A method for correcting the motion synchronization accuracy of the feed chuck device of a seamless steel pipe cold rolling mill

Abstract

A method for correcting the kinematic synchronization accuracy of the feed chuck assembly in a seamless steel tube cold rolling mill utilizes online precision measurement and backlash compensation based on the operating characteristics of the feed chuck assembly and its threaded pair. The method includes three steps, including measuring and determining wear values for the three-wire lead screw, the rolling bearing, and the threaded pair, and then correcting the kinematic synchronization accuracy of the threaded pair. Calculation models are then established for each step to meet the technical requirements for feed chuck operation stability. The method features a rational design, streamlined and compact procedures, convenient calculation and measurement, reduced labor intensity, and reduced reliance on personnel skills and experience. It is safe, reliable, practical, efficient, and easy to implement on-site.

Description

Technical Field

[0001] The invention relates to a steel pipe production technology, in particular to a method for correcting the motion synchronization accuracy of a feeding chuck device of a seamless steel pipe cold rolling mill. Background Art

[0002] Seamless steel pipe cold rolling technology has become the primary method for producing and processing seamless steel pipes due to its high rolling precision, fast speed, high production capacity, high yield rate, and ease of production organization and process adjustment. Seamless steel pipe cold rolling equipment is categorized by the number of rolls, including two-roll and multi-roll types. The two-roll cyclic cold rolling mill is the most widely used due to its compact structure, high rolling force, and high production capacity.

[0003] See also Figures 1 to 7 The two-roller cyclic cold rolling mill primarily consists of a feed rotary mechanism 100, a rolling mechanism 200, a transmission mechanism, a mandrel chuck mechanism, a material feeding and blanking mechanism, a hydraulic system, a process lubrication system, an electrical automation control system, a pneumatic system, and an intermediate support mechanism 300. The intermediate support mechanism 300 comprises an intermediate bed 1 and support base 2, a feed chuck 3, a three-wire lead screw 4, a movable center frame 5, lubrication pipes 6, and a transmission device. Its front end connects to the rolling mechanism's base 200, and its rear end connects to the feed rotary mechanism 100's gearbox 101, providing a transitional connection and support between the feed rotary mechanism 100 and the rolling mechanism 200. The feed chuck 3, consisting of an upper housing 31 and a lower housing 31', a rolling bearing 32, a chuck barrel 33, a jaw seat 34 and tube jaws 341, a tube guide sleeve 35, side slides 36 and a lower slide 36', a lubrication line support 37, a three-wire copper nut 38, and a nut shield 39, converts rotary motion into horizontal feed motion. The movable center frame 5, comprised of 12 independent sets of adjustable center frames and tie rods, supports the tube 400 and mandrel push rod 8 in sections. The adjustable center frames can be adjusted vertically to accommodate tubes of varying sizes (outer diameters) to ensure that the centerline of the tube 400 and mandrel push rod 8 meets technical requirements for the rolling centerline of the cold rolling mill. The three-wire lead screw 4 consists of two independent left and right screw shafts and a coupling. Its front end is connected to the positioning shaft of the rolling mechanism 200's base via a coupling, while its rear end is connected to the output shaft of the feed rotary mechanism 100 via a coupling. This transmits the rotational motion of the feed rotary mechanism 100, driving the horizontal reciprocating motion of the feed chuck assembly 3. The lubrication line 6, consisting of two independent lubrication pipes, connectors, and valves, provides online thin oil lubrication for the three-wire lead screw 4 and the intermediate bed 1.

[0004] When rolling seamless steel pipes, the main motor outputs rotational motion, which is transmitted to the main transmission mechanism and the feed rotary mechanism through the reducer and drive shaft device respectively. On the one hand, the main transmission mechanism transmits the rotational motion to the rolling mechanism, driving the working frame to perform horizontal reciprocating motion within the machine base. The gears on both sides of the roll device engage with the racks on both sides of the machine base, converting the horizontal reciprocating motion of the working frame into the synchronous rotational motion of the roll device, thereby achieving the rolling deformation process of the tube blank. Therefore, the horizontal reciprocating motion of the rolling mechanism is the main motion in the rolling deformation motion of the cold rolling mill. On the other hand, the input rotational motion is converted into output feed motion and rotary motion through the various shaft systems of the feed rotary mechanism. The feed motion is to convert the rotational motion output by the feed rotary mechanism into the horizontal reciprocating motion of the feed chuck device, pushing the tube billet into the rolling mechanism for deformation processing at a uniform speed. The rotary motion is to transmit power (rotational motion) to the mandrel chuck device, driving the mandrel (thrust rod) and the tube billet to perform synchronous rotational motion, so as to ensure the roundness and coaxiality of the seamless steel pipe during rolling. Therefore, the feed and rotary motions are secondary (auxiliary) motions in the rolling deformation motion of the cold rolling mill.

[0005] As for the intermediate support mechanism, during seamless steel tube rolling, the first thing it receives is the feed (rotation) motion output by the feed rotary mechanism. This rotational motion is transmitted to the three-wire screws on both sides of the intermediate bed through a coupling, and then transmitted to the feed chuck device inside the intermediate bed. The three-wire threaded pairs (copper nuts) installed in the ears on both sides of the feed chuck device convert the rotational motion transmitted by the three-wire screws into horizontal reciprocating motion of the feed chuck device. The feed chuck device drives the billet tube to perform uniform horizontal motion within the bed support seat of the intermediate bed mechanism. The billet tube is pushed into the rolling mechanism at a uniform speed according to the set rolling feed rate (equivalent horizontal motion displacement per minute, unit: mm / min). The horizontal reciprocating motion of the working frame and the synchronous rotational motion of the roller device inside the frame complete the cold rolling (extrusion) deformation process of the billet tube. Therefore, the operating stability of the feed chuck device directly affects the quality and efficiency of tube billet rolling. With the technological progress of the seamless steel pipe industry, the industrial production of high-end seamless steel pipes made of high-strength, high-alloy, corrosion-resistant, and deformation-resistant nickel-based alloys, high-temperature alloys, duplex stainless steel and other steel grades has become more stringent in terms of rolling accuracy. The error value of horizontal feed movement is ≤1mm.

[0006] In production practice, the operational stability of the feed chuck assembly depends not only on the accuracy of the assembly itself but also on the accuracy of the rotational motion transmitted by the three-wire screw and the synchronization of the three-wire screws on the left and right sides. Besides factors inherent to the three-wire screw itself (such as machining accuracy, wear equivalent, deformation equivalent, and the output accuracy of the feed rotary mechanism), the synchronization and rotational motion accuracy of the three-wire screw primarily depend on the three-wire thread pair (copper nut). Compared to three-wire screws made of high-strength steel and heat-treated, the thread pair (copper nut) is a consumable and replaceable part. Due to the wear of the thread pair (copper nut) from long-term rotational friction with the three-wire screw, an axial motion gap is generated on the trapezoidal thread mating surface, and the wear equivalent of the left and right thread pairs (copper nuts) is inconsistent. While the rotational motion of the three-wire lead screws on both sides is relatively stable, the different wear values of the thread pair (copper nut) will cause one side of the feed chuck device to advance or lag in the horizontal motion, resulting in left and right twisting of the feed chuck device in the horizontal motion, which will eventually cause the stability of the feed chuck device in horizontal operation to decrease. At the same time, this phenomenon will accelerate the wear of the copper nut.

[0007] Abnormal operational stability of the feed chuck assembly can cause feed rate anomalies during seamless steel pipe rolling. According to action and reaction (Newton's third law of motion), the feed rate of the tube billet pushed into the rolling mechanism during rolling is the force exerted by the feed chuck assembly. The reaction force exerted by the tube billet on the feed chuck assembly is constant and commensurate with the action force. This force is primarily exerted on the left and right threaded pairs of the feed chuck assembly and the two front and rear rolling bearings of the chuck barrel (spindle) within the chuck housing. The function of these rolling bearings is to ensure synchronous rotation of the chuck barrel (spindle) under axial load. Due to the structural characteristics of these bearings, radial friction and wear are minimized under axial load. However, when the threaded pairs on both sides of the feed chuck assembly are subjected to axial loads transmitted by the feed chuck housing, friction increases at the axial contact surface between the lead screw and the copper nut (trapezoidal threads), leading to increased wear. As the wear of the threaded pair increases, the clearance between them also increases, and the destructive effect of the reaction force during rolling increases simultaneously, directly generating a reverse impact load on the feed chuck assembly. This load persists for a long time and is directly proportional to the rolling force and the size of the wear clearance. Therefore, the clearance between the threaded pair (copper nut) and the three-wire lead screw caused by wear is a detrimental factor to the cold rolling of seamless steel pipes. In particular, the wear of the threaded pairs on the left and right sides of the feed chuck assembly is different. Therefore, when the rotational motion output from the feed rotary mechanism to the three-wire lead screw remains synchronized, the difference in threaded pair wear is the direct cause of the feed chuck assembly's horizontal motion stability.

[0008] Therefore, timely discovering the wear equivalent errors of the thread pairs (copper nuts) on both sides and taking effective measures to ensure that their movement synchronization meets the technical requirements can ensure the horizontal movement accuracy of the feed chuck device during seamless steel pipe rolling. At present, because the equipment design and manufacturer have not been able to provide corresponding process manuals for the actual measurement of the wear equivalent of the thread pair (copper nut), it is only required to replace the thread pair (copper nut) when the trapezoidal thread wear is ≥ 2 / 3 of the pitch P. Based on this, referring to the general operating methods of mechanical transmission components, the actual measurement method and estimation method are generally used for treatment, namely:

[0009] 1) Actual measurement method: This involves regularly disassembling the threaded pairs (copper nuts) in the ear seats on both sides of the feed chuck device in a stopped state and measuring the actual wear equivalent of the threads. When the wear value is ≥ 2 / 3 of the standard thread thickness (2 / 3 pitch P), the threaded pair (copper nut) is scrapped and replaced with a new one. This method is highly practical and determines the wear equivalent by directly measuring the thread thickness. The measurement error is small and the accuracy is high, but it requires disassembling the entire feed chuck device and removing the fasteners such as the direct connection bolts between the upper and lower boxes. This is labor-intensive and time-consuming, with long downtimes, and it is impossible to timely measure the synchronization error value of the threaded pairs on the left and right sides of the feed chuck. Therefore, it is only suitable for implementation during planned repairs and overhauls of the equipment, and is not suitable for fast and accurate operation and maintenance operations at the company's production site.

[0010] 2) Estimation method: When the feed chuck device is in operation, based on the principle of action and reaction, the equivalent displacement between the push and retraction of the feed chuck device is used to estimate the equivalent motion clearance between the thread pair (copper nut) and the three-wire screw. The thickness of the three-wire screw thread segment is then measured and compared with the estimated motion clearance value to finally determine the wear value of the thread pair. The wear value is determined to be ≥ 2 / 3 of the standard thread thickness value (2 / 3 of the pitch P value) to determine whether the thread pair needs to be disassembled and replaced with a new one. This method does not require disassembly of the feed chuck device, saving labor and time, but the accuracy is relatively low, the error in the estimation is relatively large, and the experience and skill level of the operator are required to be high. In particular, it is impossible to estimate the synchronization error value of the thread pairs on the left and right sides of the feed chuck. Therefore, it is only suitable for inspection and maintenance operations at the production site and is not suitable for planned maintenance operations.

[0011] In summary, both the actual measurement method and the estimation method have certain limitations. In particular, both methods aim to determine the clearance between the thread pair (copper nut) and the three-wire lead screw, and determine whether the thread pair (copper nut) needs to be replaced with a new one. However, they cannot address operating conditions where wear occurs but does not exceed 2 / 3 of the standard thread thickness (pitch P) of the thread segment, and the clearance values (wear) on the left and right sides differ. Currently, for the operating accuracy and stability of the feed chuck device, it is necessary not only to ensure that the accuracy (clearance) of the thread pair and the three-wire lead screw meet technical requirements, but also to ensure the synchronization of the clearance between the left and right thread pairs. That is, during horizontal feed motion, the lead and lag equivalents of the left and right thread pairs must meet technical requirements (≤1.0mm). However, existing operating process methods cannot simultaneously meet these requirements. Summary of the Invention

[0012] The purpose of the present invention is to provide a method for correcting the precision of the motion synchronization of the feed chuck device of a seamless steel tube cold rolling mill, which is a technical improvement of the online precision measurement and synchronization correction method of the motion gap of the feed chuck device in the intermediate bed mechanism of the existing two-roller periodic seamless steel tube cold rolling mill; after the online precision measurement and correction operation, the synchronization error of the thread pairs on the left and right sides of the feed chuck device is ≤0.5mm, which provides data for the deterioration tendency analysis of the thread pair components, promotes the functional precision construction of the equipment, and realizes the continuous stability of the operation of the feed chuck device from the source, and meets the technical requirements of the cold rolling production of high-end seamless steel tubes such as nickel-based alloys, high-temperature alloys, and duplex stainless steel, and has a certain effect of eliminating faults, reducing costs and promoting production; moreover, the method of the present invention has strong versatility, reasonable design, compact and smooth process, convenient calculation and measurement, reduced labor intensity, reduced dependence on personnel skills and experience, and is easy to implement on site.

[0013] To achieve the above object, the technical solution of the present invention is:

[0014] The present invention adopts an online precision measurement and clearance correction and compensation method based on the working characteristics of the feed chuck device and its threaded pair. It consists of four main processes, namely, measurement and determination of the wear value of the three-wire screw, measurement and determination of the wear value of the rolling bearing, measurement and determination of the wear value of the threaded pair, and precision correction of the synchronization of the movement of the threaded pair, and two auxiliary processes, namely, operation preparation and reset debugging. Calculation models are set for each process to meet the technical requirements for the operational stability of the feed chuck device.

[0015] Specifically, the method for correcting the motion synchronization accuracy of the feed chuck device of a seamless steel tube cold rolling mill according to the present invention comprises the following steps:

[0016] 1) Preparation

[0017] Remove the tube blanks and mandrels in the middle bed and rolling mechanism, clean the upper box of the feed chuck device and the threaded section of the three-wire lead screw, and confirm that the feed chuck device is stopped at the middle bed; remove the tube blank guide sleeve at the end of the chuck cylinder of the feed chuck device and the nut protective covers on the outside of the copper nuts on both sides of the feed chuck device;

[0018] 2) Measurement and determination of screw wear value

[0019] 2.1 Determine the effective stroke length L of the feed chuck's horizontal reciprocating motion in the middle bed, L = bed length B - (front movable center frame length D1 + rear movable center frame length D2 + front coupling length D3 + rear coupling length D4);

[0020] 2.2 Determine the measured length L1 of the three lead screws located above the middle bed, i.e. the left and right lead screws. L1 = the effective stroke length L of the feed chuck in the middle bed - the feed chuck length correction factor t1; the value of t1 is determined according to the feed chuck length of the cold rolling mill and the length of the copper threaded end face protective cover of different models and specifications, and is preferably 120-200mm;

[0021] 2.3 Select the measuring position: Use the three-segment method. According to the measuring length of the three-wire screw, determine the three measuring positions C1, C2, and C3 at the beginning, middle, and end in the horizontal running direction of the feed chuck. Among them, C1 = the beginning of the screw measuring length + 100mm, C2 = the midpoint of the screw measuring length, and C3 = the end of the screw measuring length - 100mm.

[0022] 2.4 Measurement of left side screw wear: Use a national standard 1-16mm tooth thickness caliper to measure the left side screw in the bed, and select the head end C1 left, the middle part C2 left, and the end part C3 left; measure the screw by cutting three continuous trapezoidal threads at the front end, rear end, and middle part of the screw for actual measurement, and use the average method to determine the wear of the three measuring points. Finally, determine the average wear value of the left side screw, that is, C left = (C1 left + C2 left + C3 left) / 3;

[0023] 2.5 Measurement of right side screw wear: Use a national standard 1-16mm tooth thickness caliper to measure the right side screw in the bed, and select the head end C1 right, the middle part C2 right, and the end part C3 right. To measure the screw, cut off three continuous trapezoidal threads at the front end, rear end, and middle part of the screw, respectively, and measure them. Record the readings and use the average method to determine the wear of the three measuring points. Finally, determine the average wear value of the right side screw, that is, C right = (C1 right + C2 right + C3 right) / 3.

[0024] 3) Measurement and determination of rolling bearing wear value

[0025] 3.1 Use a dial indicator to measure the axial clearance between the front and rear rolling bearings in the feed chuck assembly. First, secure the magnet holder of the dial indicator bracket to the middle of the upper housing of the feed chuck assembly, aligning the centerline of the magnet holder with the axis of the feed chuck. Align the dial indicator probe with the end face of the threaded section at the end of the feed chuck barrel.

[0026] 3.2 Online clearance measurement: First, start the motor of the quick-ejection device of the feed rotary mechanism, run the feed chuck horizontally in the forward direction at low speed for 200 to 350 mm, and read and record the reading on the dial indicator. This reading is the actual measured clearance value F1 of the rolling bearing when the feed chuck is running in the forward direction; start the motor of the quick-ejection device of the feed rotary mechanism again, run the feed chuck horizontally in the reverse direction at low speed for 200 to 350 mm, and read and record the reading on the dial indicator. This reading is the actual measured clearance value F2 of the rolling bearing when the feed chuck is running in the reverse direction;

[0027] 3.3 Remove the dial indicator installed on the feed chuck device and return the feed chuck device to its original stop position;

[0028] 3.4 Confirmation of rolling bearing clearance: Compare the clearance values of the rolling bearing of the feed chuck device under forward and reverse working conditions, and take the clearance under forward working condition as the standard. If the forward clearance value F1 ≥ the reverse clearance value F2, the forward clearance shall be the actual measured clearance value of the rolling bearing; if the forward clearance value F1 < the reverse clearance value F2, the average of the sum of the forward clearance value and the reverse clearance value shall be the actual measured clearance value F of the rolling bearing, F = (F1 + F2) / 2;

[0029] 4) Measurement and determination of thread pair wear value

[0030] The wear equivalent of the middle section of the screw is used as the basic value for measurement and correction;

[0031] 4.1 Use the end surface of the threaded section of the chuck cylinder of the feed chuck device as the reference, align the reference with the 100mm scale line of the steel ruler, and fix them on the protective covers on the left and right sides of the middle bed respectively;

[0032] 4.2 Thread pair clearance measurement: Applicable to the clearance measurement within the pitch range of 6 to 16 mm. The measurement interval is preferably 10 to 12 turns of the screw. That is: first start the motor of the quick-exit device of the feed rotary mechanism, run the feed chuck horizontally at low speed in the forward direction for 140 to 168 mm, that is, the 240 to 268 mm scale line on the steel ruler, and then run the feed chuck horizontally in the reverse direction. The stagnation distance of the feed chuck when it starts is the thread pair meshing clearance value between the screw and the copper nut.

[0033] 4.3 Reading the thread pair clearance: After the feed chuck starts running horizontally in the reverse direction at low speed for 140 to 168 mm, observe the error between the end face of the threaded section at the end of the chuck barrel and the 100 mm scale line on the 0 to 300 mm steel ruler. This is the thread pair meshing clearance between the lead screw and the copper nut. Read the scale value parameters of the steel rulers on the left and right sides of the bed respectively. This is the wear equivalent A left and A right of the feed chuck after the lead screw thread pair is engaged under no-load conditions.

[0034] 4.4 Determination of thread pair wear:

[0035] The meshing clearance H left between the left lead screw and the copper nut in the left ear seat of the feed chuck device = the left thread pair clearance value A left - the rolling bearing clearance value F of the feed chuck device;

[0036] The meshing clearance Hright between the right side lead screw and the copper nut in the left ear seat of the feed chuck device = the right side thread pair clearance value Aright - the rolling bearing clearance value F of the feed chuck device;

[0037] 4.5 Determination of the applicability of thread pair wear:

[0038] The 2 / 3 of the standard thread thickness value, that is, 2 / 3 of the pitch P value, is used as the criterion for judging whether the copper nut is suitable for use, that is:

[0039] When the measured wear value is ≥ 2 / 3 of the standard thread thickness, the copper nut can no longer be used and needs to be removed and replaced;

[0040] When the measured wear value is less than 2 / 3 of the standard thread thickness value, the axial reference position of the copper nut can be adjusted to correct the synchronization accuracy of the left and right thread pairs and then continue to use. The use cycle is proportional to the wear value and can be determined according to the actual wear value;

[0041] 5) Thread pair motion synchronization accuracy correction, i.e. online motion gap correction

[0042] 5.1 Determine the wear correction equivalent of the left thread pair: Correction equivalent Ileft = left thread pair motion clearance Hleft - left screw wear Cleft;

[0043] 5.2 Determine the wear correction equivalent of the right thread pair: Correction equivalent Iright = left thread pair motion clearance Hright - left screw wear Cright;

[0044] 5.3 Determine the correction location: Compare the values of the correction equivalent I left and the correction equivalent I right, and use the thread pair on the side with less wear and a relatively smaller correction equivalent as the reference, and the other side as the correction location;

[0045] 5.4 Determine the correction amount I: The absolute value of the difference between the correction equivalent I left and the correction equivalent I right is used as the online correction amount. By axially shifting the copper nut installation position, the synchronization error correction between the copper nut and the three-wire lead screw during positive horizontal displacement is achieved;

[0046] 5.5 Preparation and processing of gaskets: Based on the measured correction equivalent, a semi-annular gasket is processed according to the shape of the copper nut end face shoulder. The gasket material is copper. The gasket thickness should not exceed the measured correction equivalent and should not be less than 10-20% of the measured correction equivalent I left or I right.

[0047] 5.6 Correction and compensation work: Taking the copper nut on the side with less wear as the reference, first remove the fastening screws on the copper nut end face with more wear on the feed chuck device. Then, inching the feed chuck in the reverse horizontal direction at a low speed, that is, the screw rotation amount is not more than 1 circle. Then, install the prepared gasket in the area between the split copper nut shoulder with more wear and the end face of the feed chuck ear seat. Install and pre-tighten the screws. At this time, inching the feed chuck in the forward horizontal direction at a low speed, that is, the screw rotation amount is not more than 1 circle, and then tighten the copper nut screws.

[0048] 6) Reset and debugging of the intermediate bed mechanism:

[0049] 6.1 Carry out debugging under power-on and no-load conditions, and use the steel ruler scale method to check the synchronization error value of the thread pair of the left and right feed screws and the copper nut of the feed chuck device; when the error value is less than 1mm, the synchronization of the thread pair meets the requirements and rolling production can be carried out; when the error value is ≥1mm, it means that the online correction operation is unqualified and correction and adjustment operation must be carried out again until the error value is less than 1mm;

[0050] 6.2 Install the feed chuck tube guide sleeve and copper nut end protective cover and deliver them to the manufacturer for use.

[0051] Beneficial effects of the present invention:

[0052] 1) The process design is reasonable, the process steps are smooth, practical and efficient, and it has a certain effect of eliminating errors, reducing costs and promoting production. It meets the cold rolling production needs of high-end seamless steel pipes such as nickel-based alloys, high-temperature alloys, and duplex stainless steel, and promotes the market competitiveness of the company's core products;

[0053] 2) Using Newton's third law of motion (action and reaction theorem), the wear clearance between the feed chuck device and the three-wire lead screw trapezoidal thread of the seamless steel tube cold rolling mill can be measured and accurately trimmed under non-disassembly conditions;

[0054] 3) Based on the working characteristics of the feed chuck device and its thread pair, online precision measurement and gap correction compensation are adopted, and calculation models are set separately to achieve standardized operation, and the operation process is quantitatively controllable;

[0055] 4) Calculation and measurement are convenient, labor-saving and time-saving, safe and reliable, reduce labor intensity, and reduce dependence on personnel skills and experience. Intermediate workers can be competent;

[0056] 5) Comprehensively considering the actual working conditions of each moving component, the motion clearance under no-load conditions is used as the basis for trimming and compensation. This is more operational in production practice, and the accuracy meets the production technology and equipment operation technical requirements.

[0057] 6) No need to increase related expenses, the one-time pass rate of precision trimming operation reaches 100%, which is practical, efficient and easy to implement on site;

[0058] 7) After online precision measurement and calibration, the synchronization error of the thread pairs on the left and right sides of the feed chuck device is ≤0.5mm, providing data for deterioration tendency analysis of the thread pair components, continuously ensuring the operational stability of the feed chuck device and promoting the functional precision of cold rolling production equipment;

[0059] 8) It has strong versatility and is applicable to all current models and specifications of two-roller periodic seamless steel tube cold rolling mills. It has broad application prospects and has certain reference and application value for the methods and measures for improving the operating stability of the feed chuck device in the intermediate bed mechanism of the two-roller periodic seamless steel tube cold rolling mill in the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a schematic diagram of the structure of the intermediate support mechanism of a two-roller periodic seamless steel pipe cold rolling mill;

[0061] Figure 2 for Figure 1 Side view of

[0062] Figure 3 for Figure 1 A top view of

[0063] Figure 4 This is a structural diagram of the feed chuck device of a seamless steel pipe cold rolling mill;

[0064] Figure 5 for Figure 4 A top view of

[0065] Figure 6 for Figure 4 AA cross-sectional view;

[0066] Figure 7 for Figure 6 K-direction view;

[0067] Figure 8 This is a structural diagram of the feed motion gap of a seamless steel pipe cold rolling mill;

[0068] Figure 9 for Figure 8 A partial enlarged schematic diagram of the middle part I;

[0069] Figure 10 This is a schematic diagram of the measurement working conditions of the intermediate support mechanism of the seamless steel pipe cold rolling mill;

[0070] In the picture:

[0071] t1 - feed chuck length correction factor;

[0072] D1-the total length of the movable center frame at the front end of the middle bed; D2-the total length of the movable center frame at the rear end of the middle bed;

[0073] D3 - total length of the front coupling and other devices in the middle bed; D4 - total length of the rear coupling and other devices in the middle bed;

[0074] L - the effective length of the feed chuck's horizontal reciprocating motion in the middle bed;

[0075] L1 - the measuring length of the three-wire screw in the middle bed;

[0076] B - total length of the middle bed support (bed);

[0077] Feed chuck positioning position - midpoint of screw measurement length + t2;

[0078] C1-the beginning of the screw measuring length-100mm; C2-the midpoint of the screw measuring length;

[0079] C3 - end of screw measuring length - 100mm;

[0080] Figure 11 This is a schematic diagram of the working condition for measuring the rolling bearing clearance of the feed chuck of a seamless steel tube cold rolling mill;

[0081] Figure 12 This is a schematic diagram of the wear clearance measurement working conditions of the feed chuck thread pair of the seamless steel pipe cold rolling mill. DETAILED DESCRIPTION

[0082] See also Figures 1 to 12 The method for correcting the motion synchronization accuracy of the feed chuck device of a seamless steel tube cold rolling mill according to the present invention comprises the following steps:

[0083] 1) Preparation

[0084] Remove the tube 400 and mandrel (thrust rod) 8 from the intermediate bed 1 and the rolling mechanism, clean the upper housing 31 of the feed chuck device 3 and the threaded section of the three-wire lead screw 4, and confirm that the feed chuck device 3 is stopped at the intermediate bed 1; remove the tube guide sleeve 35 at the end of the chuck cylinder 33 of the feed chuck device 3 and the nut protective covers 39 on the outside of the copper nuts 38 on both sides of the feed chuck device 3;

[0085] 2) Measurement and determination of screw wear value

[0086] 2.1 Determine the effective stroke length L of the horizontal reciprocating motion of the feed chuck device 3 in the intermediate bed 1, L = bed length B - (front movable center frame 5 length D1 + rear movable center frame 5' length D2 + front coupling 6 length D3 + rear coupling 6' length D4);

[0087] 2.2 Determine the measured length L1 of the three-wire lead screw 4 (left and right lead screws 41 and 42) located above the intermediate bed 1. L1 = the effective stroke length L of the feed chuck assembly 3 within the intermediate bed 1 - the length correction factor t1 of the feed chuck assembly 3. The value of t1 is determined based on the length of the feed chuck of the cold rolling mill of different models and specifications and the length of the end face protection cover 39 of the copper nut 38, and is preferably 120 to 200 mm.

[0088] 2.3 Select the measurement position: Using the three-segment method, based on the measured lengths of the three-line screw 4, i.e., the left and right screws 41 and 42, determine the three measurement positions C1, C2, and C3 of the beginning, middle, and end in the horizontal running direction of the feed chuck. Among them, C1 = the beginning of the screw measurement length + 100mm, C2 = the midpoint of the screw measurement length, and C3 = the end of the screw measurement length - 100mm.

[0089] 2.4 Measurement of the wear value of the left side screw 41: Use a national standard 1~16mm tooth thickness caliper to measure the left side screw in the bed, and select the head end C1 left, the middle part C2 left, and the end part C3 left; the screw is measured by cutting three continuous trapezoidal threads at the front end, rear end, and middle part of the screw for actual measurement, and the average method is used to determine the wear value of the three measuring points. Finally, the average wear value of the left side screw is determined, that is, C left = (C1 left + C2 left + C3 left) / 3;

[0090] 2.5 Measurement of the wear value of the right side screw 42: Use a national standard 1~16mm tooth thickness caliper to measure the right side screw in the bed, and select the head end C1 right, the middle part C2 right, and the end part C3 right; measure the screw by cutting three continuous trapezoidal threads at the front end, rear end, and middle part of the screw for actual measurement, record the readings and use the average method to determine the wear value of the three measuring points respectively, and finally determine the average wear value of the right side screw, that is, C right = (C1 right + C2 right + C3 right) / 3;

[0091] 3) Measurement and determination of rolling bearing wear value

[0092] 3.1 Use the dial indicator 9 to measure the axial clearance between the front and rear rolling bearings 32 in the feed chuck assembly. First, secure the magnet holder of the dial indicator bracket 91 to the center of the upper housing 31 of the feed chuck assembly 3, with the centerline of the magnet holder aligned with the axis of the feed chuck assembly 3. Align the probe of the dial indicator 9 with the end surface 331 of the threaded section at the end of the feed chuck barrel 33.

[0093] 3.2 Online Gap Measurement: First, start the motor of the quick-ejection device of the feed rotary mechanism, run the feed chuck device 3 horizontally in the forward direction at a low speed for 200 to 350 mm, and read and record the reading on the dial indicator. This reading is the actual measured gap value F1 of the rolling bearing 32 when the feed chuck device 3 is running in the forward direction; then start the motor of the quick-ejection device of the feed rotary mechanism again, run the feed chuck device 3 horizontally in the reverse direction at a low speed for 200 to 350 mm, and read and record the reading on the dial indicator. This reading is the actual measured gap value F2 of the rolling bearing 32 when the feed chuck device 3 is running in the reverse direction;

[0094] 3.3 Remove the dial indicator 9 installed on the feed chuck device 3, and return the feed chuck device 3 to its original stop position;

[0095] 3.4 Confirmation of rolling bearing clearance: Compare the clearance values of the rolling bearing 32 of the feed chuck device 3 under forward and reverse working conditions, with the clearance under the forward working condition as the standard. If the forward clearance value F1 ≥ the reverse clearance value F2, the forward clearance shall be the actual measured clearance value of the rolling bearing 32. If the forward clearance value F1 < the reverse clearance value F2, the average of the sum of the forward clearance value and the reverse clearance value shall be the actual measured clearance value F of the rolling bearing 32, where F = (F1 + F2) / 2.

[0096] 4) Measurement and determination of thread pair wear value

[0097] The wear equivalent of the middle section of the three-wire screw 4 is used as the basic value for measurement and correction;

[0098] 4.1 Fix two (0-300mm) steel rulers 10 on the left and right sides of the protective cover 36 of the middle bed 1 respectively, with the end surface of the threaded section of the chuck cylinder 33 of the feed chuck device 3 as the reference and the reference aligned with the 100mm scale line of the steel ruler;

[0099] 4.2 Thread pair clearance measurement: Applicable to the clearance measurement within the pitch range of 6 to 16 mm. The pitch of the three-wire screw 4 and the copper nut 38 is 14 mm, so the measurement range is preferably 10 to 12 rotations of the three-wire screw 4. That is: first start the feed rotary mechanism quick exit device motor, run the feed chuck device 3 at low speed in the forward horizontal direction for 140 to 168 mm, that is, the 240 to 268 mm scale line on the steel ruler, and then run the feed chuck device 3 in the reverse horizontal direction. At this time, the stagnation distance of the feed chuck device 3 when it starts is the thread pair meshing clearance value between the three-wire screw 4 and the copper nut 38.

[0100] 4.3 Reading the thread pair clearance: After the feed chuck assembly 3 starts running horizontally at low speed and in the reverse direction for 140 to 168 mm, observe the error between the end face of the threaded segment at the end of the chuck barrel 33 and the 100 mm scale line on the 0 to 300 mm steel ruler. This is the thread pair meshing clearance between the three-wire lead screw 4 and the copper nut 35. Read the scale parameters of the steel ruler on the middle of the left and right sides of the bed 1 respectively. This is the wear equivalent A left and A right of the thread pair meshing between the feed chuck assembly 3 and the three-wire lead screw 4 under no-load conditions.

[0101] 4.4 Determination of thread pair wear:

[0102] The meshing clearance H left between the left lead screw 41 and the copper nut 38 in the left ear seat 37 of the feed chuck device 3 = the left thread pair clearance value A left - the clearance value F of the rolling bearing 38 of the feed chuck device 3;

[0103] The meshing clearance Hright between the right lead screw 42 and the copper nut 38 in the right ear seat 37' of the feed chuck device 3 = the right thread pair clearance value Aright - the clearance value F of the rolling bearing 32 of the feed chuck device 3;

[0104] 4.5 Determination of the applicability of thread pair wear:

[0105] The 2 / 3 standard thread thickness value, i.e. 2 / 3 of the pitch P value, is used as the criterion for determining whether the copper nut 38 is suitable for use, i.e.:

[0106] When the measured wear value is ≥ 2 / 3 of the standard thread thickness value, the copper nut 38 can no longer be used and needs to be removed and replaced;

[0107] When the measured wear value is less than 2 / 3 of the standard thread thickness value, the axial reference position of the copper nut 38 can be adjusted to correct the synchronization accuracy of the left and right thread pairs and then continue to use. The use cycle is proportional to the wear value and can be determined according to the actual wear value.

[0108] 5) Thread pair motion synchronization accuracy correction, i.e. online motion gap correction

[0109] 5.1 Determine the wear correction equivalent of the left thread pair: Correction equivalent Ileft = left thread pair motion clearance Hleft - left screw wear Cleft;

[0110] 5.2 Determine the wear correction equivalent of the right thread pair: Correction equivalent Iright = left thread pair motion clearance Hright - left screw 4 wear Cright;

[0111] 5.3 Determine the correction location: Compare the values of the correction equivalent I left and the correction equivalent I right, and use the thread pair on the side with less wear and a relatively smaller correction equivalent as the reference, and the other side as the correction location;

[0112] 5.4 Determine the correction amount I: The absolute value of the difference between the correction equivalent I left and the correction equivalent I right is used as the online correction amount. By axially displacing the installation position of the copper nut 38, the synchronization error correction between the copper nut 38 and the three-wire lead screw 4 during the positive horizontal displacement is achieved;

[0113] 5.5 Preparation and processing of gaskets: Based on the measured correction equivalent, a semi-annular gasket is processed according to the shape of the copper nut end face shoulder. The gasket material is copper. The gasket thickness should not exceed the measured correction equivalent and should not be less than 10-20% of the measured correction equivalent I left or I right.

[0114] 5.6 Correction and compensation operation: Taking the copper nut on the side with less wear as the reference, first remove the fastening screws on the end face of the copper nut with more wear on the feed chuck device 3. Then, inching the feed chuck device 3 in the reverse horizontal direction at a low speed, that is, the rotation of the three-wire screw 4 is not more than 1 circle. Then, install the prepared gasket in the area between the shoulder of the split copper nut 38 with more wear and the end face of the ear seat of the feed chuck device 3. Install and pre-tighten the screws. At this time, inching the feed chuck in the forward horizontal direction at a low speed, that is, the rotation of the three-wire screw is not more than 1 circle, and then tighten the copper nut screws.

[0115] 6) Reset and debugging of the intermediate bed mechanism:

[0116] 6.1 Carry out debugging under power-on and no-load conditions, and use the steel ruler scale method to check the synchronization error value of the thread pair of the three-wire lead screws on the left and right sides of the feed and the copper nut of the feed chuck device; when the error value is less than 1mm, the synchronization of the thread pair meets the requirements and rolling production can be carried out; when the error value is ≥1mm, it means that the online correction operation is unqualified and correction and adjustment operations must be carried out again until the error value is less than 1mm;

[0117] 6.2 Install the feed chuck tube guide sleeve 35, copper nut 38 end protection cover 39 and deliver it to the manufacturer for use.

[0118] According to the above-mentioned process, the on-site use of the method provided by the present invention for correcting the motion synchronization accuracy of the feed chuck device of a seamless steel pipe cold rolling mill is completed. After online precision trimming, the threaded pair between the feed chuck device and the three-wire lead screw can be restored to a better working state. The synchronization error value of the threaded pairs on both sides of the feed chuck device is ≤0.5mm, which can meet the technical requirements of the cold rolling production of seamless steel pipes of high-strength, deformation-resistant nickel-based alloys, high-temperature alloys, duplex stainless steel and other steel grades.

[0119] Example 1

[0120] According to the specifications of rolled products LG-220H two-roller cyclic seamless steel pipe cold rolling mill, three-wire lead screw pitch = 14mm, bed length B = 12726mm, front and rear movable center frame cumulative total length D1 = 620mm, D2 = 620mm, front and rear couplings and other devices in the bed total length D3 = 520mm, D4 = 1270mm, correction coefficient t1 = 160mm. Taking the equipment maintenance work before seamless steel pipe as an example, the on-site precision correction of the motion clearance of the feed chuck device of the intermediate bed mechanism is carried out. The operation steps include:

[0121] 1. Preparation

[0122] 1.1 Remove the tube blanks, mandrels and other items in the intermediate bed mechanism and rolling mechanism, clean the upper box of the feed chuck device and the threaded section of the three-wire screw (free of impurities and oil stains), and confirm that the feed chuck device is stopped at the stop position in the intermediate bed (the feed chuck is stopped at the middle of the intermediate bed support seat slightly close to the end position, and the distance t2 from the end protective cover of the copper nut to the measuring point in the middle of the three-wire screw is preferably 250-300mm).

[0123] 1.2 Remove the tube guide sleeve at the end of the chuck cylinder of the feed chuck device and clean the end surface of the guide sleeve (no impurities, oil stains); remove the nut protective cover on the outside of the copper nuts on both sides of the feed chuck device, and clean the copper nuts and the screw meshing parts (no impurities, oil stains);

[0124] 2. Measurement and determination of three-wire screw wear value

[0125] 2.1. Determine the effective stroke length L of the feed chuck's horizontal reciprocating motion within the intermediate bed: L = intermediate bed support (bed length B - total length of the front and rear movable center frames within the bed D1, D2 - total length of the front and rear couplings and other devices within the bed D3, D4) = 12726 - 620 - 620 - 520 - 1270 = 9696 mm;

[0126] 2.2. Determine the measured length L1 of the three lead screws (left and right lead screws) above the middle bed: L1 = effective stroke length L of the feed chuck in the middle bed - feed chuck length correction factor t1, t1 = 160mm. L1 = 9696 - 160 = 9536mm;

[0127] 2.3. Select the measuring position: Use the three-segment method. According to the measuring length of the three-wire screw, determine the three measuring positions (C1, C2, and C3) at the beginning, middle, and end in the horizontal running direction of the feed chuck. Among them, C1 = the measuring length of the screw at the beginning + 100mm = 0 + 100 = 100mm, C2 = the measuring length of the screw at the middle = 9536 / 2 = 4768mm, and C3 = the measuring length of the screw at the end - 100mm = 9536 - 100 = 9436mm.

[0128] 2.4. Measurement of the wear value of the left side screw: Use a national standard 1-16mm tooth thickness caliper to measure the left side screw in the bed, and select the starting end C1 left, the middle part C2 left, and the end part C3 left; measure three consecutive trapezoidal threads before and after the measuring station, and use the average method to determine the wear value of the three measuring points respectively, C1 left = 0.12mm, middle part C2 left = 0.18mm, and end part C3 left = 0.10mm. Finally, the average wear value of the left side screw is determined, that is, C left = (C1 left + C2 left + C3 left) / 3 = (0.12 + 0.18 + 0.10) / 3 = 0.13mm;

[0129] 2.5. Measurement of right side screw wear: Use a national standard 1-16mm tooth thickness caliper to measure the right side screw in the bed, and select the starting end C1 right, the middle part C2 right, and the end part C3 right; measure three consecutive trapezoidal threads before and after the measuring station, record the readings, and use the average method to determine the wear of the three measuring points, C1 right = 0.14mm, middle part C2 right = 0.22mm, and end part C3 = 0.12mm right. Finally, determine the average wear value of the right side screw, that is, C right = (C1 right + C2 right + C3 right) / 3 = (0.14 + 0.22 + 0.12) / 3 = 0.16mm;

[0130] 3. Measurement and determination of rolling bearing wear value

[0131] 3.1) Install the measuring tool: Use a dial indicator to measure the axial clearance between the two sets of rolling bearings in the front and rear of the feed chuck. First, fix the magnet holder of the dial indicator bracket to the middle of the upper housing of the feed chuck, with the centerline of the magnet holder aligned with the axis of the feed chuck. Align the dial indicator probe with the end face of the threaded section at the end of the feed chuck barrel (where the tube guide sleeve was originally installed).

[0132] 3.2) Online Gap Measurement: First, start the motor of the quick-ejection device of the feed rotary mechanism, run the feed chuck horizontally in the forward direction at low speed for 200-350 mm, preferably 250-300 mm, and read and record the reading on the dial indicator. This reading is the actual measured gap value F1 of the rolling bearing when the feed chuck is running in the forward direction, which is 0.36 mm. Then, start the motor of the quick-ejection device of the feed rotary mechanism again, run the feed chuck horizontally in the reverse direction at low speed for 200-350 mm, preferably 250-300 mm, and read and record the reading on the dial indicator. This reading is the actual measured gap value F2 of the rolling bearing when the feed chuck is running in the reverse direction, which is 0.28 mm.

[0133] 3.3) Removing the measuring tool: Remove the dial indicator installed on the feed chuck device and return the feed chuck device to its original stop position;

[0134] 3.4) Confirmation of rolling bearing clearance: Compare the clearance values of the rolling bearing of the feed chuck device under forward and reverse working conditions, and take the clearance under forward working condition as the standard. When the forward clearance value F1 ≥ the reverse clearance value F2, take the forward clearance as the actual measured clearance value of the rolling bearing, F1 = 0.36mm, F2 = 0.28mm, F1 ≥ F2, i.e. F = 0.36mm;

[0135] 4. Measurement and determination of thread pair wear value

[0136] Since the middle section of the three-wire screw is used most frequently when the feed chuck is running in the middle bed, the wear equivalent of this area is used as the basic value for measurement and correction, that is:

[0137] 4.1) Install measuring tools: Use two 0-300mm steel rulers, with the end surface of the threaded section of the chuck barrel of the feed chuck as the reference, align the reference with the 100mm scale line of the steel ruler, and fix them to the left and right protective covers of the middle bed respectively;

[0138] 4.2) Thread pair clearance measurement: The pitch of the three-wire screw and the copper nut is 14mm, so the measurement interval is preferably 10 to 12 rotations of the three-wire screw. That is, first start the feed rotary mechanism's quick-ejection device motor, run the feed chuck horizontally at low speed in the forward direction for 10 rotations, that is, 140mm (240mm scale mark on the steel ruler), then run the feed chuck horizontally in the reverse direction. The stop distance of the feed chuck at the time of starting is the thread pair meshing clearance value between the three-wire screw and the copper nut;

[0139] 4.3) Reading the thread pair clearance: After the chuck starts and runs horizontally in the reverse direction for 10 revolutions (approximately 140 mm), observe the error between the end face of the threaded section at the end of the chuck barrel and the 100 mm scale line on the (0-300 mm) steel ruler. This is the thread pair clearance between the three-wire lead screw and the copper nut. Read the scale values on the steel rulers on the left and right sides of the bed, respectively. This is the wear equivalent of the meshing of the feed chuck assembly and the three-wire lead screw thread pair under no-load conditions: Aleft = 3.6 mm and Aright = 4.7 mm.

[0140] 4.4) Determination of thread pair wear:

[0141] The meshing clearance Hleft between the left lead screw and the copper nut inside the left ear seat of the feed chuck device = the left thread pair clearance value Aleft - the rolling bearing clearance value of the feed chuck device F = 3.6 - 0.36 = 3.24mm.

[0142] The meshing clearance Hright between the right side lead screw and the copper nut inside the left side ear seat of the feed chuck device = the right side thread pair clearance value Aright - the rolling bearing clearance value of the feed chuck device F = 4.7 - 0.36 = 4.34 mm.

[0143] 4.5) Determination of the applicability of thread pair wear:

[0144] Taking 2 / 3 of the standard thread thickness value (2 / 3 of the pitch P value) as the criterion for judging whether the copper nut is suitable, the pitch = 14mm, 2 / 3 of the pitch P value = 9.3mm, the measured clearance values Hleft = 2.84mm, Hright = 3.04mm, both < 9.3mm, the wear amount is within the range that can be corrected for use, and the axial reference position of the copper nut can be adjusted and the synchronization accuracy of the left and right thread pairs can be corrected before continuing to use.

[0145] 5. Online motion gap correction

[0146] 5.1) Determine the wear correction equivalent of the left thread pair: Correction equivalent Ileft = left thread pair motion clearance Hleft - left screw wear Cleft = 3.24mm - 0.13mm = 3.11mm;

[0147] 5.2) Determine the wear correction equivalent of the right thread pair: Correction equivalent Iright = left thread pair motion clearance Hright - left screw wear Cright = 4.34mm - 0.16mm = 4.18mm;

[0148] 5.3) Determine the correction location: Compare the values of the correction equivalent Ileft and the correction equivalent Iright. Use the thread pair with less wear and a relatively smaller correction equivalent as the reference. Correction equivalent Ileft = 3.11mm < Correction equivalent Iright 4.18mm. Therefore, the left thread pair is the correction reference, and the right thread pair is the correction location.

[0149] 5.4) Determine the correction amount I: The absolute value of the difference between the correction equivalent Ileft (3.11mm) and the correction equivalent Iright (4.18mm) is the online correction amount, i.e., correction amount I = 4.18 - 3.11mm = 1.07mm. By axially shifting the copper nut's mounting position, the synchronization error between the copper nut and the three-wire lead screw during positive horizontal displacement is corrected.

[0150] 5.5) Preparation and Processing of Gaskets: Based on the measured correction equivalent, a semi-annular gasket is manufactured according to the shape of the copper nut end face shoulder. The gasket material is copper sheet. The gasket thickness should not exceed the measured correction equivalent and should not be less than 10-20% of the measured correction equivalent I left or I right. Correction equivalent I left = 3.11mm, correction equivalent I right = 4.18mm, correction amount I = 1.07mm. Use copper sheet with a thickness of 1.0mm to prepare the semi-annular gasket, which meets the above-mentioned relevant parameter requirements.

[0151] 5.6) Correction and compensation: Using the copper nut on the side with less wear as a reference, first remove the fastening screws on the copper nut end face with more wear on the feed chuck assembly. Then, inching the feed chuck in the reverse horizontal direction at a low speed (the screw rotation amount should not exceed 1 turn). Then, install the prepared 1.0mm thick gasket between the shoulder of the split copper nut with more wear and the end face of the feed chuck ear seat. Install and pre-tighten the screws. Now, inching the feed chuck in the forward horizontal direction at a low speed (the screw rotation amount should not exceed 1 turn), and then tighten the copper nut screws.

[0152] 6. Reset and debugging of the intermediate bed mechanism:

[0153] 6.1 The synchronization error between the left and right three-wire feed screws and the copper nut thread pair of the feed chuck assembly was verified using a steel ruler scale method. The measured reading of the scale on the left side of the feed chuck assembly under no-load conditions was 103.6 mm, and the reading on the right side was 103.8 mm. The error between the two was less than 1 mm, which met the technical requirements.

[0154] 6.2 Install the feed chuck tube guide sleeve, copper nut end protective cover, etc. and deliver it to the manufacturer for use.

[0155] Example 2

[0156] According to the specifications of rolled products LG-150H two-roller cyclic seamless steel pipe cold rolling mill, three-wire lead screw pitch = 14mm, bed length B = 12520mm, front and rear movable center frame cumulative total length D1 = 600mm, D2 = 600mm, front and rear couplings and other devices in the bed total length D3 = 520mm, D4 = 1240mm, correction coefficient t1 = 160mm. Taking the equipment maintenance work before seamless steel pipe as an example, the on-site precision correction of the motion clearance of the feed chuck device of the intermediate bed mechanism is carried out. The operation steps include:

[0157] 1. Preparation

[0158] 1.1. Remove the tubes, mandrels and other items in the intermediate bed mechanism and rolling mechanism, clean the upper box of the feed chuck device and the threaded section of the three-wire screw (free of impurities and oil stains), and confirm that the feed chuck device is stopped at the stop position in the intermediate bed (the feed chuck is stopped at the middle of the intermediate bed support seat slightly close to the end position, and the distance t2 from the copper nut end protective cover to the measuring point in the middle of the three-wire screw is preferably 250-300mm);

[0159] 1.2. Remove the tube guide sleeve at the end of the chuck cylinder of the feed chuck device and clean the end face of the guide sleeve (free of impurities and oil stains); remove the nut protective cover on the outside of the copper nuts on both sides of the feed chuck device, and clean the copper nuts and their screw meshing parts (free of impurities and oil stains).

[0160] 2. Measurement and determination of three-wire screw wear value:

[0161] 2.1. Determine the effective stroke length L of the feed chuck's horizontal reciprocating motion in the middle bed: L = middle bed support (bed length B - total length of the front and rear movable center frames in the bed D1, D2 - total length of the front and rear couplings and other devices in the bed D3, D4) = 12520 - 600 - 600 - 520 - 1240 = 9560 mm;

[0162] 2.2. Determine the measured length L1 of the three lead screws (left and right lead screws) above the middle bed: L1 = effective stroke length L of the feed chuck in the middle bed - feed chuck length correction factor t1, t1 = 160mm. L1 = 9560 - 160 = 9400mm;

[0163] 2.3. Select the measuring position: Use the three-segment method. According to the measuring length of the three-wire screw, determine the three measuring positions (C1, C2, and C3) at the beginning, middle, and end in the horizontal running direction of the feed chuck. Among them, C1 = the measuring length of the screw at the beginning + 100mm = 0 + 100 = 100mm, C2 = the measuring length of the screw at the middle = 9400 / 2 = 4700mm, and C3 = the measuring length of the screw at the end - 100mm = 9400 - 100 = 9300mm.

[0164] 2.4. Measurement of the wear value of the left side screw: Use a national standard 1-16mm tooth thickness caliper to measure the three-wire screw on the left side of the bed, and select the starting end C1 left, the middle part C2 left, and the end part C3 left; measure three consecutive trapezoidal threads before and after the measuring station, and use the average method to determine the wear value of the three measuring points respectively, C1 left = 0.12mm, middle part C2 left = 0.18mm, and end part C3 left = 0.14mm. Finally, the average wear value of the left side screw is determined, that is, C left = (C1 left + C2 left + C3 left) / 3 = (0.12 + 0.18 + 0.14) / 3 = 0.15mm;

[0165] 2.5. Measurement of right side screw wear: Use a national standard 1-16mm tooth thickness caliper to measure the right side screw in the bed, and select the starting end C1 right, the middle part C2 right, and the end part C3 right; measure three consecutive trapezoidal threads before and after the measuring station, record the readings, and use the average method to determine the wear of the three measuring points, C1 right = 0.14mm, middle part C2 right = 0.23mm, and end part C3 = 0.16mm right. Finally, determine the average wear value of the right side screw, that is, C right = (C1 right + C2 right + C3 right) / 3 = (0.14 + 0.23 + 0.16) / 3 = 0.18mm;

[0166] 3. Measurement and determination of rolling bearing wear value

[0167] 3.1) Install the measuring tool: Use a dial indicator to measure the axial clearance between the two sets of rolling bearings in the front and rear of the feed chuck. First, fix the magnet holder of the dial indicator bracket to the middle of the upper housing of the feed chuck, with the centerline of the magnet holder aligned with the axis of the feed chuck. Align the dial indicator probe with the end face of the threaded section at the end of the feed chuck barrel (where the tube guide sleeve was originally installed).

[0168] 3.2) Online Gap Measurement: First, start the motor of the quick-ejection device of the feed rotary mechanism, run the feed chuck horizontally in the forward direction at a low speed for 200 to 350 mm, preferably 250 to 300 mm, and read and record the reading on the dial indicator. This reading is the actual measured gap value F1 of the rolling bearing when the feed chuck is running in the forward direction, which is 0.36 mm. Then, start the motor of the quick-ejection device of the feed rotary mechanism again, run the feed chuck horizontally in the reverse direction at a low speed for 200 to 350 mm, preferably 250 to 300 mm, and read and record the reading on the dial indicator. This reading is the actual measured gap value F2 of the rolling bearing when the feed chuck is running in the reverse direction, which is 0.40 mm.

[0169] 3.3) Removing the measuring tool: Remove the dial indicator installed on the feed chuck device and return the feed chuck device to its original stop position;

[0170] 3.4) Confirmation of rolling bearing clearance: Compare the clearance values of the rolling bearing of the feed chuck device under forward and reverse working conditions, with the clearance under forward working condition as the standard. When the forward clearance F1 is less than the reverse clearance value F2, the average of the sum of the forward clearance and the reverse clearance is the actual measured rolling bearing clearance value F, F = (F1 + F2) / 2 = (0.36 + 0.40) / 2 = 0.38 mm;

[0171] 4. Measurement and determination of thread pair wear value:

[0172] Since the middle section of the three-wire screw is used most frequently when the feed chuck is running in the middle bed, the wear equivalent of this area is used as the basic value for measurement and correction, that is:

[0173] 4.1) Install measuring tools: Use two 0-300mm steel rulers, with the end face of the threaded section of the chuck cylinder of the feed chuck device as the reference, align the reference with the 100mm scale line of the steel ruler, and fix them on the left and right sides of the protective cover of the middle bed respectively.

[0174] 4.2) Thread pair clearance measurement: The pitch of the three-wire screw and the copper nut is 14mm, so the measurement range is preferably 10 to 12 rotations of the three-wire screw. That is: first start the motor of the feed rotary mechanism's quick exit device, run the feed chuck horizontally at low speed in the forward direction for 10 rotations, that is, 140mm (240mm scale line on the steel ruler), and then run the feed chuck horizontally in the reverse direction. At this time, the stagnation distance of the feed chuck when it starts is the thread pair meshing clearance value between the three-wire screw and the copper nut.

[0175] 4.3) Reading the thread pair clearance value: After starting the chuck and running it horizontally in the reverse direction for 10 revolutions (about 140mm), observe the error between the end face of the threaded section at the end of the chuck barrel and the 100mm scale line on the 0-300mm steel ruler. This is the thread pair engagement clearance value between the three-wire lead screw and the copper nut. Read the (scale value) parameters of the steel ruler on the left and right sides of the bed respectively. This is the wear equivalent of the feed chuck device and the three-wire lead screw thread pair after engagement under no-load conditions. Aleft = 3.5mm and Aright = 4.6mm.

[0176] 4.4) Determination of thread pair wear:

[0177] The meshing clearance Hleft between the left lead screw and the copper nut inside the left ear seat of the feed chuck device = the left thread pair clearance value Aleft - the rolling bearing clearance value of the feed chuck device F = 3.5 - 0.38 = 3.12 mm.

[0178] The meshing clearance Hright between the right lead screw and the copper nut in the left ear seat of the feed chuck device = the right thread pair clearance value Aright - the rolling bearing clearance value of the feed chuck device F = 4.6 - 0.38 = 4.22mm;

[0179] 4.5) Determination of the applicability of thread pair wear:

[0180] Taking 2 / 3 of the standard thread thickness value (2 / 3 of the pitch P value) as the criterion for judging whether the copper nut is suitable, the pitch = 14mm, 2 / 3 of the pitch P value = 9.3mm, the measured clearance values Hleft = 3.12mm, Hright = 4.22mm, both < 9.3mm, the wear amount is within the range that can be corrected for use, and the axial reference position of the copper nut can be adjusted and the synchronization accuracy of the left and right thread pairs can be corrected before continuing to use.

[0181] 5. Online motion gap correction

[0182] 5.1) Determine the wear correction equivalent of the left thread pair: Correction equivalent Ileft = left thread pair motion clearance Hleft - left screw wear Cleft = 3.12mm - 0.15mm = 2.97mm.

[0183] 5.2) Determine the wear correction equivalent of the right thread pair: Correction equivalent Iright = left thread pair motion clearance Hright - left screw wear Cright = 4.22mm - 0.18mm = 4.04mm;

[0184] 5.3) Determine the correction location: Compare the values of the correction equivalent Ileft and the correction equivalent Iright. Use the thread pair with less wear and a relatively smaller correction equivalent as the reference. Correction equivalent Ileft = 2.97mm < Correction equivalent Iright 4.04mm. Therefore, the left thread pair is the correction reference, and the right thread pair is the correction location.

[0185] 5.4) Determine the correction amount I: The absolute value of the difference between the correction equivalent Ileft (2.97mm) and the correction equivalent Iright (4.04mm) is the online correction amount, i.e., correction amount I = 4.04 - 2.97mm = 1.07mm. By axially shifting the copper nut's mounting position, the synchronization error between the copper nut and the three-wire lead screw during positive horizontal displacement is corrected.

[0186] 5.5) Preparation and Processing of Gaskets: Based on the measured correction equivalent, a semi-annular gasket is processed according to the shape of the copper nut end face shoulder. The gasket material is copper sheet. The gasket thickness should not exceed the measured correction equivalent and should not be less than 10-20% of the measured correction equivalent I left or I right. Correction equivalent I left = 2.97mm, correction equivalent I right = 4.07mm, correction amount I = 1.07mm. Use copper sheet with a thickness of 1.0mm to prepare the semi-annular gasket, which meets the above-mentioned relevant parameter requirements.

[0187] 5.6) Correction and compensation work: Taking the copper nut on the side with less wear as the reference, first remove the fastening screws of the copper nut end face with more wear on the feed chuck device, then move the feed chuck in the reverse horizontal direction at a low speed (the screw rotation amount is not more than 1 circle), and then install the prepared 1.0mm thick gasket in the area between the split copper nut shoulder with more wear and the end face of the feed chuck ear seat, install and pre-tighten the screws, at this time move the feed chuck in the forward horizontal direction at a low speed (the screw rotation amount is not more than 1 circle), and then tighten the copper nut screws.

[0188] 6. Reset and debugging of the intermediate bed mechanism:

[0189] 6.1) Use a steel ruler to verify the synchronization error between the left and right feed screws and the copper nut thread pair of the feed chuck assembly. The measured reading on the left scale of the feed chuck assembly under no-load conditions is 103.6 mm, and the reading on the right scale is 104.0 mm. The error between the two is less than 1 mm, meeting the technical requirements.

[0190] 6.2) Install the feed chuck tube guide sleeve, copper nut end protection cover, etc. and deliver it to the manufacturer for use.

[0191] Example 3

[0192] According to the specifications of rolled products LG-110H two-roller cyclic seamless steel pipe cold rolling mill, three-wire lead screw pitch = 12mm, bed length B = 10470mm, front and rear movable center frame cumulative total length D1 = 560mm, D2 = 560mm, front and rear couplings and other devices in the bed total length D3 = 490mm, D4 = 1180mm, correction coefficient t1 = 140mm. Taking the equipment maintenance work before seamless steel pipe as an example, the on-site precision correction of the motion clearance of the feed chuck device of the intermediate bed mechanism is carried out. The operation steps include:

[0193] 1. Preparation

[0194] 1.1. Remove the tubes, mandrels and other items in the intermediate bed mechanism and rolling mechanism, clean the upper box of the feed chuck device and the threaded section of the three-wire screw (free of impurities and oil stains), and confirm that the feed chuck device is stopped at the stop position in the intermediate bed (the feed chuck is stopped at the middle of the intermediate bed support seat slightly close to the end position, and the distance t2 from the copper nut end protective cover to the measuring point in the middle of the three-wire screw is preferably 250-300mm);

[0195] 1.2. Remove the tube guide sleeve at the end of the chuck cylinder of the feed chuck device and clean the end surface of the guide sleeve (no impurities or oil stains); remove the nut protective covers on the outside of the copper nuts on both sides of the feed chuck device, and clean the copper nuts and the screw meshing parts (no impurities or oil stains);

[0196] 2. Measurement and determination of three-wire screw wear value

[0197] 2.1. Determine the effective stroke length L of the feed chuck's horizontal reciprocating motion in the middle bed: L = (bed length B - total length of the front and rear movable center frames in the bed D1, D2 - total length of the front and rear couplings and other devices in the bed D3, D4) = 10470 - 560 - 560 - 490 - 1190 = 7670 mm;

[0198] 2.2. Determine the measured length L1 of the three lead screws (left and right lead screws) above the middle bed: L1 = effective stroke length L of the feed chuck in the middle bed - feed chuck length correction factor t1, t1 = 140mm. L1 = 7670 - 140 = 7530mm;

[0199] 2.3. Select the measuring position: Use the three-segment method. According to the measuring length of the three-wire screw, determine the three measuring positions (C1, C2, and C3) at the beginning, middle, and end in the horizontal running direction of the feed chuck. Among them, C1 = the measuring length of the screw at the beginning + 100mm = 0 + 100 = 100mm, C2 = the measuring length of the screw at the middle = 7530 / 2 = 3765mm, and C3 = the measuring length of the screw at the end - 100mm = 7670 - 100 = 7570mm.

[0200] 2.4. Measurement of the wear value of the left side screw: Use a national standard 1-16mm tooth thickness caliper to measure the left side screw in the bed, and select the starting end C1 left, the middle part C2 left, and the end part C3 left; measure three consecutive trapezoidal threads before and after the measuring station, and use the average method to determine the wear value of the three measuring points respectively, C1 left = 0.15mm, middle part C2 left = 0.20mm, and end part C3 left = 0.13mm. Finally, the average wear value of the left side screw is determined, that is, C left = (C1 left + C2 left + C3 left) / 3 = (0.15+0.20+0.13) / 3 = 0.16mm;

[0201] 2.5. Measurement of the wear value of the right side screw: Use the national standard 1~16mm tooth thickness caliper to measure the right side screw in the bed, and select the head end C1 right, middle C2 right, and end C3 right; measure three consecutive trapezoidal threads before and after the measuring station, record the readings and use the average method to determine the wear value of the three measuring points, C1 right = 0.12mm, middle C2 right = 0.18mm, end C3 = 0.12mm right. Finally, determine the average wear value of the right side screw, that is, C right = (C1 right + C2 right + C3 right) / 3 = (0.12+0.18+0.12) / 3 = 0.14mm.

[0202] 3. Measurement and determination of rolling bearing wear value

[0203] 3.1) Install the measuring tool: Use a dial indicator to measure the axial clearance between the two sets of rolling bearings in front and behind the feed chuck device. First, fix the magnet seat of the dial indicator bracket in the middle of the upper box of the feed chuck device. The center line of the magnet seat coincides with the axis of the feed chuck. Align the dial indicator probe with the end face of the threaded section at the end of the feed chuck cylinder (originally installed with the tube guide sleeve).

[0204] 3.2) Online Gap Measurement: First, start the motor of the quick-ejection device of the feed rotary mechanism, run the feed chuck horizontally in the forward direction at a low speed for 200 to 350 mm, preferably 250 to 300 mm, and read and record the reading on the dial indicator. This reading is the actual measured gap value F1 of the rolling bearing when the feed chuck is running in the forward direction, which is 0.32 mm. Then, start the motor of the quick-ejection device of the feed rotary mechanism again, run the feed chuck horizontally in the reverse direction at a low speed for 200 to 350 mm, preferably 250 to 300 mm, and read and record the reading on the dial indicator. This reading is the actual measured gap value F2 of the rolling bearing when the feed chuck is running in the reverse direction, which is 0.30 mm.

[0205] 3.3) Removing the measuring tool: Remove the dial indicator installed on the feed chuck device and return the feed chuck device to its original stop position;

[0206] 3.4) Confirmation of rolling bearing clearance: Compare the clearance values of the rolling bearing of the feed chuck device under forward and reverse working conditions, and take the clearance under forward working condition as the standard. When the forward clearance value F1 ≥ the reverse clearance value F2, take the forward clearance as the actual measured clearance value of the rolling bearing, F1 = 0.32mm, F2 = 0.30mm, F1 ≥ F2, that is, F = 0.32mm.

[0207] 4. Measurement and determination of thread pair wear value

[0208] Since the middle section of the three-wire screw is used most frequently when the feed chuck is running in the middle bed, the wear equivalent of this area is used as the basic value for measurement and correction, that is:

[0209] 4.1) Install measuring tools: Use two 0-300mm steel rulers, with the end surface of the threaded section of the chuck barrel of the feed chuck as the reference, align the reference with the 100mm scale line of the steel ruler, and fix them to the left and right protective covers of the middle bed respectively;

[0210] 4.2) Thread pair clearance measurement: The pitch of the three-wire screw and the copper nut is 12mm, so the measurement interval is preferably 10 to 12 rotations of the three-wire screw. That is, first start the feed rotary mechanism's quick-ejection device motor, run the feed chuck horizontally at low speed in the forward direction for 10 rotations, that is, 120mm (220mm scale line on the steel ruler), then run the feed chuck horizontally in the reverse direction. The stop distance of the feed chuck at the time of starting is the thread pair meshing clearance value between the three-wire screw and the copper nut;

[0211] 4.3) Reading the thread pair clearance: After the chuck starts and runs horizontally in the reverse direction for 10 revolutions (approximately 120 mm), observe the error between the end face of the threaded section at the end of the chuck barrel and the 100 mm scale line on the 0-300 mm steel ruler. This is the thread pair clearance between the three-wire lead screw and the copper nut. Read the scale values on the steel rulers on the left and right sides of the bed, respectively. This is the wear equivalent of the meshing of the feed chuck assembly and the three-wire lead screw thread pair under no-load conditions: Aleft = 3.7 mm and Aright = 2.8 mm.

[0212] 4.4) Determination of thread pair wear:

[0213] The meshing clearance H left between the left lead screw and the copper nut in the left ear seat of the feed chuck device = the left thread pair clearance value A left - the rolling bearing clearance value of the feed chuck device F = 3.7 - 0.32 = 3.38 mm;

[0214] The meshing clearance Hright between the right side lead screw and the copper nut in the left ear seat of the feed chuck device = the right side thread pair clearance value Aright - the rolling bearing clearance value of the feed chuck device F = 2.8 - 0.32 = 2.48mm;

[0215] 4.5) Determination of the applicability of thread pair wear:

[0216] Taking 2 / 3 of the standard thread thickness value (2 / 3 of the pitch P value) as the criterion for judging whether the copper nut is suitable, the pitch = 12mm, 2 / 3 of the pitch P value = 9.0mm, the measured clearance values Hleft = 3.38mm, Hright = 2.48mm, both < 9.0mm, the wear amount is within the range that can be corrected for use, and the axial reference position of the copper nut can be adjusted to correct the synchronization accuracy of the left and right thread pairs before continuing to use.

[0217] 5. Online motion gap correction

[0218] 5.1) Determine the wear correction equivalent of the left thread pair: Correction equivalent Ileft = left thread pair motion clearance Hleft - left screw wear Cleft = 3.38mm - 0.16mm = 3.22mm;

[0219] 5.2) Determine the wear correction equivalent of the right thread pair: Correction equivalent Iright = left thread pair motion clearance Hright - left screw wear Cright = 2.48mm - 0.14mm = 2.34mm;

[0220] 5.3) Determine the correction location: Compare the values of the correction equivalent Ileft and the correction equivalent Iright. Use the thread pair with less wear and a relatively smaller correction equivalent as the reference. Correction equivalent Ileft = 3.22mm > Correction equivalent Iright 2.34mm. Therefore, the right thread pair is the correction reference, and the left thread pair is the correction location.

[0221] 5.4) Determine the correction amount I: The absolute value of the difference between the correction equivalent Ileft (3.22mm) and the correction equivalent Iright (2.34mm) is the online correction amount, i.e., correction amount I = 3.22 - 2.34mm = 0.88mm. By axially shifting the copper nut's mounting position, the synchronization error between the copper nut and the three-wire lead screw during positive horizontal displacement is corrected.

[0222] 5.5) Preparation and Processing of Gaskets: Based on the measured correction equivalent, semi-annular gaskets are manufactured according to the shape of the copper nut end face shoulder. The gasket material is copper sheet. The gasket thickness should not exceed the measured correction equivalent and should not be less than 10-20% of the measured correction equivalent Ileft or Iright. Correction equivalent Ileft = 3.22mm, correction equivalent Iright = 2.34mm, and correction amount I = 0.88mm. Semi-annular gaskets are made of copper sheet with thicknesses of 0.5mm and 0.30mm, respectively, meeting the above-mentioned relevant parameter requirements.

[0223] 5.6) Correction and compensation work: Taking the copper nut on the side with less wear as the reference, first remove the fastening screws of the copper nut end face with more wear on the feed chuck device, then move the feed chuck in the reverse horizontal direction at a low speed (the screw rotation amount is not more than 1 circle), and then stack the prepared 0.5mm and 0.3mm thickness gaskets and install them in the area between the split copper nut shoulder with more wear and the end face of the feed chuck ear seat, install and pre-tighten the screws, at this time move the feed chuck in the forward horizontal direction at a low speed (the screw rotation amount is not more than 1 circle), and then tighten the copper nut screws.

[0224] 6. Resetting and debugging of the intermediate bed mechanism

[0225] 6.1 Use the steel ruler scale method to check the synchronization error value of the left and right feed screws and the copper nut thread pair of the feed chuck device; the measured scale reading on the left side of the feed chuck device under no-load conditions is 103.1mm, and the scale reading on the right side is 102.8mm. The error between the two is less than 1mm, which meets the technical requirements;

[0226] 6.2 Install the feed chuck tube guide sleeve, copper nut end protective cover, etc. and deliver it to the manufacturer for use.

[0227] The method of the present invention fully utilizes Newton's third law of motion (the law of action and reaction) to achieve the measurement and precision trimming of the wear clearance between the feed chuck assembly and the three-wire lead screw trapezoidal thread of the intermediate bed mechanism of a seamless steel tube cold rolling mill under non-disassembly conditions. Based on the operating characteristics of the feed chuck assembly and its thread pair, an online precision measurement and gap correction compensation method is adopted, and calculation models are set separately to achieve standardized operations. The operation process is quantified and controllable, saving labor and time, reducing labor intensity, and reducing dependence on personnel skills and experience. The process design is reasonable, the process is compact and smooth, the calculation and measurement are convenient, and the one-time pass rate of the precision trimming operation reaches 100%. After the online precision measurement and correction operation, the synchronization error of the thread pairs on the left and right sides of the feed chuck assembly is ≤1.0mm, providing data for deterioration tendency analysis of the thread pair components, promoting the functional precision of the equipment, and achieving continuous stability of the feed chuck assembly operation from the source, meeting the technical requirements of the cold rolling production of high-end seamless steel tubes such as nickel-based alloys, high-temperature alloys, and duplex stainless steel.

Claims

1. A method for correcting the motion synchronization accuracy of the feed chuck device of a seamless steel tube cold rolling mill, characterized in that: The steps include: 1) Preparation Remove the tube blanks and mandrels in the middle bed and rolling mechanism, clean the upper box of the feed chuck device and the threaded section of the three-wire lead screw, and confirm that the feed chuck device is stopped at the middle bed; remove the tube blank guide sleeve at the end of the chuck cylinder of the feed chuck device and the nut protective covers on the outside of the copper nuts on both sides of the feed chuck device; 2) Measurement and determination of screw wear value 2.1 Determine the effective stroke length L of the feed chuck's horizontal reciprocating motion in the middle bed, L = bed length B - (front movable center frame length D1 + rear movable center frame length D2 + front coupling length D3 + rear coupling length D4); 2.2 Determine the measured length L1 of the three lead screws above the middle bed, i.e. the left and right lead screws. L1 = the effective stroke length L of the feed chuck in the middle bed - the feed chuck length correction factor t1. The value of t1 is determined according to the feed chuck length of the cold rolling mill and the length of the copper threaded end face protective cover of different models and specifications. t1 is 120~200mm. 2.3 Select the measuring position: Use the three-segment method, according to the measuring length of the three-wire screw, and determine the three measuring positions C1, C2, and C3 of the head end, middle part, and end part in the horizontal running direction of the feed chuck. C1 = screw measuring length start point + 100mm, C2 = screw measuring length midpoint, C3 = screw measuring length end point - 100mm; 2.4 Measurement of left side screw wear: Use a national standard 1~16mm tooth thickness caliper to measure the left side screw in the bed, and select the head end C1 left, the middle part C2 left, and the end part C3 left. To measure the screw, cut three continuous trapezoidal threads at the front end, rear end, and middle part of the screw for actual measurement. Use the mean method to determine the wear of the three measuring points. Finally, determine the mean wear value of the left side screw, that is, C left = (C1 left + C2 left + C3 left) / 3. 2.5 Measurement of right side screw wear: Use a national standard 1~16mm tooth thickness caliper to measure the right side screw in the bed, and select the head end C1 right, the middle part C2 right, and the end part C3 right. To measure the screw, cut off three continuous trapezoidal threads at the front end, rear end, and middle part of the screw for actual measurement, record the readings, and use the average method to determine the wear of the three measuring points. Finally, determine the average wear value of the right side screw, that is, C right = (C1 right + C2 right + C3 right) / 3. 3) Measurement and determination of rolling bearing wear value 3.1 Use a dial indicator to measure the axial clearance between the front and rear rolling bearings in the feed chuck assembly. First, secure the magnet holder of the dial indicator bracket to the middle of the upper housing of the feed chuck assembly, aligning the centerline of the magnet holder with the axis of the feed chuck. Align the dial indicator probe with the end face of the threaded section at the end of the feed chuck barrel. 3.2 Online clearance measurement: First, start the motor of the quick-ejection device of the feed rotary mechanism, run the feed chuck horizontally in the forward direction at low speed for 200-350 mm, and read and record the reading on the dial indicator. This reading is the actual measured clearance value F1 of the rolling bearing when the feed chuck is running in the forward direction. Start the motor of the quick-ejection device of the feed rotary mechanism again, run the feed chuck horizontally in the reverse direction at low speed for 200-350 mm, and read and record the reading on the dial indicator. This reading is the actual measured clearance value F2 of the rolling bearing when the feed chuck is running in the reverse direction. 3.3 Remove the dial indicator installed on the feed chuck device and return the feed chuck device to its original stop position; 3.4 Confirmation of rolling bearing clearance: Compare the clearance values of the rolling bearing of the feed chuck device under forward and reverse working conditions, and take the clearance under forward working condition as the standard. If the forward clearance value F1 ≥ the reverse clearance value F2, the forward clearance shall be the actual measured clearance value of the rolling bearing; if the forward clearance value F1 < the reverse clearance value F2, the average of the sum of the forward clearance value and the reverse clearance value shall be the actual measured clearance value F of the rolling bearing, F = (F1 + F2) / 2; 4) Measurement and determination of thread pair wear value The wear equivalent of the middle section of the three-wire screw is used as the basic value for measurement and correction; 4.1 Use the end surface of the threaded section of the chuck cylinder of the feed chuck device as the reference, align the reference with the 100mm scale line of the steel ruler, and fix them on the protective covers on the left and right sides of the middle bed respectively; 4.2 Thread pair clearance measurement: This is used to measure clearance values within the pitch range of 6 to 16 mm. The measurement interval is 10 to 12 screw rotations. That is, first start the motor of the feed rotary mechanism's quick-ejection device, run the feed chuck horizontally at low speed in the forward direction for 140 to 168 mm, which is the 240 to 268 mm scale line on the steel ruler. Then, run the feed chuck horizontally in the reverse direction. The stagnation distance of the feed chuck at the time of start-up is the thread pair meshing clearance value between the three-wire lead screw and the copper nut. 4.3 Reading the thread pair clearance: After the feed chuck starts running horizontally in the reverse direction at low speed for 140-168 mm, observe the error between the end face of the threaded section at the end of the chuck barrel and the 100 mm scale line on the steel ruler. This is the thread pair meshing clearance between the three-wire lead screw and the copper nut. Read the scale value parameters of the steel ruler on the left and right sides of the bed respectively. This is the wear equivalent A left and A right of the feed chuck after the three-wire lead screw thread pair is engaged under no-load conditions. 4.4 Determination of thread pair wear: The meshing clearance H left between the left lead screw and the copper nut in the left ear seat of the feed chuck device = the left thread pair clearance value A left - the rolling bearing clearance value F of the feed chuck device; The meshing clearance Hright between the right side lead screw and the copper nut in the left ear seat of the feed chuck device = the right side thread pair clearance value Aright - the rolling bearing clearance value F of the feed chuck device; 4.5 Determination of the applicability of thread pair wear: The 2 / 3 of the standard thread thickness value, that is, 2 / 3 of the pitch P value, is used as the criterion for judging whether the copper nut is suitable for use, that is: When the measured wear value is ≥ 2 / 3 of the standard thread thickness, the copper nut can no longer be used and needs to be removed and replaced; When the measured wear value is less than 2 / 3 of the standard thread thickness value, adjust the axial reference position of the copper nut and correct the synchronization accuracy of the left and right thread pairs before continuing to use. The use cycle is proportional to the wear value and should be determined based on the actual wear value. 5) Thread pair motion synchronization accuracy correction, i.e. online motion gap correction 5.1 Determine the wear correction equivalent of the left thread pair: Correction equivalent Ileft = left thread pair motion clearance Hleft - left screw wear Cleft; 5.2 Determine the wear correction equivalent of the right thread pair: Correction equivalent Iright = left thread pair motion clearance Hright - left screw wear Cright; 5.3 Determine the correction location: Compare the values of the correction equivalent I left and the correction equivalent I right, and use the thread pair on the side with less wear and a relatively smaller correction equivalent as the reference, and the other side as the correction location; 5.4 Determine the correction amount I: The absolute value of the difference between the correction equivalent I left and the correction equivalent I right is used as the online correction amount. By axially shifting the copper nut installation position, the synchronization error correction between the copper nut and the three-wire lead screw during positive horizontal displacement is achieved; 5.5 Preparation and processing of gaskets: Based on the measured correction equivalent, a semi-annular gasket is processed according to the shape of the copper nut end face shoulder. The gasket material is copper, and the gasket thickness shall not exceed the measured correction equivalent and shall not be less than 10-20% of the measured correction equivalent I left or I right; 5.6 Correction and compensation work: Taking the copper nut on the side with less wear as the reference, first remove the fastening screws on the copper nut end face with more wear on the feed chuck device. Then, inching the feed chuck in the reverse horizontal direction at a low speed, that is, the screw rotation amount is not more than 1 circle. Then, install the prepared gasket in the area between the split copper nut shoulder with more wear and the end face of the feed chuck ear seat. Install and pre-tighten the screws. At this time, inching the feed chuck in the forward horizontal direction at a low speed, that is, the screw rotation amount is not more than 1 circle, and then tighten the copper nut screws. 6) Resetting and debugging of the intermediate bed mechanism 6.1 Carry out debugging under power-on and no-load conditions, and use the steel ruler scale method to check the synchronization error value of the thread pair of the left and right feed screws and the copper nut of the feed chuck device; when the error value is less than 1mm, the synchronization of the thread pair meets the requirements and rolling production can be carried out; when the error value is ≥1mm, it means that the online correction operation is unqualified and correction and adjustment operation must be carried out again until the error value is less than 1mm; 6.2 Install the feed chuck tube guide sleeve and copper nut end protective cover and deliver them to the manufacturer for use.

2. The method for correcting the motion synchronization accuracy of the feed chuck device of a seamless steel tube cold rolling mill according to claim 1, wherein: In step 1), the feed chuck stops at the end station near the middle of the middle bed support seat, and the distance t2 from the end protective cover of the copper nut to the measuring point in the middle of the three-wire screw is 250~300mm.

3. The method for correcting the motion synchronization accuracy of the feed chuck device of a seamless steel tube cold rolling mill according to claim 1, wherein: Step 3) During the online clearance measurement, first start the motor of the quick-ejection device of the feed rotary mechanism, run the feed chuck horizontally in the forward direction at a low speed for 250-300 mm, and read and record the reading on the dial indicator. This reading is the actual measured clearance value F1 of the rolling bearing when the feed chuck is running in the forward direction. Start the motor of the quick-ejection device of the feed rotary mechanism again, run the feed chuck horizontally in the reverse direction at a low speed for 250-300 mm, and read and record the reading on the dial indicator. This reading is the actual measured clearance value F2 of the rolling bearing when the feed chuck is running in the reverse direction.

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