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The motor iron core is the core component of the motor. The iron core is a non-professional term in the electrical industry, and the iron core is also the magnetic core. The iron core (magnetic core) plays a pivotal role in the entire motor. It is used to increase the magnetic flux of the inductor coil and has achieved the maximum conversion of electromagnetic power. The motor core is usually a combination of a stator and a rotor. The stator is usually a non-rotating part, and the rotor is usually embedded in the inner position of the stator.
The motor core has a wide range of applications, and is widely used in stepper motors, AC and DC motors, geared motors, outer rotor motors, shaded pole motors, synchronous asynchronous motors, etc. For the finished motor, the role of the motor core in the motor accessories is more critical. To improve the overall performance of a motor, it is necessary to improve the performance of the motor core. Usually, this kind of performance can be solved by improving the material of the iron core punching sheet, adjusting the magnetic permeability of the material, and controlling the size of the iron loss.
A good motor core needs to be stamped out by a precision metal stamping die, using an automatic riveting process, and then stamped out by a high-precision stamping machine. The advantage of this is that it can ensure the completeness of the product’s plane to the greatest extent and ensure the accuracy of its products to the greatest extent.
Modern stamping technology is a high and new technology that integrates multiple technologies such as equipment, molds, materials, and processes. High-speed stamping technology is an advanced forming technology developed in the past 20 years. The modern stamping technology of motor stator and rotor core parts is to use a high-precision, high-efficiency, long-life, multi-station progressive die that integrates various processes in a pair of molds for automatic stamping on a high-speed punching machine. The stamping process is After the strip comes out of the coil, it is leveled by a leveling machine, and then automatically fed by an automatic feeding device, and then the strip enters the mold, which can continuously complete blanking, forming, finishing, trimming, and iron core The punching process of automatic lamination, blanking with skew lamination, and blanking with rotary lamination, until the finished iron core parts are transported out of the mold, the entire punching process is automatically completed on a high-speed punching machine.
With the continuous development of motor manufacturing technology, modern stamping technology refers to the process method of manufacturing motor iron cores, which are now more and more accepted by motor manufacturers, and the processing methods for manufacturing motor iron cores are becoming more and more advanced. Compared with the original iron core parts made by ordinary molds and equipment, the punching of iron core parts with modern stamping technology has the characteristics of a high degree of automation, high dimensional accuracy, and long service life of molds. It is suitable for punching. Mass production of pieces. Since the multi-station progressive die is a punching process that integrates many processing techniques on a pair of molds, the manufacturing process of the motor is reduced, and the production efficiency of manufacturing the motor is improved.
Modern High-speed Stamping Equipment
Modern high-speed stamping precision molds are inseparable from the cooperation of high-speed punches. The current development trend of modern stamping technology is stand-alone automation, mechanization, automatic feeding, automatic unloading, automatically finished products, high-speed stamping technology, motor stator and rotor iron core progressive die The stamping speed is generally 200 to 400 times per minute, and most of the work is carried out within the range of medium-speed stamping. The precision progressive die with automatic lamination of the stator and rotor cores of the punching motor requires high-speed precision punching technology. The slider of the punching press requires a higher accuracy at the bottom dead center because it affects the automatic lamination formation of the stator and rotor punches in the die. The quality problem of the iron core process. Now precision stamping equipment is developing in the direction of high speed, high precision, and good stability. Especially in recent years, precision high-speed punching machines have developed rapidly, and they have played a significant role in improving the production efficiency of stamping parts. The high-speed precision punching machine is relatively advanced in terms of design structure and high manufacturing accuracy. It is suitable for high-speed stamping of multi-station cemented carbide progressive dies and can greatly improve the service life of the progressive dies.
The material punched by the progressive die is in the form of coils, so modern stamping equipment is equipped with levelers and other auxiliary devices. The automatic feeding devices include: roller, cam, mechanical step-less adjustment, gear, and numerical control Structural forms such as stage-adjustable feeders are used in conjunction with modern stamping equipment. Due to the high degree of automation and high speed of modern stamping equipment, in order to fully ensure the safety of the mold during the stamping process, modern stamping equipment is equipped with an electrical control system in the event of errors, such as the mold in the stamping process If a fault occurs in the middle, the error signal will be immediately transmitted to the electrical control system, and the electrical control system will send a signal to stop the punch immediately. At present, the modern stamping equipment used for punching motor stator and rotor core parts mainly includes Germany: SCHULER, Japan: AIDA high-speed punch, DOBBY high-speed punch, ISIS high-speed punch, the United States: MINSTER high-speed punch, China has: WORLD, HARSLE, Yingyu high-speed punch, etc. These high-precision high-speed punching presses have high feeding precision, punching precision and machine rigidity, and reliable machine safety systems. The punching speed is generally in the range of 200 to 600 times per minute, which is suitable for automatic stacking of stator and rotor cores of punching motors. Sheets and structural parts with skewing and rotating automatic riveting sheets.
Modern Die Technology of Motor Stator And Rotor Core
1. Overview of The Progressive Die For The Stator And Rotor Cores of The Motor
In the motor industry, the stator and rotor cores are one of the important parts of the motor, and their quality directly affects the technical performance of the motor. The traditional method of making iron core is to punch out stator and rotor punching pieces (scattered pieces) with ordinary molds, and then use rivet riveting, clasp, or argon arc welding to make the iron core. For the AC motor rotor, The iron core also needs to be twisted out of the skew by hand. The stepper motor requires the stator and rotor iron cores to have uniform magnetic properties and thickness directions. The stator iron core and rotor iron core punching pieces are required to rotate at a certain angle, such as using traditional methods. The production efficiency is low, and the precision is difficult to meet the technical requirements. Now with the rapid development of high-speed stamping technology, in the fields of motors and electrical appliances, high-speed stamping multi-station progressive dies have been widely used to manufacture automatic laminated structural iron cores. Among them, stator and rotor iron cores can also be twisted and stacked. There is a large-angle rotating riveting structure between the groove and the punching piece. Compared with ordinary punching dies, the multi-station progressive die has high punching precision, high production efficiency, long service life, and consistent dimensional accuracy of the punched iron core Good, easy to achieve automation, suitable for mass production, etc., are the development direction of precision molds in the motor industry.
Stator and rotor automatic riveting progressive molds have high manufacturing precision, advanced structure, high-tech rotation mechanism, counting separation mechanism and safety mechanism, etc., iron core automatic riveting, rotor with skew riveting, large-angle rotation The punching steps of stacking riveting are all done on the blanking station of the stator and rotor. The main parts of the progressive die, the punch, and the die are made of cemented carbide materials. Each cutting edge can be punched more than 1.5 million times, and the total life of the mold is more than 120 million times.
2. Automatic Riveting Technology For Motor Stator And Rotor Cores
The automatic stacking riveting technology on the progressive die is to put the original traditional process of making iron cores (punch out the loose pieces-all the pieces-riveting) in a pair of molds, that is, add on the basis of the progressive die The new stamping process technology, in addition to the punching and rotor shaft hole, slot hole and other punching shape requirements, adds the rivet points required for the stator and rotor core rivets and the counting hole that separates the rivet points. Stamping station, and change the original stator and rotor blanking stations into a blanking station first, and then make each punching piece form a stacking riveting process and a stacking riveting process (to ensure the thickness of the iron core) For example, if the stator and rotor cores need to be twisted and rotated, the lower die of the progressive die rotor or stator blanking station must be equipped with a torsion mechanism or a revolving mechanism, and the riveting point is continuously changed on the punching piece. Or rotate the position to achieve this function, so as to meet the technical requirements of automatically completing the riveting and rotary riveting of the punching sheet in a pair of molds.
The process of automatic lamination of the iron core is: punch out a certain geometrical riveting point on the appropriate part of the stator and rotor punching. The form of the riveting point is as shown in the figure. The upper part is a concave hole and the lower part is convex. , And then when the convex part of the upper punching piece of the same size is embedded into the concave hole of the next punching piece, an “interference” is naturally formed in the tightening ring of the blanking die in the mold, so as to achieve the purpose of tightening and connecting. as the picture shows. The process of forming the iron core in the die is to make the convex part of the upper riveting point coincide with the concave hole part of the lower riveting point in the blanking station of the punching sheet. When the upper part is dropped When the pressure of the punch of the material is applied, the lower one uses the reaction force generated by the friction between its outer shape and the wall of the concave mold to cause the two sheets to be riveted.
In this way, through the continuous punching of the high-speed automatic punching machine, a neat iron core that is arranged next to each other, the burrs are in the same direction and have a certain stack thickness can be obtained.
The method of controlling the thickness of the iron core lamination is to punch through the riveting point on the last punched piece when the iron core is a predetermined number of pieces so that the iron core is separated according to the predetermined number of pieces, and an automatic lamination is set on the mold structure Counting separation device, as shown in the figure.
There is a plate-drawing mechanism on the counting punch. The plate drawing is driven by a cylinder. The movement of the cylinder is controlled by a solenoid valve. The solenoid valve operates according to the instructions issued by the control box. Each stroke signal of the punch is input into the control box. When the set number of slices is reached, the control box will send out a signal. Through the solenoid valve and the air cylinder, the drawing board is activated, so that the counting punch achieves the purpose of counting separation. That is to achieve the purpose of punching the metering hole and not punching the metering hole on the riveting point of the punching sheet. The thickness of the lamination of the iron core can be set by yourself. In addition, the shaft hole of some rotor cores is required to be punched with two or three shoulder counterbores due to the needs of the supporting structure.
There are two types of iron core stacked riveting structure: the first is the close-stacked type, that is, the iron core of the stacked riveting group does not need to be pressurized outside the mold, and the bonding force of the iron core stacked riveting can be achieved after the mold is ejected. The second type is the semi-closed type. There is a gap between the riveted iron core punches when the mold is ejected, and it needs to be pressurized to ensure the bonding force.
3. The Setting And Quantity of Iron Core Stacking Riveting
The position of the core riveting point should be selected according to the geometry of the punching piece, while taking into account the electromagnetic performance and use requirements of the motor, the mold should consider whether the position of the punch and the concave die inserts of the riveting point has interference phenomenon and drop. The strength problem of the distance between the position of the mandrel hole of the material punch and the edge of the corresponding stacked riveting rod. The distribution of riveting points on the iron core should be symmetrical and uniform. The number and size of riveting points should be determined according to the required bonding force between the iron core punching pieces. At the same time, the manufacturing process of the mold must be considered. If there is a large-angle rotary riveting between the iron core punching pieces, the requirements for equal division of the riveting points should also be considered. As shown below.
The geometric shapes of the iron core rivet points are:
- Cylindrical stacked riveting points, suitable for close stacked structure of iron core;
- V-shaped stacked riveting point, the feature of the stacked riveting point is that the strength of the connection between the iron core punching pieces is large, and it is suitable for the close-stacked structure and semi-closed-stacked structure of the iron core;
- L-shaped stacked riveting point, the shape of the stacked riveting point is generally used for the twisted riveting of the rotor core of the AC motor, and is suitable for the close-stacked structure of the iron core;
- Trapezoidal stacked riveting point, the stacked riveting point is divided into round trapezoidal and long trapezoidal stacked riveting point structure, both of which are suitable for the close-stacked structure of the iron core.
4. The Interference of The Riveting Point
The binding force of the iron core riveting is related to the interference of the riveting point. The size difference between the outer diameter D and the inner warp d of the boss of the riveting point (ie the interference) is determined by the punch and the concave The gap of the die edge is determined, so selecting the appropriate gap is an important part of ensuring the strength of the core and the difficulty of the riveting.
The use of modern stamping technology to manufacture the stator and rotor cores of the motor can greatly improve the level of motor manufacturing technology, especially in automobile motors, precision stepping motors, small precision DC motors and AC motors, etc., which not only guarantees these The high-tech performance of the motor is also suitable for the needs of mass production. Now, manufacturers that design and manufacture progressive die for stator and rotor cores of motors have gradually developed, and their design and manufacturing technologies are constantly improving. With the internationalization of the manufacturing industry, improving the specialization of mold products is an inevitable trend in the development of the mold manufacturing industry. Especially in today’s rapid development of modern stamping technology, modern stamping technology for motor stator and rotor core parts will be widely used.