Method for manufacturing a tapered main shaft for a precious metal stirrer

Abstract

The application discloses a manufacturing method, in particular to a manufacturing method for a main rod with taper of a precious metal stirrer, and belongs to the technical field of design and manufacture of precious metal product production process equipment. The manufacturing method for the main rod with taper of the precious metal stirrer has no stress concentration and can guarantee the use performance.

Description

Technical Field

[0001] This invention relates to a manufacturing method, and more particularly to a manufacturing method for a tapered main rod of a precious metal stirrer, belonging to the field of design and manufacturing technology of precious metal product manufacturing process equipment. Background Technology

[0002] In the production process of borosilicate pharmaceutical glass, the agitator plays a crucial role, primarily stirring the molten glass to eliminate air bubbles and reduce streaks. The design of the agitator directly affects the mixing uniformity of the glass raw materials and production efficiency. Currently, there is a significant technical contradiction in the main rod design of agitators used in the production of borosilicate pharmaceutical glass: to meet the structural strength requirements under high-temperature conditions (typically above 1600℃) and high-viscosity conditions, the traditional straight-rod agitator main rod design is forced to increase the wall thickness and diameter, typically ≥3.5mm thick and ≥50mm in diameter, leading to a significant increase in the amount of precious metals used. To address this, some agitators have incorporated a certain taper on the main rod, setting different diameters at different positions according to the stress conditions of the agitator, with the taper serving as a transition, thus achieving the goal of reducing the weight of precious metals in the agitator main rod. Currently, there are two main types of stirrer rods. One type involves directly machining a small-diameter section to reduce weight, with a tapered connection to the large-diameter section in the middle. This type of rod significantly increases the machining workload and results in substantial loss of precious metals. The other type of stirrer rod with a tapered design primarily uses welding to create the tapered structure. This involves separately manufacturing the large-diameter and small-diameter sections of the main rod, then welding them together to form a single unit. While this method allows for the production of a tapered rod and reduces precious metal loss to some extent, it also has the following two major drawbacks:

[0003] 1. The heat-affected zone of welding induces the precipitation of dispersed ZrO2 along the grain boundaries, resulting in a significant decrease in the material's creep resistance;

[0004] 2. The multi-segment welded structure causes stress concentration, posing a significant risk for subsequent use. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for manufacturing a tapered main rod for a precious metal stirrer that does not have stress concentration and whose performance can be well guaranteed.

[0006] The technical solution adopted to solve the above-mentioned technical problems is: a method for manufacturing a tapered main rod for a precious metal stirrer. The method uses a rolled and welded qualified precious metal thin-walled tube as a large-diameter straight tube main rod blank, and uses multi-die progressive gradient drawing to obtain a precious metal stirrer main rod with a specified taper.

[0007] Furthermore, the precious metal thin-walled tube is made of platinum, platinum-rhodium alloy or dispersion-reinforced platinum material, and the thickness of the precious metal sheet before rolling is 1.8-2.5 mm.

[0008] The preferred method of the above scheme is to anneal the qualified precious metal sheet before rolling it into a tube. The annealing temperature is 1150-1250℃ and the holding time is 42-48min.

[0009] Furthermore, the large-diameter straight tube main rod blank is rolled using a scratch-free rolling process. The rolling rolls of the scratch-free rolling process are first heat-treated, and then chrome-plated on the surface to form a surface with a hardness of not less than HRC60. The chrome plating layer thickness is 0.02 to 0.04 mm. The rolls are made of Cr12MoV or Gcr15 material.

[0010] The preferred method of the above scheme is to use flame melting gas welding process to weld the splice seam after the large-diameter straight pipe main rod blank is rolled. The welding wire material is dispersed platinum, the weld seam is beveled at 45°±2°, and the splice seam gap is controlled between 0-1.0mm.

[0011] Furthermore, the multi-die progressive gradient drawing process for forming the tapered main rod is carried out according to the following steps: First, the large-diameter straight tube main rod blank is drawn step by step to obtain the outer diameter of the large-diameter section of the main rod. Then, using the large-diameter straight tube main rod blank as a reference, the outer diameter of the small-diameter section of the large-diameter straight tube main rod blank is gradually reduced to the specified outer diameter through multi-stage tapered die drawing, and the specified tapered transition section is drawn out accordingly to obtain the finished main rod blank.

[0012] Among them, at least one level of conical die drawing corresponds to one pass of conical die drawing. In each pass of conical die drawing, the size of the small diameter section of the large diameter straight tube main rod blank is gradually reduced to the specified diameter according to the reduction size specified by the drawing conical die of that level.

[0013] The preferred embodiment of the above scheme is that the drawing die includes a tapered outer die and a stepped inner core. The stepped inner core is fitted inside the large-diameter straight tube main rod blank. An inner flange is provided at the drawing end of the large-diameter straight tube main rod blank. The large-diameter straight tube main rod blank and the tapered main rod process tube blanks obtained by drawing in stages are respectively fitted onto the stepped inner core. The tapered transition section of the tapered main rod process tube blank in each pass is formed during the drawing process through the tapered surface of the tapered outer die with the corresponding outer diameter.

[0014] Furthermore, the drawing of the first-stage large-diameter straight tube main rod blank corresponds to one pass of large-diameter straight tube main rod blank drawing. Each pass of large-diameter straight tube main rod blank drawing reduces the outer diameter of the large-diameter straight tube main rod blank by 0.8 to 1.2 mm until the diameter of the large-diameter straight tube main rod blank is reduced to the specified size to obtain the large-diameter straight tube main rod blank. During the drawing process of the large-diameter straight tube main rod blank in each pass, 46# anti-wear hydraulic oil is applied to the surface of the corresponding pass straight tube drawing die.

[0015] The preferred embodiment of the above scheme is that the tapered outer die is made of K20 hard alloy material with a surface hardness ≥88HRA. Both ends of the tapered transition section of the precious metal stirrer main rod are set as smooth transition structures. During the drawing process of the small diameter section and the tapered transition section of the precious metal stirrer main rod, the process billet of the tapered main rod in two adjacent drawing passes needs to be rotated at least 90° before drawing. In the drawing of the process billet of the tapered main rod in each pass, the tapered length b formed by the tapered outer die is ≤5mm. The number of tapered die drawing passes required based on this is k=L2 / b, where b max =5mm, L2 is the length of the tapered transition section of the main rod of the precious metal agitator, in mm; the length L of each drawing pass. k =L0-5(k-1), where L0 is the sum of the lengths of the small-diameter section of the main rod of the precious metal stirrer and the conical transition section of the precious metal stirrer;

[0016] The inner core of the step is made of Cr12MoV material, with a heat treatment hardness between HRC60 and 65, and the surface is plated with Cr, with a Cr layer thickness between 0.02 and 0.04 mm.

[0017] The tapered outer die is fixed to the drawing equipment by a support sleeve made of 45K steel.

[0018] Furthermore, both the large-diameter straight tube billet and the tapered tube billet need to be annealed before their first drawing. The annealing temperature is 1150-1250℃ and the holding time is 42-48 minutes.

[0019] Before rolling the main tube blank of a large-diameter straight pipe, calculate the cutting dimensions of the precious metal sheet according to the following formula.

[0020] T = t + Δt,

[0021] A=(φ 中2 +5)×π,

[0022] L=V / (T×A)+ΔL,

[0023] Where t is the thickness of the main rod in mm, and φ is... 中2The mean diameter of the main rod's large end is in mm, Δt = 0.2 mm and ΔL = 50 mm are process compensation amounts, and V is the precise volume obtained from 3D modeling;

[0024] After drawing, the main rod of the precious metal agitator is obtained by shaping, straightening and ultrasonic cleaning on a lathe.

[0025] The beneficial effects of this invention are as follows: The technical solution provided in this application involves rolling and welding a large-diameter straight tube billet using a precious metal thin-walled plate, and then obtaining a precious metal stirrer main rod with a specified taper through multi-die progressive gradient drawing. This solves the technical problem in the prior art where obtaining tapered main rods of different diameters through direct machining results in significant loss of precious metals. It also solves the technical problem of separately manufacturing large-diameter and small-diameter main rod sections and then welding the tapered sections to form main rods of different diameters, leading to a significant decrease in the material's creep resistance due to the precipitation of dispersed ZrO2 along grain boundaries, and the stress concentration caused by welding. Since the main rods of different diameters in this application are produced by multi-die progressive gradient drawing of a large-diameter precious metal tube billet, there is no need for a large amount of metal material removal or welding operations. Consequently, there is no precipitation of dispersed ZrO2 along grain boundaries or stress concentration, thus achieving the goal of better performance assurance while significantly reducing manufacturing costs. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the main rod involved in the manufacturing method of the tapered main rod of the precious metal stirrer of the present invention;

[0027] Figure 2 This is a schematic diagram of the tapered outer mold involved in the manufacturing method of the tapered main rod for a precious metal stirrer according to the present invention;

[0028] Figure 3 This is a schematic diagram of the stepped inner core involved in the manufacturing method of the tapered main rod of the precious metal stirrer of the present invention;

[0029] Figure 4 This is a schematic diagram illustrating the method for manufacturing a tapered main rod for a precious metal stirrer according to the present invention, which involves using a drawing cone die to draw the main rod.

[0030] The components in the diagram are labeled as follows: 1. Main rod of precious metal stirrer; 2. Stepped inner core; 3. Tapered outer mold; 4. Support sleeve. Detailed Implementation

[0031] like Figure 1 , Figure 2 , Figure 3 as well as Figure 4The diagram illustrates a method for manufacturing a tapered main rod for a precious metal stirrer, provided by this invention, which eliminates stress concentration and ensures good performance. The method uses a rolled and welded qualified precious metal thin-walled tube as a large-diameter straight main rod blank, and employs multi-die progressive gradient drawing to obtain the precious metal stirrer main rod 1 with a specified taper. The technical solution provided in this application involves rolling and welding a precious metal thin-walled plate into a large-diameter straight main rod blank, and then obtaining the precious metal stirrer main rod with a specified taper through multi-die progressive gradient drawing. This invention solves the technical problems of significant precious metal loss caused by direct machining of tapered main rods of varying diameters in existing technologies, as well as the problems of significant creep resistance due to the precipitation of dispersed ZrO2 along grain boundaries in the main rods of different diameters formed by separately manufacturing large-diameter and small-diameter sections and then welding the tapered sections. It also addresses the stress concentration caused by welding. Since the main rods of this invention are produced by progressively drawing large-diameter precious metal tube blanks using multiple dies, there is no need for significant metal removal or welding operations. Therefore, there is no precipitation of dispersed ZrO2 along grain boundaries or stress concentration, thus ensuring better performance while significantly reducing manufacturing costs. In comparison to existing technologies, the precious metal thin-walled tube of this application is made of platinum, platinum-rhodium alloy, or dispersion-reinforced platinum material, with a thickness of 1.8-2.5 mm before rolling.

[0032] Accordingly, in order to ensure the sequence of rolling and welding, and considering the actual production situation, the cutting dimensions of the precious metal sheet are calculated according to the following formula before rolling the large-diameter straight main tube blank.

[0033] T = t + Δt,

[0034] A=(φ 中2 +5)×π,

[0035] L=V / (T×A)+ΔL,

[0036] Where t is the thickness of the main rod in mm, and φ is... 中2 The mean diameter of the main rod's large end is in mm, Δt = 0.2 mm and ΔL = 50 mm are process compensation amounts, and V is the precise volume obtained from 3D modeling;

[0037] Before rolling, the qualified precious metal sheets are annealed at 1150–1250℃ for 42–48 minutes. To improve rolling quality, this application employs a scratch-free rolling process for rolling large-diameter straight pipe main rod blanks. The rolling rolls for this process are first heat-treated and then chrome-plated to form a surface with a hardness of not less than HRC60. The chrome plating layer thickness is 0.02–0.04 mm. The rolls are made of Cr12MoV or Gcr15 material. Considering the material properties and actual production needs, this application uses a flame fusion gas welding process for splicing the large-diameter straight pipe main rod blanks after rolling. The welding wire material is dispersed platinum, the weld bevel is 45°±2°, and the splice gap is controlled between 0-1.0 mm.

[0038] Furthermore, as a key improvement in this application, in order to maximize the manufacturing quality of the main rod and reduce manufacturing costs, the tapered main rod 1 formed by multi-die progressive gradient drawing in this application is carried out according to the following steps: First, the large-diameter straight tube main rod blank is drawn step by step to obtain the outer diameter of the large-diameter section of the main rod. Then, based on the large-diameter straight tube main rod blank, the outer diameter of the small-diameter section of the large-diameter straight tube main rod blank is gradually reduced to the specified outer diameter through multi-stage tapered die drawing, and the specified tapered transition section is drawn out accordingly to obtain the finished main rod blank. Among them, at least one stage of tapered die drawing corresponds to one pass of tapered die drawing. Each pass of tapered die drawing gradually reduces the size of the small-diameter section of the large-diameter straight tube main rod blank to the specified diameter according to the reduction size specified by the tapered die of that stage of drawing. At this time, the drawing die includes a tapered outer die 3 and a stepped inner core 2. The stepped inner core 2 is fitted inside the large-diameter straight tube main rod blank. An inner flange 3 is provided at the drawing end of the large-diameter straight tube main rod blank. The large-diameter straight tube main rod blank and the tapered main rod process tube blanks obtained by drawing in stages are respectively fitted onto the stepped inner core 2. The tapered transition section of the tapered main rod process tube blank in each pass is formed during the drawing process through the tapered surface of the tapered outer die 3 with the corresponding outer diameter. More specifically, when drawing a large-diameter straight tube billet into a large-diameter straight tube billet, the drawing of the first-stage large-diameter straight tube billet corresponds to one pass of drawing. Each pass of drawing the large-diameter straight tube billet reduces the outer diameter of the large-diameter straight tube billet by 0.8 to 1.2 mm until the diameter of the large-diameter straight tube billet is reduced to the specified size to obtain the large-diameter straight tube billet. During the drawing process of the large-diameter straight tube billet in each pass, 46# anti-wear hydraulic oil is applied to the surface of the straight tube drawing die of the corresponding pass. Accordingly, in this application, the tapered outer die 3 used in the gradual drawing of the large-diameter straight tube billet into the finished tube billet is made of K20 hard alloy material with a surface hardness ≥88HRA. Both ends of the tapered transition section of the precious metal stirrer tube are designed with smooth transition structures. During the drawing process of the small-diameter section and the tapered transition section of the precious metal stirrer tube, the tube billet of the tapered tube in two adjacent drawing passes must be rotated at least 90° before drawing. The tapered length b formed by the tapered outer die in each drawing pass of the tapered tube is ≤5mm. The number of tapered die drawing passes required based on this is k=L2 / b, where b max =5mm, L2 is the length of the tapered transition section of the main rod of the precious metal agitator, in mm; the length L of each drawing pass. k =L0-5(k-1), where L0 is the sum of the lengths of the small-diameter section of the main rod of the precious metal stirrer and the conical transition section of the precious metal stirrer;

[0039] The inner core 2 of the step is made of Cr12MoV material, with a heat treatment hardness between HRC60 and 65, and the surface is plated with Cr, with a Cr layer thickness between 0.02 and 0.04 mm.

[0040] The tapered outer mold 3 is fixed to the drawing equipment by a support sleeve 4, which is made of 45K steel. Meanwhile, both the large-diameter straight main tube blank and the tapered main tube blank require annealing before their first drawing. The annealing temperature is 1150–1250℃, and the holding time is 42–48 minutes.

[0041] After the drawing is completed, the main rod of the precious metal stirrer is obtained by shaping, straightening and ultrasonic cleaning on a lathe.

[0042] In summary, the technical solution provided in this application also has the following advantages:

[0043] The manufacturing method of the precious metal stirrer with tapered main rod of the present invention breaks through the material deformation problem caused by welding in the traditional manufacturing process of tapered stirrers, realizes the integrated manufacturing of tapered main rod, and effectively improves the strength and service life of stirrer main rod through precise tapering forming method, thus meeting the specific needs of borosilicate pharmaceutical glass production process.

[0044] The technical solution of this application will be further described below through specific embodiments:

[0045] The focus of this invention is to develop a "gradient drawing-multi-mode progressive" method for manufacturing tapered main rods.

[0046] Method for manufacturing straight main pipe:

[0047] The main process flow for straight tube main rods is: blanking, annealing, tube rolling, welding, and drawing.

[0048] a. Material preparation process: Prepare the sheet metal according to the required dimensions of the main rod.

[0049] T=t+Δt

[0050] A=(φ 中2 +5)*π

[0051] L=V / (T*A)+ΔL

[0052] Where t is the thickness of the main rod, and φ 中2 The mean diameter of the main rod's large end is given by Δt = 0.2 mm and ΔL = 50 mm, which are the process compensation amounts. V is the precise volume obtained from the 3D model.

[0053] b. Annealing process: The sheet material is annealed in an annealing furnace at 1200℃ for 45 minutes to improve the plasticity of the material and facilitate subsequent processing.

[0054] c. Rolling process: Special equipment is used to roll the sheet into a circle. In order to avoid the introduction of impurities during the rolling process and to ensure that the sheet is free of scratches, the rolls need to be heat-treated and chrome-plated. The heat treatment hardness must reach HRC60~65, and the surface Cr layer must reach a thickness of 0.02~0.04mm. For this purpose, Cr12MoV or Gcr15 alloys are usually selected to make the rolls.

[0055] d. Welding process: Use an oxyhydrogen flame to weld the pipe. Note that to improve the welding strength, the welding wire should be made of a stronger precious metal material. For example, if the main rod is made of dispersed platinum, platinum-rhodium welding wire can be used. In addition, the length of the plate needs to be chamfered at 45°±2° using a CNC machine tool or a chamfering tool to form a bevel and ensure the strength of the weld.

[0056] e. Drawing: A specialized drawing tool is used for the tubing. To ensure that the material does not wrinkle or break during the drawing process, φ... 外2 +6、φ 外2 +5, φ 外2 +4、φ 外2 +3、φ 外2 +2, φ 外2 +1、φ 外2 For standard pipe drawing dies, φ should be used for the inner die. 内2 The mandrel and drawing die should be made of K20 cemented carbide with a hardness ≥88HRA. The drawing mandrel should be made of Cr12MoV material with a heat treatment hardness of HRC60-65 and a surface Cr layer thickness of 0.02-0.04mm. Before drawing, the inside of the tube needs to be lubricated using 46 anti-wear hydraulic oil specifically for drawing for cooling and lubrication. Drawing can then be performed according to the drawing process to obtain the required straight tube main rod.

[0057] Method for manufacturing the taper of the main rod:

[0058] The main process flow for the taper of the main rod is annealing, taper die design, drawing, and shaping.

[0059] f. Annealing process: The pipe is annealed in an annealing furnace at 1200℃ for 45 minutes to improve the plasticity of the material and facilitate subsequent processing.

[0060] g. Drawing Taper Die Design: When designing the drawing taper die: the outer die material should be K20 cemented carbide, and the drawing core should have a hardness ≥88HRA. The outer layer can be made of 45 steel. Drawing Angle Design: To ensure the taper effect of the main rod after drawing, the angle ∠α2 of the designed drawing taper die core should be consistent with the taper angle ∠α1 of the main rod. Furthermore, to prevent damage to the die or main rod during the drawing process, the angled length of the designed drawing taper die core should be b≤5mm, i.e., the number of dies required should be designed.

[0061] n = L2 / b(b) max =5mm)

[0062] Rounding up n, the φ2 of the next mold is equal to the φ1 of the current mold.

[0063] The inner core mold must be made of Cr12MoV material, with a heat treatment hardness of HRC60-65 and a surface Cr layer thickness of 0.02-0.04 mm. Its diameter must be smaller than the minimum diameter of the main rod, and its length must be greater than the length l3 of the agitator main rod.

[0064] h. Drawing: Drawing must be performed on a dedicated CNC drawing machine. This machine can be set to the end length of the drawing. That is, if the taper is located at the length of the main rod l, the machine will stop after the first drawing l. After the machine stops, the main rod is taken out in the reverse direction, and then the drawing outer die is used to draw from large to small in sequence.

[0065] Pay attention to the following when pulling.

[0066] 1. Before drawing, the inside of the tube needs to be lubricated. Use 46 anti-wear hydraulic oil specifically for drawing to cool and lubricate the tube.

[0067] 2. After each drawing process and replacement with a new drawing die, the main tube should be rotated 90° to prevent taper deviation during tapered drawing.

[0068] 3. After each pull, a new pull length needs to be set on the equipment control panel, i.e., the pull length L. k，

[0069] L k =L0-5(k-1)(k=1,2,...,n)

[0070] Where K represents the number of pulls.

[0071] i. Lower length: Use a lathe tool to cut off the excess material according to the drawing requirements. The grooving tool should be a 9GR200 model. Before cutting, it should be positioned at the taper position and the excess material on both sides should be cut off.

[0072] j. Shaping process: Using tools such as hammers, sandpaper, and files on a lathe, the taper of the drawn piece is trimmed.

[0073] k. Straightening process: The main rod is straightened on a lathe using rollers.

[0074] 1. Cleaning procedure: The main rod can be cleaned using ultrasonic cleaning equipment.

[0075] Example 1

[0076] The following description, in conjunction with the accompanying drawings and examples, further illustrates the design of a tapered stirrer main rod. The main rod has a maximum diameter of 62 mm, a minimum diameter of 48 mm, a total length of 900 mm, and a thickness of 2.0 mm. The material is dispersed platinum.

[0077] a. Material preparation process: Prepare the sheet metal according to the required dimensions of the main rod. Sheet metal thickness T = t + 0.2mm = 2.2mm, sheet metal width A = (φ 中2 +5)×3.14≈205mm, plate length L=main rod volume V / (T×A)+50 allowance=284948 / (2.2×205)≈630mm, main rod volume 284948mm 3 The dimensions of the prepared sheet material, calculated by 3D software based on the drawings, should be 2.2×205×630 mm, and the material should be dispersed platinum.

[0078] b. Annealing process: The sheet material is annealed in an annealing furnace at 1200℃ for 45 minutes to improve the plasticity of the material and facilitate subsequent processing.

[0079] c. Rolling process: Special equipment is used to roll the sheet into a circle. In order to avoid the introduction of impurities during the rolling process and to ensure that the sheet is free of scratches, the rolls need to be heat-treated and chrome-plated. The heat treatment hardness must reach HRC60~65, and the surface Cr layer must reach a thickness of 0.02~0.04mm. For this purpose, Cr12MoV or Gcr15 alloys are usually selected to make the rolls.

[0080] d. Welding process: Use a chamfering tool to chamfer the welding edges at 45°, use platinum-rhodium 10 solder to improve the welding strength, and use an oxyhydrogen flame to weld the pipe.

[0081] e. Drawing Forming: Specialized drawing tools are used to form the tubes. To prevent wrinkling and breakage during the drawing process, external dies of φ68, φ67, φ66, φ65, φ64, φ63, and φ62 are used respectively. A φ58 mandrel is used for the internal die. The external drawing die should be made of K20 cemented carbide with a hardness ≥88HRA. The drawing mandrel should be made of Cr12MoV material, with a heat treatment hardness reaching HRC60~65, and a surface Cr layer thickness of 0.02~0.04mm. Before drawing, the tube interior needs to be lubricated using 46 anti-wear hydraulic oil specifically for cooling and lubrication. Drawing is then performed according to the specified process to obtain the required straight tube main.

[0082] Method for manufacturing the taper of the main rod:

[0083] The main process flow for the taper of the main rod is annealing, taper die design, drawing, and shaping.

[0084] f. Annealing process: The pipe is annealed in an annealing furnace at 1200℃ for 45 minutes to improve the plasticity of the material and facilitate subsequent processing.

[0085] g. Drawing taper die design: Design the die according to the drawings. The process requires n = l2 / b pieces = 40 / 5 = 8 pieces of drawing taper dies. One inner core die is also required.

[0086] h. Drawing Forming: Drawing forming must be performed on a dedicated CNC drawing machine. Set the initial drawing length l = 650, using the largest drawing taper outer die. After the machine stops, reverse the direction and remove the main rod. Then, draw using drawing outer dies from largest to smallest. During drawing, pay attention to the following: 1. Before drawing, lubricate the inside of the tube using 46 anti-wear hydraulic oil specifically for drawing to cool and lubricate the tube. 2. After each drawing, replace the drawing outer die and rotate the main rod tube by 90° to prevent taper deviation during taper drawing. 3. After each drawing, set a new drawing length on the machine control panel, i.e., the drawing lengths should be 650, 645, 640, 635...610 respectively.

[0087] i. Lower length: Use a lathe tool to cut off the excess material according to the drawing requirements. The grooving tool should be a 9GR200 model. Before cutting, it should be positioned at the taper position and the excess material on both sides should be cut off.

[0088] j. Shaping process: The taper drawn out is trimmed on a lathe using tools such as hammers, sandpaper, and files.

[0089] k. Straightening process: The main rod is straightened using rollers on a lathe.

[0090] 1. Cleaning process: The main rod can be cleaned using ultrasonic cleaning equipment.

Claims

1. A method for manufacturing a tapered main rod for a precious metal stirrer, characterized in that: The manufacturing method described above uses a rolled and welded qualified precious metal thin-walled tube as a large-diameter straight tube main rod blank, and adopts multi-die progressive gradient drawing to obtain a precious metal agitator main rod (1) with a specified taper. The thickness of the precious metal thin plate before rolling is 1.8-2.5mm. The multi-die progressive gradient drawing forming of tapered main rod (1) is carried out according to the following steps: first, the large-diameter straight tube main rod blank is drawn step by step to obtain the outer diameter of the large-diameter section of the main rod. Then, based on the large-diameter straight tube main rod blank, the outer diameter of the small-diameter section of the large-diameter straight tube main rod blank is gradually reduced to the specified outer diameter through multi-stage tapered die drawing, and the specified tapered transition section is drawn out accordingly to obtain the finished main rod blank. In this process, at least one level of conical die drawing corresponds to one pass of conical die drawing. In each pass of conical die drawing, the size of the small diameter section of the large-diameter straight tube main rod blank is gradually reduced to the specified diameter according to the reduction size specified by the drawing conical die of that level. The drawing die includes a tapered outer die (3) and a stepped inner core (2). During the drawing process of the small-diameter section and the tapered transition section of the main rod of the precious metal agitator, the process billet of the tapered main rod in two adjacent drawing passes must be rotated at least 90° before drawing. In the drawing of the process billet of the tapered main rod in each pass, the tapered length b formed by the tapered outer die is ≤ 5mm. Based on this, the number of tapered die drawing passes required is k = L2 / b, where b max =5mm, L2 is the length of the tapered transition section of the main rod of the precious metal agitator, in mm; L is the length of each drawing pass. k =L0-5(k-1), where L0 is the sum of the lengths of the small-diameter section of the main rod of the precious metal stirrer and the conical transition section of the precious metal stirrer. Before rolling the main tube blank of a large-diameter straight pipe, calculate the cutting dimensions of the precious metal sheet according to the following formula. T = t + Δt, A=(φ 中2 +5)×π, L = V / (T×A) + ΔL, Where t is the thickness of the main rod in mm, and φ is... 中2 The mean diameter of the main rod's large end is in mm, Δt=0.2mm and ΔL=50mm are process compensation amounts, and V is the precise volume obtained from 3D modeling.

2. The method for manufacturing a tapered main rod for a precious metal stirrer according to claim 1, characterized in that: Precious metal thin-walled tubes are made of platinum or platinum-rhodium alloy materials.

3. The method for manufacturing a tapered main rod for a precious metal stirrer according to claim 1, characterized in that: The precious metal thin-walled tube is made of dispersion-reinforced platinum material.

4. The method for manufacturing a tapered main rod for a precious metal stirrer according to claim 1, 2, or 3, characterized in that: Before rolling precious metal sheets into tubes, the cut precious metal sheets are first annealed at a temperature of 1150-1250℃ for 42-48 minutes.

5. The method for manufacturing a tapered main rod for a precious metal stirrer according to claim 4, characterized in that: The large-diameter straight tube main rod blank is rolled using a scratch-free rolling process. The rolling rolls of the scratch-free rolling process are first heat-treated, and then chrome-plated on the surface to form a surface with a hardness of not less than HRC60. The chrome plating layer thickness is 0.02 to 0.04 mm. The rolls are made of Cr12MoV or Gcr15 material.

6. The method for manufacturing a tapered main rod for a precious metal stirrer according to claim 5, characterized in that: After the large-diameter straight pipe main rod blank is rolled, the splice seam is welded by flame melting gas welding process. The welding wire material is dispersed platinum. The weld seam has a bevel of 45°±2° and the splice seam gap is controlled between 0-1.0mm.

7. The method for manufacturing a tapered main rod for a precious metal stirrer according to claim 1, characterized in that: The stepped inner core (2) is fitted inside the large-diameter straight tube main rod blank. An inner flange is provided at the drawing end of the large-diameter straight tube main rod blank. The large-diameter straight tube main rod blank and the tapered main rod process tube blank obtained by step drawing are respectively fitted on the stepped inner core (2). The tapered transition section of each tapered main rod process tube blank is formed during the drawing process through the tapered surface of the tapered outer mold (3) with the corresponding outer diameter.

8. The method for manufacturing a tapered main rod for a precious metal stirrer according to claim 6, characterized in that: The drawing of the first-stage large-diameter straight tube main rod blank corresponds to one pass of large-diameter straight tube main rod blank drawing. In each pass of large-diameter straight tube main rod blank drawing, the outer diameter of the large-diameter straight tube main rod blank is reduced by 0.8 to 1.2 mm until the diameter of the large-diameter straight tube main rod blank is reduced to the specified size to obtain the large-diameter straight tube main rod blank. During the drawing process of the large-diameter straight tube main rod blank in each pass, 46# anti-wear hydraulic oil is applied to the surface of the straight tube drawing die of the corresponding pass.

9. The method for manufacturing a tapered main rod for a precious metal stirrer according to claim 7, characterized in that: The tapered outer mold (3) is made of K20 hard alloy material with a surface hardness ≥88HRA. The two ends of the tapered transition section of the precious metal stirrer main rod are respectively set as smooth transition structures. The inner core of the step (2) is made of Cr12MoV material, with a heat treatment hardness between HRC60 and 65, and the surface is plated with Cr, with a Cr layer thickness between 0.02 and 0.04 mm. The tapered outer mold (3) is fixed to the drawing equipment by a support sleeve (4), which is made of 45K steel.

10. The method for manufacturing a tapered main rod for a precious metal stirrer according to claim 9, characterized in that: Both the large-diameter straight tube billet and the tapered tube billet need to be annealed before their first drawing. The annealing temperature is 1150-1250℃ and the holding time is 42-48min. After the drawing is completed, the appearance is shaped and straightened on a lathe, and ultrasonic cleaning is performed to obtain the main rod of the precious metal stirrer (1).

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