Movable core rod and method for extruding small-aperture seamless tube / blind hole tube by large extruder

Abstract

The invention discloses a movable core rod which comprises a positioning part, a working part and a core rod body, the positioning part and the working part are located at the lower end and the upper end of the core rod body respectively, a conical slope is arranged at the rear end of the positioning part, and the inclination of the conical slope is smaller than or equal to 10 degrees. The invention further discloses a method for extruding the small-aperture seamless pipe / blind hole pipe through the large extruding machine. The technical problem that a large extruder cannot obtain a small-aperture seamless pipe or a blind hole pipe through extrusion is solved.

Description

Technical Field

[0001] The invention belongs to the field of seamless pipe forming, and in particular relates to a method for extruding a small-diameter seamless pipe / blind hole pipe using a movable mandrel and a large extruder. Background Art

[0002] With the emergence and development of extrusion technology, the extruder can use extrusion dies and mandrels to extrude metal hollow billets into products of different shapes. The process is relatively simple. During the extrusion process, the metal is subjected to three-dimensional compressive stress, the metal deformation capacity is improved, and the mechanical properties are improved. In addition, compared with forging, the extruded products have high dimensional accuracy, good surface quality, and the utilization rate of finished product materials is effectively improved.

[0003] The 36,000-ton vertical extruder is a large extruder that mainly produces large-diameter seamless pipes and bars. The inner hole size of the seamless pipe blank ranges from 200mm to 1100mm. However, due to the equipment structure characteristics of large extruders, for seamless pipes with inner holes below 200mm, due to the structure and strength of the mandrel, it is impossible to extrude them. The small-sized mandrel has low strength, one end is fixedly connected to the extrusion equipment, and a part passes through the hollow billet and extends into the extruded tube. It is easy to break during the extrusion process. After breaking, the extruded product is scrapped. It can only be extruded into bars or forged into bars, and small-diameter seamless pipes are manufactured by mechanical processing. This production process has low material utilization, high production costs, and low efficiency. For small-diameter seamless pipes made of high-alloy materials, the materials are expensive, which greatly increases the cost, which is very unfavorable for the application of pipes. Summary of the invention

[0004] The purpose of the present invention is to provide a movable mandrel and a method for extruding a small-diameter seamless pipe / blind hole pipe by a large extruder, which solves the technical problem that a large extruder cannot obtain a small-diameter seamless pipe or a blind hole pipe by extrusion.

[0005] To achieve the above purpose, the technical solution used in the present invention is:

[0006] The movable mandrel comprises a positioning part, a working part and a mandrel body. The positioning part and the working part are respectively located at the lower end and the upper end of the mandrel body. The rear end of the positioning part is provided with a conical inclined surface, and the inclination of the conical inclined surface is ≤10°.

[0007] Furthermore, the included angle between the tapered inclined surface and the end surface of the positioning portion is 80-90°.

[0008] Furthermore, the length of the tapered slope is 90-110 mm.

[0009] Furthermore, the included angle between the positioning portion and the outer wall surface of the working portion is 140-160°.

[0010] Furthermore, the end of the working portion is provided with a rounded corner or a chamfered corner.

[0011] The method of extruding a small-diameter seamless tube / blind hole tube by a large extruder comprises:

[0012] The steel ingot is formed into a hollow billet / blind hole tube billet through closed upsetting and perforation. After the hollow billet is finished and heated, the mold lubricant is applied to the movable core rod, and the hollow billet is sprayed with glass powder for lubrication.

[0013] Use a manipulator to clamp the hollow billet, insert the inner hole of the hollow billet / blind hole tube billet into the movable mandrel, apply downward pressure to the movable mandrel, and inlay the inner hole of the hollow billet and the positioning part of the movable mandrel together;

[0014] A manipulator is used to put the hollow billet / blind hole tube billet and the movable core rod into the extruder for extrusion, and the hollow billet is extruded into a small-diameter seamless tube / blind hole tube.

[0015] Preferably, the material of the hollow billet / blind hole tube billet is a nickel-based alloy, and the material of the movable core rod is 5CrNiMo.

[0016] Preferably, the electroslag ingot is upset in an upsetting tube and then perforated to form a hollow billet / blind hole tube billet.

[0017] Preferably, the hollow billet / blind hole tube billet is mechanically processed after air cooling, including: processing the inner hole of the hollow billet, the outer circle of the hollow billet, and chamfering the upper end of the hollow billet.

[0018] Preferably, when the total length of the movable mandrel is slightly longer than the hollow blank, it is used to extrude a seamless tube; when the total length of the movable mandrel is shorter than the blind hole blank, it is used to extrude a blind hole tube.

[0019] The technical effects of the present invention include:

[0020] 1. The present invention breaks the traditional method of fixed connection of the mandrel and provides a new process method for extruding small-diameter pipes. The movable mandrel does not move upward with the metal during the extrusion process, and can extrude small-diameter seamless pipes and blind-hole pipes, solving the technical problem that large extruders cannot extrude small-diameter seamless pipes and blind-hole pipes.

[0021] In order to solve the problem of high manufacturing cost and low service life of small-sized mandrels, a movable mandrel that is not fixedly connected to the equipment is designed. The lower end of the movable mandrel is the positioning part and the upper end is the working part. The inner hole size of the seamless pipe after extrusion is equivalent to the size of the mandrel. The size of the large diameter end of the lower end of the mandrel is equivalent to the inner hole diameter of the metal hollow billet. It is the positioning part and has an inclined design. During extrusion, the bottom of the movable mandrel is just the right size to match the bottom of the metal hollow billet. The inclined design ensures that the movable mandrel does not move upward with the metal during the extrusion process, and plays a positioning role. The head of the movable mandrel is rounded or chamfered to facilitate insertion into the inner hole of the billet.

[0022] 2. Before extrusion, assemble the heated blank and the movable mandrel together and extrude at the same time. After extrusion, the movable mandrel remains in the seamless tube, and the mandrel is destructively removed by mechanical processing. The present invention is mainly aimed at the extrusion of small-diameter seamless tubes of precious metals, and the cost of the mandrel is very low relative to the product. In addition, the present invention can also extrude blind-hole tubes. The problem of large-scale extruders extruding small-diameter seamless tubes and blind-hole tubes is solved, and the material utilization rate of such products is improved and the production cycle is shortened. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the movable mandrel in the present invention;

[0024] Figure 2 It is a schematic diagram of the movable mandrel and the large extruder in the present invention for extruding a seamless pipe with a small aperture;

[0025] Figure 3 It is a schematic diagram of the movable mandrel and the large extruder in the present invention for extruding a small-diameter blind hole tube. DETAILED DESCRIPTION

[0026] The following description sufficiently illustrates specific embodiments of the invention to enable those skilled in the art to practice and reproduce the invention.

[0027] like Figure 1 The figure is a schematic diagram of the structure of the movable mandrel 1 in the present invention.

[0028] The movable mandrel 1 comprises a positioning portion 11 , a working portion 12 , and a mandrel body 13 . The positioning portion 11 and the working portion 12 are respectively located at the lower end and the upper end of the mandrel body 13 .

[0029] The lower end of the movable mandrel 1 is a positioning portion 11, and the upper end is a working portion 12. The rear end of the positioning portion 11 is provided with a conical inclined surface 14. The angle α between the conical inclined surface and the end surface of the positioning portion 11 is 80-90° (inclination ≤ 10°, preferably 85°), and the length of the conical inclined surface 14 is 90-110mm (preferably 100mm). The end of the working portion 12 is provided with a rounded corner or chamfer to facilitate penetration into the inner hole of the blank. The outer wall surface of the positioning portion 11 and the working portion 12 has an angle of 140-160°.

[0030] The rear end size of the positioning part 11 is adapted to the inner diameter of the metal hollow billet. During extrusion, the rear end of the positioning part 11 is just matched with the bottom of the metal hollow billet. The conical slope 14 ensures that the movable mandrel 1 does not move upward with the metal during the extrusion process, and plays a positioning role. The inner hole size of the seamless pipe after extrusion is equivalent to the fixed size of the movable mandrel 1. The total length of the movable mandrel 1 is slightly longer than the metal hollow billet, and is used to extrude seamless pipes; the total length is less than the blind hole billet, and is used to extrude blind hole pipes.

[0031] Example 1: A large extruder extrudes a small-diameter seamless pipe.

[0032] The method of extruding small-diameter seamless tubes / blind hole tubes using a movable mandrel and a large extruder, the process flow: closed upsetting and perforation of steel ingots - billet finishing - coating with anti-oxidation coating - billet heating - descaling - lubrication - inserting a movable mandrel - placing in an extruder for extrusion.

[0033] The heating and holding time of the hollow blank 2 is determined according to the material properties.

[0034] like Figure 2 The figure shows a schematic diagram of the movable mandrel and the large extruder for extruding a small-diameter seamless pipe in the present invention.

[0035] Step 1: The steel ingot is subjected to closed upsetting and perforation to form a hollow billet;

[0036] The electroslag ingot with a diameter of 500mm is upset in an upset tube with a diameter of 700mm, and then pierced. The inner hole diameter of the billet after piercing is 115mm. The electroslag ingot material is nickel-based alloy 6617.

[0037] Step 2: finishing of the hollow blank 2;

[0038] After air cooling, the blank is machined to machine the inner hole of the blank to 125 mm, the outer circle of the blank to 680 mm, and the upper end is chamfered to C50.

[0039] Step 3: Processing the movable mandrel 1;

[0040] The movable mandrel material is 5CrNiMo, the upper end diameter is 115mm, the slope is 10° (α=80°), the lower end diameter of the working part 12 is 120mm, and the angle between the outer wall of the positioning part 11 and the working part 12 is 155°. The total length of the movable mandrel 1 is slightly longer than the hollow billet 2 and is used to extrude the seamless pipe. The length of the conical slope 14 is 110mm.

[0041] Step 4: heating the blank;

[0042] The hollow billet 2 is coated with an anti-oxidation coating before being loaded into the furnace for heating. The heating temperature of the hollow billet 2 is 1175°C, and the holding time is 6 hours.

[0043] Step 5: Lubrication of the blank;

[0044] After the hollow blank 2 is heated, the oxide scale on the surface is removed, the movable core rod 1 is coated with mold lubricant, and the hollow blank 2 is sprayed with glass powder for lubrication.

[0045] Step 6: The hollow blank 2 is inserted into the movable mandrel 1;

[0046] After the hollow blank 2 is sprayed with glass powder for lubrication, the manipulator is used to clamp the hollow blank 2, and the inner hole of the hollow blank 2 is inserted into the movable core rod 1 placed on the platform in advance. After the hollow blank 2 is inserted into the movable core rod 1, a certain force is applied downward to inlay the inner hole of the hollow blank 2 and the positioning part 11 of the movable core rod 1.

[0047] Step 7: The hollow billet 2 is placed in an extruder for extrusion;

[0048] The manipulator is used to clamp the hollow billet 2 and the movable core rod 1 together and put them into the extruder for extrusion, and the hollow billet 2 is extruded into a small-aperture seamless pipe. The specification is OD250*ID120mm small-aperture seamless pipe, and the material is nickel-based alloy 6617.

[0049] Example 2: Large extruder extruding small-diameter blind hole tube

[0050] like Figure 3 The figure shows a schematic diagram of the movable mandrel and the large extruder in the present invention for extruding a small-diameter blind hole tube.

[0051] Process flow: closed upsetting of steel ingot, drilling of blind holes - billet finishing - coating with anti-oxidation coating - billet heating - lubrication - insertion of movable mandrel - placing in extruder for extrusion.

[0052] Step 1: Closed upsetting and blind hole drilling of steel ingot;

[0053] The steel ingot is upset in a closed upsetting cylinder, and the perforation is stopped after a certain formation, thereby preparing a blind hole blank 3.

[0054] Step 2: finishing of blind hole blank 3;

[0055] The blind hole blank 3 is air-cooled and then machined, the upper end of the outer circle is chamfered C50, and the inner hole is machined to have a metallic luster.

[0056] Step 3: Processing of the movable mandrel 1;

[0057] The material of the movable mandrel 1 is 5CrNiMo, the height of the working part of the mandrel is 20mm shorter than the height of the through hole of the blank, the slope is 10°, the diameter of the lower end of the working part 11 is 100mm larger than the diameter of the inner hole of the blank, and the angle between the outer wall of the positioning part 11 and the working part 12 is 155°. The total length of the movable mandrel 1 is less than the blind hole blank 3, and is used to extrude the blind hole tube. The length of the tapered slope 14 is 110mm.

[0058] Step 4: heating the blind hole blank 3;

[0059] Blind hole blank 3 is coated with anti-oxidation paint before being loaded into the furnace for heating. The heating temperature of blind hole blank 3 is 1175℃, and the holding time is 6h.

[0060] Step 5: Apply mold lubricant to the movable core rod 1;

[0061] After the blind hole blank 3 is heated, there is no oxide scale on the surface, the movable core rod 1 is coated with mold lubricant, and the blind hole blank 3 is sprayed with glass powder for lubrication.

[0062] Step 6: The blind hole blank 3 passes through the movable mandrel 1;

[0063] After the blind hole blank 3 is sprayed with glass powder for lubrication, the blank 2 is clamped by a manipulator and inserted into the movable core rod 1 placed on the platform in advance. After the blind hole blank 3 is inserted, a certain force is applied downward to inlay the inner hole of the blind hole blank 3 and the positioning part of the movable core rod 1. The positioning part 11 is a large diameter end with an inclination at the lower end, and its function is to inlay and fix the core rod 1 and the blind hole blank 3 and to position it with the blind hole blank 3 during extrusion, so as to prevent the movable core rod 1 from moving relative to the undeformed metal product during the extrusion process.

[0064] Step 7: The blind hole blank 3 is placed in an extruder for extrusion.

[0065] A manipulator is used to clamp the blind hole blank 3 and the movable core rod 1 together and put them into an extruder for extrusion to form a blind hole tube.

[0066] Embodiment 3: Large-scale extruder extrudes small-diameter seamless pipes.

[0067] Process flow: closed upsetting and piercing of steel ingot - billet finishing - coating with anti-oxidation coating - billet heating - oxide scale removal - lubrication - insertion of movable mandrel - extrusion in extruder.

[0068] The method of extruding small-diameter seamless pipes and blind-hole pipes by a movable mandrel and a large extruder is as follows:

[0069] Step 1: The steel ingot is subjected to closed upsetting and perforation to form a hollow billet;

[0070] The electroslag ingot with a diameter of 500mm is upset in an upset tube with a diameter of 700mm, and then pierced. The inner hole diameter of the billet after piercing is 115mm. The electroslag ingot material is nickel-based alloy 6617.

[0071] Step 2: finishing of the hollow blank 2;

[0072] After air cooling, the blank is machined to machine the inner hole of the blank to 125 mm, the outer circle of the blank to 680 mm, and the upper end is chamfered to C50.

[0073] Step 3: Processing the movable mandrel 1;

[0074] The movable mandrel is made of 5CrNiMo, with an upper diameter of 115 mm and a slope of 9° (α=81°). The lower diameter of the working part 12 is 120 mm, and the angle between the outer wall of the positioning part 11 and the working part 12 is 153°. The total length of the movable mandrel 1 is slightly longer than the hollow billet 2 and is used to extrude the seamless pipe. The length of the tapered slope 14 is 100 mm.

[0075] Step 4: heating the blank;

[0076] Before loading the hollow billet 2 into the furnace for heating, an anti-oxidation coating is applied. The billet heating temperature is 1175°C and the holding time is 6h.

[0077] Step 5: Lubrication of the blank;

[0078] After the hollow blank 2 is heated, the oxide scale on the surface is removed, the movable core rod 1 is coated with mold lubricant, and the hollow blank 2 is sprayed with glass powder for lubrication.

[0079] Step 6: The hollow blank 2 is inserted into the movable mandrel 1;

[0080] After the hollow blank 2 is sprayed with glass powder for lubrication, the manipulator is used to clamp the hollow blank 2, and the inner hole of the hollow blank 2 is inserted into the movable core rod 1 placed on the platform in advance. After the hollow blank 2 is inserted into the movable core rod 1, a certain force is applied downward to inlay the inner hole of the hollow blank 2 and the positioning part 11 of the movable core rod 1.

[0081] Step 7: The hollow billet 2 is placed in an extruder for extrusion;

[0082] The manipulator is used to clamp the hollow billet 2 and the movable core rod 1 together and put them into the extruder for extrusion, and the hollow billet 2 is extruded into a small-aperture seamless pipe. The specification is OD250*ID120mm small-aperture seamless pipe, and the material is nickel-based alloy 6617.

[0083] Example 4: Large extruder extruding small-diameter blind hole tube

[0084] Process flow: closed upsetting of steel ingot, drilling of blind holes - billet finishing - coating with anti-oxidation coating - billet heating - lubrication - insertion of movable mandrel - placing in extruder for extrusion.

[0085] Step 1: Closed upsetting and blind hole drilling of steel ingot;

[0086] The steel ingot is upset in a closed upsetting cylinder, and the perforation is stopped after a certain formation, thereby preparing a blind hole blank 3.

[0087] Step 2: finishing of blind hole blank 3;

[0088] The blind hole blank 3 is air-cooled and then machined, the upper end of the outer circle is chamfered C50, and the inner hole is machined to have a metallic luster.

[0089] Step 3: Processing of the movable mandrel 1;

[0090] The material of the movable mandrel 1 is 5CrNiMo, the height of the working part of the mandrel is 20mm shorter than the height of the through hole of the blank, the slope is 9°, the diameter of the lower end of the working part 11 is 100mm larger than the diameter of the inner hole of the blank, the height of the conical slope 14 is 100mm, and the angle between the outer wall of the positioning part 11 and the working part 12 is 153°. The total length of the movable mandrel 1 is less than the blind hole blank 3, and is used to extrude the blind hole tube.

[0091] Step 4: heating the blind hole blank 3;

[0092] Blind hole blank 3 is coated with anti-oxidation paint before being loaded into the furnace for heating. The heating temperature of blind hole blank 3 is 1175℃, and the holding time is 6h.

[0093] Step 5: Apply mold lubricant to the movable core rod 1;

[0094] After the blind hole blank 3 is heated, there is no oxide scale on the surface, the movable core rod 1 is coated with mold lubricant, and the blind hole blank 3 is sprayed with glass powder for lubrication.

[0095] Step 6: The blind hole blank 3 passes through the movable mandrel 1;

[0096] After the blind hole blank 3 is sprayed with glass powder for lubrication, the blank 2 is clamped by a manipulator and inserted into the movable core rod 1 placed on the platform in advance. After the blind hole blank 3 is inserted, a certain force is applied downward to inlay the inner hole of the blind hole blank 3 and the positioning part of the movable core rod 1. The positioning part 11 is a large diameter end with an inclination at the lower end, and its function is to inlay and fix the core rod 1 and the blind hole blank 3 and to position it with the blind hole blank 3 during extrusion, so as to prevent the movable core rod 1 from moving relative to the undeformed metal product during the extrusion process.

[0097] Step 7: The blind hole blank 3 is placed in an extruder for extrusion.

[0098] A manipulator is used to clamp the blind hole blank 3 and the movable core rod 1 together and put them into an extruder for extrusion to form a blind hole tube.

[0099] Example 5: Large extruder extrude small diameter seamless pipe.

[0100] Process flow: closed upsetting and piercing of steel ingot - billet finishing - coating with anti-oxidation coating - billet heating - oxide scale removal - lubrication - insertion of movable mandrel - extrusion in extruder.

[0101] The method of extruding small-diameter seamless pipes and blind-hole pipes by a movable mandrel and a large extruder is as follows:

[0102] Step 1: The steel ingot is subjected to closed upsetting and perforation to form a hollow billet;

[0103] The electroslag ingot with a diameter of 500mm is upset in an upset tube with a diameter of 700mm, and then pierced. The inner hole diameter of the billet after piercing is 115mm. The electroslag ingot material is nickel-based alloy 6617.

[0104] Step 2: finishing of the hollow blank 2;

[0105] After air cooling, the blank is machined to machine the inner hole of the blank to 125 mm, the outer circle of the blank to 680 mm, and the upper end is chamfered to C50.

[0106] Step 3: Processing the movable mandrel 1;

[0107] The movable mandrel material is 5CrNiMo, the upper end diameter is 115mm, the slope is 8° (α=82°), the lower end diameter of the working part 12 is 120mm, and the outer wall angle between the positioning part 11 and the working part 12 is 150°. The total length of the movable mandrel 1 is slightly longer than the hollow billet 2, and is used to extrude seamless pipes.

[0108] Step 4: heating the blank;

[0109] The hollow billet 2 is coated with anti-oxidation paint before being loaded into the furnace for heating. The billet heating temperature is 1175℃ and the holding time is 6h.

[0110] Step 5: Lubrication of the blank;

[0111] After the hollow blank 2 is heated, the oxide scale on the surface is removed, the movable core rod 1 is coated with mold lubricant, and the hollow blank 2 is sprayed with glass powder for lubrication.

[0112] Step 6: The hollow blank 2 is inserted into the movable mandrel 1;

[0113] After the hollow blank 2 is sprayed with glass powder for lubrication, the manipulator is used to clamp the hollow blank 2, and the inner hole of the hollow blank 2 is inserted into the movable core rod 1 placed on the platform in advance. After the hollow blank 2 is inserted into the movable core rod 1, a certain force is applied downward to inlay the inner hole of the hollow blank 2 and the positioning part 11 of the movable core rod 1.

[0114] Step 7: The hollow billet 2 is placed in an extruder for extrusion;

[0115] The manipulator is used to clamp the hollow billet 2 and the movable core rod 1 together and put them into the extruder for extrusion, and the hollow billet 2 is extruded into a small-aperture seamless pipe. The specification is OD250*ID120mm small-aperture seamless pipe, and the material is nickel-based alloy 6617.

[0116] Example 6: Large extruder extruding small-diameter blind hole tube

[0117] Process flow: closed upsetting of steel ingot, drilling of blind holes - billet finishing - coating with anti-oxidation coating - billet heating - lubrication - insertion of movable mandrel - placing in extruder for extrusion.

[0118] Step 1: Closed upsetting and blind hole drilling of steel ingot;

[0119] The steel ingot is upset in a closed upsetting cylinder, and the perforation is stopped after a certain formation, thereby preparing a blind hole blank 3.

[0120] Step 2: finishing of blind hole blank 3;

[0121] The blind hole blank 3 is air-cooled and then machined, the upper end of the outer circle is chamfered C50, and the inner hole is machined to have a metallic luster.

[0122] Step 3: Processing of the movable mandrel 1;

[0123] The material of the movable mandrel 1 is 5CrNiMo, the height of the working part of the mandrel is 20mm shorter than the height of the through hole of the blank, the slope is 8°, the diameter of the lower end of the working part 11 is 100mm larger than the diameter of the inner hole of the blank, the height of the conical slope 14 is 100mm, and the angle between the outer wall of the positioning part 11 and the working part 12 is 150°. The total length of the movable mandrel 1 is less than the blind hole blank 3, and is used to extrude the blind hole tube.

[0124] Step 4: heating the blind hole blank 3;

[0125] Blind hole blank 3 is coated with anti-oxidation paint before being loaded into the furnace for heating. The heating temperature of blind hole blank 3 is 1175℃, and the holding time is 6h.

[0126] Step 5: Apply mold lubricant to the movable core rod 1;

[0127] After the blind hole blank 3 is heated, there is no oxide scale on the surface, the movable core rod 1 is coated with mold lubricant, and the blind hole blank 3 is sprayed with glass powder for lubrication.

[0128] Step 6: The blind hole blank 3 passes through the movable mandrel 1;

[0129] After the blind hole blank 3 is sprayed with glass powder for lubrication, the blank 2 is clamped by a manipulator and inserted into the movable core rod 1 placed on the platform in advance. After the blind hole blank 3 is inserted, a certain force is applied downward to inlay the inner hole of the blind hole blank 3 and the positioning part of the movable core rod 1. The positioning part 11 is a large diameter end with an inclination at the lower end, and its function is to inlay and fix the core rod 1 and the blind hole blank 3 and to position it with the blind hole blank 3 during extrusion, so as to prevent the movable core rod 1 from moving relative to the undeformed metal product during the extrusion process.

[0130] Step 7: The blind hole blank 3 is placed in an extruder for extrusion.

[0131] A manipulator is used to clamp the blind hole blank 3 and the movable core rod 1 together and put them into an extruder for extrusion to form a blind hole tube.

[0132] Example 7: Large extruder extrude small diameter seamless pipe.

[0133] Process flow: closed upsetting and piercing of steel ingot - billet finishing - coating with anti-oxidation coating - billet heating - oxide scale removal - lubrication - insertion of movable mandrel - extrusion in extruder.

[0134] The method of extruding small-diameter seamless pipes and blind-hole pipes by a movable mandrel and a large extruder is as follows:

[0135] Step 1: The steel ingot is subjected to closed upsetting and perforation to form a hollow billet;

[0136] The electroslag ingot with a diameter of 500mm is upset in an upset tube with a diameter of 700mm, and then pierced. The inner hole diameter of the billet after piercing is 115mm. The electroslag ingot material is nickel-based alloy 6617.

[0137] Step 2: finishing of the hollow blank 2;

[0138] After air cooling, the blank is machined to machine the inner hole of the blank to 125 mm, the outer circle of the blank to 680 mm, and the upper end is chamfered to C50.

[0139] Step 3: Processing the movable mandrel 1;

[0140] The movable mandrel material is 5CrNiMo, the upper end diameter is 115mm, the slope is 7° (α=83°), the lower end diameter of the working part 12 is 120mm, and the angle between the positioning part 11 and the outer wall of the working part 12 is 150°. The total length of the movable mandrel 1 is slightly longer than the hollow billet 2, and is used to extrude seamless pipes.

[0141] Step 4: heating the blank;

[0142] Before loading the hollow billet 2 into the furnace for heating, an anti-oxidation coating is applied. The billet heating temperature is 1175°C and the holding time is 6h.

[0143] Step 5: Lubrication of the blank;

[0144] After the hollow blank 2 is heated, the oxide scale on the surface is removed, the movable core rod 1 is coated with mold lubricant, and the hollow blank 2 is sprayed with glass powder for lubrication.

[0145] Step 6: The hollow blank 2 is inserted into the movable mandrel 1;

[0146] After the hollow blank 2 is sprayed with glass powder for lubrication, the manipulator is used to clamp the hollow blank 2, and the inner hole of the hollow blank 2 is inserted into the movable core rod 1 placed on the platform in advance. After the hollow blank 2 is inserted into the movable core rod 1, a certain force is applied downward to inlay the inner hole of the hollow blank 2 and the positioning part 11 of the movable core rod 1.

[0147] Step 7: The hollow billet 2 is placed in an extruder for extrusion;

[0148] The manipulator is used to clamp the hollow billet 2 and the movable core rod 1 together and put them into the extruder for extrusion, and the hollow billet 2 is extruded into a small-aperture seamless pipe. The specification is OD250*ID120mm small-aperture seamless pipe, and the material is nickel-based alloy 6617.

[0149] Example 8: Large extruder extruding small-diameter blind hole tube

[0150] Process flow: closed upsetting of steel ingot, drilling of blind holes - billet finishing - coating with anti-oxidation coating - billet heating - lubrication - insertion of movable mandrel - placing in extruder for extrusion.

[0151] Step 1: Closed upsetting and blind hole drilling of steel ingot;

[0152] The steel ingot is upset in a closed upsetting cylinder, and the perforation is stopped after a certain formation, thereby preparing a blind hole blank 3.

[0153] Step 2: finishing of blind hole blank 3;

[0154] The blind hole blank 3 is air-cooled and then machined, the upper end of the outer circle is chamfered C50, and the inner hole is machined to have a metallic luster.

[0155] Step 3: Processing of the movable mandrel 1;

[0156] The material of the movable mandrel 1 is 5CrNiMo, the height of the working part of the mandrel is 20mm shorter than the height of the through hole of the blank, the slope is 7°, the diameter of the lower end of the working part 11 is 100mm larger than the diameter of the inner hole of the blank, the height of the conical slope 14 is 100mm, and the angle between the outer wall of the positioning part 11 and the working part 12 is 150°. The total length of the movable mandrel 1 is less than the blind hole blank 3, and is used to extrude the blind hole tube.

[0157] Step 4: heating the blind hole blank 3;

[0158] Blind hole blank 3 is coated with anti-oxidation paint before being loaded into the furnace for heating. The heating temperature of blind hole blank 3 is 1175℃, and the holding time is 6h.

[0159] Step 5: Apply mold lubricant to the movable core rod 1;

[0160] After the blind hole blank 3 is heated, there is no oxide scale on the surface, the movable core rod 1 is coated with mold lubricant, and the blind hole blank 3 is sprayed with glass powder for lubrication.

[0161] Step 6: The blind hole blank 3 passes through the movable mandrel 1;

[0162] After the blind hole blank 3 is sprayed with glass powder for lubrication, the blank 2 is clamped by a manipulator and inserted into the movable core rod 1 placed on the platform in advance. After the blind hole blank 3 is inserted, a certain force is applied downward to inlay the inner hole of the blind hole blank 3 and the positioning part of the movable core rod 1. The positioning part 11 is a large diameter end with an inclination at the lower end, and its function is to inlay and fix the core rod 1 and the blind hole blank 3 and to position it with the blind hole blank 3 during extrusion, so as to prevent the movable core rod 1 from moving relative to the undeformed metal product during the extrusion process.

[0163] Step 7: The blind hole blank 3 is placed in an extruder for extrusion.

[0164] A manipulator is used to clamp the blind hole blank 3 and the movable core rod 1 together and put them into an extruder for extrusion to form a blind hole tube.

[0165] Example 9: Large extruder extrude small diameter seamless pipe.

[0166] Process flow: closed upsetting and piercing of steel ingot - billet finishing - coating with anti-oxidation coating - billet heating - oxide scale removal - lubrication - insertion of movable mandrel - extrusion in extruder.

[0167] The method of extruding small-diameter seamless pipes and blind-hole pipes by a movable mandrel and a large extruder is as follows:

[0168] Step 1: The steel ingot is subjected to closed upsetting and perforation to form a hollow billet;

[0169] The electroslag ingot with a diameter of 500mm is upset in an upset tube with a diameter of 700mm, and then pierced. The inner hole diameter of the billet after piercing is 115mm. The electroslag ingot material is nickel-based alloy 6617.

[0170] Step 2: finishing of the hollow blank 2;

[0171] After air cooling, the blank is machined to machine the inner hole of the blank to 125 mm, the outer circle of the blank to 680 mm, and the upper end is chamfered to C50.

[0172] Step 3: Processing the movable mandrel 1;

[0173] The movable mandrel material is 5CrNiMo, the upper end diameter is 115mm, the slope is 6° (α=84°), the lower end diameter of the working part 12 is 120mm, and the outer wall angle between the positioning part 11 and the working part 12 is 150°. The total length of the movable mandrel 1 is slightly longer than the hollow billet 2, and is used to extrude seamless pipes.

[0174] Step 4: heating the blank;

[0175] The hollow billet 2 is coated with anti-oxidation paint before being loaded into the furnace for heating. The billet heating temperature is 1175℃ and the holding time is 6h.

[0176] Step 5: Lubrication of the blank;

[0177] After the hollow blank 2 is heated, the oxide scale on the surface is removed, the movable core rod 1 is coated with mold lubricant, and the hollow blank 2 is sprayed with glass powder for lubrication.

[0178] Step 6: The hollow blank 2 is inserted into the movable mandrel 1;

[0179] After the hollow blank 2 is sprayed with glass powder for lubrication, the manipulator is used to clamp the hollow blank 2, and the inner hole of the hollow blank 2 is inserted into the movable core rod 1 placed on the platform in advance. After the hollow blank 2 is inserted into the movable core rod 1, a certain force is applied downward to inlay the inner hole of the hollow blank 2 and the positioning part 11 of the movable core rod 1.

[0180] Step 7: The hollow billet 2 is placed in an extruder for extrusion;

[0181] The manipulator is used to clamp the hollow billet 2 and the movable core rod 1 together and put them into the extruder for extrusion, and the hollow billet 2 is extruded into a small-aperture seamless pipe. The specification is OD250*ID120mm small-aperture seamless pipe, and the material is nickel-based alloy 6617.

[0182] Example 10: Large extruder extruding small-diameter blind hole tube

[0183] Process flow: closed upsetting of steel ingot, drilling of blind holes - billet finishing - coating with anti-oxidation coating - billet heating - lubrication - insertion of movable mandrel - placing in extruder for extrusion.

[0184] Step 1: Closed upsetting and blind hole drilling of steel ingot;

[0185] The steel ingot is upset in a closed upsetting cylinder, and the perforation is stopped after a certain formation, thereby preparing a blind hole blank 3.

[0186] Step 2: finishing of blind hole blank 3;

[0187] The blind hole blank 3 is air-cooled and then machined, the upper end of the outer circle is chamfered C50, and the inner hole is machined to have a metallic luster.

[0188] Step 3: Processing of the movable mandrel 1;

[0189] The material of the movable mandrel 1 is 5CrNiMo, the height of the working part of the mandrel is 20mm shorter than the height of the through hole of the blank, the slope is 6°, the diameter of the lower end of the working part 11 is 100mm larger than the diameter of the inner hole of the blank, the height of the conical slope 14 is 100mm, and the angle between the outer wall of the positioning part 11 and the working part 12 is 150°. The total length of the movable mandrel 1 is less than the blind hole blank 3, and is used to extrude the blind hole tube.

[0190] Step 4: heating the blind hole blank 3;

[0191] Blind hole blank 3 is coated with anti-oxidation paint before being loaded into the furnace for heating. The heating temperature of blind hole blank 3 is 1175℃, and the holding time is 6h.

[0192] Step 5: Apply mold lubricant to the movable core rod 1;

[0193] After the blind hole blank 3 is heated, there is no oxide scale on the surface, the movable core rod 1 is coated with mold lubricant, and the blind hole blank 3 is sprayed with glass powder for lubrication.

[0194] Step 6: The blind hole blank 3 passes through the movable mandrel 1;

[0195] After the blind hole blank 3 is sprayed with glass powder for lubrication, the blank 2 is clamped by a manipulator and inserted into the movable core rod 1 placed on the platform in advance. After the blind hole blank 3 is inserted, a certain force is applied downward to inlay the inner hole of the blind hole blank 3 and the positioning part of the movable core rod 1. The positioning part 11 is a large diameter end with an inclination at the lower end, and its function is to inlay and fix the core rod 1 and the blind hole blank 3 and to position it with the blind hole blank 3 during extrusion, so as to prevent the movable core rod 1 from moving relative to the undeformed metal product during the extrusion process.

[0196] Step 7: The blind hole blank 3 is placed in an extruder for extrusion.

[0197] A manipulator is used to clamp the blind hole blank 3 and the movable core rod 1 together and put them into an extruder for extrusion to form a blind hole tube.

[0198] Example 11: Large extruder extrude small diameter seamless pipe.

[0199] Process flow: closed upsetting and piercing of steel ingot - billet finishing - coating with anti-oxidation coating - billet heating - oxide scale removal - lubrication - insertion of movable mandrel - extrusion in extruder.

[0200] The method of extruding small-diameter seamless pipes and blind-hole pipes by a movable mandrel and a large extruder is as follows:

[0201] Step 1: The steel ingot is subjected to closed upsetting and perforation to form a hollow billet;

[0202] The electroslag ingot with a diameter of 500mm is upset in an upset tube with a diameter of 700mm, and then pierced. The inner hole diameter of the billet after piercing is 115mm. The electroslag ingot material is nickel-based alloy 6617.

[0203] Step 2: finishing of the hollow blank 2;

[0204] After air cooling, the blank is machined to machine the inner hole of the blank to 125 mm, the outer circle of the blank to 680 mm, and the upper end is chamfered to C50.

[0205] Step 3: Processing the movable mandrel 1;

[0206] The movable mandrel material is 5CrNiMo, the upper end diameter is 115mm, the slope is 5° (α=85°), the lower end diameter of the working part 12 is 120mm, and the outer wall angle between the positioning part 11 and the working part 12 is 150°. The total length of the movable mandrel 1 is slightly longer than the hollow billet 2, and is used to extrude seamless pipes.

[0207] Step 4: heating the blank;

[0208] Before loading the hollow billet 2 into the furnace for heating, an anti-oxidation coating is applied. The billet heating temperature is 1175°C and the holding time is 6h.

[0209] Step 5: Lubrication of the blank;

[0210] After the hollow blank 2 is heated, the oxide scale on the surface is removed, the movable core rod 1 is coated with mold lubricant, and the hollow blank 2 is sprayed with glass powder for lubrication.

[0211] Step 6: The hollow blank 2 is inserted into the movable mandrel 1;

[0212] After the hollow blank 2 is sprayed with glass powder for lubrication, the manipulator is used to clamp the hollow blank 2, and the inner hole of the hollow blank 2 is inserted into the movable core rod 1 placed on the platform in advance. After the hollow blank 2 is inserted into the movable core rod 1, a certain force is applied downward to inlay the inner hole of the hollow blank 2 and the positioning part 11 of the movable core rod 1.

[0213] Step 7: The hollow billet 2 is placed in an extruder for extrusion;

[0214] The manipulator is used to clamp the hollow billet 2 and the movable core rod 1 together and put them into the extruder for extrusion, and the hollow billet 2 is extruded into a small-aperture seamless pipe. The specification is OD250*ID120mm small-aperture seamless pipe, and the material is nickel-based alloy 6617.

[0215] Example 12: Large extruder extruding small-diameter blind hole tube

[0216] Process flow: closed upsetting of steel ingot, drilling of blind holes - billet finishing - coating with anti-oxidation coating - billet heating - lubrication - insertion of movable mandrel - placing in extruder for extrusion.

[0217] Step 1: Closed upsetting and blind hole drilling of steel ingot;

[0218] The steel ingot is upset in a closed upsetting cylinder, and the perforation is stopped after a certain formation, thereby preparing a blind hole blank 3.

[0219] Step 2: finishing of blind hole blank 3;

[0220] The blind hole blank 3 is air-cooled and then machined, the upper end of the outer circle is chamfered C50, and the inner hole is machined to have a metallic luster.

[0221] Step 3: Processing of the movable mandrel 1;

[0222] The material of the movable mandrel 1 is 5CrNiMo, the height of the working part of the mandrel is 20mm shorter than the height of the through hole of the blank, the slope is 5°, the diameter of the lower end of the working part 11 is 100mm larger than the diameter of the inner hole of the blank, the height of the conical slope 14 is 100mm, and the angle between the outer wall of the positioning part 11 and the working part 12 is 150°. The total length of the movable mandrel 1 is less than the blind hole blank 3, and is used to extrude the blind hole tube.

[0223] Step 4: heating the blind hole blank 3;

[0224] Blind hole blank 3 is coated with anti-oxidation paint before being loaded into the furnace for heating. The heating temperature of blind hole blank 3 is 1175℃, and the holding time is 6h.

[0225] Step 5: Apply mold lubricant to the movable core rod 1;

[0226] After the blind hole blank 3 is heated, there is no oxide scale on the surface, the movable core rod 1 is coated with mold lubricant, and the blind hole blank 3 is sprayed with glass powder for lubrication.

[0227] Step 6: The blind hole blank 3 passes through the movable mandrel 1;

[0228] After the blind hole blank 3 is sprayed with glass powder for lubrication, the blank 2 is clamped by a manipulator and inserted into the movable core rod 1 placed on the platform in advance. After the blind hole blank 3 is inserted, a certain force is applied downward to inlay the inner hole of the blind hole blank 3 and the positioning part of the movable core rod 1. The positioning part 11 is a large diameter end with an inclination at the lower end, and its function is to inlay and fix the core rod 1 and the blind hole blank 3 and to position it with the blind hole blank 3 during extrusion, so as to prevent the movable core rod 1 from moving relative to the undeformed metal product during the extrusion process.

[0229] Step 7: The blind hole blank 3 is placed in an extruder for extrusion.

[0230] A manipulator is used to clamp the blind hole blank 3 and the movable core rod 1 together and put them into an extruder for extrusion to form a blind hole tube.

[0231] Example 13: Large extruder extrude small diameter seamless pipe.

[0232] Process flow: closed upsetting and piercing of steel ingot - billet finishing - coating with anti-oxidation coating - billet heating - oxide scale removal - lubrication - insertion of movable mandrel - extrusion in extruder.

[0233] The method of extruding small-diameter seamless pipes and blind-hole pipes by a movable mandrel and a large extruder is as follows:

[0234] Step 1: The steel ingot is subjected to closed upsetting and perforation to form a hollow billet;

[0235] The electroslag ingot with a diameter of 500mm is upset in an upset tube with a diameter of 700mm, and then pierced. The inner hole diameter of the billet after piercing is 115mm. The electroslag ingot material is nickel-based alloy 6617.

[0236] Step 2: finishing of the hollow blank 2;

[0237] After air cooling, the blank is machined to machine the inner hole of the blank to 125 mm, the outer circle of the blank to 680 mm, and the upper end is chamfered to C50.

[0238] Step 3: Processing the movable mandrel 1;

[0239] The movable mandrel material is 5CrNiMo, the upper end diameter is 115mm, the slope is 4° (α=86°), the lower end diameter of the working part 12 is 120mm, and the outer wall angle between the positioning part 11 and the working part 12 is 150°. The total length of the movable mandrel 1 is slightly longer than the hollow billet 2, and is used to extrude seamless pipes.

[0240] Step 4: heating the blank;

[0241] The hollow billet 2 is coated with anti-oxidation paint before being loaded into the furnace for heating. The billet heating temperature is 1175℃ and the holding time is 6h.

[0242] Step 5: Lubrication of the blank;

[0243] After the hollow blank 2 is heated, the oxide scale on the surface is removed, the movable core rod 1 is coated with mold lubricant, and the hollow blank 2 is sprayed with glass powder for lubrication.

[0244] Step 6: The hollow blank 2 is inserted into the movable mandrel 1;

[0245] After the hollow blank 2 is sprayed with glass powder for lubrication, the manipulator is used to clamp the hollow blank 2, and the inner hole of the hollow blank 2 is inserted into the movable core rod 1 placed on the platform in advance. After the hollow blank 2 is inserted into the movable core rod 1, a certain force is applied downward to inlay the inner hole of the hollow blank 2 and the positioning part 11 of the movable core rod 1.

[0246] Step 7: The hollow billet 2 is placed in an extruder for extrusion;

[0247] The manipulator is used to clamp the hollow billet 2 and the movable core rod 1 together and put them into the extruder for extrusion, and the hollow billet 2 is extruded into a small-aperture seamless pipe. The specification is OD250*ID120mm small-aperture seamless pipe, and the material is nickel-based alloy 6617.

[0248] Example 14: Large extruder extruding small-diameter blind hole tube

[0249] Process flow: closed upsetting of steel ingot, drilling of blind holes - billet finishing - coating with anti-oxidation coating - billet heating - lubrication - insertion of movable mandrel - placing in extruder for extrusion.

[0250] Step 1: Closed upsetting and blind hole drilling of steel ingot;

[0251] The steel ingot is upset in a closed upsetting cylinder, and the perforation is stopped after a certain formation, thereby preparing a blind hole blank 3.

[0252] Step 2: finishing of blind hole blank 3;

[0253] The blind hole blank 3 is air-cooled and then machined, the upper end of the outer circle is chamfered C50, and the inner hole is machined to have a metallic luster.

[0254] Step 3: Processing of the movable mandrel 1;

[0255] The material of the movable mandrel 1 is 5CrNiMo, the height of the working part of the mandrel is 20mm shorter than the height of the through hole of the blank, the slope is 4°, the diameter of the lower end of the working part 11 is 100mm larger than the diameter of the inner hole of the blank, the height of the conical slope 14 is 90mm, and the angle between the outer wall of the positioning part 11 and the working part 12 is 150°. The total length of the movable mandrel 1 is less than the blind hole blank 3, and is used to extrude the blind hole tube.

[0256] Step 4: heating the blind hole blank 3;

[0257] Blind hole blank 3 is coated with anti-oxidation paint before being loaded into the furnace for heating. The heating temperature of blind hole blank 3 is 1175℃, and the holding time is 6h.

[0258] Step 5: Apply mold lubricant to the movable core rod 1;

[0259] After the blind hole blank 3 is heated, there is no oxide scale on the surface, the movable core rod 1 is coated with mold lubricant, and the blind hole blank 3 is sprayed with glass powder for lubrication.

[0260] Step 6: The blind hole blank 3 passes through the movable mandrel 1;

[0261] After the blind hole blank 3 is sprayed with glass powder for lubrication, the blank 2 is clamped by a manipulator and inserted into the movable core rod 1 placed on the platform in advance. After the blind hole blank 3 is inserted, a certain force is applied downward to inlay the inner hole of the blind hole blank 3 and the positioning part of the movable core rod 1. The positioning part 11 is a large diameter end with an inclination at the lower end, and its function is to inlay and fix the core rod 1 and the blind hole blank 3 and to position it with the blind hole blank 3 during extrusion, so as to prevent the movable core rod 1 from moving relative to the undeformed metal product during the extrusion process.

[0262] Step 7: The blind hole blank 3 is placed in an extruder for extrusion.

[0263] A manipulator is used to clamp the blind hole blank 3 and the movable core rod 1 together and put them into an extruder for extrusion to form a blind hole tube.

[0264] Example 15: Large extruder extrude small diameter seamless pipe.

[0265] Process flow: closed upsetting and piercing of steel ingot - billet finishing - coating with anti-oxidation coating - billet heating - oxide scale removal - lubrication - insertion of movable mandrel - extrusion in extruder.

[0266] The method of extruding small-diameter seamless pipes and blind-hole pipes by a movable mandrel and a large extruder is as follows:

[0267] Step 1: The steel ingot is subjected to closed upsetting and perforation to form a hollow billet;

[0268] The electroslag ingot with a diameter of 500mm is upset in an upset tube with a diameter of 700mm, and then pierced. The inner hole diameter of the billet after piercing is 115mm. The electroslag ingot material is nickel-based alloy 6617.

[0269] Step 2: finishing of the hollow blank 2;

[0270] After air cooling, the blank is machined to machine the inner hole of the blank to 125 mm, the outer circle of the blank to 680 mm, and the upper end is chamfered to C50.

[0271] Step 3: Processing the movable mandrel 1;

[0272] The movable mandrel material is 5CrNiMo, the upper end diameter is 115mm, the slope is 3° (α=87°), the lower end diameter of the working part 12 is 120mm, and the outer wall angle between the positioning part 11 and the working part 12 is 150°. The total length of the movable mandrel 1 is slightly longer than the hollow billet 2, and is used to extrude seamless pipes.

[0273] Step 4: heating the blank;

[0274] The hollow billet 2 is coated with anti-oxidation paint before being loaded into the furnace for heating. The billet heating temperature is 1175℃ and the holding time is 6h.

[0275] Step 5: Lubrication of the blank;

[0276] After the hollow blank 2 is heated, the oxide scale on the surface is removed, the movable core rod 1 is coated with mold lubricant, and the hollow blank 2 is sprayed with glass powder for lubrication.

[0277] Step 6: The hollow blank 2 is inserted into the movable mandrel 1;

[0278] After the hollow blank 2 is sprayed with glass powder for lubrication, the manipulator is used to clamp the hollow blank 2, and the inner hole of the hollow blank 2 is inserted into the movable core rod 1 placed on the platform in advance. After the hollow blank 2 is inserted into the movable core rod 1, a certain force is applied downward to inlay the inner hole of the hollow blank 2 and the positioning part 11 of the movable core rod 1.

[0279] Step 7: The hollow billet 2 is placed in an extruder for extrusion;

[0280] The manipulator is used to clamp the hollow billet 2 and the movable core rod 1 together and put them into the extruder for extrusion, and the hollow billet 2 is extruded into a small-aperture seamless pipe. The specification is OD250*ID120mm small-aperture seamless pipe, and the material is nickel-based alloy 6617.

[0281] Example 16: Large extruder extruding small-diameter blind hole tube

[0282] Process flow: closed upsetting of steel ingot, drilling of blind holes - billet finishing - coating with anti-oxidation coating - billet heating - lubrication - insertion of movable mandrel - placing in extruder for extrusion.

[0283] Step 1: Closed upsetting and blind hole drilling of steel ingot;

[0284] The steel ingot is upset in a closed upsetting cylinder, and the perforation is stopped after a certain formation, thereby preparing a blind hole blank 3.

[0285] Step 2: finishing of blind hole blank 3;

[0286] The blind hole blank 3 is air-cooled and then machined, the upper end of the outer circle is chamfered C50, and the inner hole is machined to have a metallic luster.

[0287] Step 3: Processing of the movable mandrel 1;

[0288] The material of the movable mandrel 1 is 5CrNiMo, the height of the working part of the mandrel is 20mm shorter than the height of the through hole of the blank, the slope is 3°, the diameter of the lower end of the working part 11 is 100mm larger than the diameter of the inner hole of the blank, the height of the conical slope 14 is 90mm, and the angle between the outer wall of the positioning part 11 and the working part 12 is 150°. The total length of the movable mandrel 1 is less than the blind hole blank 3, and is used to extrude the blind hole tube.

[0289] Step 4: heating the blind hole blank 3;

[0290] Blind hole blank 3 is coated with anti-oxidation paint before being loaded into the furnace for heating. The heating temperature of blind hole blank 3 is 1175℃, and the holding time is 6h.

[0291] Step 5: Apply mold lubricant to the movable core rod 1;

[0292] After the blind hole blank 3 is heated, there is no oxide scale on the surface, the movable core rod 1 is coated with mold lubricant, and the blind hole blank 3 is sprayed with glass powder for lubrication.

[0293] Step 6: The blind hole blank 3 passes through the movable mandrel 1;

[0294] After the blind hole blank 3 is sprayed with glass powder for lubrication, the blank 2 is clamped by a manipulator and inserted into the movable core rod 1 placed on the platform in advance. After the blind hole blank 3 is inserted, a certain force is applied downward to inlay the inner hole of the blind hole blank 3 and the positioning part of the movable core rod 1. The positioning part 11 is a large diameter end with an inclination at the lower end, and its function is to inlay and fix the core rod 1 and the blind hole blank 3 and to position it with the blind hole blank 3 during extrusion, so as to prevent the movable core rod 1 from moving relative to the undeformed metal product during the extrusion process.

[0295] Step 7: The blind hole blank 3 is placed in an extruder for extrusion.

[0296] A manipulator is used to clamp the blind hole blank 3 and the movable core rod 1 together and put them into an extruder for extrusion to form a blind hole tube.

[0297] Example 17: Large extruder extrude small diameter seamless pipe.

[0298] Process flow: closed upsetting and piercing of steel ingot - billet finishing - coating with anti-oxidation coating - billet heating - oxide scale removal - lubrication - insertion of movable mandrel - extrusion in extruder.

[0299] The method of extruding small-diameter seamless pipes and blind-hole pipes by a movable mandrel and a large extruder is as follows:

[0300] Step 1: The steel ingot is subjected to closed upsetting and perforation to form a hollow billet;

[0301] The electroslag ingot with a diameter of 500mm is upset in an upset tube with a diameter of 700mm, and then pierced. The inner hole diameter of the billet after piercing is 115mm. The electroslag ingot material is nickel-based alloy 6617.

[0302] Step 2: finishing of the hollow blank 2;

[0303] After air cooling, the blank is machined to machine the inner hole of the blank to 125 mm, the outer circle of the blank to 680 mm, and the upper end is chamfered to C50.

[0304] Step 3: Processing the movable mandrel 1;

[0305] The movable mandrel material is 5CrNiMo, the upper end diameter is 115mm, the slope is 2° (α=88°), the lower end diameter of the working part 12 is 120mm, and the outer wall angle between the positioning part 11 and the working part 12 is 150°. The total length of the movable mandrel 1 is slightly longer than the hollow billet 2, and is used to extrude seamless pipes.

[0306] Step 4: heating the blank;

[0307] Before loading the hollow billet 2 into the furnace for heating, an anti-oxidation coating is applied. The billet heating temperature is 1175°C and the holding time is 6h.

[0308] Step 5: Lubrication of the blank;

[0309] After the hollow blank 2 is heated, the oxide scale on the surface is removed, the movable core rod 1 is coated with mold lubricant, and the hollow blank 2 is sprayed with glass powder for lubrication.

[0310] Step 6: The hollow blank 2 is inserted into the movable mandrel 1;

[0311] After the hollow blank 2 is sprayed with glass powder for lubrication, the manipulator is used to clamp the hollow blank 2, and the inner hole of the hollow blank 2 is inserted into the movable core rod 1 placed on the platform in advance. After the hollow blank 2 is inserted into the movable core rod 1, a certain force is applied downward to inlay the inner hole of the hollow blank 2 and the positioning part 11 of the movable core rod 1.

[0312] Step 7: The hollow billet 2 is placed in an extruder for extrusion;

[0313] The manipulator is used to clamp the hollow billet 2 and the movable core rod 1 together and put them into the extruder for extrusion, and the hollow billet 2 is extruded into a small-aperture seamless pipe. The specification is OD250*ID120mm small-aperture seamless pipe, and the material is nickel-based alloy 6617.

[0314] Example 18: Large extruder extruding small-diameter blind hole tube

[0315] Process flow: closed upsetting of steel ingot, drilling of blind holes - billet finishing - coating with anti-oxidation coating - billet heating - lubrication - insertion of movable mandrel - placing in extruder for extrusion.

[0316] Step 1: Closed upsetting and blind hole drilling of steel ingot;

[0317] The steel ingot is upset in a closed upsetting cylinder, and the perforation is stopped after a certain formation, thereby preparing a blind hole blank 3.

[0318] Step 2: finishing of blind hole blank 3;

[0319] The blind hole blank 3 is air-cooled and then machined, the upper end of the outer circle is chamfered C50, and the inner hole is machined to have a metallic luster.

[0320] Step 3: Processing of the movable mandrel 1;

[0321] The material of the movable mandrel 1 is 5CrNiMo, the height of the working part of the mandrel is 20mm shorter than the height of the through hole of the blank, the slope is 2°, the diameter of the lower end of the working part 11 is 100mm larger than the diameter of the inner hole of the blank, the height of the large bevel is 100mm, and the angle between the outer wall surface of the positioning part 11 and the working part 12 is 150°. The total length of the movable mandrel 1 is less than the blind hole blank 3, and it is used to extrude the blind hole tube.

[0322] Step 4: heating the blind hole blank 3;

[0323] Blind hole blank 3 is coated with anti-oxidation paint before being loaded into the furnace for heating. The heating temperature of blind hole blank 3 is 1175℃, and the holding time is 6h.

[0324] Step 5: Apply mold lubricant to the movable core rod 1;

[0325] After the blind hole blank 3 is heated, there is no oxide scale on the surface, the movable core rod 1 is coated with mold lubricant, and the blind hole blank 3 is sprayed with glass powder for lubrication.

[0326] Step 6: The blind hole blank 3 passes through the movable mandrel 1;

[0327] After the blind hole blank 3 is sprayed with glass powder for lubrication, the blank 2 is clamped by a manipulator and inserted into the movable core rod 1 placed on the platform in advance. After the blind hole blank 3 is inserted, a certain force is applied downward to inlay the inner hole of the blind hole blank 3 and the positioning part of the movable core rod 1. The positioning part 11 is a large diameter end with an inclination at the lower end, and its function is to inlay and fix the core rod 1 and the blind hole blank 3 and to position it with the blind hole blank 3 during extrusion, so as to prevent the movable core rod 1 from moving relative to the undeformed metal product during the extrusion process.

[0328] Step 7: The blind hole blank 3 is placed in an extruder for extrusion.

[0329] A manipulator is used to clamp the blind hole blank 3 and the movable core rod 1 together and put them into an extruder for extrusion to form a blind hole tube.

[0330] The terms used in the present invention are illustrative and exemplary, rather than restrictive. Since the present invention can be implemented in various forms without departing from the spirit or essence of the technical solution, it should be understood that the above embodiments are not limited to any of the aforementioned details, but should be widely interpreted within the spirit and scope defined by the attached claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the attached claims.

Claims

1. A movable mandrel, characterized in that: include: The positioning part, the working part and the core rod body are respectively located at the lower end and the upper end of the core rod body. The rear end of the positioning part is provided with a conical inclined surface, and the inclination of the conical inclined surface is ≤10°.

2. The movable mandrel according to claim 1, characterized in that: The included angle between the tapered inclined surface and the end surface of the positioning portion is 80-90°.

3. The movable mandrel according to claim 1, characterized in that: The length of the tapered slope is 90-110 mm.

4. The movable mandrel according to claim 1, characterized in that: The included angle between the positioning portion and the outer wall surface of the working portion is 140-160°.

5. The movable mandrel according to claim 1, characterized in that: The end of the working portion is provided with a rounded corner or a chamfered corner.

6. A method for extruding a small-diameter seamless pipe / blind hole pipe using a large extruder, characterized in that: The method of extruding using the movable mandrel as claimed in any one of claims 1 to 5 comprises: The steel ingot is formed into a hollow billet / blind hole tube billet through closed upsetting and perforation. After the hollow billet is finished and heated, the mold lubricant is applied to the movable mandrel, and the hollow billet is sprayed with glass powder for lubrication. Use a manipulator to clamp the hollow billet, insert the inner hole of the hollow billet / blind hole tube billet into the movable mandrel, apply downward pressure to the movable mandrel, and inlay the inner hole of the hollow billet and the positioning part of the movable mandrel together; A manipulator is used to put the hollow billet / blind hole tube billet and the movable core rod into the extruder for extrusion, and the hollow billet is extruded into a small-diameter seamless tube / blind hole tube.

7. The method for extruding a small-diameter seamless pipe / blind hole pipe by a large extruder as claimed in claim 6, characterized in that: The material of the hollow billet / blind hole tube billet is a nickel-based alloy, and the material of the movable core rod is 5CrNiMo.

8. The method for extruding a small-diameter seamless pipe / blind hole pipe by a large extruder as claimed in claim 6, characterized in that: The electroslag ingot is upset in the upsetting tube and then perforated to form a hollow billet / blind hole tube billet.

9. The method for extruding a small-diameter seamless pipe / blind hole pipe by a large extruder as claimed in claim 6, characterized in that: The hollow billet / blind hole tube billet is machined after air cooling, including: machining the inner hole of the hollow billet, the outer circle of the hollow billet, and the chamfering of the upper end of the hollow billet.

10. The method for extruding a small-diameter seamless pipe / blind hole pipe by a large extruder as claimed in claim 6, characterized in that: When the total length of the movable mandrel is slightly longer than the hollow billet, it is used to extrude seamless pipes; when the total length of the movable mandrel is shorter than the blind hole billet, it is used to extrude blind hole pipes.

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