Method for solving surface scabbing of prestressed PC rod

Abstract

The embodiment of the invention provides a method for solving surface scabbing of a prestressed PC (Poly Carbonate) rod, which comprises the following steps: after a square casting blank of the prestressed PC rod is output from a continuous casting machine, the square casting blank is fed into a spraying device for quenching, so that the surface temperature of the square casting blank is reduced to be below 500 DEG C; the quenched square casting blank is fed into a heating furnace to be subjected to temperature returning treatment; and the square casting blank subjected to temperature returning treatment is rolled. According to the technical scheme, the square casting blank is not naturally cooled off line like an existing cold conveying process, the square casting blank is quenched, the temperature of the square casting blank is rapidly cooled to the preset temperature, then rolling work is started through temperature returning, the whole process is conducted on line, the square casting blank does not need to be off line, and therefore production efficiency is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection technology, and in particular to a method for solving surface scarring of prestressed PC rods. Background Art

[0002] At present, the traditional production process of prestressed PC rods (i.e. steel rods for prestressed concrete) is generally divided into two production processes: hot delivery of cast billets and cold delivery. Hot delivery can effectively reduce production costs, reduce gas consumption and reduce C emissions, but the problem is that the scarring problem on the surface of the wire after rolling seriously affects the quality, and the scarring rate of the wire reaches more than 2%; the cold delivery process is that after the square billet is produced, it is first naturally cooled to below 500℃, and then heated for production. After adopting this process, the surface quality of the wire after rolling is good and there is no scar, so it has been widely adopted.

[0003] In the process of implementing the present invention, the inventors discovered that the prior art has at least the following problems:

[0004] The existing cold delivery process has a very slow natural cooling rate. Therefore, after the square billet is produced, it must be taken off the production line to cool down, and then brought back online to below 500°C for subsequent heating and rolling processes. This results in a long production cycle, low efficiency, and high production costs. Therefore, how to improve the existing process to solve the problem of surface scarring of prestressed PC bars while maintaining production efficiency is a problem that needs to be solved. Summary of the Invention

[0005] An embodiment of the present invention provides a rod production method, more specifically, a method for solving the problem of scarring on the surface of prestressed PC rods, which is used to solve the problem of scarring on the surface of prestressed PC rods without reducing production efficiency.

[0006] To achieve the above-mentioned purpose, an embodiment of the present invention provides a method for solving the problem of surface scarring of prestressed PC rods, comprising: after the square billet of the prestressed PC rod is output from the continuous casting machine, the square billet is sent to a spray device for quenching in the conveying roller area after the billet is cut, so that the surface temperature of the square billet is reduced from above 900°C, the temperature after the square billet is cut, to below 500°C; the quenched square billet is sent to a heating furnace for temperature recovery treatment; and the square billet after temperature recovery is rolled.

[0007] Furthermore, the method for solving the surface scarring of prestressed PC rods also includes: pre-setting a plurality of water nozzles in the spraying device, and arranging the plurality of water nozzles into four rows, and the four rows of row nozzles are distributed on the outside of the four sides of the square billet; when the head of the square billet is input into the spraying device, water is sprayed synchronously to the four sides of the square billet through the water nozzles.

[0008] Furthermore, the method for solving the scarring on the surface of the prestressed PC rod also includes: setting the length of the spraying device to 2000 cm; and setting the gap between two adjacent water nozzles in the same row to 300 cm.

[0009] Furthermore, during the quenching process, the total water spray intensity is controlled at 60±5m 3 / h.

[0010] Furthermore, during the quenching process, the conveying speed of the square billet is reduced to the same as the billet drawing speed.

[0011] Furthermore, the temperature of the square billet is controlled at 700°C-800°C through a temperature recovery treatment.

[0012] Furthermore, the specifications of the square billet are 165 cm×165 cm.

[0013] Furthermore, after detecting that the square billet has completely passed through the quenching device, the square billet is accelerated to be sent out.

[0014] Furthermore, after it is detected that the square billet has completely passed through the quenching device, it is accelerated and sent into the heating furnace through the hot delivery roller.

[0015] The above technical solution has the following beneficial effects:

[0016] With this technical solution, instead of requiring the square billets to cool naturally off the production line as in the existing cold delivery process, the hot billets pulled from the continuous casting machine are quenched using a spray device. After cooling to a predetermined temperature, they are then sent to a heating furnace for reheating before being sent to the rolling mill for rolling. The entire process is carried out online, eliminating the need to remove the square billets from the production line as in the existing technology. This significantly shortens production time, improves work efficiency, and reduces production costs. Actual measurements have shown that this method's production efficiency is comparable to that of the original billet hot delivery process. Furthermore, the scarring rate of prestressed PC rods after rolling is reduced from 2% to 0.1%, avoiding post-rolling defect losses. Therefore, this technical solution achieves both high efficiency and good surface quality.

[0017] In addition, this technical solution also has the following characteristics:

[0018] In the cold delivery process of the existing technology, the square billet can be cooled to below 500°C as required. However, after going online again and other operations, its actual temperature is far below 500°C when it is actually heated again, so more heat energy is required to be consumed. After adopting the method of the present application, since the square billet is always online, it can be immediately transported to the heating furnace for warming up after quenching is completed. The heat loss in the intermediate links is small, and thus the fuel consumed in the warming up process is also less, thereby reducing production costs and reducing carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a flow chart of a method for solving surface scarring of prestressed PC rods according to an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the quenching process in an embodiment of the present invention (axial angle);

[0022] Figure 3 Schematic diagram of the quenching process in an embodiment of the present invention (side angle). DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] like Figure 1 As shown, an embodiment of the present invention provides a method for solving surface scarring of prestressed PC rods, comprising:

[0025] S101, after the square cast billet of the prestressed PC rod is output from the continuous casting machine, the square cast billet is sent to a spray device in the conveying roller area after the billet is cut for quenching, so that the surface temperature of the square cast billet is reduced from the post-cutting temperature of 900° C. to below 500° C.;

[0026] S102, sending the quenched square billet into a heating furnace for temperature recovery treatment;

[0027] S103, rolling the square cast billet after the temperature recovery treatment.

[0028] To solve the aforementioned problem, in this technical solution, unlike the existing cold delivery process, the square billets are no longer taken offline for natural cooling. Instead, after the square billets come out of the continuous casting machine, they are directly sent to the spray device for quenching, thereby achieving the purpose of rapid cooling. Afterwards, in order to eliminate the adverse effects that the quenching process may have on the square billets, the quenched square billets are subjected to a temperature recovery treatment to eliminate defects, and then they can be sent to the rolling mill for rolling. In this process, the square billets do not need to be taken offline, but are always circulated online, and the quenching method greatly increases the cooling speed compared to the conventional method. Therefore, this solution can effectively improve production efficiency, and essentially still maintains the "cold delivery" method, thereby avoiding the problem of scarring on the wire surface after the billets are rolled.

[0029] Furthermore, the step S101 specifically includes:

[0030] A plurality of water nozzles are pre-installed in the spraying device and arranged in four rows, with the four rows of nozzles distributed on the outer sides of the four sides of the square billet;

[0031] When the head of the square billet is fed into the spraying device, water is sprayed synchronously to the four sides of the square billet through the water nozzles.

[0032] This method can evenly distribute water on the surface of the square billet to the greatest extent, thereby achieving uniform cooling of the surface of the square billet.

[0033] Further, the method for solving the surface scarring of prestressed PC rods also includes:

[0034] The length of the spraying device is set to 2000cm, and the gap between two adjacent water nozzles in the same row is set to 300cm. At the same time, during the quenching process, the total water spray intensity should be controlled at 60±5m 3 / h.

[0035] At present, the temperature of the square billet after cutting is about 900℃. Through calculation and actual measurement, when the effective length of the spraying device is set to 2000cm and each row is set to 8 nozzles, the spraying time is 60±5m. 3 The water spraying rate of 10000 ℃ / h can meet the temperature drop requirement of 400℃, so that the temperature of the square billet can quickly reach below 500℃ after passing through the spraying device.

[0036] Furthermore, in order to ensure that the water is evenly distributed on the surface of the square billet and achieve uniform cooling, the roller speed control requirements should also be set so that the square billet passes through the quenching device slowly after cutting, and the speed is consistent with the billet drawing speed. After detecting that the square billet has completely passed through the quenching device, it is immediately accelerated and sent out. During the quenching process, the conveying speed of the square billet is reduced to the same as the billet drawing speed.

[0037] Furthermore, in order to eliminate the adverse effects that the quenching process may have on the square billet, a temperature recovery treatment process should be added afterwards. That is, after the square billet has completely passed through the spraying device, it is accelerated into the heating furnace through the hot delivery roller, and the temperature of the square billet is controlled at 700℃-800℃.

[0038] Furthermore, according to the design requirements for producing prestressed PC rods, the specifications of the square billet are controlled at 165 cm × 165 cm.

[0039] Furthermore, after detecting that the square billet has completely passed through the quenching device, the square billet is accelerated to be sent out.

[0040] Furthermore, after it is detected that the square billet has completely passed through the quenching device, it is accelerated and sent into the heating furnace through the hot delivery roller.

[0041] The specific method of the present invention is as follows:

[0042] 1. Design a set of spray devices with the ability to quickly cool the billet, and arrange them in the area of ​​the conveyor roller after the billet is cut to achieve the goal of quickly reducing the surface temperature of the billet to below 500℃ after passing through this area.

[0043] 2. Design of the length of the quenching device. The current temperature of the billet after cutting is 900℃. Through calculation and actual measurement, the temperature drop of 400℃ (or above) is met, that is, the temperature of the square billet quickly reaches below 500℃, and the length of the quenching device is 2000cm.

[0044] 3. Quenching device water volume design, through calculation and actual measurement 60m 3 / h can meet the temperature drop requirement of 400℃.

[0045] 4. Roller speed control technology: after the billet is cut, it slowly passes through the quenching device at a speed consistent with the billet drawing speed. After it is detected that the square billet has completely passed through the quenching device, it is immediately accelerated and sent out.

[0046] 5. Billet temperature return control: after the square billet has completely passed through the quenching device, it is accelerated into the heating furnace through the hot delivery roller, and the temperature entering the heating furnace is stabilized at 700-800 degrees Celsius.

[0047] In a specific embodiment, field tests show that the surface temperature of the square billet after quenching is 400-480°C, for example, 440°C. The square billet is directly heated in a heating furnace after quenching. The actual measured temperature of the square billet in the heating furnace is between 700-800°C, for example, 750°C. The surface quality of the wire rod after rolling is good, and no scar defects are observed.

[0048] The structure of the spraying device used in this embodiment is as follows: Figure 2 、 Figure 3As shown, the conveying roller 3 is used to support and convey the square billet 1. The effective length of the spraying device is set to 2000 cm (the spraying device in the figure is composed of two 100 cm segments). The water nozzles 2 are arranged in four rows. The four rows of nozzles 2 are distributed on the outside of the square billet 1 in the four directions of up, down, left and right, respectively, for cooling the four sides of the high-temperature square billet 1. The water spraying intensity of the spraying device is set at 60m 3 / h. Before approaching the spraying device, the conveying roller 3 runs rapidly at a speed of 25m / min. When the front end of the square billet 1 begins to enter the spraying device, the conveying roller 3 reduces the speed of the square billet 1 to the casting speed of the casting machine, which is about 3m / min. After the tail end of the square billet 1 also passes through the spraying device, the conveying roller 3 returns to its original speed and quickly delivers the square billet 1 at 25m / min.

[0049] In the foregoing detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that embodiments of the claimed subject matter require more features than are expressly recited in each claim. On the contrary, as reflected in the appended claims, the invention comprises less than all the features of any individual disclosed embodiment. The appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0050] The above description of the disclosed embodiments is intended to enable any person skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments presented herein but is intended to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0051] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for solving the surface scarring of prestressed PC rods, characterized in that: include: After the square cast billets of prestressed PC rods are discharged from the continuous casting machine, the square cast billets are sent to a spray device for quenching in the conveying roller area after billet cutting, so that the surface temperature of the square cast billets is reduced from the billet cutting temperature of more than 900°C to less than 500°C. The quenched square billet is sent to a heating furnace for temperature recovery treatment; The square billet after the temperature return treatment is rolled.

2. The method for solving the surface scarring of prestressed PC rods according to claim 1, characterized in that: Also includes: Pre-arrange a plurality of water nozzles in the spraying device, and arrange the plurality of water nozzles into four rows, with the four rows of nozzles distributed outside the four sides of the square billet; When the head of the square billet is transported into the spraying device, water is sprayed synchronously toward the four sides of the square billet through the water nozzles.

3. The method for solving the surface scarring of prestressed PC rods according to claim 2, characterized in that: Also includes: The length of the spraying device is set to 2000 cm; The gap between two adjacent water sprinklers in the same row is set to 300 cm.

4. The method for solving the surface scarring of prestressed PC rods according to claim 2, characterized in that: During the quenching process, the total water spray intensity is controlled at 60±5m 3 / h.

5. The method for solving the surface scarring of prestressed PC rods according to claim 1, characterized in that: During the quenching process, the transport speed of the square billet is reduced to the same as the billet drawing speed.

6. The method for solving the surface scarring of prestressed PC rods according to claim 1, characterized in that: Through the temperature recovery treatment, the temperature of the square billet is controlled at 700°C-800°C.

7. The method for solving the surface scarring of prestressed PC rods according to claim 1, characterized in that: The specifications of the square billet are 165 cm×165 cm.

8. The method for solving the surface scarring of prestressed PC rods according to claim 5, characterized in that: After detecting that the square billet has completely passed through the quenching device, the square billet is sent out at an accelerated speed.

9. The method for solving the surface scarring of prestressed PC rods according to claim 5, characterized in that: After it is detected that the square billet has completely passed through the quenching device, it is accelerated into the heating furnace through the hot delivery roller.

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