Novel process for doubling production of seamless steel tube and titanium alloy seamless tube

Abstract

The invention discloses a novel process for doubling production of seamless steel tubes and titanium alloy seamless tubes, which is characterized in that an electric furnace and an induction coil are additionally arranged, and a series of technical measures such as a distribution form of a heating furnace, a discharge rule of tube blanks and a quick switching rule of rolling modes are set; the purpose of alternately rolling the seamless steel tube and the titanium alloy seamless tube can be well achieved, and the quality and the size precision of the seamless steel tube and the titanium alloy seamless tube both meet the expected requirements.

Description

Technical Field

[0001] The present invention belongs to the technical field of the production processes of seamless steel pipes and titanium alloy seamless pipes, and particularly relates to a new process for the parallel production of seamless steel pipes and titanium alloy seamless pipes. Background Art

[0002] At present, seamless steel pipes are widely used in all walks of life of the national economy, such as oil extraction, oil and gas transportation, petrochemical industry, power station boilers, structural supports and other fields; titanium alloy pipes are mainly used in important fields of aerospace and national defense. At present, most titanium alloy pipes are prepared by the process of sheet rolling + butt welding. This process has many disadvantages such as long manufacturing cycle, large number of welds, high production cost, and poor reliability; a few pipe manufacturing enterprises adopt some technologies of seamless pipe manufacturing, that is, they adopt the process of cross-rolling piercing + sizing of the mandrel tube for preparation. However, since these enterprises either adopt a single production mode of hydraulic drawing + stress relief annealing or a single production mode of multi-pass cold rolling + annealing treatment, the pipe manufacturing cost of these enterprises is relatively high and the production efficiency is relatively low; at the same time, since these enterprises use a gas furnace to heat the titanium alloy pipe billets, it is extremely easy to cause chemical reactions between the titanium alloy billets and oxygen, nitrogen, carbon, iron, etc. at high temperatures and cause the problem of hydrogen absorption. Therefore, the surface quality of the titanium alloy pipes produced by these enterprises is also relatively poor.

[0003] After retrieval, it is found that there are three patent literatures most relevant to the technology of the present utility model, and the specific contents are described as follows:

[0004] The patent literature CN 201410335795.1 discloses a method for producing titanium alloy pipes. This invention produces titanium alloy pipes through processes such as smelting of titanium alloy pipe billets → heating of pipe billets → cross-rolling piercing → sizing → straightening while hot → pickling → hydraulic drawing → stress relief annealing → straightening while hot. Since this invention designs the chemical composition of titanium alloy pipes and jointly adopts the technologies of controlling the thickness of the gas permeation layer by heating the round billet and pickling the rough pipe after air cooling, it can effectively avoid the generation of defects on the surface of titanium alloy pipes, thereby improving the surface quality of titanium alloy pipes. However, since this invention is based on a single rolling process for production, the pipe manufacturing cost of this invention is relatively high and the production efficiency is relatively low.

[0005] Patent document CN 201610756735.6 discloses a titanium alloy tube and its manufacturing process. This invention produces titanium alloy tubes through processes such as smelting of the titanium alloy tube blank → heating of the tube blank → cross-rolling piercing → sizing → warm straightening → pickling → hydrostatic drawing → stress relief annealing → warm straightening. Since this invention designs the chemical composition of the titanium alloy tube and combines the technologies of controlling the thickness of the gas permeation layer during the heating of the round billet and pickling the rough tube after air cooling, it can effectively avoid surface defects of the titanium alloy tube, thereby improving the surface quality of the titanium alloy tube. However, because this invention is produced based on the process of single rolling, the tube manufacturing cost of this invention is relatively high and the production efficiency is relatively low.

[0006] Patent document CN 201810734899.8 discloses a processing technology for titanium alloy tubes. This invention produces seamless titanium alloy tubes through processes such as melting + pouring + die-casting of the alloy into a tube blank → extrusion piercing → multi-pass cold rolling → degreasing + annealing treatment → surface treatment. Since this invention adopts the production process of directly extruding and piercing the tube blank with a certain temperature, the energy-consuming tube blank heating link is omitted in the middle, which is equivalent to adopting the energy-saving technology of continuous casting and rolling. This can greatly reduce the tube manufacturing cost. However, because this invention is produced based on the process of extrusion piercing + cold rolling + annealing treatment, the production efficiency of this invention is relatively low, and at the same time, the surface quality of the titanium alloy tube is also relatively poor. Summary of the Invention

[0007] The purpose of the present invention is to provide a new process for the parallel production of seamless steel tubes and seamless titanium alloy tubes. Using the new process described in the present invention, seamless titanium alloy tubes with relatively low production costs, relatively good surface quality, and relatively high production efficiency can be manufactured.

[0008] Pure titanium has two allotropes. Below 882.5 °C, it is in the low-temperature α crystal form with a close-packed hexagonal lattice, and above 882.5 °C, it is in the high-temperature β crystal form with a body-centered cubic lattice. Since the transformation temperature from the α crystal form to the β crystal form is between 890 °C and 930 °C, the best plastic deformation temperature of titanium alloy is between 880 °C and 980 °C. Since titanium alloy is extremely easy to absorb oxygen when heated in the range of 300 °C to 700 °C, it is necessary to control the oxidation atmosphere of the heating furnace during heating.

[0009] To overcome one or more of the problems existing in the prior art, based on the existing continuous pipe rolling mill production line and the characteristics of plastic deformation of titanium alloy materials, this invention patent adopts an off-line electric furnace heating + steel-titanium co-rolling production mode, where seamless steel pipes and seamless titanium alloy pipes are alternately rolled. When rolling seamless titanium alloy pipes, the tools can be appropriately preheated by relying on the rolling process of seamless steel pipes, which can save a large amount of energy consumption. When rolling seamless steel pipes, the tools can be appropriately cooled by relying on the rolling process of seamless titanium alloy pipes, and the two rely on each other. In addition, using an electric furnace for heating can ensure that the titanium alloy billets are in a non-oxidizing atmosphere during the heating process, and at the same time, the heating time is significantly shortened. Therefore, the patented technology of this invention has the characteristics of relatively low production cost, relatively good surface quality, and relatively high production efficiency.

[0010] To solve the above technical problems, this invention adopts the following technical solutions:

[0011] A new process for co-rolling seamless steel pipes and seamless titanium alloy pipes of this invention. The rolling process flow of seamless steel pipes is briefly described as: billet heating → mushroom piercing → continuous rolling → stretch reducing → hot straightening → cooling on the cooling bed → sizing sawing; the corresponding working station process of seamless steel pipes is: rotary hearth furnace → mushroom piercing machine → continuous rolling mill unit → stretch reducing mill unit → roller straightening machine → walking beam cooling bed → flying saw; where:

[0012] First, use a charging machine to send the sized steel billets after sizing sawing into the rotary hearth furnace for heating, then use a discharging machine to take out the heated steel billets from the rotary hearth furnace, then use a transfer chain to send the steel billets after leaving the furnace into the mushroom piercing machine for mushroom piercing, then use a chain conveyor to send the pierced steel shell into the continuous rolling mill unit for continuous rolling, then use a transfer roller table to send the rough steel pipes after continuous rolling into the stretch reducing mill unit for stretch reducing, then use a transfer roller table to send the rough steel pipes after stretch reducing into the roller straightening machine for hot straightening, then use a transfer roller table to send the rough steel pipes after hot straightening into the walking beam cooling bed for natural cooling, and finally use a transfer roller table to send the rough steel pipes after natural cooling into the flying saw for sizing sawing, so as to obtain the seamless steel pipe finished products of the required specifications;

[0013] The rolling process flow of seamless titanium alloy pipes is briefly described as: billet heating → mushroom piercing → continuous rolling → induction in-line heating → stretch reducing → hot straightening → cooling on the cooling bed → sizing sawing; the corresponding working station process of seamless titanium alloy pipes is: electric furnace → mushroom piercing machine → continuous rolling mill unit → induction coil → stretch reducing mill unit → roller straightening machine → walking beam cooling bed → flying saw; where:

[0014] First, use a charging machine to send the sized and sawn titanium alloy tube blanks into an electric furnace for heating. Then, use a discharging machine to take out the heated titanium alloy tube blanks from the electric furnace. Next, use a transfer chain to send the titanium alloy tube blanks out of the furnace into a mushroom piercing mill for mushroom piercing. Then, use a chain conveyor to send the pierced titanium alloy tube blanks into a continuous rolling mill for continuous rolling. Then, use a transfer roller table to send the rough titanium alloy tubes after continuous rolling into an induction coil for on-line heating. Then, use a transfer roller table to send the rough titanium alloy tubes after induction on-line heating into a stretch reducing mill for stretch reducing. Then, use a transfer roller table to send the rough titanium alloy tubes after stretch reducing into a roller straightening machine for straightening while still warm. Then, use a transfer roller table to send the rough titanium alloy tubes after straightening while still warm into a walking beam cooling bed for natural cooling. Finally, use a transfer roller table to send the rough titanium alloy tubes after natural cooling into a saw for sizing and sawing, so as to obtain the finished titanium alloy seamless tubes of the required specifications.

[0015] Furthermore, the prerequisite for the co-line rolling production of seamless steel tubes and titanium alloy seamless tubes is that the specifications of the steel tube blanks are exactly the same as those of the titanium alloy tube blanks, and the specifications of the seamless steel tubes are also exactly the same as those of the titanium alloy seamless tubes.

[0016] Furthermore, the charging form of the heating furnace for the co-line rolling production of seamless steel tubes and titanium alloy seamless tubes: Determine the charging forms of the rotary hearth furnace and the electric furnace according to the walking rhythms of the rotary hearth furnace and the electric furnace. Let's assume that the walking rhythm of the rotary hearth furnace is M minutes and the walking rhythm of the electric furnace is N minutes. Both M and N are positive integers, and M ≤ N, that is, the billet discharging frequency of the rotary hearth furnace is faster than that of the electric furnace. For the sake of simplified design, use the empty billet position time of the rotary hearth furnace to load the titanium alloy tube blanks into the electric furnace. Then, the charging method of the rotary hearth furnace is to load (N - 1) and leave 1 empty, and the charging method of the electric furnace is to load 1 and leave (M - 1) empty.

[0017] Furthermore, the billet discharging rule for the co-line rolling production of seamless steel tubes and titanium alloy seamless tubes: First, discharge the steel tube blanks from the rotary hearth furnace, and then use the empty billet position time of the rotary hearth furnace to discharge the titanium alloy tube blanks from the electric furnace.

[0018] Furthermore, the rolling mode switching rule for the co-line rolling production of seamless steel tubes and titanium alloy seamless tubes: If the steel tube blanks are discharged from the rotary hearth furnace, switch the computer to the rolling mode of seamless steel tubes and set the induction heating to the off state at the same time; if the titanium alloy tube blanks are discharged from the electric furnace, switch the computer to the rolling mode of titanium alloy seamless tubes and set the induction heating to the on state at the same time.

[0019] Furthermore, adopt an off-line electric furnace heating + co-line rolling production mode of steel and titanium, and alternately roll seamless steel tubes and titanium alloy seamless tubes.

[0020] Furthermore, during the rolling of seamless titanium alloy tubes, the tools are appropriately preheated by means of the rolling process of seamless steel tubes to save a large amount of energy consumption. During the rolling of seamless steel tubes, the tools are appropriately cooled by means of the rolling process of seamless titanium alloy tubes, and the two rely on each other.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0022] ① Due to the adoption of the production mode of offline electric furnace heating + co - rolling of steel and titanium, seamless steel tubes and seamless titanium alloy tubes are alternately rolled. When rolling seamless titanium alloy tubes, the tools can be appropriately preheated by means of the rolling process of seamless steel tubes, which can save a large amount of energy consumption. At the same time, when rolling seamless steel tubes, the tools can be appropriately cooled by means of the rolling process of seamless titanium alloy tubes. Therefore, the production cost of this invention patent is relatively low.

[0023] ② Since electric furnace heating is adopted, it can ensure that the titanium alloy tube billets are in a non - oxidation atmosphere during the heating process, eliminating the oxidation problem of titanium alloy tube billets during heating. Since an induction coil is added above the transfer roller table between the continuous pipe rolling mill and the stretch reducing mill, the titanium alloy rough tubes can be heated online to ensure their plastic deformation in the best temperature range. Therefore, the surface quality of the seamless titanium alloy tubes produced by this invention patent is relatively good.

[0024] ③ Due to the adoption of the traditional production mode of separate rolling of steel and titanium, the production cycle of seamless titanium alloy tubes is 11 hours. By adopting the production mode of co - rolling of steel and titanium provided by the present invention and using electric furnace heating, the empty furnace cooling time of the ring furnace can be eliminated, and at the same time, the soaking time of the titanium alloy tube billets can be shortened, thus shortening the production cycle of seamless titanium alloy tubes to 2 hours. Therefore, the production efficiency of this invention patent is relatively high.

[0025] In summary, based on a new process for the co - production of seamless steel tubes and seamless titanium alloy tubes provided by the present invention, an electric furnace and an induction coil are added. Through a series of technical measures such as setting the charging form of the heating furnace, the discharging rules of the tube billets, and the rapid switching rules of the rolling mode, the purpose of alternately rolling seamless steel tubes and seamless titanium alloy tubes can be well achieved, and the quality and dimensional accuracy of the products of seamless steel tubes and seamless titanium alloy tubes have reached the expected requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below with reference to the drawings.

[0027] Figure 1 It is a schematic diagram of the structural arrangement of the new process for the co - production of seamless steel tubes and seamless titanium alloy tubes;

[0028] Figure 2 It is a schematic diagram of the structural arrangement of the production process of seamless steel tubes rolled alone;

[0029] Figure 3 Schematic diagram of the structural setup for the production process of separately rolling titanium alloy seamless tubes. Specific implementation mode

[0030] The following further details the present invention patent in conjunction with Example 1 and Example 2. The rolling process flow and station process in Example 1 and Example 2 are completely the same. The specifications of the steel pipe billets are completely the same as those of the titanium alloy pipe billets, and the specifications of the seamless steel pipes are also completely the same as those of the titanium alloy seamless pipes. The only differences are the number of charging positions in the heating furnace, the charging method, the stepping frequency, the stepping rhythm, and the heating cycle of the pipe billets; the charging form of the ring furnace is determined according to the stepping rhythm of the steel pipe billets in the ring furnace and the stepping rhythm of the titanium alloy pipe billets in the electric furnace.

[0031] First, add an electric furnace near the original ring furnace and transfer chain to heat the titanium alloy pipe billets in a non-oxidizing atmosphere; at the same time, add multiple induction coils on the transport roller path between the continuous pipe rolling mill and the stretch reducing mill to heat the titanium alloy semi-finished pipes coming out of the continuous pipe rolling mill online and raise the temperature of the titanium alloy semi-finished pipes to the inlet temperature required by the stretch reducing mill; at the same time, realize the rapid switching of process parameters between rolling seamless steel pipes and rolling titanium alloy seamless pipes through computer operation software to facilitate the alternate rolling between seamless steel pipes and titanium alloy seamless pipes more conveniently.

[0032] The rolling process flow of seamless steel pipes is briefly described as: pipe billet heating → conical piercing → continuous pipe rolling → stretch reducing → hot straightening → cooling on the cooling bed → sizing sawing; the corresponding station process of seamless steel pipes is: ring furnace → conical piercing machine → continuous pipe rolling mill → stretch reducing mill → roller straightening machine → walking beam cooling bed → flying saw.

[0033] The rolling process of seamless steel pipes is briefly described as follows: First, use a loading machine to send the sized steel pipe billets after sizing sawing into the ring furnace for heating, then use an unloading machine to take out the heated steel pipe billets from the ring furnace, then use a transfer chain to send the steel pipe billets out of the furnace into the conical piercing machine for conical piercing, then use a chain conveyor to send the pierced steel pipe blanks into the continuous pipe rolling mill for continuous rolling, then use a transport roller path to send the steel pipe semi-finished pipes after continuous rolling into the stretch reducing mill for stretch reducing, then use a transport roller path to send the steel pipe semi-finished pipes after stretch reducing into the roller straightening machine for hot straightening, then use a transport roller path to send the steel pipe semi-finished pipes after hot straightening into the walking beam cooling bed for natural cooling, and finally use a transport roller path to send the steel pipe semi-finished pipes after natural cooling into the flying saw for sizing sawing, so as to obtain seamless steel pipe products of the required specifications.

[0034] The rolling process of titanium alloy seamless pipe is briefly described as follows: tube billet heating → mushroom punching → continuous tube rolling → induction online heating → tension reducing → warm straightening → cooling on cooling bed → cut to length; the corresponding work station process of titanium alloy seamless pipe is: electric furnace → mushroom punching machine → continuous tube rolling unit → induction coil → tension reducing unit → roller straightening machine → walking cooling bed → gang saw.

[0035] The rolling process of titanium alloy seamless pipe is briefly described as follows: first, the titanium alloy tube billet after the fixed length sawing is sent into the electric furnace for heating by the loader, and then the heated titanium alloy tube billet is taken out of the electric furnace by the discharging machine, and then the titanium alloy tube billet after the furnace is sent to the mushroom punching machine for mushroom punching by the transmission chain, and then the titanium alloy rough tube after the punching is sent to the continuous tube rolling unit by the chain conveyor for continuous rolling, and then the titanium alloy rough tube after continuous rolling is sent to the induction coil by the transport roller for online Heating, and then using a conveyor roller to send the titanium alloy rough pipe after induction online heating to the tension reducing unit for tension reducing, and then using a conveyor roller to send the titanium alloy rough pipe after tension reducing to the roller straightening machine for hot straightening, and then using a conveyor roller to send the titanium alloy rough pipe after hot straightening to the step-type cooling bed for natural cooling, and finally using a conveyor roller to send the titanium alloy rough pipe after natural cooling to the gang saw for fixed-length sawing, so that the required specifications of titanium alloy seamless pipe products can be obtained.

[0036] Table 1: Furnace type, number of material positions, number of steps to be taken out of the furnace, step frequency, heating cycle of the tube blank and charging method of the heating furnace of Example 1

[0037]

[0038] In Example 1, the tube blank specifications are Seamless pipe specifications are Since the stepping rhythm of the annular furnace is 1 minute and the stepping rhythm of the electric furnace is 10 minutes, the annular furnace adopts a distribution method of 9 loaded and 1 empty, and the electric furnace adopts a distribution method of 1 loaded and 0 empty, that is, a dense distribution method.

[0039] Specific conditions of steel tube billets in annular furnace:

[0040] It is advisable to count the moment when the annular furnace starts to load the first steel tube billet as the 0th minute. Since the stepping rhythm of the annular furnace is 1 minute, the annular furnace charging machine loads a steel tube billet into the annular furnace every 1 minute; since the electric furnace will not produce titanium alloy tube billets before the 299th minute, the 1st to the 85th steel tube billets can be placed in a dense manner, that is, the 2nd, 3rd, ..., 84th and 85th steel tube billets are loaded into the annular furnace at the 1st minute, the 2nd minute, ..., the 83rd minute and the 84th minute;

[0041] At the 85th minute, no steel tube billet is loaded into the annular furnace. From the 86th minute, the annular furnace adopts a distribution mode of 9 loaded and 1 empty, that is, at the 86th minute, 87th minute, ..., 93rd minute and 94th minute, the 86th, 87th, ..., 93rd and 94th steel tube billets are loaded into the annular furnace, and at the 95th minute, no steel tube billet is loaded into the annular furnace; by analogy, it is not difficult to find the charging rule of the annular furnace: that is, only at the 10A+5th minute, no steel tube billet is loaded into the annular furnace (A is an integer not less than 8), and the annular furnace is loaded at other times;

[0042] At the 376th minute, the 347th steel billet was loaded. After that, the annular furnace adopted a dense distribution method, that is, the annular furnace loader loaded a steel billet into the annular furnace every 1 minute.

[0043] Specific conditions of loading titanium alloy tube billets into electric furnace:

[0044] It is advisable to count the moment when the electric furnace starts to load the first titanium alloy tube billet as the 0th minute. Since the stepping rhythm of the electric furnace is 10 minutes and the electric furnace adopts a densely packed feeding method, the electric furnace charging machine loads a titanium alloy tube billet into the electric furnace every 10 minutes, that is, the second and third titanium alloy tube billets are loaded into the electric furnace at the 10th and 20th minutes, and so on. It is not difficult to find the charging rule of the electric furnace: that is, a titanium alloy tube billet is loaded into the electric furnace at the 10Bth minute (B is a non-negative integer);

[0045] Since the electric furnace has a total of 30 material positions, that is, the 30th titanium alloy tube billet is loaded at the 290th minute. In view of the relatively small production volume of titanium alloy tubes, only one furnace of titanium alloy tube billets is loaded each time.

[0046] Specific conditions of steel tube billet produced by ring furnace:

[0047] At the 215th minute, the first steel tube billet loaded into the annular furnace reaches its heating cycle of 215 minutes. At this time, the annular furnace discharger starts to discharge the first steel tube billet. At this time, the computer is switched to the rolling mode of the seamless steel pipe, and the induction heating is set to off. Since the annular furnace is continuously loaded with 85 steel tube billets, the annular furnace discharger starts to continuously discharge steel tube billets until the 299th minute, that is, the second, third, ..., 84th and 85th steel tube billets are discharged at the 216th minute, the 217th minute, ..., the 298th minute and the 299th minute. These 85 steel tube billets are successively subjected to mushroom punching → continuous tube rolling → tension reduction → belt temperature straightening → cooling on a cooling bed → cut to length, so as to obtain seamless steel tube finished products of the required specifications.

[0048] At the 591st minute, the 347th steel tube blank loaded into the rotary hearth furnace reaches its heating cycle of 215 minutes. At this time, the rotary hearth furnace discharging machine starts to discharge the 347th steel tube blank. At this moment, the computer is switched to the rolling mode of seamless steel tubes, and the induction heating is set to the off state. In this way, the 347th steel tube blank successively undergoes mushroom piercing → continuous rolling → stretch reducing → hot straightening → cooling on the cooling bed → sizing sawing to obtain the finished seamless steel tube of the required specification. After that, the rotary hearth furnace discharging machine starts to continuously discharge steel tube blanks.

[0049] Specific situation of the electric furnace discharging titanium alloy tube blanks:

[0050] At the 300th minute, the 1st titanium alloy tube blank loaded into the electric furnace reaches its heating cycle of 300 minutes. The electric furnace discharging machine starts to discharge the 1st titanium alloy tube blank. At this time, the computer is switched to the rolling mode of titanium alloy seamless tubes, and the induction heating is set to the on state. After that, the electric furnace discharging machine discharges one titanium alloy tube blank every 10 minutes, that is, at the 310th minute and the 320th minute, the 2nd and 3rd titanium alloy tube blanks start to be discharged. These 3 titanium alloy tube blanks successively undergo mushroom piercing → continuous rolling → induction on-line heating → stretch reducing → hot straightening → cooling on the cooling bed → sizing sawing to obtain the finished titanium alloy seamless tubes of the required specification.

[0051] At the 590th minute, the 30th titanium alloy tube blank loaded into the electric furnace reaches its heating cycle of 300 minutes. The electric furnace discharging machine starts to discharge the 30th titanium alloy tube blank. At this time, the computer is switched to the rolling mode of titanium alloy seamless tubes, and the induction heating is set to the on state. In this way, the 30th titanium alloy tube blank successively undergoes mushroom piercing → continuous rolling → induction on-line heating → stretch reducing → hot straightening → cooling on the cooling bed → sizing sawing to obtain the finished titanium alloy seamless tubes of the required specification.

[0052] Table 2: Furnace type, number of charging positions, number of discharging steps, stepping frequency, heating cycle of tube blanks, and charging method of the heating furnace in Example 2

[0053]

[0054] In Example 2, the specifications of the tube blanks are all The specifications of the seamless tubes are all Since the stepping rhythm of the rotary hearth furnace is 1 minute and that of the electric furnace is 10 minutes, therefore, the rotary hearth furnace adopts a charging method of loading 9 and leaving 1 empty, and the electric furnace adopts a charging method of loading 1 and leaving 0 empty, that is, a close-packed charging method.

[0055] Specific situation of the rotary hearth furnace loading steel tube blanks:

[0056] It is advisable to count the moment when the annular furnace starts to load the first steel tube billet as the 0th minute. Since the stepping rhythm of the annular furnace is 1 minute, the annular furnace charging machine loads a steel tube billet into the annular furnace every 1 minute; since the electric furnace will not produce titanium alloy tube billets before the 359th minute, the 1st to the 50th steel tube billets can be placed in a dense manner, that is, the 2nd, 3rd, ..., 49th and 50th steel tube billets are loaded into the annular furnace at the 1st minute, the 2nd minute, ..., the 48th minute and the 49th minute;

[0057] At the 50th minute, no steel tube billet is loaded into the annular furnace. From the 51st minute, the annular furnace adopts a charging method of 9 loaded and 1 empty, that is, at the 51st minute, 52nd minute, ..., 58th minute and 59th minute, the 51st, 52nd, ..., 58th and 59th steel tube billets are loaded into the annular furnace, and at the 60th minute, no steel tube billet is loaded into the annular furnace; by analogy, it is not difficult to find the charging rule of the annular furnace: that is, only at the 10Cth minute, no steel tube billet is loaded into the annular furnace (C is an integer not less than 5), and the annular furnace is charged at other times;

[0058] At the 401st minute, the 366th steel billet was loaded. After that, the annular furnace adopted a dense distribution method, that is, the annular furnace charging machine loaded a steel billet into the annular furnace every 1 minute.

[0059] Specific conditions of loading titanium alloy tube billets in electric furnace:

[0060] It is advisable to count the moment when the electric furnace starts to load the first titanium alloy tube billet as the 0th minute. Since the stepping rhythm of the electric furnace is 10 minutes and the electric furnace adopts a densely packed feeding method, the electric furnace charging machine loads a titanium alloy tube billet into the electric furnace every 10 minutes, that is, the second and third titanium alloy tube billets are loaded into the electric furnace at the 10th and 20th minutes, and so on. It is not difficult to find the charging rule of the electric furnace: that is, a titanium alloy tube billet is loaded into the electric furnace at the 10D minute (D is a non-negative integer);

[0061] Since the electric furnace has a total of 36 material positions, that is, the 36th titanium alloy tube billet is loaded at the 350th minute. In view of the relatively small production volume of titanium alloy tubes, only one furnace of titanium alloy tube billets is loaded each time.

[0062] Specific conditions of steel tube billets produced by ring furnace:

[0063] At the 310th minute, the first steel tube blank loaded into the rotary hearth furnace reaches its heating cycle of 310 minutes. At this time, the rotary hearth furnace discharging machine starts to discharge the first steel tube blank. At this time, switch the computer to the rolling mode of seamless steel tubes, and at the same time set the induction heating to the off state. Since 50 steel tube blanks are continuously loaded into the rotary hearth furnace, the rotary hearth furnace discharging machine starts to continuously discharge steel tube blanks until the 359th minute, that is, at the 311th minute, the 312th minute,..., the 358th minute and the 359th minute, the second, third,..., the 49th and 50th steel tube blanks start to be discharged. These 50 steel tube blanks successively go through mushroom piercing → continuous rolling → stretch reducing → straightening with temperature → cooling on the cooling bed → sizing and sawing to obtain seamless steel tube products of the required specifications.

[0064] At the 711th minute, the 366th steel tube blank loaded into the rotary hearth furnace reaches its heating cycle of 310 minutes. At this time, the rotary hearth furnace discharging machine starts to discharge the 366th steel tube blank. At this time, switch the computer to the rolling mode of seamless steel tubes, and at the same time set the induction heating to the off state. In this way, the 366th steel tube blank successively goes through mushroom piercing → continuous rolling → stretch reducing → straightening with temperature → cooling on the cooling bed → sizing and sawing to obtain seamless steel tube products of the required specifications. After that, the rotary hearth furnace discharging machine starts to continuously discharge steel tube blanks.

[0065] Specific situation of the electric furnace discharging titanium alloy tube blanks:

[0066] At the 360th minute, the first titanium alloy tube blank loaded into the electric furnace reaches its heating cycle of 360 minutes. The electric furnace discharging machine starts to discharge the first titanium alloy tube blank. At this time, switch the computer to the rolling mode of titanium alloy seamless tubes, and at the same time set the induction heating to the on state. After that, the electric furnace discharging machine discharges one titanium alloy tube blank every 10 minutes, that is, at the 370th minute and the 380th minute, the second and third titanium alloy tube blanks start to be discharged. These 3 titanium alloy tube blanks successively go through mushroom piercing → continuous rolling → induction online heating → stretch reducing → straightening with temperature → cooling on the cooling bed → sizing and sawing to obtain titanium alloy seamless tube products of the required specifications.

[0067] At the 710th minute, the 36th titanium alloy tube blank loaded into the electric furnace reaches its heating cycle of 360 minutes. The electric furnace discharging machine starts to discharge the 30th titanium alloy tube blank. At this time, switch the computer to the rolling mode of titanium alloy seamless tubes, and at the same time set the induction heating to the on state. In this way, the 36th titanium alloy tube blank successively goes through mushroom piercing → continuous rolling → induction online heating → stretch reducing → straightening with temperature → cooling on the cooling bed → sizing and sawing to obtain titanium alloy seamless tube products of the required specifications.

[0068] In summary, as can be seen from Embodiment 1 and Embodiment 2, based on a new process for co-production of seamless steel pipes and titanium alloy seamless pipes provided by the present invention, an electric furnace and an induction coil are added. By setting a series of technical measures such as the charging form of the heating furnace, the discharging rules of the tube billets, and the rapid switching rules of the rolling mode, the purpose of alternately rolling seamless steel pipes and titanium alloy seamless pipes can be well achieved, and the quality and dimensional accuracy of the seamless steel pipe and titanium alloy seamless pipe products have reached the expected requirements.

[0069] The embodiments described above are only used to describe the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A new process for the parallel production of seamless steel pipes and seamless titanium alloy pipes, characterized in that, The rolling process flow of seamless steel pipes is briefly described as: billet heating → mushroom piercing → continuous rolling → stretch reducing → hot straightening → cooling on cooling bed → sizing sawing; the corresponding station process flow of seamless steel pipes is: rotary hearth furnace → mushroom piercing machine → continuous rolling mill → stretch reducing mill → roller straightening machine → walking beam cooling bed → discharging saw; among which: First, use a charging machine to send the steel billets after sizing sawing into the rotary hearth furnace for heating, then use a discharging machine to take out the heated steel billets from the rotary hearth furnace, then use a transfer chain to send the steel billets out of the furnace into the mushroom piercing machine for mushroom piercing, then use a chain conveyor to send the pierced steel semi-finished pipes into the continuous rolling mill for continuous rolling, then use a roller conveyor to send the rough pipes after continuous rolling into the stretch reducing mill for stretch reducing, then use a roller conveyor to send the rough pipes after stretch reducing into the roller straightening machine for hot straightening, then use a roller conveyor to send the rough pipes after hot straightening into the walking beam cooling bed for natural cooling, and finally use a roller conveyor to send the rough pipes after natural cooling into the discharging saw for sizing sawing, so as to obtain the finished seamless steel pipes of the required specifications; The rolling process flow of titanium alloy seamless pipes is briefly described as: billet heating → mushroom piercing → continuous rolling → induction in-line heating → stretch reducing → hot straightening → cooling on cooling bed → sizing sawing; the corresponding station process flow of titanium alloy seamless pipes is: electric furnace → mushroom piercing machine → continuous rolling mill → induction coil → stretch reducing mill → roller straightening machine → walking beam cooling bed → discharging saw; among which: First, use a charging machine to send the titanium alloy billets after sizing sawing into the electric furnace for heating, then use a discharging machine to take out the heated titanium alloy billets from the electric furnace, then use a transfer chain to send the titanium alloy billets out of the furnace into the mushroom piercing machine for mushroom piercing, then use a chain conveyor to send the pierced titanium alloy semi-finished pipes into the continuous rolling mill for continuous rolling, then use a roller conveyor to send the rough titanium alloy pipes after continuous rolling into the induction coil for in-line heating, then use a roller conveyor to send the rough titanium alloy pipes after induction in-line heating into the stretch reducing mill for stretch reducing, then use a roller conveyor to send the rough titanium alloy pipes after stretch reducing into the roller straightening machine for hot straightening, then use a roller conveyor to send the rough titanium alloy pipes after hot straightening into the walking beam cooling bed for natural cooling, and finally use a roller conveyor to send the rough titanium alloy pipes after natural cooling into the discharging saw for sizing sawing, so as to obtain the finished titanium alloy seamless pipes of the required specifications.

2. The new process for the co-production of seamless steel pipes and seamless titanium alloy pipes according to claim 1, characterized in that, The prerequisite for the co-line rolling production of seamless steel pipes and titanium alloy seamless pipes: the specifications of the steel billets are exactly the same as those of the titanium alloy billets, and the specifications of the seamless steel pipes are also exactly the same as those of the titanium alloy seamless pipes.

3. The new process for co-production of seamless steel pipes and seamless titanium alloy pipes according to claim 1, characterized in that, The charging pattern of reheating furnaces for seamless steel pipes and seamless titanium alloy pipes capable of co-wire rolling production: According to the walking rhythm of the rotary hearth furnace and the electric furnace, determine the charging pattern of the rotary hearth furnace and the electric furnace. Assume that the walking rhythm of the rotary hearth furnace is M minutes and the walking rhythm of the electric furnace is N minutes. Both M and N are positive integers, and M ≤ N, that is, the billet discharging frequency of the rotary hearth furnace is faster than that of the electric furnace; utilize the empty billet position time of the rotary hearth furnace to load the titanium alloy billets into the electric furnace. Then the charging pattern of the rotary hearth furnace is to load (N - 1) and leave 1 empty, and the charging pattern of the electric furnace is to load 1 and leave (M - 1) empty.

4. The new process for the co-production of seamless steel pipes and seamless titanium alloy pipes according to claim 1, characterized in that, The billet discharging rule of seamless steel pipes and seamless titanium alloy pipes capable of co-wire rolling production: First, discharge the steel billets from the rotary hearth furnace, and then utilize the empty billet position time of the rotary hearth furnace to discharge the titanium alloy billets from the electric furnace.

5. The new process for the co-production of seamless steel pipes and seamless titanium alloy pipes according to claim 1, characterized in that, The rolling mode switching rule of seamless steel pipes and seamless titanium alloy pipes capable of co-wire rolling production: If discharging steel billets from the rotary hearth furnace, switch the computer to the rolling mode of seamless steel pipes and set the induction heating to the off state at the same time; if discharging titanium alloy billets from the electric furnace, switch the computer to the rolling mode of seamless titanium alloy pipes and set the induction heating to the on state at the same time.

6. The new process for the parallel production of seamless steel pipes and seamless titanium alloy pipes according to claim 1, characterized in that, Adopt the production mode of off-line electric furnace heating + co-wire rolling of steel and titanium, and roll seamless steel pipes and seamless titanium alloy pipes alternately.

7. The new process for the parallel production of seamless steel pipes and seamless titanium alloy pipes according to claim 6, characterized in that, When rolling seamless titanium alloy pipes, appropriately preheat the tools by means of the rolling process of seamless steel pipes to save a large amount of energy consumption. When rolling seamless steel pipes, appropriately cool the tools by means of the rolling process of seamless titanium alloy pipes. The two rely on each other.

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