JP2560699Y2 - Contact detection device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact detecting device for detecting a point of time when a rotating body comes into contact with a machine tool.

[0002]

2. Description of the Related Art In a grinding machine that controls the feed of a grinding wheel by a CNC device, the position of the grinding wheel surface and the mutual positional relationship between the workpiece and the workpiece are accurately measured in order to keep the processing dimensional accuracy within a certain tolerance. I have. Also, when performing truing to maintain the grinding wheel surface in a state where good grinding can be performed, the mutual positional relationship between the truer and the grinding wheel surface is accurately checked, and the truing is completed with the minimum cutting operation, so the detection pin is Contact detection is performed by detecting an AE (acoustic emission) signal generated when the wheel comes into contact with the grindstone.

[0003]

[Problems to be Solved by the Invention] Conventional contact detection is
A detection pin equipped with an E sensor is brought to the surface of the rotating grindstone by a very small amount, and a contact signal is issued when the AE signal of a specific range of frequencies generated by the contact reaches a certain level as a contact point. . However, a pseudo AE wave may be generated when the coolant that rotates with the grindstone comes into contact with the detection pin, and the disturbance phenomenon adversely affects the contact detection accuracy.

An object of the present invention is to detect a contact in accordance with an AND condition with the pressure of a hydrostatic bearing so that the contact can be accurately detected without being affected by a pseudo AE wave generated at the time of the contact detection. An object of the present invention is to provide a contact detection device as described above.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is characterized in that a contact between a rotating shaft rotatably supported by a hydrostatic bearing and a rotating body attached to the rotating shaft is provided. A detection pin having an AE sensor for detecting, a pressure sensor for detecting the pressure of the hydrostatic bearing, and a control circuit for outputting a contact signal only when a detection signal of a certain level or more is output from each of the AE sensor and the pressure sensor. It is provided with.

[0006]

According to the above construction, when the rotating body comes into contact with the detection pin, a detection signal is output from the AE sensor, and the static pressure bearing fluctuates in pressure when the detection pin comes into contact with the rotating body. Detection is performed by the pressure sensor, and a detection signal is output from the pressure sensor. The time when these two detection signals reach a certain level is regarded as true detection, and a contact signal is transmitted to perform accurate contact detection.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a grindstone table, 2 is a feed screw for moving the grindstone table 1 forward and backward, 3 is a servo motor for rotating the feed screw 2 forward and reverse, 4 is a rotation amount of the servo motor, that is, a grindstone table. An encoder 5 for detecting the position 1 is a nut that is screwed to the feed screw 2 to move the grindstone table 1.

Reference numeral 6 denotes a grindstone shaft (rotary shaft) rotatably supported by a hydrostatic bearing 8. The grindstone shaft 6 has a grindstone 7.
(Rotating body) is attached.

The static pressure bearing 8 has a static pressure pocket 8a. Oil is supplied to the static pressure pocket 8a from a bearing oil supply pump 10 through a fixed throttle 9, and the static pressure bearing 8 supports the grinding wheel shaft 6. The static pressure pocket 8a includes a static pressure pocket 8
a pressure sensor 11 for detecting pressure fluctuations in

Reference numeral 12 denotes a coolant nozzle, which is supplied with coolant from a coolant supply pump 13 and applies coolant during grinding of a workpiece, and a detection pin 16 described later.
When the grindstone 7 is brought into contact with the coolant, the supply of the coolant is stopped.

Reference numeral 14 denotes a headstock provided in front of the wheel head 1 in the feed direction. A detection pin 16 is held by the headstock 14 via a bracket 15. An AE sensor 17 is bonded to the rear end of the detection pin 16 by an adhesive in a state where vibration can be propagated.

The pressure sensor 11 is connected to a filter 18a for passing a signal of a specific frequency, and the filter 18a is connected to a comparator 19a to which a setter 20a is connected.
It is connected to the.

The AE sensor 17 is also connected to a filter 18b which passes a signal of a specific frequency. The filter 18b is connected to a comparator 1 to which a setting unit 20b is connected.
9b.

The comparators 19a and 19b compare the signal of a specific frequency filtered by the filters 18a and 18b with a fixed level set by setting devices 20a and 20b. The ON signal is transmitted only when the signal becomes.

The comparators 19a and 19b are connected to an AND circuit 21. The AND circuit 21 transmits a contact signal to a monitor (not shown) only when two ON signals from the comparators 19a and 19b are transmitted simultaneously. The filters 18a, 18b and the comparators 19a, 1
9b, the setting devices 20a and 20b, and the AND circuit 21 constitute a control circuit that outputs a contact signal in accordance with the AND condition of the detection signal from the AE sensor 17 and the detection signal from the pressure sensor 11.

Since the present invention has the structure as described above, after grinding the work, if the grindstone 7 is fed forward before truing, the grindstone 7 comes into contact with the detection pin 16 and a detection signal of a certain frequency is output from the AE sensor 17. Put out. Further, in the static pressure bearing 8, when the detection pin 16 comes into contact with the grindstone 7, the pressure in the static pressure pocket 8 a fluctuates. This pressure fluctuation is detected by the pressure sensor 11, and a detection signal of a certain frequency is output from the pressure sensor 11. . That is, the AE sensor 17 of the detection pin 16 that has come into contact with the grindstone 7 receives an ultrasonic wave of a predetermined frequency,
Pseudo AE due to the impact force when the coolant rotating with the grindstone 7 comes into contact with the detection pin 16 or other noise
Waves are also received.

These two detection signals are filtered by filters 18a and 18b to specific frequencies only, and the two filtered signals are compared by comparators 19a and 19b. 19
a and 19b transmit an ON signal.

When the AND circuit 21 receives two ON signals from the comparators 19a and 19b at the same time, the AND circuit 21 transmits a contact signal to the monitor as a true detection, and the contact signal displayed on the monitor. As the detection signal, a contact detection signal with high accuracy excluding the influence of the coolant and the disturbance phenomenon of the pseudo AE wave due to other noise can be obtained. By reading the output of the encoder 4 when this contact signal is obtained, the coordinates of the tip of the grinding wheel or the diameter of the grinding wheel can be detected.

[0019]

As described above, the present invention provides a rotary shaft rotatably supported by a hydrostatic bearing, a detection pin provided with an AE sensor for detecting contact with a rotary body attached to the rotary shaft, Since it has a pressure sensor that detects the pressure of the hydrostatic bearing, and a control circuit that outputs a contact signal only when a detection signal of a certain level or more is output from each of the AE sensor and the pressure sensor, the rotating body is A contact signal is obtained by using both a detection signal when a contact is made with the detection pin and a pressure fluctuation detection signal of the pocket pressure of the hydrostatic bearing of the rotating body at this time, so that highly reliable detection is obtained. The accuracy is improved.

[Brief description of the drawings]

FIG. 1 is a structural view of the device of the present invention.

[Explanation of symbols]

 Reference Signs List 1 wheel head 6 wheel shaft 7 wheel 8 static pressure bearing 8a static pressure pocket 11 pressure sensor 14 headstock 16 detection pin 17 AE sensor 18a filter 18b filter 19a comparator 19b comparator 20a setting device 20b setting device 21 AND circuit

Claims (1)

(57) [Scope of request for utility model registration] A rotating shaft rotatably supported by a hydrostatic bearing, a detecting pin provided with an AE sensor for detecting contact with a rotating body attached to the rotating shaft, and detecting a pressure of the hydrostatic bearing. A contact detection device comprising: a pressure sensor; and a control circuit that outputs a contact signal only when a detection signal of a certain level or more is output from each of the AE sensor and the pressure sensor.