A prefabricated heating block, heating module and high-strength fine tungsten wire drawing equipment

Abstract

The present invention discloses a heating block, which comprises a heating wire and an insulating heat-conducting layer covering the outside of the heating wire. The insulating heat-conducting layer is formed on the outside of the heating wire by high-temperature sintering, so that the heat generated by the heating wire is first transferred to the insulating heat-conducting layer by direct heat transfer, and then transferred to the component to be heated by thermal radiation. The overall temperature uniformity is good and the heating efficiency is high.

Description

Technical Field

[0001] The invention relates to the technical field of tungsten wire preparation, and in particular to a prefabricated heating block, a heating module and high-strength fine tungsten wire drawing equipment. Background Art

[0002] Tungsten wire refers to the filament made by forging and drawing tungsten bars. It is mainly used in electric light sources such as incandescent lamps and halogen tungsten lamps. It can also be used as high-speed cutting alloy steel, or used in optical instruments, chemical instruments, etc. In order to improve the high-temperature creep resistance of tungsten wire, a small amount of dispersion strengthening elements such as potassium, silicon, aluminum and rare metal oxides are usually added during the smelting process of tungsten wire to form an interlocking internal grain structure in the shape of a "dovetail overlap". This kind of tungsten wire is called doped tungsten wire (Doped Tungsten Wire). Doped tungsten wire is also called 218 tungsten wire or non-sag tungsten wire (Non-sag Tungsten Wire).

[0003] The production process of doped tungsten wire includes several main stages: tungsten smelting, powder metallurgy billet making and plastic processing. Among them, plastic processing mainly adopts rotary forging (rotary forging), rolling and drawing. Since tungsten has a high plastic-brittle transition temperature and shows obvious brittleness at low temperature or room temperature, it must be heated to a certain temperature during the plastic processing process. Too low temperature may cause tungsten wire to be delaminated, and at the same time, it may cause the surface fiber of tungsten wire to be fragmented, thereby causing high concentration of stress, thus causing the source of tungsten wire fracture. Therefore, a reasonable drawing temperature is the key to ensuring the processing performance and winding performance of tungsten wire. In addition, in actual application, graphite emulsion is usually coated on the surface of tungsten wire before drawing. Therefore, heating the tungsten wire can also evaporate the water in the graphite emulsion, so that the graphite powder is evenly attached to the surface of the tungsten wire. Since the evaporation process of water will also affect the temperature of tungsten wire, this factor must be fully considered during the heating process. In the existing wire drawing equipment, the temperature control accuracy of the heating module is low. Under the influence of the evaporation of water in the graphite emulsion, the actual temperature of the tungsten wire may be lower than the expected temperature, thereby affecting its performance.

[0004] In the process of heating the tungsten wire, indirect heating is often used. In order to improve the accuracy of temperature control, the distance between the tungsten wire and the heating module should be as small as possible. However, if the distance is too small, the tungsten wire may contact the heating module and cause damage. For example, the common U-shaped or W-shaped heating tube is prone to ups and downs during the heating process. Therefore, in order to avoid it touching the tungsten wire, the distance between the heating tube and the tungsten wire is usually large, which can easily cause energy waste. Summary of the invention

[0005] In view of some or all of the problems in the prior art, the present invention provides a prefabricated heating block in a first aspect, comprising:

[0006] a heating wire; and

[0007] The insulating heat-conducting layer is coated on the outside of the heating wire.

[0008] Furthermore, the insulating heat-conducting layer is made of silicon dioxide.

[0009] Furthermore, the heating block is manufactured according to the following steps:

[0010] burying the heating wire in silica powder but leaving the terminal exposed; and

[0011] The silicon dioxide powder embedded with the heating wire is heated at high temperature, so that the powder particles are sintered to form a heating block.

[0012] Based on the prefabricated heating block as described above, the second aspect of the present invention provides a heating module, which is used for fine tungsten wire drawing and includes at least one prefabricated heating block as described above.

[0013] Furthermore, the heating temperature T of the prefabricated heating block is determined according to the tungsten wire diameter d:

[0014] T=(-9*10 3 )d 2 +(4.35*10 3 )d+305,

[0015] The unit of the tungsten wire diameter is millimeter.

[0016] A third aspect of the present invention provides a high-strength fine tungsten wire drawing device, which includes the heating module as described above.

[0017] Furthermore, the high-strength fine tungsten wire drawing equipment also includes a wire-paying module, a graphite emulsion module, a die module, a tower wheel module and a wire-taking module.

[0018] Furthermore, the high-strength fine tungsten wire drawing equipment also includes a guide wheel group, which is arranged between the wire pay-off module and the graphite emulsion module, and / or between the die module and the tower wheel module.

[0019] The present invention provides a heating block, which forms an insulating heat-conducting layer on the outside of the heating wire by high-temperature sintering, so that the heat generated by the heating wire is first transferred to the insulating heat-conducting layer by direct heat transfer, and then transferred to the component to be heated by thermal radiation. The overall temperature uniformity is good and the heating efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] To further illustrate the above and other advantages and features of various embodiments of the present invention, a more specific description of various embodiments of the present invention will be presented with reference to the accompanying drawings. It will be understood that these drawings only depict typical embodiments of the present invention and are therefore not to be considered as limiting the scope thereof. In the accompanying drawings, for clarity, identical or corresponding parts will be represented by identical or similar reference numerals.

[0021] Figure 1 A schematic diagram showing the structure of a high-strength fine tungsten wire drawing device according to an embodiment of the present invention;

[0022] Figure 2 A schematic structural diagram showing a high-strength fine tungsten wire drawing device according to another embodiment of the present invention;

[0023] Figure 3 A schematic diagram showing the structure of a multi-stage heating thin tungsten wire heating module according to an embodiment of the present invention;

[0024] Figure 4 A schematic diagram showing the structure of a mobile heating module according to an embodiment of the present invention;

[0025] Figure 5 A schematic diagram showing the structure of a heating module using a heating tube according to an embodiment of the present invention;

[0026] Figure 6 A schematic diagram showing the structure of a prefabricated heating block according to an embodiment of the present invention;

[0027] Figure 7 A schematic diagram showing the structure of a guide wheel according to an embodiment of the present invention;

[0028] Figure 8 A schematic diagram showing the structure of a wire-releasing device according to an embodiment of the present invention; and

[0029] Fig. 9 A schematic structural diagram of a wire drawing die according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0030] In the following description, the present invention is described with reference to various embodiments. However, those skilled in the art will recognize that various embodiments can be implemented without one or more specific details or with other replacement and / or additional methods, materials or components. In other cases, well-known structures, materials or operations are not shown or described in detail to avoid blurring the inventive point of the present invention. Similarly, for the purpose of explanation, specific quantities, materials and configurations are set forth to provide a comprehensive understanding of embodiments of the present invention. However, the present invention is not limited to these specific details. In addition, it should be understood that the various embodiments shown in the drawings are illustrative representations and are not necessarily drawn in correct proportions.

[0031] In this specification, reference to "one embodiment" or "the embodiment" means that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. The phrase "in one embodiment" appearing in various places in this specification does not necessarily all refer to the same embodiment.

[0032] It should be noted that the embodiments of the present invention describe the process steps in a specific order, but this is only for the purpose of illustrating the specific embodiment, rather than limiting the order of the steps. On the contrary, in different embodiments of the present invention, the order of the steps can be adjusted according to the adjustment of the process.

[0033] In the present invention, the term "high-strength tungsten wire" refers to a tungsten wire with a tensile strength of not less than 5800 MPa. The term "fine tungsten wire" refers to a tungsten wire with a wire diameter of not more than 36 microns, especially about 28 microns. For example, the fine tungsten wire of the present invention can be an ultra-fine tungsten wire with a wire diameter of about 0.4 mm stretched to about 0.028 mm and a tensile strength of not less than 5800 MPa.

[0034] In order to form high-strength grain structure tungsten wire, the present application improves the existing tungsten wire drawing equipment, so that ultra-fine tungsten wire with a wire diameter of no more than 36 microns and a tensile strength of no less than 5800 MPa can be produced. The scheme of the present application is further described below in conjunction with the accompanying drawings of the embodiments.

[0035] Figure 1 The schematic diagram of the structure of a high-strength fine tungsten wire drawing device according to an embodiment of the present invention is shown. Figure 1 As shown, a high-strength fine tungsten wire drawing equipment includes a wire-paying module 101, a graphite emulsion module 102, a heating module 103, a die module 104, a tower wheel module 105 and a wire-receiving module 106 in sequence along the tungsten wire drawing direction. In order to prevent the tungsten wire from shaking, a guide wheel group 107 is further arranged between the wire-paying module 101 and the graphite emulsion module 102, and / or between the die module 104 and the tower wheel module 105, and the number of guide wheels in the guide wheel group 107 is consistent with the number of wire drawing times, that is, the number of wire drawing dies included in the die module 104.

[0036] The pay-off module 101 may adopt an active pay-off mode or a passive pay-off mode. Figure 8 A schematic diagram showing the structure of a wire-releasing device according to an embodiment of the present invention is shown in FIG. Figure 8As shown, in one embodiment of the present invention, the pay-off module 101 includes a pay-off disc 111, a guide wheel group 112, a fixed rod 113, a swing rod 114, a balance wheel 115, a fixed guide wheel 116, a support frame 117, a motor 118 and a controller (not shown). The pay-off disc 111, the fixed rod 113 and the fixed guide wheel 116 are all fixedly arranged on the first side of the support frame 117. The pay-off disc 111 is used to release tungsten wire. The guide wheel group 112 is fixedly arranged at the end of the fixed rod 113, including two parallel guide wheel grooves, wherein the first guide wheel groove is away from the support frame 117, and the second guide wheel groove is adjacent to the support frame 117. The swing rod 114 is movably arranged on the first side of the support frame 117. The balance wheel 115 is fixedly arranged at the end of the swing rod 114. The swing rod 114 can detect the swing angle of the balance wheel 115 and transmit the signal to the controller, and then the active pay-off speed is adjusted by the controller to balance it with the wire drawing speed. The balance wheel 115 is fixedly connected to the swing rod, and the tungsten wire passes through the balance wheel 115. Under the pull of the tungsten wire, the balance wheel 115 and the swing rod 114 can swing up and down. The motor 118 is located on the second side of the support frame 117 opposite to the first side thereof, and is fixedly connected to the pay-off drum 111 to drive the pay-off drum 111 to rotate and pay-off. The controller controls the operation of the motor 118, including starting and stopping the motor 118 by the controller, and adjusting the speed of the motor 8 according to the signal received from the balance wheel 114.

[0037] Graphite emulsion plays a role of lubrication and protection in the tungsten wire processing. If the lubrication performance is not good, the required tensile force will be greater, which will correspondingly increase the friction heat between the tungsten wire and the mold, thereby reducing the temperature difference in and out of the mold, causing "wire shrinkage". Therefore, before drawing the tungsten wire, it is usually necessary to apply a layer of graphite emulsion on the surface of the tungsten wire through a graphite emulsion module. In one embodiment of the present invention, the graphite emulsion module 102 includes a graphite emulsion container, a graphite emulsion trough, a water pump, a tilting plate, a first pipeline, a second pipeline, and a third pipeline. The graphite emulsion container is a container with a conical bottom, which is used to store graphite emulsion and enables the graphite emulsion to flow without residue. The graphite emulsion is used to coat the surface of the tungsten wire with graphite emulsion. The upper part of the graphite emulsion has a plurality of arc-shaped wire-passing openings. The width of the wire-passing openings is 3 mm, so that the metal wire can pass through the graphite emulsion. The graphite emulsion is contained in the graphite emulsion. The horizontal plane of the graphite emulsion is not lower than the wire-passing opening. When the metal wire passes through the opening on the groove wall, a layer of graphite emulsion will be covered on the surface. The water pump is used to provide power. It is connected with the graphite emulsion container and the graphite emulsion cylinder through the second pipeline and the third pipeline respectively, so as to transport the graphite emulsion in the graphite emulsion container to the graphite emulsion cylinder. The inclined plate is located below the graphite emulsion cylinder and is connected with the graphite emulsion container through the first pipeline. It is used to receive the graphite emulsion flowing out of the graphite emulsion cylinder and transport the graphite emulsion to the graphite emulsion container under the action of gravity. The length and width of the inclined plate are both greater than the length and width of the graphite emulsion cylinder. In one embodiment of the present invention, a graphite emulsion trough can be used instead of a graphite emulsion cylinder. The graphite emulsion trough has two opposite trough walls with multiple opposite openings so that a metal wire can pass through the graphite emulsion trough. When the metal wire passes through the wire opening on the trough wall, a layer of graphite emulsion will be covered on the surface.

[0038] Since the graphite emulsion coated on the surface of the tungsten wire by the graphite emulsion module 102 is actually a graphite powder suspension, the tungsten wire coated with the graphite emulsion needs to be heated by the heating module 103 before being sent into the mold. On the one hand, the heating module 103 can evaporate the water in the graphite emulsion, thereby solidifying the graphite powder on the surface of the tungsten wire, and on the other hand, the heating module 103 can also make the tungsten wire reach a temperature suitable for stretching.

[0039] Since the evaporation process of the water in the graphite emulsion will also have a certain impact on the temperature of the tungsten wire itself, therefore, in one embodiment of the present invention, Figure 3As shown, at least two temperature zones are arranged along the direction of the tungsten wire in the heating module 103, wherein the first temperature zone is mainly used to evaporate water quickly, and the second temperature zone is used to adjust the temperature of the tungsten wire. In order to avoid excessive temperature changes affecting the elongation of the tungsten wire, in one embodiment of the present invention, several temperature transition zones can also be arranged between the first and second temperature zones. In one embodiment of the present invention, the first temperature zone is mainly used to evaporate the water in the graphite emulsion, and the heating of the tungsten wire is mainly completed by the second temperature zone. Since the temperature required for water evaporation is usually lower than the heating temperature of the tungsten wire, the temperature of the first temperature zone is lower than the second temperature zone, wherein the temperature of the second temperature zone is dynamically adjusted according to the wire diameter of the tungsten wire. In another embodiment of the present invention, the first temperature zone is used to evaporate the water in the graphite emulsion and heat the tungsten wire at the same time. In order to quickly evaporate the water in the graphite emulsion, the temperature of the first temperature zone is higher than the temperature of the second temperature zone, and preferably the first temperature zone is 50°C higher than the temperature of the second temperature zone. The suitable stretching temperature of the tungsten wire is usually between 350°C and 800°C, and is related to the wire diameter of the tungsten wire itself. Generally speaking, as the wire diameter of the tungsten wire decreases, the required heating temperature should continue to decrease. Based on this, in an embodiment of the present invention, the temperature T of the second temperature zone is dynamically adjusted according to the wire diameter d of the tungsten wire in the pay-off module 101:

[0040] T=(-9*10 3 )d 2 +(4.35*10 3 )d+305,

[0041] The unit of the tungsten wire diameter d is millimeter.

[0042] In another embodiment of the present invention, when the tungsten wire needs to be stretched from 0.39 mm to 0.18 mm in wire diameter, the temperature of the second temperature zone can be set to, for example, between 750°C and 850°C; when the tungsten wire needs to be stretched from 0.18 mm to 0.07 mm in wire diameter, the temperature of the second temperature zone can be set to, for example, between 600°C and 700°C; and when the tungsten wire needs to be stretched from 0.07 mm to 0.03 mm in wire diameter, the temperature of the second temperature zone can be set to, for example, between 400°C and 550°C.

[0043] Limited by the existing heating technology, the heating module usually takes 30 minutes or even longer to reach the required temperature. In the process of tungsten wire drawing, the tungsten wire needs to pass through the inside of the heating module, and the wire threading operation usually needs to be done manually, which means that the heating module can only be started after the wire threading is completed, which seriously affects the overall production efficiency. In order to improve efficiency, in one embodiment of the present invention, Figure 4As shown in the figure, the heating module 103 includes a heating part 131 and a moving part 132. The heating part 131 can move along the moving part 132 in a direction perpendicular to the direction of the tungsten wire. With this structure, during the tungsten wire threading process, the heating part can start preheating synchronously, thereby saving time, improving efficiency, and effectively enhancing the safety during the threading operation. Specifically, the heating part 131 includes an upper half and a lower half that are parallel or substantially parallel to each other. A heating device, such as a heating rod, is provided inside or on the surface of the upper half and / or the lower half. The tungsten wire passes through the gap between the upper half and the lower half, and thus the tungsten wire can be heated by the heating device of the upper half and / or the lower half. In an embodiment of the present invention, the first side walls of the upper half and the lower half are connected to each other, such that the cross-section of the heating part 131 in the direction of the tungsten wire is in a "C" shape. The moving part 132 is used to enable the heating part 131 to translate in a direction perpendicular to the direction of the tungsten wire. In an embodiment of the present invention, the moving part 132 includes a guide rail, a slider, a ball screw, and a driving motor. The guide rail is arranged above or below the tungsten wire path and is perpendicular or substantially perpendicular to the tungsten wire. The slider is correspondingly arranged on the surface of the upper half or the lower half of the heating part 131. One end of the ball screw is connected to the driving motor, and the other end is connected to the heating part 131. The driving motor drives the ball screw to rotate, thereby enabling the heating part 131 to translate along the guide rail. It should be understood that in other embodiments of the present invention, other translation mechanisms can also be used to achieve the movement of the heating part, such as belt drive, chain drive, or manual operation, etc.

[0044] During the process of heating the tungsten wire, due to the use of an indirect heating method, in order to improve the accuracy of temperature control, the distance between the tungsten wire and the heating module should be as small as possible. However, if the distance is too small, it may cause the tungsten wire to contact the heating module, thereby resulting in damage. To solve this problem, in an embodiment of the present invention, as Figure 5As shown, the heating module heats the tungsten wire by using a U-shaped or W-shaped heating tube 501. At the same time, in order to prevent the heating tube 501 from fluctuating during the heating process and then touching the tungsten wire, the two ends of the U-shaped or W-shaped heating tube are compacted with thermal insulation material 502. The U-shaped or W-shaped heating tube has high thermal efficiency and uniform heat generation, which can meet the requirements of tungsten wire drawing for temperature uniformity. In order to ensure temperature uniformity, the thermal insulation material cannot cover the heating tube too much. In one embodiment of the present invention, the distance that the heating tube is covered by the thermal insulation material does not exceed 1 / 2 of the length of the bend of the U-shaped heating tube or the W-shaped heating tube, and is preferably 1 / 4. In one embodiment of the present invention, the distance that the heating tube is covered by the thermal insulation material is between 1.5cm and 2.5cm, and is preferably 2cm. As mentioned above, in one embodiment of the present invention, the heating module adopts a multi-stage heating method, so the heating module includes a first heating tube and a second heating tube, wherein the second heating tube is arranged downstream of the first heating tube along the tungsten wire routing direction, and the temperatures of the first heating tube and the second heating tube can be set according to the first temperature zone and the second temperature zone as mentioned above, for example, the heating temperature of the second heating tube is set lower than that of the first heating tube. For another example, the difference between the heating temperatures of the first heating tube and the second heating tube can be set between 10°C and 100°C, preferably 50°C.

[0045] In another embodiment of the present invention, the heating module uses a prefabricated heating block to heat the tungsten wire, and the prefabricated heating block has good temperature uniformity. Figure 6 As shown, the prefabricated heating block includes a heating wire 601 and an insulating heat-conducting layer 602 covering the heating wire. After the prefabricated heating block is powered on, the heating wire starts to work and generates heat, and directly heats the insulating heat-conducting layer by contact, and finally heats the tungsten wire by thermal radiation. In one embodiment of the present invention, the material of the insulating heat-conducting layer is silicon dioxide. As mentioned above, in one embodiment of the present invention, the heating module adopts a multi-stage heating method, so the heating module includes a first heating block and a second heating block, wherein the second heating block is arranged downstream of the first heating block along the tungsten wire routing direction, and the temperatures of the first heating block and the second heating block can be set according to the first temperature zone and the second temperature zone as mentioned above, respectively. For example, the heating temperature of the second heating block can be set to be lower than that of the first heating block. For another example, the difference in heating temperature between the first heating block and the second heating block can be set between 10°C and 100°C, preferably 50°C.

[0046] In one embodiment of the present invention, the prefabricated heating block is made according to the following steps:

[0047] First, the heating wire is buried in silica powder, but the terminal is exposed; and

[0048] Next, the silicon dioxide powder embedded with the heating wire is heated at high temperature to cause sintering between the powder particles to form a whole prefabricated heating block.

[0049] The die module 104 is used to compress and size the tungsten wire to obtain a tungsten wire of a specified wire diameter. In one embodiment of the present invention, the die module 104 includes a wire drawing die and a die holder. The die holder is arranged below the wire drawing die and includes a heating mechanism, which can heat the wire drawing die so that its temperature is close to or equal to the temperature of the tungsten wire heated by the heating module 103. In one embodiment of the present invention, the heating temperature of the die holder is between 200°C and 700°C.

[0050] Fig. 9 The structural schematic diagram of the wire drawing die according to one embodiment of the present invention is shown. Fig. 9 As shown, in one embodiment of the present invention, the wire drawing die includes a bushing 141 and a core 142. The bushing 141 is arranged on the periphery of the core 142. The core 142 is a polycrystalline diamond core, the diamond content in the polycrystalline diamond core is 90%-98%, and the diamond in the polycrystalline diamond core includes nano-diamond grains and micron diamond grains, wherein the grain diameter of the nano-diamond grains is less than or equal to 50 nanometers, the grain diameter of the micron diamond grains is less than or equal to 10 microns, and the mass proportion of the micron diamond grains is less than or equal to 46%. The bushing 141 can be a metal material, for example, cast iron, stainless steel, copper, etc. There is a processing hole at the center of the bushing 141 and the core 142. During the tungsten wire drawing process, the tungsten wire is compressed and stretched to the required diameter through the processing hole.

[0051] like Fig. 9 As shown, the processing hole includes a compression zone 143, a sizing zone 144 and an outlet zone 145. The compression zone 143, the sizing zone 144 and the outlet zone 145 are arranged in sequence in the direction from the entrance to the outlet of the processing hole, the diameter of the compression zone 143 gradually decreases in the direction from the entrance to the outlet of the processing hole, and the diameter of the outlet zone 145 gradually increases in the direction from the entrance to the outlet of the processing hole. The angle of the cone angle θ formed by the diameter change of the compression zone 143 and / or the outlet zone 145 is less than or equal to 18°, and the length of the sizing zone is less than or equal to 0.3 mm.

[0052] The tower wheel module 105 is arranged behind the die module 104 along the tungsten wire routing direction. The sliding friction between the tower wheel module 105 and the tungsten wire can provide traction force for the tungsten wire. After being drawn by the die, the tungsten wire is drawn around the tower wheel module for at least half a circle and then pulled back to the graphite emulsion module for the next drawing operation. The tower wheel module 105 includes multiple layers of guide wheels. The number of layers of the guide wheels is consistent with the number of wire drawing times, that is, the number of wire drawing dies included in the die module 104. During the tungsten wire drawing process, as the diameter of the tungsten wire continues to decrease, the required traction force also decreases. At the same time, as the wire diameter decreases, the length of the tungsten wire continues to increase. Therefore, in one embodiment of the present invention, the diameter of each layer of the guide wheels of the tower wheel gradually increases. In one embodiment of the present invention, the size of the diameter of each layer of the guide wheels is related to the elongation rate δ of the tungsten wire. 模具 The elongation of the tungsten wire is related to 模具 =(d n-1 2-d n 2) / d n 2 , where d n-1 is the wire diameter of the tungsten wire before entering the nth drawing die, i.e. before the nth drawing, and d n is the diameter of the tungsten wire after being drawn by the nth wire drawing die. In one embodiment of the present invention, the elongation δ of the tungsten wire is 模具 The elongation of the step pulley δ 塔轮 Close to, but slightly greater than the elongation δ of the step pulley 塔轮 , that is, the ratio of the two 模具 :δ 塔轮 ≥1.01, wherein the elongation of the step pulley δ 塔轮 =(D n -D n-1 ) / D n-1 , where D n Refers to the diameter of the nth layer of guide wheels. In one embodiment of the present invention, the tower wheel module 105 is driven by a motor, and the speed of the tower wheel module can be controlled by a controller connected to the motor. In one embodiment of the present invention, the tower wheel module is controlled by a motor as a whole, that is, the guide wheels of each layer rotate synchronously. In another embodiment of the present invention, the guide wheels of each layer of the tower wheel module are controlled by different motors, and then the speeds of different guide wheels can be controlled according to the required elongation. In order to improve the wear resistance of the tower wheel module and avoid the wear of the tower wheel or even contamination of the tungsten wire due to the surface friction between the tungsten wire and the tower wheel module during the traction process, in one embodiment of the present invention, the tower wheel module is made of cast iron or stainless steel, and a layer of cemented carbide or ceramic is compounded on its surface, wherein the cemented carbide can be, for example, tungsten carbide. In addition, in one embodiment of the present invention, in order to provide an optimal friction coefficient, the surface of the tower wheel module is further polished with 600 to 1200 meshes to limit its surface roughness.

[0053] As mentioned above, the tower wheel module can adjust the traction force according to the required tungsten wire diameter, thereby ensuring that the tungsten wire reaches the preset elongation rate. In the multi-axis control scheme, the traction force is adjusted by the rotational speed. However, in the integrated control scheme, since the tower wheel module is a whole, the speed of each layer of the guide wheel is consistent. If the traction force is controlled only by the guide wheel diameter, once the required tungsten wire diameter changes, a different tower wheel module may be required, which greatly reduces the versatility of the tower wheel module. To avoid this situation, in actual operation, the traction force can be adjusted by controlling the number of turns of the tungsten wire around the tower wheel module. In order to further control the adjustment accuracy, in one embodiment of the present invention, such as Figure 2 As shown, a wire splitting guide wheel 108 can also be provided in front of the tower wheel module. The tungsten wire extruded by the wire drawing die is wound around the wire splitting guide wheel and the tower wheel module in sequence, and then the contact length between the tungsten wire and the tower wheel module can be adjusted in steps of half a circle, thereby adjusting the traction force. Since the traction force does not need to be adjusted further during the last wire drawing, the number of wire splitting guide wheels should usually be less than the number of layers of the tower wheel module, preferably one less than the number of guide wheel layers of the tower wheel module.

[0054] The guide wheel assembly 107 includes a plurality of guide wheels. In one embodiment of the present invention, the guide wheel includes a bearing and a housing, wherein the housing is connected to the bearing and can rotate under the drive of the bearing. In order to avoid the shaking of the tungsten wire during the tungsten wire drawing process, thereby affecting the straightness of the tungsten wire, in one embodiment of the present invention, the housing includes a "V"-shaped wire groove. Figure 7 As shown, the bottom of the wire groove includes an arc segment, and the width of the arc segment is slightly larger than the diameter of the tungsten wire, for example, it can be in the range of 110% to 130% of the diameter of the tungsten wire. The setting of the conical surfaces on both sides can guide the metal wire to fall into the bottom of the wire groove and can effectively prevent the tungsten wire from falling off the guide wheel. In order to avoid the guide wheel being damaged by the friction between the tungsten wire and the guide wheel during the wire drawing process, in one embodiment of the present invention, the outer shell of the guide wheel is made of high molecular polyester material. In addition, in order to improve stability, in one embodiment of the present invention, the guide wheel includes at least two bearings, wherein the at least two bearings are concentrically arranged.

[0055] Based on the structure of the high-strength fine tungsten wire drawing equipment as described above, fine drawing of tungsten wire can be achieved. Usually, the fine drawing of tungsten wire can increase the wire diameter from 0.39 mm to about 35 microns. The overall fine drawing process usually requires 25 to 35 dies. Therefore, if the high-strength fine tungsten wire drawing equipment as described above is used, multiple operations are required to complete the fine drawing. Each operation includes:

[0056] First, the heating temperature of the heating module 103 is set according to the current tungsten wire diameter, and preheating is performed;

[0057] Next, the threading operation is performed, so that the tungsten wire passes through the pay-off module 101, the graphite emulsion module 102, the heating module 103, the mold module 104, and the tower wheel module 105 in sequence, wherein the tungsten wire first passes through the first drawing die, and after winding around the first layer of the tower wheel module for a specified number of turns, it is wound back to the graphite emulsion module 102, and so on, after winding around the last layer of the tower wheel module for a specified number of turns, it is pulled out of the tungsten wire drawing equipment through the take-up module 106. In order to prevent the tungsten wire from shaking, a guide wheel group 107 is also provided between the pay-off module 101 and the graphite emulsion module 102, and / or between the mold module 104 and the tower wheel module 105. In order to improve the stress adjustment progress, a wire dividing guide wheel 108 can also be provided in front of the tower wheel module 105. In addition, if a movable heating module is used, the threading operation can be completed while the heating module is preheated;

[0058] Next, the equipment is started, so that the tungsten wire begins to be transmitted along a preset path, that is, first enters the graphite emulsion module 102, and then is evenly coated with graphite emulsion on the surface, and then is heated in the heating module 103, on the one hand to dry the moisture of the graphite emulsion, and on the other hand to make the tungsten wire reach the drawing temperature. The tungsten wire reaching the specified temperature is pulled and extruded through the drawing die, and then returns to the graphite emulsion module after passing through the tower wheel module to continue the next drawing; and

[0059] Finally, after one operation is completed, the mold module is replaced, the heating module temperature is reset, and the operation is continued until the preset tungsten wire diameter is reached.

[0060] Although various embodiments of the present invention are described above, it should be understood that they are presented as examples only and not as limitations. It is obvious to those skilled in the relevant art that various combinations, modifications and changes can be made thereto without departing from the spirit and scope of the present invention. Therefore, the breadth and scope of the present invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should only be defined according to the attached claims and their equivalents.

Claims

1. A prefabricated heating block, characterized in that: It is a block structure and is configured to heat the tungsten wire during the tungsten wire drawing process. The prefabricated heating block includes: a plurality of dispersed heating wires and an insulating heat-conducting layer, the insulating heat-conducting layer is coated on the outside of the heating wire and is made of silicon dioxide. The prefabricated heating block is manufactured according to the following steps: burying the heating wire in silica powder but leaving the terminal exposed; and The silicon dioxide powder embedded with the heating wire is heated at high temperature, so that the powder particles are sintered to form a heating block.

2. A heating module, characterized in that: Comprising at least one prefabricated heating block as described in claim 1.

3. The heating module according to claim 2, characterized in that: The heating temperature T of the prefabricated heating block is determined according to the tungsten wire diameter d: T=(-9*10 3 )d 2 +(4.35*10 3 )d+305, The unit of the tungsten wire diameter is millimeter.

4. A high-strength fine tungsten wire drawing equipment, characterized in that: Comprising the heating module as claimed in claim 2 or 3.

5. The high-strength fine tungsten wire drawing equipment according to claim 4, characterized in that: It also includes a pay-off module, a graphite emulsion module, a mold module, a tower wheel module and a take-up module.

6. The high-strength fine tungsten wire drawing equipment according to claim 5, characterized in that: It also includes a guide wheel group, which is arranged between the wire-paying module and the graphite emulsion module, or between the mold module and the tower wheel module.

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