A surface hardening coil for shaft parts and its manufacturing method

Abstract

Embodiments of the present disclosure relate to a surface hardening coil for shaft parts and a manufacturing method. It includes: a plurality of annular induction coils, each of which has a notch, and the notch makes the end of the annular induction coil not closed; each annular induction coil is arranged successively from bottom to top, and adjacent layers of annular induction coils are connected by an arc-shaped connecting section. One end of the connecting section is flush with one end of the annular induction coil located above the connecting section, and the other end of the connecting section is connected to one end of the annular induction coil located below the connecting section. The connecting section makes an arc-shaped gap between adjacent layers of annular induction coils, and the gap is used to fill an insulating medium; a first flow pipe, and the first flow pipe is respectively arranged in the inner cavity of each annular induction coil. Embodiments of the present disclosure can solve the problem of product heating, as well as the drawback of short wear-resistant life of the crankshaft caused by a shallow quenching layer, and improve the product heating efficiency.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of additive manufacturing technology, and in particular, to a surface hardening coil for shaft parts and a manufacturing method thereof. Background Art

[0002] In the field of automobile manufacturing, a half shaft is a rod member that drives and brakes wheels on a motor vehicle and is a core component of power. Generally, full-floating half shafts are used in heavy trucks, which mainly bear driving and braking torques. Semi-floating half shafts are mostly used in passenger cars, and the working load is a combined bending and torsion moment. In addition, the half shaft is also subject to a certain impact load. In order to improve the surface hardness, wear resistance and fatigue strength of shaft parts, while maintaining a relatively high toughness in the core, surface hardening is usually carried out on key parts of shaft parts during the heat treatment stage.

[0003] In related technologies, high-frequency induction heating coils for quenching shafts such as transmission and braking have great randomness in the manufacturing process, no unified standard, rough manufacturing, inaccurate external parameter dimensions, and the copper tube is wound according to the workpiece style. The preparation process of the copper coil with an internal flow channel basically adopts traditional processes, such as machining the copper plate, milling out the middle flow channel and then welding it to form a certain shape. The above high-frequency heating coils have the following deficiencies: 1) The shape design process of the existing shaft quenching coils on the market has great randomness, the quenching treatment efficiency of rapid cooling and heating is low, and the energy saving performance is poor; 2) There are many welding joints and it depends on manual work; 3) The service life is short; 4) The preparation depends on traditional manual work, the preparation period is long, and it is difficult to achieve batch production.

[0004] Therefore, it is necessary to improve one or more problems existing in the above related technical solutions.

[0005] It should be noted that this part is intended to provide background or context for the technical solutions of the present disclosure stated in the claims. The description herein is not admitted to be prior art merely because it is included in this part. Summary of the Invention

[0006] The purpose of the embodiments of the present disclosure is to provide a surface hardening coil for shaft parts and a manufacturing method thereof, so as to at least overcome one or more problems caused by the limitations and defects of related technologies to a certain extent.

[0007] According to the first aspect of the embodiments of the present disclosure, a surface hardening coil for shaft parts is provided, including:

[0008] A plurality of annular induction coils, each of the annular induction coils having a notch, the notch making the end of the annular induction coil not closed; wherein, the position of each notch is different, and the notch is used for filling an insulating medium;

[0009] Each of the annular induction coils is arranged successively from bottom to top, and adjacent layers of the annular induction coils are connected by an arc-shaped connecting section. One end of the connecting section is flush with one end of the annular induction coil located above the connecting section, and the other end of the connecting section is connected to one end of the annular induction coil located below the connecting section. This connecting section creates an arc-shaped gap between adjacent layers of the annular induction coils, and the gap is used to fill an insulating medium; wherein, the diameter of each of the annular induction coils decreases successively from bottom to top;

[0010] A first flow pipe, the first flow pipe is respectively arranged in the inner cavity of each of the annular induction coils, and the first flow pipes in adjacent layers of the annular induction coils are communicated; wherein, the first flow pipe is used for the circulation of a cooling medium;

[0011] A medium inlet, the medium inlet is arranged on the annular induction coil located at the lowermost layer, and is communicated with the first flow pipe in the annular induction coil at the lowermost layer;

[0012] A medium outlet, the medium outlet is arranged on the annular induction coil located at the uppermost layer, and is communicated with the first flow pipe in the annular induction coil at the uppermost layer.

[0013] In an embodiment of the present disclosure, two electrode plates are located at the center of the annular space formed by several of the annular induction coils. An insulating partition is arranged between the two electrode plates. One of the electrode plates is connected to the uppermost annular induction coil by a copper wire, and the other electrode plate is connected to the lowermost annular induction coil by a copper wire.

[0014] In an embodiment of the present disclosure, an adjustable magnetic yoke is arranged on the copper wire connected to one of the electrode plates, and the adjustable magnetic yoke is used to adjust the magnitude of the magnetic flux.

[0015] In an embodiment of the present disclosure, it further includes:

[0016] A first conductive rod is arranged at the medium inlet. The first conductive rod has a cavity, and the cavity in the first conductive rod is communicated with the medium inlet; one of the electrode plates is connected to the first conductive rod by a copper wire;

[0017] A second conductive rod is arranged at the medium outlet. The second conductive rod has a cavity, and the cavity in the second conductive rod is communicated with the medium outlet; the other electrode plate is connected to the second conductive rod by a copper wire.

[0018] In an embodiment of the present disclosure, it further includes:

[0019] A cooling medium storage tank is provided with an inlet end and an outlet end respectively. The inlet end is connected to the cavity inside the second conductive rod through a second flow pipe, and the outlet end is connected to the cavity inside the first conductive rod through a second flow pipe. Among them, a circulation pump is arranged on the pipe between the outlet end and the first conductive rod.

[0020] According to the second aspect of the embodiments of the present disclosure, a manufacturing method of a surface hardening coil for shaft parts is provided, and the method includes:

[0021] Establish a three-dimensional digital model of the hardening coil, and import the layer-by-layer scanning data obtained after slicing and discretizing the hardening coil into an electron beam scanning control software;

[0022] Under vacuum conditions, preheat the forming bottom plate;

[0023] Under vacuum conditions, evenly lay copper powder on the preheated forming bottom plate;

[0024] Under vacuum conditions, use a defocused electron beam to scan the powder layer to equalize the temperature;

[0025] Under vacuum conditions, a focused electron beam scans the molten powder layer according to the layer-by-layer scanning data;

[0026] Repeat the steps of laying copper powder, defocused scanning, and focused scanning to complete layer-by-layer solidification accumulation until the hardening coil is printed; after naturally cooling to below 50°C under vacuum conditions, clean it to obtain the hardening coil.

[0027] In an embodiment of the present disclosure, the slice thickness is 40-70 μm.

[0028] In an embodiment of the present disclosure, the preheating of the forming bottom plate is realized by defocused electron beam scanning, the scanning beam current is 10-25 mA, and the scanning speed is 10-20 m / s.

[0029] In an embodiment of the present disclosure, the copper powder is spherical, and the average diameter of the copper powder is 40-150 μm, and the powder laying thickness is 40-70 μm.

[0030] In an embodiment of the present disclosure, when the defocused electron beam scans the powder layer, the scanning beam current is 10-20 mA, the defocus amount is -0.2 to -0.5 V, and the scanning time is 10-25 s.

[0031] In an embodiment of the present disclosure, when scanning the molten powder layer, the spot diameter of the focused electron beam is 80-120 μm, the scanning beam current is 5-20 mA, the scanning speed is 1-3 m / s, and the scanning pitch is 80-150 μm.

[0032] The technical solutions provided by the embodiments of the present disclosure may include the following beneficial effects:

[0033] In the embodiments of the present disclosure, through the above-mentioned surface hardening coil for shaft parts, each annular induction coil is arranged successively from bottom to top, and adjacent layers of annular induction coils are connected by an arc-shaped connecting section. This connecting section forms an arc-shaped gap between adjacent layers of annular induction coils, and the gap is filled with an insulating medium to prevent current short-circuit, so as to ensure that the current flows along the coil winding direction. The diameters of the annular induction coils from bottom to top gradually decrease in sequence, such that several annular induction coils form a quenching coil similar to a sphere. At the same time, a first flow channel for the circulation of the cooling medium is provided inside the annular induction coil. This quenching coil greatly solves the problem of product heating and the drawback of short wear-resistant life of the crankshaft caused by a shallow quenching layer, and improves the product heating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0035] Figure 1 Showing a schematic structural diagram of the surface hardening coil for shaft parts in an exemplary embodiment of the present disclosure;

[0036] Figure 2 Showing a flowchart of the steps of a manufacturing method of the surface hardening coil for shaft parts in an exemplary embodiment of the present disclosure.

[0037] In the figure: 100, annular induction coil; 110, notch; 200, connecting section; 300, electrode plate; 310, insulating partition; 400, copper wire; 410, adjustable magnetic yoke; 500, first conducting rod; 600, second conducting rod; 700, cooling medium storage tank; 800, circulation pump; 900, second flow channel; 1000, insulating medium. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be more complete and comprehensive, and will fully convey the concept of the example embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0039] In addition, the accompanying drawings are only schematic illustrations of the embodiments of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0040] In this exemplary embodiment, a surface hardening coil for a shaft part is first provided. Referring to Figure 1 as shown in, the hardening coil may include: a plurality of annular induction coils 100, a notch 110, a first flow pipe, a medium inlet, and a medium outlet.

[0041] Among them, there are a plurality of annular induction coils 100, and each of the annular induction coils 100 is respectively provided with a notch 110, and the notch 110 makes the end of the annular induction coil 100 not closed; among them, the position of each notch 110 is different, and the notch 100 is used to fill an insulating medium.

[0042] Each of the annular induction coils 100 is arranged in sequence from bottom to top, and adjacent layers of the annular induction coils 100 are connected by an arc-shaped connecting section 200. One end of the connecting section 200 is flush with one end of the annular induction coil 100 located above the connecting section 200, and the other end of the connecting section 200 is connected to one end of the annular induction coil 100 located below the connecting section 200. The connecting section 200 makes an arc-shaped gap between adjacent layers of the annular induction coils 100, and the gap is used to fill an insulating medium 1000; among them, the diameter of each of the annular induction coils 100 decreases in sequence from bottom to top.

[0043] A first flow pipe, the first flow pipe is respectively arranged in the inner cavity of each of the annular induction coils 100, and the first flow pipes in adjacent layers of the annular induction coils 100 are communicated; among them, the first flow pipe is used for the circulation of a cooling medium.

[0044] A medium inlet, the medium inlet is arranged on the annular induction coil 100 located at the lowermost layer and is communicated with the first flow pipe in the annular induction coil 100 located at the lowermost layer.

[0045] A medium outlet, the medium outlet is arranged on the annular induction coil 100 located at the uppermost layer and is communicated with the first flow pipe in the annular induction coil 100 located at the uppermost layer.

[0046] Through the above-mentioned surface hardening coil for shaft parts, each annular induction coil 100 is arranged successively from bottom to top, and adjacent layers of annular induction coils 100 are connected by an arc-shaped connecting section 200. This connecting section 200 creates an arc-shaped gap between adjacent layers of annular induction coils 100, and the gap is filled with an insulating medium 1000 to prevent current short-circuiting, ensuring that the current flows along the coil winding direction. The diameters of the annular induction coils 100 from bottom to top gradually decrease successively, such that several annular induction coils 100 form a quenching coil similar to a sphere. At the same time, a first flow channel for the circulation of a cooling medium is provided inside the annular induction coil 100. This quenching coil greatly solves the problem of product heating and the drawback of short wear-resistant life of the crankshaft caused by a shallow quenching layer, and improves the product heating efficiency.

[0047] Next, reference will be made to Figure 1 for a more detailed description of each part of the above-mentioned quenching coil in the present exemplary embodiment.

[0048] In one embodiment, each annular induction coil 100 has a notch 110 respectively. The notch 110 makes the ends of the annular induction coil 100 not closed. The positions of each notch 110 on the corresponding annular induction coil 100 are different. The notch 100 is used to fill the insulating medium. Each annular induction coil 100 is arranged successively from bottom to top, and the diameter of each annular induction coil 100 gradually decreases from bottom to top, so that a number of annular induction coils 100 form a quenching coil similar to a sphere. The adjacent layers of annular induction coils 100 are connected by an arc-shaped connecting section 200, and the positions of the arc-shaped connecting sections 200 are different. One end of the connecting section 200 is flush with one end of the annular induction coil 100 above the connecting section 200, and the other end of the connecting section 200 is connected to one end of the annular induction coil 100 below the connecting section 200. The connecting section 200 makes an arc-shaped gap between the adjacent layers of annular induction coils 100. The gap is filled with the insulating medium 1000 to prevent the current from short-circuiting, so as to ensure that the current flows along the coil winding direction. The insulating medium filled at the gap and the notch 110 can prevent the current from short-circuiting, so as to ensure that the current flows along the coil winding direction. A medium inlet is arranged on the annular induction coil 100 at the lowermost layer. The medium inlet is used for the inflow of the cooling medium. A medium outlet is arranged on the annular induction coil 100 at the uppermost layer. The medium outlet is used for the outflow of the cooling medium. A first flow channel is arranged in the inner cavity of each annular induction coil 100, and the first flow channels in the inner cavities of the adjacent layers of annular induction coils 100 are communicated. The shape of the first flow channel is annular and matches the shape of the inner cavity of the annular induction coil 100. The first flow channel is used for the flow of the cooling medium. The medium inlet is communicated with the first flow channel in the annular induction coil 100 at the lowermost layer, and the medium outlet is communicated with the first flow channel in the annular induction coil 100 at the uppermost layer. Since the first flow channel is arranged in each annular induction coil 100, the contact area with the workpiece is increased when cooling the workpiece, and the cooling efficiency is improved. When using this quenching coil, the shaft-like product enters from the outer ring of the quenching coil similar to a sphere and sleights the induction coil, showing a wrapped shape. The consistency of the quenching depth of the product is realized by the self-rotation of the shaft-like product. After the surface quenching heating is completed, the product and the coil can be cooled by external cooling. At the same time, the cooling medium in the first flow channel in the annular induction coil 100 speeds up the cooling speed of the annular induction coil 100. After the surface quenching is completed, the product is taken off from the quenching coil similar to a sphere. It should be noted that the number of a number of annular induction coils 100 is at least 2 turns. For example, the number of annular induction coils 100 is 2 turns or 3 turns or 4 turns, etc. The number of annular induction coils 100 can be selected according to the actual situation, and this embodiment does not make any restrictions.1) When the annular induction coil 100 has 3 turns or even more turns, compared with the traditional configuration, the spherical reduction degree is high. When the alternating current surrounds the spherical coil, a strong magnetic flux with higher density, fuller and better three-dimensionality is generated. This magnetic flux penetrates the quenching layer to form a larger reverse eddy current and a stronger Joule heat power to accelerate the quenching heating process, shorten the working hours, improve the quenching efficiency of shaft parts, and reduce the energy consumption by about 1 / 3 under the same treatment; 2) The spherical magnetic flux cooperates with the rotation of the product to achieve consistent quenching depth of the product. In this way, the disadvantages of short wear-resistant life of the crankshaft caused by shallow and different quenching layers are solved, and at the same time, the heating efficiency of the product is improved to solve the product heating problem; 3) More turns can increase the passing time of the cooling medium in the first flow pipe, ensure the full heat exchange process of the cooling medium, and accelerate the cooling speed of the crankshaft quenching process.

[0049] In one embodiment, the quenching coil further includes:

[0050] Two electrode plates 300, located at the center of the annular space formed by several said annular induction coils 100. An insulating partition 310 is arranged between the two electrode plates 300. One of the electrode plates 300 is connected to the uppermost annular induction coil 100 through a copper wire 400, and the other electrode plate 300 is connected to the lowermost annular induction coil 100 through a copper wire 400.

[0051] Specifically, the quenching coil further includes two electrode plates 300. A plurality of annular induction coils 100 form an annular space. The two electrode plates 300 are located at the central position of the annular space. An insulating partition 310 is arranged between the two electrode plates 300. The insulating partition 310 is used for short-circuit protection, and the insulating partition 310 is a high-temperature-resistant insulating partition 310. Among the two electrode plates 300, when one of the electrode plates 300 is connected to the annular induction coil 100 located at the uppermost layer through a copper wire 400; the other electrode plate 300 is connected to the annular induction coil 100 located at the lowermost layer through a copper wire 400. Among them, for the positive and negative of the two electrode plates 300, this embodiment does not limit this. When one of the electrode plates 300 is the positive electrode and the other electrode plate 300 is the negative electrode. There are the following two situations for the current direction: 1) One of the electrode plates 300 as the positive electrode is connected to the annular induction coil 100 located at the uppermost layer through a copper wire 400, and the other electrode plate 300 as the negative electrode is connected to the annular induction coil 100 located at the lowermost layer through a copper wire 400. The current flows out from the electrode plate 300 as the positive electrode, flows through the copper wire 400 to the annular induction coil 100 at the uppermost layer, then flows layer by layer to the annular induction coil 100 at the lowermost layer, and then returns to the end of the electrode plate 300 as the negative electrode. 2) One of the electrode plates 300 as the positive electrode is connected to the annular induction coil 100 located at the lowermost layer through a copper wire 400, and the other electrode plate 300 as the negative electrode is connected to the annular induction coil 100 located at the uppermost layer through a copper wire 400. The current flows out from the electrode plate 300 as the positive electrode, flows through the copper wire 400 to the annular induction coil 100 at the lowermost layer, then flows layer by layer to the annular induction coil 100 at the uppermost layer, and then returns to the end of the electrode plate 300 as the negative electrode.

[0052] It should be noted that the two electrode plates are located at the center of the annular space formed by a plurality of annular induction coils. For the convenience of schematically showing the structure of the two electrode plates in the present disclosure, the Figure 1 structures of the two electrode plates in are pulled to the outside of the annular space formed by a plurality of annular induction coils for structural illustration, but Figure 1 the structures in do not represent a limitation to the present disclosure. It should also be noted that the current direction can be selected according to the actual situation, and this embodiment does not limit this.

[0053] In one embodiment, an adjustable magnetic yoke 410 is arranged on the copper wire 400 connected to one of the electrode plates 300, and the adjustable magnetic yoke 410 is used to adjust the magnitude of the magnetic flux.

[0054] Specifically, an adjustable magnetic yoke 410 is arranged on the copper wire 400 connected to the electrode plate 300 to adjust the magnitude of the magnetic flux at different positions, which has the function of directional guiding of the magnetic circuit, thereby adjusting the heating speed of each area of the workpiece and ultimately improving the overall heating efficiency of the quenching coil.

[0055] In one embodiment, a first conductive rod 500 is provided at the medium inlet. The first conductive rod 500 has a cavity, and the cavity inside the first conductive rod 500 communicates with the medium inlet; one of the electrode plates 300 is connected to the first conductive rod 500 through a copper wire 400;

[0056] A second conductive rod 600 is provided at the medium outlet. The second conductive rod 600 has a cavity, and the cavity inside the second conductive rod 600 communicates with the medium outlet; the other electrode plate 300 is connected to the second conductive rod 600 through a copper wire 400.

[0057] Specifically, the first conductive rod 500 is arranged at the medium inlet of the lowermost annular induction coil 100. The first conductive rod 500 has a cavity, and the cavity inside the first conductive rod 500 penetrates along the length direction of the first conductive rod 500. The cavity inside the first conductive rod 500 communicates with the medium inlet, facilitating the cooling medium to enter the medium inlet through the cavity inside the first conductive rod 500 and then enter the first flow channel inside the lowermost annular induction coil 100. A second conductive rod 600 is arranged at the medium outlet of the uppermost annular induction coil 100. The conductive rod has a cavity, and the cavity inside the second conductive rod 600 penetrates along the length direction of the second conductive rod 600. The cavity inside the second conductive rod 600 communicates with the medium outlet, facilitating the cooling medium to flow from the medium outlet to the cavity inside the second conductive rod 600.

[0058] When the cooling medium sequentially enters the first flow channel inside the lowermost annular induction coil 100 from the cavity inside the first conductive rod 500 and the medium inlet, since the first flow channels inside the annular induction coils 100 of adjacent layers are connected, the cooling medium flows from the first flow channel inside the lowermost annular induction coil 100 to the first flow channel inside the annular induction coil 100 above it, and thus flows to the first flow channel inside the uppermost annular induction coil 100, and then flows from the medium outlet to the cavity inside the second conductive rod 600.

[0059] It should be noted that in the process of the cooling medium gradually flowing from the first flow channel inside the annular induction coil 100 to the first flow channel inside the uppermost annular induction coil 100, the assistance of a circulation pump 800 is required to achieve this. And in the process of the cooling medium gradually flowing from the first flow channel inside the lowermost annular induction coil 100 to the first flow channel inside the uppermost annular induction coil 100, heat exchange occurs with the workpiece, thereby realizing the cooling of the workpiece.

[0060] In one embodiment, it further includes:

[0061] Cooling medium storage tank 700, an inlet end and an outlet end are respectively arranged on the cooling medium storage tank 700, the inlet end is connected to the cavity inside the second conductive rod 600 through a second flow pipeline, and the outlet end is connected to the cavity inside the first conductive rod 500 through a second flow pipeline. Among them, a circulation pump 800 is arranged on the second flow pipeline between the outlet end and the first conductive rod 500.

[0062] Specifically, the quenching coil further includes a cooling medium storage tank 700, and an inlet end and an outlet end are respectively arranged on the cooling medium storage tank 700. The inlet end on the cooling medium storage tank 700 is connected to the cavity inside the first conductive rod 500 through a second flow pipeline, and the outlet end on the cooling medium storage tank 700 is connected to the cavity inside the second conductive rod 600 through a second flow pipeline. A circulation pump 800 is arranged on the second flow pipeline between the outlet end and the first conductive rod 500. The circulation pump 800 is used for the circulation of the cooling medium in the cooling medium storage tank 700, the cavity inside the first conductive rod 500, the first flow pipeline inside the lowermost annular induction coil 100, the first flow pipeline inside the middle annular induction coil 100, the first flow pipeline inside the uppermost annular induction coil 100, and the cavity inside the second conductive rod 600, thereby greatly improving the cooling speed of the quenching coil.

[0063] In this exemplary embodiment, a manufacturing method of a surface quenching coil for shaft parts is also provided. Refer to Figure 1 As shown in, this method may include:

[0064] Step S101: Establish a three-dimensional digital model of the quenching coil, and import the layer-by-layer scanning data obtained after slicing and discretizing the quenching coil into an electron beam scanning control software.

[0065] Step S102: Preheat the forming bottom plate under vacuum conditions.

[0066] Step S103: Uniformly lay copper powder on the preheated forming bottom plate under vacuum conditions.

[0067] Step S104: Use a defocused electron beam to scan the powder layer to equalize the temperature under vacuum conditions.

[0068] Step S105: The focused electron beam scans the molten powder layer according to the layer-by-layer scanning data under vacuum conditions.

[0069] Step S106: Repeat the steps of laying copper powder, defocused scanning, and focused scanning to complete layer-by-layer solidification and accumulation until the quenching coil is printed; after naturally cooling to below 50 °C under vacuum conditions and cleaning, the quenching coil can be obtained.

[0070] In one embodiment, in the manufacturing method of the surface hardening coil for the shaft parts above, the hardening coil is prepared by powder bed fusion additive manufacturing technology. When preparing, metal powder is used as the raw material, and then high-energy beams such as electron beams and laser beams are used as the energy source. Based on the three-dimensional model of the target part, using the principle of discrete - deposition, the raw material powder is melted point by point and deposited layer by layer under the control of software and numerical control system, so as to realize the rapid manufacturing of metal components. With the continuous development of application fields such as new energy and the processing of other high-end equipment parts, and thermal processing equipment, the requirements for the structural complexity and functionality of high-performance pure copper induction coils are gradually increasing. The production process of the traditional manufacturing method for pure copper induction coils is: machining - splicing and assembling - re-welding - size correction, shaping, etc. The entire production process is relatively long, and there are many product welding joints, resulting in problems such as high production costs, long production cycles, poor conductivity, high energy consumption, and short product service life. However, the pure copper induction coil manufactured by powder bed fusion additive manufacturing technology can integrally and rapidly manufacture induction coil parts with complex configurations.

[0071] Compared with the traditional manufacturing method, it has many innovations and advantages:

[0072] 1. Advanced manufacturing process. Powder bed fusion additive manufacturing technology is a digital and intelligent high-end manufacturing method, which can manufacture pure copper thin-walled hollow copper coil parts with more complex geometric structures and higher functional requirements. 2. Reduced production costs and environmentally friendly production process. The traditional manufacturing method has a long production process and requires welding connections, with high manual operation intensity. However, the production process using powder bed fusion additive manufacturing technology is fully automated, can integrally and rapidly form induction coils with complex configurations, has a short production cycle and high production efficiency, significantly reduces labor costs and production costs, and does not require welding during the production process and is environmentally friendly. 3. The pure copper induction coil produced has high conductivity and obvious energy-saving effect. The additive manufacturing product has no welding seams, etc., the conductivity performance is increased by more than 20%, and the electric energy is saved by more than 10%. 4. The product has a relatively long service life. After industry comparison and verification, the induction coil manufactured by additive manufacturing has an integral forming, no welding seams, etc., and the product service life is 2 - 3 times that of the traditional butt-welded forming induction coil. 5. High design freedom and precise processing. The complex structure is integrally formed, not only with high design freedom, but also with high product dimensional tolerance accuracy, which is closer to the theoretical model size of the product design.

[0073] In one embodiment, the slice thickness is 40 - 70 μm. Specifically, when the slice thickness is 40 - 70 μm, the required layer scanning data can be obtained.

[0074] In one embodiment, the preheating of the forming base plate is achieved by defocused electron beam scanning, with a scanning beam current of 10 - 25 mA and a scanning speed of 10 - 20 m / s. Specifically, before powder spreading, the forming base plate needs to be preheated first, and the preheating of the forming base plate is achieved by defocused electron beam scanning here.

[0075] In one embodiment, the copper powder is spherical, and the average diameter of the copper powder is 40 - 150 μm, and the powder spreading thickness is 40 - 70 μm. Specifically, by selecting copper powder with an average diameter of 40 - 150 μm and spreading the powder with a thickness of 40 - 70 μm, it is possible to better print out the quenching coil.

[0076] In one embodiment, when the defocused electron beam scans the powder layer, the scanning beam current is 10 - 20 mA, the defocus amount is -0.2 - -0.5 V, and the scanning time is 10 - 25 s. Specifically, when the scanning beam current is 10 - 20 mA, the defocus amount is -0.2 - -0.5 V, and the scanning time is 10 - 25 s, it is possible to achieve better scanning of the powder layer by the defocused electron beam.

[0077] In one embodiment, when scanning and melting the powder layer, the spot diameter of the focused electron beam is 80 - 120 μm, the scanning beam current is 5 - 20 mA, the scanning speed is 1 - 3 m / s, and the scanning pitch is 80 - 150 μm. Specifically, when the spot diameter of the focused electron beam is 80 - 120 μm, the scanning beam current is 5 - 20 mA, the scanning speed is 1 - 3 m / s, and the scanning pitch is 80 - 150 μm, it is possible to better scan and melt the powder layer.

[0078] The following further elaborates on the present disclosure through the following embodiments.

[0079] Example 1:

[0080] Referring to the technical solution, a three - turn induction spherical quenching coil for the surface of a shaft - type part is designed. The overall contour spherical diameter of the three - turn outer shape is designed to be R58.5 mm, the fillet at the upper and lower connections of the large surfaces of the middle two layers is R0.8 mm, the designed value of the side wall thickness of the annular induction coil is 1.2 mm, and the designed value of the wall thickness of the middle two layers is 2.0 mm. It is adapted to the low - line - energy - density process to ensure no warping during the forming process and airtightness under a pressure of 0.75 MPa.

[0081] (1) Establish a three - dimensional digital model of the formed part;

[0082] (2) Import the layer - by - layer scanning data obtained after slicing and discretizing the three - dimensional digital model into the electron beam scanning control software, with a slice thickness of 50 μm;

[0083] (3) Under vacuum conditions, the required vacuum degree is 2.0×10 -3Preheat the formed bottom plate to 300 °C. The preheating is achieved by defocused electron beam scanning. The scanning beam current is 10 mA, the scanning speed is 15 m / s, and the defocus amount is -0.2 V.

[0084] (4) Under vacuum conditions, the required vacuum degree is 2.0×10 -3 Pa. Uniformly lay spherical copper powder on the formed bottom plate.

[0085] (5) Under vacuum conditions, the required vacuum degree is 2.0×10 -3 Pa. Use defocused electron beam to scan the powder layer to equalize the temperature. The scanning beam current is 15 mA, the defocus amount is -0.2 V, and the scanning time is 10 s.

[0086] (6) Under vacuum conditions, the required vacuum degree is 2.0×10 -3 Pa. Use focused electron beam to scan and melt the powder layer according to the layer scanning data. Forming process for the large bottom surface of the middle two layers: the scanning beam current is 12 mA, the scanning speed is 2 m / s, and the scanning pitch is 100 μm. Forming parameters at other heights: the scanning beam current is 15 mA, the scanning speed is 2.5 m / s, and the scanning pitch is 100 μm.

[0087] (7) Repeat steps (4) to (6) to complete layer-by-layer solidification accumulation until the entire part is printed. After naturally cooling to below 50 °C under vacuum conditions and cleaning, a three-turn spherical induction hardening coil part can be obtained.

[0088] Static tests are carried out after forming: 1) Air tightness test, no air hole leakage at 0.75 MPa air pressure, and the pressure remains 0.75 MPa after 20 minutes; 2) Flow rate test: the flow rate is 27.4 L / min under 0.3 MPa water pressure.

[0089] Install and carry out dynamic tests: 1) The single quenching working hours of the crankshaft with the same process are shortened by 8 - 10 s, the quenching efficiency is increased by 24.6%, and the energy consumption is reduced by about 22%; 2) The service life of the three-turn spherical induction hardening coil is about more than 600,000 times, and the product service life is 2 - 3 times that of the traditional (200,000 - 300,000 times) welded forming induction coil; 3) Conductivity test is carried out after the coil is installed, and the conductivity is 94.3%, which is more than 23% higher than that of the traditional welded coil, saving 12% of electric energy; 4) After heat treatment, the crankshaft is sampled annularly to calibrate the quenching depth. The quenching layer depth value of one annular turn is 3.5 mm ± 0.2 mm, and the depth is uniform.

[0090] Example 2:

[0091] Design a four - turn spherical induction coil for surface hardening of shaft parts according to the technical solution. The overall contour sphere diameter of the four - turn shape is designed to be R59mm, the fillet at the connection of the upper and lower large surfaces of the middle two layers is R0.8mm, the designed value of the side wall thickness of the annular induction coil is 1.3mm, and the designed value of the wall thickness of the middle two layers is 2.1mm. It is adapted to the low - line - energy - density process to ensure no warping during the forming process and airtightness under a pressure of 0.75MPa.

[0092] (1) Establish a three - dimensional digital model of the formed part;

[0093] (2) Import the layer - by - layer scanning data obtained after slicing and discretizing the three - dimensional digital model into the electron beam scanning control software, and the slice thickness is 50μm;

[0094] (3) Under vacuum conditions, with a required vacuum degree of 2.0×10 - 3pa, preheat the forming bottom plate to 310℃. The preheating is achieved through defocused electron beam scanning, with a scanning beam current of 12mA, a scanning speed of 14m / s, and a defocus amount of - 0.2V;

[0095] (4) Under vacuum conditions, with a required vacuum degree of 2.0×10 -3 pa, evenly lay the spherical copper powder on the forming bottom plate;

[0096] (5) Under vacuum conditions, with a required vacuum degree of 2.0×10 -3 pa, use defocused electron beam scanning to equalize the temperature of the powder layer. The scanning beam current is 16mA, the defocus amount is - 0.2V, and the scanning time is 12s;

[0097] (6) Under vacuum conditions, with a required vacuum degree of 2.0×10 -3 pa, use a focused electron beam to scan and melt the powder layer according to the layer - by - layer scanning data. Forming process for the large bottom surface of the middle two layers: the scanning beam current is 13mA, the scanning speed is 2.5m / s, and the scanning pitch is 100μm. Forming parameters at other heights: the scanning beam current is 14.5mA, the scanning speed is 2.5m / s, and the scanning pitch is 100μm;

[0098] (7) Repeat steps (4) to (6) to complete layer - by - layer solidification accumulation until the entire part is printed. After naturally cooling to below 50℃ under vacuum conditions, clean it to obtain the four - turn spherical induction quenching coil part.

[0099] After forming, conduct static tests: 1) Airtightness test, no air hole leakage at 0.75MPa air pressure, and the pressure remains 0.75MPa after maintaining for 20min; 2) Flow rate test: the flow rate is 26.1L / min under 0.3MPa water pressure.

[0100] Installation for dynamic testing: 1) For the same process, the single quenching time of the crankshaft is shortened by 11 - 15 s, the quenching efficiency is increased by 30.6%, and the energy consumption is reduced by about 27%; 2) The service life of the four-turn spherical induction quenching coil is about more than 800,000 times, and the service life of the product is 2 - 4 times that of the traditional (200,000 - 300,000 times) welded forming induction coil; 3) After the coil is installed, a conductivity test is carried out. The conductivity is 95.7%, which is more than 26% higher than that of the traditional welded coil, saving 17% of electric energy; 4) After heat treatment, the crankshaft is sampled in a ring shape for quenching depth calibration. The quenching layer depth value of one ring is 3.6 mm ± 0.2 mm, and the depth is uniform.

[0101] In the manufacturing method of the above-mentioned quenching coil: 1) The spherical diameter of the overall contour of the three-turn outer shape is designed to be R58 - 60 mm. At this curvature, the slope angles of the inner and outer sides of the annular sphere can be directly formed without adding auxiliary supports, avoiding the problem of difficult removal of the inner side and inclined surface gap supports. 2) The fillet at the upper and lower joints of the large surfaces of the middle two layers is R0.8 mm to ensure that the edges do not curl. 3) The designed value of the side wall thickness of the annular induction coil is 1.2 - 1.5 mm, taking into account dense forming to ensure airtightness and coolant flow through at a pressure of 0.75 MPa. 4) The designed value of the wall thickness of the middle two layers is 2.0 - 2.3 mm, adapting to the low heat energy density process, ensuring no warping during the forming process and airtightness at a pressure of 0.75 MPa.

[0102] It should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. in the above description is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the embodiments of the present disclosure.

[0103] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present disclosure, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0104] In the embodiments of the present disclosure, unless otherwise clearly defined and limited, terms such as "installation", "connection", "connection", "fixation", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0105] In the embodiments of the present disclosure, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "under" and "beneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0106] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0107] Those skilled in the art will readily conceive of other implementations of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure, which follow the general principles of the present disclosure and include the common general knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and examples are only regarded as exemplary, and the true scope and spirit of the present disclosure are pointed out by the appended claims.

Claims

1. A surface hardening coil for shaft parts, characterized in that, Including: A number of annular induction coils, each of which has a notch, and the notch makes the end of the annular induction coil not closed; wherein, the positions of each notch are different, and the notch is used to fill an insulating medium; Each of the annular induction coils is arranged successively from bottom to top, and adjacent layers of the annular induction coils are connected by an arc-shaped connecting section. One end of the connecting section is flush with one end of the annular induction coil located above the connecting section, and the other end of the connecting section is connected to one end of the annular induction coil located below the connecting section. The connecting section makes an arc-shaped gap between adjacent layers of the annular induction coils, and the gap is used to fill an insulating medium; wherein, the diameter of each annular induction coil decreases successively from bottom to top; A first flow pipe, which is respectively arranged in the inner cavity of each annular induction coil, and the first flow pipes in adjacent layers of the annular induction coils are communicated; wherein, the first flow pipe is used for the flow of a cooling medium; A medium inlet, which is arranged on the annular induction coil located at the lowermost layer and is communicated with the first flow pipe in the annular induction coil at the lowermost layer; A medium outlet, which is arranged on the annular induction coil located at the uppermost layer and is communicated with the first flow pipe in the annular induction coil at the uppermost layer.

2. The surface hardening coil for shaft parts according to claim 1, wherein Further including: Two electrode plates, located at the center of the annular space formed by a number of the annular induction coils. An insulating partition is arranged between the two electrode plates. One of the electrode plates is connected to the uppermost annular induction coil by a copper wire, and the other electrode plate is connected to the lowermost annular induction coil by a copper wire.

3. The surface hardening coil for shaft parts according to claim 2, characterized in that, An adjustable magnetic yoke is arranged on the copper wire connected to one of the electrode plates, and the adjustable magnetic yoke is used to adjust the magnitude of the magnetic flux.

4. The surface hardening coil for shaft parts according to claim 2, characterized in that, A first conducting rod is arranged at the medium inlet. The first conducting rod has a cavity, and the cavity in the first conducting rod is communicated with the medium inlet; one of the electrode plates is connected to the first conducting rod by a copper wire; A second conducting rod is arranged at the medium outlet. The second conducting rod has a cavity, and the cavity in the second conducting rod is communicated with the medium outlet; the other electrode plate is connected to the second conducting rod by a copper wire.

5. The surface hardening coil for shaft parts according to claim 4, characterized in that, Further including: A cooling medium storage tank, which is respectively provided with an inlet end and an outlet end. The inlet end is connected to the cavity in the second conducting rod through a second flow pipe, and the outlet end is connected to the cavity in the first conducting rod through a second flow pipe. Wherein, a circulation pump is arranged on the second flow pipe between the outlet end and the first conducting rod.

6. A manufacturing method for a surface hardening coil of a shaft-like part, characterized in that, Using this method to prepare the surface hardening coil for the shaft parts as described in any one of claims 1 to 5 above, this method includes: Establishing a three-dimensional digital model of the hardening coil and importing the layer-by-layer scanning data obtained after slicing and discretizing the hardening coil into an electron beam scanning control software; Preheating the forming bottom plate under vacuum conditions; Under vacuum conditions, uniformly lay the copper powder on the preheated forming bottom plate; Under vacuum conditions, use a defocused electron beam to scan the powder layer to equalize the temperature; Under vacuum conditions, the focused electron beam scans and melts the powder layer according to the layer-by-layer scanning data; Repeat the steps of laying copper powder, defocused scanning, and focused scanning to complete layer-by-layer solidification accumulation until the quenching coil is printed; after naturally cooling to below 50°C under vacuum conditions, clean it to obtain the quenching coil.

7. The manufacturing method of the surface hardening coil for shaft parts according to claim 6, characterized in that, The slice thickness is 40 - 70 μm.

8. The manufacturing method of the surface hardening coil for shaft parts according to claim 6, characterized in that, The preheating of the forming bottom plate is achieved by defocused electron beam scanning, with a scanning beam current of 10 - 25 mA and a scanning speed of 10 - 20 m / s.

9. The manufacturing method of the surface hardening coil for shaft parts according to claim 6, characterized in that, The copper powder is spherical, and the average diameter of the copper powder is 40 - 150 μm, and the powder laying thickness is 40 - 70 μm.

10. The manufacturing method of the surface hardening coil for shaft parts according to claim 6, characterized in that, When the defocused electron beam scans the powder layer, the scanning beam current is 10 - 20 mA, the defocus amount is -0.2 - -0.5 V, and the scanning time is 10 - 25 s.

11. The manufacturing method of the surface hardening coil for shaft parts according to claim 6, characterized in that, When scanning and melting the powder layer, the spot diameter of the focused electron beam is 80 - 120 μm, the scanning beam current is 5 - 20 mA, the scanning speed is 1 - 3 m / s, and the scanning pitch is 80 - 150 μm.

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