A pipe manufacturing method for reducing surface defects of a pure nickel cold-rolled seamless pipe

Abstract

The application discloses a pipe manufacturing method for reducing surface defects of pure nickel cold-rolled seamless pipes, and raw materials with a specification of Ф80*7.5mm are rolled into finished products with a specification of Ф48.3*1.65mm by using two-roller cold rolling machines, two-roller cold rolling machines and three-roller cold rolling machines in sequence. The application effectively avoids the generation of wave-shaped defects by optimizing the feeding amount and wall thickness reduction amount during cold rolling pipe manufacturing, effectively reduces the pitting (pits) in the raw pipe rolling by strengthening the inspection and grinding of the surface of the raw pipe and increasing the on-line checking frequency of the rolling groove, and effectively reduces the rubbing damage of the inner surface by optimizing the deformation tools such as the mandrel and the sliding groove and reasonably adjusting the feeding amount.

Description

TECHNICAL FIELD

[0001] The present application relates to the cold rolling pipe-making technology of seamless steel pipe in metallurgical and mechanical industry, more particularly to a pipe-making method for reducing surface defects of pure nickel cold-rolled seamless pipe, which is particularly suitable for cold-rolled pipe-making production of Nickel201 pure nickel seamless pipe with a finished product outer diameter of 10mm-50mm. BACKGROUND

[0002] Seamless steel pipe is a common metallurgical steel product. Metal nickel has excellent high-temperature corrosion resistance, high toughness, ductility and forgeability, good mechanical, physical and process properties, and special corrosion resistance and oxidation resistance, especially excellent resistance to strong alkali corrosion. Therefore, it is often used in the production of alkali industry, chlor-alkali chemical industry and organic chlorides, food processing industry, high-temperature halogen and salt corrosion environment, electronic instrument parts, water treatment and various strong alkali resistant equipment fields. At present, the nickel pipe made of metal nickel is all pure nickel seamless pipe, and there is no welded pipe in existence. The pipe-making standards for pure nickel seamless pipe are Chinese national standard GB / T2882-2005 and American national standard ASTM B163, ASTM B165. However, due to the scarcity of nickel metal resources on earth, the production process of pure nickel seamless pipe is complex, the technical difficulty is high, and the production cost is high, thereby limiting the production and application of pure nickel seamless pipe.

[0003] Nickel201 pure nickel seamless pipe is a new type of seamless steel pipe developed and produced internationally in recent years, which can be used for caustic soda production equipment in petroleum and chemical industry. The finished product specifications are Φ13.7x1.2x5000mm, Φ32x4.5x4000mm, and Φ48.3x1.6x1400mm, which execute American standard ASTM B163. According to the process flow of pipe blank preparation (round steel peeling, end face processing, centering hole, inspection) → rough pipe preparation (pipe blank heating, high-temperature piercing, rough pipe inspection) → rough pipe pickling → rough pipe finishing (sizing pipe cutting, surface grinding) → cold-rolled pipe-making → pickling → intermediate inspection → head beating → lubrication → cold-drawn pipe-making → finishing (straightening) → pickling → sizing → finished product inspection, etc. The process can select cold-rolled pipe-making or cold-rolled + cold-drawn pipe-making according to the specifications of finished pipe. The pure nickel seamless steel pipe after pipe-making processing can meet the technical requirements of users.

[0004] From the above process, the cold rolling pipe process is the key process to determine the quality and efficiency of pure nickel seamless pipe production. The cold rolling pipe process of seamless pipe is to use periodic cold rolling pipe machine to roll the blank pipe under normal temperature working condition. The periodic cold rolling pipe machine is divided into two-roller periodic and multi-roller periodic according to the number of rollers, and the most commonly used is three-roller periodic. The characteristics of cold rolling pipe of seamless steel pipe are: strong wall reduction capacity, large pass surface reduction rate, good machining precision, high finished product rate, less metal loss, high yield, but slow production speed, inconvenient specification change, high cost of tools and intermediate treatment, and the structure of periodic cold rolling pipe machine is complex, the equipment investment cost is large, the daily use and maintenance cost is high, and it is mainly used for the production of stainless steel, alloy steel and other seamless steel pipes.

[0005] The two-roller periodic cold rolling pipe machine is composed of rolling mechanism, feeding and rotating mechanism, transmission mechanism, core rod chuck mechanism, bed body supporting mechanism, material feeding and blanking mechanism, hydraulic system, process lubrication system, electrical automation control system, pneumatic system and auxiliary mechanism. The function of the rolling mechanism is to deform the blank pipe of seamless steel pipe under normal temperature working condition through the deformation tool composed of a top head and a pass. Its rolling working principle is: the depth of the half-circular groove in the middle of the single pair of passes changes continuously and uniformly from deep to shallow on the entire pass circumference. During rolling, the passes are used in pairs according to the rolling specification, that is, the circular hole composed of two passes changes from large to small, thereby realizing the reduction of pipe diameter, wall thickness and elongation of pipe material. When the roller rotates one revolution, the pass installed in the middle of the roller completes a change cycle synchronously, and the blank pipe completes a feeding amount and a synchronous rotation amount in one change cycle, and then does reverse rolling motion under the driving of the roller……In this way, the pipe rolling(reduction, wall thickness reduction and elongation) processing is completed week after week. When the pass contacts the blank pipe during rolling, the diameter of the contacted section is gradually reduced and the wall thickness is thinned once; when the roller rotates one revolution, the blank pipe at the section realizes the functions of forging, finishing, sizing and the like in one go. The rolling speed is fast, the rolling force is large, the deformation amount of pass is large, the processing pass is less, the production cycle is short, so it is suitable for cold rolling production of seamless steel pipe with large deformation resistance, large wall and diameter reduction.

[0006] Three-roll periodic cold rolling pipe machine is composed of rolling mechanism, feeding rotary mechanism, transmission mechanism, mandrel chuck mechanism, bed body supporting mechanism, material feeding and blanking mechanism and hydraulic system, process lubrication system, electrical automation control system, pneumatic system and auxiliary mechanism, etc. Compared with two-roll periodic cold rolling pipe machine, its rolling mechanism is completely different. The rolling groove composed of three pairs of two-end trunnion and middle equal-diameter rolling groove replaces the hole type, and the deformation tool composed of the top head carries out cold deformation processing of the blank pipe under normal temperature working condition. Its rolling working principle is that three rolling grooves are symmetrically arranged at the vertices of the equilateral triangle with the rolling center line as the center, the rolling groove axis and the rolling center line are inclined at two different angles, one is the feeding angle, and the other is the rolling angle. The blank pipe realizes the purposes of reducing diameter, reducing wall and extending in the closed circular ring composed of three rolling grooves and a top head. The deformation amount of three-roll periodic cold rolling pipe reducing diameter is smaller than that of two-roll periodic cold rolling pipe, and the deformation amount of reducing wall is relatively larger, so it can improve the inner wall surface quality of seamless steel pipe, and belongs to finishing deformation processing. The rolling pipe has high precision and good surface quality, and is suitable for finishing rolling production of seamless steel pipe with high inner wall surface quality requirement, and is also commonly used for cold rolling production of seamless steel pipe with thin wall thickness.

[0007] According to the finished product specifications of Nickel201 pure nickel seamless pipe Φ13.7×1.2×5000mm, Φ32×4.5×4000mm and Φ48.3×1.6×1400mm, LG-80 two-roll periodic cold rolling pipe machine, LG-55 two-roll periodic cold rolling pipe machine or LG-60H two-roll periodic cold rolling pipe machine, LD-60 three-roll periodic cold rolling pipe machine and KPW-50VRM high-speed cold rolling pipe machine can be selected to form a continuous rolling production line to carry out cold rolling pipe production of Nickel201 pure nickel seamless pipe, i.e.

[0008] Table 1: Cold rolling pipe process flow table of Nickel201 pure nickel seamless pipe

[0009]

[0010] According to different finished product specifications, LG-80→LG-55→KPW-50 can be used to roll the blank specifications Ф80×7.5mm into semi-finished products Ф38×5.0mm and Ф25×1.5mm, and LG-80→LG-60H→LD-60 can be used to roll the blank specifications Ф80×7.5mm into finished product Ф48.3×1.65mm. According to the actual finished product specifications, the finished product or semi-finished product is processed. The above-mentioned cold rolling pipe process is relatively mature and can meet the cold rolling pipe production of Nickel201 pure nickel seamless pipe, but there are still some problems, i.e.

[0011] 1) The surface of the pipe has a dot (pit) when the pipe is rolled: when the pipe is rolled on the LG-80 two-roll periodic cold rolling pipe machine, the defect is clearly visible after pickling, and if it is not treated in time, it will cause the defect to deepen and worsen during subsequent pipe rolling, forming intermittent or continuous cracks and causing quality accidents. The main reason is that the surface defects of the round steel after high-temperature perforation have not been completely eliminated or the defect grinding is not thorough before entering the subsequent rolling process, and the point-like corrosion in the rolling groove is not treated in time, in addition, the feeding amount during pipe rolling is closely related.

[0012] 2) The inner surface of the pure nickel pipe is scratched: it mainly occurs during the rolling of the LD-60 three-roll periodic cold rolling pipe machine, and the main reason is that the metal being rolled is adhered to the mandrel during rolling, which is closely related to the deformation and feeding amount during rolling. In addition, factors such as the inner wall of the blank pipe being not clean, the pipe being bent, the mandrel being bent, and the chamfer of the end of the mandrel being too small can also cause damage to the inner wall of the pure nickel seamless pipe.

[0013] 3) The pure nickel pipe appears wavy: the so-called wavy is that the outer circumference has a ring-shaped uneven phenomenon along the length direction, like a continuous or intermittent deformation, which mainly occurs in the KPW-50 VRM high-speed cold rolling pipe machine. The main reason is that the feeding amount during rolling is large and the wall thickness reduction amount is large, in addition, the blank pipe feeding is unstable, the support plate reverse slope is not enough, the hole type sizing section is worn and becomes conical after failure, and the opening part of the hole type rolling groove is poorly processed and the feeding rotation motion of the equipment output is not matched.

[0014] In summary, due to the metal characteristics of nickel and the related factors in the cold rolling process of pure nickel seamless pipe, the surface defect damage of the finished product specifications Φ13.7x1.2x5000mm, Φ32x4.5x4000mm, Φ48.3x1.6x1400mm Nickel 201 pure nickel seamless pipe for caustic soda device exists in the cold rolling pipe, which affects the production quality and efficiency of the product to some extent, and has an adverse effect on the production of the enterprise. According to the technical requirements of Nickel 201 pure nickel seamless pipe, relying on the advantages of long-term accumulation of technical reserves and advanced equipment, the existing cold rolling pipe production process is improved, the surface quality of pure nickel seamless steel pipe is further improved, the surface defect is reduced, the production technical requirements are met, and the core market competitiveness of the enterprise is promoted. SUMMARY

[0015] In view of the above-mentioned defects in the prior art, the purpose of the present application is to provide a pipe manufacturing method for reducing surface defects of pure nickel cold-rolled seamless pipes, which effectively avoids the generation of wave-shaped defects by optimizing the feed amount and wall thickness reduction amount during cold rolling pipe manufacturing; effectively reduces the pitting (pits) in the rough pipe rolling by strengthening the inspection and grinding of the rough pipe surface and increasing the on-line inspection frequency of the rolling groove; and effectively reduces the rubbing damage on the inner surface by optimizing the deformation tools such as the mandrel and the sliding groove and reasonably adjusting the feed amount.

[0016] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0017] The present application provides, in a first aspect, a pipe manufacturing method for reducing surface defects of pure nickel cold-rolled seamless pipes:

[0018] A two-roll cold rolling mill, a two-roll cold rolling mill, and a three-roll cold rolling mill are sequentially used to roll the blank with a specification of Ф80x7.5mm into a finished product blank with a specification of Ф48.3x1.65mm.

[0019] Preferably, the pipe manufacturing method further comprises the following passes:

[0020] Pass 0: a two-roll cold rolling mill is used for rolling to roll the blank with a specification of Ф80x7.5mm into a blank with a specification of Ф57x4.5mm;

[0021] Pass 1: a two-roll cold rolling mill is used for rolling to roll the blank with a specification of Ф57x4.5mm into a blank with a specification of Ф53x3.0mm;

[0022] Pass 2: a three-roll cold rolling mill is used for rolling to roll the blank with a specification of Ф53x3.0mm into a finished product blank with a specification of Ф48.3x1.65mm.

[0023] Preferably, in the pass 0, the rolling speed of the two-roll cold rolling mill is 60-70 times / minute, the pass gap is 0.3-1.0mm, the rolling gap is 1.5-3.8mm, the feed amount is 3-6mm, the rotation angle is 41.5-42.2 degrees, the lubrication mode adopts on-line large-flow thin oil lubrication, blank re-inspection is added before rolling, and the pass is re-inspected after rolling three pipes;

[0024] In the pass 1, the rolling speed of the two-roll cold rolling mill is 68-80 times / minute, the pass gap is 0.2-1.0mm, the rolling gap is 1.5-3.2mm, the feed amount is 3-6mm, the rotation angle is 41.5-42.2 degrees, and the lubrication mode adopts on-line large-flow thin oil lubrication;

[0025] In the pass 2, the rolling speed of the three-roller cold rolling machine is 55-65 times / minute, the rolling gap is 0.5-2.0 mm, the feed amount is 3.5-4.5 mm, the rotation angle is 47.5-48.5 degrees, the lubrication mode adopts on-line large-flow thin oil lubrication, and the deformation surfaces of the sliding groove, the mandrel and the roller are smoothly transitioned by chamfering.

[0026] The second aspect of the present application provides a pipe manufacturing method for reducing surface defects of a pure nickel cold-rolled seamless pipe:

[0027] The blank with the specification of Φ80*7.5 mm is sequentially rolled into a semi-finished product with the specification of Φ38*5.0 mm by the two-roller cold rolling machine and the two-roller cold rolling machine, and then rolled into a finished product with the specification of Φ32*4.5 mm.

[0028] Preferably, the pipe manufacturing method further comprises the following passes:

[0029] Pass 0: the two-roller cold rolling machine is used for rolling, and the blank with the specification of Φ80*7.5 mm is rolled into a semi-finished product with the specification of Φ57*5.5 mm;

[0030] Pass 1: the two-roller cold rolling machine is used for rolling, and the semi-finished product with the specification of Φ57*5.5 mm is rolled into a finished product with the specification of Φ38*5.0 mm.

[0031] Preferably, in the pass 0, the rolling speed of the two-roller cold rolling machine is 60-70 times / minute, the pass gap is 0.3-1.0 mm, the rolling gap is 1.5-3.8 mm, the feed amount is 3.5-6 mm, the rotation angle is 41.5-42.2 degrees, the lubrication mode adopts on-line large-flow thin oil lubrication, the blank re-inspection is added before rolling, and the pass is re-inspected after rolling three pipes;

[0032] In the pass 1, the rolling speed of the two-roller cold rolling machine is 68-80 times / minute, the pass gap is 0.2-1.0 mm, the rolling gap is 1.5-3.2 mm, the feed amount is 4-6 mm, the rotation angle is 41.5-42.2 degrees, and the lubrication mode adopts on-line large-flow thin oil lubrication.

[0033] The third aspect of the present application provides a pipe manufacturing method for reducing surface defects of a pure nickel cold-rolled seamless pipe:

[0034] The blank with the specification of Φ80*7.5 mm is sequentially rolled into a semi-finished product with the specification of Φ25*1.5 mm by the two-roller cold rolling machine, the two-roller cold rolling machine and the two-roller high-speed rolling machine, and then rolled into a finished product with the specification of Φ13.7*1.2 mm.

[0035] Preferably, the pipe manufacturing method further comprises the following passes:

[0036] Pass 0: using two-roller cold rolling mill, the Ф80*7.5mm blank is rolled into Ф57*4.5mm semi-product;

[0037] Pass 1: using two-roller cold rolling mill, the Ф57*4.5mm semi-product is rolled into Ф38*3.0mm semi-product;

[0038] Pass 2: using two-roller high-speed rolling mill, the Ф38*3.0mm semi-product is rolled into Ф13.7*1.2mm finished product.

[0039] Preferably, in the pass 0, the rolling speed of the two-roller cold rolling mill is 60-70 times / minute, the pass gap is 0.3-1.0mm, the rolling gap is 1.5-3.8mm, the feed amount is 3-6mm, the rotation angle is 41.5-42.2 degrees, the lubrication mode adopts on-line large-flow thin oil lubrication, the blank re-inspection is added before rolling, and the pass is re-inspected after rolling three pipes;

[0040] In the pass 1, the rolling speed of the two-roller cold rolling mill is 68-80 times / minute, the pass gap is 0.2-1.0mm, the rolling gap is 1.5-3.2mm, the feed amount is 3-6mm, the rotation angle is 41.5-42.2 degrees, and the lubrication mode adopts on-line large-flow thin oil lubrication;

[0041] In the pass 2, the rolling speed of the two-roller high-speed rolling mill is 110-140 times / minute, the pass gap is 0.15-0.5mm, the rolling gap is 1.2-2.8mm, the feed amount is 3.5-5mm, the rotation angle is 31.0 degrees at the inlet end and 26.0 degrees at the outlet end, and the lubrication mode adopts on-line large-flow thin oil external lubrication combined with special rolling lubricant core rod tail high-pressure input internal lubrication.

[0042] The pipe manufacturing method for reducing the surface defects of pure nickel cold-rolled seamless pipes has the following beneficial effects:

[0043] 1) The process design is reasonable, the process organization is smooth, safe, reliable, practical, efficient, meets the technical requirements of Nickel 201 pure nickel seamless pipe cold rolling pipe manufacturing, and promotes the core competitiveness of enterprises;

[0044] 2) According to the steel type characteristics and technical requirements of three kinds of finished product specifications of Nickel 201 pure nickel seamless pipe, the cold rolling pipe manufacturing process is organized and implemented, the surface defect loss of pure nickel pipe is reduced, the surface rolling quality is continuously and stably improved, and the energy saving, emission reduction and consumption reduction effects are remarkable;

[0045] 3) LG-80 two-roller cold rolling machine → LG-60H two-roller cold rolling machine → LD-60 three-roller cold rolling machine, the blank size Ф80*7.5mm is rolled into Ф48.3*1.65mm finished product, the characteristics of two-roller and three-roller cold rolling machines are fully utilized, and the quality and efficiency of finished product rolling are ensured;

[0046] 4) LG-80 two-roller cold rolling machine → LG-55 two-roller cold rolling machine, the blank size Ф80*7.5mm is rolled into Ф38*5.0mm semi-finished product, and Ф32*4.5mm finished product is provided with blank, short process reduces the production cost of rolled pipe, and the wall thickness precision is controlled to create conditions for subsequent cold drawing processing;

[0047] 5) LG-80 two-roller cold rolling machine → LG-55 two-roller cold rolling machine → KPW-50 two-roller high-speed rolling machine, the blank size Ф80*7.5mm is rolled into Ф25*1.5mm semi-finished product, and Ф13.7*1.2mm finished product is provided with blank, the characteristics of high-speed rolling machine, such as high speed and high capacity, are fully utilized, and production organization on site is facilitated;

[0048] 6) The frequency of on-line inspection of the groove rolling groove is increased through strengthened inspection and grinding of the surface of the rough pipe, and the generation of pitting curve in the rough pipe rolling is effectively reduced;

[0049] 7) The generation of wave-shaped defects is effectively avoided by optimizing the feed amount and wall thickness reduction amount during cold rolling of the pipe, and ensuring the rolling gap and the groove gap;

[0050] 8) The generation rate of inner surface scratch damage is effectively reduced by optimizing the deformation tool such as the mandrel and the sliding groove and reasonably adjusting the feed amount;

[0051] 9) The application value of the application is high, the research and development and industrialized scale production of the pure nickel seamless pipe cold rolling pipe in the industry have certain reference, popularization and application value, the domestic key engineering equipment field key material is promoted to be localized, the market application prospect is wide, and the economic benefit is considerable. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 It is a cold rolling process flow chart of the finished product size Ф48.3*1.65mm Nickel201 pure nickel seamless pipe in the pipe manufacturing method of the application;

[0053] Figure 2 It is a cold rolling process flow chart of the finished product size Ф32*4.5mm Nickel201 pure nickel seamless pipe in the pipe manufacturing method of the application;

[0054] Figure 3 It is a cold rolling process flow chart of the finished product size Ф13.7*1.2mm Nickel201 pure nickel seamless pipe in the pipe manufacturing method of the application. DETAILED DESCRIPTION

[0055] In order to better understand the above technical solutions of the present application, the technical solutions of the present application are further explained below in combination with the drawings and examples.

[0056] In combination with the drawings and examples Figure 1 As shown in the drawings, the first aspect of the present application provides a pipe manufacturing method for reducing surface defects of pure nickel cold-rolled seamless pipes, which is a technical optimization of the cold-rolled pipe manufacturing process for Nickel 201 pure nickel seamless pipes:

[0057] The LG-80 two-roll cold-rolling machine, the LG-60H two-roll cold-rolling machine, and the LD-60 three-roll cold-rolling machine are used in sequence to roll the blank with a specification of Ф80×7.5mm into a finished product blank with a specification of Ф48.3×1.65mm. The cold-rolled pipe manufacturing process is shown in Table 1 below.

[0058] Table 1: Cold-rolled process flow table for Nickel 201 pure nickel seamless pipes with a finished product specification of Ф48.3×1.65mm

[0059]

[0060] The cold-rolled process flow for Nickel 201 pure nickel seamless pipes with a finished product specification of Ф48.3×1.65mm is shown in Table 1 above:

[0061] Pass 0: The LG-80 two-roll cold-rolling machine is used for rolling, and the blank with a specification of Ф80×7.5mm is rolled into a blank with a specification of Ф57×4.5mm. The technical points of this process include: the rolling speed of the LG-80 two-roll cold-rolling machine is 60-70 times / minute, the pass gap is 0.3-1.0mm, the rolling gap is 1.5-3.8mm, the feed amount is 3-6mm, the rotation angle is 41.5-42.2 degrees, the lubrication method is online high-flow thin oil lubrication, blank re-inspection is added before rolling, and the pass is re-inspected after rolling three branches;

[0062] Pass 1: The LG-60H two-roll cold-rolling machine is used for rolling, and the blank with a specification of Ф57×4.5mm is rolled into a blank with a specification of Ф53×3.0mm. The technical points of this process include: the rolling speed of the LG-60H two-roll cold-rolling machine is 68-80 times / minute, the pass gap is 0.2-1.0mm, the rolling gap is 1.5-3.2mm, the feed amount is 3-6mm, the rotation angle is 41.5-42.2 degrees, and the lubrication method is online high-flow thin oil lubrication;

[0063] Pass 2: LD-60 is used to adopt three-roller cold rolling mill to roll, and the blank with specification Ф53*3.0mm is rolled into the finished product with specification Ф48.3*1.65mm. The technical points of this process include: the rolling speed of LD-60 three-roller cold rolling mill is 55-65 times / minute, the rolling gap is 0.5-2.0mm, the feeding amount is 3.5-4.5mm, the rotation angle is 47.5-48.5 degrees, the lubrication mode adopts online large-flow thin oil lubrication, and the chamfered smooth transition is adopted for each deformation surface of the sliding groove, the mandrel and the roller.

[0064] In combination Figure 2 As shown in the figure, the second aspect of the application provides a pipe manufacturing method for reducing the surface defects of pure nickel cold-rolled seamless pipe, which is a technical optimization of the cold-rolled pipe manufacturing process of Nickel 201 pure nickel seamless pipe:

[0065] The LG-80 two-roller cold rolling mill and the LG-55 two-roller cold rolling mill are used in sequence to roll the blank with specification Ф80*7.5mm into the semi-finished product with specification Ф38*5.0mm, and then into the finished product with specification Ф32*4.5mm. The cold-rolled pipe manufacturing process is shown in Table 2 below.

[0066] Table 2: Cold rolling process flow table of Nickel 201 pure nickel seamless pipe with finished product specification Ф32*4.5mm

[0067]

[0068]

[0069] The cold rolling process flow of Nickel 201 pure nickel seamless pipe with finished product specification Ф32*4.5mm is shown in Table 2 above:

[0070] Pass 0: LG-80 two-roller cold rolling mill is used to roll, and the blank with specification Ф80*7.5mm is rolled into the semi-finished product with specification Ф57*5.5mm. The technical points of this process include: the rolling speed of LG-80 two-roller cold rolling mill is 60-70 times / minute, the hole type gap is 0.3-1.0mm, the rolling gap is 1.5-3.8mm, the feeding amount is 3.5-6mm, the rotation angle is 41.5-42.2 degrees, the lubrication mode adopts online large-flow thin oil lubrication, the blank re-inspection is added before rolling, and the hole type is re-inspected after rolling three pipes;

[0071] Pass 1: LG-55 two-roller cold rolling mill is adopted to roll the semi-product with a specification of Ф57*5.5 mm into a product with a specification of Ф38*5.0 mm. The technical points of this process include: the rolling speed of the LG-55 two-roller cold rolling mill is 68-80 times per minute, the pass gap is 0.2-1.0 mm, the rolling gap is 1.5-3.2 mm, the feed amount is 4-6 mm, the rotation angle is 41.5-42.2 degrees, and the lubrication mode is on-line large-flow thin oil lubrication.

[0072] In combination Figure 3 As shown in the figure, the third aspect of the present application provides a pipe manufacturing method for reducing surface defects of pure nickel cold-rolled seamless pipes, which is a technical optimization of the cold-rolled pipe manufacturing process of the Nickel 201 pure nickel seamless pipe:

[0073] LG-80 two-roller cold rolling mill, LG-55 two-roller cold rolling mill and KPW-50 two-roller high-speed rolling mill are adopted in sequence to roll the blank with a specification of Ф80*7.5 mm into a semi-product with a specification of Ф25*1.5 mm, and then into a product with a specification of Ф13.7*1.2 mm. The cold-rolled pipe manufacturing process is shown in Table 3 below.

[0074] Table 3: Cold-rolled pipe manufacturing process table of the Nickel 201 pure nickel seamless pipe with a product specification of Ф13.7*1.2 mm

[0075]

[0076] The cold-rolled pipe manufacturing process of the Nickel 201 pure nickel seamless pipe with a product specification of Ф13.7*1.2 mm is shown in Table 3 above:

[0077] Pass 0: LG-80 two-roller cold rolling mill is adopted to roll the blank with a specification of Ф80*7.5 mm into a semi-product with a specification of Ф57*4.5 mm. The technical points of this process include: the rolling speed of the LG-80 two-roller cold rolling mill is 60-70 times per minute, the pass gap is 0.3-1.0 mm, the rolling gap is 1.5-3.8 mm, the feed amount is 3-6 mm, the rotation angle is 41.5-42.2 degrees, the lubrication mode is on-line large-flow thin oil lubrication, blank re-inspection is added before rolling, and the pass is re-inspected after rolling three pipes;

[0078] Pass 1: LG-55 two-roller cold rolling mill is adopted to roll the semi-product with a specification of Ф57*4.5 mm into a semi-product with a specification of Ф38*3.0 mm. The technical points of this process include: the rolling speed of the LG-55 two-roller cold rolling mill is 68-80 times per minute, the pass gap is 0.2-1.0 mm, the rolling gap is 1.5-3.2 mm, the feed amount is 3-6 mm, the rotation angle is 41.5-42.2 degrees, and the lubrication mode is on-line large-flow thin oil lubrication;

[0079] Pass 2: the semi-finished product with a specification of Ф38*3.0mm is rolled into a finished product with a specification of Ф13.7*1.2mm by using a KPW-50 two-high high-speed rolling mill. The technical key points of the process include that the rolling speed of the KPW-50 two-high high-speed rolling mill is 110-140 times per minute, the pass gap is 0.15-0.5mm, the rolling gap is 1.2-2.8mm, the feed amount is 3.5-5mm, the angle of the entry end is 31.0 degrees, the angle of the exit end is 26.0 degrees, and the lubrication mode is combined with online large-flow thin oil external lubrication and high-pressure internal lubrication of the special rolling lubricant core rod tail.

[0080] In summary, according to the steel type characteristics and technical requirements of the three finished product specifications of Nickel201 pure nickel seamless pipes, the cold rolling pipe production under normal temperature conditions can be completed according to the production process, and the surface defects of the pure nickel pipe can be reduced, and the quality of the inner and outer surfaces can be improved. The cold rolled pipe after rolling directly enters the subsequent finished product processing process, or the pipe is directly drawn according to the requirements of the finished pipe.

[0081] It should be particularly pointed out that the technical scheme provided by the present application only relates to the rolling process in the cold rolling pipe, and does not include heat treatment, finishing (sizing pipe cutting flat head, straightening), pickling (cleaning) and inspection, preparation and installation of deformation tools (pass, roller, inner and outer die, core rod, top head) and other processes. At the same time, the size of the pass product is the nominal nominal size.

[0082] A pipe manufacturing method for reducing surface defects of pure nickel cold-rolled seamless pipes is a technical optimization of the cold-rolled seamless pipe process of Nickel201 pure nickel seamless pipes. According to three different finished product specifications, the matching cold-rolled pipe process is implemented, the existing equipment is fully utilized, the characteristics of two-roll and three-roll cold rolling machines are utilized, the advantages of short process and high productivity are highlighted, the quality and efficiency of finished product rolling are ensured, the production organization is facilitated, and the production cost is reduced. By optimizing the feed amount and wall thickness reduction amount during cold rolling, the generation of wavy defects is effectively avoided; by strengthening the inspection and grinding of the surface of the blank pipe and increasing the online inspection frequency of the pass rolling groove, the pitting (pit) during blank pipe rolling is effectively reduced; by optimizing the deformation tools such as core rod and sliding groove and reasonably adjusting the feed amount, the internal surface scratching damage is effectively reduced. The process design is reasonable, the process organization is smooth, it is safe, reliable, practical and efficient, it meets the technical requirements of the cold-rolled pipe process of Nickel201 pure nickel seamless pipes, reduces the surface defect loss of the pure nickel pipe, continuously and stably improves the surface rolling quality, promotes the core competitiveness of the enterprise, and has significant energy saving, emission reduction and consumption reduction effects. It has strong universality and certain reference, popularization and application value for the research and development and industrialized scale production of pure nickel seamless pipe cold rolling in the industry, promotes the localization of key materials in the field of domestic key engineering equipment, has broad market application prospect and considerable economic benefits.

[0083] Example 1

[0084] Referring again to Figure 1 , a steel pipe plant of a certain steel company, using the technical solutions provided by the present application on the cold-rolled seamless steel pipe production line, produces cold-rolled nickel 201 pure nickel seamless pipe with a finished product specification of Ф48.3x1.65mm for a caustic soda device used in a technical improvement project of a certain key petrochemical enterprise in China. The cold-rolling equipment involved includes LG-80 two-roll periodic cold-rolling machine, LG-60H two-roll periodic cold-rolling machine, and LD-60 three-roll periodic cold-rolling machine. The cold-rolled pipe process is shown in Table 1 below.

[0085] Table 1: Cold-rolling process table for finished product specification Ф48.3x1.65mm nickel 201 pure nickel seamless pipe

[0086]

[0087] Pass 0: LG-80 two-roll cold-rolling machine is used for rolling, and the blank with a specification of Ф80x7.5mm is rolled into a blank with a specification of Ф57x4.5mm. The technical points of this process include: the rolling speed of the LG-80 two-roll cold-rolling machine is 65 times / minute, the pass gap is 0.65mm, the rolling gap is 2.65mm, the feed amount is 4.5mm, the angle is 41.85 degrees, the lubrication mode is online high-flow thin oil lubrication, and the blank is rechecked before rolling, and the pass is rechecked after rolling three pipes;

[0088] Pass 1: LG-60H two-roll cold-rolling machine is used for rolling, and the blank with a specification of Ф57x4.5mm is rolled into a blank with a specification of Ф53x3.0mm. The technical points of this process include: the rolling speed of the LG-60H two-roll cold-rolling machine is 74 times / minute, the pass gap is 0.6mm, the rolling gap is 2.35mm, the feed amount is 4.5mm, the angle is 41.85 degrees, and the lubrication mode is online high-flow thin oil lubrication;

[0089] Pass 2: LD-60 three-roll cold-rolling machine is used for rolling, and the blank with a specification of Ф53x3.0mm is rolled into a finished product with a specification of Ф48.3x1.65mm. The technical points of this process include: the rolling speed of the LD-60 three-roll cold-rolling machine is 60 times / minute, the rolling gap is 1.25mm, the feed amount is 4mm, the angle is 48 degrees, the lubrication mode is online high-flow thin oil lubrication, and the chamfered smooth transition is adopted for each deformation surface of the chute, mandrel and roller.

[0090] The cold-rolled pipe is the finished product pipe, which is then finished, pickled, inspected and put into storage for delivery.

[0091] Example 2

[0092] Referring again toFigure 2 A steel pipe plant of a certain steel company uses the technical solution provided by the present application on the cold working production line of seamless steel pipes to produce cold-rolled pipes of Ф32x4.5mm Nickel 201 pure nickel seamless pipes used in the caustic soda device of a certain key petrochemical enterprise in China. The cold-rolling equipment involved includes LG-80 two-roll periodic cold-rolling machine and LG-55 two-roll periodic cold-rolling machine. The cold-rolled pipe process is shown in Table 2 below.

[0093] Table 2: Cold-rolling process table of Ф32x4.5mm Nickel 201 pure nickel seamless pipe product specification

[0094]

[0095] The cold-rolling process of Ф32x4.5mm Nickel 201 pure nickel seamless pipe product specification is shown in Table 2 above:

[0096] Pass 0: LG-80 two-roll cold-rolling machine is used for rolling, and the Ф80x7.5mm blank is rolled into Ф57x5.5mm semi-finished product. The technical points of this process include: the rolling speed of LG-80 two-roll cold-rolling machine is 65 times / minute, the pass gap is 0.65mm, the rolling gap is 2.65mm, the feed amount is 4.75mm, the angle is 41.85 degrees, the lubrication mode is online large-flow thin oil lubrication, and the blank re-inspection before rolling is increased, and the pass is re-inspected after rolling three pipes;

[0097] Pass 1: LG-55 two-roll cold-rolling machine is used for rolling, and the Ф57x5.5mm semi-finished product is rolled into Ф38x5.0mm finished product for blank. The technical points of this process include: the rolling speed of LG-55 two-roll cold-rolling machine is 74 times / minute, the pass gap is 0.6mm, the rolling gap is 2.35mm, the feed amount is 5mm, the angle is 41.85 degrees, and the lubrication mode is online large-flow thin oil lubrication.

[0098] The cold-rolled pipe is the intermediate product pipe, which is used as the blank for the subsequent cold-drawing pipe after inspection.

[0099] Example 3

[0100] A steel pipe plant of a certain steel company uses the technical solution provided by the present application on the cold working production line of seamless steel pipes to produce cold-rolled pipes of Ф32x4.5mm Nickel 201 pure nickel seamless pipes used in the caustic soda device of a certain key petrochemical enterprise in China. The cold-rolling equipment involved includes LG-80 two-roll periodic cold-rolling machine, LG-55 two-roll periodic cold-rolling machine, and KPW-50 two-roll high-speed rolling machine. The cold-rolled pipe process is shown in Table 3 below.

[0101] Table 3: Cold rolling process table of finished product specification Ф13.7x1.2mm Nickel 201 pure nickel seamless pipe

[0102]

[0103]

[0104] Pass 0: LG-80 two-roller cold rolling mill is adopted for rolling, and the blank with specification Ф80x7.5mm is rolled into semi-product with specification Ф57x4.5mm. The technical points of this process include: the rolling speed of LG-80 two-roller cold rolling mill is 65 times per minute, the pass gap is 0.65mm, the rolling gap is 2.65mm, the feed amount is 4.5mm, the rotation angle is 41.85 degrees, the lubrication mode adopts online large-flow thin oil lubrication, blank re-inspection is added before rolling, and the pass is re-inspected after rolling three pipes;

[0105] Pass 1: LG-55 two-roller cold rolling mill is adopted for rolling, and the semi-product with specification Ф57x4.5mm is rolled into semi-product with specification Ф38x3.0mm. The technical points of this process include: the rolling speed of LG-55 two-roller cold rolling mill is 74 times per minute, the pass gap is 0.6mm, the rolling gap is 2.35mm, the feed amount is 4.5mm, the rotation angle is 41.85 degrees, and the lubrication mode adopts online large-flow thin oil lubrication;

[0106] Pass 2: KPW-50 two-roller high-speed rolling mill is adopted for rolling, and the semi-product with specification Ф38x3.0mm is rolled into finished product with specification Ф13.7x1.2mm for blank. The technical points of this process include: the rolling speed of KPW-50 two-roller high-speed rolling mill is 125 times per minute, the pass gap is 0.325mm, the rolling gap is 2mm, the feed amount is 4.25mm, the rotation angle is 31.0 degrees at the import end and 26.0 degrees at the export end, and the lubrication mode adopts the combination of online large-flow thin oil external lubrication and special rolling lubricant core rod tail high-pressure input internal lubrication.

[0107] The cold-rolled pipe is the intermediate product pipe, which is used as the blank for the subsequent processing of cold-drawing pipe after inspection.

[0108] Those skilled in the art of the present technical field should recognize that the above embodiments are only used to illustrate the present application, and are not used as the limitation of the present application, and as long as the changes and modifications of the above described embodiments are within the scope of the spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A pipe manufacturing method for reducing surface defects of a pure nickel cold-rolled seamless pipe, characterized in that: a LG-80 two-roller cold-rolling machine, a LG-60H two-roller cold-rolling machine and a LD-60 three-roller cold-rolling machine are sequentially used to roll a blank with a size of Ф80×7.5 mm into a finished blank with a size of Ф48.3×1.65 mm through the following passes, the passes include: Pass 0: the LG-80 two-roller cold-rolling machine is used to roll the blank with a size of Ф80×7.5 mm into a blank with a size of Ф57×4.5 mm; Pass 1: the LG-60H two-roller cold-rolling machine is used to roll the blank with a size of Ф57×4.5 mm into a blank with a size of Ф53×3.0 mm; Pass 2: the LD-60 three-roller cold-rolling machine is used to roll the blank with a size of Ф53×3.0 mm into the finished blank with a size of Ф48.3×1.65 mm, in the pass 0, the rolling speed of the LG-80 two-roller cold-rolling machine is 60-70 times per minute, the pass gap is 0.3-1.0 mm, the rolling gap is 1.5-3.8 mm, the feed amount is 3-6 mm, the rotation angle is 41.5-42.2 degrees, the lubrication mode is online large-flow thin oil lubrication, blank re-inspection is added before rolling, and the pass is re-inspected after rolling three pipes; in the pass 1, the rolling speed of the LG-60H two-roller cold-rolling machine is 68-80 times per minute, the pass gap is 0.2-1.0 mm, the rolling gap is 1.5-3.2 mm, the feed amount is 3-6 mm, the rotation angle is 41.5-42.2 degrees, and the lubrication mode is online large-flow thin oil lubrication; in the pass 2, the rolling speed of the LD-60 three-roller cold-rolling machine is 55-65 times per minute, the rolling gap is 0.5-2.0 mm, the feed amount is 3.5-4.5 mm, the rotation angle is 47.5-48.5 degrees, the lubrication mode is online large-flow thin oil lubrication, and the chamfered smooth transition is adopted for each deformation surface of the chute, the mandrel and the roller.

2. A pipe manufacturing method for reducing surface defects of a pure nickel cold-rolled seamless pipe, characterized in that: a LG-80 two-roller cold-rolling machine, a LG-55 two-roller cold-rolling machine and a KPW-50 two-roller high-speed rolling machine are sequentially used to roll a blank with a size of Ф80×7.5 mm into a semi-finished product with a size of Ф57×4.5 mm, a semi-finished product with a size of Ф38×3.0 mm, and then a finished blank with a size of Ф13.7×1.2 mm through the following passes, the passes include: Pass 0: the LG-80 two-roller cold-rolling machine is used to roll the blank with a size of Ф80×7.5 mm into the semi-finished product with a size of Ф57×4.5 mm; Pass 1: the LG-55 two-roller cold-rolling machine is used to roll the semi-finished product with a size of Ф57×4.5 mm into the semi-finished product with a size of Ф38×3.0 mm; Pass 2: the KPW-50 two-roller high-speed rolling machine is used to roll the semi-finished product with a size of Ф38×3.0 mm into the finished blank with a size of Ф13.7×1.2 mm, ​ In the pass 0, the rolling speed of the LG-80 two-roll cold rolling machine is 60-70 times per minute, the pass gap is 0.3-1.0 mm, the rolling gap is 1.5-3.8 mm, the feed amount is 3-6 mm, the rotation angle is 41.5-42.2 degrees, the lubrication mode adopts online large-flow thin oil lubrication, and the blank re-inspection is added before rolling; the pass is re-inspected after rolling three branch pipes; In the pass 1, the rolling speed of the LG-55 two-roll cold rolling machine is 68-80 times per minute, the pass gap is 0.2-1.0 mm, the rolling gap is 1.5-3.2 mm, the feed amount is 3-6 mm, the rotation angle is 41.5-42.2 degrees, and the lubrication mode adopts online large-flow thin oil lubrication; In the pass 2, the rolling speed of the KPW-50 two-roll high-speed rolling machine is 110-140 times per minute, the pass gap is 0.15-0.5 mm, the rolling gap is 1.2-2.8 mm, the feed amount is 3.5-5 mm, the rotation angle at the inlet end is 31.0 degrees, and the outlet end is 26.0 degrees, and the lubrication mode adopts the combination of online large-flow thin oil external lubrication and special rolling lubricant core rod tail high-pressure input internal lubrication.

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