INTERLOCKING PACKAGES BY MEANS OF A QUICK- RELEASE ROTARY SPINDLE HEAD AND A THREADED SPINDLE

The present invention relates to a concept, a construction and an embodiment of a part of the technical process of producing a laminated rotor package of an electric drive in a progressive blanking tool, and specifically to a system with a quick-release rotary spindle head and a threaded spindle allowing the package to be additionally pressed in the arresting part of the tool. Said system allows for a faster substitution of the quick-release spindle head and for a more rigid operation of the system as such, thereby improving the flatness E and the compactness of laminated/interlocking packages. Herein, the term interlocking will refer to the conventional technical process of mechanically interconnecting laminations to form a laminated package, whereby individual laminas, the basic building components of a rotor or stator package, are joined by mechanical connections, known as interlocking tabs or clamps, disposed in convenient or allowable locations on the individual laminas.

The invention relates to a construction of a ^' system, which is part of a progressive blanking tool, the system comprising a quick-release rotary spindle head and a threaded spindle which, in combination with other structural solutions customary in the field of progressive blanking tools, allow for faster substitution of the spindle head assembly, as well as for a more rigid operation of the system, in order to produce flatter and more compact interlocking packages of complex shapes.

In recent times, manufacturing electric drives has become increasingly challenging due to strict international regulations having to do with efficiency and consequently with the energy class, with demands for reduced noise and reduced emissions of dangerous/harmful substances in the technological process.

Likewise, there has been an ever-growing demand for improved efficiency of electric motors, which consequently means stricter requirements in the fabrication of interlocking packages, encompassing rotor and stator packages alike. A rotor or stator package is composed of basic building elements called laminas. Laminas are the end product of progressive stamping, or blanking, wherein predetermined cutouts or shapes are fashioned in the lamina by following predetermined steps and using various cutting elements; packages being stacks of such laminations, integrated into a compact core, called a package. In order to make a rotor or stator package strong enough, laminations are joined together by using various techniques. The technique which is most widely used employs clamps or tabs, the shape whereof is tailored to the thickness of the sheet metal the laminations are made of. However, the flatness of a package cannot be guaranteed by the shape of the clamp alone. The flatness of the front side of a package mainly depends on the size of the cutting edge A on the outer diameter of the lamination, on the thickness of the sheet, on the geometry of the cutting edge, and on the ratio between the length of the cutting edge A along the outer diameter of the lamina and the thickness of the bridge B. In certain cases, because of the geometry of the lamina, it is not possible to design a favorable position for the interlocks which would ensure the flatness of the front side of the package, and the geometry of the lamina being is the main factor determining the flatness, and consequently the compactness, the idle running, and the squareness of the package, which all affect the operation of the electric motor. Hereinafter, the term "interlocking package" shall be intended as referring to rotor and stator laminated packages alike.

In the field of improvements to the rigidity and the ease of assembly of the system for improving the flatness of complexly shaped laminas, several similar solutions exist, all of which, however, struggle with finding a quality overall solution for the system, which strongly affects the assembly time and the quality of operation of the system for improving the flatness and the compactness of interlocking packages.

A system for improving flatness and compactness in interlocking packages of known design is the system with a hydraulic cylinder, disclosed in WO2011053258 (Al ) . In the particular case, the system has its own control unit which controls the stroke of the hydraulic cylinder by means of a hydraulic pump and control valves. The said hydraulic cylinder is fixed to the lower part of the base panel which is inserted into the table of the stamping machine and serves as support to the tool. Into this panel a bore is made, extending to the lower part of the tool. At the end of the piston rod, an axially pivotable head is mounted. The piston rod pushes the head to the arresting device in the tool. During blanking, the laminations, in other words, the unfinished interlocking packages, are held not only by the arresting device in the tool, but by the piston rod with the support head as well, which retreats by the thickness of a single lamination in the vertical direction towards the starting point synchronously with the abutment of the tool. When the package is released, exiting the arresting device, the piston rod quickly retracts to the level of the base panel, so that the blanked package may be removed from the tool. After the package is _. ejected, the piston rod with the head moves back up to the arresting device in the tool, supporting the new package being blanked. Overall, the system is effective' at preventing lamina deformation and improving compactness, but it exhibits some deficiencies in the accuracy of the overall response of the system, because air can not be completely removed from the hydraulic system, which renders the system not perfectly rigid, leading to uncontrollable errors in the movement of the piston rod. An additional problem is posed by the heating of the hydraulic fluid, reflected again in the operating precision of the system. The system as a whole is also unwieldy to assemble, and despite the fact that the axially pivotable head can be exchanged, mounting it into another tool takes a long time due to the bulk of the hydraulic cylinder and to the complexity of system design. It is a further deficiency of the said system and other systems of this type that they have many component parts, requiring a lot of maintenance and a long assembling time, besides rendering the systems less precise as the errors of individual components add up, which all results in higher production costs.

It is the object and purpose of the present invention to provide a system which will do away with all the foregoing technical inadequacies, that is, a system providing shorter assembling and disassembling times, having a minimal number of components, not having a dedicated control system and being controllable by the programming system of the blanking machine instead, and exhibiting a higher rigidity during operation, resulting in improved precision, and consequently easier control of the movements of the threaded spindle.

The proposed invention shall be described according to an embodiment of the system for improving flatness and compactness of interlocking packages having an integrated quick-release rotary spindle head and a threaded spindle and the appended drawings, in which:

Figure 1 - shows a stator lamination;

Figure 2 - shows a vertically positioned rotor package;

Figure 3 - shows the entire system of the invention in a cross-section of the support system; Figure 4 - shows a detailed cross-section of the quick- release rotary spindle head.

The inventive system for improving the flatness and the compactness of interlocking packages having an integrated quick-release rotary spindle head and a threaded spindle comprises a servomotor 8, coupled directly to the electronics or the programming system of the blanking machine and operating in synchronicity with the operation of the blanking machine, a reducing gear 6 transferring the revolutions to a threaded spindle 5 which is movable in a vertical direction, and a threaded spindle 5, on which a quick-release rotary head 16 of the spindle is mounted. The quick-release rotary head 16 of the spindle supports the interlocking package in the exit region of the tool. In the quick-release rotary head 16 of the spindle an additional disc spring 15 is inserted, which protects the threaded spindle 5 from getting damaged in the case of abutting on the interlocking package from below. In the case of a malfunction of the servomotor 8, or of the movement of the threaded spindle 5 being set incorrectly, resulting in the threaded spindle 5 standing still or moving in the opposite direction during blanking, an uncontrollable abutting of the head 9 against the interlocking package occurs, causing the head 9, the washer 10, and the head support 11 to be displaced vertically, leading to a deformation of the disc springs 15. At that moment a vertical displacement of the screw 17, by means of which the spacer 13 is secured to the head support 11, takes place, with said screw 17 actuating the sensor 14, fixed to the end of the threaded spindle 5, and causing said sensor 14 to signal the control system of the blanking machine to stop the blanking machine.

The sensor 1 is mounted in the lower region of the tool 2 and has the purpose of determining the upper limit position of the threaded spindle 5, and consequently of the quick- release rotary head 16 of the spindle. By means of the flange 7, the reducing gear 6 is fastened to the base panel 3, which is inserted into the table of the blanking machine and serves as support to the tool. The servomotor 8 is secured to the reducing gear 6 in the horizontal direction, and operatively coupled to the programming system of the blanking machine.

In this manner, a synchronous operation of the blanking tool and of the entire system for improving the flatness and the compactness of interlocking packages with an integrated quick-release rotary head and a threaded spindle is made possible, the pressure exerted on the interlocking package is stabler and more constant due to the rigidity provided by the threaded spindle. The extreme position of the quick-release rotary head 16 of the spindle and of the threaded spindle 5, or rather, its upper limit position, is protected by means of the sensor 1, so that damage to the threaded spindle 5 can not occur.

The operating principle of the system for improving the flatness and the compactness of interlocking packages having an integrated quick-release rotary spindle head and a threaded spindle in a progressive blanking tool is as follows :

During a move, the programming system of the blanking machine sends a signal to the servomotor 8, which rotates for a precisely determined step, depending upon the displacement of the blanking machine and upon the preset sheet thickness. By means of the flange 7, the motor 8 is fastened to the reducing gear 6, wherein the revolutions are transferred to the threaded spindle 5 by means of a worm-wheel and a worm having a gear ratio of 16:1. The quick-release rotary head 16 of the spindle is secured to the threaded spindle 5 by means of a collar 12. The disclosed system as a whole is fixed to the base panel 3 by means of a flange 4, and the base panel 3, serving as support to the tool, is inserted into the table of the blanking machine. To the base panel 3, serving as support to the tool, the lower portion of the tool 2 is then fixed, in which there is located a sensor 1 for determining the upper limit position of the threaded spindle 5 with the quick-release rotary head 16 of the spindle.

The quick-release rotary head 16 of the spindle, illustrated in Figure 4, is composed of: a head 9, enabling axial displacement in the case of the blanked interlocking package being rotated inside the tool, a washer 10, into which the head 9 is screwed by means of a screw, the head support 11 under which two disc springs 15 are disposed for cushioning the abutments of the interlocking package against the head 9 during blanking, a collar 12 for securing the head support 11 as well as securing the quick- release rotary head 16 of the spindle to the threaded spindle 5, and the spacer 13 for keeping a constant clearance between the collar 12 and the head support 11. The screw 17 secures the spacer 13 to the head support 11. The collar 12 doubles as a guide to the spacer 13, thereby enabling the screw 17, the head support 11, the washer 10, and the head 9 to be displaced vertically. In the case of a malfunction of the servomotor 8 during blanking, an uncontrollable vertical displacement of the head 9, the washer 10, and the head support 11 occurs, leading to a deformation of the disc springs 15. At the same time, there is a vertical displacement of the spacer 13, and consequently of the screw 17, which, in turn, actuates the sensor 14, which then signals the control system of the blanking machine to stop the same.

When the sensor 1 for determining the upper limit position of the threaded spindle 5 with the quick-release rotary head 16 of the spindle detects the upper limit position of the threaded spindle 5, it sends a signal to the control system of the blanking machine, and via the said system to the servomotor 8, which receives the command to move, which is to say, to start blanking a further interlocking package, as , a result of which the threaded spindle 5 is pivoted and the threaded spindle 5 with the quick-release rotary head 16 of the spindle is displaced vertically by the thickness of a single lamination.

Based on the number of revolutions of the servomotor 8, the program package of the blanking machine determines the lower limit position of the threaded spindle 5, in other words, the position in which the threaded spindle 5 with the quick-release rotary head 16 of the spindle reaches the base panel 3 which serves as support to the tool, and the interlocking package is removed from the tool. As soon as the interlocking package is removed from the tool, the threaded spindle 5 with the quick-release rotary head 16 receives the command to move up to the arresting device in the tool, or to a predetermined position, that is to the upper limit position of the threaded spindle 5 detected by the sensor 1, thus rendering support in the blanking of a further interlocking package. This cycle is repeated through the entire operation of the tool, that is, through the entire blanking process.