JPH10138013A - Radial cross feed device for machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radial cross feed device for a metal cutting machine tool of a simplified structure, less deterioration in precision, and capable of avoiding such problems as frictional heating and deterioration of cutting precision due to abrasion and durability. SOLUTION: With a first rod 15 inserted into the draw bar 7 of a main spindle 2, which is rotationally driven by a main spindle drive mechanism 4 supported on a main spindle head 2 in a rotatable manner, in a rotatable manner and movable in the axial direction, and also with a second rod 16 having a screw formed on its outer circumference inserted into the main spindle head 1 in a rotatable manner and movable in the axial direction, the second rod 16 is connected to the first rod 15 in a relatively rotatable manner and axially movable and transmittable manner, while a nut member 18 screwed in the second rod 16 is supported on the main spindle head 1 in a rotatable manner but unmovable in the axial direction. By rotating the nut member 18 by a motor 21, the second rod 16 and the first rod 15 are moved in the axial direction and, by a moving direction switching mechanism provided inside a tool holder 5, the movement of the first rod 15 in the axial direction is switched to the movement in the radial direction of the main spindle of a cutting tool.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial cutting device for a machine tool, for example, for boring a desired diameter by moving a cutting tool of a tool holder mounted on a spindle in a radial direction of the spindle. .

[0002]

2. Description of the Related Art Conventionally, for example, in Japanese Patent Publication No. 62-42726 (first conventional example), it is possible to control a cutting amount of a cutting tool in a main shaft radial direction in a machining center.
JP-B-62-42727 (second conventional example) and JP-A-5-27781 (third reference) are known.

In the first conventional example, a tool holder is mounted on the tip of a spindle, and an eccentric mechanism for changing the radial position of a cutting tool is provided in the tool holder. The eccentric mechanism is inserted into the spindle and unlocks the tool holder. The cutting control shaft is inserted and placed in the draw bar to be clamped, and the cutting edge position of the tool is numerically controlled from the reference angle position through the differential mechanism, the cutting control shaft, and the eccentric mechanism, the rotation of which is controlled by a servomotor. This is an example in which control is performed.

The second conventional example is an improvement of the first conventional example, in which a planetary gear mechanism is disposed in a tool holder as a differential mechanism, and a cutting control shaft is linked to a coupling shaft on the tool holder side. This is an example in which a cylinder device for detachment is provided.

In the third conventional example, a mechanism for converting the axial movement of a piston member into a radial movement of a cutting tool by an inclined cam is provided in a tool holder, and a ball screw is provided on the outer periphery to allow the piston member to move in the axial direction. In this example, a drive shaft to be driven is inserted into the main shaft so as to be rotatable and movable in the axial direction, a ball nut is mounted on the drive shaft, and the ball nut is driven to rotate by a motor.

The first prior art apparatus has a problem that the structure becomes complicated because it is necessary to provide an eccentric mechanism in the tool holder, and the apparatus also requires a differential mechanism. However, since the cutting amount is controlled by the rotation angle of the eccentric mechanism, there is a problem that the cutting feed command value is not proportional to the actual cutting amount.

[0006] The second conventional apparatus has a problem that the structure becomes complicated because it is necessary to provide a planetary gear mechanism for controlling the rotation of the cutting control shaft in the tool holder. There is also a problem that a special cylinder device for engaging and disengaging the connecting shaft is required.

Both the first and second prior art devices employ a system in which the rotation of a cutting control shaft is transmitted to an eccentric mechanism and a planetary gear mechanism via a gear to control the cutting amount. There is a concern about power loss and accuracy deterioration due to transmission.

On the other hand, in the third conventional example, since the axial movement of the piston member is changed to the radial movement by using the inclined cam surface, the structure is simple, and the power loss and the accuracy deterioration due to the transmission of the gears are reduced. Problem can be avoided.

However, in the third conventional example, in the machining state, the tool holder rotates together with the main shaft, but the drive shaft does not rotate. Therefore, relative rotation occurs at the connection between the piston member and the drive shaft, and friction occurs. There is a concern that heat may increase the amount of thermal expansion and reduce processing accuracy, or that wear may reduce durability.

The third conventional apparatus is intended for a case where a tool holder of a type fixed to a lower end surface of a spindle with a nut, that is, a tool holder of a type different from a type for fixing a general pull stud bolt by pulling with a draw bar is used. When a tool holder of the type in which the above-mentioned general pull stud bolt is pulled and fixed is used, there is a problem that it is difficult to adopt the tool holder as it is.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has a simple structure with little deterioration in accuracy. Also, the processing accuracy and durability due to frictional heat and wear at the connecting portion between the tool holder and the drive shaft. It is an object of the present invention to provide a radial cutting device for a machine tool capable of avoiding the problem of deterioration in performance.

[0012]

According to a first aspect of the present invention, a cutting tool of a tool holder mounted rotatably by a spindle head and mounted on a tip of a spindle driven by a spindle drive mechanism is moved in a radial direction of the spindle. In the radial cutting device of a machine tool, a first rod is rotatably and axially movably inserted into a draw bar of the main spindle, and the first rod is axially moved into the tool holder in a radial direction of the cutting tool. A moving direction changing mechanism for changing the direction of movement is provided, and a second rod having a thread formed on its outer periphery is inserted into the main spindle head in a non-rotatable and axially movable manner, and the second rod and the first rod are relatively moved. Rotatably and axially movably coupled, the second
A nut member is screwed onto the rod, and the nut member is supported by the spindle head so as to be rotatable and immovable in the axial direction. A motor for rotating the nut member is mounted on the spindle head, and the nut member is rotated by the motor. By doing so, the second rod is moved in the axial direction, and the movement of the second rod moves the cutting tool in the main shaft radial direction via the first rod and the moving direction changing mechanism.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 6 are views for explaining a radial cutting device of a machine tool according to an embodiment of the present invention. FIG. 1 is a schematic overall configuration diagram of a spindle head, and FIG. 2 is a diagram of a spindle mounting portion of a tool holder. FIG. 3 is a partial cross-sectional side view of the tool holder, FIG. 4 is a bottom view of the tool holder, FIG. 5 is a schematic cross-sectional view of a moving direction changing mechanism, and FIG.
It is a schematic cross section side view of a rod connection part.

In FIG. 1, reference numeral 1 denotes a spindle head mounted on a column (not shown) so as to be movable in the axial direction (Z-axis direction).
A spindle 2 is inserted and disposed in a cylindrical casing 1a of the spindle head 1, and is supported by bearings 3 and 3 so as to be rotatable and immovable in the axial direction. The spindle 2 is disposed in the casing 1a. It is rotationally driven by the spindle motor 4 housed and arranged. The rotor of the spindle motor 4 is fixed to the spindle 2, and the stator is fixed to the inner surface of the casing 1a.

A tapered hole 2 formed at the lower end of the main shaft 2
The tapered portion 9a of the tool holder 5 is removably fitted and mounted in a. A lower locking portion 6a of the collet 6 is engaged with a locking step 9b formed on the head of the tool holder 5. The upper locking portion 6b of the collet 6 is engaged with a locking groove 7a at the tip of a draw bar 7 which is inserted and arranged in the axial center of the main shaft 2 so as to be movable in the axial direction. 8 urged upward. Thus, the tool holder 5 is fitted and fixed in the tapered hole 2a, and rotates together with the main shaft 2. In FIG. 2, the right side of the spindle axis A indicates the tool holder clamping state.
The left side shows a tool holder unclamped state.

The tool holder 5 has a holder main body 9 and a direction perpendicular to the axis A of the tool holder 5 and the spindle 2 (FIG. 3).
The holder body 9 can be moved in the left-right direction,
And a moving direction changing mechanism 11 for converting the axial movement of a push rod, which will be described later, into a movement perpendicular to the axis, thereby moving the tool holding part 10 in the direction perpendicular to the axis. I have.

A tool 10a is attached to the tool holding portion 10, and a slide flange 10b is integrally formed at an upper end portion. The slide flange 10b is formed by a slide guide hole 9d formed in a lower end portion of the holder body 9. It is movably supported in the direction perpendicular to the axis.

The moving direction changing mechanism 11 inserts and arranges the movable rod 12 slidably in the direction of the main axis A in a slide hole 9c formed in the holder main body 9 so as to be coaxial with the main axis. An inclined cam surface 12a is formed at the lower end of the movable rod 12 so as to be inclined with respect to the spindle axis A, and the inclined cam surface 12a slides on an inclined cam surface 10c formed on a slide flange 10b of the tool holding portion 10. And a double coil spring 13 for urging the tool holding portion 10 to the retracted end position.

The lower end of the push rod 14 and the upper end of the movable rod 12 are connected to or released from the upper end of the movable rod 12 by lowering or raising the push rod 14, which will be described later. A ball catch type coupling / release mechanism 23 is formed. The coupling / release mechanism 23 forms a cylindrical portion 12b at the upper end of the movable rod 12, and retainers 12c, 12c inside and outside the cylindrical portion 12b.
The sleeve 12d can be moved up and down and the springs 12e and 12f
And a plurality of steel balls 12g are interposed in a hole formed in the upper part of the cylindrical portion 12b.

The push rod 14 includes a first rod 15 rotatably and axially movably inserted into a draw bar 7 inserted into the axis of the spindle 2, and the spindle head 1.
And a second rod 16 inserted in the casing 1a so as to be non-rotatable and axially movable.
The first rod 15 is connected to the first rod 15 via a bearing 15c so as to be relatively rotatable and capable of transmitting axial movement. Specifically, as shown in FIG.
5, a plurality of bearings 15c are fixed by nuts 15d, and the bearings 15c are connected to coupling holes 16a of the second rod 16.
And is locked by a lock ring 16b fixed to the second rod 16 side.

The lower end of the first rod 15 is provided with a concave groove 15a which can be engaged with the steel ball 12g, and a small-diameter insertion portion 15b is formed so as to protrude. When the first rod 15 is lowered, the insertion portion 15b enters the retainer 12c of the coupling / disengaging mechanism 23. When the first rod 15 is further lowered, the retainer 12c is pressed downward. And the first rod 15
And the movable rod 12 are connected.

A ball screw is formed on the outer peripheral surface at the center of the second rod 16, and a ball nut (nut member) 18 is screwed onto the second rod 16. The ball nut 18 is supported by a casing 1a of the spindle head 1 via a bearing 19 so as to be rotatable and immovable in the axial direction.

A spline 16c is formed on the outer peripheral surface of the upper end of the second rod 16, and meshes with a spline groove formed on the casing 1a side. As a result, the second
The rod 16 cannot rotate and can move in the axial direction.

A driven pulley 18a is connected to the upper end of the ball nut 18.
a is a drive pulley 2 of a servomotor 21 driven by a belt 20.
1a. Thus, the push rod 1 is rotated via the ball nut 18 by the rotation of the servomotor 21.
Push rod moving mechanism 2 for moving spindle 4 in the spindle direction
2 are configured.

An unclamping cylinder mechanism 17 is provided in the casing 1a of the spindle head 1 so as to surround the joint between the first and second rods 15, 16. In the unclamping cylinder mechanism 17, a cylindrical piston 17b surrounding the connecting portion is inserted and arranged in a cylinder 17a fixed to the casing 1a side, and the piston 17b is urged in a clamping direction (upward) by a return spring 17c. The lower end surface of the piston 17b is
Opposes the upper end surface. Therefore, when the piston 17b moves downward, the draw bar 7 lowers the collet 6 to the unclamping position of the tool holder 5.

Next, the operation and effects of the present embodiment will be described. When the spindle motor 4 rotates with the tool holder 5 clamped to the lower end of the spindle 2, the tool holder 5 rotates together with the spindle 2, and cutting is performed by the cutting tool 10a of the tool holding unit 10.

When replacing the tool holder 5, hydraulic pressure is supplied to the unclamping cylinder mechanism 17 and the piston 17
b descends to lower the draw bar 7 against the urging force of the disc spring 8, and the engagement between the lower locking portion 6a of the collet 6 and the locking step 9b of the tool holder 5 is released. 5 is unclamped from the tapered hole 2a. When a new tool holder 5 is fitted into the tapered hole 2a and the hydraulic pressure to the unclamping cylinder mechanism 17 is eliminated, the draw bar 7 is raised by the urging force of the disc spring 8, and the collet 6 is moved to the tool holder 5
And the tool holder 5 is clamped in the tapered hole 2a.

When controlling the radial position of the cutting tool 10a of the tool holder 5 in the main shaft direction, that is, the cutting amount, the push rod 14 descends with the rotation of the servomotor 21, and the insertion portion at the lower end of the first rod 15 is inserted. 15b is retainer 1
Enter within 2c. When the first rod 15 further descends, the retainer 12c is pushed down, and the sleeve 1
2d rises and the steel ball 12g is inserted into the concave groove 15 of the first rod 15.
a, and the first rod 15 and the movable rod 12 are coupled.

After the first rod 15 and the movable rod 12 are connected, the inclined cam surface 12a of the movable rod 12 slides on the inclined cam surface 10c of the tool holding portion 10 as the push rod 14 is lowered and raised. As the movable rod 12 descends, the tool holding unit 10 moves in the radial direction, and the radial cutting amount by the cutting tool 10a increases.

When the control of the cutting depth in the radial direction of the cutting tool 10a is not performed, the lower end surface of the push rod 14 is caused to interfere with the tool holder 9 by the rotation of the servomotor 21. Raise so that it is not in the original position. Thereby, the first rod 15
And the movable rod 12 are released, and the tool holder 10
Is biased and held at a reference radial position by the double coil spring 13.

As described above, according to the present embodiment, the push rod 14 is connected to the servo motor 21 and the ball nut 18.
The push rod moving mechanism 22 is configured to move in the axial direction, and the axial movement is converted into the radial movement of the tool holder 10 by the inclined cam surfaces 12a and 10c. The structure is extremely simple as compared with a device having a gear mechanism or the like.

When the push rod 14 is located at the original position, the connection between the push rod 14 and the movable rod 12 of the tool holder 5 is released, and the push rod 1
Since the tool 4 does not interfere with the tool holder 5, it can be set on the main spindle 2 without any problem even with a normal tool holder having no cutting amount control function.

A ball catch type coupling / release mechanism 23
, The push rod 14 and the movable rod 1
The connection with the cable 2 and the release thereof are automatically performed only by moving the push rod 14 a predetermined distance in the main axis direction, and a dedicated device such as the above-described conventional device is not required.

In this embodiment, the push rod 1
4 is divided into a first rod 15 rotatably and axially movably inserted into the main shaft 2 and a second rod 16 arranged above the main shaft 2 so as to be non-rotatably and axially movable, Since the first and second rods 15 and 16 are connected so as to be relatively rotatable and capable of transmitting the axial movement, the first rod 15 rotates together with the main shaft 2 in the machining state. Relative rotation does not occur between the movable rod 12 and frictional heat and wear can be avoided.

In the above embodiment, the cut amount of the cutting tool 10a is adjusted by moving the push rod 14 in the axial direction.
The structure for moving in the axial direction is applicable to applications other than the above.

For example, as shown in FIG. 7, when a tool holder 5 with a built-in drive motor is used, a contact power supply mechanism 31 for electric power is provided between the lower end of the push rod 14 and the upper end of the movable rod 12. The power supply member 3 of the mechanism 31
1a is fixed to the push rod 14 side, the cable 32 connected to the power supply member 31a is connected to a power source through the push rod 14, and the power receiving member 31b is fixed to the movable rod 12 side and connected to the power receiving member 31b. The cable 33 is connected to the motor through the movable rod 12. Also, compressed air and hydraulic oil can be supplied instead of the power supply.

[0037]

As described above, according to the radial cutting device for a machine tool according to the first aspect of the present invention, the second rod is moved in the axial direction by rotating the nut member by the motor. The directional movement is transmitted to the moving direction changing mechanism via the first rod, and the moving direction changing mechanism moves the cutting tool in the radial direction, thereby providing an effect of realizing the adjustment of the radial cutting amount with a simple structure.

When the rotation of the motor is converted to the axial movement, the first rod and the second rod are connected so as to be rotatable relative to each other, so that the first rod rotates with the main shaft in the working state, and thus rotates with the main shaft. Relative rotation does not occur between the movement direction changing mechanism and the first rod, so that frictional heat and wear caused by the relative rotation can be avoided, and there is an effect that a reduction in machining accuracy and durability can be avoided.

[0039]

[Brief description of the drawings]

FIG. 1 is a schematic overall configuration diagram of a spindle head for explaining a radial cutting depth control device for a machine tool according to an embodiment of the present invention.

FIG. 2 is a sectional side view around a spindle mounting portion of a tool holder of the apparatus of the embodiment.

FIG. 3 is a partial cross-sectional side view of a tool holder of the embodiment device.

FIG. 4 is a bottom view of a tool holder of the apparatus according to the embodiment.

FIG. 5 is a schematic sectional view of a moving direction changing mechanism part of the apparatus according to the embodiment.

FIG. 6 is a schematic cross-sectional side view of first and second rod coupling portions of the embodiment device.

FIG. 7 is a schematic sectional side view showing an application example of the present invention.

[Explanation of symbols]

 Reference Signs List 1 spindle head 2 spindle 4 spindle motor (spindle drive mechanism) 5 tool holder 10a blade 11 moving direction changing mechanism 15 first rod 16 second rod 18 ball nut (nut member) 21 servo motor

Claims (1)

[Claims] 1. A radial cutting device for a machine tool, wherein a cutting tool of a tool holder mounted on a tip of a spindle rotatably supported by a spindle head and rotatably driven by a spindle drive mechanism is moved in a spindle radial direction. The first rod is rotatably and axially movably inserted into the draw bar of
A moving direction changing mechanism for converting the axial movement of the first rod into a radial movement of the cutting tool in the tool holder;
A second rod having a thread formed on its outer periphery is inserted into the spindle head so as to be non-rotatable and axially movable, and the second rod and the first rod are connected so as to be relatively rotatable and axially movable. A nut member is screwed onto the second rod, the nut member is supported by the spindle head so as to be rotatable and immovable in the axial direction, and a motor that rotationally drives the nut member is mounted on the spindle head. Rotating the nut member moves the second rod in the axial direction, and moving the second rod moves the cutting tool in the main shaft radial direction via the first rod and the moving direction changing mechanism. Radial cutting device for machine tools.