Magnetic fastening assembly

A fastening assembly is provided that includes a first permanent magnet having a first operating temperature and a second permanent magnet having a second operating temperature lower than the first operating temperature. The first permanent magnet is attachable to the second permanent magnet in a locked state at a first temperature lower than the second operating temperature. The first permanent magnet is releasable from the second permanent magnet in an unlocked state at a second temperature that is higher than the second operating temperature.

BACKGROUND

The present disclosure relates generally to fasteners and fastening devices/assemblies.

Generally, a fastening mechanism such as a screw or snap feature may be used to attach two components of a device. However, the clean aesthetic requirements of a finished product in certain applications may make the use of unsightly screws and other snap features undesirable. Such aesthetic requirements may exist, for example, for display monitors and/or mobile devices with displays. Current solutions in such devices include, for instance, using adhesive to bond the display to a housing or chassis in a mobile phone or a laptop computer.

More specifically, in some applications, Pressure Sensitive Adhesive (PSA) may be used to address such clean aesthetic requirements. PSA can achieve a clean and high-strength fastening mechanism. However, the ease of removal of a component that is attached by PSA is inversely proportional to the strength of the attachment, while using a higher strength PSA makes the removal process much more difficult in cases where there is a need for subsequent removal of a PSA-attached component.

Accordingly, more practical fasteners and fastening mechanisms are needed.

SUMMARY

In an aspect, a fastening assembly includes a first permanent magnet having a first operating temperature and a second permanent magnet having a second operating temperature lower than the first operating temperature. The first permanent magnet is attachable to the second permanent magnet in a locked state at a first temperature lower than the second operating temperature. The first permanent magnet is releasable from the second permanent magnet in an unlocked state at a second temperature that is higher than the second operating temperature.

In a further aspect, a method is provided for using a fastening assembly including a first permanent magnet and a second permanent magnet. The method may include attaching a first surface of the first permanent magnet to a first component of a device, where the first permanent magnet has a first operating temperature. The method may further include attaching a second surface of the second permanent magnet to a second component of the device, where the second permanent magnet has a second operating temperature lower than the first operating temperature. The method may further include attaching the first component of the device to the second component of the device by aligning a third surface of the first permanent magnet opposite the first surface with a fourth surface of the second permanent magnet opposite the second surface so as to lock the first permanent magnet with the second permanent magnet at a first temperature lower than the second operating temperature.

In another aspect, a fastening assembly kit includes a first permanent magnet having a first operating temperature and a second permanent magnet having a second operating temperature lower than the first operating temperature. The first permanent magnet is attachable to the second permanent magnet in a locked state at a first temperature lower than the second operating temperature. The first permanent magnet is releasable from the second permanent magnet in an unlocked state at a second temperature that is higher than the second operating temperature.

DETAILED DESCRIPTION

Aspects of the present disclosure provide a magnetic fastening assembly including two permanent magnets with different operating temperatures such that the fastening assembly can be locked/fastened at temperatures below the operating temperatures of both permanent magnets and can be unlocked/released at temperatures larger than at least one of the two operating temperatures of the two permanent magnets. The present aspects take advantage of the permanent degradation of the magnetic strength of permanent magnets over certain temperature thresholds to provide a temporary fastening mechanism that can be unlocked/released by applying heat to a permanent magnet. Thus, the magnetic fastening assembly may provide a practical and efficient mechanism for reliably connecting components in devices while at the same time enabling simple disassembly and rework.

Turning now to the figures, example aspects are depicted with reference to one or more components described herein, where components in dashed lines may be optional. In the following,FIGS. 1-4, which may include similar or related components, are described with reference to each other.

Referring toFIGS. 1-4, an example of a device100implements a fastening assembly116that includes a first permanent magnet102having a first operating temperature and a second permanent magnet104having a second operating temperature lower than the first operating temperature, such that the first permanent magnet102is attachable to the second permanent magnet104in a locked state at a first temperature lower than the second operating temperature, as shown inFIG. 1. Also, as shown inFIG. 2, the first permanent magnet102is releasable from the second permanent magnet104in an unlocked state at a second temperature higher than the second operating temperature of the second permanent magnet104. Accordingly, the first permanent magnet102may be releasably attachable to the second permanent magnet104in the locked state. As such, heating up the fastening assembly116to the second temperature higher than the second operating temperature of the second permanent magnet104enables quick, efficient, clean, and low cost disassembly of the device100.

In an aspect, the first permanent magnet102may be sized and/or otherwise configured to engage the second permanent magnet104in the locked state as shown inFIG. 1. For example, in an aspect, the first permanent magnet102has a first magnetic pole114that may be alignable with a corresponding attractable second magnetic pole115of the second permanent magnet104in the locked state such that at least the magnetic attraction force between the first magnetic pole114of the first permanent magnet102and the second magnetic pole115of the second permanent magnet104keeps the fastening assembly116in the locked state as shown inFIG. 1. For example, the first magnetic pole114may be one of a north pole or a south pole, and the second magnetic pole115may be opposite that of the first magnetic pole114(e.g., south if the first magnetic pole114is north). However, in various other alternative aspects, the first permanent magnet102and the second permanent magnet104may have multiple attractable pairs of magnetic poles and/or differently located/sized attractable pairs of magnetic poles than the first magnetic pole114and the second magnetic pole115, such that the collective magnetic attraction force between such multiple attractable pairs of magnetic poles and/or differently located/sized attractable pairs of magnetic poles keeps the fastening assembly116in the locked state as shown inFIG. 1.

In an aspect, for example, the unlocked state of the fastening assembly116may be defined by a substantial reduction in the magnetic attraction force between the first permanent magnet102and the second permanent magnet104at the second temperature at least due to a de-magnetization of the second permanent magnet104since the second temperature is higher than the second operating temperature of the second permanent magnet104. For example, the substantial reduction in the magnetic attraction may be a threshold percentage or threshold amount, such as greater than 50% or equal to or greater than an amount of attraction force required to maintain the device100in the locked state during typical usage. In an aspect, the de-magnetization of the second permanent magnet104causes at least a partial loss of a magnetic field or magnetic flux in the second permanent magnet104. In an aspect, the first permanent magnet102may be forcibly releasable from the second permanent magnet104in the unlocked state by applying a force greater than any remaining and substantially reduced magnetic attraction force between the first permanent magnet102and the second permanent magnet104at the second temperature.

Optionally, in an aspect, the substantial reduction in the magnetic attraction force between the first permanent magnet102and the second permanent magnet104at the second temperature may further be due to a de-magnetization of the first permanent magnet102if the second temperature is higher than both the first operating temperature of the first permanent magnet102and the second operating temperature of the second permanent magnet104and if the first permanent magnet102is also heated up to the second temperature due to its proximity to the second permanent magnet104that is heated up to the second temperature. In this aspect, the de-magnetization of the first permanent magnet102also causes at least a partial loss of the magnetic field or the magnetic flux of the first permanent magnet102.

In an aspect, for example, the fastening assembly116transitions from the locked state (e.g., seeFIG. 1) to the unlocked state (e.g., seeFIG. 2) when at least the second permanent magnet104in the fastening assembly116is heated up from the first temperature to the second temperature causing de-magnetization of the second permanent magnet104. In this aspect, if the second temperature is lower than the first operating temperature of the first permanent magnet102, the first permanent magnet102maintains magnetism at the second temperature that causes the second permanent magnet104to become de-magnetized. In an aspect, after the second permanent magnet104is de-magnetized at the second temperature causing or enabling transition to the unlocked/released state of the fastening assembly116, the second permanent magnet104may be cooled down to below the second operating temperature and then re-magnetized, such that the fastening assembly116may be used in the fastened/locked state again. Accordingly, the fastening assembly116may be re-usable in some aspects. That is, subsequent to being detached from the second permanent magnet104in the unlocked state, the first permanent magnet102may be re-attachable to the second permanent magnet104(at a temperature below the second operating temperature of the second permanent magnet104) by re-magnetization of the second permanent magnet104.

In an aspect, the fastening assembly116may be used to attach/fasten a first component106of a device100to a second component108of the device100.

Optionally, in an aspect and specifically referring toFIGS. 3 and 4, the first permanent magnet102has a magnet body sized and/or otherwise configured to fit within a first opening302within the first component106, such as a pocket or a cubic/box-shaped space. For instance, the first opening302may be defined by a first set of walls306formed, pressed, molded, an/or otherwise configured in the first component106of the device100. Optionally, in an aspect, the second permanent magnet104has a magnet body sized and/or otherwise configured to fit within a second opening304within the second component108, such as a pocket or a cubic/box-shaped space. For instance, the second opening304may be defined by a second set of walls308formed, pressed, molded, an/or otherwise configured in the second component108of the device100. Further, the first opening302may be further defined by a top wall310that connects to the first set of walls306to define an open-ended space. Similarly, the second opening304may be further defined by a bottom wall312that connects to the second set of walls308to define an open-ended space.

Further, a first surface402of the first permanent magnet102may be attachable to the first component106of the device100, and a second surface408of the second permanent magnet104may be attachable to the second component108of the device100. In this aspect, a third surface404of the first permanent magnet102, opposite the first surface402, may be attachable to a fourth surface406of the second permanent magnet104, opposite the second surface408, in the locked state so as to attach the first component106of the device100to the second component108of the device100. For instance, in one example, the first surface402of the first permanent magnet102may be attachable to the first component106, and/or the second surface408of the second permanent magnet104is attachable to the second component108, such as by sizing and/or shaping the adjoining components so as to form a force fit attachment. For instance, in another example, the first surface402of the first permanent magnet102may be attachable to the first component106, and/or the second surface408of the second permanent magnet104may be attachable to the second component108, such as by connecting the components using a fastening mechanism, such as a screw, a bolt, a tang or tab, or any other type of mechanical retaining mechanism.

In an aspect, the first surface402of the first permanent magnet102extends in a first plane that is perpendicular to a second plane where the first set of walls306extend. In an aspect, the second surface408of the second permanent magnet104extends in a third plane that is perpendicular to a fourth plane where the second set of walls308extend. In an aspect, in the locked state of the fastening assembly116, a fifth plane where the third surface404of the first permanent magnet102extends is parallel to a sixth plane where the fourth surface406of the second permanent magnet104extends.

Optionally, in an aspect and additionally referring toFIGS. 1 and 2, for example, the first surface402of the first permanent magnet102may be attachable to the first component106of the device100by a first adhesive layer110. In an aspect, the first adhesive layer110may be curable at a temperature lower than the first operating temperature of the first permanent magnet102such that curing the first adhesive layer110does not de-magnetize the first permanent magnet102. Optionally, in an aspect, for example, the second surface408of the second permanent magnet104may be attachable to the second component108of the device100by a second adhesive layer112. In an aspect, the second adhesive layer112may be curable at a temperature lower than the second operating temperature of the second permanent magnet104such that curing the second adhesive layer112does not de-magnetize the second permanent magnet104. In an aspect, each one of the first adhesive layer110or the second adhesive layer112may include, but is not limited to, a Pressure Sensitive Adhesive (PSA), a cyanoacrylate, epoxy, polyurethane, a resin, or any other type of adhesive. In some aspects, each one of the first adhesive layer110or the second adhesive layer112may include cyanoacrylates or epoxies that can withstand the temperatures required for de-magnetizing the second permanent magnet104. In some alternative or additional aspects, however, screws or other mechanical fasteners may be used to hold the first permanent magnet102and/or the second permanent magnet104in place.

In an aspect, for example but not limited hereto, the first component106may be a chassis, the second component108may be a display assembly or a screen, and the device100may be a computing device such as a hand-held device, a mobile phone, a laptop computer, etc. It should be understood, however, that the first component106and second component108each may be any type of device, component, or sub-component that may be fastened together.

Table 1 provides the maximum energy product and the maximum operating temperature of non-limiting example grades of the first permanent magnet102and the second permanent magnet104that may be used in various aspects.

As shown in Table 1, different grades of permanent magnets have different maximum operating temperatures, and a higher grade magnet has a higher maximum operating temperature as compared to a lower grade magnet. For example, for N52 grade magnets, the maximum operating temperature is 70 C, and for higher grade magnets such as N48H grade magnets, the maximum operating temperature is 120 C. If a permanent magnet is heated beyond its maximum operating temperature, the permanent magnet irreversibly and substantially lose its magnetic strength unless and until re-magnetized. A permanent magnet does not completely lose its magnetic strength unless heated up to its Curie temperature. For the example grades of permanent magnets in Table 1, the Curie temperature is above 300 C.

In an aspect, for example, the first permanent magnet102may be a higher grade magnet with a higher operating temperature compared to the second permanent magnet104. In an aspect, for example, the grade of the first permanent magnet102and the second permanent magnet104may be selected such that the maximum operating temperature of the first permanent magnet102is at least 40 C higher than the maximum operating temperature of the second permanent magnet104. In an aspect, for example, the grade of the first permanent magnet102and the second permanent magnet104may be selected such that the maximum operating temperature of the first permanent magnet102is 50 C higher than the maximum operating temperature of the second permanent magnet104. For example, the first permanent magnet102may be an N48H grade magnet with a maximum operating temperature of 120 C, and the second permanent magnet104may be an N52 grade magnet with a maximum operating temperature of 70 C. Accordingly, when the first permanent magnet102and the second permanent magnet104are aligned at temperatures below 70 C, the fastening assembly116is in the locked state due to the strong magnetic force between the first permanent magnet102and the second permanent magnet104. If the fastening assembly116or at least the second permanent magnet104is heated up beyond the maximum operating temperature of the second permanent magnet104, i.e., 70 C, the second permanent magnet104substantially loses magnetism and the fastening assembly116transitions from the locked state to the unlocked where the first permanent magnet102can be detached from the second permanent magnet104by applying a force greater than any remaining and substantially reduced magnetic attraction force between the first permanent magnet102and the second permanent magnet104.

In an aspect, in order to transition from the locked state to the unlocked state, the fastening assembly116or at least the second permanent magnet104may be heated beyond 70 C for at least a minimum time duration so that at least a substantial portion of the body of the second permanent magnet104reaches a temperature beyond 70 C. In an aspect, for example, the fastening assembly116or at least the second permanent magnet104may be heated, for example, by a heating fixture or a heat gun, and the minimum time duration required for heating the second permanent magnet104may depend on the body size of the second permanent magnet104and/or the proximity/location of the heating tool with respect to the second permanent magnet104. In an aspect, for example, a heat gun may be used to heat up the second permanent magnet104for 5-10 minutes to transition from the locked state to the unlocked state.

In an aspect, after a sufficient amount of time at a temperature above 70 C (e.g., one minute at 75-80 C), the second permanent magnet104undergoes irreversible magnetic field loss which results in an at least substantially reduced magnet force between and the first permanent magnet102and the second permanent magnet104such that the first permanent magnet102can be detached from the second permanent magnet104by applying a small force, and the amount of the force may depend on the geometry and/or the surface area of the first permanent magnet102and/or the second permanent magnet104. In an aspect, since the operating temperature of the first permanent magnet102is 120 C, the magnetism of the first permanent magnet102may not be affected by temperatures below 120 C. Accordingly, applying a temperature between 70 C and 120 C may substantially reduce the magnetism of the second permanent magnet104but may not affect the magnetism of the first permanent magnet102. Therefore, the second permanent magnet104may later be re-magnetized, for example, by being placed within a magnetizing fixture, so that the second permanent magnet104may be re-used to attach the first permanent magnet102to the second permanent magnet104in the locked state in the fastening assembly116.

In an aspect, in some implementations, the thinner the second permanent magnet104is, the faster it may lose its magnetic property when heated beyond its maximum operating temperature. In an aspect, given two heating temperatures that are both above the maximum operating temperature of the second permanent magnet104, the higher heating temperature may cause the second permanent magnet104to lose its magnetic property faster compared to the lower heating temperature. Optionally, in an aspect, in order to totally de-magnetize the second permanent magnet104and reduce the magnetic attraction force between the first permanent magnet102and the second permanent magnet104to zero, the second permanent magnet104may be heated up to its Curie temperature.

Aspects of the fastening assembly116may be applicable in any devices where the first component106and the second component108need to be fastened together without screws or other unsightly fastening mechanisms that cannot provide clean aesthetics. Alternatively and/or additionally, aspects of the fastening assembly116may be applicable as an alternative to PSA-based fastening. However, PSA-based fastening mechanisms are not re-usable once removed, and the leftover PSA needs to be cleaned after removing a PSA-based fastening mechanism, while the fastening assembly116may be re-usable with no such cleaning needed after unlocking the fastening assembly116.

Optionally, in aspects where the second permanent magnet104is attached to the second component108of the device100by the second adhesive layer112, the maximum operating temperature of the second permanent magnet104may be higher than the bonding temperature of the second adhesive layer112such that curing the second adhesive layer112does not de-magnetize the second permanent magnet104. In one aspect, for example, if the second adhesive layer112is curable at room temperature, the second permanent magnet104may be an N52 grade permanent magnet or a higher grade permanent magnet.

Optionally, in an aspect, the fastening assembly116may include a fastener member instead of the first permanent magnet102, and the material of the fastener member may be a magnetically-attractive material, such as a ferrous or soft magnet material, for being magnetically attractable by the second permanent magnet104in the locked state. In this optional aspect, the magnet body of the second permanent magnet104may be sized and/or otherwise configured to provide a magnetic attraction force between the second permanent magnet104and the fastener member to keep the fastening assembly116in the locked state at a temperature that is lower than the maximum operating temperature of the second permanent magnet104. Specifically, the magnet body of the second permanent magnet104may be sized and/or otherwise configured to induce a magnetic field around the second permanent magnet104such that when the fastener member is positioned within such magnetic field, the magnetic field magnetizes the magnetically-attractive material of the fastener member, and the interaction between the magnetic field of the second permanent magnet104and the magnetized material of the fastener member results in the magnetic attraction force between the second permanent magnet104and the fastener member. In an aspect, the fastener member may be made of stainless steel. For example, in an aspect, the fastener member may be made of a 100 grade steel. In an aspect, when the second permanent magnet104is heated up to a temperature that is above the maximum operating temperature of the second permanent magnet104, the second permanent magnet104may substantially lose magnetism. That is, the magnetic field of the second permanent magnet104may be substantially weakened, resulting in a substantial reduction in the magnetic attraction force between the second permanent magnet104and the fastener member. Accordingly, the fastening assembly116may transition from the locked state to the unlocked state where the second permanent magnet104can be easily detached/disengaged from the fastener member by applying a small force.

Referring now to the example flowchart500inFIG. 5, an aspect of the present disclosure provides a method of using the fastening assembly116in the device100for connecting the first component106of the device100to the second component108of the device100. At502the method includes attaching the first surface402of the first permanent magnet102to the first component106of the device100. At504the method further includes attaching the second surface408of the second permanent magnet104to the second component108of the device100. At506the method further includes attaching the first component106of the device100to the second component108of the device100by aligning the third surface404of the first permanent magnet102opposite the first surface402with the fourth surface406of the second permanent magnet104opposite the second surface408so as to lock the first permanent magnet102with the second permanent magnet104at the first temperature lower than the second operating temperature of the second permanent magnet104.

Optionally, at508the method may further include detaching the first component106of the device100from the second component108of the device100by unlocking the first permanent magnet102from the second permanent magnet104at the second temperature that is higher than the second operating temperature of the second permanent magnet104. In an aspect, for example, the unlocking may include heating the second permanent magnet104up to the second temperature so as to de-magnetize the second permanent magnet104, and applying a force greater than the magnetic attraction force between the first permanent magnet102and the second permanent magnet104at the second temperature above the second operating temperature of the second permanent magnet104.

Optionally, when the second temperature is above the second operating temperature of the second permanent magnet104but below a first operating temperature of the first permanent magnet102and hence does not de-magnetize the first permanent magnet102, at510the method may further include re-magnetizing the second permanent magnet104at the first temperature below the second operating temperature of the second permanent magnet104, and at512the method may further include re-attaching the first component106of the device100to the second component108of the device100by aligning the third surface404of the first permanent magnet102with the fourth surface406of the second permanent magnet104so as to lock the first permanent magnet102with the second permanent magnet104at the first temperature.

Optionally, in an aspect, the attaching of the first surface402of the first permanent magnet102to the first component106of the device100may include curing the first adhesive layer110between the first surface402of the first permanent magnet102and the first component106of the device100at a third temperature lower than the first operating temperature.

Optionally, in an aspect, the attaching of the second surface408of the second permanent magnet104to the second component108of the device100may include curing the second adhesive layer112between the second surface408of the second permanent magnet104and the second component108of the device100at a third temperature lower than the second operating temperature.

Optionally, in an aspect, the attaching of the first surface402of the first permanent magnet102to the first component106of the device100may include placing the first permanent magnet102within the first opening302configured on the first component106of the device100.

Optionally, in an aspect, the attaching of the second surface408of the second permanent magnet104to the second component108of the device100includes placing the second permanent magnet104within the second opening304configured on the second component108of the device100.

In some implementations, the apparatus of the present disclosure may be in the form of a kit of parts that can be assembled to form the apparatus. For instance, in an aspect a fastening assembly kit is provided. The fastening assembly kit includes a first permanent magnet having a first operating temperature and a second permanent magnet having a second operating temperature lower than the first operating temperature. The first permanent magnet is attachable to the second permanent magnet in a locked state at a first temperature lower than the second operating temperature. The first permanent magnet is releasable from the second permanent magnet in an unlocked state at a second temperature that is higher than the second operating temperature. In an aspect, the fastening assembly kit further includes a first component attachable to a first surface of the first permanent magnet, and a second component attachable to a second surface of the second permanent magnet, where a third surface of the first permanent magnet opposite the first surface is attachable to a fourth surface of the second permanent magnet opposite the second surface in the locked state so as to attach the first component to the second component. Accordingly, the first permanent magnet is releasably attachable to the second permanent in the locked state. In an aspect, the first permanent magnet is forcibly releasable from the second permanent magnet in the unlocked state by applying a force greater than a magnetic attraction force between the first permanent magnet and the second permanent magnet at the second temperature.

Thus, the described fastening assembly allows for using two permanent magnets of different grades/operating temperatures to provide a temporary fastening mechanism. The two permanent magnets are sized and/or otherwise configured such that a high strength magnetic attraction force between the two permanent magnets causes a locked state of the fastening assembly. The two permanent magnets may be separated by heating at least one of the permanent magnets up to or slightly over its maximum operating temperature.