Method for preventing medium and large alternating current motor rotor cage bars from being broken

Abstract

The invention discloses a method for preventing medium and large alternating current motor rotor cage bars from being broken. The method comprises the following steps of S1, manufacturing corresponding fixing parts according to the shapes of the cage bars; s2, the manufactured fixing piece is arranged between the iron core and the short circuit ring at the two ends of the motor rotor; wherein a flat copper conductor is used as the fixing piece, the fixing piece is welded on the cage bar between the iron core and the short circuit ring by using a welding technology, and the fixing piece is welded for a circle to form an auxiliary short circuit ring.

Description

Technical Field

[0001] The present invention relates to the technical field of motor manufacturing and repair, and particularly relates to a method for preventing the rotor cage bars of medium and large-sized AC motors from breaking. Background Art

[0002] In medium and large-sized AC motors, the cage rotor generates current through the induced magnetic field, converting electrical energy into mechanical energy. Different motor powers result in different motor torques. The greater the motor torque, the greater the force on a single cage bar, and the higher the probability of the cage bar breaking. Summary of the Invention

[0003] In view of the above technical problems, the present invention provides a method for preventing the rotor cage bars of medium and large-sized AC motors from breaking.

[0004] To achieve the above object, the technical solution of the present invention is as follows: A method for preventing the rotor cage bars of medium and large-sized AC motors from breaking, comprising the following steps: S1. Fabricate corresponding fixing parts according to the shape of the cage bars; S2. Place the fabricated fixing parts between the iron core and the short-circuit ring at both ends of the motor rotor; Among them, the fixing parts use flat copper conductors, and the fixing parts are welded to the cage bars between the iron core and the short-circuit ring by welding technology. The fixing parts are welded in a circle to form a secondary short-circuit ring.

[0005] The beneficial effects of the present invention are as follows: 1. The present invention installs the fixing parts between the rotor iron core and the end ring. Through the fixing parts, the force on a single cage bar can be distributed to both sides, and in addition, the current in the original cage bar and short-circuit ring circuit is shunted, reducing the accident of the motor rotor cage bar breaking and extending the service life of the motor.

[0006] 2. The present invention is an improved invention of traditional manufacturing and repair technologies. By adding cage bar fixing parts between the iron core and the short-circuit ring at both ends of the motor rotor, the failure of the cage bars breaking during the operation of the motor can be completely avoided. Brief Description of the Drawings

[0007] Figure 1 It is the schematic diagram of the present invention. Detailed Description of the Invention

[0008] To make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that these descriptions are exemplary and not intended to limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0009] As Figure 1 shown, a method for preventing the rotor cage bars of medium and large AC motors from breaking includes the following steps: S1. Fabricate corresponding fixing parts 3 according to the shape of the cage bars 2; S2. Place the fabricated fixing parts 3 between the iron core 1 and the short-circuit ring 4 at both ends of the motor rotor; Among them, the fixing parts 3 are made of flat copper conductors, and the fixing parts 3 are welded to the cage bars 2 between the iron core 1 and the short-circuit ring 4 by welding technology. The fixing parts 3 are welded in a circle to form a secondary short-circuit ring.

[0010] Explanation of the force on the cage bars: 1) Cutting the electromagnetic force of the rotating magnetic field. The cage bars 2 cut the magnetic lines of force in the rotating magnetic field formed by the stator to generate torque. During the rotation of the cage bars 2, the force on each position is inconsistent, and the force-bearing part between the single cage bar 2 and the welded short-circuit ring 4 is prone to breakage. 2) The cage bars 2 carry current during the process of cutting the magnetic lines of force. The current is the largest when the motor starts, and the heat is proportional to the square of the current. Therefore, the cage bars 2 are prone to breakage due to the influence of thermal expansion and contraction. 3) The welded joints of the cage bars 2 and the end rings are subjected to the long-term action of inertial force, centrifugal force, and shear stress, and are prone to breakage.

[0011] Explanation of the present invention: 1) The fixing parts 3 are placed between the iron core 1 and the short-circuit ring 4 at both ends of the motor rotor, which solves the problem of uneven force on the cage bars 2, makes the force on each cage bar 2 more uniform, and avoids the breakage caused by the single force on the motor rotor cage bars. 2) After the fixing parts 3 are welded to the circumference of the cage bars 2, a secondary short-circuit ring is formed. It is connected in parallel with the original end short-circuit ring, and the current of the original short-circuit ring and the cage bars is shunted in parallel. This avoids the breakage of the cage bars due to excessive current at the original connection of the motor rotor cage bars. 3) At the contact between the iron core 1 and the cage bars 2, epoxy resin glue can be poured into the loose slots for fixation, or the copper bars can be impacted with a flat chisel or a pointed chisel to expand the area, so as to squeeze the two sides of the iron slots to fix the cage bars, making the contact between the cage bars 2 and the iron core 1 closer, reducing the relative displacement of the cage bars 2 in the middle of the iron core 1, and reducing the force generated by this relative displacement of the cage bars 2.

[0012] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preventing the breakage of rotor bars of medium and large AC motors, characterized in that: The following steps are involved: S1. Making corresponding fixing parts (3) according to the shape of the cage bars (2); S2, placing the manufactured fixing member (3) between the iron core (1) and the short-circuit ring (4) at both ends of the motor rotor; The fixing member (3) uses a flat copper conductor and is welded to the cage bar (2) between the iron core (1) and the short-circuit ring (4) using welding technology. The fixing member (3) is welded around to form a secondary short-circuit ring.

Images