JPH07117446B2 - Method for measuring fixed strength of rotor conductor rod of cage rotor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to measurement of a fixing strength (that is, looseness) of a rotor conductor rod used in a squirrel-cage rotor of an induction motor or the like to a core. It is a thing.

[Prior Art] A conventional rotor conductor rod fixing method will be described with reference to FIGS. In the figure, 1 is a rotary shaft, 2 is a rotor core laminated on this shaft, 3 is a slot provided on the outer peripheral portion of the rotor core 2, and 4 is a rotor conductor rod inserted into the slot 3. 5 is a gap formed between the inner peripheral wall of the slot 3 and the rotor conductor rod 4, 6 is an end ring welded or brazed to the rotor conductor rod 4, and 7 is the rotor core 2
Rotor clampers 8 for tightening the both ends of the core 2 are ventilation ducts formed between the cores 2. Next, 9 is, for example, a "chisel" that strikes the end of the rotor conductor rod 4,
Reference numeral 10 is a groove of the rotor conductor rod 4 formed by the chisel, and 11 is a protrusion on the side surface of the rotor conductor rod 4 that is formed by the groove 10 to have an expanded and uneven thickness. In this way, the protrusion 11 is formed on the side surface of the rotor conductor rod 4 by plastic deformation to fill a part of the gap 5,
As a result, the rotor conductor rod 4 is fixed to the slot 3.

Next, the operation will be described.

After inserting the conductor rod 4 into the core 2, as shown in FIG. 6, a groove is formed in the conductor rod 4 by a driving tool 9 such as a "chisel".
10 is formed, and the conductor rod 4 is firmly fixed to the core 2. Forming the groove 10 is called a swage. The driving operation is performed before the end ring 6 is fixed, that is, after the conductor rod 4 is hit into the core 2. The groove 10 is the core 2
A predetermined depth D is formed over substantially the entire length of the conductor rod 4. However, if the depth is equal to or larger than a predetermined value, the conductor rod 4 will not be loosened.

Next, FIG. 7 shows a method of measuring the fixing strength between the rotor core and the rotor conductor rod. Conventionally, a point A was hit with a test hammer 12, and a fingertip was applied to the point C. The strength of fixation was judged by sensing the degree of vibration of the human tactile sensation.

[Problems to be Solved by the Invention]

As described above, the conventional measuring method has the drawbacks that the measurement is performed by the feel of the fingertip, and therefore there are individual differences due to the feel, variation occurs in the determination, and quantification cannot be performed.

The present invention has been made to solve the above problems, and it is an object of the present invention to eliminate the variations due to individual differences as described above and to quantify them.

[Means for Solving the Problems]

The measuring method according to the present invention is hit by a hammer or the like of the rotor conductor rod inserted and fixed in the slot of the core, and at the same time, vibration of each of the rotor conductor rod at one point and the core in the vicinity is sensed through a sensor. The fixed strength is quantified by taking out the vibration, analyzing the vibration, and comparing the values.

[Action]

In the measuring method of the present invention, since the fixed strength is quantified by vibration analysis, there is no variation due to individual differences as in the conventional method that relies on the human touch.

〔Example〕

A measurement method according to an embodiment of the present invention will be described below with reference to FIGS.
This will be described with reference to FIGS. In the figure, 13 is a mount for supporting the shaft 1 during the vibration test. The vibration test is performed in the state shown in FIG. That is, it is performed after the end ring 6 is fixed to the conductor rod 4, and the vibration direction is by hitting the conductor rod 4 with the hammer 12 from the outer diameter direction. 14 is a vibration analysis device, which is composed of the following 15 to 21. That is, 15 is an amplifier, 16 is an A / D converter, 17 is a calculator, 18 is a display device for displaying the calculation result, 19 is a control value setting device, 20 is an alarm device, and 21 is a calculator 17 at the time of calculation. It is a storage device that inputs and outputs data between them.

Next, the measuring method will be described. In FIG. 1, an accelerometer 22 is attached to the rotor core 2 and an accelerometer 23 is attached to the rotor conductor rod 4.
Is attached and the conductor rod 4 is vibrated with a hammer 12. Accelerations B and A obtained from the accelerometers 22 and 23 are measured by the amplifier 1
5, it is input to the calculator 17 through the A / D converter 16, and the calculation result is displayed on the display device 18. At this time, if the rotor core 2 and the rotor conductor rod 4 are sufficiently fixed to each other, they have almost the same vibration acceleration, and if the fixation is insufficient, the vibration acceleration B of the rotor core 2 is the rotor acceleration. It is smaller than the vibration acceleration A of the rod 4.

FIG. 3 is an example of an acceleration response waveform in the frequency domain displayed on the CRT 18, in which the difference between the vibration acceleration A and the vibration acceleration B is equal to or larger than the value set in the presetter 19 (that is, the swaging rate is a constant value). In the following case, the alarm device 20 immediately notifies the abnormality.

As a result of the experiment, the swaging rate (in FIG. 6, the groove
When the ratio of the cross-sectional area of 10 to the cross-sectional area of the conductor rod 4 is large, that is, when the conductor rod 4 is sufficiently fixed to the core 2, the vibration acceleration ratio A / B is small and is close to 1. When the swaging rate is small, that is, when the fixing of the conductor rod 4 is insufficient, A shows a larger value than B.

The difference in the swaging rate A / B is estimated to be due to the following reasons. When the processing rate is high, that is,
If the conductor rod 4 is in close contact with the core 2, the conductor rod 4
It is considered that the vibration is well transmitted to the core 2, and when the machining rate is small, the vibration is not sufficiently transmitted and is damped midway (a gap or the like).

The rotor conductor rod 4 may be hit with any one other than the hammer 12 as long as the same size is obtained. The accelerometer may have any shape and size as long as it does not affect the vibration of the rotor conductor and the rotor core. The vibration acceleration may be either time domain data or frequency domain data. The vibration test is not limited to the state in which the shaft 1 is supported by the pedestal 13 as shown in FIG. 1, but may be performed in a state in which the shaft 1 is hung by a wire or the like.

〔The invention's effect〕

As described above, according to the present invention, the fixed strength of the rotor conductor rod and the rotor core can be quantitatively obtained as a numerical value, and when the fixed strength falls below a certain value (control value), an alarm device is activated. Since it can be operated and reliably detected, accurate and efficient measurement is possible.

[Brief description of drawings]

FIG. 1 is a measurement procedure diagram showing an embodiment of the present invention.
The figure is a detailed view of the vibration analysis apparatus of FIG. 1, FIG. 3 is an example of data obtained by the vibration analysis apparatus, FIG. 4 is a front view of the rotor, and FIG. 5 is a line V-V of FIG. A sectional view before fixing the rotor conductor rod, FIG. 6 is a sectional view of the same conductor rod after being fixed by a wedge, and FIG. 7 is a method for measuring the fixing strength of the rotor conductor rod by a conventional method. In the figure, 1 is a shaft, 2 is a rotor core, 3 is a slot, 4 is a rotor conductor rod, 12 is a hammer, 14 is a vibration analysis device, and 22, 23.
Is an accelerometer. The same reference numerals in the drawings indicate the same or corresponding parts.

Continuation of the front page (56) Reference JP-A-60-58551 (JP, A) JP-A-60-29660 (JP, A) JP-A-57-91419 (JP, A) JP-A-59-63605 (JP , A)

Claims (1)

[Claims] Claim: What is claimed is: 1. A rotor conductor rod is inserted into a slot provided on the outer periphery of a rotor core and fixed to the inner wall of the slot. A cage characterized by sampling the vibrations of both an arbitrary part of the rotor and the rotor core part adjacent to this, analyzing each vibration, and comparing the values to quantify and measure the fixed strength. Method for measuring the fixed strength of the rotor conductor rod of a rectangular rotor.