CN112453305B - Forming die and method for inhibiting local extrusion cracks - Google Patents
Forming die and method for inhibiting local extrusion cracks Download PDFInfo
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- CN112453305B CN112453305B CN202011177681.0A CN202011177681A CN112453305B CN 112453305 B CN112453305 B CN 112453305B CN 202011177681 A CN202011177681 A CN 202011177681A CN 112453305 B CN112453305 B CN 112453305B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J13/00—Details of machines for forging, pressing, or hammering
- B21J13/02—Dies or mountings therefor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/02—Die forging; Trimming by making use of special dies ; Punching during forging
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Abstract
The invention discloses a forming die and a method for inhibiting local extrusion cracks, wherein the forming die comprises an upper die and a lower die, and further comprises the following steps: the extrusion buffering piece is placed in the forming cavity of the lower die in a clearance fit manner before extrusion, and applies axial flow resistance to the extending end of the blank through synchronous deformation with the blank in the extrusion process; the die angle θ of the lower die is proportional to the selected billet extrusion ratio. On one hand, the equivalent strain value at the extrusion port is lower than the maximum deformation which can be borne by a forging material through designing a reasonable extrusion port die angle, so that the grid distortion at the joint of the forged disc rod obtained by forging is obviously reduced, and the generation of cracks at the joint of the forged disc rod is avoided; on the other hand, the extrusion buffering piece is added at the bottom of the blank, the axial flow resistance of the blank is increased through the extrusion buffering piece, and the three-way compressive stress is enhanced, so that a part of axial additional tensile stress is offset, and the possibility of generating cracks is further reduced.
Description
Technical Field
The invention relates to the field of extrusion forming, in particular to a forming die and a forming method for inhibiting local extrusion cracks.
Background
The turbine disc and the turbine short shaft are one of the most important parts of an aircraft engine or a gas turbine, and are mainly made of nickel-based and cobalt-based high-temperature alloys such as GH4169 and GH500 under the severe conditions of high temperature, high speed and high load after long-term operation, and forged blanks are usually adopted.
A turbine disc and a turbine short shaft forging of a certain type of aero-engine are disc-shaft integrated structures, and a local heading and extrusion rod forming mode is adopted. During preparation, the prefabricated blank of the front turning cone or the drawing rod part is heated and then put into a die cavity of a forging press to apply pressure, so that the upper part is upset and the lower part is extruded and formed. By adopting the method, the forming efficiency can be improved (the disc part and the rod part are formed in one step), and meanwhile, the disc part and the rod part can be ensured to have certain deformation, so that the forming method is generally adopted by the conventional turbine disc and turbine short shaft forgings, but the rod part has certain local extrusion deformation, and the nickel-based and cobalt-based high-temperature alloys have the characteristics of high alloying degree, poor plasticity, large deformation resistance and the like, and cracks are often generated at the joint of the disc and the rod in the forming process.
Disclosure of Invention
The invention provides a forming die for inhibiting local extrusion cracks, and aims to solve the technical problem that cracks often appear at the joint of a disk rod in the forming process due to the characteristics of poor plasticity, large deformation resistance and the like of the conventional turbine disk and turbine short shaft forgings.
The technical scheme adopted by the invention is as follows:
a forming die for inhibiting local extrusion cracks comprises an upper die and a lower die, and further comprises:
the extrusion buffering piece is placed in the forming cavity of the lower die in a clearance fit manner before extrusion, and applies axial flow resistance to the extending end of the blank through synchronous deformation with the blank in the extrusion process;
the die angle θ of the lower die is proportional to the selected billet extrusion ratio.
Further, the extrusion bolster adopts plastic deformation's buffering metalwork, after blank stamping forming, the volume of the shared space after the buffering metalwork compression equals model cavity volume and the difference of forging volume down, the entity volume after the buffering metalwork compression is less than model cavity volume and the difference of forging volume down.
Further, the buffer metal piece is made of No. 45 steel.
Furthermore, the buffer metal part adopts an annular metal backing ring provided with a central through hole, and the height of the metal backing ring is equal to the height of a lower cavity of the lower die when the blank is placed before forming.
Further, the outer diameter of the metal backing ring is smaller than the minimum inner diameter of the lower die cavity, and the diameter of the central through hole of the metal backing ring meets the condition: when the blank is extruded in place to obtain the required forged piece, the diameter of the central through hole after the metal backing ring is synchronously deformed is larger than 0.
Furthermore, the buffer metal part is made of columnar metal, the height of the columnar metal is equal to the height of a lower cavity of the lower die when the lower die is placed before blank forming, and a plurality of cavities are uniformly formed in the columnar metal.
Further, the outer diameter of the columnar metal is smaller than the minimum inner diameter of the cavity of the lower mold, and the cavity inside the columnar metal meets the condition: when the blank is extruded in place to obtain the required forging, the sum of the volumes of all cavities in the columnar metal after synchronous deformation is larger than 0.
Further, the outer diameter of the extrusion buffer is 0.5-2mm larger than the minimum inner diameter of the lower die cavity.
Further, the extrusion die angle θ of the lower die satisfies the condition:
the equivalent strain produced after the billet has been extruded is lower than the maximum tensile strain epsilon that the material of the billet can withstand in the forging temperature range max And is greater than the critical strain epsilon Critical point of ：
Wherein D is the diameter of the initial blank, and D is the diameter of the rod part of the forged piece after extrusion forming.
In another aspect, the present invention provides a forming method for inhibiting local extrusion cracking, comprising the steps of:
cutting off the blank according to the length requirement, and turning the excircle of one end of the cut blank into a cone, wherein the turning length is 20-30mm, and the diameter of the turned cone is matched with the inner diameter of the lower die;
spraying a lubricant on the blank after turning the cone, heating to a forging temperature specified by a standard, and simultaneously heating an extrusion buffer prepared in advance to the same temperature as the blank;
and placing the heated extrusion buffer piece at the bottom of the lower die cavity heated in advance, placing the heated blank at the upper part of the extrusion buffer piece, and then pressing the upper die by a press machine to drive the blank to be extruded into the lower die cavity for forming so as to obtain the required forging.
The invention has the following beneficial effects:
on one hand, the equivalent strain value at the extrusion port is lower than the maximum deformation which can be borne by a forging material through designing a reasonable extrusion port die angle, so that the grid distortion at the joint of the forged disc rod obtained by forging is obviously reduced, and the generation of cracks at the joint of the forged disc rod is avoided; on the other hand, the extrusion buffering piece is added at the bottom of the blank, the axial flow resistance of the blank is increased through the extrusion buffering piece, and the three-way compressive stress is enhanced, so that a part of axial additional tensile stress is offset, the possibility of crack generation is further reduced, and the forging quality is ensured.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic view of a forming die for suppressing local extrusion cracks (without an extrusion cushion) according to a preferred embodiment of the present invention.
Fig. 2 is a schematic view of a forming die for inhibiting local extrusion cracking according to a preferred embodiment of the present invention before extrusion.
FIG. 3(a) is a schematic diagram of the grid distribution at the corner of a forged piece extruded by the existing extrusion process.
FIG. 3(b) is a schematic diagram of the grid distribution at the corner of the forged piece after the angle extrusion of the extrusion die optimized by the invention.
FIG. 4 is a schematic view of a turbine disk forging in an embodiment of the invention.
FIG. 5 is a schematic cross-sectional view of a metal backing ring according to an embodiment of the present invention.
FIG. 6 is a schematic cross-sectional view of a metal pillar in accordance with an embodiment of the present invention.
Fig. 7 is a schematic view of a blank after turning a cone according to an embodiment of the present invention.
FIG. 8 is a schematic view of a forming die of an embodiment of the present invention after extrusion to inhibit localized extrusion cracking.
Fig. 9(a) is a schematic diagram of damage value distribution of a forging NLC extruded by a conventional extrusion process.
FIG. 9(b) is a schematic diagram of the first principal stress distribution of a forged part extruded by the existing extrusion process.
Fig. 10(a) is a schematic diagram of the distribution of NLC damage values of a forged piece extruded by the extrusion process according to the embodiment of the invention.
FIG. 10(b) is a schematic diagram of the first principal stress distribution of the forged part after extrusion by the extrusion process of the embodiment of the invention.
In the figure: 1. an upper die; 2. a lower die; 3. a blank; 4. extruding the buffer member; 5. and (5) forging.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
Referring to fig. 1 and 2, a preferred embodiment of the present invention provides a forming die for suppressing local extrusion cracks, including an upper die 1 and a lower die 2, further including:
the extrusion buffering piece 4 is placed in the forming cavity of the lower die 2 in a clearance fit manner before extrusion, and applies axial flow resistance to the extension end of the blank 3 through synchronous deformation with the blank 3 in the extrusion process; the die angle theta of the extrusion opening of the lower die 2 is in direct proportion to the extrusion ratio D/D of the selected blank 3, and D is.
The forming die for inhibiting the local extrusion cracks of the embodiment comprises an upper die 1, a lower die 2 and an extrusion buffering member 4, wherein the extrusion die angle theta of the lower die 2 is in direct proportion to the extrusion ratio D/D of the selected blank 3, namely the larger the extrusion ratio D/D of the selected blank 3 is, the larger the extrusion die angle theta of the lower die 2 is. And the extrusion buffering piece 4 is placed in the forming cavity of the lower die 2 in a clearance fit manner before extrusion, and is synchronously deformed with the blank 3 in the extrusion process, so that axial flow resistance is applied to the extension end of the blank 3. Therefore, on one hand, the equivalent strain value at the extrusion opening is lower than the maximum deformation amount which can be borne by the forging material through designing the reasonable die angle theta of the extrusion opening, as shown in fig. 3(a) and 3(b), the grid distortion at the joint of the forging disc rod obtained by adopting the die in the embodiment is obviously reduced, and the crack at the joint of the forging disc rod is avoided; on the other hand, in the embodiment, the extrusion buffer is added at the bottom of the blank 3, the axial flow resistance of the blank 3 is increased through the extrusion buffer 4, and the three-way compressive stress is enhanced, so that a part of axial additional tensile stress is offset, the possibility of crack generation is further reduced, and the forging quality is ensured.
In a preferred embodiment of the present invention, the extruding and buffering member 4 is a plastically deformable buffering metal member, after the stamping forming of the blank 3 is completed, the volume of the space occupied by the buffering metal member after compression is equal to the difference between the volume of the cavity of the lower die 2 and the volume of the forging 5, and the solid volume of the buffering metal member after compression is smaller than the difference between the volume of the cavity of the lower die 2 and the volume of the forging 5.
In this embodiment, the extruding buffer member 4 is a plastically deformable buffering metal member, such as a buffering metal member made of 45 # steel with good plasticity, and in addition, in order to ensure smooth proceeding of the extruding process, although the extruding buffer member 4 can form axial resistance to the blank 3 in the extruding process, the extruding buffer member cannot prevent smooth proceeding of the extruding process, therefore, in this embodiment, after the punch forming of the blank 3 is completed, the volume of the space occupied by the compressed buffering metal member is equal to the difference between the volume of the cavity of the lower die 2 and the volume of the forging 5, and the volume of the compressed buffering metal member is smaller than the difference between the volume of the cavity of the lower die 2 and the volume of the forging 5. That is to say, even after the extrusion is finished, the solid volume of the compressed buffer metal part is smaller than the difference between the volume of the cavity of the lower die 2 and the volume of the forging 5, so as to ensure that the die can be extruded in place, otherwise, the blank 3 is not extruded in place, but because the buffer metal part completely fills the cavity between the forging 5 and the bottom of the cavity of the lower die 2, at this time, the press cannot push the upper die 1 and the blank 3 to continue to extrude downwards, so that the forging 5 with the preset size cannot be obtained, but the buffer metal part of the embodiment can form axial resistance on the blank 3 in the extrusion process, and meanwhile, the blank cannot be prevented from being extruded to obtain the forging with the final size, so as to ensure that the extrusion operation is carried out smoothly.
In a preferred embodiment of the invention, as shown in fig. 5, the buffer metal member is an annular metal backing ring provided with a central through hole, and the outer diameter of the metal backing ring is 1mm larger than the minimum inner diameter of the cavity of the lower die 2. The height of the metal backing ring is equal to the height of a lower cavity of the lower die 2 when the blank 3 is placed before forming. The external diameter of the metal backing ring is smaller than the minimum internal diameter of the cavity of the lower die 2, and the diameter of the central through hole of the metal backing ring meets the condition that: when the blank 3 is extruded in place to obtain the required forged piece 5, the diameter of the central through hole after the metal backing ring is synchronously deformed is larger than 0.
In the embodiment, the buffer metal part adopts an annular metal backing ring provided with a central through hole, and the outer diameter of the metal backing ring is 1mm larger than the minimum inner diameter of the cavity of the lower die 2, so that the metal backing ring can be ensured to be smoothly placed into the cavity of the lower die 2; the height of the metal backing ring is equal to the height of a lower cavity of the lower die 2 when the blank 3 is placed before forming, so that the metal backing ring can form axial resistance on the blank 3 in the extrusion process, meanwhile, the diameter of the central through hole of the metal backing ring is gradually reduced along with the synchronous deformation of the blank 3, even after the extrusion is finished, the diameter of the central through hole is still larger than 0, namely, the metal backing ring is guaranteed to have a plastic deformation margin in the extrusion process through the central through hole in the embodiment, the plastic deformation can be carried out all the time, the blank cannot be prevented from being extruded to obtain the forging 5 with the final size due to the incapability of carrying out the plastic deformation, and the smooth extrusion operation is guaranteed.
In a preferred embodiment of the present invention, as shown in fig. 6, the buffer metal member is made of a columnar metal having an outer diameter 1mm larger than the minimum inner diameter of the cavity of the lower mold 2. The height of the columnar metal is equal to the height of a cavity at the lower part of the lower die 2 when the blank 3 is placed before forming, and a plurality of cavities are uniformly arranged in the columnar metal. The outer diameter of the columnar metal is smaller than the minimum inner diameter of the cavity of the lower die 2, and the cavity inside the columnar metal meets the conditions: and when the blank 3 is extruded in place to obtain the required forging 5, the sum of the volumes of all cavities in the columnar metal after synchronous deformation is more than 0.
In this embodiment, the buffer metal member is made of a cylindrical metal, and a plurality of cavities are uniformly formed in the cylindrical metal. The outer diameter of the columnar metal is 1mm larger than the minimum inner diameter of the cavity of the lower die 2, namely a 1mm gap is reserved between the outer diameter of the columnar metal and the minimum inner diameter of the cavity of the lower die 2, so that the columnar metal can be ensured to be smoothly placed into the cavity of the lower die 2; the height of the columnar metal is equal to the height of the lower cavity of the lower die 2 when the billet 3 is placed before forming, so that the columnar metal in the embodiment can form axial resistance on the billet 3 in the extrusion process, meanwhile, the size of the cavity inside the columnar metal is gradually reduced in the synchronous deformation process of the billet 3, and even after the extrusion is finished, the sum of the volumes of the cavities inside the columnar metal is greater than 0.
For the extrusion forming of an axisymmetric part, the strain tensor at the extrusion die opening can be represented by a third-order tensor epsilon under a cylindrical coordinate system ij As shown below:
wherein epsilon ρ 、ε θ 、ε z Positive strain, gamma, in radial, circumferential, axial direction, respectively ρz And gamma zρ Is the tangential strain on the meridian plane. For crush deformation, the radial and circumferential positive strains are equal
Axial positive strain of
Tangential strain in meridian plane
In a preferred embodiment of the present invention, the extrusion die angle θ (rad) of the lower die 2 satisfies the condition: the equivalent strain produced after the extrusion of the billet 3 is lower than the maximum tensile strain that the material of the billet 3 can withstand:
wherein D is the diameter of the initial blank 3, and D is the diameter of the rod part of the forged piece 5 after extrusion forming; epsilon msx The maximum tensile strain that the material of the blank 3 can carry in its forging temperature interval is determined by consulting a handbook of materials or by tensile testing.
In other words, in order to ensure that the forging does not crack, the equivalent strain generated after the metal is squeezed in is lower than the maximum tensile strain which can be borne by the forging material, namely, the formula (1) is met.
For any metallic material, the degree of deformation experienced by the metal during thermoplastic deformation must be greater than the critical strain ε Critical point of It is ensured that dynamic recrystallization takes place, i.e. the equivalent strain is greater than the critical strain:
as can be seen from the equations (1) and (2), the die angle θ is the maximum tensile strain ε that can be tolerated by the material of the billet 3 msx Critical strain epsilon Critical point of Initial blankThe diameter D of 3, the diameter D of the shank of the extruded forging 5. The larger the diameter D of the billet 3 is selected (i.e. the larger the extrusion ratio D/D), the larger the die angle theta of the extrusion die should be to ensure that the metal entering the extrusion deformation zone does not crack due to severe deformation.
The following description will explain the embodiment of the invention by taking a free turbine disk (made of GH4169) of an aircraft engine as an example (the forging drawing is shown in FIG. 4).
Through examination of relevant research documents (see "research on the structure and properties of Lihuyan, GH4169 Ni-based superalloy [ D ], northeast university, 2014: 37"), it is known that the GH4169 alloy material can bear a maximum deformation of about 85% (engineering strain) in terms of equivalent strain of 0.615 when stretched at 950 ℃. The forged piece is produced by adopting a raw material with the specification D equal to phi 95, and the diameter D of the rod part of the forged piece 5 equal to phi 90 after extrusion forming. The extrusion die angle calculated according to the formula (1) should satisfy theta >0.522 radian (≈ 30 °), at the moment, the larger theta is more beneficial to metal flow, in order to ensure that the forging can generate dynamic recrystallization during extrusion molding, the deformation amount of the forging is greater than the critical deformation amount, generally speaking, the critical deformation value of the dynamic recrystallization of the metal is 0.2, and the inlet angle of the extrusion film calculated according to the formula (2) should satisfy theta < 1.28 radian (≈ 73 °). Research shows that (see 'Wangcheng, GH4169 alloy forging structure forming mechanism and hot working process window [ D ], northwest industry university, 2018: 98'), for GH4169 alloy, when the equal effect is changed to 0.5-0.6, the dynamic recrystallization rate of the alloy reaches the maximum value, the dynamic recrystallization is most likely to occur at the moment, and the optimal value of the extrusion inlet angle theta of the die is determined to be 35 degrees through calculation of formulas (1) and (2).
In addition, a metal backing ring is prepared to serve as an extrusion buffering piece 4, the outer diameter of the metal backing ring is slightly smaller than the minimum diameter of the cavity of the lower die 2, and the height of the metal backing ring is equal to the height of the cavity of the lower die 2 when the blank 3 is placed before forming.
Based on the above arrangement, a preferred embodiment of the present invention also provides a forming method of suppressing local extrusion cracking, including the steps of:
s1, cutting the blank 3 according to phi 95 multiplied by 250 +/-1, and tapering the excircle of one end of the cut blank 3 for placing in a die, wherein the tapering length is 30mm, and the diameter after tapering is matched with the inner diameter of the lower die 2 (see figure 7);
s2, spraying a lubricant on the blank 3 after turning the cone, preheating the blank in an electric furnace for about 100min at 800 ℃, then heating the blank to 980 ℃ and preserving the heat for about 60min so as to heat the blank to the forging temperature specified by the standard, and simultaneously heating a metal backing ring prepared in advance to the same temperature of the blank 3, namely 980 ℃ and preserving the heat for 20 min;
and S3, discharging the heated metal backing ring out of the furnace, putting the heated metal backing ring into the bottom of a cavity of the lower die 2 which is heated in advance (the die needs to be heated to about 200 ℃ in advance), axially placing the metal backing ring, rapidly discharging the preheated blank 3 out of the furnace, putting the blank into the upper part of the metal backing ring in the cavity of the lower die 2, and finally pressing the upper die 1 under the action of a 1600T press, wherein the required forging 5 is obtained by one-time hammering (see figure 8).
In order to evaluate the effects of the above examples, Normalized Latham-Cockroft (NLC) damage values (see equation (3)) and the first principal stress were used as evaluation criteria. By comparing the maximum NLC damage value at the corner with the existing 0.25 to 0.15, the maximum value of the first main stress is reduced from 586MPa to 394.5MPa, so that the generation of cracks at the joint of the forged disc and the forged disc rod is effectively avoided.
Wherein, the expression of NLC damage value:
wherein epsilon f Equivalent strain after forging is completed;
σ 1 is a first principal stress;
Compared with the prior art, the method has obvious technical effects and overcomes the defects in the prior art, so that the grid distortion of the joint of the forged piece disc rods obtained by forging is obviously reduced, and the cracks at the joint of the forged piece disc rods are avoided.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The utility model provides a restrain forming die of local extrusion crack, includes mould (1), lower mould (2), its characterized in that still includes:
the extrusion buffer piece (4) is placed in a forming cavity of the lower die (2) in a clearance fit manner before extrusion, and is synchronously deformed with the blank (3) in the extrusion process, so that axial flow resistance is applied to the extending end of the blank (3);
the extrusion die angle theta of the lower die (2) is in direct proportion to the extrusion ratio of the selected billet (3).
2. The forming die for inhibiting the local extrusion cracks according to claim 1, wherein the extrusion buffer member (4) is a plastically deformable buffer metal member, when the blank (3) is punched and formed, the volume of the space occupied by the compressed buffer metal member is equal to the difference between the volume of the cavity of the lower die (2) and the volume of the forging (5), and the solid volume of the compressed buffer metal member is smaller than the difference between the volume of the cavity of the lower die (2) and the volume of the forging (5).
3. The forming die for suppressing local extrusion cracks according to claim 2, wherein the material of the buffer metal member is 45 steel.
4. The forming die for inhibiting the local extrusion cracks according to claim 2, wherein the buffer metal piece adopts an annular metal backing ring provided with a central through hole, and the height of the metal backing ring is equal to the height of a lower cavity of the lower die (2) when the blank (3) is placed before forming.
5. The forming die for inhibiting the local extrusion cracks according to claim 4, wherein the outer diameter of the metal backing ring is smaller than the minimum inner diameter of the cavity of the lower die (2), and the diameter of the central through hole of the metal backing ring meets the condition that: when the blank (3) is extruded in place to obtain the required forged piece (5), the diameter of the central through hole after the metal backing ring is synchronously deformed is larger than 0.
6. The forming die for inhibiting the local extrusion cracks as recited in claim 2, wherein the buffer metal piece is made of columnar metal, the height of the columnar metal is equal to the height of a lower cavity of the lower die (2) when the billet (3) is placed before forming, and a plurality of cavities are uniformly arranged in the columnar metal.
7. The forming die for inhibiting the local extrusion cracks according to claim 6, wherein the outer diameter of the columnar metal is smaller than the minimum inner diameter of a cavity of the lower die (2), and the cavity inside the columnar metal meets the condition that: when the blank (3) is extruded in place to obtain the required forging (5), the sum of the volumes of all cavities in the columnar metal after synchronous deformation is larger than 0.
8. The forming die for inhibiting local extrusion cracks according to claim 1, wherein the outer diameter of the extrusion cushion (4) is 0.5mm-2mm larger than the minimum inner diameter of the cavity of the lower die (2).
9. The forming die for suppressing local extrusion cracks according to claim 1, wherein an extrusion die angle θ of the lower die (2) satisfies a condition:
the equivalent strain produced after the billet (3) is extruded is lower than the maximum tensile strain epsilon that the material of the billet (3) can bear in the forging temperature range max And is greater than the critical strain epsilon Critical point of ：
Wherein D is the diameter of the initial blank (3), and D is the diameter of the rod part of the forged piece (5) after extrusion forming.
10. A forming method for suppressing local extrusion cracking, comprising the steps of:
cutting off the blank (3) according to the length requirement, and tapering the excircle of one end of the cut blank (3), wherein the tapered processing length is 20-30mm, and the diameter after tapering is matched with the inner diameter of the lower die (2);
spraying a lubricant on the blank (3) after the turning of the cone, heating to a forging temperature specified by a standard, and simultaneously heating an extrusion buffer piece (4) prepared in advance to the same temperature as the blank (3);
the heated extrusion buffer part (4) is placed at the bottom of a cavity of a lower die (2) which is heated in advance, a heated blank (3) is placed at the upper part of the extrusion buffer part, then a press machine is used for applying pressure to an upper die (1) to drive the blank (3) to be extruded into the cavity of the lower die (2) for forming, and a required forging (5) is obtained, wherein the die angle theta of an extrusion opening of the lower die (2) is in direct proportion to the extrusion ratio of the selected blank (3).
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| CN114160730B (en) * | 2021-12-06 | 2024-06-18 | 陕西宏远航空锻造有限责任公司 | Manufacturing method of large-size variable-cross-section GH4169 alloy power turbine rear shaft forging |
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| CN104108012A (en) * | 2014-07-28 | 2014-10-22 | 中国南方航空工业(集团)有限公司 | Forging method of disc-shaped integrated part and die used for forging method |
| CN105057529A (en) * | 2015-08-20 | 2015-11-18 | 西北工业大学 | Extrusion forming method for hollow shaft forged piece with variable cross section |
| CN111097808A (en) * | 2019-12-31 | 2020-05-05 | 天津重型装备工程研究有限公司 | Preparation method of GH4169 alloy bar |
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