A process for roll forming a housing flange

Abstract

The application discloses a process for shell flange rolling forming, and relates to the shell flange manufacturing field.The technical scheme is characterized by comprising the following steps: step S1, blanking;step S2, heating;step S3, upsetting and drawing: the blank is drawn for the first time, then the blank is upset for the first time, then the blank is drawn for the second time, the blank is inverted into an octagonal shape, the blank is upset for the second time, and the outer edge of the blank is rounded;step S4, punching;step S5, spinning;step S6, heating by returning to the furnace: the blank is heated and kept in the furnace;step S7, ring rolling: the ring rolling is carried out by using a special-shaped main roller and a special-shaped core roller, the initial stage of rolling is a blank rounding stage a, the speed is increased to carry out a forming stage b, the shape of the forged piece is completely formed, the forged piece enters a direct growth stage, the core roller feeding speed is reduced, and the forged piece enters a shaping stage c;the rolling curve is an exponential function, wherein x is a radial rolling amount, and y is an axial rolling amount.The application has the advantages of improving the material utilization rate and the quality of the shell flange.

Description

Technical Field

[0001] This invention relates to the field of shell flange manufacturing, and more particularly to a process for rolling shell flanges. Background Technology

[0002] A shell flange is a component used to connect or secure a shell structure. It is typically made of metal and has a ring-shaped structure. Shell flanges are widely used in many industries and applications, such as machinery manufacturing, chemical engineering, and the energy sector.

[0003] Currently, there is a type of large shell flange that requires the traditional ring rolling process for single-piece blank irregular-shaped rolling, which involves preparing two irregular-shaped dies: an outer edge irregular-shaped die and an inner edge irregular-shaped die. The outer edge irregular-shaped die is adapted to the outer edge shape of the shell flange, and the inner edge irregular-shaped die is adapted to the inner edge shape of the shell flange. The outer edge irregular-shaped die is installed on the ring rolling mill to roll the outer edge of the blank, and then the inner edge irregular-shaped die is installed on the ring rolling mill to roll the inner edge of the blank. Finally, machining and shaping are performed.

[0004] However, the following problems exist in the rolling process:

[0005] 1. The inner and outer edges of the billet are not formed synchronously, which leads to asymmetrical stress on the billet during the ring rolling process. This can easily cause dynamic instability, resulting in uneven weight distribution or geometric deviations in the billet. Consequently, the internal stress distribution of the billet is unbalanced, and the uniformity of the structure is poor. This can lead to processing defects such as folds and grooves, affecting the quality of the billet.

[0006] 2. After rolling, a lot of additional machining processes are required to shape the billet to the target size. For example, if the blank weight is 5000kg / piece, the finished product weight is 2768kg / piece, resulting in low material utilization. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a process for rolling shell flanges, which has the advantages of improving the material utilization rate and quality of shell flanges.

[0008] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0009] A process for rolling and forming a housing flange, characterized by comprising the following steps:

[0010] Step S1: Unloading;

[0011] Step S2, Heating: Heating and holding the slab at the desired temperature;

[0012] Step S3, Upsetting and Drawing: The billet is initially drawn, with a minimum forging ratio of 3.6. Then, it is initially upset, with a minimum forging ratio of 1.6. The billet is then drawn a second time, with a minimum forging ratio of 1.6. The billet is then turned into an octagon and upset a second time, with a minimum forging ratio of 1.8. Finally, the outer edge of the billet is rounded.

[0013] Step S4, punching:

[0014] Step S5, Spinning: Using the center of the wall thickness as a reference, first press one side of the outer edge (L1), then press one side of the inner edge (L2). The pressing amount of (L1) and (L2) is the same. Then the billet is flipped over and the same spinning action is performed.

[0015] Step S6, Reheating in the furnace: The billet is heated in the furnace and kept at that temperature;

[0016] Step S7, Ring Rolling: The ring is rolled using a special-shaped main roll and a special-shaped mandrel. The initial rolling stage is the billet rounding stage a, followed by the speed increase for the forming stage b. Once the forging shape is fully formed, the forging enters the direct growth stage, the mandrel feed speed is reduced, and finally the forging enters the shaping stage c.

[0017] The rolling curve is an exponential function Where x is the radial rolling amount and y is the axial rolling amount.

[0018] Furthermore, in step S2, the slab is heated to 1230℃ and held for 3 to 4 hours.

[0019] Furthermore, in step S3, the total forging ratio of the billet reaches 8.6 or higher.

[0020] Furthermore, in step S5, the deformation amount of spinning is 36%.

[0021] Furthermore, in step S6, the billet is heated to 1230°C and held for 1.5 hours.

[0022] Furthermore, in step S7, during the billet rounding stage, the roller feed speed is set to 0.8 mm / s, and after the billet has rotated 3 to 5 times, the feed speed is rapidly increased to 2 mm / s.

[0023] Furthermore, in step S7, during forming stage b, once the shape of the forging is fully formed, the core roller feed speed is reduced to 1 mm / s, and then the direct growth stage begins.

[0024] Furthermore, in step S7, when the diameter of the forging is 100mm away from the finished product, the core roller feed speed is reduced to 0.6mm / s, at which point the forging enters the shaping stage.

[0025] In summary, the present invention has the following beneficial effects:

[0026] 1. During upsetting and drawing, ensuring a single upsetting and drawing ratio, and a total forging ratio of 8.6, allows the defects at the center of the billet to be subjected to tension, compression, and deformation, resulting in material rearrangement and redistribution in the defect area. This facilitates bonding between the defect area and the surrounding material, reducing or eliminating the defect. The applied pressure helps to compact the material in the defect area, reducing the size and extent of the defect. Strain and thermal effects promote material recrystallization. Recrystallization improves the grain structure of the material, causing the grains in the defect area to grow or rearrange. The combined effect of these three factors results in a more uniform material structure, refined grains, and improved mechanical properties of the forging.

[0027] 2. Spinning at the end face of the forging can locally increase the strain of the material, thereby improving the material's fluidity and forming corresponding bulges at both ends of the billet. This makes it easier to adjust and deform the shape of the billet during subsequent forging processes, thus promoting the forming of the forging.

[0028] 3. In the ring rolling process, the material enters the rounding stage at a low speed, then the speed is increased, with only radial rolling and no axial rolling. Due to the compression of the main roll and mandrel, the material in the middle section flows towards both ends, with the most material accumulating near the two end faces. Next, the forming stage begins. The high feed speed and the previously spun end bulges are beneficial for forging formation. The axial reduction speed gradually decreases until it reaches zero. This is to eliminate end face grooves caused by the wide wall thickness at the top and bottom ends, which can easily occur during rolling when the main roll and mandrel are in full contact with the forging. As the rolling progresses, the wall thickness gradually decreases, and the groove phenomenon gradually lessens until it disappears. Finally, the shaping stage begins, similar to the rounding stage, achieving overall symmetrical rolling and improving rolling stability. Furthermore, the rolling curve is designed to facilitate forging formation and ensure dimensional and shape tolerances, reducing rolling difficulty while guaranteeing forging quality.

[0029] 4. Reasonable rolling parameters and design of rolling curves are beneficial to the forming of forgings and ensure their size and shape, control tolerances, and the shape of the forgings after rolling is more in line with the design of the parts, which also helps to reduce material consumption.

[0030] 5. By selecting slab blanks for blanking, and without the need for extensive machining operations to process the blanks to the specified dimensions, the weight of the blanks is reduced, the utilization rate of materials is improved, and the raw material cost is lowered. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the process steps for rolling and forming shell flanges.

[0032] Figure 2This is a schematic diagram of the billet structure in step S5.

[0033] Figure 3 This is a schematic diagram of the billet structure in step S7.

[0034] Figure 4 This is a schematic diagram of the structure of the part after it has been rolled into shape.

[0035] Figure 5 It is a rolling curve diagram.

[0036] Figure 6 This is a metallographic image of Example 1.

[0037] Figure 7 This is the metallographic image of Example 2.

[0038] Figure 8 This is the metallographic examination image of Comparative Example 1.

[0039] Figure 9 This is the metallographic image of Example 2. Detailed Implementation

[0040] Example 1:

[0041] A process for rolling forming of shell flanges, such as Figure 1 As shown, it includes the following steps:

[0042] Step S1: Unloading;

[0043] Material specifications: 14Cr1Mo slab blank, weight 8000kg, dimensions 1500mm×1500mm×450mm.

[0044] Step S2, Heating: The slab is heated and kept at a constant temperature, specifically heated to 1230℃ and kept at a constant temperature for 3 to 4 hours.

[0045] Step S3, Upsetting:

[0046] The billet undergoes initial drawing along the thickness direction to 800mm×800mm×1600mm, with a minimum forging ratio of 3.6 for the initial drawing.

[0047] Then, the billet is upsetting to a height H=1000, with a forging ratio of 1.6.

[0048] Then, the billet is drawn to 800mm×800mm×1600mm, with a forging ratio of 1.6.

[0049] After the billet is drawn out, it is turned into an octagon, and then the billet is roughened to a height H=920mm with a ratio of 1.6.

[0050] The final blank outer diameter was rolled to Φ1200mm, and the total forging ratio was 8.6.

[0051] The upsetting and drawing process effectively eliminates defects such as white spots and shrinkage cavities in the center of the slab, enabling it to meet the flaw detection requirements of NB / T47013.3-2017. Simultaneously, it makes the material microstructure more uniform, refines the grains, and improves the mechanical properties of the forging.

[0052] Step S4, punching: the inner hole size of the blank is Φ550mm.

[0053] Step S5, Spinning: Using the center of the wall thickness as a reference, such as... Figure 2 As shown, the outer edge (L1) is pressed first, followed by the inner edge (L2). The pressing amount for (L1) and (L2) is the same, which is 95mm. The cross-sectional area of ​​the billet is 311025mm². 2 The cross-sectional area of ​​the forging is 198717 mm². 2 The deformation amount is 36%. After that, the billet is flipped over and the same spinning action is performed. After the two-step pressing is completed, there is a certain bulge on the outer wall and the inner wall of the inner hole of the billet, leaving a deformation allowance for subsequent rolling and forming.

[0054] Step S6, Heating: Return the forged billet to the furnace and heat it to 1230℃, then hold it at that temperature for 1.5 hours.

[0055] Step S7, Ring Rolling: (e.g.) Figure 3 As shown,

[0056] Ring rolling is performed using shaped main rolls and shaped core rolls.

[0057] The initial rolling stage is the billet rounding stage a, with the roll feed speed set to 0.8 mm / s. After the billet has rotated 3-5 times, the feed speed is rapidly increased to 2 mm / s. Only radial rolling occurs, without axial rolling. At this stage, due to the compression of the main roll and the core roll, the material in the middle section flows towards both ends, with the most material accumulating near the two end faces. If axial rolling were present, even more material would accumulate near the end faces, resulting in a folding phenomenon.

[0058] Next, the speed is increased to the forming stage b. Once the forging shape is fully formed, a higher feed speed, combined with the bulging of the inner and outer walls of the forging, provides sufficient deformation material, and the forging enters the direct growth stage. The mandrel feed speed is reduced to 1 mm / s, and the forging enters the growth stage. Reducing the mandrel feed speed at this point is more conducive to stable rolling of the forging. In forming stage b, the axial reduction speed gradually decreases until it reaches zero. The purpose is that after the main roll and mandrel are in full contact with the forging, due to the wide wall thickness at both ends, the center is prone to not being fully forged, resulting in grooves. Axial rolling can eliminate these end face grooves. Furthermore, as rolling progresses, the wall thickness gradually decreases, and the groove phenomenon gradually lessens until it disappears.

[0059] When the forging diameter is 100mm away from the finished product, the mandrel feed speed is rapidly reduced to 0.6mm / s. At this point, the forging enters the forming stage c. The deformation in forming stage c is similar to that in rounding stage a, but the length change of the forging in forming stage c is less than that in rounding stage a. Reducing the forging diameter growth rate is more conducive to ensuring the roundness and flatness of the forging. The final forging structure is as follows. Figure 4 As shown,

[0060] like Figure 5 As shown, the rolling curve in stage b is an exponential function. Where x is the radial rolling amount and y is the axial rolling amount.

[0061] The comprehensive test results of the forgings are shown in Table 1:

[0062]

[0063]

[0064] Table 1

[0065] in conclusion:

[0066] 1. The tensile strength, yield strength, and impact energy in both tangential (0°) and tangential (180°) test directions meet and are at the high level of the design specifications, proving that the alloy has been strengthened and has good mechanical properties, thus indirectly proving that the grain structure has been refined and the strengthening mechanism has taken effect.

[0067] 2. The elongation in the two testing directions, tangential (0°) and tangential (180°), represents the tensile deformation capacity of the alloy under stress. Alloys with high elongation can be more easily processed into the required shape during manufacturing and have better resistance to deformation.

[0068] 3. A small difference between the test data in the two test directions, tangential (0°) and tangential (180°), indicates that the microstructure of the forging is uniform throughout.

[0069] 4. The forging has a grain size of 7.5, and the grain structure is fine, which proves that the grains in the defect area have grown or rearranged, the grains have been refined, and there are no excessive non-metallic inclusions in the structure.

[0070] 5. After the deformation of the forging is completed, non-destructive testing is carried out. The sound wave signal feedback in each testing area meets the testing standards, which indicates that no forging defects were caused during the deformation process of the forging.

[0071] Example 2:

[0072] The steps that differ from those in Example 1 are as follows:

[0073] Step S3, Upsetting:

[0074] The billet undergoes initial drawing along the thickness direction to 750mm×750mm×1800mm, with a minimum forging ratio of 4.0 for the initial drawing.

[0075] Then, the billet is upsetting to a height H = 1000 mm, with a forging ratio of 1.8.

[0076] Then, the billet is drawn to 750mm×750mm×1800mm, with a forging ratio of 1.8.

[0077] After the billet is drawn out, it is turned into an octagon, and then the billet is roughened to a height H=920mm with a ratio of 1.9.

[0078] The final blank outer diameter was rolled to Φ1200mm, and the total forging ratio was 9.5.

[0079] Step S5, Spinning: Using the center of the wall thickness as a reference, such as... Figure 2 As shown, first press one side of the outer edge (L1), then press one side of the inner edge (L2). The pressing amount for (L1) and (L2) is the same, which is 95mm. Step S7, Ring Rolling: As shown Figure 3 As shown, The forging inspection results are as follows:

[0080]

[0081]

[0082] Table 2

[0083] Comparative Example 1:

[0084] The steps that differ from those in Example 1 are as follows:

[0085] Step S3, Upsetting:

[0086] The billet undergoes initial drawing along the thickness direction to 1000mm×1000mm×1025mm, with a minimum forging ratio of 2.3 for the initial drawing.

[0087] Then, the billet is upsetting to a height H = 920 mm, with a forging ratio of 1.1.

[0088] Then, the billet is drawn to 1000mm×1000mm×1025mm, with a forging ratio of 1.1.

[0089] After the billet is drawn out, it is turned into an octagon, and then the billet is roughened to a height H = 920 mm with a ratio of 1.1.

[0090] The final blank outer diameter was rolled to Φ1200mm, and the total forging ratio was 5.6.

[0091] The forging inspection results are as follows:

[0092]

[0093]

[0094]

[0095] Table 3

[0096] in conclusion:

[0097] 1. The main difference between Comparative Example 1 and Example 1 is the different forging ratio. Compared with the test results of Example 1, Comparative Example 1 shows a decrease in mechanical properties and a lower grain size.

[0098] 2. Multiple areas in the forging exhibited echo signals exceeding the standard, indicating more defects. This indirectly proves that when the forging ratio does not reach the set window, the desired defect elimination effect cannot be achieved.

[0099] Comparative Example 2:

[0100] The steps that differ from those in Example 1 are as follows:

[0101] Step S3, Upsetting:

[0102] The billet undergoes initial drawing along the thickness direction to 800mm×800mm×1600mm, with a minimum forging ratio of 3.6 for the initial drawing.

[0103] Then, the billet is upsetting to a height H = 920, with a forging ratio of 1.7.

[0104] The final blank outer circle was rolled to Φ1200mm, and the total forging ratio was 5.3.

[0105] Step S7, Ring Rolling: The ring rolling method is adopted at a constant speed of 1.5 mm / s.

[0106] The forging inspection results are as follows:

[0107]

[0108]

[0109]

[0110] Table 4

[0111] in conclusion:

[0112] 1. The main difference between Comparative Example 1 and Example 1 is that the upsetting process is different. Compared with the test results of Example 1, the mechanical properties of Comparative Example 2 are lower, the grain size is lower, and more defects appear.

[0113] 2. Comparing the grain structures of the two, the grain structure of Comparative Example 2 has poorer uniformity, with localized agglomeration. Multiple ultrasonic echo signals were detected in the forging obtained in Comparative Example 2, indicating the presence of forging defects in the structure.

[0114] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0115] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A process for rolling forming a shell flange, characterized in that, Includes the following steps: Step S1: Unloading; Step S2, Heating: Heating and holding the slab at the desired temperature; Step S3, Upsetting and Drawing: The billet is initially drawn, with a minimum forging ratio of 3.

6. Then, it is initially upset, with a minimum forging ratio of 1.

6. The billet is then drawn a second time, with a minimum forging ratio of 1.

6. The billet is then turned into an octagon and upset a second time, with a minimum forging ratio of 1.

8. Finally, the outer edge of the billet is rounded. Step S4: Punching; Step S5, Spinning: Using the center of the wall thickness as a reference, first press one side of the outer edge L1, then press one side of the inner edge L2. The pressing amount of L1 and L2 is the same. Then the billet is flipped over and the same spinning action is performed. Step S6, Reheating in the furnace: The billet is heated in the furnace and kept at that temperature; Step S7, Ring Rolling: Ring rolling is performed using shaped main rolls and shaped mandrels. The initial rolling stage is the billet rounding stage (a), followed by the speed-up forming stage (b). The rolling curve is an exponential function y=f(x)= Where x is the radial rolling amount and y is the axial rolling amount, the forging is fully formed and enters the direct growth stage, the core roll feed speed is reduced, and finally the forging enters the shaping stage c.

2. The process for rolling a shell flange according to claim 1, characterized in that: In step S2, the slab is heated to 1230℃ and held for 3-4 hours.

3. The process for rolling a shell flange according to claim 1, characterized in that: In step S3, the total forging ratio of the billet reaches 8.6 or higher.

4. The process for rolling and forming a shell flange according to claim 1, characterized in that: In step S5, the deformation amount of spinning is 36%.

5. The process for rolling a shell flange according to claim 1, characterized in that: In step S6, the billet is heated to 1230°C and held for 1.5 hours.

6. The process for rolling a shell flange according to claim 1, characterized in that: In step S7, during the billet rounding stage, the roller feed speed is set to 0.8 mm / s. After the billet has rotated 3 to 5 times, the feed speed is rapidly increased to 2 mm / s.

7. The process for rolling a shell flange according to claim 1, characterized in that: In step S7, during forming stage b, the shape of the forging is fully formed, the core roller feed speed is reduced to 1 mm / s, and then it enters the direct growth stage.

8. The process for rolling a shell flange according to claim 1, characterized in that: In step S7, when the diameter of the forging is 100mm away from the finished product, the feed speed of the core roller is reduced to 0.6mm / s, at which point the forging enters the shaping stage.

Images