Forging method of special-shaped step barrel

Abstract

A forging method of a special-shaped step barrel belongs to the technical field of forging and comprises the steps of pressing a jaw and pressing edges and corners of a steel ingot body; a plane cover plate is adopted for upsetting, and upper and lower wide anvils are adopted for drawing; blanking, and performing secondary upsetting by adopting a spherical cover plate; indentation and material distribution are carried out, and steps are forged; punching and chambering in sections; according to the forging method for the step barrel, the problem that the blank allowance of the forge piece forged through a traditional method is large is solved, and the material utilization rate of the forge piece is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of forging, in particular to a forging method for a special-shaped step cylinder. Background Art

[0002] The cylinder is an important component of various pressure vessels, and its performance requirements are extremely strict. With the widespread application of pressure vessels, the shape of the cylinder has changed from simple to complex. For example, the external step on the surface of the thin-walled cylinder greatly increases the difficulty of forging the cylinder.

[0003] In the prior art, the traditional method of forging a stepped barrel is to increase the wall thickness of the barrel blank so that it covers the entire step, first forge a barrel blank without a step, and then machine the step on the thicker barrel blank during the subsequent machining process. The disadvantages of this conventional method are: 1. It increases material loss, making the preparation cost higher; 2. Machining destroys the metal streamlines at the middle stage of the stepped barrel, which greatly reduces the service life of this part.

[0004] Therefore, it is of great significance to reasonably improve the existing step cylinder forging method so that it has the advantages of high raw material utilization and long service life of the finished product. Summary of the invention

[0005] The technical purpose of the present invention is to provide a new forging method for a special-shaped step cylinder, which improves the tool selection, step sequence and process parameters in the forging method, so that the finished special-shaped step cylinder has significant advantages such as excellent performance, long service life of the finished product, and high raw material utilization rate, thereby greatly reducing production costs and improving product quality.

[0006] The present invention solves the above technical problems and adopts the following technical solutions: a forging method for a special-shaped step cylinder, comprising the steps of pressing jaws and chamfering; upsetting and drawing; blanking; secondary upsetting; jaw removal; punching and segmented hole expansion; and finishing and finished product production; in the secondary upsetting step, a spherical cover plate is used to upset the blank, the curvature of the spherical cover plate is 0.17-0.18 rad, and the curved surface of the spherical cover plate in contact with the blank needs to completely cover the upsetting surface of the blank before and after the secondary upsetting; A step of forging a step is also provided between the secondary roughening and the jaw removal steps. In the step of forging a step, a 700 mm narrow anvil and a 45° lower triangle are used to divide the material into upper and lower steps with the step junction of the blank as the boundary, and the pressing amount of the 45° lower triangle is controlled to be 100-200 mm. In the steps of punching and segmented reaming, the large diameter end of the blank is facing downward and the small diameter end is facing upward, and a hollow punch is used for punching. Then, a water-passing core rod, a horse bar and a narrow anvil are used to reame the step part and the barrel part of the blank respectively.

[0007] Furthermore, in the steps of jaw pressing and chamfering, the steel ingot raw material needs to be placed in a heating furnace and subjected to heat preservation treatment at a temperature of 1050-1200°C for 8-12 hours before jaw pressing and chamfering.

[0008] Furthermore, in the upsetting and drawing steps, the blank needs to be placed in a heating furnace, and the heating furnace is controlled to heat up to 1200~1250℃, and insulation treatment is carried out for 18~36h. After that, the blank is upset with a flat cover plate and a leak plate tooling, and the upsetting ratio is controlled to be 2.0~2.5. Then, the operating machine clamps the jaws and uses a wide anvil for drawing, controlling the reduction amount of each drawing to be 15~30%, and drawing is performed 8~10 times.

[0009] Furthermore, in the step of cutting, the blank needs to be placed in a heating furnace first, and subjected to heat preservation treatment at a temperature of 1200-1250°C for 4-8 hours, and then the blank is cut off and cut into pieces and roughened for the second time.

[0010] Furthermore, in the secondary upsetting step, the curvature of the spherical cover plate is 0.175 rad.

[0011] Furthermore, in the secondary upsetting step, the upsetting ratio needs to be controlled to be 2.0-2.5.

[0012] Furthermore, in the step of forging the step, the blank needs to be placed in a heating furnace first, and subjected to a heat preservation treatment at a temperature of 1200-1250° C. for 4-6 hours, and then the step forging operation is performed.

[0013] Furthermore, in the step of removing the jaws, the blank needs to be placed in a heating furnace and subjected to a heat preservation treatment at a temperature of 1200-1250°C for 2-5 hours before the jaws are removed and punching and segmented hole expansion are performed.

[0014] Furthermore, in the steps of punching and segmented hole expansion, a hollow punch is used to punch the blank from top to bottom.

[0015] Furthermore, in the steps of finishing and producing the finished product, the blank must first be placed in a heating furnace and subjected to a heat preservation treatment at a temperature of 1100-1200°C for 2-5 hours, and then finely expanded, rounded, and smoothed on the upper and lower end faces to obtain a finished special-shaped stepped cylinder.

[0016] Beneficial effects: 1. The forging method of a special-shaped step cylinder of the present invention processes the steel ingot raw material through a multi-step and orderly forging process, so that the blank is fully plastically deformed, and the internal quality defects inside the blank are eliminated to the greatest extent, so that the structure of the finished special-shaped step cylinder is more uniform and stable, and the comprehensive performance is more excellent. It well solves the problems of large blank margin, serious damage to metal streamlines, and short service life when forging such forgings by traditional methods, thereby improving the material utilization rate of the forgings, reducing production costs, and improving product quality and service life.

[0017] 2. A forging method for a special-shaped step cylinder of the present invention uses a spherical cover plate to perform secondary upsetting on the blank after cutting. During the secondary upsetting, the arc-shaped spherical surface of the spherical cover plate covers the upsetting surface of the blank, thereby changing the tensile stress state of the original upsetting surface into compressive stress to the greatest extent, preventing the blank from having a concave center phenomenon during the subsequent forging process, thereby improving its forming rate.

[0018] 3. In the forging method of a special-shaped step cylinder of the present invention, in the step of forging the step, a 700 mm narrow anvil and a 45° lower triangle are used for precise step-type material division, and the metal streamline at the junction of the 100-200 mm thick step and the cylinder is cut off in advance, thereby effectively avoiding the problem of excessive shear stress at the subsequent junction and the occurrence of forging cracks. This step uses a narrow anvil to forge a small step according to the shape of the product, and then uses a water-passing mandrel, a horse bar, and a narrow anvil to expand the hole in sections to achieve near-net forming of the step cylinder, improve material utilization, and greatly reduce the risk of cracks in the forged step.

[0019] 4. In the forging method of a special-shaped step cylinder of the present invention, a hollow punch is used for punching in the steps of punching and segmented hole expansion, thereby avoiding the conventional solid punching which squeezes the central defect of the blank to other places, and can remove the internal defects of the blank to the maximum extent, reduce the appearance of inclusions inside the forging, and improve the quality of the forging. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the forging flow chart of the present invention; Figure 2 This is a schematic diagram of the structure of the spherical cover plate used in Example 1; Figure 3 This is a schematic diagram of the structure of the step of forging a step in Example 1.

[0021] Figure numerals: 1. blank, 2. narrow anvil, 3. lower triangle. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, which should not be used to limit the protection scope of the present invention. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention.

[0023] The forging method of a special-shaped step cylinder of the present invention is to solve the problem of low material utilization rate and short service life of the special-shaped step cylinder produced by the traditional forging method, and provides a new forging method, which specifically comprises the following steps: 1) First heating: Place the raw steel ingot in a gas-fired heating furnace, heating to 1050~1200℃, keeping warm for 8~12h; 2) Pressing jaws and chamfering: Forging jaws that are convenient for the subsequent forging process operator to clamp, pressing the edges and corners of the ingot body to avoid forging cracks due to subsequent stress concentration and other problems; 3) Return to furnace for heating: The heating furnace is heated to 1200~1250℃, and the billet is returned to the furnace for heating and kept warm for 18~36h; 4) Upsetting and drawing: Use a flat cover plate and a leaking plate tooling to upset the blank, with an upsetting ratio of 2.0-2.5. Then operate the machine to clamp the jaws and use a wide anvil for drawing. The pressing amount for each drawing is 15-30%, and the drawing is repeated 8-10 times. 5) Return to the furnace for heating: the billet is returned to the furnace, heated to 1200~1250℃, and kept warm for 4~8h; 6) Blanking and secondary upsetting: pinch off the head and tail, cut off the excess material at both ends of the billet after stretching, use spherical cover plate for upsetting to prevent the end surface from being concave when forging small forging steps later. The upsetting ratio is 2.0~2.5; 7) Return to furnace for heating: the billet is returned to the furnace, heated to 1200~1250℃, and kept warm for 4~6h; 8) Forging steps: Use 45° lower triangle and 700 narrow anvil to divide the material, so as to avoid excessive local pressure when pressing out small steps, resulting in forging defects such as cracks and fractures. After forging the steps, stretching is performed; 9) Return to furnace for heating: return the step billet to the furnace, heating temperature is 1200~1250℃, keep warm for 2~5h; 10) Remove the jaws: remove the jaws; 11) Punching and segmented hole expansion: Place the large end of the blank downward and the small end upward, and use a hollow punch to punch holes to remove internal inclusion defects to the greatest extent. Then use a water-passing mandrel, a horse bar, and a narrow anvil to expand the flange part and the barrel part of the forging respectively; 12) Return to furnace for heating: Return the expanded billet to the furnace at a heating temperature of 1100~1200℃ and keep warm for 2~5h; 13) Finishing and production of finished products: fine-tune the rounding, level the upper and lower end surfaces, and forge the finished special-shaped step cylinder.

[0024] The process method of the present invention prepares a special-shaped step cylinder with excellent performance and long service life through reasonable process route setting, solves the problem of large blank margin in forging such forgings by traditional methods, and improves the material utilization rate of the forgings.

[0025] Example 1 The special-shaped step cylinder prepared in this embodiment specifically includes the following production process: 1) First heating: Place the raw steel ingot with a material of 12Mn and an ingot shape of 139T in a gas-fired heating furnace, heat to 1050°C, and keep warm for 10 hours; 2) Pressing jaws and chamfering: Forge jaws with a size of φ840×1200mm, and press the edges and corners of the ingot until there are no protrusions on the surface of the ingot; 3) Return to furnace for heating: The heating furnace is heated to 1200°C, the billet is returned to the furnace for heating and kept warm for 24 hours; 4) Upsetting and drawing: Use a flat cover plate and a leaking plate tooling to upset the blank, with an upsetting ratio of 2, a height of H=1600mm, and a diameter of φ=3300mm. Then operate the machine to clamp the jaws and use a 1800mm wide anvil for drawing. The pressing amount for each drawing is 15%, and the drawing is repeated 8 times. 5) Return to furnace for heating: the billet is returned to the furnace, heated to 1200℃, and kept warm for 6 hours; 6) Cutting and secondary upsetting: rounding and elongating, cutting the head and tail, cutting φ2000×4000, using spherical cover plate for upsetting, the spherical size of the spherical cover plate is as shown in the attached Figure 2 As shown, the upsetting ratio is 2.5, the height H = 1660 mm, and the diameter φ = 3200 mm; 7) Return to furnace for heating: the billet is returned to the furnace, heated to 1200℃, and kept warm for 5h; 8) Forging steps: Use 45° lower triangle and 700 narrow anvil to divide the steps, as shown in the attached Figure 3 As shown, the small step material has a diameter of φ=3200mm, L=470mm, and is drawn to φ2400×L using a 700mm narrow anvil; 9) Return to furnace for heating: return the step billet to the furnace, heating temperature 1200℃, keep warm for 3h; 10) Remove the jaws: remove the jaws; 11) Punching and segmented hole expansion: The large end of the blank faces downward and the small end faces upward. Use a φ1000 hollow punch for punching. Then use a φ800 water-permeated mandrel, a horse bar, and a 700 narrow anvil to expand the small step part and the large end part of the cylinder to an inner hole of φ=1200mm, an outer circle of the small end of φ=2400mm, and an outer circle of the large end of φ=3200mm.

[0026] 12) Return to furnace for heating: return the expanded billet to the furnace, heating temperature 1100℃, keep warm for 3h; 13) Finishing and production of finished products: precision expansion and rounding, flattening of upper and lower end surfaces, forging of finished products with inner hole φ=1870mm, small end outer circle φ=2750mm, large end outer circle φ=3870mm, small end height H=620mm, large end height H=1050mm.

[0027] During the forging process of this embodiment, no cracks caused by forging occurred, no internal inclusion defects were found by ultrasonic testing, and 28.47 kg of material was saved.

[0028] Example 2 The special-shaped step cylinder prepared in this embodiment specifically includes the following production process: 1) First heating: Place the raw steel ingot with a material of 12Cr2Mo1V and an ingot shape of 180T in a gas-fired heating furnace, heating to a temperature of 1200°C and keeping warm for 12 hours; 2) Pressing jaws and chamfering: Forge jaws with a size of φ1200×1500mm, and press the edges and corners of the ingot until there are no protrusions on the surface of the ingot; 3) Return to furnace for heating: The heating furnace is heated to 1250°C, the billet is returned to the furnace for heating and kept warm for 32 hours; 4) Upsetting and drawing: Use a flat cover plate and a leaking plate tooling to upset the blank, with an upsetting ratio of 2.4, a height of H=1800mm, and a diameter of φ=3600mm. Then operate the machine to clamp the jaws and use a 1800mm wide anvil for drawing. The pressing amount for each drawing is 15%, and the drawing is repeated 8 times. 5) Return to furnace for heating: the billet is returned to the furnace, heated to 1250℃, and kept warm for 8h; 6) Cutting and secondary upsetting: rolling and stretching, cutting the head and tail, cutting φ2300×4000, using spherical cover plate for upsetting, upsetting ratio 2.5, height H=1660mm, diameter φ=3200mm; 7) Return to furnace for heating: the billet is returned to the furnace, heated to 1250℃, and kept warm for 6 hours; 8) Forging steps: Use 45° lower triangle clamp and 700 narrow anvil clamp to divide the material into steps. The diameter of the small step material is φ=3300mm, L=500mm, and the 700mm narrow anvil is used to draw it to φ2400×L; 9) Return to furnace for heating: return the step billet to the furnace, heating temperature 1250℃, keep warm for 5h; 10) Remove the jaws: remove the jaws; 11) Punching and segmented reaming: Punching and segmented reaming: The large end of the blank faces downward and the small end faces upward. A φ1000 hollow punch is used for punching. Then a φ800 water-permeated mandrel, a horse bar, and a 700 narrow anvil are used to reaming the small step part and the large end part of the cylinder to an inner hole of φ=1200mm, an outer circle of the small end of φ=2400mm, and an outer circle of the large end of φ=3200mm.

[0029] 12) Return to furnace for heating: return the expanded billet to the furnace, heating temperature 1200℃, keep warm for 5h; 13) Finishing and production of finished products: precision expansion and rounding, flattening of upper and lower end faces, forging of finished products with inner hole φ=1800mm, small end outer circle φ=2800mm, large end outer circle φ=3850mm, small end height H=750mm, large end height H=1200mm.

[0030] During the forging process of this embodiment, no cracks caused by forging occurred, no internal inclusion defects were found by ultrasonic testing, and 32.34T of material was saved.

[0031] Comparative Example 1 The special-shaped step cylinder prepared in this embodiment has the same size as that in Embodiment 1 and is forged by a traditional method. The specific production process is as follows: 1) First heating: Place the raw steel ingot with a material of 12Mn and an ingot shape of 170T in a gas-fired heating furnace, heating to a temperature of 1050°C and keeping warm for 10 hours; 2) Pressing jaws and chamfering: Forge jaws with a size of φ1200×1500mm, and press the edges and corners of the ingot until there are no protrusions on the surface of the ingot; 3) Return to furnace for heating: The heating furnace is heated to 1200°C, the billet is returned to the furnace for heating and kept warm for 24 hours; 4) Upsetting and drawing: Use a flat cover plate and a leaking plate tooling to upset the blank, with an upsetting ratio of 2, a height of H=1600mm, and a diameter of φ=3300mm. Then operate the machine to clamp the jaws and use a 1800mm wide anvil for drawing. The pressing amount for each drawing is 15%, and the drawing is repeated 8 times. 5) Return to furnace for heating: the billet is returned to the furnace, heated to 1200℃, and kept warm for 6 hours; 6) Blanking and secondary upsetting: rounding and drawing, blanking φ2000×4000, using flat cover plate for upsetting, upsetting ratio 2.5, height H=1660mm, diameter φ=3200mm; 7) Return to furnace for heating: the billet is returned to the furnace, heated to 1200℃, and kept warm for 5h; 8) Punching and expanding holes: Use a φ1000 solid punch for punching, and then use a φ800 water-permeable core rod, a horse bar, and a 700 narrow anvil to expand the entire cylinder to an inner hole of φ=1200mm and an outer circle of φ=3200mm.

[0032] 9) Return to furnace for heating: return the expanded billet to the furnace, heating temperature 1100℃, keep warm for 3h; 10) Finishing and production of finished products: precision expansion and rounding, flattening of upper and lower end faces, and forging of finished products with special-shaped stepped cylinder forgings with inner hole φ=1870mm, outer circle φ=3870mm and height H=1670mm.

[0033] During the forging process of this example, the forging allowance increased because the forging blank wrapped the cylinder step, so the required raw material steel ingot increased from 139T to 170T, and about 30T of steel was wasted; in the subsequent ultrasonic testing, a small amount of flaw detection defects were found, with a defect diameter of about φ2.3 and distributed along the inner wall.

[0034] The embodiments herein selected for the purpose of disclosing the present invention are those presently considered suitable, but it should be understood that the present invention is intended to include all changes and modifications of the embodiments that fall within the concept and scope of the present invention.

Claims

1. A forging method for a special-shaped stepped cylinder, comprising the steps of pressing the jaws and chamfering; upsetting and stretching; blanking; secondary upsetting; jaw removal; punching and segmented hole expansion; and finishing and finished product production; characterized in that: In the secondary upsetting step, a spherical cover plate is used to upset the blank. The curvature of the spherical cover plate is 0.17-0.18 rad, and the curved surface of the spherical cover plate in contact with the blank needs to completely cover the upsetting surface of the blank before and after the secondary upsetting. A step of forging a step is also provided between the secondary roughening and the jaw removal steps. In the step of forging a step, a 700 mm narrow anvil and a 45° lower triangle are used to divide the material into upper and lower steps with the step junction of the blank as the boundary, and the pressing amount of the 45° lower triangle is controlled to be 100-200 mm. In the steps of punching and segmented reaming, the large diameter end of the blank is facing downward and the small diameter end is facing upward, and a hollow punch is used for punching. Then, a water-passing core rod, a horse bar and a narrow anvil are used to reame the step part and the barrel part of the blank respectively.

2. The forging method of a special-shaped step cylinder according to claim 1, characterized in that: In the steps of jaw pressing and chamfering, the steel ingot raw material must first be placed in a heating furnace and subjected to insulation treatment at a temperature of 1050-1200°C for 8-12 hours before jaw pressing and chamfering are performed.

3. The forging method of a special-shaped step cylinder according to claim 1, characterized in that: In the upsetting and drawing steps, the blank needs to be placed in a heating furnace, and the heating furnace is controlled to heat up to 1200~1250℃, and then kept warm for 18~36h. After that, the blank is upset with a flat cover plate and a leaking plate tooling, and the upsetting ratio is controlled to be 2.0~2.

5. Then, the operating machine clamps the jaws and uses a wide anvil for drawing, controlling the reduction amount for each drawing to be 15~30%, and drawing is performed 8~10 times.

4. The forging method of a special-shaped step cylinder according to claim 1, characterized in that: In the step of cutting, the blank needs to be placed in a heating furnace first, and kept warm at 1200~1250℃ for 4~8h, and then the blank is cut off and roughened for the second time.

5. The forging method of a special-shaped step cylinder according to claim 1, characterized in that: In the secondary upsetting step, the curvature of the spherical cover plate is 0.175 rad.

6. A forging method for a special-shaped step cylinder according to claim 1 or 5, characterized in that: In the secondary upsetting step, the upsetting ratio needs to be controlled at 2.0~2.

5.

7. The forging method of a special-shaped step cylinder according to claim 1, characterized in that: In the step of forging the steps, the blank must first be placed in a heating furnace and subjected to a heat preservation treatment at a temperature of 1200-1250°C for 4-6 hours before the step forging operation is performed.

8. The forging method of a special-shaped step cylinder according to claim 1, characterized in that: In the step of removing the jaws, the blank must first be placed in a heating furnace and subjected to a heat preservation treatment at a temperature of 1200-1250°C for 2-5 hours, and then the jaws are removed and punched and the holes are expanded in sections.

9. The forging method of a special-shaped step cylinder according to claim 1, characterized in that: In the steps of punching and segmented hole expansion, a hollow punch is used to punch the blank from top to bottom.

10. The forging method of a special-shaped step cylinder according to claim 1, characterized in that: In the steps of trimming and producing finished products, the blank must first be placed in a heating furnace and subjected to insulation treatment at a temperature of 1100~1200℃ for 2~5 hours, and then fine-expanded, rounded, and the upper and lower end faces are smoothed in turn to forge the finished special-shaped stepped cylinder.

Images