of the machine tool 1 includes a pair of support members 22 arranged at a predetermined interval on the side surface of a column 13, and a plate spring spanned between the pair of support members 22. 21, a mass member 23 provided via a spacer member 24 that contacts the central portion of the leaf spring 21, and a damping mechanism 30 that elastically damps vibrations of the mass member 23. has.

As shown in FIG. 3, the vibration absorption mechanism 2 is installed at the top of both sides of the column 13 in the X-axis direction. The vibration absorption mechanism 2 can suppress the vibration of the machine tool 1 by attaching it to a location where vibration of the machine body is desired to be suppressed. In this embodiment, the vibration absorption mechanism 2 reduces the natural vibration in the X-axis direction that occurs in the aircraft body by causing the mass member 23 to vibrate instead of the aircraft body due to resonance. In this embodiment, the vibration absorption mechanism 2 is installed on the side surface of a column 13 that vibrates in the X-axis direction at a specific frequency. The vibration absorption mechanism 2 is configured to have the same predetermined natural frequency as the natural vibration frequency of the column 13 in order to resonate with the natural vibration of the column 13 and suppress the vibration.

In the vibration absorption mechanism 2, a pair of support members 22 are arranged on the side surfaces of a column 13 at a predetermined distance apart in the Y-axis direction, a leaf spring 21 is spanned between the support members 22, and a mass member 23 supports a spacer member 24. It is provided on the plate spring 21 via the plate spring 21, and has a vertically and horizontally symmetrical shape. The plate spring 21 is made of, for example, an SS400 iron plate, and serves as a spring for the vibration absorption mechanism 2. The mass member 23 is preferably made of a plurality of stacked metal plates so that the weight can be adjusted.

The spacer member 24 is arranged between the leaf spring 21 and the mass member 23, and is fixed to the leaf spring 21 together with the mass member 23 using a fixing device such as a screw. Further, the spacer member 24 is formed so that its width in the Y-axis direction (horizontal direction in FIG. 1) is narrower than the width of the mass member 23, and contacts only the central portion of the leaf spring 21 to limit the range of motion a of the leaf spring 21. It is designed to keep it wide.

If there is no spacer member 24, the movable range a of the leaf spring 21 is between the inner end of the support member 22 and the outer end of the mass member 23, so it is possible to increase the weight of the mass member 23 while ensuring the movable range a. Then, the vibration absorbing mechanism 2 has a shape that greatly protrudes from the column 13. On the other hand, since the machine tool 1 has space constraints in its installation location, the mass member 23 may be expanded in the Y-axis direction to ensure weight so that the vibration absorption mechanism 2 does not protrude too far from the column 13. preferable. In this embodiment, the vibration absorption mechanism 2 has a spacer member 24 disposed between the leaf spring 21 and the mass member 23, so that a relatively low vibration damping band matching the natural vibration of the column 13 can be maintained. It has become possible to secure the weight by expanding the mass member 23 in the Y-axis direction while securing the movable range a of the leaf spring 21.

In the embodiment shown in FIG. 1, the damping mechanism 30 includes a viscoelastic body 31 housed in a cavity 26 formed in the mass member 23, and a vibration direction of the mass member 23 with respect to the column 13. and a stopper member 32 that restricts displacement. The cavity 26 is formed into a cylindrical shape in which the center portions of the mass member 23 and the spacer member 24 are hollowed out, and includes a cover body 27 that covers the cavity 26 .

The vibration absorbing mechanism 2 of this embodiment uses, as the viscoelastic body 31, a low resilience material such as polynorbrunene rubber, which has a resilience measured in accordance with JIS K 6400-3 of 15% or less. An example of the low-resilience material is "Hanenight" (registered trademark) manufactured by Naigai Rubber Co., Ltd. The viscoelastic body 31 has a low repulsion elasticity with a repulsion elasticity of 1 to 5% so as to widen the frequency band of the natural vibration to be damped and to obtain a stable damping force even against slight vibrations. It is preferable that it is a material.

The stopper member 32 includes a support rod 33 that is erected on the column 13 and extends to the cavity 26 through an insertion hole 28 formed in the center of the leaf spring 21, and a support rod 33 that holds the viscoelastic body 31 together with the leaf spring 21. , a stopper plate 34 that restricts displacement of the viscoelastic body 31 in the vibration direction of the mass member 23 with respect to the column 13, and an adjustment nut 35 that adjusts the position of the stopper plate 34. The viscoelastic body 31 has a hole in the center thereof through which the support rod 33 is inserted, and is held between the leaf spring 21 and the stopper plate 34 at a predetermined position. The damping mechanism 30 generates damping by the plate spring 21 vibrating and crushing the viscoelastic body 31.

In the damping mechanism 30 of this embodiment, the viscoelastic body 31 is housed in the cavity 26 whose opening is covered with the leaf spring 21 and the cover body 27, so that it is suitable for work in which cooling oil mist is diffused. Even under environmental conditions, it is possible to prevent oil from adhering to the viscoelastic body 31. Since the damping mechanism 30 only needs to be able to damp the vibrations of the mass member 23, the viscoelastic body 31 only needs to be in contact with the spacer member 24 or the mass member 23 and the stopper plate 34 in addition to the plate spring 21.

As shown in FIG. 2, the vibration absorbing mechanism 2 of the present invention is configured such that the mass member 23 has a protrusion 25 that contacts only the central portion of the leaf spring, and maintains a wide range of motion a of the leaf spring 21. It's okay. Further, the mass member 23 has a hollow portion 26 formed by hollowing out a cylindrical hole on the opposite side of the protruding portion 25 , and the viscoelastic body 31 is housed in the hollow portion 26 . In the vibration absorbing mechanism 2 shown in FIG. 2, the width of the protrusion 25 in the Y-axis direction (horizontal direction in FIG. 2) can be formed narrower than the width of the viscoelastic body 31. Can be made wider. In the vibration absorption mechanism 2 shown in FIG. 2, a spacer member may be arranged between the leaf spring 21 and the mass member 23 instead of the protrusion 25.

The damping mechanism 30 shown in FIG. It is composed of a stopper member 32 that regulates. The stopper member 32 includes a support rod 33 that is erected on the column 13 and extends to the cavity 26 through insertion holes 28 and 29 formed at the center of the leaf spring 21 and the mass member 23, and a support rod 33 that extends from the bottom of the cavity 26. A stopper plate 34 that holds the viscoelastic body 31 therebetween and restricts displacement of the viscoelastic body 31 in the vibration direction of the mass member 23 with respect to the column 13, and an adjustment nut 35 that adjusts the position of the stopper plate 34. It consists of The viscoelastic body 31 has a hole in the center thereof through which the support rod 33 is inserted, and is held between the bottom surface of the cavity 26 and the stopper plate 34 at a predetermined position. The damping mechanism 30 generates damping by the mass member 23 vibrating and crushing the viscoelastic body 31.

The machine tool 1 also has a function of comparing the NC position command to the servo motor with the actually moved position measured by a linear scale to obtain the position deviation of the servo. The machine tool 1 can further improve machined surface quality by applying a servo system vibration damping filter together with the vibration damping device of the present invention.

FIG. 7 shows the measured vibration displacement of the end of the main shaft 11 in the X-axis direction when the shaft is stopped, with the horizontal axis representing the frequency and the vertical axis representing the amount of displacement. The upper part of FIG. 7 shows the vibration displacement before damping measures, and the vibration displacement peak exists at a specific frequency (1F). The middle part of FIG. 7 shows the vibration displacement after the measures taken by the vibration absorption mechanism 2 of this embodiment, and the vibration displacement near the frequency 1F is small. The lower part of FIG. 7 shows the vibration displacement when the vibration absorption mechanism 2 and the vibration damping filter function are used together, and the vibration displacement becomes even smaller.

FIG. 8 shows the frequency band of the vibration absorption mechanism 2 of this embodiment and the natural frequency of the column 13 measured with a two-plane displacement meter in different bodies of the machine tool 1. In the vibration absorption mechanism 2, when the damping mechanism 30 is not provided, the width of the damping band where the vibration reduction rate is 50% or more is about 1F ± 1% of the frequency, but when the damping mechanism 30 is provided, The damping band has been significantly expanded to frequency 1F±7-8%. Since the natural frequencies of the different machines (1) to (5) are all within the damping band of the vibration absorbing mechanism 2, the vibration damping device of the present invention can be adjusted depending on the characteristics of each machine tool 1 and the There is no need to make adjustments according to the tool.

FIG. 4 is a sectional view showing another embodiment of the vibration damping device for a machine tool according to the present invention.
The vibration absorption mechanism 2 includes a pair of support members 22 provided on the side surfaces of the column 13 at a predetermined interval in the Y-axis direction (horizontal direction in FIG. 4), and is attached to the side surfaces of the column 13 via the support members 22. It consists of a flat spring 21 and a mass member 23 provided at the center of the flat spring 21. The plate spring 21 is made of, for example, an SS400 iron plate, and serves as a spring for the vibration absorption mechanism 2.

In the vibration absorption mechanism 2, the mass member 23 vibrates due to the vibration of the column 13 transmitted from the support member 22, and the leaf spring 21 holds the mass member 23. The vibration absorption mechanism 2 acts to cancel the vibration of the column 13 by the vibration of the mass member 23, and reduces the vibration of the body of the machine tool 1.

In the embodiment shown in FIG. 4, the vibration absorption mechanism 2 suppresses the vibration of the column 13 by causing the mass member 23 to vibrate in the X-axis direction instead of the column 13 at a predetermined natural frequency. Further, in the vibration absorbing mechanism 2, a damping sheet such as damping rubber is attached to the surface of the leaf spring 21, and the frequencies that can be damped are expanded to the vicinity of the above-mentioned natural frequency.

The vibration absorption mechanism 2 includes a viscoelastic body 31 provided between the plate spring 21 and the column 13 as a mechanism for damping the vibration of the plate spring 21, and in combination with the above-mentioned vibration damping sheet, widens the frequency band to damp the vibration. There is. For the viscoelastic body 24, a low-resilience material or a silicone rubber sponge can be used. The vibration absorption mechanism 2 generates damping by the plate spring 21 crushing the viscoelastic body 31.

FIG. 5 is a sectional view showing another embodiment of the vibration damping device for a machine tool according to the present invention. FIG. 6 is a diagram showing the functions of the vibration damping device according to the embodiment of FIG. 5.

The vibration absorption mechanism 2 of this embodiment utilizes the Lorentz force generated by the movement of a magnetic field as a mechanism for damping the vibration of the leaf spring 21 instead of the viscoelastic body 31 shown in the first and second embodiments. method may be adopted.

As shown in FIG. 5, in the vibration absorption mechanism 2, a flat conductor 37 is fastened to the plate spring 21 toward the column 13, so that the conductor 37 vibrates together with the plate spring 21. The vibration absorbing mechanism 2 has a pair of magnets 36 arranged above and below so as to sandwich a conductor 37 between them, and when the conductor 37 vibrates together with the leaf spring 21, the vibration absorbing mechanism 2 creates a gap between the conductor 37 and the magnet 36 fixed to the column 13 with a support member 38. The structure is such that a Lorentz force is generated, and a damping force is generated.

As shown in FIG. 6, the damping mechanism 30 is configured such that the magnetic flux generated between the pair of magnets 36 is perpendicular to the vibration direction of the conductor, and the conductor 37 is When it moves, a Lorentz force is generated in the direction in which it tries to stay in place (the direction opposite to the relative movement), and this Lorentz force becomes a damping force that dampens the vibration of the leaf spring 21.

Since the damping mechanism 30 only needs to be able to magnetically damp the vibrations of the mass member 23 and the leaf spring 21, a magnet 36 is provided on either the leaf spring 21 or the column 13, and a conductor 37 is provided on the other. All you have to do is stay there. In addition to the magnetic damping means that magnetically damps the vibrations of the mass member 23 and the leaf spring 21, the damping mechanism 30 also elastically damps the vibrations of the mass member 23 and the leaf spring 21 described in the first embodiment. You may also use a combination of methods.

1 Machine tool 2 Vibration absorption mechanism 10 Spindle unit 13 Column 21 Leaf spring 22 Support member 23 Mass member 24 Spacer member 25 Projection 26 Cavity 27 Cover body 30 Damping mechanism 31 Viscoelastic body 32 Stopper member 33 Support rod 34 Stopper plate 35 Adjustment nut 36 Magnet 37 Conductor 38 Support member

Claims (8)

In a machine tool equipped with a column that supports the spindle unit,
a support member arranged in pairs at a predetermined interval on the side surface of the column; a leaf spring attached to the side surface of the column via the support member; a mass member provided at the center of the leaf spring; It has a vibration absorption mechanism consisting of a damping mechanism that elastically damps the vibration of the mass member ,
The damping mechanism includes a viscoelastic body housed in a cavity formed in the mass member, and a stopper member that restricts displacement of the viscoelastic body with respect to the column in a vibration direction of the mass member. A vibration damping device for a machine tool , comprising: a cover body that covers the cavity . In a machine tool equipped with a column that supports the spindle unit,
a support member arranged in pairs at a predetermined interval on the side surface of the column; a leaf spring attached to the side surface of the column via the support member; A vibration absorption mechanism including a mass member provided on the surface and a damping mechanism that elastically damps vibrations of the mass member,
A vibration damping device for a machine tool, wherein the damping mechanism includes a viscoelastic body between the leaf spring and the column. In a machine tool equipped with a column that supports the spindle unit,
a support member arranged in pairs at a predetermined interval on the side surface of the column; a leaf spring attached to the side surface of the column via the support member; a mass member provided at the center of the leaf spring; A vibration absorption mechanism comprising a damping mechanism that elastically and/or magnetically damps vibrations of the mass member,
A vibration damping device for a machine tool , comprising a spacer member disposed between the leaf spring and the mass member and abutting a central portion of the leaf spring. The vibration damping device for a machine tool according to claim 3, wherein the damping mechanism includes a viscoelastic body that elastically damps vibrations of the mass member. 5. The vibration absorbing mechanism according to claim 1, wherein the leaf spring is spanned between the support members arranged in pairs at predetermined intervals in the horizontal direction, forming a vertically and laterally symmetrical shape. Vibration damping device for the machine tool described. 5. The vibration damping device for a machine tool according to claim 1 , wherein the viscoelastic body is a low resilience material having a resilience of 15% or less. The damping mechanism includes a magnet provided on either the leaf spring or the column, and a conductor provided on the other, and includes magnetic damping means for magnetically damping vibrations of the mass member. The vibration damping device for a machine tool according to claim 3 . The vibration damping device for a machine tool according to claim 1 or 2, wherein the mass member has a protrusion that abuts a central portion of the leaf spring.

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