Forming tool and forming method for large forge piece with flange deep blind hole

Abstract

The invention relates to a forming tool and a forming method for a large forged piece with a flange and a deep blind hole, belongs to the technical field of forging, and is used for at least solving one of the problems that an existing press cannot meet the forging pressure of integral forming of the large forged piece with the flange and the deep blind hole and coarse grains and mixed crystals are easily generated in the preparation process of the large forged piece with the flange and the deep blind hole. The forming tool comprises a platform and a female die above the platform. The female die is hollow and comprises a first lower die body and a second lower die body. A conical inclined face is arranged on the inner side of the upper end face of the second lower die, the included angle theta between the conical inclined face and the center line of the female die ranges from 5 degrees to 45 degrees, a positioning groove is formed in the bottom end face of the first lower die, and the upper end face of the second lower die is clamped into the positioning groove. According to the forming tool, shunting in the forging process can be achieved, and therefore it is guaranteed that grains of forgings are uniform.

Description

Technical Field

[0001] The invention belongs to the technical field of forging, and in particular relates to a forming tool and a forming method for a large-scale forging with a flange and a deep blind hole. Background Art

[0002] Stainless steel or high-temperature alloys do not undergo phase changes during hot working and heat treatment. Therefore, the coarse grains and mixed grains caused by uneven forging are difficult to eliminate during subsequent heat treatment. The deformation uniformity of the finished product obtained by forging will affect the uniformity of the grain size of the finished product. Therefore, how to ensure the deformation uniformity of the finished forging is particularly important to ensure product quality.

[0003] The manufacturing of large forgings with flanges and deep blind holes has a large risk factor. The forgings have complex shapes, are difficult to form, and the flange end faces are prone to cracking. The grain size of the forgings and the uniformity of deformation of each part are difficult to guarantee. At present, the forming methods for forgings with shallow blind holes mainly include punching and deep drawing. For deep blind hole forgings, there is a method of multiple drawing after punching. However, when forging large stainless steel or high-temperature alloy forgings with flanges and deep blind holes, the force required for punching exceeds the limit value of the press, and general presses cannot meet the requirements. In addition, the multi-fire drawing method not only has the risk of thickening and deformation at the bottom head position, but also undergoes multiple fires of heating without deformation, which is bound to cause coarse grain size. Therefore, providing a forming tool and forming method for large forgings with flanges and deep blind holes has become an urgent problem to be solved. Summary of the invention

[0004] In view of the above analysis, the present invention aims to provide a forming tool and forming method for large flanged deep blind hole forgings, so as to solve at least one of the following technical problems: the existing press cannot meet the forging pressure for the overall forming of large flanged deep blind hole forgings, and the preparation process of large flanged deep blind hole forgings is prone to produce coarse grains and mixed grains.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] The invention provides a forming tool for a large-scale flanged deep blind hole forging, the forming tool comprising a platform and a die above the platform; the die is hollow, and comprises a first lower die and a second lower die; a conical inclined surface is arranged on the inner side of the upper end surface of the second lower die, and the angle θ between the conical inclined surface and the center line of the die is 5° to 45°; a positioning groove is arranged on the bottom end surface of the first lower die, and the upper end surface of the second lower die is inserted into the positioning groove.

[0007] Furthermore, the concave mold also includes a bottom pad, which is placed in the second lower mold and is in the shape of a hollow ring.

[0008] Furthermore, the forming tool also includes a punch, which includes a punch rod and a punch ring. A boss is provided at the lower end of the punch rod, and the punch ring is sleeved on the boss. The punch rod and the punch ring are connected by a soft pin; the outer diameter D9 of the punch ring is greater than the outer diameter D8 of the punch rod.

[0009] Furthermore, a chamfer is provided on the outer side of the lower end of the punch ring.

[0010] Furthermore, the material of the soft pin is Q235 steel or 45 steel.

[0011] Furthermore, the forming tooling also includes a core rod and a core rod retaining ring, the core rod includes a clamping section and a working section, and the side of the working section has a taper; the clamping section and the working section are connected by a connecting section in the middle, the diameter of the working section is smaller than the diameter of the connecting section, and the diameter of the clamping section is smaller than the diameter of the working section.

[0012] The present invention also provides a forming method for a large flanged deep blind hole forging, wherein the forming tooling is used, and the forming method comprises the following specific steps:

[0013] S1. Making the steel ingot into a large preform forging with flange and deep blind hole;

[0014] S2, placing the preform in the concave die, the third constant diameter section of the preform matches with the first lower die of the concave die, and the conical inclined surface of the second lower die of the concave die matches with the third expanded diameter section of the preform;

[0015] S3, the movable crossbeam of the press presses down to drive the punch to move downward and start die forging; when the punch stroke reaches the preset value, loading stops;

[0016] S4. After die forging is completed, the punch ring is locked by the inner hole blank, the movable crossbeam of the press is lifted, the movable crossbeam of the press drives the punch rod to lift, the soft pin is sheared off, and the punch ring remains in the inner hole of the forging;

[0017] S5. Separate the forging blank from the die after die forging, return the forging blank to the furnace for reheating, and then lengthen the core rod to obtain a large forging with a flange and a deep blind hole.

[0018] Furthermore, the large flanged deep blind hole forging preform includes, from bottom to top, a second diameter expansion section, a third diameter expansion section, a third constant diameter section, a fourth diameter expansion section and a fourth constant diameter section connected in sequence;

[0019] The angle k1 between the outer cylindrical surface of the second diameter expansion section and the center line of the preform and the angle k2 between the outer cylindrical surface of the third diameter expansion section and the center line of the preform meet the following relationship: k1<k2;

[0020] A second central blind hole is provided on the upper surface of the fourth constant diameter section. The second central blind hole is in a truncated cone shape. The aperture of the upper surface of the second central blind hole is larger than the aperture of the lower surface.

[0021] Furthermore, the upper surface of the fourth constant diameter section is inclined downward in a direction gradually moving away from the center line of the preform.

[0022] Furthermore, in S5, when the core rod is stretched, 100 to 200 mm of the end of the blank remains unpressed.

[0023] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0024] The die of the forming tool of the present invention comprises a first lower die and a second lower die. By controlling the shapes of the first lower die and the second lower die, diversion during forging can be achieved; the die also comprises a bottom pad, which can prevent the blank from cracking during die forging.

[0025] The punch of the forming tool of the present invention comprises a punch rod and a punch holding ring, and the punch rod and the punch holding ring are connected by a soft pin. After the die forging is completed, when the movable crossbeam of the press drives the punch rod to move upward, the soft pin between the punch rod and the punch holding ring will be sheared off due to the gravity of the blank, and the punch holding ring and the broken soft pin will remain in the inner hole of the forging. In this way, demoulding is simple and quick.

[0026] In the forming method of the large flanged deep blind hole forging of the present invention, a preform is first made, and the preform is in a multi-stage step shape. When the preform is placed in the die, a part of the third diameter expansion section is placed on the conical inclined surface of the die, and the fourth constant diameter section is located above the die and the outer diameter of the fourth constant diameter section is greater than the maximum inner diameter of the die, while the preform in the non-traditional design is completely inside the die. In this way, when punching, a part of the third diameter expansion section is in close contact with the conical inclined surface of the die, and the fourth diameter expansion section gradually contacts the upper end surface of the die, which can effectively prevent the height of the preform from decreasing, and further prevent the blank from gradually filling the cavity due to the downward movement of the blank metal, thereby causing the forming force to increase and the limit stroke of the punch to shorten. The step-type preforming design is adopted to compress the deformation of the subsequent drawing process, and can achieve single-fire drawing, thereby ensuring the technical advantages of single-fire drawing forming.

[0027] In the forming method of the present invention, by accurately controlling the shape and size of the preform, combined with the control of the forming tooling, for example, the concave die of the forming tooling includes a first lower die and a second lower die, and by controlling the shapes of the first lower die and the second lower die, the diversion during the forging process can be achieved. Combined with the control of the process steps of the present invention, the diversion gradient deformation of the first constant diameter section and the second constant diameter section can be achieved, so that the strain of the second constant diameter section is 0.4-0.6, and the strain of the first constant diameter section and the bottom head is 0.5-1; thereby ensuring that the deformation amount at each position is uniform, so that the grain size distribution is uniform and the grains are fine.

[0028] The large-scale flanged deep blind hole forgings prepared by the method of the present invention have uniform grains, a grain size of 3 to 4 levels, and a maximum grain size difference of less than 1 level at different locations, for example, a maximum grain size difference of 0.5 levels at different locations. During the preparation process of the present invention, there are no defects such as cracks and concave centers.

[0029] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are only for the purpose of illustrating the particular invention and are not to be considered as limiting the invention. The same reference symbols denote the same components throughout the accompanying drawings.

[0031] Figure 1 It is a schematic structural diagram of a large-scale flanged deep blind hole forging of the present invention;

[0032] Figure 2 It is a structural schematic diagram of a large-scale forging preform with a flange and a deep blind hole of the present invention;

[0033] Figure 3 It is a schematic assembly diagram of the forming process of the large flanged deep blind hole forging of the present invention;

[0034] Figure 4 is a schematic diagram of a first lower mold of the present invention;

[0035] Figure 5 is a schematic diagram of a second lower mold of the present invention;

[0036] Figure 6 is a schematic diagram of a punch rod of the present invention;

[0037] Figure 7 It is a schematic diagram of the punch holding ring of the present invention;

[0038] Figure 8 is a schematic diagram of a bottom pad of the present invention;

[0039] Fig. 9 is a schematic diagram of a mandrel of the present invention;

[0040] Fig.10 It is a schematic diagram of the preform forging process of the present invention;

[0041] Fig.11 It is a schematic diagram of the preform after die forging of the present invention;

[0042] Fig.12 It is a schematic diagram of the elongation of the present invention;

[0043] Fig.13 Schematic diagram of the preparation process of Comparative Example 1;

[0044] Fig.14 This is a schematic diagram of the preparation process of Comparative Example 2.

[0045] Reference numerals:

[0046] 1-first constant diameter section, 2-first expanded diameter section, 3-second constant diameter section, 4-first center blind hole, 5-second expanded diameter section, 6-third expanded diameter section, 7-third constant diameter section, 8-fourth expanded diameter section, 9-fourth constant diameter section, 10-second center blind hole, 11-platform, 12-die, 1201-first lower die, 1202-second lower die, 1203-bottom pad, 13-punch, 1301-punch rod, 1302-punch ring, 1303-soft pin, 14-core rod, 1401-clamping section, 1402-working section, 1403-connecting part, 15-core rod retaining ring. DETAILED DESCRIPTION

[0047] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the present invention.

[0048] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the term "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be a direct connection or an indirect connection through an intermediate medium.

[0049] The terms "top", "bottom", "above", "lower", and "on" used throughout the description are relative to the relative positions of components of a device, such as the relative positions of the top and bottom substrates within a device. It is understood that devices are multifunctional regardless of their orientation in space.

[0050] The common working surface of the present invention can be a plane or a curved surface, can be inclined, or can be horizontal. For the convenience of description, the embodiment of the present invention is placed on a horizontal plane and used on the horizontal plane, and "high and low" and "up and down" are defined in this way.

[0051] The present invention provides a large flanged deep blind hole forging, such as Figure 1As shown, the large flanged deep blind hole forging includes a first constant diameter section 1, a first enlarged diameter section 2 and a second constant diameter section 3 connected in sequence from bottom to top. The flanged deep blind hole forging is also provided with a first central blind hole 4, which penetrates the second constant diameter section 3 and the first enlarged diameter section 2 and extends to the bottom of the first constant diameter section 1; the outer diameter of the second constant diameter section 3 is D1, the diameter of the first central blind hole 4 is D2, and the outer diameter of the first constant diameter section 1 is D3, D1>D3>D2; the height of the first constant diameter section 1 is H2, the height of the first enlarged diameter section 2 is H3, the height of the second constant diameter section 3 is H4, the overall height of the forging is H, and the distance between the lowest end of the bottom of the first central blind hole 4 and the bottom of the forging along the central axis is H1. The first enlarged diameter section 2 and the second constant diameter section 3 as a whole can be called a flange.

[0052] Specifically, the material of the large flanged deep blind hole forging of the present invention is stainless steel or high-temperature alloy, which has high deformation resistance and difficult to control grain size; for example, the material of the large flanged deep blind hole forging of the present invention is 316 stainless steel.

[0053] Specifically, the above-mentioned H is greater than 2000mm, for example, H is 1700-4600mm, H1 is 100-500mm, H2 is 600-1800mm, H3 is 100-400mm, and H4 is 1000-2400mm; D3 is greater than 1000mm, for example, D3 is 1000-1500mm, D2 is 800-1200mm, and D1 is greater than 1400mm, for example, D1 is 1400-2400mm.

[0054] Specifically, a ratio h / D2 of the depth h of the first central blind hole 4 to the diameter D2 of the first central blind hole 4 is greater than 1.5, such as 1.5 to 3, such as 2, 2.2, 2.4, 2.6, or 2.8.

[0055] When the inventor prepared the above-mentioned large forgings with flanges and deep blind holes, it was difficult to ensure the grain size of the forgings and the uniformity of deformation of each part; and because the blind holes were deep, the force required for punching was relatively large, and the punching force exceeded the limit value of the press, and a general press could not meet the requirements; and because the blind holes were deep, the die was easily stuck after punching, making it difficult to remove the punch.

[0056] The present invention provides a forming tool for large-scale flanged deep blind hole forgings, such as Figure 3As shown, the forming tooling includes a platform 11 and a die 12 above the platform 11; the die 12 is hollow, and includes a first lower die 1201 and a second lower die 1202, a conical slope is arranged on the inner side of the upper end surface of the second lower die 1202, and an angle θ between the conical slope and the center line of the die 12 is 5° to 45°, for example, 10°, 15°, 20°, 25°, 30°, 35°, 40°; a positioning groove is arranged on the bottom end surface of the first lower die 1201, and the upper end surface of the second lower die 1202 is inserted into the positioning groove.

[0057] Specifically, the platform 11 and the die 12 are split, which can avoid stress concentration at the bottom and extend the life of the mold; and the split shape is relatively simple, easy to manufacture and process, and cost-saving.

[0058] Specifically, the concave mold 12 further includes a bottom pad 1203 , which is placed in the second lower mold 1202 , and the bottom pad 1203 is a hollow ring.

[0059] Considering that too large thickness H10 of the bottom pad 1203 wastes the weight of the forging, and too small thickness fails to prevent cracking, therefore, the thickness H10 of the bottom pad 1203 is controlled to be 80-200 mm, for example, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm.

[0060] Specifically, the forming tool further includes a punch 13, which includes a punch rod 1301 and a punch ring 1302. The lower end of the punch rod 1301 is provided with a boss, and the punch ring 1302 is sleeved on the boss. The punch rod 1301 and the punch ring 1302 are connected by a soft pin 1303; the outer side of the lower end of the punch ring 1302 is provided with a chamfer; the outer diameter D9 of the punch ring 1302 is greater than the outer diameter D8 of the punch rod 1301; for example, the difference between the outer diameter of the punch ring 1302 and the outer diameter of the punch rod 1301 is 40 to 100 mm. The height H9 of the punch ring 1302 is 150 to 250 mm.

[0061] Specifically, the punch connecting frame is connected to the movable crossbeam of the press above the punch connecting frame, and the punch rod 1301 is connected to the punch connecting frame through a long pin, thereby connecting the punch rod 1301 to the movable crossbeam of the press.

[0062] After die forging is completed, when the movable crossbeam of the press drives the punch rod 1301 to move upward, the soft pin between the punch rod 1301 and the punch ring 1302 will be sheared off due to the gravity of the blank, and the punch ring 1302 and the broken soft pin will remain in the inner hole of the forging. In this way, demoulding is simple and quick.

[0063] Specifically, in order to ensure that the soft pin can bear the weight of the punch but cannot bear the weight of the blank, the material of the soft pin is Q235 steel or 45 steel, and the diameter is 22 to 25 mm.

[0064] Specifically, the above-mentioned forming tooling also includes a mandrel 14 and a mandrel retaining ring 15, such as Fig.12 As shown, the core rod 14 includes a clamping section 1401 and a working section 1402. The working section 1402 acts on the central blind hole of the blank. The side of the working section 1402 is tapered, and the draft taper is 4°, which is convenient for demolding. The clamping section 1401 and the working section 1402 are connected by a connecting section 1403 in the middle. The diameter of the working section 1402 is smaller than the diameter of the connecting section 1403, and the diameter of the clamping section 1401 is smaller than the diameter of the working section 1402.

[0065] On the other hand, the present invention also provides a forming method for a large flanged deep blind hole forging, wherein the forming tooling is used, and the forming method comprises the following specific steps:

[0066] S1. The steel ingot is made into a large preform forging with a flange and deep blind hole (hereinafter referred to as a preform);

[0067] S2, such as Fig.10 As shown in A, the preform is placed in the concave die 12, the third constant diameter section 7 of the preform cooperates with the first lower die 1201 of the concave die, and the conical inclined surface of the second lower die 1202 of the concave die cooperates with the third expanded diameter section 6;

[0068] S3, the movable crossbeam of the press presses down to drive the punch to move downward and start die forging; Fig.10 As shown in B, the punch stroke reaches the preset value and the loading stops;

[0069] S4, such as Fig.11 As shown, after the die forging is completed, the punch ring 1302 is locked by the inner hole blank, and the movable crossbeam of the press is lifted, and the movable crossbeam of the press drives the punch rod 1301 to be lifted. Since the soft pin cannot drive the weight of the blank, it is sheared and cut off, so that the punch ring 1302 remains in the inner hole of the forging;

[0070] S5, separating the forging blank from the die 12 after die forging, returning the forging blank to the furnace for reheating, and then lengthening the mandrel after reheating to obtain a large forging with a flange and a deep blind hole.

[0071] Specifically, Figure 2As shown, the preform includes, from bottom to top, a second diameter expansion section 5, a third diameter expansion section 6, a third constant diameter section 7, a fourth diameter expansion section 8 and a fourth constant diameter section 9 connected in sequence; the angle k1 between the outer cylindrical surface of the second diameter expansion section 5 and the center line of the preform, and the angle k2 between the outer cylindrical surface of the third diameter expansion section 6 and the center line of the preform meet the following relationship: k1<k2; the upper surface of the fourth constant diameter section 9 is provided with a second center blind hole 10, the second center blind hole 10 is a truncated cone, and the aperture of the upper surface of the second center blind hole 10 is larger than the aperture of the lower surface. Specifically, considering that the angle α / 2 between the upper end side wall of the second center blind hole 10 and the center line of the preform is too large, the preform will form a large slope after punching, and when the core rod is stretched, there will be a large gap between the inner hole of the forging and the core rod, which affects the deformation of the flange part; if α / 2 is too small, the inner hole blank will wrap around the punch rod during the punching process, making it difficult to demold. Therefore, α is controlled to be 4° to 15°, for example, 6°, 8°, 10°, 12°, 14°; that is, α / 2 is 2° to 7.5°.

[0072] Specifically, in order to prevent the height of the blank from decreasing during the die forging process, the angle k3 between the outer cylindrical surface of the fourth expansion section 8 and the center line of the preform is greater than 30°. For example, k3 is 33° to 80°; for example, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°.

[0073] Specifically, the total height H' of the preform is smaller than the height H of the finished large forging with flange and deep blind hole.

[0074] Compared with the prior art, the large-scale preform of forging with flange and deep blind hole of the present invention is in the shape of multiple steps. When the preform is placed in the die, a part of the third diameter expansion section is placed on the conical inclined surface of the die, and the fourth constant diameter section is located above the die and the outer diameter of the fourth constant diameter section is greater than the maximum inner diameter of the die, instead of the blank completely placed inside the die in the traditional design. In this way, when punching, a part of the third diameter expansion section is in close contact with the conical inclined surface of the die, and the fourth diameter expansion section gradually contacts with the upper end surface of the die, which can effectively prevent the height of the preform from decreasing, and further prevent the blank from gradually filling the cavity due to the downward movement of the blank metal, thereby causing the forming force to increase and the limit stroke of the punch to shorten. The step-type preforming design is adopted to compress the deformation of the subsequent drawing process, and can achieve single-fire drawing, thereby ensuring the technical advantages of single-fire drawing.

[0075] Specifically, the connection between the side wall of the second central blind hole 10 and the bottom wall of the second central blind hole 10 has a rounded chamfer, which can reduce the tensile stress at the connection between the side wall and the bottom surface and prevent cracks from occurring.

[0076] Specifically, a connection between the side wall of the second central blind hole 10 and the upper surface of the fourth constant diameter section 9 has a circular chamfer, which can reduce stress concentration.

[0077] Specifically, the upper surface of the fourth constant diameter section 9 is inclined downward in a direction gradually away from the center line of the preform. This is because the height of the inner hole will decrease after die forging. This will make the height of the rear end face of the punching tend to be consistent, so that there will be no concave heart phenomenon. Considering that if the inclination angle β is too large, the inner hole of the end face will be high and the outer circle will be low, and if β is too small, it will not achieve the desired effect, the inner hole will be low and the outer circle will be high. Once the inner hole is low and the outer circle is high, in the subsequent drawing process, the inner hole and the core rod will contact, the inner hole will grow slowly in the length direction, and the outer circle will grow quickly, and the concave heart situation will be aggravated. Therefore, β is controlled to be 2° to 8°, for example, 3°, 4°, 5°, 6°, and 7°.

[0078] Specifically, the height L2 of the third diameter expansion section 6, the height L3 of the second diameter expansion section 5, and the height H2 of the first constant diameter section 1 of the forging satisfy the following relationship: H2<L2+L3.

[0079] Specifically, the diameter D4 of the lower surface of the second diameter-expanding section 5 and the outer ring diameter D3 of the first constant diameter section 1 satisfy the following relationship: D4=(0.4-0.7)D3.

[0080] Specifically, the diameter D2' of the lower surface of the second central blind hole 10 and the diameter D2 of the first central blind hole 4 satisfy the following relationship: D2'=D2.

[0081] Specifically, the diameter D0 of the upper surface of the second enlarged diameter section 5 and the diameter D2 ′ of the lower surface of the second central blind hole 10 satisfy the following relationship: D0>D2 ′.

[0082] Specifically, the diameter D1' of the third constant diameter section 7 and the outer diameter D1 of the second constant diameter section 3 satisfy the following relationship: D1'=D1.

[0083] Specifically, the diameter D1″ of the fourth constant diameter section 9, the outer diameter D1 of the second constant diameter section 3, and the diameter D2 of the first central blind hole 4 meet the following relationship:

[0084]

[0085] Specifically, if the angle γ / 2 between the lower end side wall of the third expansion section 6 and the center line of the preform is too large, the blank will be stuck in this layer, and it is easy to cause the metal below this inclined surface to crack during punching; if the angle is too small, the blank will flow downward, and after filling the cavity, the punching force will increase and the stroke will decrease. Therefore, γ is controlled to be 80° to 120°.

[0086] Specifically, the height L4 of the second center blind hole 10 and the height L1 of the fourth constant diameter section 9 meet the following relationship: L4<L1. Specifically, the height L1 of the fourth constant diameter section 9 is controlled between 600 and 1000 mm, L1=L4+(50~200) mm. L4 is smaller than L1 to ensure uniformity of deformation. If L4 is deeper than L1, after punching, the blank between L4 and L1 will not be deformed, and will not be covered when the core rod is stretched. Therefore, L4<L1 is controlled.

[0087] Specifically, the first lower die 1201 of the forming tool cooperates with the third constant diameter section 7 of the preform, and the conical inclined surface of the second lower die 1202 can cooperate with the third expanded diameter section 6 of the preform.

[0088] During die forging, the bottom of the second enlarged diameter section 5 of the preform is placed in the inner hole of the bottom pad 1203, and the bottom pad 1203 prevents the preform from being torn during the die forging process.

[0089] Specifically, the diameter of the mandrel retaining ring 15 is larger than the outer ring diameter of the second constant diameter section 3 of the forging. When the forging is stretched, the mandrel retaining ring 15 is used and is placed at the connection between the working section 1402 and the connecting section 1403. The mandrel retaining ring 15 can prevent cracks and concave centers on the end face of the forging and is conducive to demolding the mandrel. Mechanism of preventing cracks: When there is no mandrel retaining ring 15 against the forging, the end face of the forging is in contact with the air, the temperature drops quickly, and the resulting end face bulge is subjected to tensile stress, which is easy to produce cracks; when there is a mandrel retaining ring 15 against the end face, the end face bulge cannot be formed, the end face tends to be flat and the tensile stress is reduced. Mechanism of preventing concave centers: During the process of stretching the mandrel, the inner hole of the blank contacts the mandrel, the temperature drops quickly, and the friction is large. The end face often moves while the core does not move, resulting in a concave center. Therefore, when there is a mandrel retaining ring 15, the end face is flatter and the concave center is eliminated. Demolding: During the process of drawing the mandrel, the temperature of the blank gradually decreases, and the thermal expansion and contraction make it easy for the blank to wrap around the mandrel and difficult to demold. Therefore, when the end face of the blank is pulled against the mandrel retaining ring 15, the length of the mandrel retaining ring 15 increases, and there is relative movement between the blank and the mandrel in the inner hole of the forging, and it will not be stuck on the mandrel. Demolding is performed based on this principle.

[0090] Specifically, Figure 4 is a schematic diagram of the first lower die, Figure 5 is a schematic diagram of the second lower die. Figure 6 is a schematic diagram of the punch rod. Figure 7 This is a schematic diagram of the punch ring. Figure 8 is a schematic diagram of the bottom pad. Fig. 9Schematic diagram of the core rod. The inner wall of the upper surface of the first lower die 1201 is chamfered; the inner diameter of the first lower die 1201 is D6, the inner diameter of the positioning groove at the bottom of the first lower die 1201 is D5, and the height of the first lower die 1201 is H7; the inner diameter of the upper surface of the second lower die 1202 is D7, the inner diameter of the lower surface of the second lower die 1202 is D3', the diameter of the outer ring of the second lower die 1202 is D5', and the height of the second lower die 1202 is H6; the outer ring diameter of the punch rod 1301 is The diameter of the punch rod 1301 is D8, the height of the boss of the punch rod 1301 is H8, and the diameter of the boss is D12; the height of the punch ring 1302 is H9, the inner diameter of the punch ring 1302 is D13, and the outer diameter of the punch ring 1302 is D9; the outer diameter of the bottom pad 1203 is D10; the maximum diameter of the working section 1402 of the mandrel is D11, and the length of the working section 1402 of the mandrel is H4'; the units of the above dimensions are mm, and the above dimensions meet the following relationship:

[0091] D6=D7=D1;

[0092] D3' = D3;

[0093] D5 = D5' + (3 ~ 20) mm;

[0094] H6 = H2 + (100-400) mm;

[0095] D8 = D9 - (40 ~ 100) mm;

[0096] D9 = D2;

[0097] D10 = D3'-(20~50) mm;

[0098] D11=D2;

[0099] D12 = D13 - (1-5) mm;

[0100] H8=H9;

[0101] H10 = 80 ~ 200mm;

[0102] H4'<H-H1-H9.

[0103] Specifically, in the above S2, the length between the upper end surface of the third constant diameter section 7 of the preform and the lower end surface of the second expanded diameter section 5 is greater than the total assembly height of the first lower mold 1201 and the second lower mold 1202;

[0104] Specifically, in the above S5, the mandrel 14 is inserted into the central blind hole of the forging blank, the mandrel retaining ring 15 is pressed between the connecting portion 1403 and the forging blank, and the forging is stretched in a single step to obtain a large-scale forging with a flange and a deep blind hole.

[0105] Specifically, in the above S5, when the core rod is stretched, 100 to 200 mm of the end of the blank is left unpressed to prevent cracks from occurring at the end.

[0106] Compared with the prior art, the die of the forming tooling of the present invention includes a first lower die and a second lower die. By controlling the shapes of the first lower die and the second lower die, diversion during the forging process can be achieved; the die also includes a bottom pad, which can prevent the blank from being cracked during the die forging process.

[0107] The punch of the forming tool of the present invention comprises a punch rod and a punch holding ring, and the punch rod and the punch holding ring are connected by a soft pin. After the die forging is completed, when the movable crossbeam of the press drives the punch rod to move upward, the soft pin between the punch rod and the punch holding ring will be sheared off due to the gravity of the blank, and the punch holding ring and the broken soft pin will remain in the inner hole of the forging. In this way, demoulding is simple and quick.

[0108] In the forming method of the large flanged deep blind hole forging of the present invention, a preform is first made, and the preform is in a multi-stage step shape. When the preform is placed in the die, a part of the third diameter expansion section is placed on the conical inclined surface of the die, and the fourth constant diameter section is located above the die and the outer diameter of the fourth constant diameter section is greater than the maximum inner diameter of the die, while the preform in the non-traditional design is completely inside the die. In this way, when punching, a part of the third diameter expansion section is in close contact with the conical inclined surface of the die, and the fourth diameter expansion section gradually contacts the upper end surface of the die, which can effectively prevent the height of the preform from decreasing, and further prevent the blank from gradually filling the cavity due to the downward movement of the blank metal, thereby causing the forming force to increase and the limit stroke of the punch to shorten. The step-type preforming design is adopted to compress the deformation of the subsequent drawing process, and can achieve single-fire drawing, thereby ensuring the technical advantages of single-fire drawing forming.

[0109] In the forming method of the present invention, by accurately controlling the shape and size of the preform, combined with the control of the forming tooling, for example, the concave die of the forming tooling includes a first lower die and a second lower die, and by controlling the shapes of the first lower die and the second lower die, the diversion during the forging process can be achieved. Combined with the control of the process steps of the present invention, the diversion gradient deformation of the first constant diameter section and the second constant diameter section can be achieved, so that the strain of the second constant diameter section is 0.4-0.6, and the strain of the first constant diameter section and the bottom head is 0.5-1; thereby ensuring that the deformation amount at each position is uniform, so that the grain size distribution is uniform and the grains are fine.

[0110] The large-scale flanged deep blind hole forgings prepared by the method of the present invention have uniform grains, a grain size of 3 to 4 levels, and a maximum grain size difference of less than 1 level at different locations, for example, a maximum grain size difference of 0.5 levels at different locations. During the preparation process of the present invention, there are no defects such as cracks and concave centers.

[0111] Example 1

[0112] This embodiment provides a large flanged deep blind hole forging, such as Figure 1 As shown, the large flanged deep blind hole forging includes, from bottom to top, a first constant diameter section 1, a first enlarged diameter section 2, and a second constant diameter section 3 connected in sequence. The flanged deep blind hole forging is also provided with a first central blind hole 4, which penetrates the second constant diameter section 3 and the first enlarged diameter section 2 and extends to the bottom of the first constant diameter section 1; the outer diameter of the second constant diameter section 3 is D1, the diameter of the first central blind hole 4 is D2, the outer diameter of the first constant diameter section 1 is D3, D1 = 1650mm, D3 = 1310mm, D2 = 900mm; the height of the first constant diameter section 1 is H2, the height of the first enlarged diameter section 2 is H3, the height of the second constant diameter section 3 is H4, the overall height of the forging is H, and the distance between the lowest end of the bottom of the first central blind hole 4 and the bottom of the forging along the central axis is H1. The first enlarged diameter section 2 and the second constant diameter section 3 as a whole can be called a flange. H1 = 200 mm, H2 = 1135 mm, H3 = 180 mm, H4 = 1305 mm, H = 2620 mm. The depth h of the first central blind hole 4 is 2420 mm.

[0113] Large flanged deep blind hole forgings are made of 316 stainless steel.

[0114] Example 2

[0115] This embodiment provides a forming tool for a large forging with a flange and a deep blind hole, such as Figure 3 As shown, the forming tooling includes a platform 11 and a die 12 above the platform 11; the die 12 is hollow, and includes a first lower die 1201 and a second lower die 1202. A conical slope is arranged on the inner side of the upper end face of the second lower die 1202, and the angle θ between the conical slope and the center line of the die is 10°. A positioning groove is arranged on the bottom end face of the first lower die 1201, and the upper end face of the second lower die 1202 is inserted into the positioning groove. When in use, the first lower die 1201 cooperates with the third constant diameter section 7, and the conical slope of the second lower die 1202 can cooperate with the third expanded diameter section 6.

[0116] Specifically, the platform 11 and the die 12 are split.

[0117] Specifically, the die 12 further includes a bottom pad 1203, which is placed in the second lower die 1202. The bottom pad 1203 is a hollow ring. During die forging, the bottom of the second diameter expansion section 5 is placed in the inner hole of the bottom pad 1203. The thickness H10 of the bottom pad 1203 is 100 mm.

[0118] Specifically, the above-mentioned forming tooling also includes a punch 13, which includes a punch rod 1301 and a punch ring 1302. The lower end of the punch rod 1301 is provided with a boss, and the punch ring 1302 is sleeved on the boss. The punch rod 1301 and the punch ring 1302 are connected by a soft pin 1303; the outer side of the lower end of the punch ring 1302 is provided with a chamfer; the outer diameter of the punch ring 1302 is larger than the outer diameter of the punch rod 1301.

[0119] Specifically, the punch connecting frame is connected to the movable crossbeam of the press above the punch connecting frame, and the punch rod 1301 is connected to the punch connecting frame through a long pin.

[0120] After die forging is completed, when the movable crossbeam of the press drives the punch rod 1301 to move upward, the soft pin between the punch rod 1301 and the punch ring 1302 will be sheared off due to the gravity of the blank, and the punch ring 1302 and the broken soft pin will remain in the inner hole of the forging. Specifically, the material of the soft pin is 45# steel with a diameter of 25mm.

[0121] Specifically, the above-mentioned forming tooling also includes a core rod 14 and a core rod retaining ring 15. The core rod 14 includes a clamping section 1401 and a working section 1402. The working section 1402 acts on the central blind hole of the blank. The side of the working section 1402 is tapered, and the draft angle is 4°; the clamping section 1401 and the working section 1402 are connected by a connecting section 1403 in the middle, the diameter of the working section 1402 is smaller than the diameter of the connecting section 1403, and the diameter of the clamping section 1401 is smaller than the diameter of the working section 1402.

[0122] Specifically, the diameter of the mandrel retaining ring 15 is larger than the outer diameter of the second constant diameter section 3 of the forging. When drawing, the mandrel retaining ring 15 is used and is sleeved at the connection between the working section 1402 and the connecting portion 1403. The mandrel retaining ring 15 can prevent the end face of the forging from cracking and concave center and facilitate demoulding of the mandrel.

[0123] Specifically, Figure 4 is a schematic diagram of the first lower die, Figure 5 is a schematic diagram of the second lower die. Figure 6 is a schematic diagram of the punch rod. Figure 7 This is a schematic diagram of the punch ring. Figure 8 is a schematic diagram of the bottom pad. Fig. 9Schematic diagram of the core rod. The inner wall of the upper surface of the first lower die 1201 is provided with a chamfer; the inner diameter D6 of the first lower die 1201 is 1650 mm, the inner diameter D5 of the positioning groove at the bottom of the first lower die 1201 is 1955 mm, and the height H7 of the first lower die 1201 is 740 mm; the inner diameter D7 of the upper surface of the second lower die 1202 is 1650 mm, the inner diameter D3' of the lower surface of the second lower die 1202 is 1310 mm, the diameter D5' of the outer ring of the second lower die 1202 is 1950 mm, and the height H6 of the second lower die 1202 is 1450 mm; the punch The outer ring diameter D8 of the rod 1301 is 840mm, the height H8 of the boss of the punch rod 1301 is 220mm, and the diameter D12 of the boss is 640mm; the height H9 of the punch ring 1302 is 220mm, the inner diameter D13 of the punch ring 1302 is 645mm, and the outer diameter D9 of the punch ring 1302 is 900mm; the outer diameter D10 of the bottom pad 1203 is 1290mm; the maximum diameter D11 of the working section 1402 of the core rod is 900mm, and the length H4' of the working section 1402 of the core rod is 1900mm.

[0124] Example 3

[0125] This embodiment provides a forming method for a large forging with a flange and a deep blind hole of the embodiment 1, using the forming tool of the embodiment 2.

[0126] The specific steps of the forming method of the large flanged deep blind hole forging of this embodiment include:

[0127] S1. Making the steel ingot into a large preform forging with flange and deep blind hole;

[0128] S2, such as Fig.10 As shown in A, the preform is placed in the concave die 12, the third constant diameter section 7 of the preform cooperates with the first lower die 1201 of the concave die, and the conical inclined surface of the second lower die 1202 of the concave die cooperates with the third expanded diameter section 6;

[0129] S3, the movable crossbeam of the press presses down to drive the punch to move downward and start die forging; Fig.10 As shown in B, the punch stroke reaches the preset value and the loading stops;

[0130] S4, such as Fig.11 As shown, after the die forging is completed, the punch ring 1302 is locked by the inner hole blank, and the movable crossbeam of the press is lifted, and the movable crossbeam of the press drives the punch rod 1301 to be lifted. Since the soft pin cannot drive the weight of the blank, it is sheared and cut off, so that the punch ring 1302 remains in the inner hole of the forging;

[0131] S5, separating the forging blank from the die 12 after die forging, returning the forging blank to the furnace for reheating, and then lengthening the mandrel after reheating.

[0132] like Figure 2 As shown, the preform includes, from bottom to top, a second diameter expansion section 5, a third diameter expansion section 6, a third constant diameter section 7, a fourth diameter expansion section 8 and a fourth constant diameter section 9, which are connected in sequence. The angles k1, k2 and k3 between the outer cylindrical surfaces of the second diameter expansion section 5, the third diameter expansion section 6 and the fourth diameter expansion section 8 and the center line of the preform are 13.5°, 45° and 55° respectively. The upper surface of the fourth constant diameter section 9 is provided with a second central blind hole 10, which is truncated cone-shaped. The aperture of the upper surface of the second central blind hole 10 is larger than that of the lower surface, and α is 6°. There is a circular chamfer at the connection between the side wall of the second central blind hole 10 and the bottom wall of the second central blind hole 10, and there is a circular chamfer at the connection between the side wall of the second central blind hole 10 and the upper surface of the fourth constant diameter section 9. The upper surface of the fourth constant diameter section 9 is inclined downward in a direction gradually away from the center line of the preform, and β is 2°.

[0133] Specifically, the height L2 of the third expanded diameter section 6, the height L3 of the second expanded diameter section 5, the height L1 of the fourth constant diameter section 9, the diameter D0 of the upper surface of the second expanded diameter section 5, the height L4 of the second center blind hole 10, the diameter D4 of the lower surface of the second expanded diameter section 5, the diameter D2' of the lower surface of the second center blind hole 10, the diameter D1' of the third constant diameter section 7, the diameter D1" of the fourth constant diameter section 9, γ, and the total height H' of the preform are: L2=280mm, L3=1100mm, L1=800mm, D0=1148mm, L4=750mm, D4=640mm, D2'=900mm, D1'=1650mm, D1"=1920mm, γ=90°, H'=2520mm.

[0134] The forgings obtained in this embodiment have uniform grains, a grain size of 3 to 3.5, and a maximum grain size difference of 0.5 at different locations. During the preparation process of this embodiment, no defects such as cracks and concave cores were found.

[0135] At the end of forming, the forming force is the largest, reaching 14,000 tons. The maximum load of the forming press is 15,000 tons, which does not exceed the limit of the press. Compared with the original traditional forming method of 22,000 tons, the forming force is reduced by 8,000 tons.

[0136] The inventor has conducted a large number of experimental studies during the research process, and now uses some solutions with poor performance as comparative examples.

[0137] Comparative Example 1

[0138] This comparative example provides a forming method for a large forging with a flange and a deep blind hole, which is used to prepare a forging of the shape of Example 1.

[0139] The method of this comparative example adopts the traditional method, such as Fig.13As shown, the blank is directly punched and formed. However, this forming method requires a large forming force, about 22000T, which exceeds the limit of the press. Within the limit forming force range of the press, the punch stroke is short, leaving a large processing allowance at the bottom of the inner hole.

[0140] Comparative Example 2

[0141] This comparative example provides a forming method for a large forging with a flange and a deep blind hole, which is used to prepare a forging of the shape of Example 1.

[0142] The method of this comparative example is substantially the same as that of Example 4, except that:

[0143] Using ordinary preform (such as Fig.14 As shown, the preform shape is different from that of the present invention. When the forming force is large, the core rod needs to be stretched to a long length, which makes it difficult to form in one fire. As a result, the bottom is heated in multiple fires without forging ratio, and coarse grains and mixed grains exist at the bottom.

[0144] Comparative Example 3

[0145] This comparative example provides a forming method for a large forging with a flange and a deep blind hole, which is used to prepare a forging of the shape of Example 1.

[0146] The method of this comparative example is substantially the same as that of Example 4, except that:

[0147] If γ=140°, the tensile stress in the first constant diameter section will be too large, resulting in tensile cracking.

[0148] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A forming tool for large-scale flanged deep blind hole forgings, characterized in that: The forming tool comprises a platform (11) and a die (12) above the platform (11); the die (12) is hollow, and comprises a first lower die (1201) and a second lower die (1202); a conical inclined surface is arranged on the inner side of the upper end surface of the second lower die (1202), and the angle θ between the conical inclined surface and the center line of the die is 5° to 45°; a positioning groove is arranged on the bottom end surface of the first lower die (1201), and the upper end surface of the second lower die (1202) is inserted into the positioning groove.

2. The forming tool according to claim 1, characterized in that: The concave mold (12) further comprises a bottom pad (1203), wherein the bottom pad (1203) is placed in the second lower mold (1202), and the bottom pad (1203) is in the shape of a hollow ring.

3. The forming tool according to claim 1, characterized in that: The forming tool also includes a punch (13), and the punch (13) includes a punch rod (1301) and a punch ring (1302). The lower end of the punch rod (1301) is provided with a boss, and the punch ring (1302) is sleeved on the boss. The punch rod (1301) and the punch ring (1302) are connected by a soft pin (1303); the outer diameter D9 of the punch ring (1302) is greater than the outer diameter D8 of the punch rod (1301).

4. The forming tool according to claim 3, characterized in that: The outer side of the lower end of the punch ring (1302) is provided with a chamfer.

5. The forming tool according to claim 3, characterized in that: The material of the soft pin is Q235 steel or 45 steel.

6. The forming tool according to any one of claims 1 to 5, characterized in that: The forming tool also includes a core rod (14) and a core rod retaining ring (15), the core rod (14) includes a clamping section (1401) and a working section (1402), and the side of the working section (1402) is tapered; the clamping section (1401) and the working section (1402) are connected by a connecting section (1403) in the middle, the diameter of the working section (1402) is smaller than the diameter of the connecting section (1403), and the diameter of the clamping section (1401) is smaller than the diameter of the working section (1402).

7. A forming method for large flanged deep blind hole forgings, characterized in that: The forming method adopts the forming tool according to any one of claims 1 to 6, and the forming method comprises the following specific steps: S1. Making the steel ingot into a large preform forging with flange and deep blind hole; S2, placing the preform in the concave die, the third constant diameter section of the preform matches with the first lower die of the concave die, and the conical inclined surface of the second lower die of the concave die matches with the third expanded diameter section of the preform; S3, the movable crossbeam of the press presses down to drive the punch to move downward and start die forging; S4. After die forging is completed, the punch ring is locked by the inner hole blank, the movable crossbeam of the press is lifted, the movable crossbeam of the press drives the punch rod to lift, the soft pin is sheared off, and the punch ring remains in the inner hole of the forging; S5. Separate the forging blank from the die after die forging, return the forging blank to the furnace for reheating, and then lengthen the core rod to obtain a large forging with a flange and a deep blind hole.

8. The forming method according to claim 7, characterized in that: The large flanged deep blind hole forging preform comprises, from bottom to top, a second diameter expansion section (5), a third diameter expansion section (6), a third constant diameter section (7), a fourth diameter expansion section (8) and a fourth constant diameter section (9) which are connected in sequence; The angle k1 between the outer cylindrical surface of the second diameter expansion section (5) and the center line of the preform and the angle k2 between the outer cylindrical surface of the third diameter expansion section (6) and the center line of the preform meet the following relationship: k1<k2; A second central blind hole (10) is provided on the upper surface of the fourth constant diameter section (9); the second central blind hole (10) is truncated cone-shaped; the aperture of the upper surface of the second central blind hole (10) is larger than the aperture of the lower surface.

9. The forming method according to claim 8, characterized in that: The upper surface of the fourth constant diameter section (9) is inclined downward in a direction gradually moving away from the center line of the preform.

10. The forming method according to any one of claims 7 to 9, characterized in that: In S5, when the core rod is stretched, 100 to 200 mm of the end of the blank remains unpressed.

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