A method for forging and drawing a super large alloy steel shaft forging

Abstract

The present application relates to a kind of super large alloy steel shaft class forgings' forging drawing method, belong to the field of forging forging, solve the existing super large alloy steel shaft class forgings' forging drawing method exists after drawing serious and / or the problem of the final compaction effect of the surface fold of shaft body of forging blank.For the method includes: using upper convex anvil to the forging blank is sequentially compacted and drawn, finishing drawing and reverse octagon;Compacted and drawn includes four passes, the lower edge of upper convex anvil includes horizontal section and the first straight section being inclined upward and being arranged at the both ends of the horizontal section, the horizontal section and the first straight section form angle, the horizontal section and the first straight section are connected by fillet transition;The side of the upper convex anvil is the second straight section being inclined to the direction of anvil main body.The surface quality and compaction effect of the forging obtained after the method drawing are good.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of forging technology of forgings, in particular to a forging and elongating method of super-large alloy steel shaft forgings. BACKGROUND

[0002] At present, the super-large alloy steel shaft forgings (about 260 tons and above) produced have relatively coarse original as-cast grains of the ingot, and various ingot defects often exist in the core, which requires a series of deformation measures to refine the grains and forge the internal defects such as holes and shrinkage during the forging process. Elongation is the main deformation method of large alloy steel shaft forgings, which plays a crucial role in the compaction of the core of the ingot. At the same time, due to the large section of the shaft body after upsetting, many conventional elongation methods are limited.

[0003] The main elongation method currently applied is FM elongation method. However, due to the elongation characteristics of the FM elongation method, the surface folds of the forgings obtained by the lap between each anvil in the same pass during the elongation process are serious, which further leads to poor final compaction effect. SUMMARY

[0004] In view of the above analysis, the embodiments of the present application aim to provide a forging and elongation method of super-large alloy steel shaft forgings, to solve at least one of the following problems existing in the prior art: (1) the surface folds of the forgings after elongation are serious; (2) the final compaction effect is poor.

[0005] The present application provides a forging and elongation method of super-large alloy steel shaft forgings, which comprises: using an upper convex anvil to sequentially perform compaction elongation, finishing elongation and reverse octagonal elongation on the forgings;

[0006] The compaction elongation comprises:

[0007] Step (1-1): connecting the upper convex anvil with the output end of the press, and placing the forgings between the upper convex anvil and the lower platform;

[0008] Step (1-2): compaction elongation first pass, setting the press stroke target value according to the given reduction amount in the process, lowering the upper convex anvil to the press stroke target value, so that the height of the forgings reaches the first pass target size, and the forgings are turned over by 180°.

[0009] Step (1-3): compaction elongation second pass, setting the press stroke target value according to the given reduction amount in the process, lowering the upper convex anvil to the press stroke target value, so that the height of the forgings reaches the second pass target size, and the forgings are turned over by 90°.

[0010] Step (1-4): Compacting and elongating the third pass, setting the press stroke target value according to the given reduction, lowering the upper anvil to the press stroke target value, so that the height of the forging blank reaches the target size of the third pass, and the forging blank is turned over 180°.

[0011] Step (1-5): Compacting and elongating the fourth pass, setting the press stroke target value according to the given reduction, lowering the upper anvil to the press stroke target value, so that the height of the forging blank reaches the target size of the fourth pass, and the compacting pass is completed.

[0012] The lower edge of the upper anvil includes a horizontal segment and a first straight segment inclined upward at both ends of the horizontal segment, the horizontal segment and the first straight segment form an included angle, and the horizontal segment and the first straight segment are connected by a rounded corner transition; the side edge of the upper anvil is a second straight segment inclined to the anvil body direction, the second straight segment forms an included angle with the vertical direction, and the second straight segment and the first straight segment are connected by a rounded corner transition.

[0013] Preferably, in step (1-2), the reduction of the first compacting and elongating pass is △11=(H11-H14’) / 2+100; wherein H11 is the height of the forging blank before the first pass, and H14’ is the height of the forging blank after the fourth pass.

[0014] Preferably, in step (1-3), the reduction of the second compacting and elongating pass is △12=(H11-H14’) / 2+100; wherein H11 is the height of the forging blank before the first pass, and H14’ is the height of the forging blank after the fourth pass.

[0015] Preferably, in step (1-4), the reduction of the third compacting and elongating pass is △13=(H13-H14’) / 2+100; wherein H13 is the height of the forging blank before the third pass, and H14’ is the height of the forging blank after the fourth pass.

[0016] Preferably, in step (1-5), the reduction of the fourth compacting and elongating pass is △14=(H13-H14’) / 2-100; wherein H13 is the height of the forging blank before the third pass, and H14’ is the height of the forging blank after the fourth pass.

[0017] Preferably, in steps (1-2) to (1-5), the overlapping amount D of adjacent passes is (1 / 2-1)*B1, wherein B1 is the length of the horizontal segment of the lower edge of the upper anvil.

[0018] Preferably, the difference between the target size of the second compacting and elongating pass and the target size of the fourth compacting and elongating pass is 150-300mm.

[0019] Preferably, the inverted octagon has four passes, and the forging blank is turned over 90° between adjacent passes.

[0020] Preferably, the first pass reduction of the inverted octagonal shape is Δ21=(H21-H14') / 2, the second pass reduction of the inverted octagonal shape is Δ22=(H22-H14') / 2, the third pass reduction of the inverted octagonal shape is Δ23=H23-H14'-100, and the fourth pass reduction is controlled according to the target size after the forging blank is finished; wherein H21 is the height of the forging blank before the first pass reduction of the inverted octagonal shape, H22 is the height of the forging blank before the second pass reduction of the inverted octagonal shape, H23 is the height of the forging blank before the third pass reduction of the inverted octagonal shape, and H14' is the height of the forging blank after the fourth pass reduction.

[0021] Preferably, the weight of the super-large alloy steel shaft forging is 260t or more.

[0022] Compared with the prior art, the present application can achieve at least one of the following beneficial effects:

[0023] 1. The method of the present application uses an upper convex anvil, and the compaction passes are four passes (the compaction passes of the existing FM elongation method using an upper flat anvil are five passes), so that the actual forging production efficiency is improved and the manufacturing cost is reduced.

[0024] 2. The lower edge of the upper convex anvil of the present application comprises a horizontal section and first straight sections arranged at both ends of the horizontal section and inclined upward, and the horizontal section and the first straight sections form an included angle. During the elongation operation, as the upper convex anvil is pressed downward on the blank, the contact area between the upper convex anvil and the blank gradually increases, that is, the anvil width is in a gradually increasing state (the length B1 of the horizontal section gradually increases to the distance B2 between the intersection point of the second straight sections at both ends of the upper convex anvil and the extension line of the first straight sections), and at the same time, the height of the blank gradually decreases. In terms of process parameters, the anvil width ratio (anvil width / blank height) can be effectively improved, the optimal parameter coverage range of the anvil width ratio in actual production is improved, the compaction effect of the core of the forging blank is optimized, axial tensile stress is avoided, and crack propagation is inhibited. In addition, when the contact area between the upper convex anvil and the forging blank is small, it is beneficial to reduce the load applied by the press in the initial stage and to improve the equipment forging limit. As the reduction proceeds, the contact area between the upper convex anvil and the forging blank becomes larger and larger, which is beneficial to reduce the number of anvil arrangements in the same pass, thereby reducing the number of overlaps between the hammers in the same pass, and further inhibiting the generation of surface folds of the forging blank.

[0025] 3. Compared with the traditional flat anvil elongation, the included angle between the horizontal section and the first straight section in the upper convex anvil of the present application and the round corner transition thereof, and the included angle between the second straight section and the vertical direction and the round corner transition thereof, make the overlap between the pressed area and the unpressed area of the forging blank form a certain gentle slope, so that the subsequent overlap area is smooth, the generation of folds is effectively inhibited, the reduction amount is guaranteed, the cleaning process is reduced, the elongation efficiency of forging is improved, and the manufacturing cost is reduced.

[0026] 4. The present application fixes the pass number of the compaction pass and the reverse octagonal pass to four, controls the reduction of the compaction pass and the reverse octagonal pass, and does not limit the pass number of the finishing pass, so that the solidification and elongation process is given certain flexibility, which is beneficial to improving the actual forging production efficiency and reducing the manufacturing cost.

[0027] The above technical solutions can be combined with each other in the present application to realize more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purposes and other advantages of the present application can be realized and obtained from the contents particularly pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated herein and constitute a part of the detailed description. The drawings illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application. In the drawings:

[0029] Figure 1 The figure is a schematic diagram of the elongation of the super-large alloy steel shaft forging of the present application.

[0030] Figure 2 The figure is a schematic diagram of the main view structure of the upper convex anvil of the present application;

[0031] Figure 3 The figure is a schematic diagram of the compaction pass flow of the present application;

[0032] Figure 4 The figure is a schematic diagram of the reverse octagonal pass flow of the present application;

[0033] Figure 5 The figure is a schematic diagram of the compaction pass lap of the present application;

[0034] Figure 6 The figure is a schematic diagram of the lap shape of the pressed area and the non-pressed area after the upper convex anvil of the present application and the traditional flat anvil press the billet;

[0035] Figure 7 The figure is a photograph of the forging obtained in Example 2;

[0036] Figure 8 The figure is a photograph of the forging obtained in Comparative Example 1.

[0037] Reference signs:

[0038] 1 - upper convex anvil; 2 - lower platform; 3 - billet;

[0039] H1-height of the forging blank; H2-height of the upper convex anvil; B1-length of the horizontal section; B2-distance between the intersection of the extension line of the second straight section at both ends of the upper convex anvil and the extension line of the first straight section; B3-upper side length of the upper convex anvil; A-angle between the horizontal section and the first straight section; B-angle between the second straight section and the vertical direction; C1-first straight section; C1'-horizontal projection length of the first straight section; C2-second straight section; C2'-horizontal projection length of the second straight section; D-amount of overlap of adjacent passes; R1-rounding between the horizontal section and the first straight section; R2-rounding between the second straight section and the first straight section. DETAILED DESCRIPTION

[0040] The preferred embodiments of the present application will be described in detail below with reference to the drawings, which form a part of this application, and together with the embodiments of the present application illustrate the principles of the present application, but are not intended to limit the scope of the present application.

[0041] It should be noted that the "upper side", "lower side", "side", "straight section", "horizontal section" in the present application are all based on the front view of the upper convex anvil as shown in the drawings. Figure 2

[0042] The FM elongation method adopts an upper flat anvil, the upper side and the lower side of the upper flat anvil are the same length, and the two sides are both perpendicular downward, that is, the existing upper flat anvil is a quadrangular structure, the side and the lower side are connected through a round corner transition, and the existing upper flat anvil has the following disadvantages in elongation: the surface fold of the elongated forging blank is serious, if not cleaned in time, it is easy to expand to the center, increase the forging fire times, and greatly reduce the production efficiency, at the same time, because the section after upsetting is large, the anvil width ratio γ is difficult to be in the optimal interval (γ≥0.5) during elongation, thereby generating axial tensile stress, which seriously affects the surface quality of the forging blank obtained by the FM elongation method and the final compaction effect.

[0043] The present application provides a forging elongation method for super large alloy steel shaft forgings, as shown in the drawings, the method comprises: Figures 1-3 adopting an upper convex anvil 1 to sequentially perform compaction elongation, finishing elongation and reverse octagon on a forging blank 3.

[0044] The compaction elongation comprises:

[0045] Step (1-1): connecting the upper convex anvil 1 with the output end of the press, and placing the forging blank 3 between the upper convex anvil 1 and the lower platform 2.

[0046] Step (1-2): compaction elongation first pass, setting the press stroke target value according to the given reduction amount in the process, lowering the upper convex anvil 1 to the press stroke target value, so that the forging blank height reaches the first pass target size, and the forging blank is turned over 180°.

[0047] ​Steps (1-3): Compact and lengthen the second pass. Set the press stroke target value according to the given pressing amount in the process. Press the upper anvil 1 down to the press stroke target value so that the height of the forging billet reaches the target size of the second pass. Then, rotate the forging billet 90°.

[0048] Steps (1-4): Compact and lengthen for the third pass. Set the press stroke target value according to the given pressing amount in the process. Press the upper anvil 1 down to the press stroke target value so that the billet height reaches the target size of the third pass. Then, rotate the billet 180°.

[0049] Steps (1-5): Fourth pass of compaction and elongation. Set the press stroke target value according to the process given pressing amount. Press the upper anvil 1 down to the press stroke target value so that the forging billet height reaches the target size of the fourth pass. At this point, the compaction pass is completed.

[0050] by Figure 2 Taking the main view of the upper convex anvil as a reference, the lower side of the upper convex anvil 1 includes a horizontal segment and a first straight segment C1 located at both ends of the horizontal segment and inclined upward. The horizontal segment and the first straight segment C1 form an angle A, and the horizontal segment and the first straight segment C1 are connected by a rounded corner R1. The side of the upper convex anvil 1 is a second straight segment C2 that is inclined towards the anvil body. The second straight segment C2 forms an angle B with the vertical direction, and the second straight segment C2 is connected by a rounded corner R2.

[0051] Compared with existing technologies, the method of this invention uses an upper convex anvil and requires only four compaction passes, which reduces the number of passes and improves actual forging production efficiency while lowering manufacturing costs. The upper convex anvil used in this invention is of variable width. As the upper convex anvil presses down on the forging billet, the contact area between the anvil and the billet gradually increases, meaning the anvil width gradually increases (from the length B1 of the horizontal section to the distance B2 between the intersection of the extension lines of the second and first straight lines at both ends of the upper convex anvil). Simultaneously, the height of the forging billet gradually decreases. In terms of process parameters, this effectively improves the anvil width ratio (anvil width / forging billet height H1), expands the coverage range of the optimal anvil width ratio parameter in actual production, and thus optimizes the compaction effect of the forging billet core, avoiding axial tensile stress and inhibiting crack propagation. In addition, when the contact area between the upper anvil and the forging billet is small, it is beneficial to reduce the load applied by the press in the initial stage and improve the forging limit of the equipment. As the forging is pressed down, the contact area between the upper anvil and the forging billet becomes larger and larger, which is beneficial to reduce the number of times the anvil is placed in the same pass, thereby reducing the number of times the hammers overlap in the same pass and further suppressing the formation of creases on the surface of the forging billet.

[0052] It should be noted that, Figure 3In the formula, H11 is the height of the forging blank before the first pass reduction; H11' is the height of the forging blank after the first pass reduction, H12 is the height of the forging blank before the second pass reduction, H12' is the height of the forging blank after the second pass reduction, H13 is the height of the forging blank before the third pass reduction, H13' is the height of the forging blank after the third pass reduction, H14 is the height of the forging blank before the fourth pass reduction, and H14' is the height of the forging blank after the fourth pass reduction.

[0053] In the step (1-1), the center lines in the width direction of the upper convex anvil, the forging blank and the lower platform are coincided before the compaction and elongation.

[0054] In the step (1-1), the length of the lower platform 2 is greater than the length of the shaft body of the forging blank after the elongation.

[0055] In the step (1-2), the first pass reduction amount of the compaction and elongation is Δ11=(H11-H14') / 2+100.

[0056] In the step (1-3), the second pass reduction amount of the compaction and elongation is Δ12=(H11-H14') / 2+100.

[0057] In the step (1-4), the third pass reduction amount of the compaction and elongation is Δ13=(H13-H14') / 2+100.

[0058] In the step (1-5), the fourth pass reduction amount of the compaction and elongation is Δ14=(H13-H14') / 2-100.

[0059] In the steps (1-2) to (1-5), the adjacent pass overlap amount D=(1 / 2~1)*B1, wherein B1 is the length of the horizontal section of the lower edge of the upper convex anvil.

[0060] It should be noted that in the same pass, there is no gap between the adjacent two hammers.

[0061] The compaction and elongation of the present application is four passes in total. Due to the deformation characteristics, the difference between the target size of the second pass of the compaction and elongation and the target size of the fourth pass of the compaction and elongation is 150mm~300mm, i.e. H14'-H12'=(150~300)mm, so that when the target size of the fourth pass is reached, the horizontal size of the forging blank is also close to the final target size.

[0062] In the step (2-1), the first pass of the finishing elongation is performed by turning 90° and reducing to the first pass target size of the finishing elongation.

[0063] In the step (2-1), the first pass of the finishing elongation is performed by turning 90° and reducing to the first pass target size of the finishing elongation.

[0064] Step (2-2): Turn over 90°, finish the second pass of elongation, and press down to the target size of the second pass of finish elongation.

[0065] As shown in the figure, the inverse octagon is forged in four passes, and the blank is turned over 90° between adjacent passes. Figure 4

[0066] It should be noted that, Figure 4 H21 is the height of the blank before the first pass of the inverse octagon, H21' is the height of the blank after the first pass of the inverse octagon, H22 is the height of the blank before the second pass of the inverse octagon, H22' is the height of the blank after the second pass of the inverse octagon, H23 is the height of the blank before the third pass of the inverse octagon, H23' is the height of the blank after the third pass of the inverse octagon, H24 is the height of the blank before the fourth pass of the inverse octagon, and H24' is the height of the blank after the fourth pass of the inverse octagon.

[0067] For example, the first pass reduction of the inverse octagon is △21 = (H21-H14') / 2, the second pass reduction of the inverse octagon is △22 = (H22-H14') / 2, the third pass reduction of the inverse octagon is △23 = H23-H14'-100, and the fourth pass reduction is controlled according to the target size of the finished blank.

[0068] It should be noted that the weight of the super-large alloy steel shaft forging is more than 260t.

[0069] For example, the angle A between the horizontal segment and the first straight segment C1 is 10°-15°. If the angle is too large, it will affect the reduction of the blank contacted by the first straight segment C1 during pressing; if the angle is too small, it is not conducive to suppressing the fold.

[0070] For example, the angle B between the second straight segment C2 and the vertical direction is 8°-10°. If the angle is too large, it will affect the anvil width, and thus affect the elongation efficiency; if the angle is too small, it is not conducive to suppressing the fold.

[0071] For example, the radius of the circle corresponding to the round corner R2 between the horizontal segment and the first straight segment C1 is 500mm-600mm.

[0072] For example, the radius of the circle corresponding to the round corner R1 between the second straight segment C2 and the first straight segment C1 is 200mm-300mm.

[0073] For example, the difference between the distance B2 between the intersection points of the second straight segment extension lines at both ends of the upper convex anvil 1 and the first straight segment extension line and the length B1 of the horizontal segment is 0-50mm. ​If the difference is too large, the angle B is too small, which is not conducive to inhibit the generation of creases in the drawing process; if the difference is too small, the drawing efficiency will be reduced.

[0074] Exemplarily, the projection length C1' of the first straight line segment C1 in the horizontal direction is (B2-B1) / 2. If the projection length is too long, it will affect the inclination angle of the second straight line segment C2 of the side, which is not conducive to inhibit the creases. If the projection length is too small, the production efficiency will be greatly reduced.

[0075] Exemplarily, the distance B2 between the intersection point of the second straight line segment at both ends of the upper convex anvil 1 and the extension line of the first straight line segment and the extension line of the first straight line segment is less than the upper edge length B3 of the upper convex anvil 1.

[0076] Exemplarily, the difference between the distance B2 between the intersection point of the second straight line segment at both ends of the upper convex anvil 1 and the extension line of the first straight line segment and the extension line of the first straight line segment and the upper edge length B3 of the upper convex anvil is 200mm-300mm. In theory, the larger the difference, the more the creases can be inhibited, but the too large difference will reduce the production efficiency.

[0077] It can be understood that the upper edge length B3 of the upper convex anvil 1 is equal to 2*(C1'+C2')+B1.

[0078] Exemplarily, the difference between the upper edge length B3 of the upper convex anvil 1 and the length B1 of the horizontal segment is 2*(C1'+C2'). In the present application, the inhibition of the generation of creases in the drawing process benefits from the combined design of "C1'+C2". The larger the value, the more conducive to inhibit the generation of creases, but at the same time, B1 will be smaller, thereby affecting the drawing efficiency. The appropriate "C1'+C2" can be obtained through the length relationship between the preferred included angles A, B and B1, B2, B3 in the above.

[0079] Exemplarily, the projection length C1' of the first straight line segment C1 in the horizontal direction is 150mm-200mm, and the projection length C2' of the second straight line segment C2 in the horizontal direction is 100mm-150mm.

[0080] It can be understood that the upper convex anvil 1 as a whole is an inverted trapezoid with "upper wide and lower narrow", i.e. B3>B1. By reducing the contact area of the upper convex anvil 1 and the forging blank, the press pressure during initial pressing can be further reduced.

[0081] During the drawing process, the included angles A and B, the first straight line segment C1 and the second straight line segment C2 make the lap joint of the pressed area and the unpressed area form a certain slope (such as Figure 6The angle A further effectively suppresses the generation of the creases. The angle A makes the upper convex anvil 1 in the elongation process, as the contact surface between the upper convex anvil 1 and the forging blank 3 increases, the anvil width is in a variable stage: B1-B2. In this stage, the anvil width gradually increases, and the height of the forging blank gradually decreases. In the process parameters, the anvil width ratio can be effectively improved, and the optimal parameter coverage range of the anvil width ratio in actual production can be improved.

[0082] Exemplarily, the length of the lower platform 2 is greater than or equal to the length of the elongated forging blank.

[0083] Exemplarily, the width of the lower platform 2 is greater than or equal to the maximum width of the forging blank in the elongation process.

[0084] Exemplarily, the sum of the upper convex anvil height H2, the lower platform height, and the maximum height of the blank in the elongation process is less than the vertical net distance of the press.

[0085] Next, the forging elongation method of the super-large alloy steel shaft forging of the present application will be further described through specific embodiments.

[0086] Embodiment 1

[0087] This embodiment provides a forging elongation method of a super-large alloy steel shaft forging. For a super-large alloy steel shaft forging (30Cr2Ni4MoV, weight 300t), the upset forging blank shaft body diameter is about H11=3300mm, and the square billet is elongated to H14'=2300mm according to the process, and then the regular octagon is inverted. Specifically, it comprises:

[0088] (1) The upper convex anvil is connected with the output end of the press, and the forging blank is placed between the upper convex anvil and the lower platform. The lower edge of the upper convex anvil 1 comprises a horizontal section and a first straight section C1 arranged at both ends of the horizontal section and inclined upward, the horizontal section and the first straight section C1 form an included angle A, and the horizontal section and the first straight section C1 are connected by a round corner R1; the side edge of the upper convex anvil 1 is a second straight section C2 inclined to the direction of the anvil body, the second straight section C2 forms an included angle B with the vertical direction, and the second straight section C2 and the first straight section C1 are connected by a round corner R2. The included angle A between the horizontal section and the first straight section C1 is 13°; the included angle B between the second straight section C2 and the vertical direction is 9°; the radius of the circle corresponding to the round corner R2 between the horizontal section and the first straight section C1 is 550 mm; the radius of the circle corresponding to the round corner R1 between the second straight section C2 and the first straight section C1 is 250 mm. The projection length C1' of the first straight section C1 in the horizontal direction is 150 mm; the projection length C2' of the second straight section in the horizontal direction is 100 mm; the length B1 of the horizontal section of the lower edge is 1500 mm; B2=1800 mm, the length B3 of the upper edge of the upper convex anvil is 2000 mm; the length of the lower platform 2 is greater than or equal to the length of the elongated forging blank. The width of the platform 2 is greater than the maximum width of the forging blank during elongation. The sum of the height H2 of the upper convex anvil, the height of the lower platform and the maximum height of the blank during elongation is less than the vertical net distance of the press.

[0089] (2) The first pass of compaction and elongation is performed, the reduction amount Δ11=(H11-H14') / 2+100=600 mm, the target value of the press stroke is set, the upper convex anvil is pressed down to the target value of the press stroke, so that the height of the forging blank reaches the first pass target size H11'=H11-Δ11=2700 mm, and the forging blank is turned over by 180°. In this process, the anvil width ratio B / H=(B1-B2) / (H11-H11')=0.45-0.67.

[0090] (3) The second pass of compaction and elongation is performed, the reduction amount Δ12=(H11-H14') / 2+100=600 mm, the target value of the press stroke is set, the upper convex anvil is pressed down to the target value of the press stroke, so that the height of the forging blank reaches the second pass target size H12'=H12-Δ12=2100 mm, and the forging blank is turned over by 90°. In this process, the anvil width ratio B / H=(B1-B2) / H12=0.56-0.85.

[0091] (4) Compaction and elongation third pass, after the first two passes of the reduction, the width of the forging billet to H13≈3750mm, reduction △13=(H13-H14') / 2+100, set the target value of the press stroke, the upper convex anvil is reduced to the target value of the press stroke, so that the height of the forging billet reaches the third pass target size H13'=H13-△13=2925mm, the forging billet is turned over 180°. In this process, the anvil width ratio B / H=(B1-B2) / H12=0.40-0.61.

[0092] (5) Compaction and elongation fourth pass, reduction △14=(H13-H14') / 2-100, set the target value of the press stroke, the upper convex anvil is reduced to the target value of the press stroke, so that the height of the forging billet reaches the second pass target size H14'=H14-△14=2300mm. In this process, the anvil width ratio B / H=(B1-B2) / H12=0.51-0.78.

[0093] So far, the compaction pass is over. As can be seen from the above, except that the anvil width ratio is less than 0.5 at the initial reduction of the first pass and the third pass, the anvil width ratio in the remaining process is higher than 0.5, and the anvil width ratio in the actual reduction process of each pass covers a wide range of optimal intervals, which can effectively suppress the axial tensile stress of the shaft body of the forging billet in the elongation process, thereby effectively avoiding cracks.

[0094] (6) Turn over 90°, finish elongation first pass, reduce to the finish elongation first pass target size.

[0095] (7) Turn over 90°, finish elongation second pass, reduce to the finish elongation second pass target size.

[0096] (8) Inverted octagonal process, inverted octagonal four passes, the forging billet is turned over 90° between passes.

[0097] Each pass is turned over 90°, the first pass reduction is calculated according to △21=(H21-H14') / 2, the second pass reduction is calculated according to △22=(H22-H14') / 2, the third pass reduction is calculated according to △23=H23-H14'-100, and the fourth pass reduction is controlled according to the target size after the finish of the forging billet.

[0098] The forged piece obtained in this example is shown in Figure 7 As can be seen, the surface quality is good, and compared with the Figure 8 of Comparative Example 1, the fold is significantly improved, which can significantly reduce the subsequent fire cleaning pass, effectively shorten the forging cycle, and reduce the manufacturing cost; at the same time, the forged piece obtained in this example is detected by flaw detection, and the maximum equivalent diameter of the defects existing in each area of the finished forging piece is less than Φ0.8, and compared with Comparative Example 1, the flaw detection quality of the core of the forging piece is obviously improved, and the bottom attenuation is small.

[0099] Example 2

[0100] The embodiment provides a forging and elongating method of the super large alloy steel shaft forging similar to that in Embodiment 1, different from which, the included angle A between the horizontal section and the first straight section C1 is 8°.

[0101] The surface quality of the forging obtained in the embodiment is improved (compared with Comparative Example 1), but there are still a few obvious folds on the shaft surface of the forging blank, and the detection of the product forgings elongated in the embodiment shows that the heart detection quality of the product forgings is improved (compared with Comparative Example 1), the bottom wave has no obvious attenuation, and the maximum defect signal equivalent diameter is less than Φ1.3.

[0102] Embodiment 3

[0103] The embodiment provides a forging and elongating method of the super large alloy steel shaft forging similar to that in Embodiment 1, different from which, the difference B2 between the intersection point between the second straight section extension line at the two ends of the upper anvil 1 and the first straight section extension line and the upper side length B3 of the upper anvil is 150 mm.

[0104] The surface quality of the forging obtained in the embodiment is slightly improved (compared with Comparative Example 1), but there are still a few obvious folds on the shaft surface, and the detection of the product forgings elongated in the embodiment shows that the heart detection quality of the product forgings is improved (compared with Comparative Example 1), the bottom wave has no obvious attenuation, and the maximum defect signal equivalent diameter is less than Φ1.4.

[0105] Embodiment 4

[0106] The embodiment provides a forging and elongating method of the super large alloy steel shaft forging similar to that in Embodiment 1, different from which, the included angle B between the second straight section C2 and the vertical direction is 6 degrees.

[0107] The surface quality of the forging obtained in the embodiment is improved (compared with Comparative Example 1), but there are still a few obvious folds on the shaft surface, and the detection of the product forgings elongated in the embodiment shows that the heart detection quality of the product forgings is improved (compared with Comparative Example 1), the bottom wave has no obvious attenuation, and the maximum defect signal equivalent diameter is less than Φ1.4.

[0108] Embodiment 5

[0109] The embodiment provides a forging and elongating method of the super large alloy steel shaft forging similar to that in Embodiment 1, different from which, the reduction angle B is increased, and the difference B2 between the intersection point between the second straight section extension line at the two ends of the upper anvil 1 and the first straight section extension line and the length B1 of the horizontal section is

[0110] The surface quality of the forged piece obtained in this example is slightly improved (compared with Comparative Example 1), but there are still a few obvious folds on the surface of the shaft of the billet, and the ultrasonic testing of the finished product after elongation shows that the heart of the finished product has improved (compared with Comparative Example 1), the bottom wave has no obvious attenuation, and the maximum defect signal equivalent diameter is less than Φ1.5.

[0111] Comparative Example 1

[0112] This comparative example provides a forging elongation method for a super large alloy steel shaft forging similar to Example 1, except that a traditional flat anvil is used, and the anvil width of the upper flat anvil used is 1500 mm. For a super large alloy steel shaft forging (30Cr2Ni4MoV, weight 300 t), the shaft diameter of the upset billet is about H11 = 3300 mm, and the square billet is elongated to H14' = 2300 mm according to the process, and then the octagon is inverted.

[0113] The specific steps include:

[0114] (1) Connect the upper flat anvil with the output end of the press, and place the billet between the upper flat anvil and the lower platform

[0115] (2) Compaction and elongation first pass, with a reduction of Δ11 = 400 mm, set the press stroke target value, lower the upper flat anvil to the press stroke target value, so that the billet height reaches the first pass target size H11' = H11 - Δ11 = 2900 mm, and then the billet is turned over 180°. The anvil width ratio B / H = 0.45-0.53 during this process.

[0116] (3) Compaction and elongation second pass, with a reduction of Δ12 = 500 mm, set the press stroke target value, lower the upper flat anvil to the press stroke target value, so that the billet height reaches the second pass target size H12' = H12 - Δ12 = 2400 mm, and then the billet is turned over 90°. The anvil width ratio B / H = 0.51-0.62 during this process.

[0117] (4) Compaction and elongation third pass, after the reduction of the previous two passes, the billet is widened to H13 ≈ 3700 mm, with a reduction of Δ13 = 600 mm, set the press stroke target value, lower the upper flat anvil to the press stroke target value, so that the billet height reaches the third pass target size H13' = H13 - Δ13 = 3100 mm, and then the billet is turned over 180°. The anvil width ratio B / H = (B1-B2) / H12 = 0.40-0.48 during this process.

[0118] (5) Compaction and elongation fourth pass, the amount of reduction△14=600mm, set the press stroke target value, the upper flat anvil is pressed to the press stroke target value, so that the height of the forging billet reaches the second pass target size H14'=H14-△14=2500mm, and then the billet is turned over 90°. The anvil width ratio B / H in this process is 0.48-0.60.

[0119] (6) Compaction and elongation fifth pass, after the reduction of the third and fourth passes, the forging billet is expanded to H15≈3000mm, the amount of reduction△15=500mm, set the press stroke target value, the upper flat anvil is pressed to the press stroke target value, so that the height of the forging billet reaches the third pass target size H13'=H15-△13=2500mm. The anvil width ratio B / H in this process is 0.50-0.60.

[0120] At this point, the compaction pass is completed.

[0121] (7) Turn over 90°, finishing elongation first pass, press to the target size 2500mm.

[0122] (8) Turn over 90°, finishing elongation second pass, press to the target size 2500mm.

[0123] (9) Inverted octagonal process, inverted octagonal for four passes, the forging billet is turned over 90° between passes. The single-sided reduction of each pass is controlled at 300mm.

[0124] This comparative example has a total of 5 passes, compared with Example 1, the actual reduction passes are increased (the more the reduction passes, the more the number of overlaps, and the more likely to produce folds), and in addition to the second and fifth passes, the anvil width ratio optimal interval coverage range is relatively narrow during the actual reduction process, as shown in Table 1, which causes the folds at the overlap of the shaft to further expand into cracks due to axial tensile stress, resulting in poor surface quality of the forging billet, and the surface folds of the forged piece are obvious, as shown in Figure 8 , in order to clean up, the crack is further aggravated, and a longer fire length is required for subsequent cleaning; at the same time, the finished forged piece after elongation of this comparative example is detected by flaw detection, and it is found that the core flaw detection quality of the finished forged piece is general, the core flaw detection unqualified defect wave appears, the bottom wave attenuation is obvious, and the maximum defect signal equivalent diameter reaches Φ1.9.

[0125] Table 1

[0126] Pass First pass Second pass Third pass Fourth pass Fifth pass Post-press size 2900 mm 2400 mm 3100 mm 2500 mm 2500 mm Anvil width ratio 0.45～0.53 0.51～0.62 0.40～0.48 0.48～0.60 0.50～0.60

[0127] Comparative Example 2

[0128] This comparative example provides a similar forging method as Example 1, except that an upper flat anvil is used, and the other steps are the same as Example 1.

[0129] The surface quality of the forging blank obtained by the comparative example is poor, the surface fold of the forging is obvious, the quality of the product forging core is poor, the core flaw wave of the unqualified flaw detection appears, the bottom wave attenuation is obvious, and the maximum defect signal equivalent diameter reaches Φ2.8.

[0130] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A method of forging and drawing a superalloy steel shaft forging, characterized in that, The method comprises: sequentially performing compaction elongation, finishing elongation and reverse octagon on the forging blank by using the upper convex anvil; The compaction elongation comprises: Step (1-1): connecting the upper convex anvil with the output end of the press, and placing the forging blank between the upper convex anvil and the lower platform; Step (1-2): first pass of compaction elongation, setting the press stroke target value according to the given reduction amount in the process, lowering the upper convex anvil to the press stroke target value, so that the height of the forging blank reaches the first pass target size, and the forging blank is turned over by 180°; Step (1-3): second pass of compaction elongation, setting the press stroke target value according to the given reduction amount in the process, lowering the upper convex anvil to the press stroke target value, so that the height of the forging blank reaches the second pass target size, and the forging blank is turned over by 90°; Step (1-4): third pass of compaction elongation, setting the press stroke target value according to the given reduction amount in the process, lowering the upper convex anvil to the press stroke target value, so that the height of the forging blank reaches the third pass target size, and the forging blank is turned over by 180°; Step (1-5): fourth pass of compaction elongation, setting the press stroke target value according to the given reduction amount in the process, lowering the upper convex anvil to the press stroke target value, so that the height of the forging blank reaches the fourth pass target size, and the compaction passes are completed. The lower edge of the upper convex anvil comprises a horizontal segment and first straight line segments arranged at both ends of the horizontal segment and inclined upward, the horizontal segment and the first straight line segments form an included angle, and the horizontal segment and the first straight line segments are connected by a round corner transition; the side edge of the upper convex anvil is a second straight line segment inclined to the anvil body direction, the second straight line segment and the vertical direction form an included angle, and the second straight line segment and the first straight line segment are connected by a round corner transition.

2. The method of claim 1, wherein, In step (1-2), the first pass reduction amount of compaction elongation is △11=(H11-H14’) / 2+100; wherein H11 is the height of the forging blank before the first pass reduction, and H14’ is the height of the forging blank after the fourth pass reduction.

3. The method of claim 1, wherein, In step (1-3), the second pass reduction amount of compaction elongation is △12=(H11-H14’) / 2+100; wherein H11 is the height of the forging blank before the first pass reduction, and H14’ is the height of the forging blank after the fourth pass reduction.

4. The method of claim 1, wherein, In step (1-4), the third pass reduction amount of compaction elongation is △13=(H13-H14’) / 2+100; wherein H13 is the height of the forging blank before the third pass reduction, and H14’ is the height of the forging blank after the fourth pass reduction.

5. The method of claim 1, wherein, In step (1-5), the fourth pass reduction amount of compaction elongation is △14=(H13-H14’) / 2-100; wherein H13 is the height of the forging blank before the third pass reduction, and H14’ is the height of the forging blank after the fourth pass reduction.

6. The method of claim 1, wherein, In steps (1-2) to (1-5), the overlapping amount D of adjacent passes is (1 / 2-1)*B1, wherein B1 is the length of the horizontal segment of the lower edge of the upper convex anvil.

7. The method of claim 1, wherein, The difference between the second pass target size of compaction elongation and the fourth pass target size of compaction elongation is 150-300 mm.

8. The method of claim 1, wherein, The reverse octagon has four passes, and the forging blank is turned over by 90° between adjacent passes.

9. The method of claim 8, wherein, The first-pass reduction amount of the inverted regular octagon is Δ21=(H21-H14') / 2, the second-pass reduction amount of the inverted regular octagon is Δ22=(H22-H14') / 2, the third-pass reduction amount of the inverted regular octagon is Δ23=H23-H14'-100, and the fourth-pass reduction amount is controlled according to the target size after the forging blank is finished; wherein H21 is the height of the forging blank before the first-pass reduction of the inverted regular octagon, H22 is the height of the forging blank before the second-pass reduction of the inverted regular octagon, H23 is the height of the forging blank before the third-pass reduction of the inverted regular octagon, and H14' is the height of the forging blank after the fourth-pass reduction.

10. The method of claim 1, wherein, The weight of the super-large alloy steel shaft forging is 260 t or more.

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