Method for turning and maintaining different leads of internal threads in numerical control manner at specific rotational speed of main shaft

Abstract

The invention provides a method for turning and maintaining different leads of internal threads in a numerical control manner at a specific rotational speed of a main shaft. The method comprises the following steps of at a preset rotating speed of the main shaft, turning a reference spiral line with a lead P0 on a reference workpiece from the starting point S of a tool; positioning a tool tip in the middle of the reference spiral line; rotating the main shaft to an angled position to point the tool tip to the reference spiral line; dismounting the reference workpiece and mounting a to-be-turned internal thread workpiece with the lead P, and rotating the main shaft to the angled position; providing a tool setting ruler, and enabling a positioning contact of a vernier of the tool setting ruler to be embedded in a toothed groove of the to-be-turned internal thread; pointing the tool tip to the center of a tool setting groove of the vernier, and removing the tool setting ruler; calculatingthe axial deviation distance or circumferential bias of the starting point E' of a tool needed for turning maintained and the starting point E of a tool set by a turning and maintaining program, andeliminating the bias; and operating the adjusted turning and the maintaining program. The method can achieve the tool setting when the different leads of internal threads are turned and maintained ina numerical control manner at the specific rotational speed of the main shaft, and facilitates the maintenance and tool setting of the internal threads.

Description

technical field [0001] The invention relates to the technical field of thread maintenance, in particular to a method for numerically controlled turning and repairing internal threads with different leads at a specific spindle speed. Background technique [0002] A large number of threads are processed and repaired by oil drilling technology service companies every year. Oil pipe thread repair service itself is very necessary for the drilling industry to control equipment costs. Maintenance can prolong the service life of oil pipes and save equipment investment. The technical key point of oil pipe thread repair is to machine along the original helical line of the thread, not to completely remove and reprocess. [0003] For a long time, the industry has generally used special pipe lathes to process threads. Its advantages are simple structure and strong applicability. Its disadvantages are also obvious. The labor intensity of operators is high, the working environment is poor,...

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Problems solved by technology

None of these methods can accurately find the starting point of car repair at one time, and the efficiency is low, so it is only suitable for individual car repair

[0006] 2. System special function expansion technology: The earliest domestically available materials are documents (Wang Ke, Tang Zongjun, Zhao Wenzhen. Several technical issues in pipe thread CNC machining [J]. Petroleum Machinery, 1998, 26(11): 42-43), the general idea is to increase the measurement and feedback functions on the CNC lathe equipment until the layout of the machine tool is completely changed. This method is not economical

[0008] This idea has not been widely adopted by relevant enterprises for the following reasons: Due to the characteristics of heavy load cutting, harsh working conditions, various workpiece forms and variable thread types in the oil pipe thread turning repair, the processing equipment used in this process has been determined. It has the requirements of simple structure, convenient operation, stability and reliability, and easy maintenance. However, this method complicates the structure of the equipment due to the need for additional equipment, and the cost of purchase, use, and maintenance is high. The exposure of the location increases the probability of equipment damage and failure. , reducing the stability, reliability and convenience of operation of CNC lathes, therefore, this method is unacceptable for oil companies that have a large demand for thread turning repairs

[0009] 4. Special system function technology: literature (Zhang Dewu, Gong Junyan, Zhang Hui, Zhao Haiyuan. Application of Siemens 828D in CNC pipe thread lathe for thread repair[J]. Metal Processing: Cold Working, 2015(2):71-72 ), literature (Tang Zongjun, Gu Yanling. Continued cutting of existing threads on CNC lathes [J]. Manufacturing Technology and Machine Tools, 2003 (12): 96-97), literature (Ma Bin, Yu Li. Application on pipe thread special machine [J]. CNC machine tool market, 2007 (12): 108-110) respectively introduced the application of the thread repair function provided by Siemens 828D, FAGOR and NUM systems, which can complete the relevant position calculation and coordinate The work set by the system saves some manual labor, but it does not have the ability to detect the position of the thread to be repaired. For thread repair, the characteristic parts of the thread to be repaired are different each time. Therefore, this technology It is usually necessary to install a position detection device on the CNC lathe, resulting in an increase in equipment costs; at the same time, this type of system is limited by its own functions and application range, and can only be used on CNC lathes with corresponding systems. not applicable, not of general applicability

[0010] 5. Marking zero position signal technology: literature (Cai Shanle, Ma Zhihong. CNC lathe manual thread tool setting [J]. Machine Tools and Hydraulics, 2004 (9): 177-178), literature (Meng Shengcai. Thread repair on CNC lathes Tool setting problem [J]. Electromechanical Engineering Technology, 2008, 37 (4): 100-102+112), literature (Fan Fanghong, Shi Jinyan. Discussion and application of the method of automatic positioning and repairing thread of CNC lathe spindle [J]. Manufacturing technology and Machine Tools, 2015(4):173-176) and literature (Wan Fawei, Zhao Junyou, Cao Qingyuan, Wang Futao, Cao Jianming, Han Xueyi. Research on oil drill pipe thread repair technology[J]. Machine Tool and Hydraulics, 2017,45(2) :15-19), the idea is to mark the zero signal of the spindle. This method has an insurmountable shortcoming, that is, the distance between the measuring point on the thread corresponding to the zero signal and the cutting start point is not an integer multiple of the lead, so the The calculated starting point is inaccurate and needs to be corrected, which is inherently determined by the principle of thread feed operation of the CNC machine tool

However, in actual operation, this method still has the following disadvantages: 1. The distance L1 cannot be directly obtained from the machine tool. If manual measurement is used, it is difficult to ensure the measurement accuracy of L1. If instrument measurement is used, the equipment structure will be complicated; 2. , This method also needs to detect and calculate the "rotation angle difference", but most of the CNC lathe systems in the prior art do not have the function of displaying the phase angle of the spindle, so the scope of application of this method is limited; to detect the "rotation angle difference", you need to use Testing instruments, or refitting or transforming machine tools will complicate the turning repair operation of each thread, increase cost input, and reduce work efficiency; in addition, the introduction of "rotation angle difference" complicates position calculation, cumbersome operation, low efficiency, and is applicable small range

[0013] The Chinese invention patent application with the publication number CN104148752A discloses a method for automatically extracting and eliminating deviations in CNC thread grinding tool setting and grinding. The method automatically calculates the synchronous following error of the Z axis and the A axis as the deviation, which is equivalent to The most commonly used test method for thread repairing on CNC lathes relies on the operator to visually measure the distance between the tool and the existing thread teeth, and then repeatedly adjusts and eliminates the distance. The process is relatively complicated; and most of the existing CNC lathe systems do not It has the functions of continuous multi-point and multi-dimensional collection, recording, storage and calculation of data, so it limits the scope of application of this method

In addition, this method is suitable for turning and repairing threads with the same lead, but does not give a method of how to repair threads with different leads in batches

[0014] The Chinese invention patent application with the publication number CN109799783A discloses a method, a control device and a CNC machine tool for repairing a threaded pipe body by a CNC machine tool. The method obtains the thread track data of the threaded pipe and compares it with the program data of the CNC machine tool. Calculate the data difference between the program thread and the thread to be repaired. This method belongs to the above-mentioned "thread contour scanning detection technology". It is necessary to add other systems to obtain the information mentioned in the method and simulate turning the thread, which makes the equipment complicated. ; At the same time, this method needs to obtain the angle of the CNC machine tool spindle encoder and the machine tool, which makes the whole tool setting process more complicated

In addition, this method is suitable for turning and repairing threads with the same lead, but does not give a method of how to repair threads with different leads in batches

[0015] At the same time, for the maintenance of the internal thread, since the internal thread is located in the workpiece, it is difficult to judge the relative position of the turning tool and the internal thread during tool setting, so the axial coordinates of the tooth groove of the internal thread cannot be accurately marked during tool setting, resulting in tool setting difficulty

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