JPS58126044A - Monitoring device for unbalance vibration of main shaft - Google Patents

Abstract

PURPOSE:To coincide the sense of human with a decision level by a method wherein the unbalance vibration of the main shaft is detected by the speed of the vibration to dicide an abnormal condition. CONSTITUTION:In case a tool 12, attached to the main shaft 11, is rotated, the unbalance vibration of the main shaft is detected by the vibrating speed through a displacement detector 13 provided on the head 10 of the main shaft. An abnormal signal NG is outputted when the vibrating speed A has become larger than a standard value B while a normal signal OK is outputted when it is smaller than the standard value B. Since the vibration sensing characteristics of human at operation is proportional to rather the speed of the vibration than the amplitude of the same, a certain deviation is caused from the sense of human at operation in case the decision standard of a decision unit is defined by the amplitude, however, the decision level of both human at operation and decision unit coincides by deciding the vibration through the speed as the reference of the decision.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a spindle unbalance vibration monitoring device that monitors all unbalance vibrations of a spindle equipped with a tool so that cutting can always be performed in a normal state. The present invention relates to the above-mentioned vibration monitoring device suitable for a machine tool that performs complete cutting of objects.

The purpose of the present invention is to capture the unbalanced vibration of the spindle as a speed value, and to make it possible to determine the abnormal state of the spindle unbalanced vibration by comparing it with a predetermined speed tolerance regardless of the spindle rotation speed. That's true.

Generally, in machine tools such as machining centers,
The spindle rotation speed is varied from several tens of revolutions per minute to nearly 10,000 revolutions per minute depending on the various tools attached to the spindle. In such a machine tool, when various tools are attached and the spindle is rotated, the spindle vibrates uncontrollably, and if this vibration becomes large, it becomes impossible to ensure the required machining accuracy. For this purpose, the unbalanced vibration of the main shaft is detected as a vibration displacement, and this is compared with a certain displacement tolerance value to detect an abnormal state of the unbalanced vibration of the main shaft.

However, when considered from the sensory and psychological aspects of humans, in the case where the above-mentioned fixed vibration displacement tolerance is the standard, the sensory impact on humans, especially during high-speed rotation,
It has a large psychological effect, and even if there is no problem with machining accuracy, it may be perceived as an abnormal state due to the sense of vibration, which is not realistic.

This means that the human vibration sense has a frequency of 8H2 or higher (480rp).
This is due to the fact that the vibration velocity is close to the vibration velocity and does not match the vibration displacement.

Therefore, in order to manage the unbalanced vibration of the spindle in a manner that satisfies the machining accuracy at any spindle rotation speed and does not cause the unbalanced vibration of the spindle to be perceived as an abnormal state from the sense of vibration,
This system captures unbalanced vibration as a speed value and compares it with a certain speed tolerance to identify all abnormal conditions.

Embodiments of the present invention will be described below with reference to all the drawings.

In Figure 1, 10 is, for example, the spindle head of a numerically controlled machine tool equipped with an automatic tool change bag @? Various tools 12 are sequentially attached to a main shaft 11 supported by the main spindle head 10 according to a predetermined cutting program, and are driven to rotate at a set rotational speed. An electrodynamic displacement detector 13 is attached to the spindle head lO, and this displacement detector 13 detects unbalanced vibrations caused by rotation of the spindle 11 as a speed value, and inputs the detection signal to the full amplifier 14.

A comparator 15 is connected to the amplifier 14.
The speed value A output from the displacement detector 13 is compared with the speed tolerance value B set by the setting device 16, and if the speed value A is smaller than the speed tolerance value B, an OK double signal is issued, and vice versa. In this case, the discriminator 17 outputs an NG signal.

FIG. 2 shows the vibration frequency f (f
This is experimental data investigated from the perspective of the vibration sensation experienced by humans due to the unbalanced vibration of the vibration velocity Vf main axis 11 with respect to the vibration velocity (N/6 Q). This figure shows all the areas where the vibration is felt to be small.This figure shows that regardless of the vibration frequency f (spindle rotation speed N), at a certain speed value of 71 or above, the vibration sensation given to humans is large, and when the speed value is below 1 Furthermore, it has been found that machining accuracy can be well guaranteed when cutting is performed under unbalanced vibration of the spindle at a speed value v1 or less.

Therefore, by setting the speed value 1 as the speed tolerance value B in the setting device 16, the speed value A detected by the displacement detector 13 and the setting device 1 can be set at any spindle rotation speed.
It is possible to determine the abnormal state of unbalanced vibration of the main shaft 11 by comparing it with the speed tolerance value B (Vl) set to N.
When the G signal is sent out, cutting is not performed to prevent a decrease in machining accuracy.

As described above, the present invention has a configuration in which the unbalanced vibration of the spindle is captured as a speed value, and the abnormal state of the unbalanced vibration can be determined by comparing it with a certain speed tolerance value. Also, by comparing with a certain speed tolerance value, machining accuracy can be satisfied, and there is an effect that management can be easily carried out so that it is not detected as an abnormality or condition from the vibration sense.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention. Fig. 1 is a block diagram schematically showing a spindle unbalance vibration monitoring device, and Fig. 2 shows the relationship between vibration frequency and vibration speed. This is the experimental data shown. 10...Spindle head, 11...Spindle, 12・φ・tool,
13...Detector, 14...Amplifier, 15...Comparator, 16...Setter, 17...Discriminator. Patent applicant Toyota Machinery Co., Ltd.

Claims (1)

[Claims] (1) A detector for monitoring all unbalanced vibrations of a spindle that is mounted with a tool and rotated at various rotational speeds, and detects unbalanced vibrations of the spindle generated by the rotation of the spindle as a speed value; The spindle imbalance is characterized by comprising a comparison and determination device that compares the speed value detected by the detector and the speed tolerance value set by the setting device to determine an abnormal state of the unbalanced vibration. Vibration monitoring equipment.