Method for repairing internal thread of numerical control lathe at variable spindle rotation speeds

Abstract

The invention relates to a method for repairing an internal thread of a numerical control lathe at variable spindle rotation speeds. The method comprises the steps that with an initial point S of a tool, spiral lines T1 and T2 are turned on a reference workpiece at a spindle rotation speed n1 and a spindle rotation speed n2 respectively; a tool tip is positioned at a point A1 of the middle of T1;after a spindle is rotated to an angle position, the tool tip points at T1; the tool tip is positioned at a point A2 to point at T2 adjacent to T1; through coordinates of A1 and A2, the axial or circumferential deviation between T1 and T2 is calculated and eliminated; the reference workpiece is detached; a to-be-repaired workpiece is installed, and the spindle is rotated to the angle position; a tool setting ruler is provided, and a positioning contact on a vernier of the tool setting ruler is embedded in a toothed groove of the to-be-repaired internal thread; the tool tip is positioned at a point B and aligned with a tool setting groove in the vernier, and the tool setting ruler is removed; through coordinates of the points A1 and B, the axial deviation distance or circumferential deviation between the initial point, set by a tool repairing procedure, of the tool and the initial point of the tool required by tool repairing is calculated and eliminated, and the adjusted tool repairingprocedure is executed. The method can achieve coincidence of a turning trajectory and a trajectory of the to-be-repaired thread at the variable spindle rotation speeds.

Description

technical field [0001] The invention relates to the technical field of thread maintenance, in particular to a method for CNC turning and repairing internal threads with variable 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, and there are occupational risks such a...

AI Technical Summary

Problems solved by technology

[0004] 1. It is difficult to economically and conveniently obtain the installation position information of the existing helix of the thread to be repaired: the workpieces to be repaired in the petroleum technical service industry are very heavy, and the clamping position on the CNC lathe can only be random, which is different from the previous successful completion Program parameters for threading are independent

CNC lathes must associate the position information of the thread to be repaired with the processing program so that the tool can cut along the original thread trajectory, which is also a very inefficient repetitive labor

[0005] 2. There is a phenomenon of variable speed and chaotic teeth: when turning threads on a CNC lathe, the speed cannot be changed arbitrarily like an ordinary lathe, otherwise the threads will be randomly buckled

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 investment, and reduce work efficiency; in addition, the introduction of "rotation angle difference" complicates position calculation

Therefore, the existence of "rotation angle difference" in this method makes it cumbersome to operate, low in efficiency, and high in equipment cost, and it does not provide a method for avoiding random threads during thread maintenance

[0008] 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 line and the thread line to be repaired. This method belongs to the "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 leads to the complexity of the equipment; 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, it does not give a method on how to avoid thread disorder during thread maintenance

[0009] 3. 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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