JPH0631508A - Turning tool - Google Patents

Abstract

PURPOSE:To machine a deep hole, and to extend the lifetime of a tip by preventing chattering vibration of a turning tool, especially, that of a boring bar from occurring at the time of cutting. CONSTITUTION:A turning tool is made up of a weight 12 housed within a hollow part formed in its holder body 10 and a resiliently deformable linear support means 30 for supporting the weight 12, and tension is changed by moving the position where the support means 30 is fixed to the holder body 10. An electrical means such as a piezoelectric element and a magnetostrictor for converting an electric signal to a mechanical displacement and a piston which is displaced due to fluid pressure are employed as the means for moving the fixed position. Hence, the change of the supported position causes a change of the natural frequency of the weight 12 supported by the linear support means 30 and chatter is suppressed by setting this natural frequency to an appropriate value in response to chatter occurring at the time of cutting, so that a tip is protected. This enables a deep hole to be machined, and machining surface roughness to be improved and the effect of reduced working noise to be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turning tool, and more particularly to a tool for suppressing chatter vibration of a holder body.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional example of a turning tool called a boring bar used for cutting a cylinder bore or the like. The boring bar is composed of a holder body 2 attached to a chuck of a machine tool and a head 4 provided at the tip of the holder body 2, and a cutting blade 6 such as a throwaway tip is provided at the tip of the head 4.
Is provided. The holder main body 2 is formed of a highly rigid cemented carbide to prevent bending and chattering, while the head 4 is formed of a material such as steel in consideration of workability.

FIG. 5 shows another conventional example of a boring bar. The holder main body 10 of the boring bar is formed in a hollow shape, and the inside of the holder main body 10 is filled with grease and oil, and the weight 1 is supported by these.
2 are housed. In this bowling bar,
The vibration of the holder body 10 is canceled by the inertial force of the weight 12 to obtain a vibration damping effect. Further, the movement of the weight 12 is braked by a filler 14 such as grease. The head 10 is detachably attached to the holder main body 10, and a seal is interposed on the fitting surface of the head 10 to prevent the filling material 14 from being filled.
It is designed to prevent leaks.

[0004]

However, the above-mentioned conventional tool has a problem that the cemented carbide as the material of the holder body is expensive and has poor workability. Also,
However high the rigidity of cemented carbide is, it is inevitable that it has a specific natural frequency, and there is a problem that a sufficient chatter suppressing effect cannot be obtained depending on the cutting conditions.

Even in the case of other conventional tools, the damping effect of the weight 12 is effective only within a specific frequency range. In this case as well, the damping effect is ensured by flexibly responding to cutting conditions. The problem is that it is difficult to maintain. Therefore, there is a problem that it is difficult to efficiently perform deep hole machining (inner surface machining of a hole having a certain depth or more with respect to the outer diameter of the holder body) regardless of which of the conventional tools is used. . The present invention has been made in view of the above circumstances, and an object thereof is to provide a turning tool capable of exhibiting an optimum vibration damping effect in accordance with various cutting conditions.

[0006]

To achieve the above object, the invention of claim 1 is a turning tool comprising a head to which a blade is attached and a holder body supported by a machine tool. A hollow portion provided inside, a weight accommodated in the hollow portion, and a support means provided between the weight and the holder body to support the weight at a distance from the inner surface of the holder body. The supporting means is composed of a linear elastic member connected to the weight and extending outward from both ends of the weight, and a plurality of fixing means for fixing both ends of the elastic member to the holder body, respectively. At least one of the fixing means is configured to be supported by the holder body so as to be movable in the length direction of the elastic member. According to a second aspect of the present invention, in the first aspect of the present invention, a fluid is enclosed in the holder body, and a drive means for moving the weight with respect to the holder body by pressurizing the fluid is provided. Is. According to a third aspect of the invention, in the second aspect, the driving means drives the fixing means by converting an electric signal into a mechanical displacement.

[0007]

According to the above construction, the tension of the linear support member for supporting the weight can be increased or decreased by moving the support means. By increasing the tension of the support member, the natural frequency of the pendulum motion of the weight increases, and by decreasing the tension, the natural frequency decreases. Therefore, the weight can be set to the natural frequency according to the chatter. Further, the movement of the supporting means can be performed by the driving means by electric means or by the action of fluid pressure.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In the figure, the same parts as those in the conventional example are designated by the same reference numerals to simplify the description. FIG. 1 shows a first embodiment of the present invention. A hole 20 is formed in the head 4 with the same axis as the holder body 10, and a plug 22 having a female thread at the center is screwed into the hole. On the other hand, a hole 24 is formed on the base end side of the hollow portion in the holder body 10 with the same axis, and a sliding member 26 is inserted into the hole 24 so as to be movable in the axial direction. A connecting member 28 is screwed into the female thread of the plug 22. On the other hand, one end of a linear member 30 made of an elastic body such as carbon steel, stainless steel, or piano wire is integrally attached to the end of the sliding member 26.

The linear member 30 is passed through the through hole 32 at the center of the weight 12, and the other end thereof is connected to the connecting member 28 via a connecting portion 34. This connecting portion 34
Is preferably a rotatable joint such that the linear member 30 is not twisted even when the plug 22 is rotated.
The linear member 30 is fixed to the weight 12 by, for example, making the dimension intersection with the through hole 32 negative.

A female screw hole 40 is formed in the holder body 10 so as to penetrate therethrough in the radial direction. A range near the center of the holder body 10 in the female screw hole 40 is a smooth inner surface without a female screw, and a drive shaft 42 is axially movably inserted in this portion. The upper end of the drive shaft 42 is formed in a flat shape and the lower end thereof is formed in a wedge shape, and the wedge portion 44 is in contact with the notch 46 formed in the sliding member 26. That is, by sliding the wedge portion 44 and the notch 46, the movement of the drive shaft 42 in the holder body radial direction is converted into the movement of the sliding member 26 in the holder body axial direction.

Bolts 4 are provided in the female screw holes 40, respectively.
8 is screwed in, and one of the bolts 48 (the upper side in FIG. 1) is rotated to operate the drive shaft 42 to move the sliding member 26 and change the tension of the linear member 30. Is able to.

Reference numeral 50 designates the head 4 and the holder body 1.
Reference numeral 52 denotes a viscous fluid sealed in a hollow portion inside the holder body 10 to seal a gap between 0 and 0.

Next, the operation of the boring bar of the present invention will be described. The boring bar is used for cutting the inner circumference of the cylinder bore. In such cutting, the frequency of chattering is obtained in advance by using past data or by performing test cutting.

The bolt 48 is operated so as to set the natural frequency of the weight 12 to a value as close as possible to the frequency of the chatter, based on the chatter frequency previously obtained. That is, by screwing the bolt 48 and pushing the drive shaft 42 downward, the sliding member 26 moves to the right in FIG. 1, and the tension of the linear member 30 increases. On the other hand, by operating the bolt 48 in the opposite direction, the linear member 30 is elastically restored and the tension thereof is lowered. Thus, when the tension of the linear member 30 is increased, the natural frequency of the pendulum motion of the weight 12 supported by the linear member 30 is increased, and when the tension is decreased, the natural frequency is decreased. Therefore, the operation of the bolt 48 causes the weight 12 to vibrate in an opposite phase with a frequency close to that of chatter, thereby suppressing chatter.

If there is no known data,
The operator operates the bolt 48 while performing the test cutting,
The position corresponding to the tension with the least vibration may be found.

The operation of the bolt 48 can be easily performed from the outside of the holder body 10 even during cutting by inserting a tool such as a hexagon wrench into the operation hole at the tip of the bolt 48. . Further, when it is necessary to adjust the tension beyond the adjustable range by the drive shaft 42, the plug 22 in the head 4 is rotated to change the position of the other end of the linear member 30 to further increase the strain. It may be given or the total length of the linear member 30 may be adjusted. That is,
The natural frequency can be raised by shortening the total length, and the natural frequency can be lowered by lengthening the total length.

FIG. 2 shows a second embodiment of the present invention. The sliding member 26 connected to one end of the linear member 30 in this embodiment is screwed into the screw portion 60 because it is formed on the holder body 10. The plug 22 connected to the other end of the linear member 30 has a female screw portion 6 at the center of a piston 62 that is provided so as to be movable in the axial direction of the holder body 10.
Screwed in 4. That is, the piston 62 uses the holder body 10 as a cylinder and the viscous fluid 52 in the piston 62
It is possible to move by the pressure of.

An internal thread portion 6 is provided on the inner circumference of the holder body 10.
6 is formed on which an annular support member 68 is screwed. One end of the driving means 70 is connected to the support member 68. The other end of the driving means 70 is connected to the piston 62. The driving means 70 is a means such as a piezoelectric element or a magnetostrictive element for converting an electric signal into a mechanical displacement. The driving force of the driving means 70 allows the piston 62 to move in the axial direction of the holder body 10 with respect to the support member 68.

The head 4 is provided with a sensor 72 such as an acceleration sensor for converting the chatter generated at the cutting edge 6 into an electric signal, and the output of the sensor 72 is supplied to a controller 74. . Further, the controller 74 is adapted to supply a drive signal to the drive means 70.

Next, the operation of the boring bar of the second embodiment will be described together with the control contents of the controller 74. The boring bar is used for cutting the inner circumference of the cylinder bore. When the cutting edge 6 is applied to the surface to be cut and lathe turning is performed, vibration is generated in the cutting edge 6 during machining. This vibration is detected by the sensor 72, converted into an electric signal, and supplied to the controller 74. The controller 74 controls the drive signal to the drive means 70 according to the input electric signal.

In this controller 74, for example, the piston 62 is moved by supplying a drive current to the drive means 70 based on the vibration frequency of chatter detected by the sensor 72. That is, if the natural frequency of the weight 12 is lower than the detected vibration, the drive means 70 is used to move the piston 62 to the left in FIG.
A driving current is supplied to increase the tension of the linear member 30. On the contrary, if the natural frequency of the weight 12 is higher than the chatter frequency, a drive current is supplied to the drive means 70 to move the piston 62 to the right in FIG. 2, and the tension of the linear member 30 is lowered.

When the period of the pendulum motion of the weight 12 is automatically adjusted to an appropriate value in accordance with the chatter, the reaction of the motion of the weight 12 can cancel the vibration of the cutting edge 6.

Alternatively, the controller 74 may be manually adjusted while actually cutting, and the drive current of the drive means 70 may be adjusted to obtain the condition with the least chattering.

FIG. 3 shows a third embodiment of the present invention. One end of the linear member 30 is connected to the sliding member 26 as in the second embodiment. The plug 22 connected to the other end of the linear member 30 is screwed into the threaded portion 64 at the center of the piston 62 which is slidable in the axial direction with the holder body 10 as a cylinder. An oil seal 76 is fitted on the outer circumference of the piston 62 to seal the sliding surface.

The controller 74 of the third embodiment controls hydraulic pressure, and is connected to a connecting portion 78 formed on the holder body 10 via a hydraulic pipe 80.

Next, the operation of the boring bar of the third embodiment will be described together with the control contents of the controller 74. The boring bar is used for cutting the inner circumference of the cylinder bore. When the cutting edge 6 is applied to the surface to be cut and lathe turning is performed, vibration is generated in the cutting edge 6 during machining. This vibration is detected by the sensor 72, converted into an electric signal, and supplied to the controller 74. The controller 74 controls the hydraulic pressure in the holder body 10 according to the input electric signal.

If the natural frequency of the weight 12 is lower than the detected vibration, the controller 74 increases the hydraulic pressure in the holder body 10 to move the piston 62 to the left in FIG. Increase the tension of 30. On the contrary, if the natural frequency of the weight 12 is higher than chatter,
In order to move the piston 62 to the right in FIG. 3, the hydraulic pressure in the holder body 10 is reduced to reduce the tension of the linear member 30. In reality, the pulling force of the piston 62 is reduced due to the decrease in the hydraulic pressure, and the linear member 30 elastically contracts to a position balanced with this.

When the period of the pendulum motion of the weight 12 is automatically adjusted to an appropriate value corresponding to the chatter, the vibration of the cutting edge 6 can be canceled by the reaction of the motion of the weight 12.

Further, as in the other embodiments described above, the controller 74 may be manually adjusted while actually cutting to adjust the drive current of the drive means 70 to obtain the condition with the least chatter. Of course.

Needless to say, the specific structure of the component for supporting or driving the weight is not limited to the embodiment.

[0031]

As is apparent from the above description, the present invention is
In a turning tool composed of a head to which a blade is attached and a holder main body supported by a machine tool, a hollow portion provided in the holder main body, a weight accommodated in the hollow portion, the weight and the And a supporting means provided between the holder body and supporting the weight at a distance from the inner surface of the holder body, the supporting means being connected to the weight and extending from both ends of the weight to the outside. -Shaped elastic member and a plurality of fixing means for fixing both ends of the elastic member to the holder main body, and at least one of the fixing means moves in the length direction of the elastic member with respect to the holder main body. Since it is configured to be supported, the tension of the linear support member that supports the weight can be increased by moving the support means electrically or by fluid pressure. It is possible to increase or decrease the.

Therefore, the natural vibration period of the weight can be changed so as to be close to or the same as the frequency of chatter. Therefore, the weight resonates with the chatter generated in the holder main body, and the weight within the holder main body. It moves like a pendulum, which offsets the chatter. In this way, chatter during cutting can be effectively suppressed, deep hole drilling can be performed, the life of the cutting edge can be extended as much as possible, and further, the roughness of the cutting surface and noise during machining can be improved. The effect of reduction can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a tool according to a first embodiment.

FIG. 2 is a vertical sectional view of a tool according to a second embodiment.

FIG. 3 is a vertical sectional view of a tool according to a third embodiment.

FIG. 4 is a vertical sectional view of a conventional example of a boring bar.

FIG. 5 is a vertical cross-sectional view of another conventional example of a boring bar.

[Explanation of symbols]

 4 heads 6 cutting blades 10 holder body 12 weights 22 holes 22 plugs 26 sliding members 28 connecting members 30 linear members 42 drive shafts 44 wedges 46 notches 52 viscous fluid 62 pistons 64 female threads 66 female threads 68 supporting members 70 drive means 72 sensor 74 controller 80 hydraulic line

Claims (3)

[Claims] 1. A turning tool including a head to which a blade is attached and a holder main body supported by a machine tool, wherein a hollow portion provided in the holder main body and a weight accommodated in the hollow portion. A supporting means provided between the weight and the holder main body for supporting the weight at a distance from the inner surface of the holder main body, the supporting means being connected to the weight and extending from both ends of the weight. It comprises a linear elastic member extending to the outside and a plurality of fixing means for fixing both ends of the elastic member to the holder main body, at least one of the fixing means of the elastic member with respect to the holder main body. A turning tool characterized by being supported so as to be movable in the length direction. 2. The turning tool according to claim 1, further comprising a drive means for enclosing a fluid in the holder body and moving the weight with respect to the holder body by pressurizing the fluid. . 3. The turning tool according to claim 2, wherein the driving means drives the fixing means by converting an electric signal into a mechanical displacement.