Cold shrinkage-free control method for bar production

Abstract

The invention discloses a cold shrinkage-free control method for bar production, which relates to the technical field of bar production process, and comprises the following steps of: rolling a steel billet into a bar with a corresponding finished product size through a rolling area, cooling the bar on a cooling bed after the bar is taken out of a rolling mill, and controlling the temperature of the bar taken out of the cooling bed to be t1, t2 and t3; the bars taken out of the cooling bed are put into a storage position frame to be further cooled, the target cooling temperature is set to be t2, the required cooling time of the bars from t1 to t2 is Tn, the storage position frame comprises x storage positions, and the bars are sequentially put into the storage positions to be cooled, and then the bars on all the storage positions are sequentially fed into a cold shearing machine to be sheared according to the first-in and second-out sequence, the production takt of the cold shearing machine is T, and x is not smaller than Tn / T. The problem of cost caused by non-uniform cold contraction of the bar due to temperature difference can be solved, and the effects of not influencing the production rhythm and improving the yield are achieved.

Description

Technical Field

[0001] This invention relates to the field of bar production technology, and in particular to a method for controlling cold shrinkage in bar production. Background Technology

[0002] The newly constructed bar production line has significantly improved overall speed and continuity. After the steel billets are rolled into bars of the corresponding finished size from the rolling area, they need to be sheared by a cold shear machine to form the fixed length required by the customer, such as 9m or 12m for bulk commodities. After leaving the rolling mill, the bars need to be cooled and stored on the cooling bed, and then transported to the cold shear machine roller conveyor via a flat support device for shearing. Because the finished bars enter the cooling bed at different times and move on the cooling bed at the same time, there is a large temperature difference between the two sides, resulting in different shrinkage lengths after cooling. However, for the customer, the finished product can only be longer, not shorter. Therefore, the cold shear machine needs to shear with a large allowance, which brings significant losses to the company. Roughly calculated, the yield will be reduced by about 0.1% due to the different shrinkage. In the actual rolling process, the surface temperature of the roller table is about 280°C. If we wait for further cooling before shearing, it will significantly affect the production cycle and be counterproductive. Therefore, there is an urgent need for a systematic equipment that can improve the yield rate without affecting the production rhythm. Summary of the Invention

[0003] The purpose of this invention is to provide a method for controlling cold shrinkage in bar production. By trading space for time, this method can solve the cost problem caused by uneven cold shrinkage of bars due to temperature differences, without affecting the production rhythm and improving the yield.

[0004] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A method for controlling cold shrinkage in bar production includes the following steps: The steel billet is rolled into bars of the corresponding finished size through the rolling zone. After exiting the rolling mill, the bars are cooled on a cooling bed. The temperature of the bars exiting the cooling bed is t1. After exiting the cooling bed, the bar stock is placed in a storage rack for further cooling. The target cooling temperature is set as t2, and the cooling time T required for the bar stock to cool from t1 to t2 is calculated. n The storage rack includes x storage positions, and the bars are sequentially placed into each storage position for cooling. The bars from each storage location are then fed into the cold shear machine in the order of first-in, first-out for shearing. The production cycle of the cold shear machine is T, and x is not less than T. n / T.

[0005] Furthermore, x is T n / T is the integer value.

[0006] Furthermore, t2 is no greater than 130 degrees Celsius.

[0007] Furthermore, t2 is taken as 100 degrees Celsius.

[0008] Furthermore, T n Take for 15 to 25 minutes.

[0009] Furthermore, the storage rack sequentially includes a first storage space, a second storage space, ..., an xth storage space. When the bar is placed into the storage rack, The first batch of bars is placed in the first storage location, the second batch of bars is placed in the second storage location, and so on, until the xth batch of bars is placed in the xth storage location. Then, the bars in the first storage position are sent into the cold shearing machine, and at the same time, the (x+1)th batch of bars is placed into the first storage position. The bars in the second storage position are sent into the cold shearing machine, and at the same time, the (x+2)th batch of bars is placed into the second storage position... and so on for continuous production.

[0010] Furthermore, the number of bars in the storage location is no greater than the maximum number of bars that the cold shear machine can cut simultaneously.

[0011] Furthermore, the bars are laid out in each storage position, and the bars are placed into the storage position or sent from the storage position to the cold shear machine by a lifting magnetic flat support. The number of bars in the storage position is no greater than the number of bars that the lifting magnetic flat support can transport at the same time.

[0012] Furthermore, the spacing between adjacent storage bits is not less than 1m.

[0013] Furthermore, the storage space includes several parallel steel sections with a spacing of 1.5m between them.

[0014] In summary, the present invention has the following beneficial effects: Considering the heat resistance, load-bearing capacity, and adaptability to the production rhythm of the equipment, this application solves the problem of increased costs caused by uneven cooling and shrinkage of the bars due to temperature differences by setting up a storage rack on one side of the cooling bed outlet. The bars exiting the cooling bed are moved to the storage rack by horizontal sliding and flat support, and the "first-in, first-out" queue management is used. This does not affect the production rhythm. Because there is a storage space, the risk of the entire line being shut down due to equipment failure is greatly reduced. Attached Figure Description

[0015] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1This is a diagram illustrating the principle of determining the target temperature t2 in a method for controlling cold shrinkage in bar production according to the present invention. Figure 2 The cooling time T in the bar production non-shrinkage control method of the present invention is... n The principle of determination is shown in the table and diagram; Figure 3 This is a schematic diagram of the storage rack structure in a bar production method for controlling cold shrinkage according to the present invention. Detailed Implementation

[0017] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. These embodiments do not constitute a limitation of the present invention. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this application.

[0018] A method for controlling cold shrinkage in bar production includes the following steps: In step S10, the steel billet is rolled into bars of the corresponding finished size through the rolling zone. After exiting the rolling mill, the bars are cooled on a cooling bed. The temperature of the bars exiting the cooling bed is t1. In this embodiment, taking the production line for producing 25mm threaded bars as an example, the bar temperature t1 at the cooling bed is about 300℃. The cold shearing capacity of this production line is 1300T, which can simultaneously shear 50 bars. The overall length of the cooling bed is 135m, and the normal multiple length is 120m (135m is a redundant design). The time for each cut by the cold shearing machine is about 25s / cut. Assuming that a fixed length of 12m is produced, it requires 10 cuts, and the production cycle is 250s.

[0019] Step S20: Place the bar stock after cooling on the cooling bed into the storage rack for further cooling. Set the target cooling temperature as t2, and the cooling time T required for the bar stock to cool from t1 to t2. n The storage rack includes x storage positions, and the bars are sequentially placed into each storage position for cooling. Since all subsequent equipment parameter settings are based on cooling time, the first step is to study the cooling shrinkage time of the corresponding product to obtain the target temperature for bar cooling; for example... Figure 1 As shown, the contraction exhibits an exponential distribution with respect to temperature, with t2 not exceeding 130 degrees Celsius. For example, in this embodiment, according to... Figure 1 The optimal temperature for t2 is 100 degrees Celsius. When the finished product is cooled to around 100 degrees Celsius, the shrinkage after cooling is almost negligible.

[0020] Taking the summer cooling cycle as an example, such as Figure 2 As shown, the temperature exhibits a similar exponential distribution as time increases, T n It can be taken for 15 to 25 minutes; (Comprehensive) Figure 1 and Figure 2After 15 minutes, the cooling rate decreases. If a 20-minute cooling time is provided, the shrinkage can be reduced from 1.47 cm to 0.11 cm. Assuming a fixed length of 9 m, the yield can be increased by (1.47 - 0.11) cm / 9 m = 0.124%. Therefore, in this embodiment, when t2 = 104 degrees Celsius, the corresponding T... n =20min, after cooling for 20 minutes, the overall shrinkage is almost 0, which is about 100 degrees Celsius.

[0021] Step S30: The bars in each storage position are sequentially fed into the cold shear machine for shearing in the order of first-in, first-out. The production cycle of the cold shear machine is T, and x is not less than T. n / T, in this embodiment, x is T n / T is the integer value.

[0022] Among them, such as Figure 3 As shown, the storage rack includes, in sequence, the first storage space, the second storage space, ... the xth storage space. When the bar is placed into the storage rack, The first batch of bars is placed in the first storage location, the second batch of bars is placed in the second storage location, and so on, until the xth batch of bars is placed in the xth storage location. Then, the bars in the first storage position are sent into the cold shearing machine, and at the same time, the (x+1)th batch of bars is placed into the first storage position. The bars in the second storage position are sent into the cold shearing machine, and at the same time, the (x+2)th batch of bars is placed into the second storage position... and so on for continuous production.

[0023] In this embodiment, it is confirmed that the required cooling time T is determined in step S20. n After a storage time of 20 minutes, the production cycle time for each batch of products on the cold shear machine is T=250s. x≥20min / T=4.8, which means that to ensure smooth production, 4.8 times the storage capacity is required. Rounding up, this means that the storage capacity required is the same as that required for 5 batches of products. The weight of one batch of rebar is 3.85kg / m * 50 pieces * 120m = 2.31 tons for 25mm specification. For 5 batches, it is 11.55 tons. The number of bars in each storage position shall not exceed the maximum number of bars that the cold shear machine can cut at the same time (50 bars). The bars are laid on each storage position and are placed into or sent from the storage position to the cold shear machine by a lifting magnetic flat support. Therefore, it is also necessary to set the number of bars in the storage position to not exceed the number of bars that the lifting magnetic flat support can transport at the same time, that is, to meet the weight of one strand of rebar.

[0024] like Figure 3 As shown, in this embodiment, the distance between adjacent storage positions is not less than 1m (each trailer is 1.8m wide and the distance between them is 1m); the storage position includes several parallel H-beams for load bearing, the spacing between the H-beams is 1.5m (suitable for both 9m and 12m), and the surface is covered with refractory castable. During production, after the first flat rack reaches the exit roller conveyor of the cooling bed, the magnetic flat rack picks it up (and places it in storage position 1). After the second flat rack reaches the exit of the cooling bed, the magnetic flat rack picks it up (and places it in storage position 2)... until it is placed in storage position 5. When the cooling bed is ready to send the sixth flat rack off the line, the magnetic flat rack starts to put the bar stock in storage position 1 into the roller conveyor before the sixth flat rack, and sends it into the cold shear machine for shearing. Then, after the sixth flat rack is on the roller conveyor, it is picked up again and placed into the first flat rack. Then the bar stock in the second flat rack is picked up, placed into the roller conveyor, and sent into the cold shear machine for shearing. Then the bar stock that has come off the cooling bed is transported to the second flat rack... This process is repeated to form continuous production, which not only meets the requirements of continuous production, but also greatly reduces cold shrinkage, improves the yield and the company's operating income.

[0025] In summary, this invention patent allows for specific designs tailored to different process conditions, fulfilling the advantages claimed in the patent. The procedure in step S30 involves the speed and logic of the flat-lift movement in each step, which is easily implemented using current electrical systems (a simple positioning problem, not detailed further). The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within the scope of its essence and protection. Such modifications or equivalent substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A method for controlling cold shrinkage in bar production, characterized in that: Includes the following steps, The steel billet is rolled into bars of the corresponding finished size through the rolling zone. After exiting the rolling mill, the bars are cooled on a cooling bed. The temperature of the bars exiting the cooling bed is t1. After exiting the cooling bed, the bar stock is placed in a storage rack for further cooling. The target cooling temperature is set as t2, and the cooling time T required for the bar stock to cool from t1 to t2 is calculated. n The storage rack includes x storage positions, and the bars are sequentially placed into each storage position for cooling. The bars from each storage location are then fed into the cold shear machine in the order of first-in, first-out for shearing. The production cycle of the cold shear machine is T, and x is not less than T. n / T.

2. The method for controlling cold shrinkage in bar production according to claim 1, characterized in that: x is T n / T is the integer value.

3. The method for controlling cold shrinkage in bar production according to claim 1, characterized in that: t2 is not greater than 130 degrees Celsius.

4. The method for controlling cold shrinkage in bar production according to claim 3, characterized in that: t2 is set to 100 degrees Celsius.

5. A method for controlling cold shrinkage in bar production according to claim 1 or 3, characterized in that: T n Take for 15 to 25 minutes.

6. The method for controlling cold shrinkage in bar production according to claim 1, characterized in that: The storage rack sequentially includes a first storage space, a second storage space, ..., the xth storage space. When the bar is placed into the storage rack... The first batch of bars is placed in the first storage location, the second batch of bars is placed in the second storage location, and so on, until the xth batch of bars is placed in the xth storage location. Then, the bars in the first storage position are sent into the cold shearing machine, and at the same time, the (x+1)th batch of bars is placed into the first storage position. The bars in the second storage position are sent into the cold shearing machine, and at the same time, the (x+2)th batch of bars is placed into the second storage position... and so on for continuous production.

7. A method for controlling cold shrinkage in bar production according to claim 1 or 6, characterized in that: The number of bars in the storage location is no greater than the maximum number of bars that the cold shear machine can cut simultaneously.

8. The method for controlling cold shrinkage in bar production according to claim 1, characterized in that: The bars are laid out in each storage position, and are placed into or sent from the storage position to the cold shearing machine by a lifting magnetic flat support. The number of bars in the storage position is not greater than the number of bars that the lifting magnetic flat support can transport at the same time.

9. The method for controlling cold shrinkage in bar production according to claim 1, characterized in that: The distance between adjacent storage bits is not less than 1m.

10. A method for controlling cold shrinkage in bar production according to claim 1 or 9, characterized in that: The storage space consists of several parallel steel sections, with a spacing of 1.5m between them.

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