Precious Metal Large Diameter Thin-Walled Pipe Forming Die and Forming Method

Abstract

This invention relates to the field of precious metal product manufacturing technology, and particularly to a forming mold and method for forming large-diameter thin-walled bent pipes of precious metal. The forming mold includes a first mold body and a second mold body. The forming method involves first fabricating the forming mold, then forming the precious metal raw material on the forming mold, and finally obtaining the thin-walled bent pipe through cutting and welding. This invention provides a forming mold and method for forming large-diameter thin-walled bent pipes of precious metal, suitable for forming pipes with a diameter of 40mm or more and a wall thickness of 0.5-2.0mm. The forming mold has a simple structure and is easy to operate. The thickness tolerance of the formed thin-walled bent pipe is within ±0.05mm, ensuring uniform wall thickness. This solves the problems of uneven internal surface and slight wrinkles caused by traditional bending methods. Furthermore, the high-temperature melting and welding method makes the thin-walled bent pipe less prone to cracking, significantly improving the forming quality of large-diameter thin-walled bent pipes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precious metal product manufacturing, and particularly relates to a precious metal large-diameter thin-wall elbow forming die and a forming method thereof. BACKGROUND

[0002] Various high-end glasses commonly use precious metals such as platinum, platinum-rhodium alloy and platinum-yellow alloy as basic materials of their smelting devices. The smelting device is usually composed of a circular pipe, an elliptical pipe, a transition pipe and an elbow pipe. The elbow pipe is used frequently. A common forming method of the precious metal thin-wall elbow pipe is to directly bend the circular pipe into the elbow pipe through equipment. This forming method is suitable for forming the precious metal thin-wall elbow pipe with a pipe diameter of less than 40 mm. For the precious metal thin-wall elbow pipe with a pipe diameter of more than 40 mm, the large-diameter thin-wall elbow pipe obtained by this forming method has a thickness obviously thinner on the outside than on the inside, and the inside also has problems such as roughness and a little wrinkle. The forming quality of the large-diameter thin-wall elbow pipe is poor, which further affects the quality of the glass. SUMMARY

[0003] The present application solves the technical problem of providing a precious metal large-diameter thin-wall elbow forming die capable of improving the forming quality of the large-diameter thin-wall elbow pipe.

[0004] The technical solution adopted by the present application to solve the technical problem is: the precious metal large-diameter thin-wall elbow forming die comprises a first die body and a second die body. The first die body is an axisymmetric figure. The first die body comprises a first cylindrical table, a circular-arc table, a second cylindrical table and a first connecting part. The longitudinal section shape of the outer side wall of the circular-arc table is a circular arc inwardly concave. The first cylindrical table is arranged on the circular-arc table. The circular-arc table is arranged on the second cylindrical table. The second cylindrical table is arranged on the first connecting part. The outer side wall of the first cylindrical table is smoothly connected with the outer side wall of the circular-arc table.

[0005] The second die body is an axisymmetric figure. The second die body comprises a circular-arc ring table, a third cylindrical table and a second connecting part. The circular-arc ring table is arranged on the third cylindrical table. The third cylindrical table is arranged on the second connecting part. The longitudinal section shape of the circular-arc ring table is a circular arc upwardly convex. The central part of the third cylindrical table is provided with a cylindrical accommodation slot. The outer side wall of the circular-arc ring table is smoothly connected with the outer side wall of the third cylindrical table. The inner side wall of the circular-arc ring table is smoothly connected with the side wall of the cylindrical accommodation slot.

[0006] Further, the inner diameter of the thin-wall elbow pipe is Φ, the pipe wall thickness of the thin-wall elbow pipe is t, and the inner diameter of the elbow pipe on the inside is Φin.

[0007] The diameter of the longitudinal section circular arc of the circular arc ring platform is R2, R2=Φ / 2+t-(0.05-0.10)mm, the depth of the cylindrical giving way slot is 5-8mm, the diameter of the transverse section circular arc of the cylindrical giving way slot is Φ3, Φ3=Φin+2t+(0.05-0.10)mm, and the diameter of the transverse section circular arc of the third cylindrical platform is Φ4, Φ4=Φin+4R2-(0.05-0.10)mm.

[0008] The diameter of the longitudinal section circular arc of the circular arc ring platform is R2, R2=Φ / 2+t-(0.05-0.10)mm, the depth of the cylindrical giving way slot is 5-8mm, the diameter of the transverse section circular arc of the cylindrical giving way slot is Φ3, Φ3=Φin+2t+(0.05-0.10)mm, and the diameter of the transverse section circular arc of the third cylindrical platform is Φ4, Φ4=Φin+4R2-(0.05-0.10)mm.

[0009] Further, the application also discloses a cylindrical gasket which is detachably matched with the cylindrical giving way slot.

[0010] In addition, the application solves the technical problem of providing a precious metal large-diameter thin-wall elbow pipe forming method with good forming quality.

[0011] The precious metal large-diameter thin-wall elbow pipe forming method comprises the following steps:

[0012] a. manufacturing the precious metal large-diameter thin-wall elbow pipe forming die;

[0013] b. preparing a precious metal raw material, wherein the shape of the precious metal raw material is circular, the diameter of the circular shape of the precious metal raw material is Φ2+(10-20)mm, and the thickness of the precious metal raw material is t+0.25-0.35mm;

[0014] c. clamping and installing the first die body on a rotary lathe or a lathe through the first connecting part, and placing the precious metal raw material on the first die body, wherein the center of the precious metal raw material is located on the central axis of the first die body;

[0015] d. working the rotary lathe or the lathe, and simultaneously adopting a spinning tool to spin the precious metal raw material into the outer contour shape of the first die body, and taking out the first semi-finished product from the first die body, wherein the first semi-finished product comprises a first cylindrical platform part, a first circular arc platform part and a circular platform part, the first circular arc platform part is located in the middle of the circular platform part, and the first cylindrical platform part is arranged on the first circular arc platform part;

[0016] e. placing the first semi-finished product on the second die body after being turned over by 180°, wherein the central axis of the first semi-finished product is located on the same straight line as the central axis of the second die body, the first circular arc platform part and the first cylindrical platform part are located in the cylindrical giving way slot, and the circular platform part is located on the circular arc ring platform;

[0017] f. The second mold is clamped and mounted on a spinning lathe or a lathe through the second connecting part, the spinning lathe or the lathe is operated, and at the same time, the first semi-finished product is spun into the circular arc ring table outer contour shape of the second mold through the spinning tool, and the second semi-finished product is obtained after being taken out of the second mold, the second semi-finished product comprises the first cylindrical table part, the first circular arc table part, the second cylindrical table part and the second circular arc table part, one end of the second circular arc table part is connected with the first circular arc table part, the other end of the second circular arc table part is connected with the second cylindrical table part, and the first cylindrical table part and the second cylindrical table part are arranged in parallel with each other;

[0018] g. According to the bending degree and length of the thin-walled bent pipe, the second semi-finished product is cut by a cutting machine, the cutting is along the longitudinal direction of the second semi-finished product, and at least two third semi-finished products are obtained;

[0019] h. The first cylindrical table part and the second cylindrical table part in the third semi-finished product are subjected to folding treatment, the folding angle is 90°, the first cylindrical table part is perpendicular to the first circular arc table part after the folding treatment, the second cylindrical table part is perpendicular to the second circular arc table part, the two third semi-finished products are buckled together to form a thin-walled bent pipe shape, and the two third semi-finished products are welded together by high-temperature melting of the first cylindrical table part and the second cylindrical table part, so that the finished thin-walled bent pipe is obtained.

[0020] Preferably, in step a, the first mold and the second mold are subjected to quenching treatment, the quenching hardness is above 45HRC, then the first mold and the second mold are plated with hard chromium and subjected to polishing treatment.

[0021] Preferably, in step b, the precious metal raw material is annealed in an annealing furnace at 1100-1350°C for 30-40 minutes, and then is subjected to flattening on a flattening device, and the flatness after flattening is within ±0.15mm.

[0022] Preferably, in step d, after the first semi-finished product is obtained, the surface of the first semi-finished product is cleaned, and then is subjected to leakage detection.

[0023] Preferably, in step e, the bottom of the first cylindrical table part is in contact with a cylindrical gasket, and the height of the cylindrical gasket is 2-3mm.

[0024] Preferably, in step f, after the second semi-finished product is obtained, the surface of the second semi-finished product is cleaned, and then is subjected to leakage detection.

[0025] Preferably, in step g, after the third semi-finished product is obtained, the first cylindrical table part and the second cylindrical table part of the third semi-finished product are trimmed, and the length of the first cylindrical table part and the second cylindrical table part after trimming is between 0.5-1.0mm.

[0026] In step h, the first cylindrical platform after the folding treatment is located outside the first arc platform, and the second cylindrical platform is located outside the second arc platform.

[0027] The precious metal large-diameter thin-wall elbow forming die and the forming method thereof have the advantages that the forming die and the forming method thereof are suitable for forming a precious metal thin-wall elbow with a pipe diameter of 40 mm or more and a pipe wall thickness of 0.5-2.0 mm. The forming die has a simple structure and is easy to operate. The thickness tolerance of the formed thin-wall elbow is within ±0.05 mm, the wall thickness of the elbow is uniform, the problems of internal roughness and a few wrinkles caused by the traditional elbow forming method are solved, the thin-wall elbow is not prone to cracking through high-temperature fusion welding, the forming quality of the large-diameter thin-wall elbow is significantly improved, and the large-diameter thin-wall elbow is suitable for large-scale use. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a structural schematic diagram of the first mold;

[0029] Figure 2 is a front view schematic diagram of the first mold;

[0030] Figure 3 is a structural schematic diagram of the second mold;

[0031] Figure 4 is a front view schematic diagram of the second mold;

[0032] Figure 5 is a plane schematic diagram of the thin-wall elbow;

[0033] Figure 6 is a schematic diagram of step c in the forming of the precious metal large-diameter thin-wall elbow;

[0034] Figure 7 is a schematic diagram of step d in the forming of the precious metal large-diameter thin-wall elbow;

[0035] Figure 8 is a schematic diagram of step e in the forming of the precious metal large-diameter thin-wall elbow Figure 1 ;

[0036] Figure 9 is a schematic diagram of step e in the forming of the precious metal large-diameter thin-wall elbow Figure 2 ;

[0037] Figure 10 is a schematic diagram of the third semi-finished product;

[0038] Figure 11 is a schematic diagram of step f in the forming of the precious metal large-diameter thin-wall elbow;

[0039] Figure 12 is a schematic diagram of step h in the forming of the precious metal large-diameter thin-wall elbow;

[0040] Figure 13 is the schematic diagram of step i when forming the large-diameter thin-wall elbow pipe of noble metal Figure 1 ;

[0041] Figure 14 is the schematic diagram of step i when forming the large-diameter thin-wall elbow pipe of noble metal Figure 2 ;

[0042] Figure 15 is the schematic diagram of the first semi-finished product;

[0043] Figure 16 is the schematic diagram of the second semi-finished product;

[0044] marked: the first mold concrete 1, the first cylindrical table 11, the arc table 12, the second cylindrical table 13, the first connecting part 14, the second mold concrete 2, the arc ring table 21, the third cylindrical table 22, the second connecting part 23, the cylindrical displacement slot 24, the cylindrical gasket 25, the thin-wall elbow pipe 3, the noble metal raw material 30, the first semi-finished product 31, the first cylindrical table part 311, the first arc table part 312, the arc table part 313, the second semi-finished product 32, the second cylindrical table part 321, the second arc table part 322, the third semi-finished product 33. DETAILED DESCRIPTION

[0045] The application will be further described below in combination with the drawings and specific embodiments.

[0046] As shown in the drawings, Figures 1 to 4 the noble metal large-diameter thin-wall elbow pipe forming mold of the application comprises a first mold concrete 1 and a second mold concrete 2, the shape of the first mold concrete 1 is an axisymmetric figure, the first mold concrete 1 comprises a first cylindrical table 11, an arc table 12, a second cylindrical table 13 and a first connecting part 14, the longitudinal section shape of the outer side wall of the arc table 12 is an inwardly concave arc, the first cylindrical table 11 is arranged on the arc table 12, the arc table 12 is arranged on the second cylindrical table 13, the second cylindrical table 13 is arranged on the first connecting part 14, and the outer side wall of the first cylindrical table 11 is smoothly connected with the outer side wall of the arc table 12.

[0047] the shape of the second mold concrete 2 is an axisymmetric figure, the second mold concrete 2 comprises an arc ring table 21, a third cylindrical table 22 and a second connecting part 23, the arc ring table 21 is arranged on the third cylindrical table 22, the third cylindrical table 22 is arranged on the second connecting part 23, the longitudinal section shape of the arc ring table 21 is an upwardly convex arc, the middle of the third cylindrical table 22 is provided with a cylindrical displacement slot 24, the outer side wall of the arc ring table 21 is smoothly connected with the outer side wall of the third cylindrical table 22, and the inner side wall of the arc ring table 21 is smoothly connected with the side wall of the cylindrical displacement slot 24.

[0048] Again as shown in the drawings, Figure 1 ,Figure 2 As shown in the figure, the smooth connection of the outer side wall of the first cylindrical table 11 and the outer side wall of the circular arc table 12 means that the outer side wall of the first cylindrical table 11 and the outer side wall of the circular arc table 12 are directly connected together. As shown in the figure Figure 3 、 Figure 4 As shown in the figure, the smooth connection of the outer side wall of the circular arc ring table 21 and the outer side wall of the third cylindrical table 22 means that the outer side wall of the circular arc ring table 21 and the outer side wall of the third cylindrical table 22 are directly connected together, and the smooth connection of the inner side wall of the circular arc ring table 21 and the side wall of the cylindrical accommodation slot 24 means that the inner side wall of the circular arc ring table 21 and the side wall of the cylindrical accommodation slot 24 are directly connected together.

[0049] As shown in the figure Figure 5 , the inner diameter of the thin-walled elbow pipe 3 formed by the present application is Φ, the pipe wall thickness of the thin-walled elbow pipe 3 is t, the inner diameter of the elbow of the thin-walled elbow pipe 3 is Φin, the center diameter of the elbow of the thin-walled elbow pipe 3 is Φmid, and the outer diameter of the elbow of the thin-walled elbow pipe 3 is Φout. In order to ensure and improve the forming quality of the thin-walled elbow pipe 3, as shown in the figure Figure 2 、 Figure 4 , the diameter of the longitudinal section circular arc of the outer side wall of the circular arc table 12 is R1, R1 = Φ / 2 + t - (0.05-0.10) mm, the height of the first cylindrical table 11 is 3-5 mm, the transverse section circular diameter of the first cylindrical table 11 is Φ1, Φ1 = Φin-2t-(0.15-0.25) mm, and the transverse section circular diameter of the second cylindrical table (13) is Φ2, Φ2 = Φin+4R1+(30-50) mm;

[0050] The diameter of the longitudinal section circular arc of the circular arc ring table 21 is R2, R2 = Φ / 2 + t - 0.05-0.10 mm, the depth of the cylindrical accommodation slot 24 is 5-8 mm, the transverse section circular diameter of the cylindrical accommodation slot 24 is Φ3, Φ3 = Φin+2t+(0.05-0.10) mm, and the transverse section circular diameter of the third cylindrical table 22 is Φ4, Φ4 = Φin+4R2-(0.05-0.10) mm.

[0051] As shown in the figure Figures 6 to 16 , the precious metal large-diameter thin-walled elbow pipe forming method comprises the following steps:

[0052] a. Making the precious metal large-diameter thin-walled elbow pipe forming mold described above;

[0053] b. Preparing a precious metal raw material 30, the shape of the precious metal raw material 30 is circular, the circular diameter of the precious metal raw material 30 is Φ2+(10-20) mm, and the thickness of the precious metal raw material 30 is t+0.25-0.35 mm;

[0054] c. The first mold body 1 is clamped and installed on a lathe or a turning machine through the first connecting part 14, and the precious metal raw material 30 is placed on the first mold body 1, with the center of the precious metal raw material 30 located on the central axis of the first mold body 1.

[0055] d. The lathe or turning machine operates, and at the same time, the precious metal raw material 30 is spun into the outer contour shape of the first mold body 1 using a spinning tool. After being taken out from the first mold body 1, the first semi-finished product 31 is obtained. The first semi-finished product 31 includes a first cylindrical platform 311, a first arc platform 312, and a frustum 313. The first arc platform 312 is located in the middle of the frustum 313, and the first cylindrical platform 311 is disposed on the first arc platform 312.

[0056] e. After the first semi-finished product 31 is flipped 180°, it is placed on the second mold body 2. At this time, the centerline axis of the first semi-finished product 31 and the centerline axis of the second mold body 2 are on the same straight line. The first arc platform 312 and the first cylindrical platform 311 are located in the cylindrical relief groove 24, and the platform 313 is located on the arc ring platform 21.

[0057] f. The second mold body 2 is clamped and installed on a lathe or a turning machine via the second connecting part 23. The lathe or turning machine works, and at the same time, a spinning tool is used to spin the frustum portion 313 of the first semi-finished product 31 into the outer contour shape of the arc ring 21 of the second mold body 2. After being taken out from the second mold body 2, the second semi-finished product 32 is obtained. The second semi-finished product 32 includes a first cylindrical frustum portion 311, a first arc ring portion 312, a second cylindrical frustum portion 321, and a second arc ring portion 322. One end of the second arc ring portion 322 is connected to the first arc ring portion 312, and the other end of the second arc ring portion 322 is connected to the second cylindrical frustum portion 321. The first cylindrical frustum portion 311 and the second cylindrical frustum portion 321 are arranged parallel to each other.

[0058] g. Based on the curvature and length of the thin-walled bend 3, the second semi-finished product 32 is cut using a cutting machine. A laser cutting machine is preferred. The cutting is performed along the longitudinal direction of the second semi-finished product 32 to obtain at least two third semi-finished products 33.

[0059] h. Fold the first cylindrical truncated section 311 and the second cylindrical truncated section 321 of the third semi-finished product 33 at an angle of 90°. After folding, the first cylindrical truncated section 311 is perpendicular to the first arc truncated section 312, and the second cylindrical truncated section 321 is perpendicular to the second arc truncated section 322. Then, fasten the two third semi-finished products 33 together to form a thin-walled bent tube 3 shape. Weld the two third semi-finished products 33 together by melting the first cylindrical truncated section 311 and the second cylindrical truncated section 321 at high temperature to obtain the finished thin-walled bent tube 3.

[0060] In order to improve the quality and use effect of the first mold body 1 and the second mold body 2, in step a, the first mold body 1 and the second mold body 2 are quenched, the quenching hardness is above 45HRC, then the first mold body 1 and the second mold body 2 are plated with hard chrome and polished.

[0061] In order to ensure the forming quality of the thin-walled bent pipe 3, the precious metal raw material 30 is annealed in an annealing furnace at 1100-1350℃ for 30-40 minutes, and then is leveled on a leveling device, and the flatness is within ±0.15mm after leveling.

[0062] In step d, the precious metal raw material 30 is spun into the outer contour shape of the first mold body 1, specifically, the first cylindrical platform 311 is formed at the first cylindrical platform 11, the first circular arc platform 312 is formed at the circular arc platform 12, and the circular platform 313 is formed at the second cylindrical platform 13. In order to ensure the accuracy of the arc surface of the first circular arc platform 312, the accuracy of the arc surface is measured during spinning, and the accuracy of the arc surface is controlled within t±0.05mm. In order to improve the forming stability of the thin-walled bent pipe 3, after obtaining the first semi-finished product 31, the surface of the first semi-finished product 31 is cleaned, and then leakage detection is performed.

[0063] In step e, in order to reduce the possibility of damage to the first cylindrical platform 311, a cylindrical gasket 25 is also provided, which is detachably matched in the cylindrical accommodation groove 24, the height of the cylindrical gasket 25 is 2-3mm, and the material of the cylindrical gasket 25 is PA6 nylon. During forming, the bottom of the first cylindrical platform 311 is in contact with the cylindrical gasket 25.

[0064] In step f, the circular platform 313 of the first semi-finished product 31 is spun into the outer contour shape of the circular arc ring platform 21 of the second mold body 2 by using a spinning tool, that is, the circular platform 313 is formed into the second circular arc platform 322 and the second cylindrical platform 321 at the circular arc ring platform 21 and the third cylindrical platform 22. In order to ensure the accuracy of the arc surface of the second circular arc platform 322, the accuracy of the arc surface is measured during spinning, and the accuracy of the arc surface is controlled within t±0.05mm. In order to further improve the forming stability of the thin-walled bent pipe 3, after obtaining the second semi-finished product 32, the surface of the second semi-finished product 32 is cleaned, and then leakage detection is performed.

[0065] In step g, since the first cylindrical platform 311 and the second cylindrical platform 321 in the third semi-finished product 33 are straight walls, the first cylindrical platform 311 and the second cylindrical platform 321 function as high-temperature melting to weld the two third semi-finished products 33 together. In order to facilitate the effect of high-temperature melting welding, after obtaining the third semi-finished product 33, the first cylindrical platform 311 and the second cylindrical platform 321 of the third semi-finished product 33 are trimmed, and the length of the first cylindrical platform 311 and the second cylindrical platform 321 after trimming is between 0.5-1.0mm.

[0066] In order to further improve the forming quality of the thin-walled elbow pipe 3, the first cylindrical platform 311 is located outside the first arc platform 312 after the folding treatment, and the second cylindrical platform 321 is located outside the second arc platform 322. And the height of the high-temperature melting welding seam is about 1.1-1.3 times the pipe wall thickness of the thin-walled elbow pipe 3.

[0067] In summary, the precious metal large-diameter thin-walled elbow pipe forming die and the forming method thereof are suitable for forming a precious metal thin-walled elbow pipe with a pipe diameter of 40mm or more and a pipe wall thickness of 0.5-2.0mm. The forming die has a simple structure and is easy to operate. The thickness tolerance of the formed thin-walled elbow pipe is within ±0.05mm, which ensures the uniformity of the elbow pipe wall thickness, solves the problems of internal roughness and a few wrinkles caused by traditional elbow pipe forming methods, and makes the thin-walled elbow pipe 3 less prone to cracking through high-temperature melting welding. The forming quality of the large-diameter thin-walled elbow pipe is significantly improved, which is conducive to large-scale use.

[0068] Embodiment

[0069] The parameters of the thin-walled elbow pipe 3 are as follows: the material is PtRh10, the inner diameter is 80mm, the pipe wall thickness is t1.5mm, and the inner, center and outer diameters of the elbow pipe are 240mm, 320mm and 400mm respectively.

[0070] The precious metal large-diameter thin-walled elbow pipe forming method comprises the following steps:

[0071] a, the forming die of the large-diameter thin-walled bend pipe of noble metal is made, the diameter of the longitudinal section arc of the outer side wall of the arc ring table 12 in the first die body 1 is 42.9 mm, the height of the first cylindrical table 11 is 3 mm, the transverse section circle diameter of the first cylindrical table 11 is 236.8 mm, and the transverse section circle diameter of the second cylindrical table 13 is 430 mm; the diameter of the longitudinal section arc of the arc ring table 21 in the second die body 2 is 39.9 mm, the depth of the cylindrical relief groove 24 is 8 mm, the transverse section circle diameter of the cylindrical relief groove 24 is 243.1 mm, and the transverse section circle diameter of the third cylindrical table 22 is 399.9 mm; the first die body 1 and the second die body 2 are quenched, the quenching hardness is above 48HRC, then the first die body 1 and the second die body 2 are plated with hard chromium and polished.

[0072] b, the noble metal raw material 30 is prepared, the shape of the noble metal raw material 30 is circular, the diameter of the noble metal raw material 30 is 450 mm, and the thickness of the noble metal raw material 30 is 1.75 mm; the noble metal raw material 30 is annealed in an annealing furnace at 1250℃ for 30 minutes, and then is flattened on a flattening device after natural cooling, and the flatness is within ±0.10 mm after flattening.

[0073] c, the first die body 1 is clamped and installed on a rotary lathe or a lathe through the first connecting part 14, and the noble metal raw material 30 is placed on the first die body 1, and the center of the noble metal raw material 30 is located on the central axis of the first die body 1;

[0074] d, the rotary lathe or the lathe works, and at the same time, the noble metal raw material 30 is spun into the outer contour shape of the first die body 1 by using a spinning tool, the thickness of the arc surface is measured during the spinning process, and the thickness of the arc surface is controlled to be within t±0.05 mm, the first half product 31 is obtained after being taken out from the first die body 1, after the first half product 31 is obtained, the surface of the first half product 31 is cleaned first, and then leakage detection is performed; the first half product 31 includes a first cylindrical table part 311, a first arc table part 312 and a circular table part 313, the first arc table part 312 is located in the middle of the circular table part 313, and the first cylindrical table part 311 is arranged on the first arc table part 312;

[0075] e, the first half product 31 is turned over by 180° and matched and placed on the second die body 2, at this time, the center line axis of the first half product 31 is on the same straight line as the center line axis of the second die body 2, the first arc table part 312 and the first cylindrical table part 311 are located in the cylindrical relief groove 24, and the circular table part 313 is located on the arc ring table 21;

[0076] f. The second mold body 2 is clamped and installed on a lathe or rotary table via the second connecting part 23. The lathe or rotary table works, and at the same time, a spinning tool is used to spin the frustum portion 313 of the first semi-finished product 31 into the outer contour shape of the arc ring 21 of the second mold body 2. During the spinning process, the thickness of the arc surface is measured and controlled within t±0.05mm. After completion, it is taken out from the second mold body 2 to obtain the second semi-finished product 32. After obtaining the second semi-finished product 32, the surface of the first semi-finished product 31 is cleaned first, and then a leakage test is performed. The second semi-finished product 32 includes a first cylindrical frustum portion 311, a first arc ring portion 312, a second cylindrical frustum portion 321, and a second arc ring portion 322. One end of the second arc ring portion 322 is connected to the first arc ring portion 312, and the other end of the second arc ring portion 322 is connected to the second cylindrical frustum portion 321. The first cylindrical frustum portion 311 and the second cylindrical frustum portion 321 are arranged parallel to each other.

[0077] g. Based on the curvature and length of the thin-walled bend 3, the second semi-finished product 32 is cut using a laser cutting machine. The cutting is performed along the longitudinal direction of the second semi-finished product 32 to obtain at least two third semi-finished products 33. The third semi-finished products 33 are then ultrasonically cleaned for 45 minutes to remove the precious metal powder residue from the laser cutting that adheres to the surface. After cutting, the first cylindrical truncated section 311 and the second cylindrical truncated section 321 of the third semi-finished product 33 are trimmed using stainless steel scissors. After trimming, the length of the first cylindrical truncated section 311 and the second cylindrical truncated section 321 is 1 mm.

[0078] h. The first cylindrical platform portion 311 and the second cylindrical platform portion 321 in the third semi-finished product 33 are folded. The folding process is performed by first annealing with an oxyhydrogen flame for 40 seconds and then folding at an angle of 90°. After the folding process, the first cylindrical platform portion 311 is perpendicular to the first arc platform portion 312, and the second cylindrical platform portion 321 is perpendicular to the second arc platform portion 322. The first cylindrical platform portion 311 is located outside the first arc platform portion 312, and the second cylindrical platform portion 321 is located outside the second arc platform portion 322. Then, the two third semi-finished products 33 are fastened together to form a thin-walled bent pipe 3 shape. The two third semi-finished products 33 are welded together by melting the first cylindrical platform portion 311 and the second cylindrical platform portion 321 at high temperature. The height of the weld is about 1.2 times the wall thickness of the thin-walled bent pipe 3, thereby obtaining the finished thin-walled bent pipe 3.

[0079] After the finished thin-walled bend 3 has cooled naturally, a leakage test is conducted. If no leakage occurs, it can be assembled and welded with other pipes.

Claims

1. A method of forming a large-diameter thin-wall bend of a noble metal, characterized by, It comprises the following steps: a, making noble metal large pipe diameter thin wall elbow forming die, the noble metal large pipe diameter thin wall elbow forming die comprises first die body (1) and second die body (2), the shape of first die body (1) is axisymmetric figure, first die body (1) includes first cylindrical table (11), circular arc table (12), second cylindrical table (13) and first connecting part (14), the longitudinal section shape of the outer side wall of circular arc table (12) is inwardly concave circular arc, first cylindrical table (11) is arranged on circular arc table (12), circular arc table (12) is arranged on second cylindrical table (13), second cylindrical table (13) is arranged on first connecting part (14), the outer side wall of first cylindrical table (11) is smoothly connected with the outer side wall of circular arc table (12); The shape of second die body (2) is axisymmetric figure, second die body (2) includes circular arc ring table (21), third cylindrical table (22) and second connecting part (23), circular arc ring table (21) is arranged on third cylindrical table (22), third cylindrical table (22) is arranged on second connecting part (23), the longitudinal section shape of circular arc ring table (21) is upwardly convex circular arc, the middle of third cylindrical table (22) is provided with cylindrical accommodation slot (24), the outer side wall of circular arc ring table (21) is smoothly connected with the outer side wall of third cylindrical table (22), the inner side wall of circular arc ring table (21) is smoothly connected with the sidewall of cylindrical accommodation slot (24); The inner diameter of thin wall elbow (3) is Φ, the pipe wall thickness of thin wall elbow (3) is t, the inner diameter of thin wall elbow (3) is Φin; The diameter of the longitudinal section circular arc of the outer side wall of circular arc table (12) is R1, R1=Φ / 2+t-(0.05~0.10)mm, the height of first cylindrical table (11) is 3-5mm, the transverse section circular diameter of first cylindrical table (11) is Φ1, Φ1=Φin-2t-(0.15~0.25)mm, the transverse section circular diameter of second cylindrical table (13) is Φ2, Φ2=Φin+4R1+(30~50)mm; The diameter of the longitudinal section circular arc of circular arc ring table (21) is R2, R2=Φ / 2+t-(0.05~0.10)mm, the depth of cylindrical accommodation slot (24) is 5-8mm, the transverse section circular diameter of cylindrical accommodation slot (24) is Φ3, Φ3=Φin+2t+(0.05~0.10)mm, the transverse section circular diameter of third cylindrical table (22) is Φ4, Φ4=Φin+4R2-(0.05~0.10)mm; b, prepare noble metal raw material (30), the shape of noble metal raw material (30) is circular, the circular diameter of noble metal raw material (30) is Φ2+(10~20)mm, the thickness of noble metal raw material (30) is t+0.25~0.35mm; c, first die body (1) is clamped and installed on the rotary bed or lathe through first connecting part (14), and noble metal raw material (30) is placed on first die body (1), the center of noble metal raw material (30) is located on the central axis of first die body (1). d. The lathe or turning machine is used to spin the precious metal raw material (30) into the outer contour shape of the first mold body (1) using a spinning tool. After being taken out from the first mold body (1), the first semi-finished product (31) is obtained. The first semi-finished product (31) includes a first cylindrical platform (311), a first arc platform (312) and a frustum (313). The first arc platform (312) is located in the middle of the frustum (313), and the first cylindrical platform (311) is set on the first arc platform (312). e. After flipping the first semi-finished product (31) 180°, place it on the second mold body (2). At this time, the centerline of the first semi-finished product (31) and the centerline of the second mold body (2) are on the same straight line. The first arc platform (312) and the first cylindrical platform (311) are located in the cylindrical relief groove (24), and the platform (313) is located on the arc ring platform (21). f. The second mold body (2) is clamped and installed on a lathe or a turning machine through the second connecting part (23). The lathe or turning machine works, and at the same time, a spinning tool is used to spin the frustum part (313) of the first semi-finished product (31) into the outer contour shape of the arc ring frustum (21) of the second mold body (2). After being taken out from the second mold body (2), the second semi-finished product (32) is obtained. The second semi-finished product (32) includes a first cylindrical frustum part (311), a first arc frustum part (312), a second cylindrical frustum part (321) and a second arc frustum part (322). One end of the second arc frustum part (322) is connected to the first arc frustum part (312), and the other end of the second arc frustum part (322) is connected to the second cylindrical frustum part (321). The first cylindrical frustum part (311) and the second cylindrical frustum part (321) are arranged parallel to each other. g. Based on the curvature and length of the thin-walled bend (3), the second semi-finished product (32) is cut using a cutting machine. The cutting is performed along the longitudinal direction of the second semi-finished product (32) to obtain at least two third semi-finished products (33). h. Fold the first cylindrical truncated section (311) and the second cylindrical truncated section (321) in the third semi-finished product (33) at an angle of 90°. After folding, the first cylindrical truncated section (311) is perpendicular to the first arc truncated section (312), and the second cylindrical truncated section (321) is perpendicular to the second arc truncated section (322). Then, fasten the two third semi-finished products (33) together to form a thin-walled bent pipe (3). Weld the two third semi-finished products (33) together by melting the first cylindrical truncated section (311) and the second cylindrical truncated section (321) at high temperature to obtain the finished thin-walled bent pipe (3).

2. The method of forming a noble metal large-diameter thin-wall elbow as recited in claim 1, wherein: The precious metal large-diameter thin-walled pipe bending forming mold also includes a cylindrical gasket (25), which is detachably matched and set in a cylindrical relief groove (24).

3. The method of forming a noble metal large diameter thin wall elbow as set forth in claim 1, wherein: In step a, the first mold body (1) and the second mold body (2) are first quenched to a hardness of 45HRC or higher. Then, hard chrome is plated on the surface of the first mold body (1) and the second mold body (2) and polished.

4. The method of forming a noble metal large diameter thin wall elbow as set forth in claim 1, wherein: In step b, the noble metal raw material (30) is annealed in an annealing furnace at 1100-1350°C for 30-40 minutes, and then is flattened on a flattening device after natural cooling, and the flatness is within ±0.15 mm after flattening.

5. The method of forming a noble metal large diameter thin wall elbow as set forth in claim 1, wherein: In step d, after the first semi-finished product (31) is obtained, the surface of the first semi-finished product (31) is cleaned, and then leakage detection is performed.

6. The method of forming a noble metal large diameter thin wall elbow as set forth in claim 1, wherein: In step e, the bottom of the first cylindrical platform (311) is in contact with the cylindrical gasket (25), and the height of the cylindrical gasket (25) is 2-3 mm.

7. The method of forming a noble metal large diameter thin wall elbow as set forth in claim 1, wherein: In step f, after the second semi-finished product (32) is obtained, the surface of the second semi-finished product (32) is cleaned, and then leakage detection is performed.

8. The method of forming a noble metal large diameter thin wall elbow as set forth in claim 1, wherein: In step g, after the third semi-finished product (33) is obtained, the first cylindrical platform (311) and the second cylindrical platform (321) of the third semi-finished product (33) are trimmed, and the length of the first cylindrical platform (311) and the second cylindrical platform (321) is 0.5-1.0 mm after trimming. In step h, after the folding treatment, the first cylindrical platform (311) is located outside the first arc platform (312), and the second cylindrical platform (321) is located outside the second arc platform (322).

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