JPH04294959A - Support device for spindle of machine tool - Google Patents

Abstract

PURPOSE:To restrain the vibration level of a spindle lower with the vibration frequency based on the rotation number of the spindle conformed to the proper vibration number of the whole spindle device being evaded. CONSTITUTION:One part of the spindle head 3 installed movably to a column 1 is engaged in a press-fitting state to the column 1 by engageable connection devices 6, 7. To this connection device 6, 7 an engaging drive command is given according to the rotation number of a spindle 4 from a rotation number responding engaging command means 10.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle support device for a machine tool that is applied to machining centers, turning centers, lathes, and the like.

0002

2. Description of the Related Art Conventionally, in order to cope with higher speed rotation of the spindle, a built-in motor type spindle head 33 in which a motor 32 is integrated with a spindle 31, as shown in plan and side views in FIGS. 4 and 5, has been used. Proposed.

The spindle head 33 is guided in a vertically movable manner by a linear guide 17 provided between a flange 33a protruding from both sides thereof and a column 34, and is movable vertically by an elevating drive source (not shown). It is said that Since the motor 32 is integrated so as to surround the spindle 31, the motor housing 35 is attached to the spindle head 33.
The spindle head 33 extends in the axial direction of the spindle 31 at the rear thereof, and the spindle head 33 is generally supported by a column 34 in a cantilevered manner.

0004

[Problem to be solved by the invention] However, the spindle 3
As the maximum rotational speed of the spindle 31 increases, the rotational range expands, and the natural frequency of the spindle head 33 and the basic rotational frequency of the spindle 31 match, so that there is a rotational speed at which the vibration level reaches its peak due to resonance. became. Therefore, there is a problem in that the rear part of the spindle head 33, that is, the side of the motor housing 35 vibrates, reducing machining accuracy.

FIG. 6 shows the spindle 3 in the above conventional example.
1 is a graph showing the correspondence between the number of rotations and its vibration level, where the horizontal axis represents the number of rotations and the vertical axis represents the vibration level. As is clear from this figure, the peak of the vibration level appears when the rotational speed of the spindle 31 is around Arpm and Brpm. That is, at these rotational speeds, the basic rotational frequency of the spindle 31 and the natural frequency of the spindle head 33 match and resonate.

[0006] As described above, the phenomenon in which the vibration frequency corresponding to the rotation speed of the spindle matches the natural frequency of the spindle head and the vibration level of the spindle reaches its peak is limited to the above-mentioned built-in motor type spindle device. The same problem occurs in spindle devices configured to transmit the rotation of a motor to a spindle via a transmission mechanism, although there are differences in degree.

An object of the present invention is to provide a spindle support device that can suppress the vibration level of the spindle to a low level by preventing the vibration frequency based on the rotational speed of the spindle from matching the natural frequency of the spindle head. That's true.

[0008]

[Means for Solving the Problems] The structure of the present invention will be explained with reference to FIG. 1 corresponding to an embodiment. This invention is based on the column (
1) is a spindle support device in which a spindle head (3) is installed, and a coupling device (6), ( 7). Further, a rotational speed responsive engagement/disengagement command means (10) is separately provided which gives an engagement/disengagement drive command to the coupling devices (6), (7) according to the rotational speed of the spindle (4).

[0009]

[Operation] When the rotational speed of the spindle (4) reaches a rotational speed that resonates with the natural frequency of the spindle head, the rotational speed responsive engagement/disengagement command means (10) engages the coupling devices (6) and (7). A de-drive command is given. In response to this command, the coupling devices (6), (7) engage a part of the spindle head (3) with the column (1) in a press-contact state. As a result, the natural frequency of the spindle head is changed to a value that does not resonate with the rotational speed of the spindle (4) at this time, and the vibration level is suppressed to a low level.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a perspective view showing a column section of a machining center, and FIG. 2 is a horizontal sectional view thereof. In these figures, a column 1 is formed in an inverted U-shape with side plates 2 on both sides, and a spindle head 3 has a linear guide provided between the side plates 2 and guide flanges 3a (Fig. 2) protruding from both sides. 17, it is installed in the column 1 so as to be able to rise and fall freely.

A motor (not shown) for driving the spindle 4 is a built-in type motor integrated into the rear part of the spindle head 3, and the motor housing 5 is shown in the figure.

Actuators 7 for moving the ratchets 6 in and out toward the side plates 2 are provided on portions of the outer peripheral surface of the motor housing 5 facing the side plates 2 on both sides of the column 1, respectively. Furthermore, engagement grooves 2b that engage with the ratchets 6 are vertically formed in the inward surfaces of each side plate 2 of the column 1, in portions that face the ratchets 6 of the actuator 7.

Hydraulic pressure or air pressure for driving each actuator 7 is supplied from a pressure source 8 through a pressure supply hose 9 as shown in FIG. 2, and a control circuit 10 for controlling the drive is provided as shown in FIG. electrically connected as shown.

The control circuit 10 includes a rotation speed detection unit 11 that detects the rotation speed of the spindle 4, and converts the detected rotation speed into a preset rotation speed, that is, the rotation speed of the entire spindle device including the column 1 and the spindle head 3. A rotation speed comparing unit 12 compares the natural frequency with the resonant rotation speed and determines whether these substantially match, and when it is determined that the rotation speeds match, the ratchet 6 is opposed to the actuator 7. and a signal generating section 13 that gives a command to engage the engaging groove 2b of the side plate 2 in a press-contact state.

Next, the operation of the above configuration will be explained. When the spindle 4 is in a non-rotating state, the ratchet 6 is recessed into the actuator 7, and the motor housing 5 at the rear of the spindle head 3 and the side plate 2 of the column 1 are separated. The spindle 4 is rotationally driven by a motor integrated into the spindle head 3, and cutting is performed by a tool (not shown) installed in a tool attachment hole (not shown) at the tip of the spindle 4.

When the rotational speed of the spindle 4 increases and reaches a rotational speed at which the spindle 4 resonates with the natural frequency of the spindle head 3, an engagement drive command is given from the control circuit 10 to the actuator 7. In response to this, the ratchet 6 protrudes from the actuator 7, and the ratchet 6 engages with the engagement groove 2b of the side plate 2 of the column 1 so as to be in pressure contact. Thereby, the column 1 and the rear part of the spindle head 3, that is, the motor housing 5 are connected via the ratchet 6.

As a result, the natural frequency of the spindle head 3 changes, the rotational speed of the spindle 4 no longer resonates with the natural frequency of the spindle head 3, and the vibration level at this time is significantly reduced.

FIG. 3 is a graph showing changes in the vibration level as the natural frequency changes, with the horizontal axis representing the rotational speed of the spindle 4, and the vertical axis representing the level of vibration occurring in the spindle 4. The broken line graph shows the vibration level when the column 1 and the motor housing 5 are not connected by the ratchet 6, and the solid line graph shows the vibration level when the ratchet 6 is connected as in the example. Each level is indicated.

In the figure, the number of rotations of the spindle 4 is N.
a, the vibration level would normally resonate with the natural frequency of the spindle head 3 and the vibration level would reach a peak value Va as shown by the broken line graph, but in this embodiment, the natural vibration of the spindle head 3 is reduced by the coupling action of the ratchet 6. As the number changes, the vibration characteristics change as shown by the solid line graph. That is, the vibration level at this time is suppressed to V'a, which is sufficiently lower than the peak value Va.

When the rotation speed of the spindle 4 further increases above Na, a disengagement command is given to the actuator 7 from the control circuit 10 to disengage the ratchet 6, thereby causing the side plate 2 of the column 1 and the motor to be disengaged. The housing 5 is separated back to its original state. Therefore, Figure 3
Even if the rotational speed Nb increases to the peak value of the solid line graph in , the vibration level is suppressed to the vibration level V'b of the broken line graph at this rotational speed Nb.

[0021] In the above embodiment, a case was explained in which the spindle head 3 is of a built-in motor type, but other types such as a type in which the rotation of an external motor is transmitted to the spindle via a transmission mechanism are also applicable. May be applied to Further, in the embodiment, the case of the spindle head 3 of a machining center has been described, but the present invention may be applied to a spindle head of other machine tools such as a milling machine and a turning center. The spindle head may be fixed in position.

[0022]

Effects of the Invention In the spindle support device for a machine tool of the present invention, when the rotational speed of the spindle reaches a rotational speed that resonates with the natural frequency of the spindle head, the rotational speed responsive engagement/disengagement command means engages the coupling device. A disengagement command was given, and in response to that command, the coupling device engaged a part of the spindle head in pressure contact with the column, so the natural frequency of the spindle head was set to a value that did not resonate with the rotational speed of the spindle at this time. can be changed to Therefore, there is an effect that the vibration level can be suppressed to a low level over a wide range of rotational speeds.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a horizontal sectional view of the embodiment.

FIG. 3 is a graph showing vibration characteristics according to the example.

FIG. 4 is a cutaway plan view showing a conventional example.

FIG. 5 is a cutaway side view of the conventional example.

FIG. 6 is a graph showing vibration characteristics according to the conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Column, 2... Side plate, 2b... Engagement groove, 4... Spindle, 5... Motor housing, 6... Ratchet, 7... Actuator, 10... Control circuit

Claims (1)

[Claims] [Claim 1] A spindle head is installed in the column,
A rotation speed-responsive engagement/disengagement command means for providing a coupling device capable of engagement and disengagement for engaging a part of the spindle head with the column in a press-contact state, and giving an engagement/disengagement driving command to the coupling device according to the rotation speed of the spindle. Spindle support device for machine tools equipped with