Automatic ultrasonic testing apparatus for detecting flaws of balls

Abstract: An immersion type automatic ultrasonic testing apparatus for detecting flaws of balls has a tank for containing a liquid medium for transmitting ultrasonic waves, a ball rotating device for rotating a ball to be tested, and an ultrasonic flaw detection device for detecting flaws in the ball. A ball feeding and removing device is provided for feeding the ball to the position of the ball rotating device and removing the tested ball from the ball rotating device to a predetermined position. The ball feeding device comprises a holding device having an air cylinder (30) and a tip with a pair of holder claws (33) moved by the air cylinder to release the ball and a pair of side support claws (38) for locating the ball.

Description: This invention relates to an automatic ultrasonic testing apparatus for detecting flaws of balls, and more particularly to an automatic ultrasonic testing apparatus for balls which is capable of automatic and efficient detection of flaws in the balls. Tests on the surface and the inside part of balls for structural members have hitherto been made by an X-ray testing or fluorescent penetrate testing or by examining the appearance of the balls under a microscope or with the naked eye. In the X-ray or fluorescent penetrate testing or the inspection of the appearance under a microscope or with the naked eye, however, the object of testing, i.e., the ball for structural member is rotated manually and, therefore, much time is required for testing the entire peripheral surface of the ball. In addition, it is doubtful whether the entire peripheral surface of the ball can always be tested completely. In order to overcome the drawbacks of the conventional testing methods mentioned above, one of the present inventors have previously proposed with other inventors, in US-A-4 969 361 (identified with Japanese Patent Application Laid-Open (KOKAI) No. 1-219554(1989)), an ultrasonic testing method and apparatus by which the entire peripheral surface of the ball can be tested by placing the ball on drive rollers and rotating the ball. In the proposal of the ultrasonic testing method and apparatus disclosed in US-A-4 969 361, however, there is no concrete description of means for feeding the ball onto the drive rollers, only a description of holding the ball by suction of an air cylinder. It is an object of this invention to enhance the total testing efficiency of an ultrasonic testing apparatus particularly by improving the ball handling means. According to this invention, there is provided an apparatus for automatic ultrasonic testing for detecting flaws of balls which comprises a tank for containing a liquid medium for transmitting ultrasonic wave, a ball rotating means for rotating a ball to be tested, an ultrasonic flaw detection means for detecting flaws in the ball while horizontally swiveling a probe around the ball vertically rotated by the ball rotating means or rotating the ball spirally by the ball rotating means with or without swiveling the probe, and a ball feeding and removing means for feeding the ball to the position of the ball rotating means and removing the tested ball from the ball rotating means to a predetermined position, the ball feeding and removing means comprising a holding means having an air cylinder and a tip with a pair of holder claws and a pair of side support claws for holding the ball. The above and other optional features and advantages of this invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings which show by way of example some preferred embodiments of the invention. Figs.1 illustrate one embodiment of a ball feeding means used in an automatic ultrasonic testing apparatus according to this invention, in which Fig.1(a) is a front view and Fig.1(b) a side view; Figs.2 illustrate one embodiment of the relationship between a ball rotating means and a ball feeding and removing means, in which Fig.2(a) is an illustrative plan view and Fig.2(b) an illustrative side view; Fig.3 is a perspective view showing the total arrangement of one embodiment of an automatic ultrasonic testing apparatus for detecting flaws of balls in which the ball feeding and removing means is incorporated; and Fig.4 is a perspective view of a tip portion of an untested-ball supply chute. The automatic ultrasonic testing apparatus according to this invention comprises, basically, a ball rotating means, an ultrasonic testing means and a ball feeding and removing means, and especially a holding means having an air cylinder and a tip with a pair of holder claws and a pair of side support claws for supporting the ball is used as the ball feeding and removing means. After the ball is held by the pair of holder claws and the pair of side support claws of the holding means, the ball is conveyed to rotating rollers of the ball rotating means and is lowered to a position just above the rotating rollers which are immersed in a liquid medium of transmitting ultrasonic wave, for example, water, oil, etc. At this moment, each tip of the pair of the holder claws is located between two pairs of the rollers whereas each tip of the pair of the side support claws is located directly above the rollers. Next, only the holder claws are opened to the left and right, to place the ball on the rollers, and the ball holding portion is raised away from the ball. Then, flaw detection is carried out while the probe is swiveled around the ball by the ultrasonic flaw detection means or while the ball is rotated spirally and the probe is maintained stationary or swiveled if necessary. In conducting the flaw detection, an ultrasonic wave is sent from the probe toward the ball, an ultrasonic echo reflected back from the ball is received, and the waveform of the echo signal is observed on an ultrasonic flaw detector connected to the probe, thereby detecting flaws in the ball. After the flaw detection for the ball is finished, the ball holding portion is lowered, each tip of the holder claws located between two pairs of rollers is closed to hold the ball, and the ball holding portion is moved upward. In this case, the side support claws prevent the ball from dropping. The ball is conveyed to a predetermined place, then a new ball to be tested is gripped and fed onto the ball rotating means, to be subjected to flaw detection. According to the ball feeding and removing means of this invention, flaw detection for a predetermined number of balls to be tested is automatically, smooth and speedily carried out, because the balls can be placed or removed from the ball rotating rollers immersed in the liquid medium of transmitting ultrasonic wave without adjusting the level of the medium, if compared with the prior arts which needed to make the level of the medium lower. The ball as the material to be tested, namely, the object of the ultrasonic testing according to this invention is a ball used for a bearing member, a wear-resistant member or a sliding member. This type of balls, whether made of ceramic or metal, can be used as the object of the ultrasonic testing of this invention, without any particular restrictions. However, ceramic balls are particularly effective for use as the object of the ultrasonic testing according to this invention, because the reliability of the ceramic balls is heavily dependent on the accurate detection of minute flaws in the surface and the sub-surface of the balls. As the ceramic balls, those ceramic balls which comprise silicon nitride, silicon carbide, zirconia or alumina are preferably used, in view of the high strength and high hardness requirements of bearing members, wear-resistant members, sliding members, etc. This invention will now be described more in detail below while referring to the embodiments shown in the drawings; it is to be understood, however, that the invention is not limited to the embodiments. Figs.1 illustrate one embodiment of a ball feeding and removing mechanism used in an automatic ultrasonic testing apparatus according to this invention, in which Fig.1(a) is a front view and Fig.1(b) a side view. In Figs.1, denoted by 3⊘ is a single acting type air cylinder, which has a rear port 31 to be supplied with air from a compressor or the like (not shown) via an air hose 32 and to be a transmitter of an air pressure. To the tip of the air cylinder 3⊘ is fitted a pair of side support claws 38 and a pair of holder claws 33 is fitted to the side support claws 38 with shafts 34. The pair of holder claws 33 are opened and closed by a lever action with the shafts 34 as fulcra. The ball is held and released by the closing and opening of the holder claws. The pair of side support claws 38 is maintained stationary, functioning only to prevent the ball from falling off. With air supplied to the rear port 31 of the single acting type air cylinder 3⊘, an air cylinder rod 35 is lowered, and a push plate 36 for opening the holder claws which is attached to the rod 35 presses against a rear portion of each of the holder claws 33. The pair of holder claws 33 thus pressed is turned about the respective shafts 34, against the force of a coil spring 37 fitted between the holder claws 33 in order to close the claws, so that the tips of the claws 33 are opened outward. In this condition, the ball is placed at a lower portion of a space between the holder claws 33, and the air in the air cylinder 3⊘ is removed, whereupon the holder claws 33 are closed by the force of the coil spring 37 to hold the ball. In this case, when the side support claws 38 fitted to the tip of the air cylinder 3⊘ and disposed in a rectangular positional relationship with the holder claws 33 are set with a spacing therebetween being slightly greater than the diameter of the ball, the ball is prevented from slipping off the holder claws 33. After the ball is held by the holder claws 33 and the air cylinder 3⊘ is moved to a position just above the ball rotating device immersed in water as the liquid medium of transmitting ultrasonic wave contained in a tank 23, the air cylinder rod 35 is again lowered and the holder claws 33 are opened to place the ball on the ball rotating device. As shown in Figs.2(a) and 2(b), the holder claws 33 are each located between two shafts 41 and 42 and two pairs of rotating rollers 39 and 4⊘ fitted to the shafts 41 and 42 respectively whereas the tips of the side support claws 38 are located directly above the rollers 39 and 4⊘. Next, the holder claws 33 are opened in the same manner as above, thereby placing the ball on the ball rotating device comprising the rotating rollers 39 and 4⊘, and the air cylinder 3⊘ is raised. On the inside of the holder claws 33 and the side support claws 38, there is a sufficient space for the ball to move vertically. At the time of placing the ball on the rotating rollers 39 and 4⊘, therefore, no irrational forces are exerted on the rollers 39 and 4⊘, and it is unnecessary to enhance the accuracy of the position of the ball relative to to other members. Fig.3 is a perspective view showing the total arrangement of one embodiment of an automatic ultrasonic testing apparatus for detecting flaws of balls which incorporates the ball feeding and removing means. In Fig.3, denoted by 1 is a container for supplying untested balls. The untested balls 1⊘ placed in the container 1 are aligned along an untested-ball supply chute 2 sloped down toward the tip thereof. As shown in Fig. 4, stoppers a , b and c for stopping the ball are provided at a tip portion of the chute 2. The stoppers a is set stationary, for stopping the ball at a predetermined position. On the other hand, the stoppers b and c are movable, and function to feed out the balls to the predetermined position, one ball at a time. Denoted by 3 is a ball feeding device, which comprises a feed carriage 5 capable of moving along a feed rail 4. The carriage 5 is capable of being moved along the feed rail 4 to an arbitrary position by a feeding drive motor 6 and be stopped in the arbitrary position. The carriage 5 is equipped with an air cylinder 9 shown in Fig.1 (in Fig.1, denoted by 3⊘). At the start of the ultrasonic testing for detecting flaws of a ball, the feed carriage 5 is located in a position corresponding to the untested-ball supply chute 2, and the holder claws 8 (in Fig.1, denoted by 33) of the air cylinder 9 are in an opened condition. Next, the air cylinder 9 is lowered, and an untested ball 1⊘ disposed at the tip of the chute 2 is held by the holder claws 8. After the ball 1⊘ is thus held, the air cylinder 9 is moved upward, and the carriage 5 is moved to a position corresponding to rollers 11 (in Fig.2, denoted by 39 and 4⊘) for rotating the ball under test, and is stopped at that position. The air cylinder 9 is then lowered. When the untested ball 1⊘ is brought to the position for the ball 12 on the rotating rollers 11, the holder claws 8 are opened to place the untested ball 1⊘ on the rollers 11 immersed in water contained in the tank 23, and the air cylinder 9 is retracted. Next, a motor 13 for rotating the ball under test is operated to rotate the rollers 11, thereby vertically or spirally rotating the ball 12 under test. Simultaneously with the rotation of the ball 12, a probe swiveling motor 14 is rotated so that a probe 15 immersed in water is horizontally swiveled 18⊘° by a probe swiveling arm 24 when vertically or spirally rotating the ball 12, or the probe swiveling motor 14 is not operated so that the probe 15 is fixed without being swiveled when spirally rotating the ball 12. In Fig.3, numeral 25 denotes a shaft for transmitting a rotating force for the ball under test, and numeral 26 denotes a bevel gearing for transmitting the rotating force. The probe 15 is connected to an ultrasonic flaw detector 16, and the test for detecting internal flaws in the ball 12 is carried out over the entire periphery of the ball. When a flaw is present in the ball, a flaw waveform of echo signal is observed on an oscilloscope 17 of the ultrasonic flaw detector 16, and a flaw signal is sent to a mechanical drive portion control panel 18. Besides, a computer 27 is provided for controlling the ultrasonic flaw detector 16 and analyzing the flaw detection data. After the ultrasonic test on the entire periphery of the ball 12 is finished, the air cylinder 9 is lowered to hold the ball 12 in water by the holder claws 8. With the ball 12 thus held, the air cylinder 9 is retracted, and the feed carriage 5 is moved to and stopped in either a position corresponding to an accepted-ball discharge chute 19 or a position corresponding to a rejected-ball discharge chute 2⊘, according to the absence or presence of the flaw signal. On the upper side of either one of the discharge chutes, the air cylinder 9 is lowered, and the holder claws 8 are opened to drop the ball. The ball rolls down the discharge chute, to be contained into an accepted-ball receiver 21 or a rejected-ball receiver 22. After the ball is thus dropped, the air cylinder 9 is retracted, and the feed carriage 5 is moved to the initial position corresponding to the untested-ball supply chute 2 and stopped in that position. Thereafter, the above process is repeated, whereby the ultrasonic test for detecting flaws of the balls in the liquid medium of transmitting ultrasonic wave can be carried out automatically to separate accepted balls and rejected balls from each other. Solenoid valves for operating the air cylinder and for a suction cup, limit switches for positioning mechanical drive portions, such as the feeding device, and the like, which are not shown, are controlled appropriately by the mechanical drive portion control panel 18. As has been described above, the automatic ultrasonic testing apparatus for detecting flaws of balls according to this invention is capable of performing ah automatic and speedy detecting flaws test on the balls, completely over the entire periphery of each ball. Various modifications are possible within the scope of the invention. The ball feeding device may be used in ultrasonic testing apparatus in which either the ball or the ultrasonic probe are stationary, and apparatus in which the ball and probe are moved relatively in any suitable manner by appropriate means. The feeding/removing device may be used only for feeding the ball and not for removing it, or vice versa . The air cylinder may be replaced by any suitable means, e.g. hydraulic or mechanical, for moving the holder claws.

Claims: An immersion type automatic ultrasonic testing apparatus for detecting flaws of balls which comprises: a tank (23) for containing a liquid medium for transmitting ultrasonic waves. a ball rotating means (11) in said tank for rotating a ball (12) to be tested, an ultrasonic flaw detection means (16) for detecting flaws in the ball while swiveling a probe (15) around the ball rotated by the ball rotating means or rotating the ball spirally by the ball rotating means with or without swiveling the probe, and a feeding and removing means (3) for feeding the ball to the position of the ball rotating means and removing the tested ball from the ball rotating means to a predetermined position, the feeding and removing means comprising a holding means having an air cylinder (30) and a tip with a pair of holder claws (33) and a pair of side support claws (38) for holding the ball. An apparatus according to claim 1, wherein said ball rotating means comprise two pairs of rotating rollers (39,40), and each tip of the holder claws (33) is adjusted to be located between the two pairs of rotating rollers of the rotating means (11) which the ball (12) is placed onto or removed from. An apparatus according to claim 1 or 2, wherein the pair of side support claws (38) is fitted to the tip of the air cylinder (30) and the pair of holder claws (33) is combined with a coil spring (37) and each of the holder claws is fitted rectangularly to the pair of side support claws with a shaft (34). An apparatus according to claim 3, wherein the pair of holder claws (33) can turn around the shaft (34) and open by being pressed at the rear portion by the air cylinder pressure.

Inventors: FUSHIMI KOJI, NISHIOKA SHIGEO, FUSHIMI, KOJI, NISHIOKA, SHIGEO
Applicants: NGK INSULATORS LTD, NGK INSULATORS, LTD.
Application year: 1990
Main classification: G01N29
IPC codes: G01N29