JPH0448517Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a dynamic balance testing machine, and in particular, the invention is designed to prevent the effects of electric charges accumulated on the workpiece from being discharged by rotating the workpiece. Regarding dynamic balance testing machines.

[Prior art] As a testing machine for measuring the unbalance of the armature of a small DC motor, the workpiece is supported by a bearing fixed to a table, the workpiece is driven by a belt, and the workpiece is rotated at a desired speed. There is a dynamic balance tester that detects the rotation speed using a proximity switch installed near the engine.

[Problems that the invention aims to solve] However, when testing the armature of a small, high-voltage DC motor using this type of testing machine, the core and shaft of the motor are insulated, so
When a belt is placed on the testing machine and rotated, the belt carries an electric charge as shown in FIG. 2, and a considerable amount of electric charge is accumulated in the core of the workpiece 2 in a short period of time.

Therefore, when detecting the rotation speed by detecting the pole of the core using the proximity switch 3, arc discharge frequently occurs between the core of the workpiece 2 and the proximity switch 3, as shown in Fig. 3. This adversely affects the electrical signal of the proximity switch, making rotational speed detection inaccurate.

Therefore, an object of the present invention is to provide a dynamic balance tester that prevents the proximity switch from being affected by noise and the like due to arc discharge, and that can accurately detect the rotational speed.

[Means for Solving the Problems] In order to solve the above problems, the present invention has the following configuration.

In other words, the workpiece is rotated by a belt drive,
In a dynamic balance testing machine that measures the unbalance of the workpiece by detecting the rotation speed with a proximity switch installed near the workpiece, a lightning rod is provided to discharge the charge accumulated in the workpiece, and the proximity switch is installed. , is characterized by being installed at a distance from the lightning rod that will not cause noise in the output signal when lightning strikes the rod.

[Function] Since the lightning rod is provided in a position where it is more likely to be struck by lightning than the proximity switch, when arc discharge occurs due to the charge accumulated in the core of the work, lightning strikes the lightning rod.

Since the lightning rod and the proximity switch are installed with a sufficient distance between them, when the lightning rod is struck by lightning, the proximity switch is not affected by noise etc. when the lightning rod is struck by lightning.

[Example] FIG. 1 is a diagram showing the configuration of an example of the present invention.
In the figure, a workpiece 6 has a belt 7 attached thereto, which is wound around a pulley 9 attached to the rotating shaft of a motor 10.
It is rotated by driving the motor 10. The workpiece 6 is rotated while being supported by the bearing 13, and the pick-up 11 provided on the bearing 13 detects the unbalance that appears when the shaft rotates. In addition, the rotation speed of the workpiece 6 is controlled by a proximity switch 14 provided near the workpiece.
It is measured by sensing the poles of the core. Signals from the pickup 11 and the proximity switch 14 are input to the measuring instrument main body 15, where they are subjected to arithmetic processing.

A lightning rod 16 is further provided near the work 6. The tip of the lightning rod 16 is placed at a position preceding the arc generating portion of the workpiece 6 and closer to the workpiece than the switch, and the proximity switch 14 is installed at a sufficient distance from each other. 14 and the measuring instrument body 15
The signal line connecting the two is kept away from the lightning rod 16.

Therefore, when arc discharge occurs due to the charge accumulated in the core of the workpiece 6 while the workpiece 6 is rotating, lightning will not strike the proximity switch but the lightning rod 16.

Further, when the lightning rod 16 is struck by lightning, the output signal of the proximity switch 14 is not affected by noise because the lightning rod 16 and the proximity switch 14 are installed sufficiently apart.

[Effects of the invention] As explained above, the dynamic balance tester according to the invention is configured to prevent the proximity switch from being struck by lightning and to prevent the output signal of the proximity switch from being affected by the noise caused by the lightning strike. Therefore, the rotational speed of the workpiece can be accurately measured, and unbalance can be measured reliably.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of an embodiment of the present invention;
FIG. 3 is an explanatory diagram of a conventional example. 6...Work, 14...Proximity switch, 16...
…lightning rod.

Claims (1)

[Scope of utility model registration request] In a dynamic balance testing machine that rotates a workpiece by driving a belt and measures the unbalance of the workpiece by detecting the number of rotations with a proximity switch installed near the workpiece, electric charges accumulated in the workpiece are discharged. A dynamic balance tester characterized in that a lightning rod is provided and the proximity switch is installed at a distance from the lightning rod that does not cause noise in its output signal when lightning strikes the lightning rod.