Permanent magnet induction heating method for aluminum bar for aluminum alloy profile extrusion

Abstract

The invention relates to an aluminum bar permanent magnetic induction heating method for extruding an aluminum alloy profile, which mainly solves the problem of poor heating uniformity of an aluminum bar heated by electromagnetic induction in the prior art, and comprises the following steps of: a, placing the aluminum bar on a conveying mechanism for conveying, pushing the aluminum bar into a conveying channel of a heating mechanism through a pushing mechanism, and heating the aluminum bar in the conveying channel; the aluminum bar is arranged in a composite magnetic field generated by the permanent magnet assembly; b, a gradient magnetic field is formed through alternate arrangement of permanent magnet polarities of the permanent magnet assembly, meanwhile, the electromagnet generates a high-frequency alternating magnetic field through alternating current, eddy current is excited on the surface of the aluminum bar through the magnetic field coupling effect, conduction type heating from outside to inside is achieved, and the electromagnet is independently controlled through a sub-power source of the power source system; local magnetic field compensation is realized through independent current control, and the compensation range is + / -0.3 T; c, the temperature of the aluminum bar is detected through an infrared temperature sensor and fed back to a control system, and the distance between the permanent magnet unit and the aluminum bar is dynamically adjusted.

Description

Technical Field

[0001] The invention relates to a permanent magnetic induction heating method for an aluminum rod used for extruding aluminum alloy profiles. Background Art

[0002] Aluminum rod is a kind of aluminum product. Before the aluminum rod is extruded into aluminum profiles, it needs to be heated, usually in a heating furnace with a resistance heating rod. However, the existing aluminum rod heating furnace has a complex structure, is inconvenient to operate, and has poor heating and insulation effects.

[0003] With the improvement of technology, electromagnetic induction heating technology is widely used in the field of metal smelting due to its advantages of high heating rate. Therefore, electromagnetic induction heating furnaces gradually replace heating furnaces with resistance heating rods. Induction heating uses electromagnetic induction to generate current inside the heated material, relying on the energy of these eddy currents to achieve the purpose of heating. The basic components of the induction heating system include an induction coil, an AC power supply, and a workpiece. Depending on the heating object, the coil can be made into different shapes. The coil is connected to a power supply, which provides an alternating current to the coil. The alternating current flowing through the coil generates an alternating magnetic field passing through the workpiece, which causes the workpiece to generate eddy currents for heating.

[0004] However, currently electromagnetic induction heating is mainly medium and high frequency AC induction heating, which uses the principle of electromagnetic induction to generate induced current in the aluminum rod for heating. However, medium and high frequencies have obvious skin effect and low heat penetration depth. The induced eddy currents are mainly concentrated in the outer layer of the metal. For aluminum rods with larger diameters, the skin effect will be more obvious, resulting in poor heating uniformity. Summary of the invention

[0005] Therefore, in view of the above problems, the present invention provides a permanent magnet induction heating method for aluminum bars used for aluminum alloy profile extrusion, which mainly solves the problem of poor heating uniformity of aluminum bars heated by electromagnetic induction in the prior art.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A permanent magnetic induction heating method for an aluminum rod for extrusion of an aluminum alloy profile comprises the following steps:

[0008] a. The aluminum rod is placed on the conveying mechanism for transportation, and then the pushing mechanism pushes the aluminum rod into the conveying channel of the heating mechanism, so that the aluminum rod is placed in the composite magnetic field generated by the permanent magnet assembly;

[0009] b. The permanent magnets of the permanent magnet assembly are arranged alternately to form a gradient magnetic field. At the same time, the electromagnet generates a high-frequency alternating magnetic field through an alternating current, and uses the magnetic field coupling effect to excite eddy currents on the surface of the aluminum rod to achieve conductive heating from the outside to the inside. The electromagnet is independently controlled by the sub-power supply of the power system, and local magnetic field compensation is achieved through independent current control, with a compensation range of ±0.3T.

[0010] c. The temperature of the aluminum rod is detected by an infrared temperature sensor and fed back to the control system to dynamically adjust the distance between the permanent magnet unit and the aluminum rod.

[0011] Furthermore, the magnetic field strength of the composite magnetic field is 0.5-2T.

[0012] Furthermore, the frequency of the alternating current can be adjusted in the range of 1 to 20 kHz, and the power density can be controlled in the range of 50 to 200 W / cm 2 .

[0013] Furthermore, the adjustment distance between the permanent magnet unit and the aluminum rod is 0.5-5 mm, the diameter of the aluminum rod is defined as D, and the distance between the permanent magnet unit and the aluminum rod is d, where d=0.02D+0.5 mm.

[0014] Furthermore, the heating mechanism has a conveying channel for the conveying mechanism to pass through, the heating mechanism includes a shell and at least three permanent magnet assemblies, each of the permanent magnet assemblies has a through hole at the central axis, the permanent magnet assemblies are distributed in sequence along the longitudinal direction, the central axis of the through hole of each permanent magnet assembly coincides with the central axis of the conveying channel, each permanent magnet assembly includes 6 to 8 permanent magnet units distributed in a ring array, an electromagnet is embedded between two adjacent permanent magnet units on the same permanent magnet assembly, the power supply system includes a main power supply and multiple sub-power supplies, and each sub-power supply is electrically connected to each electromagnet respectively.

[0015] Furthermore, each of the permanent magnet units includes a plurality of permanent magnets with an arc-shaped structure, and each of the permanent magnets is arranged in sequence along the radial direction of the conveying channel, and the distance between adjacent permanent magnets located on the same permanent magnet unit gradually increases from the inner layer to the outer layer.

[0016] Furthermore, the permanent magnet is a neodymium iron boron magnet.

[0017] Furthermore, each of the electromagnets is respectively connected to a first linear drive assembly for driving the electromagnet to move along the radial direction of the conveying channel, and each of the first linear drive assemblies is respectively electrically connected to a control system.

[0018] Furthermore, the permanent magnet units on each of the permanent magnet assemblies and located on a straight line parallel to the central axis of the conveying channel are connected via a connecting frame, and a second linear drive assembly is connected to the connecting frame for synchronously driving the permanent magnet units located on a straight line parallel to the central axis of the conveying channel to move synchronously in the radial direction of the conveying channel, and each of the second linear drive assemblies is electrically connected to the control system respectively.

[0019] By adopting the above technical scheme, the beneficial effects of the present invention are as follows: the permanent magnet induction heating method for aluminum rods for extrusion of aluminum alloy profiles combines the gradient magnetic field formed by the alternating polarity arrangement of the permanent magnets of the permanent magnet assembly with the high-frequency alternating magnetic field generated by the alternating current to generate high-density eddy currents on the surface of the aluminum rods, achieving efficient, uniform and rapid heating, that is, arranging multiple groups of permanent magnet units circumferentially on the aluminum rods, and forming a controllable rotating magnetic field by adjusting the polarity distribution of the permanent magnets and the frequency of the alternating current; combining the temperature feedback system to dynamically optimize the magnetic field parameters to ensure the consistency of the axial and radial temperatures of the aluminum rods. Compared with traditional resistance / gas heating, this heating method reduces energy consumption by more than 30%, increases the heating rate by 2 to 3 times, and has no pollution emissions, and is suitable for high-precision extrusion forming processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of a top view of the structure of an embodiment of the present invention;

[0021] Figure 2 is a schematic cross-sectional structural diagram of a heating mechanism in an embodiment of the present invention;

[0022] Figure 3 1 is a schematic diagram of the right side structure of the permanent magnet assembly in an embodiment of the present invention;

[0023] Figure 4 2 is a schematic diagram of the magnetization direction structure of the permanent magnet unit in an embodiment of the present invention;

[0024] Figure 5 is a schematic cross-sectional structural diagram of a support assembly in an embodiment of the present invention;

[0025] Figure 6 is a schematic diagram of the electrical connection structure between the power supply system and the electromagnet in an embodiment of the present invention;

[0026] Figure 7 It is a circuit module diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0028] The embodiments of the present invention are:

[0029] refer to Figures 1 to 7 As shown, a permanent magnetic induction heating method for aluminum bars for aluminum alloy profile extrusion comprises the following steps:

[0030] a. The aluminum rod is placed on the conveying mechanism 3 for conveying, and then pushed into the conveying channel 51 of the heating mechanism 5 by the pushing mechanism 4, so that the aluminum rod is placed in the composite magnetic field generated by the permanent magnet assembly 53, and the magnetic field strength of the composite magnetic field is 0.5-2T, preferably 1.8T;

[0031] b. The permanent magnets 6 of the permanent magnet assembly 53 are arranged alternately to form a gradient magnetic field. At the same time, the electromagnet 55 generates a high-frequency alternating magnetic field through an alternating current, and uses the magnetic field coupling effect to excite eddy currents on the surface of the aluminum rod to achieve conductive heating from the outside to the inside. The adjustable range of the alternating current frequency is 1 to 20 kHz, and the power density is controlled to be 50-200 W / cm 2 , and the electromagnet 55 is independently controlled by the sub-power supply 12 of the power supply system 1, and local magnetic field compensation is achieved by independent current control, and the compensation range is ±0.3T;

[0032] c. The temperature of the aluminum rod is detected by the infrared temperature sensor 10, and the temperature is fed back to the control system 2 to dynamically adjust the distance between the permanent magnet unit 100 and the aluminum rod. The adjustment distance between the permanent magnet unit 100 and the aluminum rod is 0.5-5 mm. The diameter of the aluminum rod is defined as D, and the distance between the permanent magnet unit and the aluminum rod is d, d=0.02D+0.5 mm, to ensure that the magnetic field penetration depth matches the diameter of the aluminum rod. When the temperature difference ΔT>5°C, the distance between the permanent magnet units 100 corresponding to the low temperature area is increased to reduce the local heating rate. When the overall heating rate is insufficient, the alternating current frequency is increased to 15-20 kHz, so that the skin depth is reduced and the surface eddy current density is increased.

[0033] The above heating method combines the gradient magnetic field formed by the alternating polarity arrangement of the permanent magnets 6 of the permanent magnet assembly 53 with the high-frequency alternating magnetic field generated by the alternating current to generate high-density eddy currents on the surface of the aluminum rod, thereby achieving efficient, uniform and rapid heating. That is, multiple groups of permanent magnet units 100 are arranged circumferentially on the aluminum rod, and a controllable rotating magnetic field is formed by adjusting the polarity distribution of the permanent magnets 6 and the frequency of the alternating current; the magnetic field parameters are dynamically optimized in combination with the temperature feedback system to ensure the consistency of the axial and radial temperatures of the aluminum rod. Compared with traditional resistance / gas heating, this heating method reduces energy consumption by more than 30%, increases the heating rate by 2 to 3 times, and has no pollution emissions, and is suitable for high-precision extrusion forming processes.

[0034] A permanent magnetic induction heating device for aluminum bars for aluminum alloy profile extrusion, comprising a frame, a power supply system 1, a control system 2, a conveying mechanism 3, a material pushing mechanism 4 and a heating mechanism 5, wherein the conveying mechanism 3 is arranged on the frame and used for conveying the aluminum bars, and the conveying direction extending along the conveying mechanism 3 is defined as the longitudinal direction, and the width direction extending along the conveying mechanism 3 is defined as the transverse direction;

[0035] The heating mechanism 5 is arranged on the frame, and has a conveying channel 51 for the conveying mechanism 3 to pass through. The heating mechanism 5 includes a shell 52 and three permanent magnet components 53. Each permanent magnet component 53 has a through hole 54 at the central axis. Each permanent magnet component 53 is sequentially distributed along the longitudinal direction. The central axis of the through hole 54 of each permanent magnet component 53 coincides with the central axis of the conveying channel 51. Each permanent magnet component 53 includes 6 to 8 permanent magnet units 100 distributed in a ring array, preferably 8, and an electromagnet 55 is embedded between two adjacent permanent magnet units 100 on the same permanent magnet component 53.

[0036] The power supply system 1 includes a main power supply 11 and multiple sub-power supplies 12. Each sub-power supply 2 is electrically connected to each electromagnet 55. The pushing mechanism 4 is arranged on the frame and is used to push the aluminum rod into the conveying channel 51 or push it out of the conveying channel 51. The power supply system 1, the conveying mechanism 3, the pushing mechanism 4, and the heating mechanism 5 are electrically connected to the control system 2 respectively.

[0037] Furthermore, each of the permanent magnet units 100 includes a plurality of permanent magnets 6 with an arc-shaped structure, and each of the permanent magnets 6 is arranged in sequence along the radial direction of the conveying channel 51. The spacing between adjacent permanent magnets 6 on the same permanent magnet unit 100 gradually increases from the inner layer to the outer layer, and the permanent magnets 6 are neodymium iron boron magnets.

[0038] At the same time, each of the electromagnets 55 is respectively connected to a first linear drive component 7 for driving the electromagnet 5 to move in the radial direction of the conveying channel 51. Each of the first linear drive components 7 is respectively electrically connected to the control system 2, so as to adjust the distance between the electromagnet 55 and the aluminum rod to achieve local magnetic field compensation.

[0039] Furthermore, the permanent magnet units 100 on each of the permanent magnet assemblies 53 and located on a straight line parallel to the central axis of the conveying channel 51 are connected via a connecting frame 8, and a second linear drive assembly 9 is connected to the connecting frame 8 for synchronously driving the permanent magnet units 100 located on a straight line parallel to the central axis of the conveying channel 51 to move synchronously in the radial direction of the conveying channel 51. Each of the second linear drive assemblies 9 is electrically connected to the control system 2, respectively, to dynamically adjust the spacing between the permanent magnet unit 100 and the aluminum rod to ensure that the magnetic field penetration depth matches the diameter of the aluminum rod, thereby reducing the local heating rate.

[0040] In this embodiment, the permanent magnet assembly 53 includes 8 permanent magnet units 100 distributed in a ring array, which are the first permanent magnet unit 101, the second permanent magnet unit 102, the third permanent magnet unit 103, the fourth permanent magnet unit 104, the fifth permanent magnet unit 105, the sixth permanent magnet unit 106, the seventh permanent magnet unit 107 and the eighth permanent magnet unit 108 in the clockwise direction. The first permanent magnet unit 101 is magnetized radially outward, the second permanent magnet unit 102 is magnetized tangentially clockwise, the third permanent magnet unit 103 is magnetized tangentially clockwise, the fourth permanent magnet unit 104 is magnetized tangentially clockwise, the fifth permanent magnet unit 105 is magnetized radially inward, the sixth permanent magnet unit 106 is magnetized tangentially counterclockwise, the seventh permanent magnet unit 107 is magnetized tangentially counterclockwise, and the eighth permanent magnet unit 108 is magnetized tangentially counterclockwise. A gradient magnetic field is formed by the alternating arrangement of the permanent magnet units 100 of the permanent magnet assembly 53.

[0041] Furthermore, the conveying mechanism 3 includes a first roller conveying assembly 31, a second roller conveying assembly 32 and a support assembly 33. The first roller conveying assembly 31 and the second roller conveying assembly 32 are distributed at the longitudinal ends of the heating mechanism 5. The support assembly 33 is distributed in the conveying channel 51 and distributed along the longitudinal direction of the conveying channel 51. The support assembly 33 includes two support rails 331. The support rails 331 are provided with strip grooves 332. The strip grooves 332 are provided with balls 333. The strip grooves 332 are covered with upper pressure plates 334. The upper pressure plates 334 are provided with through grooves 335 protruding from the upper parts of the balls 333 at intervals, thereby improving the stability of aluminum rod conveying.

[0042] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0043] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0045] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. A permanent magnetic induction heating method for aluminum bars for aluminum alloy profile extrusion, characterized in that: The following steps are involved: a. The aluminum rod is placed on the conveying mechanism for transportation, and then the pushing mechanism pushes the aluminum rod into the conveying channel of the heating mechanism, so that the aluminum rod is placed in the composite magnetic field generated by the permanent magnet assembly; b. The permanent magnets of the permanent magnet assembly are arranged alternately to form a gradient magnetic field. At the same time, the electromagnet generates a high-frequency alternating magnetic field through an alternating current, and uses the magnetic field coupling effect to excite eddy currents on the surface of the aluminum rod to achieve conductive heating from the outside to the inside. The electromagnet is independently controlled by the sub-power supply of the power system, and local magnetic field compensation is achieved through independent current control, with a compensation range of ±0.3T. c. The temperature of the aluminum rod is detected by an infrared temperature sensor and fed back to the control system to dynamically adjust the distance between the permanent magnet unit and the aluminum rod.

2. The method for permanent magnetic induction heating of an aluminum rod for extrusion of an aluminum alloy profile according to claim 1, characterized in that: The magnetic field strength of the composite magnetic field is 0.5-2T.

3. The method for permanent magnetic induction heating of aluminum bars for aluminum alloy profile extrusion according to claim 1, characterized in that: The adjustable range of the alternating current frequency is 1-20kHz, and the power density is controlled to be 50-200W / cm 2 .

4. The method for permanent magnetic induction heating of an aluminum rod for extrusion of an aluminum alloy profile according to claim 1, characterized in that: The adjustment distance between the permanent magnet unit and the aluminum rod is 0.5-5 mm, the diameter of the aluminum rod is defined as D, and the distance between the permanent magnet unit and the aluminum rod is d, where d=0.02D+0.5 mm.

5. The method for permanent magnetic induction heating of an aluminum bar for extrusion of an aluminum alloy profile according to any one of claims 1 to 4, characterized in that: The heating mechanism is provided with a conveying channel for the conveying mechanism to pass through. The heating mechanism includes a shell and at least three permanent magnet assemblies. Each of the permanent magnet assemblies has a through hole at the central axis. The permanent magnet assemblies are distributed in sequence along the longitudinal direction. The central axis of the through hole of each permanent magnet assembly coincides with the central axis of the conveying channel. Each permanent magnet assembly includes 6 to 8 permanent magnet units distributed in a ring array. An electromagnet is embedded between two adjacent permanent magnet units on the same permanent magnet assembly. The power supply system includes a main power supply and multiple sub-power supplies. Each of the sub-power supplies is electrically connected to each electromagnet respectively.

6. The method for permanent magnetic induction heating of an aluminum rod for extrusion of an aluminum alloy profile according to claim 5, characterized in that: Each of the permanent magnet units includes a plurality of permanent magnets in an arc-shaped structure. Each of the permanent magnets is arranged in sequence along the radial direction of the conveying channel. The distance between adjacent permanent magnets on the same permanent magnet unit gradually increases from the inner layer to the outer layer.

7. The method for permanent magnetic induction heating of an aluminum rod for extrusion of an aluminum alloy profile according to claim 6, characterized in that: The permanent magnet is a neodymium iron boron magnet.

8. The method for permanent magnetic induction heating of an aluminum rod for extrusion of an aluminum alloy profile according to claim 7, characterized in that: Each of the electromagnets is respectively connected to a first linear drive assembly for driving the electromagnet to move along the radial direction of the conveying channel, and each of the first linear drive assemblies is respectively electrically connected to a control system.

9. The method for permanent magnetic induction heating of an aluminum rod for extrusion of an aluminum alloy profile according to claim 8, characterized in that: The permanent magnet units on each of the permanent magnet assemblies and located on a straight line parallel to the central axis of the conveying channel are connected via a connecting frame, and a second linear drive assembly is connected to the connecting frame for synchronously driving the permanent magnet units located on a straight line parallel to the central axis of the conveying channel to move synchronously in the radial direction of the conveying channel, and each of the second linear drive assemblies is electrically connected to the control system respectively.

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