JPH063340A - Method for retaining ultrasonic probe - Google Patents

Abstract

PURPOSE:To obtain such an actuator that can easily adjust the pressing pressure of an ultrasonic probe against an object to be inspected for an automatic nondestructive inspection device using the ultrasonic probe. CONSTITUTION:An automatic inspection device is constituted of a pinion 4 installed to the rotating shaft of a DC motor 5, rack 3 engaged with the pinion 4, controller which adjusts the impressed current of motor 5, and ultrasonic probe 1 held by a gimbal 2 installed at the front end of the rack 3. When the impressed current of the motor 5 is adjusted, the pressing pressure of the probe 1 against an object 6 to be inspected can be adjusted to an arbitrary value. Therefore, the optimum contact pressure can be obtained between the probe 1 and object 6 and a remote automatic flaw detecting using the probe 1 can effectively become independent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a remote automatic flaw detector using ultrasonic waves, and particularly to a contact pressure for pressing an ultrasonic probe against the surface of an object under the condition that the rotation of an electric motor is restricted. The present invention relates to a method of holding an ultrasonic probe that is suitable for adjusting an optimum contact pressure by using a torque.

[0002]

2. Description of the Related Art In a conventional remote automatic flaw detector using ultrasonic waves, in order to press the ultrasonic probe along the surface of a subject with a constant pressure, a material having elasticity is used and constantly pressed. Measures are taken so that it can be done. Among these methods, there is a method using a coil spring, but since the acting direction is one direction, it is not often used in an automatic inspection device. Generally, as described in Japanese Patent Publication No. 1-56703, a method using an air cylinder as an actuator is often used.

[0003]

The above-mentioned prior art requires a compressor as a power source of an air cylinder which is an actuator, and uses an inflexible air hose for propagating air compressed by the compressor. For this reason,
The air hose must be bent to some extent when driving the ultrasonic probe, and the posture of the ultrasonic probe changes due to the increase in power required for this bending and the reaction force generated at this time, and positioning accuracy is increased. It is also a cause of poor operability. Further, since air cylinders generally have poor characteristics during low-speed operation and stick slips are particularly likely to occur, the performance of following changes such as waviness on the surface of the subject may be adversely affected.

An object of the present invention is to provide a method for holding an ultrasonic probe which can easily scan the surface of a subject in an automatic inspection apparatus using ultrasonic waves.

[0005]

In order to achieve the above-mentioned object, an ultrasonic probe holding method of the present invention includes an electric motor for pressing the ultrasonic probe and a generated torque for the ultrasonic probe. The maximum value of the current applied to the mechanism and the motor transmitted to the child was defined as the stall current.

[0006]

According to the present invention, the temperature rise of the electric motor is suppressed by pressing the ultrasonic probe against the subject using the stop torque obtained by restraining the rotation of the electric motor and adjusting the applied current flowing through the electric motor. Since it can be eliminated and an arbitrary torque can be generated, and the pressure can be released or released from the subject by changing the direction of the current, it is possible to improve the operability of the ultrasonic probe. Can be done.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a scanner 10 of a remote automatic flaw detector is shown.
It is attached to the holder 9 of the pinion 4
A DC motor 5 mounted with and a freely rotatable guide roller 8 are supported. The ultrasonic probe 1 is held at the center position of a gimbal 2 which is rotatable in the XY directions, and the gimbal 2 is supported by a rack / pinion type rack 3 which can move in the Z-axis direction. Is held so as to be sandwiched between the guide roller 8 and the pinion 4, and the power of the DC motor 5 is transmitted to the rack 3 of the drive mechanism by meshing with the pinion 4. Now, when a current is applied to the DC motor 5 so that the rack 3 operates downward, the rack 3 starts moving downward, and when the ultrasonic probe 1 contacts the subject 6, the movement ends. Even after this, the DC motor 5 tries to continue to rotate, but its movement is mechanically restrained, so that the rotation is stopped but the torque corresponding to the applied current is continuously generated. Therefore, the ultrasonic probe 1 continues to contact the subject 6 while being pressed with a constant torque corresponding to the applied current.

Generally, in a DC motor, the relationship between the applied current and the torque is proportional, and the torque of the DC motor can be easily adjusted only by adjusting the applied current. The DC motor 5 does not need to control the position and speed, and may control only the magnitude and direction of the torque. Therefore, it suffices to control the value and direction of the applied current corresponding to the magnitude of the torque, and this can be easily realized by using a constant current circuit or the like normally used for motor control.

The contact pressure between the ultrasonic probe 1 and the subject 6 is determined only by the torque of the DC motor 5 if the mass W of the ultrasonic probe 1, the gimbal 2 and the rack 3 is ignored. Therefore, the value P obtained by dividing the torque by the radius of the pinion 4
That is, the size is the same and constant regardless of the position of the rack 3. However, the mass W of the ultrasonic probe 1, the gimbal 2, the rack 3, etc. cannot be ignored, and the magnitude of the contact pressure depends on the mass W and the torque of the ultrasonic probe 1, the gimbal 2, the rack 3, etc. Pressed by P
The value Q obtained by adding is the contact pressure of the ultrasonic probe 1, and Q
The value of P is determined by adjusting the current applied to the DC motor 5 so that the value of becomes a predetermined contact pressure. If the value of the applied current is kept constant in this way, the operation of the DC motor 5 always acts so that the pressing force is P, so that it becomes an actuator having elasticity, so that the surface of the subject 6 is undulated. Even if there is, the pressure P is maintained at a predetermined contact pressure. If the mass W of the gimbal 2 or the like is larger than the predetermined contact pressure, the pressure acts upward by adjusting the direction and magnitude of the current applied to the DC motor 5 so as to reduce the difference. As described above, it is possible to easily generate the torque and maintain the predetermined contact pressure. In this way, the rotor of the DC motor 5 can be used like an air cylinder by allowing a constant applied current to flow while restraining the rotation of the DC motor 5. If there is a large foreign substance in the scanning direction of the ultrasonic probe 1, another sensor generates an abnormal signal to reverse the DC motor 5 and pull up the ultrasonic probe 1 to raise the foreign substance. You can also pass through.

When the rotation of the DC motor is restricted and used as in the embodiment, the motor is not sufficiently cooled, and if the applied current is used up to the rated value, the temperature rises due to heat generation. To prevent this, the maximum value of the applied current may be limited to a stall current peculiar to the motor.

In this embodiment, the rack 3 is used as the torque transmission mechanism.
The pinion 4 system has been described above, but the present invention can be implemented by applying other methods such as a method using a lever and a cam.

[0012]

According to the present invention, by restraining the rotation of the DC motor and pressing the ultrasonic probe with its stop torque, it can be used as an elastic actuator instead of the air cylinder, and the applied current An arbitrary contact pressure can be easily obtained by adjustment, and the motor can be used normally by using it at a stall current or less. In particular, it is effective for making a remote automatic flaw detector using an ultrasonic probe independent.

[Brief description of drawings]

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

[Explanation of symbols]

1 ... Ultrasonic probe, 2 ... Gimbal, 3 ... Rack, 4 ... Pinion, 5 ... Motor, 6 ... Subject.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Kajiyama 1168 Moriyama-cho, Hitachi-shi, Ibaraki Pref., Energy Research Laboratory, Hiritsu Manufacturing Co., Ltd.

Claims (2)

[Claims] 1. A remote automatic flaw detection apparatus for performing flaw detection inspection or the like by scanning along a surface of a subject using an ultrasonic probe, which is provided at a tip portion of the flaw detection apparatus or an XY scanner, and is attached to a gimbal The ultrasonic probe provided, an electric motor as an actuator that presses these against the subject, a drive mechanism including a mechanism for transmitting torque generated by the electric motor, and suppression of rotation of the electric motor Then, the method for holding an ultrasonic probe is characterized by comprising an electric motor used as an actuator having elasticity by using a torque generated while the rotation is stopped. 2. The method for holding an ultrasonic probe according to claim 1, wherein a maximum value of a current applied to the electric motor is a stall current.