Method of adjusting a perforating roller after wear

Abstract

The application provides a method for adjusting the wear of a piercing roll, comprising the following steps: step S1, pre-adjustment, selecting the top front reduction rate according to the pipe blank diameter and the steel type, selecting the top head according to the pipe specification, and obtaining the adjustment parameters by using the adjustment calculation formula, wherein the adjustment parameters comprise the top head diameter, the roll gap, the top head penetration amount and the guide distance; step S2, initial adjustment; step S3, fine adjustment; measuring the actual roll gap corresponding to the top head tip, comparing the actual roll gap with the theoretical roll gap corresponding to the top head tip, obtaining the roll wear amount corresponding to the top head tip, compensating the roll gap for the wear amount, and reducing the roll gap by half of the roll wear amount. Since the wear amount of the roll is different at different positions of the top head tip, the ideal actual top front reduction rate value and the piercing wall thickness value are unchanged through the cooperation of the series of top front reduction rate increasing methods of the pre-adjustment, the initial adjustment and the fine adjustment.

Description

Technical Field

[0001] This invention relates to tube rolling processes, and particularly to a method for adjusting worn piercing rolls. Background Technology

[0002] Piercing the billet is the most crucial deformation process in the production of hot-rolled seamless steel pipes. Its task is to pierce the solid billet into a hollow tube. The inner surface quality of the hollow tube, i.e., the internal folding condition and the uniformity of wall thickness, determines the inner surface quality, i.e., the internal folding condition and the uniformity of wall thickness of the finished product. Subsequent rolling and diameter reduction deformation processes cannot improve the inner surface quality (i.e., the internal folding condition) of the pierced billet, and have only a slight improvement on the uniformity of wall thickness. The quality of hot-rolled seamless steel pipes mainly depends on the uniformity of wall thickness and the inner surface quality (i.e., the internal folding condition). Therefore, the piercing of the billet determines the quality of hot-rolled seamless steel pipes.

[0003] Drilling adjustment is crucial. With a fixed tool shape, the length of the deformation zone varies with different adjustment parameters. For example, moving the mandrel forward reduces the piercing preparation area; decreasing the roll distance lengthens the entire deformation zone; and increasing the guide plate distance increases the lateral deformation of the metal.

[0004] The pre-aperture reduction ratio is the most important and critical parameter in piercing adjustment. An excessively high pre-aperture reduction ratio can cause premature cavity formation, resulting in inward bending. Simultaneously, an excessively high pre-aperture reduction ratio, with the mandrel passing too far ahead, leads to instability in the rolling process near the end of piercing, resulting in uneven wall thickness at the rear end. An excessively low pre-aperture reduction ratio, failing to meet the minimum pre-aperture reduction ratio required for secondary biting during piercing, will prevent piercing from being achieved or may cause jamming. Furthermore, an excessively low pre-aperture reduction ratio, with the mandrel passing too far ahead, results in an insufficient funnel-shaped effect at the billet head, causing the mandrel to misalign with the billet center and resulting in uneven wall thickness at the rear end.

[0005] Because there is a lack of scientific theoretical guidance for adjusting the top pressure reduction rate after the piercing roller wears, the top pressure reduction rate is often too high or too low, affecting product quality and process smoothness. In order to ensure that the top pressure reduction rate remains stable after the piercing roller wears, we have creatively proposed an adjustment method for the piercing roller after wear. Summary of the Invention

[0006] The purpose of this invention is to provide a method for adjusting a worn perforated roller, thereby improving the ability of adjusting the roller after wear to ensure product quality and smooth process operation.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for adjusting a worn perforated roller includes the following steps:

[0009] Step S1, Pre-adjustment

[0010] The pre-compression reduction rate is selected based on the billet diameter and steel grade, and the mandrel is selected based on the tube specifications. The shunting parameters are obtained using the shunting calculation formula, which includes the mandrel diameter, roll gap, mandrel extension, and guide distance.

[0011] Step S2, Initial Adjustment

[0012] The actual roll gap corresponding to the mandrel tip is measured and compared with the theoretical roll gap to obtain the roll wear amount corresponding to the mandrel tip. The roll gap is then compensated for the wear amount by reducing it by half of the roll wear amount. The other half of the roll wear amount is used to calculate the mandrel extension amount using the mandrel extension calculation formula, and the guide distance is calculated using the guide distance calculation formula.

[0013] Step S3, fine-tuning

[0014] The actual roll gap corresponding to the mandrel tip is measured and compared with the theoretical roll gap corresponding to the mandrel tip to obtain the roll wear amount corresponding to the mandrel tip. The roll gap is then compensated for the wear amount by reducing the roll gap by half of the roll wear amount. The other half of the roll wear amount is calculated by the mandrel extension amount using the mandrel extension amount calculation formula and the guide distance is calculated using the guide distance calculation formula. At the same time, the roll wear amount corresponding to the mandrel tip after fine adjustment is checked.

[0015] In the above-mentioned adjustment method for worn perforated rollers, selecting the mandrel according to the capillary tube specification refers to selecting the mandrel diameter Dt, where Dt = dm - Dm / (5 * (δm)). 1 / 2 ), where dm is the inner diameter of the capillary tube, Dm is the outer diameter of the capillary tube, and δm is the wall thickness of the capillary tube.

[0016] In the above-mentioned adjustment method after the wear of the piercing roll, the pre-top reduction ratio ε is selected according to the billet diameter and steel grade. The pre-top reduction ratio is the percentage of the diameter reduction of the billet when it contacts the mandrel to the diameter of the billet. The selected pre-top reduction ratio should be less than the critical reduction ratio of the steel grade and greater than the minimum pre-top reduction ratio required for bite-in. The pre-top reduction ratio is 4% to 8%.

[0017] In the above-mentioned adjustment method after the wear of the piercing roller, the selected top pre-reduction rate for carbon steel and general alloy steel, ∮155-270 billet is 6-8%.

[0018] In the above-mentioned adjustment method after the wear of the piercing roll, the top pre-pressing rate of carbon steel and general alloy steel, ∮155-270 billet is further selected to be 7%.

[0019] In the above-mentioned adjustment method after the piercing roller wears, the selected top pre-reduction rate for high alloy steel, ∮155-270 billet is 5-7%.

[0020] In the above-mentioned adjustment method for worn perforated rollers, the shunting calculation formula in step S1 is as follows:

[0021] B=(1-ε)*Dp*tanβ2 / (tanβ1+tanβ2)+(Dt+2δm)*tanβ1 / (tanβ1+tanβ2)-2Lt*tanβ1*tanβ2 / (tanβ1+tanβ2)

[0022] C=Lt-(Dt+2δm-B) / 2tanβ2

[0023] Y = Lt - C

[0024] A=(2Dm / (Dt+2δm)-1)*B

[0025] Wherein, Dp is the billet diameter, δm is the capillary wall thickness, β1 is the roll inlet cone angle, β2 is the roll outlet cone angle, Dt is the mandrel diameter, Lt is the mandrel length, B is the roll gap, C is the mandrel extension, Y is the mandrel position, A is the guide distance, and Dm is the capillary outer diameter.

[0026] In the above-mentioned adjustment method for worn perforated rollers, the calculation formulas for top extension and guide distance in step S2 are as follows:

[0027] C=Lt-(Dt+2δm-B) / 2tanβ2A=(2Dm / (Dt+2δm)-1)*B

[0028] Wherein, C is the mandrel extension, Lt is the mandrel length, Dt is the mandrel diameter, δm is the capillary tube wall thickness, B is the roll gap, β2 is the roll exit cone angle, A is the guide distance, and Dm is the capillary tube outer diameter.

[0029] In the above-mentioned adjustment method for worn perforated rollers, the calculation formulas for top extension and guide distance in step S3 are as follows:

[0030] C=Lt-(Dt+2δm-B) / 2tanβ2A=(2Dm / (Dt+2δm)-1)*B

[0031] Wherein, C is the mandrel extension, Lt is the mandrel length, Dt is the mandrel diameter, δm is the capillary tube wall thickness, B is the roll gap, β2 is the roll exit cone angle, A is the guide distance, and Dm is the capillary tube outer diameter.

[0032] In the above-mentioned adjustment method for worn perforated rollers, in step S3, if the wear amount measured before and after adjustment is the same, the adjustment is completed. If the wear amount measured before and after adjustment is different, step S3 needs to be repeated once to fine-tune until the wear amount measured before and after adjustment is the same, and then the adjustment is completed.

[0033] Analysis reveals that this invention discloses a method for adjusting a worn piercing roll. It measures the roll gap corresponding to the mandrel tip, obtains the wear amount of the roll at the mandrel tip, compensates for the roll gap, and ensures that the wall thickness and outer diameter of the tube remain unchanged, guaranteeing the actual required value for the pre-mandrel reduction rate. This method scientifically compensates for wear by adjusting the roll gap, avoiding the problem of an excessively high or low actual pre-mandrel reduction rate caused by experience-based adjustments based on bite conditions during actual operation, which could affect product quality and process smoothness. This achieves the goal of ensuring that the actual pre-mandrel reduction rate after piercing roll wear is the same as that of a new piercing roll, improving the ability of adjusting the piercing roll after wear to guarantee product quality and process smoothness. Attached Figure Description

[0034] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0035] Figure 1 This is a schematic diagram of the perforation deformation zone. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. Indeed, those skilled in the art will recognize that modifications and variations can be made to the invention without departing from its scope or spirit. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the invention encompass such modifications and variations falling within the scope of the appended claims and their equivalents.

[0037] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected," "linked," and "set up" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a direct connection or an indirect connection through intermediate components; a wired connection, a radio connection, or a wireless communication signal connection. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0038] The accompanying drawings illustrate one or more examples of the invention. The detailed description uses numerals and letters to refer to features in the drawings. Similar or analogous reference numerals in the drawings and description have been used to refer to similar or analogous parts of the invention. As used herein, the terms “first,” “second,” and “third,” etc., are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of individual components.

[0039] like Figure 1 As shown in the embodiment of the present invention, a method for adjusting a worn perforated roller is provided, comprising the following steps:

[0040] Step S1, Pre-adjustment

[0041] The pre-top reduction rate is selected based on the billet diameter and steel grade, and the mandrel is selected based on the tube specifications. The shunting parameters are obtained using the shunting calculation formula, which includes the mandrel diameter, roll gap, mandrel extension, and guide distance.

[0042] Selecting the mandrel according to the capillary tube specification refers to selecting the mandrel diameter Dt.

[0043] Dt=dm-Dm / (5*(δm) 1 / 2 ),

[0044] Wherein, dm is the inner diameter of the capillary tube, Dm is the outer diameter of the capillary tube, and δm is the wall thickness of the capillary tube.

[0045] The pre-top reduction ratio ε, determined based on the billet diameter and steel grade, refers to...

[0046] The pre-pin reduction ratio is the percentage of the diameter reduction of the billet when it contacts the mandrel to the diameter of the billet. The selected pre-pin reduction ratio should be less than the critical reduction ratio of the steel grade and greater than the minimum pre-pin reduction ratio required for bite-in. The pre-pin reduction ratio is generally 4% to 8%.

[0047] The pre-top reduction ratio of the new piercing roll is selected based on the billet, material, mill characteristics, and empirical data. For carbon steel and general alloy steel, 4-8% and 6-8% are optimal, respectively; for high alloy steel and stainless steel, 5-7% is recommended. After a period of use, the bite cone of the piercing roll wears down, often making secondary bite difficult. Adjustments are made based on the bite situation and experience to reduce the roll gap and retract the mandrel.

[0048] For high-alloy steel, smaller values ​​are used; for carbon steel and general alloy steel, larger values ​​are used. For carbon steel and general alloy steel, the selected pre-top reduction rate for ∮155-270 billets is 6-8%, preferably 7%. For high-alloy steel, the selected pre-top reduction rate for ∮155-270 billets is 5-7%, preferably 6%.

[0049] In step S1, the shunting calculation formula is as follows:

[0050] B=(1-ε)*Dp*tanβ2 / (tanβ1+tanβ2)+(Dt+2δm)*tanβ1 / (tanβ1+tanβ2)-2Lt*tanβ1*tanβ2 / (tanβ1+tanβ2)

[0051] C=Lt-(Dt+2δm-B) / 2tanβ2

[0052] Y = Lt - C

[0053] A=(2Dm / (Dt+2δm)-1)*B

[0054] Wherein, Dp is the billet diameter, δm is the capillary wall thickness, β1 is the roll inlet cone angle, β2 is the roll outlet cone angle, Dt is the mandrel diameter, Lt is the mandrel length, B is the roll gap, C is the mandrel extension, Y is the mandrel position, A is the guide distance, and Dm is the capillary outer diameter.

[0055] The positions represented by the letter codes in the formulas for calculating jacking extension, guide distance, and shunting can be found in [reference needed]. Figure 1 Schematic diagram of the perforation deformation zone.

[0056] Step S2, Initial Adjustment

[0057] The actual roll gap corresponding to the mandrel tip is measured and compared with the theoretical roll gap to obtain the roll wear amount corresponding to the mandrel tip. The roll gap is then compensated for the wear amount by reducing the roll gap by half of the roll wear amount.

[0058] The other half of the roll wear is calculated by determining the mandrel extension amount using the mandrel extension calculation formula, and the guide distance is calculated using the guide distance calculation formula.

[0059] In step S2, the formulas for calculating the top extension and guide distance are as follows:

[0060] C=Lt-(Dt+2δm-B) / 2tanβ2A=(2Dm / (Dt+2δm)-1)*B

[0061] Wherein, C is the mandrel extension, Lt is the mandrel length, Dt is the mandrel diameter, δm is the capillary tube wall thickness, B is the roll gap, β2 is the roll exit cone angle, A is the guide distance, and Dm is the capillary tube outer diameter.

[0062] That is, the theoretical roll gap minus 0.5 wear amount is the adjusted actual roll gap. Since the roll gap has changed, the data of the mandrel extension and guide distance calculated by the formula for mandrel extension and guide distance have also changed.

[0063] Step S3, fine-tuning

[0064] The actual roll gap corresponding to the mandrel tip is measured and compared with the theoretical roll gap to obtain the roll wear amount corresponding to the mandrel tip. The roll gap is then compensated for the wear amount by reducing the roll gap by half of the roll wear amount.

[0065] The other half of the roll wear is calculated by determining the mandrel extension amount using the mandrel extension calculation formula, and the guide distance is calculated using the guide distance calculation formula.

[0066] Simultaneously, the wear amount of the roll corresponding to the mandrel tip was checked after fine-tuning. The wear amount measured before and after adjustment was different, requiring re-entry of the roll wear amount for final adjustment. Once the wear amount measured before and after adjustment were the same, the adjustment was complete.

[0067] In step S3, the formulas for calculating the top extension and guide distance are as follows:

[0068] C=Lt-(Dt+2δm-B) / 2tanβ2A=(2Dm / (Dt+2δm)-1)*B

[0069] Wherein, C is the mandrel extension, Lt is the mandrel length, Dt is the mandrel diameter, δm is the capillary tube wall thickness, B is the roll gap, β2 is the roll exit cone angle, A is the guide distance, and Dm is the capillary tube outer diameter.

[0070] That is, the theoretical roll gap minus 0.5 wear amount is the adjusted actual roll gap. Since the roll gap has changed, the data of the mandrel extension and guide distance calculated by the formula for mandrel extension and guide distance have also changed.

[0071] In step S3, if the wear measured before and after adjustment are the same, the adjustment is complete. If the wear measured before and after adjustment are different, step S3 needs to be repeated once more for fine-tuning until the wear measured before and after adjustment are the same. Multiple wear measurements should be taken, and multiple fine-tuning adjustments should be made to the top compression rate. Typically, 1-2 fine-tuning operations are sufficient to complete the adjustment.

[0072] Because the wear of the rolls is not uniform, the wear is greater at the beginning and slightly less at the end. The initial adjustment in step S2 is based on the preset wear amount (e.g., 3mm), and the fine adjustment in step S3 is based on the initial wear amount (e.g., 2mm). The subsequent wear amounts may be 2.5mm or 2mm. If it is 2.5mm, further adjustment is needed, but if it is 2mm, no adjustment is needed.

[0073] The adjustment content and calculation formulas in step S2 (initial adjustment) and step S3 (fine adjustment) are the same. However, the wear amount at the adjusted position may differ from the wear amount at the original position. Therefore, further adjustment is needed after step S2 (initial adjustment). Hence, step S3 (fine adjustment) is set up. Subsequent adjustments will gradually approach the actual wear amount after adjustment. Once the wear amount is the same, the adjustment is complete. This is because the adjustment at the top is less frequent in later steps, and eventually, the wear amount becomes the same as the original position.

[0074] The purpose of this invention is to overcome the technical shortcomings of existing methods for adjusting worn perforated rollers in terms of theoretical calculation, and to achieve a controllable adjustment method for worn perforated rollers. This method for adjusting worn perforated rollers is suitable for adjusting perforated rollers when the perforating cones have experienced uneven wear after a period of use, and is mainly applied to the perforation process when the wear of the perforated rollers exceeds 1mm.

[0075] The reason for measuring roll wear at different locations in the above method is that roll wear is uneven. Roll wear is greatest at the inlet bite point and decreases towards the exit. After the inlet cone, the wear curve remains uniform from the rolling zone to the exit cone. During pre-adjustment, the roll wear is greater at the mandrel tip (which is further forward). During initial adjustment, the roll wear is smaller at the mandrel tip (which is further back). During fine adjustment, the roll wear measured in the initial adjustment is compared with the fine-adjustment roll wear. If there is a discrepancy, the roll wear measurement must be re-entered for final adjustment.

[0076] Example 1

[0077] The piercing roll line has rolled 10,000 pieces (the typical service life of a piercing roll line is around 20,000 pieces). Now, using 155mm billet, 45# steel, and pierced tubes ∮158*22, piercing adjustments are being made. The specific method is as follows:

[0078] The theoretical outer diameter of the mandrel is 107. Based on the mandrel group spacing of ∮102, ∮105, and ∮108, the ∮108 mandrel is selected, and the corresponding mandrel length is 270.

[0079] Pre-adjustment: Top front reduction rate 7%, roll gap, mandrel extension, and guide distance: 134, 98, 147 respectively. Roll gap and mandrel extension are adjusted to the correct positions.

[0080] Initial adjustment: The measured roll gap at the tip of the mandrel is 148, the theoretical roll gap at the center is 144, and the wear of the center roll is 4. The reduction rate before the mandrel is 7%, and the roll gap, mandrel extension, and guide distance are 132, 78, and 145, respectively. The roll gap and mandrel extension are now in place.

[0081] Fine adjustment: The measured roll gap at the tip of the mandrel is 142, the theoretical value of the top roll gap is 140, and the wear of the top roll is 2. The reduction rate before the mandrel is 7%, and the roll gap, mandrel extension, and guide distance are 133, 88, and 146, respectively. The roll gap and mandrel extension are now in place.

[0082] The measured roll gap at the mandrel tip is 144, the theoretical roll gap at the top is 142, and the wear amount of the top roll is 2. There is no need to re-enter the roll wear amount.

[0083] Example 2

[0084] The piercing roll line has rolled 18,000 pieces (the typical service life of a piercing roll line is around 20,000 pieces). Now, using 270mm tube blanks, 45# steel, and pierced tubes ∮279*25mm, piercing adjustments are being made. The specific method is as follows:

[0085] The theoretical outer diameter of the mandrel is 218. Based on the mandrel group spacing of ∮214, ∮218, and ∮222, the ∮218 mandrel is selected, and the corresponding mandrel length is 500.

[0086] Pre-adjustment: Top front reduction rate 7%, roll gap, mandrel extension, and guide distance: 233, 169, 257 respectively. Roll gap and mandrel extension are adjusted to the correct positions.

[0087] Initial adjustment: The measured roll gap at the tip of the mandrel is 257 mm, the theoretical roll gap at the center is 251 mm, and the wear of the center roll is 6 mm. The reduction rate before the mandrel is 7%. The roll gap, mandrel extension, and guide distance are 230 mm, 141 mm, and 254 mm, respectively. The roll gap and mandrel extension are now in place.

[0088] Fine adjustment: The measured roll gap at the tip of the mandrel is 249, the theoretical value of the top roll gap is 245, and the wear of the top roll is 4. The reduction rate before the mandrel is 7%, and the roll gap, mandrel extension, and guide distance are 231, 150, and 255, respectively. The roll gap and mandrel extension are now in place.

[0089] The measured roll gap at the mandrel tip is 251, the theoretical roll gap at the top is 247, and the wear amount of the top roll is 4. No need to re-enter the roll wear amount.

[0090] This method was used to monitor the production of 30,000 tons of steel pipes. The piercing process was smooth, with no piercing process failures such as pre-piercing jamming or post-piercing jamming occurring from the biting in to the end. After finishing, the pass rate reached 100%, with no quality defects such as internal folds, and the wall thickness unevenness was within 12%S. It meets the standards and usage requirements.

[0091] Comparative Example 1

[0092] Using traditional methods, 10,000 tubes were rolled on the piercing roll line, using 155mm billet, 45# steel, and pierced tubes ∮158*22mm, and piercing adjustments were performed. The specific method is as follows:

[0093] Calculate using the shunting calculation formula.

[0094] The theoretical outer diameter of the mandrel is 107 mm. Based on the mandrel group spacing of ∮102, ∮105, and ∮108, the ∮108 mandrel is selected, with a corresponding mandrel length of 270 mm. Adjustment: Observe the biting situation and empirical values, and take a pre-mandrel reduction rate of 10%. The roll gap, mandrel extension, and guide distance are 131.6 mm, 75 mm, and 145 mm, respectively.

[0095] The piercing process proceeded smoothly, and production remained stable. After steel pipe finishing, the pass rate was 96%. The main issue was that steel grades with higher alloy content, which are more prone to internal folds (such as 42CrMo), exhibited fine, unstable internal folds on the inner surface. The uneven wall thickness at the tail end was also significant, reaching 16%S, failing to fully meet standards and customer requirements. Measurement and analysis revealed that the wear of the mandrel tip roll was 2%, and the actual pre-mandrel reduction rate of 8.7% was excessive, contributing to the internal folds and uneven wall thickness at the tail end.

[0096] Comparative Example 2

[0097] Using traditional methods, 18,000 pieces were rolled on the piercing roll line. Now, using 270mm billet, 45# steel, and pierced tubes ∮279*25mm, piercing adjustment is performed. The specific method is as follows:

[0098] The calculation is performed using the shunting calculation formula. The theoretical outer diameter of the mandrel is 218 mm. Based on the mandrel group spacing of ∮214, ∮218, and ∮222, a ∮218 mandrel is selected, corresponding to a mandrel length of 500 mm. Shunting: Observe the bite situation and empirical values, and take the pre-mandrel reduction rate as 8%. The roll gap, mandrel extension, and guide distance are 232 mm, 156 mm, and 256 mm, respectively.

[0099] The piercing process was unsuccessful, resulting in unstable production and occasional piercing process failures such as difficulty in biting and front jamming. After steel pipe finishing, the pass rate was 98%, mainly characterized by uneven front-end wall thickness, ranging from 16% to 18%. This did not fully meet standards and customer requirements. Measurement and analysis revealed that the wear of the mandrel tip roll was 5%, and the actual front-end reduction rate of 6% was too low, contributing to the difficulty in biting and the uneven front-end wall thickness.

[0100] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: Controlling the pre-piercing reduction rate is one of the most important means of controlling the details of the piercing process. For the adjustment process after wear of the relatively mature piercing rolls, the level of control over the pre-piercing reduction rate determines the stability of the actual piercing. Pre-adjustment is performed based on the adjustment parameters of the new roll, and the roll wear corresponding to the top point is measured. The roll gap is reduced and the mandrel is retracted accordingly using the method of increasing the pre-piercing reduction rate to maintain the actual pre-piercing reduction and the piercing wall thickness unchanged. Based on the initial adjustment die shape, the roll wear corresponding to the top point is measured, and compensation for the roll wear is performed to obtain fine adjustment. Because the wear of the rolls differs at different top point positions, through the combination of pre-adjustment, initial adjustment, and fine adjustment—a series of methods to increase the pre-piercing reduction rate—the ideal actual pre-piercing reduction rate value and the piercing wall thickness value remain unchanged.

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for adjusting a worn perforated roller, characterized in that, Includes the following steps: Step S1, Pre-adjustment The pre-compression reduction rate is selected based on the billet diameter and steel grade, and the mandrel is selected based on the tube specifications. The shunting parameters are obtained using the shunting calculation formula, which includes the mandrel diameter, roll gap, mandrel extension, and guide distance. Step S2, Initial Adjustment The actual roll gap corresponding to the mandrel tip is measured and compared with the theoretical roll gap to obtain the roll wear amount corresponding to the mandrel tip. The roll gap is then compensated for the wear amount by reducing the roll gap by half of the roll wear amount. The other half of the roll wear is calculated by determining the mandrel extension amount using the mandrel extension calculation formula, and the guide distance is calculated using the guide distance calculation formula. Step S3, fine-tuning The actual roll gap corresponding to the mandrel tip is measured and compared with the theoretical roll gap to obtain the roll wear amount corresponding to the mandrel tip. The roll gap is then compensated for the wear amount by reducing the roll gap by half of the roll wear amount. The other half of the roll wear is calculated by determining the mandrel extension amount using the mandrel extension calculation formula, and the guide distance is calculated using the guide distance calculation formula. At the same time, the wear of the roll corresponding to the tip of the mandrel after fine-tuning is checked. Selecting the mandrel according to the capillary tube specification refers to selecting the mandrel diameter Dt. Dt=dm- Dm / (5 (δm) 1 / 2 ), Wherein, dm is the inner diameter of the capillary tube, Dm is the outer diameter of the capillary tube, and δm is the wall thickness of the capillary tube. The pre-top reduction ratio ε, determined based on the billet diameter and steel grade, refers to... The pre-pin reduction ratio is the percentage of the diameter reduction of the billet when it contacts the mandrel, relative to the billet diameter. The selected pre-pin reduction ratio should be less than the critical reduction ratio of the steel grade and greater than the minimum pre-pin reduction ratio required for bite-in. The top compression rate is 4% to 8%.

2. The adjustment method for worn perforated rollers according to claim 1, characterized in that, For carbon steel and general alloy steel, the selected pre-top reduction rate for ∮155-270 billets is 6-8%.

3. The adjustment method for worn perforated rollers according to claim 2, characterized in that, For carbon steel and general alloy steel, the pre-top reduction rate for ∮155-270 billets is further selected to be 7%.

4. The adjustment method for worn perforated rollers according to claim 1, characterized in that, For high-alloy steel, the selected pre-top reduction rate for ∮155-270 billets is 5-7%.

5. The adjustment method for worn perforated rollers according to claim 1, characterized in that, In step S1, the shunting calculation formula is as follows: B=(1-e) Dp tanβ2 / (tanβ1+ tanβ2)+(Dt+2δm) tanβ1 / (tanβ1+ tanβ2)-2Lt tanβ1 tanβ2 / (tanβ1+ tanβ2) C = Lt - (Dt + 2δm - B) / 2 tanβ2 Y=Lt-C A=(2Dm / ( Dt+2δm)-1) B Wherein, Dp is the billet diameter, δm is the capillary wall thickness, β1 is the roll inlet cone angle, β2 is the roll outlet cone angle, Dt is the mandrel diameter, Lt is the mandrel length, B is the roll gap, C is the mandrel extension, Y is the mandrel position, A is the guide distance, and Dm is the capillary outer diameter.

6. The adjustment method for worn perforated rollers according to claim 1, characterized in that, In step S2, the formulas for calculating the top extension and guide distance are as follows: C=Lt-(Dt+2δm-B) / 2 tanβ2 A=(2Dm / ( Dt+2δm)-1) B Wherein, C is the mandrel extension, Lt is the mandrel length, Dt is the mandrel diameter, δm is the capillary tube wall thickness, B is the roll gap, β2 is the roll exit cone angle, A is the guide distance, and Dm is the capillary tube outer diameter.

7. The adjustment method for worn perforated rollers according to claim 1, characterized in that, In step S3, the formulas for calculating the top extension and guide distance are as follows: C=Lt-(Dt+2δm-B) / 2 tanβ2 A=(2Dm / ( Dt+2δm)-1) B Wherein, C is the mandrel extension, Lt is the mandrel length, Dt is the mandrel diameter, δm is the capillary tube wall thickness, B is the roll gap, β2 is the roll exit cone angle, A is the guide distance, and Dm is the capillary tube outer diameter.

8. The adjustment method for worn perforated rollers according to claim 1, characterized in that, In step S3, if the wear measured before and after adjustment are the same, the adjustment is complete. If the wear amount measured before and after adjustment is different, step S3 needs to be repeated once more to fine-tune until the wear amount measured before and after adjustment is the same, and then the adjustment is completed.

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