Abstract
A magnetic pin insertion system comprises a rotary drive of a workpiece (rotor or stator) that a set of axially oriented slots around a circumferential surface that are receptive of magnetic pins. A cartridge holds an axially oriented stack of magnetic pins in guide chutes for each axial section of the workpiece. A pre-loaded feed mechanism (a weight or push spring) pushes the pins into successive slots of the workpiece as the rotary drive rotates the workpiece. Each cartridge chute terminates in an adjustable tongue, with a specified gap from the workpiece, that provides a resistive surface for shearing each pin away from other pins in the stack as they are pushed into their successive slots.
Claims
1. A magnetic pin insertion system in the manufacture of motors, comprising: a rotary drive of a workpiece being assembled for subsequent use in a motor, the rotary drive rotating the workpiece about an axis thereof, the workpiece having a set of axially oriented slots around a circumferential surface of the workpiece that are receptive of magnetic pins; a cartridge with at least one chute, with each chute associated with a corresponding axial section of the workpiece and holding an axially oriented stack of magnetic pins in guide channels thereof, each chute of the cartridge also having a pre-loaded feed mechanism applied radially against the stack of magnetic pins to push the pins into successive slots of the workpiece as the rotary drive rotates the workpiece, each guide channel terminating in an adjustable tongue providing a resistive surface for shearing each pin away from other pins in the stack as the pin is pushed into its slot.
2. The magnetic pin insertion system as in claim 1, wherein the workpiece is a rotor.
3. The magnetic pin insertion system as in claim 2, wherein the workpiece is a hybrid rotor having two axially disposed sections with circumferentially offset slots, the cartridge having two chutes for simultaneously feeding both stacks of the pins into corresponding slots of the respective sections.
4. The magnetic pin insertion system as in claim 1, wherein the workpiece is a stator.
5. The magnetic pin insertion system as in claim 1, wherein the pre-loaded feed mechanism of each chute of the cartridge is a mass that pushes pins downward by gravity into slots of the workpiece situated below the cartridge.
6. The magnetic pin insertion system as in claim 1, wherein the pre-loaded feed mechanism of each chute of the cartridge is a push spring.
7. The magnetic pin insertion system as in claim 1, wherein a gap between an end of the adjustable tongue and a corresponding top of a slot of the workpiece is less than half of a thickness of each magnetic pin to discourage any axial turning or twisting of pins as they are fed into successive slots.
8. The magnetic pin insertion system as in claim 1, wherein the rotary drive accommodates multiple workpieces and there are, in one or more cartridges, as many chutes as the total number of corresponding axial sections of all workpieces on the rotary drive.
9. A method of assembly of a motor workpiece with magnetic pin inserts, comprising: placing at least one motor workpiece onto a rotary drive, the rotary drive rotating the workpiece about an axis thereof, the workpiece having a set of axially oriented slots around a circumferential surface that are receptive of magnetic pins; feeding magnetic pins from a cartridge with at least one chute, each chute of the cartridge associated with a corresponding axial section of the workpiece and holding an axially oriented stack of magnetic pins in guide channels of the chute, each chute of the cartridge also having a pre-loaded feed mechanism that pushes against the stack of magnetic pins and feeds the pins into successive slots of the workpiece as the rotary drive rotates the workpiece; and shearing, as each pin is inserted into its slot, that pin away from other pins in its stack against a resistive surface of an adjustable tongue that terminates each guide channel of a chute at a specified gap distance from the motor workpiece.
10. The method as in claim 9, wherein the workpiece is a rotor.
11. The method as in claim 10, wherein the workpiece is a hybrid rotor having two axially disposed sections with circumferentially offset slots, stacks of pins from two chutes of the cartridge being simultaneously fed into the corresponding slots of the respective sections.
12. The method as in claim 9, wherein the workpiece is a stator.
13. The method as in claim 9, wherein the pre-loaded feed mechanism of each chute of the cartridge is a mass that pushes pins downward by gravity into slots of the workpiece situated below the cartridge.
14. The method as in claim 9, wherein the pre-loaded feed mechanism of each chute of the cartridge is a push spring.
15. The method as in claim 9, wherein the specified gap distance between the adjustable tongue and a corresponding top of a slot of the workpiece is less than half of a thickness of each magnetic pin to discourage any axial turning or twisting of pins as they are fed into successive slots.
16. The method as in claim 9, wherein multiple workpieces are placed onto the rotary drive for simultaneous rotation, and there are, in one or more cartridges, as many chutes as the total number of corresponding axial sections of all workpieces on the rotary drive.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIGS. 1A and 1B are respective closeup elevational views of rotor and stator interfaces for both a standard prior art hybrid stepper motor (FIG. 1A) and an enhanced prior art Sigma Instruments motor (FIG. 1B) with magnet inserts in inter-tooth slots of the stator, illustrating focused or concentrated torque producing flux.
[0016] FIG. 2 is a schematic illustration of a rotor and stator interface representing those parameters that are relevant to calculating Carter's coefficient in the prior art.
[0017] FIG. 3 is a perspective view of a prior art rotor for a hybrid stepper motor with two offset sets of axially oriented teeth (Z is the rotation axis of the rotor), showing surface slots into which magnetic pins can be inserted between the rotor teeth.
[0018] FIG. 4 is a schematic perspective view of a standard process of axial insertion of magnet pins into slots between teeth of a rotor as in FIG. 3, using a prior art mechanism in which a push rod slides each pin along a cartridge guide and axially into an positionally indexed inter-tooth slot.
[0019] FIG. 5 is a schematic front perspective view of a magnetic pin insertion system in accord with the present invention, using elevational or radial insertion of magnet pins into inter-tooth slots of a workpiece here seen as a hybrid rotor). Note that both halves of the hybrid rotor workpiece are loaded simultaneously with magnetic pins fed from two adjacent cartridge chutes.
[0020] FIG. 6 is a close-up perspective view seen slightly from below of the magnetic pin insertion system of FIG. 5 that includes a rotor (or stator) workpiece motor drive and cartridge with one or more magnetic pin guide chutes for loading magnetic pins into inter-tooth workpiece slots. The adjustable tongue for shearing the fed magnetic pins from the pin stack is visible at the bottom of the cartridge chutes.
[0021] FIG. 7 is a close-up, mainly axial, perspective view of the workpiece receiving the pins from the bottom of a cartridge chute, as in FIG. 5.
[0022] FIGS. 8A through 8C are successive close-up axial side views showing magnetic pin insertion from a guide chute of a cartridge into one of the workpiece slots, and subsequent shearing from other magnetic pins remaining in the guide chute as the workpiece is continuously driven.
DETAILED DESCRIPTION
[0023] With reference to FIGS. 5-7, a magnetic pin insertion system for use in the manufacture of motors comprises a rotary drive 41 of a motor workpiece (rotor or stator) 33 and fixtures that place a cartridge 37 containing one or more chutes, e.g. 37A and 37B, with stacks of magnetic pins 39 directly over the rotor and/or stator tooth valleys (inter-tooth slots) 35.
[0024] In FIGS. 5-7, the workpiece 33 is represented by a hybrid rotor for a stepper motor. The rotor 33 has two sections 33A and 33B with offset sets of axially oriented teeth 34 and corresponding offset sets of inter-tooth slots or valleys 35. A cartridge 37 has one chute per workpiece section, and therefore in this case two chutes 37A and 37B, each of which can hold stacks of magnetic pins 39 to be successively loaded into the slots 35 as the pins 39 are fed from the cartridge 37. This invention replaces the customary axial insertion of magnetic pins into an elevational or radial insertion of magnetic pins 39 into the various slots 35 of the workpiece. Additionally, the invention replaces the requirement for precision indexing of workpiece rotational position with a continuous rotation of the workpiece 33 as magnetic pins 39 are fed from above as the successive slots 35 rotate into position.
[0025] As seen in FIG. 5, directly over the magnet cartridge 37 is either a pin feed mechanism in the form of a controlled mass (here, linear slide plate weights 36) that is used to ensure the magnet pins 39 inside the cartridge 37 are fed successively into the respective tooth valleys 35. Alternatively, a preloaded push spring could be used. Through precision fixturing and the controlled mass or load spring, the drive motor 41 can activate the axial turning of the rotor or stator workpiece 33 while each magnet pin 39 is automatically placed directly into the target tooth valley 35 and then separated from the other magnet pins 39 by shearing action against the adjustable tongues 38 on the cartridge guide rails or chutes 37A and 37B as the workpiece 33 continuously turns. With multiple magnet pin chutes 37A and 37B in the cartridge, both halves of the hybrid rotor, and even multiple rotors, or stators, can be situated under the cartridge 37 and loaded simultaneously with their respective pins 39.
[0026] Situated above the workpiece 33 is a magnetic pin cartridge 37 in the form of a precision machined hopper which guides and resists magnetic pins 39. The magnetic pins 39 are dropped down at least one guide chute (or more usually, simultaneously down multiple guide chutes 37A, 37B, . . . ) in the cartridge 37 via either gravity (preferably assisted by a weight placed above the stack of pins) or via spring load. The pins 39 in the stack slide between rails down their respective guide chutes into inter-tooth surface slots around the circumference of the workpiece 33. More specifically, an upright mounting plate 31 attached at the top of the cartridge 37 supports linear slide plate weights 36 in linear open slot races 32 with guide posts 31A and 31B for those races that allow the weights 36 to slide vertically in the chutes 37A and 37B. The bottom end 36 of each slide plate weight 36 thereby pushes downward against a corresponding stack 39 of magnetic pins.
[0027] As seen more clearly in FIG. 6, a single rotary drive 41 with a workpiece mounting block 42 transfers rotational motion about a central axis to the motor workpiece 33 being assembled. The workpiece 33 is fixed to the rotary mount 42 so that it will axially align with the cartridge 37 and its several chutes 37A and 37B above. If desired, spacers with posts fitting into corresponding holes 44 in the ends of each workpiece 33 can allow multiple workpieces to be mounted to the rotary drive 41, so that more than one workpiece might be simultaneously loaded. In that case, the cartridge 37 would have as many chutes 37A, 37B, . . . as there are corresponding workpiece sections to be loaded with magnetic pins 39.
[0028] Although the motor workpiece in FIGS. 5-7 is, by way of example, a rotor 33, the workpiece might also be a stator receiving magnetic pins associated with stator pole teeth. This is easiest to accomplish in an interior stator and exterior rotor type motor, wherein the circumferential surface receiving the magnetic pins is an exterior surface of the stator, just as with the rotor. However, in the case of an interior rotor and exterior stator type motor, wherein it is the interior surface of the stator that needs to receive the magnetic pins, the workpiece can be attached at one end to the rotary drive in such a way that will leave enough space within the stator workpiece interior to accommodate the presence of the magnetic pin feed cartridge. A preloaded push spring feed mechanism for the stack of pins will ensure that the cartridge is not too tall to fit within the workpiece interior space. Thus, both types of stators can be loaded with magnetic pins using this type of radially pin loading setup.
[0029] With reference to FIGS. 8A-8C, as rotary motion is applied to the rotor or stator workpiece 33 by the drive, represented by arrow 6 showing the movement of the teeth 34A, 34B, 34C, . . . and slots 35A, 35B, 35C, . . . past the chute 37A, the successive magnetic pins 39A, 39B, 39C, . . . from a stack within the cartridge chute 37A (and likewise from chute 37B, not seen) are sequentially fed into each successive slot 35A, 35B, 35C, . . . between the rotor or stator workpiece teeth 34A, 34B, 34C, . . . , which then shear away at the end of their chutes from the other pins still in the stack. The aforementioned weight or load spring helps to push the pins downward with a radial force R between rails along their guide chutes 37A, etc. to ensure the feeding of pins into their respective slots.
[0030] There is typically a 50 m (0.002) gap 40 (seen in FIG. 8B) between the end of the cartridge chute 37A etc. and the tops of the teeth 34A, 34B, 34C, . . . on the workpiece 33. The smallness of this gap 40, which is generally less than half of the thickness of each magnetic pin 39A, 39B, 39C, . . . , discourages any axial turning or twisting of pins as they are fed into their successive slots. To enforce the size of the gap, the several chutes 37A and 37B of the cartridge 37 preferably terminate in a mechanically adjustable tongue 38 that provides a resistive surface for shearing each pin away from other pins in the stack as that pin is pushed into its workpiece slot. Such tongues 38 (one for each chute) are adjusted, e.g. with knobs, so that their ends closest to the workpiece 33 have the desired gap 40 from the end of the cartridge chutes to the tops of the workpiece teeth.
[0031] After all pins have been successfully placed within their respective inter-tooth valleys, an adhesive is typically externally applied onto the workpiece using another rotary machine, as in prior methods.
