A strong magnetic field application device for heat treatment

Abstract

The application discloses a strong magnetic field action device for heat treatment and relates to the technical field of metal heat treatment. The device comprises a shell, a magnetic field generating mechanism, an inner container, a coil support and a cooling mechanism. The shell is in a cylindrical structure, and the inner container is vertically arranged in the interior of the shell. The magnetic field generating mechanism comprises a coil unit and a power supply. The coil unit is arranged between the inner container and the shell and comprises four groups of coils arranged in sequence along the axial direction of the inner container. The two groups of coils arranged at the top are symmetrically arranged above and below, and the two groups of coils arranged at the bottom are symmetrically arranged above and below. The coil comprises a plurality of coils stacked in sequence from top to bottom. The coil is a sheet-shaped copper wire wound by double glass filaments. The coils of the same height in each group of coils are connected to the power supply in sequence after being connected in series, and the coils in the same group are connected in parallel. The winding direction and the current direction of each coil are the same. The application can improve the hardness and other mechanical properties of the heat-treated workpiece, reduce the number of heat treatment tempering, and improve the production capacity and efficiency.

Description

Technical Field

[0001] This invention relates to the field of metal heat treatment technology, and more specifically to a strong magnetic field device for heat treatment. Background Technology

[0002] Magnetic field heat treatment is an emerging field of heat treatment. It refers to the heat treatment method used to improve the mechanical properties of various metallic materials under the influence of a magnetic field. Magnetic field heat treatment can be applied to various structural steels, tool steels, stainless steels, etc.

[0003] Magnetic field heat treatment refers to a heat treatment process in which a material is held at a temperature near the Curie temperature in a magnetic field for a certain period of time and then cooled, or cooled in a magnetic field at a certain rate. Through magnetic field heat treatment, magnetic ions or ion pairs in an alloy can often be made to exhibit oriented order, thereby inducing so-called anisotropy. This transforms the original magnetic domain structures in the material, which had different easy magnetization directions, into easily magnetized magnetic domain structures with directions roughly parallel to the magnetic field orientation.

[0004] Magnetic field hardening essentially utilizes an external magnetic field to deform the austenite lattice (i.e., lattice distortion), forming dislocation cells, refining martensite, increasing dislocation density, and improving mechanical properties. This is similar to deformation heat treatment of steel. Although these are two different deformation methods, they produce the same microstructure—dislocation cells—strengthening the material. Magnetic field hardening has a more pronounced effect on improving the strength and toughness of the material, and a more significant increase in service life. Existing heat treatment cooling devices have excessively low magnetic field strength and often use pulsed magnetic fields, resulting in short actual durations, low efficiency, and limited improvement on the internal microstructure of the workpiece. After heat treatment, the workpiece exhibits long and coarse needle-like structures, with low hardness and wear resistance. Therefore, existing technology urgently needs further improvement and enhancement. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a strong magnetic field device for heat treatment, which solves the problems that the magnetic field strength of existing heat treatment cooling devices is too low and that most of them use pulsed magnetic fields, resulting in insufficient improvement of workpiece performance after heat treatment.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A strong magnetic field device for heat treatment includes a shell, a magnetic field generating mechanism, an inner liner, a coil support, and a cooling mechanism. The shell is a cylindrical structure with an open top, and the inner liner is vertically arranged inside the shell.

[0008] The magnetic field generating mechanism includes a coil unit and a power supply. The coil unit is set between the inner liner and the outer shell through the coil support. It includes 2n sets of coils arranged sequentially along the axial direction of the inner liner, where n is a natural number greater than zero.

[0009] Each group of coils consists of multiple coils stacked sequentially from top to bottom. The coils are ring-shaped structures made of double glass wire copper wire. Coils of the same height in each group are connected in series and then connected to the power supply. The coils in the same group are connected in parallel.

[0010] The winding direction and current direction of each coil are the same.

[0011] Furthermore, the outer shell includes a top plate, an annular side plate, and a bottom plate. The annular side plate is arranged vertically, and the top plate and the bottom plate are fixedly connected to the upper and lower ends of the annular side plate to form a whole.

[0012] Both the top plate and the bottom plate are made of stainless steel or aluminum alloy with low magnetic permeability. The top plate has a feed inlet in the center, and the bottom plate closes the bottom of the annular side plate.

[0013] Furthermore, the outer shell includes a top plate, an annular side plate, and a bottom plate. The annular side plate is arranged vertically, and the top plate and the bottom plate are fixedly connected to the upper and lower ends of the annular side plate to form a whole.

[0014] Both the top plate and the bottom plate are made of stainless steel or aluminum alloy with low magnetic permeability. The top plate has a feed inlet in the center, and the bottom plate has a discharge outlet in the center, which is directly opposite the feed inlet.

[0015] Furthermore, the inner liner is a copper cylindrical structure, arranged coaxially with the annular side plate.

[0016] The inner liner is fixedly connected to the top and bottom plates at its upper and lower ends, respectively, and its inner wall is provided with an asbestos insulation layer with a thickness of ≥5mm.

[0017] Furthermore, the coil has four sets, with the two sets of coils at the top arranged symmetrically, and the two sets of coils at the bottom also arranged symmetrically.

[0018] The number of turns of each coil in the same group increases or decreases sequentially along the axial direction of the inner liner, and the thickness of each coil is equal to the width of the double glass wire copper wire.

[0019] Furthermore, the magnetic field generating mechanism also includes a first terminal block and a second terminal block, which are respectively fixedly mounted on the outer casing.

[0020] The current input terminals of each coil in the topmost group are electrically connected to the first terminal block, and the current output terminals of each coil in the bottommost group are connected to the second terminal block.

[0021] The first and second terminal blocks are electrically connected to the two terminals of the power supply, respectively.

[0022] Furthermore, the coil support includes an upper fixing plate, a lower fixing plate, and multiple screws. The upper fixing plate and the lower fixing plate are respectively horizontally arranged above and below the coil unit and are sleeved on the outside of the inner liner.

[0023] The lower fixing plate is detachably and fixedly connected to the inner liner. Multiple screws are evenly arranged in a ring on the outside of the coil unit. The upper fixing plate is fixedly connected to the lower fixing plate through the screws.

[0024] Furthermore, for all coils, two adjacent coils are considered as a pair of coils, and a mesh spacer for heat dissipation is provided between any two adjacent pairs of coils.

[0025] Furthermore, the cooling mechanism includes multiple axial flow fans, which are evenly arranged in a ring on the top plate and located outside the feed inlet.

[0026] The base plate has multiple air outlets, which are evenly arranged in a ring around the outer perimeter of the inner liner.

[0027] By adopting the above technical solution, the beneficial technical effects of the present invention are as follows:

[0028] 1. Compared with traditional heat treatment processes, the heat treatment process using this device can improve the hardness and other mechanical properties of the heat-treated workpiece.

[0029] 2. Using this device in the heat treatment and tempering process of some workpieces can effectively reduce the number of heat treatment and tempering cycles, thereby improving production capacity and efficiency.

[0030] 3. After multiple simulation optimizations and actual experiments, each group of coils is made up of multiple coils stacked into a frustum shape. The adjacent groups of coils are arranged symmetrically from top to bottom, which can greatly reduce the impact of current reduction caused by mutual inductance between coils, provide a high-intensity alternating magnetic field, and consume little energy.

[0031] 4. The ampere-turns ratio (A / N) obtained through multiple simulations and practical tests was selected, and the optimal configuration of power and magnetic field strength was chosen to avoid excessive energy waste.

[0032] 5. By selecting the frequency, the coil impedance is reduced, which reduces the heat generated by eddy currents on the metal surface, enabling a larger current and resulting in a stronger magnetic field. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the first embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram of the structure of the second embodiment of the present invention.

[0035] Figure 3This is a schematic diagram of the circuit connections of each group of coils in this invention.

[0036] Figure 4 This is a structural schematic diagram of a certain part of the present invention, showing the inner liner and the asbestos insulation layer.

[0037] Figure 5 It is a scanning electron microscope image after ordinary heat treatment quenching and tempering.

[0038] Figure 6 This is a scanning electron microscope image after 0.2T quenching under alternating magnetic field heat treatment followed by ordinary heat treatment and tempering.

[0039] Figure 7 This is a scanning electron microscope (SEM) image after quenching under alternating magnetic field heat treatment at 0.2T and tempering under alternating magnetic field heat treatment at 0.2T.

[0040] Figure 8 These are microscopic images of the product after ordinary heat treatment and quenching.

[0041] Figure 9 These are microscopic images of a 0.1T quenched product subjected to alternating magnetic field heat treatment.

[0042] Figure 10 This is a friction and wear diagram of the workpiece under the usage state of the present invention.

[0043] Figure 11 This is a Rockwell hardness diagram of the workpiece under the condition of use according to the present invention. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings:

[0045] Example 1, combined with Figure 1 , Figure 3 and Figure 4 A strong magnetic field device for heat treatment includes a shell 1, a magnetic field generating mechanism, an inner liner 2, a coil support, and a cooling mechanism. The shell 1 is a cylindrical structure with an open top, and its cross-section along its axial direction is circular or polygonal. The shell 1 includes a top plate 11, an annular side plate 12, and a bottom plate 13. The annular side plate 12 is arranged vertically, and the top plate 11 and the bottom plate 13 are fixedly connected to the upper and lower ends of the annular side plate 12, respectively. Both the top plate 11 and the bottom plate 13 are made of stainless steel or aluminum alloy with low magnetic permeability. The top plate 11 has a feed inlet 14 at its center, and the bottom plate 13 has a discharge outlet 15 at its center, directly opposite the feed inlet 14.

[0046] The inner liner 2 is vertically arranged inside the outer shell 1. Specifically, the inner liner 2 is a copper cylindrical structure with a thickness of 5mm, and is arranged coaxially with the annular side plate 12. The upper and lower ends of the inner liner 2 are fixedly and sealed to the top plate 11 and the bottom plate 13, respectively. An asbestos insulation layer 21 with a thickness of 5mm is provided on its inner side wall.

[0047] Both the inlet 14 and the outlet 15 are connected to the interior of the inner liner 2. During use, the heated workpiece is hoisted into the inner liner 2 through the inlet 14, where it can cool naturally. Simultaneously, a fan can be used to blow air into the inlet 14 to cool the heated workpiece.

[0048] The magnetic field generating mechanism includes a coil unit 3 and a power supply. The coil unit 3 is set between the inner liner 2 and the outer shell 1 through the coil support. It includes four sets of coils arranged sequentially along the axial direction of the inner liner 2. The two sets of coils located at the top are arranged symmetrically from top to bottom, and the two sets of coils located at the bottom are arranged symmetrically from top to bottom.

[0049] Each coil group comprises multiple coils stacked sequentially from top to bottom. The coils are ring-shaped structures wound with double glass-fiber copper wire. Coils of the same height position within each group are connected in series, while coils within the same group are connected in parallel. The winding direction and current direction of each coil are the same. Each coil in the same group is fitted onto the outside of the inner liner 2, with the number of turns increasing or decreasing sequentially along the axial direction of the inner liner. The double glass-fiber copper wire has a diameter of 3*10mm, and the thickness of each coil is equal to the width of the double glass-fiber copper wire.

[0050] Specifically, this embodiment uses 60 layers of coils, stacked in a trapezoidal structure. Each layer has 30-44 turns, and the 60 layers are divided into four groups, each group containing 15 layers. The outer surface of each group is a conical frustum structure, with a fixed inner diameter along its axial direction. Combined with... Figure 3 As shown, coils of the same height in each group are connected in series, and coils in the same group are connected in parallel to the power supply to ensure that the coil winding direction and current winding direction are the same. Due to the dense connection of the wires, Figure 3 Only the connection method of the top and bottom coils in each group of coils is shown.

[0051] The specific coil arrangement is as follows: from bottom to top: 44-43-42-……-30, 30-31-32-……-44, 44-43-42-……-30, 30-31-32-……-44. Each group of coils adopts a conical structure arrangement, and the two adjacent groups of coils above and below adopt a symmetrical structure. The purpose of this is to reduce the impedance under energized conditions.

[0052] For all coils, two adjacent coils are considered as a pair of coils. A mesh spacer for heat dissipation is provided between any two adjacent pairs of coils. The same mesh spacer is provided between the uppermost coil and the upper fixed plate 61 and between the lowermost coil and the lower fixed plate 62. The mesh spacer is 5mm thick and its function is to improve the heat dissipation capacity of the double glass wire copper wire.

[0053] The magnetic field generating mechanism also includes a first terminal block 51 and a second terminal block 52, which are fixedly mounted on the outer casing 1. Coils of the same height in each group are connected in series, and coils within the same group are connected in parallel. The current input terminals of all coils in the uppermost group are electrically connected to the first terminal block, and the current output terminals of all coils in the lowermost group are connected to the second terminal block. The first terminal block 51 and the second terminal block 52 are electrically connected to terminals A and B of the power supply, respectively. The power supply uses sinusoidal alternating current, enabling constant current and constant voltage output, with an adjustable frequency of 0-2000Hz, a maximum voltage of 600V, and a maximum current of 4000A. Different current and voltage parameters are selected according to the required magnetic field strength.

[0054] This invention employs a constant current mode because current is positively correlated with magnetic field strength. Under energized conditions, a magnetic field strength of 0-0.8T can be generated inside the coil.

[0055] The coil support includes an upper fixing plate 61, a lower fixing plate 62, and four screws 63. Both the upper fixing plate 61 and the lower fixing plate 62 have a perforated structure for easy heat dissipation and are horizontally positioned above and below the coil unit, respectively. Both the upper fixing plate 61 and the lower fixing plate 62 are fitted onto the outer side of the inner liner 2. The lower fixing plate 62 is detachably and fixedly connected to the inner liner 2. The four screws 63 are evenly arranged in a ring on the outer side of the coil unit, and the upper fixing plate 61 is fixedly connected to the lower fixing plate 62 via the screws 63.

[0056] The cooling mechanism includes multiple axial flow fans 7, which are evenly arranged in a ring on the top plate 11 and located outside the feed inlet 14. Multiple air outlets 16 are provided on the bottom plate 13, which are evenly arranged in a ring around the feed inlet 14. In operation, the axial flow fans 7 are turned on, allowing external air to enter the annular side plate 12 and inner liner 2 from above and exit through the air outlets 16 on the bottom plate 13, thus carrying away the heat generated by the double glass fiber copper wire and improving its heat dissipation effect.

[0057] Because the coil generates heat during operation, and the workpiece enters the equipment at a high temperature, a cooling device is needed to cool both the equipment and the workpiece. Two methods can be used: water mist spray cooling or high-pressure air cooling. The cooling device is located above the coil, blowing water mist or high-pressure air from top to bottom for cooling. This embodiment only lists high-pressure air cooling; water mist spray cooling can be achieved using existing technology.

[0058] Example 2, combined with Figures 2 to 4The structure of the strong magnetic field device for heat treatment disclosed in Embodiment 2 is largely the same as that of the strong magnetic field generating mechanism for heat treatment disclosed in Embodiment 1, except that the structure of the outer shell 1 is different. Embodiment 2 has a top plate 11, annular side plate 12, and bottom plate 13. The annular side plate 12 is arranged vertically, and the top plate 11 and bottom plate 13 are fixedly connected to the upper and lower ends of the annular side plate 12, respectively, forming a single unit. Both the top plate 11 and bottom plate 13 are made of stainless steel or aluminum alloy with low magnetic permeability. A feed inlet 14 is provided in the center of the top plate 11. The bottom plate 13 seals the bottom of the annular side plate 12. Simultaneously, the bottom plate 13 is fixedly and sealed to the lower end of the inner liner 2, also sealing the bottom of the inner liner 2. According to the requirements of heat treatment, quenching liquid can be poured into the inner liner 2, and the high-temperature workpiece can be placed into the quenching liquid through the feed inlet 14 for cooling. Simultaneously, the cooling process is completed under the action of the magnetic field. After the workpiece heat treatment is completed, it is removed from the feed inlet 14.

[0059] Example 3, combined with Figures 1 to 11 The specific usage of the strong magnetic field device for heat treatment disclosed in this embodiment is as follows:

[0060] Based on the material properties of the workpiece and its intended use, pre-set the required current value and frequency for the equipment.

[0061] Place the workpiece, whose temperature is near the Curie temperature, into the inner chamber of the equipment and center it.

[0062] Start the equipment and input the set current to the coil through the power supply. The current generates a magnetic field after passing through the coil. The magnetic field acts on the workpiece to strengthen it.

[0063] If the workpiece needs to be cooled from high temperature to room temperature by air cooling, then high-pressure air should be turned on for cooling. If rapid cooling is required, then water mist should be sprayed for cooling.

[0064] Taking high-chromium cast iron workpieces as an example:

[0065] S1, perform preliminary rough machining on test workpieces A1, A2, and SC;

[0066] S2, heat-treat and quench workpiece A1:

[0067] Heated to 1050℃ and held for 120 minutes, then placed inside the equipment for water mist cooling and an alternating magnetic field of 0.5T.

[0068] Workpiece A2 is subjected to heat treatment quenching: heated to 1050℃, held for 120 minutes, and then placed in the equipment for water mist spray cooling and an alternating magnetic field of +0.5T.

[0069] The control sample SC was subjected to heat treatment quenching: heated to 1050℃, held for 120 min, and then quenched in water.

[0070] S3, perform heat treatment tempering on workpiece A1:

[0071] Heat to 520℃, hold for 180 minutes, then air cool to room temperature;

[0072] Workpiece A2 is subjected to heat treatment tempering: heated to 520℃, held for 180 min, and then a 0.5T alternating magnetic field is introduced into the device and cooled to room temperature.

[0073] Workpiece SC was subjected to heat treatment tempering: heated to 520℃, held for 180 min, and then air-cooled to room temperature. S3, A1, A2, and SC specimens were then subjected to subsequent finishing processes.

[0074] Wear and wear under different process conditions were measured on a friction and wear testing machine, and hardness values ​​under different process conditions were measured on a Rockwell tester.

[0075] (a) is a 2500x magnification scan electron microscope image of a typical heat treatment process involving quenching and tempering.

[0076] (b) is a scanning electron microscope image magnified 2500x after 0.2T quenching under alternating magnetic field heat treatment followed by conventional heat treatment and tempering.

[0077] (c) is a scanning electron microscope image magnified 2500x after 0.2T quenching followed by 0.2T tempering under alternating magnetic field heat treatment.

[0078] By comparing (a), (b) and (c), it can be seen that, through scanning electron microscopy, the internal structure of the workpiece becomes increasingly fine and uniform under the influence of an alternating magnetic field, with fine and oriented carbides.

[0079] Figure 8 Microscopic images after conventional heat treatment and quenching (5000x magnification using a scanning electron microscope); Figure 9 Microscopic images (5000x magnification using scanning electron microscopy) of a 0.1T quenched product subjected to alternating magnetic field heat treatment. From Figure 8 and Figure 9 It can be seen that the workpiece is more homogeneous after being subjected to a magnetic field. The oriented needle-like structures become shorter and finer, which is beneficial to the uniformity of the structure.

[0080] (d) The figure shows the friction and wear diagram. The test sample is placed on the friction and wear test machine. After the same time and the same distance of friction, the friction loss weight and wear rate are measured.

[0081] Figure 11 The Rockwell hardness chart is obtained by placing the sample on a Rockwell hardness tester and measuring its HRC hardness.

[0082] SC refers to products that have undergone ordinary heat treatment on the market.

[0083] A1 refers to samples made of the same material and with the same manufacturing process, but with the hardness measured by introducing a magnetic field during the quenching process.

[0084] A2 is a product made of the same material and with the same process. In this device, a magnetic field is applied to determine the hardness after quenching and tempering.

[0085] For any parts not mentioned in this invention, existing technologies can be used or referenced.

[0086] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0087] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0088] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A device for applying a strong magnetic field in heat treatment, characterized in that, The application relates to a magnetic field generating device, which comprises a shell, a magnetic field generating mechanism, an inner container, a coil support and a cooling mechanism. The magnetic field generating mechanism comprises a coil unit and a power supply, the coil unit is arranged between the inner container and the shell through the coil support, and the coil unit comprises 2n groups of coils arranged in sequence along the axial direction of the inner container, wherein n is a natural number greater than zero. Each group of coils comprises a plurality of coils stacked in sequence from top to bottom, the coils are annular sheet structures wound by double glass silk copper wires, the coils at the same height in each group are connected in sequence, and the coils in the same group are connected in parallel. The winding direction and current direction of each coil are the same. The coils are divided into four groups, the upper two groups of coils are arranged in an upper-lower symmetrical mode, and the lower two groups of coils are also arranged in an upper-lower symmetrical mode. The number of turns of the coils in the same group increases or decreases in sequence along the axial direction of the inner container, and the thickness of each coil is equal to the width of the double glass silk copper wire. The magnetic field generating mechanism further comprises a first wiring board and a second wiring board, and the first wiring board and the second wiring board are fixedly arranged on the shell. The current input ends of the coils in the uppermost group are electrically connected with the first wiring board, and the current output ends of the coils in the lowermost group are connected with the second wiring board. The first wiring board and the second wiring board are respectively electrically connected with the two wiring ends of the power supply.

2. A high magnetic field application apparatus for heat treatment according to claim 1, wherein The shell comprises a top plate, an annular side plate and a bottom plate, the annular side plate is vertically arranged, and the top plate and the bottom plate are fixedly connected with the upper and lower ends of the annular side plate to form an integral body. A feeding port is formed in the center of the top plate, and the bottom plate closes the bottom of the annular side plate.

3. The high magnetic field application apparatus for heat treatment according to claim 1, characterized by The shell comprises a top plate, an annular side plate and a bottom plate, the annular side plate is vertically arranged, and the top plate and the bottom plate are fixedly connected with the upper and lower ends of the annular side plate to form an integral body. A feeding port is formed in the center of the top plate, and the bottom plate closes the bottom of the annular side plate.

4. A high magnetic field application apparatus for heat treatment according to claim 2 or 3, characterized in that The inner container is a copper cylindrical structure coaxially arranged opposite to the annular side plate. The upper and lower ends of the inner container are fixedly connected with the top plate and the bottom plate respectively, a stone wool heat insulation layer is arranged on the inner side wall of the inner container, and the thickness of the stone wool heat insulation layer is greater than or equal to 5 mm.

5. The high magnetic field application apparatus for heat treatment according to claim 1, wherein The coil support comprises an upper fixing disc, a lower fixing disc and a plurality of screw rods, the upper fixing disc and the lower fixing disc are horizontally arranged above and below the coil unit respectively and are sleeved on the outer side of the inner container. The lower fixing disc is detachably fixedly connected with the inner container, the plurality of screw rods are annularly and uniformly arranged on the outer side of the coil unit, and the upper fixing disc is fixedly connected with the lower fixing disc through the screw rods.

6. The high magnetic field application apparatus for heat treatment according to claim 1, wherein For all the coils, two coils arranged in sequence and adjacent to each other are taken as a pair of coils, and a mesh-shaped spacing sheet for heat dissipation is arranged between any two pairs of adjacent coils.

7. The high magnetic field application apparatus for heat treatment according to claim 2, wherein The cooling mechanism comprises a plurality of axial flow fans, the axial flow fans are annularly and uniformly arranged on the top plate and located on the outer side of the feeding port. A plurality of air outlets are formed in the bottom plate, and the air outlets are annularly and uniformly arranged on the periphery of the inner container.

Images