PATENT DOCUMENT

Publication Number: US-10121581-B2
Application Number: US-201414500887-A
Country: US
Kind Code: B2

Title: Method for magnetizing multiple zones in a monolithic piece of magnetic material

Abstract:
An article having a multiple magnetic polarities and a method for making the article are disclosed. The article can be a monolithic substrate form from a metallic material or materials. The article may include a first magnetic polarity and a second magnetic polarity opposite the first magnetic polarity. Methods for making the article include provide either providing a monolithic substrate having a first magnetic polarity, or applying a first magnetic field to the monolithic substrate to impart a first magnetic polarity. The method may also include raising the temperature of the monolithic substrate in order to reduce the coercivity of the monolithic substrate. The temperature of the monolithic substrate may also be selectively raised to lower the coercivity of the monolithic substrate in associated areas. By lowering the coercivity, the second magnetic polarity may be imparted on the monolithic substrate.

Claims:
What is claimed is: 
     
       1. A method for forming a magnet having multiple magnetic zones in a single monolithic substrate, the method comprising:
 applying a first magnetic field to the single monolithic substrate to impart a first magnetic polarity to the single monolithic substrate; 
 aligning first regions of the single monolithic substrate with heating elements, the first regions separated by intervening second regions; 
 causing the heating elements to heat the first regions of the single monolithic substrate, wherein a coercivity of the first regions that are heated is reduced from a first coercivity to a second coercivity; and 
 applying a second magnetic field to the single monolithic substrate, thereby imparting a second magnetic polarity to the first regions, the second magnetic polarity opposite the first magnetic polarity, wherein the second regions retain the first magnetic polarity. 
 
     
     
       2. The method of  claim 1 , wherein subsequent to heating the first regions, the method further comprises:
 aligning the first regions with magnetic field concentration zones of a fixture, wherein applying the second magnetic field includes causing the magnetic field concentration zones to apply the second magnetic field locally to the first regions. 
 
     
     
       3. The method of  claim 2 , wherein the magnetic field concentration zones correspond to extending members of the fixture. 
     
     
       4. The method of  claim 1 , wherein the first magnetic field is stronger than the second magnetic field. 
     
     
       5. The method of  claim 1 , wherein the first magnetic field has a strength of at least 5 kilogauss. 
     
     
       6. The method of  claim 1 , further comprising aligning shunts with the second regions of the single monolithic substrate prior to applying the second magnetic field. 
     
     
       7. The method of  claim 6 , the shunts are composed of iron. 
     
     
       8. The method of  claim 1 , wherein the heating elements are lasers or inductive heating elements. 
     
     
       9. The method of  claim 1 , wherein the single monolithic substrate has a thickness of between about 0.4 and 2.2 millimeters. 
     
     
       10. A method for forming a magnet having multiple magnetic zones in a single monolithic substrate, the single monolithic substrate having a first magnetic polarity, the method comprising:
 heating the single monolithic substrate to change a coercivity of the single monolithic substrate from a first coercivity to a second coercivity less than the first coercivity; 
 aligning first regions of the single monolithic substrate with magnetic field concentration zones of a fixture, the first regions separated by intervening second regions of the single monolithic substrate; and 
 causing the magnetic field concentration zones to apply a magnetic field to the first regions, thereby imparting a second magnetic polarity to the first regions, the second magnetic polarity opposite the first magnetic polarity, wherein the second regions retain the first magnetic polarity. 
 
     
     
       11. The method of  claim 10 , wherein an entirety of the single monolithic substrate is heated. 
     
     
       12. The method of  claim 11 , wherein only the first regions of the single monolithic substrate are sufficiently heated to the second coercivity. 
     
     
       13. The method of  claim 12 , wherein the first regions are heated using multiple heating elements. 
     
     
       14. The method of  claim 10 , wherein the magnetic field concentration zones correspond to extending members of the fixture. 
     
     
       15. The method of  claim 14 , further comprising aligning shunts with the second regions of the single monolithic substrate prior to applying the magnetic field. 
     
     
       16. The method of  claim 10 , wherein the fixture is in contact with the single monolithic substrate when the magnetic field is applied. 
     
     
       17. The method of  claim 10 , wherein the fixture is a permanent magnet. 
     
     
       18. A magnet, comprising:
 a single monolithic substrate composed of ferromagnetic metal, the single monolithic substrate including:
 a first magnetic region characterized as having a first induced magnetic field polarity strength corresponding to a first coercivity at a first temperature; and 
 a transition zone located between the first magnetic region and a second magnetic region of the single monolithic substrate, wherein the second magnetic region is characterized as having a second induced magnetic field polarity that is opposite of the first induced magnetic field polarity, and the transition zone is characterized as being un-magnetized in accordance with a coercivity at a nominal temperature that is less than the first temperature. 
 
 
     
     
       19. The magnet of  claim 18 , wherein the first induced magnetic field polarity is caused by:
 applying a first magnetic field to the single monolithic substrate to impart the first induced magnetic field polarity to the first magnetic region while the first magnetic region is heated by heating elements. 
 
     
     
       20. The magnet of  claim 18 , wherein the second magnetic region is characterized as having a second induced magnetic field polarity corresponding to a second coercivity at a second temperature.

Description:
FIELD 
     The described embodiments relate generally to forming a magnet. In particular, the present embodiments relate to forming a multi-pole magnet from a monolithic substrate. 
     BACKGROUND 
     Some devices include a magnetic assembly having more than one magnetic polarity. This can be done in several ways. Several individual magnets with different polarities can be aligned together to form the magnetic assembly. Alternatively, an electromagnet may be used to apply a magnetic field to a substrate. 
     However, each method has drawbacks. For instance, aligning several magnets can be time consuming and expensive. Further, to cut the magnets made from relatively hard materials requires a high end blade (e.g., diamond blade) which erodes much of the substrate during the cutting process. Electromagnets may require a relatively high amount of voltage and current, particularly in materials having a high coercivity. This may also increase costs and create a potentially dangerous environment. 
     SUMMARY 
     In one aspect, a method for forming a magnet having magnetic field lines in multiple directions from a substrate is described. The method may include applying a first magnetic field to the substrate to impart a magnetic polarity in a first direction to the substrate. The method may include heating the substrate. In some embodiments, the substrate includes a first portion and a second portion. In these embodiments, the first portion and the second portion may include a first coercivity prior to heating the substrate. The method may further include applying a second magnetic field to the substrate to impart a magnetic polarity in a second direction to the substrate. In some embodiments, the second direction is opposite the first direction. 
     In another aspect, a method for forming a multi-polarity magnet from a substrate is described. The method may include applying a first magnetic field in a first direction to a first portion of the substrate. The method may further include applying a second magnetic field in a second direction to a second portion of the substrate. In some embodiments, the second direction is opposite the first direction. The method may further include means for changing the substrate from a first coercivity to a second coercivity different from the first coercivity. 
     In another aspect, a monolithic substrate is described. The monolithic substrate may include a first portion having a magnetic field in a first direction. The monolithic substrate may further include a second portion having a magnetic field in a second direction opposite the first direction. The monolithic substrate may further include a third portion having the magnetic field in the first direction. The monolithic substrate may further include a fourth portion having the magnetic field in the second direction. In some embodiments, the second portion is positioned between the first portion and the third portion. In some embodiments, the third portion is positioned between the second portion and the fourth portion. 
     Other systems, methods, features and advantages of the embodiments will be, or will become, apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description and this summary, be within the scope of the embodiments, and be protected by the following claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  illustrates a magnetic assembly having several magnets arranged in a row; 
         FIG. 2  illustrates a first electromagnet and a second electromagnet used simultaneously to form a substrate into a magnet; 
         FIG. 3  illustrates an isometric view of a substrate having multiple portions, with each portion having a dipole magnetic arrangement and associated magnetic field lines, in accordance with the described embodiments; 
         FIG. 4  illustrates a plan view of an embodiment of a substrate formed from a ferrous or ferromagnetic material, in accordance with the described embodiments; 
         FIG. 5  illustrates a plan view of a substrate shown in  FIG. 4 , positioned within a heating element; 
         FIG. 6  illustrates a plan view of a substrate shown in  FIG. 5 , with a fixture applying a magnetic field or magnetic flux lines in a direction opposite of those produced from a fixture shown in  FIG. 4 ; 
         FIG. 7  illustrates an embodiment of a monolithic substrate having several portions portions in which adjacent portions include magnetic field lines are aligned in opposite directions, in accordance with the described embodiments; 
         FIG. 8  illustrates a plan view of an embodiment of a substrate formed from a ferrous or ferromagnetic material, in accordance with the described embodiments; 
         FIG. 9  illustrates the embodiment of the substrate shown in  FIG. 8 , heated to a temperature such that the substrate includes a second, lower coercivity and positioned proximate to a fixture; 
         FIG. 10  illustrates a plan view of a substrate having several magnetic shunts proximate to the substrate, in accordance with the described embodiments; 
         FIG. 11  illustrates a plan view of a substrate having magnetic field lines aligned in a first direction proximate to a magnet assembly having magnetic field lines aligned in a second direction opposite the first direction; 
         FIG. 12  illustrates an X-Y graph showing coercivity vs. temperature for a neodymium (N45SH) magnet; 
         FIG. 13  illustrates a flowchart showing a method for forming a magnet having magnetic field lines in multiple directions from a substrate; and 
         FIG. 14  illustrates a flowchart showing a method for forming a multi-polarity magnet from a substrate. 
     
    
    
     Those skilled in the art will appreciate and understand that, according to common practice, various features of the drawings discussed below are not necessarily drawn to scale, and that dimensions of various features and elements of the drawings may be expanded or reduced to more clearly illustrate the embodiments of the present invention described herein. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     In the following detailed description, references are made to the accompanying drawings, which form a part of the description and in which are shown, by way of illustration, specific embodiments in accordance with the described embodiments. Although these embodiments are described in sufficient detail to enable one skilled in the art to practice the described embodiments, it is understood that these examples are not limiting such that other embodiments may be used, and changes may be made without departing from the spirit and scope of the described embodiments. 
     The following disclosure relates to a monolithic substrate having portion with magnetic field lines in different directions. The monolithic substrate may be a single piece of metal having magnetic field lines in a first direction and magnetic field lines in a second direction opposite the first direction. For example, the monolithic substrate includes an orientation of a north-seeking pole, or “north” pole, and a south-seeking pole, or “south” pole, to define a magnetic field in a first direction. The monolithic substrate also includes another orientation of a north pole and a south to define a magnetic field in a second (opposite) direction. To impart or impose the magnetic field in the second direction to the monolithic substrate, the coercivity of the monolithic substrate may be altered. The term “coercivity” as used throughout this detailed description and in the claims refers to a measure of the ability of a ferromagnetic material to withstand or resist becoming demagnetized by an external magnetic field. Coercivity may also be associated with the intensity of an external magnetic field required to reduce the magnetization of a material to zero. For instance, a material with a relatively low coercivity requires a relatively low external magnetic field to reduce the magnetic field to zero. Further, once the magnetic field of a monolithic substrate is reduced to zero, the external magnetic field may reverse the magnetic field of the monolithic substrate such that the monolithic substrate including a region initially having a magnetic field in a first direction to now including a magnetic field in a second direction. 
     Generally, the coercivity is inversely proportional with respect to temperature. In other words, the coercivity may be decreased by increasing the temperature of the monolithic substrate (e.g., heating). Alternatively, the coercivity may be increased by decreasing the temperature of the monolithic substrate. While the temperature of the entire monolithic substrate can be altered, in some cases, localized temperature changes can be performed. Altering means may include placing the monolithic substrate in an oven to heat the monolithic, or positioning a magnet having a temperature different from the monolithic substrate proximate to the monolithic substrate. For instance, the magnet may include a temperature lower than that of the monolithic substrate. 
     Lowering the coercivity of the monolithic substrate has several advantages. For example, an external magnetic field required to change the magnetic polarity of the substrate may be relatively low in instances where the coercivity is sufficiently decreased. This may save energy costs in cases where an electromagnet requiring electrical current is used to create the external magnetic field. 
     These and other embodiments are discussed below with reference to  FIGS. 3-14 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  illustrates an embodiment of magnetic assembly  100  having several magnets arranged in a row. Magnetic assembly  100  may include first magnet  102  and second magnet  104  adjacent to first magnet  102 . First magnet  102  may include a first polarity, that is, first magnet  104  is magnetized in a first direction. Second magnet  104  may include a second polarity opposite the first polarity, or magnetized in a second direction opposite the first direction. The direction of magnetization is denoted by the arrows. 
     Aligning magnetic assembly  100  in this manner can be time consuming and expensive. Also, in cases where magnetic assembly  100  includes magnets formed from relatively dense materials (e.g., neodymium, samarium cobalt), the magnets must be cut by a robust cutting tool, such as a diamond saw, to cut the individual magnets. Further, in cases where magnetic assembly  100  includes a dimension  106  on the order of a few millimeters, a relatively large portion of the material is lost due to the cutting action of the diamond saw. This results in wasted material. 
       FIG. 2  illustrates a plan view of first electromagnet  202  and second electromagnet  204  used simultaneously to form substrate  206  into a magnet. Both first electromagnet  202  and second electromagnet  204  may combine to form an electromagnetic field in opposite directions. In this manner, substrate  206  may be formed having magnetized regions with opposite magnetic polarities. However, substrate  206  formed in this manner also includes non-magnetized region  208  resulting from the prongs in close proximity to one another and having opposing electromagnetic fields. For instances, first electromagnetic  202  having first prong  212  and second prong  214  is paired with second electromagnet  204  having third prong  222  and fourth prong  224  to form first magnetic polarity  232  and second magnetic polarity  234 . As shown, first prong  212  and third prong  222  combine to impart first magnetic polarity  232  while second prong  214  and fourth prong  224  combine to impart second magnetic polarity  234  on substrate  206 . Non-magnetized region  208  is the result of the competing polarities offsetting each other due to the proximity of the prongs. Accordingly, substrate  206  includes a region in which substrate includes no magnetic polarity and accordingly cannot attract ferrous materials. This is undesirable, particularly when substrate  206  includes a dimension  216  on the order of a few millimeters or less, as non-magnetized region  208  may occupy a larger portion of substrate  206 . 
     Smaller electromagnets require an increasing amount of current, in some cases on the order of several thousand Amps, to attempt to reduce non-magnetized region  208 . Moreover, the thickness of the wire used to form the coils of the electromagnets may be too large to both support the increased current and fit around relatively small prongs. 
       FIG. 3  illustrates an isometric view of substrate  300  having multiple portions, with each portion having a dipole magnetic arrangement and associated magnetic field lines, in accordance with the described embodiments. For example, substrate  300  may include first portion  302  and second portion  304  adjacent to first portion  302 . As shown, first portion  302  and second portion  304  are designed to include magnetic fields extending in opposite directions. For example, first portion  302  may include a dipole magnetic arrangement having first pole  314  (e.g., north-seeking pole, or “north” pole) and second pole  316  opposite first pole (e.g., south-seeking pole, or “south” pole) resulting in magnetic field lines in a first direction  318 . Second portion  304  may also include a dipole magnetic arrangement having first pole  324  (similar to first pole  314 ) and second pole  326  (similar to second pole  316 ) opposite first pole  324 . However, second portion  304  includes first pole  324  and second pole  326  are arranged to form magnetic field lines in a second direction  328  opposite first direction  318 . This may be performed by switching the locations or regions of first pole  324  and second pole  326  of second portion  304 , as compared to first pole  314  and second pole  316 , respectively, of first portion  302 . 
     Substrate  300  may further include third portion  306  and fourth portion  308  having substantially similar dipole magnetic arrangements as those of first portion  302  and second portion  304 , respectively. Substrate  300  may include this arrangement along a lengthwise direction  330  of substrate  300  such that fifth portion  310  and sixth portion  312  are substantially similar to that of first portion  302  and second portion  304 , respectively. In other embodiments, substrate  300  includes several additional portions similar to those of first portion  302  and second portion  304 . Also, in some embodiments, substrate  300  is a monolithic substrate. Substrate  300  may generally be formed from any hard ferromagnetic material. Also, substrate  300  may include first dimension  332  and second dimension  334 , and accordingly, substrate  300  may be magnetized in multiple dimensions (e.g., two dimensions) described in the magnetization methods herein. Both first dimension  332  and second dimension  334  may be approximately in the range of 0.4 to 2.2 millimeters. 
       FIGS. 4-7  illustrate a process for transforming a substrate (e.g., substrate  300 ) into a magnet having several dipole magnetic arrangements, in accordance with the described embodiments.  FIG. 4  illustrates a plan view of substrate  400  formed from a magnetic material, in accordance with the described embodiments. As shown, substrate  400  is a monolithic substrate. Fixture  402  may be used to apply an external magnetic field or magnetic flux lines (shown as dotted lines) to substrate  400 . The magnetic field may include a strength of approximately 30 kG (kilogauss). In some embodiments, fixture  402  is made from iron, which may include a soft iron. When a magnetic field (not shown) is applied to fixture  402 , magnetic fields may be concentrated at extensions of fixture  402 , such as first extension  404 , second extension  406 , and third extension  408 . Fixture  402  is capable of producing magnetic flux lines at the extensions of fixture  402  in order to transform substrate  400  into a magnet having magnetic flux lines in a first direction, as shown in the arrows within substrate  400 . Although  FIG. 4  shows substrate  400  transforming into a magnet, in other embodiments, the process may alternatively include substrate  400  already transformed into a magnet with magnetic flux lines similar to those shown in  FIG. 4 . 
       FIG. 5  illustrates a plan view of substrate  400  shown in  FIG. 4 , positioned within heating element  410  emitting heat (denoted by the wavelike lines). Heating element  410  may generally be any type of heating instrument capable of producing localized heating to raise substrate  400  from a room temperature to at least 150 degrees Celsius. This may include a laser heating device or an inductive heating device. Heating element  410  may include multiple heating elements, such as first heating element  412 , second heating element  414 , and third heating element  416 , designed and positioned to provide localized heating to substrate  400 . In this manner, in these regions of localized heating, substrate  400  initially having a first coercivity may decrease to a second coercivity (denoted as relatively smaller arrows) less than the first coercivity. That is, in the regions of localized heating, the ability of substrate  400  to resist a change (e.g., decrease) in magnetization is reduced. 
     When substrate  400  includes a second (lesser) coercivity, a magnetic field having magnetic flux lines in the opposite direction as those of substrate  400  may be applied to substrate  400  to not only (momentarily) demagnetize substrate  400  but to also magnetize substrate  400  to include a magnetic field in a different direction. For example,  FIG. 6  illustrates a plan view of substrate  400  shown in  FIG. 5 , with fixture  422  applying a magnetic field (shown as dotted lines) to substrate  400  in a direction opposite of those produced from fixture  402  (shown in  FIG. 4 ). Fixture  422  may be made from any material or materials used to make a fixture previously described. When a magnetic field (not shown) is applied to fixture  422 , magnetic fields may be concentrated at extensions of fixture  422 , such as first extension  424 , second extension  426 , and third extension  428 . Also, fixture  422  is designed and positioned in a manner such that first extensions of fixture  422 , such as first extension  424 , second extension  426 , and third extension  428  are proximate to the regions of localized heating of substrate  400 . Further, fixture  422  is capable of producing magnetic flux lines at the extensions of fixture  422  in order to transform substrate  400  into a magnet having magnetic field lines in a second direction in the regions of localized heating. In this manner, substrate  400  may include multiple portions in which adjacent portions include magnetic field lines that are aligned in opposite directions, as shown in  FIG. 7 . 
     Referring again to  FIG. 6 , fixture  422  can be configured to produce magnetic flux lines strong enough to alter the magnetization (e.g., direction of magnetic field lines) in areas of substrate  400  having a second coercivity. Generally, the regions associated with the second coercivity are also associated with the regions of localized heating. Further, these magnetic flux lines produced by fixture  422  may be of a magnetic strength (e.g., 5 kilogauss) incapable of altering substrate  400  in regions of substrate  400  having a first coercivity greater than the second coercivity. These may also be referred to as the regions not heated by heating element  410  (in  FIG. 5 ). Accordingly, fixture  422  may be designed to affect portions having a particular coercivity (e.g., second coercivity) so as ensure substrate  400  includes adjacent portions having magnetic field lines in opposite directions. Also, non-magnetic regions, if any, between adjacent portions are generally negligible. 
       FIGS. 8-11  illustrate another process for transforming a substrate (e.g., substrate  300 ) into a magnet having several dipole magnetic arrangements, in accordance with the described embodiments.  FIG. 8  illustrates a plan view of an embodiment of substrate  500  formed from a ferrous or ferromagnetic material, in accordance with the described embodiments. As shown, substrate  500  is a monolithic substrate. In some embodiments, a magnetic field (not shown) may be applied to substrate  500  to transform substrate into a magnet with magnetic field lines, denoted as arrows, aligned in a first direction. Substrate  500  may be positioned within heating element  510  in order to raise the temperature of substrate  500 . In some embodiments, heating element  510  is an oven designed to raise the temperature of substrate  500  from a first temperature (e.g., ambient temperature) to at least 150 degrees Celsius. Unlike previous embodiments, in the embodiment shown in  FIG. 8 , substrate  500  is generally heated in its entirety to a temperature such that the coercivity of substrate  500  decreases from a first coercivity to a second coercivity. 
       FIG. 9  illustrates the embodiment of substrate  500  shown in  FIG. 8 , heated to a temperature such that substrate  500  includes a second, lower coercivity (denoted as relatively smaller arrows) and positioned proximate to fixture  520  designed to provide localized magnetic field lines. Fixture  520  may be made from any material previously described for a fixture. In  FIG. 9 , fixture  520  is configured to apply a magnetic field (shown as dotted lines) in a second direction opposite of the magnetic field of substrate  500 . When a magnetic field (not shown) is applied to fixture  520 , magnetic fields (shown as dotted lines) may be concentrated at extensions of fixture  520 , such as first extension  524 , second extension  526 , and third extension  528 . In this manner, fixture  520  may produce magnetic fields such that portions of substrate  500  within the magnetic field lines of fixture change from having magnetic field lines from a first direction to a second direction opposite the first direction, similar to that of substrate  400  (shown in  FIG. 7 ). 
     In order to ensure substrate  500  is formed with desired magnetic properties, that is, with adjacent portion having magnetic fields aligned in opposite directions, additional techniques may be used. For example,  FIG. 10  illustrates a plan view of substrate  500  having several magnetic shunts  530  proximate to substrate  500 , in accordance with the described embodiments. In some embodiments, magnetic shunts  530  may be engaged with substrate  500 . As shown in  FIG. 10 , magnetic shunts  530  may include first magnetic shunt  532 , second magnetic shunt  534 , third magnetic shunt  536 , and fourth magnetic shunt  538 . Magnetic shunts  530  may be made from metallic materials such as iron, including a soft iron. Generally, magnetic shunts  530  include properties such as a relatively high magnetic permeability. In this manner, magnetic shunts  530  may be arranged in locations along substrate  500  in order to maintain the direction of magnetic field lines of substrate  500  in those locations. For example, magnetic shunts  530  in  FIG. 10  are positioned in locations to maintain magnetic fields in a first direction, while fixture  520  is positioned proximate to locations of substrate  500  in order change the magnetic fields from a first direction to a second direction opposite the first direction. Any magnetic fields (shown as dotted lines) received in location of substrate  500  proximate to magnetic shunts  530  may be absorbed by the magnetic shunts  530  so as not to disturb the magnetic field direction in of substrate  500  in those locations. Magnetic shunts  530  used in this manner provide a means for maintaining desired magnetic field lines even when the coercivity of substrate  500  is reduced when heating substrate  500 . 
     When the coercivity is substantially reduced, a fixture previously described may not be required to change the direction of the magnetic field. For example,  FIG. 11  illustrates a plan view of substrate  600  having magnetic field lines (shown as arrows within substrate  600 ) aligned in a first direction proximate to magnet assembly  620  having magnetic field lines in a second direction (denoted as arrows with dotted lines) opposite the first direction. In some embodiments, magnet assembly  620  includes permanent magnets. In some embodiments, magnet assembly  620  includes neodymium magnets. As shown, magnet assembly  620  includes first magnet  622 , second magnet  624 , and third magnet  626 . Each of first magnet  622 , second magnet  624 , and third magnet  626  may include a magnetic field strength capable of altering substrate  600  to include magnetic field lines in a second direction, in locations proximate to first magnet  622 , second magnet  624 , and third magnet  626 . In addition, magnet assembly  620  may include a temperature substantially less than that of substrate  600  when substrate  600  is heated, as the magnetization of substrate  600  is changed (for example, from first direction to a second direction) before a change in temperature (e.g., cooling of substrate  600 ) begins to alter coercivity, even when substrate  600  is relatively thin (e.g., having dimensions of 2 millimeters or less). This may allow manufacturing/processing times of substrate  600  to decrease as substrate  600  may be handled in a relatively shorter time due to the increased cooling from magnet assembly  620 . 
     Also, although not shown, magnetic shunts may be positioned proximate to, or engaged with, substrate  600  in locations of substrate  600  that are not proximate to magnet assembly  620 . This ensures substrate  600  is transformed into a magnet with desired magnetic field lines (that is, similar to those shown in  FIGS. 3 and 7 ). Using permanent magnets may be an energy-saving alternative, particular when fixtures previously described require an electromagnet. 
     Although coercivity of a substrate previously described decreases with increasing temperature, the substrate may regain its initial, or first, coercivity when the temperature of the substrate decreases. This property allows the substrates previously described to maintain their desired magnetic properties. 
       FIG. 12  illustrates an X-Y graph  700  showing coercivity vs. temperature for a neodymium (N45SH) magnet. The substrates previously described may be made from neodymium magnet. Coercivity, shown on the y-axis, is in units of kilo-oersteds (KOe), and temperature, shown on the x-axis, is in units of degrees Celsius. The graph illustrates that neodymium magnet has a coercivity at temperature T 1 , approximately 20-25 degrees Celsius, that reduces by approximately 50% at temperature T 2 , approximately 100 degrees Celsius. These charts may be useful in determining where coercivity of a substrate is most sensitive to changes in temperature in order to influence the magnetic fields of the substrate along these temperatures of greatest sensitivity. 
       FIG. 13  illustrates a flowchart  800  showing a method for forming a magnet having magnetic field lines in multiple directions from a substrate. In step  802 , a first magnetic field is applied to the substrate to impart a magnetic field in a first direction to the substrate. The term “first direction” may be associated with an orientation of a dipole arrangement of a north pole and a south pole. Also, the first magnetic field may be applied by a fixture that receives an external magnetic field. The fixture is configured to have concentrated magnetic flux lines along extensions of the fixture. 
     In step  804 , the substrate is heated. Heating means may include localized heating (e.g., laser heating or inductive heating) to selectively heat the substrate. In other embodiments, heating means may include an oven used to heat the entire substrate. Also, the substrate may include a first portion and a second portion adjacent to the first portion. The first portion may be designed to include magnetic field lines orientated in a first direction, and the second portion may be designed to include magnetic field lines oriented in a second direction opposite the first direction. Also, the substrate may initially include a first coercivity before the substrate is heated. However, when the substrate is heated from an initial, or first, temperature to a second temperature greater than the first temperature, the heated portions of the substrate may decrease to a second coercivity less than the first coercivity. 
     In step  806 , a second magnetic field to the substrate to impart a magnetic field in a second direction to the substrate. In some embodiments, the second direction is a direction opposite the first direction. In other words, the north pole and the south pole are arranged in the second direction are opposite the locations relative to the first direction. 
     Also, a magnetic shunt may be used, particularly when the substrate includes magnetic field lines already oriented in a desired direction, that is, in a direction that is not intended to change (to the second direction). 
       FIG. 14  illustrates a flowchart  900  showing a method for forming a multi-polarity magnet from a substrate. In step  902 , a first magnetic field having a magnetic field in a first direction to a first portion of a substrate. In step  904 , applying a second magnetic field having a magnetic field in a second direction to a second portion of a substrate. The second direction is opposite the first direction. In step  906 , means for changing the substrate from a first coercivity to a second coercivity different from the first coercivity is performed. Means for change the coercivity include heating the substrate, either locally or the entire substrate, or positioning a magnet proximate to the substrate. The magnet can include a lower temperature than that of the substrate. The substrates described in this and in other embodiments may include dimensions as small as approximately 2 millimeters, and in some cases, as small as approximately 0.5 millimeters. 
     The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. Various aspects of the described embodiments can be implemented by software, hardware or a combination of hardware and software. The described embodiments can also be embodied as computer readable code on a computer readable medium for controlling manufacturing operations or as computer readable code on a computer readable medium for controlling a manufacturing line. The computer readable medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-access memory, CD-ROMs, HDDs, DVDs, magnetic tape, and optical data storage devices. The computer readable medium can also be distributed over network-coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20140929
Publication Date: 20181106
Grant Date: 20181106
Priority Date: 20140929
Inventors: ZHU, HAO
DIFONZO, JOHN C.
CORBIN, SEAN S.
Assignee: APPLE INC
CPC Classifications: [{"code": "H01F13/003", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01F13/003", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 55585204