Flux-leakage magnetic conductive plate and flux-leakage magnetic holding device

A magnetic conductive coverplate of leakage type that may used in magnetic holding devices covers a holding surface of the magnetic holding device. The leakage type magnetic conductive coverplate is made integrally of a single magnetic conductive material. The leakage type magnetic conductive coverplate can conduct magnetic force of the holding device into a workpiece so as to hold it. Because the leakage type magnetic conductive coverplate is made integrally of a single magnetic conductive material, when there is any change in ambient temperature, no crevice will be produced due to different coefficients of expansion and contraction. Therefore, any coolant used in workpiece machining and any magnetic conductive impurities will not infiltrate into or enter the magnetic holding device to lose the internal insulation, thus effectively protecting the internal structure of the magnetic holding device and remarkably improving durability and service life of the magnetic holding device.

CROSS-REFERENCE TO FOREIGN PRIORITY APPLICATION

FIELD OF THE INVENTION

The present disclosure relates to a kind of magnetic conductive coverplate of leakage type used in magnetic holding devices and a kind of magnetic holding device of leakage type.

BACKGROUND OF THE INVENTION

Magnetic holding devices can be divided into electromagnetic holding device and electric permanent magnetic holding device according to their use of electricity in operation.

An electromagnetic holding device is a holding device, inside which are the iron core and the coil around it. When direct current runs through the coil continuously, magnetic flux is generated by the iron core, and the holding device shows magnetism externally; when current stops, magnetic flux disappears, and the holding device does not show magnetism externally. Most of the current devices are designed without magnetic leakage. This means that utmost use can be made of magnetic force. However, non-magnetic-conductive material must be used between magnetic poles to separate them, to prevent magnetic short-circuit between poles. Usually, the material used is epoxy resin or non-ferrous metals, such as copper. Because the working surface of the holding device is made of two materials, when there is any change in ambient temperature, it is liable to produce crevices due to different coefficients of expansion and contraction, and coolant and other magnetic conductive substances will thus infiltrate into the holding device, to lose internal insulation in the holding device, reducing service life of the holding device.

An electric permanent magnetic holding device is now widely used in the field of mechanical processing as a kind of highly efficient holding method thanks to its advantages of no electric consumption during operation, no thermal deformation, and great holding power. They are divided into two types according to their design of magnetic circuits, with magnetic variation and without magnetic variation. No matter what type is used, it is currently designed without magnetic leakage. This means that utmost use can be made of magnetic force.

The so-called electric permanent magnetic holding device with magnetic variation is the device in which there are two different kinds of magnets to form the circuit. The magnets are generally made from NdFeB with higher coercivity and Alnico with lower coercivity. The direction of the lines of magnetic force of Alnico can be determined by the direction of the current in the external field coil. When the lines of magnetic force of both magnets are in the same direction, magnetism is shown externally. When the lines of magnetic force of the two magnets are in the opposite direction, they are neutralized, and no magnetism is shown externally. However, non-magnetic-conductive material must be used between magnetic poles to separate them, to prevent magnetic short-circuit between poles. Usually the material used is epoxy resin or non-ferrous metals, such as copper. Because the working surface of the holding device is made of two materials, when there is any change in ambient temperature, it is liable to produce crevices due to different coefficients of expansion and contraction, and coolant and other magnetic conductive substances will thus infiltrate into the holding device, to lose internal insulation in the holding device, reducing service life of the holding device.

The so-called electric permanent magnetic holding device without magnetic variation is the device in which there is only one kind of magnet to form the circuit. The magnet is generally made from Alnico with lower coercivity. The direction of the lines of magnetic force of Alnico can be determined by the direction of the current in the external field coil. After the field coil magnetizes Alnico, magnetism is shown externally. After the field coil demagnetizes Alnico oscillatorily, magnetism is not shown externally.

However, non-magnetic-conductive material must be used between magnetic poles to separate them, to prevent magnetic short-circuit between poles. Usually the material used is epoxy resin or non-ferrous metals, such as copper. Because the working surface of the holding device is made of two materials, when there is any change in ambient temperature, it is liable to produce crevices due to different coefficients of expansion and contraction, and coolant and other magnetic conductive substances will thus infiltrate into the holding device, easy to lose internal insulation in the holding device, reducing service life of the holding device.

SUMMARY OF THE INVENTION

In order to solve the above-discussed issues, it is the object of the present disclosure to provide a kind of magnetic conductive coverplate of leakage type used in magnetic holding devices; the magnetic holding device includes a holding surface formed jointly by source magnets and non-magnetic-conductive material; the leakage type magnetic conductive coverplate covers the holding surface of the magnetic holding device; the leakage type magnetic conductive coverplate is made integrally of a single magnetic conductive material.

With such a structure, the leakage type magnetic conductive coverplate can conduct the magnetic force of the holding device into a workpiece so as to hold it. Because the leakage type magnetic conductive coverplate is made integrally of a single magnetic conductive material, when there is any change in ambient temperature, no crevices will be produced due to different coefficients of expansion and contraction. Therefore, the coolant used in workpiece machining and any magnetic conductive impurities will not infiltrate into or enter the holding device from above to lose the internal insulation in the holding device. The leakage type magnetic conductive coverplate covers the holding surface of the magnetic holding device, thus effectively prolonging service life of the holding device.

Preferably, the leakage type magnetic conductive coverplate seals up the holding surface of the magnetic holding device.

Because the leakage type magnetic conductive coverplate covers and seals up the holding surface, the whole leakage type magnetic holding device is in a closed state by means of the leakage type magnetic conductive coverplate, thus effectively protecting the internal structure of the holding device, and greatly improving durability and service life of the holding device.

Furthermore, the leakage type magnetic conductive coverplate contains several magnetic conductive areas and the magnetic leakage area surrounding them, several magnetic conductive areas correspond to the source magnets one to one inside the magnetic holding device, the magnetic leakage area contains the inner grooves set on the inner surface of the leakage type magnetic conductive coverplate and/or the outer grooves set on the outer surface of the leakage type magnetic conductive coverplate.

Preferably, the inner grooves are separated from and opposite to the outer grooves.

Preferably, the depth of the inner grooves is greater than that of the outer grooves.

Furthermore, the leakage type magnetic conductive coverplate coves the magnetic holding device by fixing with a fastening mechanism.

Preferably, the fastening mechanism includes screws, several magnetic conductive areas on the leakage type magnetic conductive coverplate have through holes for inserting the screws.

Preferably, the fastening mechanism includes frame walls set on the edges of the leakage type magnetic conductive coverplate, the frame walls are used to be engaged in the matching structure on the magnetic holding device, thus fixing the leakage type magnetic conductive coverplate onto the magnetic holding device.

The present disclosure provides another kind of magnetic holding device of leakage type, including the base and several source magnets. The base has a bottom and the side walls perpendicular to the bottom, and a cavity having an opening on the top and formed by the bottom and the surrounding side walls. Several source magnets are distributed in the cavity, and lines of magnetic force of the source magnets are conducted outwards from inside the opening. The cavity around the source magnets are filled with non-magnetic-conductive material. The magnetic conductive coverplate as mentioned above is also included.

With such a structure, the leakage type magnetic conductive coverplate can conduct the magnetic force of the holding device into a workpiece so as to hold it. Because the outer surface of the leakage type magnetic conductive coverplate is made integrally of a single magnetic conductive material, when there is any change in ambient temperature, no crevices will be produced due to different coefficients of expansion and contraction. Therefore, the coolant used in workpiece machining and any magnetic conductive impurities will not infiltrate into or enter the holding device from above to lose internal insulation in the holding device, thus effectively prolonging service life of the holding device. Because leakage type magnetic conductive coverplate covers and seals up the holding surface, the whole leakage type magnetic holding device is in a closed state by means of the leakage type magnetic conductive coverplate, thus effectively protecting the internal structure of the holding device, and remarkably improving durability and service life of the holding device.

Furthermore, each of the source magnets includes an iron core and the field coil around it, and the iron core extends from the inner surface of the bottom to the inner surface of the leakage type magnetic conductive coverplate.

Furthermore, each of the source magnets includes a core block on the upper part, a reversible magnet on the lower part and a field coil around the corresponding reversible magnet, the top of the core block presses against the inner surface of the leakage type magnetic conductive coverplate, and the reversible magnet is located between the inner surface of the bottom and the core block.

Preferably, each of the source magnets also includes an irreversible magnet. The irreversible magnet is set between any two core blocks, and between the core block and the inner surface of the side wall.

To sum up, the leakage type magnetic holding device and the leakage type magnetic conductive coverplate of the present utility model use the leakage type magnetic conductive coverplate to cover the holding surface of the holding device. The surface in contact with the workpiece on the leakage type magnetic holding device is formed by a single magnetic conductive material, thus to avoid crevices produced due to different coefficients of expansion and contraction when there is any change in ambient temperature, so that the coolant and other magnetic conductive impurities will not infiltrate into the holding device from above, thus effectively prolonging service life of the holding device with a high value for marketing.

In order to make the above description of the present disclosure more understandable, the preferable embodiments are detailed below with reference to the figures attached:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment of the present disclosure is described below with specific embodiments. One of ordinary skill in the art can easily understand other advantages and functions of the present disclosure from the contents revealed in this specification. Although the present disclosure will be presented with relatively better embodiments, it does not mean that the present disclosure is limited to these embodiments only. On the contrary, the purpose of presentation of the present disclosure with embodiments is to cover other choices or modifications which may extend from the claims of the present disclosure. In order to provide a deeper understanding of the present disclosure, the description below will include many specific details. The present disclosure can also be embodied without these details. Besides, to avoid confusion or ambiguity in the key points of the present disclosure, some of the details are omitted in the description.

In addition, the words “upper,” “lower,” “left,” “right,” “top,” and “bottom” used in the description below should not be interpreted as limitation to the present disclosure.

FIG.1ashows the overall structure of the leakage type magnetic conductive coverplate based on the first embodiment of the present disclosure;FIG.1bis the three-dimensional broken-out section view of the leakage type magnetic conductive coverplate based on the first embodiment of the present disclosure;FIG.1cis the three-dimensional broken-out section view of the first embodiment of the magnetic holding device of the present disclosure;FIG.1dis the three-dimensional broken-out section view of the first embodiment of the leakage type magnetic conductive coverplate of the present disclosure with the fastening mechanism inserted from the bottom;FIG.1eis the three-dimensional broken-out section view of the first embodiment of the leakage type magnetic holding device of the present disclosure with the fastening mechanism inserted from the bottom;FIG.1fis the three-dimensional broken-out section view of the first embodiment of the leakage type magnetic conductive coverplate with frame walls of the present disclosure;FIG.1gis the three-dimensional broken-out section view of the first embodiment of the leakage type magnetic holding device with frame walls of the present disclosure;FIG.1his the section view of the first embodiment of the leakage type magnetic holding device with frame walls of the present disclosure under excitation condition.

As shown inFIGS.1ato1c, the first embodiment of the present disclosure provides a kind of leakage type magnetic conductive coverplate4used in a magnetic holding device100; magnetic holding device100includes a holding surface102formed jointly by source magnets3and a non-magnetic-conductive material101, a leakage type magnetic conductive coverplate4covers the holding surface102of the magnetic holding device100, the leakage type magnetic conductive coverplate4is made integrally of a single magnetic conductive material.

Preferably, the leakage type magnetic conductive coverplate4is an integral cover plate formed by a single magnetic conductive material, in which, magnetic conductive material is meant by the material of higher magnetic permeability, such as low carbon steel.

Furthermore, the leakage type magnetic conductive coverplate4also seals up the holding surface of the magnetic holding device. With such a structure, the whole leakage type magnetic holding device is put in a closed state. The coolant used in workpiece machining and magnetic conductive impurities will not infiltrate into or enter the holding device100from the holding surface102, thus effectively protecting the internal structure of the holding device100.

In this embodiment, the leakage type magnetic conductive coverplate4can be designed into different shapes, such as a triangle or circle, to match the holding device100. The leakage type magnetic conductive coverplate4contains several magnetic conductive areas41, and the leakage area42surrounding the magnetic conductive areas41; several magnetic conductive areas41correspond to several source magnets3, one-to-one inside the magnetic holding device100; the leakage area42contains inner grooves43set on the inner surface of the leakage type magnetic conductive coverplate4and/or the outer grooves44set on the outer surface of the leakage type magnetic conductive coverplate4.

More specifically, in the first embodiment of the present disclosure, the non-magnetic-conductive material101can be filled in the inner groove43; or a stainless steel bar can be set in the inner groove43to reinforce the leakage type magnetic conductive coverplate4. The stainless steel bar can be welded in the inner groove43, or be set in the inner groove43by other means, and in the inner groove43, the stainless steel bar is covered by the non-magnetic-conductive material101. In the first embodiment of the present disclosure, the inner grooves43, which surround the magnetic conductive area41, can be made by milling or other means on the leakage area42on the inner surface of the plate-shaped single magnetic conductive material forming leakage type magnetic conductive coverplate4, and a stainless steel bar is placed in the inner groove43, then the non-magnetic-conductive material101is poured in the inner groove43with the stainless steel bar placed inside so that the inner surface of the whole leakage type magnetic conductive coverplate4is flattened; or only the non-magnetic conductive material101is poured without placing a stainless steel bar. With this method, the magnetic conductive areas41corresponding to the source magnets3one-to-one, and the leakage area42surrounding the magnetic conductive areas41can be formed on the leakage type magnetic conductive coverplate4. More specifically, the non-magnetic-conductive material101is epoxy resin.

Alternatively, no material is filled in the inner groove43so that the space in the inner groove43can be full of the non-magnetic-conductive material when it expands at heat inside the holding device, thus ensuring flatness of the whole holding surface.

Furthermore, the magnetic leakage area42also contains outer grooves44set on the outer surface of the leakage type magnetic conductive coverplate4with or without setting of the inner grooves43. When both the inner and outer grooves43,44are set, inner groove43and outer groove44are separated from and opposite to each other, i.e., the leakage area42is formed by inner grooves43and outer grooves44set on the inner and outer surfaces of the leakage type magnetic conductive coverplate4and separated from and opposite to each other, between the inner groove43and outer groove44is a thin interlayer. More specifically, the depth of outer groove44can be less than that of the inner groove43. With such a structure, positions of the magnetic conductive area41and the leakage area42can be marked on the outer surface of leakage type magnetic conductive coverplate4to convenience identification of each area on the leakage type magnetic conductive coverplate4by operators from outside. Outer groove44in this embodiment is only a structure for marking each area on the leakage type magnetic conductive coverplate4from outside. One of ordinary skill in the art should understand that the structure for marking each area on the leakage type magnetic conductive coverplate4from outside is not limited to the embodiments enumerated in present disclosure.

Furthermore, leakage type magnetic conductive coverplate4is fixed onto the magnetic holding device100by means of a fastening mechanism6. Preferably, the fastening mechanism6includes screws. When the screws6are inserted from the leakage type magnetic conductive coverplate4into the magnetic holding device100, screw holes7for inserting the screws6are set in several magnetic conductive areas41on the leakage type magnetic conductive coverplate4. The screw holes7can be set separately in the centers of several magnetic conductive areas41or other positions good for fixation. The upper part of the screw hole7is set in the leakage type magnetic conductive coverplate4, and the lower part is set in the magnetic holding device100to match the upper part. The screw6is inserted from the upper part into the lower part of the screw hole7, thus affixing the leakage type magnetic conductive plate4onto the magnetic holding device100.

Preferably, as shown inFIGS.1dand1e, when the screw6is inserted from the bottom of the the magnetic holding device100into the leakage type magnetic conductive coverplate4, in this case, the upper part of screw hole7is set in the magnetic holding device100; accordingly, the lower part of the screw hole7is set in the relevant position on the inner surface of the leakage type magnetic conductive coverplate4. The screw6is inserted from the upper part into the lower part of the screw hole7, so as to affix leakage type magnetic conductive coverplate4onto the magnetic holding device100from the bottom of the magnetic holding device100. The fastening mechanism can also be bolts or other elements having the same function.

Preferably, as shown inFIGS.1fto1h, the fastening mechanism also includes frame walls8set around the edges of the leakage type magnetic conductive coverplate4. The frame walls8are used to be engaged in the matching structure on magnetic holding device100, thus affixing the leakage type magnetic conductive coverplate4onto magnetic holding device100. With such a method, not only leakage type magnetic conductive coverplate4can be affixed onto the magnetic holding device100in an easy way, thus simplifying production and manufacturing processes, but the accuracy of positioning between leakage type magnetic conductive coverplate4and the magnetic holding device100can also be ensured, thus extending service life and application scope of the whole holding device.

According to the magnetic conductive coverplate4of the first embodiment of present disclosure, because the leakage type magnetic conductive coverplate4is made integrally of a single magnetic conductive material, and this magnetic conductive coverplate4covers the holding surface of holding device100, when there is any change in ambient temperature, no crevices will be produced due to different coefficients of expansion and contraction. Therefore, the coolant used in processing of workpiece5and magnetic conductive impurities will not infiltrate into or enter holding device100to lose internal insulation in holding device100, thus protecting the internal structure of holding device100and effectively prolonging service life of holding device100. Furthermore, the leakage area42is of small thickness; therefore, this magnetic leakage has small impact on magnetism shown externally on holding device100. Such a structure is also advantageous to the magnetic holding device in demagnetization. Remnant magnetism on the surface of leakage type magnetic conductive coverplate4is removed by means of a magnetic short-circuit to reduce the effect of remnant magnetism.

FIG.2ashows the three-dimensional broken-out section view of the leakage type magnetic holding device1based on the second embodiment of the present disclosure;FIG.2bshows the section view along line A-A inFIG.2aof the leakage type magnetic holding device1based on the second embodiment of the present disclosure under excitation condition;FIG.2cis the partially enlarged view ofFIG.2b;FIG.2dshows the top view of the leakage type magnetic holding device1based on the second embodiment of the present disclosure under excitation condition.

Leakage type magnetic holding device1based on the second embodiment of present disclosure is a leakage type electric permanent magnetic holding device with no magnetic variation. As shown inFIGS.2ato2c, the leakage type magnetic holding device1provided on the basis of the second embodiment of the present disclosure includes: base2and several source magnets3; base2has a bottom21, side walls22perpendicular to the bottom, and a cavity23having an opening on the top and formed by the bottom21and the surrounding side walls22. Several source magnets3are distributed in the cavity23, lines of magnetic force of source magnets3conducted outwards from inside the opening, the cavity around source magnets3is filled with magnetic-non-conductive material101; also includes a leakage type magnetic conductive coverplate4covering the opening of cavity23, the leakage type magnetic conductive coverplate4is made integrally of a single magnetic conductive material.

In this embodiment, the leakage type magnetic conductive coverplate4is in a rectangular shape, and the outer surface of this leakage type magnetic conductive coverplate4is the holding surface of the holding device to hold a workpiece5for machining. Source magnets3can be evenly distributed in the cavity23, and their number can be determined with actual needs. In this embodiment, they are set to four. These four source magnets are arranged in two rows and two columns in the cavity23on the base1. However, the number of source magnets3in this embodiment is obviously not limited to four, and the shapes of the leakage type magnetic conductive coverplate4and the base1are not limited to rectangles, and the arrangement of the source magnets3in the cavity23is not limited to evenly-distributed two rows and two columns.

With such a structure, the leakage type magnetic conductive coverplate4can conduct magnetic force of the holding device into workpiece5so as to hold it. Furthermore, the leakage type magnetic conductive coverplate4also seals up the holding surface of the magnetic holding device. Because the leakage type magnetic conductive coverplate4covers the opening of cavity23, the edges of the leakage type magnetic conductive coverplate4are tightly connected with the side walls22of the base1, the whole holding device is thus in a closed state through the leakage type magnetic conductive coverplate4, effectively protecting the internal structure of the holding device, and remarkably improving durability and service life of the holding device.

More specifically, as shown inFIGS.2ato2c, in the leakage type magnetic holding device provided in this embodiment, the leakage type magnetic conductive coverplate4contains several magnetic conductive areas41and the leakage area42surrounding the magnetic conductive areas41, the magnetic conductive areas41match the source magnets3one-to-one in a direction perpendicular to the inner surface of bottom21. The magnetic conductive areas41conduct the magnetic force outwards from inside the holding device, thus forming the magnetic poles to hold the workpiece5.

More specifically, in the second embodiment of the present utility module, the leakage area42of the leakage type magnetic conductive coverplate4contains inner grooves43set on the inner surface of the leakage type magnetic conductive coverplate4and/or the outer grooves44set on the outer surface of leakage type magnetic conductive coverplate4. Non-magnetic-conductive material101can be filled in the inner groove43; or a stainless steel bar can be set in inner groove43to reinforce leakage type magnetic conductive coverplate4. The stainless steel bar can be welded in the inner groove43, or be set in the inner groove43by other means, and in the inner groove43the stainless steel bar is covered by the non-magnetic-conductive material101. In the second embodiment of the present disclosure, the inner groove43, which surrounds the magnetic conductive area41, can be made by milling or other means on the inner surface of leakage area42on the plate-shaped single magnetic conductive material forming leakage type magnetic conductive coverplate4, and a stainless steel bar is placed in the inner groove43, then non-magnetic-conductive material101is poured in the inner groove43with the stainless steel bar placed inside so that the inner surface of the whole leakage type magnetic conductive coverplate4is flattened; or only the non-magnetic-conductive material101is poured in the inner groove43without placing a stainless steel bar. Preferably, the non-magnetic-conductive material101is epoxy resin.

Alternatively, no material is filled in the inner groove43so that the space in the inner groove43can be full of the non-magnetic-conductive material when it expands at heat inside the holding device, thus ensuring flatness of the whole holding surface.

Furthermore, the magnetic leakage area42also contains outer grooves44set on the outer surface of the leakage type magnetic conductive coverplate4with or without setting of the inner grooves43. When both the inner and outer grooves43,44are set, the inner groove43and the outer groove44are separated from and opposite to each other, i.e., the leakage area42is formed by the inner groove43and the outer groove44set on the inner and outer surfaces of the leakage type magnetic conductive coverplate4and separated from and opposite to each other, between the inner groove43and the outer groove44is a thin interlayer. In this embodiment, the depth of the outer groove44is less than that of the inner groove43. With such design, positions of the magnetic conductive area41and the leakage area42can be marked on the outer surface of the leakage type magnetic conductive coverplate4to convenience identification of each area on the leakage type magnetic conductive coverplate4by operators from outside. Outer groove44in this embodiment is only a structure for marking each area on the leakage type magnetic conductive coverplate4from outside. One of ordinary skill in the art should understand that the structure for marking each area on the leakage type magnetic conductive coverplate4from outside is not limited to the embodiments enumerated in the present disclosure.

More specifically, in the second embodiment of the present disclosure, each source magnet3contains a core block31aon the upper part, a reversible magnet31bon the lower part, and a field coil32around a reversible magnet3bcorresponding to it, one-to-one; the top of core block31apresses against the inner surface of the leakage type magnetic conductive coverplate4, the reversible magnet31bis located between the inner surface of the bottom and the core block31a. Magnetic material, such as Alnico, can be chosen for the reversible magnet31b. As shown inFIG.2b, the reversible magnet31bis set in each core block31ain several source magnets3just below and pressing against the core block31a. When instantaneous current runs through the field coil32, the reversible magnet31bis excited, polarity N-S is exhibited from top to bottom; when the adjacent reversible magnet31bis excited, polarity is S-N from top to bottom, thus a magnetic circuit, as shown inFIG.2b, is formed among the reversible magnet31b, the adjacent reversible magnet31b, the core block31a, the leakage type magnetic conductive coverplate4, the base2, and a workpiece5. In this way, the magnetic holding device1shows magnetism externally, holding the workpiece5to be processed onto the outer surface of the leakage type magnetic conductive coverplate4.

In the case that holding needs to be released, the current with gradually attenuating oscillation runs through the field coil32, the reversible magnet31bis demagnetized gradually, so that the leakage type magnetic holding device100does not show magnetism externally, holding of the workpiece5on the outer surface of leakage type magnetic conductive coverplate4is released.

Furthermore, the leakage type magnetic conductive coverplate4is fixed onto the magnetic holding device100by means of fastening mechanism6. Preferably, fastening mechanism6includes screws. When screws6are inserted from the leakage type magnetic conductive coverplate4into magnetic holding device100, screw holes7for inserting the screws6are set in several magnetic conductive areas41on the leakage type magnetic conductive coverplate4. Screw holes7can be set separately in the centers of several magnetic conductive areas41or other positions good for fixation. The upper part of screw hole7is set in the leakage type magnetic conductive coverplate4, and the lower part is set in the magnetic holding device100to match the upper part. The screw6is inserted from the upper part into the lower part of the screw hole7, thus fixing the leakage type magnetic conductive plate4onto the magnetic holding device100.

Preferably, as shown inFIGS.1dand1e, when the screw6is inserted from the bottom of the the magnetic holding device100into the leakage type magnetic conductive coverplate4, in this case, the upper part of the screw hole7is set in the magnetic holding device100, accordingly, the lower part of the screw hole7is set in the relevant position on the inner surface of the leakage type magnetic conductive coverplate4. The screw6is inserted from the upper part into the lower part of screw hole7, so as to fix the leakage type magnetic conductive coverplate4onto the magnetic holding device100from the bottom of the magnetic holding device100. The fastening mechanism can also be bolts or other elements having the same function.

Preferably, as shown inFIGS.1gto1h, the fastening mechanism also includes frame walls8set around the edges of leakage type magnetic conductive coverplate4. The frame walls8are used to be engaged in the matching structure on the magnetic holding device100, thus affixing the leakage type magnetic conductive coverplate4onto the magnetic holding device100. With such a method, not only the leakage type magnetic conductive coverplate4can be affixed onto the base2in an easy way, thus simplifying production and manufacturing processes, but the accuracy of positioning between the leakage type magnetic conductive coverplate4and the base2can also be ensured, thus extending service life and application scope of the whole holding device.

According to the leakage type magnetic holding device1of the second embodiment of the present disclosure, because the leakage type magnetic conductive coverplate4is made integrally of a single magnetic conductive material, and this magnetic conductive coverplate4covers the opening of the cavity23in the base2, when there is any change in the ambient temperature, no crevices will be produced due to different coefficients of expansion and contraction. Therefore, the coolant used in processing of the workpiece5and the magnetic conductive impurities will not infiltrate into or enter the leakage type magnetic holding device1to lose internal insulation in the leakage type magnetic holding device1, thus protecting the internal structure of the holding device100and effectively prolonging service life of the leakage type magnetic holding device1. Furthermore, the leakage area42is of small thickness, therefore, this the magnetic leakage42has small impact on magnetism shown externally on the leakage type magnetic holding device1. Such a structure is also advantageous to the the magnetic holding device in demagnetization. Remnant magnetism on the surface of the leakage type magnetic conductive coverplate4is removed by means of magnetic short-circuit to reduce the effect of remnant magnetism.

FIG.3ashows the three-dimensional, broken-out section view of the leakage type magnetic holding device1based on the third embodiment of the present disclosure;FIG.3bshows the section view along line A-A inFIG.3aof the leakage type magnetic holding device1based on the third embodiment of the present disclosure under excitation condition;FIG.3cis the partially enlarged view ofFIG.3b;FIG.3dshows the top view of the leakage type magnetic holding device1based on the third embodiment of the present disclosure under excitation condition. In the appended drawings used in this embodiment, the same definitions are followed for the reference numbers identical with those in the above embodiments.

Leakage type magnetic holding device1based on the third embodiment of the present disclosure is a leakage type electric permanent magnetic holding device with magnetic variation.

The difference between the leakage type magnetic holding device1of the third embodiment and that of the second embodiment lies in that the source magnet3also contains an irreversible magnet33set around the periphery of each core block31ain several source magnets3. Permanent magnets, such as NdFeB, can be chosen for the irreversible magnet33.

As shown inFIGS.3a,3b, and3c, instantaneous current runs through field coil32, reversible magnet31bis excited in forward direction, polarity N-S is exhibited from top to bottom; when the adjacent reversible magnet31bis excited, polarity S-N is exhibited from top to bottom, thus magnetic circuits as shown inFIG.3bare formed among the reversible magnet31b, the adjacent reversible magnet31b, the leakage type magnetic conductive coverplate4, the core block31a, the workpiece5, and the base2, and among the core block31a, the irreversible magnet33, the leakage type magnetic conductive coverplate4, the side wall22, and the workpiece5, and among the core block31a, the irreversible magnet33, the workpiece5, and the leakage type magnetic conductive coverplate4. In this way, the leakage type magnetic holding device1shows magnetism externally, holding the workpiece5to be processed onto the outer surface of the leakage type magnetic conductive coverplate4.

In the case that holding needs to be released, instantaneous reverse current runs through the field coil32, the reversible magnet31bis excited in reverse direction, polarity S-N is exhibited from top to bottom; when the adjacent reversible magnet31bis excited, polarity N-S is exhibited from top to bottom, thus magnetic short-circuits are formed among the reversible magnet31b, the adjacent reversible magnet31b, the irreversible magnet33, the core block31a, and the lower base2, and among the reversible magnet31b, the lower base2, the side wall22, the irreversible magnet33, and the core block31a. In this way, the leakage type magnetic holding device1does not show magnetism externally, holding of the workpiece5on the outer surface of the leakage type magnetic conductive coverplate4is released.

FIG.4ashows the section view of the leakage type magnetic holding device1based on the fourth embodiment of the present disclosure under excitation condition;FIG.4bis the partially enlarged view ofFIG.4a;FIG.4cshows the top view of the leakage type magnetic holding device1based on the fourth embodiment of the present disclosure under excitation condition;FIG.4dis the section view of the leakage type magnetic holding device based on the fourth embodiment of the present disclosure under demagnetization condition;FIG.4eis the top view of the leakage type magnetic holding device of the fourth embodiment of the present disclosure under demagnetization condition. In the appended drawings used in this embodiment, the same definitions are followed for the reference numbers identical with those in the above embodiments.

The fourth embodiment is a variation of the second embodiment. As shown inFIGS.4ato4d, the difference between leakage type magnetic holding device1of the fourth embodiment and that of the second embodiment lies in that the number of the source magnets3is set to three, and three source magnets3are arranged in one line in the cavity23in the base2. More specifically, the number of source magnets3is set to three, but not limited to three, and any two of the three source magnets3have a partition wall24in between. The partition wall24extends from the inner surface of the bottom21of the base2to the inner surface, which faces the bottom21, of the leakage type magnetic conductive coverplate4. More specifically, the partition wall24is also made of magnetic conductive material, and is integrated with the bottom21.

FIG.5ashows the section view of leakage type magnetic holding device1based on the fifth embodiment of the present disclosure under excitation condition;FIG.5bis the partially enlarged view ofFIG.5a;FIG.5cshows the top view of leakage type magnetic holding device1based on the fifth embodiment of the present disclosure under excitation condition;FIG.5dis the section view of the leakage type magnetic holding device1based on the fifth embodiment of the present disclosure under demagnetization condition;FIG.5eis the top view of the leakage type magnetic holding device1of the fifth embodiment of the present disclosure under demagnetization condition. In the appended drawings used in this embodiment, the same definitions are followed for the reference numbers identical with those in the above embodiments.

The fifth embodiment is a variation of the third embodiment. As shown inFIGS.5ato5d, the difference between the leakage type magnetic holding device1of the fifth embodiment and that of the third embodiment lies in that the number of the source magnets3is set to three, and three source magnets3are arranged in one line in the cavity23in the base2. More specifically, the number of source magnets3is set to three, but not limited to three, and any two of the three source magnets3have a partition wall24in between. The partition wall24extends from the inner surface of the bottom21of the base2to the inner surface, which faces the bottom21, of the leakage type magnetic conductive coverplate4. More specifically, partition wall24is also made of magnetic conductive material, and is integrated with the bottom21.

FIG.6ashows the section view of the leakage type magnetic holding device1based on the sixth embodiment of the present disclosure under excitation condition;FIG.6bis the partially enlarged view ofFIG.6a;FIG.6cshows the top view of the leakage type magnetic holding device1based on the sixth embodiment of the present disclosure under excitation condition;FIG.6dis the section view of the leakage type magnetic holding device1based on the sixth embodiment of the present disclosure under demagnetization condition;FIG.6eis the top view of the leakage type magnetic holding device1of the sixth embodiment of the present disclosure under demagnetization condition. In the appended drawings used in this embodiment, the same definitions are followed for the reference numbers identical with those in the above embodiments.

The sixth embodiment is a variation of the second embodiment. As shown inFIGS.6ato6c, the difference between the leakage type magnetic holding device1of the sixth embodiment and that of the second embodiment lies in that the leakage type magnetic holding device1of the sixth embodiment is cylindrical; the upper surface of the leakage type magnetic conductive coverplate4is circular, and can be used as the working surface for processing the ring-shaped workpiece5; several source magnets3in the cavity23in the base2are evenly distributed in the cavity23in the base2in circumferential direction, and the cross section of the core block31ain each source magnet3, parallel with the upper surface of the leakage type magnetic conductive coverplate4, is trapezoidal. More specifically, the number of several source magnets3is set to eight, but not limited to eight, and any two of the several source magnets3have a partition wall24in between. The partition wall24extends from the inner surface of the bottom21of the base2to the inner surface, which faces the bottom21, of leakage type magnetic conductive coverplate4. More specifically, partition wall24is also made of magnetic conductive material, and is integrated with the bottom21. One of ordinary skill in the art should understand that the structure of leakage type magnetic holding device is not limited to enumeration in this embodiment, there are also other structures to be included with the same functions, for instance, the cross section of the core block31ain the source magnet3of the leakage type magnetic holding device1, parallel with the outer surface of leakage type magnetic conductive coverplate4, may also be triangular.

As shown inFIGS.6ato6c, instantaneous forward current runs through a field coil32, all reversible magnets31bare excited in forward direction, exhibiting polarities N-S from top to bottom, thus magnetic circuits as shown inFIG.6aare formed among the workpiece5, the side wall22, the base2, the leakage type magnetic conductive coverplate4, the reversible magnet31b, and the core block31a, and among workpiece5, the core block31a, the reversible magnet31b, the leakage type magnetic conductive coverplate4, the lower base2and the partition wall24. In this way, the leakage type magnetic holding device1shows magnetism externally, holding the workpiece5to be processed onto the outer surface of leakage type magnetic conductive coverplate4.

As shown inFIG.6d, in the case that holding needs to be released, the current with gradually attenuating oscillation runs through the field coil32, the reversible magnet31bis demagnetized gradually, so that leakage type magnetic holding device1does not show magnetism externally, holding of the workpiece5on the outer surface of the leakage type magnetic conductive coverplate4is released.

FIG.7ashows the section view of the leakage type magnetic holding device1based on the seventh embodiment of the present disclosure under excitation condition;FIG.7bis the partially enlarged view ofFIG.7a;FIG.7cshows the top view of the leakage type magnetic holding device1based on the seventh embodiment of the present disclosure under excitation condition;FIG.7dis the section view of the leakage type magnetic holding device1based on the seventh embodiment of the present disclosure under demagnetization condition;FIG.7eis the top view of the leakage type magnetic holding device1of the seventh embodiment of the present disclosure under demagnetization condition. In the appended drawings used in this embodiment, the same definitions are followed for the reference numbers identical with those in the above embodiments.

The seventh embodiment is a variation of the third embodiment. As shown inFIGS.7ato7d, the difference between the leakage type magnetic holding device1of the seventh embodiment and that of the third embodiment lies in that the leakage type magnetic holding device1of the seventh embodiment is cylindrical; the upper surface of the leakage type magnetic conductive coverplate4is circular, and can be used as the working surface for processing the ring-shaped workpiece5; several source magnets3in the cavity23in the base2are evenly distributed in the cavity23in the base2in circumferential direction, and the cross section of the core block31ain each source magnet3, parallel with the outer surface of the leakage type magnetic conductive coverplate4, is trapezoidal. More specifically, the number of several source magnets3is set to eight, but not limited to eight, and any two of the several source magnets3have a partition wall24in between. The partition wall24extends from the inner surface of the bottom21of the base2to the inner surface, which faces the bottom21, of the leakage type magnetic conductive coverplate4. More specifically, the partition wall24is also made of magnetic conductive material, and is integrated with the bottom21. One of ordinary skill in the art should understand that the structure of the leakage type magnetic holding device is not limited to enumeration in this embodiment, there are also other structures to be included with the same functions, for instance, the cross section of the core block31ain the source magnet3of the leakage type magnetic holding device1, parallel with the outer surface of the leakage type magnetic conductive coverplate4, may also be triangular.

As shown inFIGS.7ato7c, instantaneous forward current runs through the field coil32, all reversible magnets31bare excited in forward direction, exhibiting polarities N-S from top to bottom, thus magnetic circuits as shown inFIG.7aare formed among the workpiece5, the side wall4, the lower base2, the leakage type magnetic conductive coverplate4, the reversible magnet31band the core block31a, and among the workpiece5, the core block31a, the reversible magnet31b, the leakage type magnetic conductive coverplate4, the lower base2and the partition wall24, and among the workpiece5, the side wall22, the leakage type magnetic conductive coverplate4, the irreversible magnet33and the core block31a, and among the workpiece5, the partition wall24, the leakage type magnetic conductive coverplate4, the irreversible magnet33and the core block31a. In this way, the leakage type magnetic holding device1shows magnetism externally, holding the workpiece5to be processed onto the outer surface of the leakage type magnetic conductive coverplate4.

As shown inFIG.7d, in the case that holding needs to be released, instantaneous reverse current runs through the field coil32, all reversible magnets31bare excited in reverse direction, exhibiting polarities S-N from top to bottom, thus magnetic short-circuits as shown inFIG.7dare formed among the side wall22, the lower base2, the reversible magnet31b, the core block31a, and the irreversible magnet33, and among the core block31a, the reversible magnet31b, the lower base2, the partition wall24, and the irreversible magnet33. In this way, the leakage type magnetic holding device1does not show magnetism externally, holding of the workpiece5on the outer surface of the leakage type magnetic conductive coverplate4is released.

FIG.8ashows the section view of the leakage type magnetic holding device1based on the eighth embodiment of the present disclosure under excitation condition;FIG.8bis the partially enlarged view ofFIG.8a;FIG.8cshows the top view of the leakage type magnetic holding device1based on the eighth embodiment of the present disclosure under excitation condition;FIG.8dis the section view of the leakage type magnetic holding device1based on the eighth embodiment of the present disclosure under demagnetization condition;FIG.8eis the top view of the leakage type magnetic holding device1of the eighth embodiment of the present disclosure under demagnetization condition. In the appended drawings used in this embodiment, the same definitions are followed for the reference numbers identical with those in the above embodiments.

The eighth embodiment is a variation of the fourth embodiment. As shown inFIGS.8ato8c, the difference between the leakage type magnetic holding device1of the eighth embodiment and that of the fourth embodiment lies in that the leakage type magnetic holding device1in the eighth embodiment is a leakage type electromagnetic holding device, i.e., source magnets3in the eighth embodiment do not have reversible magnet31b, and each source magnet3contains an iron core31c, which faces the interior of cavity23from the inner surface of the bottom21of the base2, and is perpendicular to the inner surface of the bottom21and extends to the inner surface of the leakage type magnetic conductive coverplate4, and the field coil32set around corresponding iron core31cone-to-one. That is, in the eighth embodiment, the source magnets3do not have reversible magnet31b, and the field coil32is set around the circumference of the iron core31c. When direct current runs through the field coil32continuously, magnetic flux is produced in the iron core31cto form a magnetic circuit, as shown inFIG.8a, so that the holding device shows magnetism externally. When current stops flow in the field coil32, magnetic flux disappears in the iron core31c, so that the holding device does not show magnetism externally.

FIG.9ashows the section view of the leakage type magnetic holding device1based on the ninth embodiment of the present disclosure under excitation condition;FIG.9bis the partially enlarged view ofFIG.9a;FIG.9cshows the top view of the leakage type magnetic holding device1based on the ninth embodiment of the present disclosure under excitation condition;FIG.9dis the section view of the leakage type magnetic holding device1based on the ninth embodiment of the present disclosure under demagnetization condition;FIG.9eis the top view of the leakage type magnetic holding device1of the ninth embodiment of the present disclosure under demagnetization condition. In the appended drawings used in this embodiment, the same definitions are followed for the reference numbers identical with those in the above embodiments.

The ninth embodiment is a variation of the sixth embodiment. As shown inFIGS.9ato9d, the difference between the leakage type magnetic holding device1of the ninth embodiment and that of the sixth embodiment lies in that the leakage type magnetic holding device1in the ninth embodiment is a leakage type electromagnetic holding device, i.e., source magnets3in the ninth embodiment do not have the reversible magnet31b, and each source magnet3contains an iron core31c, which faces the interior of cavity23from the inner surface of the bottom21of the base2, and is perpendicular to the inner surface of the bottom21and extends to the inner surface of the leakage type magnetic conductive coverplate4, and the field coil32set around corresponding iron core31c, one-to-one. That is, in the ninth embodiment, source magnets3do not have reversible magnet31b, and the field coil32is set around the circumference of the iron core31c. When direct current runs through the field coil32continuously, magnetic flux is produced in the iron core31cto form a magnetic circuit, as shown inFIG.9a, so that the holding device shows magnetism externally. When current stops flow in the field coil32, magnetic flux disappears in the iron core31c, so that the holding device does not show magnetism externally.

In conclusion, the leakage type magnetic conductive coverplate and the leakage type magnetic holding device provided by the present utility model make use of the leakage type magnetic conductive coverplate to cover the holding surface of the holding device, so that the surface in contact with workpiece on the holding device is made of one material. This avoids crevices produced due to different coefficients of expansion and contraction when there is any change in ambient temperature, and coolant and other magnetic conductive substances will not infiltrate into the holding device, thus prolonging service life of the holding device, therefore, it has high value for marketing. The above-described embodiments exemplify the principles and functions of the present utility model only, and are not used to restrict the present disclosure. On the premise of not going against the spirit and scope of the present disclosure, anyone familiar with the technology can make modifications or changes of the above-described embodiments. Therefore, all the equivalent modifications or changes made by the persons, who have common knowledge in this technical field, without disaffiliating from the spirit and technical thought revealed in the present utility model should still be covered in the scope claimed for protection of the present utility model.